Top 100 most referenced chemical warfare agents

[megalomania]

Chemical abstarcts is a wonderful tool. Using its subject area search feature I was able to find over 6000 journal articles about chemical warfare. Since most are irrevelant I weeded the articles down based on referenced CAS number, and then limited the search to those journals most likely to provide synthesis info. Here then are the results, about 350 articles worth:

505-60-2 (523 references)
107-44-8 (418 references)
96-64-0 (347 references)
50782-69-9 (290 references)
77-81-6 (161 references)
409-21-2 (156 references)
7732-18-5 (137 references)
756-79-6 (112 references)
51-55-8 (108 references)
7440-44-0 (96 references)
12033-89-5 (94 references)
993-13-5 (89 references)
9000-81-1 (89 references)
1344-28-1 (85 references)
81-81-2 (83 references)
541-25-3 (78 references)
311-45-5 (77 references)
34433-31-3 (74 references)
329-99-7 (73 references)
101-26-8 (70 references)
9001-08-5 (69 references)
1445-75-6 (68 references)
7782-44-7 (68 references)
1832-54-8 (67 references)
7440-70-2 (67 references)
1314-23-4 (66 references)
111-48-8 (65 references)
124-38-9 (65 references)
616-52-4 (64 references)
55-91-4 (61 references)
1832-53-7 (58 references)
7439-89-6 (53 references)
7631-86-9 (52 references)
67-56-1 (50 references)
630-08-0 (50 references)
7440-23-5 (50 references)
439-14-5 (48 references)
7440-50-8 (48 references)
693-07-2 (47 references)
75-44-5 (46 references)
7664-41-7 (46 references)
6735-59-7 (45 references)
7723-14-0 (44 references)
7440-09-7 (43 references)
7439-95-4 (41 references)
117698-12-1 (41 references)
7440-38-2 (40 references)
7727-37-9 (40 references)
64-17-5 (38 references)
7440-02-0 (37 references)

I know this is only 50 CAS numbers, the list was truncated :(

2003-April 2005

Bibliographic Information

Degradation Kinetics of VX on Concrete by Secondary Ion Mass Spectrometry. Williams, John M.; Rowland, Brad; Jeffery, Mark T.; Groenewold, Gary S.; Appelhans, Anthony D.; Gresham, Garold L.; Olson, John E. Battelle Salt Lake City Operations, West Valley City, UT, USA. Langmuir (2005), 21(6), 2386-2390. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 142:279785 AN 2005:130995 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At trace coverages on concrete surfaces, the nerve agent VX (O-Et S-2-diisopropylaminoethyl Me phosphonothiolate) degrades by cleavage of the P-S and S-C bonds, as revealed by periodic secondary ion mass spectrometry (SIMS). The obsd. kinetics were (pseudo-) first-order, with a half-life of 2-3 h at room temp. The rate increased with surface pH and temp., with an apparent second-order const. of kOH = 0.64 M-1 min-1 at 25 C and an activation energy of 50-60 kJ mol-1. These values are consistent with a degrdn. mechanism of alk. hydrolysis within the adventitious water film on the concrete surface. Degrdn. of bulk VX on concrete would proceed more slowly. Safety: VX must only be handled in approved chem. warfare surety labs. by trained agent chemists.

Bibliographic Information

The pharmacokinetics and pharmacodynamics of two HI-6 salts in swine and efficacy in the treatment of GF and soman poisoning. Lundy, Paul M.; Hill, Ira; Lecavalier, Pierre; Hamilton, Murray G.; Vair, Cory; Davidson, Corey; Weatherby, Kendal L.; Berger, Bradley J. Chemical Biological Defence Section, Defence Research and Development Canada - Suffield, Medicine Hat Alberta, AB, Can. Toxicology (2005), 208(3), 399-409. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. AN 2005:107852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anesthetized pigs were injected i.m. with 500 mg HI-6 dichloride (HI-6 2Cl) (1-[[[4-(aminocarbonyl)-pyridinio]methoxy]methyl]-2[(hydroxyimino)methyl]pyridinium dichloride; CAS 34433-31-3)) or the molar equivalent of HI-6 dimethanesulfonate (HI-6 DMS) 633 mg. Plasma HI-6 concns. were measured by HPLC (1, 3, 5, 10, 15, 30, 60 min and every 30 min until 4 h or 6 h following the i.v. or i.m. dose resp.) while a variety of physiol. responses were continuously examd. HI-6 (500 mg 2Cl or 633 mg DMS) resulted in an identical pharmacokinetic profile unaffected by atropine co-administration. Neither HI-6 salt resulted in clin. significant changes in cardiovascular or respiratory function. HI-6 DMS (1899 mg i.v.) resulted in plasma HI-6 concns. about 10 times higher than measured following i.m. 500 mg 2Cl or 633 mg DMS and resulted in small transitory effect on mean arterial pressure. Atropine plus HI-6 DMS (1-9 mg/kg or 127-172 mg/kg i.m.) protected up to 100% of guinea pigs exposed to 5  LD50 of GF (cyclohexyl Me phosphonoflouridate) or soman (pinacolyl methylphosphonofluoridate) (GD) resp. The results suggest that the two HI-6 salts have a similar pharmacokinetic profile while HI-6 DMS appears extremely safe and effective against nerve agents and may be as suitable for human use.

Bibliographic Information

Antidotal treatment of GF-agent intoxication in mice with bispyridinium oximes. Sevelova, Lucie; Kuca, Kamil; Krejcova-Kunesova, Gabriela. Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2005), 207(1), 1-6. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 142:213533 AN 2004:1067008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It was shown that intoxications with GF-agent are rather resistant to convential oxime therapy; therefore, the development of new oximes in an effort to improve this unsatisfactory situation continues. Upon screening in vitro reactivation test for oximes, that were either newly synthesized at our department, or those that have never been tested for reactivation of GF-inhibited acetylcholinesterase (AChE), three oximes {(1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide) (K033); (1-(2-hydroxyiminomethylpyridinium)-3-(3-carbamoylpyridinium)-2-oxa-propane dichloride) (HS-6); and (1-(2-hydroxyiminomethylpyridinium)-4-(4-carbamoylpyridinium)-but-2-ene dibromide) (BI-6)} with the highest reactivation potency were chosen for in vivo testing in our study. (1,3-Bis(4-hydroxyiminomethylpyridinium)-2-oxa-propane dibromide) (obidoxime); (1-(2-hydroxyiminomethylpyridinium)-3-(4-carbamoylpyridinium)-2-oxa-propane dichloride) (HI-6); and (1,1-bis(4-hydroxyiminomethylpyridinium)-methane dibromide) (methoxime) were chosen for comparison as a std. antidotal treatment. All the oximes were applied at the same proportion of their LD50 value (5%), and because of the different acute toxicity of the oximes, the molar concns. of their solns. for i.m. administration were considerably different. The highest therapeutic ratio was achieved for therapeutic regimen consisting of HI-6 and atropine. The significantly (P < 0.05) lowest effectivity in treatment of supralethal GF-agent poisoning in comparison with all the other therapeutic regimens, was surprisingly obsd. for methoxime. HS-6, K033 and BI-6 as well as obidoxime were comparably effective antidotes against GF-agent intoxication and their therapeutic ratios were similar.

Bibliographic Information

Bis(dialkylamide)hydrogen Dibromobromate Precursors of Hypobromite Ion in Reactions with Nerve and Blister Agent Simulants. Simanenko, Yuri S.; Savelova, Vera A.; Prokop'eva, Tatyana M.; Mikhailov, Vasily A.; Turovskaya, Marya K.; Karpichev, Eugen A.; Popov, Anatolii F.; Gillitt, Nicholas D.; Bunton, Clifford A. L.M. Litvinenko Institute of Physical Organic Coal Chemistry, National Academy of Sciences of Ukraine, Donetsk, Ukraine. Journal of Organic Chemistry (2004), 69(26), 9238-9240. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 142:108643 AN 2004:949799 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hypobromite ion, BrO-, is an effective -nucleophile that reacts rapidly with activated phosphorus(V) and sulfonate esters. The parent acid rapidly oxidizes org. sulfides and aryloxide ions. At pH 10-11 BrO- and HOBr coexist in water and are potentially useful as decontaminants of chlorosulfide blister agents and the phosphonyl nerve agents. Bis(dialkylamide)hydrogen dibromobromates are well characterized, stable, solids which rapidly form HOBr-BrO- in mildly alk. water. Reactions of 4-nitrophenyl di-Et phosphate and phosphonate, which are simulants of the phosphonofluoridate nerve agents, and of 4-nitrophenyl tosylate, with BrO- are rapid (t1/2 = 60-700 s) with 0.1 M BrO-, under conditions in which oxidns. of org. sulfides are too fast to be followed by conventional methods.

Bibliographic Information

Localization of substance P gene expression for evaluating protective countermeasures against sulfur mustard. Casbohm, Stacy L.; Rogers, James V.; Stonerock, Mindy K.; Martin, Jamie L.; Ricketts-Kaminsky, Karen M.; Babin, Michael C.; Casillas, Robert P.; Sabourin, Carol L. K. Medical Research and Evaluation Facility, Battelle Memorial Institute, Columbus, OH, USA. Toxicology (2004), 204(2-3), 229-239. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:421169 AN 2004:789078 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard [bis(2-chloroethyl)sulfide; SM] is a chem. warfare agent that produces edema and blister formation with a severe inflammatory reaction. The mouse ear vesicant model for SM injury has been used to evaluate pharmacol. agents for countering SM dermal injury. The vanilloid olvanil reduces SM-induced edema and mRNA expression of cytokines and chemokines, suggesting that blocking the inflammatory effects of neuropeptides, such as substance P (SP), may provide protection against SM-induced dermal injury. This study examd. SP expression in mice exposed to SM (0.16 mg) on the inner surface of the right ear, with or without olvanil pretreatment at 1, 10, 30, 60, and 360 min following exposure. In naive skin, SP mRNA localization was assocd. with blood vessels and sebaceous glands. In SM-exposed skin, SP mRNA was also detected in perivascular dermal cells. Immunohistochem. localization of SP protein was obsd. in the ear skin of naive, SM-, olvanil/SM-, and vehicle-treated mice. Quantification of SP+ perivascular dermal cells revealed that SM exposure led to a significant increase (P  0.05) in SP+ cells over the obsd. time period. Olvanil pretreatment significantly reduced (P  0.05) the mean no. of SP+ cells at 60 and 360 min. This study demonstrates that SP expression could provide an addnl. endpoint for evaluating the effectiveness of vanilloid drugs on SM-induced skin inflammation.

Bibliographic Information

Photocatalytic oxidation of VX simulant 2-(butylamino)ethanethiol. Vorontsov, Alexandre V.; Chen, Yi-Chuan; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russian Federation, Russia. Journal of Hazardous Materials (2004), 113(1-3), 89-95. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 141:383605 AN 2004:745354 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Photocatalytic oxidn. of 2-(butylamino)ethanethiol (BAET) was undertaken in aq. suspension of TiO2 Hombikat UV 100 and Degussa P25 under different initial reaction conditions in order to det. the best parameters for the fastest mineralization of the substrate. BAET is considered to be a simulant for the VX chem. warfare agent. The application of ultrasound had only a small pos. effect on the BAET photocatalytic degrdn. The highest mineralization rate of 0.433 mg/L-min was found in unbuffered TiO2 Degussa P25 suspension with initial pH of .apprx.9.4, TiO2 concn. 500 mg/L and the initial BAET concn. 1000 mg/L. Decreasing of the initial soln. pH to 6.1 stops the mineralization of BAET while increasing of pH to .apprx.11 drastically changed the degrdn. profile. At this initial pH, the 1st 100 min of reaction led to only oxidn. of S moiety and org. intermediates accumulated in the soln. Thereafter, mineralization of the products started. The main detected volatile product was Bu aldehyde and the main polar one was 2-(butylamino)acetic acid. In the case of TiO2 Hombikat UV 100, conversion of TOC at initial pH 11 exceeded that at initial pH 9.1. For Degussa P25, the starting pH 9.4 was the best for TOC conversion. The results can be used for the treatment of water and wastewater.

Bibliographic Information

Synthesis and Chemosensory Behavior of Anthracene Bisimide Derivatives. Ilhan, Faysal; Tyson, Daniel S.; Meador, Michael A. Polymers Branch Materials Division, NASA Glenn Research Center, Cleveland, OH, USA. Chemistry of Materials (2004), 16(16), 2978-2980. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 141:268374 AN 2004:559158 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors used the photoenolization reaction of a dibenzoyl-p-xylene deriv. to synthesize two new, highly substituted anthracene-based mols.: N,N'-bis(p-nitrophenyl)-1,5-bis(p-(tetraethyleneglycoloxy)phenyl)anthracene-2,3,6,7-tetracarboxyl bis-imide (ABI-NO2) and N,N'-bis(p-aminophenyl)-1,5-bis(p-(tetraethyleneglycoloxy)phenyl)anthracene-2,3,6,7-tetracarboxyl bis-imide (ABI-NH2). ABI-NO2 and ABI-NH2 maintained photostability with longer wavelength absorption and emission spectra as compared to unsubstituted anthracene. Conversion of the terminal nitro groups to amines created an internal photoinduced electron-transfer that quenched the luminescence of ABI-NH2. Reversible or irreversible reaction of the attached amines resulted in fluorescence recovery. Sensitivity, of ABI-NH2 and other potential derivs., to toxic chems. may prove useful for early detection systems. Electronic supplementary information (ESI) is available at http://pubs.acs.org and contains synthetic prepns. of the ABI-NO2 and ABI-NH2 compds.

Bibliographic Information

Dimethyl Methylphosphonate Decomposition on Titania-Supported Ni Clusters and Films: A Comparison of Chemical Activity on Different Ni Surfaces. Zhou, J.; Ma, S.; Kang, Y. C.; Chen, D. A. Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA. Journal of Physical Chemistry B (2004), 108(31), 11633-11644. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 141:195800 AN 2004:528273 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The thermal decompn. of di-Me methylphosphonate (DMMP) has been studied in ultrahigh vacuum by temp. programmed desorption (TPD) and XPS on Ni clusters and films deposited on TiO2(110). The four different Ni surfaces under investigation consisted of small Ni clusters (5.0  0.8 nm diam., 0.9  0.2 nm height) deposited at room temp. and quickly heated to 550 K, large Ni clusters (8.8  1.4 nm diam., 2.3  0.5 nm height) prepd. by annealing to 850 K, a 50 monolayer Ni film deposited at room temp., and a 50 monolayer Ni film annealed to 850 K. The morphologies of the Ni surfaces were characterized by scanning tunneling microscopy (STM). TPD expts. show that CO and H2 are the major gaseous products evolved from the decompn. of DMMP on all of the Ni surfaces, and mol. DMMP and methane desorption were also obsd. The product yields for CO and H2 were highest for reactions on the small Ni clusters and unannealed Ni film and lowest for reactions on the large clusters and annealed film. Furthermore, XPS expts. demonstrate that the unannealed Ni surfaces decomp. a greater fraction of DMMP at room temp. The loss of activity for the annealed surfaces is not caused by a redn. in surface area because the annealed surfaces have approx. the same surface area as the small clusters. CO adsorption studies suggest that the loss of activity upon annealing cannot be completely due to a decrease in surface defects, such as step and edge sites, and we propose that a TiOx moiety is responsible for blocking active sites on the annealed Ni surfaces. In comparison to the TiO2 surface, the small Ni clusters are more chem. active because a greater fraction of DMMP decomps. at room temp., and the total amt. of DMMP decompn. is also higher on the small Ni clusters. Although DMMP decomps. on TiO2 to produce gaseous Me radicals, methane, and H2, the activity of the substrate surface itself appears to be quenched in the presence of the Ni clusters and films.
However, the TiO2 support plays a significant role in providing a source of oxygen for the recombination of at. carbon on Ni to form CO, which desorbs above 800 K.

Bibliographic Information

Reductive Destruction of Chemical Warfare Agent Simulants in Water. Kiddle, James J.; Mezyk, Stephen P. Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA. Journal of Physical Chemistry B (2004), 108(28), 9568-9570. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 141:194628 AN 2004:479880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The efficient detection, decontamination, and destruction of chem. warfare (CW) agents remain an active area of scientific research. Rate consts. for the reaction of substituted di-Et phosphates and phosphonates with the hydroxyl radical and hydrated electron have been measured in water to elucidate the primary destruction pathway for the CW agents Tabun (GA), Sarin (GB), Soman (GD), and VX with these two species. The measured kinetics for simulants with leaving groups that more closely mimic these actual CW agents predict that reductive destruction will be the most efficient mechanism, and that nontoxic simulants such as alkyl phosphonates undergo different redox chem.

Bibliographic Information

Detect-to-warn cell based sensing technology: Chemical sensing of multiple agents in a cascade. Zhang, Xuan; Yang, Mo; Kohr, Bonnie; Morgan, Andre; Ozkan, Cengiz S. Mechanical Engineering Department, University of California, Riverside, CA, USA. Materials Research Society Symposium Proceedings (2004), EXS-1(Architecture and Application of Biomaterials and Biomolecular Materials), 187-195. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:119751 AN 2004:469459 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Techniques to develop highly sensitive biosensors are largely dependent upon the properties of the material and its assocd. interactions. A novel challenge is the development of effective biosensors based on fundamental research in biotechnol., genetics and information technol., which will change the existing axiom of "detect -to-treat" to "detect -to-warn". Current biosensor technologies encompass antibody-antigen interactions, hormone-receptor interactions, and nucleic acid based assays. These sensors are useful in narrow band applications requiring high specificity for agent identification. Mammalian cells have excitable cell membranes that function as novel sensing platforms by producing a variation in the extracellular potential based on the chem. stimulus. Here we report a method of developing single cell based sensors by integrating the biol. tool of dielectrophoresis with the micro fabrication technol. We display its ability to detect a large no. of chem. agents, reject false alarms, characterize the chem. agent functionality and det. the assocd. sensitivity limit, and the physiol. response in terms of the calcium transients for each specific chem. agent that produces synergistic effects on humans. We finally demonstrate the capability of a single cell based sensor to identify general chem. agents in cascade.

Bibliographic Information

Preparation, Derivatization with Trimethylsilyldiazomethane, and GC/MS Analysis of a "Pool" of Alkyl Methylphosphonic Acids for Use as Qualitative Standards in Support of Counterterrorism and the Chemical Weapons Convention. Crenshaw, Michael D.; Cummings, David B. Battelle Memorial Institute, Columbus, OH, USA. Phosphorus, Sulfur and Silicon and the Related Elements (2004), 179(6), 1009-1018. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 141:225604 AN 2004:460857 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

There are hundreds of nerve agents in the class of alkyl methylphosphonofluoridates covered by Schedule 1 of the CWC (Chem. Weapons Convention). Hydrolysis of these sarin-like nerve agents results in an equal no. of alkyl methylphosphonic acids. These alkyl methylphosphonic acids are persistent and provide good evidence of specific agent prodn. or use. To support the CWC and counterterrorism activities, it is desirable to have ready access to each of these hydrolysis products for use as qual. stds. A means for simultaneously producing multiple alkyl methylphosphonates from methylphosphonic acid, phenylarsonic acid and the corresponding alcs. was developed. Derivatization of these alkyl methylphosphonic acids with trimethylsilyldiazomethane yields the corresponding Me esters which are suitable for GC/MS anal.

Bibliographic Information

MBE grown AlN films on SiC for piezoelectric MEMS sensors. Doppalapudi, Dharanipal; Mlcak, Richard; Chan, Jeffrey; Tuller, Harry; Bhattacharya, Anirban; Moustakas, Theodore. Boston MicroSystems Inc., Woburn, MA, USA. Materials Research Society Symposium Proceedings (2004), 798(GaN and Related Alloys--2003), 403-408. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:132159 AN 2004:423724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Miniaturized piezoelec. sensors based on Microelectromech. Systems (MEMS) offer the advantages of reduced size, reduced power consumption, increased sensitivity coupled with the ability to form compact multi-sensor arrays. Fabrication of such sensors from single crystal materials further insure more highly reproducible and stable devices with improved performance. The authors describe the integration of MBE grown AlN films onto photoelectrochem. machined SiC microcantilevers and membranes. AlN exhibits excellent piezoelec. properties, including an electromech. coupling coeff. of 0.088 and a high in-plane acoustic velocity (.apprx.5700 m/s) as well as excellent thermal-mech. compatibility with SiC. The fabrication of AlN-SiC-based microresonators and flexural plate wave devices, and their application to chem., biol. and fluid sensing, are reported.

Bibliographic Information

Biochemical changes in mouse lung after subcutaneous injection of the sulfur mustard 2-chloroethyl 4-chlorobutyl sulfide. Elsayed, Nabil M.; Omaye, Stanley T. Hurley Consulting Associates, Department of Scientific Affairs, Chatham, NJ, USA. Toxicology (2004), 199(2-3), 195-206. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:237904 AN 2004:404473 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant-type chem. warfare agent (CWA) introduced in World War I which continues to be produced, stockpiled, and occasionally deployed by some countries, and could be used potentially by terrorists. Exposure to HD can cause erythema, blisters, corneal opacity, and airway damage. The authors have reported previously that s.c. (SC) injection of immunodeficient athymic nude mice with the half mustard Bu 2-chloroethyl sulfide (BCS) causes systemic biochem. changes in several organs distal to the exposure site. In the present study, the authors examd. the response of nonimmunodeficient Swiss Webster mice to the mustard, 2-chloroethyl 4-chlorobutyl sulfide (CECBS). In a pilot study, a single SC injection of 20-25 L/mouse caused death within 24 h. Consequently, the authors used 5 L/mouse (.apprx.0.017 mg/kg body wt.) of neat CECBS or an equal vol. of saline as control. The authors examd. lungs after 1, 24, and 48 h for biochem. changes including total and oxidized glutathione, protein, DNA, and lipid peroxidn. contents in tissue homogenate, and superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, and glutathione S-transferases activities in the cytosol. After 1 and(or) 24 h, significant changes were found that were resolved by 48 h. These changes mimicked those of HD and BCS and were generally consistent with free radical-mediated oxidative stress. The implications of these observations are 2-fold. First, dermal exposure to low-dose mustard gas could elicit systemic changes impacting distal organs such as the lungs. It also suggests that antioxidants could potentially modulate the response and reduce the damage. Second, although the use of known CWAs such as HD is prohibited, analogs that are not recognized as agents are as toxic and could be dangerous if acquired and used by potential terrorists.

Bibliographic Information

A thermo-chemical surface treatment of AlN powder for the aqueous processing of AlN ceramics. Olhero, S. M.; Novak, S.; Oliveira, M.; Krnel, K.; Kosmac, T.; Ferreira, J. M. F. Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro, Port. Journal of Materials Research (2004), 19(3), 746-751. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 141:41662 AN 2004:346050 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Dense aluminum nitride ceramics were prepd. by sintering green bodies at 1750C for 2 h. These green bodies were prepd. by aq. slip-casting from a powder that was surface-treated to prevent hydrolysis. The surface treatment of the aluminum nitride (AlN) powder consisted of dispersing the powder in warm-water solns. of aluminum dihydrogenphosphate Al(H2PO4)3. Different treatment temps. in the range 30-80C were tested. For all the tested temps., the surface-treated AlN powder was found to be water-resistant, even after drying and/or redispersion. Various com. dispersants were tested for their effectiveness, and the amt. of dispersant was optimized in terms of a high solids loading of the suspension and an acceptable viscosity for slip casting. Based on these studies, a stable aq. suspension of AlN powder, treated at 60C, with a total solids loading of 50 vol%, was prepd. using CaF2 as a sintering additive. The well-dispersed powder made it possible to prep. green samples with close particle packing and relatively high sintered densities, i.e., >96%.

Bibliographic Information

Progress in developing nerve agent sensors using combinatorial techniques. DiCesare, John C.; Parker, Jennifer; Horne, Starr N.; Kita, Justin; Earni, Raghu; Peeples, Christopher. Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK, USA. Materials Research Society Symposium Proceedings (2004), Volume Date 2003, 787(Molecularly Imprinted Materials--2003), 17-22. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:201377 AN 2004:280892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Development of a sensor capable of selective detection of specific nerve agents is imperative in today's atm. of terrorism. The sensor needs to be inexpensive, portable, reliable, absent of false positives and available to all military and first responders. By utilizing the techniques of mol. imprinting, combinatorial chem., silica sol-gel synthesis and lanthanide luminescence, a sensor for the detection of the hydrolysis product of the nerve agent soman is being developed. There are many parameters that require investigation in order for the sensor to become a reality. These parameters include (1) the selection of a chelate that can bind to the lanthanide and anchor the nerve agent simulant during the formation of the molecularly imprinted polymer, (2) the detn. of the environment best suited for this complex formation, (3) the formation, as well as modification of the silica sol-gel for mol. imprinting to take place, and (4) the proper quantity and ratios of monomers used to create the three dimensional imprint. Key to the success of optimizing these parameters is the development of a combinatorial assay that allows for the synthesis and testing of tens of thousands of combinations of parameters. Work on the development of the combinatorial assay has lead to a method of prepg. thin film polymers capable of analyzing the presence of nerve agent simulants. Current work is underway to validate the combinatorial assay and to synthesize and evaluate a library of sensor materials selective for nerve agents.

Bibliographic Information

Synthesis and adsorption properties of intimately intermingled mixed metal oxide nanoparticles. Medine, Gavin M.; Zaikovskii, Vladimir; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2004), 14(4), 757-763. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 140:359698 AN 2004:131545 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A series of intimately intermingled mixed metal oxide nanoparticles were prepd. via a modified aerogel procedure (MAP). These mixed oxides were composed of alk. earth oxides and aluminas. It was found that the surface area and reactivity of these materials decreased on going from magnesium to barium in these intimately intermingled metal oxides. The samples were analyzed by HRTEM and the images obtained illustrate the degree of mixing throughout each of the intermingled mixed metal oxides. As well as synthesizing and characterizing these samples, standardized adsorption tests were also carried out and compared to those of individual metal oxide nanoparticles and phys. mixts. of metal oxide nanoparticles. The following tests have been shown to be effective in detg. the adsorption properties of metal oxide nanoparticles: (i) destructive adsorption of paraoxon (a surrogate of the chem. warfare nerve agent, VX) and (ii) the adsorption of acid gases. The data clearly show enhanced kinetics and capacities for the intermingled AP-MgAl2O4 and indeed, the data suggest that surface reactivities can be tailored by the aerogel mixing process.

Bibliographic Information

Examination of changes in connective tissue macromolecular components of large white pig skin following application of Lewisite vapour. Lindsay, Christopher D.; Hambrook, Joy L.; Brown, Roger F. R.; Platt, Jan C.; Knight, Robert; Rice, Paul. Biomedical Sciences Department, Salisbury, UK. Journal of Applied Toxicology (2004), 24(1), 37-46. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 140:316407 AN 2004:99102 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to provide information about the degradative processes that occur in major connective tissue components in skin following exposure of large white pigs to Lewisite vapor. Of particular interest were alterations in glycoproteins, which are known to mediate dermo-epidermal attachment (laminin and type IV collagen) and the main collagen found in the dermis (type III collagen). The immunostaining of transfer blots from skin exts. run on SDS-PAGE gels revealed no evidence of crosslinking of laminin or of type III or IV collagen. However, there was evidence of a very considerable degrdn. of laminin and, to a lesser extent, of type IV collagen. Type III collagen did not appear to be degraded in skin exposed to Lewisite. These degradative processes appeared to be more severe than found in previous studies in Yucatan mini-pigs percutaneously exposed to sulfur mustard, in which only laminin was found to undergo partial cleavage rather than wholesale degrdn. The results suggest that damage to macromol. components in the sub-epidermal basement membrane in skin which mediate dermo-epidermal sepn. processes may be a common feature in the mechanism of action of vesicating agents such as Lewisite and sulfur mustard. It is of interest that the damage to laminin in this study appeared to be more severe than that previously found for sulfur mustard. This suggests that skin can suffer substantial damage yet, in the case of Lewisite exposure, recover relatively quickly. However, Lewisite is not an alkylating agent. Sulfur mustard, in contrast, generates characteristically slow healing lesions, most probably because of its ability to alkylate cell types that normally would be involved in skin regenerative processes.

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In vitro-in vivo extrapolation: estimation of human serum concentrations of chemicals equivalent to cytotoxic concentrations in vitro. [Erratum to document cited in CA139:346894]. Gulden, Michael; Seibert, Hasso. Institut fur Experimentelle Toxikologie, Universitatsklinikum Schleswig-Holstein, Kiel, Germany. Toxicology (2003), 192(2-3), 265. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:152304 AN 2003:826065 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Equation (6) should read: EC50 = ECu50  (1 + KOW  V'L, in vitro) + Cbin vitro. The cor. version of Table 2 is given.

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Solid-Phase Synthesis of Some Alkyl Hydrogen Methylphosphonates. Barucki, Hubert; Black, Robin M.; Kinnear, Kenneth I.; Holden, Ian; Read, Robert W.; Timperley, Christopher M. Defence Science and Technology Laboratory, Wiltshire, UK. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(10), 2279-2286. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 141:23606 AN 2003:764571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Eleven alkyl H methylphosphonates of structure RO(HO)P(O)Me (R = Me, Et, Pr, i-Pr, Bu, hexyl, octyl, cyclohexyl, cycloheptyl, cyclooctyl, and Me3CCH(Me)) were made by phosphoramidite chem. on hydroxymethyl polystyrene resin with yields 30%. MeP(NiPr2)Cl was attached to hydroxymethyl polystyrene using Et3N in CH2Cl2 to give MeP(NiPr2)OCH2-bound polystyrene, which was reacted with various alcs. in MeCN in the presence of tetrazole followed by oxidn. using tBuO2H in toluene; the final product was cleaved from MeP(O)(OR)OCH2-bound resin using CF3CO2H. NCCH2CH2OP(OR)O2H (R = Et iPr) were also prepd. via solid-phase synthesis.

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Effects of sulfur mustard on transcription in human epidermal keratinocytes: Analysis by mRNA differential display. Platteborze, Peter L. Pharmacology Division, USAMRICD, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2003), 23(4), 249-254. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 139:360142 AN 2003:619968 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study examines the transcriptional response of human epidermal keratinocytes (HEK) to sulfur mustard (HD) in order to gain a better understanding of the intracellular events that result in cytotoxicity. Differential display polymerase chain reaction technol. was used to examine the relative transcriptional activity of healthy cells to those exposed to subvesicating or vesicating concns. of HD for 4 h. Approx. 2% of the HEK transcriptome had altered expression. Sixty of the most prominently altered transcripts were characterized. Important upregulated genes include NADH dehydrogenase III, GADD45 and ubiquitin. Key downregulated genes include type I keratin 14, -enolase and caltractin. Many of the identified transcripts protein products presently do not have an assigned function and eleven transcripts were unidentifiable. These transcriptional alterations provide one of the first mol. insights into the intracellular events induced by HD.

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Degradation of VX and sulfur mustard by enzymatic haloperoxidation. Amitai, G.; Adani, R.; Hershkovitz, M.; Bel, P.; Rabinovitz, I.; Meshulam, H. Division of Medicinal Chemistry, Israel Institute for Biological Research, Ness Ziona, Israel. Journal of Applied Toxicology (2003), 23(4), 225-233. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 140:72285 AN 2003:619965 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chloroperoxidase (CPO) isolated from Caldariomyces fumago (20 U ml-1) together with urea hydrogenperoxide (UPER, 0.5 mM) and sodium chloride as co-substrate (NaCl, 0.5 M) caused rapid breakdown of VX (10 M) (t1/2=8 s, 25, 50 mM tartarate, pH 2.75). Glucose oxidase (GOX, Aspergillus niger) and glucose were used as an alternative source for H2O2. A mixt. of GOX (20 U ml-1), glucose (GLU 0.45 M), CPO (20 U ml-1) and NaCl (0.5 M) caused a 3.8-fold slower degrdn. of VX (10 M) (t1/2=30 s, 25, 50 mM tartarate, pH 2.75). The concns. of H2O2 and chlorine produced by this enzyme/substrate mixt. depended mainly on the GLU concn. Horseradish peroxidase (HRP) together with UPER (1 mM) and sodium iodide (NaI, 0.05 M) caused progressive degrdn. of VX that was more than 400-fold slower than with CPO (20 U ml-1), UPER (0.5 mM) and NaCl (0.5 M) (t1/2=55 min, 25, pH 8). Skin decontamination of VX by CPO was tested in pig-ear skin in vitro. The chem. agent VX (0.01 M, 100 l) was degraded by 98% within 3 h of skin diffusion when a mixt. of UPER/NaCl/CPO was applied 60 min prior to VX application. A mixt. of UPER/NaCl without CPO also caused significant VX degrdn. (94%) during skin diffusion whereas it did not cause any VX degrdn. in soln. Degrdn. of VX in skin, obtained without exogenous CPO, may indicate involvement of endogenous intradermal haloperoxidase-like enzyme. Reagent UPER (1 mM) did not cause any degrdn. of VX in soln. or during its skin diffusion. Furthermore, a mixt. of CPO, UPER and NaCl caused rapid degrdn. of sulfur mustard (HD). Sulfur mustard (50 M) incubated in the presence of CPO (4 U ml-1), UPER (0.05 M) and NaCl (0.5 M) at pH 2.75 and 30 was oxidized by 97% and 99% within 5 and 10 min, resp. The oxidn. products HD sulfoxide, HD sulfone and HD sulfoxidevinyl were identified by GC/MS in the enzymic chloroperoxidn. mixt.

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Analysis of Chemical Neutralization Products of Phosphonothiolates by Gas Chromatography Mass Spectrometry. Gupta, A. K.; Palit, M.; Dubey, D. K.; Raza, S. K. Defence Research & Development Establishment, Gwalior, India. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(8), 1631-1637. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 140:303747 AN 2003:603631 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A series of phosphonothioates, including the highly toxic O-Ethyl-S-(2-diisopropylamino) Et methylphosphonothioate (VX), were subjected to chem. neutralization reaction with metallic sodium; the reaction products were identified by GC/MS. The phosphonothioates decomp. to their resp. phosphonic and phosphonothioic acids and this results in the detoxification of VX. Phosphonodithioates R1PO(SR2)2 (2-8; R1 = Me, Et, n-Pr, iPr; R2 = Bu, n-Pr) were reacted with metallic sodium, giving disulfides R2SSR2 and R1PS(OH)2. Trithioate MePS(SPr)2 (9) upon reaction with Na gave polysulfides R2SSR2, R2SSSR2 and R2SSSSR2 (R2 = n-Pr); MePO(OH)2 and MePS(OH)2. All obtained acids were analyzed by GC/MS in the form of their trimethylsilyl esters. GC/MS technique in both EI and CI mode was applied for reaction monitoring and final identification of the neutralization products formed in this reaction.

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Kinetics of Spontaneous Hydrolysis of O-(2,2-Dimethylcyclopentyl)-methylfluorophosphonate and of Hydrolysis During Constant pH Value of the Reaction Medium. Cekovic, Boban; Jovanovic, Bratislav; Lukovic, Zoran. Military Technical Institute, Belgrade, Yugoslavia. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(7), 1521-1540. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 140:253619 AN 2003:524831 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Kinetics of hydrolysis of O-(2,2-dimethylcyclopentyl)-methylfluorophosphonate (1) in dil. aq. soln. was investigated. Rates of hydrolysis of O-(2,2-dimethylcyclopentyl)-methylfluorophosphonate were measured as a function of pH in the range from 3 to 9 in temp. range from 25 to 40. Spontaneous hydrolysis was also studied without monitoring of the pH-value. Rate consts. and activation parameters of the hydrolysis were obtained. The lowest hydrolysis rates for 1 were obtained at pH range 4-6, the reaction was several times faster at pH 3.0 and more than ten times faster at pH 9.0. For dild. solns. the spontaneous hydrolysis had half-life time (t1/2) about 2.8 days at 25, the reaction may be accelerated in more concd. solns. due to proton autocatalysis. Obtained data can be used in processes of degrdn. and detoxification of highly toxic warfare-type compds.

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Enhanced Degradation of Chemical Warfare Agents through Molecular Engineering of the Phosphotriesterase Active Site. Hill, Craig M.; Li, Wen-Shan; Thoden, James B.; Holden, Hazel M.; Raushel, Frank M. Department of Chemistry, Texas A&M University, College Station, TX, USA. Journal of the American Chemical Society (2003), 125(30), 8990-8991. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 139:208973 AN 2003:516949 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The bacterial phosphotriesterase has been utilized as a template for the evolution of improved enzymes for the catalytic decompn. of organophosphate nerve agents. A combinatorial library of active site mutants was constructed by randomizing residues His-254, His-257, and Leu-303. The collection of mutant proteins was screened for the ability to hydrolyze a chromogenic analog of the most toxic stereoisomer of the chem. warfare agent, soman. The mutant H254G/H257W/L303T catalyzed the hydrolysis of the target substrate nearly 3 orders of magnitude faster than the wild-type enzyme. The x-ray crystal structure was solved in the presence and absence of diisopropyl Me phosphonate. The mutant enzyme was ligated to an addnl. divalent cation at the active site that was displaced upon the binding of the substrate analog inhibitor. These studies demonstrate that substantial changes in substrate specificity can be achieved by relatively minor changes to the primary amino acid sequence.

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In vitro-in vivo extrapolation: estimation of human serum concentrations of chemicals equivalent to cytotoxic concentrations in vitro. Gulden, Michael; Seibert, Hasso. Institut fur Experimentelle Toxikologie, Universitatsklinikum Schleswig-Holstein, Kiel, Germany. Toxicology (2003), 189(3), 211-222. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:346894 AN 2003:484566 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In the present study an extrapolation model for estg. serum concns. of chems. equiv. to in vitro effective concns. is developed and applied to median cytotoxic concns. (EC50) detd. in vitro. Nominal concns. of a chem. in serum and in vitro are regarded as equiv., if they result in the same aq. concn. of the unbound form. The algorithm used is based on equil. distribution and requires albumin binding data, the octanol-water partition coeff. (Kow), and the albumin concns. and lipid vol. fractions in vitro and in serum. The chems. studied cover wide ranges of cytotoxic potency (EC50: 2.5-530 000 M) and lipophilicity (log Kow: -5 to 7). Their albumin binding characteristics were detd. by an in vitro cytotoxicity test as described previously. The equivalent serum concns. of 19 of the 33 compds. investigated, having high protein binding and/or lipophilicity, were substantially higher than the EC50-values, by factors of 2.5-58. Prominent deviations between the equiv. nominal concns. in serum and in vitro were largely restricted to chems. with higher cytotoxic potency (EC501000 M). The results suggest that ests. of equiv. serum concns. based on in vitro data are robust for chems. with low lipophilicity (log Kow2) and low potency (EC50>1000 M). With more potent chems. or those with higher lipophilicity partitioning into lipids and/or binding to serum proteins have to be taken into account when estg. in vivo serum concns. equiv. to in vitro effective concns.

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Putative role of proteolysis and inflammatory response in the toxicity of nerve and blister chemical warfare agents: Implications for multi-threat medical countermeasures. Cowan, F. M.; Broomfield, C. A.; Lenz, D. E.; Smith, W. J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2003), 23(3), 177-186. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 139:241394 AN 2003:447085 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review. Despite the contrasts in chem. and toxicity, for blister and nerve chem. warfare agents there may be some analogous proteolytic and inflammatory mediators and pathol. pathways that can be pharmacol. targets for a single-drug multi-threat medical countermeasure. The dermal-epidermal sepn. caused by proteases and bullous diseases compared with that obsd. following exposure to the blister agent sulfur mustard (2,2'-dichlorodiethyl sulfide) has fostered the hypothesis that sulfur mustard vesication involves proteolysis and inflammation. In conjunction with the paramount toxicol. event of cholinergic crisis that causes acute toxicity and ppts. neuronal degeneration, both anaphylactoid reactions and pathol. proteolytic activity have been reported in nerve-agent-intoxicated animals. Two classes of drugs already have demonstrated multi-threat activity for both nerve and blister agents. Serine protease inhibitors can prolong the survival of animals intoxicated with the nerve agent soman and can also protect against vesication caused by the blister agent sulfur mustard. Poly(ADP-ribose) polymerase (PARP) inhibitors can reduce both soman-induced neuronal degeneration and sulfur-mustard-induced epidermal necrosis. Protease and PARP inhibitors, like many of the other countermeasures for blister and nerve agents, have potent primary or secondary anti-inflammatory pharmacol. Accordingly, we hypothesize that drugs with anti-inflammatory actions against either nerve or blister agent might also display multithreat efficacy for the inflammatory pathogenesis of both classes of chem. warfare agent.

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Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: Influence of atropine dose. Taysse, L.; Calvet, J.-H.; Buee, J.; Christin, D.; Delamanche, S.; Breton, P. Defense Research Centre, Centre d'Etudes du Bouchet, Vert-Le-Petit, Fr. Toxicology (2003), 188(2-3), 197-209. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:346870 AN 2003:415467 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This investigation compared the efficacy of diazepam and the water-sol. prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD50 of sarin (s.c. route) and 1 min after intoxication treated by i.m. injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiol. parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were obsd. in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were obsd. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not obsd. but 62.5% of the animals displayed respiratory difficulties. These symptoms were not obsd. when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concn. of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.

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Low-level sarin-induced alteration of immune system reaction in inbred BALB/c mice. Kassa, Jiri; Krocova, Z.; Sevelova, L.; Sheshko, V.; Kasalova, I.; Neubauerova, V. Department of Toxicology, Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2003), 187(2-3), 195-203. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:241449 AN 2003:289956 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To study the influence of low-level sarin inhalation exposure on immune functions, inbred BALB/c mice were exposed to low concns. of sarin for 60 min in the inhalation chamber. Two concns. of sarin were chosen-asymptomatic concn. (LEVEL 1) and non-convulsive symptomatic concn. (LEVEL 2). The evaluation of immune functions was carried out using phenotyping of CD3 (T-lymphocytes), CD4 (helper T-lymphocytes), CD8 (cytotoxic T-lymphocytes) and CD19 cells (B-lymphocytes) in the lungs, blood and spleen, lymphoproliferation of spleen cells stimulated in vitro by various mitogens (Con A, lipopolysaccharides), phagocyte activity of peritoneal and alveolar macrophages, prodn. of N-oxides by peritoneal macrophages and the measurement of the natural killer cell activity at 1 wk following sarin exposure. The results were compared to the values obtained from control mice exposed to pure air instead of sarin. The results indicate that not only symptomatic but also asymptomatic dose of sarin is able to alter the reaction of immune system at 1 wk following exposure to sarin. While the no. of CD3 cells in the lungs was slightly decreased, an increase in CD19 cells was obsd. esp. in the lungs and blood. The reduced proportion of T-lymphocytes is caused by decay of CD4 pos. T-cells. Lymphoproliferation was significantly decreased regardless of the mitogen and sarin concn. used. The prodn. of N-oxides by peritoneal macrophages was stimulated after exposure to LEVEL 2 of sarin, whereas their ability to phagocyte the microbes was increased after exposure to LEVEL 1. The natural killer cell activity was significantly higher in the case of inhalation exposure of mice to LEVEL 2 of sarin. Thus, not only organophosphorus insecticides but also nerve agents such as sarin are able to alter immune functions even at a dose that does not cause clin. manifested intoxication following the inhalation exposure. Nevertheless, the alteration of immune functions following the inhalation exposure to a symptomatic concn.
of sarin seems to be more pronounced.

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Development of a sensor for the hydrolysis product of the nerve agent soman utilizing molecular imprinting and silica sol-gel techniques. Parker, Jennifer L.; Horne, Starr N.; Kita, Justin M.; Peeples, Christopher J.; DiCesare, John C. Department of Chemistry and Biochemistry, University of Tulsa, Tulsa, OK, USA. Polymeric Materials Science and Engineering (2003), 88 328-329. CODEN: PMSEDG ISSN: 1550-6703. Journal; Computer Optical Disk written in English. CAN 139:48357 AN 2003:222702 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preliminary findings were presented leading to the development of a pinacolylmethylphosphonate (PMP, the hydrolysis product of the nerve agent soman) sensor, utilizing silica sol-gel techniques, mol. imprinting, and lanthanide luminescence.

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Fluorescent Detection of Chemical Warfare Agents: Functional Group Specific Ratiometric Chemosensors. Zhang, Shi-Wei; Swager, Timothy M. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA. Journal of the American Chemical Society (2003), 125(12), 3420-3421. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 138:332984 AN 2003:159757 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Indicators providing highly sensitive and functional group specific fluorescent response to diisopropyl fluorophosphate (DFP, a nerve gas (G-agent) simulant) are reported. Nonemissive phenylpyridyl indicator reacts with DFP to give a cyclized compd. that shows a high emission due to its highly planar and rigid structure. Very weak emission was obsd. by the addn. of HCl. Another indicator based on pyridyl naphthalene exhibits a large shift in its emission spectrum after reaction with DFP, which provides for quant. ratiometric detection.

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Nerve Agents Detection Using a Cu2+/L-Cysteine Bilayer-Coated Microcantilever. Yang, Yuming; Ji, Hai-Feng; Thundat, Thomas. Department of Chemistry Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, USA. Journal of the American Chemical Society (2003), 125(5), 1124-1125. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 138:51039 AN 2003:24843 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A Cu2+/L-Cys bilayer-coated microcantilever undergoes bending upon exposure to di-Me Me phosphonate at concn. as low as 10-15 M due to the complexation of a phosphonyl group with the Cu2+/L-cysteine bilayer on the microcantilever surface.

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Neuroprotective efficacy of pharmacological pretreatment and antidotal treatment in tabun-poisoned rats. Krejcova, G.; Kassa, J. Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2003), 185(1-2), 129-139. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:2191 AN 2002:970172 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To study the influence of pharmacol. pretreatment (PANPAL) and antidotal treatment (obidoxime plus atropine) on tabun-induced neurotoxicity, male albino rats were poisoned with a LD of tabun (280 g/kg i.m.; 100% of LD50 value) and obsd. at 24 h and 7 days following tabun challenge. The neurotoxicity of tabun was evaluated using a functional observational battery (FOB) and an automatic measurement of motor activity. Pharmacol. pretreatment as well as antidotal treatment were able to eliminate most of tabun-induced neurotoxic effects obsd. at 24 h following tabun poisoning. However, there was not significant difference between the efficacy of PANPAL and antidotal treatment to eliminate tabun-induced neurotoxicity in rats. The combination of PANPAL pretreatment and antidotal treatment seems to be slightly more effective in the elimination of tabun-induced neurotoxicity in rats at 24 h following tabun challenge in comparison with the administration of PANPAL pretreatment or antidotal treatment alone. At 7 days following tabun poisoning, very few neurotoxic signs in tabun-poisoned rats were obsd. regardless of administration of pharmacol. pretreatment or antidotal treatment. Thus, our findings confirm that the combination of pharmacol. pretreatment and antidotal treatment is not only able to protect the exptl. animals from the lethal effects of tabun but also to eliminate most of tabun-induced signs of neurotoxicity in tabun-poisoned rats.

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Pyridostigmine bromide modulates topical irritant-induced cytokine release from human epidermal keratinocytes and isolated perfused porcine skin. Monteiro-Riviere, Nancy A.; Baynes, Ronald E.; Riviere, Jim E. Center for Chemical Toxicology Research and Pharmacokinetics (CCTRP), North Carolina State University, Raleigh, NC, USA. Toxicology (2003), 183(1-3), 15-28. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 138:364009 AN 2002:970031 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gulf War personnel were given pyridostigmine bromide (PB) as a prophylactic treatment against organophosphate nerve agent exposure, and were exposed to the insecticide permethrin and the insect repellent N,N-diethyl-m-toluamide (DEET). The purpose of this study was to assess the effects of PB to modulate release of inflammatory biomarkers after topical chem. exposure to chem. mixts. contg. permethrin and DEET applied in ethanol or water vehicles. Treatments were topically applied to isolated perfused porcine skin flaps (IPPSFs). Concns. of interleukin-8 (IL-8), tumor necrosis factor- (TNF-) and prostaglandin E2 (PGE2) were assayed in perfusate to probe for potential inflammatory effects after complex mixt. application. IPPSFs (n=4/treatment) were topically dosed with mixts. of permethrin, DEET, and permethrin/DEET, in EtOH. Each treatment was repeated with perfusate spiked with 50 ng/mL of PB. Perfusate was also spiked with 30 ng/mL diisopropylfluorophosphate to simulate low level organophosphate nerve agent exposure. Timed IPPSF venous effluent samples (0.5,1,2,4, and 8 h) were assayed by ELISA for IL-8 and TNF- and by EIA for PGE2. Overall, PB infusion caused a decrease or IL-8 and PGE2 release. Effects on TNF- were vehicle dependent. To probe the potential mechanism of this PB effect, human epidermal keratinocyte HEK cell cultures were exposed to permethrin DEET permethrin/DEET, with and without PB in DMSO. IL-8 was assayed at 1, 2, 4, 8, 12 and 24 h. PB suppressed IL-8 in permethrin and EtOH treatment from 4 to 24 h confirming the IPPSF results. In conclusion, these studies suggest that systemic exposure to PB suppressed IL-8 release at multiple time points in 2 skin model systems. This interaction merits further study.

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The pharmacokinetics and pharmacodynamics of two HI-6 salts in swine and efficacy in the treatment of GF and soman poisoning. Lundy Paul M; Hill Ira; Lecavalier Pierre; Hamilton Murray G; Vair Cory; Davidson Corey; Weatherby Kendal L; Berger Bradley J Chemical Biological Defence Section, Defence Research and Development Canada-Suffield, Box 4000, Medicine Hat Alberta, Alta., Canada T1A 8K6. paul.lundy@drdc-rddc.gc.ca Toxicology (2005 Mar 30), 208(3), 399-409. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15695025 AN 2005067571 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Anesthetized pigs were injected i.m. with 500 mg HI-6 dichloride (HI-6 2Cl) (1-[[[4-(aminocarbonyl)-pyridinio]methoxy]methyl]-2[(hydroxyimino)methyl]pyridinium dichloride; CAS 34433-31-3)) or the molar equivalent of HI-6 dimethanesulphonate (HI-6 DMS) 633 mg. Plasma HI-6 concentrations were measured by HPLC (1, 3, 5, 10, 15, 30, 60 min and every 30 min until 4h or 6h following the i.v. or i.m. dose respectively) while a variety of physiological responses were continuously examined. HI-6 (500 mg 2Cl or 633 mg DMS) resulted in an identical pharmacokinetic profile unaffected by atropine co-administration. Neither HI-6 salt resulted in clinically significant changes in cardiovascular or respiratory function. HI-6 DMS (1899 mg i.v.) resulted in plasma HI-6 concentrations about 10 times higher than measured following i.m. 500 mg 2Cl or 633 mg DMS and resulted in small transitory effect on mean arterial pressure. Atropine plus HI-6 DMS (1-9 mg/kg or 127-172 mg/kg i.m.) protected up to 100% of guinea pigs exposed to 5 x LD50 of GF (cyclohexyl methyl phosphonoflouridate) or soman (pinacolyl methylphosphonofluoridate) (GD) respectively. The results suggest that the two HI-6 salts have a similar pharmacokinetic profile while HI-6 DMS appears extremely safe and effective against nerve agents and may be as suitable for human use.

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Inhalation toxicity in mice exposed to sarin (GB) for 20-720 min. Bide R W; Risk D J Defence R&D Canada--Suffield, Box 4000, Medicine Hat, Alberta, Canada T1A 8K6. Richard.Bide@drdc-rddc.gc.ca Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 459-67. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558652 AN 2004610605 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Most of the historical data for the toxicity of sarin (GB) was collected for exposure times of <10 min in attempts to establish the utility of and defence against this agent in offensive military use. However, information concerning the toxicity of GB (and other nerve agents) from longer exposures of 1-12 h is critical for all personnel who must work in or close to low-level concentrations of chemical for extended periods and for all personnel, dressed in Individual Protective Equipment, who need to know when, and if, it is safe to take off these cumbersome garments.The data presented for the toxicity of GB to mice for whole-body exposures of 20 min to 12 h are intended to form part of an ongoing, multi-species effort aimed at establishing toxicity estimates for humans for these longer exposure times: LCT50 values of 430, 540, 900, 1210 and 2210 mg.min m(-3) or LC50 values of 21.5, 9.0, 5.0, 3.4 and 3.1 mg m(-3) were obtained for mice for 20-, 60-, 180-, 360- and 720-min exposures to GB, respectively. The data for longer exposures do not follow Haber's rule (LCT50=CT). The 20- and 60-min data fit the 'toxic load model' involving CnT that was established previously from historical data for 0.17-30 min GB exposures to mice. The LCT(50) and LC50 values for 3, 6 and 12 h are progressively higher (toxicity lower) than predicted by either Haber's rule or the toxic load model.

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Low levels of sarin affect the EEG in marmoset monkeys: a pilot study. van Helden Herman P M; Vanwersch Raymond A P; Kuijpers Willem C; Trap Henk C; Philippens Ingrid H C; Benschop Hendrik P Department of Medical Countermeasures. TNO Prins Maurits Laboratory, PO Box 45, 2280 AA Rijswijk, The Netherlands. helden@pml.tno.nl Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 475-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558834 AN 2004598850 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The main purpose of this pilot study was to estimate the lowest observable adverse effect level (LOAEL) for the electroencephalogram (EEG) upon long-term, low-level exposure of vehicle-pretreated and pyridostigmine-pretreated marmoset monkeys to sarin vapour. This is the C.t value (t=5 h) of exposure at which the EEG becomes significantly different from that resulting from air exposure of the same animals. The LOAELs for effects on the EEG in vehicle- and pyridostigmine-pretreated marmosets appeared to be 0.2 and 0.1 mg min m(-3), respectively. Comparatively, the latter LOAEL values are at least an order of magnitude lower than the previously established LOAEL for miosis and only 2-5 times higher than the lowest observable effect level (LOEL) of bound sarin in blood.The second aim of the study was to analyse the EEG of the same marmosets again during a 5-h exposure to air 1 year after exposure to sarin vapour. All the marmosets still demonstrated significant (P <0.05) EEG differences. In most vehicle-pretreated marmosets the energy (microV2) per EEG band was higher than that observed 1 year earlier, which might indicate that neurons had become more sensitive to excitation. This phenomenon was less pronounced in pyridostigmine-pretreated animals. Visual examination of the EEG records revealed clear bursts of alpha frequencies (ca. 9 Hz), resembling sleep-spindles, that were present more frequently in both groups of exposed marmosets than in naive animals. These late changes in spindle oscillation might be the result of changes in the cholinergic system due to exposure to sarin vapour 1 year previously. In conclusion, EEG abnormalities persisting for more than 1 year may occur in humans during long-term (5 h) exposure to subclinical levels of sarin that are not detectable by the currently fielded alarm systems.

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Protection and inflammatory markers following exposure of guinea pigs to sarin vapour: comparative efficacy of three oximes. Levy A; Chapman S; Cohen G; Raveh L; Rabinovitz I; Manistersky E; Kapon Y; Allon N; Gilat E Israel Institute for Biological Research, Department of Pharmacology, PO Box 19, Ness Ziona 74100, Israel. RonLevy@iibr.gov.il Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 501-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558827 AN 2004598847 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The purpose of the present study was to compare the antidotal efficacy and the combined effects on inflammatory markers of three oximes--toxogonine, TMB4 and 2-PAM--in combination with anticholinergic drugs following exposure to sarin vapour by inhalation.Guinea pigs restrained in plethysmographs were exposed to various doses of sarin vapour (in the range of 1.4-4.4LD50). The antidotal mixture was injected immediately (5-20 s) following exposure (3 mg kg(-1) atropine and 1 mg kg(-1) benactyzine in combination with 6 mg kg(-1) toxogonine, 2 mg kg(-1) TMB4 or 12 mg kg(-1) 2-PAM). Bronchoalveolar lavage (BAL) samples were taken from surviving animals 24 h after exposure to determine the levels of inflammatory markers. A differential cell count was performed in BAL samples on Giemsa-stained slides. The inflammatory markers--histamine and prostaglandins (PGE)--were measured in BAL using radioimmunoassay (RIA) techniques.The survival rate in the various treatment groups and analysis of BAL samples showed that: (i) Toxogonine, TMB4 and 2-PAM, without pyridostigmine pretreatment, at doses that were proportional to their doses in the respective auto-injectors, exhibited similar antidotal efficacy against sarin exposure. (ii) The results demonstrated that a centrally acting anticholinergic drug is essential in the antidotal mixture to ensure survival. (iii) Histamine release and eosinophilia following sarin inhalation might require additional intervention, aimed at reducing the symptoms of allergic reaction and possibly expediting recovery.

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Delayed haematological complications of mustard gas. Ghanei Mostafa Department of Internal Medicine, Baqiyatallah University of Medical Sciences, Chemical Injured Research Centre, Tehran, Iran. m.ghanei@bmsu.ac.ir Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 493-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558826 AN 2004598846 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Haematopoiesis could be affected by mustard gas. We randomly selected 318 chemical victims exposed to mustard gas and compared their cell blood counts and peripheral blood smears (PBS) with those of 377 healthy men, and also various haematological indices of 57 of these victims compared with previous data 5 years ago.The average number of red blood cells and haemoglobin of victims compared with the controls was not significantly different, but they were increased compared with data from 5 years ago. White blood cell counts, neutrophils and lymphocytes did not show any clinically meaningful difference compared with the control group but 20 cases with atypical lymphocytes in their PBS have been found.Change in lymphocyte shape may be related to committed stem cell involvement. Further studies on bone marrow cells and cell markers are needed to document this hypothesis. The mild increase in erythroid cells and haemoglobin concentration may be due to chronic obstructive pulmonary disorder and other respiratory diseases in these patients.

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Investigating the affinities and persistence of VX nerve agent in environmental matrices. Love Adam H; Vance Andrew L; Reynolds John G; Davisson M Lee Environmental Science Division, Lawrence Livermore National Laboratory, P.O. Box 808, L-396, Livermore, CA 94551, USA. love5@llnl.gov Chemosphere (2004 Dec), 57(10), 1257-64. Journal code: 0320657. ISSN:0045-6535. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15519370 AN 2004547393 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity for an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when specific adsorption was forced. No enhanced degradation occurred with goethite in small amounts of water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.

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Localization of substance P gene expression for evaluating protective countermeasures against sulfur mustard. Casbohm Stacy L; Rogers James V; Stonerock Mindy K; Martin Jamie L; Ricketts-Kaminsky Karen M; Babin Michael C; Casillas Robert P; Sabourin Carol L K Battelle Memorial Institute, Medical Research and Evaluation Facility, 505 King Avenue, JM-3, Columbus, OH 43201, USA Toxicology (2004 Nov 15), 204(2-3), 229-39. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE); (VALIDATION STUDIES) written in English. PubMed ID 15388249 AN 2004477792 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard [bis(2-chloroethyl)sulfide; SM] is a chemical warfare agent that produces edema and blister formation with a severe inflammatory reaction. The mouse ear vesicant model for SM injury has been used to evaluate pharmacological agents for countering SM dermal injury. The vanilloid olvanil reduces SM-induced edema and mRNA expression of cytokines and chemokines, suggesting that blocking the inflammatory effects of neuropeptides, such as substance P (SP), may provide protection against SM-induced dermal injury. This study examined SP expression in mice exposed to SM (0.16 mg) on the inner surface of the right ear, with or without olvanil pretreatment at 1, 10, 30, 60, and 360 min following exposure. In naive skin, SP mRNA localization was associated with blood vessels and sebaceous glands. In SM-exposed skin, SP mRNA was also detected in perivascular dermal cells. Immunohistochemical localization of SP protein was observed in the ear skin of naive, SM-, olvanil/SM-, and vehicle-treated mice. Quantification of SP+ perivascular dermal cells revealed that SM exposure led to a significant increase (P < or = 0.05) in SP+ cells over the observed time period. Olvanil pretreatment significantly reduced (P < or = 0.05) the mean number of SP+ cells at 60 and 360 min. This study demonstrates that SP expression could provide an additional endpoint for evaluating the effectiveness of vanilloid drugs on SM-induced skin inflammation.

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Enhanced degradation of chemical warfare agents through molecular engineering of the phosphotriesterase active site. Hill Craig M; Li Wen-Shan; Thoden James B; Holden Hazel M; Raushel Frank M Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, TX 77842-3012, USA Journal of the American Chemical Society (2003 Jul 30), 125(30), 8990-1. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15369336 AN 2004461552 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

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Photocatalytic oxidation of VX simulant 2-(butylamino)ethanethiol. Vorontsov Alexandre V; Chen Yi-Chuan; Smirniotis Panagiotis G Boreskov Institute of Catalysis, Novosibirsk 630090, Russian Federation, Russia Journal of hazardous materials (2004 Sep 10), 113(1-3), 89-95. Journal code: 9422688. ISSN:0304-3894. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15363518 AN 2004456562 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Photocatalytic oxidation of 2-(butylamino)ethanethiol (BAET) was undertaken in aqueous suspension of TiO2 Hombikat UV 100 and Degussa P25 under different initial reaction conditions in order to determine the best parameters for the fastest mineralization of the substrate. BAET is considered to be a simulant for the VX chemical warfare agent. The application of ultrasound had only a small positive effect on the BAET photocatalytic degradation. The highest mineralization rate of 0.433 mg/(l min) was found in unbuffered TiO2 Degussa P25 suspension with initial pH value of about 9.4, TiO2 concentration 500 mg/l and the initial BAET concentration 1000 mg/l. Decreasing of the initial solution pH to 6.1 or below stops the mineralization of BAET while increasing of pH to about 11 drastically changed the degradation profile. At this initial pH, the first 100 min of reaction led to only oxidation of sulfur moiety and organic intermediates accumulated in the solution. Thereafter, mineralization of the products started. The main detected volatile product was butyl aldehyde and the main polar one was 2-(butylamino) acetic acid. In the case of TiO2 Hombikat UV 100, conversion of TOC at initial pH 11 exceeded that at initial pH 9.1. For Degussa P25, the starting pH 9.4 was the best for TOC conversion. The results can be used for treatment of water from pollutants with aliphatic nitrogen and sulfur atoms.

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Retrospective detection of exposure to nerve agents: analysis of phosphofluoridates originating from fluoride-induced reactivation of phosphylated BuChE. van der Schans Marcel J; Polhuijs Martine; van Dijk Corry; Degenhardt Carla E A M; Pleijsier Kees; Langenberg Jan P; Benschop Hendrik P Department of Medical Countermeasures, TNO Prins Maurits Laboratory, P.O. Box 45, 2280 AA Rijswijk, The Netherlands. schansm@pml.tno.nl Archives of toxicology (2004 Sep), 78(9), 508-24. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15170525 AN 2004433787 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The utility was explored of a new approach to detect retrospectively exposure to nerve agents by means of conversion of the inhibitor moiety bound to the active site of the enzyme BuChE in plasma with fluoride ions into a phosphofluoridate which is subsequently analyzed by means of gas chromatography (GC). This quantifies >or=0.01% inhibition of BuChE and identifies the structure of the inhibitor except for the original leaving group. A three-tiered approach was followed involving the five classical nerve agents GA, GB, GF, GD, and VX, as well as the active metabolite of parathion, i.e., paraoxon: in vivo experiments in rhesus monkeys after iv administration of a sign-free dose of agent and concomitant in vitro experiments in plasma of rhesus monkeys and humans should allow an assessment of in vivo retrospectivity in humans. A systematic investigation was performed in order to find a single set of reaction conditions which yields a maximum amount of phosphofluoridate for all nerve agents. Fluoride-induced reactivation at 25 degrees C at a final concentration of 250 mM KF during 15 min in a pH-range between 4 and 6 appears to be effective. The in vitro decrease with time in reactivatibility of inhibited BuChE in plasma from humans and rhesus monkeys was largely due to aging of the phosphyl moiety, except for VX where spontaneous reactivation was a major cause. The decrease followed first-order except for a biphasic course in the case of GF in human and rhesus monkey plasma as well as of GD in rhesus plasma. In vitro half-lifes in human plasma ranged between ca. 14 h for GB and ca. 63 h for GA. A comparison of the in vivo data from rhesus monkeys and the in vitro data is complicated by the observation that the in vivo decrease with time of fluoride-reactivated phosphofluoridate is biphasic for all nerve agents.
The terminal in vivo phase pertains to a small fraction of the amount of initially regenerated phosphofluoridate but is responsible for a considerable degree of retrospectivity, ranging between 14 and 56 days for GF and GB, respectively. The new procedure can be used in a variety of practical applications, e.g., (i) biomonitoring in health surveillance at exposure levels that are several orders of magnitude lower than presently possible; (ii) diagnosis in case of alleged exposure to nerve agents in time of war or after terrorist attacks; (iii) in forensic cases against suspected terrorists that have handled organophosphate anticholinesterases; and (iv) in research applications such as investigations on lowest observable effect levels of exposure to nerve agents.

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Biochemical changes in mouse lung after subcutaneous injection of the sulfur mustard 2-chloroethyl 4-chlorobutyl sulfide. Elsayed Nabil M; Omaye Stanley T Department of Nutrition and Environmental Sciences and Health, Graduate Program, University of Nevada at Reno, Reno, NV, USA. nelsayed@hurleyconsulting.com Toxicology (2004 Jul 1), 199(2-3), 195-206. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15147793 AN 2004250354 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant-type chemical warfare agent (CWA) introduced in World War I which continues to be produced, stockpiled, and occasionally deployed by some countries, and could be used potentially by terrorists. Exposure to HD can cause erythema, blisters, corneal opacity, and airway damage. We have reported previously that subcutaneous (SC) injection of immunodeficient athymic nude mice with the half mustard butyl 2-chloroethyl sulfide (BCS) causes systemic biochemical changes in several organs distal to the exposure site. In the present study, we examined the response of non-immunodeficient Swiss Webster mice to the mustard, 2-chloroethyl 4-chlorobutyl sulfide (CECBS). In a pilot study, we found that a single SC injection of 20-25 microl/mouse causes death within 24h. Consequently, we used 5 microl/mouse (approx. 0.017 mg/kg body weight) of neat CECBS or an equal volume of saline as control. We examined the lungs after 1, 24, and 48 h for biochemical changes including total and oxidized glutathione, protein, DNA, and lipid peroxidation contents in tissue homogenate, and superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, and glutathione S-transferases activities in the cytosol. After 1h and/or 24h, we found statistically significant changes that were resolved by 48 h. These changes mimicked those of HD and BCS and were generally consistent with free radical-mediated oxidative stress. The implications of these observations are two-fold. First, dermal exposure to low-dose mustard gas could elicit systemic changes impacting distal organs such as the lungs. It also suggests that antioxidants could potentially modulate the response and reduce the damage. Second, although the use of known CWAs such as HD is prohibited, analogs that are not recognized as agents are as toxic and could be dangerous if acquired and used by potential terrorists.

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Reactivation and aging kinetics of human acetylcholinesterase inhibited by organophosphonylcholines. Worek F; Thiermann H; Szinicz L Institut fur Pharmakologie und Toxikologie der Bundeswehr, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2004 Apr), 78(4), 212-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14647978 AN 2004188515 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A great number of structurally different organophosphorus compounds (OPs) was synthesized in the past decades to be used as pesticides or chemical warfare agents. Methyl-fluorophosphonylcholines were found to be highly toxic OPs and the acetylcholinesterase (AChE) reactivator pralidoxime was shown to be unable to reactivate inhibited AChE. In the course of the development of more effective AChE reactivators, we have determined the reactivation rate constants of various oximes with human AChE inhibited by methylfluorophosphonylcholine (MFPCh), methylfluoro-beta-phosphonylcholine (MFP beta Ch) and methylfluorophosphonylhomocholine (MFPhCh). In addition, we investigated the potential influence of aging phenomena on the oxime efficacy. Human AChE inhibited by MFPCh, MFP beta Ch or MFPhCh was extremely resistant towards reactivation by oximes. Nevertheless, the newer compounds, HLo 7 and HI 6, were substantially more potent reactivators than obidoxime and pralidoxime. The low oxime efficacy was not due to rapid aging since no decrease in reactivatability was found over 96 h at 37 degrees C. Within this period a substantial spontaneous reactivation was observed, with MFPCh >MFP beta Ch >MFPhCh, which did not follow pseudo-first-order kinetics. In conclusion, the unexpected results, i.e., high resistance of inhibited AChE towards oxime reactivation and aging, and much lower resistance towards spontaneous reactivation, calls for further experiments at a molecular level for a better understanding of the interactions among AChE, its inhibitors and reactivators.

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Amelioration of sulfur mustard skin injury following a topical treatment with a mixture of a steroid and a NSAID. Dachir Shlomit; Fishbeine Eliezer; Meshulam Yakov; Sahar Rita; Chapman Shira; Amir Adina; Kadar Tamar Israel Institute for Biological Research, Department of Pharmacology, PO Box 19, Ness-Ziona 74100, Israel. shlomit@iibr.gov.il Journal of applied toxicology : JAT (2004 Mar-Apr), 24(2), 107-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15052605 AN 2004157688 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The ability to ameliorate sulfur mustard (HD)-induced oedema by treatment with anti-inflammatory drugs was reported previously after screening four steroids and four non-steroidal anti-inflammatory drugs (NSAIDs) using the mouse ear vesicant model. Following the screening study, one steroid and one NSAID (Adexone and Voltaren) were selected as the most effective, and a mixture of the two was chosen for the present more extensive research. The effect of the combined treatment on clinical, biochemical and histopathological parameters following HD insult was studied. Mice ears were exposed to 0.2 micro l of HD for 10 min to produce a moderate skin injury. Oedema development peaked ca. 48 h following exposure, as determined by weighing ear biopsies. Histological observations at that time exhibited damage to the epidermis and dermis. An increase in prostaglandin E (PGE) was measured in skin homogenates, starting 8 h following exposure and lasting at least up to 48 h post-exposure. A topical treatment using the above anti-inflammatory mixture significantly reduced inflammatory parameters when applied up to 4 h following exposure. These parameters included extent of oedema, levels of PGE, area of clinical damage and extent of cytotoxic injury (vesications and damaged epithelial cells). Thus, a combination of a steroid and NSAID was found to be effective in reducing the intensity of HD skin injury and possibly shortening the time to full recovery. The treatment, however, did not prevent completely the ensuing cytotoxic processes in the epithelial layer. Copyright 2004 John Wiley & Sons, Ltd.

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Protective effect of topical iodine containing anti-inflammatory drugs against sulfur mustard-induced skin lesions. Wormser Uri; Sintov Amnon; Brodsky Berta; Casillas Robert P; Nyska Abraham Berman Building, Institute of Life Sciences, The Hebrew University, 91904 Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2004 Mar), 78(3), 156-66. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14618300 AN 2004140011 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Previous studies have shown the antidotal efficacy of topical iodine at 15 and 30 min post-exposure to sulfur mustard (SM). Here we demonstrate efficacy at longer intervals (20, 30, 45, and 60 min, respectively, for data) using an improved topical povidone-iodine preparation termed N66, which contains steroidal and non-steroidal anti-inflammatory agents. In the mouse, N66 reduced severity of ear edema by 43, 47, 44, and 36%; ear epidermal ulceration by 74, 58, 45, and 58%; and epidermal necrosis by 54, 34, 26, and 31% at the respective time points. A similar effect was observed with encrustation. The healing marker, grade of acanthotic area, showed dramatic increases of 39.6-, 25.3-, 20.9-, and 22-fold. Severity of the dermal parameters, acute inflammation and dermal necrosis, was reduced by 63, 34, 34, and 38% and 80, 54, 54, and 59%, respectively. In guinea pig skin, topical treatment with N66 45 min post-exposure reduced the SM-induced ulceration area by 75%. The histological parameters subepidermal microblister formation, epidermal ulceration, epidermal necrosis, and encrustation were reduced by 63, 61, 41, and 41%, respectively. The healing marker, grade of acanthotic area, was elevated by 73%. N66 induced a statistically significant reduction in two dermal markers for tissue damage: acute inflammation (33%) and dermal necrosis (48%). Reduced skin damage was also observed in areas adjacent the treated sites. The pharmacologically active components of N66 showed additive effect. These findings suggest that the povidone-iodine preparation combined with anti-inflammatory agents functions as a potent antidote against skin lesions induced by SM at relatively long intervals between exposure and treatment.

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Low-level exposure of guinea pigs and marmosets to sarin vapour in air: lowest-observable-adverse-effect level (LOAEL) for miosis. van Helden Herman P M; Trap Henk C; Kuijpers Willem C; Oostdijk John P; Benschop Hendrik P; Langenberg Jan P Department of Medical Countermeasures, TNO Prins Maurits Laboratory, PO Box 45, 2280 AA Rijswijk, The Netherlands. helden@pml.tno.nl Journal of applied toxicology : JAT (2004 Jan-Feb), 24(1), 59-68. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14745848 AN 2004044499 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration x time (C.t) value (t = 5 h) of exposure at which miosis becomes significant. The ratio of pupil and iris diameters, measured on digital photographs taken on-line during exposure, was calculated as a measure for miosis. The exposure concentrations were in the range 7-150 microg x m(-3) and the exposure times needed to achieve significant miosis were in the range 10-300 min. Both vehicle- and pyridostigmine-pretreated animals were used in the experiments. The latter pretreatment resulted in ca. 30% inhibition of erythrocyte acetylcholinesterase in both species. In vehicle-pretreated guinea pigs and marmosets the pupil size was decreased significantly (P < 0.05) at sarin doses of 1.8 +/- 0.3 and 2.5 +/- 0.8 mg x min x m(-3), respectively. In pyridostigmine-pretreated guinea pigs and marmosets the pupil size was affected significantly (P < 0.05) at 1.8 +/- 0.5 and 3.0 +/- 0.8 mg x min x m(-3), respectively. Evidently there is no significant influence of pyridostigmine pretreatment on the LOAEL. These data were addressed in light of the recommended occupational and detection limits for sarin vapour in air. It was concluded that miosis will occur during low-level sarin exposure at levels that are not detectable by the currently fielded alarm systems, assuming that humans are as sensitive for sarin vapour in air as guinea pigs and marmosets. Copyright 2004 John Wiley & Sons, Ltd.

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Examination of changes in connective tissue macromolecular components of large white pig skin following application of Lewisite vapour. Lindsay Christopher D; Hambrook Joy L; Brown Roger F R; Platt Jan C; Knight Robert; Rice Paul Biomedical Sciences Department, Dstl Porton Down, Salisbury, Wilts SP4 0JQ, UK. clindsay@dstl.gov.uk Journal of applied toxicology : JAT (2004 Jan-Feb), 24(1), 37-46. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14745845 AN 2004044496 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to provide information about the degradative processes that occur in major connective tissue components in skin following exposure of large white pigs to Lewisite vapour. Of particular interest were alterations in glycoproteins, which are known to mediate dermo-epidermal attachment (laminin and type IV collagen) and the main collagen found in the dermis (type III collagen). The immunostaining of transfer blots from skin extracts run on sodium dodecyl sulphate polyacrylamide gel electrophoresis gels revealed no evidence of cross-linking of laminin or of type III or IV collagen. However, there was evidence of a very considerable degradation of laminin and, to a lesser extent, of type IV collagen. Type III collagen did not appear to be degraded in skin exposed to Lewisite. These degradative processes appeared to be more severe than found in previous studies in Yucatan mini-pigs percutaneously exposed to sulphur mustard, in which only laminin was found to undergo partial cleavage rather than wholesale degradation.The results suggest that damage to macromolecular components in the sub-epidermal basement membrane in skin which mediate dermo-epidermal separation processes may be a common feature in the mechanism of action of vesicating agents such as Lewisite and sulphur mustard. It is of interest that the damage to laminin in this study appeared to be more severe than that previously found for sulphur mustard. This suggests that skin can suffer substantial damage yet, in the case of Lewisite exposure, recover relatively quickly. However, Lewisite is not an alkylating agent. Sulphur mustard, in contrast, generates characteristically slow healing lesions, most probably because of its ability to alkylate cell types that normally would be involved in skin regenerative processes. Published by John Wiley & Sons, Ltd.

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Cardiovascular effects of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) decisive for its therapeutic efficacy in sarin poisoning. Joosen Marloes J A; Bueters Tjerk J H; van Helden Herman P M Research Group Medical Countermeasures, TNO Prins Maurits Laboratory, Lange Kleiweg 137, PO Box 45, 2280 AA Rijswijk, The Netherlands. joosen@pml.tno.nl Archives of toxicology (2004 Jan), 78(1), 34-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14508639 AN 2004043790 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Mortality and occurrence of cholinergic symptoms upon sarin intoxication (144 micro g/kg s.c., approximately 2 x LD50) in rats is completely prevented by treatment with the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA, 2 mg/kg i.m.). Previously, we have shown that CPA treatment altered the distribution of sarin into the brain, presumably through its cardiovascular side effects. Therefore, the objective of the present study was to evaluate the contribution of the cardiodepressant effects of CPA to its therapeutic efficacy against sarin intoxication. Intramuscular treatment of rats with 0.5 and 2.0 mg/kg CPA 1 min after sarin poisoning attenuated most cholinergic symptoms and prevented mortality, which seemed to be directly associated with an immediate strong and long-lasting bradycardia and hypotension caused by CPA. Treatment with lower doses of CPA (0.1 and 0.05 mg/kg i.m.) caused similar levels of bradycardia and hypotension, albeit a few minutes later than at the higher doses of CPA. Upon sarin intoxication, this was correlated with increased incidence of cholinergic symptoms and decreased survival rates. Pretreatment with the peripheral adenosine A1 receptor antagonist 8- p-sulphophenyltheophylline (8-PST, 20 mg/kg i.p.) counteracted the cardiodepressant effects of 0.05 mg/kg CPA almost completely, thereby nearly abolishing its therapeutic efficacy against sarin poisoning. In conclusion, the present results strongly indicate that bradycardia and hypotension induced by the peripheral adenosine A1 receptor play a prominent role in the therapeutic efficacy of CPA in cases of sarin poisoning.

Bibliographic Information

Effects of daily stress or repeated paraoxon exposures on subacute pyridostigmine toxicity in rats. Shaikh Jamaluddin; Karanth Subramanya; Chakraborty Dibyendu; Pruett Steve; Pope Carey N Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 264 McElroy Hall, OK 74078, Stillwater, USA Archives of toxicology (2003 Oct), 77(10), 576-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14574445 AN 2003495653 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Pyridostigmine (PYR) is a carbamate cholinesterase (ChE) inhibitor used during the Persian Gulf War as a pretreatment against possible chemical nerve agent attack. Because of its quaternary structure, PYR entry into the central nervous system is limited by the blood-brain barrier (BBB). Following reports of unexplained illnesses among Gulf War veterans, however, central nervous system effects of PYR have been postulated through either stress-induced alteration of BBB permeability or via interactions with other neurotoxic agents. We evaluated the effects of daily physical (treadmill running) stress or daily exposure to a subclinical dosage of the organophosphate ChE inhibitor paraoxon (PO) on ChE inhibition in blood, diaphragm and selected brain regions in young adult male Sprague-Dawley rats following subacute PYR exposures. In physical stress studies, rats were placed on a treadmill for 90 min each day for 14 days just prior to PYR (0, 3, or 10 mg/kg per day) administration. In PO-PYR interaction studies, rats were treated with PO (0, 0.05, or 0.1 mg/kg per day) 1 h prior to daily PYR (0 or 3 mg/kg per day) administration for 14 consecutive days. Rats were evaluated daily for signs of cholinergic toxicity and were killed 1 h after the final PYR treatment. Forced running increased plasma corticosterone levels throughout the experiment (on days 1, 3, 7 and 14) when measured immediately after termination of stress. PYR-treated rats in the high dosage (10 mg/kg per day) group exhibited slight signs of toxicity (involuntary movements) for the first 6 days, after which tolerance developed. Interestingly, signs of cholinergic toxicity following PYR were slightly but significantly increased in rats forced to run on the treadmill prior to dosing. ChE activities in whole blood and diaphragm were significantly reduced 1 h after the final PYR challenge, and ChE inhibition in diaphragm was significantly greater in stressed rats than in non-stressed controls following high dose PYR (10 mg/kg per day).
No significant effects of treadmill running on PYR-induced ChE inhibition in brain regions were noted, however. Repeated subclinical PO exposure had no apparent effect on functional signs of PYR toxicity. As with repeated treadmill running, whole blood and diaphragm ChE activities were significantly reduced 1 h after the final PYR administration, and ChE inhibition was significantly greater with combined PO and PYR exposures. Brain regional ChE activity was significantly inhibited after daily PO exposure, but no increased inhibition was noted following combined PO and PYR dosing. We conclude that, while some stressors may under some conditions affect functional signs of toxicity following repeated pyridostigmine exposures, these changes are likely to occur via alteration of peripheral cholinergic mechanisms and not through enhanced entry of pyridostigmine into the brain.

Bibliographic Information

Effects of sulfur mustard on transcription in human epidermal keratinocytes: analysis by mRNA differential display. Platteborze Peter L Pharmacology Division, USAMRICD, Aberdeen Proving Ground, MD 21010-5425, USA. Peter.Platteborze@det.amedd.army.mil Journal of applied toxicology : JAT (2003 Jul-Aug), 23(4), 249-54. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12884408 AN 2003350997 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This study examines the transcriptional response of human epidermal keratinocytes (HEK) to sulfur mustard (HD) in order to gain a better understanding of the intracellular events that result in cytotoxicity. Differential display polymerase chain reaction technology was used to examine the relative transcriptional activity of healthy cells to those exposed to subvesicating or vesicating concentrations of HD for 4 h. Approximately 2% of the HEK transcriptome had altered expression. Sixty of the most prominently altered transcripts were characterized. Important upregulated genes include NADH dehydrogenase III, GADD45 and ubiquitin. Key downregulated genes include type I keratin 14, alpha-enolase and caltractin. Many of the identified transcripts protein products presently do not have an assigned function and eleven transcripts were unidentifiable. These transcriptional alterations provide one of the first molecular insights into the intracellular events induced by HD. Published in 2003 by John Wiley & Sons, Ltd.

Bibliographic Information

Degradation of VX and sulfur mustard by enzymatic haloperoxidation. Amitai G; Adani R; Hershkovitz M; Bel P; Rabinovitz I; Meshulam H Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. amitai@ibr.gov.il Journal of applied toxicology : JAT (2003 Jul-Aug), 23(4), 225-33. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12884405 AN 2003350994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chloroperoxidase (CPO) isolated from Caldariomyces fumago (20 U ml(-1)) together with urea hydrogenperoxide (UPER, 0.5 mM) and sodium chloride as co-substrate (NaCl, 0.5 M) caused rapid breakdown of VX (10 microM) (t((1/2)) = 8 s, 25 C, 50 mM tartarate, pH 2.75). Glucose oxidase (GOX, Aspergillus niger) and glucose were used as an alternative source for H(2)O(2). A mixture of GOX (20 U ml(-1)), glucose (GLU 0.45 M), CPO (20 U ml(-1)) and NaCl (0.5 M) caused a 3.8-fold slower degradation of VX (10 microM) (t((1/2)) = 30 s, 25 C, 50 mM tartarate, pH 2.75). The concentrations of H(2)O(2) and chlorine produced by this enzyme/substrate mixture depended mainly on the GLU concentration. Horseradish peroxidase (HRP) together with UPER (1 mM) and sodium iodide (NaI, 0.05 M) caused progressive degradation of VX that was more than 400-fold slower than with CPO (20 U ml(-1)), UPER (0.5 mM) and NaCl (0.5 M) (t((1/2)) = 55 min, 25 C, pH 8). Skin decontamination of VX by CPO was tested in pig-ear skin in vitro. The chemical agent VX (0.01 M, 100 microl) was degraded by 98% within 3 h of skin diffusion when a mixture of UPER/NaCl/CPO was applied 60 min prior to VX application. A mixture of UPER/NaCl without CPO also caused significant VX degradation (94%) during skin diffusion whereas it did not cause any VX degradation in solution. Degradation of VX in skin, obtained without exogenous CPO, may indicate involvement of endogenous intradermal haloperoxidase-like enzyme. Reagent UPER (1 mM) did not cause any degradation of VX in solution or during its skin diffusion. Furthermore, a mixture of CPO, UPER and NaCl caused rapid degradation of sulfur mustard (HD). Sulfur mustard (50 microM) incubated in the presence of CPO (4 U ml(-1)), UPER (0.05 M) and NaCl (0.5 M) at pH 2.75 and 30 C was oxidized by 97% and 99% within 5 and 10 min, respectively. The oxidation products HD sulfoxide, HD sulfone and HD sulfoxidevinyl were identified by GC/MS in the enzymatic chloroperoxidation mixture. Copyright 2003 John Wiley & Sons, Ltd.

Bibliographic Information

Billion-fold acceleration of the methanolysis of paraoxon promoted by La(OTf)3 in methanol. Tsang Josephine S; Neverov Alexei A; Brown R S Department of Chemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6 Journal of the American Chemical Society (2003 Jun 25), 125(25), 7602-7. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12812502 AN 2003285652 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The methanolysis of the insecticide paraoxon (2) was investigated in methanol solution containing varying [La(OTf)(3)] (OTf = (-)OS(O)(2)CF(3)) as a function of at 25 degrees C. Plots of the pseudo-first-order rate constants (k(obs)) for methanolysis as a function of [La(OTf)(3)](total) were obtained under buffered conditions from 5.15 to 10.97, and the slopes of the linear parts of these were used to determine the second-order rate constants (k(2)(obs)) for the La(3+)-catalyzed methanolysis of 2. Detailed analysis of the potentiometric titration data of La(OTf)(3) in methanol through fits to a multicomponent equilibrium mixture of dimers of general stoichiometry La(3+)(2)((-)OCH3)n, where n assumes values of 1-5, gives the equilibrium distribution of each as a function of. These data, when fit to a second expression describing k(2)(obs) in terms of a linear combination of individual rate constants k(2)(2:1), k(2)(2:2).k(2)(2:)n for the dimers, allow one to describe the overall catalytic profile in terms of the individual contributions. The most catalytically important species are the three dimers La(3+)(2)((-)OCH3)1, La(3+)(2)((-)OCH3)2, and La(3+)(2)((-)OCH3)3. The catalysis of the methanolysis of 2 is spectacular: a 2 x 10(-3) M solution of [La(3+)](total), at neutral, affords a 10(9)-fold acceleration relative to the base reaction (t(1/2) approximately 20 s at 8.2) with excellent turnover. A mechanism of the catalyzed reaction involving the La(3+)(2)((-)OCH3)2 species is proposed.

Bibliographic Information

Putative role of proteolysis and inflammatory response in the toxicity of nerve and blister chemical warfare agents: implications for multi-threat medical countermeasures. Cowan F M; Broomfield C A; Lenz D E; Smith W J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. fred.cowan@amedd.army.mil Journal of applied toxicology : JAT (2003 May-Jun), 23(3), 177-86. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 12794939 AN 2003268101 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Despite the contrasts in chemistry and toxicity, for blister and nerve chemical warfare agents there may be some analogous proteolytic and inflammatory mediators and pathological pathways that can be pharmacological targets for a single-drug multi-threat medical countermeasure. The dermal-epidermal separation caused by proteases and bullous diseases compared with that observed following exposure to the blister agent sulfur mustard (2,2'-dichlorodiethyl sulfide) has fostered the hypothesis that sulfur mustard vesication involves proteolysis and inflammation. In conjunction with the paramount toxicological event of cholinergic crisis that causes acute toxicity and precipitates neuronal degeneration, both anaphylactoid reactions and pathological proteolytic activity have been reported in nerve-agent-intoxicated animals. Two classes of drugs already have demonstrated multi-threat activity for both nerve and blister agents. Serine protease inhibitors can prolong the survival of animals intoxicated with the nerve agent soman and can also protect against vesication caused by the blister agent sulfur mustard. Poly (ADP-ribose) polymerase (PARP) inhibitors can reduce both soman-induced neuronal degeneration and sulfur-mustard-induced epidermal necrosis. Protease and PARP inhibitors, like many of the other countermeasures for blister and nerve agents, have potent primary or secondary anti-inflammatory pharmacology. Accordingly, we hypothesize that drugs with anti-inflammatory actions against either nerve or blister agent might also display multi-threat efficacy for the inflammatory pathogenesis of both classes of chemical warfare agent.

Bibliographic Information

Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: influence of atropine dose. Taysse L; Calvet J-H; Buee J; Christin D; Delamanche S; Breton P Centre d'Etudes du Bouchet, Defense Research Centre, BP No. 3, Vert-Le-Petit 91710, France. laurent.taysse@ceb.etca.fr Toxicology (2003 Jun 30), 188(2-3), 197-209. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12767691 AN 2003245521 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This investigation compared the efficacy of diazepam and the water-soluble prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD(50) of sarin (s.c. route) and 1 min after intoxication treated by intramuscular injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiological parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were observed in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were observed. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not observed but 62.5% of the animals displayed respiratory difficulties. These symptoms were not observed when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concentration of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.

Bibliographic Information

Low-level sarin-induced alteration of immune system reaction in inbred BALB/c mice. Kassa Jiri; Krocova Z; Sevelova L; Sheshko V; Kasalova I; Neubauerova V Department of Toxicology, Purkyne Military Medical Academy, P.O. Box 35/T, 500 01 Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2003 May 3), 187(2-3), 195-203. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12699908 AN 2003232384 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

To study the influence of low-level sarin inhalation exposure on immune functions, inbred BALB/c mice were exposed to low concentrations of sarin for 60 min in the inhalation chamber. Two concentrations of sarin were chosen-asymptomatic concentration (LEVEL 1) and non-convulsive symptomatic concentration (LEVEL 2). The evaluation of immune functions was carried out using phenotyping of CD3 (T-lymphocytes), CD4 (helper T-lymphocytes), CD8 (cytotoxic T-lymphocytes) and CD19 cells (B-lymphocytes) in the lungs, blood and spleen, lymphoproliferation of spleen cells stimulated in vitro by various mitogens (concanavalin A, lipopolysaccharides), phagocyte activity of peritoneal and alveolar macrophages, production of N-oxides by peritoneal macrophages and the measurement of the natural killer cell activity at 1 week following sarin exposure. The results were compared to the values obtained from control mice exposed to pure air instead of sarin. The results indicate that not only symptomatic but also asymptomatic dose of sarin is able to alter the reaction of immune system at 1 week following exposure to sarin. While the number of CD3 cells in the lungs was slightly decreased, an increase in CD19 cells was observed especially in the lungs and blood. The reduced proportion of T-lymphocytes is caused by decay of CD4 positive T-cells. Lymphoproliferation was significantly decreased regardless of the mitogen and sarin concentration used. The production of N-oxides by peritoneal macrophages was stimulated after exposure to LEVEL 2 of sarin whereas their ability to phagocyte the microbes was increased after exposure to LEVEL 1. The natural killer cell activity was significantly higher in the case of inhalation exposure of mice to LEVEL 2 of sarin. Thus, not only organophosphorus insecticides but also nerve agents such as sarin are able to alter immune functions even at a dose that does not cause clinically manifested intoxication following the inhalation exposure.
Nevertheless, the alteration of immune functions following the inhalation exposure to a symptomatic concentration of sarin seems to be more pronounced.

Bibliographic Information

Nerve agents detection using a Cu2+/L-cysteine bilayer-coated microcantilever. Yang Yuming; Ji Hai-Feng; Thundat Thomas Department of Chemistry, Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272, USA Journal of the American Chemical Society (2003 Feb 5), 125(5), 1124-5. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12553787 AN 2003045046 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Bibliographic Information

Assessment of the effectiveness of downward water sprays for mitigating gaseous chlorine releases in partially confined spaces. Dimbour J P; Gilbert D; Dandrieux A; Dusserre G Ecole Nationale Superieure des Techniques Industrielles et des Mines d'Ales Laboratoire Genie de l'Environnement Industriel 6, Avenue de Clavieres, 30319 Cedex, Ales, France. jean-philippe.dimbour@ema.fr Journal of hazardous materials (2003 Jan 31), 96(2-3), 127-41. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12493204 AN 2002730858 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Water sprays are sometimes used as a means of mitigating accidental releases of chlorine gas. This paper gives results of a series of small-scale experimental field tests on the mitigation of chlorine gaseous releases (about 1kg/min) by various downward water sprays. The releases were from a cylinder of liquefied chlorine located in a storage shed. The shed could be configured to simulate confined and semi-confined installations used at public swimming pools. The water sprays were located in the shed. During these tests, different types of spray nozzles and storage configurations were tested under various atmospheric conditions, in order to select the best water spray. It was shown that the best chlorine downstream concentration reduction (factor 3-5 at 10m) was achieved with a flat fan water spray for the semi-confined configuration. Poor absorption in water was observed (<1%). The highest absorption (roughly 5%) was obtained with a fog water spray for the confined configuration. This is expected since chlorine is a low soluble gas. It has been evidenced for the confined configuration, that even if reduction of concentration has been observed (factor 2), downstream concentration remains very high (>10,000ppm), and above critical level of toxicity. Consequently, the use of water sprays in this case without additives to promote absorption seems to be inefficient.

[megalomania]

Chemical abstarcts is a wonderful tool. Using its subject area search feature I was able to find over 6000 journal articles about chemical warfare. Since most are irrevelant I weeded the articles down based on referenced CAS number, and then limited the search to those journals most likely to provide synthesis info. Here then are the results, about 350 articles worth:

505-60-2 (523 references)
107-44-8 (418 references)
96-64-0 (347 references)
50782-69-9 (290 references)
77-81-6 (161 references)
409-21-2 (156 references)
7732-18-5 (137 references)
756-79-6 (112 references)
51-55-8 (108 references)
7440-44-0 (96 references)
12033-89-5 (94 references)
993-13-5 (89 references)
9000-81-1 (89 references)
1344-28-1 (85 references)
81-81-2 (83 references)
541-25-3 (78 references)
311-45-5 (77 references)
34433-31-3 (74 references)
329-99-7 (73 references)
101-26-8 (70 references)
9001-08-5 (69 references)
1445-75-6 (68 references)
7782-44-7 (68 references)
1832-54-8 (67 references)
7440-70-2 (67 references)
1314-23-4 (66 references)
111-48-8 (65 references)
124-38-9 (65 references)
616-52-4 (64 references)
55-91-4 (61 references)
1832-53-7 (58 references)
7439-89-6 (53 references)
7631-86-9 (52 references)
67-56-1 (50 references)
630-08-0 (50 references)
7440-23-5 (50 references)
439-14-5 (48 references)
7440-50-8 (48 references)
693-07-2 (47 references)
75-44-5 (46 references)
7664-41-7 (46 references)
6735-59-7 (45 references)
7723-14-0 (44 references)
7440-09-7 (43 references)
7439-95-4 (41 references)
117698-12-1 (41 references)
7440-38-2 (40 references)
7727-37-9 (40 references)
64-17-5 (38 references)
7440-02-0 (37 references)

I know this is only 50 CAS numbers, the list was truncated :(

2003-April 2005

Bibliographic Information

Degradation Kinetics of VX on Concrete by Secondary Ion Mass Spectrometry. Williams, John M.; Rowland, Brad; Jeffery, Mark T.; Groenewold, Gary S.; Appelhans, Anthony D.; Gresham, Garold L.; Olson, John E. Battelle Salt Lake City Operations, West Valley City, UT, USA. Langmuir (2005), 21(6), 2386-2390. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 142:279785 AN 2005:130995 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At trace coverages on concrete surfaces, the nerve agent VX (O-Et S-2-diisopropylaminoethyl Me phosphonothiolate) degrades by cleavage of the P-S and S-C bonds, as revealed by periodic secondary ion mass spectrometry (SIMS). The obsd. kinetics were (pseudo-) first-order, with a half-life of 2-3 h at room temp. The rate increased with surface pH and temp., with an apparent second-order const. of kOH = 0.64 M-1 min-1 at 25 C and an activation energy of 50-60 kJ mol-1. These values are consistent with a degrdn. mechanism of alk. hydrolysis within the adventitious water film on the concrete surface. Degrdn. of bulk VX on concrete would proceed more slowly. Safety: VX must only be handled in approved chem. warfare surety labs. by trained agent chemists.

Bibliographic Information

The pharmacokinetics and pharmacodynamics of two HI-6 salts in swine and efficacy in the treatment of GF and soman poisoning. Lundy, Paul M.; Hill, Ira; Lecavalier, Pierre; Hamilton, Murray G.; Vair, Cory; Davidson, Corey; Weatherby, Kendal L.; Berger, Bradley J. Chemical Biological Defence Section, Defence Research and Development Canada - Suffield, Medicine Hat Alberta, AB, Can. Toxicology (2005), 208(3), 399-409. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. AN 2005:107852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anesthetized pigs were injected i.m. with 500 mg HI-6 dichloride (HI-6 2Cl) (1-[[[4-(aminocarbonyl)-pyridinio]methoxy]methyl]-2[(hydroxyimino)methyl]pyridinium dichloride; CAS 34433-31-3)) or the molar equivalent of HI-6 dimethanesulfonate (HI-6 DMS) 633 mg. Plasma HI-6 concns. were measured by HPLC (1, 3, 5, 10, 15, 30, 60 min and every 30 min until 4 h or 6 h following the i.v. or i.m. dose resp.) while a variety of physiol. responses were continuously examd. HI-6 (500 mg 2Cl or 633 mg DMS) resulted in an identical pharmacokinetic profile unaffected by atropine co-administration. Neither HI-6 salt resulted in clin. significant changes in cardiovascular or respiratory function. HI-6 DMS (1899 mg i.v.) resulted in plasma HI-6 concns. about 10 times higher than measured following i.m. 500 mg 2Cl or 633 mg DMS and resulted in small transitory effect on mean arterial pressure. Atropine plus HI-6 DMS (1-9 mg/kg or 127-172 mg/kg i.m.) protected up to 100% of guinea pigs exposed to 5  LD50 of GF (cyclohexyl Me phosphonoflouridate) or soman (pinacolyl methylphosphonofluoridate) (GD) resp. The results suggest that the two HI-6 salts have a similar pharmacokinetic profile while HI-6 DMS appears extremely safe and effective against nerve agents and may be as suitable for human use.

Bibliographic Information

Antidotal treatment of GF-agent intoxication in mice with bispyridinium oximes. Sevelova, Lucie; Kuca, Kamil; Krejcova-Kunesova, Gabriela. Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2005), 207(1), 1-6. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 142:213533 AN 2004:1067008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It was shown that intoxications with GF-agent are rather resistant to convential oxime therapy; therefore, the development of new oximes in an effort to improve this unsatisfactory situation continues. Upon screening in vitro reactivation test for oximes, that were either newly synthesized at our department, or those that have never been tested for reactivation of GF-inhibited acetylcholinesterase (AChE), three oximes {(1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide) (K033); (1-(2-hydroxyiminomethylpyridinium)-3-(3-carbamoylpyridinium)-2-oxa-propane dichloride) (HS-6); and (1-(2-hydroxyiminomethylpyridinium)-4-(4-carbamoylpyridinium)-but-2-ene dibromide) (BI-6)} with the highest reactivation potency were chosen for in vivo testing in our study. (1,3-Bis(4-hydroxyiminomethylpyridinium)-2-oxa-propane dibromide) (obidoxime); (1-(2-hydroxyiminomethylpyridinium)-3-(4-carbamoylpyridinium)-2-oxa-propane dichloride) (HI-6); and (1,1-bis(4-hydroxyiminomethylpyridinium)-methane dibromide) (methoxime) were chosen for comparison as a std. antidotal treatment. All the oximes were applied at the same proportion of their LD50 value (5%), and because of the different acute toxicity of the oximes, the molar concns. of their solns. for i.m. administration were considerably different. The highest therapeutic ratio was achieved for therapeutic regimen consisting of HI-6 and atropine. The significantly (P < 0.05) lowest effectivity in treatment of supralethal GF-agent poisoning in comparison with all the other therapeutic regimens, was surprisingly obsd. for methoxime. HS-6, K033 and BI-6 as well as obidoxime were comparably effective antidotes against GF-agent intoxication and their therapeutic ratios were similar.

Bibliographic Information

Bis(dialkylamide)hydrogen Dibromobromate Precursors of Hypobromite Ion in Reactions with Nerve and Blister Agent Simulants. Simanenko, Yuri S.; Savelova, Vera A.; Prokop'eva, Tatyana M.; Mikhailov, Vasily A.; Turovskaya, Marya K.; Karpichev, Eugen A.; Popov, Anatolii F.; Gillitt, Nicholas D.; Bunton, Clifford A. L.M. Litvinenko Institute of Physical Organic Coal Chemistry, National Academy of Sciences of Ukraine, Donetsk, Ukraine. Journal of Organic Chemistry (2004), 69(26), 9238-9240. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 142:108643 AN 2004:949799 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hypobromite ion, BrO-, is an effective -nucleophile that reacts rapidly with activated phosphorus(V) and sulfonate esters. The parent acid rapidly oxidizes org. sulfides and aryloxide ions. At pH 10-11 BrO- and HOBr coexist in water and are potentially useful as decontaminants of chlorosulfide blister agents and the phosphonyl nerve agents. Bis(dialkylamide)hydrogen dibromobromates are well characterized, stable, solids which rapidly form HOBr-BrO- in mildly alk. water. Reactions of 4-nitrophenyl di-Et phosphate and phosphonate, which are simulants of the phosphonofluoridate nerve agents, and of 4-nitrophenyl tosylate, with BrO- are rapid (t1/2 = 60-700 s) with 0.1 M BrO-, under conditions in which oxidns. of org. sulfides are too fast to be followed by conventional methods.

Bibliographic Information

Localization of substance P gene expression for evaluating protective countermeasures against sulfur mustard. Casbohm, Stacy L.; Rogers, James V.; Stonerock, Mindy K.; Martin, Jamie L.; Ricketts-Kaminsky, Karen M.; Babin, Michael C.; Casillas, Robert P.; Sabourin, Carol L. K. Medical Research and Evaluation Facility, Battelle Memorial Institute, Columbus, OH, USA. Toxicology (2004), 204(2-3), 229-239. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:421169 AN 2004:789078 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard [bis(2-chloroethyl)sulfide; SM] is a chem. warfare agent that produces edema and blister formation with a severe inflammatory reaction. The mouse ear vesicant model for SM injury has been used to evaluate pharmacol. agents for countering SM dermal injury. The vanilloid olvanil reduces SM-induced edema and mRNA expression of cytokines and chemokines, suggesting that blocking the inflammatory effects of neuropeptides, such as substance P (SP), may provide protection against SM-induced dermal injury. This study examd. SP expression in mice exposed to SM (0.16 mg) on the inner surface of the right ear, with or without olvanil pretreatment at 1, 10, 30, 60, and 360 min following exposure. In naive skin, SP mRNA localization was assocd. with blood vessels and sebaceous glands. In SM-exposed skin, SP mRNA was also detected in perivascular dermal cells. Immunohistochem. localization of SP protein was obsd. in the ear skin of naive, SM-, olvanil/SM-, and vehicle-treated mice. Quantification of SP+ perivascular dermal cells revealed that SM exposure led to a significant increase (P  0.05) in SP+ cells over the obsd. time period. Olvanil pretreatment significantly reduced (P  0.05) the mean no. of SP+ cells at 60 and 360 min. This study demonstrates that SP expression could provide an addnl. endpoint for evaluating the effectiveness of vanilloid drugs on SM-induced skin inflammation.

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Photocatalytic oxidation of VX simulant 2-(butylamino)ethanethiol. Vorontsov, Alexandre V.; Chen, Yi-Chuan; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russian Federation, Russia. Journal of Hazardous Materials (2004), 113(1-3), 89-95. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 141:383605 AN 2004:745354 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Photocatalytic oxidn. of 2-(butylamino)ethanethiol (BAET) was undertaken in aq. suspension of TiO2 Hombikat UV 100 and Degussa P25 under different initial reaction conditions in order to det. the best parameters for the fastest mineralization of the substrate. BAET is considered to be a simulant for the VX chem. warfare agent. The application of ultrasound had only a small pos. effect on the BAET photocatalytic degrdn. The highest mineralization rate of 0.433 mg/L-min was found in unbuffered TiO2 Degussa P25 suspension with initial pH of .apprx.9.4, TiO2 concn. 500 mg/L and the initial BAET concn. 1000 mg/L. Decreasing of the initial soln. pH to 6.1 stops the mineralization of BAET while increasing of pH to .apprx.11 drastically changed the degrdn. profile. At this initial pH, the 1st 100 min of reaction led to only oxidn. of S moiety and org. intermediates accumulated in the soln. Thereafter, mineralization of the products started. The main detected volatile product was Bu aldehyde and the main polar one was 2-(butylamino)acetic acid. In the case of TiO2 Hombikat UV 100, conversion of TOC at initial pH 11 exceeded that at initial pH 9.1. For Degussa P25, the starting pH 9.4 was the best for TOC conversion. The results can be used for the treatment of water and wastewater.

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Synthesis and Chemosensory Behavior of Anthracene Bisimide Derivatives. Ilhan, Faysal; Tyson, Daniel S.; Meador, Michael A. Polymers Branch Materials Division, NASA Glenn Research Center, Cleveland, OH, USA. Chemistry of Materials (2004), 16(16), 2978-2980. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 141:268374 AN 2004:559158 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors used the photoenolization reaction of a dibenzoyl-p-xylene deriv. to synthesize two new, highly substituted anthracene-based mols.: N,N'-bis(p-nitrophenyl)-1,5-bis(p-(tetraethyleneglycoloxy)phenyl)anthracene-2,3,6,7-tetracarboxyl bis-imide (ABI-NO2) and N,N'-bis(p-aminophenyl)-1,5-bis(p-(tetraethyleneglycoloxy)phenyl)anthracene-2,3,6,7-tetracarboxyl bis-imide (ABI-NH2). ABI-NO2 and ABI-NH2 maintained photostability with longer wavelength absorption and emission spectra as compared to unsubstituted anthracene. Conversion of the terminal nitro groups to amines created an internal photoinduced electron-transfer that quenched the luminescence of ABI-NH2. Reversible or irreversible reaction of the attached amines resulted in fluorescence recovery. Sensitivity, of ABI-NH2 and other potential derivs., to toxic chems. may prove useful for early detection systems. Electronic supplementary information (ESI) is available at http://pubs.acs.org and contains synthetic prepns. of the ABI-NO2 and ABI-NH2 compds.

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Dimethyl Methylphosphonate Decomposition on Titania-Supported Ni Clusters and Films: A Comparison of Chemical Activity on Different Ni Surfaces. Zhou, J.; Ma, S.; Kang, Y. C.; Chen, D. A. Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA. Journal of Physical Chemistry B (2004), 108(31), 11633-11644. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 141:195800 AN 2004:528273 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The thermal decompn. of di-Me methylphosphonate (DMMP) has been studied in ultrahigh vacuum by temp. programmed desorption (TPD) and XPS on Ni clusters and films deposited on TiO2(110). The four different Ni surfaces under investigation consisted of small Ni clusters (5.0  0.8 nm diam., 0.9  0.2 nm height) deposited at room temp. and quickly heated to 550 K, large Ni clusters (8.8  1.4 nm diam., 2.3  0.5 nm height) prepd. by annealing to 850 K, a 50 monolayer Ni film deposited at room temp., and a 50 monolayer Ni film annealed to 850 K. The morphologies of the Ni surfaces were characterized by scanning tunneling microscopy (STM). TPD expts. show that CO and H2 are the major gaseous products evolved from the decompn. of DMMP on all of the Ni surfaces, and mol. DMMP and methane desorption were also obsd. The product yields for CO and H2 were highest for reactions on the small Ni clusters and unannealed Ni film and lowest for reactions on the large clusters and annealed film. Furthermore, XPS expts. demonstrate that the unannealed Ni surfaces decomp. a greater fraction of DMMP at room temp. The loss of activity for the annealed surfaces is not caused by a redn. in surface area because the annealed surfaces have approx. the same surface area as the small clusters. CO adsorption studies suggest that the loss of activity upon annealing cannot be completely due to a decrease in surface defects, such as step and edge sites, and we propose that a TiOx moiety is responsible for blocking active sites on the annealed Ni surfaces. In comparison to the TiO2 surface, the small Ni clusters are more chem. active because a greater fraction of DMMP decomps. at room temp., and the total amt. of DMMP decompn. is also higher on the small Ni clusters. Although DMMP decomps. on TiO2 to produce gaseous Me radicals, methane, and H2, the activity of the substrate surface itself appears to be quenched in the presence of the Ni clusters and films.
However, the TiO2 support plays a significant role in providing a source of oxygen for the recombination of at. carbon on Ni to form CO, which desorbs above 800 K.

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Reductive Destruction of Chemical Warfare Agent Simulants in Water. Kiddle, James J.; Mezyk, Stephen P. Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA. Journal of Physical Chemistry B (2004), 108(28), 9568-9570. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 141:194628 AN 2004:479880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The efficient detection, decontamination, and destruction of chem. warfare (CW) agents remain an active area of scientific research. Rate consts. for the reaction of substituted di-Et phosphates and phosphonates with the hydroxyl radical and hydrated electron have been measured in water to elucidate the primary destruction pathway for the CW agents Tabun (GA), Sarin (GB), Soman (GD), and VX with these two species. The measured kinetics for simulants with leaving groups that more closely mimic these actual CW agents predict that reductive destruction will be the most efficient mechanism, and that nontoxic simulants such as alkyl phosphonates undergo different redox chem.

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Detect-to-warn cell based sensing technology: Chemical sensing of multiple agents in a cascade. Zhang, Xuan; Yang, Mo; Kohr, Bonnie; Morgan, Andre; Ozkan, Cengiz S. Mechanical Engineering Department, University of California, Riverside, CA, USA. Materials Research Society Symposium Proceedings (2004), EXS-1(Architecture and Application of Biomaterials and Biomolecular Materials), 187-195. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:119751 AN 2004:469459 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Techniques to develop highly sensitive biosensors are largely dependent upon the properties of the material and its assocd. interactions. A novel challenge is the development of effective biosensors based on fundamental research in biotechnol., genetics and information technol., which will change the existing axiom of "detect -to-treat" to "detect -to-warn". Current biosensor technologies encompass antibody-antigen interactions, hormone-receptor interactions, and nucleic acid based assays. These sensors are useful in narrow band applications requiring high specificity for agent identification. Mammalian cells have excitable cell membranes that function as novel sensing platforms by producing a variation in the extracellular potential based on the chem. stimulus. Here we report a method of developing single cell based sensors by integrating the biol. tool of dielectrophoresis with the micro fabrication technol. We display its ability to detect a large no. of chem. agents, reject false alarms, characterize the chem. agent functionality and det. the assocd. sensitivity limit, and the physiol. response in terms of the calcium transients for each specific chem. agent that produces synergistic effects on humans. We finally demonstrate the capability of a single cell based sensor to identify general chem. agents in cascade.

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Preparation, Derivatization with Trimethylsilyldiazomethane, and GC/MS Analysis of a "Pool" of Alkyl Methylphosphonic Acids for Use as Qualitative Standards in Support of Counterterrorism and the Chemical Weapons Convention. Crenshaw, Michael D.; Cummings, David B. Battelle Memorial Institute, Columbus, OH, USA. Phosphorus, Sulfur and Silicon and the Related Elements (2004), 179(6), 1009-1018. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 141:225604 AN 2004:460857 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

There are hundreds of nerve agents in the class of alkyl methylphosphonofluoridates covered by Schedule 1 of the CWC (Chem. Weapons Convention). Hydrolysis of these sarin-like nerve agents results in an equal no. of alkyl methylphosphonic acids. These alkyl methylphosphonic acids are persistent and provide good evidence of specific agent prodn. or use. To support the CWC and counterterrorism activities, it is desirable to have ready access to each of these hydrolysis products for use as qual. stds. A means for simultaneously producing multiple alkyl methylphosphonates from methylphosphonic acid, phenylarsonic acid and the corresponding alcs. was developed. Derivatization of these alkyl methylphosphonic acids with trimethylsilyldiazomethane yields the corresponding Me esters which are suitable for GC/MS anal.

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MBE grown AlN films on SiC for piezoelectric MEMS sensors. Doppalapudi, Dharanipal; Mlcak, Richard; Chan, Jeffrey; Tuller, Harry; Bhattacharya, Anirban; Moustakas, Theodore. Boston MicroSystems Inc., Woburn, MA, USA. Materials Research Society Symposium Proceedings (2004), 798(GaN and Related Alloys--2003), 403-408. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:132159 AN 2004:423724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Miniaturized piezoelec. sensors based on Microelectromech. Systems (MEMS) offer the advantages of reduced size, reduced power consumption, increased sensitivity coupled with the ability to form compact multi-sensor arrays. Fabrication of such sensors from single crystal materials further insure more highly reproducible and stable devices with improved performance. The authors describe the integration of MBE grown AlN films onto photoelectrochem. machined SiC microcantilevers and membranes. AlN exhibits excellent piezoelec. properties, including an electromech. coupling coeff. of 0.088 and a high in-plane acoustic velocity (.apprx.5700 m/s) as well as excellent thermal-mech. compatibility with SiC. The fabrication of AlN-SiC-based microresonators and flexural plate wave devices, and their application to chem., biol. and fluid sensing, are reported.

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Biochemical changes in mouse lung after subcutaneous injection of the sulfur mustard 2-chloroethyl 4-chlorobutyl sulfide. Elsayed, Nabil M.; Omaye, Stanley T. Hurley Consulting Associates, Department of Scientific Affairs, Chatham, NJ, USA. Toxicology (2004), 199(2-3), 195-206. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:237904 AN 2004:404473 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant-type chem. warfare agent (CWA) introduced in World War I which continues to be produced, stockpiled, and occasionally deployed by some countries, and could be used potentially by terrorists. Exposure to HD can cause erythema, blisters, corneal opacity, and airway damage. The authors have reported previously that s.c. (SC) injection of immunodeficient athymic nude mice with the half mustard Bu 2-chloroethyl sulfide (BCS) causes systemic biochem. changes in several organs distal to the exposure site. In the present study, the authors examd. the response of nonimmunodeficient Swiss Webster mice to the mustard, 2-chloroethyl 4-chlorobutyl sulfide (CECBS). In a pilot study, a single SC injection of 20-25 L/mouse caused death within 24 h. Consequently, the authors used 5 L/mouse (.apprx.0.017 mg/kg body wt.) of neat CECBS or an equal vol. of saline as control. The authors examd. lungs after 1, 24, and 48 h for biochem. changes including total and oxidized glutathione, protein, DNA, and lipid peroxidn. contents in tissue homogenate, and superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, and glutathione S-transferases activities in the cytosol. After 1 and(or) 24 h, significant changes were found that were resolved by 48 h. These changes mimicked those of HD and BCS and were generally consistent with free radical-mediated oxidative stress. The implications of these observations are 2-fold. First, dermal exposure to low-dose mustard gas could elicit systemic changes impacting distal organs such as the lungs. It also suggests that antioxidants could potentially modulate the response and reduce the damage. Second, although the use of known CWAs such as HD is prohibited, analogs that are not recognized as agents are as toxic and could be dangerous if acquired and used by potential terrorists.

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A thermo-chemical surface treatment of AlN powder for the aqueous processing of AlN ceramics. Olhero, S. M.; Novak, S.; Oliveira, M.; Krnel, K.; Kosmac, T.; Ferreira, J. M. F. Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro, Port. Journal of Materials Research (2004), 19(3), 746-751. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 141:41662 AN 2004:346050 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Dense aluminum nitride ceramics were prepd. by sintering green bodies at 1750C for 2 h. These green bodies were prepd. by aq. slip-casting from a powder that was surface-treated to prevent hydrolysis. The surface treatment of the aluminum nitride (AlN) powder consisted of dispersing the powder in warm-water solns. of aluminum dihydrogenphosphate Al(H2PO4)3. Different treatment temps. in the range 30-80C were tested. For all the tested temps., the surface-treated AlN powder was found to be water-resistant, even after drying and/or redispersion. Various com. dispersants were tested for their effectiveness, and the amt. of dispersant was optimized in terms of a high solids loading of the suspension and an acceptable viscosity for slip casting. Based on these studies, a stable aq. suspension of AlN powder, treated at 60C, with a total solids loading of 50 vol%, was prepd. using CaF2 as a sintering additive. The well-dispersed powder made it possible to prep. green samples with close particle packing and relatively high sintered densities, i.e., >96%.

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Progress in developing nerve agent sensors using combinatorial techniques. DiCesare, John C.; Parker, Jennifer; Horne, Starr N.; Kita, Justin; Earni, Raghu; Peeples, Christopher. Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK, USA. Materials Research Society Symposium Proceedings (2004), Volume Date 2003, 787(Molecularly Imprinted Materials--2003), 17-22. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:201377 AN 2004:280892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Development of a sensor capable of selective detection of specific nerve agents is imperative in today's atm. of terrorism. The sensor needs to be inexpensive, portable, reliable, absent of false positives and available to all military and first responders. By utilizing the techniques of mol. imprinting, combinatorial chem., silica sol-gel synthesis and lanthanide luminescence, a sensor for the detection of the hydrolysis product of the nerve agent soman is being developed. There are many parameters that require investigation in order for the sensor to become a reality. These parameters include (1) the selection of a chelate that can bind to the lanthanide and anchor the nerve agent simulant during the formation of the molecularly imprinted polymer, (2) the detn. of the environment best suited for this complex formation, (3) the formation, as well as modification of the silica sol-gel for mol. imprinting to take place, and (4) the proper quantity and ratios of monomers used to create the three dimensional imprint. Key to the success of optimizing these parameters is the development of a combinatorial assay that allows for the synthesis and testing of tens of thousands of combinations of parameters. Work on the development of the combinatorial assay has lead to a method of prepg. thin film polymers capable of analyzing the presence of nerve agent simulants. Current work is underway to validate the combinatorial assay and to synthesize and evaluate a library of sensor materials selective for nerve agents.

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Synthesis and adsorption properties of intimately intermingled mixed metal oxide nanoparticles. Medine, Gavin M.; Zaikovskii, Vladimir; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2004), 14(4), 757-763. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 140:359698 AN 2004:131545 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A series of intimately intermingled mixed metal oxide nanoparticles were prepd. via a modified aerogel procedure (MAP). These mixed oxides were composed of alk. earth oxides and aluminas. It was found that the surface area and reactivity of these materials decreased on going from magnesium to barium in these intimately intermingled metal oxides. The samples were analyzed by HRTEM and the images obtained illustrate the degree of mixing throughout each of the intermingled mixed metal oxides. As well as synthesizing and characterizing these samples, standardized adsorption tests were also carried out and compared to those of individual metal oxide nanoparticles and phys. mixts. of metal oxide nanoparticles. The following tests have been shown to be effective in detg. the adsorption properties of metal oxide nanoparticles: (i) destructive adsorption of paraoxon (a surrogate of the chem. warfare nerve agent, VX) and (ii) the adsorption of acid gases. The data clearly show enhanced kinetics and capacities for the intermingled AP-MgAl2O4 and indeed, the data suggest that surface reactivities can be tailored by the aerogel mixing process.

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Examination of changes in connective tissue macromolecular components of large white pig skin following application of Lewisite vapour. Lindsay, Christopher D.; Hambrook, Joy L.; Brown, Roger F. R.; Platt, Jan C.; Knight, Robert; Rice, Paul. Biomedical Sciences Department, Salisbury, UK. Journal of Applied Toxicology (2004), 24(1), 37-46. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 140:316407 AN 2004:99102 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to provide information about the degradative processes that occur in major connective tissue components in skin following exposure of large white pigs to Lewisite vapor. Of particular interest were alterations in glycoproteins, which are known to mediate dermo-epidermal attachment (laminin and type IV collagen) and the main collagen found in the dermis (type III collagen). The immunostaining of transfer blots from skin exts. run on SDS-PAGE gels revealed no evidence of crosslinking of laminin or of type III or IV collagen. However, there was evidence of a very considerable degrdn. of laminin and, to a lesser extent, of type IV collagen. Type III collagen did not appear to be degraded in skin exposed to Lewisite. These degradative processes appeared to be more severe than found in previous studies in Yucatan mini-pigs percutaneously exposed to sulfur mustard, in which only laminin was found to undergo partial cleavage rather than wholesale degrdn. The results suggest that damage to macromol. components in the sub-epidermal basement membrane in skin which mediate dermo-epidermal sepn. processes may be a common feature in the mechanism of action of vesicating agents such as Lewisite and sulfur mustard. It is of interest that the damage to laminin in this study appeared to be more severe than that previously found for sulfur mustard. This suggests that skin can suffer substantial damage yet, in the case of Lewisite exposure, recover relatively quickly. However, Lewisite is not an alkylating agent. Sulfur mustard, in contrast, generates characteristically slow healing lesions, most probably because of its ability to alkylate cell types that normally would be involved in skin regenerative processes.

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In vitro-in vivo extrapolation: estimation of human serum concentrations of chemicals equivalent to cytotoxic concentrations in vitro. [Erratum to document cited in CA139:346894]. Gulden, Michael; Seibert, Hasso. Institut fur Experimentelle Toxikologie, Universitatsklinikum Schleswig-Holstein, Kiel, Germany. Toxicology (2003), 192(2-3), 265. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:152304 AN 2003:826065 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Equation (6) should read: EC50 = ECu50  (1 + KOW  V'L, in vitro) + Cbin vitro. The cor. version of Table 2 is given.

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Solid-Phase Synthesis of Some Alkyl Hydrogen Methylphosphonates. Barucki, Hubert; Black, Robin M.; Kinnear, Kenneth I.; Holden, Ian; Read, Robert W.; Timperley, Christopher M. Defence Science and Technology Laboratory, Wiltshire, UK. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(10), 2279-2286. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 141:23606 AN 2003:764571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Eleven alkyl H methylphosphonates of structure RO(HO)P(O)Me (R = Me, Et, Pr, i-Pr, Bu, hexyl, octyl, cyclohexyl, cycloheptyl, cyclooctyl, and Me3CCH(Me)) were made by phosphoramidite chem. on hydroxymethyl polystyrene resin with yields 30%. MeP(NiPr2)Cl was attached to hydroxymethyl polystyrene using Et3N in CH2Cl2 to give MeP(NiPr2)OCH2-bound polystyrene, which was reacted with various alcs. in MeCN in the presence of tetrazole followed by oxidn. using tBuO2H in toluene; the final product was cleaved from MeP(O)(OR)OCH2-bound resin using CF3CO2H. NCCH2CH2OP(OR)O2H (R = Et iPr) were also prepd. via solid-phase synthesis.

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Effects of sulfur mustard on transcription in human epidermal keratinocytes: Analysis by mRNA differential display. Platteborze, Peter L. Pharmacology Division, USAMRICD, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2003), 23(4), 249-254. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 139:360142 AN 2003:619968 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study examines the transcriptional response of human epidermal keratinocytes (HEK) to sulfur mustard (HD) in order to gain a better understanding of the intracellular events that result in cytotoxicity. Differential display polymerase chain reaction technol. was used to examine the relative transcriptional activity of healthy cells to those exposed to subvesicating or vesicating concns. of HD for 4 h. Approx. 2% of the HEK transcriptome had altered expression. Sixty of the most prominently altered transcripts were characterized. Important upregulated genes include NADH dehydrogenase III, GADD45 and ubiquitin. Key downregulated genes include type I keratin 14, -enolase and caltractin. Many of the identified transcripts protein products presently do not have an assigned function and eleven transcripts were unidentifiable. These transcriptional alterations provide one of the first mol. insights into the intracellular events induced by HD.

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Degradation of VX and sulfur mustard by enzymatic haloperoxidation. Amitai, G.; Adani, R.; Hershkovitz, M.; Bel, P.; Rabinovitz, I.; Meshulam, H. Division of Medicinal Chemistry, Israel Institute for Biological Research, Ness Ziona, Israel. Journal of Applied Toxicology (2003), 23(4), 225-233. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 140:72285 AN 2003:619965 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chloroperoxidase (CPO) isolated from Caldariomyces fumago (20 U ml-1) together with urea hydrogenperoxide (UPER, 0.5 mM) and sodium chloride as co-substrate (NaCl, 0.5 M) caused rapid breakdown of VX (10 M) (t1/2=8 s, 25, 50 mM tartarate, pH 2.75). Glucose oxidase (GOX, Aspergillus niger) and glucose were used as an alternative source for H2O2. A mixt. of GOX (20 U ml-1), glucose (GLU 0.45 M), CPO (20 U ml-1) and NaCl (0.5 M) caused a 3.8-fold slower degrdn. of VX (10 M) (t1/2=30 s, 25, 50 mM tartarate, pH 2.75). The concns. of H2O2 and chlorine produced by this enzyme/substrate mixt. depended mainly on the GLU concn. Horseradish peroxidase (HRP) together with UPER (1 mM) and sodium iodide (NaI, 0.05 M) caused progressive degrdn. of VX that was more than 400-fold slower than with CPO (20 U ml-1), UPER (0.5 mM) and NaCl (0.5 M) (t1/2=55 min, 25, pH 8). Skin decontamination of VX by CPO was tested in pig-ear skin in vitro. The chem. agent VX (0.01 M, 100 l) was degraded by 98% within 3 h of skin diffusion when a mixt. of UPER/NaCl/CPO was applied 60 min prior to VX application. A mixt. of UPER/NaCl without CPO also caused significant VX degrdn. (94%) during skin diffusion whereas it did not cause any VX degrdn. in soln. Degrdn. of VX in skin, obtained without exogenous CPO, may indicate involvement of endogenous intradermal haloperoxidase-like enzyme. Reagent UPER (1 mM) did not cause any degrdn. of VX in soln. or during its skin diffusion. Furthermore, a mixt. of CPO, UPER and NaCl caused rapid degrdn. of sulfur mustard (HD). Sulfur mustard (50 M) incubated in the presence of CPO (4 U ml-1), UPER (0.05 M) and NaCl (0.5 M) at pH 2.75 and 30 was oxidized by 97% and 99% within 5 and 10 min, resp. The oxidn. products HD sulfoxide, HD sulfone and HD sulfoxidevinyl were identified by GC/MS in the enzymic chloroperoxidn. mixt.

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Analysis of Chemical Neutralization Products of Phosphonothiolates by Gas Chromatography Mass Spectrometry. Gupta, A. K.; Palit, M.; Dubey, D. K.; Raza, S. K. Defence Research & Development Establishment, Gwalior, India. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(8), 1631-1637. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 140:303747 AN 2003:603631 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A series of phosphonothioates, including the highly toxic O-Ethyl-S-(2-diisopropylamino) Et methylphosphonothioate (VX), were subjected to chem. neutralization reaction with metallic sodium; the reaction products were identified by GC/MS. The phosphonothioates decomp. to their resp. phosphonic and phosphonothioic acids and this results in the detoxification of VX. Phosphonodithioates R1PO(SR2)2 (2-8; R1 = Me, Et, n-Pr, iPr; R2 = Bu, n-Pr) were reacted with metallic sodium, giving disulfides R2SSR2 and R1PS(OH)2. Trithioate MePS(SPr)2 (9) upon reaction with Na gave polysulfides R2SSR2, R2SSSR2 and R2SSSSR2 (R2 = n-Pr); MePO(OH)2 and MePS(OH)2. All obtained acids were analyzed by GC/MS in the form of their trimethylsilyl esters. GC/MS technique in both EI and CI mode was applied for reaction monitoring and final identification of the neutralization products formed in this reaction.

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Kinetics of Spontaneous Hydrolysis of O-(2,2-Dimethylcyclopentyl)-methylfluorophosphonate and of Hydrolysis During Constant pH Value of the Reaction Medium. Cekovic, Boban; Jovanovic, Bratislav; Lukovic, Zoran. Military Technical Institute, Belgrade, Yugoslavia. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(7), 1521-1540. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 140:253619 AN 2003:524831 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Kinetics of hydrolysis of O-(2,2-dimethylcyclopentyl)-methylfluorophosphonate (1) in dil. aq. soln. was investigated. Rates of hydrolysis of O-(2,2-dimethylcyclopentyl)-methylfluorophosphonate were measured as a function of pH in the range from 3 to 9 in temp. range from 25 to 40. Spontaneous hydrolysis was also studied without monitoring of the pH-value. Rate consts. and activation parameters of the hydrolysis were obtained. The lowest hydrolysis rates for 1 were obtained at pH range 4-6, the reaction was several times faster at pH 3.0 and more than ten times faster at pH 9.0. For dild. solns. the spontaneous hydrolysis had half-life time (t1/2) about 2.8 days at 25, the reaction may be accelerated in more concd. solns. due to proton autocatalysis. Obtained data can be used in processes of degrdn. and detoxification of highly toxic warfare-type compds.

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Enhanced Degradation of Chemical Warfare Agents through Molecular Engineering of the Phosphotriesterase Active Site. Hill, Craig M.; Li, Wen-Shan; Thoden, James B.; Holden, Hazel M.; Raushel, Frank M. Department of Chemistry, Texas A&M University, College Station, TX, USA. Journal of the American Chemical Society (2003), 125(30), 8990-8991. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 139:208973 AN 2003:516949 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The bacterial phosphotriesterase has been utilized as a template for the evolution of improved enzymes for the catalytic decompn. of organophosphate nerve agents. A combinatorial library of active site mutants was constructed by randomizing residues His-254, His-257, and Leu-303. The collection of mutant proteins was screened for the ability to hydrolyze a chromogenic analog of the most toxic stereoisomer of the chem. warfare agent, soman. The mutant H254G/H257W/L303T catalyzed the hydrolysis of the target substrate nearly 3 orders of magnitude faster than the wild-type enzyme. The x-ray crystal structure was solved in the presence and absence of diisopropyl Me phosphonate. The mutant enzyme was ligated to an addnl. divalent cation at the active site that was displaced upon the binding of the substrate analog inhibitor. These studies demonstrate that substantial changes in substrate specificity can be achieved by relatively minor changes to the primary amino acid sequence.

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In vitro-in vivo extrapolation: estimation of human serum concentrations of chemicals equivalent to cytotoxic concentrations in vitro. Gulden, Michael; Seibert, Hasso. Institut fur Experimentelle Toxikologie, Universitatsklinikum Schleswig-Holstein, Kiel, Germany. Toxicology (2003), 189(3), 211-222. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:346894 AN 2003:484566 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In the present study an extrapolation model for estg. serum concns. of chems. equiv. to in vitro effective concns. is developed and applied to median cytotoxic concns. (EC50) detd. in vitro. Nominal concns. of a chem. in serum and in vitro are regarded as equiv., if they result in the same aq. concn. of the unbound form. The algorithm used is based on equil. distribution and requires albumin binding data, the octanol-water partition coeff. (Kow), and the albumin concns. and lipid vol. fractions in vitro and in serum. The chems. studied cover wide ranges of cytotoxic potency (EC50: 2.5-530 000 M) and lipophilicity (log Kow: -5 to 7). Their albumin binding characteristics were detd. by an in vitro cytotoxicity test as described previously. The equivalent serum concns. of 19 of the 33 compds. investigated, having high protein binding and/or lipophilicity, were substantially higher than the EC50-values, by factors of 2.5-58. Prominent deviations between the equiv. nominal concns. in serum and in vitro were largely restricted to chems. with higher cytotoxic potency (EC501000 M). The results suggest that ests. of equiv. serum concns. based on in vitro data are robust for chems. with low lipophilicity (log Kow2) and low potency (EC50>1000 M). With more potent chems. or those with higher lipophilicity partitioning into lipids and/or binding to serum proteins have to be taken into account when estg. in vivo serum concns. equiv. to in vitro effective concns.

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Putative role of proteolysis and inflammatory response in the toxicity of nerve and blister chemical warfare agents: Implications for multi-threat medical countermeasures. Cowan, F. M.; Broomfield, C. A.; Lenz, D. E.; Smith, W. J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2003), 23(3), 177-186. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 139:241394 AN 2003:447085 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review. Despite the contrasts in chem. and toxicity, for blister and nerve chem. warfare agents there may be some analogous proteolytic and inflammatory mediators and pathol. pathways that can be pharmacol. targets for a single-drug multi-threat medical countermeasure. The dermal-epidermal sepn. caused by proteases and bullous diseases compared with that obsd. following exposure to the blister agent sulfur mustard (2,2'-dichlorodiethyl sulfide) has fostered the hypothesis that sulfur mustard vesication involves proteolysis and inflammation. In conjunction with the paramount toxicol. event of cholinergic crisis that causes acute toxicity and ppts. neuronal degeneration, both anaphylactoid reactions and pathol. proteolytic activity have been reported in nerve-agent-intoxicated animals. Two classes of drugs already have demonstrated multi-threat activity for both nerve and blister agents. Serine protease inhibitors can prolong the survival of animals intoxicated with the nerve agent soman and can also protect against vesication caused by the blister agent sulfur mustard. Poly(ADP-ribose) polymerase (PARP) inhibitors can reduce both soman-induced neuronal degeneration and sulfur-mustard-induced epidermal necrosis. Protease and PARP inhibitors, like many of the other countermeasures for blister and nerve agents, have potent primary or secondary anti-inflammatory pharmacol. Accordingly, we hypothesize that drugs with anti-inflammatory actions against either nerve or blister agent might also display multithreat efficacy for the inflammatory pathogenesis of both classes of chem. warfare agent.

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Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: Influence of atropine dose. Taysse, L.; Calvet, J.-H.; Buee, J.; Christin, D.; Delamanche, S.; Breton, P. Defense Research Centre, Centre d'Etudes du Bouchet, Vert-Le-Petit, Fr. Toxicology (2003), 188(2-3), 197-209. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:346870 AN 2003:415467 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This investigation compared the efficacy of diazepam and the water-sol. prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD50 of sarin (s.c. route) and 1 min after intoxication treated by i.m. injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiol. parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were obsd. in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were obsd. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not obsd. but 62.5% of the animals displayed respiratory difficulties. These symptoms were not obsd. when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concn. of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.

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Low-level sarin-induced alteration of immune system reaction in inbred BALB/c mice. Kassa, Jiri; Krocova, Z.; Sevelova, L.; Sheshko, V.; Kasalova, I.; Neubauerova, V. Department of Toxicology, Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2003), 187(2-3), 195-203. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:241449 AN 2003:289956 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To study the influence of low-level sarin inhalation exposure on immune functions, inbred BALB/c mice were exposed to low concns. of sarin for 60 min in the inhalation chamber. Two concns. of sarin were chosen-asymptomatic concn. (LEVEL 1) and non-convulsive symptomatic concn. (LEVEL 2). The evaluation of immune functions was carried out using phenotyping of CD3 (T-lymphocytes), CD4 (helper T-lymphocytes), CD8 (cytotoxic T-lymphocytes) and CD19 cells (B-lymphocytes) in the lungs, blood and spleen, lymphoproliferation of spleen cells stimulated in vitro by various mitogens (Con A, lipopolysaccharides), phagocyte activity of peritoneal and alveolar macrophages, prodn. of N-oxides by peritoneal macrophages and the measurement of the natural killer cell activity at 1 wk following sarin exposure. The results were compared to the values obtained from control mice exposed to pure air instead of sarin. The results indicate that not only symptomatic but also asymptomatic dose of sarin is able to alter the reaction of immune system at 1 wk following exposure to sarin. While the no. of CD3 cells in the lungs was slightly decreased, an increase in CD19 cells was obsd. esp. in the lungs and blood. The reduced proportion of T-lymphocytes is caused by decay of CD4 pos. T-cells. Lymphoproliferation was significantly decreased regardless of the mitogen and sarin concn. used. The prodn. of N-oxides by peritoneal macrophages was stimulated after exposure to LEVEL 2 of sarin, whereas their ability to phagocyte the microbes was increased after exposure to LEVEL 1. The natural killer cell activity was significantly higher in the case of inhalation exposure of mice to LEVEL 2 of sarin. Thus, not only organophosphorus insecticides but also nerve agents such as sarin are able to alter immune functions even at a dose that does not cause clin. manifested intoxication following the inhalation exposure. Nevertheless, the alteration of immune functions following the inhalation exposure to a symptomatic concn.
of sarin seems to be more pronounced.

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Development of a sensor for the hydrolysis product of the nerve agent soman utilizing molecular imprinting and silica sol-gel techniques. Parker, Jennifer L.; Horne, Starr N.; Kita, Justin M.; Peeples, Christopher J.; DiCesare, John C. Department of Chemistry and Biochemistry, University of Tulsa, Tulsa, OK, USA. Polymeric Materials Science and Engineering (2003), 88 328-329. CODEN: PMSEDG ISSN: 1550-6703. Journal; Computer Optical Disk written in English. CAN 139:48357 AN 2003:222702 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preliminary findings were presented leading to the development of a pinacolylmethylphosphonate (PMP, the hydrolysis product of the nerve agent soman) sensor, utilizing silica sol-gel techniques, mol. imprinting, and lanthanide luminescence.

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Fluorescent Detection of Chemical Warfare Agents: Functional Group Specific Ratiometric Chemosensors. Zhang, Shi-Wei; Swager, Timothy M. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA. Journal of the American Chemical Society (2003), 125(12), 3420-3421. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 138:332984 AN 2003:159757 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Indicators providing highly sensitive and functional group specific fluorescent response to diisopropyl fluorophosphate (DFP, a nerve gas (G-agent) simulant) are reported. Nonemissive phenylpyridyl indicator reacts with DFP to give a cyclized compd. that shows a high emission due to its highly planar and rigid structure. Very weak emission was obsd. by the addn. of HCl. Another indicator based on pyridyl naphthalene exhibits a large shift in its emission spectrum after reaction with DFP, which provides for quant. ratiometric detection.

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Nerve Agents Detection Using a Cu2+/L-Cysteine Bilayer-Coated Microcantilever. Yang, Yuming; Ji, Hai-Feng; Thundat, Thomas. Department of Chemistry Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, USA. Journal of the American Chemical Society (2003), 125(5), 1124-1125. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 138:51039 AN 2003:24843 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A Cu2+/L-Cys bilayer-coated microcantilever undergoes bending upon exposure to di-Me Me phosphonate at concn. as low as 10-15 M due to the complexation of a phosphonyl group with the Cu2+/L-cysteine bilayer on the microcantilever surface.

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Neuroprotective efficacy of pharmacological pretreatment and antidotal treatment in tabun-poisoned rats. Krejcova, G.; Kassa, J. Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2003), 185(1-2), 129-139. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:2191 AN 2002:970172 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To study the influence of pharmacol. pretreatment (PANPAL) and antidotal treatment (obidoxime plus atropine) on tabun-induced neurotoxicity, male albino rats were poisoned with a LD of tabun (280 g/kg i.m.; 100% of LD50 value) and obsd. at 24 h and 7 days following tabun challenge. The neurotoxicity of tabun was evaluated using a functional observational battery (FOB) and an automatic measurement of motor activity. Pharmacol. pretreatment as well as antidotal treatment were able to eliminate most of tabun-induced neurotoxic effects obsd. at 24 h following tabun poisoning. However, there was not significant difference between the efficacy of PANPAL and antidotal treatment to eliminate tabun-induced neurotoxicity in rats. The combination of PANPAL pretreatment and antidotal treatment seems to be slightly more effective in the elimination of tabun-induced neurotoxicity in rats at 24 h following tabun challenge in comparison with the administration of PANPAL pretreatment or antidotal treatment alone. At 7 days following tabun poisoning, very few neurotoxic signs in tabun-poisoned rats were obsd. regardless of administration of pharmacol. pretreatment or antidotal treatment. Thus, our findings confirm that the combination of pharmacol. pretreatment and antidotal treatment is not only able to protect the exptl. animals from the lethal effects of tabun but also to eliminate most of tabun-induced signs of neurotoxicity in tabun-poisoned rats.

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Pyridostigmine bromide modulates topical irritant-induced cytokine release from human epidermal keratinocytes and isolated perfused porcine skin. Monteiro-Riviere, Nancy A.; Baynes, Ronald E.; Riviere, Jim E. Center for Chemical Toxicology Research and Pharmacokinetics (CCTRP), North Carolina State University, Raleigh, NC, USA. Toxicology (2003), 183(1-3), 15-28. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 138:364009 AN 2002:970031 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gulf War personnel were given pyridostigmine bromide (PB) as a prophylactic treatment against organophosphate nerve agent exposure, and were exposed to the insecticide permethrin and the insect repellent N,N-diethyl-m-toluamide (DEET). The purpose of this study was to assess the effects of PB to modulate release of inflammatory biomarkers after topical chem. exposure to chem. mixts. contg. permethrin and DEET applied in ethanol or water vehicles. Treatments were topically applied to isolated perfused porcine skin flaps (IPPSFs). Concns. of interleukin-8 (IL-8), tumor necrosis factor- (TNF-) and prostaglandin E2 (PGE2) were assayed in perfusate to probe for potential inflammatory effects after complex mixt. application. IPPSFs (n=4/treatment) were topically dosed with mixts. of permethrin, DEET, and permethrin/DEET, in EtOH. Each treatment was repeated with perfusate spiked with 50 ng/mL of PB. Perfusate was also spiked with 30 ng/mL diisopropylfluorophosphate to simulate low level organophosphate nerve agent exposure. Timed IPPSF venous effluent samples (0.5,1,2,4, and 8 h) were assayed by ELISA for IL-8 and TNF- and by EIA for PGE2. Overall, PB infusion caused a decrease or IL-8 and PGE2 release. Effects on TNF- were vehicle dependent. To probe the potential mechanism of this PB effect, human epidermal keratinocyte HEK cell cultures were exposed to permethrin DEET permethrin/DEET, with and without PB in DMSO. IL-8 was assayed at 1, 2, 4, 8, 12 and 24 h. PB suppressed IL-8 in permethrin and EtOH treatment from 4 to 24 h confirming the IPPSF results. In conclusion, these studies suggest that systemic exposure to PB suppressed IL-8 release at multiple time points in 2 skin model systems. This interaction merits further study.

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The pharmacokinetics and pharmacodynamics of two HI-6 salts in swine and efficacy in the treatment of GF and soman poisoning. Lundy Paul M; Hill Ira; Lecavalier Pierre; Hamilton Murray G; Vair Cory; Davidson Corey; Weatherby Kendal L; Berger Bradley J Chemical Biological Defence Section, Defence Research and Development Canada-Suffield, Box 4000, Medicine Hat Alberta, Alta., Canada T1A 8K6. paul.lundy@drdc-rddc.gc.ca Toxicology (2005 Mar 30), 208(3), 399-409. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15695025 AN 2005067571 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Anesthetized pigs were injected i.m. with 500 mg HI-6 dichloride (HI-6 2Cl) (1-[[[4-(aminocarbonyl)-pyridinio]methoxy]methyl]-2[(hydroxyimino)methyl]pyridinium dichloride; CAS 34433-31-3)) or the molar equivalent of HI-6 dimethanesulphonate (HI-6 DMS) 633 mg. Plasma HI-6 concentrations were measured by HPLC (1, 3, 5, 10, 15, 30, 60 min and every 30 min until 4h or 6h following the i.v. or i.m. dose respectively) while a variety of physiological responses were continuously examined. HI-6 (500 mg 2Cl or 633 mg DMS) resulted in an identical pharmacokinetic profile unaffected by atropine co-administration. Neither HI-6 salt resulted in clinically significant changes in cardiovascular or respiratory function. HI-6 DMS (1899 mg i.v.) resulted in plasma HI-6 concentrations about 10 times higher than measured following i.m. 500 mg 2Cl or 633 mg DMS and resulted in small transitory effect on mean arterial pressure. Atropine plus HI-6 DMS (1-9 mg/kg or 127-172 mg/kg i.m.) protected up to 100% of guinea pigs exposed to 5 x LD50 of GF (cyclohexyl methyl phosphonoflouridate) or soman (pinacolyl methylphosphonofluoridate) (GD) respectively. The results suggest that the two HI-6 salts have a similar pharmacokinetic profile while HI-6 DMS appears extremely safe and effective against nerve agents and may be as suitable for human use.

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Inhalation toxicity in mice exposed to sarin (GB) for 20-720 min. Bide R W; Risk D J Defence R&D Canada--Suffield, Box 4000, Medicine Hat, Alberta, Canada T1A 8K6. Richard.Bide@drdc-rddc.gc.ca Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 459-67. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558652 AN 2004610605 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Most of the historical data for the toxicity of sarin (GB) was collected for exposure times of <10 min in attempts to establish the utility of and defence against this agent in offensive military use. However, information concerning the toxicity of GB (and other nerve agents) from longer exposures of 1-12 h is critical for all personnel who must work in or close to low-level concentrations of chemical for extended periods and for all personnel, dressed in Individual Protective Equipment, who need to know when, and if, it is safe to take off these cumbersome garments.The data presented for the toxicity of GB to mice for whole-body exposures of 20 min to 12 h are intended to form part of an ongoing, multi-species effort aimed at establishing toxicity estimates for humans for these longer exposure times: LCT50 values of 430, 540, 900, 1210 and 2210 mg.min m(-3) or LC50 values of 21.5, 9.0, 5.0, 3.4 and 3.1 mg m(-3) were obtained for mice for 20-, 60-, 180-, 360- and 720-min exposures to GB, respectively. The data for longer exposures do not follow Haber's rule (LCT50=CT). The 20- and 60-min data fit the 'toxic load model' involving CnT that was established previously from historical data for 0.17-30 min GB exposures to mice. The LCT(50) and LC50 values for 3, 6 and 12 h are progressively higher (toxicity lower) than predicted by either Haber's rule or the toxic load model.

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Low levels of sarin affect the EEG in marmoset monkeys: a pilot study. van Helden Herman P M; Vanwersch Raymond A P; Kuijpers Willem C; Trap Henk C; Philippens Ingrid H C; Benschop Hendrik P Department of Medical Countermeasures. TNO Prins Maurits Laboratory, PO Box 45, 2280 AA Rijswijk, The Netherlands. helden@pml.tno.nl Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 475-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558834 AN 2004598850 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The main purpose of this pilot study was to estimate the lowest observable adverse effect level (LOAEL) for the electroencephalogram (EEG) upon long-term, low-level exposure of vehicle-pretreated and pyridostigmine-pretreated marmoset monkeys to sarin vapour. This is the C.t value (t=5 h) of exposure at which the EEG becomes significantly different from that resulting from air exposure of the same animals. The LOAELs for effects on the EEG in vehicle- and pyridostigmine-pretreated marmosets appeared to be 0.2 and 0.1 mg min m(-3), respectively. Comparatively, the latter LOAEL values are at least an order of magnitude lower than the previously established LOAEL for miosis and only 2-5 times higher than the lowest observable effect level (LOEL) of bound sarin in blood.The second aim of the study was to analyse the EEG of the same marmosets again during a 5-h exposure to air 1 year after exposure to sarin vapour. All the marmosets still demonstrated significant (P <0.05) EEG differences. In most vehicle-pretreated marmosets the energy (microV2) per EEG band was higher than that observed 1 year earlier, which might indicate that neurons had become more sensitive to excitation. This phenomenon was less pronounced in pyridostigmine-pretreated animals. Visual examination of the EEG records revealed clear bursts of alpha frequencies (ca. 9 Hz), resembling sleep-spindles, that were present more frequently in both groups of exposed marmosets than in naive animals. These late changes in spindle oscillation might be the result of changes in the cholinergic system due to exposure to sarin vapour 1 year previously. In conclusion, EEG abnormalities persisting for more than 1 year may occur in humans during long-term (5 h) exposure to subclinical levels of sarin that are not detectable by the currently fielded alarm systems.

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Protection and inflammatory markers following exposure of guinea pigs to sarin vapour: comparative efficacy of three oximes. Levy A; Chapman S; Cohen G; Raveh L; Rabinovitz I; Manistersky E; Kapon Y; Allon N; Gilat E Israel Institute for Biological Research, Department of Pharmacology, PO Box 19, Ness Ziona 74100, Israel. RonLevy@iibr.gov.il Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 501-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558827 AN 2004598847 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The purpose of the present study was to compare the antidotal efficacy and the combined effects on inflammatory markers of three oximes--toxogonine, TMB4 and 2-PAM--in combination with anticholinergic drugs following exposure to sarin vapour by inhalation.Guinea pigs restrained in plethysmographs were exposed to various doses of sarin vapour (in the range of 1.4-4.4LD50). The antidotal mixture was injected immediately (5-20 s) following exposure (3 mg kg(-1) atropine and 1 mg kg(-1) benactyzine in combination with 6 mg kg(-1) toxogonine, 2 mg kg(-1) TMB4 or 12 mg kg(-1) 2-PAM). Bronchoalveolar lavage (BAL) samples were taken from surviving animals 24 h after exposure to determine the levels of inflammatory markers. A differential cell count was performed in BAL samples on Giemsa-stained slides. The inflammatory markers--histamine and prostaglandins (PGE)--were measured in BAL using radioimmunoassay (RIA) techniques.The survival rate in the various treatment groups and analysis of BAL samples showed that: (i) Toxogonine, TMB4 and 2-PAM, without pyridostigmine pretreatment, at doses that were proportional to their doses in the respective auto-injectors, exhibited similar antidotal efficacy against sarin exposure. (ii) The results demonstrated that a centrally acting anticholinergic drug is essential in the antidotal mixture to ensure survival. (iii) Histamine release and eosinophilia following sarin inhalation might require additional intervention, aimed at reducing the symptoms of allergic reaction and possibly expediting recovery.

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Delayed haematological complications of mustard gas. Ghanei Mostafa Department of Internal Medicine, Baqiyatallah University of Medical Sciences, Chemical Injured Research Centre, Tehran, Iran. m.ghanei@bmsu.ac.ir Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 493-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558826 AN 2004598846 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Haematopoiesis could be affected by mustard gas. We randomly selected 318 chemical victims exposed to mustard gas and compared their cell blood counts and peripheral blood smears (PBS) with those of 377 healthy men, and also various haematological indices of 57 of these victims compared with previous data 5 years ago.The average number of red blood cells and haemoglobin of victims compared with the controls was not significantly different, but they were increased compared with data from 5 years ago. White blood cell counts, neutrophils and lymphocytes did not show any clinically meaningful difference compared with the control group but 20 cases with atypical lymphocytes in their PBS have been found.Change in lymphocyte shape may be related to committed stem cell involvement. Further studies on bone marrow cells and cell markers are needed to document this hypothesis. The mild increase in erythroid cells and haemoglobin concentration may be due to chronic obstructive pulmonary disorder and other respiratory diseases in these patients.

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Investigating the affinities and persistence of VX nerve agent in environmental matrices. Love Adam H; Vance Andrew L; Reynolds John G; Davisson M Lee Environmental Science Division, Lawrence Livermore National Laboratory, P.O. Box 808, L-396, Livermore, CA 94551, USA. love5@llnl.gov Chemosphere (2004 Dec), 57(10), 1257-64. Journal code: 0320657. ISSN:0045-6535. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15519370 AN 2004547393 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity for an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when specific adsorption was forced. No enhanced degradation occurred with goethite in small amounts of water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.

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Localization of substance P gene expression for evaluating protective countermeasures against sulfur mustard. Casbohm Stacy L; Rogers James V; Stonerock Mindy K; Martin Jamie L; Ricketts-Kaminsky Karen M; Babin Michael C; Casillas Robert P; Sabourin Carol L K Battelle Memorial Institute, Medical Research and Evaluation Facility, 505 King Avenue, JM-3, Columbus, OH 43201, USA Toxicology (2004 Nov 15), 204(2-3), 229-39. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE); (VALIDATION STUDIES) written in English. PubMed ID 15388249 AN 2004477792 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard [bis(2-chloroethyl)sulfide; SM] is a chemical warfare agent that produces edema and blister formation with a severe inflammatory reaction. The mouse ear vesicant model for SM injury has been used to evaluate pharmacological agents for countering SM dermal injury. The vanilloid olvanil reduces SM-induced edema and mRNA expression of cytokines and chemokines, suggesting that blocking the inflammatory effects of neuropeptides, such as substance P (SP), may provide protection against SM-induced dermal injury. This study examined SP expression in mice exposed to SM (0.16 mg) on the inner surface of the right ear, with or without olvanil pretreatment at 1, 10, 30, 60, and 360 min following exposure. In naive skin, SP mRNA localization was associated with blood vessels and sebaceous glands. In SM-exposed skin, SP mRNA was also detected in perivascular dermal cells. Immunohistochemical localization of SP protein was observed in the ear skin of naive, SM-, olvanil/SM-, and vehicle-treated mice. Quantification of SP+ perivascular dermal cells revealed that SM exposure led to a significant increase (P < or = 0.05) in SP+ cells over the observed time period. Olvanil pretreatment significantly reduced (P < or = 0.05) the mean number of SP+ cells at 60 and 360 min. This study demonstrates that SP expression could provide an additional endpoint for evaluating the effectiveness of vanilloid drugs on SM-induced skin inflammation.

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Enhanced degradation of chemical warfare agents through molecular engineering of the phosphotriesterase active site. Hill Craig M; Li Wen-Shan; Thoden James B; Holden Hazel M; Raushel Frank M Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, TX 77842-3012, USA Journal of the American Chemical Society (2003 Jul 30), 125(30), 8990-1. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15369336 AN 2004461552 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

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Photocatalytic oxidation of VX simulant 2-(butylamino)ethanethiol. Vorontsov Alexandre V; Chen Yi-Chuan; Smirniotis Panagiotis G Boreskov Institute of Catalysis, Novosibirsk 630090, Russian Federation, Russia Journal of hazardous materials (2004 Sep 10), 113(1-3), 89-95. Journal code: 9422688. ISSN:0304-3894. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15363518 AN 2004456562 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Photocatalytic oxidation of 2-(butylamino)ethanethiol (BAET) was undertaken in aqueous suspension of TiO2 Hombikat UV 100 and Degussa P25 under different initial reaction conditions in order to determine the best parameters for the fastest mineralization of the substrate. BAET is considered to be a simulant for the VX chemical warfare agent. The application of ultrasound had only a small positive effect on the BAET photocatalytic degradation. The highest mineralization rate of 0.433 mg/(l min) was found in unbuffered TiO2 Degussa P25 suspension with initial pH value of about 9.4, TiO2 concentration 500 mg/l and the initial BAET concentration 1000 mg/l. Decreasing of the initial solution pH to 6.1 or below stops the mineralization of BAET while increasing of pH to about 11 drastically changed the degradation profile. At this initial pH, the first 100 min of reaction led to only oxidation of sulfur moiety and organic intermediates accumulated in the solution. Thereafter, mineralization of the products started. The main detected volatile product was butyl aldehyde and the main polar one was 2-(butylamino) acetic acid. In the case of TiO2 Hombikat UV 100, conversion of TOC at initial pH 11 exceeded that at initial pH 9.1. For Degussa P25, the starting pH 9.4 was the best for TOC conversion. The results can be used for treatment of water from pollutants with aliphatic nitrogen and sulfur atoms.

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Retrospective detection of exposure to nerve agents: analysis of phosphofluoridates originating from fluoride-induced reactivation of phosphylated BuChE. van der Schans Marcel J; Polhuijs Martine; van Dijk Corry; Degenhardt Carla E A M; Pleijsier Kees; Langenberg Jan P; Benschop Hendrik P Department of Medical Countermeasures, TNO Prins Maurits Laboratory, P.O. Box 45, 2280 AA Rijswijk, The Netherlands. schansm@pml.tno.nl Archives of toxicology (2004 Sep), 78(9), 508-24. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15170525 AN 2004433787 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The utility was explored of a new approach to detect retrospectively exposure to nerve agents by means of conversion of the inhibitor moiety bound to the active site of the enzyme BuChE in plasma with fluoride ions into a phosphofluoridate which is subsequently analyzed by means of gas chromatography (GC). This quantifies >or=0.01% inhibition of BuChE and identifies the structure of the inhibitor except for the original leaving group. A three-tiered approach was followed involving the five classical nerve agents GA, GB, GF, GD, and VX, as well as the active metabolite of parathion, i.e., paraoxon: in vivo experiments in rhesus monkeys after iv administration of a sign-free dose of agent and concomitant in vitro experiments in plasma of rhesus monkeys and humans should allow an assessment of in vivo retrospectivity in humans. A systematic investigation was performed in order to find a single set of reaction conditions which yields a maximum amount of phosphofluoridate for all nerve agents. Fluoride-induced reactivation at 25 degrees C at a final concentration of 250 mM KF during 15 min in a pH-range between 4 and 6 appears to be effective. The in vitro decrease with time in reactivatibility of inhibited BuChE in plasma from humans and rhesus monkeys was largely due to aging of the phosphyl moiety, except for VX where spontaneous reactivation was a major cause. The decrease followed first-order except for a biphasic course in the case of GF in human and rhesus monkey plasma as well as of GD in rhesus plasma. In vitro half-lifes in human plasma ranged between ca. 14 h for GB and ca. 63 h for GA. A comparison of the in vivo data from rhesus monkeys and the in vitro data is complicated by the observation that the in vivo decrease with time of fluoride-reactivated phosphofluoridate is biphasic for all nerve agents.
The terminal in vivo phase pertains to a small fraction of the amount of initially regenerated phosphofluoridate but is responsible for a considerable degree of retrospectivity, ranging between 14 and 56 days for GF and GB, respectively. The new procedure can be used in a variety of practical applications, e.g., (i) biomonitoring in health surveillance at exposure levels that are several orders of magnitude lower than presently possible; (ii) diagnosis in case of alleged exposure to nerve agents in time of war or after terrorist attacks; (iii) in forensic cases against suspected terrorists that have handled organophosphate anticholinesterases; and (iv) in research applications such as investigations on lowest observable effect levels of exposure to nerve agents.

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Biochemical changes in mouse lung after subcutaneous injection of the sulfur mustard 2-chloroethyl 4-chlorobutyl sulfide. Elsayed Nabil M; Omaye Stanley T Department of Nutrition and Environmental Sciences and Health, Graduate Program, University of Nevada at Reno, Reno, NV, USA. nelsayed@hurleyconsulting.com Toxicology (2004 Jul 1), 199(2-3), 195-206. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15147793 AN 2004250354 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant-type chemical warfare agent (CWA) introduced in World War I which continues to be produced, stockpiled, and occasionally deployed by some countries, and could be used potentially by terrorists. Exposure to HD can cause erythema, blisters, corneal opacity, and airway damage. We have reported previously that subcutaneous (SC) injection of immunodeficient athymic nude mice with the half mustard butyl 2-chloroethyl sulfide (BCS) causes systemic biochemical changes in several organs distal to the exposure site. In the present study, we examined the response of non-immunodeficient Swiss Webster mice to the mustard, 2-chloroethyl 4-chlorobutyl sulfide (CECBS). In a pilot study, we found that a single SC injection of 20-25 microl/mouse causes death within 24h. Consequently, we used 5 microl/mouse (approx. 0.017 mg/kg body weight) of neat CECBS or an equal volume of saline as control. We examined the lungs after 1, 24, and 48 h for biochemical changes including total and oxidized glutathione, protein, DNA, and lipid peroxidation contents in tissue homogenate, and superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, and glutathione S-transferases activities in the cytosol. After 1h and/or 24h, we found statistically significant changes that were resolved by 48 h. These changes mimicked those of HD and BCS and were generally consistent with free radical-mediated oxidative stress. The implications of these observations are two-fold. First, dermal exposure to low-dose mustard gas could elicit systemic changes impacting distal organs such as the lungs. It also suggests that antioxidants could potentially modulate the response and reduce the damage. Second, although the use of known CWAs such as HD is prohibited, analogs that are not recognized as agents are as toxic and could be dangerous if acquired and used by potential terrorists.

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Reactivation and aging kinetics of human acetylcholinesterase inhibited by organophosphonylcholines. Worek F; Thiermann H; Szinicz L Institut fur Pharmakologie und Toxikologie der Bundeswehr, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2004 Apr), 78(4), 212-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14647978 AN 2004188515 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A great number of structurally different organophosphorus compounds (OPs) was synthesized in the past decades to be used as pesticides or chemical warfare agents. Methyl-fluorophosphonylcholines were found to be highly toxic OPs and the acetylcholinesterase (AChE) reactivator pralidoxime was shown to be unable to reactivate inhibited AChE. In the course of the development of more effective AChE reactivators, we have determined the reactivation rate constants of various oximes with human AChE inhibited by methylfluorophosphonylcholine (MFPCh), methylfluoro-beta-phosphonylcholine (MFP beta Ch) and methylfluorophosphonylhomocholine (MFPhCh). In addition, we investigated the potential influence of aging phenomena on the oxime efficacy. Human AChE inhibited by MFPCh, MFP beta Ch or MFPhCh was extremely resistant towards reactivation by oximes. Nevertheless, the newer compounds, HLo 7 and HI 6, were substantially more potent reactivators than obidoxime and pralidoxime. The low oxime efficacy was not due to rapid aging since no decrease in reactivatability was found over 96 h at 37 degrees C. Within this period a substantial spontaneous reactivation was observed, with MFPCh >MFP beta Ch >MFPhCh, which did not follow pseudo-first-order kinetics. In conclusion, the unexpected results, i.e., high resistance of inhibited AChE towards oxime reactivation and aging, and much lower resistance towards spontaneous reactivation, calls for further experiments at a molecular level for a better understanding of the interactions among AChE, its inhibitors and reactivators.

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Amelioration of sulfur mustard skin injury following a topical treatment with a mixture of a steroid and a NSAID. Dachir Shlomit; Fishbeine Eliezer; Meshulam Yakov; Sahar Rita; Chapman Shira; Amir Adina; Kadar Tamar Israel Institute for Biological Research, Department of Pharmacology, PO Box 19, Ness-Ziona 74100, Israel. shlomit@iibr.gov.il Journal of applied toxicology : JAT (2004 Mar-Apr), 24(2), 107-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15052605 AN 2004157688 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The ability to ameliorate sulfur mustard (HD)-induced oedema by treatment with anti-inflammatory drugs was reported previously after screening four steroids and four non-steroidal anti-inflammatory drugs (NSAIDs) using the mouse ear vesicant model. Following the screening study, one steroid and one NSAID (Adexone and Voltaren) were selected as the most effective, and a mixture of the two was chosen for the present more extensive research. The effect of the combined treatment on clinical, biochemical and histopathological parameters following HD insult was studied. Mice ears were exposed to 0.2 micro l of HD for 10 min to produce a moderate skin injury. Oedema development peaked ca. 48 h following exposure, as determined by weighing ear biopsies. Histological observations at that time exhibited damage to the epidermis and dermis. An increase in prostaglandin E (PGE) was measured in skin homogenates, starting 8 h following exposure and lasting at least up to 48 h post-exposure. A topical treatment using the above anti-inflammatory mixture significantly reduced inflammatory parameters when applied up to 4 h following exposure. These parameters included extent of oedema, levels of PGE, area of clinical damage and extent of cytotoxic injury (vesications and damaged epithelial cells). Thus, a combination of a steroid and NSAID was found to be effective in reducing the intensity of HD skin injury and possibly shortening the time to full recovery. The treatment, however, did not prevent completely the ensuing cytotoxic processes in the epithelial layer. Copyright 2004 John Wiley & Sons, Ltd.

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Protective effect of topical iodine containing anti-inflammatory drugs against sulfur mustard-induced skin lesions. Wormser Uri; Sintov Amnon; Brodsky Berta; Casillas Robert P; Nyska Abraham Berman Building, Institute of Life Sciences, The Hebrew University, 91904 Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2004 Mar), 78(3), 156-66. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14618300 AN 2004140011 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Previous studies have shown the antidotal efficacy of topical iodine at 15 and 30 min post-exposure to sulfur mustard (SM). Here we demonstrate efficacy at longer intervals (20, 30, 45, and 60 min, respectively, for data) using an improved topical povidone-iodine preparation termed N66, which contains steroidal and non-steroidal anti-inflammatory agents. In the mouse, N66 reduced severity of ear edema by 43, 47, 44, and 36%; ear epidermal ulceration by 74, 58, 45, and 58%; and epidermal necrosis by 54, 34, 26, and 31% at the respective time points. A similar effect was observed with encrustation. The healing marker, grade of acanthotic area, showed dramatic increases of 39.6-, 25.3-, 20.9-, and 22-fold. Severity of the dermal parameters, acute inflammation and dermal necrosis, was reduced by 63, 34, 34, and 38% and 80, 54, 54, and 59%, respectively. In guinea pig skin, topical treatment with N66 45 min post-exposure reduced the SM-induced ulceration area by 75%. The histological parameters subepidermal microblister formation, epidermal ulceration, epidermal necrosis, and encrustation were reduced by 63, 61, 41, and 41%, respectively. The healing marker, grade of acanthotic area, was elevated by 73%. N66 induced a statistically significant reduction in two dermal markers for tissue damage: acute inflammation (33%) and dermal necrosis (48%). Reduced skin damage was also observed in areas adjacent the treated sites. The pharmacologically active components of N66 showed additive effect. These findings suggest that the povidone-iodine preparation combined with anti-inflammatory agents functions as a potent antidote against skin lesions induced by SM at relatively long intervals between exposure and treatment.

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Low-level exposure of guinea pigs and marmosets to sarin vapour in air: lowest-observable-adverse-effect level (LOAEL) for miosis. van Helden Herman P M; Trap Henk C; Kuijpers Willem C; Oostdijk John P; Benschop Hendrik P; Langenberg Jan P Department of Medical Countermeasures, TNO Prins Maurits Laboratory, PO Box 45, 2280 AA Rijswijk, The Netherlands. helden@pml.tno.nl Journal of applied toxicology : JAT (2004 Jan-Feb), 24(1), 59-68. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14745848 AN 2004044499 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration x time (C.t) value (t = 5 h) of exposure at which miosis becomes significant. The ratio of pupil and iris diameters, measured on digital photographs taken on-line during exposure, was calculated as a measure for miosis. The exposure concentrations were in the range 7-150 microg x m(-3) and the exposure times needed to achieve significant miosis were in the range 10-300 min. Both vehicle- and pyridostigmine-pretreated animals were used in the experiments. The latter pretreatment resulted in ca. 30% inhibition of erythrocyte acetylcholinesterase in both species. In vehicle-pretreated guinea pigs and marmosets the pupil size was decreased significantly (P < 0.05) at sarin doses of 1.8 +/- 0.3 and 2.5 +/- 0.8 mg x min x m(-3), respectively. In pyridostigmine-pretreated guinea pigs and marmosets the pupil size was affected significantly (P < 0.05) at 1.8 +/- 0.5 and 3.0 +/- 0.8 mg x min x m(-3), respectively. Evidently there is no significant influence of pyridostigmine pretreatment on the LOAEL. These data were addressed in light of the recommended occupational and detection limits for sarin vapour in air. It was concluded that miosis will occur during low-level sarin exposure at levels that are not detectable by the currently fielded alarm systems, assuming that humans are as sensitive for sarin vapour in air as guinea pigs and marmosets. Copyright 2004 John Wiley & Sons, Ltd.

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Examination of changes in connective tissue macromolecular components of large white pig skin following application of Lewisite vapour. Lindsay Christopher D; Hambrook Joy L; Brown Roger F R; Platt Jan C; Knight Robert; Rice Paul Biomedical Sciences Department, Dstl Porton Down, Salisbury, Wilts SP4 0JQ, UK. clindsay@dstl.gov.uk Journal of applied toxicology : JAT (2004 Jan-Feb), 24(1), 37-46. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14745845 AN 2004044496 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to provide information about the degradative processes that occur in major connective tissue components in skin following exposure of large white pigs to Lewisite vapour. Of particular interest were alterations in glycoproteins, which are known to mediate dermo-epidermal attachment (laminin and type IV collagen) and the main collagen found in the dermis (type III collagen). The immunostaining of transfer blots from skin extracts run on sodium dodecyl sulphate polyacrylamide gel electrophoresis gels revealed no evidence of cross-linking of laminin or of type III or IV collagen. However, there was evidence of a very considerable degradation of laminin and, to a lesser extent, of type IV collagen. Type III collagen did not appear to be degraded in skin exposed to Lewisite. These degradative processes appeared to be more severe than found in previous studies in Yucatan mini-pigs percutaneously exposed to sulphur mustard, in which only laminin was found to undergo partial cleavage rather than wholesale degradation.The results suggest that damage to macromolecular components in the sub-epidermal basement membrane in skin which mediate dermo-epidermal separation processes may be a common feature in the mechanism of action of vesicating agents such as Lewisite and sulphur mustard. It is of interest that the damage to laminin in this study appeared to be more severe than that previously found for sulphur mustard. This suggests that skin can suffer substantial damage yet, in the case of Lewisite exposure, recover relatively quickly. However, Lewisite is not an alkylating agent. Sulphur mustard, in contrast, generates characteristically slow healing lesions, most probably because of its ability to alkylate cell types that normally would be involved in skin regenerative processes. Published by John Wiley & Sons, Ltd.

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Cardiovascular effects of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) decisive for its therapeutic efficacy in sarin poisoning. Joosen Marloes J A; Bueters Tjerk J H; van Helden Herman P M Research Group Medical Countermeasures, TNO Prins Maurits Laboratory, Lange Kleiweg 137, PO Box 45, 2280 AA Rijswijk, The Netherlands. joosen@pml.tno.nl Archives of toxicology (2004 Jan), 78(1), 34-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14508639 AN 2004043790 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Mortality and occurrence of cholinergic symptoms upon sarin intoxication (144 micro g/kg s.c., approximately 2 x LD50) in rats is completely prevented by treatment with the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA, 2 mg/kg i.m.). Previously, we have shown that CPA treatment altered the distribution of sarin into the brain, presumably through its cardiovascular side effects. Therefore, the objective of the present study was to evaluate the contribution of the cardiodepressant effects of CPA to its therapeutic efficacy against sarin intoxication. Intramuscular treatment of rats with 0.5 and 2.0 mg/kg CPA 1 min after sarin poisoning attenuated most cholinergic symptoms and prevented mortality, which seemed to be directly associated with an immediate strong and long-lasting bradycardia and hypotension caused by CPA. Treatment with lower doses of CPA (0.1 and 0.05 mg/kg i.m.) caused similar levels of bradycardia and hypotension, albeit a few minutes later than at the higher doses of CPA. Upon sarin intoxication, this was correlated with increased incidence of cholinergic symptoms and decreased survival rates. Pretreatment with the peripheral adenosine A1 receptor antagonist 8- p-sulphophenyltheophylline (8-PST, 20 mg/kg i.p.) counteracted the cardiodepressant effects of 0.05 mg/kg CPA almost completely, thereby nearly abolishing its therapeutic efficacy against sarin poisoning. In conclusion, the present results strongly indicate that bradycardia and hypotension induced by the peripheral adenosine A1 receptor play a prominent role in the therapeutic efficacy of CPA in cases of sarin poisoning.

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Effects of daily stress or repeated paraoxon exposures on subacute pyridostigmine toxicity in rats. Shaikh Jamaluddin; Karanth Subramanya; Chakraborty Dibyendu; Pruett Steve; Pope Carey N Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 264 McElroy Hall, OK 74078, Stillwater, USA Archives of toxicology (2003 Oct), 77(10), 576-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14574445 AN 2003495653 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Pyridostigmine (PYR) is a carbamate cholinesterase (ChE) inhibitor used during the Persian Gulf War as a pretreatment against possible chemical nerve agent attack. Because of its quaternary structure, PYR entry into the central nervous system is limited by the blood-brain barrier (BBB). Following reports of unexplained illnesses among Gulf War veterans, however, central nervous system effects of PYR have been postulated through either stress-induced alteration of BBB permeability or via interactions with other neurotoxic agents. We evaluated the effects of daily physical (treadmill running) stress or daily exposure to a subclinical dosage of the organophosphate ChE inhibitor paraoxon (PO) on ChE inhibition in blood, diaphragm and selected brain regions in young adult male Sprague-Dawley rats following subacute PYR exposures. In physical stress studies, rats were placed on a treadmill for 90 min each day for 14 days just prior to PYR (0, 3, or 10 mg/kg per day) administration. In PO-PYR interaction studies, rats were treated with PO (0, 0.05, or 0.1 mg/kg per day) 1 h prior to daily PYR (0 or 3 mg/kg per day) administration for 14 consecutive days. Rats were evaluated daily for signs of cholinergic toxicity and were killed 1 h after the final PYR treatment. Forced running increased plasma corticosterone levels throughout the experiment (on days 1, 3, 7 and 14) when measured immediately after termination of stress. PYR-treated rats in the high dosage (10 mg/kg per day) group exhibited slight signs of toxicity (involuntary movements) for the first 6 days, after which tolerance developed. Interestingly, signs of cholinergic toxicity following PYR were slightly but significantly increased in rats forced to run on the treadmill prior to dosing. ChE activities in whole blood and diaphragm were significantly reduced 1 h after the final PYR challenge, and ChE inhibition in diaphragm was significantly greater in stressed rats than in non-stressed controls following high dose PYR (10 mg/kg per day).
No significant effects of treadmill running on PYR-induced ChE inhibition in brain regions were noted, however. Repeated subclinical PO exposure had no apparent effect on functional signs of PYR toxicity. As with repeated treadmill running, whole blood and diaphragm ChE activities were significantly reduced 1 h after the final PYR administration, and ChE inhibition was significantly greater with combined PO and PYR exposures. Brain regional ChE activity was significantly inhibited after daily PO exposure, but no increased inhibition was noted following combined PO and PYR dosing. We conclude that, while some stressors may under some conditions affect functional signs of toxicity following repeated pyridostigmine exposures, these changes are likely to occur via alteration of peripheral cholinergic mechanisms and not through enhanced entry of pyridostigmine into the brain.

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Effects of sulfur mustard on transcription in human epidermal keratinocytes: analysis by mRNA differential display. Platteborze Peter L Pharmacology Division, USAMRICD, Aberdeen Proving Ground, MD 21010-5425, USA. Peter.Platteborze@det.amedd.army.mil Journal of applied toxicology : JAT (2003 Jul-Aug), 23(4), 249-54. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12884408 AN 2003350997 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This study examines the transcriptional response of human epidermal keratinocytes (HEK) to sulfur mustard (HD) in order to gain a better understanding of the intracellular events that result in cytotoxicity. Differential display polymerase chain reaction technology was used to examine the relative transcriptional activity of healthy cells to those exposed to subvesicating or vesicating concentrations of HD for 4 h. Approximately 2% of the HEK transcriptome had altered expression. Sixty of the most prominently altered transcripts were characterized. Important upregulated genes include NADH dehydrogenase III, GADD45 and ubiquitin. Key downregulated genes include type I keratin 14, alpha-enolase and caltractin. Many of the identified transcripts protein products presently do not have an assigned function and eleven transcripts were unidentifiable. These transcriptional alterations provide one of the first molecular insights into the intracellular events induced by HD. Published in 2003 by John Wiley & Sons, Ltd.

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Degradation of VX and sulfur mustard by enzymatic haloperoxidation. Amitai G; Adani R; Hershkovitz M; Bel P; Rabinovitz I; Meshulam H Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. amitai@ibr.gov.il Journal of applied toxicology : JAT (2003 Jul-Aug), 23(4), 225-33. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12884405 AN 2003350994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chloroperoxidase (CPO) isolated from Caldariomyces fumago (20 U ml(-1)) together with urea hydrogenperoxide (UPER, 0.5 mM) and sodium chloride as co-substrate (NaCl, 0.5 M) caused rapid breakdown of VX (10 microM) (t((1/2)) = 8 s, 25 C, 50 mM tartarate, pH 2.75). Glucose oxidase (GOX, Aspergillus niger) and glucose were used as an alternative source for H(2)O(2). A mixture of GOX (20 U ml(-1)), glucose (GLU 0.45 M), CPO (20 U ml(-1)) and NaCl (0.5 M) caused a 3.8-fold slower degradation of VX (10 microM) (t((1/2)) = 30 s, 25 C, 50 mM tartarate, pH 2.75). The concentrations of H(2)O(2) and chlorine produced by this enzyme/substrate mixture depended mainly on the GLU concentration. Horseradish peroxidase (HRP) together with UPER (1 mM) and sodium iodide (NaI, 0.05 M) caused progressive degradation of VX that was more than 400-fold slower than with CPO (20 U ml(-1)), UPER (0.5 mM) and NaCl (0.5 M) (t((1/2)) = 55 min, 25 C, pH 8). Skin decontamination of VX by CPO was tested in pig-ear skin in vitro. The chemical agent VX (0.01 M, 100 microl) was degraded by 98% within 3 h of skin diffusion when a mixture of UPER/NaCl/CPO was applied 60 min prior to VX application. A mixture of UPER/NaCl without CPO also caused significant VX degradation (94%) during skin diffusion whereas it did not cause any VX degradation in solution. Degradation of VX in skin, obtained without exogenous CPO, may indicate involvement of endogenous intradermal haloperoxidase-like enzyme. Reagent UPER (1 mM) did not cause any degradation of VX in solution or during its skin diffusion. Furthermore, a mixture of CPO, UPER and NaCl caused rapid degradation of sulfur mustard (HD). Sulfur mustard (50 microM) incubated in the presence of CPO (4 U ml(-1)), UPER (0.05 M) and NaCl (0.5 M) at pH 2.75 and 30 C was oxidized by 97% and 99% within 5 and 10 min, respectively. The oxidation products HD sulfoxide, HD sulfone and HD sulfoxidevinyl were identified by GC/MS in the enzymatic chloroperoxidation mixture. Copyright 2003 John Wiley & Sons, Ltd.

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Billion-fold acceleration of the methanolysis of paraoxon promoted by La(OTf)3 in methanol. Tsang Josephine S; Neverov Alexei A; Brown R S Department of Chemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6 Journal of the American Chemical Society (2003 Jun 25), 125(25), 7602-7. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12812502 AN 2003285652 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The methanolysis of the insecticide paraoxon (2) was investigated in methanol solution containing varying [La(OTf)(3)] (OTf = (-)OS(O)(2)CF(3)) as a function of at 25 degrees C. Plots of the pseudo-first-order rate constants (k(obs)) for methanolysis as a function of [La(OTf)(3)](total) were obtained under buffered conditions from 5.15 to 10.97, and the slopes of the linear parts of these were used to determine the second-order rate constants (k(2)(obs)) for the La(3+)-catalyzed methanolysis of 2. Detailed analysis of the potentiometric titration data of La(OTf)(3) in methanol through fits to a multicomponent equilibrium mixture of dimers of general stoichiometry La(3+)(2)((-)OCH3)n, where n assumes values of 1-5, gives the equilibrium distribution of each as a function of. These data, when fit to a second expression describing k(2)(obs) in terms of a linear combination of individual rate constants k(2)(2:1), k(2)(2:2).k(2)(2:)n for the dimers, allow one to describe the overall catalytic profile in terms of the individual contributions. The most catalytically important species are the three dimers La(3+)(2)((-)OCH3)1, La(3+)(2)((-)OCH3)2, and La(3+)(2)((-)OCH3)3. The catalysis of the methanolysis of 2 is spectacular: a 2 x 10(-3) M solution of [La(3+)](total), at neutral, affords a 10(9)-fold acceleration relative to the base reaction (t(1/2) approximately 20 s at 8.2) with excellent turnover. A mechanism of the catalyzed reaction involving the La(3+)(2)((-)OCH3)2 species is proposed.

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Putative role of proteolysis and inflammatory response in the toxicity of nerve and blister chemical warfare agents: implications for multi-threat medical countermeasures. Cowan F M; Broomfield C A; Lenz D E; Smith W J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. fred.cowan@amedd.army.mil Journal of applied toxicology : JAT (2003 May-Jun), 23(3), 177-86. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 12794939 AN 2003268101 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Despite the contrasts in chemistry and toxicity, for blister and nerve chemical warfare agents there may be some analogous proteolytic and inflammatory mediators and pathological pathways that can be pharmacological targets for a single-drug multi-threat medical countermeasure. The dermal-epidermal separation caused by proteases and bullous diseases compared with that observed following exposure to the blister agent sulfur mustard (2,2'-dichlorodiethyl sulfide) has fostered the hypothesis that sulfur mustard vesication involves proteolysis and inflammation. In conjunction with the paramount toxicological event of cholinergic crisis that causes acute toxicity and precipitates neuronal degeneration, both anaphylactoid reactions and pathological proteolytic activity have been reported in nerve-agent-intoxicated animals. Two classes of drugs already have demonstrated multi-threat activity for both nerve and blister agents. Serine protease inhibitors can prolong the survival of animals intoxicated with the nerve agent soman and can also protect against vesication caused by the blister agent sulfur mustard. Poly (ADP-ribose) polymerase (PARP) inhibitors can reduce both soman-induced neuronal degeneration and sulfur-mustard-induced epidermal necrosis. Protease and PARP inhibitors, like many of the other countermeasures for blister and nerve agents, have potent primary or secondary anti-inflammatory pharmacology. Accordingly, we hypothesize that drugs with anti-inflammatory actions against either nerve or blister agent might also display multi-threat efficacy for the inflammatory pathogenesis of both classes of chemical warfare agent.

Bibliographic Information

Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: influence of atropine dose. Taysse L; Calvet J-H; Buee J; Christin D; Delamanche S; Breton P Centre d'Etudes du Bouchet, Defense Research Centre, BP No. 3, Vert-Le-Petit 91710, France. laurent.taysse@ceb.etca.fr Toxicology (2003 Jun 30), 188(2-3), 197-209. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12767691 AN 2003245521 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This investigation compared the efficacy of diazepam and the water-soluble prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD(50) of sarin (s.c. route) and 1 min after intoxication treated by intramuscular injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiological parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were observed in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were observed. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not observed but 62.5% of the animals displayed respiratory difficulties. These symptoms were not observed when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concentration of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.

Bibliographic Information

Low-level sarin-induced alteration of immune system reaction in inbred BALB/c mice. Kassa Jiri; Krocova Z; Sevelova L; Sheshko V; Kasalova I; Neubauerova V Department of Toxicology, Purkyne Military Medical Academy, P.O. Box 35/T, 500 01 Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2003 May 3), 187(2-3), 195-203. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12699908 AN 2003232384 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

To study the influence of low-level sarin inhalation exposure on immune functions, inbred BALB/c mice were exposed to low concentrations of sarin for 60 min in the inhalation chamber. Two concentrations of sarin were chosen-asymptomatic concentration (LEVEL 1) and non-convulsive symptomatic concentration (LEVEL 2). The evaluation of immune functions was carried out using phenotyping of CD3 (T-lymphocytes), CD4 (helper T-lymphocytes), CD8 (cytotoxic T-lymphocytes) and CD19 cells (B-lymphocytes) in the lungs, blood and spleen, lymphoproliferation of spleen cells stimulated in vitro by various mitogens (concanavalin A, lipopolysaccharides), phagocyte activity of peritoneal and alveolar macrophages, production of N-oxides by peritoneal macrophages and the measurement of the natural killer cell activity at 1 week following sarin exposure. The results were compared to the values obtained from control mice exposed to pure air instead of sarin. The results indicate that not only symptomatic but also asymptomatic dose of sarin is able to alter the reaction of immune system at 1 week following exposure to sarin. While the number of CD3 cells in the lungs was slightly decreased, an increase in CD19 cells was observed especially in the lungs and blood. The reduced proportion of T-lymphocytes is caused by decay of CD4 positive T-cells. Lymphoproliferation was significantly decreased regardless of the mitogen and sarin concentration used. The production of N-oxides by peritoneal macrophages was stimulated after exposure to LEVEL 2 of sarin whereas their ability to phagocyte the microbes was increased after exposure to LEVEL 1. The natural killer cell activity was significantly higher in the case of inhalation exposure of mice to LEVEL 2 of sarin. Thus, not only organophosphorus insecticides but also nerve agents such as sarin are able to alter immune functions even at a dose that does not cause clinically manifested intoxication following the inhalation exposure.
Nevertheless, the alteration of immune functions following the inhalation exposure to a symptomatic concentration of sarin seems to be more pronounced.

Bibliographic Information

Nerve agents detection using a Cu2+/L-cysteine bilayer-coated microcantilever. Yang Yuming; Ji Hai-Feng; Thundat Thomas Department of Chemistry, Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272, USA Journal of the American Chemical Society (2003 Feb 5), 125(5), 1124-5. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12553787 AN 2003045046 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Bibliographic Information

Assessment of the effectiveness of downward water sprays for mitigating gaseous chlorine releases in partially confined spaces. Dimbour J P; Gilbert D; Dandrieux A; Dusserre G Ecole Nationale Superieure des Techniques Industrielles et des Mines d'Ales Laboratoire Genie de l'Environnement Industriel 6, Avenue de Clavieres, 30319 Cedex, Ales, France. jean-philippe.dimbour@ema.fr Journal of hazardous materials (2003 Jan 31), 96(2-3), 127-41. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12493204 AN 2002730858 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Water sprays are sometimes used as a means of mitigating accidental releases of chlorine gas. This paper gives results of a series of small-scale experimental field tests on the mitigation of chlorine gaseous releases (about 1kg/min) by various downward water sprays. The releases were from a cylinder of liquefied chlorine located in a storage shed. The shed could be configured to simulate confined and semi-confined installations used at public swimming pools. The water sprays were located in the shed. During these tests, different types of spray nozzles and storage configurations were tested under various atmospheric conditions, in order to select the best water spray. It was shown that the best chlorine downstream concentration reduction (factor 3-5 at 10m) was achieved with a flat fan water spray for the semi-confined configuration. Poor absorption in water was observed (<1%). The highest absorption (roughly 5%) was obtained with a fog water spray for the confined configuration. This is expected since chlorine is a low soluble gas. It has been evidenced for the confined configuration, that even if reduction of concentration has been observed (factor 2), downstream concentration remains very high (>10,000ppm), and above critical level of toxicity. Consequently, the use of water sprays in this case without additives to promote absorption seems to be inefficient.

[megalomania]

Chemical abstarcts is a wonderful tool. Using its subject area search feature I was able to find over 6000 journal articles about chemical warfare. Since most are irrevelant I weeded the articles down based on referenced CAS number, and then limited the search to those journals most likely to provide synthesis info. Here then are the results, about 350 articles worth:

505-60-2 (523 references)
107-44-8 (418 references)
96-64-0 (347 references)
50782-69-9 (290 references)
77-81-6 (161 references)
409-21-2 (156 references)
7732-18-5 (137 references)
756-79-6 (112 references)
51-55-8 (108 references)
7440-44-0 (96 references)
12033-89-5 (94 references)
993-13-5 (89 references)
9000-81-1 (89 references)
1344-28-1 (85 references)
81-81-2 (83 references)
541-25-3 (78 references)
311-45-5 (77 references)
34433-31-3 (74 references)
329-99-7 (73 references)
101-26-8 (70 references)
9001-08-5 (69 references)
1445-75-6 (68 references)
7782-44-7 (68 references)
1832-54-8 (67 references)
7440-70-2 (67 references)
1314-23-4 (66 references)
111-48-8 (65 references)
124-38-9 (65 references)
616-52-4 (64 references)
55-91-4 (61 references)
1832-53-7 (58 references)
7439-89-6 (53 references)
7631-86-9 (52 references)
67-56-1 (50 references)
630-08-0 (50 references)
7440-23-5 (50 references)
439-14-5 (48 references)
7440-50-8 (48 references)
693-07-2 (47 references)
75-44-5 (46 references)
7664-41-7 (46 references)
6735-59-7 (45 references)
7723-14-0 (44 references)
7440-09-7 (43 references)
7439-95-4 (41 references)
117698-12-1 (41 references)
7440-38-2 (40 references)
7727-37-9 (40 references)
64-17-5 (38 references)
7440-02-0 (37 references)

I know this is only 50 CAS numbers, the list was truncated :(

2003-April 2005

Bibliographic Information

Degradation Kinetics of VX on Concrete by Secondary Ion Mass Spectrometry. Williams, John M.; Rowland, Brad; Jeffery, Mark T.; Groenewold, Gary S.; Appelhans, Anthony D.; Gresham, Garold L.; Olson, John E. Battelle Salt Lake City Operations, West Valley City, UT, USA. Langmuir (2005), 21(6), 2386-2390. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 142:279785 AN 2005:130995 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At trace coverages on concrete surfaces, the nerve agent VX (O-Et S-2-diisopropylaminoethyl Me phosphonothiolate) degrades by cleavage of the P-S and S-C bonds, as revealed by periodic secondary ion mass spectrometry (SIMS). The obsd. kinetics were (pseudo-) first-order, with a half-life of 2-3 h at room temp. The rate increased with surface pH and temp., with an apparent second-order const. of kOH = 0.64 M-1 min-1 at 25 C and an activation energy of 50-60 kJ mol-1. These values are consistent with a degrdn. mechanism of alk. hydrolysis within the adventitious water film on the concrete surface. Degrdn. of bulk VX on concrete would proceed more slowly. Safety: VX must only be handled in approved chem. warfare surety labs. by trained agent chemists.

Bibliographic Information

The pharmacokinetics and pharmacodynamics of two HI-6 salts in swine and efficacy in the treatment of GF and soman poisoning. Lundy, Paul M.; Hill, Ira; Lecavalier, Pierre; Hamilton, Murray G.; Vair, Cory; Davidson, Corey; Weatherby, Kendal L.; Berger, Bradley J. Chemical Biological Defence Section, Defence Research and Development Canada - Suffield, Medicine Hat Alberta, AB, Can. Toxicology (2005), 208(3), 399-409. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. AN 2005:107852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anesthetized pigs were injected i.m. with 500 mg HI-6 dichloride (HI-6 2Cl) (1-[[[4-(aminocarbonyl)-pyridinio]methoxy]methyl]-2[(hydroxyimino)methyl]pyridinium dichloride; CAS 34433-31-3)) or the molar equivalent of HI-6 dimethanesulfonate (HI-6 DMS) 633 mg. Plasma HI-6 concns. were measured by HPLC (1, 3, 5, 10, 15, 30, 60 min and every 30 min until 4 h or 6 h following the i.v. or i.m. dose resp.) while a variety of physiol. responses were continuously examd. HI-6 (500 mg 2Cl or 633 mg DMS) resulted in an identical pharmacokinetic profile unaffected by atropine co-administration. Neither HI-6 salt resulted in clin. significant changes in cardiovascular or respiratory function. HI-6 DMS (1899 mg i.v.) resulted in plasma HI-6 concns. about 10 times higher than measured following i.m. 500 mg 2Cl or 633 mg DMS and resulted in small transitory effect on mean arterial pressure. Atropine plus HI-6 DMS (1-9 mg/kg or 127-172 mg/kg i.m.) protected up to 100% of guinea pigs exposed to 5  LD50 of GF (cyclohexyl Me phosphonoflouridate) or soman (pinacolyl methylphosphonofluoridate) (GD) resp. The results suggest that the two HI-6 salts have a similar pharmacokinetic profile while HI-6 DMS appears extremely safe and effective against nerve agents and may be as suitable for human use.

Bibliographic Information

Antidotal treatment of GF-agent intoxication in mice with bispyridinium oximes. Sevelova, Lucie; Kuca, Kamil; Krejcova-Kunesova, Gabriela. Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2005), 207(1), 1-6. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 142:213533 AN 2004:1067008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It was shown that intoxications with GF-agent are rather resistant to convential oxime therapy; therefore, the development of new oximes in an effort to improve this unsatisfactory situation continues. Upon screening in vitro reactivation test for oximes, that were either newly synthesized at our department, or those that have never been tested for reactivation of GF-inhibited acetylcholinesterase (AChE), three oximes {(1,4-bis(4-hydroxyiminomethylpyridinium)butane dibromide) (K033); (1-(2-hydroxyiminomethylpyridinium)-3-(3-carbamoylpyridinium)-2-oxa-propane dichloride) (HS-6); and (1-(2-hydroxyiminomethylpyridinium)-4-(4-carbamoylpyridinium)-but-2-ene dibromide) (BI-6)} with the highest reactivation potency were chosen for in vivo testing in our study. (1,3-Bis(4-hydroxyiminomethylpyridinium)-2-oxa-propane dibromide) (obidoxime); (1-(2-hydroxyiminomethylpyridinium)-3-(4-carbamoylpyridinium)-2-oxa-propane dichloride) (HI-6); and (1,1-bis(4-hydroxyiminomethylpyridinium)-methane dibromide) (methoxime) were chosen for comparison as a std. antidotal treatment. All the oximes were applied at the same proportion of their LD50 value (5%), and because of the different acute toxicity of the oximes, the molar concns. of their solns. for i.m. administration were considerably different. The highest therapeutic ratio was achieved for therapeutic regimen consisting of HI-6 and atropine. The significantly (P < 0.05) lowest effectivity in treatment of supralethal GF-agent poisoning in comparison with all the other therapeutic regimens, was surprisingly obsd. for methoxime. HS-6, K033 and BI-6 as well as obidoxime were comparably effective antidotes against GF-agent intoxication and their therapeutic ratios were similar.

Bibliographic Information

Bis(dialkylamide)hydrogen Dibromobromate Precursors of Hypobromite Ion in Reactions with Nerve and Blister Agent Simulants. Simanenko, Yuri S.; Savelova, Vera A.; Prokop'eva, Tatyana M.; Mikhailov, Vasily A.; Turovskaya, Marya K.; Karpichev, Eugen A.; Popov, Anatolii F.; Gillitt, Nicholas D.; Bunton, Clifford A. L.M. Litvinenko Institute of Physical Organic Coal Chemistry, National Academy of Sciences of Ukraine, Donetsk, Ukraine. Journal of Organic Chemistry (2004), 69(26), 9238-9240. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 142:108643 AN 2004:949799 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hypobromite ion, BrO-, is an effective -nucleophile that reacts rapidly with activated phosphorus(V) and sulfonate esters. The parent acid rapidly oxidizes org. sulfides and aryloxide ions. At pH 10-11 BrO- and HOBr coexist in water and are potentially useful as decontaminants of chlorosulfide blister agents and the phosphonyl nerve agents. Bis(dialkylamide)hydrogen dibromobromates are well characterized, stable, solids which rapidly form HOBr-BrO- in mildly alk. water. Reactions of 4-nitrophenyl di-Et phosphate and phosphonate, which are simulants of the phosphonofluoridate nerve agents, and of 4-nitrophenyl tosylate, with BrO- are rapid (t1/2 = 60-700 s) with 0.1 M BrO-, under conditions in which oxidns. of org. sulfides are too fast to be followed by conventional methods.

Bibliographic Information

Localization of substance P gene expression for evaluating protective countermeasures against sulfur mustard. Casbohm, Stacy L.; Rogers, James V.; Stonerock, Mindy K.; Martin, Jamie L.; Ricketts-Kaminsky, Karen M.; Babin, Michael C.; Casillas, Robert P.; Sabourin, Carol L. K. Medical Research and Evaluation Facility, Battelle Memorial Institute, Columbus, OH, USA. Toxicology (2004), 204(2-3), 229-239. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:421169 AN 2004:789078 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard [bis(2-chloroethyl)sulfide; SM] is a chem. warfare agent that produces edema and blister formation with a severe inflammatory reaction. The mouse ear vesicant model for SM injury has been used to evaluate pharmacol. agents for countering SM dermal injury. The vanilloid olvanil reduces SM-induced edema and mRNA expression of cytokines and chemokines, suggesting that blocking the inflammatory effects of neuropeptides, such as substance P (SP), may provide protection against SM-induced dermal injury. This study examd. SP expression in mice exposed to SM (0.16 mg) on the inner surface of the right ear, with or without olvanil pretreatment at 1, 10, 30, 60, and 360 min following exposure. In naive skin, SP mRNA localization was assocd. with blood vessels and sebaceous glands. In SM-exposed skin, SP mRNA was also detected in perivascular dermal cells. Immunohistochem. localization of SP protein was obsd. in the ear skin of naive, SM-, olvanil/SM-, and vehicle-treated mice. Quantification of SP+ perivascular dermal cells revealed that SM exposure led to a significant increase (P  0.05) in SP+ cells over the obsd. time period. Olvanil pretreatment significantly reduced (P  0.05) the mean no. of SP+ cells at 60 and 360 min. This study demonstrates that SP expression could provide an addnl. endpoint for evaluating the effectiveness of vanilloid drugs on SM-induced skin inflammation.

Bibliographic Information

Photocatalytic oxidation of VX simulant 2-(butylamino)ethanethiol. Vorontsov, Alexandre V.; Chen, Yi-Chuan; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russian Federation, Russia. Journal of Hazardous Materials (2004), 113(1-3), 89-95. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 141:383605 AN 2004:745354 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Photocatalytic oxidn. of 2-(butylamino)ethanethiol (BAET) was undertaken in aq. suspension of TiO2 Hombikat UV 100 and Degussa P25 under different initial reaction conditions in order to det. the best parameters for the fastest mineralization of the substrate. BAET is considered to be a simulant for the VX chem. warfare agent. The application of ultrasound had only a small pos. effect on the BAET photocatalytic degrdn. The highest mineralization rate of 0.433 mg/L-min was found in unbuffered TiO2 Degussa P25 suspension with initial pH of .apprx.9.4, TiO2 concn. 500 mg/L and the initial BAET concn. 1000 mg/L. Decreasing of the initial soln. pH to 6.1 stops the mineralization of BAET while increasing of pH to .apprx.11 drastically changed the degrdn. profile. At this initial pH, the 1st 100 min of reaction led to only oxidn. of S moiety and org. intermediates accumulated in the soln. Thereafter, mineralization of the products started. The main detected volatile product was Bu aldehyde and the main polar one was 2-(butylamino)acetic acid. In the case of TiO2 Hombikat UV 100, conversion of TOC at initial pH 11 exceeded that at initial pH 9.1. For Degussa P25, the starting pH 9.4 was the best for TOC conversion. The results can be used for the treatment of water and wastewater.

Bibliographic Information

Synthesis and Chemosensory Behavior of Anthracene Bisimide Derivatives. Ilhan, Faysal; Tyson, Daniel S.; Meador, Michael A. Polymers Branch Materials Division, NASA Glenn Research Center, Cleveland, OH, USA. Chemistry of Materials (2004), 16(16), 2978-2980. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 141:268374 AN 2004:559158 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors used the photoenolization reaction of a dibenzoyl-p-xylene deriv. to synthesize two new, highly substituted anthracene-based mols.: N,N'-bis(p-nitrophenyl)-1,5-bis(p-(tetraethyleneglycoloxy)phenyl)anthracene-2,3,6,7-tetracarboxyl bis-imide (ABI-NO2) and N,N'-bis(p-aminophenyl)-1,5-bis(p-(tetraethyleneglycoloxy)phenyl)anthracene-2,3,6,7-tetracarboxyl bis-imide (ABI-NH2). ABI-NO2 and ABI-NH2 maintained photostability with longer wavelength absorption and emission spectra as compared to unsubstituted anthracene. Conversion of the terminal nitro groups to amines created an internal photoinduced electron-transfer that quenched the luminescence of ABI-NH2. Reversible or irreversible reaction of the attached amines resulted in fluorescence recovery. Sensitivity, of ABI-NH2 and other potential derivs., to toxic chems. may prove useful for early detection systems. Electronic supplementary information (ESI) is available at http://pubs.acs.org and contains synthetic prepns. of the ABI-NO2 and ABI-NH2 compds.

Bibliographic Information

Dimethyl Methylphosphonate Decomposition on Titania-Supported Ni Clusters and Films: A Comparison of Chemical Activity on Different Ni Surfaces. Zhou, J.; Ma, S.; Kang, Y. C.; Chen, D. A. Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA. Journal of Physical Chemistry B (2004), 108(31), 11633-11644. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 141:195800 AN 2004:528273 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The thermal decompn. of di-Me methylphosphonate (DMMP) has been studied in ultrahigh vacuum by temp. programmed desorption (TPD) and XPS on Ni clusters and films deposited on TiO2(110). The four different Ni surfaces under investigation consisted of small Ni clusters (5.0  0.8 nm diam., 0.9  0.2 nm height) deposited at room temp. and quickly heated to 550 K, large Ni clusters (8.8  1.4 nm diam., 2.3  0.5 nm height) prepd. by annealing to 850 K, a 50 monolayer Ni film deposited at room temp., and a 50 monolayer Ni film annealed to 850 K. The morphologies of the Ni surfaces were characterized by scanning tunneling microscopy (STM). TPD expts. show that CO and H2 are the major gaseous products evolved from the decompn. of DMMP on all of the Ni surfaces, and mol. DMMP and methane desorption were also obsd. The product yields for CO and H2 were highest for reactions on the small Ni clusters and unannealed Ni film and lowest for reactions on the large clusters and annealed film. Furthermore, XPS expts. demonstrate that the unannealed Ni surfaces decomp. a greater fraction of DMMP at room temp. The loss of activity for the annealed surfaces is not caused by a redn. in surface area because the annealed surfaces have approx. the same surface area as the small clusters. CO adsorption studies suggest that the loss of activity upon annealing cannot be completely due to a decrease in surface defects, such as step and edge sites, and we propose that a TiOx moiety is responsible for blocking active sites on the annealed Ni surfaces. In comparison to the TiO2 surface, the small Ni clusters are more chem. active because a greater fraction of DMMP decomps. at room temp., and the total amt. of DMMP decompn. is also higher on the small Ni clusters. Although DMMP decomps. on TiO2 to produce gaseous Me radicals, methane, and H2, the activity of the substrate surface itself appears to be quenched in the presence of the Ni clusters and films.
However, the TiO2 support plays a significant role in providing a source of oxygen for the recombination of at. carbon on Ni to form CO, which desorbs above 800 K.

Bibliographic Information

Reductive Destruction of Chemical Warfare Agent Simulants in Water. Kiddle, James J.; Mezyk, Stephen P. Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA. Journal of Physical Chemistry B (2004), 108(28), 9568-9570. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 141:194628 AN 2004:479880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The efficient detection, decontamination, and destruction of chem. warfare (CW) agents remain an active area of scientific research. Rate consts. for the reaction of substituted di-Et phosphates and phosphonates with the hydroxyl radical and hydrated electron have been measured in water to elucidate the primary destruction pathway for the CW agents Tabun (GA), Sarin (GB), Soman (GD), and VX with these two species. The measured kinetics for simulants with leaving groups that more closely mimic these actual CW agents predict that reductive destruction will be the most efficient mechanism, and that nontoxic simulants such as alkyl phosphonates undergo different redox chem.

Bibliographic Information

Detect-to-warn cell based sensing technology: Chemical sensing of multiple agents in a cascade. Zhang, Xuan; Yang, Mo; Kohr, Bonnie; Morgan, Andre; Ozkan, Cengiz S. Mechanical Engineering Department, University of California, Riverside, CA, USA. Materials Research Society Symposium Proceedings (2004), EXS-1(Architecture and Application of Biomaterials and Biomolecular Materials), 187-195. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:119751 AN 2004:469459 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Techniques to develop highly sensitive biosensors are largely dependent upon the properties of the material and its assocd. interactions. A novel challenge is the development of effective biosensors based on fundamental research in biotechnol., genetics and information technol., which will change the existing axiom of "detect -to-treat" to "detect -to-warn". Current biosensor technologies encompass antibody-antigen interactions, hormone-receptor interactions, and nucleic acid based assays. These sensors are useful in narrow band applications requiring high specificity for agent identification. Mammalian cells have excitable cell membranes that function as novel sensing platforms by producing a variation in the extracellular potential based on the chem. stimulus. Here we report a method of developing single cell based sensors by integrating the biol. tool of dielectrophoresis with the micro fabrication technol. We display its ability to detect a large no. of chem. agents, reject false alarms, characterize the chem. agent functionality and det. the assocd. sensitivity limit, and the physiol. response in terms of the calcium transients for each specific chem. agent that produces synergistic effects on humans. We finally demonstrate the capability of a single cell based sensor to identify general chem. agents in cascade.

Bibliographic Information

Preparation, Derivatization with Trimethylsilyldiazomethane, and GC/MS Analysis of a "Pool" of Alkyl Methylphosphonic Acids for Use as Qualitative Standards in Support of Counterterrorism and the Chemical Weapons Convention. Crenshaw, Michael D.; Cummings, David B. Battelle Memorial Institute, Columbus, OH, USA. Phosphorus, Sulfur and Silicon and the Related Elements (2004), 179(6), 1009-1018. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 141:225604 AN 2004:460857 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

There are hundreds of nerve agents in the class of alkyl methylphosphonofluoridates covered by Schedule 1 of the CWC (Chem. Weapons Convention). Hydrolysis of these sarin-like nerve agents results in an equal no. of alkyl methylphosphonic acids. These alkyl methylphosphonic acids are persistent and provide good evidence of specific agent prodn. or use. To support the CWC and counterterrorism activities, it is desirable to have ready access to each of these hydrolysis products for use as qual. stds. A means for simultaneously producing multiple alkyl methylphosphonates from methylphosphonic acid, phenylarsonic acid and the corresponding alcs. was developed. Derivatization of these alkyl methylphosphonic acids with trimethylsilyldiazomethane yields the corresponding Me esters which are suitable for GC/MS anal.

Bibliographic Information

MBE grown AlN films on SiC for piezoelectric MEMS sensors. Doppalapudi, Dharanipal; Mlcak, Richard; Chan, Jeffrey; Tuller, Harry; Bhattacharya, Anirban; Moustakas, Theodore. Boston MicroSystems Inc., Woburn, MA, USA. Materials Research Society Symposium Proceedings (2004), 798(GaN and Related Alloys--2003), 403-408. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:132159 AN 2004:423724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Miniaturized piezoelec. sensors based on Microelectromech. Systems (MEMS) offer the advantages of reduced size, reduced power consumption, increased sensitivity coupled with the ability to form compact multi-sensor arrays. Fabrication of such sensors from single crystal materials further insure more highly reproducible and stable devices with improved performance. The authors describe the integration of MBE grown AlN films onto photoelectrochem. machined SiC microcantilevers and membranes. AlN exhibits excellent piezoelec. properties, including an electromech. coupling coeff. of 0.088 and a high in-plane acoustic velocity (.apprx.5700 m/s) as well as excellent thermal-mech. compatibility with SiC. The fabrication of AlN-SiC-based microresonators and flexural plate wave devices, and their application to chem., biol. and fluid sensing, are reported.

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Biochemical changes in mouse lung after subcutaneous injection of the sulfur mustard 2-chloroethyl 4-chlorobutyl sulfide. Elsayed, Nabil M.; Omaye, Stanley T. Hurley Consulting Associates, Department of Scientific Affairs, Chatham, NJ, USA. Toxicology (2004), 199(2-3), 195-206. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:237904 AN 2004:404473 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant-type chem. warfare agent (CWA) introduced in World War I which continues to be produced, stockpiled, and occasionally deployed by some countries, and could be used potentially by terrorists. Exposure to HD can cause erythema, blisters, corneal opacity, and airway damage. The authors have reported previously that s.c. (SC) injection of immunodeficient athymic nude mice with the half mustard Bu 2-chloroethyl sulfide (BCS) causes systemic biochem. changes in several organs distal to the exposure site. In the present study, the authors examd. the response of nonimmunodeficient Swiss Webster mice to the mustard, 2-chloroethyl 4-chlorobutyl sulfide (CECBS). In a pilot study, a single SC injection of 20-25 L/mouse caused death within 24 h. Consequently, the authors used 5 L/mouse (.apprx.0.017 mg/kg body wt.) of neat CECBS or an equal vol. of saline as control. The authors examd. lungs after 1, 24, and 48 h for biochem. changes including total and oxidized glutathione, protein, DNA, and lipid peroxidn. contents in tissue homogenate, and superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, and glutathione S-transferases activities in the cytosol. After 1 and(or) 24 h, significant changes were found that were resolved by 48 h. These changes mimicked those of HD and BCS and were generally consistent with free radical-mediated oxidative stress. The implications of these observations are 2-fold. First, dermal exposure to low-dose mustard gas could elicit systemic changes impacting distal organs such as the lungs. It also suggests that antioxidants could potentially modulate the response and reduce the damage. Second, although the use of known CWAs such as HD is prohibited, analogs that are not recognized as agents are as toxic and could be dangerous if acquired and used by potential terrorists.

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A thermo-chemical surface treatment of AlN powder for the aqueous processing of AlN ceramics. Olhero, S. M.; Novak, S.; Oliveira, M.; Krnel, K.; Kosmac, T.; Ferreira, J. M. F. Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, Aveiro, Port. Journal of Materials Research (2004), 19(3), 746-751. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 141:41662 AN 2004:346050 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Dense aluminum nitride ceramics were prepd. by sintering green bodies at 1750C for 2 h. These green bodies were prepd. by aq. slip-casting from a powder that was surface-treated to prevent hydrolysis. The surface treatment of the aluminum nitride (AlN) powder consisted of dispersing the powder in warm-water solns. of aluminum dihydrogenphosphate Al(H2PO4)3. Different treatment temps. in the range 30-80C were tested. For all the tested temps., the surface-treated AlN powder was found to be water-resistant, even after drying and/or redispersion. Various com. dispersants were tested for their effectiveness, and the amt. of dispersant was optimized in terms of a high solids loading of the suspension and an acceptable viscosity for slip casting. Based on these studies, a stable aq. suspension of AlN powder, treated at 60C, with a total solids loading of 50 vol%, was prepd. using CaF2 as a sintering additive. The well-dispersed powder made it possible to prep. green samples with close particle packing and relatively high sintered densities, i.e., >96%.

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Progress in developing nerve agent sensors using combinatorial techniques. DiCesare, John C.; Parker, Jennifer; Horne, Starr N.; Kita, Justin; Earni, Raghu; Peeples, Christopher. Department of Chemistry and Biochemistry, The University of Tulsa, Tulsa, OK, USA. Materials Research Society Symposium Proceedings (2004), Volume Date 2003, 787(Molecularly Imprinted Materials--2003), 17-22. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 141:201377 AN 2004:280892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Development of a sensor capable of selective detection of specific nerve agents is imperative in today's atm. of terrorism. The sensor needs to be inexpensive, portable, reliable, absent of false positives and available to all military and first responders. By utilizing the techniques of mol. imprinting, combinatorial chem., silica sol-gel synthesis and lanthanide luminescence, a sensor for the detection of the hydrolysis product of the nerve agent soman is being developed. There are many parameters that require investigation in order for the sensor to become a reality. These parameters include (1) the selection of a chelate that can bind to the lanthanide and anchor the nerve agent simulant during the formation of the molecularly imprinted polymer, (2) the detn. of the environment best suited for this complex formation, (3) the formation, as well as modification of the silica sol-gel for mol. imprinting to take place, and (4) the proper quantity and ratios of monomers used to create the three dimensional imprint. Key to the success of optimizing these parameters is the development of a combinatorial assay that allows for the synthesis and testing of tens of thousands of combinations of parameters. Work on the development of the combinatorial assay has lead to a method of prepg. thin film polymers capable of analyzing the presence of nerve agent simulants. Current work is underway to validate the combinatorial assay and to synthesize and evaluate a library of sensor materials selective for nerve agents.

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Synthesis and adsorption properties of intimately intermingled mixed metal oxide nanoparticles. Medine, Gavin M.; Zaikovskii, Vladimir; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2004), 14(4), 757-763. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 140:359698 AN 2004:131545 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A series of intimately intermingled mixed metal oxide nanoparticles were prepd. via a modified aerogel procedure (MAP). These mixed oxides were composed of alk. earth oxides and aluminas. It was found that the surface area and reactivity of these materials decreased on going from magnesium to barium in these intimately intermingled metal oxides. The samples were analyzed by HRTEM and the images obtained illustrate the degree of mixing throughout each of the intermingled mixed metal oxides. As well as synthesizing and characterizing these samples, standardized adsorption tests were also carried out and compared to those of individual metal oxide nanoparticles and phys. mixts. of metal oxide nanoparticles. The following tests have been shown to be effective in detg. the adsorption properties of metal oxide nanoparticles: (i) destructive adsorption of paraoxon (a surrogate of the chem. warfare nerve agent, VX) and (ii) the adsorption of acid gases. The data clearly show enhanced kinetics and capacities for the intermingled AP-MgAl2O4 and indeed, the data suggest that surface reactivities can be tailored by the aerogel mixing process.

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Examination of changes in connective tissue macromolecular components of large white pig skin following application of Lewisite vapour. Lindsay, Christopher D.; Hambrook, Joy L.; Brown, Roger F. R.; Platt, Jan C.; Knight, Robert; Rice, Paul. Biomedical Sciences Department, Salisbury, UK. Journal of Applied Toxicology (2004), 24(1), 37-46. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 140:316407 AN 2004:99102 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to provide information about the degradative processes that occur in major connective tissue components in skin following exposure of large white pigs to Lewisite vapor. Of particular interest were alterations in glycoproteins, which are known to mediate dermo-epidermal attachment (laminin and type IV collagen) and the main collagen found in the dermis (type III collagen). The immunostaining of transfer blots from skin exts. run on SDS-PAGE gels revealed no evidence of crosslinking of laminin or of type III or IV collagen. However, there was evidence of a very considerable degrdn. of laminin and, to a lesser extent, of type IV collagen. Type III collagen did not appear to be degraded in skin exposed to Lewisite. These degradative processes appeared to be more severe than found in previous studies in Yucatan mini-pigs percutaneously exposed to sulfur mustard, in which only laminin was found to undergo partial cleavage rather than wholesale degrdn. The results suggest that damage to macromol. components in the sub-epidermal basement membrane in skin which mediate dermo-epidermal sepn. processes may be a common feature in the mechanism of action of vesicating agents such as Lewisite and sulfur mustard. It is of interest that the damage to laminin in this study appeared to be more severe than that previously found for sulfur mustard. This suggests that skin can suffer substantial damage yet, in the case of Lewisite exposure, recover relatively quickly. However, Lewisite is not an alkylating agent. Sulfur mustard, in contrast, generates characteristically slow healing lesions, most probably because of its ability to alkylate cell types that normally would be involved in skin regenerative processes.

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In vitro-in vivo extrapolation: estimation of human serum concentrations of chemicals equivalent to cytotoxic concentrations in vitro. [Erratum to document cited in CA139:346894]. Gulden, Michael; Seibert, Hasso. Institut fur Experimentelle Toxikologie, Universitatsklinikum Schleswig-Holstein, Kiel, Germany. Toxicology (2003), 192(2-3), 265. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 141:152304 AN 2003:826065 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Equation (6) should read: EC50 = ECu50  (1 + KOW  V'L, in vitro) + Cbin vitro. The cor. version of Table 2 is given.

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Solid-Phase Synthesis of Some Alkyl Hydrogen Methylphosphonates. Barucki, Hubert; Black, Robin M.; Kinnear, Kenneth I.; Holden, Ian; Read, Robert W.; Timperley, Christopher M. Defence Science and Technology Laboratory, Wiltshire, UK. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(10), 2279-2286. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 141:23606 AN 2003:764571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Eleven alkyl H methylphosphonates of structure RO(HO)P(O)Me (R = Me, Et, Pr, i-Pr, Bu, hexyl, octyl, cyclohexyl, cycloheptyl, cyclooctyl, and Me3CCH(Me)) were made by phosphoramidite chem. on hydroxymethyl polystyrene resin with yields 30%. MeP(NiPr2)Cl was attached to hydroxymethyl polystyrene using Et3N in CH2Cl2 to give MeP(NiPr2)OCH2-bound polystyrene, which was reacted with various alcs. in MeCN in the presence of tetrazole followed by oxidn. using tBuO2H in toluene; the final product was cleaved from MeP(O)(OR)OCH2-bound resin using CF3CO2H. NCCH2CH2OP(OR)O2H (R = Et iPr) were also prepd. via solid-phase synthesis.

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Effects of sulfur mustard on transcription in human epidermal keratinocytes: Analysis by mRNA differential display. Platteborze, Peter L. Pharmacology Division, USAMRICD, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2003), 23(4), 249-254. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 139:360142 AN 2003:619968 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study examines the transcriptional response of human epidermal keratinocytes (HEK) to sulfur mustard (HD) in order to gain a better understanding of the intracellular events that result in cytotoxicity. Differential display polymerase chain reaction technol. was used to examine the relative transcriptional activity of healthy cells to those exposed to subvesicating or vesicating concns. of HD for 4 h. Approx. 2% of the HEK transcriptome had altered expression. Sixty of the most prominently altered transcripts were characterized. Important upregulated genes include NADH dehydrogenase III, GADD45 and ubiquitin. Key downregulated genes include type I keratin 14, -enolase and caltractin. Many of the identified transcripts protein products presently do not have an assigned function and eleven transcripts were unidentifiable. These transcriptional alterations provide one of the first mol. insights into the intracellular events induced by HD.

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Degradation of VX and sulfur mustard by enzymatic haloperoxidation. Amitai, G.; Adani, R.; Hershkovitz, M.; Bel, P.; Rabinovitz, I.; Meshulam, H. Division of Medicinal Chemistry, Israel Institute for Biological Research, Ness Ziona, Israel. Journal of Applied Toxicology (2003), 23(4), 225-233. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 140:72285 AN 2003:619965 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chloroperoxidase (CPO) isolated from Caldariomyces fumago (20 U ml-1) together with urea hydrogenperoxide (UPER, 0.5 mM) and sodium chloride as co-substrate (NaCl, 0.5 M) caused rapid breakdown of VX (10 M) (t1/2=8 s, 25, 50 mM tartarate, pH 2.75). Glucose oxidase (GOX, Aspergillus niger) and glucose were used as an alternative source for H2O2. A mixt. of GOX (20 U ml-1), glucose (GLU 0.45 M), CPO (20 U ml-1) and NaCl (0.5 M) caused a 3.8-fold slower degrdn. of VX (10 M) (t1/2=30 s, 25, 50 mM tartarate, pH 2.75). The concns. of H2O2 and chlorine produced by this enzyme/substrate mixt. depended mainly on the GLU concn. Horseradish peroxidase (HRP) together with UPER (1 mM) and sodium iodide (NaI, 0.05 M) caused progressive degrdn. of VX that was more than 400-fold slower than with CPO (20 U ml-1), UPER (0.5 mM) and NaCl (0.5 M) (t1/2=55 min, 25, pH 8). Skin decontamination of VX by CPO was tested in pig-ear skin in vitro. The chem. agent VX (0.01 M, 100 l) was degraded by 98% within 3 h of skin diffusion when a mixt. of UPER/NaCl/CPO was applied 60 min prior to VX application. A mixt. of UPER/NaCl without CPO also caused significant VX degrdn. (94%) during skin diffusion whereas it did not cause any VX degrdn. in soln. Degrdn. of VX in skin, obtained without exogenous CPO, may indicate involvement of endogenous intradermal haloperoxidase-like enzyme. Reagent UPER (1 mM) did not cause any degrdn. of VX in soln. or during its skin diffusion. Furthermore, a mixt. of CPO, UPER and NaCl caused rapid degrdn. of sulfur mustard (HD). Sulfur mustard (50 M) incubated in the presence of CPO (4 U ml-1), UPER (0.05 M) and NaCl (0.5 M) at pH 2.75 and 30 was oxidized by 97% and 99% within 5 and 10 min, resp. The oxidn. products HD sulfoxide, HD sulfone and HD sulfoxidevinyl were identified by GC/MS in the enzymic chloroperoxidn. mixt.

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Analysis of Chemical Neutralization Products of Phosphonothiolates by Gas Chromatography Mass Spectrometry. Gupta, A. K.; Palit, M.; Dubey, D. K.; Raza, S. K. Defence Research & Development Establishment, Gwalior, India. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(8), 1631-1637. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 140:303747 AN 2003:603631 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A series of phosphonothioates, including the highly toxic O-Ethyl-S-(2-diisopropylamino) Et methylphosphonothioate (VX), were subjected to chem. neutralization reaction with metallic sodium; the reaction products were identified by GC/MS. The phosphonothioates decomp. to their resp. phosphonic and phosphonothioic acids and this results in the detoxification of VX. Phosphonodithioates R1PO(SR2)2 (2-8; R1 = Me, Et, n-Pr, iPr; R2 = Bu, n-Pr) were reacted with metallic sodium, giving disulfides R2SSR2 and R1PS(OH)2. Trithioate MePS(SPr)2 (9) upon reaction with Na gave polysulfides R2SSR2, R2SSSR2 and R2SSSSR2 (R2 = n-Pr); MePO(OH)2 and MePS(OH)2. All obtained acids were analyzed by GC/MS in the form of their trimethylsilyl esters. GC/MS technique in both EI and CI mode was applied for reaction monitoring and final identification of the neutralization products formed in this reaction.

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Kinetics of Spontaneous Hydrolysis of O-(2,2-Dimethylcyclopentyl)-methylfluorophosphonate and of Hydrolysis During Constant pH Value of the Reaction Medium. Cekovic, Boban; Jovanovic, Bratislav; Lukovic, Zoran. Military Technical Institute, Belgrade, Yugoslavia. Phosphorus, Sulfur and Silicon and the Related Elements (2003), 178(7), 1521-1540. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 140:253619 AN 2003:524831 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Kinetics of hydrolysis of O-(2,2-dimethylcyclopentyl)-methylfluorophosphonate (1) in dil. aq. soln. was investigated. Rates of hydrolysis of O-(2,2-dimethylcyclopentyl)-methylfluorophosphonate were measured as a function of pH in the range from 3 to 9 in temp. range from 25 to 40. Spontaneous hydrolysis was also studied without monitoring of the pH-value. Rate consts. and activation parameters of the hydrolysis were obtained. The lowest hydrolysis rates for 1 were obtained at pH range 4-6, the reaction was several times faster at pH 3.0 and more than ten times faster at pH 9.0. For dild. solns. the spontaneous hydrolysis had half-life time (t1/2) about 2.8 days at 25, the reaction may be accelerated in more concd. solns. due to proton autocatalysis. Obtained data can be used in processes of degrdn. and detoxification of highly toxic warfare-type compds.

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Enhanced Degradation of Chemical Warfare Agents through Molecular Engineering of the Phosphotriesterase Active Site. Hill, Craig M.; Li, Wen-Shan; Thoden, James B.; Holden, Hazel M.; Raushel, Frank M. Department of Chemistry, Texas A&M University, College Station, TX, USA. Journal of the American Chemical Society (2003), 125(30), 8990-8991. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 139:208973 AN 2003:516949 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The bacterial phosphotriesterase has been utilized as a template for the evolution of improved enzymes for the catalytic decompn. of organophosphate nerve agents. A combinatorial library of active site mutants was constructed by randomizing residues His-254, His-257, and Leu-303. The collection of mutant proteins was screened for the ability to hydrolyze a chromogenic analog of the most toxic stereoisomer of the chem. warfare agent, soman. The mutant H254G/H257W/L303T catalyzed the hydrolysis of the target substrate nearly 3 orders of magnitude faster than the wild-type enzyme. The x-ray crystal structure was solved in the presence and absence of diisopropyl Me phosphonate. The mutant enzyme was ligated to an addnl. divalent cation at the active site that was displaced upon the binding of the substrate analog inhibitor. These studies demonstrate that substantial changes in substrate specificity can be achieved by relatively minor changes to the primary amino acid sequence.

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In vitro-in vivo extrapolation: estimation of human serum concentrations of chemicals equivalent to cytotoxic concentrations in vitro. Gulden, Michael; Seibert, Hasso. Institut fur Experimentelle Toxikologie, Universitatsklinikum Schleswig-Holstein, Kiel, Germany. Toxicology (2003), 189(3), 211-222. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:346894 AN 2003:484566 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In the present study an extrapolation model for estg. serum concns. of chems. equiv. to in vitro effective concns. is developed and applied to median cytotoxic concns. (EC50) detd. in vitro. Nominal concns. of a chem. in serum and in vitro are regarded as equiv., if they result in the same aq. concn. of the unbound form. The algorithm used is based on equil. distribution and requires albumin binding data, the octanol-water partition coeff. (Kow), and the albumin concns. and lipid vol. fractions in vitro and in serum. The chems. studied cover wide ranges of cytotoxic potency (EC50: 2.5-530 000 M) and lipophilicity (log Kow: -5 to 7). Their albumin binding characteristics were detd. by an in vitro cytotoxicity test as described previously. The equivalent serum concns. of 19 of the 33 compds. investigated, having high protein binding and/or lipophilicity, were substantially higher than the EC50-values, by factors of 2.5-58. Prominent deviations between the equiv. nominal concns. in serum and in vitro were largely restricted to chems. with higher cytotoxic potency (EC501000 M). The results suggest that ests. of equiv. serum concns. based on in vitro data are robust for chems. with low lipophilicity (log Kow2) and low potency (EC50>1000 M). With more potent chems. or those with higher lipophilicity partitioning into lipids and/or binding to serum proteins have to be taken into account when estg. in vivo serum concns. equiv. to in vitro effective concns.

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Putative role of proteolysis and inflammatory response in the toxicity of nerve and blister chemical warfare agents: Implications for multi-threat medical countermeasures. Cowan, F. M.; Broomfield, C. A.; Lenz, D. E.; Smith, W. J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2003), 23(3), 177-186. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 139:241394 AN 2003:447085 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review. Despite the contrasts in chem. and toxicity, for blister and nerve chem. warfare agents there may be some analogous proteolytic and inflammatory mediators and pathol. pathways that can be pharmacol. targets for a single-drug multi-threat medical countermeasure. The dermal-epidermal sepn. caused by proteases and bullous diseases compared with that obsd. following exposure to the blister agent sulfur mustard (2,2'-dichlorodiethyl sulfide) has fostered the hypothesis that sulfur mustard vesication involves proteolysis and inflammation. In conjunction with the paramount toxicol. event of cholinergic crisis that causes acute toxicity and ppts. neuronal degeneration, both anaphylactoid reactions and pathol. proteolytic activity have been reported in nerve-agent-intoxicated animals. Two classes of drugs already have demonstrated multi-threat activity for both nerve and blister agents. Serine protease inhibitors can prolong the survival of animals intoxicated with the nerve agent soman and can also protect against vesication caused by the blister agent sulfur mustard. Poly(ADP-ribose) polymerase (PARP) inhibitors can reduce both soman-induced neuronal degeneration and sulfur-mustard-induced epidermal necrosis. Protease and PARP inhibitors, like many of the other countermeasures for blister and nerve agents, have potent primary or secondary anti-inflammatory pharmacol. Accordingly, we hypothesize that drugs with anti-inflammatory actions against either nerve or blister agent might also display multithreat efficacy for the inflammatory pathogenesis of both classes of chem. warfare agent.

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Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: Influence of atropine dose. Taysse, L.; Calvet, J.-H.; Buee, J.; Christin, D.; Delamanche, S.; Breton, P. Defense Research Centre, Centre d'Etudes du Bouchet, Vert-Le-Petit, Fr. Toxicology (2003), 188(2-3), 197-209. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:346870 AN 2003:415467 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This investigation compared the efficacy of diazepam and the water-sol. prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD50 of sarin (s.c. route) and 1 min after intoxication treated by i.m. injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiol. parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were obsd. in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were obsd. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not obsd. but 62.5% of the animals displayed respiratory difficulties. These symptoms were not obsd. when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concn. of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.

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Low-level sarin-induced alteration of immune system reaction in inbred BALB/c mice. Kassa, Jiri; Krocova, Z.; Sevelova, L.; Sheshko, V.; Kasalova, I.; Neubauerova, V. Department of Toxicology, Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2003), 187(2-3), 195-203. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:241449 AN 2003:289956 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To study the influence of low-level sarin inhalation exposure on immune functions, inbred BALB/c mice were exposed to low concns. of sarin for 60 min in the inhalation chamber. Two concns. of sarin were chosen-asymptomatic concn. (LEVEL 1) and non-convulsive symptomatic concn. (LEVEL 2). The evaluation of immune functions was carried out using phenotyping of CD3 (T-lymphocytes), CD4 (helper T-lymphocytes), CD8 (cytotoxic T-lymphocytes) and CD19 cells (B-lymphocytes) in the lungs, blood and spleen, lymphoproliferation of spleen cells stimulated in vitro by various mitogens (Con A, lipopolysaccharides), phagocyte activity of peritoneal and alveolar macrophages, prodn. of N-oxides by peritoneal macrophages and the measurement of the natural killer cell activity at 1 wk following sarin exposure. The results were compared to the values obtained from control mice exposed to pure air instead of sarin. The results indicate that not only symptomatic but also asymptomatic dose of sarin is able to alter the reaction of immune system at 1 wk following exposure to sarin. While the no. of CD3 cells in the lungs was slightly decreased, an increase in CD19 cells was obsd. esp. in the lungs and blood. The reduced proportion of T-lymphocytes is caused by decay of CD4 pos. T-cells. Lymphoproliferation was significantly decreased regardless of the mitogen and sarin concn. used. The prodn. of N-oxides by peritoneal macrophages was stimulated after exposure to LEVEL 2 of sarin, whereas their ability to phagocyte the microbes was increased after exposure to LEVEL 1. The natural killer cell activity was significantly higher in the case of inhalation exposure of mice to LEVEL 2 of sarin. Thus, not only organophosphorus insecticides but also nerve agents such as sarin are able to alter immune functions even at a dose that does not cause clin. manifested intoxication following the inhalation exposure. Nevertheless, the alteration of immune functions following the inhalation exposure to a symptomatic concn.
of sarin seems to be more pronounced.

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Development of a sensor for the hydrolysis product of the nerve agent soman utilizing molecular imprinting and silica sol-gel techniques. Parker, Jennifer L.; Horne, Starr N.; Kita, Justin M.; Peeples, Christopher J.; DiCesare, John C. Department of Chemistry and Biochemistry, University of Tulsa, Tulsa, OK, USA. Polymeric Materials Science and Engineering (2003), 88 328-329. CODEN: PMSEDG ISSN: 1550-6703. Journal; Computer Optical Disk written in English. CAN 139:48357 AN 2003:222702 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preliminary findings were presented leading to the development of a pinacolylmethylphosphonate (PMP, the hydrolysis product of the nerve agent soman) sensor, utilizing silica sol-gel techniques, mol. imprinting, and lanthanide luminescence.

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Fluorescent Detection of Chemical Warfare Agents: Functional Group Specific Ratiometric Chemosensors. Zhang, Shi-Wei; Swager, Timothy M. Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA. Journal of the American Chemical Society (2003), 125(12), 3420-3421. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 138:332984 AN 2003:159757 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Indicators providing highly sensitive and functional group specific fluorescent response to diisopropyl fluorophosphate (DFP, a nerve gas (G-agent) simulant) are reported. Nonemissive phenylpyridyl indicator reacts with DFP to give a cyclized compd. that shows a high emission due to its highly planar and rigid structure. Very weak emission was obsd. by the addn. of HCl. Another indicator based on pyridyl naphthalene exhibits a large shift in its emission spectrum after reaction with DFP, which provides for quant. ratiometric detection.

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Nerve Agents Detection Using a Cu2+/L-Cysteine Bilayer-Coated Microcantilever. Yang, Yuming; Ji, Hai-Feng; Thundat, Thomas. Department of Chemistry Institute for Micromanufacturing, Louisiana Tech University, Ruston, LA, USA. Journal of the American Chemical Society (2003), 125(5), 1124-1125. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 138:51039 AN 2003:24843 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A Cu2+/L-Cys bilayer-coated microcantilever undergoes bending upon exposure to di-Me Me phosphonate at concn. as low as 10-15 M due to the complexation of a phosphonyl group with the Cu2+/L-cysteine bilayer on the microcantilever surface.

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Neuroprotective efficacy of pharmacological pretreatment and antidotal treatment in tabun-poisoned rats. Krejcova, G.; Kassa, J. Purkyne Military Medical Academy, Hradec Kralove, Czech Rep. Toxicology (2003), 185(1-2), 129-139. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 139:2191 AN 2002:970172 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To study the influence of pharmacol. pretreatment (PANPAL) and antidotal treatment (obidoxime plus atropine) on tabun-induced neurotoxicity, male albino rats were poisoned with a LD of tabun (280 g/kg i.m.; 100% of LD50 value) and obsd. at 24 h and 7 days following tabun challenge. The neurotoxicity of tabun was evaluated using a functional observational battery (FOB) and an automatic measurement of motor activity. Pharmacol. pretreatment as well as antidotal treatment were able to eliminate most of tabun-induced neurotoxic effects obsd. at 24 h following tabun poisoning. However, there was not significant difference between the efficacy of PANPAL and antidotal treatment to eliminate tabun-induced neurotoxicity in rats. The combination of PANPAL pretreatment and antidotal treatment seems to be slightly more effective in the elimination of tabun-induced neurotoxicity in rats at 24 h following tabun challenge in comparison with the administration of PANPAL pretreatment or antidotal treatment alone. At 7 days following tabun poisoning, very few neurotoxic signs in tabun-poisoned rats were obsd. regardless of administration of pharmacol. pretreatment or antidotal treatment. Thus, our findings confirm that the combination of pharmacol. pretreatment and antidotal treatment is not only able to protect the exptl. animals from the lethal effects of tabun but also to eliminate most of tabun-induced signs of neurotoxicity in tabun-poisoned rats.

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Pyridostigmine bromide modulates topical irritant-induced cytokine release from human epidermal keratinocytes and isolated perfused porcine skin. Monteiro-Riviere, Nancy A.; Baynes, Ronald E.; Riviere, Jim E. Center for Chemical Toxicology Research and Pharmacokinetics (CCTRP), North Carolina State University, Raleigh, NC, USA. Toxicology (2003), 183(1-3), 15-28. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 138:364009 AN 2002:970031 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gulf War personnel were given pyridostigmine bromide (PB) as a prophylactic treatment against organophosphate nerve agent exposure, and were exposed to the insecticide permethrin and the insect repellent N,N-diethyl-m-toluamide (DEET). The purpose of this study was to assess the effects of PB to modulate release of inflammatory biomarkers after topical chem. exposure to chem. mixts. contg. permethrin and DEET applied in ethanol or water vehicles. Treatments were topically applied to isolated perfused porcine skin flaps (IPPSFs). Concns. of interleukin-8 (IL-8), tumor necrosis factor- (TNF-) and prostaglandin E2 (PGE2) were assayed in perfusate to probe for potential inflammatory effects after complex mixt. application. IPPSFs (n=4/treatment) were topically dosed with mixts. of permethrin, DEET, and permethrin/DEET, in EtOH. Each treatment was repeated with perfusate spiked with 50 ng/mL of PB. Perfusate was also spiked with 30 ng/mL diisopropylfluorophosphate to simulate low level organophosphate nerve agent exposure. Timed IPPSF venous effluent samples (0.5,1,2,4, and 8 h) were assayed by ELISA for IL-8 and TNF- and by EIA for PGE2. Overall, PB infusion caused a decrease or IL-8 and PGE2 release. Effects on TNF- were vehicle dependent. To probe the potential mechanism of this PB effect, human epidermal keratinocyte HEK cell cultures were exposed to permethrin DEET permethrin/DEET, with and without PB in DMSO. IL-8 was assayed at 1, 2, 4, 8, 12 and 24 h. PB suppressed IL-8 in permethrin and EtOH treatment from 4 to 24 h confirming the IPPSF results. In conclusion, these studies suggest that systemic exposure to PB suppressed IL-8 release at multiple time points in 2 skin model systems. This interaction merits further study.

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The pharmacokinetics and pharmacodynamics of two HI-6 salts in swine and efficacy in the treatment of GF and soman poisoning. Lundy Paul M; Hill Ira; Lecavalier Pierre; Hamilton Murray G; Vair Cory; Davidson Corey; Weatherby Kendal L; Berger Bradley J Chemical Biological Defence Section, Defence Research and Development Canada-Suffield, Box 4000, Medicine Hat Alberta, Alta., Canada T1A 8K6. paul.lundy@drdc-rddc.gc.ca Toxicology (2005 Mar 30), 208(3), 399-409. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15695025 AN 2005067571 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Anesthetized pigs were injected i.m. with 500 mg HI-6 dichloride (HI-6 2Cl) (1-[[[4-(aminocarbonyl)-pyridinio]methoxy]methyl]-2[(hydroxyimino)methyl]pyridinium dichloride; CAS 34433-31-3)) or the molar equivalent of HI-6 dimethanesulphonate (HI-6 DMS) 633 mg. Plasma HI-6 concentrations were measured by HPLC (1, 3, 5, 10, 15, 30, 60 min and every 30 min until 4h or 6h following the i.v. or i.m. dose respectively) while a variety of physiological responses were continuously examined. HI-6 (500 mg 2Cl or 633 mg DMS) resulted in an identical pharmacokinetic profile unaffected by atropine co-administration. Neither HI-6 salt resulted in clinically significant changes in cardiovascular or respiratory function. HI-6 DMS (1899 mg i.v.) resulted in plasma HI-6 concentrations about 10 times higher than measured following i.m. 500 mg 2Cl or 633 mg DMS and resulted in small transitory effect on mean arterial pressure. Atropine plus HI-6 DMS (1-9 mg/kg or 127-172 mg/kg i.m.) protected up to 100% of guinea pigs exposed to 5 x LD50 of GF (cyclohexyl methyl phosphonoflouridate) or soman (pinacolyl methylphosphonofluoridate) (GD) respectively. The results suggest that the two HI-6 salts have a similar pharmacokinetic profile while HI-6 DMS appears extremely safe and effective against nerve agents and may be as suitable for human use.

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Inhalation toxicity in mice exposed to sarin (GB) for 20-720 min. Bide R W; Risk D J Defence R&D Canada--Suffield, Box 4000, Medicine Hat, Alberta, Canada T1A 8K6. Richard.Bide@drdc-rddc.gc.ca Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 459-67. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558652 AN 2004610605 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Most of the historical data for the toxicity of sarin (GB) was collected for exposure times of <10 min in attempts to establish the utility of and defence against this agent in offensive military use. However, information concerning the toxicity of GB (and other nerve agents) from longer exposures of 1-12 h is critical for all personnel who must work in or close to low-level concentrations of chemical for extended periods and for all personnel, dressed in Individual Protective Equipment, who need to know when, and if, it is safe to take off these cumbersome garments.The data presented for the toxicity of GB to mice for whole-body exposures of 20 min to 12 h are intended to form part of an ongoing, multi-species effort aimed at establishing toxicity estimates for humans for these longer exposure times: LCT50 values of 430, 540, 900, 1210 and 2210 mg.min m(-3) or LC50 values of 21.5, 9.0, 5.0, 3.4 and 3.1 mg m(-3) were obtained for mice for 20-, 60-, 180-, 360- and 720-min exposures to GB, respectively. The data for longer exposures do not follow Haber's rule (LCT50=CT). The 20- and 60-min data fit the 'toxic load model' involving CnT that was established previously from historical data for 0.17-30 min GB exposures to mice. The LCT(50) and LC50 values for 3, 6 and 12 h are progressively higher (toxicity lower) than predicted by either Haber's rule or the toxic load model.

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Low levels of sarin affect the EEG in marmoset monkeys: a pilot study. van Helden Herman P M; Vanwersch Raymond A P; Kuijpers Willem C; Trap Henk C; Philippens Ingrid H C; Benschop Hendrik P Department of Medical Countermeasures. TNO Prins Maurits Laboratory, PO Box 45, 2280 AA Rijswijk, The Netherlands. helden@pml.tno.nl Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 475-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558834 AN 2004598850 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The main purpose of this pilot study was to estimate the lowest observable adverse effect level (LOAEL) for the electroencephalogram (EEG) upon long-term, low-level exposure of vehicle-pretreated and pyridostigmine-pretreated marmoset monkeys to sarin vapour. This is the C.t value (t=5 h) of exposure at which the EEG becomes significantly different from that resulting from air exposure of the same animals. The LOAELs for effects on the EEG in vehicle- and pyridostigmine-pretreated marmosets appeared to be 0.2 and 0.1 mg min m(-3), respectively. Comparatively, the latter LOAEL values are at least an order of magnitude lower than the previously established LOAEL for miosis and only 2-5 times higher than the lowest observable effect level (LOEL) of bound sarin in blood.The second aim of the study was to analyse the EEG of the same marmosets again during a 5-h exposure to air 1 year after exposure to sarin vapour. All the marmosets still demonstrated significant (P <0.05) EEG differences. In most vehicle-pretreated marmosets the energy (microV2) per EEG band was higher than that observed 1 year earlier, which might indicate that neurons had become more sensitive to excitation. This phenomenon was less pronounced in pyridostigmine-pretreated animals. Visual examination of the EEG records revealed clear bursts of alpha frequencies (ca. 9 Hz), resembling sleep-spindles, that were present more frequently in both groups of exposed marmosets than in naive animals. These late changes in spindle oscillation might be the result of changes in the cholinergic system due to exposure to sarin vapour 1 year previously. In conclusion, EEG abnormalities persisting for more than 1 year may occur in humans during long-term (5 h) exposure to subclinical levels of sarin that are not detectable by the currently fielded alarm systems.

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Protection and inflammatory markers following exposure of guinea pigs to sarin vapour: comparative efficacy of three oximes. Levy A; Chapman S; Cohen G; Raveh L; Rabinovitz I; Manistersky E; Kapon Y; Allon N; Gilat E Israel Institute for Biological Research, Department of Pharmacology, PO Box 19, Ness Ziona 74100, Israel. RonLevy@iibr.gov.il Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 501-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558827 AN 2004598847 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The purpose of the present study was to compare the antidotal efficacy and the combined effects on inflammatory markers of three oximes--toxogonine, TMB4 and 2-PAM--in combination with anticholinergic drugs following exposure to sarin vapour by inhalation.Guinea pigs restrained in plethysmographs were exposed to various doses of sarin vapour (in the range of 1.4-4.4LD50). The antidotal mixture was injected immediately (5-20 s) following exposure (3 mg kg(-1) atropine and 1 mg kg(-1) benactyzine in combination with 6 mg kg(-1) toxogonine, 2 mg kg(-1) TMB4 or 12 mg kg(-1) 2-PAM). Bronchoalveolar lavage (BAL) samples were taken from surviving animals 24 h after exposure to determine the levels of inflammatory markers. A differential cell count was performed in BAL samples on Giemsa-stained slides. The inflammatory markers--histamine and prostaglandins (PGE)--were measured in BAL using radioimmunoassay (RIA) techniques.The survival rate in the various treatment groups and analysis of BAL samples showed that: (i) Toxogonine, TMB4 and 2-PAM, without pyridostigmine pretreatment, at doses that were proportional to their doses in the respective auto-injectors, exhibited similar antidotal efficacy against sarin exposure. (ii) The results demonstrated that a centrally acting anticholinergic drug is essential in the antidotal mixture to ensure survival. (iii) Histamine release and eosinophilia following sarin inhalation might require additional intervention, aimed at reducing the symptoms of allergic reaction and possibly expediting recovery.

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Delayed haematological complications of mustard gas. Ghanei Mostafa Department of Internal Medicine, Baqiyatallah University of Medical Sciences, Chemical Injured Research Centre, Tehran, Iran. m.ghanei@bmsu.ac.ir Journal of applied toxicology : JAT (2004 Nov-Dec), 24(6), 493-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15558826 AN 2004598846 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Haematopoiesis could be affected by mustard gas. We randomly selected 318 chemical victims exposed to mustard gas and compared their cell blood counts and peripheral blood smears (PBS) with those of 377 healthy men, and also various haematological indices of 57 of these victims compared with previous data 5 years ago.The average number of red blood cells and haemoglobin of victims compared with the controls was not significantly different, but they were increased compared with data from 5 years ago. White blood cell counts, neutrophils and lymphocytes did not show any clinically meaningful difference compared with the control group but 20 cases with atypical lymphocytes in their PBS have been found.Change in lymphocyte shape may be related to committed stem cell involvement. Further studies on bone marrow cells and cell markers are needed to document this hypothesis. The mild increase in erythroid cells and haemoglobin concentration may be due to chronic obstructive pulmonary disorder and other respiratory diseases in these patients.

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Investigating the affinities and persistence of VX nerve agent in environmental matrices. Love Adam H; Vance Andrew L; Reynolds John G; Davisson M Lee Environmental Science Division, Lawrence Livermore National Laboratory, P.O. Box 808, L-396, Livermore, CA 94551, USA. love5@llnl.gov Chemosphere (2004 Dec), 57(10), 1257-64. Journal code: 0320657. ISSN:0045-6535. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15519370 AN 2004547393 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Laboratory experiments were conducted to determine environmental variables that affect the affinities and persistence of the nerve agent O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX) at dilute concentrations in environmental matrices. Quantitative analyses of VX and its degradation products were performed using LC-MS. Batch hydrolysis experiments demonstrated an increasing hydrolysis rate as pH increased, as shown in previous studies, but also indicated that dissolved aqueous constituents can cause significant differences in the absolute hydrolysis rate. Adsorption isotherms from batch aqueous experiments revealed that VX has a high affinity for hydrophobic organics, a moderate affinity for montmorillonite clay, and a very low affinity for an iron-oxyhydroxide soil mineral, goethite. The adsorption on goethite was increased with the presence of dissolved organic matter in solution. VX degraded rapidly when dried onto goethite, when specific adsorption was forced. No enhanced degradation occurred with goethite in small amounts of water. These results suggest that aqueous conditions have important controls on VX adsorption and degradation in the environment and a more mechanistic understanding of these controls is needed in order to enable accurate predictions of its long-term fate and persistence.

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Localization of substance P gene expression for evaluating protective countermeasures against sulfur mustard. Casbohm Stacy L; Rogers James V; Stonerock Mindy K; Martin Jamie L; Ricketts-Kaminsky Karen M; Babin Michael C; Casillas Robert P; Sabourin Carol L K Battelle Memorial Institute, Medical Research and Evaluation Facility, 505 King Avenue, JM-3, Columbus, OH 43201, USA Toxicology (2004 Nov 15), 204(2-3), 229-39. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE); (VALIDATION STUDIES) written in English. PubMed ID 15388249 AN 2004477792 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard [bis(2-chloroethyl)sulfide; SM] is a chemical warfare agent that produces edema and blister formation with a severe inflammatory reaction. The mouse ear vesicant model for SM injury has been used to evaluate pharmacological agents for countering SM dermal injury. The vanilloid olvanil reduces SM-induced edema and mRNA expression of cytokines and chemokines, suggesting that blocking the inflammatory effects of neuropeptides, such as substance P (SP), may provide protection against SM-induced dermal injury. This study examined SP expression in mice exposed to SM (0.16 mg) on the inner surface of the right ear, with or without olvanil pretreatment at 1, 10, 30, 60, and 360 min following exposure. In naive skin, SP mRNA localization was associated with blood vessels and sebaceous glands. In SM-exposed skin, SP mRNA was also detected in perivascular dermal cells. Immunohistochemical localization of SP protein was observed in the ear skin of naive, SM-, olvanil/SM-, and vehicle-treated mice. Quantification of SP+ perivascular dermal cells revealed that SM exposure led to a significant increase (P < or = 0.05) in SP+ cells over the observed time period. Olvanil pretreatment significantly reduced (P < or = 0.05) the mean number of SP+ cells at 60 and 360 min. This study demonstrates that SP expression could provide an additional endpoint for evaluating the effectiveness of vanilloid drugs on SM-induced skin inflammation.

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Enhanced degradation of chemical warfare agents through molecular engineering of the phosphotriesterase active site. Hill Craig M; Li Wen-Shan; Thoden James B; Holden Hazel M; Raushel Frank M Department of Chemistry, P.O. Box 30012, Texas A&M University, College Station, TX 77842-3012, USA Journal of the American Chemical Society (2003 Jul 30), 125(30), 8990-1. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15369336 AN 2004461552 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

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Photocatalytic oxidation of VX simulant 2-(butylamino)ethanethiol. Vorontsov Alexandre V; Chen Yi-Chuan; Smirniotis Panagiotis G Boreskov Institute of Catalysis, Novosibirsk 630090, Russian Federation, Russia Journal of hazardous materials (2004 Sep 10), 113(1-3), 89-95. Journal code: 9422688. ISSN:0304-3894. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15363518 AN 2004456562 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Photocatalytic oxidation of 2-(butylamino)ethanethiol (BAET) was undertaken in aqueous suspension of TiO2 Hombikat UV 100 and Degussa P25 under different initial reaction conditions in order to determine the best parameters for the fastest mineralization of the substrate. BAET is considered to be a simulant for the VX chemical warfare agent. The application of ultrasound had only a small positive effect on the BAET photocatalytic degradation. The highest mineralization rate of 0.433 mg/(l min) was found in unbuffered TiO2 Degussa P25 suspension with initial pH value of about 9.4, TiO2 concentration 500 mg/l and the initial BAET concentration 1000 mg/l. Decreasing of the initial solution pH to 6.1 or below stops the mineralization of BAET while increasing of pH to about 11 drastically changed the degradation profile. At this initial pH, the first 100 min of reaction led to only oxidation of sulfur moiety and organic intermediates accumulated in the solution. Thereafter, mineralization of the products started. The main detected volatile product was butyl aldehyde and the main polar one was 2-(butylamino) acetic acid. In the case of TiO2 Hombikat UV 100, conversion of TOC at initial pH 11 exceeded that at initial pH 9.1. For Degussa P25, the starting pH 9.4 was the best for TOC conversion. The results can be used for treatment of water from pollutants with aliphatic nitrogen and sulfur atoms.

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Retrospective detection of exposure to nerve agents: analysis of phosphofluoridates originating from fluoride-induced reactivation of phosphylated BuChE. van der Schans Marcel J; Polhuijs Martine; van Dijk Corry; Degenhardt Carla E A M; Pleijsier Kees; Langenberg Jan P; Benschop Hendrik P Department of Medical Countermeasures, TNO Prins Maurits Laboratory, P.O. Box 45, 2280 AA Rijswijk, The Netherlands. schansm@pml.tno.nl Archives of toxicology (2004 Sep), 78(9), 508-24. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15170525 AN 2004433787 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The utility was explored of a new approach to detect retrospectively exposure to nerve agents by means of conversion of the inhibitor moiety bound to the active site of the enzyme BuChE in plasma with fluoride ions into a phosphofluoridate which is subsequently analyzed by means of gas chromatography (GC). This quantifies >or=0.01% inhibition of BuChE and identifies the structure of the inhibitor except for the original leaving group. A three-tiered approach was followed involving the five classical nerve agents GA, GB, GF, GD, and VX, as well as the active metabolite of parathion, i.e., paraoxon: in vivo experiments in rhesus monkeys after iv administration of a sign-free dose of agent and concomitant in vitro experiments in plasma of rhesus monkeys and humans should allow an assessment of in vivo retrospectivity in humans. A systematic investigation was performed in order to find a single set of reaction conditions which yields a maximum amount of phosphofluoridate for all nerve agents. Fluoride-induced reactivation at 25 degrees C at a final concentration of 250 mM KF during 15 min in a pH-range between 4 and 6 appears to be effective. The in vitro decrease with time in reactivatibility of inhibited BuChE in plasma from humans and rhesus monkeys was largely due to aging of the phosphyl moiety, except for VX where spontaneous reactivation was a major cause. The decrease followed first-order except for a biphasic course in the case of GF in human and rhesus monkey plasma as well as of GD in rhesus plasma. In vitro half-lifes in human plasma ranged between ca. 14 h for GB and ca. 63 h for GA. A comparison of the in vivo data from rhesus monkeys and the in vitro data is complicated by the observation that the in vivo decrease with time of fluoride-reactivated phosphofluoridate is biphasic for all nerve agents.
The terminal in vivo phase pertains to a small fraction of the amount of initially regenerated phosphofluoridate but is responsible for a considerable degree of retrospectivity, ranging between 14 and 56 days for GF and GB, respectively. The new procedure can be used in a variety of practical applications, e.g., (i) biomonitoring in health surveillance at exposure levels that are several orders of magnitude lower than presently possible; (ii) diagnosis in case of alleged exposure to nerve agents in time of war or after terrorist attacks; (iii) in forensic cases against suspected terrorists that have handled organophosphate anticholinesterases; and (iv) in research applications such as investigations on lowest observable effect levels of exposure to nerve agents.

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Biochemical changes in mouse lung after subcutaneous injection of the sulfur mustard 2-chloroethyl 4-chlorobutyl sulfide. Elsayed Nabil M; Omaye Stanley T Department of Nutrition and Environmental Sciences and Health, Graduate Program, University of Nevada at Reno, Reno, NV, USA. nelsayed@hurleyconsulting.com Toxicology (2004 Jul 1), 199(2-3), 195-206. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15147793 AN 2004250354 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant-type chemical warfare agent (CWA) introduced in World War I which continues to be produced, stockpiled, and occasionally deployed by some countries, and could be used potentially by terrorists. Exposure to HD can cause erythema, blisters, corneal opacity, and airway damage. We have reported previously that subcutaneous (SC) injection of immunodeficient athymic nude mice with the half mustard butyl 2-chloroethyl sulfide (BCS) causes systemic biochemical changes in several organs distal to the exposure site. In the present study, we examined the response of non-immunodeficient Swiss Webster mice to the mustard, 2-chloroethyl 4-chlorobutyl sulfide (CECBS). In a pilot study, we found that a single SC injection of 20-25 microl/mouse causes death within 24h. Consequently, we used 5 microl/mouse (approx. 0.017 mg/kg body weight) of neat CECBS or an equal volume of saline as control. We examined the lungs after 1, 24, and 48 h for biochemical changes including total and oxidized glutathione, protein, DNA, and lipid peroxidation contents in tissue homogenate, and superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, and glutathione S-transferases activities in the cytosol. After 1h and/or 24h, we found statistically significant changes that were resolved by 48 h. These changes mimicked those of HD and BCS and were generally consistent with free radical-mediated oxidative stress. The implications of these observations are two-fold. First, dermal exposure to low-dose mustard gas could elicit systemic changes impacting distal organs such as the lungs. It also suggests that antioxidants could potentially modulate the response and reduce the damage. Second, although the use of known CWAs such as HD is prohibited, analogs that are not recognized as agents are as toxic and could be dangerous if acquired and used by potential terrorists.

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Reactivation and aging kinetics of human acetylcholinesterase inhibited by organophosphonylcholines. Worek F; Thiermann H; Szinicz L Institut fur Pharmakologie und Toxikologie der Bundeswehr, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2004 Apr), 78(4), 212-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14647978 AN 2004188515 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A great number of structurally different organophosphorus compounds (OPs) was synthesized in the past decades to be used as pesticides or chemical warfare agents. Methyl-fluorophosphonylcholines were found to be highly toxic OPs and the acetylcholinesterase (AChE) reactivator pralidoxime was shown to be unable to reactivate inhibited AChE. In the course of the development of more effective AChE reactivators, we have determined the reactivation rate constants of various oximes with human AChE inhibited by methylfluorophosphonylcholine (MFPCh), methylfluoro-beta-phosphonylcholine (MFP beta Ch) and methylfluorophosphonylhomocholine (MFPhCh). In addition, we investigated the potential influence of aging phenomena on the oxime efficacy. Human AChE inhibited by MFPCh, MFP beta Ch or MFPhCh was extremely resistant towards reactivation by oximes. Nevertheless, the newer compounds, HLo 7 and HI 6, were substantially more potent reactivators than obidoxime and pralidoxime. The low oxime efficacy was not due to rapid aging since no decrease in reactivatability was found over 96 h at 37 degrees C. Within this period a substantial spontaneous reactivation was observed, with MFPCh >MFP beta Ch >MFPhCh, which did not follow pseudo-first-order kinetics. In conclusion, the unexpected results, i.e., high resistance of inhibited AChE towards oxime reactivation and aging, and much lower resistance towards spontaneous reactivation, calls for further experiments at a molecular level for a better understanding of the interactions among AChE, its inhibitors and reactivators.

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Amelioration of sulfur mustard skin injury following a topical treatment with a mixture of a steroid and a NSAID. Dachir Shlomit; Fishbeine Eliezer; Meshulam Yakov; Sahar Rita; Chapman Shira; Amir Adina; Kadar Tamar Israel Institute for Biological Research, Department of Pharmacology, PO Box 19, Ness-Ziona 74100, Israel. shlomit@iibr.gov.il Journal of applied toxicology : JAT (2004 Mar-Apr), 24(2), 107-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 15052605 AN 2004157688 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The ability to ameliorate sulfur mustard (HD)-induced oedema by treatment with anti-inflammatory drugs was reported previously after screening four steroids and four non-steroidal anti-inflammatory drugs (NSAIDs) using the mouse ear vesicant model. Following the screening study, one steroid and one NSAID (Adexone and Voltaren) were selected as the most effective, and a mixture of the two was chosen for the present more extensive research. The effect of the combined treatment on clinical, biochemical and histopathological parameters following HD insult was studied. Mice ears were exposed to 0.2 micro l of HD for 10 min to produce a moderate skin injury. Oedema development peaked ca. 48 h following exposure, as determined by weighing ear biopsies. Histological observations at that time exhibited damage to the epidermis and dermis. An increase in prostaglandin E (PGE) was measured in skin homogenates, starting 8 h following exposure and lasting at least up to 48 h post-exposure. A topical treatment using the above anti-inflammatory mixture significantly reduced inflammatory parameters when applied up to 4 h following exposure. These parameters included extent of oedema, levels of PGE, area of clinical damage and extent of cytotoxic injury (vesications and damaged epithelial cells). Thus, a combination of a steroid and NSAID was found to be effective in reducing the intensity of HD skin injury and possibly shortening the time to full recovery. The treatment, however, did not prevent completely the ensuing cytotoxic processes in the epithelial layer. Copyright 2004 John Wiley & Sons, Ltd.

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Protective effect of topical iodine containing anti-inflammatory drugs against sulfur mustard-induced skin lesions. Wormser Uri; Sintov Amnon; Brodsky Berta; Casillas Robert P; Nyska Abraham Berman Building, Institute of Life Sciences, The Hebrew University, 91904 Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2004 Mar), 78(3), 156-66. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14618300 AN 2004140011 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Previous studies have shown the antidotal efficacy of topical iodine at 15 and 30 min post-exposure to sulfur mustard (SM). Here we demonstrate efficacy at longer intervals (20, 30, 45, and 60 min, respectively, for data) using an improved topical povidone-iodine preparation termed N66, which contains steroidal and non-steroidal anti-inflammatory agents. In the mouse, N66 reduced severity of ear edema by 43, 47, 44, and 36%; ear epidermal ulceration by 74, 58, 45, and 58%; and epidermal necrosis by 54, 34, 26, and 31% at the respective time points. A similar effect was observed with encrustation. The healing marker, grade of acanthotic area, showed dramatic increases of 39.6-, 25.3-, 20.9-, and 22-fold. Severity of the dermal parameters, acute inflammation and dermal necrosis, was reduced by 63, 34, 34, and 38% and 80, 54, 54, and 59%, respectively. In guinea pig skin, topical treatment with N66 45 min post-exposure reduced the SM-induced ulceration area by 75%. The histological parameters subepidermal microblister formation, epidermal ulceration, epidermal necrosis, and encrustation were reduced by 63, 61, 41, and 41%, respectively. The healing marker, grade of acanthotic area, was elevated by 73%. N66 induced a statistically significant reduction in two dermal markers for tissue damage: acute inflammation (33%) and dermal necrosis (48%). Reduced skin damage was also observed in areas adjacent the treated sites. The pharmacologically active components of N66 showed additive effect. These findings suggest that the povidone-iodine preparation combined with anti-inflammatory agents functions as a potent antidote against skin lesions induced by SM at relatively long intervals between exposure and treatment.

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Low-level exposure of guinea pigs and marmosets to sarin vapour in air: lowest-observable-adverse-effect level (LOAEL) for miosis. van Helden Herman P M; Trap Henk C; Kuijpers Willem C; Oostdijk John P; Benschop Hendrik P; Langenberg Jan P Department of Medical Countermeasures, TNO Prins Maurits Laboratory, PO Box 45, 2280 AA Rijswijk, The Netherlands. helden@pml.tno.nl Journal of applied toxicology : JAT (2004 Jan-Feb), 24(1), 59-68. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14745848 AN 2004044499 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The purpose of this pilot study was to indicate, for low-level exposure of conscious guinea pigs and marmoset monkeys to sarin vapour in air, the lowest-observable-adverse-effect level (LOAEL) of sarin for miosis. This is the concentration x time (C.t) value (t = 5 h) of exposure at which miosis becomes significant. The ratio of pupil and iris diameters, measured on digital photographs taken on-line during exposure, was calculated as a measure for miosis. The exposure concentrations were in the range 7-150 microg x m(-3) and the exposure times needed to achieve significant miosis were in the range 10-300 min. Both vehicle- and pyridostigmine-pretreated animals were used in the experiments. The latter pretreatment resulted in ca. 30% inhibition of erythrocyte acetylcholinesterase in both species. In vehicle-pretreated guinea pigs and marmosets the pupil size was decreased significantly (P < 0.05) at sarin doses of 1.8 +/- 0.3 and 2.5 +/- 0.8 mg x min x m(-3), respectively. In pyridostigmine-pretreated guinea pigs and marmosets the pupil size was affected significantly (P < 0.05) at 1.8 +/- 0.5 and 3.0 +/- 0.8 mg x min x m(-3), respectively. Evidently there is no significant influence of pyridostigmine pretreatment on the LOAEL. These data were addressed in light of the recommended occupational and detection limits for sarin vapour in air. It was concluded that miosis will occur during low-level sarin exposure at levels that are not detectable by the currently fielded alarm systems, assuming that humans are as sensitive for sarin vapour in air as guinea pigs and marmosets. Copyright 2004 John Wiley & Sons, Ltd.

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Examination of changes in connective tissue macromolecular components of large white pig skin following application of Lewisite vapour. Lindsay Christopher D; Hambrook Joy L; Brown Roger F R; Platt Jan C; Knight Robert; Rice Paul Biomedical Sciences Department, Dstl Porton Down, Salisbury, Wilts SP4 0JQ, UK. clindsay@dstl.gov.uk Journal of applied toxicology : JAT (2004 Jan-Feb), 24(1), 37-46. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14745845 AN 2004044496 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to provide information about the degradative processes that occur in major connective tissue components in skin following exposure of large white pigs to Lewisite vapour. Of particular interest were alterations in glycoproteins, which are known to mediate dermo-epidermal attachment (laminin and type IV collagen) and the main collagen found in the dermis (type III collagen). The immunostaining of transfer blots from skin extracts run on sodium dodecyl sulphate polyacrylamide gel electrophoresis gels revealed no evidence of cross-linking of laminin or of type III or IV collagen. However, there was evidence of a very considerable degradation of laminin and, to a lesser extent, of type IV collagen. Type III collagen did not appear to be degraded in skin exposed to Lewisite. These degradative processes appeared to be more severe than found in previous studies in Yucatan mini-pigs percutaneously exposed to sulphur mustard, in which only laminin was found to undergo partial cleavage rather than wholesale degradation.The results suggest that damage to macromolecular components in the sub-epidermal basement membrane in skin which mediate dermo-epidermal separation processes may be a common feature in the mechanism of action of vesicating agents such as Lewisite and sulphur mustard. It is of interest that the damage to laminin in this study appeared to be more severe than that previously found for sulphur mustard. This suggests that skin can suffer substantial damage yet, in the case of Lewisite exposure, recover relatively quickly. However, Lewisite is not an alkylating agent. Sulphur mustard, in contrast, generates characteristically slow healing lesions, most probably because of its ability to alkylate cell types that normally would be involved in skin regenerative processes. Published by John Wiley & Sons, Ltd.

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Cardiovascular effects of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) decisive for its therapeutic efficacy in sarin poisoning. Joosen Marloes J A; Bueters Tjerk J H; van Helden Herman P M Research Group Medical Countermeasures, TNO Prins Maurits Laboratory, Lange Kleiweg 137, PO Box 45, 2280 AA Rijswijk, The Netherlands. joosen@pml.tno.nl Archives of toxicology (2004 Jan), 78(1), 34-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14508639 AN 2004043790 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Mortality and occurrence of cholinergic symptoms upon sarin intoxication (144 micro g/kg s.c., approximately 2 x LD50) in rats is completely prevented by treatment with the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA, 2 mg/kg i.m.). Previously, we have shown that CPA treatment altered the distribution of sarin into the brain, presumably through its cardiovascular side effects. Therefore, the objective of the present study was to evaluate the contribution of the cardiodepressant effects of CPA to its therapeutic efficacy against sarin intoxication. Intramuscular treatment of rats with 0.5 and 2.0 mg/kg CPA 1 min after sarin poisoning attenuated most cholinergic symptoms and prevented mortality, which seemed to be directly associated with an immediate strong and long-lasting bradycardia and hypotension caused by CPA. Treatment with lower doses of CPA (0.1 and 0.05 mg/kg i.m.) caused similar levels of bradycardia and hypotension, albeit a few minutes later than at the higher doses of CPA. Upon sarin intoxication, this was correlated with increased incidence of cholinergic symptoms and decreased survival rates. Pretreatment with the peripheral adenosine A1 receptor antagonist 8- p-sulphophenyltheophylline (8-PST, 20 mg/kg i.p.) counteracted the cardiodepressant effects of 0.05 mg/kg CPA almost completely, thereby nearly abolishing its therapeutic efficacy against sarin poisoning. In conclusion, the present results strongly indicate that bradycardia and hypotension induced by the peripheral adenosine A1 receptor play a prominent role in the therapeutic efficacy of CPA in cases of sarin poisoning.

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Effects of daily stress or repeated paraoxon exposures on subacute pyridostigmine toxicity in rats. Shaikh Jamaluddin; Karanth Subramanya; Chakraborty Dibyendu; Pruett Steve; Pope Carey N Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, 264 McElroy Hall, OK 74078, Stillwater, USA Archives of toxicology (2003 Oct), 77(10), 576-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 14574445 AN 2003495653 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Pyridostigmine (PYR) is a carbamate cholinesterase (ChE) inhibitor used during the Persian Gulf War as a pretreatment against possible chemical nerve agent attack. Because of its quaternary structure, PYR entry into the central nervous system is limited by the blood-brain barrier (BBB). Following reports of unexplained illnesses among Gulf War veterans, however, central nervous system effects of PYR have been postulated through either stress-induced alteration of BBB permeability or via interactions with other neurotoxic agents. We evaluated the effects of daily physical (treadmill running) stress or daily exposure to a subclinical dosage of the organophosphate ChE inhibitor paraoxon (PO) on ChE inhibition in blood, diaphragm and selected brain regions in young adult male Sprague-Dawley rats following subacute PYR exposures. In physical stress studies, rats were placed on a treadmill for 90 min each day for 14 days just prior to PYR (0, 3, or 10 mg/kg per day) administration. In PO-PYR interaction studies, rats were treated with PO (0, 0.05, or 0.1 mg/kg per day) 1 h prior to daily PYR (0 or 3 mg/kg per day) administration for 14 consecutive days. Rats were evaluated daily for signs of cholinergic toxicity and were killed 1 h after the final PYR treatment. Forced running increased plasma corticosterone levels throughout the experiment (on days 1, 3, 7 and 14) when measured immediately after termination of stress. PYR-treated rats in the high dosage (10 mg/kg per day) group exhibited slight signs of toxicity (involuntary movements) for the first 6 days, after which tolerance developed. Interestingly, signs of cholinergic toxicity following PYR were slightly but significantly increased in rats forced to run on the treadmill prior to dosing. ChE activities in whole blood and diaphragm were significantly reduced 1 h after the final PYR challenge, and ChE inhibition in diaphragm was significantly greater in stressed rats than in non-stressed controls following high dose PYR (10 mg/kg per day).
No significant effects of treadmill running on PYR-induced ChE inhibition in brain regions were noted, however. Repeated subclinical PO exposure had no apparent effect on functional signs of PYR toxicity. As with repeated treadmill running, whole blood and diaphragm ChE activities were significantly reduced 1 h after the final PYR administration, and ChE inhibition was significantly greater with combined PO and PYR exposures. Brain regional ChE activity was significantly inhibited after daily PO exposure, but no increased inhibition was noted following combined PO and PYR dosing. We conclude that, while some stressors may under some conditions affect functional signs of toxicity following repeated pyridostigmine exposures, these changes are likely to occur via alteration of peripheral cholinergic mechanisms and not through enhanced entry of pyridostigmine into the brain.

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Effects of sulfur mustard on transcription in human epidermal keratinocytes: analysis by mRNA differential display. Platteborze Peter L Pharmacology Division, USAMRICD, Aberdeen Proving Ground, MD 21010-5425, USA. Peter.Platteborze@det.amedd.army.mil Journal of applied toxicology : JAT (2003 Jul-Aug), 23(4), 249-54. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12884408 AN 2003350997 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This study examines the transcriptional response of human epidermal keratinocytes (HEK) to sulfur mustard (HD) in order to gain a better understanding of the intracellular events that result in cytotoxicity. Differential display polymerase chain reaction technology was used to examine the relative transcriptional activity of healthy cells to those exposed to subvesicating or vesicating concentrations of HD for 4 h. Approximately 2% of the HEK transcriptome had altered expression. Sixty of the most prominently altered transcripts were characterized. Important upregulated genes include NADH dehydrogenase III, GADD45 and ubiquitin. Key downregulated genes include type I keratin 14, alpha-enolase and caltractin. Many of the identified transcripts protein products presently do not have an assigned function and eleven transcripts were unidentifiable. These transcriptional alterations provide one of the first molecular insights into the intracellular events induced by HD. Published in 2003 by John Wiley & Sons, Ltd.

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Degradation of VX and sulfur mustard by enzymatic haloperoxidation. Amitai G; Adani R; Hershkovitz M; Bel P; Rabinovitz I; Meshulam H Division of Medicinal Chemistry, Israel Institute for Biological Research, PO Box 19, Ness Ziona 74100, Israel. amitai@ibr.gov.il Journal of applied toxicology : JAT (2003 Jul-Aug), 23(4), 225-33. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12884405 AN 2003350994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chloroperoxidase (CPO) isolated from Caldariomyces fumago (20 U ml(-1)) together with urea hydrogenperoxide (UPER, 0.5 mM) and sodium chloride as co-substrate (NaCl, 0.5 M) caused rapid breakdown of VX (10 microM) (t((1/2)) = 8 s, 25 C, 50 mM tartarate, pH 2.75). Glucose oxidase (GOX, Aspergillus niger) and glucose were used as an alternative source for H(2)O(2). A mixture of GOX (20 U ml(-1)), glucose (GLU 0.45 M), CPO (20 U ml(-1)) and NaCl (0.5 M) caused a 3.8-fold slower degradation of VX (10 microM) (t((1/2)) = 30 s, 25 C, 50 mM tartarate, pH 2.75). The concentrations of H(2)O(2) and chlorine produced by this enzyme/substrate mixture depended mainly on the GLU concentration. Horseradish peroxidase (HRP) together with UPER (1 mM) and sodium iodide (NaI, 0.05 M) caused progressive degradation of VX that was more than 400-fold slower than with CPO (20 U ml(-1)), UPER (0.5 mM) and NaCl (0.5 M) (t((1/2)) = 55 min, 25 C, pH 8). Skin decontamination of VX by CPO was tested in pig-ear skin in vitro. The chemical agent VX (0.01 M, 100 microl) was degraded by 98% within 3 h of skin diffusion when a mixture of UPER/NaCl/CPO was applied 60 min prior to VX application. A mixture of UPER/NaCl without CPO also caused significant VX degradation (94%) during skin diffusion whereas it did not cause any VX degradation in solution. Degradation of VX in skin, obtained without exogenous CPO, may indicate involvement of endogenous intradermal haloperoxidase-like enzyme. Reagent UPER (1 mM) did not cause any degradation of VX in solution or during its skin diffusion. Furthermore, a mixture of CPO, UPER and NaCl caused rapid degradation of sulfur mustard (HD). Sulfur mustard (50 microM) incubated in the presence of CPO (4 U ml(-1)), UPER (0.05 M) and NaCl (0.5 M) at pH 2.75 and 30 C was oxidized by 97% and 99% within 5 and 10 min, respectively. The oxidation products HD sulfoxide, HD sulfone and HD sulfoxidevinyl were identified by GC/MS in the enzymatic chloroperoxidation mixture. Copyright 2003 John Wiley & Sons, Ltd.

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Billion-fold acceleration of the methanolysis of paraoxon promoted by La(OTf)3 in methanol. Tsang Josephine S; Neverov Alexei A; Brown R S Department of Chemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6 Journal of the American Chemical Society (2003 Jun 25), 125(25), 7602-7. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12812502 AN 2003285652 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The methanolysis of the insecticide paraoxon (2) was investigated in methanol solution containing varying [La(OTf)(3)] (OTf = (-)OS(O)(2)CF(3)) as a function of at 25 degrees C. Plots of the pseudo-first-order rate constants (k(obs)) for methanolysis as a function of [La(OTf)(3)](total) were obtained under buffered conditions from 5.15 to 10.97, and the slopes of the linear parts of these were used to determine the second-order rate constants (k(2)(obs)) for the La(3+)-catalyzed methanolysis of 2. Detailed analysis of the potentiometric titration data of La(OTf)(3) in methanol through fits to a multicomponent equilibrium mixture of dimers of general stoichiometry La(3+)(2)((-)OCH3)n, where n assumes values of 1-5, gives the equilibrium distribution of each as a function of. These data, when fit to a second expression describing k(2)(obs) in terms of a linear combination of individual rate constants k(2)(2:1), k(2)(2:2).k(2)(2:)n for the dimers, allow one to describe the overall catalytic profile in terms of the individual contributions. The most catalytically important species are the three dimers La(3+)(2)((-)OCH3)1, La(3+)(2)((-)OCH3)2, and La(3+)(2)((-)OCH3)3. The catalysis of the methanolysis of 2 is spectacular: a 2 x 10(-3) M solution of [La(3+)](total), at neutral, affords a 10(9)-fold acceleration relative to the base reaction (t(1/2) approximately 20 s at 8.2) with excellent turnover. A mechanism of the catalyzed reaction involving the La(3+)(2)((-)OCH3)2 species is proposed.

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Putative role of proteolysis and inflammatory response in the toxicity of nerve and blister chemical warfare agents: implications for multi-threat medical countermeasures. Cowan F M; Broomfield C A; Lenz D E; Smith W J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. fred.cowan@amedd.army.mil Journal of applied toxicology : JAT (2003 May-Jun), 23(3), 177-86. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 12794939 AN 2003268101 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Despite the contrasts in chemistry and toxicity, for blister and nerve chemical warfare agents there may be some analogous proteolytic and inflammatory mediators and pathological pathways that can be pharmacological targets for a single-drug multi-threat medical countermeasure. The dermal-epidermal separation caused by proteases and bullous diseases compared with that observed following exposure to the blister agent sulfur mustard (2,2'-dichlorodiethyl sulfide) has fostered the hypothesis that sulfur mustard vesication involves proteolysis and inflammation. In conjunction with the paramount toxicological event of cholinergic crisis that causes acute toxicity and precipitates neuronal degeneration, both anaphylactoid reactions and pathological proteolytic activity have been reported in nerve-agent-intoxicated animals. Two classes of drugs already have demonstrated multi-threat activity for both nerve and blister agents. Serine protease inhibitors can prolong the survival of animals intoxicated with the nerve agent soman and can also protect against vesication caused by the blister agent sulfur mustard. Poly (ADP-ribose) polymerase (PARP) inhibitors can reduce both soman-induced neuronal degeneration and sulfur-mustard-induced epidermal necrosis. Protease and PARP inhibitors, like many of the other countermeasures for blister and nerve agents, have potent primary or secondary anti-inflammatory pharmacology. Accordingly, we hypothesize that drugs with anti-inflammatory actions against either nerve or blister agent might also display multi-threat efficacy for the inflammatory pathogenesis of both classes of chemical warfare agent.

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Comparative efficacy of diazepam and avizafone against sarin-induced neuropathology and respiratory failure in guinea pigs: influence of atropine dose. Taysse L; Calvet J-H; Buee J; Christin D; Delamanche S; Breton P Centre d'Etudes du Bouchet, Defense Research Centre, BP No. 3, Vert-Le-Petit 91710, France. laurent.taysse@ceb.etca.fr Toxicology (2003 Jun 30), 188(2-3), 197-209. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12767691 AN 2003245521 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This investigation compared the efficacy of diazepam and the water-soluble prodiazepam-avizafone-in sarin poisoning therapy. Guinea pigs, pretreated with pyridostigmine 0.1 mg/kg, were intoxicated with 4LD(50) of sarin (s.c. route) and 1 min after intoxication treated by intramuscular injection of atropine (3 or 33.8 mg/kg), pralidoxime (32 mg/kg) and either diazepam (2 mg/kg) or avizafone (3.5 mg/kg). EEG and pneumo-physiological parameters were simultaneously recorded. When atropine was administered at a dose of 3 mg/kg, seizures were observed in 87.5% of the cases; if an anticonvulsant was added (diazepam (2 mg/kg) or avizafone (3.5 mg/kg)), seizure was prevented but respiratory disorders were observed. At 33.8 mg/kg, atropine markedly increased the seizure threshold and prevented early respiratory distress induced by sarin. When diazepam was administered together with atropine, seizures were not observed but 62.5% of the animals displayed respiratory difficulties. These symptoms were not observed when using avizafone. The pharmacokinetic data showed marked variation of the plasma levels of atropine and diazepam in different antidote combination groups, where groups receiving diazepam exhibited the lowest concentration of atropine in plasma. Taken together, the results indicate that avizafone is suitable in therapy against sarin when an anticonvulsant is judged necessary.

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Low-level sarin-induced alteration of immune system reaction in inbred BALB/c mice. Kassa Jiri; Krocova Z; Sevelova L; Sheshko V; Kasalova I; Neubauerova V Department of Toxicology, Purkyne Military Medical Academy, P.O. Box 35/T, 500 01 Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2003 May 3), 187(2-3), 195-203. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12699908 AN 2003232384 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

To study the influence of low-level sarin inhalation exposure on immune functions, inbred BALB/c mice were exposed to low concentrations of sarin for 60 min in the inhalation chamber. Two concentrations of sarin were chosen-asymptomatic concentration (LEVEL 1) and non-convulsive symptomatic concentration (LEVEL 2). The evaluation of immune functions was carried out using phenotyping of CD3 (T-lymphocytes), CD4 (helper T-lymphocytes), CD8 (cytotoxic T-lymphocytes) and CD19 cells (B-lymphocytes) in the lungs, blood and spleen, lymphoproliferation of spleen cells stimulated in vitro by various mitogens (concanavalin A, lipopolysaccharides), phagocyte activity of peritoneal and alveolar macrophages, production of N-oxides by peritoneal macrophages and the measurement of the natural killer cell activity at 1 week following sarin exposure. The results were compared to the values obtained from control mice exposed to pure air instead of sarin. The results indicate that not only symptomatic but also asymptomatic dose of sarin is able to alter the reaction of immune system at 1 week following exposure to sarin. While the number of CD3 cells in the lungs was slightly decreased, an increase in CD19 cells was observed especially in the lungs and blood. The reduced proportion of T-lymphocytes is caused by decay of CD4 positive T-cells. Lymphoproliferation was significantly decreased regardless of the mitogen and sarin concentration used. The production of N-oxides by peritoneal macrophages was stimulated after exposure to LEVEL 2 of sarin whereas their ability to phagocyte the microbes was increased after exposure to LEVEL 1. The natural killer cell activity was significantly higher in the case of inhalation exposure of mice to LEVEL 2 of sarin. Thus, not only organophosphorus insecticides but also nerve agents such as sarin are able to alter immune functions even at a dose that does not cause clinically manifested intoxication following the inhalation exposure.
Nevertheless, the alteration of immune functions following the inhalation exposure to a symptomatic concentration of sarin seems to be more pronounced.

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Nerve agents detection using a Cu2+/L-cysteine bilayer-coated microcantilever. Yang Yuming; Ji Hai-Feng; Thundat Thomas Department of Chemistry, Institute for Micromanufacturing, Louisiana Tech University, Ruston, Louisiana 71272, USA Journal of the American Chemical Society (2003 Feb 5), 125(5), 1124-5. Journal code: 7503056. ISSN:0002-7863. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12553787 AN 2003045046 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

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Assessment of the effectiveness of downward water sprays for mitigating gaseous chlorine releases in partially confined spaces. Dimbour J P; Gilbert D; Dandrieux A; Dusserre G Ecole Nationale Superieure des Techniques Industrielles et des Mines d'Ales Laboratoire Genie de l'Environnement Industriel 6, Avenue de Clavieres, 30319 Cedex, Ales, France. jean-philippe.dimbour@ema.fr Journal of hazardous materials (2003 Jan 31), 96(2-3), 127-41. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12493204 AN 2002730858 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Water sprays are sometimes used as a means of mitigating accidental releases of chlorine gas. This paper gives results of a series of small-scale experimental field tests on the mitigation of chlorine gaseous releases (about 1kg/min) by various downward water sprays. The releases were from a cylinder of liquefied chlorine located in a storage shed. The shed could be configured to simulate confined and semi-confined installations used at public swimming pools. The water sprays were located in the shed. During these tests, different types of spray nozzles and storage configurations were tested under various atmospheric conditions, in order to select the best water spray. It was shown that the best chlorine downstream concentration reduction (factor 3-5 at 10m) was achieved with a flat fan water spray for the semi-confined configuration. Poor absorption in water was observed (<1%). The highest absorption (roughly 5%) was obtained with a fog water spray for the confined configuration. This is expected since chlorine is a low soluble gas. It has been evidenced for the confined configuration, that even if reduction of concentration has been observed (factor 2), downstream concentration remains very high (>10,000ppm), and above critical level of toxicity. Consequently, the use of water sprays in this case without additives to promote absorption seems to be inefficient.

[megalomania]

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Development of multifunctional perfluorinated polymer blends as an active barrier cream against chemical warfare agents. Hobson, Stephen T.; Braue, Ernest H., Jr. Drug Assessment Div., U.S. Army Medical Research Institute for Chemical Defense, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 80-81. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:363990 AN 2003:381106 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare agents (CWA's) represent a real and growing threat both to U.S. armed forces as well as to civilians. Within the last three decades, chem. weapons have been used by the Soviets in Cambodia (yellow rain, tricothecene mycotoxins), by Iraq against Iran (HD and tabun), and by Iraq against its own dissident Kurdish population at Halabja (H-ID HCN0). In the United States' experience in World War I, almost one-third of hospitalized casualties were a result of CWA's. Furthermore, the 1000 casualties and 12 deaths resulting from the 1995 terrorist use of sarin (GB) in Tokyo show that civilians have also become targets. In this paper we focus on protection against two classes of CWA's: nerve agents (soman, GD) and blister agents (sulfur mustard, HD). Protection against these agents in the United States Army consists of a chem. resistant outer layer of clothing (BDO) and protective mask (M40). This scheme of protection allows operation in a chem. contaminated area but results in decreased performance and increased heat retention. We have investigated a material that serves as a phys. barrier to CWA's and contains an active moiety to neutralize hazardous chems. This Active Topical Skin Protectant (aTSP) would be used in conjunction with other protective procedures. Herein we report the prepn., characterization, and evaluation of aTSP's.

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Molecularly imprinted polymers for the detection of chemical agents in water. Jenkins, Amanda L.; Yin, Ray; Jensen, Janet L.; Durst, H. Dupont. US Army Research Laboratory, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 76-77. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:343335 AN 2003:381101 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molecularly imprinted polymers contg. Eu3+ were prepd. using a no. of pesticides and pinacolyl methylphosphonate (hydrolysis product of the nerve agent Soman), and sensors were fabricated by coating the polymers on optical fibers. The sensors were characterized in terms of sensitivity, selectivity, response time, adaptability, and portability; they provided detection limits in the low parts per trillion.

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Synthesis of carbon-coated MgO nanoparticles. Bedilo, Alexander F.; Sigel, M. Jake; Koper, Olga B.; Melgunov, Maxim S.; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2002), 12(12), 3599-3604. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 138:174329 AN 2002:910661 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Carbon-coated MgO nanoparticles, with carbon forming a porous coating on the surface of MgO nanoparticles, have been prepd. by two different techniques. Resorcinol has been found to be an efficient agent for the modification of magnesium methoxide leading to carbon-coated MgO nanocrystals of small crystallite size and high surface area. Decompn. of dry magnesium methoxide under an inert gas flow proved to be another efficient and economical way to synthesize carbon-coated MgO. The carbon coating acts as a hydrophobic barrier partially protecting the core metal oxide from water adsorption and conversion to magnesium hydroxide. However, destructive adsorption reactions can still proceed on the metal oxide surface, as evidenced by the dehydrochlorination of 2-chloroethyl Et sulfide (2-CEES) and 1-chlorobutane. The overall stability of the material in the presence of water vapor is significantly improved in comparison with non-coated nanocryst. MgO.

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Micellar Effects on Hypochlorite Catalyzed Decontamination of Toxic Phosphorus Esters. Dubey, D. K.; Gupta, A. K.; Sharma, Mamta; Prabha, S.; Vaidyanathaswamy, R. Defence R and D Establishment, Gwalior, India. Langmuir (2002), 18(26), 10489-10492. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 138:94789 AN 2002:866089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At pH 8.5, the surfactant N,N,N-trimethyl-1-hexadecanaminium bromide (I) increased the pseudo-first-order rate consts. of hypochlorite-catalyzed hydrolysis of the sarin model compd. p-nitrophenyl di-Ph phosphate by 300 times and that of the toxic p-nitrophenyl iso-Pr methylphosphonate by 20 times, and the nerve agent sarin itself was completely decontaminated within 10 min at a sarin-hypochlorite ratio of 20:1 in a micellar I-hypochlorite mixt. In the absence of surfactant , it takes >70 min to detoxify sarin, even at a 10 times higher concn. of hypochlorite.

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A Comparative Study of the Adsorption of Chloro- and Non-Chloro-Containing Organophosphorus Compounds on WO3. Kanan, Sofian M.; Lu, Zhixiang; Tripp, Carl P. Laboratory for Surface Science Technology and Department of Chemistry, University of Maine, Orono, ME, USA. Journal of Physical Chemistry B (2002), 106(37), 9576-9580. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 137:253624 AN 2002:620746 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The adsorption of di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), and methyldichlorophosphate (MDCP) on monoclinic tungsten oxide (m-WO3) evacuated at various temps. was investigated using IR spectroscopy. DMMP is the most common mol. used for evaluating the performance of WO3 and other semiconducting metal oxide (SMO)-based sensors to phosphonate-based nerve agents. However, toxic nerve agents such as sarin differ from DMMP in that they contain a functional group (P-F in sarin) that can be readily hydrolyzed. It is shown that the adsorption of organophosphates that contain P-Cl groups differs from nonhalogenated simulants such as DMMP and TMP on WO3 surfaces. Specifically, the non-chlorinated simulants DMMP and TMP adsorb on the surface solely through the P:O functionality with the surface water layer as well as the Lewis and Bronsted acid sites. The relative no. of mols. bound on Lewis and Bronsted acid surface sites depends on the initial evacuation temp. of the WO3 surface. When MDCP adsorbs on WO3 through the P:O bond, it is accompanied by the hydrolysis of P-Cl groups by water vapor or the adsorbed water layer leading to addnl. phosphate-like species on the surface. The IR data suggests that a halogenated phosphate like MDCP is a better simulant mol. for studies aimed at understanding the role of water and hydrolysis in the response of metal oxide-based sensors to nerve agents.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock, Shannon D.; Till, Gerd O.; Smith, Milton G.; Ward, Peter A. Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2002), 22(4), 257-262. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 137:151235 AN 2002:596130 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. warfare agent analog, 2-chloroethyl Et sulfide, known as half-mustard gas (HMG), is less toxic and less of an environmental hazard than the full mol. and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of 125I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, the authors obsd. significant attenuation of the pulmonary injury when exptl. animals were complement- or neutrophil-depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, DMSO, dimethylthiourea, Resveratrol, and N-acetyl-L-cysteine (NAC). The last compd. showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement-mediated pathways and the generation by neutrophils of toxic oxygen species. The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber, Ellen; McGuire, Raymond. Lawrence Livermore National Laboratory, Environment Protection Department, University of California, Livermore, CA, USA. Journal of Hazardous Materials (2002), 93(3), 339-352. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 137:374412 AN 2002:558690 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A decontamination method was developed using a single reagent that is effective both against chem. warfare (CW) and biol. warfare (BW) agents. The new reagent, L-Gel, consists of an aq. soln. of a mild com. oxidizer, Oxone, together with a com. fumed silica gelling agent, Cab-O-Sil EH 5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. This reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Expts. to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Lab. and independently at 4 other locations. L-Gel was tested against all classes of chem. warfare agents and against various biol. warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biol. agents. Testing showed that L-Gel is as effective against chem. agents and biol. materials, including spores, as the best military decontaminants.

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Synthesis, Characterization, and Adsorption Studies of Nanocrystalline Aluminum Oxide and a Bimetallic Nanocrystalline Aluminum Oxide/Magnesium Oxide. Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J.; Bonevich, John. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry of Materials (2002), 14(7), 2922-2929. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 137:128541 AN 2002:469813 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of Al2O3 and Al2O3/MgO have been produced by a modified aerogel synthesis involving the corresponding aluminum tri-tert-butoxide, magnesium methoxide, toluene, methanol, ethanol, and water. The resulting oxides are in the form of powders having crystallites of .ltorsim.2 nm. These crystallites have been studied by TEM and BET methods, and were found to possess high surface areas and pore vols. (800 m2/g for Al2O3 and 790 m2/g for Al2O3/MgO, compared to 450 m2/g for MgO). As seen with other metal oxides, once they are produced as nanoparticles, their reactivity is greatly enhanced on a per unit surface area basis. This is thought to be due to morphol. differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites possess much higher surface concn. of such sites per unit surface area. Elemental anal., X-ray diffraction, and IR spectroscopy have been used to characterize these nanoparticles, and reactions with CCl4, SO2, and Paraoxon have demonstrated significantly enhanced reactivity and/or capacity compared with common com. forms of the oxide powders. A significant feature is that, by a cogellation synthesis, Al2O3 and MgO have been intermingled, which engenders enhanced reactivity/capacity over the pure forms of nanoscale Al2O3 or MgO toward a chem. warfare surrogate (Paraoxon) and an acid gas (SO2). This serves as an example where tailored synthesis of a nanostructured formulation can yield special benefits.

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Nanocrystalline metal oxides as destructive adsorbents for organophosphorus compounds at ambient temperatures. Rajagopalan, Shyamala; Koper, Olga; Decker, Shawn; Klabunde, Kenneth J. Nanoscale Materials, Inc., Manhattan, KS, USA. Chemistry--A European Journal (2002), 8(11), 2602-2607. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 137:191092 AN 2002:451335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of magnesium oxide react with organophosphorus compds. at room temp. by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant mol. fragments. These ultrafine powders have unusual cryst. shapes and possess high surface concns. of reactive edge/corner and defect sites, and thereby display higher surface reactivity, normalized for surface area, than typical polycryst. material. This high surface reactivity coupled with high surface area allows their use for effective decontamination of chem. warfare agents and related toxic substances. Herein data is presented for paraoxon, diisopropylfluorophosphate (DFP), and (CH3CH2O)2P(O)CH2SC6H5 (DEPTMP). Solid-state NMR and IR spectroscopy indicate that all OR and F groups dissoc.; this leaves bound -PO4, -F, and -OR groups for paraoxon, DFP, and DEPTMP, resp. For paraoxon, it was shown that one monolayer reacts. For DEPTMP, the OR groups dissoc., but not the P-CH2SC6H5 group. The nanocryst. MgO reacts much faster and in higher capacity than typical activated carbon samples, which physisorb but do not destructively adsorb these phosphorous compds.

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Routes of photocatalytic destruction of chemical warfare agent simulants. Vorontsov, Alexandre V.; Davydov, Lev; Reddy, Ettireddy P.; Lion, Claude; Savinov, Eugenii N.; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russia. New Journal of Chemistry (2002), 26(6), 732-744. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 137:236738 AN 2002:427511 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Selected imitants of chem. warfare agents such as di-Me methylphosphonate (DMMP), di-Et phosphoramidate (DEPA), pinacolyl methylphosphonate (PMP), and butylaminoethanethiol (BAET) were subjected to photocatalytic and sonophotocatalytic treatment in aq. suspensions of TiO2. Complete conversion of the same mass of imitants to inorg. products was obtained within 600 min for DMMP, DEPA, PMP, but required a longer time for BAET. Sonolysis accelerated photodegrdn. of DMMP. No degrdn. was obsd. without UV illumination. Final products of degrdn. were PO43-, CO2 for DMMP and PMP, PO43-, NO3- (25%), NH4+ (75%), CO2 for DEPA, and SO42-, NH4+, CO2 for BAET. The no. of main detected intermediate products increases in the order DMMP (7), DEPA (9), PMP (21), and exceeds 34 for BAET. Degrdn. of DMMP mainly proceeds through consecutive oxidn. of methoxy groups and then the Me group. Di-Me hydroxymethylphosphonate and dimethylphosphate testify to the parallel oxidn. of the Me group. Destruction of DEPA mainly starts with cleavage of the P-NH2 bond to form di-Et phosphate, which transforms further into Et phosphate. Oxidn. of  and  carbons of ethoxy groups to form ethylphosphonoamidate, hydroxyethyl ethylphosphonoamidate and other products also contributes to the destruction. Photocatalytic degrdn. of PMP mainly starts with oxidn. of the pinacolyl fragment, methylphosphonic acid and acetone being the major products. Oxidn. of BAET begins with dark dimerization to disulfide, which undergoes oxidn. of sulfur forming sulfinic and sulfonic acids as well as oxidn. of carbons to form butanal, aminobutane, etc., and cyclic products such as 2-propylthiazole. A scheme of degrdn. was proposed for DMMP and DEPA, and starting routes for PMP and BAET. Quantum efficiencies of complete mineralization calcd. as reaction rate to photon flux ratio approx. 10-3%.

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Solvent Effects on the Heterogeneous Adsorption and Reactions of (2-Chloroethyl) ethyl Sulfide on Nanocrystalline Magnesium Oxide. Narske, Richard M.; Klabunde, Kenneth J.; Fultz, Shawn. Department of Chemistry, Augustana College, Rock Island, IL, USA. Langmuir (2002), 18(12), 4819-4825. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:62952 AN 2002:360518 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The noncatalytic destructive adsorption of (2-chloroethyl) Et sulfide (2-CEES), a mimic of bis(2-chloroethyl) sulfide (HD or Mustard Gas), on nanocryst. Mg oxide (AP-MgO) was studied in several solvents from pentane to methanol. The decompn. products formed in these reactions were vinyl Et sulfide and (2-hydroxyethyl) Et sulfide. Reactions in pentane allowed the highest reaction rates, while THF and methanol gave results quite different from those for the hydrocarbon solvent. Reactions in methanol yielded (methoxyethyl) Et sulfide and not the vinyl Et sulfide and (2-hydroxyethyl) Et sulfide compds. These studies showed that the MgO-2-CEES reaction chem. is significantly affected by the solvent present and can be enhanced by choice of solvent and the addn. of small amts. of water. Interestingly, the least polar, least reactive solvent (pentane) allowed the most rapid 2-CEES reactions, indicating that the solvent simply aided material transfer to the reactive surface sites without blocking these sites. Rate changes upon water addn., coupled with FTIR studies, indicate that isolated surface OH groups are important reactive sites. These results indicate that the use of certain inert solvents greatly aids material transfer, and thereby the reaction rates of the sorbent with the toxin are significantly enhanced.

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Adsorption and Reaction of Diethyl Sulfide on Active Carbons with and without Impregnants under Static Conditions. Prasad, G. K.; Singh, Beer; Saradhi, U. V. R.; Suryanarayana, M. V. S.; Pandey, D. Defence Research and Development Establishment, Gwalior, India. Langmuir (2002), 18(11), 4300-4306. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:52819 AN 2002:306380 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Active carbons of different grades with and without impregnants were studied for the adsorption of di-Et sulfide (DES), the simulant of S mustard, under static conditions at 36  1. Kinetics of the adsorption were studied using linear driving force (LDF) and the Fickian diffusion model. The kinetic parameters such as equilibration time, equilibration capacity, equilibration const., diffusional exponent, and adsorbate-adsorbent interaction const. (K) were detd. The diffusional exponent (n), being <0.5, indicated a Fickian mode of diffusion of DES in the studied C. Chem. interaction also seemed to be the 2nd mechanism (although minor) involved in the DES uptake rate (the 1st being simple Fickian diffusion). The adsorbate-adsorbent interaction const. did not vary significantly indicating that probably DES chem. interacts to a small extent with the metal salts present on the surface of active C as impregnants. However, the characterization of reaction products, after extn. in CH2Cl2, using GC/MS indicated that the system CrO3/NaOH/C (C impregnated with Cr(VI) plus NaOH) only reacted with DES to give di-Et sulfone.

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An improved brain slice model of nerve agent-induced seizure activity. Wood, Sebastien J.; Tattersall, John E. H. Biomedical Sciences Department, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(Suppl. 1), S83-S86. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:290254 AN 2002:246280 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice prepn. Soman (1 M) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice prepn. is a suitable model for investigating the origin and propagation of nerve agent-induced seizures within the limbic system.

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The NMDA receptor ion channel: a site for binding of huperzine A. Gordon, Richard K.; Nigam, Savita V.; Weitz, Julie A.; Dave, Jitendra R.; Doctor, Bhupendra P.; Ved, Haresh S. Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S47-S51. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:397222 AN 2002:246274 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Huperzine A (HUP-A), first isolated from the Chinese club moss Huperzia serrata, is a potent, reversible and selective inhibitor of acetylcholinesterase (AChE) over butyrylcholinesterase (BChE) (Life Sci. 54: 991-997). Because HUP-A has been shown to penetrate the blood-brain barrier, is more stable than the carbamates used as pretreatments for organophosphate poisoning (OP) and the HUP-A:AChE complex has a longer half-life than other prophylactic sequestering agents, HUP-A has been proposed as a pretreatment drug for nerve agent toxicity by protecting AChE from irreversible OP-induced phosphonylation. More recently (NeuroReport 8: 963-968), pretreatment of embryonic neuronal cultures with HUP-A reduced glutamate-induced cell death and also decreased glutamate-induced calcium mobilization. These results suggest that HUP-A might interfere with and be beneficial for excitatory amino acid overstimulation, such as seen in ischemia, where persistent elevation of internal calcium levels by activation of the N-methyl-D-aspartate (NMDA) glutamate subtype receptor is found. The authors have now investigated the interaction of HUP-A with glutamate receptors. Freshly frozen cortex or synaptic plasma membranes were used, providing 60-90% specific radioligand binding. Huperzine A (100 M) had no effect on the binding of [3H]glutamate (low- and high-affinity glutamate sites), [3H]MDL 105,519 (NMDA glycine regulatory site), [3H]ifenprodil (NMDA polyamine site) or [3H]CGS 19755 (NMDA antagonist). In contrast with these results, HUP-A non-competitively (Hill slope < 1) inhibited [3H]MK-801 and [3H]TCP binding (co-located NMDA ion channel PCP site) with pseudo Ki .apprx. 6 M. Furthermore, when neuronal cultures were pretreated with HUP-A for 45 min prior to NMDA exposure, HUP-A dose-dependently inhibited the NMDA-induced toxicity.
Although HUP-A has been implicated to interact with cholinergic receptors, it was without effect at 100 M on muscarinic (measured by inhibition of [3H]QNB or [3H]NMS binding) or nicotinic [3H]epibatidine binding) receptors; also, HUP-A did not perturb adenosine receptor binding [3H]PIA or [3H]NECA). Therefore, HUP-A most likely attenuates excitatory amino acid toxicity by blocking the NMDA ion channel and subsequent Ca2+ mobilization at or near the PCP and MK-801 ligand sites. Thus, on the one hand, HUP-A could be used as a pretreatment against OPs and it might also be a valuable therapeutic intervention in a variety of acute and chronic disorders by protecting against overstimulation of the excitatory amino acid pathway. By blocking NMDA ion channels without psychotomimetic side-effects, HUP-A may protect against diverse neurodegenerative states obsd. during ischemia or Alzheimer's disease.

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Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense. Smith, J. Richard; Shih, Ming L.; Price, Elvis O.; Platoff, Gennady E.; Schlager, John J. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S35-S41. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365032 AN 2002:246272 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An army medical field lab. presently has the capability of performing std. protocols developed at the US Army Medical Research Institute of Chem. Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chem. warfare agents using gas chromatog./mass spectrometry. Addnl., chem. warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biol. half-lives and can be used as diagnostic biomarkers of chem. agent exposure. An anal. technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examd. for its potential to analyze these biomarkers. The technique is capable of detecting large biomols. and modifications made to them. Its fast anal. time makes MALDI-TOF/MS technol. suitable for screening casualties from chem. or biol. attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

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Analysis of the degradation compounds of chemical warfare agents using liquid chromatography/mass spectrometry. Smith, J. Richard; Shih, Ming L. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S27-S34. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365031 AN 2002:246271 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of the degrdn. products of chem. warfare (CW) agents has been a challenge to analysts. The low volatility of these compds. makes them unsuitable for direct gas chromatog. anal. without prior derivatization. Lack of a chromophore causes difficulties with classic detection methods after liq. chromatog. sepn. With the recent development of various interfaces that allow for the introduction of a liq. solvent stream into the mass spectrometer, the task of directly analyzing these compds. has become easier. For this report, the authors examd. three different liq. chromatog./mass spectrometry (LC/MS) interfaces for their suitability for the anal. of CW degrdn. compds. The interface types examd. were particle beam electron impact ionization (PBI), electrospray ionization (ESI) and atm. pressure chem. ionization (APCI). Several alkylphosphonates and thiodiglycol analogs that are produced from the degrdn. of organophosphorus nerve agents and sulfur mustard, resp., were analyzed using each of the three techniques. Electron impact ionization following gas chromatog. or particle beam introduction typically generates very reproducible, library-searchable mass spectra. Most of the CW breakdown compds. examd. using the PBI interface did not produce a mol. ion. Despite the lack of a mol. ion, the mass spectra of the various compds. contained enough different structural information from fragment ions for the pos. identification of each. The mass spectra generated using ESI are generally limited to protonated mol. ions with little or no fragmentation. For pos. identification and confirmation, tandem mass spectrometry techniques quite often must be used. Many of the compds. in this study were characterized by prominent sodiated adducts along with the protonated mol. ion. Methylphosphonic acid produced protonated dimers, trimers, etc. Although the various adduct ions can be used for addnl. confirmation of the mol. wt. of a compd., the adducts also can result in suppression of ionization of the compd.
and thus reduce sensitivity. Another "soft" ionization technique that results in abundant protonated mol. ions is APCI. The mass spectra of the breakdown compds. produced using APCI were characterized generally by either a prominent protonated mol. ion or a dehydrated form of it. In addn., a no. of structurally significant fragment ions were obsd. and their relative abundances could be adjusted by altering the APCI conditions. The data presented here indicate that each of the three techniques can be used successfully for direct liq. introduction and anal. of the non-volatile compds. produced from the degrdn. of CW agents. The mass spectra produced using each technique are quite different and could be utilized as addnl. confirmation of compd. identity.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller, Jennifer K.; Lenz, David E. Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S23-S26. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:336395 AN 2002:246270 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-mol.-wt. compds. is effected by the use of chromatog. techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the anal. To overcome those drawbacks, the authors were involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compds. such as pinacolylmethyl phosphonofluoridate (soman), which is a chem. warfare agent. Prior ests. suggested that it is necessary to be able to detect soman at a concn. below 2.5  10-7 M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The min. required assay time was 2.0-2.5 h with no loss in sensitivity. To det. the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogs were 5  10-7 M for 4-nitrophenylpinacolylmethylphosphonate, 8  10-7 M for dipinacolylmethylphosphonate, 2  10-6 M for diisopropylmethylphosphonate, 3  10-5 M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5  10-5 M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman mol., were effective inhibitors. Compds., which contained predominately arom. groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to det. its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman.

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The active site of human paraoxonase (PON1). Josse, Denis; Lockridge, Oksana; Xie, Weihua; Bartels, Cynthia F.; Schopfer, Lawrence M.; Masson, Patrick. Eppley Institute, University of Nebraska Medical Center, Omaha, NE, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S7-S11. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365079 AN 2002:246267 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ideally the authors would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman. However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4  106 M-1 min-1, and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, the authors have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw, M. D.; Hayes, T. L.; Miller, T. L.; Shannon, C. M. Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S3-S6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365078 AN 2002:246266 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) iso-Bu methylphosphonothiolate-a V-type nerve agent developed by the former Soviet Union-in the environment is an important parameter in threat assessment anal. and for the detn. of use, prodn., testing and storage of this chem. warfare agent. S-(N,N-Diethylaminoethyl) iso-Bu methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same mol. formula, it is expected that their phys. and chem. properties would be different. This preliminary investigation was undertaken to det. the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compd. at approx. 1 mg ml-1 in unbuffered water at pH 7 was detd. side-by-side. The half-lives for VXA and VX were detd. to be 12.4 days and 4.78 days, resp. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chem. Weapons Convention.

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Synthesis of high surface area monoclinic WO3 particles using organic ligands and emulsion based methods. Lu, Zhixiang; Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST), University of Maine, Orono, ME, USA. Journal of Materials Chemistry (2002), 12(4), 983-989. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 136:389533 AN 2002:226497 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several synthetic approaches have been used to obtain nano-sized monoclinic WO3 (m-WO3) powders. All of these methods begin with a std. preparative method where H2WO4 is first generated by passing a Na2WO4 soln. through a cation-exchange resin. It is shown that high surface area particles are produced by dripping the H2WO4 exiting from the ion-exchange column into a soln. contg. oxalate and acetate exchange ligands or alternatively, into a water-in-oil (w/o) based emulsion. In comparison to com. WO3 powders, the surface area of the m-WO3 powders were higher by factors of 10 and 20 times when prepd. in the presence of acetate/oxalate chelating agents and w/o emulsions, resp. The much higher surface areas enable IR spectroscopic identification of surface sites along with detection and monitoring of gaseous reactions and adsorbed species on the surface of this metal oxide. This is demonstrated with the adsorption of a nerve agent simulant, di-Me Me phosphonate. In general, little is known about the reactions of gaseous mols. on m-WO3 surfaces and the fabrication of high surface area m-WO3 particles will aid in gaining an understanding of the chem. processes occurring in WO3 based sensors.

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Prefiltering Strategies for Metal Oxide Based Sensors: The Use of Chemical Displacers to Selectively Dislodge Adsorbed Organophosphonates from Silica Surfaces. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2002), 18(3), 722-728. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 136:173252 AN 2002:22837 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

IR spectroscopy is used to monitor the competitive adsorption/desorption behavior of the nerve gas simulants, di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on SiO2. All 4 compds. molecularly adsorb via hydrogen bonds (H-bonds) with the surface hydroxyl groups. The adsorption strength depends on 2 factors: the specific functional group H-bonded to the surface hydroxyl groups and the no. of such bonds per mol. The phosphonates are molecularly displaced from the SiO2 surface by chem. displacers. By judiciously selecting chem. displacers as dictated by the 2 factors, (i.e., type and no. of functional groups H-bonded to the surface silanols) it is possible to selectively and sequentially dislodge each of the 4 phosphonate compds. adsorbed on SiO2. Specifically, the relative adsorption strength of the phosphonate compds. and the chem. displacers (labeled A-C) follows the order: TCP < MDCP < A < DMMP < B < TMP < C, where A = NEt3 (TEA), B = 2-pyridyl MeCN (2-PyAN), and C= ethylenediamine (EDA). AM1 semiempirical calcns. show that the toxic nerve agent, sarin, would position itself between MDCP and DMMP in the above order. The implications of using chem. displacers in filtering applications with metal oxide based sensors are discussed.

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New -phthalimidoperoxyalkanoic acids in decontamination. Destruction of some toxic organophosphorus and organosulfur pollutants. Lion, Claude; Da Conceicao, Louis; Delmas, Gerard; Magnaud, Gilbert. Institut de Topologie et de Dynamique des Systemes, Universite de Paris 7, Paris, Fr. New Journal of Chemistry (2001), 25(9), 1182-1184. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 136:90120 AN 2001:726141 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (chem. warfare agents and/or insecticides) is of increasing importance. We report the use of -phthalimidoperoxyalkanoic acids in the destruction of paraoxon (di-Et p-nitrophenyl phosphate), a well-known insecticide, and 2-chloro-2'-phenyldiethyl sulfide (a half mustard). We show that while all the peroxy acids used in this series allow the destruction of toxic compds., the length n of the alkanoic side chain is important to the choice of the optimal industrial compd., which is 6-phthalimidoperoxyhexanoic acid (n = 5).

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig ear skin. Chilcott, R. P.; Jenner, J.; Hotchkiss, S. A. M.; Rice, P. Department of Biomedical Sciences, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(4), 279-283. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:191481 AN 2001:616748 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chem. warfare agent sulfur mustard (SM). The in vitro absorption rates of SM through heat-sepd. human (15766 g cm-2 h-1) and pig-ear (411175 g cm-2 h-1) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 g cm-2 h-1, resp. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig ear epidermal membranes measured in vitro. Thus, although pig ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells contg. human epidermal membranes as a model for predicting in vivo human skin absorption.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen, J.; Riikonen, K.; Nikmo, J.; Jappinen, A.; Nieminen, K. Air Quality Research, Finnish Meteorological Institute, Helsinki, Finland. Journal of Hazardous Materials (2001), 85(3), 165-179. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 136:41716 AN 2001:572441 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Math. models were developed to evaluate the atm. dispersion of selected chem. warfare agents (CWA), including evapn. and settling of pollutant liq. droplets. The presented models and numerical results may be used to design protection and control measures against the conceivable use of CWA. The model, AERCLOUD (AERosol CLOUD), was extended to treat 2 nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodn. evolution of a 5-component aerosol mixt., consisting of 2-component droplets together with the surrounding 3-component gas. Numerical computations were performed using this model on the evapn. and settling of airborne sarin droplets in characteristic dispersion and atm. conditions. In particular, the max. radii (rM) of a totally evapg. droplet, in terms of the ambient temp. and pollutant vapor concn., were evaluated. The radii rM were .apprx.15-80 m for sarin droplets for selected ambient conditions and initial heights. Deposition fractions in terms of initial droplet size were also evaluated.

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Oxidation of triphenylarsine to triphenylarsine oxide by Trichoderma harzianum and other fungi. Hofmann, K.; Hammer, E.; Kohler, M.; Bruser, V. URST Umwelt- und Rohstoff-Technologie GmbH Greifswald, Greifswald, Germany. Chemosphere (2001), 44(4), 697-700. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 135:254254 AN 2001:483254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Arsenic resistant strains of bacteria and fungi were isolated from soil contaminated by chem. warfare agents. Until now, no metabolic products of microbial attack against the Ph residues of the model substrate triphenylarsine (TP) were found if it was incubated together with these strains in liq. culture assays. However, one of the isolated fungi, Trichoderma harzianum As 11, was found to oxidize TP to triphenylarsine oxide (TPO). The yeast Trichosporon mucoides SBUG 801 and the white-rot fungus Phanerochaete chrysosporium were also able to oxidize the As(III) in TP. In addn., P. chrysosporium transformed phenylarsine oxide (PAO) to phenylarsonic acid (PAA) under O2-atmosphere. By means of a respirometer system, the oxidn. of TP by T. harzianum As 11 was confirmed by a significantly higher consumption of oxygen in the presence of these compds. HPLC anal. of the oxidn. products TPO and PAA in the medium of the assays provided evidence for the transfer reaction of As(III) to As(V) in org. bonds. The oxidn. products TPO and PAA are more hydrophilic than TP and PAO. Therefore, it was concluded that particular fungi contribute to the mobilization of arsenic in soil contaminated by chem. warfare agents.

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Nanocrystalline metal oxides as unique chemical reagents/sorbents. Lucas, Erik; Decker, Shawn; Khaleel, Abbas; Seitz, Adam; Fultz, Shawn; Ponce, Aldo; Li, Weifeng; Carnes, Corrie; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry--A European Journal (2001), 7(12), 2505-2510. CODEN: CEUJED ISSN: 0947-6539. Journal; General Review written in English. CAN 135:216336 AN 2001:471452 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 29 refs. A new family of porous inorg. solids based on nanocryst. metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar orgs., and even chem./biol. warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chem. properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price, Elvis O.; Smith, J. Richard; Clark, Connie R.; Schlager, John J.; Shih, Ming L. Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S193-S197. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:206570 AN 2001:455416 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The continual threat of chem. and biol. warfare has prompted the need for unambiguous anal. methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with Hb and metallothioneins were conducted. In vitro expts. with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to det. the extent of alkylation and occurrence of HD crosslinking using the MALDI-ToF/MS technique. In a typical expt., 50 mL of 5 mM HD in acetonitrile was added to an equal vol. of 0.5 mM Hb in deionized water followed by vortexing and incubation at room temp. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES expts. These results demonstrate that MALDI-ToF/MS is a useful anal. technique to investigate the interaction of HD with biomols. and may be employed potentially as a diagnostic tool for the confirmation of exposure to chem. warfare agents.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham, John S.; Reid, Frances M.; Smith, J. Richard; Stotts, Richard R.; Tucker, F. Steven; Shumaker, Shawn M.; Niemuth, Nancy A.; Janny, Stephen J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S161-S172. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72547 AN 2001:455411 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chem. warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clin. pathol. findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liq. on the ventral surface for 2 h, generating six 3-cm diam. full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematol. and serum chem. examns. Urine was collected in metab. cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatog./mass spectrometry. Examn. of clin. pathol. parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clin. significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 g ml-1 with a mean of 2.14 g ml-1. Thiodiglycol concns. were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml-1. Mean levels remained 10-40 ng ml-1 for the remainder of the 7-day observation period, with the highest individual concn. noted during this period of 132 ng ml-1. Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other lab. animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 wk. Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h.
Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin, M. C.; Ricketts, K.; Skvorak, J. P.; Gazaway, M.; Mitcheltree, L. W.; Casillas, R. P. Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S141-S144. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72425 AN 2001:455408 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quant. edema response as well as histopathol. and biochem. endpoints as measurements of inflammation and tissue damage following exposure to the chem. warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal sepn. This study evaluated the protective effects of three of these pharmacol. compds. when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver an s.c. dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 l of a 195 mM (0.16 mg) soln. of sulfur mustard (d. = 1.27 g ml-1; MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathol. damage (necrosis, epidermal-dermal sepn.). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant redn. in edema (24%, 26% and 22%, resp.) from the pos. control. Compared to HD-pos. controls, hydrocortisone, indomethacin and olvanil caused a significant redn. in subepidermal blisters (71%, 52% and 57%, resp.) whereas only hydrocortisone produced a significant redn. in contralateral epidermal necrosis (41%). The authors show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins, Kevin B.; Lodhi, Irfan J.; Hurley, Lauren L.; Hinshaw, Daniel B. University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S125-S128. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72423 AN 2001:455404 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chem. warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells. Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 M HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 M buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 M HD for 5-6 h. Externally applied GSH up to a concn. of 5 mM had no toxic effect on the cells. Mild toxicity was assocd. with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examd. the hypothesis that HD may activate the nuclear transcription factor NFB by performing EMSAs with nuclear exts. of endothelial cells following exposure to 0, 250 or 500 M HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFB binding to its consensus sequence induced by 500 M HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFB, although HD-induced activation of NFB was partially suppressed by NAC at 5 h. Factor NFB is an important transcription factor for a no. of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFB activity. The NFB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction assocd. with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha, M.; Bowers, W., Jr.; Kohl, J.; DuBose, D.; Walker, J.; Alkhyyat, A.; Wong, G. US Army Research Institute of Environmental Medicine, Natick, MA, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S101-S108. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72420 AN 2001:455401 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl Et sulfide (CEES, 1-2 mg l-1 min-1) in humidified air or to humidified air alone. Tissues were evaluated histol., ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histol. showed that CEES induced the sepn. of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histol. and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1 (IL-1), prostaglandin-E2 (PGE2) and esp. IL-1 receptor antagonist (IL-1Ra) release (56334 vs. 84614 pg ml-1), but decreased interleukin-6 (IL-6, 4755 vs. 351 pg ml-1). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracellular IL-1 (371 vs. 92 pg ml-1). Extracellular IL-1Ra greatly increased (2375 vs. 24875 pg ml-1), whereas cellular levels decreased (165425 vs. 96625 pg ml-1). Extracellular (224 vs. 68 pg ml-1) and intracellular (485 vs. 233 pg ml-1) sol. interleukin-1 receptor II (sIL-1RII) decreased. Prostanglandin E2 increased (1835 vs. 2582 pg ml-1), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57000 vs. 96000 pg ml-1). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Intervention of sulfur mustard toxicity by down-regulation of cell proliferation and metabolic rates. Ray, R.; Benton, B. J.; Anderson, D. R.; Byers, S. L.; Petrali, J. P. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S87-S91. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72419 AN 2001:455399 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chem. warfare compd. HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37) first in keratinocyte growth medium (KGM) contg. BAPTA AM (10-40 M) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concn.-dependent manner with some cellular degeneration above 30 M (light microscopy). At 20-30 M, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 545%), [3H]-uridine (RNA synthesis, 296%) and [14C]-valine (protein synthesis, 122%) as well as a lower protein content per culture (303%) compared with corresponding untreated controls. However, 20-30 M BAPTA AM did not cause any demonstrable cytopathol. based on morphol. (electron microscopy) as well as biochem. (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Calmodulin, poly(ADP-ribose)polymerase and p53 are targets for modulating the effects of sulfur mustard. Rosenthal, Dean S.; Simbulan-Rosenthal, Cynthia M.; Iyer, Sudha; Smith, William J.; Ray, Radharaman; Smulson, Mark E. Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S43-S49. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72546 AN 2001:455392 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

We describe two pathways by which the vesicating agent sulfur mustard (HD) may cause basal cell death and detachment: induction of terminal differentiation and apoptosis. Following treatment of normal human epidermal keratinocytes (NHEK) with 10 or 100 M HD, the differentiation-specific keratin pair K1/K10 was induced and the cornified envelope precursor protein, involucrin, was crosslinked by epidermal transglutaminase. Fibronectin levels were reduced in a time- and dose-dependent manner. The rapid increase in p53 and decrease in Bcl-2 levels was consistent not only with epidermal differentiation but with apoptosis as well. Further examn. of biochem. markers of apoptosis following treatment of either NHEK or human papillomavirus (HPV)-immortalized keratinocytes revealed a burst of poly(ADP-ribose) synthesis, specific cleavage of poly(ADP-ribose)polymerase (PARP) in vivo and in vitro into characteristic 89 and 24 kDa fragments, processing of caspase-3 into its active form and the formation of DNA ladders. The intracellular calcium chelator BAPTA suppressed the differentiation markers, whereas antisense oligonucleotides and chem. inhibitors specific for calmodulin blocked both markers of differentiation and apoptosis. Modulation of p53 levels utilizing retroviral constructs expressing the E6, E7 or E6 + E7 genes of HPV-16 revealed that HD-induced apoptosis was partially p53-dependent. Finally, immortalized fibroblasts derived from PARP -/- "knockout mice" were exquisitely sensitive to HD-induced apoptosis. These cells became HD resistant when wild-type PARP was stably expressed in these cells. These results indicate that HD exerts its effects via calmodulin, p53 and PARP-sensitive pathways.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser, Janet; Meier, Henry L. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S23-S30. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72413 AN 2001:455389 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chem. warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compds. in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell prepns. were exposed to various concns. of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these expts. suggest that, with increasing HD concn. and time, NHEK will fragment irresp. of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains const. over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concn.- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, resp., is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concns. that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers, S.; Anderson, D.; Brobst, D.; Cowan, F. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S19-S22. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72270 AN 2001:455388 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chem. warfare compd., has been shown to deplete the NAD (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compds. To examine NAD+ levels, an automated method based on the alc. dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clin. analyzer has been developed. Automation of this assay led to smaller sample vols. and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD-exposed group. This assay appears to be useful for testing potential antivesicant compds. using both in vivo and in vitro exposure systems.

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Effects of Lewisite on cell membrane integrity and energy metabolism in human keratinocytes and SCL II cells. Kehe, K.; Flohe, S.; Krebs, G.; Kreppel, H.; Reichl, F. X.; Liebl, B.; Szinicz, L. Institute of Pharmacology and Toxicology, FAF Medical Academy, Munich, Germany. Toxicology (2001), 163(2-3), 137-144. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:133255 AN 2001:448571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite is a highly toxic arsenic compd. which can cause skin damage. In the present study effects of Lewisite on cell membrane integrity and energy metab. as well as antidotal effects of DL-2,3-dimercaptopropanesulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (m-DMSA) were investigated in a keratinocyte derived cell line (SCL II) and primary human keratinocytes (HK). Cells were incubated in Lewisite (60 M) contg. medium for 5 min. During the following 6 h lactate dehydrogenase (LDH) activity in the supernatant, intracellular ATP content, tetrazolium redn., glucose consumption and lactate formation were measured. Glucose consumption and lactate prodn. were decreased in both cell lines after Lewisite exposure. In SCL II cells an increase of LDH activity in the supernatant, a decrease of ATP content, and an impaired ability to reduce tetrazolium was found 3 h after Lewisite exposure. In HK cultures tetrazolium redn. was significantly decreased already after 2 h, whereas LDH increase in the supernatant and ATP content decrease occurred only at 6 h after Lewisite exposure. When DMPS or m-DMSA was added directly after Lewisite exposure to SCL II cells, glucose consumption and lactate formation were restored and LDH leakage was prevented. SCL II cells might be more prone to membrane damage whereas in keratinocytes mitochondrial impairment seems to be the predominant effect of Lewisite.

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Prophylactic efficacy of amifostine and its analogues against sulphur mustard toxicity. Vijayaraghavan, R.; Kumar, P.; Joshi, U.; Raza, S. K.; Lakshmana Rao, P. V.; Malhotra, R. C.; Jaiswal, D. K. Defence Research and Development Establishment, Gwalior, India. Toxicology (2001), 163(2-3), 83-91. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:299804 AN 2001:448565 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The successful implication of the chem. weapons convention stimulated research with a new vigor on the destruction of the stockpiled sulfur mustard (SM). A prophylactic agent for SM will be very useful for personnel engaged in the destruction of SM and during inspections by the Organization for the Prohibition of Chem. Weapons. Due to simple method of prepn., SM can be used clandestinely during war or by terrorist groups. Inspite of research over several decades no satisfactory prophylactic or treatment regimen has evolved for SM. Amifostine an organophosphorothioate, originally developed as a radioprotector, and its analogs were evaluated as a prophylactic agent for SM. Three analogs by varying the chain length and substitution at the sulfur atom were synthesized and coded as DRDE-06, DRDE-07 and DRDE-08. LD50 of amifostine and its analogs were estd. through i.p. route. For the protection studies, amifostine and its analogs were administered i.p. in mice, 30 min before dermal (percutaneous) application of SM. The dose of the prophylactic agent was 0.2 LD50 (i.p.) and that of SM was 152 mg/kg (undiluted) equal to 19-fold LD50 of SM. Amifostine and one of its analogs, DRDE-07 gave significant protection. Further studies were carried out using amifostine and DRDE-07, and both of them significantly protected mice against SM (155 mg/kg, in PEG 300, equal to 19 LD50) when they were administered i.p. either 30 min before or simultaneously. LD50 of amifostine and DRDE-07 were also estd. through the oral route (1049 or 1248 mg/kg, resp.). Prophylactically administered amifostine and DRDE-07 (0.2 LD50, p.o.) significantly protected the mice against dermally applied SM (155 mg/kg, in PEG 300, equal to 19 LD50). The protection offered by DRDE-07 was better than that of amifostine by the oral route. DRDE-07 (0.2 LD50, p.o.) also protected significantly with respect to the decrease in body wt. and the depletion of GSH induced by SM.
DNA damage induced by SM was also significantly reduced by amifostine and DRDE-07 (0.2 LD50, p.o.). Further studies are in progress on the various pharmacol. and toxicol. properties of DRDE-07.

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Adsorption of Organic Contaminants from Water Using Tailored ACFs. Mangun, Christian L.; Yue, Zhongren; Economy, James; Maloney, Stephen; Kemme, Patricia; Cropek, Donald. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, USA. Chemistry of Materials (2001), 13(7), 2356-2360. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 135:200059 AN 2001:428900 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Six activated carbon fibers (ACFs) with different chem. and phys. properties were prepd. by 1st curing a phenolic resin-coated glass fiber, followed by activation and post-treatment. Their adsorption properties were studied to evaluate the removal of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and the chem. warfare simulants diisopropylmethyl phosphonate (DIMP) and half mustard (HM) from water. The adsorption isotherms showed that ACF SL-2 (activated with CO2/H2O at 800) has a higher adsorption capacity for BTEX, DIMP, and HM than other ACFs. This suggests that the high adsorption affinity of SL-2 is related to its higher surface area, larger av. micropore size of 11.6 .ANG. (esp. effective for the adsorption of DIMP), and lower O content of the surface. The adsorption isotherms are well represented by the Freundlich equation. For BTEX, the adsorption parameters based on C coating showed that, in all cases, ACFs have a higher K value than the best available data obtained on granulated activated C. The adsorption isotherms of DIMP and HM on ACFs are presented.

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The U.S. Army reactive topical skin protectant (rTSP): challenges and successes. Hobson, Stephen T.; Lehnert, Erich K.; Braue, Ernest H., Jr. Drug Assessment Division, U. S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Materials Research Society Symposium Proceedings (2001), 628(Organic/Inorganic Hybrid Materials), CC10.8.1-CC10.8.8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 135:118044 AN 2001:354344 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In 1994, the U.S. Army initiated a research effort towards an effective material that acts both as a protective barrier and as an active destructive matrix against chem. warfare agents (CWA). We report results on our prepn. and evaluation of Reactive Topical Skin Protectants (rTSP's). These creams are composite materials consisting of a base material (TSP) and a reactive moiety. Using an established base of perfluorinated-polyether and perfluoropolyethylene solids we incorporated over 60 reactive components. Classes tested include org. polymers, org./inorg. hybrid materials, polyoxometallates (POM's), enzymes, inorg. oxides, metal alloys and small mols. We characterized these materials by light microscopy and FTIR. We detd. the efficacy of these materials against both sulfur mustard (HD) and a representative nerve agent, soman (GD), using a penetration cell model coupled to a continuous air monitor and also by in vivo testing. Composite materials with optimum reactive compds. exhibit a 94% redn. of GD vapor break-through after 20 h (from 9458 ng to 581 ng) and a 3.6 fold increase (from 162 min to 588 min) in the time 1000 ng of GD liq. penetrates through the material. Similar composite materials show a 99% redn. in HD vapor break-through after 20 h (from 4040 ng to 16 ng), a 2.3 fold increase (from 524 min to > 1200 min) in the time 1000 ng of HD vapor penetrates through the material, and an elimination of erythema vs. control in an HD vapor challenge. These results indicate that an rTSP that protects against sulfur mustard and nerve agents is within reach.

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Inhibition and promotion of combustion by organophosphorus compounds added to flames of CH4 or H2 in O2 and Ar. Korobeinichev, O. P.; Bolshova, T. A.; Shvartsberg, V. M.; Chernov, A. A. Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia. Combustion and Flame (2001), 125(1/2), 744-751. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 134:328437 AN 2001:309769 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Early in evaluating the destruction mechanisms of a no. of organophosphorus compds. (OPCs), such as tri-Me phosphate (TMP), di-Me methylphosphonate, and diisopropyl methylphosphonate, in connection with the disposal of chem. warfare agents, the promotion and inhibition effects of OPCs on stabilized flat flames of H2 +O2 were studied. Because OPCs were demonstrated to be more effective fire suppressants than CF3Br (Halon 1301) and due to the need for replacing the currently used Halon 1301, further investigation of the effects of the OPCs on flames is of interest. Thus a lean flame of CH4/O2/Ar (0.078/0.222/0.7) with and without TMP added, stabilized on a flat burner at 0.1 bar, was studied by mol. beam mass spectrometry (MBMS) and computer modeling using PREMIX and CHEMKIN codes. An exptl. study of this flame revealed that TMP increases the width of the reaction zone by inhibiting the flame.

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An Infrared Study of Adsorbed Organophosphonates on Silica: A Prefiltering Strategy for the Detection of Nerve Agents on Metal Oxide Sensors. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2001), 17(7), 2213-2218. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 134:349067 AN 2001:156303 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The gas-phase adsorption of the nerve gas simulant di-Me methylphosphonate (DMMP) along with tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on silica have been studied using IR spectroscopy. Each phosphonate compd. adsorbs through a different no. of H-bonds of the methoxy and P:O moieties with the surface hydroxyl groups on silica. The strength of the adsorption depends on the no. and type of the H-bonds and follows the order TCP < MDCP < DMMP < TMP. TCP is completely removed from silica by evacuation at room temp., adsorbed MDCP is removed by evacuation at 150 C, DMMP requires an evacuation temp. of 300 C, and TMP is eliminated at 400 C. All phosphonate compds. molecularly desorb, and the silica returns to its original state. The differences in the reactivity of phosphonate compds. on silica from other oxides demonstrate the potential use of silica in prefiltering/preconcg. strategies for semiconductive metal oxide based sensing devices. Specifically, it is shown that silica can be used to selectively adsorb DMMP from a gas stream contg. methanol/DMMP mixts.

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Reactions of VX, GB, GD, and HD with Nanosize Al2O3. Formation of Aluminophosphonates. Wagner, George W.; Procell, Lawrence R.; O'Connor, Richard J.; Munavalli, Shekar; Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA. Journal of the American Chemical Society (2001), 123(8), 1636-1644. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 134:276643 AN 2001:85006 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of VX, GB, GD, and HD with nanosize Al2O3 (AP-Al2O3) have been characterized by 31P, 13C, and 27Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH3)OR]3, are generated which are identical to synthesized model compds. Thus, the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amt. of the CH-TG sulfonium ion (12%), although some elimination of HCl is also obsd. (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addn. of excess water results in the quant. hydrolysis of sorbed HD to CH-TG. On AP-Al2O3 dried to remove physisorbed water, 13C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

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New microemulsions for oxidative decontamination of mustard gas analogues and polymer-thickened half-mustard. Gonzaga, Ferdinand; Perez, Emile; Rico-Lattes, Isabelle; Lattes, Armand. Laboratoire des Interactions Moleculaires et Reactivite Chimique et Photochimique (CNRS UMR 5623), Universite Paul Sabatier, Toulouse, Fr. New Journal of Chemistry (2001), 25(1), 151-155. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 134:232826 AN 2001:12053 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidn. of mustard gas analogs in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quant. and chemoselective oxidn. of the analogs. In a second formulation, the choice of microemulsion components used allowed us to study the oxidn. of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aq. systems.

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Bacterial release of arsenic ions and organoarsenic compounds from soil contaminated by chemical warfare agents. Kohler, Manfred; Hofmann, Klaus; Volsgen, Fernando; Thurow, Kerstin; Koch, Andreas. URST Umwelt- und Rohstoff-Technologie GmbH, Greifswald, Germany. Chemosphere (2000), Volume Date 2001, 42(4), 425-429. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 134:60919 AN 2000:878002 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The objective was to study possible participation of microorganisms in the release of sol. arsenical compds. from organoarsenic warfare agents in contaminated soil. A no. of bacterial strains were isolated with high resistance against As5+ ions which are able to degrade the water insol. compds. triphenylarsine (TP) and triphenylarsineoxide (TPO). Release of As and sol. organoarsenic compds. from soil by the activity of autochthonic soil bacteria and a mixt. of the isolated pure cultures was demonstrated by percolation expts. with undisturbed soil samples (core drills) from the contaminated site. This release increased after addnl. of nutrients (mineral N and P, Na acetate and ethanol) and is nearly independent of the percolation temp. (5 and 22). These results show that bacteria play an important role in the release of arsenical compds. from organoarsenic warfare agent contaminated soil. This release is limited by shortage of water and, above all, of nutrients for the microorganisms in the sandy forest soil. These results are important both for the management and security and possibly for bioremediation of military waste sites contg. similar contaminations.

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The chemistry of the destruction of organophosphorus compounds in flames-IV: destruction of DIMP in a flame of H2 + O2 + Ar. Korobeinichev, O. P.; Chernov, A. A.; Bolshova, T. A. Institute of Chemical Kinetics and Combustion, Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia. Combustion and Flame (2000), 123(3), 412-420. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 133:285779 AN 2000:714913 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mol. beam mass spectrometry with electron impact ionization at 11-70 eV and an electron energy spread of  0.25 eV was used to study the structure of a premixed H2/O2/Ar (0.26/0.13/0.61) flame without any additives and with 0.14% of diisopropylmethylphosphonate (DIMP), stabilized on a flat-flame burner at 62 mbar. Stable species (H2, O2, H2O), as well as atoms and radicals (H, O, OH) were monitored, including phosphorus-contg. compds.: DIMP and some intermediates of its destruction, phosphorus oxides and acids. The profiles of the mole fractions of most species, including those of atoms and free radicals were obtained. The calibration coeffs. for some species were detd. exptl., and estd. for others. Isopropylmethylphosphonate was detected as a main primary phosphorus-contg. product of the destruction of DIMP. It has been shown that bimol. reactions with hydroxyl radicals and hydrogen atoms, rather than a unimol. decompn., provide the crucial initial steps in the destruction of DIMP. A detailed mechanism for the destruction of DIMP in H2/O2/Ar flames is suggested.

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Cytotoxicity of the MEIC reference chemicals in rat hepatoma-derived Fa32 cells. Dierickx, P. J. Laboratorium Biochemische Toxikologie, Afdeling Toxikologie, Instituut voor Volksgezondheid, Brussels, Belg. Toxicology (2000), 150(1-3), 159-169. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 134:1437 AN 2000:660792 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The cytotoxicity of the MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) ref. chems. was investigated in rat hepatoma-derived Fa32 cells. The total protein content was measured as an endpoint after exposure times of 30 min and 24 h, both in normal and glutathione-depleted cells. The neutral red uptake inhibition and the MTT conversion were also measured after 30 min. On av., the cytotoxicity was higher in glutathione-depleted cells when compared to normal cells, and was lower after 30 min than after 24 h. Evidence was obtained for lysosomal attack (of five chems.) or mitochondrial dysfunction (of six chems.) as the primary intoxication mechanism. Malathion and mercuric chloride belong to both series of chems. Good to excellent correlations were obsd. when the 50% inhibitory concns. of the six different in vitro assays were compared. When the six in vitro assays in Fa32 cells were compared with the human toxicity, the correlation coeff. was almost always identical to that obtained previously in human hepatoma-derived Hep G2 cells. The latter was the best acute in vitro assay for the prediction of human toxicity within the MEIC study. Altogether the results integrate very well with the basal cytotoxicity concept (B. Ekwall; 1995).

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The role of time in toxicology or Haber's ct product. Rozman, K. K. Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA. Toxicology (2000), 149(1), 35-42. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 133:306404 AN 2000:589244 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It happened exactly 100 yr ago that Warren established for the first time a quant. link between dose and time while studying the toxicity of sodium chloride in Daphnia magna (Straus). During this century many toxicologists in different contexts returned to this idea, which has become known as Haber's rule of inhalation toxicol. Most attempts to explore this relationship ended in frustration because of the supposed occurrence of exceptions. Thus, toxicologists concd. on the quant. relationship between dose and effect under mostly isotemporal conditions while time took a back seat and was assigned such arbitrary, semiquant. designations as acute, subacute, subchronic and chronic. Time itself as a quantifiable variable of toxicity was seldom studied and when it was studied, it was often not under isodosic (steady state) conditions as required by theory. A recent anal. of toxicol. time indicated the impact of three independent time scales (toxicokinetic, toxicodynamic, exposure frequency/duration) in toxicol. studies, which interact with dose and effect to yield the enormous complexity known to every toxicologist. Based on prototypical examples when toxicokinetic (dioxins), toxicodynamic (nitrosamines, benzene) or exposure frequency (methylene chloride, chloroacetic acid, HgCl2, CdCl2, etc.) represent the crit. time scale, the general validity of the ct=k concept will be discussed as a starting point for a theory of toxicol. As endpoints of toxicity, (delayed) acute toxicity, blood dyscrasias and cancer will be used to illustrate the crit. conditions needed to demonstrate the validity of this theory.

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Detection of Fluorophosphonate Chemical Warfare Agents by Catalytic Hydrolysis with a Porous Silicon Interferometer. Sohn, Honglae; Letant, Sonia; Sailor, Michael J.; Trogler, William C. Department of Chemistry and Biochemistry, University of California at San Diego, CA, USA. Journal of the American Chemical Society (2000), 122(22), 5399-5400. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 133:100551 AN 2000:335868 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The detection of a fluorophosphonate nerve chem. warfare agent can be achieved with an oxidized porous silicon interferometer film contg. a Cu(II) hydrolysis catalyst and surfactant (CTAB). Hydrolysis of the nerve agent produces HF gas, which removes the silicon oxide as SiF4(g) and induces both a blue-shift and a decrease in intensity of the Fabry-Perot fringes. Significant changes in these 2 parameters are detected after 5 min of DFP vapor (800 ppm) exposure.

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Reactions of VX, GD, and HD with Nanosize CaO: Autocatalytic Dehydrohalogenation of HD. Wagner, George W.; Koper, Olga B.; Lucas, Erik; Decker, Shawn; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, MD, USA. Journal of Physical Chemistry B (2000), 104(21), 5118-5123. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 133:30783 AN 2000:281288 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of the chem. warfare agents VX, GD, and HD with nanosize CaO (AP-CaO), and HD with com. CaO were studied using solid-state MAS NMR. VX and GD hydrolyze to yield surface-bound complexes of nontoxic Et methylphosphonate and pinacolyl methylphosphonate, resp. The kinetics were characterized by an initial fast reaction followed by a slower, diffusion-limited reaction. Similar behavior is obsd. for HD on either dried or hydrated AP-CaO and CaO. On partially hydrated AP-CaO (but not CaO), a rather fast steady-state elimination of HCl occurs after an induction period. This behavior is attributed to acid-catalyzed surface reconstruction (to regenerate fresh surface) and the formation of CaCl2, which is known to be more reactive than CaO. The product distribution for HD is .apprx.80% divinyl sulfide and 20% thiodiglycol and/or sulfonium ions, which apparently reside as surface alkoxides. Such kinetic behavior was not evident for the common mustard simulant 2-chloroethyl Et sulfide (CEES) on partially hydrated AP-CaO, which exhibited only the typical fast/diffusion-limited reaction.

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Design and synthesis of an ,-difluorophosphinate hapten for antibody-catalyzed hydrolysis of organophosphorus nerve agents. Vayron, Philippe; Renard, Pierre-Yves; Valleix, Alain; Mioskowski, Charles. CEA, Service des Molecules Marquees, CE-Saclay, Gif sur Yvette, Fr. Chemistry--A European Journal (2000), 6(6), 1050-1063. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 133:13524 AN 2000:214064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In a new approach to the safe neutralization of organophosphorus chem. weapons, we designed a hapten to elicit catalytic antibodies with phosphatase activity. Here we report the synthesis of this ,-difluorophosphinate hapten 6. Various methods for the introduction of the key ,-difluoromethyl feature into the phosphinate hapten are discussed. The best results were obtained with the electrophilic gem-difluorinating agent N-fluorobenzenesulfonimide.

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Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate. Richardson, David E.; Yao, Huirong; Frank, Karen M.; Bennett, Deon A. Center for Catalysis Department of Chemistry, University of Florida, Gainesville, FL, USA. Journal of the American Chemical Society (2000), 122(8), 1729-1739. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 132:222157 AN 2000:94955 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Bicarbonate ion is an effective activator for hydrogen peroxide in the oxidn. of sulfides. Kinetic and spectroscopic results support the formation of peroxymonocarbonate ion (HCO4-) as the oxidant in the catalytic reactions. The reaction of hydrogen peroxide and bicarbonate to form HCO4- occurs rapidly at 25 (t1/2  300 s) near neutral pH in aq. soln. and alc./water mixts., and an equil. anal. of the reaction by 13C NMR leads to an est. of the electrode potential for the HCO4-/HCO3- couple (1.8 V vs NHE). Soly. of the bicarbonate catalyst is enhanced by the use of NH4HCO3 rather than by the use of group 1 salts, which tend to have lower soly. in the mixed solvents and can lead to phase sepn. Rate laws and mechanistic analyses are presented for the oxidn. of Et Ph sulfide and related sulfides. The second-order rate consts. for sulfide oxidns. by HCO4- are .apprx.300-fold greater than those for H2O2, and this increase is consistent with expectations based on a Bronsted anal. of the kinetics for other heterolytic peroxide oxidns. At high concns. of H2O2, a pathway that is second order in H2O2 is significant, and this path is interpreted as a general acid catalysis by H2O2 of carbonate displacement accompanying substrate attack at the electrophilic oxygen of HCO4-. Increasing water content up to 80% in the solvent increases the rate of oxidn. The BAP (bicarbonate-activated peroxide) oxidn. system is a simple, inexpensive, and relatively nontoxic alternative to other oxidants and peroxyacids, and it can be used in a variety of oxidns. where a mild, neutral pH oxidant is required. Variation of bicarbonate source and the cosolvent can allow optimization of substrate soly. and oxidn. rates for applications such as org. synthesis and chem. warfare agent decontamination.

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Synthesis and Characterization of a Functionalized Double-Chain Surfactant and Its Cleavage of O-Methyl S-Benzyl Phenylphosphonothioate. Jaeger, David A.; Li, Bei. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (2000), 16(1), 5-10. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 132:24141 AN 1999:379097 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant 2-hydrazino-N-methyl-N,N-didodecyl-2-oxoethanaminium bromide (I) was synthesized, and its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry. In a pH 9.0 borate buffer at 25, vesicular I and O-Me S-benzyl phenylphosphonothioate (II), a simulant for the chem. warfare agent VX [O-Et S-(2-N,N-diisopropylamino)ethyl methylphosphonothioate] reacted to give anion S-benzyl phenylphosphonothioate (III) and 3 cations (2-(2-N-methylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, 2-(2-N,N-dimethylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, and 2-[1-hydroxy-2-(N-methyl-N,N-didodecylammonio)ethylidene]-N',N',N'-trimethylhydrazinium, resp.) by SN2 substitution on the Me group of II. This reaction was accompanied by the pptn. of anion III with surfactant cations, which resulted in wounding/destruction of the vesicles. The combination of vesicle damage and reaction of II suggests the potential of vesicular systems for simultaneous signaling and decontamination of chem. agents. Ester II hydrolyzed in 0.10 M NaOH at 25 to give anions III and O-Me phenylphosphonothioate in a 38:62 ratio, resp.

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Reactivation kinetics of acetylcholinesterase from different species inhibited by highly toxic organophosphates. Worek F; Reiter G; Eyer P; Szinicz L Sanitatsakademie der Bundeswehr, Institut fur Pharmakologie und Toxikologie, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2002 Sep), 76(9), 523-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242610 AN 2002479746 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Standard treatment of poisoning by organophosphates (OP) includes the administration of an antimuscarinic agent, e.g. atropine, and of an acetylcholinesterase (AChE) reactivator (oxime). The presently available oximes, obidoxime and pralidoxime (2-PAM), are considered to be insufficient for highly toxic OPs, e.g. sarin. In the past decades numerous oximes were prepared and tested for their efficacy in OP poisoning, mostly in animal experiments. However, data indicate that the reactivating potency of oximes may be different in humans and animal species, which may hamper the extrapolation of animal data to humans and may pose a problem in the drug licensing of new compounds. In order to provide data for a better evaluation of the reactivating potency of oximes, experiments were undertaken to determine the reactivation rate constants of several oximes with human, rabbit, rat and guinea-pig AChE inhibited by the OPs sarin, cyclosarin and VX. The results show marked differences among the species, depending on the inhibitor and on the oxime, and indicate that the findings from animal experiments need careful evaluation before extrapolating these data to humans.

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Skin toxicokinetics of mustard gas in the guinea pig: effect of hypochlorite and safety aspects. Wormser Uri; Brodsky Berta; Sintov Amnon Faculty of Sciences,The Hebrew University, Edmond Safra Campus, Givat Ram, Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2002 Sep), 76(9), 517-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242609 AN 2002479745 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (SM, mustard gas) is a chemical warfare vesicant that rapidly penetrates the skin due to its hydrophobicity. This study measured the rate of SM disappearance from the skin after topical application of the vesicant. In both fur-covered and hairless animals, the remaining toxicant levels measured 60 min after exposure to undiluted SM were 0.6% and 0.3%, respectively, of the initially applied SM amount. However, SM concentration reached 0.4% of the initial dose 3 h following exposure in female fur-covered guinea pigs. SM quantities extracted from skin of male fur-covered and hairless guinea pigs immediately after 16 min of exposure to SM vapor were 12.2 and 21.8 microg, respectively; levels declined to 1.6 and 1.7 microg at 30 and 15 min following termination of exposure of male fur-covered and hairless guinea pigs, respectively. Three swabbing treatments of undiluted SM-exposed skin with gauze pads soaked in 0.5% hypochlorite caused 68% reduction in skin SM content. Similar findings were obtained when hypochlorite was replaced by water (64% reduction). SM content in the gauze pads was 59, 38 and 25 microg, respectively, for the first, second and third decontamination processes with water. No SM was detected in the gauze pads soaked with hypochlorite. In vitro studies showed that incubation of SM with 0.5% hypochlorite at a ratio of 10:1 (v/v) did not cause SM inactivation, whereas 4% hypochlorite reduced SM levels by 17%. However, at a decontaminant:SM ratio of 1000:1, 0.5% and 4% hypochlorite reduced SM levels by 92% and 99%, respectively. These findings are important for health authorities and regulatory agencies in planning precautionary steps to be taken in case of emergency and in routine laboratory work.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock Shannon D; Till Gerd O; Smith Milton G; Ward Peter A Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602, USA Journal of applied toxicology : JAT (2002 Jul-Aug), 22(4), 257-62. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12210543 AN 2002449749 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The chemical warfare agent analog, 2-chloroethyl ethyl sulfide, known as 'half-mustard gas' (HMG), is less toxic and less of an environmental hazard than the full molecule and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of (125)I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, we observed significant attenuation of the pulmonary injury when experimental animals were complement or neutrophil depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, dimethyl sulfoxide, dimethyl thiourea, resveratrol and N-acetyl-L-cysteine (NAC). The last compound showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement mediated pathways and the generation by neutrophils of toxic oxygen species The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat. Copyright 2002 John Wiley & Sons, Ltd.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber Ellen; McGuire Raymond Environment Protection Department, Lawrence Livermore National Laboratory, University of California, P.O. Box 808, L-626, Livermore, CA 94551, USA Journal of hazardous materials (2002 Aug 5), 93(3), 339-52. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12137994 AN 2002389537 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A decontamination method has been developed using a single reagent that is effective both against chemical warfare (CW) and biological warfare (BW) agents. The new reagent, "L-Gel", consists of an aqueous solution of a mild commercial oxidizer, Oxone, together with a commercial fumed silica gelling agent, Cab-O-Sil EH-5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. The new reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Experiments to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Laboratory and independently at four other locations. L-Gel was tested against all classes of chemical warfare agents and against various biological warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biological agents. Testing showed that L-Gel is as effective against chemical agents and biological materials, including spores, as the best military decontaminants.

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Adamantyl tenocyclidines--adjuvant therapy in poisoning with organophosphorus compounds and carbamates. Erratum in: Arch Toxicol 2002 Sep;76(9):552 Skare Danko; Radic Bozica; Lucic Ana; Peraica Maja; Domijan Ana-Marija; Milkovic-Kraus Sanja; Bradamante Vlasta; Jukic Ivan Institute Ruder Boskovic, Bijenicka c. 54, 10000 Zagreb, Croatia. skare@rudjer.irb.hr Archives of toxicology (2002 Apr), 76(3), 173-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11967623 AN 2002328057 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The objective of this study was to evaluate the efficacy of thienyl phencyclidine (tenocyclidine, TCP) and its newly synthesized adamantyl derivatives containing piperidine (TAPIP), pyrolidine (TAPIR) and morpholine (TAMORF) groups, which were tested with or without standard therapy in mice poisoned with organophosphates (OPs) and carbamates. These compounds with potential activity at the N-methyl- D-aspartate and muscarinic receptors showed low acute toxicity, having LD50 values varying from 106.00 mg/kg (TCP) to >504.00 mg/kg body weight (TAMORF). TCP and its adamantyl derivatives were administered intraperitoneally (2.5 mg/kg body weight) together with atropine (10.0 mg/kg body weight) and with or without 1/4 LD50 of the oxime HI-6. Each compound administered with atropine had a therapeutic effect against poisoning with carbamates propoxur, aldicarb and Ro 02-0683 (protective ratio of tenocyclidines was from 3.99 LD50 of aldicarb to >16.00 LD50 for propoxur). However, the efficacy of those compounds in combination with atropine was lower against poisoning with the OP insecticide dichlorvos (DDVP) and chemical warfare agents soman and tabun. In soman-poisoned mice, the best therapeutic effects were obtained with the combination of HI-6 plus atropine and test compounds, with protective ratios being from 5.40 to 7.12 LD50 of soman. The results suggest that TCP and adamantyl tenocyclidines could be used in combination with atropine as antidotes in carbamate poisoning and as adjuvant therapy to HI-6 and atropine in soman poisoning.

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Site-specific percutaneous absorption of methyl salicylate and VX in domestic swine. Duncan E J Scott; Brown April; Lundy Paul; Sawyer Thomas W; Hamilton Murray; Hill Ira; Conley John D Chemical Biological Defence Section, Defence Research Establishment, Suffield, PO Box 4000, Station Main, Medicine Hat, Alberta, Canada T1A 8K6 Journal of applied toxicology : JAT (2002 May-Jun), 22(3), 141-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12015792 AN 2002313565 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The site specificity of the percutaneous absorption of methyl salicylate (MeS) and the organophosphate nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) was examined in anaesthetized domestic swine that were fully instrumented for physiological endpoints. Four different anatomical sites (ear, perineum, inguinal crease and epigastrium) were exposed to the MeS and the serum levels were measured over a 6-h time period. The dose absorbed at the ear region was 11 microg cm(-2) with an initial flux of 0.063 microg cm(-2)min(-1), whereas at the epigastrium region the dose absorbed was 3 microg cm(-2) with an initial flux of 0.025 microg cm(-2)min(-1). For this reason further studies were carried out with VX on the ear and the epigastrium only. In animals treated with agent on the epigastrium, blood cholinesterase (ChE) activity began to drop 90 min after application and continued to decline at a constant rate for the remainder of the experiment to ca. 25% of awake control activity. At this time there were negligible signs of poisoning and the medical prognosis was judged to be good. In contrast, the ChE activity in animals receiving VX on the ear decreased to 25% of awake control values within 45 min and levelled out at 5-6% by 120 min. Clinical signs of VX poisoning paralleled the ChE inhibition, progressing in severity over the duration of the exposure. It was judged that these animals would not survive. The dramatic site dependence of agent absorption leading to vastly different toxicological endpoints demonstrated in this model system has important ramifications for chemical protective suit development, threat assessment, medical countermeasures and contamination control protocols. Copyright 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

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An improved brain slice model of nerve agent-induced seizure activity. Wood S J; Tattersall J E Biomedical Sciences Department, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S83-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920926 AN 2002191151 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice preparation. Soman (1 microM) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists, but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice preparation is a suitable model for investigating the origin and propagation of nerve-agent-induced seizures within the limbic system. Copyright 2001 John Wiley & Sons, Ltd.

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Cardiopulmonary effects of HI-6 treatment in soman intoxication. Goransson-Nyberg A; Cassel G Division of NBC Defence, Department of Medical Counter Measures, Swedish Defence Research Agency, SE-90182 Umea, Sweden Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S79-81. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920925 AN 2002191150 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The cardiopulmonary effects of HI-6, together with atropine and soman, were studied in the rat. HI-6 is an effective antidote in acute poisoning with the nerve agent soman. The therapeutic efficiency of HI-6 is still unclear and cannot be explained entirely by the HI-6 reactivating ability of acetylcholinesterase (AChE). Other non-cholinergic factors must be involved. One possible detoxifying process might be an effect of HI-6 on the blood flow to sensitive organs. The purpose of the present study was to investigate 1) whether soman per se induces changes in regional blood flow and 2) whether the blood flow to different organs is affected when HI-6 (50 mg x kg(-1) i.m.) and atropine (10 mg x kg(-1) i.m.) are given either before or immediately after soman intoxication (90 microg x kg(-1) s.c.). For regional blood flow determinations the microsphere method was used with male Wistar rats weighing 300-400 g. The rats were anaesthetised and breathed spontaneously during the experiment. Three different blood flow measurements were made in the same animal and concomitant physiological parameters such as mean arterial blood pressure and respiratory rate were recorded. The blood AChE activity was followed throughout the experiment. Our results show that when HI-6 is given after intoxication with soman, dramatic changes in blood flow occur with a significant decrease in both respiratory rate and blood AChE activity. If HI-6 is given prior to the intoxication, however, all rats are unaffected and none of the parameters measured are changed. Copyright 2001 John Wiley & Sons, Ltd.

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Prophylaxis against organophosphate poisoning by sustained release of scopolamine and physostigmine. Meshulam Y; Cohen G; Chapman S; Alkalai D; Levy A Department of Pharmacology, Israel Institute for Biological Research (IIBR), PO Box 19, 70450 Ness-Ziona, Israel Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S75-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920924 AN 2002191149 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Protection efficacy of continuous prophylactic administration of physostigmine and scopolamine against sarin-induced toxicity was evaluated previously in guinea pigs. The present study in large animals used Beagle dogs, that serve as an animal model with cholinergic sensitivity similar to that of humans. Pretreatment with physostigmine salicylate and scopolamine hydrochloride at dose rates of 2.5 and 1 microg x kg(-1) x h(-1), respectively, was administered via Alzet mini-osmotic pumps. At the time of exposure, the physostigmine salicylate concentration in plasma was 0.7 ng x ml(-1) and the scopolamine hydrochloride concentration was ca. 0.2 ng x ml(-1), both of which are levels known to be well tolerated in humans. Whole-blood cholinesterase inhibition was 15-20%. This regimen conferred full protection against 2.5 x LD50 i.v. of sarin. Albeit the high-dose exposure, cholinergic toxicity symptoms were mild with no convulsions. About 11-14 min following poisoning the treated animals started to walk and 15-20 min following exposure full recovery was observed and the dogs behaved normally. With higher dose rates of physostigmine salicylate and scopolamine hydrochloride, at plasma concentrations of 2.1 and 0.6 ng x ml(-1), respectively, treated dogs regained normal posture 6-10 min after exposure. Copyright 2001 John Wiley & Sons, Ltd.

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Intramuscular diazepam pharmacokinetics in soman-exposed guinea pigs. Capacio B R; Whalley C E; Byers C E; McDonough J H Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S67-74. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920923 AN 2002191148 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Intramuscular (i.m.) diazepam is included by the US military as an anticonvulsant in the standard therapeutic regimen for organophosphorus nerve agent intoxication. In this study we investigated the pharmacokinetics of diazepam after i.m. administration while monitoring pharmacodynamic (electroencephalogram, EEG) data in soman-exposed guinea pigs. Prior to experiments the animals were surgically implanted with EEG leads to monitor seizure activity. For the study, animals were administered pyridostigmine (0.026 mg x kg(-1) i.m.) 30 min prior to soman (56 microg x kg(-1), 2 x LD50; subcutaneously, s.c.), which was followed in 1 min by atropine sulfate (2 mg x kg(-1) i.m.) and pralidoxime chloride (25 mg x kg(-1) i.m.). All animals receiving this regimen developed seizure activity. Diazepam (10 mg x kg(-1) i.m.) was administered 5 min after onset of seizure activity. Based on EEG data, animals were categorized as either seizure terminated or not terminated at 30 min after diazepam. Serial blood samples were obtained from each animal. Diazepam (10 mg x kg(-1) i.m.) terminated seizure activity in 52% of the animals within 30 min. The pharmacokinetics were characterized by a one-compartment model with first-order absorption and elimination. The maximum plasma concentrations (Cmax) were 991 and 839 ng x ml(-1) for seizure terminated and not terminated, respectively. Mean plasma concentrations of diazepam were significantly different (P < 0.05) for seizure terminated vs not terminated groups at 30 min. The plasma Cmax in seizure-terminated animals in this study is similar to the minimum range of plasma diazepam (200-800 ng x ml(-1)) reported to suppress seizure activity in humans. It has been reported in an earlier study that the minimum effective i.m. dose (0.1 mg x kg(-1)) required to prevent soman-induced convulsions in Rhesus monkeys produces a mean Cmax of 50 ng x ml(-1) for diazepam.
The data from our current study suggest that a higher dose (and corresponding Cmax) is necessary to terminate ongoing seizure activity. Copyright 2001 John Wiley & Sons, Ltd.

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Combination anticonvulsant treatment of soman-induced seizures. Koplovitz I; Schulz S; Shutz M; Railer R; Macalalag R; Schons M; McDonough J Drug Assessment Division, US Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010, USA. Koplovitz@asia.apgea.army.mil Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S53-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920921 AN 2002191147 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures. Copyright 2001 John Wiley & Sons, Ltd.

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Soman-induced seizures: limbic activity, oxidative stress and neuroprotective proteins. Pazdernik T L; Emerson M R; Cross R; Nelson S R; Samson F E Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City, KS 66160, USA. tpazdern@kumc.edu Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S87-94. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920927 AN 2002185330 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman, a potent acetylcholinesterase inhibitor, induces status epilepticus in rats followed by conspicuous neuropathology, most prominent in piriform cortex and the CA3 region of the hippocampus. Cholinergic seizures originate in striatal-nigral pathways and with fast-acting agents (soman) rapidly spread to limbic related areas and finally culminate in a full-blown status epilepticus. This leads to neurochemical changes, some of which may be neuroprotective whereas others may cause brain damage. Pretreatment with lithium sensitizes the brain to cholinergic seizures. Likewise, other agents that increase limbic hyperactivity may sensitize the brain to cholinergic agents. The hyperactivity associated with the seizure state leads to an increase in intracellular calcium, cellular edema and metal delocalization producing an oxidative stress. These changes induce the synthesis of stress-related proteins such as heat shock proteins, metallothioneins and heme oxygenases. We show that soman-induced seizures cause a depletion in tissue glutathione and an increase in tissue 'catalytic' iron, metallothioneins and heme oxygenase-1. The oxidative stress induces the synthesis of stress-related proteins, which are indicators of 'stress' and possibly provide neuroprotection. These findings suggest that delocalization of iron may catalyze Fenton-like reactions, causing progressive cellular damage via free radical products. Copyright 2001 John Wiley & Sons, Ltd.

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Beneficial effects of TCP on soman intoxication in guinea pigs: seizures, brain damage and learning behaviour. de Groot D M; Bierman E P; Bruijnzeel P L; Carpentier P; Kulig B M; Lallement G; Melchers B P; Philippens I H; van Huygevoort A H TNO Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S57-65. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920922 AN 2002185328 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Poisoning with the potent nerve agent soman produces a cascade of central nervous system (CNS) effects characterized by severe convulsions and eventually death. In animals that survive a soman intoxication, lesions in the amygdala, piriform cortex, hippocampus and thalamus can be observed. In order to examine the mechanisms involved in the effects of soman and to evaluate possible curative interventions, a series of behavioural, electrophysiological and neuropathological experiments were carried out in the guinea pig using the NMDA antagonist N-[1-(2-thienyl)cyclohexyl] piperidine (TCP) in conjunction with atropine and pyridostigmine. The NMDA antagonist TCP appeared to be very effective in the treatment of casualties who suffered from soman-induced seizures for 30 min: (i)Seizures were arrested within minutes after the TCP injection, confirmed by quantitative electroencephalogram (EEG), after fast Fourier analysis. Three hours after TCP the quantitative EEGs were completely normal in all frequency bands and remained normal during the entire 3-week intoxication period. The power shift to the lower (delta) frequency bands, indicative for neuropathology and found in control animals intoxicated only by soman, was not observed in the soman-TCP group. (ii)The gross neuropathology found in soman control animals within 48 h after soman was prevented in soman-TCP animals and was still absent in 3-week survivors. Instead, ultrastructural changes were observed, indicative of defense mechanisms of the cell against toxic circumstances. (iii)Twenty-four hours after soman, soman-TCP animals were able to perform in the shuttle box and Morris water maze. The beneficial effects of TCP on the performance in these tests during the 3-week intoxication period were very impressive, notwithstanding (minor) deficits in memory and learning. (iv)The increase in excitability after TCP was confirmed by an increase in the acoustic startle response.
Taken together, these results confirmed the involvement of NMDA receptors in the maintenance of soman-induced seizures and the development of brain damage. They underline the current hypothesis that cholinergic mechanisms are responsible for eliciting seizure activity after soman and that, most likely, the subsequent recruitment of other excitatory neurotransmitters and loss of inhibitory control are responsible for the maintenance of seizures and the development of subsequent brain damage. Copyright 2001 John Wiley & Sons, Ltd.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw M D; Hayes T L; Miller T L; Shannon C M Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH 43201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S3-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920912 AN 2002185325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate--a V-type nerve agent developed by the former Soviet Union--in the environment is an important parameter in threat assessment analysis and for the determination of use, production, testing and storage of this chemical warfare agent. S-(N,N-Diethylaminoethyl) isobutyl methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same molecular formula, it is expected that their physical and chemical properties would be different. This preliminary investigation was undertaken to determine the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compound at approximately 1 mg x ml(-1) in unbuffered water at pH 7 was determined side-by-side. The half-lives for VXA and VX were determined to be 12.4 days and 4.78 days, respectively. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chemical Weapons Convention. Copyright 2001 John Wiley & Sons, Ltd.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller J K; Lenz D E Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD 21201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S23-6. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920916 AN 2002185323 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-molecular-weight compounds is effected by the use of chromatographic techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the analysis. To overcome those drawbacks, we have been involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds such as pinacolylmethyl phosphonofluoridate (soman), which is a chemical warfare agent. Prior estimates suggested that it is necessary to be able to detect soman at a concentration below 2.5 x 10(-7) M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The minimum required assay time was 2.0-2.5 h with no loss in sensitivity. To determine the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogues were 5 x 10(-7) M for 4-nitrophenylpinacolylmethylphosphonate, 8 x 10(-7) M for dipinacolylmethylphosphonate, 2 x 10(-6) M for diisopropylmethylphosphonate, 3 x 10(-5) M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5 x 10(-5) M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman molecule, were effective inhibitors. Compounds, which contained predominately aromatic groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to determine its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman. Copyright 2001 John Wiley & Sons, Ltd.

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Protective action of the serine protease inhibitor N-tosyl-L-lysine chloromethyl ketone (TLCK) against acute soman poisoning. Cowan F M; Broomfield C A; Lenz D E; Shih T M Biochemical Pharmacology and Neurotoxicology Branches, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 293-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481662 AN 2002027826 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman-poisoned rats display cholinergic crisis, a systemic mast cell degranulation characteristic of anaphylactic reactions and an excitotoxin-like sequential seizure and neuronal degeneration. The protection of guinea pigs from soman lethality by prophylactic administration of the serine protease inhibitor suramin suggests a possible proteolytic component in soman poisoning. The present study tested the effect of N-tosyl-L-lysine chloromethyl ketone (TLCK), an inhibitor of trypsin-like serine proteases, on soman-induced toxic signs (convulsions, righting reflex) and survival time. Nine control guinea pigs receiving 2 x LD(50) (56 microg kg(-1), s.c.) of soman immediately followed by a therapeutic dose of atropine sulfate (17.4 mg kg(-1) i.m.) experienced severe convulsions, and 8/9 lost the righting reflex. Six of these nine animals expired within 65 min; the three remaining animals survived 24 h to termination of the experiment. When a second group of animals were given TLCK (12 mg kg(-1), i.p.) 30 min prior to a 2 x LD(50) soman challenge and atropine-sulfate therapy, 5/9 experienced convulsions and only 3/9 lost the righting reflex. All nine animals survived beyond 4 h, with six surviving to 24 h. Compared with soman controls, prophylaxis with TLCK significantly prevented the loss of righting reflex (P = 0.05) and enhanced 4-h survival (P = 0.005). Although, convulsions were reduced and 24-h survival was improved in TLCK-treated animals, these results were not statistically significant. The protection from soman toxicity by chemically distinct protease inhibitors such as suramin and TLCK suggests a role for pathological proteolytic pathways in soman intoxication. Copyright 2001 John Wiley & Sons, Ltd.

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin. Chilcott R P; Jenner J; Hotchkiss S A; Rice P Department of Biomedical Sciences, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 279-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481660 AN 2002027824 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption. Copyright 2001 John Wiley & Sons, Ltd.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen J; Riikonen K; Nikmo J; Jappinen A; Nieminen K Air Quality Research, Finnish Meteorological Institute, Sahaajankatu 20 E, FIN-00810, Helsinki, Finland. jaakko.kukkonen@fmi.fi Journal of hazardous materials (2001 Aug 17), 85(3), 165-79. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11489522 AN 2001443815 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

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Effects of iodine on inducible nitric oxide synthase and cyclooxygenase-2 expression in sulfur mustard-induced skin. Nyska A; Lomnitski L; Maronpot R; Moomaw C; Brodsky B; Sintov A; Wormser U Laboratory of Experimental Pathology, National Institutes of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA. nyska@niehs.nih.gov Archives of toxicology (2001 Feb), 74(12), 768-74. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11305779 AN 2001394179 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

In a previous study we demonstrated the protective effect of topical iodine as postexposure treatment for sulfur mustard (SM) application. The iodine treatment results in significantly reduced inflammation and necrosis and increased epidermal hyperplasia. The expression and localization of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in paraffin-embedded skin samples from that study were evaluated in the present investigation. We compared the immunoreactivity of iNOS and COX-2 using five samples from each of the following four test sites: untreated control sites, SM-exposed sites, sites treated with iodine mixture 15 min after SM exposure, and sites treated with iodine 30 min after SM exposure. All animals were killed 2 days after irritant exposure. iNOS immunoreactivity was present only in skin sites exposed to SM without iodine treatment. The ulcerated skin was covered with a relatively thick band of exudate composed of iNOS-immunostained polymorphonuclear cells and macrophages. In untreated skin, COX-2 immunostaining was limited to the thin suprabasal epidermal layer. In SM-exposed skin, induction of COX-2 was noted in inflammatory cells located close to the site of epidermal injury. In skin sites treated with iodine 15 or 30 min after SM exposure, the regenerating hyperplastic epithelium showed moderate cytoplasmic staining localized to the epithelium overlying the basal layer. This pattern of staining was also present in the nearby dermal fibroblasts. Thus, in contrast to the skin samples exposed to SM without iodine treatment, the epidermal layer expressing immunohistochemical positivity for COX-2 was thicker and corresponded to the epidermal hyperplasia noted in samples treated with iodine. It is well documented that prostaglandins (PGs) promote epidermal proliferation, thereby contributing to the repair of injured skin. That the induction of the COX-2 shown in our study may also play a role in the healing process is indicated by the present evidence.
The results suggest that nitric oxide radicals (NO*) are involved in mediating the damage induced by the SM and that iodine-related reduction in acute epidermal inflammation is associated with reduced iNOS expression.

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Intervention of sulfur mustard toxicity by downregulation of cell proliferation and metabolic rates. Ray R; Benton B J; Anderson D R; Byers S L; Petrali J P US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. radharaman.ray@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S87-91. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428650 AN 2001371709 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chemical warfare compound HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37 degrees C) first in keratinocyte growth medium (KGM) containing BAPTA AM (10-40 microM) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concentration-dependent manner with some cellular degeneration above 30 microM (light microscopy). At 20-30 microM, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 54 +/- 5%), [3H]-uridine (RNA synthesis, 29 +/- 6%) and [14C]-valine (protein synthesis, 12 +/- 2%) as well as a lower protein content per culture (30 +/- 3%) compared with corresponding untreated controls. However, 20-30 microM BAPTA AM did not cause any demonstrable cytopathology based on morphological (electron microscopy) as well as biochemical (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser J; Meier H L Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S23-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428638 AN 2001371697 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chemical warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compounds in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell preparations were exposed to various concentrations of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these experiments suggest that, with increasing HD concentration and time, NHEK will fragment irrespective of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains constant over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concentration- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, respectively, is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concentrations that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price E O; Smith J R; Clark C R; Schlager J J; Shih M L Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S193-7. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428636 AN 2001371695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The continual threat of chemical and biological warfare has prompted the need for unambiguous analytical methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with hemoglobin and metallothioneine were conducted. In vitro experiments with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to determine the extent of alkylation and occurrence of HD cross-linking using the MALDI-ToF/MS technique. In a typical experiment, 50 ml of 5 mM HD in acetonitrile was added to an equal volume of 0.5 mM hemoglobin in deionized water followed by vortexing and incubation at room temperature. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES experiments. These results demonstrate that MALDI-ToF/MS is a useful analytical technique to investigate the interaction of HD with biomolecules and may be employed potentially as a diagnostic tool for the confirmation of exposure to chemical warfare agents.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers S; Anderson D; Brobst D; Cowan F Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S19-22. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428635 AN 2001371694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham J S; Reid F M; Smith J R; Stotts R R; Tucker E S; Shumaker S M; Niemuth N A; Janny S J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S161-72. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428630 AN 2001371689 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chemical warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clinical pathology findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liquid on the ventral surface for 2 h, generating six 3-cm diameter full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematology and serum chemistry examinations. Urine was collected in metabolism cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatography/mass spectrometry. Examination of clinical pathology parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clinically significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 microg ml(-1) with a mean of 2.14 microg ml(-1). Thiodiglycol concentrations were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml(-1). Mean levels remained 10-40 ng ml(-1) for the remainder of the 7-day observation period, with the highest individual concentration noted during this period of 132 ng ml(-1). Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other laboratory animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 week.
Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h. Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin M C; Ricketts K; Skvorak J P; Gazaway M; Mitcheltree L W; Casillas R P Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA. Michael.Babin@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S141-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428627 AN 2001371686 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quantitative edema response as well as histopathological and biochemical endpoints as measurements of inflammation and tissue damage following exposure to the chemical warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal separation. This study evaluated the protective effects of three of these pharmacological compounds when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver a subcutaneous dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 microl of a 195 mM (0.16 mg) solution of sulfur mustard (density = 1.27 g ml(-1); MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathological damage (necrosis, epidermal-dermal separation). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant reduction in edema (24%, 26% and 22%, respectively) from the positive control. Compared to HD-positive controls, hydrocortisone, indomethacin and olvanil caused a significant reduction in subepidermal blisters (71%, 52% and 57%, respectively) whereas only hydrocortisone produced a significant reduction in contralateral epidermal necrosis (41%). We show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins K B; Lodhi I J; Hurley L L; Hinshaw D B University of Michigan Medical School, Ann Arbor 48105, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S125-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428622 AN 2001371681 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chemical warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells (Toxicol. Appl. Pharmacol. 1996; 141: 568-583). Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFkappaB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFkappaB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 microM HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 microM buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 microM HD for 5-6 h. Externally applied GSH up to a concentration of 5 mM had no toxic effect on the cells. Mild toxicity was associated with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examined the hypothesis that HD may activate the nuclear transcription factor NFkappaB by performing EMSAs with nuclear extracts of endothelial cells following exposure to 0, 250 or 500 microM HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFkappaB binding to its consensus sequence induced by 500 microM HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFkappaB, although HD-induced activation of NFkappaB was partially suppressed by NAC at 5 h. Factor NFkappaB is an important transcription factor for a number of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFkappaB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFkappaB activity. The NFkappaB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction associated with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha M; Bowers W Jr; Kohl J; DuBose D; Walker J; Alkhyyat A; Wong G US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S101-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428619 AN 2001371678 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chemical warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl ethyl sulfide (CEES, 1-2 mg l(-1) min(-1)) in humidified air or to humidified air alone. Tissues were evaluated histologically, ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histology showed that CEES induced the separation of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histology and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1alpha (IL-1alpha), prostaglandin-E2 (PGE2) and especially IL-1 receptor antagonist (IL-1Ra) release (56,334 vs 84,614 pg ml(-1)), but decreased interleukin-6 (IL-6, 4,755 vs 351 pg ml(-1)). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracelluar IL-1alpha (371 vs 92 pg ml(-1)). Extracellular IL-1Ra greatly increased (2,375 vs 24,875 pg ml(-1)), whereas cellular levels decreased (16,5425 vs 96,625 pg ml(-1)). Extracellular (224 vs 68 pg ml(-1)) and intracellular (485 vs 233 pg ml(-1)) soluble interleukin-1 receptor H (sIL-1RII) decreased. Prostanglandin E2 increased (1,835 vs 2,582 pg ml(-1)), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57,000 vs 96,000 pg ml(-1)). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Correlation of a specific mitochondrial phospholipid-phosgene adduct with chloroform acute toxicity. Di Consiglio E; De Angelis G; Testai E; Vittozzi L Biochemical Toxicology Unit, Department of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita, Viale Regina Elena 299, I-00161, Rome, Italy Toxicology (2001 Feb 21), 159(1-2), 43-53. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11250054 AN 2001195862 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The dose and time dependence of formation of a specific adduct between mitochondrial phospholipid and phosgene have been determined in the liver of Sprague-Dawley (SD) rats as well as in the liver and kidney of B6C3F1 mice after dosing with chloroform. Rats were induced with phenobarbital or non-induced. Determination of tissue glutathione (GSH) and of serum markers of hepatotoxicity and nephrotoxicity was also carried out. With dose-dependence experiments, a strong correlation between the formation of the specific phospholipid adduct, GSH depletion and organ toxicity could be evidenced in all the organs studied. With non-induced SD rats, no such effects could be induced up to a dose of 740 mg/kg. Time-course studies with B6C3F1 mice indicated that the specific adduct formation took place at very early times after chloroform dosing and was concurrent with GSH depletion. The adduct formed during even transient GSH depletion (residual level: 30% of control) and persisted after restoration of GSH levels. Following a chloroform dose at the hepatotoxicity threshold (150 mg/kg), the elimination of the adduct in the liver occurred within 24 h and correlated with the recovery of ALT, which was slightly increased (12 times) after treatment. Following a moderately nephrotoxic dose (60 mg/kg), the renal adduct persisted longer than 48 h, when a 100% increase in blood urea nitrogen and a 40% increase in serum creatinine indicated the onset of organ damage. The formation of the adduct in the liver mitochondria of B6C3F1 mice was associated with the decrease of phosphatidyl-ethanolamine (PE), in line with previous results in rat liver indicating that the adduct results from the reaction of phosgene with PE. The adduct levels implicated the reaction of phosgene with about 50% PE molecules in the liver mitochondrial membrane of phenobarbital-induced SD rats and of about 10% PE molecules of the inner mitochondrial membrane of the liver of B6C3F1 mice.
The association of this adduct with the toxic effects of chloroform makes it a very good candidate as the primary critical alteration in the sequence of events leading to cell death caused by chloroform.

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The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats. Kassa J; Fusek J Purkyne Military Medical Academy, PO Box 35/T, 500 01, Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2000 Nov 23), 154(1-3), 67-73. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11118671 AN 2001083637 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.

[megalomania]

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Development of multifunctional perfluorinated polymer blends as an active barrier cream against chemical warfare agents. Hobson, Stephen T.; Braue, Ernest H., Jr. Drug Assessment Div., U.S. Army Medical Research Institute for Chemical Defense, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 80-81. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:363990 AN 2003:381106 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare agents (CWA's) represent a real and growing threat both to U.S. armed forces as well as to civilians. Within the last three decades, chem. weapons have been used by the Soviets in Cambodia (yellow rain, tricothecene mycotoxins), by Iraq against Iran (HD and tabun), and by Iraq against its own dissident Kurdish population at Halabja (H-ID HCN0). In the United States' experience in World War I, almost one-third of hospitalized casualties were a result of CWA's. Furthermore, the 1000 casualties and 12 deaths resulting from the 1995 terrorist use of sarin (GB) in Tokyo show that civilians have also become targets. In this paper we focus on protection against two classes of CWA's: nerve agents (soman, GD) and blister agents (sulfur mustard, HD). Protection against these agents in the United States Army consists of a chem. resistant outer layer of clothing (BDO) and protective mask (M40). This scheme of protection allows operation in a chem. contaminated area but results in decreased performance and increased heat retention. We have investigated a material that serves as a phys. barrier to CWA's and contains an active moiety to neutralize hazardous chems. This Active Topical Skin Protectant (aTSP) would be used in conjunction with other protective procedures. Herein we report the prepn., characterization, and evaluation of aTSP's.

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Molecularly imprinted polymers for the detection of chemical agents in water. Jenkins, Amanda L.; Yin, Ray; Jensen, Janet L.; Durst, H. Dupont. US Army Research Laboratory, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 76-77. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:343335 AN 2003:381101 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molecularly imprinted polymers contg. Eu3+ were prepd. using a no. of pesticides and pinacolyl methylphosphonate (hydrolysis product of the nerve agent Soman), and sensors were fabricated by coating the polymers on optical fibers. The sensors were characterized in terms of sensitivity, selectivity, response time, adaptability, and portability; they provided detection limits in the low parts per trillion.

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Synthesis of carbon-coated MgO nanoparticles. Bedilo, Alexander F.; Sigel, M. Jake; Koper, Olga B.; Melgunov, Maxim S.; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2002), 12(12), 3599-3604. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 138:174329 AN 2002:910661 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Carbon-coated MgO nanoparticles, with carbon forming a porous coating on the surface of MgO nanoparticles, have been prepd. by two different techniques. Resorcinol has been found to be an efficient agent for the modification of magnesium methoxide leading to carbon-coated MgO nanocrystals of small crystallite size and high surface area. Decompn. of dry magnesium methoxide under an inert gas flow proved to be another efficient and economical way to synthesize carbon-coated MgO. The carbon coating acts as a hydrophobic barrier partially protecting the core metal oxide from water adsorption and conversion to magnesium hydroxide. However, destructive adsorption reactions can still proceed on the metal oxide surface, as evidenced by the dehydrochlorination of 2-chloroethyl Et sulfide (2-CEES) and 1-chlorobutane. The overall stability of the material in the presence of water vapor is significantly improved in comparison with non-coated nanocryst. MgO.

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Micellar Effects on Hypochlorite Catalyzed Decontamination of Toxic Phosphorus Esters. Dubey, D. K.; Gupta, A. K.; Sharma, Mamta; Prabha, S.; Vaidyanathaswamy, R. Defence R and D Establishment, Gwalior, India. Langmuir (2002), 18(26), 10489-10492. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 138:94789 AN 2002:866089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At pH 8.5, the surfactant N,N,N-trimethyl-1-hexadecanaminium bromide (I) increased the pseudo-first-order rate consts. of hypochlorite-catalyzed hydrolysis of the sarin model compd. p-nitrophenyl di-Ph phosphate by 300 times and that of the toxic p-nitrophenyl iso-Pr methylphosphonate by 20 times, and the nerve agent sarin itself was completely decontaminated within 10 min at a sarin-hypochlorite ratio of 20:1 in a micellar I-hypochlorite mixt. In the absence of surfactant , it takes >70 min to detoxify sarin, even at a 10 times higher concn. of hypochlorite.

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A Comparative Study of the Adsorption of Chloro- and Non-Chloro-Containing Organophosphorus Compounds on WO3. Kanan, Sofian M.; Lu, Zhixiang; Tripp, Carl P. Laboratory for Surface Science Technology and Department of Chemistry, University of Maine, Orono, ME, USA. Journal of Physical Chemistry B (2002), 106(37), 9576-9580. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 137:253624 AN 2002:620746 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The adsorption of di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), and methyldichlorophosphate (MDCP) on monoclinic tungsten oxide (m-WO3) evacuated at various temps. was investigated using IR spectroscopy. DMMP is the most common mol. used for evaluating the performance of WO3 and other semiconducting metal oxide (SMO)-based sensors to phosphonate-based nerve agents. However, toxic nerve agents such as sarin differ from DMMP in that they contain a functional group (P-F in sarin) that can be readily hydrolyzed. It is shown that the adsorption of organophosphates that contain P-Cl groups differs from nonhalogenated simulants such as DMMP and TMP on WO3 surfaces. Specifically, the non-chlorinated simulants DMMP and TMP adsorb on the surface solely through the P:O functionality with the surface water layer as well as the Lewis and Bronsted acid sites. The relative no. of mols. bound on Lewis and Bronsted acid surface sites depends on the initial evacuation temp. of the WO3 surface. When MDCP adsorbs on WO3 through the P:O bond, it is accompanied by the hydrolysis of P-Cl groups by water vapor or the adsorbed water layer leading to addnl. phosphate-like species on the surface. The IR data suggests that a halogenated phosphate like MDCP is a better simulant mol. for studies aimed at understanding the role of water and hydrolysis in the response of metal oxide-based sensors to nerve agents.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock, Shannon D.; Till, Gerd O.; Smith, Milton G.; Ward, Peter A. Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2002), 22(4), 257-262. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 137:151235 AN 2002:596130 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. warfare agent analog, 2-chloroethyl Et sulfide, known as half-mustard gas (HMG), is less toxic and less of an environmental hazard than the full mol. and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of 125I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, the authors obsd. significant attenuation of the pulmonary injury when exptl. animals were complement- or neutrophil-depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, DMSO, dimethylthiourea, Resveratrol, and N-acetyl-L-cysteine (NAC). The last compd. showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement-mediated pathways and the generation by neutrophils of toxic oxygen species. The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber, Ellen; McGuire, Raymond. Lawrence Livermore National Laboratory, Environment Protection Department, University of California, Livermore, CA, USA. Journal of Hazardous Materials (2002), 93(3), 339-352. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 137:374412 AN 2002:558690 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A decontamination method was developed using a single reagent that is effective both against chem. warfare (CW) and biol. warfare (BW) agents. The new reagent, L-Gel, consists of an aq. soln. of a mild com. oxidizer, Oxone, together with a com. fumed silica gelling agent, Cab-O-Sil EH 5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. This reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Expts. to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Lab. and independently at 4 other locations. L-Gel was tested against all classes of chem. warfare agents and against various biol. warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biol. agents. Testing showed that L-Gel is as effective against chem. agents and biol. materials, including spores, as the best military decontaminants.

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Synthesis, Characterization, and Adsorption Studies of Nanocrystalline Aluminum Oxide and a Bimetallic Nanocrystalline Aluminum Oxide/Magnesium Oxide. Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J.; Bonevich, John. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry of Materials (2002), 14(7), 2922-2929. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 137:128541 AN 2002:469813 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of Al2O3 and Al2O3/MgO have been produced by a modified aerogel synthesis involving the corresponding aluminum tri-tert-butoxide, magnesium methoxide, toluene, methanol, ethanol, and water. The resulting oxides are in the form of powders having crystallites of .ltorsim.2 nm. These crystallites have been studied by TEM and BET methods, and were found to possess high surface areas and pore vols. (800 m2/g for Al2O3 and 790 m2/g for Al2O3/MgO, compared to 450 m2/g for MgO). As seen with other metal oxides, once they are produced as nanoparticles, their reactivity is greatly enhanced on a per unit surface area basis. This is thought to be due to morphol. differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites possess much higher surface concn. of such sites per unit surface area. Elemental anal., X-ray diffraction, and IR spectroscopy have been used to characterize these nanoparticles, and reactions with CCl4, SO2, and Paraoxon have demonstrated significantly enhanced reactivity and/or capacity compared with common com. forms of the oxide powders. A significant feature is that, by a cogellation synthesis, Al2O3 and MgO have been intermingled, which engenders enhanced reactivity/capacity over the pure forms of nanoscale Al2O3 or MgO toward a chem. warfare surrogate (Paraoxon) and an acid gas (SO2). This serves as an example where tailored synthesis of a nanostructured formulation can yield special benefits.

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Nanocrystalline metal oxides as destructive adsorbents for organophosphorus compounds at ambient temperatures. Rajagopalan, Shyamala; Koper, Olga; Decker, Shawn; Klabunde, Kenneth J. Nanoscale Materials, Inc., Manhattan, KS, USA. Chemistry--A European Journal (2002), 8(11), 2602-2607. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 137:191092 AN 2002:451335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of magnesium oxide react with organophosphorus compds. at room temp. by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant mol. fragments. These ultrafine powders have unusual cryst. shapes and possess high surface concns. of reactive edge/corner and defect sites, and thereby display higher surface reactivity, normalized for surface area, than typical polycryst. material. This high surface reactivity coupled with high surface area allows their use for effective decontamination of chem. warfare agents and related toxic substances. Herein data is presented for paraoxon, diisopropylfluorophosphate (DFP), and (CH3CH2O)2P(O)CH2SC6H5 (DEPTMP). Solid-state NMR and IR spectroscopy indicate that all OR and F groups dissoc.; this leaves bound -PO4, -F, and -OR groups for paraoxon, DFP, and DEPTMP, resp. For paraoxon, it was shown that one monolayer reacts. For DEPTMP, the OR groups dissoc., but not the P-CH2SC6H5 group. The nanocryst. MgO reacts much faster and in higher capacity than typical activated carbon samples, which physisorb but do not destructively adsorb these phosphorous compds.

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Routes of photocatalytic destruction of chemical warfare agent simulants. Vorontsov, Alexandre V.; Davydov, Lev; Reddy, Ettireddy P.; Lion, Claude; Savinov, Eugenii N.; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russia. New Journal of Chemistry (2002), 26(6), 732-744. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 137:236738 AN 2002:427511 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Selected imitants of chem. warfare agents such as di-Me methylphosphonate (DMMP), di-Et phosphoramidate (DEPA), pinacolyl methylphosphonate (PMP), and butylaminoethanethiol (BAET) were subjected to photocatalytic and sonophotocatalytic treatment in aq. suspensions of TiO2. Complete conversion of the same mass of imitants to inorg. products was obtained within 600 min for DMMP, DEPA, PMP, but required a longer time for BAET. Sonolysis accelerated photodegrdn. of DMMP. No degrdn. was obsd. without UV illumination. Final products of degrdn. were PO43-, CO2 for DMMP and PMP, PO43-, NO3- (25%), NH4+ (75%), CO2 for DEPA, and SO42-, NH4+, CO2 for BAET. The no. of main detected intermediate products increases in the order DMMP (7), DEPA (9), PMP (21), and exceeds 34 for BAET. Degrdn. of DMMP mainly proceeds through consecutive oxidn. of methoxy groups and then the Me group. Di-Me hydroxymethylphosphonate and dimethylphosphate testify to the parallel oxidn. of the Me group. Destruction of DEPA mainly starts with cleavage of the P-NH2 bond to form di-Et phosphate, which transforms further into Et phosphate. Oxidn. of  and  carbons of ethoxy groups to form ethylphosphonoamidate, hydroxyethyl ethylphosphonoamidate and other products also contributes to the destruction. Photocatalytic degrdn. of PMP mainly starts with oxidn. of the pinacolyl fragment, methylphosphonic acid and acetone being the major products. Oxidn. of BAET begins with dark dimerization to disulfide, which undergoes oxidn. of sulfur forming sulfinic and sulfonic acids as well as oxidn. of carbons to form butanal, aminobutane, etc., and cyclic products such as 2-propylthiazole. A scheme of degrdn. was proposed for DMMP and DEPA, and starting routes for PMP and BAET. Quantum efficiencies of complete mineralization calcd. as reaction rate to photon flux ratio approx. 10-3%.

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Solvent Effects on the Heterogeneous Adsorption and Reactions of (2-Chloroethyl) ethyl Sulfide on Nanocrystalline Magnesium Oxide. Narske, Richard M.; Klabunde, Kenneth J.; Fultz, Shawn. Department of Chemistry, Augustana College, Rock Island, IL, USA. Langmuir (2002), 18(12), 4819-4825. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:62952 AN 2002:360518 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The noncatalytic destructive adsorption of (2-chloroethyl) Et sulfide (2-CEES), a mimic of bis(2-chloroethyl) sulfide (HD or Mustard Gas), on nanocryst. Mg oxide (AP-MgO) was studied in several solvents from pentane to methanol. The decompn. products formed in these reactions were vinyl Et sulfide and (2-hydroxyethyl) Et sulfide. Reactions in pentane allowed the highest reaction rates, while THF and methanol gave results quite different from those for the hydrocarbon solvent. Reactions in methanol yielded (methoxyethyl) Et sulfide and not the vinyl Et sulfide and (2-hydroxyethyl) Et sulfide compds. These studies showed that the MgO-2-CEES reaction chem. is significantly affected by the solvent present and can be enhanced by choice of solvent and the addn. of small amts. of water. Interestingly, the least polar, least reactive solvent (pentane) allowed the most rapid 2-CEES reactions, indicating that the solvent simply aided material transfer to the reactive surface sites without blocking these sites. Rate changes upon water addn., coupled with FTIR studies, indicate that isolated surface OH groups are important reactive sites. These results indicate that the use of certain inert solvents greatly aids material transfer, and thereby the reaction rates of the sorbent with the toxin are significantly enhanced.

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Adsorption and Reaction of Diethyl Sulfide on Active Carbons with and without Impregnants under Static Conditions. Prasad, G. K.; Singh, Beer; Saradhi, U. V. R.; Suryanarayana, M. V. S.; Pandey, D. Defence Research and Development Establishment, Gwalior, India. Langmuir (2002), 18(11), 4300-4306. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:52819 AN 2002:306380 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Active carbons of different grades with and without impregnants were studied for the adsorption of di-Et sulfide (DES), the simulant of S mustard, under static conditions at 36  1. Kinetics of the adsorption were studied using linear driving force (LDF) and the Fickian diffusion model. The kinetic parameters such as equilibration time, equilibration capacity, equilibration const., diffusional exponent, and adsorbate-adsorbent interaction const. (K) were detd. The diffusional exponent (n), being <0.5, indicated a Fickian mode of diffusion of DES in the studied C. Chem. interaction also seemed to be the 2nd mechanism (although minor) involved in the DES uptake rate (the 1st being simple Fickian diffusion). The adsorbate-adsorbent interaction const. did not vary significantly indicating that probably DES chem. interacts to a small extent with the metal salts present on the surface of active C as impregnants. However, the characterization of reaction products, after extn. in CH2Cl2, using GC/MS indicated that the system CrO3/NaOH/C (C impregnated with Cr(VI) plus NaOH) only reacted with DES to give di-Et sulfone.

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An improved brain slice model of nerve agent-induced seizure activity. Wood, Sebastien J.; Tattersall, John E. H. Biomedical Sciences Department, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(Suppl. 1), S83-S86. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:290254 AN 2002:246280 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice prepn. Soman (1 M) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice prepn. is a suitable model for investigating the origin and propagation of nerve agent-induced seizures within the limbic system.

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The NMDA receptor ion channel: a site for binding of huperzine A. Gordon, Richard K.; Nigam, Savita V.; Weitz, Julie A.; Dave, Jitendra R.; Doctor, Bhupendra P.; Ved, Haresh S. Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S47-S51. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:397222 AN 2002:246274 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Huperzine A (HUP-A), first isolated from the Chinese club moss Huperzia serrata, is a potent, reversible and selective inhibitor of acetylcholinesterase (AChE) over butyrylcholinesterase (BChE) (Life Sci. 54: 991-997). Because HUP-A has been shown to penetrate the blood-brain barrier, is more stable than the carbamates used as pretreatments for organophosphate poisoning (OP) and the HUP-A:AChE complex has a longer half-life than other prophylactic sequestering agents, HUP-A has been proposed as a pretreatment drug for nerve agent toxicity by protecting AChE from irreversible OP-induced phosphonylation. More recently (NeuroReport 8: 963-968), pretreatment of embryonic neuronal cultures with HUP-A reduced glutamate-induced cell death and also decreased glutamate-induced calcium mobilization. These results suggest that HUP-A might interfere with and be beneficial for excitatory amino acid overstimulation, such as seen in ischemia, where persistent elevation of internal calcium levels by activation of the N-methyl-D-aspartate (NMDA) glutamate subtype receptor is found. The authors have now investigated the interaction of HUP-A with glutamate receptors. Freshly frozen cortex or synaptic plasma membranes were used, providing 60-90% specific radioligand binding. Huperzine A (100 M) had no effect on the binding of [3H]glutamate (low- and high-affinity glutamate sites), [3H]MDL 105,519 (NMDA glycine regulatory site), [3H]ifenprodil (NMDA polyamine site) or [3H]CGS 19755 (NMDA antagonist). In contrast with these results, HUP-A non-competitively (Hill slope < 1) inhibited [3H]MK-801 and [3H]TCP binding (co-located NMDA ion channel PCP site) with pseudo Ki .apprx. 6 M. Furthermore, when neuronal cultures were pretreated with HUP-A for 45 min prior to NMDA exposure, HUP-A dose-dependently inhibited the NMDA-induced toxicity.
Although HUP-A has been implicated to interact with cholinergic receptors, it was without effect at 100 M on muscarinic (measured by inhibition of [3H]QNB or [3H]NMS binding) or nicotinic [3H]epibatidine binding) receptors; also, HUP-A did not perturb adenosine receptor binding [3H]PIA or [3H]NECA). Therefore, HUP-A most likely attenuates excitatory amino acid toxicity by blocking the NMDA ion channel and subsequent Ca2+ mobilization at or near the PCP and MK-801 ligand sites. Thus, on the one hand, HUP-A could be used as a pretreatment against OPs and it might also be a valuable therapeutic intervention in a variety of acute and chronic disorders by protecting against overstimulation of the excitatory amino acid pathway. By blocking NMDA ion channels without psychotomimetic side-effects, HUP-A may protect against diverse neurodegenerative states obsd. during ischemia or Alzheimer's disease.

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Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense. Smith, J. Richard; Shih, Ming L.; Price, Elvis O.; Platoff, Gennady E.; Schlager, John J. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S35-S41. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365032 AN 2002:246272 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An army medical field lab. presently has the capability of performing std. protocols developed at the US Army Medical Research Institute of Chem. Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chem. warfare agents using gas chromatog./mass spectrometry. Addnl., chem. warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biol. half-lives and can be used as diagnostic biomarkers of chem. agent exposure. An anal. technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examd. for its potential to analyze these biomarkers. The technique is capable of detecting large biomols. and modifications made to them. Its fast anal. time makes MALDI-TOF/MS technol. suitable for screening casualties from chem. or biol. attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

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Analysis of the degradation compounds of chemical warfare agents using liquid chromatography/mass spectrometry. Smith, J. Richard; Shih, Ming L. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S27-S34. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365031 AN 2002:246271 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of the degrdn. products of chem. warfare (CW) agents has been a challenge to analysts. The low volatility of these compds. makes them unsuitable for direct gas chromatog. anal. without prior derivatization. Lack of a chromophore causes difficulties with classic detection methods after liq. chromatog. sepn. With the recent development of various interfaces that allow for the introduction of a liq. solvent stream into the mass spectrometer, the task of directly analyzing these compds. has become easier. For this report, the authors examd. three different liq. chromatog./mass spectrometry (LC/MS) interfaces for their suitability for the anal. of CW degrdn. compds. The interface types examd. were particle beam electron impact ionization (PBI), electrospray ionization (ESI) and atm. pressure chem. ionization (APCI). Several alkylphosphonates and thiodiglycol analogs that are produced from the degrdn. of organophosphorus nerve agents and sulfur mustard, resp., were analyzed using each of the three techniques. Electron impact ionization following gas chromatog. or particle beam introduction typically generates very reproducible, library-searchable mass spectra. Most of the CW breakdown compds. examd. using the PBI interface did not produce a mol. ion. Despite the lack of a mol. ion, the mass spectra of the various compds. contained enough different structural information from fragment ions for the pos. identification of each. The mass spectra generated using ESI are generally limited to protonated mol. ions with little or no fragmentation. For pos. identification and confirmation, tandem mass spectrometry techniques quite often must be used. Many of the compds. in this study were characterized by prominent sodiated adducts along with the protonated mol. ion. Methylphosphonic acid produced protonated dimers, trimers, etc. Although the various adduct ions can be used for addnl. confirmation of the mol. wt. of a compd., the adducts also can result in suppression of ionization of the compd.
and thus reduce sensitivity. Another "soft" ionization technique that results in abundant protonated mol. ions is APCI. The mass spectra of the breakdown compds. produced using APCI were characterized generally by either a prominent protonated mol. ion or a dehydrated form of it. In addn., a no. of structurally significant fragment ions were obsd. and their relative abundances could be adjusted by altering the APCI conditions. The data presented here indicate that each of the three techniques can be used successfully for direct liq. introduction and anal. of the non-volatile compds. produced from the degrdn. of CW agents. The mass spectra produced using each technique are quite different and could be utilized as addnl. confirmation of compd. identity.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller, Jennifer K.; Lenz, David E. Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S23-S26. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:336395 AN 2002:246270 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-mol.-wt. compds. is effected by the use of chromatog. techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the anal. To overcome those drawbacks, the authors were involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compds. such as pinacolylmethyl phosphonofluoridate (soman), which is a chem. warfare agent. Prior ests. suggested that it is necessary to be able to detect soman at a concn. below 2.5  10-7 M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The min. required assay time was 2.0-2.5 h with no loss in sensitivity. To det. the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogs were 5  10-7 M for 4-nitrophenylpinacolylmethylphosphonate, 8  10-7 M for dipinacolylmethylphosphonate, 2  10-6 M for diisopropylmethylphosphonate, 3  10-5 M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5  10-5 M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman mol., were effective inhibitors. Compds., which contained predominately arom. groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to det. its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman.

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The active site of human paraoxonase (PON1). Josse, Denis; Lockridge, Oksana; Xie, Weihua; Bartels, Cynthia F.; Schopfer, Lawrence M.; Masson, Patrick. Eppley Institute, University of Nebraska Medical Center, Omaha, NE, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S7-S11. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365079 AN 2002:246267 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ideally the authors would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman. However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4  106 M-1 min-1, and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, the authors have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw, M. D.; Hayes, T. L.; Miller, T. L.; Shannon, C. M. Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S3-S6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365078 AN 2002:246266 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) iso-Bu methylphosphonothiolate-a V-type nerve agent developed by the former Soviet Union-in the environment is an important parameter in threat assessment anal. and for the detn. of use, prodn., testing and storage of this chem. warfare agent. S-(N,N-Diethylaminoethyl) iso-Bu methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same mol. formula, it is expected that their phys. and chem. properties would be different. This preliminary investigation was undertaken to det. the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compd. at approx. 1 mg ml-1 in unbuffered water at pH 7 was detd. side-by-side. The half-lives for VXA and VX were detd. to be 12.4 days and 4.78 days, resp. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chem. Weapons Convention.

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Synthesis of high surface area monoclinic WO3 particles using organic ligands and emulsion based methods. Lu, Zhixiang; Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST), University of Maine, Orono, ME, USA. Journal of Materials Chemistry (2002), 12(4), 983-989. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 136:389533 AN 2002:226497 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several synthetic approaches have been used to obtain nano-sized monoclinic WO3 (m-WO3) powders. All of these methods begin with a std. preparative method where H2WO4 is first generated by passing a Na2WO4 soln. through a cation-exchange resin. It is shown that high surface area particles are produced by dripping the H2WO4 exiting from the ion-exchange column into a soln. contg. oxalate and acetate exchange ligands or alternatively, into a water-in-oil (w/o) based emulsion. In comparison to com. WO3 powders, the surface area of the m-WO3 powders were higher by factors of 10 and 20 times when prepd. in the presence of acetate/oxalate chelating agents and w/o emulsions, resp. The much higher surface areas enable IR spectroscopic identification of surface sites along with detection and monitoring of gaseous reactions and adsorbed species on the surface of this metal oxide. This is demonstrated with the adsorption of a nerve agent simulant, di-Me Me phosphonate. In general, little is known about the reactions of gaseous mols. on m-WO3 surfaces and the fabrication of high surface area m-WO3 particles will aid in gaining an understanding of the chem. processes occurring in WO3 based sensors.

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Prefiltering Strategies for Metal Oxide Based Sensors: The Use of Chemical Displacers to Selectively Dislodge Adsorbed Organophosphonates from Silica Surfaces. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2002), 18(3), 722-728. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 136:173252 AN 2002:22837 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

IR spectroscopy is used to monitor the competitive adsorption/desorption behavior of the nerve gas simulants, di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on SiO2. All 4 compds. molecularly adsorb via hydrogen bonds (H-bonds) with the surface hydroxyl groups. The adsorption strength depends on 2 factors: the specific functional group H-bonded to the surface hydroxyl groups and the no. of such bonds per mol. The phosphonates are molecularly displaced from the SiO2 surface by chem. displacers. By judiciously selecting chem. displacers as dictated by the 2 factors, (i.e., type and no. of functional groups H-bonded to the surface silanols) it is possible to selectively and sequentially dislodge each of the 4 phosphonate compds. adsorbed on SiO2. Specifically, the relative adsorption strength of the phosphonate compds. and the chem. displacers (labeled A-C) follows the order: TCP < MDCP < A < DMMP < B < TMP < C, where A = NEt3 (TEA), B = 2-pyridyl MeCN (2-PyAN), and C= ethylenediamine (EDA). AM1 semiempirical calcns. show that the toxic nerve agent, sarin, would position itself between MDCP and DMMP in the above order. The implications of using chem. displacers in filtering applications with metal oxide based sensors are discussed.

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New -phthalimidoperoxyalkanoic acids in decontamination. Destruction of some toxic organophosphorus and organosulfur pollutants. Lion, Claude; Da Conceicao, Louis; Delmas, Gerard; Magnaud, Gilbert. Institut de Topologie et de Dynamique des Systemes, Universite de Paris 7, Paris, Fr. New Journal of Chemistry (2001), 25(9), 1182-1184. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 136:90120 AN 2001:726141 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (chem. warfare agents and/or insecticides) is of increasing importance. We report the use of -phthalimidoperoxyalkanoic acids in the destruction of paraoxon (di-Et p-nitrophenyl phosphate), a well-known insecticide, and 2-chloro-2'-phenyldiethyl sulfide (a half mustard). We show that while all the peroxy acids used in this series allow the destruction of toxic compds., the length n of the alkanoic side chain is important to the choice of the optimal industrial compd., which is 6-phthalimidoperoxyhexanoic acid (n = 5).

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig ear skin. Chilcott, R. P.; Jenner, J.; Hotchkiss, S. A. M.; Rice, P. Department of Biomedical Sciences, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(4), 279-283. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:191481 AN 2001:616748 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chem. warfare agent sulfur mustard (SM). The in vitro absorption rates of SM through heat-sepd. human (15766 g cm-2 h-1) and pig-ear (411175 g cm-2 h-1) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 g cm-2 h-1, resp. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig ear epidermal membranes measured in vitro. Thus, although pig ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells contg. human epidermal membranes as a model for predicting in vivo human skin absorption.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen, J.; Riikonen, K.; Nikmo, J.; Jappinen, A.; Nieminen, K. Air Quality Research, Finnish Meteorological Institute, Helsinki, Finland. Journal of Hazardous Materials (2001), 85(3), 165-179. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 136:41716 AN 2001:572441 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Math. models were developed to evaluate the atm. dispersion of selected chem. warfare agents (CWA), including evapn. and settling of pollutant liq. droplets. The presented models and numerical results may be used to design protection and control measures against the conceivable use of CWA. The model, AERCLOUD (AERosol CLOUD), was extended to treat 2 nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodn. evolution of a 5-component aerosol mixt., consisting of 2-component droplets together with the surrounding 3-component gas. Numerical computations were performed using this model on the evapn. and settling of airborne sarin droplets in characteristic dispersion and atm. conditions. In particular, the max. radii (rM) of a totally evapg. droplet, in terms of the ambient temp. and pollutant vapor concn., were evaluated. The radii rM were .apprx.15-80 m for sarin droplets for selected ambient conditions and initial heights. Deposition fractions in terms of initial droplet size were also evaluated.

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Oxidation of triphenylarsine to triphenylarsine oxide by Trichoderma harzianum and other fungi. Hofmann, K.; Hammer, E.; Kohler, M.; Bruser, V. URST Umwelt- und Rohstoff-Technologie GmbH Greifswald, Greifswald, Germany. Chemosphere (2001), 44(4), 697-700. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 135:254254 AN 2001:483254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Arsenic resistant strains of bacteria and fungi were isolated from soil contaminated by chem. warfare agents. Until now, no metabolic products of microbial attack against the Ph residues of the model substrate triphenylarsine (TP) were found if it was incubated together with these strains in liq. culture assays. However, one of the isolated fungi, Trichoderma harzianum As 11, was found to oxidize TP to triphenylarsine oxide (TPO). The yeast Trichosporon mucoides SBUG 801 and the white-rot fungus Phanerochaete chrysosporium were also able to oxidize the As(III) in TP. In addn., P. chrysosporium transformed phenylarsine oxide (PAO) to phenylarsonic acid (PAA) under O2-atmosphere. By means of a respirometer system, the oxidn. of TP by T. harzianum As 11 was confirmed by a significantly higher consumption of oxygen in the presence of these compds. HPLC anal. of the oxidn. products TPO and PAA in the medium of the assays provided evidence for the transfer reaction of As(III) to As(V) in org. bonds. The oxidn. products TPO and PAA are more hydrophilic than TP and PAO. Therefore, it was concluded that particular fungi contribute to the mobilization of arsenic in soil contaminated by chem. warfare agents.

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Nanocrystalline metal oxides as unique chemical reagents/sorbents. Lucas, Erik; Decker, Shawn; Khaleel, Abbas; Seitz, Adam; Fultz, Shawn; Ponce, Aldo; Li, Weifeng; Carnes, Corrie; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry--A European Journal (2001), 7(12), 2505-2510. CODEN: CEUJED ISSN: 0947-6539. Journal; General Review written in English. CAN 135:216336 AN 2001:471452 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 29 refs. A new family of porous inorg. solids based on nanocryst. metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar orgs., and even chem./biol. warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chem. properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price, Elvis O.; Smith, J. Richard; Clark, Connie R.; Schlager, John J.; Shih, Ming L. Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S193-S197. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:206570 AN 2001:455416 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The continual threat of chem. and biol. warfare has prompted the need for unambiguous anal. methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with Hb and metallothioneins were conducted. In vitro expts. with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to det. the extent of alkylation and occurrence of HD crosslinking using the MALDI-ToF/MS technique. In a typical expt., 50 mL of 5 mM HD in acetonitrile was added to an equal vol. of 0.5 mM Hb in deionized water followed by vortexing and incubation at room temp. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES expts. These results demonstrate that MALDI-ToF/MS is a useful anal. technique to investigate the interaction of HD with biomols. and may be employed potentially as a diagnostic tool for the confirmation of exposure to chem. warfare agents.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham, John S.; Reid, Frances M.; Smith, J. Richard; Stotts, Richard R.; Tucker, F. Steven; Shumaker, Shawn M.; Niemuth, Nancy A.; Janny, Stephen J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S161-S172. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72547 AN 2001:455411 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chem. warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clin. pathol. findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liq. on the ventral surface for 2 h, generating six 3-cm diam. full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematol. and serum chem. examns. Urine was collected in metab. cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatog./mass spectrometry. Examn. of clin. pathol. parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clin. significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 g ml-1 with a mean of 2.14 g ml-1. Thiodiglycol concns. were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml-1. Mean levels remained 10-40 ng ml-1 for the remainder of the 7-day observation period, with the highest individual concn. noted during this period of 132 ng ml-1. Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other lab. animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 wk. Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h.
Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin, M. C.; Ricketts, K.; Skvorak, J. P.; Gazaway, M.; Mitcheltree, L. W.; Casillas, R. P. Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S141-S144. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72425 AN 2001:455408 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quant. edema response as well as histopathol. and biochem. endpoints as measurements of inflammation and tissue damage following exposure to the chem. warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal sepn. This study evaluated the protective effects of three of these pharmacol. compds. when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver an s.c. dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 l of a 195 mM (0.16 mg) soln. of sulfur mustard (d. = 1.27 g ml-1; MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathol. damage (necrosis, epidermal-dermal sepn.). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant redn. in edema (24%, 26% and 22%, resp.) from the pos. control. Compared to HD-pos. controls, hydrocortisone, indomethacin and olvanil caused a significant redn. in subepidermal blisters (71%, 52% and 57%, resp.) whereas only hydrocortisone produced a significant redn. in contralateral epidermal necrosis (41%). The authors show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins, Kevin B.; Lodhi, Irfan J.; Hurley, Lauren L.; Hinshaw, Daniel B. University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S125-S128. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72423 AN 2001:455404 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chem. warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells. Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 M HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 M buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 M HD for 5-6 h. Externally applied GSH up to a concn. of 5 mM had no toxic effect on the cells. Mild toxicity was assocd. with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examd. the hypothesis that HD may activate the nuclear transcription factor NFB by performing EMSAs with nuclear exts. of endothelial cells following exposure to 0, 250 or 500 M HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFB binding to its consensus sequence induced by 500 M HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFB, although HD-induced activation of NFB was partially suppressed by NAC at 5 h. Factor NFB is an important transcription factor for a no. of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFB activity. The NFB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction assocd. with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha, M.; Bowers, W., Jr.; Kohl, J.; DuBose, D.; Walker, J.; Alkhyyat, A.; Wong, G. US Army Research Institute of Environmental Medicine, Natick, MA, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S101-S108. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72420 AN 2001:455401 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl Et sulfide (CEES, 1-2 mg l-1 min-1) in humidified air or to humidified air alone. Tissues were evaluated histol., ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histol. showed that CEES induced the sepn. of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histol. and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1 (IL-1), prostaglandin-E2 (PGE2) and esp. IL-1 receptor antagonist (IL-1Ra) release (56334 vs. 84614 pg ml-1), but decreased interleukin-6 (IL-6, 4755 vs. 351 pg ml-1). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracellular IL-1 (371 vs. 92 pg ml-1). Extracellular IL-1Ra greatly increased (2375 vs. 24875 pg ml-1), whereas cellular levels decreased (165425 vs. 96625 pg ml-1). Extracellular (224 vs. 68 pg ml-1) and intracellular (485 vs. 233 pg ml-1) sol. interleukin-1 receptor II (sIL-1RII) decreased. Prostanglandin E2 increased (1835 vs. 2582 pg ml-1), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57000 vs. 96000 pg ml-1). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Intervention of sulfur mustard toxicity by down-regulation of cell proliferation and metabolic rates. Ray, R.; Benton, B. J.; Anderson, D. R.; Byers, S. L.; Petrali, J. P. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S87-S91. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72419 AN 2001:455399 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chem. warfare compd. HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37) first in keratinocyte growth medium (KGM) contg. BAPTA AM (10-40 M) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concn.-dependent manner with some cellular degeneration above 30 M (light microscopy). At 20-30 M, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 545%), [3H]-uridine (RNA synthesis, 296%) and [14C]-valine (protein synthesis, 122%) as well as a lower protein content per culture (303%) compared with corresponding untreated controls. However, 20-30 M BAPTA AM did not cause any demonstrable cytopathol. based on morphol. (electron microscopy) as well as biochem. (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Calmodulin, poly(ADP-ribose)polymerase and p53 are targets for modulating the effects of sulfur mustard. Rosenthal, Dean S.; Simbulan-Rosenthal, Cynthia M.; Iyer, Sudha; Smith, William J.; Ray, Radharaman; Smulson, Mark E. Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S43-S49. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72546 AN 2001:455392 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

We describe two pathways by which the vesicating agent sulfur mustard (HD) may cause basal cell death and detachment: induction of terminal differentiation and apoptosis. Following treatment of normal human epidermal keratinocytes (NHEK) with 10 or 100 M HD, the differentiation-specific keratin pair K1/K10 was induced and the cornified envelope precursor protein, involucrin, was crosslinked by epidermal transglutaminase. Fibronectin levels were reduced in a time- and dose-dependent manner. The rapid increase in p53 and decrease in Bcl-2 levels was consistent not only with epidermal differentiation but with apoptosis as well. Further examn. of biochem. markers of apoptosis following treatment of either NHEK or human papillomavirus (HPV)-immortalized keratinocytes revealed a burst of poly(ADP-ribose) synthesis, specific cleavage of poly(ADP-ribose)polymerase (PARP) in vivo and in vitro into characteristic 89 and 24 kDa fragments, processing of caspase-3 into its active form and the formation of DNA ladders. The intracellular calcium chelator BAPTA suppressed the differentiation markers, whereas antisense oligonucleotides and chem. inhibitors specific for calmodulin blocked both markers of differentiation and apoptosis. Modulation of p53 levels utilizing retroviral constructs expressing the E6, E7 or E6 + E7 genes of HPV-16 revealed that HD-induced apoptosis was partially p53-dependent. Finally, immortalized fibroblasts derived from PARP -/- "knockout mice" were exquisitely sensitive to HD-induced apoptosis. These cells became HD resistant when wild-type PARP was stably expressed in these cells. These results indicate that HD exerts its effects via calmodulin, p53 and PARP-sensitive pathways.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser, Janet; Meier, Henry L. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S23-S30. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72413 AN 2001:455389 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chem. warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compds. in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell prepns. were exposed to various concns. of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these expts. suggest that, with increasing HD concn. and time, NHEK will fragment irresp. of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains const. over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concn.- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, resp., is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concns. that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers, S.; Anderson, D.; Brobst, D.; Cowan, F. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S19-S22. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72270 AN 2001:455388 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chem. warfare compd., has been shown to deplete the NAD (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compds. To examine NAD+ levels, an automated method based on the alc. dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clin. analyzer has been developed. Automation of this assay led to smaller sample vols. and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD-exposed group. This assay appears to be useful for testing potential antivesicant compds. using both in vivo and in vitro exposure systems.

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Effects of Lewisite on cell membrane integrity and energy metabolism in human keratinocytes and SCL II cells. Kehe, K.; Flohe, S.; Krebs, G.; Kreppel, H.; Reichl, F. X.; Liebl, B.; Szinicz, L. Institute of Pharmacology and Toxicology, FAF Medical Academy, Munich, Germany. Toxicology (2001), 163(2-3), 137-144. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:133255 AN 2001:448571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite is a highly toxic arsenic compd. which can cause skin damage. In the present study effects of Lewisite on cell membrane integrity and energy metab. as well as antidotal effects of DL-2,3-dimercaptopropanesulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (m-DMSA) were investigated in a keratinocyte derived cell line (SCL II) and primary human keratinocytes (HK). Cells were incubated in Lewisite (60 M) contg. medium for 5 min. During the following 6 h lactate dehydrogenase (LDH) activity in the supernatant, intracellular ATP content, tetrazolium redn., glucose consumption and lactate formation were measured. Glucose consumption and lactate prodn. were decreased in both cell lines after Lewisite exposure. In SCL II cells an increase of LDH activity in the supernatant, a decrease of ATP content, and an impaired ability to reduce tetrazolium was found 3 h after Lewisite exposure. In HK cultures tetrazolium redn. was significantly decreased already after 2 h, whereas LDH increase in the supernatant and ATP content decrease occurred only at 6 h after Lewisite exposure. When DMPS or m-DMSA was added directly after Lewisite exposure to SCL II cells, glucose consumption and lactate formation were restored and LDH leakage was prevented. SCL II cells might be more prone to membrane damage whereas in keratinocytes mitochondrial impairment seems to be the predominant effect of Lewisite.

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Prophylactic efficacy of amifostine and its analogues against sulphur mustard toxicity. Vijayaraghavan, R.; Kumar, P.; Joshi, U.; Raza, S. K.; Lakshmana Rao, P. V.; Malhotra, R. C.; Jaiswal, D. K. Defence Research and Development Establishment, Gwalior, India. Toxicology (2001), 163(2-3), 83-91. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:299804 AN 2001:448565 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The successful implication of the chem. weapons convention stimulated research with a new vigor on the destruction of the stockpiled sulfur mustard (SM). A prophylactic agent for SM will be very useful for personnel engaged in the destruction of SM and during inspections by the Organization for the Prohibition of Chem. Weapons. Due to simple method of prepn., SM can be used clandestinely during war or by terrorist groups. Inspite of research over several decades no satisfactory prophylactic or treatment regimen has evolved for SM. Amifostine an organophosphorothioate, originally developed as a radioprotector, and its analogs were evaluated as a prophylactic agent for SM. Three analogs by varying the chain length and substitution at the sulfur atom were synthesized and coded as DRDE-06, DRDE-07 and DRDE-08. LD50 of amifostine and its analogs were estd. through i.p. route. For the protection studies, amifostine and its analogs were administered i.p. in mice, 30 min before dermal (percutaneous) application of SM. The dose of the prophylactic agent was 0.2 LD50 (i.p.) and that of SM was 152 mg/kg (undiluted) equal to 19-fold LD50 of SM. Amifostine and one of its analogs, DRDE-07 gave significant protection. Further studies were carried out using amifostine and DRDE-07, and both of them significantly protected mice against SM (155 mg/kg, in PEG 300, equal to 19 LD50) when they were administered i.p. either 30 min before or simultaneously. LD50 of amifostine and DRDE-07 were also estd. through the oral route (1049 or 1248 mg/kg, resp.). Prophylactically administered amifostine and DRDE-07 (0.2 LD50, p.o.) significantly protected the mice against dermally applied SM (155 mg/kg, in PEG 300, equal to 19 LD50). The protection offered by DRDE-07 was better than that of amifostine by the oral route. DRDE-07 (0.2 LD50, p.o.) also protected significantly with respect to the decrease in body wt. and the depletion of GSH induced by SM.
DNA damage induced by SM was also significantly reduced by amifostine and DRDE-07 (0.2 LD50, p.o.). Further studies are in progress on the various pharmacol. and toxicol. properties of DRDE-07.

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Adsorption of Organic Contaminants from Water Using Tailored ACFs. Mangun, Christian L.; Yue, Zhongren; Economy, James; Maloney, Stephen; Kemme, Patricia; Cropek, Donald. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, USA. Chemistry of Materials (2001), 13(7), 2356-2360. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 135:200059 AN 2001:428900 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Six activated carbon fibers (ACFs) with different chem. and phys. properties were prepd. by 1st curing a phenolic resin-coated glass fiber, followed by activation and post-treatment. Their adsorption properties were studied to evaluate the removal of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and the chem. warfare simulants diisopropylmethyl phosphonate (DIMP) and half mustard (HM) from water. The adsorption isotherms showed that ACF SL-2 (activated with CO2/H2O at 800) has a higher adsorption capacity for BTEX, DIMP, and HM than other ACFs. This suggests that the high adsorption affinity of SL-2 is related to its higher surface area, larger av. micropore size of 11.6 .ANG. (esp. effective for the adsorption of DIMP), and lower O content of the surface. The adsorption isotherms are well represented by the Freundlich equation. For BTEX, the adsorption parameters based on C coating showed that, in all cases, ACFs have a higher K value than the best available data obtained on granulated activated C. The adsorption isotherms of DIMP and HM on ACFs are presented.

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The U.S. Army reactive topical skin protectant (rTSP): challenges and successes. Hobson, Stephen T.; Lehnert, Erich K.; Braue, Ernest H., Jr. Drug Assessment Division, U. S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Materials Research Society Symposium Proceedings (2001), 628(Organic/Inorganic Hybrid Materials), CC10.8.1-CC10.8.8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 135:118044 AN 2001:354344 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In 1994, the U.S. Army initiated a research effort towards an effective material that acts both as a protective barrier and as an active destructive matrix against chem. warfare agents (CWA). We report results on our prepn. and evaluation of Reactive Topical Skin Protectants (rTSP's). These creams are composite materials consisting of a base material (TSP) and a reactive moiety. Using an established base of perfluorinated-polyether and perfluoropolyethylene solids we incorporated over 60 reactive components. Classes tested include org. polymers, org./inorg. hybrid materials, polyoxometallates (POM's), enzymes, inorg. oxides, metal alloys and small mols. We characterized these materials by light microscopy and FTIR. We detd. the efficacy of these materials against both sulfur mustard (HD) and a representative nerve agent, soman (GD), using a penetration cell model coupled to a continuous air monitor and also by in vivo testing. Composite materials with optimum reactive compds. exhibit a 94% redn. of GD vapor break-through after 20 h (from 9458 ng to 581 ng) and a 3.6 fold increase (from 162 min to 588 min) in the time 1000 ng of GD liq. penetrates through the material. Similar composite materials show a 99% redn. in HD vapor break-through after 20 h (from 4040 ng to 16 ng), a 2.3 fold increase (from 524 min to > 1200 min) in the time 1000 ng of HD vapor penetrates through the material, and an elimination of erythema vs. control in an HD vapor challenge. These results indicate that an rTSP that protects against sulfur mustard and nerve agents is within reach.

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Inhibition and promotion of combustion by organophosphorus compounds added to flames of CH4 or H2 in O2 and Ar. Korobeinichev, O. P.; Bolshova, T. A.; Shvartsberg, V. M.; Chernov, A. A. Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia. Combustion and Flame (2001), 125(1/2), 744-751. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 134:328437 AN 2001:309769 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Early in evaluating the destruction mechanisms of a no. of organophosphorus compds. (OPCs), such as tri-Me phosphate (TMP), di-Me methylphosphonate, and diisopropyl methylphosphonate, in connection with the disposal of chem. warfare agents, the promotion and inhibition effects of OPCs on stabilized flat flames of H2 +O2 were studied. Because OPCs were demonstrated to be more effective fire suppressants than CF3Br (Halon 1301) and due to the need for replacing the currently used Halon 1301, further investigation of the effects of the OPCs on flames is of interest. Thus a lean flame of CH4/O2/Ar (0.078/0.222/0.7) with and without TMP added, stabilized on a flat burner at 0.1 bar, was studied by mol. beam mass spectrometry (MBMS) and computer modeling using PREMIX and CHEMKIN codes. An exptl. study of this flame revealed that TMP increases the width of the reaction zone by inhibiting the flame.

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An Infrared Study of Adsorbed Organophosphonates on Silica: A Prefiltering Strategy for the Detection of Nerve Agents on Metal Oxide Sensors. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2001), 17(7), 2213-2218. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 134:349067 AN 2001:156303 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The gas-phase adsorption of the nerve gas simulant di-Me methylphosphonate (DMMP) along with tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on silica have been studied using IR spectroscopy. Each phosphonate compd. adsorbs through a different no. of H-bonds of the methoxy and P:O moieties with the surface hydroxyl groups on silica. The strength of the adsorption depends on the no. and type of the H-bonds and follows the order TCP < MDCP < DMMP < TMP. TCP is completely removed from silica by evacuation at room temp., adsorbed MDCP is removed by evacuation at 150 C, DMMP requires an evacuation temp. of 300 C, and TMP is eliminated at 400 C. All phosphonate compds. molecularly desorb, and the silica returns to its original state. The differences in the reactivity of phosphonate compds. on silica from other oxides demonstrate the potential use of silica in prefiltering/preconcg. strategies for semiconductive metal oxide based sensing devices. Specifically, it is shown that silica can be used to selectively adsorb DMMP from a gas stream contg. methanol/DMMP mixts.

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Reactions of VX, GB, GD, and HD with Nanosize Al2O3. Formation of Aluminophosphonates. Wagner, George W.; Procell, Lawrence R.; O'Connor, Richard J.; Munavalli, Shekar; Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA. Journal of the American Chemical Society (2001), 123(8), 1636-1644. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 134:276643 AN 2001:85006 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of VX, GB, GD, and HD with nanosize Al2O3 (AP-Al2O3) have been characterized by 31P, 13C, and 27Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH3)OR]3, are generated which are identical to synthesized model compds. Thus, the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amt. of the CH-TG sulfonium ion (12%), although some elimination of HCl is also obsd. (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addn. of excess water results in the quant. hydrolysis of sorbed HD to CH-TG. On AP-Al2O3 dried to remove physisorbed water, 13C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

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New microemulsions for oxidative decontamination of mustard gas analogues and polymer-thickened half-mustard. Gonzaga, Ferdinand; Perez, Emile; Rico-Lattes, Isabelle; Lattes, Armand. Laboratoire des Interactions Moleculaires et Reactivite Chimique et Photochimique (CNRS UMR 5623), Universite Paul Sabatier, Toulouse, Fr. New Journal of Chemistry (2001), 25(1), 151-155. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 134:232826 AN 2001:12053 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidn. of mustard gas analogs in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quant. and chemoselective oxidn. of the analogs. In a second formulation, the choice of microemulsion components used allowed us to study the oxidn. of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aq. systems.

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Bacterial release of arsenic ions and organoarsenic compounds from soil contaminated by chemical warfare agents. Kohler, Manfred; Hofmann, Klaus; Volsgen, Fernando; Thurow, Kerstin; Koch, Andreas. URST Umwelt- und Rohstoff-Technologie GmbH, Greifswald, Germany. Chemosphere (2000), Volume Date 2001, 42(4), 425-429. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 134:60919 AN 2000:878002 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The objective was to study possible participation of microorganisms in the release of sol. arsenical compds. from organoarsenic warfare agents in contaminated soil. A no. of bacterial strains were isolated with high resistance against As5+ ions which are able to degrade the water insol. compds. triphenylarsine (TP) and triphenylarsineoxide (TPO). Release of As and sol. organoarsenic compds. from soil by the activity of autochthonic soil bacteria and a mixt. of the isolated pure cultures was demonstrated by percolation expts. with undisturbed soil samples (core drills) from the contaminated site. This release increased after addnl. of nutrients (mineral N and P, Na acetate and ethanol) and is nearly independent of the percolation temp. (5 and 22). These results show that bacteria play an important role in the release of arsenical compds. from organoarsenic warfare agent contaminated soil. This release is limited by shortage of water and, above all, of nutrients for the microorganisms in the sandy forest soil. These results are important both for the management and security and possibly for bioremediation of military waste sites contg. similar contaminations.

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The chemistry of the destruction of organophosphorus compounds in flames-IV: destruction of DIMP in a flame of H2 + O2 + Ar. Korobeinichev, O. P.; Chernov, A. A.; Bolshova, T. A. Institute of Chemical Kinetics and Combustion, Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia. Combustion and Flame (2000), 123(3), 412-420. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 133:285779 AN 2000:714913 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mol. beam mass spectrometry with electron impact ionization at 11-70 eV and an electron energy spread of  0.25 eV was used to study the structure of a premixed H2/O2/Ar (0.26/0.13/0.61) flame without any additives and with 0.14% of diisopropylmethylphosphonate (DIMP), stabilized on a flat-flame burner at 62 mbar. Stable species (H2, O2, H2O), as well as atoms and radicals (H, O, OH) were monitored, including phosphorus-contg. compds.: DIMP and some intermediates of its destruction, phosphorus oxides and acids. The profiles of the mole fractions of most species, including those of atoms and free radicals were obtained. The calibration coeffs. for some species were detd. exptl., and estd. for others. Isopropylmethylphosphonate was detected as a main primary phosphorus-contg. product of the destruction of DIMP. It has been shown that bimol. reactions with hydroxyl radicals and hydrogen atoms, rather than a unimol. decompn., provide the crucial initial steps in the destruction of DIMP. A detailed mechanism for the destruction of DIMP in H2/O2/Ar flames is suggested.

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Cytotoxicity of the MEIC reference chemicals in rat hepatoma-derived Fa32 cells. Dierickx, P. J. Laboratorium Biochemische Toxikologie, Afdeling Toxikologie, Instituut voor Volksgezondheid, Brussels, Belg. Toxicology (2000), 150(1-3), 159-169. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 134:1437 AN 2000:660792 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The cytotoxicity of the MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) ref. chems. was investigated in rat hepatoma-derived Fa32 cells. The total protein content was measured as an endpoint after exposure times of 30 min and 24 h, both in normal and glutathione-depleted cells. The neutral red uptake inhibition and the MTT conversion were also measured after 30 min. On av., the cytotoxicity was higher in glutathione-depleted cells when compared to normal cells, and was lower after 30 min than after 24 h. Evidence was obtained for lysosomal attack (of five chems.) or mitochondrial dysfunction (of six chems.) as the primary intoxication mechanism. Malathion and mercuric chloride belong to both series of chems. Good to excellent correlations were obsd. when the 50% inhibitory concns. of the six different in vitro assays were compared. When the six in vitro assays in Fa32 cells were compared with the human toxicity, the correlation coeff. was almost always identical to that obtained previously in human hepatoma-derived Hep G2 cells. The latter was the best acute in vitro assay for the prediction of human toxicity within the MEIC study. Altogether the results integrate very well with the basal cytotoxicity concept (B. Ekwall; 1995).

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The role of time in toxicology or Haber's ct product. Rozman, K. K. Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA. Toxicology (2000), 149(1), 35-42. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 133:306404 AN 2000:589244 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It happened exactly 100 yr ago that Warren established for the first time a quant. link between dose and time while studying the toxicity of sodium chloride in Daphnia magna (Straus). During this century many toxicologists in different contexts returned to this idea, which has become known as Haber's rule of inhalation toxicol. Most attempts to explore this relationship ended in frustration because of the supposed occurrence of exceptions. Thus, toxicologists concd. on the quant. relationship between dose and effect under mostly isotemporal conditions while time took a back seat and was assigned such arbitrary, semiquant. designations as acute, subacute, subchronic and chronic. Time itself as a quantifiable variable of toxicity was seldom studied and when it was studied, it was often not under isodosic (steady state) conditions as required by theory. A recent anal. of toxicol. time indicated the impact of three independent time scales (toxicokinetic, toxicodynamic, exposure frequency/duration) in toxicol. studies, which interact with dose and effect to yield the enormous complexity known to every toxicologist. Based on prototypical examples when toxicokinetic (dioxins), toxicodynamic (nitrosamines, benzene) or exposure frequency (methylene chloride, chloroacetic acid, HgCl2, CdCl2, etc.) represent the crit. time scale, the general validity of the ct=k concept will be discussed as a starting point for a theory of toxicol. As endpoints of toxicity, (delayed) acute toxicity, blood dyscrasias and cancer will be used to illustrate the crit. conditions needed to demonstrate the validity of this theory.

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Detection of Fluorophosphonate Chemical Warfare Agents by Catalytic Hydrolysis with a Porous Silicon Interferometer. Sohn, Honglae; Letant, Sonia; Sailor, Michael J.; Trogler, William C. Department of Chemistry and Biochemistry, University of California at San Diego, CA, USA. Journal of the American Chemical Society (2000), 122(22), 5399-5400. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 133:100551 AN 2000:335868 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The detection of a fluorophosphonate nerve chem. warfare agent can be achieved with an oxidized porous silicon interferometer film contg. a Cu(II) hydrolysis catalyst and surfactant (CTAB). Hydrolysis of the nerve agent produces HF gas, which removes the silicon oxide as SiF4(g) and induces both a blue-shift and a decrease in intensity of the Fabry-Perot fringes. Significant changes in these 2 parameters are detected after 5 min of DFP vapor (800 ppm) exposure.

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Reactions of VX, GD, and HD with Nanosize CaO: Autocatalytic Dehydrohalogenation of HD. Wagner, George W.; Koper, Olga B.; Lucas, Erik; Decker, Shawn; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, MD, USA. Journal of Physical Chemistry B (2000), 104(21), 5118-5123. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 133:30783 AN 2000:281288 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of the chem. warfare agents VX, GD, and HD with nanosize CaO (AP-CaO), and HD with com. CaO were studied using solid-state MAS NMR. VX and GD hydrolyze to yield surface-bound complexes of nontoxic Et methylphosphonate and pinacolyl methylphosphonate, resp. The kinetics were characterized by an initial fast reaction followed by a slower, diffusion-limited reaction. Similar behavior is obsd. for HD on either dried or hydrated AP-CaO and CaO. On partially hydrated AP-CaO (but not CaO), a rather fast steady-state elimination of HCl occurs after an induction period. This behavior is attributed to acid-catalyzed surface reconstruction (to regenerate fresh surface) and the formation of CaCl2, which is known to be more reactive than CaO. The product distribution for HD is .apprx.80% divinyl sulfide and 20% thiodiglycol and/or sulfonium ions, which apparently reside as surface alkoxides. Such kinetic behavior was not evident for the common mustard simulant 2-chloroethyl Et sulfide (CEES) on partially hydrated AP-CaO, which exhibited only the typical fast/diffusion-limited reaction.

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Design and synthesis of an ,-difluorophosphinate hapten for antibody-catalyzed hydrolysis of organophosphorus nerve agents. Vayron, Philippe; Renard, Pierre-Yves; Valleix, Alain; Mioskowski, Charles. CEA, Service des Molecules Marquees, CE-Saclay, Gif sur Yvette, Fr. Chemistry--A European Journal (2000), 6(6), 1050-1063. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 133:13524 AN 2000:214064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In a new approach to the safe neutralization of organophosphorus chem. weapons, we designed a hapten to elicit catalytic antibodies with phosphatase activity. Here we report the synthesis of this ,-difluorophosphinate hapten 6. Various methods for the introduction of the key ,-difluoromethyl feature into the phosphinate hapten are discussed. The best results were obtained with the electrophilic gem-difluorinating agent N-fluorobenzenesulfonimide.

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Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate. Richardson, David E.; Yao, Huirong; Frank, Karen M.; Bennett, Deon A. Center for Catalysis Department of Chemistry, University of Florida, Gainesville, FL, USA. Journal of the American Chemical Society (2000), 122(8), 1729-1739. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 132:222157 AN 2000:94955 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Bicarbonate ion is an effective activator for hydrogen peroxide in the oxidn. of sulfides. Kinetic and spectroscopic results support the formation of peroxymonocarbonate ion (HCO4-) as the oxidant in the catalytic reactions. The reaction of hydrogen peroxide and bicarbonate to form HCO4- occurs rapidly at 25 (t1/2  300 s) near neutral pH in aq. soln. and alc./water mixts., and an equil. anal. of the reaction by 13C NMR leads to an est. of the electrode potential for the HCO4-/HCO3- couple (1.8 V vs NHE). Soly. of the bicarbonate catalyst is enhanced by the use of NH4HCO3 rather than by the use of group 1 salts, which tend to have lower soly. in the mixed solvents and can lead to phase sepn. Rate laws and mechanistic analyses are presented for the oxidn. of Et Ph sulfide and related sulfides. The second-order rate consts. for sulfide oxidns. by HCO4- are .apprx.300-fold greater than those for H2O2, and this increase is consistent with expectations based on a Bronsted anal. of the kinetics for other heterolytic peroxide oxidns. At high concns. of H2O2, a pathway that is second order in H2O2 is significant, and this path is interpreted as a general acid catalysis by H2O2 of carbonate displacement accompanying substrate attack at the electrophilic oxygen of HCO4-. Increasing water content up to 80% in the solvent increases the rate of oxidn. The BAP (bicarbonate-activated peroxide) oxidn. system is a simple, inexpensive, and relatively nontoxic alternative to other oxidants and peroxyacids, and it can be used in a variety of oxidns. where a mild, neutral pH oxidant is required. Variation of bicarbonate source and the cosolvent can allow optimization of substrate soly. and oxidn. rates for applications such as org. synthesis and chem. warfare agent decontamination.

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Synthesis and Characterization of a Functionalized Double-Chain Surfactant and Its Cleavage of O-Methyl S-Benzyl Phenylphosphonothioate. Jaeger, David A.; Li, Bei. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (2000), 16(1), 5-10. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 132:24141 AN 1999:379097 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant 2-hydrazino-N-methyl-N,N-didodecyl-2-oxoethanaminium bromide (I) was synthesized, and its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry. In a pH 9.0 borate buffer at 25, vesicular I and O-Me S-benzyl phenylphosphonothioate (II), a simulant for the chem. warfare agent VX [O-Et S-(2-N,N-diisopropylamino)ethyl methylphosphonothioate] reacted to give anion S-benzyl phenylphosphonothioate (III) and 3 cations (2-(2-N-methylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, 2-(2-N,N-dimethylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, and 2-[1-hydroxy-2-(N-methyl-N,N-didodecylammonio)ethylidene]-N',N',N'-trimethylhydrazinium, resp.) by SN2 substitution on the Me group of II. This reaction was accompanied by the pptn. of anion III with surfactant cations, which resulted in wounding/destruction of the vesicles. The combination of vesicle damage and reaction of II suggests the potential of vesicular systems for simultaneous signaling and decontamination of chem. agents. Ester II hydrolyzed in 0.10 M NaOH at 25 to give anions III and O-Me phenylphosphonothioate in a 38:62 ratio, resp.

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Reactivation kinetics of acetylcholinesterase from different species inhibited by highly toxic organophosphates. Worek F; Reiter G; Eyer P; Szinicz L Sanitatsakademie der Bundeswehr, Institut fur Pharmakologie und Toxikologie, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2002 Sep), 76(9), 523-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242610 AN 2002479746 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Standard treatment of poisoning by organophosphates (OP) includes the administration of an antimuscarinic agent, e.g. atropine, and of an acetylcholinesterase (AChE) reactivator (oxime). The presently available oximes, obidoxime and pralidoxime (2-PAM), are considered to be insufficient for highly toxic OPs, e.g. sarin. In the past decades numerous oximes were prepared and tested for their efficacy in OP poisoning, mostly in animal experiments. However, data indicate that the reactivating potency of oximes may be different in humans and animal species, which may hamper the extrapolation of animal data to humans and may pose a problem in the drug licensing of new compounds. In order to provide data for a better evaluation of the reactivating potency of oximes, experiments were undertaken to determine the reactivation rate constants of several oximes with human, rabbit, rat and guinea-pig AChE inhibited by the OPs sarin, cyclosarin and VX. The results show marked differences among the species, depending on the inhibitor and on the oxime, and indicate that the findings from animal experiments need careful evaluation before extrapolating these data to humans.

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Skin toxicokinetics of mustard gas in the guinea pig: effect of hypochlorite and safety aspects. Wormser Uri; Brodsky Berta; Sintov Amnon Faculty of Sciences,The Hebrew University, Edmond Safra Campus, Givat Ram, Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2002 Sep), 76(9), 517-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242609 AN 2002479745 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (SM, mustard gas) is a chemical warfare vesicant that rapidly penetrates the skin due to its hydrophobicity. This study measured the rate of SM disappearance from the skin after topical application of the vesicant. In both fur-covered and hairless animals, the remaining toxicant levels measured 60 min after exposure to undiluted SM were 0.6% and 0.3%, respectively, of the initially applied SM amount. However, SM concentration reached 0.4% of the initial dose 3 h following exposure in female fur-covered guinea pigs. SM quantities extracted from skin of male fur-covered and hairless guinea pigs immediately after 16 min of exposure to SM vapor were 12.2 and 21.8 microg, respectively; levels declined to 1.6 and 1.7 microg at 30 and 15 min following termination of exposure of male fur-covered and hairless guinea pigs, respectively. Three swabbing treatments of undiluted SM-exposed skin with gauze pads soaked in 0.5% hypochlorite caused 68% reduction in skin SM content. Similar findings were obtained when hypochlorite was replaced by water (64% reduction). SM content in the gauze pads was 59, 38 and 25 microg, respectively, for the first, second and third decontamination processes with water. No SM was detected in the gauze pads soaked with hypochlorite. In vitro studies showed that incubation of SM with 0.5% hypochlorite at a ratio of 10:1 (v/v) did not cause SM inactivation, whereas 4% hypochlorite reduced SM levels by 17%. However, at a decontaminant:SM ratio of 1000:1, 0.5% and 4% hypochlorite reduced SM levels by 92% and 99%, respectively. These findings are important for health authorities and regulatory agencies in planning precautionary steps to be taken in case of emergency and in routine laboratory work.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock Shannon D; Till Gerd O; Smith Milton G; Ward Peter A Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602, USA Journal of applied toxicology : JAT (2002 Jul-Aug), 22(4), 257-62. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12210543 AN 2002449749 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The chemical warfare agent analog, 2-chloroethyl ethyl sulfide, known as 'half-mustard gas' (HMG), is less toxic and less of an environmental hazard than the full molecule and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of (125)I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, we observed significant attenuation of the pulmonary injury when experimental animals were complement or neutrophil depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, dimethyl sulfoxide, dimethyl thiourea, resveratrol and N-acetyl-L-cysteine (NAC). The last compound showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement mediated pathways and the generation by neutrophils of toxic oxygen species The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat. Copyright 2002 John Wiley & Sons, Ltd.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber Ellen; McGuire Raymond Environment Protection Department, Lawrence Livermore National Laboratory, University of California, P.O. Box 808, L-626, Livermore, CA 94551, USA Journal of hazardous materials (2002 Aug 5), 93(3), 339-52. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12137994 AN 2002389537 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A decontamination method has been developed using a single reagent that is effective both against chemical warfare (CW) and biological warfare (BW) agents. The new reagent, "L-Gel", consists of an aqueous solution of a mild commercial oxidizer, Oxone, together with a commercial fumed silica gelling agent, Cab-O-Sil EH-5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. The new reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Experiments to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Laboratory and independently at four other locations. L-Gel was tested against all classes of chemical warfare agents and against various biological warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biological agents. Testing showed that L-Gel is as effective against chemical agents and biological materials, including spores, as the best military decontaminants.

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Adamantyl tenocyclidines--adjuvant therapy in poisoning with organophosphorus compounds and carbamates. Erratum in: Arch Toxicol 2002 Sep;76(9):552 Skare Danko; Radic Bozica; Lucic Ana; Peraica Maja; Domijan Ana-Marija; Milkovic-Kraus Sanja; Bradamante Vlasta; Jukic Ivan Institute Ruder Boskovic, Bijenicka c. 54, 10000 Zagreb, Croatia. skare@rudjer.irb.hr Archives of toxicology (2002 Apr), 76(3), 173-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11967623 AN 2002328057 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The objective of this study was to evaluate the efficacy of thienyl phencyclidine (tenocyclidine, TCP) and its newly synthesized adamantyl derivatives containing piperidine (TAPIP), pyrolidine (TAPIR) and morpholine (TAMORF) groups, which were tested with or without standard therapy in mice poisoned with organophosphates (OPs) and carbamates. These compounds with potential activity at the N-methyl- D-aspartate and muscarinic receptors showed low acute toxicity, having LD50 values varying from 106.00 mg/kg (TCP) to >504.00 mg/kg body weight (TAMORF). TCP and its adamantyl derivatives were administered intraperitoneally (2.5 mg/kg body weight) together with atropine (10.0 mg/kg body weight) and with or without 1/4 LD50 of the oxime HI-6. Each compound administered with atropine had a therapeutic effect against poisoning with carbamates propoxur, aldicarb and Ro 02-0683 (protective ratio of tenocyclidines was from 3.99 LD50 of aldicarb to >16.00 LD50 for propoxur). However, the efficacy of those compounds in combination with atropine was lower against poisoning with the OP insecticide dichlorvos (DDVP) and chemical warfare agents soman and tabun. In soman-poisoned mice, the best therapeutic effects were obtained with the combination of HI-6 plus atropine and test compounds, with protective ratios being from 5.40 to 7.12 LD50 of soman. The results suggest that TCP and adamantyl tenocyclidines could be used in combination with atropine as antidotes in carbamate poisoning and as adjuvant therapy to HI-6 and atropine in soman poisoning.

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Site-specific percutaneous absorption of methyl salicylate and VX in domestic swine. Duncan E J Scott; Brown April; Lundy Paul; Sawyer Thomas W; Hamilton Murray; Hill Ira; Conley John D Chemical Biological Defence Section, Defence Research Establishment, Suffield, PO Box 4000, Station Main, Medicine Hat, Alberta, Canada T1A 8K6 Journal of applied toxicology : JAT (2002 May-Jun), 22(3), 141-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12015792 AN 2002313565 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The site specificity of the percutaneous absorption of methyl salicylate (MeS) and the organophosphate nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) was examined in anaesthetized domestic swine that were fully instrumented for physiological endpoints. Four different anatomical sites (ear, perineum, inguinal crease and epigastrium) were exposed to the MeS and the serum levels were measured over a 6-h time period. The dose absorbed at the ear region was 11 microg cm(-2) with an initial flux of 0.063 microg cm(-2)min(-1), whereas at the epigastrium region the dose absorbed was 3 microg cm(-2) with an initial flux of 0.025 microg cm(-2)min(-1). For this reason further studies were carried out with VX on the ear and the epigastrium only. In animals treated with agent on the epigastrium, blood cholinesterase (ChE) activity began to drop 90 min after application and continued to decline at a constant rate for the remainder of the experiment to ca. 25% of awake control activity. At this time there were negligible signs of poisoning and the medical prognosis was judged to be good. In contrast, the ChE activity in animals receiving VX on the ear decreased to 25% of awake control values within 45 min and levelled out at 5-6% by 120 min. Clinical signs of VX poisoning paralleled the ChE inhibition, progressing in severity over the duration of the exposure. It was judged that these animals would not survive. The dramatic site dependence of agent absorption leading to vastly different toxicological endpoints demonstrated in this model system has important ramifications for chemical protective suit development, threat assessment, medical countermeasures and contamination control protocols. Copyright 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

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An improved brain slice model of nerve agent-induced seizure activity. Wood S J; Tattersall J E Biomedical Sciences Department, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S83-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920926 AN 2002191151 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice preparation. Soman (1 microM) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists, but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice preparation is a suitable model for investigating the origin and propagation of nerve-agent-induced seizures within the limbic system. Copyright 2001 John Wiley & Sons, Ltd.

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Cardiopulmonary effects of HI-6 treatment in soman intoxication. Goransson-Nyberg A; Cassel G Division of NBC Defence, Department of Medical Counter Measures, Swedish Defence Research Agency, SE-90182 Umea, Sweden Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S79-81. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920925 AN 2002191150 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The cardiopulmonary effects of HI-6, together with atropine and soman, were studied in the rat. HI-6 is an effective antidote in acute poisoning with the nerve agent soman. The therapeutic efficiency of HI-6 is still unclear and cannot be explained entirely by the HI-6 reactivating ability of acetylcholinesterase (AChE). Other non-cholinergic factors must be involved. One possible detoxifying process might be an effect of HI-6 on the blood flow to sensitive organs. The purpose of the present study was to investigate 1) whether soman per se induces changes in regional blood flow and 2) whether the blood flow to different organs is affected when HI-6 (50 mg x kg(-1) i.m.) and atropine (10 mg x kg(-1) i.m.) are given either before or immediately after soman intoxication (90 microg x kg(-1) s.c.). For regional blood flow determinations the microsphere method was used with male Wistar rats weighing 300-400 g. The rats were anaesthetised and breathed spontaneously during the experiment. Three different blood flow measurements were made in the same animal and concomitant physiological parameters such as mean arterial blood pressure and respiratory rate were recorded. The blood AChE activity was followed throughout the experiment. Our results show that when HI-6 is given after intoxication with soman, dramatic changes in blood flow occur with a significant decrease in both respiratory rate and blood AChE activity. If HI-6 is given prior to the intoxication, however, all rats are unaffected and none of the parameters measured are changed. Copyright 2001 John Wiley & Sons, Ltd.

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Prophylaxis against organophosphate poisoning by sustained release of scopolamine and physostigmine. Meshulam Y; Cohen G; Chapman S; Alkalai D; Levy A Department of Pharmacology, Israel Institute for Biological Research (IIBR), PO Box 19, 70450 Ness-Ziona, Israel Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S75-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920924 AN 2002191149 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Protection efficacy of continuous prophylactic administration of physostigmine and scopolamine against sarin-induced toxicity was evaluated previously in guinea pigs. The present study in large animals used Beagle dogs, that serve as an animal model with cholinergic sensitivity similar to that of humans. Pretreatment with physostigmine salicylate and scopolamine hydrochloride at dose rates of 2.5 and 1 microg x kg(-1) x h(-1), respectively, was administered via Alzet mini-osmotic pumps. At the time of exposure, the physostigmine salicylate concentration in plasma was 0.7 ng x ml(-1) and the scopolamine hydrochloride concentration was ca. 0.2 ng x ml(-1), both of which are levels known to be well tolerated in humans. Whole-blood cholinesterase inhibition was 15-20%. This regimen conferred full protection against 2.5 x LD50 i.v. of sarin. Albeit the high-dose exposure, cholinergic toxicity symptoms were mild with no convulsions. About 11-14 min following poisoning the treated animals started to walk and 15-20 min following exposure full recovery was observed and the dogs behaved normally. With higher dose rates of physostigmine salicylate and scopolamine hydrochloride, at plasma concentrations of 2.1 and 0.6 ng x ml(-1), respectively, treated dogs regained normal posture 6-10 min after exposure. Copyright 2001 John Wiley & Sons, Ltd.

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Intramuscular diazepam pharmacokinetics in soman-exposed guinea pigs. Capacio B R; Whalley C E; Byers C E; McDonough J H Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S67-74. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920923 AN 2002191148 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Intramuscular (i.m.) diazepam is included by the US military as an anticonvulsant in the standard therapeutic regimen for organophosphorus nerve agent intoxication. In this study we investigated the pharmacokinetics of diazepam after i.m. administration while monitoring pharmacodynamic (electroencephalogram, EEG) data in soman-exposed guinea pigs. Prior to experiments the animals were surgically implanted with EEG leads to monitor seizure activity. For the study, animals were administered pyridostigmine (0.026 mg x kg(-1) i.m.) 30 min prior to soman (56 microg x kg(-1), 2 x LD50; subcutaneously, s.c.), which was followed in 1 min by atropine sulfate (2 mg x kg(-1) i.m.) and pralidoxime chloride (25 mg x kg(-1) i.m.). All animals receiving this regimen developed seizure activity. Diazepam (10 mg x kg(-1) i.m.) was administered 5 min after onset of seizure activity. Based on EEG data, animals were categorized as either seizure terminated or not terminated at 30 min after diazepam. Serial blood samples were obtained from each animal. Diazepam (10 mg x kg(-1) i.m.) terminated seizure activity in 52% of the animals within 30 min. The pharmacokinetics were characterized by a one-compartment model with first-order absorption and elimination. The maximum plasma concentrations (Cmax) were 991 and 839 ng x ml(-1) for seizure terminated and not terminated, respectively. Mean plasma concentrations of diazepam were significantly different (P < 0.05) for seizure terminated vs not terminated groups at 30 min. The plasma Cmax in seizure-terminated animals in this study is similar to the minimum range of plasma diazepam (200-800 ng x ml(-1)) reported to suppress seizure activity in humans. It has been reported in an earlier study that the minimum effective i.m. dose (0.1 mg x kg(-1)) required to prevent soman-induced convulsions in Rhesus monkeys produces a mean Cmax of 50 ng x ml(-1) for diazepam.
The data from our current study suggest that a higher dose (and corresponding Cmax) is necessary to terminate ongoing seizure activity. Copyright 2001 John Wiley & Sons, Ltd.

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Combination anticonvulsant treatment of soman-induced seizures. Koplovitz I; Schulz S; Shutz M; Railer R; Macalalag R; Schons M; McDonough J Drug Assessment Division, US Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010, USA. Koplovitz@asia.apgea.army.mil Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S53-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920921 AN 2002191147 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures. Copyright 2001 John Wiley & Sons, Ltd.

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Soman-induced seizures: limbic activity, oxidative stress and neuroprotective proteins. Pazdernik T L; Emerson M R; Cross R; Nelson S R; Samson F E Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City, KS 66160, USA. tpazdern@kumc.edu Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S87-94. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920927 AN 2002185330 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman, a potent acetylcholinesterase inhibitor, induces status epilepticus in rats followed by conspicuous neuropathology, most prominent in piriform cortex and the CA3 region of the hippocampus. Cholinergic seizures originate in striatal-nigral pathways and with fast-acting agents (soman) rapidly spread to limbic related areas and finally culminate in a full-blown status epilepticus. This leads to neurochemical changes, some of which may be neuroprotective whereas others may cause brain damage. Pretreatment with lithium sensitizes the brain to cholinergic seizures. Likewise, other agents that increase limbic hyperactivity may sensitize the brain to cholinergic agents. The hyperactivity associated with the seizure state leads to an increase in intracellular calcium, cellular edema and metal delocalization producing an oxidative stress. These changes induce the synthesis of stress-related proteins such as heat shock proteins, metallothioneins and heme oxygenases. We show that soman-induced seizures cause a depletion in tissue glutathione and an increase in tissue 'catalytic' iron, metallothioneins and heme oxygenase-1. The oxidative stress induces the synthesis of stress-related proteins, which are indicators of 'stress' and possibly provide neuroprotection. These findings suggest that delocalization of iron may catalyze Fenton-like reactions, causing progressive cellular damage via free radical products. Copyright 2001 John Wiley & Sons, Ltd.

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Beneficial effects of TCP on soman intoxication in guinea pigs: seizures, brain damage and learning behaviour. de Groot D M; Bierman E P; Bruijnzeel P L; Carpentier P; Kulig B M; Lallement G; Melchers B P; Philippens I H; van Huygevoort A H TNO Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S57-65. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920922 AN 2002185328 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Poisoning with the potent nerve agent soman produces a cascade of central nervous system (CNS) effects characterized by severe convulsions and eventually death. In animals that survive a soman intoxication, lesions in the amygdala, piriform cortex, hippocampus and thalamus can be observed. In order to examine the mechanisms involved in the effects of soman and to evaluate possible curative interventions, a series of behavioural, electrophysiological and neuropathological experiments were carried out in the guinea pig using the NMDA antagonist N-[1-(2-thienyl)cyclohexyl] piperidine (TCP) in conjunction with atropine and pyridostigmine. The NMDA antagonist TCP appeared to be very effective in the treatment of casualties who suffered from soman-induced seizures for 30 min: (i)Seizures were arrested within minutes after the TCP injection, confirmed by quantitative electroencephalogram (EEG), after fast Fourier analysis. Three hours after TCP the quantitative EEGs were completely normal in all frequency bands and remained normal during the entire 3-week intoxication period. The power shift to the lower (delta) frequency bands, indicative for neuropathology and found in control animals intoxicated only by soman, was not observed in the soman-TCP group. (ii)The gross neuropathology found in soman control animals within 48 h after soman was prevented in soman-TCP animals and was still absent in 3-week survivors. Instead, ultrastructural changes were observed, indicative of defense mechanisms of the cell against toxic circumstances. (iii)Twenty-four hours after soman, soman-TCP animals were able to perform in the shuttle box and Morris water maze. The beneficial effects of TCP on the performance in these tests during the 3-week intoxication period were very impressive, notwithstanding (minor) deficits in memory and learning. (iv)The increase in excitability after TCP was confirmed by an increase in the acoustic startle response.
Taken together, these results confirmed the involvement of NMDA receptors in the maintenance of soman-induced seizures and the development of brain damage. They underline the current hypothesis that cholinergic mechanisms are responsible for eliciting seizure activity after soman and that, most likely, the subsequent recruitment of other excitatory neurotransmitters and loss of inhibitory control are responsible for the maintenance of seizures and the development of subsequent brain damage. Copyright 2001 John Wiley & Sons, Ltd.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw M D; Hayes T L; Miller T L; Shannon C M Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH 43201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S3-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920912 AN 2002185325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate--a V-type nerve agent developed by the former Soviet Union--in the environment is an important parameter in threat assessment analysis and for the determination of use, production, testing and storage of this chemical warfare agent. S-(N,N-Diethylaminoethyl) isobutyl methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same molecular formula, it is expected that their physical and chemical properties would be different. This preliminary investigation was undertaken to determine the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compound at approximately 1 mg x ml(-1) in unbuffered water at pH 7 was determined side-by-side. The half-lives for VXA and VX were determined to be 12.4 days and 4.78 days, respectively. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chemical Weapons Convention. Copyright 2001 John Wiley & Sons, Ltd.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller J K; Lenz D E Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD 21201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S23-6. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920916 AN 2002185323 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-molecular-weight compounds is effected by the use of chromatographic techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the analysis. To overcome those drawbacks, we have been involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds such as pinacolylmethyl phosphonofluoridate (soman), which is a chemical warfare agent. Prior estimates suggested that it is necessary to be able to detect soman at a concentration below 2.5 x 10(-7) M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The minimum required assay time was 2.0-2.5 h with no loss in sensitivity. To determine the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogues were 5 x 10(-7) M for 4-nitrophenylpinacolylmethylphosphonate, 8 x 10(-7) M for dipinacolylmethylphosphonate, 2 x 10(-6) M for diisopropylmethylphosphonate, 3 x 10(-5) M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5 x 10(-5) M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman molecule, were effective inhibitors. Compounds, which contained predominately aromatic groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to determine its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman. Copyright 2001 John Wiley & Sons, Ltd.

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Protective action of the serine protease inhibitor N-tosyl-L-lysine chloromethyl ketone (TLCK) against acute soman poisoning. Cowan F M; Broomfield C A; Lenz D E; Shih T M Biochemical Pharmacology and Neurotoxicology Branches, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 293-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481662 AN 2002027826 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman-poisoned rats display cholinergic crisis, a systemic mast cell degranulation characteristic of anaphylactic reactions and an excitotoxin-like sequential seizure and neuronal degeneration. The protection of guinea pigs from soman lethality by prophylactic administration of the serine protease inhibitor suramin suggests a possible proteolytic component in soman poisoning. The present study tested the effect of N-tosyl-L-lysine chloromethyl ketone (TLCK), an inhibitor of trypsin-like serine proteases, on soman-induced toxic signs (convulsions, righting reflex) and survival time. Nine control guinea pigs receiving 2 x LD(50) (56 microg kg(-1), s.c.) of soman immediately followed by a therapeutic dose of atropine sulfate (17.4 mg kg(-1) i.m.) experienced severe convulsions, and 8/9 lost the righting reflex. Six of these nine animals expired within 65 min; the three remaining animals survived 24 h to termination of the experiment. When a second group of animals were given TLCK (12 mg kg(-1), i.p.) 30 min prior to a 2 x LD(50) soman challenge and atropine-sulfate therapy, 5/9 experienced convulsions and only 3/9 lost the righting reflex. All nine animals survived beyond 4 h, with six surviving to 24 h. Compared with soman controls, prophylaxis with TLCK significantly prevented the loss of righting reflex (P = 0.05) and enhanced 4-h survival (P = 0.005). Although, convulsions were reduced and 24-h survival was improved in TLCK-treated animals, these results were not statistically significant. The protection from soman toxicity by chemically distinct protease inhibitors such as suramin and TLCK suggests a role for pathological proteolytic pathways in soman intoxication. Copyright 2001 John Wiley & Sons, Ltd.

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin. Chilcott R P; Jenner J; Hotchkiss S A; Rice P Department of Biomedical Sciences, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 279-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481660 AN 2002027824 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption. Copyright 2001 John Wiley & Sons, Ltd.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen J; Riikonen K; Nikmo J; Jappinen A; Nieminen K Air Quality Research, Finnish Meteorological Institute, Sahaajankatu 20 E, FIN-00810, Helsinki, Finland. jaakko.kukkonen@fmi.fi Journal of hazardous materials (2001 Aug 17), 85(3), 165-79. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11489522 AN 2001443815 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

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Effects of iodine on inducible nitric oxide synthase and cyclooxygenase-2 expression in sulfur mustard-induced skin. Nyska A; Lomnitski L; Maronpot R; Moomaw C; Brodsky B; Sintov A; Wormser U Laboratory of Experimental Pathology, National Institutes of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA. nyska@niehs.nih.gov Archives of toxicology (2001 Feb), 74(12), 768-74. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11305779 AN 2001394179 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

In a previous study we demonstrated the protective effect of topical iodine as postexposure treatment for sulfur mustard (SM) application. The iodine treatment results in significantly reduced inflammation and necrosis and increased epidermal hyperplasia. The expression and localization of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in paraffin-embedded skin samples from that study were evaluated in the present investigation. We compared the immunoreactivity of iNOS and COX-2 using five samples from each of the following four test sites: untreated control sites, SM-exposed sites, sites treated with iodine mixture 15 min after SM exposure, and sites treated with iodine 30 min after SM exposure. All animals were killed 2 days after irritant exposure. iNOS immunoreactivity was present only in skin sites exposed to SM without iodine treatment. The ulcerated skin was covered with a relatively thick band of exudate composed of iNOS-immunostained polymorphonuclear cells and macrophages. In untreated skin, COX-2 immunostaining was limited to the thin suprabasal epidermal layer. In SM-exposed skin, induction of COX-2 was noted in inflammatory cells located close to the site of epidermal injury. In skin sites treated with iodine 15 or 30 min after SM exposure, the regenerating hyperplastic epithelium showed moderate cytoplasmic staining localized to the epithelium overlying the basal layer. This pattern of staining was also present in the nearby dermal fibroblasts. Thus, in contrast to the skin samples exposed to SM without iodine treatment, the epidermal layer expressing immunohistochemical positivity for COX-2 was thicker and corresponded to the epidermal hyperplasia noted in samples treated with iodine. It is well documented that prostaglandins (PGs) promote epidermal proliferation, thereby contributing to the repair of injured skin. That the induction of the COX-2 shown in our study may also play a role in the healing process is indicated by the present evidence.
The results suggest that nitric oxide radicals (NO*) are involved in mediating the damage induced by the SM and that iodine-related reduction in acute epidermal inflammation is associated with reduced iNOS expression.

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Intervention of sulfur mustard toxicity by downregulation of cell proliferation and metabolic rates. Ray R; Benton B J; Anderson D R; Byers S L; Petrali J P US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. radharaman.ray@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S87-91. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428650 AN 2001371709 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chemical warfare compound HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37 degrees C) first in keratinocyte growth medium (KGM) containing BAPTA AM (10-40 microM) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concentration-dependent manner with some cellular degeneration above 30 microM (light microscopy). At 20-30 microM, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 54 +/- 5%), [3H]-uridine (RNA synthesis, 29 +/- 6%) and [14C]-valine (protein synthesis, 12 +/- 2%) as well as a lower protein content per culture (30 +/- 3%) compared with corresponding untreated controls. However, 20-30 microM BAPTA AM did not cause any demonstrable cytopathology based on morphological (electron microscopy) as well as biochemical (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser J; Meier H L Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S23-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428638 AN 2001371697 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chemical warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compounds in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell preparations were exposed to various concentrations of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these experiments suggest that, with increasing HD concentration and time, NHEK will fragment irrespective of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains constant over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concentration- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, respectively, is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concentrations that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price E O; Smith J R; Clark C R; Schlager J J; Shih M L Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S193-7. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428636 AN 2001371695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The continual threat of chemical and biological warfare has prompted the need for unambiguous analytical methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with hemoglobin and metallothioneine were conducted. In vitro experiments with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to determine the extent of alkylation and occurrence of HD cross-linking using the MALDI-ToF/MS technique. In a typical experiment, 50 ml of 5 mM HD in acetonitrile was added to an equal volume of 0.5 mM hemoglobin in deionized water followed by vortexing and incubation at room temperature. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES experiments. These results demonstrate that MALDI-ToF/MS is a useful analytical technique to investigate the interaction of HD with biomolecules and may be employed potentially as a diagnostic tool for the confirmation of exposure to chemical warfare agents.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers S; Anderson D; Brobst D; Cowan F Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S19-22. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428635 AN 2001371694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham J S; Reid F M; Smith J R; Stotts R R; Tucker E S; Shumaker S M; Niemuth N A; Janny S J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S161-72. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428630 AN 2001371689 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chemical warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clinical pathology findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liquid on the ventral surface for 2 h, generating six 3-cm diameter full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematology and serum chemistry examinations. Urine was collected in metabolism cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatography/mass spectrometry. Examination of clinical pathology parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clinically significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 microg ml(-1) with a mean of 2.14 microg ml(-1). Thiodiglycol concentrations were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml(-1). Mean levels remained 10-40 ng ml(-1) for the remainder of the 7-day observation period, with the highest individual concentration noted during this period of 132 ng ml(-1). Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other laboratory animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 week.
Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h. Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin M C; Ricketts K; Skvorak J P; Gazaway M; Mitcheltree L W; Casillas R P Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA. Michael.Babin@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S141-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428627 AN 2001371686 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quantitative edema response as well as histopathological and biochemical endpoints as measurements of inflammation and tissue damage following exposure to the chemical warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal separation. This study evaluated the protective effects of three of these pharmacological compounds when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver a subcutaneous dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 microl of a 195 mM (0.16 mg) solution of sulfur mustard (density = 1.27 g ml(-1); MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathological damage (necrosis, epidermal-dermal separation). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant reduction in edema (24%, 26% and 22%, respectively) from the positive control. Compared to HD-positive controls, hydrocortisone, indomethacin and olvanil caused a significant reduction in subepidermal blisters (71%, 52% and 57%, respectively) whereas only hydrocortisone produced a significant reduction in contralateral epidermal necrosis (41%). We show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins K B; Lodhi I J; Hurley L L; Hinshaw D B University of Michigan Medical School, Ann Arbor 48105, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S125-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428622 AN 2001371681 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chemical warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells (Toxicol. Appl. Pharmacol. 1996; 141: 568-583). Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFkappaB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFkappaB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 microM HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 microM buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 microM HD for 5-6 h. Externally applied GSH up to a concentration of 5 mM had no toxic effect on the cells. Mild toxicity was associated with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examined the hypothesis that HD may activate the nuclear transcription factor NFkappaB by performing EMSAs with nuclear extracts of endothelial cells following exposure to 0, 250 or 500 microM HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFkappaB binding to its consensus sequence induced by 500 microM HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFkappaB, although HD-induced activation of NFkappaB was partially suppressed by NAC at 5 h. Factor NFkappaB is an important transcription factor for a number of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFkappaB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFkappaB activity. The NFkappaB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction associated with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha M; Bowers W Jr; Kohl J; DuBose D; Walker J; Alkhyyat A; Wong G US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S101-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428619 AN 2001371678 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chemical warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl ethyl sulfide (CEES, 1-2 mg l(-1) min(-1)) in humidified air or to humidified air alone. Tissues were evaluated histologically, ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histology showed that CEES induced the separation of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histology and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1alpha (IL-1alpha), prostaglandin-E2 (PGE2) and especially IL-1 receptor antagonist (IL-1Ra) release (56,334 vs 84,614 pg ml(-1)), but decreased interleukin-6 (IL-6, 4,755 vs 351 pg ml(-1)). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracelluar IL-1alpha (371 vs 92 pg ml(-1)). Extracellular IL-1Ra greatly increased (2,375 vs 24,875 pg ml(-1)), whereas cellular levels decreased (16,5425 vs 96,625 pg ml(-1)). Extracellular (224 vs 68 pg ml(-1)) and intracellular (485 vs 233 pg ml(-1)) soluble interleukin-1 receptor H (sIL-1RII) decreased. Prostanglandin E2 increased (1,835 vs 2,582 pg ml(-1)), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57,000 vs 96,000 pg ml(-1)). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Correlation of a specific mitochondrial phospholipid-phosgene adduct with chloroform acute toxicity. Di Consiglio E; De Angelis G; Testai E; Vittozzi L Biochemical Toxicology Unit, Department of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita, Viale Regina Elena 299, I-00161, Rome, Italy Toxicology (2001 Feb 21), 159(1-2), 43-53. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11250054 AN 2001195862 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The dose and time dependence of formation of a specific adduct between mitochondrial phospholipid and phosgene have been determined in the liver of Sprague-Dawley (SD) rats as well as in the liver and kidney of B6C3F1 mice after dosing with chloroform. Rats were induced with phenobarbital or non-induced. Determination of tissue glutathione (GSH) and of serum markers of hepatotoxicity and nephrotoxicity was also carried out. With dose-dependence experiments, a strong correlation between the formation of the specific phospholipid adduct, GSH depletion and organ toxicity could be evidenced in all the organs studied. With non-induced SD rats, no such effects could be induced up to a dose of 740 mg/kg. Time-course studies with B6C3F1 mice indicated that the specific adduct formation took place at very early times after chloroform dosing and was concurrent with GSH depletion. The adduct formed during even transient GSH depletion (residual level: 30% of control) and persisted after restoration of GSH levels. Following a chloroform dose at the hepatotoxicity threshold (150 mg/kg), the elimination of the adduct in the liver occurred within 24 h and correlated with the recovery of ALT, which was slightly increased (12 times) after treatment. Following a moderately nephrotoxic dose (60 mg/kg), the renal adduct persisted longer than 48 h, when a 100% increase in blood urea nitrogen and a 40% increase in serum creatinine indicated the onset of organ damage. The formation of the adduct in the liver mitochondria of B6C3F1 mice was associated with the decrease of phosphatidyl-ethanolamine (PE), in line with previous results in rat liver indicating that the adduct results from the reaction of phosgene with PE. The adduct levels implicated the reaction of phosgene with about 50% PE molecules in the liver mitochondrial membrane of phenobarbital-induced SD rats and of about 10% PE molecules of the inner mitochondrial membrane of the liver of B6C3F1 mice.
The association of this adduct with the toxic effects of chloroform makes it a very good candidate as the primary critical alteration in the sequence of events leading to cell death caused by chloroform.

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The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats. Kassa J; Fusek J Purkyne Military Medical Academy, PO Box 35/T, 500 01, Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2000 Nov 23), 154(1-3), 67-73. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11118671 AN 2001083637 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.

[megalomania]

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Development of multifunctional perfluorinated polymer blends as an active barrier cream against chemical warfare agents. Hobson, Stephen T.; Braue, Ernest H., Jr. Drug Assessment Div., U.S. Army Medical Research Institute for Chemical Defense, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 80-81. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:363990 AN 2003:381106 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare agents (CWA's) represent a real and growing threat both to U.S. armed forces as well as to civilians. Within the last three decades, chem. weapons have been used by the Soviets in Cambodia (yellow rain, tricothecene mycotoxins), by Iraq against Iran (HD and tabun), and by Iraq against its own dissident Kurdish population at Halabja (H-ID HCN0). In the United States' experience in World War I, almost one-third of hospitalized casualties were a result of CWA's. Furthermore, the 1000 casualties and 12 deaths resulting from the 1995 terrorist use of sarin (GB) in Tokyo show that civilians have also become targets. In this paper we focus on protection against two classes of CWA's: nerve agents (soman, GD) and blister agents (sulfur mustard, HD). Protection against these agents in the United States Army consists of a chem. resistant outer layer of clothing (BDO) and protective mask (M40). This scheme of protection allows operation in a chem. contaminated area but results in decreased performance and increased heat retention. We have investigated a material that serves as a phys. barrier to CWA's and contains an active moiety to neutralize hazardous chems. This Active Topical Skin Protectant (aTSP) would be used in conjunction with other protective procedures. Herein we report the prepn., characterization, and evaluation of aTSP's.

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Molecularly imprinted polymers for the detection of chemical agents in water. Jenkins, Amanda L.; Yin, Ray; Jensen, Janet L.; Durst, H. Dupont. US Army Research Laboratory, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 76-77. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:343335 AN 2003:381101 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molecularly imprinted polymers contg. Eu3+ were prepd. using a no. of pesticides and pinacolyl methylphosphonate (hydrolysis product of the nerve agent Soman), and sensors were fabricated by coating the polymers on optical fibers. The sensors were characterized in terms of sensitivity, selectivity, response time, adaptability, and portability; they provided detection limits in the low parts per trillion.

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Synthesis of carbon-coated MgO nanoparticles. Bedilo, Alexander F.; Sigel, M. Jake; Koper, Olga B.; Melgunov, Maxim S.; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2002), 12(12), 3599-3604. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 138:174329 AN 2002:910661 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Carbon-coated MgO nanoparticles, with carbon forming a porous coating on the surface of MgO nanoparticles, have been prepd. by two different techniques. Resorcinol has been found to be an efficient agent for the modification of magnesium methoxide leading to carbon-coated MgO nanocrystals of small crystallite size and high surface area. Decompn. of dry magnesium methoxide under an inert gas flow proved to be another efficient and economical way to synthesize carbon-coated MgO. The carbon coating acts as a hydrophobic barrier partially protecting the core metal oxide from water adsorption and conversion to magnesium hydroxide. However, destructive adsorption reactions can still proceed on the metal oxide surface, as evidenced by the dehydrochlorination of 2-chloroethyl Et sulfide (2-CEES) and 1-chlorobutane. The overall stability of the material in the presence of water vapor is significantly improved in comparison with non-coated nanocryst. MgO.

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Micellar Effects on Hypochlorite Catalyzed Decontamination of Toxic Phosphorus Esters. Dubey, D. K.; Gupta, A. K.; Sharma, Mamta; Prabha, S.; Vaidyanathaswamy, R. Defence R and D Establishment, Gwalior, India. Langmuir (2002), 18(26), 10489-10492. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 138:94789 AN 2002:866089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At pH 8.5, the surfactant N,N,N-trimethyl-1-hexadecanaminium bromide (I) increased the pseudo-first-order rate consts. of hypochlorite-catalyzed hydrolysis of the sarin model compd. p-nitrophenyl di-Ph phosphate by 300 times and that of the toxic p-nitrophenyl iso-Pr methylphosphonate by 20 times, and the nerve agent sarin itself was completely decontaminated within 10 min at a sarin-hypochlorite ratio of 20:1 in a micellar I-hypochlorite mixt. In the absence of surfactant , it takes >70 min to detoxify sarin, even at a 10 times higher concn. of hypochlorite.

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A Comparative Study of the Adsorption of Chloro- and Non-Chloro-Containing Organophosphorus Compounds on WO3. Kanan, Sofian M.; Lu, Zhixiang; Tripp, Carl P. Laboratory for Surface Science Technology and Department of Chemistry, University of Maine, Orono, ME, USA. Journal of Physical Chemistry B (2002), 106(37), 9576-9580. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 137:253624 AN 2002:620746 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The adsorption of di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), and methyldichlorophosphate (MDCP) on monoclinic tungsten oxide (m-WO3) evacuated at various temps. was investigated using IR spectroscopy. DMMP is the most common mol. used for evaluating the performance of WO3 and other semiconducting metal oxide (SMO)-based sensors to phosphonate-based nerve agents. However, toxic nerve agents such as sarin differ from DMMP in that they contain a functional group (P-F in sarin) that can be readily hydrolyzed. It is shown that the adsorption of organophosphates that contain P-Cl groups differs from nonhalogenated simulants such as DMMP and TMP on WO3 surfaces. Specifically, the non-chlorinated simulants DMMP and TMP adsorb on the surface solely through the P:O functionality with the surface water layer as well as the Lewis and Bronsted acid sites. The relative no. of mols. bound on Lewis and Bronsted acid surface sites depends on the initial evacuation temp. of the WO3 surface. When MDCP adsorbs on WO3 through the P:O bond, it is accompanied by the hydrolysis of P-Cl groups by water vapor or the adsorbed water layer leading to addnl. phosphate-like species on the surface. The IR data suggests that a halogenated phosphate like MDCP is a better simulant mol. for studies aimed at understanding the role of water and hydrolysis in the response of metal oxide-based sensors to nerve agents.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock, Shannon D.; Till, Gerd O.; Smith, Milton G.; Ward, Peter A. Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2002), 22(4), 257-262. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 137:151235 AN 2002:596130 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. warfare agent analog, 2-chloroethyl Et sulfide, known as half-mustard gas (HMG), is less toxic and less of an environmental hazard than the full mol. and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of 125I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, the authors obsd. significant attenuation of the pulmonary injury when exptl. animals were complement- or neutrophil-depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, DMSO, dimethylthiourea, Resveratrol, and N-acetyl-L-cysteine (NAC). The last compd. showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement-mediated pathways and the generation by neutrophils of toxic oxygen species. The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber, Ellen; McGuire, Raymond. Lawrence Livermore National Laboratory, Environment Protection Department, University of California, Livermore, CA, USA. Journal of Hazardous Materials (2002), 93(3), 339-352. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 137:374412 AN 2002:558690 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A decontamination method was developed using a single reagent that is effective both against chem. warfare (CW) and biol. warfare (BW) agents. The new reagent, L-Gel, consists of an aq. soln. of a mild com. oxidizer, Oxone, together with a com. fumed silica gelling agent, Cab-O-Sil EH 5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. This reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Expts. to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Lab. and independently at 4 other locations. L-Gel was tested against all classes of chem. warfare agents and against various biol. warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biol. agents. Testing showed that L-Gel is as effective against chem. agents and biol. materials, including spores, as the best military decontaminants.

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Synthesis, Characterization, and Adsorption Studies of Nanocrystalline Aluminum Oxide and a Bimetallic Nanocrystalline Aluminum Oxide/Magnesium Oxide. Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J.; Bonevich, John. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry of Materials (2002), 14(7), 2922-2929. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 137:128541 AN 2002:469813 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of Al2O3 and Al2O3/MgO have been produced by a modified aerogel synthesis involving the corresponding aluminum tri-tert-butoxide, magnesium methoxide, toluene, methanol, ethanol, and water. The resulting oxides are in the form of powders having crystallites of .ltorsim.2 nm. These crystallites have been studied by TEM and BET methods, and were found to possess high surface areas and pore vols. (800 m2/g for Al2O3 and 790 m2/g for Al2O3/MgO, compared to 450 m2/g for MgO). As seen with other metal oxides, once they are produced as nanoparticles, their reactivity is greatly enhanced on a per unit surface area basis. This is thought to be due to morphol. differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites possess much higher surface concn. of such sites per unit surface area. Elemental anal., X-ray diffraction, and IR spectroscopy have been used to characterize these nanoparticles, and reactions with CCl4, SO2, and Paraoxon have demonstrated significantly enhanced reactivity and/or capacity compared with common com. forms of the oxide powders. A significant feature is that, by a cogellation synthesis, Al2O3 and MgO have been intermingled, which engenders enhanced reactivity/capacity over the pure forms of nanoscale Al2O3 or MgO toward a chem. warfare surrogate (Paraoxon) and an acid gas (SO2). This serves as an example where tailored synthesis of a nanostructured formulation can yield special benefits.

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Nanocrystalline metal oxides as destructive adsorbents for organophosphorus compounds at ambient temperatures. Rajagopalan, Shyamala; Koper, Olga; Decker, Shawn; Klabunde, Kenneth J. Nanoscale Materials, Inc., Manhattan, KS, USA. Chemistry--A European Journal (2002), 8(11), 2602-2607. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 137:191092 AN 2002:451335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of magnesium oxide react with organophosphorus compds. at room temp. by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant mol. fragments. These ultrafine powders have unusual cryst. shapes and possess high surface concns. of reactive edge/corner and defect sites, and thereby display higher surface reactivity, normalized for surface area, than typical polycryst. material. This high surface reactivity coupled with high surface area allows their use for effective decontamination of chem. warfare agents and related toxic substances. Herein data is presented for paraoxon, diisopropylfluorophosphate (DFP), and (CH3CH2O)2P(O)CH2SC6H5 (DEPTMP). Solid-state NMR and IR spectroscopy indicate that all OR and F groups dissoc.; this leaves bound -PO4, -F, and -OR groups for paraoxon, DFP, and DEPTMP, resp. For paraoxon, it was shown that one monolayer reacts. For DEPTMP, the OR groups dissoc., but not the P-CH2SC6H5 group. The nanocryst. MgO reacts much faster and in higher capacity than typical activated carbon samples, which physisorb but do not destructively adsorb these phosphorous compds.

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Routes of photocatalytic destruction of chemical warfare agent simulants. Vorontsov, Alexandre V.; Davydov, Lev; Reddy, Ettireddy P.; Lion, Claude; Savinov, Eugenii N.; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russia. New Journal of Chemistry (2002), 26(6), 732-744. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 137:236738 AN 2002:427511 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Selected imitants of chem. warfare agents such as di-Me methylphosphonate (DMMP), di-Et phosphoramidate (DEPA), pinacolyl methylphosphonate (PMP), and butylaminoethanethiol (BAET) were subjected to photocatalytic and sonophotocatalytic treatment in aq. suspensions of TiO2. Complete conversion of the same mass of imitants to inorg. products was obtained within 600 min for DMMP, DEPA, PMP, but required a longer time for BAET. Sonolysis accelerated photodegrdn. of DMMP. No degrdn. was obsd. without UV illumination. Final products of degrdn. were PO43-, CO2 for DMMP and PMP, PO43-, NO3- (25%), NH4+ (75%), CO2 for DEPA, and SO42-, NH4+, CO2 for BAET. The no. of main detected intermediate products increases in the order DMMP (7), DEPA (9), PMP (21), and exceeds 34 for BAET. Degrdn. of DMMP mainly proceeds through consecutive oxidn. of methoxy groups and then the Me group. Di-Me hydroxymethylphosphonate and dimethylphosphate testify to the parallel oxidn. of the Me group. Destruction of DEPA mainly starts with cleavage of the P-NH2 bond to form di-Et phosphate, which transforms further into Et phosphate. Oxidn. of  and  carbons of ethoxy groups to form ethylphosphonoamidate, hydroxyethyl ethylphosphonoamidate and other products also contributes to the destruction. Photocatalytic degrdn. of PMP mainly starts with oxidn. of the pinacolyl fragment, methylphosphonic acid and acetone being the major products. Oxidn. of BAET begins with dark dimerization to disulfide, which undergoes oxidn. of sulfur forming sulfinic and sulfonic acids as well as oxidn. of carbons to form butanal, aminobutane, etc., and cyclic products such as 2-propylthiazole. A scheme of degrdn. was proposed for DMMP and DEPA, and starting routes for PMP and BAET. Quantum efficiencies of complete mineralization calcd. as reaction rate to photon flux ratio approx. 10-3%.

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Solvent Effects on the Heterogeneous Adsorption and Reactions of (2-Chloroethyl) ethyl Sulfide on Nanocrystalline Magnesium Oxide. Narske, Richard M.; Klabunde, Kenneth J.; Fultz, Shawn. Department of Chemistry, Augustana College, Rock Island, IL, USA. Langmuir (2002), 18(12), 4819-4825. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:62952 AN 2002:360518 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The noncatalytic destructive adsorption of (2-chloroethyl) Et sulfide (2-CEES), a mimic of bis(2-chloroethyl) sulfide (HD or Mustard Gas), on nanocryst. Mg oxide (AP-MgO) was studied in several solvents from pentane to methanol. The decompn. products formed in these reactions were vinyl Et sulfide and (2-hydroxyethyl) Et sulfide. Reactions in pentane allowed the highest reaction rates, while THF and methanol gave results quite different from those for the hydrocarbon solvent. Reactions in methanol yielded (methoxyethyl) Et sulfide and not the vinyl Et sulfide and (2-hydroxyethyl) Et sulfide compds. These studies showed that the MgO-2-CEES reaction chem. is significantly affected by the solvent present and can be enhanced by choice of solvent and the addn. of small amts. of water. Interestingly, the least polar, least reactive solvent (pentane) allowed the most rapid 2-CEES reactions, indicating that the solvent simply aided material transfer to the reactive surface sites without blocking these sites. Rate changes upon water addn., coupled with FTIR studies, indicate that isolated surface OH groups are important reactive sites. These results indicate that the use of certain inert solvents greatly aids material transfer, and thereby the reaction rates of the sorbent with the toxin are significantly enhanced.

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Adsorption and Reaction of Diethyl Sulfide on Active Carbons with and without Impregnants under Static Conditions. Prasad, G. K.; Singh, Beer; Saradhi, U. V. R.; Suryanarayana, M. V. S.; Pandey, D. Defence Research and Development Establishment, Gwalior, India. Langmuir (2002), 18(11), 4300-4306. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:52819 AN 2002:306380 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Active carbons of different grades with and without impregnants were studied for the adsorption of di-Et sulfide (DES), the simulant of S mustard, under static conditions at 36  1. Kinetics of the adsorption were studied using linear driving force (LDF) and the Fickian diffusion model. The kinetic parameters such as equilibration time, equilibration capacity, equilibration const., diffusional exponent, and adsorbate-adsorbent interaction const. (K) were detd. The diffusional exponent (n), being <0.5, indicated a Fickian mode of diffusion of DES in the studied C. Chem. interaction also seemed to be the 2nd mechanism (although minor) involved in the DES uptake rate (the 1st being simple Fickian diffusion). The adsorbate-adsorbent interaction const. did not vary significantly indicating that probably DES chem. interacts to a small extent with the metal salts present on the surface of active C as impregnants. However, the characterization of reaction products, after extn. in CH2Cl2, using GC/MS indicated that the system CrO3/NaOH/C (C impregnated with Cr(VI) plus NaOH) only reacted with DES to give di-Et sulfone.

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An improved brain slice model of nerve agent-induced seizure activity. Wood, Sebastien J.; Tattersall, John E. H. Biomedical Sciences Department, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(Suppl. 1), S83-S86. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:290254 AN 2002:246280 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice prepn. Soman (1 M) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice prepn. is a suitable model for investigating the origin and propagation of nerve agent-induced seizures within the limbic system.

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The NMDA receptor ion channel: a site for binding of huperzine A. Gordon, Richard K.; Nigam, Savita V.; Weitz, Julie A.; Dave, Jitendra R.; Doctor, Bhupendra P.; Ved, Haresh S. Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S47-S51. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:397222 AN 2002:246274 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Huperzine A (HUP-A), first isolated from the Chinese club moss Huperzia serrata, is a potent, reversible and selective inhibitor of acetylcholinesterase (AChE) over butyrylcholinesterase (BChE) (Life Sci. 54: 991-997). Because HUP-A has been shown to penetrate the blood-brain barrier, is more stable than the carbamates used as pretreatments for organophosphate poisoning (OP) and the HUP-A:AChE complex has a longer half-life than other prophylactic sequestering agents, HUP-A has been proposed as a pretreatment drug for nerve agent toxicity by protecting AChE from irreversible OP-induced phosphonylation. More recently (NeuroReport 8: 963-968), pretreatment of embryonic neuronal cultures with HUP-A reduced glutamate-induced cell death and also decreased glutamate-induced calcium mobilization. These results suggest that HUP-A might interfere with and be beneficial for excitatory amino acid overstimulation, such as seen in ischemia, where persistent elevation of internal calcium levels by activation of the N-methyl-D-aspartate (NMDA) glutamate subtype receptor is found. The authors have now investigated the interaction of HUP-A with glutamate receptors. Freshly frozen cortex or synaptic plasma membranes were used, providing 60-90% specific radioligand binding. Huperzine A (100 M) had no effect on the binding of [3H]glutamate (low- and high-affinity glutamate sites), [3H]MDL 105,519 (NMDA glycine regulatory site), [3H]ifenprodil (NMDA polyamine site) or [3H]CGS 19755 (NMDA antagonist). In contrast with these results, HUP-A non-competitively (Hill slope < 1) inhibited [3H]MK-801 and [3H]TCP binding (co-located NMDA ion channel PCP site) with pseudo Ki .apprx. 6 M. Furthermore, when neuronal cultures were pretreated with HUP-A for 45 min prior to NMDA exposure, HUP-A dose-dependently inhibited the NMDA-induced toxicity.
Although HUP-A has been implicated to interact with cholinergic receptors, it was without effect at 100 M on muscarinic (measured by inhibition of [3H]QNB or [3H]NMS binding) or nicotinic [3H]epibatidine binding) receptors; also, HUP-A did not perturb adenosine receptor binding [3H]PIA or [3H]NECA). Therefore, HUP-A most likely attenuates excitatory amino acid toxicity by blocking the NMDA ion channel and subsequent Ca2+ mobilization at or near the PCP and MK-801 ligand sites. Thus, on the one hand, HUP-A could be used as a pretreatment against OPs and it might also be a valuable therapeutic intervention in a variety of acute and chronic disorders by protecting against overstimulation of the excitatory amino acid pathway. By blocking NMDA ion channels without psychotomimetic side-effects, HUP-A may protect against diverse neurodegenerative states obsd. during ischemia or Alzheimer's disease.

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Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense. Smith, J. Richard; Shih, Ming L.; Price, Elvis O.; Platoff, Gennady E.; Schlager, John J. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S35-S41. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365032 AN 2002:246272 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An army medical field lab. presently has the capability of performing std. protocols developed at the US Army Medical Research Institute of Chem. Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chem. warfare agents using gas chromatog./mass spectrometry. Addnl., chem. warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biol. half-lives and can be used as diagnostic biomarkers of chem. agent exposure. An anal. technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examd. for its potential to analyze these biomarkers. The technique is capable of detecting large biomols. and modifications made to them. Its fast anal. time makes MALDI-TOF/MS technol. suitable for screening casualties from chem. or biol. attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

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Analysis of the degradation compounds of chemical warfare agents using liquid chromatography/mass spectrometry. Smith, J. Richard; Shih, Ming L. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S27-S34. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365031 AN 2002:246271 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of the degrdn. products of chem. warfare (CW) agents has been a challenge to analysts. The low volatility of these compds. makes them unsuitable for direct gas chromatog. anal. without prior derivatization. Lack of a chromophore causes difficulties with classic detection methods after liq. chromatog. sepn. With the recent development of various interfaces that allow for the introduction of a liq. solvent stream into the mass spectrometer, the task of directly analyzing these compds. has become easier. For this report, the authors examd. three different liq. chromatog./mass spectrometry (LC/MS) interfaces for their suitability for the anal. of CW degrdn. compds. The interface types examd. were particle beam electron impact ionization (PBI), electrospray ionization (ESI) and atm. pressure chem. ionization (APCI). Several alkylphosphonates and thiodiglycol analogs that are produced from the degrdn. of organophosphorus nerve agents and sulfur mustard, resp., were analyzed using each of the three techniques. Electron impact ionization following gas chromatog. or particle beam introduction typically generates very reproducible, library-searchable mass spectra. Most of the CW breakdown compds. examd. using the PBI interface did not produce a mol. ion. Despite the lack of a mol. ion, the mass spectra of the various compds. contained enough different structural information from fragment ions for the pos. identification of each. The mass spectra generated using ESI are generally limited to protonated mol. ions with little or no fragmentation. For pos. identification and confirmation, tandem mass spectrometry techniques quite often must be used. Many of the compds. in this study were characterized by prominent sodiated adducts along with the protonated mol. ion. Methylphosphonic acid produced protonated dimers, trimers, etc. Although the various adduct ions can be used for addnl. confirmation of the mol. wt. of a compd., the adducts also can result in suppression of ionization of the compd.
and thus reduce sensitivity. Another "soft" ionization technique that results in abundant protonated mol. ions is APCI. The mass spectra of the breakdown compds. produced using APCI were characterized generally by either a prominent protonated mol. ion or a dehydrated form of it. In addn., a no. of structurally significant fragment ions were obsd. and their relative abundances could be adjusted by altering the APCI conditions. The data presented here indicate that each of the three techniques can be used successfully for direct liq. introduction and anal. of the non-volatile compds. produced from the degrdn. of CW agents. The mass spectra produced using each technique are quite different and could be utilized as addnl. confirmation of compd. identity.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller, Jennifer K.; Lenz, David E. Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S23-S26. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:336395 AN 2002:246270 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-mol.-wt. compds. is effected by the use of chromatog. techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the anal. To overcome those drawbacks, the authors were involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compds. such as pinacolylmethyl phosphonofluoridate (soman), which is a chem. warfare agent. Prior ests. suggested that it is necessary to be able to detect soman at a concn. below 2.5  10-7 M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The min. required assay time was 2.0-2.5 h with no loss in sensitivity. To det. the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogs were 5  10-7 M for 4-nitrophenylpinacolylmethylphosphonate, 8  10-7 M for dipinacolylmethylphosphonate, 2  10-6 M for diisopropylmethylphosphonate, 3  10-5 M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5  10-5 M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman mol., were effective inhibitors. Compds., which contained predominately arom. groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to det. its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman.

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The active site of human paraoxonase (PON1). Josse, Denis; Lockridge, Oksana; Xie, Weihua; Bartels, Cynthia F.; Schopfer, Lawrence M.; Masson, Patrick. Eppley Institute, University of Nebraska Medical Center, Omaha, NE, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S7-S11. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365079 AN 2002:246267 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ideally the authors would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman. However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4  106 M-1 min-1, and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, the authors have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw, M. D.; Hayes, T. L.; Miller, T. L.; Shannon, C. M. Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S3-S6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365078 AN 2002:246266 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) iso-Bu methylphosphonothiolate-a V-type nerve agent developed by the former Soviet Union-in the environment is an important parameter in threat assessment anal. and for the detn. of use, prodn., testing and storage of this chem. warfare agent. S-(N,N-Diethylaminoethyl) iso-Bu methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same mol. formula, it is expected that their phys. and chem. properties would be different. This preliminary investigation was undertaken to det. the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compd. at approx. 1 mg ml-1 in unbuffered water at pH 7 was detd. side-by-side. The half-lives for VXA and VX were detd. to be 12.4 days and 4.78 days, resp. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chem. Weapons Convention.

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Synthesis of high surface area monoclinic WO3 particles using organic ligands and emulsion based methods. Lu, Zhixiang; Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST), University of Maine, Orono, ME, USA. Journal of Materials Chemistry (2002), 12(4), 983-989. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 136:389533 AN 2002:226497 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several synthetic approaches have been used to obtain nano-sized monoclinic WO3 (m-WO3) powders. All of these methods begin with a std. preparative method where H2WO4 is first generated by passing a Na2WO4 soln. through a cation-exchange resin. It is shown that high surface area particles are produced by dripping the H2WO4 exiting from the ion-exchange column into a soln. contg. oxalate and acetate exchange ligands or alternatively, into a water-in-oil (w/o) based emulsion. In comparison to com. WO3 powders, the surface area of the m-WO3 powders were higher by factors of 10 and 20 times when prepd. in the presence of acetate/oxalate chelating agents and w/o emulsions, resp. The much higher surface areas enable IR spectroscopic identification of surface sites along with detection and monitoring of gaseous reactions and adsorbed species on the surface of this metal oxide. This is demonstrated with the adsorption of a nerve agent simulant, di-Me Me phosphonate. In general, little is known about the reactions of gaseous mols. on m-WO3 surfaces and the fabrication of high surface area m-WO3 particles will aid in gaining an understanding of the chem. processes occurring in WO3 based sensors.

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Prefiltering Strategies for Metal Oxide Based Sensors: The Use of Chemical Displacers to Selectively Dislodge Adsorbed Organophosphonates from Silica Surfaces. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2002), 18(3), 722-728. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 136:173252 AN 2002:22837 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

IR spectroscopy is used to monitor the competitive adsorption/desorption behavior of the nerve gas simulants, di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on SiO2. All 4 compds. molecularly adsorb via hydrogen bonds (H-bonds) with the surface hydroxyl groups. The adsorption strength depends on 2 factors: the specific functional group H-bonded to the surface hydroxyl groups and the no. of such bonds per mol. The phosphonates are molecularly displaced from the SiO2 surface by chem. displacers. By judiciously selecting chem. displacers as dictated by the 2 factors, (i.e., type and no. of functional groups H-bonded to the surface silanols) it is possible to selectively and sequentially dislodge each of the 4 phosphonate compds. adsorbed on SiO2. Specifically, the relative adsorption strength of the phosphonate compds. and the chem. displacers (labeled A-C) follows the order: TCP < MDCP < A < DMMP < B < TMP < C, where A = NEt3 (TEA), B = 2-pyridyl MeCN (2-PyAN), and C= ethylenediamine (EDA). AM1 semiempirical calcns. show that the toxic nerve agent, sarin, would position itself between MDCP and DMMP in the above order. The implications of using chem. displacers in filtering applications with metal oxide based sensors are discussed.

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New -phthalimidoperoxyalkanoic acids in decontamination. Destruction of some toxic organophosphorus and organosulfur pollutants. Lion, Claude; Da Conceicao, Louis; Delmas, Gerard; Magnaud, Gilbert. Institut de Topologie et de Dynamique des Systemes, Universite de Paris 7, Paris, Fr. New Journal of Chemistry (2001), 25(9), 1182-1184. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 136:90120 AN 2001:726141 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (chem. warfare agents and/or insecticides) is of increasing importance. We report the use of -phthalimidoperoxyalkanoic acids in the destruction of paraoxon (di-Et p-nitrophenyl phosphate), a well-known insecticide, and 2-chloro-2'-phenyldiethyl sulfide (a half mustard). We show that while all the peroxy acids used in this series allow the destruction of toxic compds., the length n of the alkanoic side chain is important to the choice of the optimal industrial compd., which is 6-phthalimidoperoxyhexanoic acid (n = 5).

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig ear skin. Chilcott, R. P.; Jenner, J.; Hotchkiss, S. A. M.; Rice, P. Department of Biomedical Sciences, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(4), 279-283. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:191481 AN 2001:616748 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chem. warfare agent sulfur mustard (SM). The in vitro absorption rates of SM through heat-sepd. human (15766 g cm-2 h-1) and pig-ear (411175 g cm-2 h-1) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 g cm-2 h-1, resp. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig ear epidermal membranes measured in vitro. Thus, although pig ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells contg. human epidermal membranes as a model for predicting in vivo human skin absorption.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen, J.; Riikonen, K.; Nikmo, J.; Jappinen, A.; Nieminen, K. Air Quality Research, Finnish Meteorological Institute, Helsinki, Finland. Journal of Hazardous Materials (2001), 85(3), 165-179. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 136:41716 AN 2001:572441 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Math. models were developed to evaluate the atm. dispersion of selected chem. warfare agents (CWA), including evapn. and settling of pollutant liq. droplets. The presented models and numerical results may be used to design protection and control measures against the conceivable use of CWA. The model, AERCLOUD (AERosol CLOUD), was extended to treat 2 nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodn. evolution of a 5-component aerosol mixt., consisting of 2-component droplets together with the surrounding 3-component gas. Numerical computations were performed using this model on the evapn. and settling of airborne sarin droplets in characteristic dispersion and atm. conditions. In particular, the max. radii (rM) of a totally evapg. droplet, in terms of the ambient temp. and pollutant vapor concn., were evaluated. The radii rM were .apprx.15-80 m for sarin droplets for selected ambient conditions and initial heights. Deposition fractions in terms of initial droplet size were also evaluated.

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Oxidation of triphenylarsine to triphenylarsine oxide by Trichoderma harzianum and other fungi. Hofmann, K.; Hammer, E.; Kohler, M.; Bruser, V. URST Umwelt- und Rohstoff-Technologie GmbH Greifswald, Greifswald, Germany. Chemosphere (2001), 44(4), 697-700. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 135:254254 AN 2001:483254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Arsenic resistant strains of bacteria and fungi were isolated from soil contaminated by chem. warfare agents. Until now, no metabolic products of microbial attack against the Ph residues of the model substrate triphenylarsine (TP) were found if it was incubated together with these strains in liq. culture assays. However, one of the isolated fungi, Trichoderma harzianum As 11, was found to oxidize TP to triphenylarsine oxide (TPO). The yeast Trichosporon mucoides SBUG 801 and the white-rot fungus Phanerochaete chrysosporium were also able to oxidize the As(III) in TP. In addn., P. chrysosporium transformed phenylarsine oxide (PAO) to phenylarsonic acid (PAA) under O2-atmosphere. By means of a respirometer system, the oxidn. of TP by T. harzianum As 11 was confirmed by a significantly higher consumption of oxygen in the presence of these compds. HPLC anal. of the oxidn. products TPO and PAA in the medium of the assays provided evidence for the transfer reaction of As(III) to As(V) in org. bonds. The oxidn. products TPO and PAA are more hydrophilic than TP and PAO. Therefore, it was concluded that particular fungi contribute to the mobilization of arsenic in soil contaminated by chem. warfare agents.

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Nanocrystalline metal oxides as unique chemical reagents/sorbents. Lucas, Erik; Decker, Shawn; Khaleel, Abbas; Seitz, Adam; Fultz, Shawn; Ponce, Aldo; Li, Weifeng; Carnes, Corrie; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry--A European Journal (2001), 7(12), 2505-2510. CODEN: CEUJED ISSN: 0947-6539. Journal; General Review written in English. CAN 135:216336 AN 2001:471452 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 29 refs. A new family of porous inorg. solids based on nanocryst. metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar orgs., and even chem./biol. warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chem. properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price, Elvis O.; Smith, J. Richard; Clark, Connie R.; Schlager, John J.; Shih, Ming L. Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S193-S197. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:206570 AN 2001:455416 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The continual threat of chem. and biol. warfare has prompted the need for unambiguous anal. methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with Hb and metallothioneins were conducted. In vitro expts. with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to det. the extent of alkylation and occurrence of HD crosslinking using the MALDI-ToF/MS technique. In a typical expt., 50 mL of 5 mM HD in acetonitrile was added to an equal vol. of 0.5 mM Hb in deionized water followed by vortexing and incubation at room temp. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES expts. These results demonstrate that MALDI-ToF/MS is a useful anal. technique to investigate the interaction of HD with biomols. and may be employed potentially as a diagnostic tool for the confirmation of exposure to chem. warfare agents.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham, John S.; Reid, Frances M.; Smith, J. Richard; Stotts, Richard R.; Tucker, F. Steven; Shumaker, Shawn M.; Niemuth, Nancy A.; Janny, Stephen J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S161-S172. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72547 AN 2001:455411 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chem. warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clin. pathol. findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liq. on the ventral surface for 2 h, generating six 3-cm diam. full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematol. and serum chem. examns. Urine was collected in metab. cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatog./mass spectrometry. Examn. of clin. pathol. parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clin. significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 g ml-1 with a mean of 2.14 g ml-1. Thiodiglycol concns. were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml-1. Mean levels remained 10-40 ng ml-1 for the remainder of the 7-day observation period, with the highest individual concn. noted during this period of 132 ng ml-1. Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other lab. animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 wk. Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h.
Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin, M. C.; Ricketts, K.; Skvorak, J. P.; Gazaway, M.; Mitcheltree, L. W.; Casillas, R. P. Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S141-S144. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72425 AN 2001:455408 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quant. edema response as well as histopathol. and biochem. endpoints as measurements of inflammation and tissue damage following exposure to the chem. warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal sepn. This study evaluated the protective effects of three of these pharmacol. compds. when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver an s.c. dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 l of a 195 mM (0.16 mg) soln. of sulfur mustard (d. = 1.27 g ml-1; MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathol. damage (necrosis, epidermal-dermal sepn.). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant redn. in edema (24%, 26% and 22%, resp.) from the pos. control. Compared to HD-pos. controls, hydrocortisone, indomethacin and olvanil caused a significant redn. in subepidermal blisters (71%, 52% and 57%, resp.) whereas only hydrocortisone produced a significant redn. in contralateral epidermal necrosis (41%). The authors show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins, Kevin B.; Lodhi, Irfan J.; Hurley, Lauren L.; Hinshaw, Daniel B. University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S125-S128. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72423 AN 2001:455404 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chem. warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells. Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 M HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 M buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 M HD for 5-6 h. Externally applied GSH up to a concn. of 5 mM had no toxic effect on the cells. Mild toxicity was assocd. with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examd. the hypothesis that HD may activate the nuclear transcription factor NFB by performing EMSAs with nuclear exts. of endothelial cells following exposure to 0, 250 or 500 M HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFB binding to its consensus sequence induced by 500 M HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFB, although HD-induced activation of NFB was partially suppressed by NAC at 5 h. Factor NFB is an important transcription factor for a no. of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFB activity. The NFB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction assocd. with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha, M.; Bowers, W., Jr.; Kohl, J.; DuBose, D.; Walker, J.; Alkhyyat, A.; Wong, G. US Army Research Institute of Environmental Medicine, Natick, MA, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S101-S108. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72420 AN 2001:455401 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl Et sulfide (CEES, 1-2 mg l-1 min-1) in humidified air or to humidified air alone. Tissues were evaluated histol., ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histol. showed that CEES induced the sepn. of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histol. and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1 (IL-1), prostaglandin-E2 (PGE2) and esp. IL-1 receptor antagonist (IL-1Ra) release (56334 vs. 84614 pg ml-1), but decreased interleukin-6 (IL-6, 4755 vs. 351 pg ml-1). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracellular IL-1 (371 vs. 92 pg ml-1). Extracellular IL-1Ra greatly increased (2375 vs. 24875 pg ml-1), whereas cellular levels decreased (165425 vs. 96625 pg ml-1). Extracellular (224 vs. 68 pg ml-1) and intracellular (485 vs. 233 pg ml-1) sol. interleukin-1 receptor II (sIL-1RII) decreased. Prostanglandin E2 increased (1835 vs. 2582 pg ml-1), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57000 vs. 96000 pg ml-1). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Intervention of sulfur mustard toxicity by down-regulation of cell proliferation and metabolic rates. Ray, R.; Benton, B. J.; Anderson, D. R.; Byers, S. L.; Petrali, J. P. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S87-S91. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72419 AN 2001:455399 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chem. warfare compd. HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37) first in keratinocyte growth medium (KGM) contg. BAPTA AM (10-40 M) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concn.-dependent manner with some cellular degeneration above 30 M (light microscopy). At 20-30 M, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 545%), [3H]-uridine (RNA synthesis, 296%) and [14C]-valine (protein synthesis, 122%) as well as a lower protein content per culture (303%) compared with corresponding untreated controls. However, 20-30 M BAPTA AM did not cause any demonstrable cytopathol. based on morphol. (electron microscopy) as well as biochem. (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Calmodulin, poly(ADP-ribose)polymerase and p53 are targets for modulating the effects of sulfur mustard. Rosenthal, Dean S.; Simbulan-Rosenthal, Cynthia M.; Iyer, Sudha; Smith, William J.; Ray, Radharaman; Smulson, Mark E. Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S43-S49. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72546 AN 2001:455392 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

We describe two pathways by which the vesicating agent sulfur mustard (HD) may cause basal cell death and detachment: induction of terminal differentiation and apoptosis. Following treatment of normal human epidermal keratinocytes (NHEK) with 10 or 100 M HD, the differentiation-specific keratin pair K1/K10 was induced and the cornified envelope precursor protein, involucrin, was crosslinked by epidermal transglutaminase. Fibronectin levels were reduced in a time- and dose-dependent manner. The rapid increase in p53 and decrease in Bcl-2 levels was consistent not only with epidermal differentiation but with apoptosis as well. Further examn. of biochem. markers of apoptosis following treatment of either NHEK or human papillomavirus (HPV)-immortalized keratinocytes revealed a burst of poly(ADP-ribose) synthesis, specific cleavage of poly(ADP-ribose)polymerase (PARP) in vivo and in vitro into characteristic 89 and 24 kDa fragments, processing of caspase-3 into its active form and the formation of DNA ladders. The intracellular calcium chelator BAPTA suppressed the differentiation markers, whereas antisense oligonucleotides and chem. inhibitors specific for calmodulin blocked both markers of differentiation and apoptosis. Modulation of p53 levels utilizing retroviral constructs expressing the E6, E7 or E6 + E7 genes of HPV-16 revealed that HD-induced apoptosis was partially p53-dependent. Finally, immortalized fibroblasts derived from PARP -/- "knockout mice" were exquisitely sensitive to HD-induced apoptosis. These cells became HD resistant when wild-type PARP was stably expressed in these cells. These results indicate that HD exerts its effects via calmodulin, p53 and PARP-sensitive pathways.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser, Janet; Meier, Henry L. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S23-S30. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72413 AN 2001:455389 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chem. warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compds. in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell prepns. were exposed to various concns. of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these expts. suggest that, with increasing HD concn. and time, NHEK will fragment irresp. of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains const. over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concn.- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, resp., is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concns. that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers, S.; Anderson, D.; Brobst, D.; Cowan, F. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S19-S22. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72270 AN 2001:455388 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chem. warfare compd., has been shown to deplete the NAD (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compds. To examine NAD+ levels, an automated method based on the alc. dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clin. analyzer has been developed. Automation of this assay led to smaller sample vols. and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD-exposed group. This assay appears to be useful for testing potential antivesicant compds. using both in vivo and in vitro exposure systems.

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Effects of Lewisite on cell membrane integrity and energy metabolism in human keratinocytes and SCL II cells. Kehe, K.; Flohe, S.; Krebs, G.; Kreppel, H.; Reichl, F. X.; Liebl, B.; Szinicz, L. Institute of Pharmacology and Toxicology, FAF Medical Academy, Munich, Germany. Toxicology (2001), 163(2-3), 137-144. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:133255 AN 2001:448571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite is a highly toxic arsenic compd. which can cause skin damage. In the present study effects of Lewisite on cell membrane integrity and energy metab. as well as antidotal effects of DL-2,3-dimercaptopropanesulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (m-DMSA) were investigated in a keratinocyte derived cell line (SCL II) and primary human keratinocytes (HK). Cells were incubated in Lewisite (60 M) contg. medium for 5 min. During the following 6 h lactate dehydrogenase (LDH) activity in the supernatant, intracellular ATP content, tetrazolium redn., glucose consumption and lactate formation were measured. Glucose consumption and lactate prodn. were decreased in both cell lines after Lewisite exposure. In SCL II cells an increase of LDH activity in the supernatant, a decrease of ATP content, and an impaired ability to reduce tetrazolium was found 3 h after Lewisite exposure. In HK cultures tetrazolium redn. was significantly decreased already after 2 h, whereas LDH increase in the supernatant and ATP content decrease occurred only at 6 h after Lewisite exposure. When DMPS or m-DMSA was added directly after Lewisite exposure to SCL II cells, glucose consumption and lactate formation were restored and LDH leakage was prevented. SCL II cells might be more prone to membrane damage whereas in keratinocytes mitochondrial impairment seems to be the predominant effect of Lewisite.

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Prophylactic efficacy of amifostine and its analogues against sulphur mustard toxicity. Vijayaraghavan, R.; Kumar, P.; Joshi, U.; Raza, S. K.; Lakshmana Rao, P. V.; Malhotra, R. C.; Jaiswal, D. K. Defence Research and Development Establishment, Gwalior, India. Toxicology (2001), 163(2-3), 83-91. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:299804 AN 2001:448565 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The successful implication of the chem. weapons convention stimulated research with a new vigor on the destruction of the stockpiled sulfur mustard (SM). A prophylactic agent for SM will be very useful for personnel engaged in the destruction of SM and during inspections by the Organization for the Prohibition of Chem. Weapons. Due to simple method of prepn., SM can be used clandestinely during war or by terrorist groups. Inspite of research over several decades no satisfactory prophylactic or treatment regimen has evolved for SM. Amifostine an organophosphorothioate, originally developed as a radioprotector, and its analogs were evaluated as a prophylactic agent for SM. Three analogs by varying the chain length and substitution at the sulfur atom were synthesized and coded as DRDE-06, DRDE-07 and DRDE-08. LD50 of amifostine and its analogs were estd. through i.p. route. For the protection studies, amifostine and its analogs were administered i.p. in mice, 30 min before dermal (percutaneous) application of SM. The dose of the prophylactic agent was 0.2 LD50 (i.p.) and that of SM was 152 mg/kg (undiluted) equal to 19-fold LD50 of SM. Amifostine and one of its analogs, DRDE-07 gave significant protection. Further studies were carried out using amifostine and DRDE-07, and both of them significantly protected mice against SM (155 mg/kg, in PEG 300, equal to 19 LD50) when they were administered i.p. either 30 min before or simultaneously. LD50 of amifostine and DRDE-07 were also estd. through the oral route (1049 or 1248 mg/kg, resp.). Prophylactically administered amifostine and DRDE-07 (0.2 LD50, p.o.) significantly protected the mice against dermally applied SM (155 mg/kg, in PEG 300, equal to 19 LD50). The protection offered by DRDE-07 was better than that of amifostine by the oral route. DRDE-07 (0.2 LD50, p.o.) also protected significantly with respect to the decrease in body wt. and the depletion of GSH induced by SM.
DNA damage induced by SM was also significantly reduced by amifostine and DRDE-07 (0.2 LD50, p.o.). Further studies are in progress on the various pharmacol. and toxicol. properties of DRDE-07.

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Adsorption of Organic Contaminants from Water Using Tailored ACFs. Mangun, Christian L.; Yue, Zhongren; Economy, James; Maloney, Stephen; Kemme, Patricia; Cropek, Donald. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, USA. Chemistry of Materials (2001), 13(7), 2356-2360. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 135:200059 AN 2001:428900 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Six activated carbon fibers (ACFs) with different chem. and phys. properties were prepd. by 1st curing a phenolic resin-coated glass fiber, followed by activation and post-treatment. Their adsorption properties were studied to evaluate the removal of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and the chem. warfare simulants diisopropylmethyl phosphonate (DIMP) and half mustard (HM) from water. The adsorption isotherms showed that ACF SL-2 (activated with CO2/H2O at 800) has a higher adsorption capacity for BTEX, DIMP, and HM than other ACFs. This suggests that the high adsorption affinity of SL-2 is related to its higher surface area, larger av. micropore size of 11.6 .ANG. (esp. effective for the adsorption of DIMP), and lower O content of the surface. The adsorption isotherms are well represented by the Freundlich equation. For BTEX, the adsorption parameters based on C coating showed that, in all cases, ACFs have a higher K value than the best available data obtained on granulated activated C. The adsorption isotherms of DIMP and HM on ACFs are presented.

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The U.S. Army reactive topical skin protectant (rTSP): challenges and successes. Hobson, Stephen T.; Lehnert, Erich K.; Braue, Ernest H., Jr. Drug Assessment Division, U. S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Materials Research Society Symposium Proceedings (2001), 628(Organic/Inorganic Hybrid Materials), CC10.8.1-CC10.8.8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 135:118044 AN 2001:354344 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In 1994, the U.S. Army initiated a research effort towards an effective material that acts both as a protective barrier and as an active destructive matrix against chem. warfare agents (CWA). We report results on our prepn. and evaluation of Reactive Topical Skin Protectants (rTSP's). These creams are composite materials consisting of a base material (TSP) and a reactive moiety. Using an established base of perfluorinated-polyether and perfluoropolyethylene solids we incorporated over 60 reactive components. Classes tested include org. polymers, org./inorg. hybrid materials, polyoxometallates (POM's), enzymes, inorg. oxides, metal alloys and small mols. We characterized these materials by light microscopy and FTIR. We detd. the efficacy of these materials against both sulfur mustard (HD) and a representative nerve agent, soman (GD), using a penetration cell model coupled to a continuous air monitor and also by in vivo testing. Composite materials with optimum reactive compds. exhibit a 94% redn. of GD vapor break-through after 20 h (from 9458 ng to 581 ng) and a 3.6 fold increase (from 162 min to 588 min) in the time 1000 ng of GD liq. penetrates through the material. Similar composite materials show a 99% redn. in HD vapor break-through after 20 h (from 4040 ng to 16 ng), a 2.3 fold increase (from 524 min to > 1200 min) in the time 1000 ng of HD vapor penetrates through the material, and an elimination of erythema vs. control in an HD vapor challenge. These results indicate that an rTSP that protects against sulfur mustard and nerve agents is within reach.

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Inhibition and promotion of combustion by organophosphorus compounds added to flames of CH4 or H2 in O2 and Ar. Korobeinichev, O. P.; Bolshova, T. A.; Shvartsberg, V. M.; Chernov, A. A. Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia. Combustion and Flame (2001), 125(1/2), 744-751. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 134:328437 AN 2001:309769 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Early in evaluating the destruction mechanisms of a no. of organophosphorus compds. (OPCs), such as tri-Me phosphate (TMP), di-Me methylphosphonate, and diisopropyl methylphosphonate, in connection with the disposal of chem. warfare agents, the promotion and inhibition effects of OPCs on stabilized flat flames of H2 +O2 were studied. Because OPCs were demonstrated to be more effective fire suppressants than CF3Br (Halon 1301) and due to the need for replacing the currently used Halon 1301, further investigation of the effects of the OPCs on flames is of interest. Thus a lean flame of CH4/O2/Ar (0.078/0.222/0.7) with and without TMP added, stabilized on a flat burner at 0.1 bar, was studied by mol. beam mass spectrometry (MBMS) and computer modeling using PREMIX and CHEMKIN codes. An exptl. study of this flame revealed that TMP increases the width of the reaction zone by inhibiting the flame.

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An Infrared Study of Adsorbed Organophosphonates on Silica: A Prefiltering Strategy for the Detection of Nerve Agents on Metal Oxide Sensors. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2001), 17(7), 2213-2218. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 134:349067 AN 2001:156303 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The gas-phase adsorption of the nerve gas simulant di-Me methylphosphonate (DMMP) along with tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on silica have been studied using IR spectroscopy. Each phosphonate compd. adsorbs through a different no. of H-bonds of the methoxy and P:O moieties with the surface hydroxyl groups on silica. The strength of the adsorption depends on the no. and type of the H-bonds and follows the order TCP < MDCP < DMMP < TMP. TCP is completely removed from silica by evacuation at room temp., adsorbed MDCP is removed by evacuation at 150 C, DMMP requires an evacuation temp. of 300 C, and TMP is eliminated at 400 C. All phosphonate compds. molecularly desorb, and the silica returns to its original state. The differences in the reactivity of phosphonate compds. on silica from other oxides demonstrate the potential use of silica in prefiltering/preconcg. strategies for semiconductive metal oxide based sensing devices. Specifically, it is shown that silica can be used to selectively adsorb DMMP from a gas stream contg. methanol/DMMP mixts.

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Reactions of VX, GB, GD, and HD with Nanosize Al2O3. Formation of Aluminophosphonates. Wagner, George W.; Procell, Lawrence R.; O'Connor, Richard J.; Munavalli, Shekar; Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA. Journal of the American Chemical Society (2001), 123(8), 1636-1644. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 134:276643 AN 2001:85006 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of VX, GB, GD, and HD with nanosize Al2O3 (AP-Al2O3) have been characterized by 31P, 13C, and 27Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH3)OR]3, are generated which are identical to synthesized model compds. Thus, the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amt. of the CH-TG sulfonium ion (12%), although some elimination of HCl is also obsd. (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addn. of excess water results in the quant. hydrolysis of sorbed HD to CH-TG. On AP-Al2O3 dried to remove physisorbed water, 13C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

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New microemulsions for oxidative decontamination of mustard gas analogues and polymer-thickened half-mustard. Gonzaga, Ferdinand; Perez, Emile; Rico-Lattes, Isabelle; Lattes, Armand. Laboratoire des Interactions Moleculaires et Reactivite Chimique et Photochimique (CNRS UMR 5623), Universite Paul Sabatier, Toulouse, Fr. New Journal of Chemistry (2001), 25(1), 151-155. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 134:232826 AN 2001:12053 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidn. of mustard gas analogs in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quant. and chemoselective oxidn. of the analogs. In a second formulation, the choice of microemulsion components used allowed us to study the oxidn. of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aq. systems.

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Bacterial release of arsenic ions and organoarsenic compounds from soil contaminated by chemical warfare agents. Kohler, Manfred; Hofmann, Klaus; Volsgen, Fernando; Thurow, Kerstin; Koch, Andreas. URST Umwelt- und Rohstoff-Technologie GmbH, Greifswald, Germany. Chemosphere (2000), Volume Date 2001, 42(4), 425-429. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 134:60919 AN 2000:878002 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The objective was to study possible participation of microorganisms in the release of sol. arsenical compds. from organoarsenic warfare agents in contaminated soil. A no. of bacterial strains were isolated with high resistance against As5+ ions which are able to degrade the water insol. compds. triphenylarsine (TP) and triphenylarsineoxide (TPO). Release of As and sol. organoarsenic compds. from soil by the activity of autochthonic soil bacteria and a mixt. of the isolated pure cultures was demonstrated by percolation expts. with undisturbed soil samples (core drills) from the contaminated site. This release increased after addnl. of nutrients (mineral N and P, Na acetate and ethanol) and is nearly independent of the percolation temp. (5 and 22). These results show that bacteria play an important role in the release of arsenical compds. from organoarsenic warfare agent contaminated soil. This release is limited by shortage of water and, above all, of nutrients for the microorganisms in the sandy forest soil. These results are important both for the management and security and possibly for bioremediation of military waste sites contg. similar contaminations.

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The chemistry of the destruction of organophosphorus compounds in flames-IV: destruction of DIMP in a flame of H2 + O2 + Ar. Korobeinichev, O. P.; Chernov, A. A.; Bolshova, T. A. Institute of Chemical Kinetics and Combustion, Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia. Combustion and Flame (2000), 123(3), 412-420. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 133:285779 AN 2000:714913 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mol. beam mass spectrometry with electron impact ionization at 11-70 eV and an electron energy spread of  0.25 eV was used to study the structure of a premixed H2/O2/Ar (0.26/0.13/0.61) flame without any additives and with 0.14% of diisopropylmethylphosphonate (DIMP), stabilized on a flat-flame burner at 62 mbar. Stable species (H2, O2, H2O), as well as atoms and radicals (H, O, OH) were monitored, including phosphorus-contg. compds.: DIMP and some intermediates of its destruction, phosphorus oxides and acids. The profiles of the mole fractions of most species, including those of atoms and free radicals were obtained. The calibration coeffs. for some species were detd. exptl., and estd. for others. Isopropylmethylphosphonate was detected as a main primary phosphorus-contg. product of the destruction of DIMP. It has been shown that bimol. reactions with hydroxyl radicals and hydrogen atoms, rather than a unimol. decompn., provide the crucial initial steps in the destruction of DIMP. A detailed mechanism for the destruction of DIMP in H2/O2/Ar flames is suggested.

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Cytotoxicity of the MEIC reference chemicals in rat hepatoma-derived Fa32 cells. Dierickx, P. J. Laboratorium Biochemische Toxikologie, Afdeling Toxikologie, Instituut voor Volksgezondheid, Brussels, Belg. Toxicology (2000), 150(1-3), 159-169. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 134:1437 AN 2000:660792 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The cytotoxicity of the MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) ref. chems. was investigated in rat hepatoma-derived Fa32 cells. The total protein content was measured as an endpoint after exposure times of 30 min and 24 h, both in normal and glutathione-depleted cells. The neutral red uptake inhibition and the MTT conversion were also measured after 30 min. On av., the cytotoxicity was higher in glutathione-depleted cells when compared to normal cells, and was lower after 30 min than after 24 h. Evidence was obtained for lysosomal attack (of five chems.) or mitochondrial dysfunction (of six chems.) as the primary intoxication mechanism. Malathion and mercuric chloride belong to both series of chems. Good to excellent correlations were obsd. when the 50% inhibitory concns. of the six different in vitro assays were compared. When the six in vitro assays in Fa32 cells were compared with the human toxicity, the correlation coeff. was almost always identical to that obtained previously in human hepatoma-derived Hep G2 cells. The latter was the best acute in vitro assay for the prediction of human toxicity within the MEIC study. Altogether the results integrate very well with the basal cytotoxicity concept (B. Ekwall; 1995).

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The role of time in toxicology or Haber's ct product. Rozman, K. K. Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA. Toxicology (2000), 149(1), 35-42. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 133:306404 AN 2000:589244 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It happened exactly 100 yr ago that Warren established for the first time a quant. link between dose and time while studying the toxicity of sodium chloride in Daphnia magna (Straus). During this century many toxicologists in different contexts returned to this idea, which has become known as Haber's rule of inhalation toxicol. Most attempts to explore this relationship ended in frustration because of the supposed occurrence of exceptions. Thus, toxicologists concd. on the quant. relationship between dose and effect under mostly isotemporal conditions while time took a back seat and was assigned such arbitrary, semiquant. designations as acute, subacute, subchronic and chronic. Time itself as a quantifiable variable of toxicity was seldom studied and when it was studied, it was often not under isodosic (steady state) conditions as required by theory. A recent anal. of toxicol. time indicated the impact of three independent time scales (toxicokinetic, toxicodynamic, exposure frequency/duration) in toxicol. studies, which interact with dose and effect to yield the enormous complexity known to every toxicologist. Based on prototypical examples when toxicokinetic (dioxins), toxicodynamic (nitrosamines, benzene) or exposure frequency (methylene chloride, chloroacetic acid, HgCl2, CdCl2, etc.) represent the crit. time scale, the general validity of the ct=k concept will be discussed as a starting point for a theory of toxicol. As endpoints of toxicity, (delayed) acute toxicity, blood dyscrasias and cancer will be used to illustrate the crit. conditions needed to demonstrate the validity of this theory.

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Detection of Fluorophosphonate Chemical Warfare Agents by Catalytic Hydrolysis with a Porous Silicon Interferometer. Sohn, Honglae; Letant, Sonia; Sailor, Michael J.; Trogler, William C. Department of Chemistry and Biochemistry, University of California at San Diego, CA, USA. Journal of the American Chemical Society (2000), 122(22), 5399-5400. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 133:100551 AN 2000:335868 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The detection of a fluorophosphonate nerve chem. warfare agent can be achieved with an oxidized porous silicon interferometer film contg. a Cu(II) hydrolysis catalyst and surfactant (CTAB). Hydrolysis of the nerve agent produces HF gas, which removes the silicon oxide as SiF4(g) and induces both a blue-shift and a decrease in intensity of the Fabry-Perot fringes. Significant changes in these 2 parameters are detected after 5 min of DFP vapor (800 ppm) exposure.

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Reactions of VX, GD, and HD with Nanosize CaO: Autocatalytic Dehydrohalogenation of HD. Wagner, George W.; Koper, Olga B.; Lucas, Erik; Decker, Shawn; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, MD, USA. Journal of Physical Chemistry B (2000), 104(21), 5118-5123. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 133:30783 AN 2000:281288 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of the chem. warfare agents VX, GD, and HD with nanosize CaO (AP-CaO), and HD with com. CaO were studied using solid-state MAS NMR. VX and GD hydrolyze to yield surface-bound complexes of nontoxic Et methylphosphonate and pinacolyl methylphosphonate, resp. The kinetics were characterized by an initial fast reaction followed by a slower, diffusion-limited reaction. Similar behavior is obsd. for HD on either dried or hydrated AP-CaO and CaO. On partially hydrated AP-CaO (but not CaO), a rather fast steady-state elimination of HCl occurs after an induction period. This behavior is attributed to acid-catalyzed surface reconstruction (to regenerate fresh surface) and the formation of CaCl2, which is known to be more reactive than CaO. The product distribution for HD is .apprx.80% divinyl sulfide and 20% thiodiglycol and/or sulfonium ions, which apparently reside as surface alkoxides. Such kinetic behavior was not evident for the common mustard simulant 2-chloroethyl Et sulfide (CEES) on partially hydrated AP-CaO, which exhibited only the typical fast/diffusion-limited reaction.

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Design and synthesis of an ,-difluorophosphinate hapten for antibody-catalyzed hydrolysis of organophosphorus nerve agents. Vayron, Philippe; Renard, Pierre-Yves; Valleix, Alain; Mioskowski, Charles. CEA, Service des Molecules Marquees, CE-Saclay, Gif sur Yvette, Fr. Chemistry--A European Journal (2000), 6(6), 1050-1063. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 133:13524 AN 2000:214064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In a new approach to the safe neutralization of organophosphorus chem. weapons, we designed a hapten to elicit catalytic antibodies with phosphatase activity. Here we report the synthesis of this ,-difluorophosphinate hapten 6. Various methods for the introduction of the key ,-difluoromethyl feature into the phosphinate hapten are discussed. The best results were obtained with the electrophilic gem-difluorinating agent N-fluorobenzenesulfonimide.

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Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate. Richardson, David E.; Yao, Huirong; Frank, Karen M.; Bennett, Deon A. Center for Catalysis Department of Chemistry, University of Florida, Gainesville, FL, USA. Journal of the American Chemical Society (2000), 122(8), 1729-1739. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 132:222157 AN 2000:94955 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Bicarbonate ion is an effective activator for hydrogen peroxide in the oxidn. of sulfides. Kinetic and spectroscopic results support the formation of peroxymonocarbonate ion (HCO4-) as the oxidant in the catalytic reactions. The reaction of hydrogen peroxide and bicarbonate to form HCO4- occurs rapidly at 25 (t1/2  300 s) near neutral pH in aq. soln. and alc./water mixts., and an equil. anal. of the reaction by 13C NMR leads to an est. of the electrode potential for the HCO4-/HCO3- couple (1.8 V vs NHE). Soly. of the bicarbonate catalyst is enhanced by the use of NH4HCO3 rather than by the use of group 1 salts, which tend to have lower soly. in the mixed solvents and can lead to phase sepn. Rate laws and mechanistic analyses are presented for the oxidn. of Et Ph sulfide and related sulfides. The second-order rate consts. for sulfide oxidns. by HCO4- are .apprx.300-fold greater than those for H2O2, and this increase is consistent with expectations based on a Bronsted anal. of the kinetics for other heterolytic peroxide oxidns. At high concns. of H2O2, a pathway that is second order in H2O2 is significant, and this path is interpreted as a general acid catalysis by H2O2 of carbonate displacement accompanying substrate attack at the electrophilic oxygen of HCO4-. Increasing water content up to 80% in the solvent increases the rate of oxidn. The BAP (bicarbonate-activated peroxide) oxidn. system is a simple, inexpensive, and relatively nontoxic alternative to other oxidants and peroxyacids, and it can be used in a variety of oxidns. where a mild, neutral pH oxidant is required. Variation of bicarbonate source and the cosolvent can allow optimization of substrate soly. and oxidn. rates for applications such as org. synthesis and chem. warfare agent decontamination.

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Synthesis and Characterization of a Functionalized Double-Chain Surfactant and Its Cleavage of O-Methyl S-Benzyl Phenylphosphonothioate. Jaeger, David A.; Li, Bei. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (2000), 16(1), 5-10. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 132:24141 AN 1999:379097 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant 2-hydrazino-N-methyl-N,N-didodecyl-2-oxoethanaminium bromide (I) was synthesized, and its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry. In a pH 9.0 borate buffer at 25, vesicular I and O-Me S-benzyl phenylphosphonothioate (II), a simulant for the chem. warfare agent VX [O-Et S-(2-N,N-diisopropylamino)ethyl methylphosphonothioate] reacted to give anion S-benzyl phenylphosphonothioate (III) and 3 cations (2-(2-N-methylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, 2-(2-N,N-dimethylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, and 2-[1-hydroxy-2-(N-methyl-N,N-didodecylammonio)ethylidene]-N',N',N'-trimethylhydrazinium, resp.) by SN2 substitution on the Me group of II. This reaction was accompanied by the pptn. of anion III with surfactant cations, which resulted in wounding/destruction of the vesicles. The combination of vesicle damage and reaction of II suggests the potential of vesicular systems for simultaneous signaling and decontamination of chem. agents. Ester II hydrolyzed in 0.10 M NaOH at 25 to give anions III and O-Me phenylphosphonothioate in a 38:62 ratio, resp.

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Reactivation kinetics of acetylcholinesterase from different species inhibited by highly toxic organophosphates. Worek F; Reiter G; Eyer P; Szinicz L Sanitatsakademie der Bundeswehr, Institut fur Pharmakologie und Toxikologie, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2002 Sep), 76(9), 523-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242610 AN 2002479746 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Standard treatment of poisoning by organophosphates (OP) includes the administration of an antimuscarinic agent, e.g. atropine, and of an acetylcholinesterase (AChE) reactivator (oxime). The presently available oximes, obidoxime and pralidoxime (2-PAM), are considered to be insufficient for highly toxic OPs, e.g. sarin. In the past decades numerous oximes were prepared and tested for their efficacy in OP poisoning, mostly in animal experiments. However, data indicate that the reactivating potency of oximes may be different in humans and animal species, which may hamper the extrapolation of animal data to humans and may pose a problem in the drug licensing of new compounds. In order to provide data for a better evaluation of the reactivating potency of oximes, experiments were undertaken to determine the reactivation rate constants of several oximes with human, rabbit, rat and guinea-pig AChE inhibited by the OPs sarin, cyclosarin and VX. The results show marked differences among the species, depending on the inhibitor and on the oxime, and indicate that the findings from animal experiments need careful evaluation before extrapolating these data to humans.

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Skin toxicokinetics of mustard gas in the guinea pig: effect of hypochlorite and safety aspects. Wormser Uri; Brodsky Berta; Sintov Amnon Faculty of Sciences,The Hebrew University, Edmond Safra Campus, Givat Ram, Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2002 Sep), 76(9), 517-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242609 AN 2002479745 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (SM, mustard gas) is a chemical warfare vesicant that rapidly penetrates the skin due to its hydrophobicity. This study measured the rate of SM disappearance from the skin after topical application of the vesicant. In both fur-covered and hairless animals, the remaining toxicant levels measured 60 min after exposure to undiluted SM were 0.6% and 0.3%, respectively, of the initially applied SM amount. However, SM concentration reached 0.4% of the initial dose 3 h following exposure in female fur-covered guinea pigs. SM quantities extracted from skin of male fur-covered and hairless guinea pigs immediately after 16 min of exposure to SM vapor were 12.2 and 21.8 microg, respectively; levels declined to 1.6 and 1.7 microg at 30 and 15 min following termination of exposure of male fur-covered and hairless guinea pigs, respectively. Three swabbing treatments of undiluted SM-exposed skin with gauze pads soaked in 0.5% hypochlorite caused 68% reduction in skin SM content. Similar findings were obtained when hypochlorite was replaced by water (64% reduction). SM content in the gauze pads was 59, 38 and 25 microg, respectively, for the first, second and third decontamination processes with water. No SM was detected in the gauze pads soaked with hypochlorite. In vitro studies showed that incubation of SM with 0.5% hypochlorite at a ratio of 10:1 (v/v) did not cause SM inactivation, whereas 4% hypochlorite reduced SM levels by 17%. However, at a decontaminant:SM ratio of 1000:1, 0.5% and 4% hypochlorite reduced SM levels by 92% and 99%, respectively. These findings are important for health authorities and regulatory agencies in planning precautionary steps to be taken in case of emergency and in routine laboratory work.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock Shannon D; Till Gerd O; Smith Milton G; Ward Peter A Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602, USA Journal of applied toxicology : JAT (2002 Jul-Aug), 22(4), 257-62. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12210543 AN 2002449749 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The chemical warfare agent analog, 2-chloroethyl ethyl sulfide, known as 'half-mustard gas' (HMG), is less toxic and less of an environmental hazard than the full molecule and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of (125)I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, we observed significant attenuation of the pulmonary injury when experimental animals were complement or neutrophil depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, dimethyl sulfoxide, dimethyl thiourea, resveratrol and N-acetyl-L-cysteine (NAC). The last compound showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement mediated pathways and the generation by neutrophils of toxic oxygen species The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat. Copyright 2002 John Wiley & Sons, Ltd.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber Ellen; McGuire Raymond Environment Protection Department, Lawrence Livermore National Laboratory, University of California, P.O. Box 808, L-626, Livermore, CA 94551, USA Journal of hazardous materials (2002 Aug 5), 93(3), 339-52. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12137994 AN 2002389537 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A decontamination method has been developed using a single reagent that is effective both against chemical warfare (CW) and biological warfare (BW) agents. The new reagent, "L-Gel", consists of an aqueous solution of a mild commercial oxidizer, Oxone, together with a commercial fumed silica gelling agent, Cab-O-Sil EH-5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. The new reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Experiments to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Laboratory and independently at four other locations. L-Gel was tested against all classes of chemical warfare agents and against various biological warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biological agents. Testing showed that L-Gel is as effective against chemical agents and biological materials, including spores, as the best military decontaminants.

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Adamantyl tenocyclidines--adjuvant therapy in poisoning with organophosphorus compounds and carbamates. Erratum in: Arch Toxicol 2002 Sep;76(9):552 Skare Danko; Radic Bozica; Lucic Ana; Peraica Maja; Domijan Ana-Marija; Milkovic-Kraus Sanja; Bradamante Vlasta; Jukic Ivan Institute Ruder Boskovic, Bijenicka c. 54, 10000 Zagreb, Croatia. skare@rudjer.irb.hr Archives of toxicology (2002 Apr), 76(3), 173-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11967623 AN 2002328057 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The objective of this study was to evaluate the efficacy of thienyl phencyclidine (tenocyclidine, TCP) and its newly synthesized adamantyl derivatives containing piperidine (TAPIP), pyrolidine (TAPIR) and morpholine (TAMORF) groups, which were tested with or without standard therapy in mice poisoned with organophosphates (OPs) and carbamates. These compounds with potential activity at the N-methyl- D-aspartate and muscarinic receptors showed low acute toxicity, having LD50 values varying from 106.00 mg/kg (TCP) to >504.00 mg/kg body weight (TAMORF). TCP and its adamantyl derivatives were administered intraperitoneally (2.5 mg/kg body weight) together with atropine (10.0 mg/kg body weight) and with or without 1/4 LD50 of the oxime HI-6. Each compound administered with atropine had a therapeutic effect against poisoning with carbamates propoxur, aldicarb and Ro 02-0683 (protective ratio of tenocyclidines was from 3.99 LD50 of aldicarb to >16.00 LD50 for propoxur). However, the efficacy of those compounds in combination with atropine was lower against poisoning with the OP insecticide dichlorvos (DDVP) and chemical warfare agents soman and tabun. In soman-poisoned mice, the best therapeutic effects were obtained with the combination of HI-6 plus atropine and test compounds, with protective ratios being from 5.40 to 7.12 LD50 of soman. The results suggest that TCP and adamantyl tenocyclidines could be used in combination with atropine as antidotes in carbamate poisoning and as adjuvant therapy to HI-6 and atropine in soman poisoning.

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Site-specific percutaneous absorption of methyl salicylate and VX in domestic swine. Duncan E J Scott; Brown April; Lundy Paul; Sawyer Thomas W; Hamilton Murray; Hill Ira; Conley John D Chemical Biological Defence Section, Defence Research Establishment, Suffield, PO Box 4000, Station Main, Medicine Hat, Alberta, Canada T1A 8K6 Journal of applied toxicology : JAT (2002 May-Jun), 22(3), 141-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12015792 AN 2002313565 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The site specificity of the percutaneous absorption of methyl salicylate (MeS) and the organophosphate nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) was examined in anaesthetized domestic swine that were fully instrumented for physiological endpoints. Four different anatomical sites (ear, perineum, inguinal crease and epigastrium) were exposed to the MeS and the serum levels were measured over a 6-h time period. The dose absorbed at the ear region was 11 microg cm(-2) with an initial flux of 0.063 microg cm(-2)min(-1), whereas at the epigastrium region the dose absorbed was 3 microg cm(-2) with an initial flux of 0.025 microg cm(-2)min(-1). For this reason further studies were carried out with VX on the ear and the epigastrium only. In animals treated with agent on the epigastrium, blood cholinesterase (ChE) activity began to drop 90 min after application and continued to decline at a constant rate for the remainder of the experiment to ca. 25% of awake control activity. At this time there were negligible signs of poisoning and the medical prognosis was judged to be good. In contrast, the ChE activity in animals receiving VX on the ear decreased to 25% of awake control values within 45 min and levelled out at 5-6% by 120 min. Clinical signs of VX poisoning paralleled the ChE inhibition, progressing in severity over the duration of the exposure. It was judged that these animals would not survive. The dramatic site dependence of agent absorption leading to vastly different toxicological endpoints demonstrated in this model system has important ramifications for chemical protective suit development, threat assessment, medical countermeasures and contamination control protocols. Copyright 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

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An improved brain slice model of nerve agent-induced seizure activity. Wood S J; Tattersall J E Biomedical Sciences Department, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S83-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920926 AN 2002191151 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice preparation. Soman (1 microM) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists, but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice preparation is a suitable model for investigating the origin and propagation of nerve-agent-induced seizures within the limbic system. Copyright 2001 John Wiley & Sons, Ltd.

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Cardiopulmonary effects of HI-6 treatment in soman intoxication. Goransson-Nyberg A; Cassel G Division of NBC Defence, Department of Medical Counter Measures, Swedish Defence Research Agency, SE-90182 Umea, Sweden Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S79-81. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920925 AN 2002191150 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The cardiopulmonary effects of HI-6, together with atropine and soman, were studied in the rat. HI-6 is an effective antidote in acute poisoning with the nerve agent soman. The therapeutic efficiency of HI-6 is still unclear and cannot be explained entirely by the HI-6 reactivating ability of acetylcholinesterase (AChE). Other non-cholinergic factors must be involved. One possible detoxifying process might be an effect of HI-6 on the blood flow to sensitive organs. The purpose of the present study was to investigate 1) whether soman per se induces changes in regional blood flow and 2) whether the blood flow to different organs is affected when HI-6 (50 mg x kg(-1) i.m.) and atropine (10 mg x kg(-1) i.m.) are given either before or immediately after soman intoxication (90 microg x kg(-1) s.c.). For regional blood flow determinations the microsphere method was used with male Wistar rats weighing 300-400 g. The rats were anaesthetised and breathed spontaneously during the experiment. Three different blood flow measurements were made in the same animal and concomitant physiological parameters such as mean arterial blood pressure and respiratory rate were recorded. The blood AChE activity was followed throughout the experiment. Our results show that when HI-6 is given after intoxication with soman, dramatic changes in blood flow occur with a significant decrease in both respiratory rate and blood AChE activity. If HI-6 is given prior to the intoxication, however, all rats are unaffected and none of the parameters measured are changed. Copyright 2001 John Wiley & Sons, Ltd.

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Prophylaxis against organophosphate poisoning by sustained release of scopolamine and physostigmine. Meshulam Y; Cohen G; Chapman S; Alkalai D; Levy A Department of Pharmacology, Israel Institute for Biological Research (IIBR), PO Box 19, 70450 Ness-Ziona, Israel Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S75-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920924 AN 2002191149 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Protection efficacy of continuous prophylactic administration of physostigmine and scopolamine against sarin-induced toxicity was evaluated previously in guinea pigs. The present study in large animals used Beagle dogs, that serve as an animal model with cholinergic sensitivity similar to that of humans. Pretreatment with physostigmine salicylate and scopolamine hydrochloride at dose rates of 2.5 and 1 microg x kg(-1) x h(-1), respectively, was administered via Alzet mini-osmotic pumps. At the time of exposure, the physostigmine salicylate concentration in plasma was 0.7 ng x ml(-1) and the scopolamine hydrochloride concentration was ca. 0.2 ng x ml(-1), both of which are levels known to be well tolerated in humans. Whole-blood cholinesterase inhibition was 15-20%. This regimen conferred full protection against 2.5 x LD50 i.v. of sarin. Albeit the high-dose exposure, cholinergic toxicity symptoms were mild with no convulsions. About 11-14 min following poisoning the treated animals started to walk and 15-20 min following exposure full recovery was observed and the dogs behaved normally. With higher dose rates of physostigmine salicylate and scopolamine hydrochloride, at plasma concentrations of 2.1 and 0.6 ng x ml(-1), respectively, treated dogs regained normal posture 6-10 min after exposure. Copyright 2001 John Wiley & Sons, Ltd.

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Intramuscular diazepam pharmacokinetics in soman-exposed guinea pigs. Capacio B R; Whalley C E; Byers C E; McDonough J H Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S67-74. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920923 AN 2002191148 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Intramuscular (i.m.) diazepam is included by the US military as an anticonvulsant in the standard therapeutic regimen for organophosphorus nerve agent intoxication. In this study we investigated the pharmacokinetics of diazepam after i.m. administration while monitoring pharmacodynamic (electroencephalogram, EEG) data in soman-exposed guinea pigs. Prior to experiments the animals were surgically implanted with EEG leads to monitor seizure activity. For the study, animals were administered pyridostigmine (0.026 mg x kg(-1) i.m.) 30 min prior to soman (56 microg x kg(-1), 2 x LD50; subcutaneously, s.c.), which was followed in 1 min by atropine sulfate (2 mg x kg(-1) i.m.) and pralidoxime chloride (25 mg x kg(-1) i.m.). All animals receiving this regimen developed seizure activity. Diazepam (10 mg x kg(-1) i.m.) was administered 5 min after onset of seizure activity. Based on EEG data, animals were categorized as either seizure terminated or not terminated at 30 min after diazepam. Serial blood samples were obtained from each animal. Diazepam (10 mg x kg(-1) i.m.) terminated seizure activity in 52% of the animals within 30 min. The pharmacokinetics were characterized by a one-compartment model with first-order absorption and elimination. The maximum plasma concentrations (Cmax) were 991 and 839 ng x ml(-1) for seizure terminated and not terminated, respectively. Mean plasma concentrations of diazepam were significantly different (P < 0.05) for seizure terminated vs not terminated groups at 30 min. The plasma Cmax in seizure-terminated animals in this study is similar to the minimum range of plasma diazepam (200-800 ng x ml(-1)) reported to suppress seizure activity in humans. It has been reported in an earlier study that the minimum effective i.m. dose (0.1 mg x kg(-1)) required to prevent soman-induced convulsions in Rhesus monkeys produces a mean Cmax of 50 ng x ml(-1) for diazepam.
The data from our current study suggest that a higher dose (and corresponding Cmax) is necessary to terminate ongoing seizure activity. Copyright 2001 John Wiley & Sons, Ltd.

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Combination anticonvulsant treatment of soman-induced seizures. Koplovitz I; Schulz S; Shutz M; Railer R; Macalalag R; Schons M; McDonough J Drug Assessment Division, US Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010, USA. Koplovitz@asia.apgea.army.mil Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S53-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920921 AN 2002191147 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures. Copyright 2001 John Wiley & Sons, Ltd.

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Soman-induced seizures: limbic activity, oxidative stress and neuroprotective proteins. Pazdernik T L; Emerson M R; Cross R; Nelson S R; Samson F E Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City, KS 66160, USA. tpazdern@kumc.edu Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S87-94. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920927 AN 2002185330 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman, a potent acetylcholinesterase inhibitor, induces status epilepticus in rats followed by conspicuous neuropathology, most prominent in piriform cortex and the CA3 region of the hippocampus. Cholinergic seizures originate in striatal-nigral pathways and with fast-acting agents (soman) rapidly spread to limbic related areas and finally culminate in a full-blown status epilepticus. This leads to neurochemical changes, some of which may be neuroprotective whereas others may cause brain damage. Pretreatment with lithium sensitizes the brain to cholinergic seizures. Likewise, other agents that increase limbic hyperactivity may sensitize the brain to cholinergic agents. The hyperactivity associated with the seizure state leads to an increase in intracellular calcium, cellular edema and metal delocalization producing an oxidative stress. These changes induce the synthesis of stress-related proteins such as heat shock proteins, metallothioneins and heme oxygenases. We show that soman-induced seizures cause a depletion in tissue glutathione and an increase in tissue 'catalytic' iron, metallothioneins and heme oxygenase-1. The oxidative stress induces the synthesis of stress-related proteins, which are indicators of 'stress' and possibly provide neuroprotection. These findings suggest that delocalization of iron may catalyze Fenton-like reactions, causing progressive cellular damage via free radical products. Copyright 2001 John Wiley & Sons, Ltd.

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Beneficial effects of TCP on soman intoxication in guinea pigs: seizures, brain damage and learning behaviour. de Groot D M; Bierman E P; Bruijnzeel P L; Carpentier P; Kulig B M; Lallement G; Melchers B P; Philippens I H; van Huygevoort A H TNO Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S57-65. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920922 AN 2002185328 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Poisoning with the potent nerve agent soman produces a cascade of central nervous system (CNS) effects characterized by severe convulsions and eventually death. In animals that survive a soman intoxication, lesions in the amygdala, piriform cortex, hippocampus and thalamus can be observed. In order to examine the mechanisms involved in the effects of soman and to evaluate possible curative interventions, a series of behavioural, electrophysiological and neuropathological experiments were carried out in the guinea pig using the NMDA antagonist N-[1-(2-thienyl)cyclohexyl] piperidine (TCP) in conjunction with atropine and pyridostigmine. The NMDA antagonist TCP appeared to be very effective in the treatment of casualties who suffered from soman-induced seizures for 30 min: (i)Seizures were arrested within minutes after the TCP injection, confirmed by quantitative electroencephalogram (EEG), after fast Fourier analysis. Three hours after TCP the quantitative EEGs were completely normal in all frequency bands and remained normal during the entire 3-week intoxication period. The power shift to the lower (delta) frequency bands, indicative for neuropathology and found in control animals intoxicated only by soman, was not observed in the soman-TCP group. (ii)The gross neuropathology found in soman control animals within 48 h after soman was prevented in soman-TCP animals and was still absent in 3-week survivors. Instead, ultrastructural changes were observed, indicative of defense mechanisms of the cell against toxic circumstances. (iii)Twenty-four hours after soman, soman-TCP animals were able to perform in the shuttle box and Morris water maze. The beneficial effects of TCP on the performance in these tests during the 3-week intoxication period were very impressive, notwithstanding (minor) deficits in memory and learning. (iv)The increase in excitability after TCP was confirmed by an increase in the acoustic startle response.
Taken together, these results confirmed the involvement of NMDA receptors in the maintenance of soman-induced seizures and the development of brain damage. They underline the current hypothesis that cholinergic mechanisms are responsible for eliciting seizure activity after soman and that, most likely, the subsequent recruitment of other excitatory neurotransmitters and loss of inhibitory control are responsible for the maintenance of seizures and the development of subsequent brain damage. Copyright 2001 John Wiley & Sons, Ltd.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw M D; Hayes T L; Miller T L; Shannon C M Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH 43201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S3-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920912 AN 2002185325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate--a V-type nerve agent developed by the former Soviet Union--in the environment is an important parameter in threat assessment analysis and for the determination of use, production, testing and storage of this chemical warfare agent. S-(N,N-Diethylaminoethyl) isobutyl methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same molecular formula, it is expected that their physical and chemical properties would be different. This preliminary investigation was undertaken to determine the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compound at approximately 1 mg x ml(-1) in unbuffered water at pH 7 was determined side-by-side. The half-lives for VXA and VX were determined to be 12.4 days and 4.78 days, respectively. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chemical Weapons Convention. Copyright 2001 John Wiley & Sons, Ltd.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller J K; Lenz D E Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD 21201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S23-6. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920916 AN 2002185323 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-molecular-weight compounds is effected by the use of chromatographic techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the analysis. To overcome those drawbacks, we have been involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds such as pinacolylmethyl phosphonofluoridate (soman), which is a chemical warfare agent. Prior estimates suggested that it is necessary to be able to detect soman at a concentration below 2.5 x 10(-7) M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The minimum required assay time was 2.0-2.5 h with no loss in sensitivity. To determine the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogues were 5 x 10(-7) M for 4-nitrophenylpinacolylmethylphosphonate, 8 x 10(-7) M for dipinacolylmethylphosphonate, 2 x 10(-6) M for diisopropylmethylphosphonate, 3 x 10(-5) M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5 x 10(-5) M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman molecule, were effective inhibitors. Compounds, which contained predominately aromatic groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to determine its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman. Copyright 2001 John Wiley & Sons, Ltd.

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Protective action of the serine protease inhibitor N-tosyl-L-lysine chloromethyl ketone (TLCK) against acute soman poisoning. Cowan F M; Broomfield C A; Lenz D E; Shih T M Biochemical Pharmacology and Neurotoxicology Branches, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 293-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481662 AN 2002027826 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman-poisoned rats display cholinergic crisis, a systemic mast cell degranulation characteristic of anaphylactic reactions and an excitotoxin-like sequential seizure and neuronal degeneration. The protection of guinea pigs from soman lethality by prophylactic administration of the serine protease inhibitor suramin suggests a possible proteolytic component in soman poisoning. The present study tested the effect of N-tosyl-L-lysine chloromethyl ketone (TLCK), an inhibitor of trypsin-like serine proteases, on soman-induced toxic signs (convulsions, righting reflex) and survival time. Nine control guinea pigs receiving 2 x LD(50) (56 microg kg(-1), s.c.) of soman immediately followed by a therapeutic dose of atropine sulfate (17.4 mg kg(-1) i.m.) experienced severe convulsions, and 8/9 lost the righting reflex. Six of these nine animals expired within 65 min; the three remaining animals survived 24 h to termination of the experiment. When a second group of animals were given TLCK (12 mg kg(-1), i.p.) 30 min prior to a 2 x LD(50) soman challenge and atropine-sulfate therapy, 5/9 experienced convulsions and only 3/9 lost the righting reflex. All nine animals survived beyond 4 h, with six surviving to 24 h. Compared with soman controls, prophylaxis with TLCK significantly prevented the loss of righting reflex (P = 0.05) and enhanced 4-h survival (P = 0.005). Although, convulsions were reduced and 24-h survival was improved in TLCK-treated animals, these results were not statistically significant. The protection from soman toxicity by chemically distinct protease inhibitors such as suramin and TLCK suggests a role for pathological proteolytic pathways in soman intoxication. Copyright 2001 John Wiley & Sons, Ltd.

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin. Chilcott R P; Jenner J; Hotchkiss S A; Rice P Department of Biomedical Sciences, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 279-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481660 AN 2002027824 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption. Copyright 2001 John Wiley & Sons, Ltd.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen J; Riikonen K; Nikmo J; Jappinen A; Nieminen K Air Quality Research, Finnish Meteorological Institute, Sahaajankatu 20 E, FIN-00810, Helsinki, Finland. jaakko.kukkonen@fmi.fi Journal of hazardous materials (2001 Aug 17), 85(3), 165-79. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11489522 AN 2001443815 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

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Effects of iodine on inducible nitric oxide synthase and cyclooxygenase-2 expression in sulfur mustard-induced skin. Nyska A; Lomnitski L; Maronpot R; Moomaw C; Brodsky B; Sintov A; Wormser U Laboratory of Experimental Pathology, National Institutes of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA. nyska@niehs.nih.gov Archives of toxicology (2001 Feb), 74(12), 768-74. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11305779 AN 2001394179 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

In a previous study we demonstrated the protective effect of topical iodine as postexposure treatment for sulfur mustard (SM) application. The iodine treatment results in significantly reduced inflammation and necrosis and increased epidermal hyperplasia. The expression and localization of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in paraffin-embedded skin samples from that study were evaluated in the present investigation. We compared the immunoreactivity of iNOS and COX-2 using five samples from each of the following four test sites: untreated control sites, SM-exposed sites, sites treated with iodine mixture 15 min after SM exposure, and sites treated with iodine 30 min after SM exposure. All animals were killed 2 days after irritant exposure. iNOS immunoreactivity was present only in skin sites exposed to SM without iodine treatment. The ulcerated skin was covered with a relatively thick band of exudate composed of iNOS-immunostained polymorphonuclear cells and macrophages. In untreated skin, COX-2 immunostaining was limited to the thin suprabasal epidermal layer. In SM-exposed skin, induction of COX-2 was noted in inflammatory cells located close to the site of epidermal injury. In skin sites treated with iodine 15 or 30 min after SM exposure, the regenerating hyperplastic epithelium showed moderate cytoplasmic staining localized to the epithelium overlying the basal layer. This pattern of staining was also present in the nearby dermal fibroblasts. Thus, in contrast to the skin samples exposed to SM without iodine treatment, the epidermal layer expressing immunohistochemical positivity for COX-2 was thicker and corresponded to the epidermal hyperplasia noted in samples treated with iodine. It is well documented that prostaglandins (PGs) promote epidermal proliferation, thereby contributing to the repair of injured skin. That the induction of the COX-2 shown in our study may also play a role in the healing process is indicated by the present evidence.
The results suggest that nitric oxide radicals (NO*) are involved in mediating the damage induced by the SM and that iodine-related reduction in acute epidermal inflammation is associated with reduced iNOS expression.

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Intervention of sulfur mustard toxicity by downregulation of cell proliferation and metabolic rates. Ray R; Benton B J; Anderson D R; Byers S L; Petrali J P US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. radharaman.ray@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S87-91. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428650 AN 2001371709 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chemical warfare compound HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37 degrees C) first in keratinocyte growth medium (KGM) containing BAPTA AM (10-40 microM) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concentration-dependent manner with some cellular degeneration above 30 microM (light microscopy). At 20-30 microM, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 54 +/- 5%), [3H]-uridine (RNA synthesis, 29 +/- 6%) and [14C]-valine (protein synthesis, 12 +/- 2%) as well as a lower protein content per culture (30 +/- 3%) compared with corresponding untreated controls. However, 20-30 microM BAPTA AM did not cause any demonstrable cytopathology based on morphological (electron microscopy) as well as biochemical (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser J; Meier H L Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S23-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428638 AN 2001371697 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chemical warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compounds in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell preparations were exposed to various concentrations of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these experiments suggest that, with increasing HD concentration and time, NHEK will fragment irrespective of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains constant over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concentration- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, respectively, is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concentrations that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price E O; Smith J R; Clark C R; Schlager J J; Shih M L Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S193-7. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428636 AN 2001371695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The continual threat of chemical and biological warfare has prompted the need for unambiguous analytical methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with hemoglobin and metallothioneine were conducted. In vitro experiments with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to determine the extent of alkylation and occurrence of HD cross-linking using the MALDI-ToF/MS technique. In a typical experiment, 50 ml of 5 mM HD in acetonitrile was added to an equal volume of 0.5 mM hemoglobin in deionized water followed by vortexing and incubation at room temperature. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES experiments. These results demonstrate that MALDI-ToF/MS is a useful analytical technique to investigate the interaction of HD with biomolecules and may be employed potentially as a diagnostic tool for the confirmation of exposure to chemical warfare agents.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers S; Anderson D; Brobst D; Cowan F Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S19-22. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428635 AN 2001371694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham J S; Reid F M; Smith J R; Stotts R R; Tucker E S; Shumaker S M; Niemuth N A; Janny S J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S161-72. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428630 AN 2001371689 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chemical warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clinical pathology findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liquid on the ventral surface for 2 h, generating six 3-cm diameter full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematology and serum chemistry examinations. Urine was collected in metabolism cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatography/mass spectrometry. Examination of clinical pathology parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clinically significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 microg ml(-1) with a mean of 2.14 microg ml(-1). Thiodiglycol concentrations were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml(-1). Mean levels remained 10-40 ng ml(-1) for the remainder of the 7-day observation period, with the highest individual concentration noted during this period of 132 ng ml(-1). Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other laboratory animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 week.
Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h. Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin M C; Ricketts K; Skvorak J P; Gazaway M; Mitcheltree L W; Casillas R P Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA. Michael.Babin@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S141-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428627 AN 2001371686 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quantitative edema response as well as histopathological and biochemical endpoints as measurements of inflammation and tissue damage following exposure to the chemical warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal separation. This study evaluated the protective effects of three of these pharmacological compounds when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver a subcutaneous dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 microl of a 195 mM (0.16 mg) solution of sulfur mustard (density = 1.27 g ml(-1); MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathological damage (necrosis, epidermal-dermal separation). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant reduction in edema (24%, 26% and 22%, respectively) from the positive control. Compared to HD-positive controls, hydrocortisone, indomethacin and olvanil caused a significant reduction in subepidermal blisters (71%, 52% and 57%, respectively) whereas only hydrocortisone produced a significant reduction in contralateral epidermal necrosis (41%). We show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins K B; Lodhi I J; Hurley L L; Hinshaw D B University of Michigan Medical School, Ann Arbor 48105, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S125-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428622 AN 2001371681 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chemical warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells (Toxicol. Appl. Pharmacol. 1996; 141: 568-583). Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFkappaB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFkappaB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 microM HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 microM buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 microM HD for 5-6 h. Externally applied GSH up to a concentration of 5 mM had no toxic effect on the cells. Mild toxicity was associated with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examined the hypothesis that HD may activate the nuclear transcription factor NFkappaB by performing EMSAs with nuclear extracts of endothelial cells following exposure to 0, 250 or 500 microM HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFkappaB binding to its consensus sequence induced by 500 microM HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFkappaB, although HD-induced activation of NFkappaB was partially suppressed by NAC at 5 h. Factor NFkappaB is an important transcription factor for a number of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFkappaB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFkappaB activity. The NFkappaB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction associated with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha M; Bowers W Jr; Kohl J; DuBose D; Walker J; Alkhyyat A; Wong G US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S101-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428619 AN 2001371678 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chemical warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl ethyl sulfide (CEES, 1-2 mg l(-1) min(-1)) in humidified air or to humidified air alone. Tissues were evaluated histologically, ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histology showed that CEES induced the separation of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histology and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1alpha (IL-1alpha), prostaglandin-E2 (PGE2) and especially IL-1 receptor antagonist (IL-1Ra) release (56,334 vs 84,614 pg ml(-1)), but decreased interleukin-6 (IL-6, 4,755 vs 351 pg ml(-1)). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracelluar IL-1alpha (371 vs 92 pg ml(-1)). Extracellular IL-1Ra greatly increased (2,375 vs 24,875 pg ml(-1)), whereas cellular levels decreased (16,5425 vs 96,625 pg ml(-1)). Extracellular (224 vs 68 pg ml(-1)) and intracellular (485 vs 233 pg ml(-1)) soluble interleukin-1 receptor H (sIL-1RII) decreased. Prostanglandin E2 increased (1,835 vs 2,582 pg ml(-1)), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57,000 vs 96,000 pg ml(-1)). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Correlation of a specific mitochondrial phospholipid-phosgene adduct with chloroform acute toxicity. Di Consiglio E; De Angelis G; Testai E; Vittozzi L Biochemical Toxicology Unit, Department of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita, Viale Regina Elena 299, I-00161, Rome, Italy Toxicology (2001 Feb 21), 159(1-2), 43-53. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11250054 AN 2001195862 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The dose and time dependence of formation of a specific adduct between mitochondrial phospholipid and phosgene have been determined in the liver of Sprague-Dawley (SD) rats as well as in the liver and kidney of B6C3F1 mice after dosing with chloroform. Rats were induced with phenobarbital or non-induced. Determination of tissue glutathione (GSH) and of serum markers of hepatotoxicity and nephrotoxicity was also carried out. With dose-dependence experiments, a strong correlation between the formation of the specific phospholipid adduct, GSH depletion and organ toxicity could be evidenced in all the organs studied. With non-induced SD rats, no such effects could be induced up to a dose of 740 mg/kg. Time-course studies with B6C3F1 mice indicated that the specific adduct formation took place at very early times after chloroform dosing and was concurrent with GSH depletion. The adduct formed during even transient GSH depletion (residual level: 30% of control) and persisted after restoration of GSH levels. Following a chloroform dose at the hepatotoxicity threshold (150 mg/kg), the elimination of the adduct in the liver occurred within 24 h and correlated with the recovery of ALT, which was slightly increased (12 times) after treatment. Following a moderately nephrotoxic dose (60 mg/kg), the renal adduct persisted longer than 48 h, when a 100% increase in blood urea nitrogen and a 40% increase in serum creatinine indicated the onset of organ damage. The formation of the adduct in the liver mitochondria of B6C3F1 mice was associated with the decrease of phosphatidyl-ethanolamine (PE), in line with previous results in rat liver indicating that the adduct results from the reaction of phosgene with PE. The adduct levels implicated the reaction of phosgene with about 50% PE molecules in the liver mitochondrial membrane of phenobarbital-induced SD rats and of about 10% PE molecules of the inner mitochondrial membrane of the liver of B6C3F1 mice.
The association of this adduct with the toxic effects of chloroform makes it a very good candidate as the primary critical alteration in the sequence of events leading to cell death caused by chloroform.

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The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats. Kassa J; Fusek J Purkyne Military Medical Academy, PO Box 35/T, 500 01, Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2000 Nov 23), 154(1-3), 67-73. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11118671 AN 2001083637 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.

[megalomania]

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Development of multifunctional perfluorinated polymer blends as an active barrier cream against chemical warfare agents. Hobson, Stephen T.; Braue, Ernest H., Jr. Drug Assessment Div., U.S. Army Medical Research Institute for Chemical Defense, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 80-81. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:363990 AN 2003:381106 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare agents (CWA's) represent a real and growing threat both to U.S. armed forces as well as to civilians. Within the last three decades, chem. weapons have been used by the Soviets in Cambodia (yellow rain, tricothecene mycotoxins), by Iraq against Iran (HD and tabun), and by Iraq against its own dissident Kurdish population at Halabja (H-ID HCN0). In the United States' experience in World War I, almost one-third of hospitalized casualties were a result of CWA's. Furthermore, the 1000 casualties and 12 deaths resulting from the 1995 terrorist use of sarin (GB) in Tokyo show that civilians have also become targets. In this paper we focus on protection against two classes of CWA's: nerve agents (soman, GD) and blister agents (sulfur mustard, HD). Protection against these agents in the United States Army consists of a chem. resistant outer layer of clothing (BDO) and protective mask (M40). This scheme of protection allows operation in a chem. contaminated area but results in decreased performance and increased heat retention. We have investigated a material that serves as a phys. barrier to CWA's and contains an active moiety to neutralize hazardous chems. This Active Topical Skin Protectant (aTSP) would be used in conjunction with other protective procedures. Herein we report the prepn., characterization, and evaluation of aTSP's.

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Molecularly imprinted polymers for the detection of chemical agents in water. Jenkins, Amanda L.; Yin, Ray; Jensen, Janet L.; Durst, H. Dupont. US Army Research Laboratory, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 76-77. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:343335 AN 2003:381101 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molecularly imprinted polymers contg. Eu3+ were prepd. using a no. of pesticides and pinacolyl methylphosphonate (hydrolysis product of the nerve agent Soman), and sensors were fabricated by coating the polymers on optical fibers. The sensors were characterized in terms of sensitivity, selectivity, response time, adaptability, and portability; they provided detection limits in the low parts per trillion.

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Synthesis of carbon-coated MgO nanoparticles. Bedilo, Alexander F.; Sigel, M. Jake; Koper, Olga B.; Melgunov, Maxim S.; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2002), 12(12), 3599-3604. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 138:174329 AN 2002:910661 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Carbon-coated MgO nanoparticles, with carbon forming a porous coating on the surface of MgO nanoparticles, have been prepd. by two different techniques. Resorcinol has been found to be an efficient agent for the modification of magnesium methoxide leading to carbon-coated MgO nanocrystals of small crystallite size and high surface area. Decompn. of dry magnesium methoxide under an inert gas flow proved to be another efficient and economical way to synthesize carbon-coated MgO. The carbon coating acts as a hydrophobic barrier partially protecting the core metal oxide from water adsorption and conversion to magnesium hydroxide. However, destructive adsorption reactions can still proceed on the metal oxide surface, as evidenced by the dehydrochlorination of 2-chloroethyl Et sulfide (2-CEES) and 1-chlorobutane. The overall stability of the material in the presence of water vapor is significantly improved in comparison with non-coated nanocryst. MgO.

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Micellar Effects on Hypochlorite Catalyzed Decontamination of Toxic Phosphorus Esters. Dubey, D. K.; Gupta, A. K.; Sharma, Mamta; Prabha, S.; Vaidyanathaswamy, R. Defence R and D Establishment, Gwalior, India. Langmuir (2002), 18(26), 10489-10492. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 138:94789 AN 2002:866089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At pH 8.5, the surfactant N,N,N-trimethyl-1-hexadecanaminium bromide (I) increased the pseudo-first-order rate consts. of hypochlorite-catalyzed hydrolysis of the sarin model compd. p-nitrophenyl di-Ph phosphate by 300 times and that of the toxic p-nitrophenyl iso-Pr methylphosphonate by 20 times, and the nerve agent sarin itself was completely decontaminated within 10 min at a sarin-hypochlorite ratio of 20:1 in a micellar I-hypochlorite mixt. In the absence of surfactant , it takes >70 min to detoxify sarin, even at a 10 times higher concn. of hypochlorite.

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A Comparative Study of the Adsorption of Chloro- and Non-Chloro-Containing Organophosphorus Compounds on WO3. Kanan, Sofian M.; Lu, Zhixiang; Tripp, Carl P. Laboratory for Surface Science Technology and Department of Chemistry, University of Maine, Orono, ME, USA. Journal of Physical Chemistry B (2002), 106(37), 9576-9580. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 137:253624 AN 2002:620746 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The adsorption of di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), and methyldichlorophosphate (MDCP) on monoclinic tungsten oxide (m-WO3) evacuated at various temps. was investigated using IR spectroscopy. DMMP is the most common mol. used for evaluating the performance of WO3 and other semiconducting metal oxide (SMO)-based sensors to phosphonate-based nerve agents. However, toxic nerve agents such as sarin differ from DMMP in that they contain a functional group (P-F in sarin) that can be readily hydrolyzed. It is shown that the adsorption of organophosphates that contain P-Cl groups differs from nonhalogenated simulants such as DMMP and TMP on WO3 surfaces. Specifically, the non-chlorinated simulants DMMP and TMP adsorb on the surface solely through the P:O functionality with the surface water layer as well as the Lewis and Bronsted acid sites. The relative no. of mols. bound on Lewis and Bronsted acid surface sites depends on the initial evacuation temp. of the WO3 surface. When MDCP adsorbs on WO3 through the P:O bond, it is accompanied by the hydrolysis of P-Cl groups by water vapor or the adsorbed water layer leading to addnl. phosphate-like species on the surface. The IR data suggests that a halogenated phosphate like MDCP is a better simulant mol. for studies aimed at understanding the role of water and hydrolysis in the response of metal oxide-based sensors to nerve agents.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock, Shannon D.; Till, Gerd O.; Smith, Milton G.; Ward, Peter A. Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2002), 22(4), 257-262. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 137:151235 AN 2002:596130 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. warfare agent analog, 2-chloroethyl Et sulfide, known as half-mustard gas (HMG), is less toxic and less of an environmental hazard than the full mol. and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of 125I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, the authors obsd. significant attenuation of the pulmonary injury when exptl. animals were complement- or neutrophil-depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, DMSO, dimethylthiourea, Resveratrol, and N-acetyl-L-cysteine (NAC). The last compd. showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement-mediated pathways and the generation by neutrophils of toxic oxygen species. The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber, Ellen; McGuire, Raymond. Lawrence Livermore National Laboratory, Environment Protection Department, University of California, Livermore, CA, USA. Journal of Hazardous Materials (2002), 93(3), 339-352. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 137:374412 AN 2002:558690 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A decontamination method was developed using a single reagent that is effective both against chem. warfare (CW) and biol. warfare (BW) agents. The new reagent, L-Gel, consists of an aq. soln. of a mild com. oxidizer, Oxone, together with a com. fumed silica gelling agent, Cab-O-Sil EH 5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. This reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Expts. to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Lab. and independently at 4 other locations. L-Gel was tested against all classes of chem. warfare agents and against various biol. warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biol. agents. Testing showed that L-Gel is as effective against chem. agents and biol. materials, including spores, as the best military decontaminants.

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Synthesis, Characterization, and Adsorption Studies of Nanocrystalline Aluminum Oxide and a Bimetallic Nanocrystalline Aluminum Oxide/Magnesium Oxide. Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J.; Bonevich, John. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry of Materials (2002), 14(7), 2922-2929. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 137:128541 AN 2002:469813 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of Al2O3 and Al2O3/MgO have been produced by a modified aerogel synthesis involving the corresponding aluminum tri-tert-butoxide, magnesium methoxide, toluene, methanol, ethanol, and water. The resulting oxides are in the form of powders having crystallites of .ltorsim.2 nm. These crystallites have been studied by TEM and BET methods, and were found to possess high surface areas and pore vols. (800 m2/g for Al2O3 and 790 m2/g for Al2O3/MgO, compared to 450 m2/g for MgO). As seen with other metal oxides, once they are produced as nanoparticles, their reactivity is greatly enhanced on a per unit surface area basis. This is thought to be due to morphol. differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites possess much higher surface concn. of such sites per unit surface area. Elemental anal., X-ray diffraction, and IR spectroscopy have been used to characterize these nanoparticles, and reactions with CCl4, SO2, and Paraoxon have demonstrated significantly enhanced reactivity and/or capacity compared with common com. forms of the oxide powders. A significant feature is that, by a cogellation synthesis, Al2O3 and MgO have been intermingled, which engenders enhanced reactivity/capacity over the pure forms of nanoscale Al2O3 or MgO toward a chem. warfare surrogate (Paraoxon) and an acid gas (SO2). This serves as an example where tailored synthesis of a nanostructured formulation can yield special benefits.

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Nanocrystalline metal oxides as destructive adsorbents for organophosphorus compounds at ambient temperatures. Rajagopalan, Shyamala; Koper, Olga; Decker, Shawn; Klabunde, Kenneth J. Nanoscale Materials, Inc., Manhattan, KS, USA. Chemistry--A European Journal (2002), 8(11), 2602-2607. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 137:191092 AN 2002:451335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of magnesium oxide react with organophosphorus compds. at room temp. by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant mol. fragments. These ultrafine powders have unusual cryst. shapes and possess high surface concns. of reactive edge/corner and defect sites, and thereby display higher surface reactivity, normalized for surface area, than typical polycryst. material. This high surface reactivity coupled with high surface area allows their use for effective decontamination of chem. warfare agents and related toxic substances. Herein data is presented for paraoxon, diisopropylfluorophosphate (DFP), and (CH3CH2O)2P(O)CH2SC6H5 (DEPTMP). Solid-state NMR and IR spectroscopy indicate that all OR and F groups dissoc.; this leaves bound -PO4%
2C -F, and -OR groups for paraoxon, DFP, and DEPTMP, resp. For paraoxon, it was shown that one monolayer reacts. For DEPTMP, the OR groups dissoc., but not the P-CH2SC6H5 group. The nanocryst. MgO reacts much faster and in higher capacity than typical activated carbon samples, which physisorb but do not destructively adsorb these phosphorous compds.

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Routes of photocatalytic destruction of chemical warfare agent simulants. Vorontsov, Alexandre V.; Davydov, Lev; Reddy, Ettireddy P.; Lion, Claude; Savinov, Eugenii N.; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russia. New Journal of Chemistry (2002), 26(6), 732-744. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 137:236738 AN 2002:427511 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Selected imitants of chem. warfare agents such as di-Me methylphosphonate (DMMP), di-Et phosphoramidate (DEPA), pinacolyl methylphosphonate (PMP), and butylaminoethanethiol (BAET) were subjected to photocatalytic and sonophotocatalytic treatment in aq. suspensions of TiO2. Complete conversion of the same mass of imitants to inorg. products was obtained within 600 min for DMMP, DEPA, PMP, but required a longer time for BAET. Sonolysis accelerated photodegrdn. of DMMP. No degrdn. was obsd. without UV illumination. Final products of degrdn. were PO43-, CO2 for DMMP and PMP, PO43-, NO3- (25%), NH4+ (75%), CO2 for DEPA, and SO42-, NH4+, CO2 for BAET. The no. of main detected intermediate products increases in the order DMMP (7), DEPA (9), PMP (21), and exceeds 34 for BAET. Degrdn. of DMMP mainly proceeds through consecutive oxidn. of methoxy groups and then the Me group. Di-Me hydroxymethylphosphonate and dimethylphosphate testify to the parallel oxidn. of the Me group. Destruction of DEPA mainly starts with cleavage of the P-NH2 bond to form di-Et phosphate, which transforms further into Et phosphate. Oxidn. of  and  carbons of ethoxy groups to form ethylphosphonoamidate, hydroxyethyl ethylphosphonoamidate and other products also contributes to the destruction. Photocatalytic degrdn. of PMP mainly starts with oxidn. of the pinacolyl fragment, methylphosphonic acid and acetone being the major products. Oxidn. of BAET begins with dark dimerization to disulfide, which undergoes oxidn. of sulfur forming sulfinic and sulfonic acids as well as oxidn. of carbons to form butanal, aminobutane, etc., and cyclic products such as 2-propylthiazole. A scheme of degrdn. was proposed for DMMP and DEPA, and starting routes for PMP and BAET. Quantum efficiencies of complete mineralization calcd. as reaction rate to photon flux ratio approx. 10-3%.

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Solvent Effects on the Heterogeneous Adsorption and Reactions of (2-Chloroethyl) ethyl Sulfide on Nanocrystalline Magnesium Oxide. Narske, Richard M.; Klabunde, Kenneth J.; Fultz, Shawn. Department of Chemistry, Augustana College, Rock Island, IL, USA. Langmuir (2002), 18(12), 4819-4825. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:62952 AN 2002:360518 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The noncatalytic destructive adsorption of (2-chloroethyl) Et sulfide (2-CEES), a mimic of bis(2-chloroethyl) sulfide (HD or Mustard Gas), on nanocryst. Mg oxide (AP-MgO) was studied in several solvents from pentane to methanol. The decompn. products formed in these reactions were vinyl Et sulfide and (2-hydroxyethyl) Et sulfide. Reactions in pentane allowed the highest reaction rates, while THF and methanol gave results quite different from those for the hydrocarbon solvent. Reactions in methanol yielded (methoxyethyl) Et sulfide and not the vinyl Et sulfide and (2-hydroxyethyl) Et sulfide compds. These studies showed that the MgO-2-CEES reaction chem. is significantly affected by the solvent present and can be enhanced by choice of solvent and the addn. of small amts. of water. Interestingly, the least polar, least reactive solvent (pentane) allowed the most rapid 2-CEES reactions, indicating that the solvent simply aided material transfer to the reactive surface sites without blocking these sites. Rate changes upon water addn., coupled with FTIR studies, indicate that isolated surface OH groups are important reactive sites. These results indicate that the use of certain inert solvents greatly aids material transfer, and thereby the reaction rates of the sorbent with the toxin are significantly enhanced.

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Adsorption and Reaction of Diethyl Sulfide on Active Carbons with and without Impregnants under Static Conditions. Prasad, G. K.; Singh, Beer; Saradhi, U. V. R.; Suryanarayana, M. V. S.; Pandey, D. Defence Research and Development Establishment, Gwalior, India. Langmuir (2002), 18(11), 4300-4306. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:52819 AN 2002:306380 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Active carbons of different grades with and without impregnants were studied for the adsorption of di-Et sulfide (DES), the simulant of S mustard, under static conditions at 36  1. Kinetics of the adsorption were studied using linear driving force (LDF) and the Fickian diffusion model. The kinetic parameters such as equilibration time, equilibration capacity, equilibration const., diffusional exponent, and adsorbate-adsorbent interaction const. (K) were detd. The diffusional exponent (n), being <0.5, indicated a Fickian mode of diffusion of DES in the studied C. Chem. interaction also seemed to be the 2nd mechanism (although minor) involved in the DES uptake rate (the 1st being simple Fickian diffusion). The adsorbate-adsorbent interaction const. did not vary significantly indicating that probably DES chem. interacts to a small extent with the metal salts present on the surface of active C as impregnants. However, the characterization of reaction products, after extn. in CH2Cl2, using GC/MS indicated that the system CrO3/NaOH/C (C impregnated with Cr(VI) plus NaOH) only reacted with DES to give di-Et sulfone.

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An improved brain slice model of nerve agent-induced seizure activity. Wood, Sebastien J.; Tattersall, John E. H. Biomedical Sciences Department, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(Suppl. 1), S83-S86. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:290254 AN 2002:246280 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice prepn. Soman (1 M) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice prepn. is a suitable model for investigating the origin and propagation of nerve agent-induced seizures within the limbic system.

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The NMDA receptor ion channel: a site for binding of huperzine A. Gordon, Richard K.; Nigam, Savita V.; Weitz, Julie A.; Dave, Jitendra R.; Doctor, Bhupendra P.; Ved, Haresh S. Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S47-S51. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:397222 AN 2002:246274 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Huperzine A (HUP-A), first isolated from the Chinese club moss Huperzia serrata, is a potent, reversible and selective inhibitor of acetylcholinesterase (AChE) over butyrylcholinesterase (BChE) (Life Sci. 54: 991-997). Because HUP-A has been shown to penetrate the blood-brain barrier, is more stable than the carbamates used as pretreatments for organophosphate poisoning (OP) and the HUP-A:AChE complex has a longer half-life than other prophylactic sequestering agents, HUP-A has been proposed as a pretreatment drug for nerve agent toxicity by protecting AChE from irreversible OP-induced phosphonylation. More recently (NeuroReport 8: 963-968), pretreatment of embryonic neuronal cultures with HUP-A reduced glutamate-induced cell death and also decreased glutamate-induced calcium mobilization. These results suggest that HUP-A might interfere with and be beneficial for excitatory amino acid overstimulation, such as seen in ischemia, where persistent elevation of internal calcium levels by activation of the N-methyl-D-aspartate (NMDA) glutamate subtype receptor is found. The authors have now investigated the interaction of HUP-A with glutamate receptors. Freshly frozen cortex or synaptic plasma membranes were used, providing 60-90% specific radioligand binding. Huperzine A (100 M) had no effect on the binding of [3H]glutamate (low- and high-affinity glutamate sites), [3H]MDL 105,519 (NMDA glycine regulatory site), [3H]ifenprodil (NMDA polyamine site) or [3H]CGS 19755 (NMDA antagonist). In contrast with these results, HUP-A non-competitively (Hill slope < 1) inhibited [3H]MK-801 and [3H]TCP binding (co-located NMDA ion channel PCP site) with pseudo Ki .apprx. 6 M. Furthermore, when neuronal cultures were pretreated with HUP-A for 45 min prior to NMDA exposure, HUP-A dose-dependently inhibited the NMDA-induced toxicity.
Although HUP-A has been implicated to interact with cholinergic receptors, it was without effect at 100 M on muscarinic (measured by inhibition of [3H]QNB or [3H]NMS binding) or nicotinic [3H]epibatidine binding) receptors; also, HUP-A did not perturb adenosine receptor binding [3H]PIA or [3H]NECA). Therefore, HUP-A most likely attenuates excitatory amino acid toxicity by blocking the NMDA ion channel and subsequent Ca2+ mobilization at or near the PCP and MK-801 ligand sites. Thus, on the one hand, HUP-A could be used as a pretreatment against OPs and it might also be a valuable therapeutic intervention in a variety of acute and chronic disorders by protecting against overstimulation of the excitatory amino acid pathway. By blocking NMDA ion channels without psychotomimetic side-effects, HUP-A may protect against diverse neurodegenerative states obsd. during ischemia or Alzheimer's disease.

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Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense. Smith, J. Richard; Shih, Ming L.; Price, Elvis O.; Platoff, Gennady E.; Schlager, John J. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S35-S41. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365032 AN 2002:246272 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An army medical field lab. presently has the capability of performing std. protocols developed at the US Army Medical Research Institute of Chem. Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chem. warfare agents using gas chromatog./mass spectrometry. Addnl., chem. warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biol. half-lives and can be used as diagnostic biomarkers of chem. agent exposure. An anal. technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examd. for its potential to analyze these biomarkers. The technique is capable of detecting large biomols. and modifications made to them. Its fast anal. time makes MALDI-TOF/MS technol. suitable for screening casualties from chem. or biol. attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

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Analysis of the degradation compounds of chemical warfare agents using liquid chromatography/mass spectrometry. Smith, J. Richard; Shih, Ming L. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S27-S34. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365031 AN 2002:246271 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of the degrdn. products of chem. warfare (CW) agents has been a challenge to analysts. The low volatility of these compds. makes them unsuitable for direct gas chromatog. anal. without prior derivatization. Lack of a chromophore causes difficulties with classic detection methods after liq. chromatog. sepn. With the recent development of various interfaces that allow for the introduction of a liq. solvent stream into the mass spectrometer, the task of directly analyzing these compds. has become easier. For this report, the authors examd. three different liq. chromatog./mass spectrometry (LC/MS) interfaces for their suitability for the anal. of CW degrdn. compds. The interface types examd. were particle beam electron impact ionization (PBI), electrospray ionization (ESI) and atm. pressure chem. ionization (APCI). Several alkylphosphonates and thiodiglycol analogs that are produced from the degrdn. of organophosphorus nerve agents and sulfur mustard, resp., were analyzed using each of the three techniques. Electron impact ionization following gas chromatog. or particle beam introduction typically generates very reproducible, library-searchable mass spectra. Most of the CW breakdown compds. examd. using the PBI interface did not produce a mol. ion. Despite the lack of a mol. ion, the mass spectra of the various compds. contained enough different structural information from fragment ions for the pos. identification of each. The mass spectra generated using ESI are generally limited to protonated mol. ions with little or no fragmentation. For pos. identification and confirmation, tandem mass spectrometry techniques quite often must be used. Many of the compds. in this study were characterized by prominent sodiated adducts along with the protonated mol. ion. Methylphosphonic acid produced protonated dimers, trimers, etc. Although the various adduct ions can be used for addnl. confirmation of the mol. wt. of a compd., the adducts also can result in suppression of ionization of the compd.
and thus reduce sensitivity. Another "soft" ionization technique that results in abundant protonated mol. ions is APCI. The mass spectra of the breakdown compds. produced using APCI were characterized generally by either a prominent protonated mol. ion or a dehydrated form of it. In addn., a no. of structurally significant fragment ions were obsd. and their relative abundances could be adjusted by altering the APCI conditions. The data presented here indicate that each of the three techniques can be used successfully for direct liq. introduction and anal. of the non-volatile compds. produced from the degrdn. of CW agents. The mass spectra produced using each technique are quite different and could be utilized as addnl. confirmation of compd. identity.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller, Jennifer K.; Lenz, David E. Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S23-S26. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:336395 AN 2002:246270 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-mol.-wt. compds. is effected by the use of chromatog. techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the anal. To overcome those drawbacks, the authors were involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compds. such as pinacolylmethyl phosphonofluoridate (soman), which is a chem. warfare agent. Prior ests. suggested that it is necessary to be able to detect soman at a concn. below 2.5  10-7 M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The min. required assay time was 2.0-2.5 h with no loss in sensitivity. To det. the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogs were 5  10-7 M for 4-nitrophenylpinacolylmethylphosphonate, 8  10-7 M for dipinacolylmethylphosphonate, 2  10-6 M for diisopropylmethylphosphonate, 3  10-5 M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5  10-5 M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman mol., were effective inhibitors. Compds., which contained predominately arom. groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to det. its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman.

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The active site of human paraoxonase (PON1). Josse, Denis; Lockridge, Oksana; Xie, Weihua; Bartels, Cynthia F.; Schopfer, Lawrence M.; Masson, Patrick. Eppley Institute, University of Nebraska Medical Center, Omaha, NE, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S7-S11. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365079 AN 2002:246267 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ideally the authors would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman. However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4  106 M-1 min-1, and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, the authors have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw, M. D.; Hayes, T. L.; Miller, T. L.; Shannon, C. M. Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S3-S6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365078 AN 2002:246266 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) iso-Bu methylphosphonothiolate-a V-type nerve agent developed by the former Soviet Union-in the environment is an important parameter in threat assessment anal. and for the detn. of use, prodn., testing and storage of this chem. warfare agent. S-(N,N-Diethylaminoethyl) iso-Bu methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same mol. formula, it is expected that their phys. and chem. properties would be different. This preliminary investigation was undertaken to det. the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compd. at approx. 1 mg ml-1 in unbuffered water at pH 7 was detd. side-by-side. The half-lives for VXA and VX were detd. to be 12.4 days and 4.78 days, resp. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chem. Weapons Convention.

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Synthesis of high surface area monoclinic WO3 particles using organic ligands and emulsion based methods. Lu, Zhixiang; Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST), University of Maine, Orono, ME, USA. Journal of Materials Chemistry (2002), 12(4), 983-989. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 136:389533 AN 2002:226497 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several synthetic approaches have been used to obtain nano-sized monoclinic WO3 (m-WO3) powders. All of these methods begin with a std. preparative method where H2WO4 is first generated by passing a Na2WO4 soln. through a cation-exchange resin. It is shown that high surface area particles are produced by dripping the H2WO4 exiting from the ion-exchange column into a soln. contg. oxalate and acetate exchange ligands or alternatively, into a water-in-oil (w/o) based emulsion. In comparison to com. WO3 powders, the surface area of the m-WO3 powders were higher by factors of 10 and 20 times when prepd. in the presence of acetate/oxalate chelating agents and w/o emulsions, resp. The much higher surface areas enable IR spectroscopic identification of surface sites along with detection and monitoring of gaseous reactions and adsorbed species on the surface of this metal oxide. This is demonstrated with the adsorption of a nerve agent simulant, di-Me Me phosphonate. In general, little is known about the reactions of gaseous mols. on m-WO3 surfaces and the fabrication of high surface area m-WO3 particles will aid in gaining an understanding of the chem. processes occurring in WO3 based sensors.

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Prefiltering Strategies for Metal Oxide Based Sensors: The Use of Chemical Displacers to Selectively Dislodge Adsorbed Organophosphonates from Silica Surfaces. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2002), 18(3), 722-728. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 136:173252 AN 2002:22837 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

IR spectroscopy is used to monitor the competitive adsorption/desorption behavior of the nerve gas simulants, di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on SiO2. All 4 compds. molecularly adsorb via hydrogen bonds (H-bonds) with the surface hydroxyl groups. The adsorption strength depends on 2 factors: the specific functional group H-bonded to the surface hydroxyl groups and the no. of such bonds per mol. The phosphonates are molecularly displaced from the SiO2 surface by chem. displacers. By judiciously selecting chem. displacers as dictated by the 2 factors, (i.e., type and no. of functional groups H-bonded to the surface silanols) it is possible to selectively and sequentially dislodge each of the 4 phosphonate compds. adsorbed on SiO2. Specifically, the relative adsorption strength of the phosphonate compds. and the chem. displacers (labeled A-C) follows the order: TCP < MDCP < A < DMMP < B < TMP < C, where A = NEt3 (TEA), B = 2-pyridyl MeCN (2-PyAN), and C= ethylenediamine (EDA). AM1 semiempirical calcns. show that the toxic nerve agent, sarin, would position itself between MDCP and DMMP in the above order. The implications of using chem. displacers in filtering applications with metal oxide based sensors are discussed.

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New -phthalimidoperoxyalkanoic acids in decontamination. Destruction of some toxic organophosphorus and organosulfur pollutants. Lion, Claude; Da Conceicao, Louis; Delmas, Gerard; Magnaud, Gilbert. Institut de Topologie et de Dynamique des Systemes, Universite de Paris 7, Paris, Fr. New Journal of Chemistry (2001), 25(9), 1182-1184. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 136:90120 AN 2001:726141 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (chem. warfare agents and/or insecticides) is of increasing importance. We report the use of -phthalimidoperoxyalkanoic acids in the destruction of paraoxon (di-Et p-nitrophenyl phosphate), a well-known insecticide, and 2-chloro-2'-phenyldiethyl sulfide (a half mustard). We show that while all the peroxy acids used in this series allow the destruction of toxic compds., the length n of the alkanoic side chain is important to the choice of the optimal industrial compd., which is 6-phthalimidoperoxyhexanoic acid (n = 5).

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig ear skin. Chilcott, R. P.; Jenner, J.; Hotchkiss, S. A. M.; Rice, P. Department of Biomedical Sciences, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(4), 279-283. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:191481 AN 2001:616748 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chem. warfare agent sulfur mustard (SM). The in vitro absorption rates of SM through heat-sepd. human (15766 g cm-2 h-1) and pig-ear (411175 g cm-2 h-1) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 g cm-2 h-1, resp. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig ear epidermal membranes measured in vitro. Thus, although pig ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells contg. human epidermal membranes as a model for predicting in vivo human skin absorption.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen, J.; Riikonen, K.; Nikmo, J.; Jappinen, A.; Nieminen, K. Air Quality Research, Finnish Meteorological Institute, Helsinki, Finland. Journal of Hazardous Materials (2001), 85(3), 165-179. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 136:41716 AN 2001:572441 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Math. models were developed to evaluate the atm. dispersion of selected chem. warfare agents (CWA), including evapn. and settling of pollutant liq. droplets. The presented models and numerical results may be used to design protection and control measures against the conceivable use of CWA. The model, AERCLOUD (AERosol CLOUD), was extended to treat 2 nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodn. evolution of a 5-component aerosol mixt., consisting of 2-component droplets together with the surrounding 3-component gas. Numerical computations were performed using this model on the evapn. and settling of airborne sarin droplets in characteristic dispersion and atm. conditions. In particular, the max. radii (rM) of a totally evapg. droplet, in terms of the ambient temp. and pollutant vapor concn., were evaluated. The radii rM were .apprx.15-80 m for sarin droplets for selected ambient conditions and initial heights. Deposition fractions in terms of initial droplet size were also evaluated.

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Oxidation of triphenylarsine to triphenylarsine oxide by Trichoderma harzianum and other fungi. Hofmann, K.; Hammer, E.; Kohler, M.; Bruser, V. URST Umwelt- und Rohstoff-Technologie GmbH Greifswald, Greifswald, Germany. Chemosphere (2001), 44(4), 697-700. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 135:254254 AN 2001:483254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Arsenic resistant strains of bacteria and fungi were isolated from soil contaminated by chem. warfare agents. Until now, no metabolic products of microbial attack against the Ph residues of the model substrate triphenylarsine (TP) were found if it was incubated together with these strains in liq. culture assays. However, one of the isolated fungi, Trichoderma harzianum As 11, was found to oxidize TP to triphenylarsine oxide (TPO). The yeast Trichosporon mucoides SBUG 801 and the white-rot fungus Phanerochaete chrysosporium were also able to oxidize the As(III) in TP. In addn., P. chrysosporium transformed phenylarsine oxide (PAO) to phenylarsonic acid (PAA) under O2-atmosphere. By means of a respirometer system, the oxidn. of TP by T. harzianum As 11 was confirmed by a significantly higher consumption of oxygen in the presence of these compds. HPLC anal. of the oxidn. products TPO and PAA in the medium of the assays provided evidence for the transfer reaction of As(III) to As(V) in org. bonds. The oxidn. products TPO and PAA are more hydrophilic than TP and PAO. Therefore, it was concluded that particular fungi contribute to the mobilization of arsenic in soil contaminated by chem. warfare agents.

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Nanocrystalline metal oxides as unique chemical reagents/sorbents. Lucas, Erik; Decker, Shawn; Khaleel, Abbas; Seitz, Adam; Fultz, Shawn; Ponce, Aldo; Li, Weifeng; Carnes, Corrie; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry--A European Journal (2001), 7(12), 2505-2510. CODEN: CEUJED ISSN: 0947-6539. Journal; General Review written in English. CAN 135:216336 AN 2001:471452 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 29 refs. A new family of porous inorg. solids based on nanocryst. metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar orgs., and even chem./biol. warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chem. properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price, Elvis O.; Smith, J. Richard; Clark, Connie R.; Schlager, John J.; Shih, Ming L. Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S193-S197. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:206570 AN 2001:455416 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The continual threat of chem. and biol. warfare has prompted the need for unambiguous anal. methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with Hb and metallothioneins were conducted. In vitro expts. with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to det. the extent of alkylation and occurrence of HD crosslinking using the MALDI-ToF/MS technique. In a typical expt., 50 mL of 5 mM HD in acetonitrile was added to an equal vol. of 0.5 mM Hb in deionized water followed by vortexing and incubation at room temp. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES expts. These results demonstrate that MALDI-ToF/MS is a useful anal. technique to investigate the interaction of HD with biomols. and may be employed potentially as a diagnostic tool for the confirmation of exposure to chem. warfare agents.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham, John S.; Reid, Frances M.; Smith, J. Richard; Stotts, Richard R.; Tucker, F. Steven; Shumaker, Shawn M.; Niemuth, Nancy A.; Janny, Stephen J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S161-S172. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72547 AN 2001:455411 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chem. warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clin. pathol. findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liq. on the ventral surface for 2 h, generating six 3-cm diam. full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematol. and serum chem. examns. Urine was collected in metab. cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatog./mass spectrometry. Examn. of clin. pathol. parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clin. significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 g ml-1 with a mean of 2.14 g ml-1. Thiodiglycol concns. were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml-1. Mean levels remained 10-40 ng ml-1 for the remainder of the 7-day observation period, with the highest individual concn. noted during this period of 132 ng ml-1. Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other lab. animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 wk. Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h.
Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin, M. C.; Ricketts, K.; Skvorak, J. P.; Gazaway, M.; Mitcheltree, L. W.; Casillas, R. P. Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S141-S144. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72425 AN 2001:455408 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quant. edema response as well as histopathol. and biochem. endpoints as measurements of inflammation and tissue damage following exposure to the chem. warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal sepn. This study evaluated the protective effects of three of these pharmacol. compds. when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver an s.c. dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 l of a 195 mM (0.16 mg) soln. of sulfur mustard (d. = 1.27 g ml-1; MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathol. damage (necrosis, epidermal-dermal sepn.). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant redn. in edema (24%, 26% and 22%, resp.) from the pos. control. Compared to HD-pos. controls, hydrocortisone, indomethacin and olvanil caused a significant redn. in subepidermal blisters (71%, 52% and 57%, resp.) whereas only hydrocortisone produced a significant redn. in contralateral epidermal necrosis (41%). The authors show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins, Kevin B.; Lodhi, Irfan J.; Hurley, Lauren L.; Hinshaw, Daniel B. University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S125-S128. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72423 AN 2001:455404 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chem. warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells. Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 M HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 M buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 M HD for 5-6 h. Externally applied GSH up to a concn. of 5 mM had no toxic effect on the cells. Mild toxicity was assocd. with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examd. the hypothesis that HD may activate the nuclear transcription factor NFB by performing EMSAs with nuclear exts. of endothelial cells following exposure to 0, 250 or 500 M HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFB binding to its consensus sequence induced by 500 M HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFB, although HD-induced activation of NFB was partially suppressed by NAC at 5 h. Factor NFB is an important transcription factor for a no. of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFB activity. The NFB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction assocd. with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha, M.; Bowers, W., Jr.; Kohl, J.; DuBose, D.; Walker, J.; Alkhyyat, A.; Wong, G. US Army Research Institute of Environmental Medicine, Natick, MA, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S101-S108. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72420 AN 2001:455401 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl Et sulfide (CEES, 1-2 mg l-1 min-1) in humidified air or to humidified air alone. Tissues were evaluated histol., ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histol. showed that CEES induced the sepn. of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histol. and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1 (IL-1), prostaglandin-E2 (PGE2) and esp. IL-1 receptor antagonist (IL-1Ra) release (56334 vs. 84614 pg ml-1), but decreased interleukin-6 (IL-6, 4755 vs. 351 pg ml-1). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracellular IL-1 (371 vs. 92 pg ml-1). Extracellular IL-1Ra greatly increased (2375 vs. 24875 pg ml-1), whereas cellular levels decreased (165425 vs. 96625 pg ml-1). Extracellular (224 vs. 68 pg ml-1) and intracellular (485 vs. 233 pg ml-1) sol. interleukin-1 receptor II (sIL-1RII) decreased. Prostanglandin E2 increased (1835 vs. 2582 pg ml-1), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57000 vs. 96000 pg ml-1). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Intervention of sulfur mustard toxicity by down-regulation of cell proliferation and metabolic rates. Ray, R.; Benton, B. J.; Anderson, D. R.; Byers, S. L.; Petrali, J. P. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S87-S91. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72419 AN 2001:455399 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chem. warfare compd. HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37) first in keratinocyte growth medium (KGM) contg. BAPTA AM (10-40 M) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concn.-dependent manner with some cellular degeneration above 30 M (light microscopy). At 20-30 M, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 545%), [3H]-uridine (RNA synthesis, 296%) and [14C]-valine (protein synthesis, 122%) as well as a lower protein content per culture (303%) compared with corresponding untreated controls. However, 20-30 M BAPTA AM did not cause any demonstrable cytopathol. based on morphol. (electron microscopy) as well as biochem. (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Calmodulin, poly(ADP-ribose)polymerase and p53 are targets for modulating the effects of sulfur mustard. Rosenthal, Dean S.; Simbulan-Rosenthal, Cynthia M.; Iyer, Sudha; Smith, William J.; Ray, Radharaman; Smulson, Mark E. Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S43-S49. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72546 AN 2001:455392 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

We describe two pathways by which the vesicating agent sulfur mustard (HD) may cause basal cell death and detachment: induction of terminal differentiation and apoptosis. Following treatment of normal human epidermal keratinocytes (NHEK) with 10 or 100 M HD, the differentiation-specific keratin pair K1/K10 was induced and the cornified envelope precursor protein, involucrin, was crosslinked by epidermal transglutaminase. Fibronectin levels were reduced in a time- and dose-dependent manner. The rapid increase in p53 and decrease in Bcl-2 levels was consistent not only with epidermal differentiation but with apoptosis as well. Further examn. of biochem. markers of apoptosis following treatment of either NHEK or human papillomavirus (HPV)-immortalized keratinocytes revealed a burst of poly(ADP-ribose) synthesis, specific cleavage of poly(ADP-ribose)polymerase (PARP) in vivo and in vitro into characteristic 89 and 24 kDa fragments, processing of caspase-3 into its active form and the formation of DNA ladders. The intracellular calcium chelator BAPTA suppressed the differentiation markers, whereas antisense oligonucleotides and chem. inhibitors specific for calmodulin blocked both markers of differentiation and apoptosis. Modulation of p53 levels utilizing retroviral constructs expressing the E6, E7 or E6 + E7 genes of HPV-16 revealed that HD-induced apoptosis was partially p53-dependent. Finally, immortalized fibroblasts derived from PARP -/- "knockout mice" were exquisitely sensitive to HD-induced apoptosis. These cells became HD resistant when wild-type PARP was stably expressed in these cells. These results indicate that HD exerts its effects via calmodulin, p53 and PARP-sensitive pathways.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser, Janet; Meier, Henry L. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S23-S30. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72413 AN 2001:455389 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chem. warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compds. in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell prepns. were exposed to various concns. of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these expts. suggest that, with increasing HD concn. and time, NHEK will fragment irresp. of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains const. over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concn.- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, resp., is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concns. that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers, S.; Anderson, D.; Brobst, D.; Cowan, F. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S19-S22. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72270 AN 2001:455388 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chem. warfare compd., has been shown to deplete the NAD (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compds. To examine NAD+ levels, an automated method based on the alc. dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clin. analyzer has been developed. Automation of this assay led to smaller sample vols. and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD-exposed group. This assay appears to be useful for testing potential antivesicant compds. using both in vivo and in vitro exposure systems.

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Effects of Lewisite on cell membrane integrity and energy metabolism in human keratinocytes and SCL II cells. Kehe, K.; Flohe, S.; Krebs, G.; Kreppel, H.; Reichl, F. X.; Liebl, B.; Szinicz, L. Institute of Pharmacology and Toxicology, FAF Medical Academy, Munich, Germany. Toxicology (2001), 163(2-3), 137-144. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:133255 AN 2001:448571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite is a highly toxic arsenic compd. which can cause skin damage. In the present study effects of Lewisite on cell membrane integrity and energy metab. as well as antidotal effects of DL-2,3-dimercaptopropanesulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (m-DMSA) were investigated in a keratinocyte derived cell line (SCL II) and primary human keratinocytes (HK). Cells were incubated in Lewisite (60 M) contg. medium for 5 min. During the following 6 h lactate dehydrogenase (LDH) activity in the supernatant, intracellular ATP content, tetrazolium redn., glucose consumption and lactate formation were measured. Glucose consumption and lactate prodn. were decreased in both cell lines after Lewisite exposure. In SCL II cells an increase of LDH activity in the supernatant, a decrease of ATP content, and an impaired ability to reduce tetrazolium was found 3 h after Lewisite exposure. In HK cultures tetrazolium redn. was significantly decreased already after 2 h, whereas LDH increase in the supernatant and ATP content decrease occurred only at 6 h after Lewisite exposure. When DMPS or m-DMSA was added directly after Lewisite exposure to SCL II cells, glucose consumption and lactate formation were restored and LDH leakage was prevented. SCL II cells might be more prone to membrane damage whereas in keratinocytes mitochondrial impairment seems to be the predominant effect of Lewisite.

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Prophylactic efficacy of amifostine and its analogues against sulphur mustard toxicity. Vijayaraghavan, R.; Kumar, P.; Joshi, U.; Raza, S. K.; Lakshmana Rao, P. V.; Malhotra, R. C.; Jaiswal, D. K. Defence Research and Development Establishment, Gwalior, India. Toxicology (2001), 163(2-3), 83-91. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:299804 AN 2001:448565 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The successful implication of the chem. weapons convention stimulated research with a new vigor on the destruction of the stockpiled sulfur mustard (SM). A prophylactic agent for SM will be very useful for personnel engaged in the destruction of SM and during inspections by the Organization for the Prohibition of Chem. Weapons. Due to simple method of prepn., SM can be used clandestinely during war or by terrorist groups. Inspite of research over several decades no satisfactory prophylactic or treatment regimen has evolved for SM. Amifostine an organophosphorothioate, originally developed as a radioprotector, and its analogs were evaluated as a prophylactic agent for SM. Three analogs by varying the chain length and substitution at the sulfur atom were synthesized and coded as DRDE-06, DRDE-07 and DRDE-08. LD50 of amifostine and its analogs were estd. through i.p. route. For the protection studies, amifostine and its analogs were administered i.p. in mice, 30 min before dermal (percutaneous) application of SM. The dose of the prophylactic agent was 0.2 LD50 (i.p.) and that of SM was 152 mg/kg (undiluted) equal to 19-fold LD50 of SM. Amifostine and one of its analogs, DRDE-07 gave significant protection. Further studies were carried out using amifostine and DRDE-07, and both of them significantly protected mice against SM (155 mg/kg, in PEG 300, equal to 19 LD50) when they were administered i.p. either 30 min before or simultaneously. LD50 of amifostine and DRDE-07 were also estd. through the oral route (1049 or 1248 mg/kg, resp.). Prophylactically administered amifostine and DRDE-07 (0.2 LD50, p.o.) significantly protected the mice against dermally applied SM (155 mg/kg, in PEG 300, equal to 19 LD50). The protection offered by DRDE-07 was better than that of amifostine by the oral route. DRDE-07 (0.2 LD50, p.o.) also protected significantly with respect to the decrease in body wt. and the depletion of GSH induced by SM.
DNA damage induced by SM was also significantly reduced by amifostine and DRDE-07 (0.2 LD50, p.o.). Further studies are in progress on the various pharmacol. and toxicol. properties of DRDE-07.

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Adsorption of Organic Contaminants from Water Using Tailored ACFs. Mangun, Christian L.; Yue, Zhongren; Economy, James; Maloney, Stephen; Kemme, Patricia; Cropek, Donald. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, USA. Chemistry of Materials (2001), 13(7), 2356-2360. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 135:200059 AN 2001:428900 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Six activated carbon fibers (ACFs) with different chem. and phys. properties were prepd. by 1st curing a phenolic resin-coated glass fiber, followed by activation and post-treatment. Their adsorption properties were studied to evaluate the removal of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and the chem. warfare simulants diisopropylmethyl phosphonate (DIMP) and half mustard (HM) from water. The adsorption isotherms showed that ACF SL-2 (activated with CO2/H2O at 800) has a higher adsorption capacity for BTEX, DIMP, and HM than other ACFs. This suggests that the high adsorption affinity of SL-2 is related to its higher surface area, larger av. micropore size of 11.6 .ANG. (esp. effective for the adsorption of DIMP), and lower O content of the surface. The adsorption isotherms are well represented by the Freundlich equation. For BTEX, the adsorption parameters based on C coating showed that, in all cases, ACFs have a higher K value than the best available data obtained on granulated activated C. The adsorption isotherms of DIMP and HM on ACFs are presented.

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The U.S. Army reactive topical skin protectant (rTSP): challenges and successes. Hobson, Stephen T.; Lehnert, Erich K.; Braue, Ernest H., Jr. Drug Assessment Division, U. S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Materials Research Society Symposium Proceedings (2001), 628(Organic/Inorganic Hybrid Materials), CC10.8.1-CC10.8.8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 135:118044 AN 2001:354344 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In 1994, the U.S. Army initiated a research effort towards an effective material that acts both as a protective barrier and as an active destructive matrix against chem. warfare agents (CWA). We report results on our prepn. and evaluation of Reactive Topical Skin Protectants (rTSP's). These creams are composite materials consisting of a base material (TSP) and a reactive moiety. Using an established base of perfluorinated-polyether and perfluoropolyethylene solids we incorporated over 60 reactive components. Classes tested include org. polymers, org./inorg. hybrid materials, polyoxometallates (POM's), enzymes, inorg. oxides, metal alloys and small mols. We characterized these materials by light microscopy and FTIR. We detd. the efficacy of these materials against both sulfur mustard (HD) and a representative nerve agent, soman (GD), using a penetration cell model coupled to a continuous air monitor and also by in vivo testing. Composite materials with optimum reactive compds. exhibit a 94% redn. of GD vapor break-through after 20 h (from 9458 ng to 581 ng) and a 3.6 fold increase (from 162 min to 588 min) in the time 1000 ng of GD liq. penetrates through the material. Similar composite materials show a 99% redn. in HD vapor break-through after 20 h (from 4040 ng to 16 ng), a 2.3 fold increase (from 524 min to > 1200 min) in the time 1000 ng of HD vapor penetrates through the material, and an elimination of erythema vs. control in an HD vapor challenge. These results indicate that an rTSP that protects against sulfur mustard and nerve agents is within reach.

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Inhibition and promotion of combustion by organophosphorus compounds added to flames of CH4 or H2 in O2 and Ar. Korobeinichev, O. P.; Bolshova, T. A.; Shvartsberg, V. M.; Chernov, A. A. Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia. Combustion and Flame (2001), 125(1/2), 744-751. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 134:328437 AN 2001:309769 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Early in evaluating the destruction mechanisms of a no. of organophosphorus compds. (OPCs), such as tri-Me phosphate (TMP), di-Me methylphosphonate, and diisopropyl methylphosphonate, in connection with the disposal of chem. warfare agents, the promotion and inhibition effects of OPCs on stabilized flat flames of H2 +O2 were studied. Because OPCs were demonstrated to be more effective fire suppressants than CF3Br (Halon 1301) and due to the need for replacing the currently used Halon 1301, further investigation of the effects of the OPCs on flames is of interest. Thus a lean flame of CH4/O2/Ar (0.078/0.222/0.7) with and without TMP added, stabilized on a flat burner at 0.1 bar, was studied by mol. beam mass spectrometry (MBMS) and computer modeling using PREMIX and CHEMKIN codes. An exptl. study of this flame revealed that TMP increases the width of the reaction zone by inhibiting the flame.

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An Infrared Study of Adsorbed Organophosphonates on Silica: A Prefiltering Strategy for the Detection of Nerve Agents on Metal Oxide Sensors. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2001), 17(7), 2213-2218. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 134:349067 AN 2001:156303 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The gas-phase adsorption of the nerve gas simulant di-Me methylphosphonate (DMMP) along with tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on silica have been studied using IR spectroscopy. Each phosphonate compd. adsorbs through a different no. of H-bonds of the methoxy and P:O moieties with the surface hydroxyl groups on silica. The strength of the adsorption depends on the no. and type of the H-bonds and follows the order TCP < MDCP < DMMP < TMP. TCP is completely removed from silica by evacuation at room temp., adsorbed MDCP is removed by evacuation at 150 C, DMMP requires an evacuation temp. of 300 C, and TMP is eliminated at 400 C. All phosphonate compds. molecularly desorb, and the silica returns to its original state. The differences in the reactivity of phosphonate compds. on silica from other oxides demonstrate the potential use of silica in prefiltering/preconcg. strategies for semiconductive metal oxide based sensing devices. Specifically, it is shown that silica can be used to selectively adsorb DMMP from a gas stream contg. methanol/DMMP mixts.

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Reactions of VX, GB, GD, and HD with Nanosize Al2O3. Formation of Aluminophosphonates. Wagner, George W.; Procell, Lawrence R.; O'Connor, Richard J.; Munavalli, Shekar; Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA. Journal of the American Chemical Society (2001), 123(8), 1636-1644. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 134:276643 AN 2001:85006 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of VX, GB, GD, and HD with nanosize Al2O3 (AP-Al2O3) have been characterized by 31P, 13C, and 27Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH3)OR]3, are generated which are identical to synthesized model compds. Thus, the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amt. of the CH-TG sulfonium ion (12%), although some elimination of HCl is also obsd. (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addn. of excess water results in the quant. hydrolysis of sorbed HD to CH-TG. On AP-Al2O3 dried to remove physisorbed water, 13C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

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New microemulsions for oxidative decontamination of mustard gas analogues and polymer-thickened half-mustard. Gonzaga, Ferdinand; Perez, Emile; Rico-Lattes, Isabelle; Lattes, Armand. Laboratoire des Interactions Moleculaires et Reactivite Chimique et Photochimique (CNRS UMR 5623), Universite Paul Sabatier, Toulouse, Fr. New Journal of Chemistry (2001), 25(1), 151-155. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 134:232826 AN 2001:12053 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidn. of mustard gas analogs in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quant. and chemoselective oxidn. of the analogs. In a second formulation, the choice of microemulsion components used allowed us to study the oxidn. of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aq. systems.

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Bacterial release of arsenic ions and organoarsenic compounds from soil contaminated by chemical warfare agents. Kohler, Manfred; Hofmann, Klaus; Volsgen, Fernando; Thurow, Kerstin; Koch, Andreas. URST Umwelt- und Rohstoff-Technologie GmbH, Greifswald, Germany. Chemosphere (2000), Volume Date 2001, 42(4), 425-429. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 134:60919 AN 2000:878002 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The objective was to study possible participation of microorganisms in the release of sol. arsenical compds. from organoarsenic warfare agents in contaminated soil. A no. of bacterial strains were isolated with high resistance against As5+ ions which are able to degrade the water insol. compds. triphenylarsine (TP) and triphenylarsineoxide (TPO). Release of As and sol. organoarsenic compds. from soil by the activity of autochthonic soil bacteria and a mixt. of the isolated pure cultures was demonstrated by percolation expts. with undisturbed soil samples (core drills) from the contaminated site. This release increased after addnl. of nutrients (mineral N and P, Na acetate and ethanol) and is nearly independent of the percolation temp. (5 and 22). These results show that bacteria play an important role in the release of arsenical compds. from organoarsenic warfare agent contaminated soil. This release is limited by shortage of water and, above all, of nutrients for the microorganisms in the sandy forest soil. These results are important both for the management and security and possibly for bioremediation of military waste sites contg. similar contaminations.

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The chemistry of the destruction of organophosphorus compounds in flames-IV: destruction of DIMP in a flame of H2 + O2 + Ar. Korobeinichev, O. P.; Chernov, A. A.; Bolshova, T. A. Institute of Chemical Kinetics and Combustion, Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia. Combustion and Flame (2000), 123(3), 412-420. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 133:285779 AN 2000:714913 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mol. beam mass spectrometry with electron impact ionization at 11-70 eV and an electron energy spread of  0.25 eV was used to study the structure of a premixed H2/O2/Ar (0.26/0.13/0.61) flame without any additives and with 0.14% of diisopropylmethylphosphonate (DIMP), stabilized on a flat-flame burner at 62 mbar. Stable species (H2, O2, H2O), as well as atoms and radicals (H, O, OH) were monitored, including phosphorus-contg. compds.: DIMP and some intermediates of its destruction, phosphorus oxides and acids. The profiles of the mole fractions of most species, including those of atoms and free radicals were obtained. The calibration coeffs. for some species were detd. exptl., and estd. for others. Isopropylmethylphosphonate was detected as a main primary phosphorus-contg. product of the destruction of DIMP. It has been shown that bimol. reactions with hydroxyl radicals and hydrogen atoms, rather than a unimol. decompn., provide the crucial initial steps in the destruction of DIMP. A detailed mechanism for the destruction of DIMP in H2/O2/Ar flames is suggested.

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Cytotoxicity of the MEIC reference chemicals in rat hepatoma-derived Fa32 cells. Dierickx, P. J. Laboratorium Biochemische Toxikologie, Afdeling Toxikologie, Instituut voor Volksgezondheid, Brussels, Belg. Toxicology (2000), 150(1-3), 159-169. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 134:1437 AN 2000:660792 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The cytotoxicity of the MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) ref. chems. was investigated in rat hepatoma-derived Fa32 cells. The total protein content was measured as an endpoint after exposure times of 30 min and 24 h, both in normal and glutathione-depleted cells. The neutral red uptake inhibition and the MTT conversion were also measured after 30 min. On av., the cytotoxicity was higher in glutathione-depleted cells when compared to normal cells, and was lower after 30 min than after 24 h. Evidence was obtained for lysosomal attack (of five chems.) or mitochondrial dysfunction (of six chems.) as the primary intoxication mechanism. Malathion and mercuric chloride belong to both series of chems. Good to excellent correlations were obsd. when the 50% inhibitory concns. of the six different in vitro assays were compared. When the six in vitro assays in Fa32 cells were compared with the human toxicity, the correlation coeff. was almost always identical to that obtained previously in human hepatoma-derived Hep G2 cells. The latter was the best acute in vitro assay for the prediction of human toxicity within the MEIC study. Altogether the results integrate very well with the basal cytotoxicity concept (B. Ekwall; 1995).

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The role of time in toxicology or Haber's ct product. Rozman, K. K. Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA. Toxicology (2000), 149(1), 35-42. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 133:306404 AN 2000:589244 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It happened exactly 100 yr ago that Warren established for the first time a quant. link between dose and time while studying the toxicity of sodium chloride in Daphnia magna (Straus). During this century many toxicologists in different contexts returned to this idea, which has become known as Haber's rule of inhalation toxicol. Most attempts to explore this relationship ended in frustration because of the supposed occurrence of exceptions. Thus, toxicologists concd. on the quant. relationship between dose and effect under mostly isotemporal conditions while time took a back seat and was assigned such arbitrary, semiquant. designations as acute, subacute, subchronic and chronic. Time itself as a quantifiable variable of toxicity was seldom studied and when it was studied, it was often not under isodosic (steady state) conditions as required by theory. A recent anal. of toxicol. time indicated the impact of three independent time scales (toxicokinetic, toxicodynamic, exposure frequency/duration) in toxicol. studies, which interact with dose and effect to yield the enormous complexity known to every toxicologist. Based on prototypical examples when toxicokinetic (dioxins), toxicodynamic (nitrosamines, benzene) or exposure frequency (methylene chloride, chloroacetic acid, HgCl2, CdCl2, etc.) represent the crit. time scale, the general validity of the ct=k concept will be discussed as a starting point for a theory of toxicol. As endpoints of toxicity, (delayed) acute toxicity, blood dyscrasias and cancer will be used to illustrate the crit. conditions needed to demonstrate the validity of this theory.

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Detection of Fluorophosphonate Chemical Warfare Agents by Catalytic Hydrolysis with a Porous Silicon Interferometer. Sohn, Honglae; Letant, Sonia; Sailor, Michael J.; Trogler, William C. Department of Chemistry and Biochemistry, University of California at San Diego, CA, USA. Journal of the American Chemical Society (2000), 122(22), 5399-5400. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 133:100551 AN 2000:335868 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The detection of a fluorophosphonate nerve chem. warfare agent can be achieved with an oxidized porous silicon interferometer film contg. a Cu(II) hydrolysis catalyst and surfactant (CTAB). Hydrolysis of the nerve agent produces HF gas, which removes the silicon oxide as SiF4(g) and induces both a blue-shift and a decrease in intensity of the Fabry-Perot fringes. Significant changes in these 2 parameters are detected after 5 min of DFP vapor (800 ppm) exposure.

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Reactions of VX, GD, and HD with Nanosize CaO: Autocatalytic Dehydrohalogenation of HD. Wagner, George W.; Koper, Olga B.; Lucas, Erik; Decker, Shawn; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, MD, USA. Journal of Physical Chemistry B (2000), 104(21), 5118-5123. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 133:30783 AN 2000:281288 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of the chem. warfare agents VX, GD, and HD with nanosize CaO (AP-CaO), and HD with com. CaO were studied using solid-state MAS NMR. VX and GD hydrolyze to yield surface-bound complexes of nontoxic Et methylphosphonate and pinacolyl methylphosphonate, resp. The kinetics were characterized by an initial fast reaction followed by a slower, diffusion-limited reaction. Similar behavior is obsd. for HD on either dried or hydrated AP-CaO and CaO. On partially hydrated AP-CaO (but not CaO), a rather fast steady-state elimination of HCl occurs after an induction period. This behavior is attributed to acid-catalyzed surface reconstruction (to regenerate fresh surface) and the formation of CaCl2, which is known to be more reactive than CaO. The product distribution for HD is .apprx.80% divinyl sulfide and 20% thiodiglycol and/or sulfonium ions, which apparently reside as surface alkoxides. Such kinetic behavior was not evident for the common mustard simulant 2-chloroethyl Et sulfide (CEES) on partially hydrated AP-CaO, which exhibited only the typical fast/diffusion-limited reaction.

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Design and synthesis of an ,-difluorophosphinate hapten for antibody-catalyzed hydrolysis of organophosphorus nerve agents. Vayron, Philippe; Renard, Pierre-Yves; Valleix, Alain; Mioskowski, Charles. CEA, Service des Molecules Marquees, CE-Saclay, Gif sur Yvette, Fr. Chemistry--A European Journal (2000), 6(6), 1050-1063. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 133:13524 AN 2000:214064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In a new approach to the safe neutralization of organophosphorus chem. weapons, we designed a hapten to elicit catalytic antibodies with phosphatase activity. Here we report the synthesis of this ,-difluorophosphinate hapten 6. Various methods for the introduction of the key ,-difluoromethyl feature into the phosphinate hapten are discussed. The best results were obtained with the electrophilic gem-difluorinating agent N-fluorobenzenesulfonimide.

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Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate. Richardson, David E.; Yao, Huirong; Frank, Karen M.; Bennett, Deon A. Center for Catalysis Department of Chemistry, University of Florida, Gainesville, FL, USA. Journal of the American Chemical Society (2000), 122(8), 1729-1739. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 132:222157 AN 2000:94955 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Bicarbonate ion is an effective activator for hydrogen peroxide in the oxidn. of sulfides. Kinetic and spectroscopic results support the formation of peroxymonocarbonate ion (HCO4-) as the oxidant in the catalytic reactions. The reaction of hydrogen peroxide and bicarbonate to form HCO4- occurs rapidly at 25 (t1/2  300 s) near neutral pH in aq. soln. and alc./water mixts., and an equil. anal. of the reaction by 13C NMR leads to an est. of the electrode potential for the HCO4-/HCO3- couple (1.8 V vs NHE). Soly. of the bicarbonate catalyst is enhanced by the use of NH4HCO3 rather than by the use of group 1 salts, which tend to have lower soly. in the mixed solvents and can lead to phase sepn. Rate laws and mechanistic analyses are presented for the oxidn. of Et Ph sulfide and related sulfides. The second-order rate consts. for sulfide oxidns. by HCO4- are .apprx.300-fold greater than those for H2O2, and this increase is consistent with expectations based on a Bronsted anal. of the kinetics for other heterolytic peroxide oxidns. At high concns. of H2O2, a pathway that is second order in H2O2 is significant, and this path is interpreted as a general acid catalysis by H2O2 of carbonate displacement accompanying substrate attack at the electrophilic oxygen of HCO4-. Increasing water content up to 80% in the solvent increases the rate of oxidn. The BAP (bicarbonate-activated peroxide) oxidn. system is a simple, inexpensive, and relatively nontoxic alternative to other oxidants and peroxyacids, and it can be used in a variety of oxidns. where a mild, neutral pH oxidant is required. Variation of bicarbonate source and the cosolvent can allow optimization of substrate soly. and oxidn. rates for applications such as org. synthesis and chem. warfare agent decontamination.

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Synthesis and Characterization of a Functionalized Double-Chain Surfactant and Its Cleavage of O-Methyl S-Benzyl Phenylphosphonothioate. Jaeger, David A.; Li, Bei. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (2000), 16(1), 5-10. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 132:24141 AN 1999:379097 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant 2-hydrazino-N-methyl-N,N-didodecyl-2-oxoethanaminium bromide (I) was synthesized, and its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry. In a pH 9.0 borate buffer at 25, vesicular I and O-Me S-benzyl phenylphosphonothioate (II), a simulant for the chem. warfare agent VX [O-Et S-(2-N,N-diisopropylamino)ethyl methylphosphonothioate] reacted to give anion S-benzyl phenylphosphonothioate (III) and 3 cations (2-(2-N-methylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, 2-(2-N,N-dimethylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, and 2-[1-hydroxy-2-(N-methyl-N,N-didodecylammonio)ethylidene]-N',N',N'-trimethylhydrazinium, resp.) by SN2 substitution on the Me group of II. This reaction was accompanied by the pptn. of anion III with surfactant cations, which resulted in wounding/destruction of the vesicles. The combination of vesicle damage and reaction of II suggests the potential of vesicular systems for simultaneous signaling and decontamination of chem. agents. Ester II hydrolyzed in 0.10 M NaOH at 25 to give anions III and O-Me phenylphosphonothioate in a 38:62 ratio, resp.

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Reactivation kinetics of acetylcholinesterase from different species inhibited by highly toxic organophosphates. Worek F; Reiter G; Eyer P; Szinicz L Sanitatsakademie der Bundeswehr, Institut fur Pharmakologie und Toxikologie, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2002 Sep), 76(9), 523-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242610 AN 2002479746 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Standard treatment of poisoning by organophosphates (OP) includes the administration of an antimuscarinic agent, e.g. atropine, and of an acetylcholinesterase (AChE) reactivator (oxime). The presently available oximes, obidoxime and pralidoxime (2-PAM), are considered to be insufficient for highly toxic OPs, e.g. sarin. In the past decades numerous oximes were prepared and tested for their efficacy in OP poisoning, mostly in animal experiments. However, data indicate that the reactivating potency of oximes may be different in humans and animal species, which may hamper the extrapolation of animal data to humans and may pose a problem in the drug licensing of new compounds. In order to provide data for a better evaluation of the reactivating potency of oximes, experiments were undertaken to determine the reactivation rate constants of several oximes with human, rabbit, rat and guinea-pig AChE inhibited by the OPs sarin, cyclosarin and VX. The results show marked differences among the species, depending on the inhibitor and on the oxime, and indicate that the findings from animal experiments need careful evaluation before extrapolating these data to humans.

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Skin toxicokinetics of mustard gas in the guinea pig: effect of hypochlorite and safety aspects. Wormser Uri; Brodsky Berta; Sintov Amnon Faculty of Sciences,The Hebrew University, Edmond Safra Campus, Givat Ram, Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2002 Sep), 76(9), 517-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242609 AN 2002479745 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (SM, mustard gas) is a chemical warfare vesicant that rapidly penetrates the skin due to its hydrophobicity. This study measured the rate of SM disappearance from the skin after topical application of the vesicant. In both fur-covered and hairless animals, the remaining toxicant levels measured 60 min after exposure to undiluted SM were 0.6% and 0.3%, respectively, of the initially applied SM amount. However, SM concentration reached 0.4% of the initial dose 3 h following exposure in female fur-covered guinea pigs. SM quantities extracted from skin of male fur-covered and hairless guinea pigs immediately after 16 min of exposure to SM vapor were 12.2 and 21.8 microg, respectively; levels declined to 1.6 and 1.7 microg at 30 and 15 min following termination of exposure of male fur-covered and hairless guinea pigs, respectively. Three swabbing treatments of undiluted SM-exposed skin with gauze pads soaked in 0.5% hypochlorite caused 68% reduction in skin SM content. Similar findings were obtained when hypochlorite was replaced by water (64% reduction). SM content in the gauze pads was 59, 38 and 25 microg, respectively, for the first, second and third decontamination processes with water. No SM was detected in the gauze pads soaked with hypochlorite. In vitro studies showed that incubation of SM with 0.5% hypochlorite at a ratio of 10:1 (v/v) did not cause SM inactivation, whereas 4% hypochlorite reduced SM levels by 17%. However, at a decontaminant:SM ratio of 1000:1, 0.5% and 4% hypochlorite reduced SM levels by 92% and 99%, respectively. These findings are important for health authorities and regulatory agencies in planning precautionary steps to be taken in case of emergency and in routine laboratory work.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock Shannon D; Till Gerd O; Smith Milton G; Ward Peter A Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602, USA Journal of applied toxicology : JAT (2002 Jul-Aug), 22(4), 257-62. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12210543 AN 2002449749 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The chemical warfare agent analog, 2-chloroethyl ethyl sulfide, known as 'half-mustard gas' (HMG), is less toxic and less of an environmental hazard than the full molecule and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of (125)I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, we observed significant attenuation of the pulmonary injury when experimental animals were complement or neutrophil depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, dimethyl sulfoxide, dimethyl thiourea, resveratrol and N-acetyl-L-cysteine (NAC). The last compound showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement mediated pathways and the generation by neutrophils of toxic oxygen species The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat. Copyright 2002 John Wiley & Sons, Ltd.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber Ellen; McGuire Raymond Environment Protection Department, Lawrence Livermore National Laboratory, University of California, P.O. Box 808, L-626, Livermore, CA 94551, USA Journal of hazardous materials (2002 Aug 5), 93(3), 339-52. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12137994 AN 2002389537 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A decontamination method has been developed using a single reagent that is effective both against chemical warfare (CW) and biological warfare (BW) agents. The new reagent, "L-Gel", consists of an aqueous solution of a mild commercial oxidizer, Oxone, together with a commercial fumed silica gelling agent, Cab-O-Sil EH-5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. The new reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Experiments to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Laboratory and independently at four other locations. L-Gel was tested against all classes of chemical warfare agents and against various biological warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biological agents. Testing showed that L-Gel is as effective against chemical agents and biological materials, including spores, as the best military decontaminants.

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Adamantyl tenocyclidines--adjuvant therapy in poisoning with organophosphorus compounds and carbamates. Erratum in: Arch Toxicol 2002 Sep;76(9):552 Skare Danko; Radic Bozica; Lucic Ana; Peraica Maja; Domijan Ana-Marija; Milkovic-Kraus Sanja; Bradamante Vlasta; Jukic Ivan Institute Ruder Boskovic, Bijenicka c. 54, 10000 Zagreb, Croatia. skare@rudjer.irb.hr Archives of toxicology (2002 Apr), 76(3), 173-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11967623 AN 2002328057 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The objective of this study was to evaluate the efficacy of thienyl phencyclidine (tenocyclidine, TCP) and its newly synthesized adamantyl derivatives containing piperidine (TAPIP), pyrolidine (TAPIR) and morpholine (TAMORF) groups, which were tested with or without standard therapy in mice poisoned with organophosphates (OPs) and carbamates. These compounds with potential activity at the N-methyl- D-aspartate and muscarinic receptors showed low acute toxicity, having LD50 values varying from 106.00 mg/kg (TCP) to >504.00 mg/kg body weight (TAMORF). TCP and its adamantyl derivatives were administered intraperitoneally (2.5 mg/kg body weight) together with atropine (10.0 mg/kg body weight) and with or without 1/4 LD50 of the oxime HI-6. Each compound administered with atropine had a therapeutic effect against poisoning with carbamates propoxur, aldicarb and Ro 02-0683 (protective ratio of tenocyclidines was from 3.99 LD50 of aldicarb to >16.00 LD50 for propoxur). However, the efficacy of those compounds in combination with atropine was lower against poisoning with the OP insecticide dichlorvos (DDVP) and chemical warfare agents soman and tabun. In soman-poisoned mice, the best therapeutic effects were obtained with the combination of HI-6 plus atropine and test compounds, with protective ratios being from 5.40 to 7.12 LD50 of soman. The results suggest that TCP and adamantyl tenocyclidines could be used in combination with atropine as antidotes in carbamate poisoning and as adjuvant therapy to HI-6 and atropine in soman poisoning.

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Site-specific percutaneous absorption of methyl salicylate and VX in domestic swine. Duncan E J Scott; Brown April; Lundy Paul; Sawyer Thomas W; Hamilton Murray; Hill Ira; Conley John D Chemical Biological Defence Section, Defence Research Establishment, Suffield, PO Box 4000, Station Main, Medicine Hat, Alberta, Canada T1A 8K6 Journal of applied toxicology : JAT (2002 May-Jun), 22(3), 141-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12015792 AN 2002313565 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The site specificity of the percutaneous absorption of methyl salicylate (MeS) and the organophosphate nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) was examined in anaesthetized domestic swine that were fully instrumented for physiological endpoints. Four different anatomical sites (ear, perineum, inguinal crease and epigastrium) were exposed to the MeS and the serum levels were measured over a 6-h time period. The dose absorbed at the ear region was 11 microg cm(-2) with an initial flux of 0.063 microg cm(-2)min(-1), whereas at the epigastrium region the dose absorbed was 3 microg cm(-2) with an initial flux of 0.025 microg cm(-2)min(-1). For this reason further studies were carried out with VX on the ear and the epigastrium only. In animals treated with agent on the epigastrium, blood cholinesterase (ChE) activity began to drop 90 min after application and continued to decline at a constant rate for the remainder of the experiment to ca. 25% of awake control activity. At this time there were negligible signs of poisoning and the medical prognosis was judged to be good. In contrast, the ChE activity in animals receiving VX on the ear decreased to 25% of awake control values within 45 min and levelled out at 5-6% by 120 min. Clinical signs of VX poisoning paralleled the ChE inhibition, progressing in severity over the duration of the exposure. It was judged that these animals would not survive. The dramatic site dependence of agent absorption leading to vastly different toxicological endpoints demonstrated in this model system has important ramifications for chemical protective suit development, threat assessment, medical countermeasures and contamination control protocols. Copyright 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

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An improved brain slice model of nerve agent-induced seizure activity. Wood S J; Tattersall J E Biomedical Sciences Department, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S83-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920926 AN 2002191151 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice preparation. Soman (1 microM) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists, but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice preparation is a suitable model for investigating the origin and propagation of nerve-agent-induced seizures within the limbic system. Copyright 2001 John Wiley & Sons, Ltd.

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Cardiopulmonary effects of HI-6 treatment in soman intoxication. Goransson-Nyberg A; Cassel G Division of NBC Defence, Department of Medical Counter Measures, Swedish Defence Research Agency, SE-90182 Umea, Sweden Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S79-81. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920925 AN 2002191150 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The cardiopulmonary effects of HI-6, together with atropine and soman, were studied in the rat. HI-6 is an effective antidote in acute poisoning with the nerve agent soman. The therapeutic efficiency of HI-6 is still unclear and cannot be explained entirely by the HI-6 reactivating ability of acetylcholinesterase (AChE). Other non-cholinergic factors must be involved. One possible detoxifying process might be an effect of HI-6 on the blood flow to sensitive organs. The purpose of the present study was to investigate 1) whether soman per se induces changes in regional blood flow and 2) whether the blood flow to different organs is affected when HI-6 (50 mg x kg(-1) i.m.) and atropine (10 mg x kg(-1) i.m.) are given either before or immediately after soman intoxication (90 microg x kg(-1) s.c.). For regional blood flow determinations the microsphere method was used with male Wistar rats weighing 300-400 g. The rats were anaesthetised and breathed spontaneously during the experiment. Three different blood flow measurements were made in the same animal and concomitant physiological parameters such as mean arterial blood pressure and respiratory rate were recorded. The blood AChE activity was followed throughout the experiment. Our results show that when HI-6 is given after intoxication with soman, dramatic changes in blood flow occur with a significant decrease in both respiratory rate and blood AChE activity. If HI-6 is given prior to the intoxication, however, all rats are unaffected and none of the parameters measured are changed. Copyright 2001 John Wiley & Sons, Ltd.

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Prophylaxis against organophosphate poisoning by sustained release of scopolamine and physostigmine. Meshulam Y; Cohen G; Chapman S; Alkalai D; Levy A Department of Pharmacology, Israel Institute for Biological Research (IIBR), PO Box 19, 70450 Ness-Ziona, Israel Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S75-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920924 AN 2002191149 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Protection efficacy of continuous prophylactic administration of physostigmine and scopolamine against sarin-induced toxicity was evaluated previously in guinea pigs. The present study in large animals used Beagle dogs, that serve as an animal model with cholinergic sensitivity similar to that of humans. Pretreatment with physostigmine salicylate and scopolamine hydrochloride at dose rates of 2.5 and 1 microg x kg(-1) x h(-1), respectively, was administered via Alzet mini-osmotic pumps. At the time of exposure, the physostigmine salicylate concentration in plasma was 0.7 ng x ml(-1) and the scopolamine hydrochloride concentration was ca. 0.2 ng x ml(-1), both of which are levels known to be well tolerated in humans. Whole-blood cholinesterase inhibition was 15-20%. This regimen conferred full protection against 2.5 x LD50 i.v. of sarin. Albeit the high-dose exposure, cholinergic toxicity symptoms were mild with no convulsions. About 11-14 min following poisoning the treated animals started to walk and 15-20 min following exposure full recovery was observed and the dogs behaved normally. With higher dose rates of physostigmine salicylate and scopolamine hydrochloride, at plasma concentrations of 2.1 and 0.6 ng x ml(-1), respectively, treated dogs regained normal posture 6-10 min after exposure. Copyright 2001 John Wiley & Sons, Ltd.

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Intramuscular diazepam pharmacokinetics in soman-exposed guinea pigs. Capacio B R; Whalley C E; Byers C E; McDonough J H Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S67-74. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920923 AN 2002191148 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Intramuscular (i.m.) diazepam is included by the US military as an anticonvulsant in the standard therapeutic regimen for organophosphorus nerve agent intoxication. In this study we investigated the pharmacokinetics of diazepam after i.m. administration while monitoring pharmacodynamic (electroencephalogram, EEG) data in soman-exposed guinea pigs. Prior to experiments the animals were surgically implanted with EEG leads to monitor seizure activity. For the study, animals were administered pyridostigmine (0.026 mg x kg(-1) i.m.) 30 min prior to soman (56 microg x kg(-1), 2 x LD50; subcutaneously, s.c.), which was followed in 1 min by atropine sulfate (2 mg x kg(-1) i.m.) and pralidoxime chloride (25 mg x kg(-1) i.m.). All animals receiving this regimen developed seizure activity. Diazepam (10 mg x kg(-1) i.m.) was administered 5 min after onset of seizure activity. Based on EEG data, animals were categorized as either seizure terminated or not terminated at 30 min after diazepam. Serial blood samples were obtained from each animal. Diazepam (10 mg x kg(-1) i.m.) terminated seizure activity in 52% of the animals within 30 min. The pharmacokinetics were characterized by a one-compartment model with first-order absorption and elimination. The maximum plasma concentrations (Cmax) were 991 and 839 ng x ml(-1) for seizure terminated and not terminated, respectively. Mean plasma concentrations of diazepam were significantly different (P < 0.05) for seizure terminated vs not terminated groups at 30 min. The plasma Cmax in seizure-terminated animals in this study is similar to the minimum range of plasma diazepam (200-800 ng x ml(-1)) reported to suppress seizure activity in humans. It has been reported in an earlier study that the minimum effective i.m. dose (0.1 mg x kg(-1)) required to prevent soman-induced convulsions in Rhesus monkeys produces a mean Cmax of 50 ng x ml(-1) for diazepam.
The data from our current study suggest that a higher dose (and corresponding Cmax) is necessary to terminate ongoing seizure activity. Copyright 2001 John Wiley & Sons, Ltd.

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Combination anticonvulsant treatment of soman-induced seizures. Koplovitz I; Schulz S; Shutz M; Railer R; Macalalag R; Schons M; McDonough J Drug Assessment Division, US Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010, USA. Koplovitz@asia.apgea.army.mil Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S53-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920921 AN 2002191147 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures. Copyright 2001 John Wiley & Sons, Ltd.

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Soman-induced seizures: limbic activity, oxidative stress and neuroprotective proteins. Pazdernik T L; Emerson M R; Cross R; Nelson S R; Samson F E Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City, KS 66160, USA. tpazdern@kumc.edu Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S87-94. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920927 AN 2002185330 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman, a potent acetylcholinesterase inhibitor, induces status epilepticus in rats followed by conspicuous neuropathology, most prominent in piriform cortex and the CA3 region of the hippocampus. Cholinergic seizures originate in striatal-nigral pathways and with fast-acting agents (soman) rapidly spread to limbic related areas and finally culminate in a full-blown status epilepticus. This leads to neurochemical changes, some of which may be neuroprotective whereas others may cause brain damage. Pretreatment with lithium sensitizes the brain to cholinergic seizures. Likewise, other agents that increase limbic hyperactivity may sensitize the brain to cholinergic agents. The hyperactivity associated with the seizure state leads to an increase in intracellular calcium, cellular edema and metal delocalization producing an oxidative stress. These changes induce the synthesis of stress-related proteins such as heat shock proteins, metallothioneins and heme oxygenases. We show that soman-induced seizures cause a depletion in tissue glutathione and an increase in tissue 'catalytic' iron, metallothioneins and heme oxygenase-1. The oxidative stress induces the synthesis of stress-related proteins, which are indicators of 'stress' and possibly provide neuroprotection. These findings suggest that delocalization of iron may catalyze Fenton-like reactions, causing progressive cellular damage via free radical products. Copyright 2001 John Wiley & Sons, Ltd.

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Beneficial effects of TCP on soman intoxication in guinea pigs: seizures, brain damage and learning behaviour. de Groot D M; Bierman E P; Bruijnzeel P L; Carpentier P; Kulig B M; Lallement G; Melchers B P; Philippens I H; van Huygevoort A H TNO Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S57-65. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920922 AN 2002185328 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Poisoning with the potent nerve agent soman produces a cascade of central nervous system (CNS) effects characterized by severe convulsions and eventually death. In animals that survive a soman intoxication, lesions in the amygdala, piriform cortex, hippocampus and thalamus can be observed. In order to examine the mechanisms involved in the effects of soman and to evaluate possible curative interventions, a series of behavioural, electrophysiological and neuropathological experiments were carried out in the guinea pig using the NMDA antagonist N-[1-(2-thienyl)cyclohexyl] piperidine (TCP) in conjunction with atropine and pyridostigmine. The NMDA antagonist TCP appeared to be very effective in the treatment of casualties who suffered from soman-induced seizures for 30 min: (i)Seizures were arrested within minutes after the TCP injection, confirmed by quantitative electroencephalogram (EEG), after fast Fourier analysis. Three hours after TCP the quantitative EEGs were completely normal in all frequency bands and remained normal during the entire 3-week intoxication period. The power shift to the lower (delta) frequency bands, indicative for neuropathology and found in control animals intoxicated only by soman, was not observed in the soman-TCP group. (ii)The gross neuropathology found in soman control animals within 48 h after soman was prevented in soman-TCP animals and was still absent in 3-week survivors. Instead, ultrastructural changes were observed, indicative of defense mechanisms of the cell against toxic circumstances. (iii)Twenty-four hours after soman, soman-TCP animals were able to perform in the shuttle box and Morris water maze. The beneficial effects of TCP on the performance in these tests during the 3-week intoxication period were very impressive, notwithstanding (minor) deficits in memory and learning. (iv)The increase in excitability after TCP was confirmed by an increase in the acoustic startle response.
Taken together, these results confirmed the involvement of NMDA receptors in the maintenance of soman-induced seizures and the development of brain damage. They underline the current hypothesis that cholinergic mechanisms are responsible for eliciting seizure activity after soman and that, most likely, the subsequent recruitment of other excitatory neurotransmitters and loss of inhibitory control are responsible for the maintenance of seizures and the development of subsequent brain damage. Copyright 2001 John Wiley & Sons, Ltd.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw M D; Hayes T L; Miller T L; Shannon C M Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH 43201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S3-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920912 AN 2002185325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate--a V-type nerve agent developed by the former Soviet Union--in the environment is an important parameter in threat assessment analysis and for the determination of use, production, testing and storage of this chemical warfare agent. S-(N,N-Diethylaminoethyl) isobutyl methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same molecular formula, it is expected that their physical and chemical properties would be different. This preliminary investigation was undertaken to determine the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compound at approximately 1 mg x ml(-1) in unbuffered water at pH 7 was determined side-by-side. The half-lives for VXA and VX were determined to be 12.4 days and 4.78 days, respectively. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chemical Weapons Convention. Copyright 2001 John Wiley & Sons, Ltd.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller J K; Lenz D E Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD 21201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S23-6. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920916 AN 2002185323 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-molecular-weight compounds is effected by the use of chromatographic techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the analysis. To overcome those drawbacks, we have been involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds such as pinacolylmethyl phosphonofluoridate (soman), which is a chemical warfare agent. Prior estimates suggested that it is necessary to be able to detect soman at a concentration below 2.5 x 10(-7) M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The minimum required assay time was 2.0-2.5 h with no loss in sensitivity. To determine the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogues were 5 x 10(-7) M for 4-nitrophenylpinacolylmethylphosphonate, 8 x 10(-7) M for dipinacolylmethylphosphonate, 2 x 10(-6) M for diisopropylmethylphosphonate, 3 x 10(-5) M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5 x 10(-5) M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman molecule, were effective inhibitors. Compounds, which contained predominately aromatic groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to determine its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman. Copyright 2001 John Wiley & Sons, Ltd.

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Protective action of the serine protease inhibitor N-tosyl-L-lysine chloromethyl ketone (TLCK) against acute soman poisoning. Cowan F M; Broomfield C A; Lenz D E; Shih T M Biochemical Pharmacology and Neurotoxicology Branches, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 293-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481662 AN 2002027826 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman-poisoned rats display cholinergic crisis, a systemic mast cell degranulation characteristic of anaphylactic reactions and an excitotoxin-like sequential seizure and neuronal degeneration. The protection of guinea pigs from soman lethality by prophylactic administration of the serine protease inhibitor suramin suggests a possible proteolytic component in soman poisoning. The present study tested the effect of N-tosyl-L-lysine chloromethyl ketone (TLCK), an inhibitor of trypsin-like serine proteases, on soman-induced toxic signs (convulsions, righting reflex) and survival time. Nine control guinea pigs receiving 2 x LD(50) (56 microg kg(-1), s.c.) of soman immediately followed by a therapeutic dose of atropine sulfate (17.4 mg kg(-1) i.m.) experienced severe convulsions, and 8/9 lost the righting reflex. Six of these nine animals expired within 65 min; the three remaining animals survived 24 h to termination of the experiment. When a second group of animals were given TLCK (12 mg kg(-1), i.p.) 30 min prior to a 2 x LD(50) soman challenge and atropine-sulfate therapy, 5/9 experienced convulsions and only 3/9 lost the righting reflex. All nine animals survived beyond 4 h, with six surviving to 24 h. Compared with soman controls, prophylaxis with TLCK significantly prevented the loss of righting reflex (P = 0.05) and enhanced 4-h survival (P = 0.005). Although, convulsions were reduced and 24-h survival was improved in TLCK-treated animals, these results were not statistically significant. The protection from soman toxicity by chemically distinct protease inhibitors such as suramin and TLCK suggests a role for pathological proteolytic pathways in soman intoxication. Copyright 2001 John Wiley & Sons, Ltd.

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin. Chilcott R P; Jenner J; Hotchkiss S A; Rice P Department of Biomedical Sciences, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 279-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481660 AN 2002027824 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption. Copyright 2001 John Wiley & Sons, Ltd.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen J; Riikonen K; Nikmo J; Jappinen A; Nieminen K Air Quality Research, Finnish Meteorological Institute, Sahaajankatu 20 E, FIN-00810, Helsinki, Finland. jaakko.kukkonen@fmi.fi Journal of hazardous materials (2001 Aug 17), 85(3), 165-79. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11489522 AN 2001443815 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

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Effects of iodine on inducible nitric oxide synthase and cyclooxygenase-2 expression in sulfur mustard-induced skin. Nyska A; Lomnitski L; Maronpot R; Moomaw C; Brodsky B; Sintov A; Wormser U Laboratory of Experimental Pathology, National Institutes of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA. nyska@niehs.nih.gov Archives of toxicology (2001 Feb), 74(12), 768-74. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11305779 AN 2001394179 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

In a previous study we demonstrated the protective effect of topical iodine as postexposure treatment for sulfur mustard (SM) application. The iodine treatment results in significantly reduced inflammation and necrosis and increased epidermal hyperplasia. The expression and localization of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in paraffin-embedded skin samples from that study were evaluated in the present investigation. We compared the immunoreactivity of iNOS and COX-2 using five samples from each of the following four test sites: untreated control sites, SM-exposed sites, sites treated with iodine mixture 15 min after SM exposure, and sites treated with iodine 30 min after SM exposure. All animals were killed 2 days after irritant exposure. iNOS immunoreactivity was present only in skin sites exposed to SM without iodine treatment. The ulcerated skin was covered with a relatively thick band of exudate composed of iNOS-immunostained polymorphonuclear cells and macrophages. In untreated skin, COX-2 immunostaining was limited to the thin suprabasal epidermal layer. In SM-exposed skin, induction of COX-2 was noted in inflammatory cells located close to the site of epidermal injury. In skin sites treated with iodine 15 or 30 min after SM exposure, the regenerating hyperplastic epithelium showed moderate cytoplasmic staining localized to the epithelium overlying the basal layer. This pattern of staining was also present in the nearby dermal fibroblasts. Thus, in contrast to the skin samples exposed to SM without iodine treatment, the epidermal layer expressing immunohistochemical positivity for COX-2 was thicker and corresponded to the epidermal hyperplasia noted in samples treated with iodine. It is well documented that prostaglandins (PGs) promote epidermal proliferation, thereby contributing to the repair of injured skin. That the induction of the COX-2 shown in our study may also play a role in the healing process is indicated by the present evidence.
The results suggest that nitric oxide radicals (NO*) are involved in mediating the damage induced by the SM and that iodine-related reduction in acute epidermal inflammation is associated with reduced iNOS expression.

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Intervention of sulfur mustard toxicity by downregulation of cell proliferation and metabolic rates. Ray R; Benton B J; Anderson D R; Byers S L; Petrali J P US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. radharaman.ray@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S87-91. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428650 AN 2001371709 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chemical warfare compound HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37 degrees C) first in keratinocyte growth medium (KGM) containing BAPTA AM (10-40 microM) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concentration-dependent manner with some cellular degeneration above 30 microM (light microscopy). At 20-30 microM, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 54 +/- 5%), [3H]-uridine (RNA synthesis, 29 +/- 6%) and [14C]-valine (protein synthesis, 12 +/- 2%) as well as a lower protein content per culture (30 +/- 3%) compared with corresponding untreated controls. However, 20-30 microM BAPTA AM did not cause any demonstrable cytopathology based on morphological (electron microscopy) as well as biochemical (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser J; Meier H L Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S23-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428638 AN 2001371697 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chemical warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compounds in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell preparations were exposed to various concentrations of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these experiments suggest that, with increasing HD concentration and time, NHEK will fragment irrespective of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains constant over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concentration- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, respectively, is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concentrations that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price E O; Smith J R; Clark C R; Schlager J J; Shih M L Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S193-7. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428636 AN 2001371695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The continual threat of chemical and biological warfare has prompted the need for unambiguous analytical methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with hemoglobin and metallothioneine were conducted. In vitro experiments with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to determine the extent of alkylation and occurrence of HD cross-linking using the MALDI-ToF/MS technique. In a typical experiment, 50 ml of 5 mM HD in acetonitrile was added to an equal volume of 0.5 mM hemoglobin in deionized water followed by vortexing and incubation at room temperature. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES experiments. These results demonstrate that MALDI-ToF/MS is a useful analytical technique to investigate the interaction of HD with biomolecules and may be employed potentially as a diagnostic tool for the confirmation of exposure to chemical warfare agents.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers S; Anderson D; Brobst D; Cowan F Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S19-22. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428635 AN 2001371694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham J S; Reid F M; Smith J R; Stotts R R; Tucker E S; Shumaker S M; Niemuth N A; Janny S J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S161-72. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428630 AN 2001371689 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chemical warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clinical pathology findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liquid on the ventral surface for 2 h, generating six 3-cm diameter full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematology and serum chemistry examinations. Urine was collected in metabolism cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatography/mass spectrometry. Examination of clinical pathology parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clinically significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 microg ml(-1) with a mean of 2.14 microg ml(-1). Thiodiglycol concentrations were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml(-1). Mean levels remained 10-40 ng ml(-1) for the remainder of the 7-day observation period, with the highest individual concentration noted during this period of 132 ng ml(-1). Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other laboratory animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 week.
Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h. Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin M C; Ricketts K; Skvorak J P; Gazaway M; Mitcheltree L W; Casillas R P Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA. Michael.Babin@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S141-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428627 AN 2001371686 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quantitative edema response as well as histopathological and biochemical endpoints as measurements of inflammation and tissue damage following exposure to the chemical warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal separation. This study evaluated the protective effects of three of these pharmacological compounds when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver a subcutaneous dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 microl of a 195 mM (0.16 mg) solution of sulfur mustard (density = 1.27 g ml(-1); MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathological damage (necrosis, epidermal-dermal separation). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant reduction in edema (24%, 26% and 22%, respectively) from the positive control. Compared to HD-positive controls, hydrocortisone, indomethacin and olvanil caused a significant reduction in subepidermal blisters (71%, 52% and 57%, respectively) whereas only hydrocortisone produced a significant reduction in contralateral epidermal necrosis (41%). We show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins K B; Lodhi I J; Hurley L L; Hinshaw D B University of Michigan Medical School, Ann Arbor 48105, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S125-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428622 AN 2001371681 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chemical warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells (Toxicol. Appl. Pharmacol. 1996; 141: 568-583). Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFkappaB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFkappaB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 microM HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 microM buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 microM HD for 5-6 h. Externally applied GSH up to a concentration of 5 mM had no toxic effect on the cells. Mild toxicity was associated with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examined the hypothesis that HD may activate the nuclear transcription factor NFkappaB by performing EMSAs with nuclear extracts of endothelial cells following exposure to 0, 250 or 500 microM HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFkappaB binding to its consensus sequence induced by 500 microM HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFkappaB, although HD-induced activation of NFkappaB was partially suppressed by NAC at 5 h. Factor NFkappaB is an important transcription factor for a number of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFkappaB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFkappaB activity. The NFkappaB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction associated with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha M; Bowers W Jr; Kohl J; DuBose D; Walker J; Alkhyyat A; Wong G US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S101-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428619 AN 2001371678 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chemical warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl ethyl sulfide (CEES, 1-2 mg l(-1) min(-1)) in humidified air or to humidified air alone. Tissues were evaluated histologically, ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histology showed that CEES induced the separation of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histology and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1alpha (IL-1alpha), prostaglandin-E2 (PGE2) and especially IL-1 receptor antagonist (IL-1Ra) release (56,334 vs 84,614 pg ml(-1)), but decreased interleukin-6 (IL-6, 4,755 vs 351 pg ml(-1)). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracelluar IL-1alpha (371 vs 92 pg ml(-1)). Extracellular IL-1Ra greatly increased (2,375 vs 24,875 pg ml(-1)), whereas cellular levels decreased (16,5425 vs 96,625 pg ml(-1)). Extracellular (224 vs 68 pg ml(-1)) and intracellular (485 vs 233 pg ml(-1)) soluble interleukin-1 receptor H (sIL-1RII) decreased. Prostanglandin E2 increased (1,835 vs 2,582 pg ml(-1)), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57,000 vs 96,000 pg ml(-1)). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Correlation of a specific mitochondrial phospholipid-phosgene adduct with chloroform acute toxicity. Di Consiglio E; De Angelis G; Testai E; Vittozzi L Biochemical Toxicology Unit, Department of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita, Viale Regina Elena 299, I-00161, Rome, Italy Toxicology (2001 Feb 21), 159(1-2), 43-53. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11250054 AN 2001195862 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The dose and time dependence of formation of a specific adduct between mitochondrial phospholipid and phosgene have been determined in the liver of Sprague-Dawley (SD) rats as well as in the liver and kidney of B6C3F1 mice after dosing with chloroform. Rats were induced with phenobarbital or non-induced. Determination of tissue glutathione (GSH) and of serum markers of hepatotoxicity and nephrotoxicity was also carried out. With dose-dependence experiments, a strong correlation between the formation of the specific phospholipid adduct, GSH depletion and organ toxicity could be evidenced in all the organs studied. With non-induced SD rats, no such effects could be induced up to a dose of 740 mg/kg. Time-course studies with B6C3F1 mice indicated that the specific adduct formation took place at very early times after chloroform dosing and was concurrent with GSH depletion. The adduct formed during even transient GSH depletion (residual level: 30% of control) and persisted after restoration of GSH levels. Following a chloroform dose at the hepatotoxicity threshold (150 mg/kg), the elimination of the adduct in the liver occurred within 24 h and correlated with the recovery of ALT, which was slightly increased (12 times) after treatment. Following a moderately nephrotoxic dose (60 mg/kg), the renal adduct persisted longer than 48 h, when a 100% increase in blood urea nitrogen and a 40% increase in serum creatinine indicated the onset of organ damage. The formation of the adduct in the liver mitochondria of B6C3F1 mice was associated with the decrease of phosphatidyl-ethanolamine (PE), in line with previous results in rat liver indicating that the adduct results from the reaction of phosgene with PE. The adduct levels implicated the reaction of phosgene with about 50% PE molecules in the liver mitochondrial membrane of phenobarbital-induced SD rats and of about 10% PE molecules of the inner mitochondrial membrane of the liver of B6C3F1 mice.
The association of this adduct with the toxic effects of chloroform makes it a very good candidate as the primary critical alteration in the sequence of events leading to cell death caused by chloroform.

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The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats. Kassa J; Fusek J Purkyne Military Medical Academy, PO Box 35/T, 500 01, Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2000 Nov 23), 154(1-3), 67-73. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11118671 AN 2001083637 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.

[megalomania]

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Development of multifunctional perfluorinated polymer blends as an active barrier cream against chemical warfare agents. Hobson, Stephen T.; Braue, Ernest H., Jr. Drug Assessment Div., U.S. Army Medical Research Institute for Chemical Defense, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 80-81. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:363990 AN 2003:381106 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare agents (CWA's) represent a real and growing threat both to U.S. armed forces as well as to civilians. Within the last three decades, chem. weapons have been used by the Soviets in Cambodia (yellow rain, tricothecene mycotoxins), by Iraq against Iran (HD and tabun), and by Iraq against its own dissident Kurdish population at Halabja (H-ID HCN0). In the United States' experience in World War I, almost one-third of hospitalized casualties were a result of CWA's. Furthermore, the 1000 casualties and 12 deaths resulting from the 1995 terrorist use of sarin (GB) in Tokyo show that civilians have also become targets. In this paper we focus on protection against two classes of CWA's: nerve agents (soman, GD) and blister agents (sulfur mustard, HD). Protection against these agents in the United States Army consists of a chem. resistant outer layer of clothing (BDO) and protective mask (M40). This scheme of protection allows operation in a chem. contaminated area but results in decreased performance and increased heat retention. We have investigated a material that serves as a phys. barrier to CWA's and contains an active moiety to neutralize hazardous chems. This Active Topical Skin Protectant (aTSP) would be used in conjunction with other protective procedures. Herein we report the prepn., characterization, and evaluation of aTSP's.

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Molecularly imprinted polymers for the detection of chemical agents in water. Jenkins, Amanda L.; Yin, Ray; Jensen, Janet L.; Durst, H. Dupont. US Army Research Laboratory, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 76-77. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:343335 AN 2003:381101 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molecularly imprinted polymers contg. Eu3+ were prepd. using a no. of pesticides and pinacolyl methylphosphonate (hydrolysis product of the nerve agent Soman), and sensors were fabricated by coating the polymers on optical fibers. The sensors were characterized in terms of sensitivity, selectivity, response time, adaptability, and portability; they provided detection limits in the low parts per trillion.

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Synthesis of carbon-coated MgO nanoparticles. Bedilo, Alexander F.; Sigel, M. Jake; Koper, Olga B.; Melgunov, Maxim S.; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2002), 12(12), 3599-3604. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 138:174329 AN 2002:910661 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Carbon-coated MgO nanoparticles, with carbon forming a porous coating on the surface of MgO nanoparticles, have been prepd. by two different techniques. Resorcinol has been found to be an efficient agent for the modification of magnesium methoxide leading to carbon-coated MgO nanocrystals of small crystallite size and high surface area. Decompn. of dry magnesium methoxide under an inert gas flow proved to be another efficient and economical way to synthesize carbon-coated MgO. The carbon coating acts as a hydrophobic barrier partially protecting the core metal oxide from water adsorption and conversion to magnesium hydroxide. However, destructive adsorption reactions can still proceed on the metal oxide surface, as evidenced by the dehydrochlorination of 2-chloroethyl Et sulfide (2-CEES) and 1-chlorobutane. The overall stability of the material in the presence of water vapor is significantly improved in comparison with non-coated nanocryst. MgO.

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Micellar Effects on Hypochlorite Catalyzed Decontamination of Toxic Phosphorus Esters. Dubey, D. K.; Gupta, A. K.; Sharma, Mamta; Prabha, S.; Vaidyanathaswamy, R. Defence R and D Establishment, Gwalior, India. Langmuir (2002), 18(26), 10489-10492. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 138:94789 AN 2002:866089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At pH 8.5, the surfactant N,N,N-trimethyl-1-hexadecanaminium bromide (I) increased the pseudo-first-order rate consts. of hypochlorite-catalyzed hydrolysis of the sarin model compd. p-nitrophenyl di-Ph phosphate by 300 times and that of the toxic p-nitrophenyl iso-Pr methylphosphonate by 20 times, and the nerve agent sarin itself was completely decontaminated within 10 min at a sarin-hypochlorite ratio of 20:1 in a micellar I-hypochlorite mixt. In the absence of surfactant , it takes >70 min to detoxify sarin, even at a 10 times higher concn. of hypochlorite.

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A Comparative Study of the Adsorption of Chloro- and Non-Chloro-Containing Organophosphorus Compounds on WO3. Kanan, Sofian M.; Lu, Zhixiang; Tripp, Carl P. Laboratory for Surface Science Technology and Department of Chemistry, University of Maine, Orono, ME, USA. Journal of Physical Chemistry B (2002), 106(37), 9576-9580. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 137:253624 AN 2002:620746 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The adsorption of di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), and methyldichlorophosphate (MDCP) on monoclinic tungsten oxide (m-WO3) evacuated at various temps. was investigated using IR spectroscopy. DMMP is the most common mol. used for evaluating the performance of WO3 and other semiconducting metal oxide (SMO)-based sensors to phosphonate-based nerve agents. However, toxic nerve agents such as sarin differ from DMMP in that they contain a functional group (P-F in sarin) that can be readily hydrolyzed. It is shown that the adsorption of organophosphates that contain P-Cl groups differs from nonhalogenated simulants such as DMMP and TMP on WO3 surfaces. Specifically, the non-chlorinated simulants DMMP and TMP adsorb on the surface solely through the P:O functionality with the surface water layer as well as the Lewis and Bronsted acid sites. The relative no. of mols. bound on Lewis and Bronsted acid surface sites depends on the initial evacuation temp. of the WO3 surface. When MDCP adsorbs on WO3 through the P:O bond, it is accompanied by the hydrolysis of P-Cl groups by water vapor or the adsorbed water layer leading to addnl. phosphate-like species on the surface. The IR data suggests that a halogenated phosphate like MDCP is a better simulant mol. for studies aimed at understanding the role of water and hydrolysis in the response of metal oxide-based sensors to nerve agents.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock, Shannon D.; Till, Gerd O.; Smith, Milton G.; Ward, Peter A. Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2002), 22(4), 257-262. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 137:151235 AN 2002:596130 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. warfare agent analog, 2-chloroethyl Et sulfide, known as half-mustard gas (HMG), is less toxic and less of an environmental hazard than the full mol. and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of 125I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, the authors obsd. significant attenuation of the pulmonary injury when exptl. animals were complement- or neutrophil-depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, DMSO, dimethylthiourea, Resveratrol, and N-acetyl-L-cysteine (NAC). The last compd. showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement-mediated pathways and the generation by neutrophils of toxic oxygen species. The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber, Ellen; McGuire, Raymond. Lawrence Livermore National Laboratory, Environment Protection Department, University of California, Livermore, CA, USA. Journal of Hazardous Materials (2002), 93(3), 339-352. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 137:374412 AN 2002:558690 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A decontamination method was developed using a single reagent that is effective both against chem. warfare (CW) and biol. warfare (BW) agents. The new reagent, L-Gel, consists of an aq. soln. of a mild com. oxidizer, Oxone, together with a com. fumed silica gelling agent, Cab-O-Sil EH 5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. This reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Expts. to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Lab. and independently at 4 other locations. L-Gel was tested against all classes of chem. warfare agents and against various biol. warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biol. agents. Testing showed that L-Gel is as effective against chem. agents and biol. materials, including spores, as the best military decontaminants.

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Synthesis, Characterization, and Adsorption Studies of Nanocrystalline Aluminum Oxide and a Bimetallic Nanocrystalline Aluminum Oxide/Magnesium Oxide. Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J.; Bonevich, John. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry of Materials (2002), 14(7), 2922-2929. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 137:128541 AN 2002:469813 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of Al2O3 and Al2O3/MgO have been produced by a modified aerogel synthesis involving the corresponding aluminum tri-tert-butoxide, magnesium methoxide, toluene, methanol, ethanol, and water. The resulting oxides are in the form of powders having crystallites of .ltorsim.2 nm. These crystallites have been studied by TEM and BET methods, and were found to possess high surface areas and pore vols. (800 m2/g for Al2O3 and 790 m2/g for Al2O3/MgO, compared to 450 m2/g for MgO). As seen with other metal oxides, once they are produced as nanoparticles, their reactivity is greatly enhanced on a per unit surface area basis. This is thought to be due to morphol. differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites possess much higher surface concn. of such sites per unit surface area. Elemental anal., X-ray diffraction, and IR spectroscopy have been used to characterize these nanoparticles, and reactions with CCl4, SO2, and Paraoxon have demonstrated significantly enhanced reactivity and/or capacity compared with common com. forms of the oxide powders. A significant feature is that, by a cogellation synthesis, Al2O3 and MgO have been intermingled, which engenders enhanced reactivity/capacity over the pure forms of nanoscale Al2O3 or MgO toward a chem. warfare surrogate (Paraoxon) and an acid gas (SO2). This serves as an example where tailored synthesis of a nanostructured formulation can yield special benefits.

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Nanocrystalline metal oxides as destructive adsorbents for organophosphorus compounds at ambient temperatures. Rajagopalan, Shyamala; Koper, Olga; Decker, Shawn; Klabunde, Kenneth J. Nanoscale Materials, Inc., Manhattan, KS, USA. Chemistry--A European Journal (2002), 8(11), 2602-2607. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 137:191092 AN 2002:451335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of magnesium oxide react with organophosphorus compds. at room temp. by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant mol. fragments. These ultrafine powders have unusual cryst. shapes and possess high surface concns. of reactive edge/corner and defect sites, and thereby display higher surface reactivity, normalized for surface area, than typical polycryst. material. This high surface reactivity coupled with high surface area allows their use for effective decontamination of chem. warfare agents and related toxic substances. Herein data is presented for paraoxon, diisopropylfluorophosphate (DFP), and (CH3CH2O)2P(O)CH2SC6H5 (DEPTMP). Solid-state NMR and IR spectroscopy indicate that all OR and F groups dissoc.; this leaves bound -PO4%
2C -F, and -OR groups for paraoxon, DFP, and DEPTMP, resp. For paraoxon, it was shown that one monolayer reacts. For DEPTMP, the OR groups dissoc., but not the P-CH2SC6H5 group. The nanocryst. MgO reacts much faster and in higher capacity than typical activated carbon samples, which physisorb but do not destructively adsorb these phosphorous compds.

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Routes of photocatalytic destruction of chemical warfare agent simulants. Vorontsov, Alexandre V.; Davydov, Lev; Reddy, Ettireddy P.; Lion, Claude; Savinov, Eugenii N.; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russia. New Journal of Chemistry (2002), 26(6), 732-744. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 137:236738 AN 2002:427511 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Selected imitants of chem. warfare agents such as di-Me methylphosphonate (DMMP), di-Et phosphoramidate (DEPA), pinacolyl methylphosphonate (PMP), and butylaminoethanethiol (BAET) were subjected to photocatalytic and sonophotocatalytic treatment in aq. suspensions of TiO2. Complete conversion of the same mass of imitants to inorg. products was obtained within 600 min for DMMP, DEPA, PMP, but required a longer time for BAET. Sonolysis accelerated photodegrdn. of DMMP. No degrdn. was obsd. without UV illumination. Final products of degrdn. were PO43-, CO2 for DMMP and PMP, PO43-, NO3- (25%), NH4+ (75%), CO2 for DEPA, and SO42-, NH4+, CO2 for BAET. The no. of main detected intermediate products increases in the order DMMP (7), DEPA (9), PMP (21), and exceeds 34 for BAET. Degrdn. of DMMP mainly proceeds through consecutive oxidn. of methoxy groups and then the Me group. Di-Me hydroxymethylphosphonate and dimethylphosphate testify to the parallel oxidn. of the Me group. Destruction of DEPA mainly starts with cleavage of the P-NH2 bond to form di-Et phosphate, which transforms further into Et phosphate. Oxidn. of  and  carbons of ethoxy groups to form ethylphosphonoamidate, hydroxyethyl ethylphosphonoamidate and other products also contributes to the destruction. Photocatalytic degrdn. of PMP mainly starts with oxidn. of the pinacolyl fragment, methylphosphonic acid and acetone being the major products. Oxidn. of BAET begins with dark dimerization to disulfide, which undergoes oxidn. of sulfur forming sulfinic and sulfonic acids as well as oxidn. of carbons to form butanal, aminobutane, etc., and cyclic products such as 2-propylthiazole. A scheme of degrdn. was proposed for DMMP and DEPA, and starting routes for PMP and BAET. Quantum efficiencies of complete mineralization calcd. as reaction rate to photon flux ratio approx. 10-3%.

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Solvent Effects on the Heterogeneous Adsorption and Reactions of (2-Chloroethyl) ethyl Sulfide on Nanocrystalline Magnesium Oxide. Narske, Richard M.; Klabunde, Kenneth J.; Fultz, Shawn. Department of Chemistry, Augustana College, Rock Island, IL, USA. Langmuir (2002), 18(12), 4819-4825. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:62952 AN 2002:360518 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The noncatalytic destructive adsorption of (2-chloroethyl) Et sulfide (2-CEES), a mimic of bis(2-chloroethyl) sulfide (HD or Mustard Gas), on nanocryst. Mg oxide (AP-MgO) was studied in several solvents from pentane to methanol. The decompn. products formed in these reactions were vinyl Et sulfide and (2-hydroxyethyl) Et sulfide. Reactions in pentane allowed the highest reaction rates, while THF and methanol gave results quite different from those for the hydrocarbon solvent. Reactions in methanol yielded (methoxyethyl) Et sulfide and not the vinyl Et sulfide and (2-hydroxyethyl) Et sulfide compds. These studies showed that the MgO-2-CEES reaction chem. is significantly affected by the solvent present and can be enhanced by choice of solvent and the addn. of small amts. of water. Interestingly, the least polar, least reactive solvent (pentane) allowed the most rapid 2-CEES reactions, indicating that the solvent simply aided material transfer to the reactive surface sites without blocking these sites. Rate changes upon water addn., coupled with FTIR studies, indicate that isolated surface OH groups are important reactive sites. These results indicate that the use of certain inert solvents greatly aids material transfer, and thereby the reaction rates of the sorbent with the toxin are significantly enhanced.

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Adsorption and Reaction of Diethyl Sulfide on Active Carbons with and without Impregnants under Static Conditions. Prasad, G. K.; Singh, Beer; Saradhi, U. V. R.; Suryanarayana, M. V. S.; Pandey, D. Defence Research and Development Establishment, Gwalior, India. Langmuir (2002), 18(11), 4300-4306. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:52819 AN 2002:306380 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Active carbons of different grades with and without impregnants were studied for the adsorption of di-Et sulfide (DES), the simulant of S mustard, under static conditions at 36  1. Kinetics of the adsorption were studied using linear driving force (LDF) and the Fickian diffusion model. The kinetic parameters such as equilibration time, equilibration capacity, equilibration const., diffusional exponent, and adsorbate-adsorbent interaction const. (K) were detd. The diffusional exponent (n), being <0.5, indicated a Fickian mode of diffusion of DES in the studied C. Chem. interaction also seemed to be the 2nd mechanism (although minor) involved in the DES uptake rate (the 1st being simple Fickian diffusion). The adsorbate-adsorbent interaction const. did not vary significantly indicating that probably DES chem. interacts to a small extent with the metal salts present on the surface of active C as impregnants. However, the characterization of reaction products, after extn. in CH2Cl2, using GC/MS indicated that the system CrO3/NaOH/C (C impregnated with Cr(VI) plus NaOH) only reacted with DES to give di-Et sulfone.

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An improved brain slice model of nerve agent-induced seizure activity. Wood, Sebastien J.; Tattersall, John E. H. Biomedical Sciences Department, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(Suppl. 1), S83-S86. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:290254 AN 2002:246280 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice prepn. Soman (1 M) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice prepn. is a suitable model for investigating the origin and propagation of nerve agent-induced seizures within the limbic system.

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The NMDA receptor ion channel: a site for binding of huperzine A. Gordon, Richard K.; Nigam, Savita V.; Weitz, Julie A.; Dave, Jitendra R.; Doctor, Bhupendra P.; Ved, Haresh S. Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S47-S51. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:397222 AN 2002:246274 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Huperzine A (HUP-A), first isolated from the Chinese club moss Huperzia serrata, is a potent, reversible and selective inhibitor of acetylcholinesterase (AChE) over butyrylcholinesterase (BChE) (Life Sci. 54: 991-997). Because HUP-A has been shown to penetrate the blood-brain barrier, is more stable than the carbamates used as pretreatments for organophosphate poisoning (OP) and the HUP-A:AChE complex has a longer half-life than other prophylactic sequestering agents, HUP-A has been proposed as a pretreatment drug for nerve agent toxicity by protecting AChE from irreversible OP-induced phosphonylation. More recently (NeuroReport 8: 963-968), pretreatment of embryonic neuronal cultures with HUP-A reduced glutamate-induced cell death and also decreased glutamate-induced calcium mobilization. These results suggest that HUP-A might interfere with and be beneficial for excitatory amino acid overstimulation, such as seen in ischemia, where persistent elevation of internal calcium levels by activation of the N-methyl-D-aspartate (NMDA) glutamate subtype receptor is found. The authors have now investigated the interaction of HUP-A with glutamate receptors. Freshly frozen cortex or synaptic plasma membranes were used, providing 60-90% specific radioligand binding. Huperzine A (100 M) had no effect on the binding of [3H]glutamate (low- and high-affinity glutamate sites), [3H]MDL 105,519 (NMDA glycine regulatory site), [3H]ifenprodil (NMDA polyamine site) or [3H]CGS 19755 (NMDA antagonist). In contrast with these results, HUP-A non-competitively (Hill slope < 1) inhibited [3H]MK-801 and [3H]TCP binding (co-located NMDA ion channel PCP site) with pseudo Ki .apprx. 6 M. Furthermore, when neuronal cultures were pretreated with HUP-A for 45 min prior to NMDA exposure, HUP-A dose-dependently inhibited the NMDA-induced toxicity.
Although HUP-A has been implicated to interact with cholinergic receptors, it was without effect at 100 M on muscarinic (measured by inhibition of [3H]QNB or [3H]NMS binding) or nicotinic [3H]epibatidine binding) receptors; also, HUP-A did not perturb adenosine receptor binding [3H]PIA or [3H]NECA). Therefore, HUP-A most likely attenuates excitatory amino acid toxicity by blocking the NMDA ion channel and subsequent Ca2+ mobilization at or near the PCP and MK-801 ligand sites. Thus, on the one hand, HUP-A could be used as a pretreatment against OPs and it might also be a valuable therapeutic intervention in a variety of acute and chronic disorders by protecting against overstimulation of the excitatory amino acid pathway. By blocking NMDA ion channels without psychotomimetic side-effects, HUP-A may protect against diverse neurodegenerative states obsd. during ischemia or Alzheimer's disease.

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Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense. Smith, J. Richard; Shih, Ming L.; Price, Elvis O.; Platoff, Gennady E.; Schlager, John J. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S35-S41. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365032 AN 2002:246272 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An army medical field lab. presently has the capability of performing std. protocols developed at the US Army Medical Research Institute of Chem. Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chem. warfare agents using gas chromatog./mass spectrometry. Addnl., chem. warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biol. half-lives and can be used as diagnostic biomarkers of chem. agent exposure. An anal. technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examd. for its potential to analyze these biomarkers. The technique is capable of detecting large biomols. and modifications made to them. Its fast anal. time makes MALDI-TOF/MS technol. suitable for screening casualties from chem. or biol. attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

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Analysis of the degradation compounds of chemical warfare agents using liquid chromatography/mass spectrometry. Smith, J. Richard; Shih, Ming L. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S27-S34. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365031 AN 2002:246271 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of the degrdn. products of chem. warfare (CW) agents has been a challenge to analysts. The low volatility of these compds. makes them unsuitable for direct gas chromatog. anal. without prior derivatization. Lack of a chromophore causes difficulties with classic detection methods after liq. chromatog. sepn. With the recent development of various interfaces that allow for the introduction of a liq. solvent stream into the mass spectrometer, the task of directly analyzing these compds. has become easier. For this report, the authors examd. three different liq. chromatog./mass spectrometry (LC/MS) interfaces for their suitability for the anal. of CW degrdn. compds. The interface types examd. were particle beam electron impact ionization (PBI), electrospray ionization (ESI) and atm. pressure chem. ionization (APCI). Several alkylphosphonates and thiodiglycol analogs that are produced from the degrdn. of organophosphorus nerve agents and sulfur mustard, resp., were analyzed using each of the three techniques. Electron impact ionization following gas chromatog. or particle beam introduction typically generates very reproducible, library-searchable mass spectra. Most of the CW breakdown compds. examd. using the PBI interface did not produce a mol. ion. Despite the lack of a mol. ion, the mass spectra of the various compds. contained enough different structural information from fragment ions for the pos. identification of each. The mass spectra generated using ESI are generally limited to protonated mol. ions with little or no fragmentation. For pos. identification and confirmation, tandem mass spectrometry techniques quite often must be used. Many of the compds. in this study were characterized by prominent sodiated adducts along with the protonated mol. ion. Methylphosphonic acid produced protonated dimers, trimers, etc. Although the various adduct ions can be used for addnl. confirmation of the mol. wt. of a compd., the adducts also can result in suppression of ionization of the compd.
and thus reduce sensitivity. Another "soft" ionization technique that results in abundant protonated mol. ions is APCI. The mass spectra of the breakdown compds. produced using APCI were characterized generally by either a prominent protonated mol. ion or a dehydrated form of it. In addn., a no. of structurally significant fragment ions were obsd. and their relative abundances could be adjusted by altering the APCI conditions. The data presented here indicate that each of the three techniques can be used successfully for direct liq. introduction and anal. of the non-volatile compds. produced from the degrdn. of CW agents. The mass spectra produced using each technique are quite different and could be utilized as addnl. confirmation of compd. identity.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller, Jennifer K.; Lenz, David E. Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S23-S26. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:336395 AN 2002:246270 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-mol.-wt. compds. is effected by the use of chromatog. techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the anal. To overcome those drawbacks, the authors were involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compds. such as pinacolylmethyl phosphonofluoridate (soman), which is a chem. warfare agent. Prior ests. suggested that it is necessary to be able to detect soman at a concn. below 2.5  10-7 M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The min. required assay time was 2.0-2.5 h with no loss in sensitivity. To det. the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogs were 5  10-7 M for 4-nitrophenylpinacolylmethylphosphonate, 8  10-7 M for dipinacolylmethylphosphonate, 2  10-6 M for diisopropylmethylphosphonate, 3  10-5 M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5  10-5 M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman mol., were effective inhibitors. Compds., which contained predominately arom. groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to det. its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman.

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The active site of human paraoxonase (PON1). Josse, Denis; Lockridge, Oksana; Xie, Weihua; Bartels, Cynthia F.; Schopfer, Lawrence M.; Masson, Patrick. Eppley Institute, University of Nebraska Medical Center, Omaha, NE, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S7-S11. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365079 AN 2002:246267 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ideally the authors would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman. However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4  106 M-1 min-1, and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, the authors have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw, M. D.; Hayes, T. L.; Miller, T. L.; Shannon, C. M. Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S3-S6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365078 AN 2002:246266 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) iso-Bu methylphosphonothiolate-a V-type nerve agent developed by the former Soviet Union-in the environment is an important parameter in threat assessment anal. and for the detn. of use, prodn., testing and storage of this chem. warfare agent. S-(N,N-Diethylaminoethyl) iso-Bu methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same mol. formula, it is expected that their phys. and chem. properties would be different. This preliminary investigation was undertaken to det. the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compd. at approx. 1 mg ml-1 in unbuffered water at pH 7 was detd. side-by-side. The half-lives for VXA and VX were detd. to be 12.4 days and 4.78 days, resp. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chem. Weapons Convention.

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Synthesis of high surface area monoclinic WO3 particles using organic ligands and emulsion based methods. Lu, Zhixiang; Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST), University of Maine, Orono, ME, USA. Journal of Materials Chemistry (2002), 12(4), 983-989. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 136:389533 AN 2002:226497 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several synthetic approaches have been used to obtain nano-sized monoclinic WO3 (m-WO3) powders. All of these methods begin with a std. preparative method where H2WO4 is first generated by passing a Na2WO4 soln. through a cation-exchange resin. It is shown that high surface area particles are produced by dripping the H2WO4 exiting from the ion-exchange column into a soln. contg. oxalate and acetate exchange ligands or alternatively, into a water-in-oil (w/o) based emulsion. In comparison to com. WO3 powders, the surface area of the m-WO3 powders were higher by factors of 10 and 20 times when prepd. in the presence of acetate/oxalate chelating agents and w/o emulsions, resp. The much higher surface areas enable IR spectroscopic identification of surface sites along with detection and monitoring of gaseous reactions and adsorbed species on the surface of this metal oxide. This is demonstrated with the adsorption of a nerve agent simulant, di-Me Me phosphonate. In general, little is known about the reactions of gaseous mols. on m-WO3 surfaces and the fabrication of high surface area m-WO3 particles will aid in gaining an understanding of the chem. processes occurring in WO3 based sensors.

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Prefiltering Strategies for Metal Oxide Based Sensors: The Use of Chemical Displacers to Selectively Dislodge Adsorbed Organophosphonates from Silica Surfaces. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2002), 18(3), 722-728. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 136:173252 AN 2002:22837 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

IR spectroscopy is used to monitor the competitive adsorption/desorption behavior of the nerve gas simulants, di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on SiO2. All 4 compds. molecularly adsorb via hydrogen bonds (H-bonds) with the surface hydroxyl groups. The adsorption strength depends on 2 factors: the specific functional group H-bonded to the surface hydroxyl groups and the no. of such bonds per mol. The phosphonates are molecularly displaced from the SiO2 surface by chem. displacers. By judiciously selecting chem. displacers as dictated by the 2 factors, (i.e., type and no. of functional groups H-bonded to the surface silanols) it is possible to selectively and sequentially dislodge each of the 4 phosphonate compds. adsorbed on SiO2. Specifically, the relative adsorption strength of the phosphonate compds. and the chem. displacers (labeled A-C) follows the order: TCP < MDCP < A < DMMP < B < TMP < C, where A = NEt3 (TEA), B = 2-pyridyl MeCN (2-PyAN), and C= ethylenediamine (EDA). AM1 semiempirical calcns. show that the toxic nerve agent, sarin, would position itself between MDCP and DMMP in the above order. The implications of using chem. displacers in filtering applications with metal oxide based sensors are discussed.

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New -phthalimidoperoxyalkanoic acids in decontamination. Destruction of some toxic organophosphorus and organosulfur pollutants. Lion, Claude; Da Conceicao, Louis; Delmas, Gerard; Magnaud, Gilbert. Institut de Topologie et de Dynamique des Systemes, Universite de Paris 7, Paris, Fr. New Journal of Chemistry (2001), 25(9), 1182-1184. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 136:90120 AN 2001:726141 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (chem. warfare agents and/or insecticides) is of increasing importance. We report the use of -phthalimidoperoxyalkanoic acids in the destruction of paraoxon (di-Et p-nitrophenyl phosphate), a well-known insecticide, and 2-chloro-2'-phenyldiethyl sulfide (a half mustard). We show that while all the peroxy acids used in this series allow the destruction of toxic compds., the length n of the alkanoic side chain is important to the choice of the optimal industrial compd., which is 6-phthalimidoperoxyhexanoic acid (n = 5).

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig ear skin. Chilcott, R. P.; Jenner, J.; Hotchkiss, S. A. M.; Rice, P. Department of Biomedical Sciences, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(4), 279-283. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:191481 AN 2001:616748 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chem. warfare agent sulfur mustard (SM). The in vitro absorption rates of SM through heat-sepd. human (15766 g cm-2 h-1) and pig-ear (411175 g cm-2 h-1) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 g cm-2 h-1, resp. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig ear epidermal membranes measured in vitro. Thus, although pig ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells contg. human epidermal membranes as a model for predicting in vivo human skin absorption.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen, J.; Riikonen, K.; Nikmo, J.; Jappinen, A.; Nieminen, K. Air Quality Research, Finnish Meteorological Institute, Helsinki, Finland. Journal of Hazardous Materials (2001), 85(3), 165-179. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 136:41716 AN 2001:572441 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Math. models were developed to evaluate the atm. dispersion of selected chem. warfare agents (CWA), including evapn. and settling of pollutant liq. droplets. The presented models and numerical results may be used to design protection and control measures against the conceivable use of CWA. The model, AERCLOUD (AERosol CLOUD), was extended to treat 2 nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodn. evolution of a 5-component aerosol mixt., consisting of 2-component droplets together with the surrounding 3-component gas. Numerical computations were performed using this model on the evapn. and settling of airborne sarin droplets in characteristic dispersion and atm. conditions. In particular, the max. radii (rM) of a totally evapg. droplet, in terms of the ambient temp. and pollutant vapor concn., were evaluated. The radii rM were .apprx.15-80 m for sarin droplets for selected ambient conditions and initial heights. Deposition fractions in terms of initial droplet size were also evaluated.

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Oxidation of triphenylarsine to triphenylarsine oxide by Trichoderma harzianum and other fungi. Hofmann, K.; Hammer, E.; Kohler, M.; Bruser, V. URST Umwelt- und Rohstoff-Technologie GmbH Greifswald, Greifswald, Germany. Chemosphere (2001), 44(4), 697-700. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 135:254254 AN 2001:483254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Arsenic resistant strains of bacteria and fungi were isolated from soil contaminated by chem. warfare agents. Until now, no metabolic products of microbial attack against the Ph residues of the model substrate triphenylarsine (TP) were found if it was incubated together with these strains in liq. culture assays. However, one of the isolated fungi, Trichoderma harzianum As 11, was found to oxidize TP to triphenylarsine oxide (TPO). The yeast Trichosporon mucoides SBUG 801 and the white-rot fungus Phanerochaete chrysosporium were also able to oxidize the As(III) in TP. In addn., P. chrysosporium transformed phenylarsine oxide (PAO) to phenylarsonic acid (PAA) under O2-atmosphere. By means of a respirometer system, the oxidn. of TP by T. harzianum As 11 was confirmed by a significantly higher consumption of oxygen in the presence of these compds. HPLC anal. of the oxidn. products TPO and PAA in the medium of the assays provided evidence for the transfer reaction of As(III) to As(V) in org. bonds. The oxidn. products TPO and PAA are more hydrophilic than TP and PAO. Therefore, it was concluded that particular fungi contribute to the mobilization of arsenic in soil contaminated by chem. warfare agents.

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Nanocrystalline metal oxides as unique chemical reagents/sorbents. Lucas, Erik; Decker, Shawn; Khaleel, Abbas; Seitz, Adam; Fultz, Shawn; Ponce, Aldo; Li, Weifeng; Carnes, Corrie; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry--A European Journal (2001), 7(12), 2505-2510. CODEN: CEUJED ISSN: 0947-6539. Journal; General Review written in English. CAN 135:216336 AN 2001:471452 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 29 refs. A new family of porous inorg. solids based on nanocryst. metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar orgs., and even chem./biol. warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chem. properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price, Elvis O.; Smith, J. Richard; Clark, Connie R.; Schlager, John J.; Shih, Ming L. Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S193-S197. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:206570 AN 2001:455416 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The continual threat of chem. and biol. warfare has prompted the need for unambiguous anal. methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with Hb and metallothioneins were conducted. In vitro expts. with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to det. the extent of alkylation and occurrence of HD crosslinking using the MALDI-ToF/MS technique. In a typical expt., 50 mL of 5 mM HD in acetonitrile was added to an equal vol. of 0.5 mM Hb in deionized water followed by vortexing and incubation at room temp. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES expts. These results demonstrate that MALDI-ToF/MS is a useful anal. technique to investigate the interaction of HD with biomols. and may be employed potentially as a diagnostic tool for the confirmation of exposure to chem. warfare agents.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham, John S.; Reid, Frances M.; Smith, J. Richard; Stotts, Richard R.; Tucker, F. Steven; Shumaker, Shawn M.; Niemuth, Nancy A.; Janny, Stephen J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S161-S172. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72547 AN 2001:455411 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chem. warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clin. pathol. findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liq. on the ventral surface for 2 h, generating six 3-cm diam. full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematol. and serum chem. examns. Urine was collected in metab. cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatog./mass spectrometry. Examn. of clin. pathol. parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clin. significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 g ml-1 with a mean of 2.14 g ml-1. Thiodiglycol concns. were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml-1. Mean levels remained 10-40 ng ml-1 for the remainder of the 7-day observation period, with the highest individual concn. noted during this period of 132 ng ml-1. Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other lab. animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 wk. Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h.
Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin, M. C.; Ricketts, K.; Skvorak, J. P.; Gazaway, M.; Mitcheltree, L. W.; Casillas, R. P. Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S141-S144. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72425 AN 2001:455408 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quant. edema response as well as histopathol. and biochem. endpoints as measurements of inflammation and tissue damage following exposure to the chem. warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal sepn. This study evaluated the protective effects of three of these pharmacol. compds. when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver an s.c. dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 l of a 195 mM (0.16 mg) soln. of sulfur mustard (d. = 1.27 g ml-1; MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathol. damage (necrosis, epidermal-dermal sepn.). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant redn. in edema (24%, 26% and 22%, resp.) from the pos. control. Compared to HD-pos. controls, hydrocortisone, indomethacin and olvanil caused a significant redn. in subepidermal blisters (71%, 52% and 57%, resp.) whereas only hydrocortisone produced a significant redn. in contralateral epidermal necrosis (41%). The authors show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins, Kevin B.; Lodhi, Irfan J.; Hurley, Lauren L.; Hinshaw, Daniel B. University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S125-S128. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72423 AN 2001:455404 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chem. warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells. Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 M HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 M buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 M HD for 5-6 h. Externally applied GSH up to a concn. of 5 mM had no toxic effect on the cells. Mild toxicity was assocd. with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examd. the hypothesis that HD may activate the nuclear transcription factor NFB by performing EMSAs with nuclear exts. of endothelial cells following exposure to 0, 250 or 500 M HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFB binding to its consensus sequence induced by 500 M HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFB, although HD-induced activation of NFB was partially suppressed by NAC at 5 h. Factor NFB is an important transcription factor for a no. of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFB activity. The NFB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction assocd. with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha, M.; Bowers, W., Jr.; Kohl, J.; DuBose, D.; Walker, J.; Alkhyyat, A.; Wong, G. US Army Research Institute of Environmental Medicine, Natick, MA, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S101-S108. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72420 AN 2001:455401 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl Et sulfide (CEES, 1-2 mg l-1 min-1) in humidified air or to humidified air alone. Tissues were evaluated histol., ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histol. showed that CEES induced the sepn. of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histol. and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1 (IL-1), prostaglandin-E2 (PGE2) and esp. IL-1 receptor antagonist (IL-1Ra) release (56334 vs. 84614 pg ml-1), but decreased interleukin-6 (IL-6, 4755 vs. 351 pg ml-1). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracellular IL-1 (371 vs. 92 pg ml-1). Extracellular IL-1Ra greatly increased (2375 vs. 24875 pg ml-1), whereas cellular levels decreased (165425 vs. 96625 pg ml-1). Extracellular (224 vs. 68 pg ml-1) and intracellular (485 vs. 233 pg ml-1) sol. interleukin-1 receptor II (sIL-1RII) decreased. Prostanglandin E2 increased (1835 vs. 2582 pg ml-1), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57000 vs. 96000 pg ml-1). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Intervention of sulfur mustard toxicity by down-regulation of cell proliferation and metabolic rates. Ray, R.; Benton, B. J.; Anderson, D. R.; Byers, S. L.; Petrali, J. P. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S87-S91. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72419 AN 2001:455399 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chem. warfare compd. HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37) first in keratinocyte growth medium (KGM) contg. BAPTA AM (10-40 M) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concn.-dependent manner with some cellular degeneration above 30 M (light microscopy). At 20-30 M, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 545%), [3H]-uridine (RNA synthesis, 296%) and [14C]-valine (protein synthesis, 122%) as well as a lower protein content per culture (303%) compared with corresponding untreated controls. However, 20-30 M BAPTA AM did not cause any demonstrable cytopathol. based on morphol. (electron microscopy) as well as biochem. (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Calmodulin, poly(ADP-ribose)polymerase and p53 are targets for modulating the effects of sulfur mustard. Rosenthal, Dean S.; Simbulan-Rosenthal, Cynthia M.; Iyer, Sudha; Smith, William J.; Ray, Radharaman; Smulson, Mark E. Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S43-S49. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72546 AN 2001:455392 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

We describe two pathways by which the vesicating agent sulfur mustard (HD) may cause basal cell death and detachment: induction of terminal differentiation and apoptosis. Following treatment of normal human epidermal keratinocytes (NHEK) with 10 or 100 M HD, the differentiation-specific keratin pair K1/K10 was induced and the cornified envelope precursor protein, involucrin, was crosslinked by epidermal transglutaminase. Fibronectin levels were reduced in a time- and dose-dependent manner. The rapid increase in p53 and decrease in Bcl-2 levels was consistent not only with epidermal differentiation but with apoptosis as well. Further examn. of biochem. markers of apoptosis following treatment of either NHEK or human papillomavirus (HPV)-immortalized keratinocytes revealed a burst of poly(ADP-ribose) synthesis, specific cleavage of poly(ADP-ribose)polymerase (PARP) in vivo and in vitro into characteristic 89 and 24 kDa fragments, processing of caspase-3 into its active form and the formation of DNA ladders. The intracellular calcium chelator BAPTA suppressed the differentiation markers, whereas antisense oligonucleotides and chem. inhibitors specific for calmodulin blocked both markers of differentiation and apoptosis. Modulation of p53 levels utilizing retroviral constructs expressing the E6, E7 or E6 + E7 genes of HPV-16 revealed that HD-induced apoptosis was partially p53-dependent. Finally, immortalized fibroblasts derived from PARP -/- "knockout mice" were exquisitely sensitive to HD-induced apoptosis. These cells became HD resistant when wild-type PARP was stably expressed in these cells. These results indicate that HD exerts its effects via calmodulin, p53 and PARP-sensitive pathways.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser, Janet; Meier, Henry L. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S23-S30. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72413 AN 2001:455389 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chem. warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compds. in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell prepns. were exposed to various concns. of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these expts. suggest that, with increasing HD concn. and time, NHEK will fragment irresp. of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains const. over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concn.- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, resp., is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concns. that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers, S.; Anderson, D.; Brobst, D.; Cowan, F. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S19-S22. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72270 AN 2001:455388 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chem. warfare compd., has been shown to deplete the NAD (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compds. To examine NAD+ levels, an automated method based on the alc. dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clin. analyzer has been developed. Automation of this assay led to smaller sample vols. and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD-exposed group. This assay appears to be useful for testing potential antivesicant compds. using both in vivo and in vitro exposure systems.

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Effects of Lewisite on cell membrane integrity and energy metabolism in human keratinocytes and SCL II cells. Kehe, K.; Flohe, S.; Krebs, G.; Kreppel, H.; Reichl, F. X.; Liebl, B.; Szinicz, L. Institute of Pharmacology and Toxicology, FAF Medical Academy, Munich, Germany. Toxicology (2001), 163(2-3), 137-144. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:133255 AN 2001:448571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite is a highly toxic arsenic compd. which can cause skin damage. In the present study effects of Lewisite on cell membrane integrity and energy metab. as well as antidotal effects of DL-2,3-dimercaptopropanesulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (m-DMSA) were investigated in a keratinocyte derived cell line (SCL II) and primary human keratinocytes (HK). Cells were incubated in Lewisite (60 M) contg. medium for 5 min. During the following 6 h lactate dehydrogenase (LDH) activity in the supernatant, intracellular ATP content, tetrazolium redn., glucose consumption and lactate formation were measured. Glucose consumption and lactate prodn. were decreased in both cell lines after Lewisite exposure. In SCL II cells an increase of LDH activity in the supernatant, a decrease of ATP content, and an impaired ability to reduce tetrazolium was found 3 h after Lewisite exposure. In HK cultures tetrazolium redn. was significantly decreased already after 2 h, whereas LDH increase in the supernatant and ATP content decrease occurred only at 6 h after Lewisite exposure. When DMPS or m-DMSA was added directly after Lewisite exposure to SCL II cells, glucose consumption and lactate formation were restored and LDH leakage was prevented. SCL II cells might be more prone to membrane damage whereas in keratinocytes mitochondrial impairment seems to be the predominant effect of Lewisite.

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Prophylactic efficacy of amifostine and its analogues against sulphur mustard toxicity. Vijayaraghavan, R.; Kumar, P.; Joshi, U.; Raza, S. K.; Lakshmana Rao, P. V.; Malhotra, R. C.; Jaiswal, D. K. Defence Research and Development Establishment, Gwalior, India. Toxicology (2001), 163(2-3), 83-91. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:299804 AN 2001:448565 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The successful implication of the chem. weapons convention stimulated research with a new vigor on the destruction of the stockpiled sulfur mustard (SM). A prophylactic agent for SM will be very useful for personnel engaged in the destruction of SM and during inspections by the Organization for the Prohibition of Chem. Weapons. Due to simple method of prepn., SM can be used clandestinely during war or by terrorist groups. Inspite of research over several decades no satisfactory prophylactic or treatment regimen has evolved for SM. Amifostine an organophosphorothioate, originally developed as a radioprotector, and its analogs were evaluated as a prophylactic agent for SM. Three analogs by varying the chain length and substitution at the sulfur atom were synthesized and coded as DRDE-06, DRDE-07 and DRDE-08. LD50 of amifostine and its analogs were estd. through i.p. route. For the protection studies, amifostine and its analogs were administered i.p. in mice, 30 min before dermal (percutaneous) application of SM. The dose of the prophylactic agent was 0.2 LD50 (i.p.) and that of SM was 152 mg/kg (undiluted) equal to 19-fold LD50 of SM. Amifostine and one of its analogs, DRDE-07 gave significant protection. Further studies were carried out using amifostine and DRDE-07, and both of them significantly protected mice against SM (155 mg/kg, in PEG 300, equal to 19 LD50) when they were administered i.p. either 30 min before or simultaneously. LD50 of amifostine and DRDE-07 were also estd. through the oral route (1049 or 1248 mg/kg, resp.). Prophylactically administered amifostine and DRDE-07 (0.2 LD50, p.o.) significantly protected the mice against dermally applied SM (155 mg/kg, in PEG 300, equal to 19 LD50). The protection offered by DRDE-07 was better than that of amifostine by the oral route. DRDE-07 (0.2 LD50, p.o.) also protected significantly with respect to the decrease in body wt. and the depletion of GSH induced by SM.
DNA damage induced by SM was also significantly reduced by amifostine and DRDE-07 (0.2 LD50, p.o.). Further studies are in progress on the various pharmacol. and toxicol. properties of DRDE-07.

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Adsorption of Organic Contaminants from Water Using Tailored ACFs. Mangun, Christian L.; Yue, Zhongren; Economy, James; Maloney, Stephen; Kemme, Patricia; Cropek, Donald. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, USA. Chemistry of Materials (2001), 13(7), 2356-2360. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 135:200059 AN 2001:428900 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Six activated carbon fibers (ACFs) with different chem. and phys. properties were prepd. by 1st curing a phenolic resin-coated glass fiber, followed by activation and post-treatment. Their adsorption properties were studied to evaluate the removal of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and the chem. warfare simulants diisopropylmethyl phosphonate (DIMP) and half mustard (HM) from water. The adsorption isotherms showed that ACF SL-2 (activated with CO2/H2O at 800) has a higher adsorption capacity for BTEX, DIMP, and HM than other ACFs. This suggests that the high adsorption affinity of SL-2 is related to its higher surface area, larger av. micropore size of 11.6 .ANG. (esp. effective for the adsorption of DIMP), and lower O content of the surface. The adsorption isotherms are well represented by the Freundlich equation. For BTEX, the adsorption parameters based on C coating showed that, in all cases, ACFs have a higher K value than the best available data obtained on granulated activated C. The adsorption isotherms of DIMP and HM on ACFs are presented.

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The U.S. Army reactive topical skin protectant (rTSP): challenges and successes. Hobson, Stephen T.; Lehnert, Erich K.; Braue, Ernest H., Jr. Drug Assessment Division, U. S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Materials Research Society Symposium Proceedings (2001), 628(Organic/Inorganic Hybrid Materials), CC10.8.1-CC10.8.8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 135:118044 AN 2001:354344 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In 1994, the U.S. Army initiated a research effort towards an effective material that acts both as a protective barrier and as an active destructive matrix against chem. warfare agents (CWA). We report results on our prepn. and evaluation of Reactive Topical Skin Protectants (rTSP's). These creams are composite materials consisting of a base material (TSP) and a reactive moiety. Using an established base of perfluorinated-polyether and perfluoropolyethylene solids we incorporated over 60 reactive components. Classes tested include org. polymers, org./inorg. hybrid materials, polyoxometallates (POM's), enzymes, inorg. oxides, metal alloys and small mols. We characterized these materials by light microscopy and FTIR. We detd. the efficacy of these materials against both sulfur mustard (HD) and a representative nerve agent, soman (GD), using a penetration cell model coupled to a continuous air monitor and also by in vivo testing. Composite materials with optimum reactive compds. exhibit a 94% redn. of GD vapor break-through after 20 h (from 9458 ng to 581 ng) and a 3.6 fold increase (from 162 min to 588 min) in the time 1000 ng of GD liq. penetrates through the material. Similar composite materials show a 99% redn. in HD vapor break-through after 20 h (from 4040 ng to 16 ng), a 2.3 fold increase (from 524 min to > 1200 min) in the time 1000 ng of HD vapor penetrates through the material, and an elimination of erythema vs. control in an HD vapor challenge. These results indicate that an rTSP that protects against sulfur mustard and nerve agents is within reach.

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Inhibition and promotion of combustion by organophosphorus compounds added to flames of CH4 or H2 in O2 and Ar. Korobeinichev, O. P.; Bolshova, T. A.; Shvartsberg, V. M.; Chernov, A. A. Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia. Combustion and Flame (2001), 125(1/2), 744-751. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 134:328437 AN 2001:309769 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Early in evaluating the destruction mechanisms of a no. of organophosphorus compds. (OPCs), such as tri-Me phosphate (TMP), di-Me methylphosphonate, and diisopropyl methylphosphonate, in connection with the disposal of chem. warfare agents, the promotion and inhibition effects of OPCs on stabilized flat flames of H2 +O2 were studied. Because OPCs were demonstrated to be more effective fire suppressants than CF3Br (Halon 1301) and due to the need for replacing the currently used Halon 1301, further investigation of the effects of the OPCs on flames is of interest. Thus a lean flame of CH4/O2/Ar (0.078/0.222/0.7) with and without TMP added, stabilized on a flat burner at 0.1 bar, was studied by mol. beam mass spectrometry (MBMS) and computer modeling using PREMIX and CHEMKIN codes. An exptl. study of this flame revealed that TMP increases the width of the reaction zone by inhibiting the flame.

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An Infrared Study of Adsorbed Organophosphonates on Silica: A Prefiltering Strategy for the Detection of Nerve Agents on Metal Oxide Sensors. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2001), 17(7), 2213-2218. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 134:349067 AN 2001:156303 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The gas-phase adsorption of the nerve gas simulant di-Me methylphosphonate (DMMP) along with tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on silica have been studied using IR spectroscopy. Each phosphonate compd. adsorbs through a different no. of H-bonds of the methoxy and P:O moieties with the surface hydroxyl groups on silica. The strength of the adsorption depends on the no. and type of the H-bonds and follows the order TCP < MDCP < DMMP < TMP. TCP is completely removed from silica by evacuation at room temp., adsorbed MDCP is removed by evacuation at 150 C, DMMP requires an evacuation temp. of 300 C, and TMP is eliminated at 400 C. All phosphonate compds. molecularly desorb, and the silica returns to its original state. The differences in the reactivity of phosphonate compds. on silica from other oxides demonstrate the potential use of silica in prefiltering/preconcg. strategies for semiconductive metal oxide based sensing devices. Specifically, it is shown that silica can be used to selectively adsorb DMMP from a gas stream contg. methanol/DMMP mixts.

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Reactions of VX, GB, GD, and HD with Nanosize Al2O3. Formation of Aluminophosphonates. Wagner, George W.; Procell, Lawrence R.; O'Connor, Richard J.; Munavalli, Shekar; Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA. Journal of the American Chemical Society (2001), 123(8), 1636-1644. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 134:276643 AN 2001:85006 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of VX, GB, GD, and HD with nanosize Al2O3 (AP-Al2O3) have been characterized by 31P, 13C, and 27Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH3)OR]3, are generated which are identical to synthesized model compds. Thus, the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amt. of the CH-TG sulfonium ion (12%), although some elimination of HCl is also obsd. (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addn. of excess water results in the quant. hydrolysis of sorbed HD to CH-TG. On AP-Al2O3 dried to remove physisorbed water, 13C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

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New microemulsions for oxidative decontamination of mustard gas analogues and polymer-thickened half-mustard. Gonzaga, Ferdinand; Perez, Emile; Rico-Lattes, Isabelle; Lattes, Armand. Laboratoire des Interactions Moleculaires et Reactivite Chimique et Photochimique (CNRS UMR 5623), Universite Paul Sabatier, Toulouse, Fr. New Journal of Chemistry (2001), 25(1), 151-155. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 134:232826 AN 2001:12053 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidn. of mustard gas analogs in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quant. and chemoselective oxidn. of the analogs. In a second formulation, the choice of microemulsion components used allowed us to study the oxidn. of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aq. systems.

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Bacterial release of arsenic ions and organoarsenic compounds from soil contaminated by chemical warfare agents. Kohler, Manfred; Hofmann, Klaus; Volsgen, Fernando; Thurow, Kerstin; Koch, Andreas. URST Umwelt- und Rohstoff-Technologie GmbH, Greifswald, Germany. Chemosphere (2000), Volume Date 2001, 42(4), 425-429. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 134:60919 AN 2000:878002 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The objective was to study possible participation of microorganisms in the release of sol. arsenical compds. from organoarsenic warfare agents in contaminated soil. A no. of bacterial strains were isolated with high resistance against As5+ ions which are able to degrade the water insol. compds. triphenylarsine (TP) and triphenylarsineoxide (TPO). Release of As and sol. organoarsenic compds. from soil by the activity of autochthonic soil bacteria and a mixt. of the isolated pure cultures was demonstrated by percolation expts. with undisturbed soil samples (core drills) from the contaminated site. This release increased after addnl. of nutrients (mineral N and P, Na acetate and ethanol) and is nearly independent of the percolation temp. (5 and 22). These results show that bacteria play an important role in the release of arsenical compds. from organoarsenic warfare agent contaminated soil. This release is limited by shortage of water and, above all, of nutrients for the microorganisms in the sandy forest soil. These results are important both for the management and security and possibly for bioremediation of military waste sites contg. similar contaminations.

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The chemistry of the destruction of organophosphorus compounds in flames-IV: destruction of DIMP in a flame of H2 + O2 + Ar. Korobeinichev, O. P.; Chernov, A. A.; Bolshova, T. A. Institute of Chemical Kinetics and Combustion, Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia. Combustion and Flame (2000), 123(3), 412-420. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 133:285779 AN 2000:714913 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mol. beam mass spectrometry with electron impact ionization at 11-70 eV and an electron energy spread of  0.25 eV was used to study the structure of a premixed H2/O2/Ar (0.26/0.13/0.61) flame without any additives and with 0.14% of diisopropylmethylphosphonate (DIMP), stabilized on a flat-flame burner at 62 mbar. Stable species (H2, O2, H2O), as well as atoms and radicals (H, O, OH) were monitored, including phosphorus-contg. compds.: DIMP and some intermediates of its destruction, phosphorus oxides and acids. The profiles of the mole fractions of most species, including those of atoms and free radicals were obtained. The calibration coeffs. for some species were detd. exptl., and estd. for others. Isopropylmethylphosphonate was detected as a main primary phosphorus-contg. product of the destruction of DIMP. It has been shown that bimol. reactions with hydroxyl radicals and hydrogen atoms, rather than a unimol. decompn., provide the crucial initial steps in the destruction of DIMP. A detailed mechanism for the destruction of DIMP in H2/O2/Ar flames is suggested.

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Cytotoxicity of the MEIC reference chemicals in rat hepatoma-derived Fa32 cells. Dierickx, P. J. Laboratorium Biochemische Toxikologie, Afdeling Toxikologie, Instituut voor Volksgezondheid, Brussels, Belg. Toxicology (2000), 150(1-3), 159-169. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 134:1437 AN 2000:660792 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The cytotoxicity of the MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) ref. chems. was investigated in rat hepatoma-derived Fa32 cells. The total protein content was measured as an endpoint after exposure times of 30 min and 24 h, both in normal and glutathione-depleted cells. The neutral red uptake inhibition and the MTT conversion were also measured after 30 min. On av., the cytotoxicity was higher in glutathione-depleted cells when compared to normal cells, and was lower after 30 min than after 24 h. Evidence was obtained for lysosomal attack (of five chems.) or mitochondrial dysfunction (of six chems.) as the primary intoxication mechanism. Malathion and mercuric chloride belong to both series of chems. Good to excellent correlations were obsd. when the 50% inhibitory concns. of the six different in vitro assays were compared. When the six in vitro assays in Fa32 cells were compared with the human toxicity, the correlation coeff. was almost always identical to that obtained previously in human hepatoma-derived Hep G2 cells. The latter was the best acute in vitro assay for the prediction of human toxicity within the MEIC study. Altogether the results integrate very well with the basal cytotoxicity concept (B. Ekwall; 1995).

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The role of time in toxicology or Haber's ct product. Rozman, K. K. Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA. Toxicology (2000), 149(1), 35-42. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 133:306404 AN 2000:589244 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It happened exactly 100 yr ago that Warren established for the first time a quant. link between dose and time while studying the toxicity of sodium chloride in Daphnia magna (Straus). During this century many toxicologists in different contexts returned to this idea, which has become known as Haber's rule of inhalation toxicol. Most attempts to explore this relationship ended in frustration because of the supposed occurrence of exceptions. Thus, toxicologists concd. on the quant. relationship between dose and effect under mostly isotemporal conditions while time took a back seat and was assigned such arbitrary, semiquant. designations as acute, subacute, subchronic and chronic. Time itself as a quantifiable variable of toxicity was seldom studied and when it was studied, it was often not under isodosic (steady state) conditions as required by theory. A recent anal. of toxicol. time indicated the impact of three independent time scales (toxicokinetic, toxicodynamic, exposure frequency/duration) in toxicol. studies, which interact with dose and effect to yield the enormous complexity known to every toxicologist. Based on prototypical examples when toxicokinetic (dioxins), toxicodynamic (nitrosamines, benzene) or exposure frequency (methylene chloride, chloroacetic acid, HgCl2, CdCl2, etc.) represent the crit. time scale, the general validity of the ct=k concept will be discussed as a starting point for a theory of toxicol. As endpoints of toxicity, (delayed) acute toxicity, blood dyscrasias and cancer will be used to illustrate the crit. conditions needed to demonstrate the validity of this theory.

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Detection of Fluorophosphonate Chemical Warfare Agents by Catalytic Hydrolysis with a Porous Silicon Interferometer. Sohn, Honglae; Letant, Sonia; Sailor, Michael J.; Trogler, William C. Department of Chemistry and Biochemistry, University of California at San Diego, CA, USA. Journal of the American Chemical Society (2000), 122(22), 5399-5400. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 133:100551 AN 2000:335868 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The detection of a fluorophosphonate nerve chem. warfare agent can be achieved with an oxidized porous silicon interferometer film contg. a Cu(II) hydrolysis catalyst and surfactant (CTAB). Hydrolysis of the nerve agent produces HF gas, which removes the silicon oxide as SiF4(g) and induces both a blue-shift and a decrease in intensity of the Fabry-Perot fringes. Significant changes in these 2 parameters are detected after 5 min of DFP vapor (800 ppm) exposure.

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Reactions of VX, GD, and HD with Nanosize CaO: Autocatalytic Dehydrohalogenation of HD. Wagner, George W.; Koper, Olga B.; Lucas, Erik; Decker, Shawn; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, MD, USA. Journal of Physical Chemistry B (2000), 104(21), 5118-5123. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 133:30783 AN 2000:281288 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of the chem. warfare agents VX, GD, and HD with nanosize CaO (AP-CaO), and HD with com. CaO were studied using solid-state MAS NMR. VX and GD hydrolyze to yield surface-bound complexes of nontoxic Et methylphosphonate and pinacolyl methylphosphonate, resp. The kinetics were characterized by an initial fast reaction followed by a slower, diffusion-limited reaction. Similar behavior is obsd. for HD on either dried or hydrated AP-CaO and CaO. On partially hydrated AP-CaO (but not CaO), a rather fast steady-state elimination of HCl occurs after an induction period. This behavior is attributed to acid-catalyzed surface reconstruction (to regenerate fresh surface) and the formation of CaCl2, which is known to be more reactive than CaO. The product distribution for HD is .apprx.80% divinyl sulfide and 20% thiodiglycol and/or sulfonium ions, which apparently reside as surface alkoxides. Such kinetic behavior was not evident for the common mustard simulant 2-chloroethyl Et sulfide (CEES) on partially hydrated AP-CaO, which exhibited only the typical fast/diffusion-limited reaction.

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Design and synthesis of an ,-difluorophosphinate hapten for antibody-catalyzed hydrolysis of organophosphorus nerve agents. Vayron, Philippe; Renard, Pierre-Yves; Valleix, Alain; Mioskowski, Charles. CEA, Service des Molecules Marquees, CE-Saclay, Gif sur Yvette, Fr. Chemistry--A European Journal (2000), 6(6), 1050-1063. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 133:13524 AN 2000:214064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In a new approach to the safe neutralization of organophosphorus chem. weapons, we designed a hapten to elicit catalytic antibodies with phosphatase activity. Here we report the synthesis of this ,-difluorophosphinate hapten 6. Various methods for the introduction of the key ,-difluoromethyl feature into the phosphinate hapten are discussed. The best results were obtained with the electrophilic gem-difluorinating agent N-fluorobenzenesulfonimide.

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Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate. Richardson, David E.; Yao, Huirong; Frank, Karen M.; Bennett, Deon A. Center for Catalysis Department of Chemistry, University of Florida, Gainesville, FL, USA. Journal of the American Chemical Society (2000), 122(8), 1729-1739. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 132:222157 AN 2000:94955 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Bicarbonate ion is an effective activator for hydrogen peroxide in the oxidn. of sulfides. Kinetic and spectroscopic results support the formation of peroxymonocarbonate ion (HCO4-) as the oxidant in the catalytic reactions. The reaction of hydrogen peroxide and bicarbonate to form HCO4- occurs rapidly at 25 (t1/2  300 s) near neutral pH in aq. soln. and alc./water mixts., and an equil. anal. of the reaction by 13C NMR leads to an est. of the electrode potential for the HCO4-/HCO3- couple (1.8 V vs NHE). Soly. of the bicarbonate catalyst is enhanced by the use of NH4HCO3 rather than by the use of group 1 salts, which tend to have lower soly. in the mixed solvents and can lead to phase sepn. Rate laws and mechanistic analyses are presented for the oxidn. of Et Ph sulfide and related sulfides. The second-order rate consts. for sulfide oxidns. by HCO4- are .apprx.300-fold greater than those for H2O2, and this increase is consistent with expectations based on a Bronsted anal. of the kinetics for other heterolytic peroxide oxidns. At high concns. of H2O2, a pathway that is second order in H2O2 is significant, and this path is interpreted as a general acid catalysis by H2O2 of carbonate displacement accompanying substrate attack at the electrophilic oxygen of HCO4-. Increasing water content up to 80% in the solvent increases the rate of oxidn. The BAP (bicarbonate-activated peroxide) oxidn. system is a simple, inexpensive, and relatively nontoxic alternative to other oxidants and peroxyacids, and it can be used in a variety of oxidns. where a mild, neutral pH oxidant is required. Variation of bicarbonate source and the cosolvent can allow optimization of substrate soly. and oxidn. rates for applications such as org. synthesis and chem. warfare agent decontamination.

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Synthesis and Characterization of a Functionalized Double-Chain Surfactant and Its Cleavage of O-Methyl S-Benzyl Phenylphosphonothioate. Jaeger, David A.; Li, Bei. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (2000), 16(1), 5-10. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 132:24141 AN 1999:379097 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant 2-hydrazino-N-methyl-N,N-didodecyl-2-oxoethanaminium bromide (I) was synthesized, and its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry. In a pH 9.0 borate buffer at 25, vesicular I and O-Me S-benzyl phenylphosphonothioate (II), a simulant for the chem. warfare agent VX [O-Et S-(2-N,N-diisopropylamino)ethyl methylphosphonothioate] reacted to give anion S-benzyl phenylphosphonothioate (III) and 3 cations (2-(2-N-methylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, 2-(2-N,N-dimethylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, and 2-[1-hydroxy-2-(N-methyl-N,N-didodecylammonio)ethylidene]-N',N',N'-trimethylhydrazinium, resp.) by SN2 substitution on the Me group of II. This reaction was accompanied by the pptn. of anion III with surfactant cations, which resulted in wounding/destruction of the vesicles. The combination of vesicle damage and reaction of II suggests the potential of vesicular systems for simultaneous signaling and decontamination of chem. agents. Ester II hydrolyzed in 0.10 M NaOH at 25 to give anions III and O-Me phenylphosphonothioate in a 38:62 ratio, resp.

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Reactivation kinetics of acetylcholinesterase from different species inhibited by highly toxic organophosphates. Worek F; Reiter G; Eyer P; Szinicz L Sanitatsakademie der Bundeswehr, Institut fur Pharmakologie und Toxikologie, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2002 Sep), 76(9), 523-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242610 AN 2002479746 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Standard treatment of poisoning by organophosphates (OP) includes the administration of an antimuscarinic agent, e.g. atropine, and of an acetylcholinesterase (AChE) reactivator (oxime). The presently available oximes, obidoxime and pralidoxime (2-PAM), are considered to be insufficient for highly toxic OPs, e.g. sarin. In the past decades numerous oximes were prepared and tested for their efficacy in OP poisoning, mostly in animal experiments. However, data indicate that the reactivating potency of oximes may be different in humans and animal species, which may hamper the extrapolation of animal data to humans and may pose a problem in the drug licensing of new compounds. In order to provide data for a better evaluation of the reactivating potency of oximes, experiments were undertaken to determine the reactivation rate constants of several oximes with human, rabbit, rat and guinea-pig AChE inhibited by the OPs sarin, cyclosarin and VX. The results show marked differences among the species, depending on the inhibitor and on the oxime, and indicate that the findings from animal experiments need careful evaluation before extrapolating these data to humans.

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Skin toxicokinetics of mustard gas in the guinea pig: effect of hypochlorite and safety aspects. Wormser Uri; Brodsky Berta; Sintov Amnon Faculty of Sciences,The Hebrew University, Edmond Safra Campus, Givat Ram, Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2002 Sep), 76(9), 517-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242609 AN 2002479745 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (SM, mustard gas) is a chemical warfare vesicant that rapidly penetrates the skin due to its hydrophobicity. This study measured the rate of SM disappearance from the skin after topical application of the vesicant. In both fur-covered and hairless animals, the remaining toxicant levels measured 60 min after exposure to undiluted SM were 0.6% and 0.3%, respectively, of the initially applied SM amount. However, SM concentration reached 0.4% of the initial dose 3 h following exposure in female fur-covered guinea pigs. SM quantities extracted from skin of male fur-covered and hairless guinea pigs immediately after 16 min of exposure to SM vapor were 12.2 and 21.8 microg, respectively; levels declined to 1.6 and 1.7 microg at 30 and 15 min following termination of exposure of male fur-covered and hairless guinea pigs, respectively. Three swabbing treatments of undiluted SM-exposed skin with gauze pads soaked in 0.5% hypochlorite caused 68% reduction in skin SM content. Similar findings were obtained when hypochlorite was replaced by water (64% reduction). SM content in the gauze pads was 59, 38 and 25 microg, respectively, for the first, second and third decontamination processes with water. No SM was detected in the gauze pads soaked with hypochlorite. In vitro studies showed that incubation of SM with 0.5% hypochlorite at a ratio of 10:1 (v/v) did not cause SM inactivation, whereas 4% hypochlorite reduced SM levels by 17%. However, at a decontaminant:SM ratio of 1000:1, 0.5% and 4% hypochlorite reduced SM levels by 92% and 99%, respectively. These findings are important for health authorities and regulatory agencies in planning precautionary steps to be taken in case of emergency and in routine laboratory work.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock Shannon D; Till Gerd O; Smith Milton G; Ward Peter A Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602, USA Journal of applied toxicology : JAT (2002 Jul-Aug), 22(4), 257-62. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12210543 AN 2002449749 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The chemical warfare agent analog, 2-chloroethyl ethyl sulfide, known as 'half-mustard gas' (HMG), is less toxic and less of an environmental hazard than the full molecule and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of (125)I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, we observed significant attenuation of the pulmonary injury when experimental animals were complement or neutrophil depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, dimethyl sulfoxide, dimethyl thiourea, resveratrol and N-acetyl-L-cysteine (NAC). The last compound showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement mediated pathways and the generation by neutrophils of toxic oxygen species The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat. Copyright 2002 John Wiley & Sons, Ltd.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber Ellen; McGuire Raymond Environment Protection Department, Lawrence Livermore National Laboratory, University of California, P.O. Box 808, L-626, Livermore, CA 94551, USA Journal of hazardous materials (2002 Aug 5), 93(3), 339-52. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12137994 AN 2002389537 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A decontamination method has been developed using a single reagent that is effective both against chemical warfare (CW) and biological warfare (BW) agents. The new reagent, "L-Gel", consists of an aqueous solution of a mild commercial oxidizer, Oxone, together with a commercial fumed silica gelling agent, Cab-O-Sil EH-5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. The new reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Experiments to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Laboratory and independently at four other locations. L-Gel was tested against all classes of chemical warfare agents and against various biological warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biological agents. Testing showed that L-Gel is as effective against chemical agents and biological materials, including spores, as the best military decontaminants.

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Adamantyl tenocyclidines--adjuvant therapy in poisoning with organophosphorus compounds and carbamates. Erratum in: Arch Toxicol 2002 Sep;76(9):552 Skare Danko; Radic Bozica; Lucic Ana; Peraica Maja; Domijan Ana-Marija; Milkovic-Kraus Sanja; Bradamante Vlasta; Jukic Ivan Institute Ruder Boskovic, Bijenicka c. 54, 10000 Zagreb, Croatia. skare@rudjer.irb.hr Archives of toxicology (2002 Apr), 76(3), 173-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11967623 AN 2002328057 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The objective of this study was to evaluate the efficacy of thienyl phencyclidine (tenocyclidine, TCP) and its newly synthesized adamantyl derivatives containing piperidine (TAPIP), pyrolidine (TAPIR) and morpholine (TAMORF) groups, which were tested with or without standard therapy in mice poisoned with organophosphates (OPs) and carbamates. These compounds with potential activity at the N-methyl- D-aspartate and muscarinic receptors showed low acute toxicity, having LD50 values varying from 106.00 mg/kg (TCP) to >504.00 mg/kg body weight (TAMORF). TCP and its adamantyl derivatives were administered intraperitoneally (2.5 mg/kg body weight) together with atropine (10.0 mg/kg body weight) and with or without 1/4 LD50 of the oxime HI-6. Each compound administered with atropine had a therapeutic effect against poisoning with carbamates propoxur, aldicarb and Ro 02-0683 (protective ratio of tenocyclidines was from 3.99 LD50 of aldicarb to >16.00 LD50 for propoxur). However, the efficacy of those compounds in combination with atropine was lower against poisoning with the OP insecticide dichlorvos (DDVP) and chemical warfare agents soman and tabun. In soman-poisoned mice, the best therapeutic effects were obtained with the combination of HI-6 plus atropine and test compounds, with protective ratios being from 5.40 to 7.12 LD50 of soman. The results suggest that TCP and adamantyl tenocyclidines could be used in combination with atropine as antidotes in carbamate poisoning and as adjuvant therapy to HI-6 and atropine in soman poisoning.

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Site-specific percutaneous absorption of methyl salicylate and VX in domestic swine. Duncan E J Scott; Brown April; Lundy Paul; Sawyer Thomas W; Hamilton Murray; Hill Ira; Conley John D Chemical Biological Defence Section, Defence Research Establishment, Suffield, PO Box 4000, Station Main, Medicine Hat, Alberta, Canada T1A 8K6 Journal of applied toxicology : JAT (2002 May-Jun), 22(3), 141-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12015792 AN 2002313565 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The site specificity of the percutaneous absorption of methyl salicylate (MeS) and the organophosphate nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) was examined in anaesthetized domestic swine that were fully instrumented for physiological endpoints. Four different anatomical sites (ear, perineum, inguinal crease and epigastrium) were exposed to the MeS and the serum levels were measured over a 6-h time period. The dose absorbed at the ear region was 11 microg cm(-2) with an initial flux of 0.063 microg cm(-2)min(-1), whereas at the epigastrium region the dose absorbed was 3 microg cm(-2) with an initial flux of 0.025 microg cm(-2)min(-1). For this reason further studies were carried out with VX on the ear and the epigastrium only. In animals treated with agent on the epigastrium, blood cholinesterase (ChE) activity began to drop 90 min after application and continued to decline at a constant rate for the remainder of the experiment to ca. 25% of awake control activity. At this time there were negligible signs of poisoning and the medical prognosis was judged to be good. In contrast, the ChE activity in animals receiving VX on the ear decreased to 25% of awake control values within 45 min and levelled out at 5-6% by 120 min. Clinical signs of VX poisoning paralleled the ChE inhibition, progressing in severity over the duration of the exposure. It was judged that these animals would not survive. The dramatic site dependence of agent absorption leading to vastly different toxicological endpoints demonstrated in this model system has important ramifications for chemical protective suit development, threat assessment, medical countermeasures and contamination control protocols. Copyright 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

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An improved brain slice model of nerve agent-induced seizure activity. Wood S J; Tattersall J E Biomedical Sciences Department, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S83-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920926 AN 2002191151 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice preparation. Soman (1 microM) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists, but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice preparation is a suitable model for investigating the origin and propagation of nerve-agent-induced seizures within the limbic system. Copyright 2001 John Wiley & Sons, Ltd.

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Cardiopulmonary effects of HI-6 treatment in soman intoxication. Goransson-Nyberg A; Cassel G Division of NBC Defence, Department of Medical Counter Measures, Swedish Defence Research Agency, SE-90182 Umea, Sweden Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S79-81. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920925 AN 2002191150 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The cardiopulmonary effects of HI-6, together with atropine and soman, were studied in the rat. HI-6 is an effective antidote in acute poisoning with the nerve agent soman. The therapeutic efficiency of HI-6 is still unclear and cannot be explained entirely by the HI-6 reactivating ability of acetylcholinesterase (AChE). Other non-cholinergic factors must be involved. One possible detoxifying process might be an effect of HI-6 on the blood flow to sensitive organs. The purpose of the present study was to investigate 1) whether soman per se induces changes in regional blood flow and 2) whether the blood flow to different organs is affected when HI-6 (50 mg x kg(-1) i.m.) and atropine (10 mg x kg(-1) i.m.) are given either before or immediately after soman intoxication (90 microg x kg(-1) s.c.). For regional blood flow determinations the microsphere method was used with male Wistar rats weighing 300-400 g. The rats were anaesthetised and breathed spontaneously during the experiment. Three different blood flow measurements were made in the same animal and concomitant physiological parameters such as mean arterial blood pressure and respiratory rate were recorded. The blood AChE activity was followed throughout the experiment. Our results show that when HI-6 is given after intoxication with soman, dramatic changes in blood flow occur with a significant decrease in both respiratory rate and blood AChE activity. If HI-6 is given prior to the intoxication, however, all rats are unaffected and none of the parameters measured are changed. Copyright 2001 John Wiley & Sons, Ltd.

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Prophylaxis against organophosphate poisoning by sustained release of scopolamine and physostigmine. Meshulam Y; Cohen G; Chapman S; Alkalai D; Levy A Department of Pharmacology, Israel Institute for Biological Research (IIBR), PO Box 19, 70450 Ness-Ziona, Israel Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S75-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920924 AN 2002191149 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Protection efficacy of continuous prophylactic administration of physostigmine and scopolamine against sarin-induced toxicity was evaluated previously in guinea pigs. The present study in large animals used Beagle dogs, that serve as an animal model with cholinergic sensitivity similar to that of humans. Pretreatment with physostigmine salicylate and scopolamine hydrochloride at dose rates of 2.5 and 1 microg x kg(-1) x h(-1), respectively, was administered via Alzet mini-osmotic pumps. At the time of exposure, the physostigmine salicylate concentration in plasma was 0.7 ng x ml(-1) and the scopolamine hydrochloride concentration was ca. 0.2 ng x ml(-1), both of which are levels known to be well tolerated in humans. Whole-blood cholinesterase inhibition was 15-20%. This regimen conferred full protection against 2.5 x LD50 i.v. of sarin. Albeit the high-dose exposure, cholinergic toxicity symptoms were mild with no convulsions. About 11-14 min following poisoning the treated animals started to walk and 15-20 min following exposure full recovery was observed and the dogs behaved normally. With higher dose rates of physostigmine salicylate and scopolamine hydrochloride, at plasma concentrations of 2.1 and 0.6 ng x ml(-1), respectively, treated dogs regained normal posture 6-10 min after exposure. Copyright 2001 John Wiley & Sons, Ltd.

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Intramuscular diazepam pharmacokinetics in soman-exposed guinea pigs. Capacio B R; Whalley C E; Byers C E; McDonough J H Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S67-74. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920923 AN 2002191148 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Intramuscular (i.m.) diazepam is included by the US military as an anticonvulsant in the standard therapeutic regimen for organophosphorus nerve agent intoxication. In this study we investigated the pharmacokinetics of diazepam after i.m. administration while monitoring pharmacodynamic (electroencephalogram, EEG) data in soman-exposed guinea pigs. Prior to experiments the animals were surgically implanted with EEG leads to monitor seizure activity. For the study, animals were administered pyridostigmine (0.026 mg x kg(-1) i.m.) 30 min prior to soman (56 microg x kg(-1), 2 x LD50; subcutaneously, s.c.), which was followed in 1 min by atropine sulfate (2 mg x kg(-1) i.m.) and pralidoxime chloride (25 mg x kg(-1) i.m.). All animals receiving this regimen developed seizure activity. Diazepam (10 mg x kg(-1) i.m.) was administered 5 min after onset of seizure activity. Based on EEG data, animals were categorized as either seizure terminated or not terminated at 30 min after diazepam. Serial blood samples were obtained from each animal. Diazepam (10 mg x kg(-1) i.m.) terminated seizure activity in 52% of the animals within 30 min. The pharmacokinetics were characterized by a one-compartment model with first-order absorption and elimination. The maximum plasma concentrations (Cmax) were 991 and 839 ng x ml(-1) for seizure terminated and not terminated, respectively. Mean plasma concentrations of diazepam were significantly different (P < 0.05) for seizure terminated vs not terminated groups at 30 min. The plasma Cmax in seizure-terminated animals in this study is similar to the minimum range of plasma diazepam (200-800 ng x ml(-1)) reported to suppress seizure activity in humans. It has been reported in an earlier study that the minimum effective i.m. dose (0.1 mg x kg(-1)) required to prevent soman-induced convulsions in Rhesus monkeys produces a mean Cmax of 50 ng x ml(-1) for diazepam.
The data from our current study suggest that a higher dose (and corresponding Cmax) is necessary to terminate ongoing seizure activity. Copyright 2001 John Wiley & Sons, Ltd.

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Combination anticonvulsant treatment of soman-induced seizures. Koplovitz I; Schulz S; Shutz M; Railer R; Macalalag R; Schons M; McDonough J Drug Assessment Division, US Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010, USA. Koplovitz@asia.apgea.army.mil Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S53-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920921 AN 2002191147 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures. Copyright 2001 John Wiley & Sons, Ltd.

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Soman-induced seizures: limbic activity, oxidative stress and neuroprotective proteins. Pazdernik T L; Emerson M R; Cross R; Nelson S R; Samson F E Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City, KS 66160, USA. tpazdern@kumc.edu Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S87-94. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920927 AN 2002185330 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman, a potent acetylcholinesterase inhibitor, induces status epilepticus in rats followed by conspicuous neuropathology, most prominent in piriform cortex and the CA3 region of the hippocampus. Cholinergic seizures originate in striatal-nigral pathways and with fast-acting agents (soman) rapidly spread to limbic related areas and finally culminate in a full-blown status epilepticus. This leads to neurochemical changes, some of which may be neuroprotective whereas others may cause brain damage. Pretreatment with lithium sensitizes the brain to cholinergic seizures. Likewise, other agents that increase limbic hyperactivity may sensitize the brain to cholinergic agents. The hyperactivity associated with the seizure state leads to an increase in intracellular calcium, cellular edema and metal delocalization producing an oxidative stress. These changes induce the synthesis of stress-related proteins such as heat shock proteins, metallothioneins and heme oxygenases. We show that soman-induced seizures cause a depletion in tissue glutathione and an increase in tissue 'catalytic' iron, metallothioneins and heme oxygenase-1. The oxidative stress induces the synthesis of stress-related proteins, which are indicators of 'stress' and possibly provide neuroprotection. These findings suggest that delocalization of iron may catalyze Fenton-like reactions, causing progressive cellular damage via free radical products. Copyright 2001 John Wiley & Sons, Ltd.

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Beneficial effects of TCP on soman intoxication in guinea pigs: seizures, brain damage and learning behaviour. de Groot D M; Bierman E P; Bruijnzeel P L; Carpentier P; Kulig B M; Lallement G; Melchers B P; Philippens I H; van Huygevoort A H TNO Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S57-65. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920922 AN 2002185328 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Poisoning with the potent nerve agent soman produces a cascade of central nervous system (CNS) effects characterized by severe convulsions and eventually death. In animals that survive a soman intoxication, lesions in the amygdala, piriform cortex, hippocampus and thalamus can be observed. In order to examine the mechanisms involved in the effects of soman and to evaluate possible curative interventions, a series of behavioural, electrophysiological and neuropathological experiments were carried out in the guinea pig using the NMDA antagonist N-[1-(2-thienyl)cyclohexyl] piperidine (TCP) in conjunction with atropine and pyridostigmine. The NMDA antagonist TCP appeared to be very effective in the treatment of casualties who suffered from soman-induced seizures for 30 min: (i)Seizures were arrested within minutes after the TCP injection, confirmed by quantitative electroencephalogram (EEG), after fast Fourier analysis. Three hours after TCP the quantitative EEGs were completely normal in all frequency bands and remained normal during the entire 3-week intoxication period. The power shift to the lower (delta) frequency bands, indicative for neuropathology and found in control animals intoxicated only by soman, was not observed in the soman-TCP group. (ii)The gross neuropathology found in soman control animals within 48 h after soman was prevented in soman-TCP animals and was still absent in 3-week survivors. Instead, ultrastructural changes were observed, indicative of defense mechanisms of the cell against toxic circumstances. (iii)Twenty-four hours after soman, soman-TCP animals were able to perform in the shuttle box and Morris water maze. The beneficial effects of TCP on the performance in these tests during the 3-week intoxication period were very impressive, notwithstanding (minor) deficits in memory and learning. (iv)The increase in excitability after TCP was confirmed by an increase in the acoustic startle response.
Taken together, these results confirmed the involvement of NMDA receptors in the maintenance of soman-induced seizures and the development of brain damage. They underline the current hypothesis that cholinergic mechanisms are responsible for eliciting seizure activity after soman and that, most likely, the subsequent recruitment of other excitatory neurotransmitters and loss of inhibitory control are responsible for the maintenance of seizures and the development of subsequent brain damage. Copyright 2001 John Wiley & Sons, Ltd.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw M D; Hayes T L; Miller T L; Shannon C M Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH 43201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S3-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920912 AN 2002185325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate--a V-type nerve agent developed by the former Soviet Union--in the environment is an important parameter in threat assessment analysis and for the determination of use, production, testing and storage of this chemical warfare agent. S-(N,N-Diethylaminoethyl) isobutyl methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same molecular formula, it is expected that their physical and chemical properties would be different. This preliminary investigation was undertaken to determine the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compound at approximately 1 mg x ml(-1) in unbuffered water at pH 7 was determined side-by-side. The half-lives for VXA and VX were determined to be 12.4 days and 4.78 days, respectively. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chemical Weapons Convention. Copyright 2001 John Wiley & Sons, Ltd.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller J K; Lenz D E Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD 21201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S23-6. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920916 AN 2002185323 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-molecular-weight compounds is effected by the use of chromatographic techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the analysis. To overcome those drawbacks, we have been involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds such as pinacolylmethyl phosphonofluoridate (soman), which is a chemical warfare agent. Prior estimates suggested that it is necessary to be able to detect soman at a concentration below 2.5 x 10(-7) M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The minimum required assay time was 2.0-2.5 h with no loss in sensitivity. To determine the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogues were 5 x 10(-7) M for 4-nitrophenylpinacolylmethylphosphonate, 8 x 10(-7) M for dipinacolylmethylphosphonate, 2 x 10(-6) M for diisopropylmethylphosphonate, 3 x 10(-5) M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5 x 10(-5) M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman molecule, were effective inhibitors. Compounds, which contained predominately aromatic groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to determine its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman. Copyright 2001 John Wiley & Sons, Ltd.

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Protective action of the serine protease inhibitor N-tosyl-L-lysine chloromethyl ketone (TLCK) against acute soman poisoning. Cowan F M; Broomfield C A; Lenz D E; Shih T M Biochemical Pharmacology and Neurotoxicology Branches, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 293-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481662 AN 2002027826 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman-poisoned rats display cholinergic crisis, a systemic mast cell degranulation characteristic of anaphylactic reactions and an excitotoxin-like sequential seizure and neuronal degeneration. The protection of guinea pigs from soman lethality by prophylactic administration of the serine protease inhibitor suramin suggests a possible proteolytic component in soman poisoning. The present study tested the effect of N-tosyl-L-lysine chloromethyl ketone (TLCK), an inhibitor of trypsin-like serine proteases, on soman-induced toxic signs (convulsions, righting reflex) and survival time. Nine control guinea pigs receiving 2 x LD(50) (56 microg kg(-1), s.c.) of soman immediately followed by a therapeutic dose of atropine sulfate (17.4 mg kg(-1) i.m.) experienced severe convulsions, and 8/9 lost the righting reflex. Six of these nine animals expired within 65 min; the three remaining animals survived 24 h to termination of the experiment. When a second group of animals were given TLCK (12 mg kg(-1), i.p.) 30 min prior to a 2 x LD(50) soman challenge and atropine-sulfate therapy, 5/9 experienced convulsions and only 3/9 lost the righting reflex. All nine animals survived beyond 4 h, with six surviving to 24 h. Compared with soman controls, prophylaxis with TLCK significantly prevented the loss of righting reflex (P = 0.05) and enhanced 4-h survival (P = 0.005). Although, convulsions were reduced and 24-h survival was improved in TLCK-treated animals, these results were not statistically significant. The protection from soman toxicity by chemically distinct protease inhibitors such as suramin and TLCK suggests a role for pathological proteolytic pathways in soman intoxication. Copyright 2001 John Wiley & Sons, Ltd.

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin. Chilcott R P; Jenner J; Hotchkiss S A; Rice P Department of Biomedical Sciences, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 279-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481660 AN 2002027824 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption. Copyright 2001 John Wiley & Sons, Ltd.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen J; Riikonen K; Nikmo J; Jappinen A; Nieminen K Air Quality Research, Finnish Meteorological Institute, Sahaajankatu 20 E, FIN-00810, Helsinki, Finland. jaakko.kukkonen@fmi.fi Journal of hazardous materials (2001 Aug 17), 85(3), 165-79. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11489522 AN 2001443815 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

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Effects of iodine on inducible nitric oxide synthase and cyclooxygenase-2 expression in sulfur mustard-induced skin. Nyska A; Lomnitski L; Maronpot R; Moomaw C; Brodsky B; Sintov A; Wormser U Laboratory of Experimental Pathology, National Institutes of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA. nyska@niehs.nih.gov Archives of toxicology (2001 Feb), 74(12), 768-74. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11305779 AN 2001394179 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

In a previous study we demonstrated the protective effect of topical iodine as postexposure treatment for sulfur mustard (SM) application. The iodine treatment results in significantly reduced inflammation and necrosis and increased epidermal hyperplasia. The expression and localization of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in paraffin-embedded skin samples from that study were evaluated in the present investigation. We compared the immunoreactivity of iNOS and COX-2 using five samples from each of the following four test sites: untreated control sites, SM-exposed sites, sites treated with iodine mixture 15 min after SM exposure, and sites treated with iodine 30 min after SM exposure. All animals were killed 2 days after irritant exposure. iNOS immunoreactivity was present only in skin sites exposed to SM without iodine treatment. The ulcerated skin was covered with a relatively thick band of exudate composed of iNOS-immunostained polymorphonuclear cells and macrophages. In untreated skin, COX-2 immunostaining was limited to the thin suprabasal epidermal layer. In SM-exposed skin, induction of COX-2 was noted in inflammatory cells located close to the site of epidermal injury. In skin sites treated with iodine 15 or 30 min after SM exposure, the regenerating hyperplastic epithelium showed moderate cytoplasmic staining localized to the epithelium overlying the basal layer. This pattern of staining was also present in the nearby dermal fibroblasts. Thus, in contrast to the skin samples exposed to SM without iodine treatment, the epidermal layer expressing immunohistochemical positivity for COX-2 was thicker and corresponded to the epidermal hyperplasia noted in samples treated with iodine. It is well documented that prostaglandins (PGs) promote epidermal proliferation, thereby contributing to the repair of injured skin. That the induction of the COX-2 shown in our study may also play a role in the healing process is indicated by the present evidence.
The results suggest that nitric oxide radicals (NO*) are involved in mediating the damage induced by the SM and that iodine-related reduction in acute epidermal inflammation is associated with reduced iNOS expression.

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Intervention of sulfur mustard toxicity by downregulation of cell proliferation and metabolic rates. Ray R; Benton B J; Anderson D R; Byers S L; Petrali J P US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. radharaman.ray@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S87-91. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428650 AN 2001371709 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chemical warfare compound HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37 degrees C) first in keratinocyte growth medium (KGM) containing BAPTA AM (10-40 microM) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concentration-dependent manner with some cellular degeneration above 30 microM (light microscopy). At 20-30 microM, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 54 +/- 5%), [3H]-uridine (RNA synthesis, 29 +/- 6%) and [14C]-valine (protein synthesis, 12 +/- 2%) as well as a lower protein content per culture (30 +/- 3%) compared with corresponding untreated controls. However, 20-30 microM BAPTA AM did not cause any demonstrable cytopathology based on morphological (electron microscopy) as well as biochemical (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser J; Meier H L Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S23-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428638 AN 2001371697 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chemical warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compounds in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell preparations were exposed to various concentrations of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these experiments suggest that, with increasing HD concentration and time, NHEK will fragment irrespective of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains constant over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concentration- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, respectively, is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concentrations that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price E O; Smith J R; Clark C R; Schlager J J; Shih M L Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S193-7. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428636 AN 2001371695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The continual threat of chemical and biological warfare has prompted the need for unambiguous analytical methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with hemoglobin and metallothioneine were conducted. In vitro experiments with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to determine the extent of alkylation and occurrence of HD cross-linking using the MALDI-ToF/MS technique. In a typical experiment, 50 ml of 5 mM HD in acetonitrile was added to an equal volume of 0.5 mM hemoglobin in deionized water followed by vortexing and incubation at room temperature. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES experiments. These results demonstrate that MALDI-ToF/MS is a useful analytical technique to investigate the interaction of HD with biomolecules and may be employed potentially as a diagnostic tool for the confirmation of exposure to chemical warfare agents.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers S; Anderson D; Brobst D; Cowan F Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S19-22. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428635 AN 2001371694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham J S; Reid F M; Smith J R; Stotts R R; Tucker E S; Shumaker S M; Niemuth N A; Janny S J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S161-72. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428630 AN 2001371689 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chemical warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clinical pathology findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liquid on the ventral surface for 2 h, generating six 3-cm diameter full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematology and serum chemistry examinations. Urine was collected in metabolism cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatography/mass spectrometry. Examination of clinical pathology parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clinically significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 microg ml(-1) with a mean of 2.14 microg ml(-1). Thiodiglycol concentrations were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml(-1). Mean levels remained 10-40 ng ml(-1) for the remainder of the 7-day observation period, with the highest individual concentration noted during this period of 132 ng ml(-1). Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other laboratory animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 week.
Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h. Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin M C; Ricketts K; Skvorak J P; Gazaway M; Mitcheltree L W; Casillas R P Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA. Michael.Babin@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S141-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428627 AN 2001371686 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quantitative edema response as well as histopathological and biochemical endpoints as measurements of inflammation and tissue damage following exposure to the chemical warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal separation. This study evaluated the protective effects of three of these pharmacological compounds when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver a subcutaneous dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 microl of a 195 mM (0.16 mg) solution of sulfur mustard (density = 1.27 g ml(-1); MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathological damage (necrosis, epidermal-dermal separation). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant reduction in edema (24%, 26% and 22%, respectively) from the positive control. Compared to HD-positive controls, hydrocortisone, indomethacin and olvanil caused a significant reduction in subepidermal blisters (71%, 52% and 57%, respectively) whereas only hydrocortisone produced a significant reduction in contralateral epidermal necrosis (41%). We show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins K B; Lodhi I J; Hurley L L; Hinshaw D B University of Michigan Medical School, Ann Arbor 48105, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S125-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428622 AN 2001371681 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chemical warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells (Toxicol. Appl. Pharmacol. 1996; 141: 568-583). Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFkappaB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFkappaB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 microM HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 microM buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 microM HD for 5-6 h. Externally applied GSH up to a concentration of 5 mM had no toxic effect on the cells. Mild toxicity was associated with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examined the hypothesis that HD may activate the nuclear transcription factor NFkappaB by performing EMSAs with nuclear extracts of endothelial cells following exposure to 0, 250 or 500 microM HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFkappaB binding to its consensus sequence induced by 500 microM HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFkappaB, although HD-induced activation of NFkappaB was partially suppressed by NAC at 5 h. Factor NFkappaB is an important transcription factor for a number of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFkappaB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFkappaB activity. The NFkappaB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction associated with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha M; Bowers W Jr; Kohl J; DuBose D; Walker J; Alkhyyat A; Wong G US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S101-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428619 AN 2001371678 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chemical warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl ethyl sulfide (CEES, 1-2 mg l(-1) min(-1)) in humidified air or to humidified air alone. Tissues were evaluated histologically, ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histology showed that CEES induced the separation of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histology and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1alpha (IL-1alpha), prostaglandin-E2 (PGE2) and especially IL-1 receptor antagonist (IL-1Ra) release (56,334 vs 84,614 pg ml(-1)), but decreased interleukin-6 (IL-6, 4,755 vs 351 pg ml(-1)). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracelluar IL-1alpha (371 vs 92 pg ml(-1)). Extracellular IL-1Ra greatly increased (2,375 vs 24,875 pg ml(-1)), whereas cellular levels decreased (16,5425 vs 96,625 pg ml(-1)). Extracellular (224 vs 68 pg ml(-1)) and intracellular (485 vs 233 pg ml(-1)) soluble interleukin-1 receptor H (sIL-1RII) decreased. Prostanglandin E2 increased (1,835 vs 2,582 pg ml(-1)), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57,000 vs 96,000 pg ml(-1)). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Correlation of a specific mitochondrial phospholipid-phosgene adduct with chloroform acute toxicity. Di Consiglio E; De Angelis G; Testai E; Vittozzi L Biochemical Toxicology Unit, Department of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita, Viale Regina Elena 299, I-00161, Rome, Italy Toxicology (2001 Feb 21), 159(1-2), 43-53. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11250054 AN 2001195862 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The dose and time dependence of formation of a specific adduct between mitochondrial phospholipid and phosgene have been determined in the liver of Sprague-Dawley (SD) rats as well as in the liver and kidney of B6C3F1 mice after dosing with chloroform. Rats were induced with phenobarbital or non-induced. Determination of tissue glutathione (GSH) and of serum markers of hepatotoxicity and nephrotoxicity was also carried out. With dose-dependence experiments, a strong correlation between the formation of the specific phospholipid adduct, GSH depletion and organ toxicity could be evidenced in all the organs studied. With non-induced SD rats, no such effects could be induced up to a dose of 740 mg/kg. Time-course studies with B6C3F1 mice indicated that the specific adduct formation took place at very early times after chloroform dosing and was concurrent with GSH depletion. The adduct formed during even transient GSH depletion (residual level: 30% of control) and persisted after restoration of GSH levels. Following a chloroform dose at the hepatotoxicity threshold (150 mg/kg), the elimination of the adduct in the liver occurred within 24 h and correlated with the recovery of ALT, which was slightly increased (12 times) after treatment. Following a moderately nephrotoxic dose (60 mg/kg), the renal adduct persisted longer than 48 h, when a 100% increase in blood urea nitrogen and a 40% increase in serum creatinine indicated the onset of organ damage. The formation of the adduct in the liver mitochondria of B6C3F1 mice was associated with the decrease of phosphatidyl-ethanolamine (PE), in line with previous results in rat liver indicating that the adduct results from the reaction of phosgene with PE. The adduct levels implicated the reaction of phosgene with about 50% PE molecules in the liver mitochondrial membrane of phenobarbital-induced SD rats and of about 10% PE molecules of the inner mitochondrial membrane of the liver of B6C3F1 mice.
The association of this adduct with the toxic effects of chloroform makes it a very good candidate as the primary critical alteration in the sequence of events leading to cell death caused by chloroform.

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The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats. Kassa J; Fusek J Purkyne Military Medical Academy, PO Box 35/T, 500 01, Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2000 Nov 23), 154(1-3), 67-73. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11118671 AN 2001083637 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.

[megalomania]

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Development of multifunctional perfluorinated polymer blends as an active barrier cream against chemical warfare agents. Hobson, Stephen T.; Braue, Ernest H., Jr. Drug Assessment Div., U.S. Army Medical Research Institute for Chemical Defense, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 80-81. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:363990 AN 2003:381106 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare agents (CWA's) represent a real and growing threat both to U.S. armed forces as well as to civilians. Within the last three decades, chem. weapons have been used by the Soviets in Cambodia (yellow rain, tricothecene mycotoxins), by Iraq against Iran (HD and tabun), and by Iraq against its own dissident Kurdish population at Halabja (H-ID HCN0). In the United States' experience in World War I, almost one-third of hospitalized casualties were a result of CWA's. Furthermore, the 1000 casualties and 12 deaths resulting from the 1995 terrorist use of sarin (GB) in Tokyo show that civilians have also become targets. In this paper we focus on protection against two classes of CWA's: nerve agents (soman, GD) and blister agents (sulfur mustard, HD). Protection against these agents in the United States Army consists of a chem. resistant outer layer of clothing (BDO) and protective mask (M40). This scheme of protection allows operation in a chem. contaminated area but results in decreased performance and increased heat retention. We have investigated a material that serves as a phys. barrier to CWA's and contains an active moiety to neutralize hazardous chems. This Active Topical Skin Protectant (aTSP) would be used in conjunction with other protective procedures. Herein we report the prepn., characterization, and evaluation of aTSP's.

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Molecularly imprinted polymers for the detection of chemical agents in water. Jenkins, Amanda L.; Yin, Ray; Jensen, Janet L.; Durst, H. Dupont. US Army Research Laboratory, Aberdeen Proving Ground, MD, USA. Polymeric Materials Science and Engineering (2001), 84 76-77. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 138:343335 AN 2003:381101 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molecularly imprinted polymers contg. Eu3+ were prepd. using a no. of pesticides and pinacolyl methylphosphonate (hydrolysis product of the nerve agent Soman), and sensors were fabricated by coating the polymers on optical fibers. The sensors were characterized in terms of sensitivity, selectivity, response time, adaptability, and portability; they provided detection limits in the low parts per trillion.

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Synthesis of carbon-coated MgO nanoparticles. Bedilo, Alexander F.; Sigel, M. Jake; Koper, Olga B.; Melgunov, Maxim S.; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Journal of Materials Chemistry (2002), 12(12), 3599-3604. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 138:174329 AN 2002:910661 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Carbon-coated MgO nanoparticles, with carbon forming a porous coating on the surface of MgO nanoparticles, have been prepd. by two different techniques. Resorcinol has been found to be an efficient agent for the modification of magnesium methoxide leading to carbon-coated MgO nanocrystals of small crystallite size and high surface area. Decompn. of dry magnesium methoxide under an inert gas flow proved to be another efficient and economical way to synthesize carbon-coated MgO. The carbon coating acts as a hydrophobic barrier partially protecting the core metal oxide from water adsorption and conversion to magnesium hydroxide. However, destructive adsorption reactions can still proceed on the metal oxide surface, as evidenced by the dehydrochlorination of 2-chloroethyl Et sulfide (2-CEES) and 1-chlorobutane. The overall stability of the material in the presence of water vapor is significantly improved in comparison with non-coated nanocryst. MgO.

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Micellar Effects on Hypochlorite Catalyzed Decontamination of Toxic Phosphorus Esters. Dubey, D. K.; Gupta, A. K.; Sharma, Mamta; Prabha, S.; Vaidyanathaswamy, R. Defence R and D Establishment, Gwalior, India. Langmuir (2002), 18(26), 10489-10492. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 138:94789 AN 2002:866089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At pH 8.5, the surfactant N,N,N-trimethyl-1-hexadecanaminium bromide (I) increased the pseudo-first-order rate consts. of hypochlorite-catalyzed hydrolysis of the sarin model compd. p-nitrophenyl di-Ph phosphate by 300 times and that of the toxic p-nitrophenyl iso-Pr methylphosphonate by 20 times, and the nerve agent sarin itself was completely decontaminated within 10 min at a sarin-hypochlorite ratio of 20:1 in a micellar I-hypochlorite mixt. In the absence of surfactant , it takes >70 min to detoxify sarin, even at a 10 times higher concn. of hypochlorite.

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A Comparative Study of the Adsorption of Chloro- and Non-Chloro-Containing Organophosphorus Compounds on WO3. Kanan, Sofian M.; Lu, Zhixiang; Tripp, Carl P. Laboratory for Surface Science Technology and Department of Chemistry, University of Maine, Orono, ME, USA. Journal of Physical Chemistry B (2002), 106(37), 9576-9580. CODEN: JPCBFK ISSN: 1520-6106. Journal written in English. CAN 137:253624 AN 2002:620746 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The adsorption of di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), and methyldichlorophosphate (MDCP) on monoclinic tungsten oxide (m-WO3) evacuated at various temps. was investigated using IR spectroscopy. DMMP is the most common mol. used for evaluating the performance of WO3 and other semiconducting metal oxide (SMO)-based sensors to phosphonate-based nerve agents. However, toxic nerve agents such as sarin differ from DMMP in that they contain a functional group (P-F in sarin) that can be readily hydrolyzed. It is shown that the adsorption of organophosphates that contain P-Cl groups differs from nonhalogenated simulants such as DMMP and TMP on WO3 surfaces. Specifically, the non-chlorinated simulants DMMP and TMP adsorb on the surface solely through the P:O functionality with the surface water layer as well as the Lewis and Bronsted acid sites. The relative no. of mols. bound on Lewis and Bronsted acid surface sites depends on the initial evacuation temp. of the WO3 surface. When MDCP adsorbs on WO3 through the P:O bond, it is accompanied by the hydrolysis of P-Cl groups by water vapor or the adsorbed water layer leading to addnl. phosphate-like species on the surface. The IR data suggests that a halogenated phosphate like MDCP is a better simulant mol. for studies aimed at understanding the role of water and hydrolysis in the response of metal oxide-based sensors to nerve agents.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock, Shannon D.; Till, Gerd O.; Smith, Milton G.; Ward, Peter A. Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2002), 22(4), 257-262. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 137:151235 AN 2002:596130 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. warfare agent analog, 2-chloroethyl Et sulfide, known as half-mustard gas (HMG), is less toxic and less of an environmental hazard than the full mol. and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of 125I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, the authors obsd. significant attenuation of the pulmonary injury when exptl. animals were complement- or neutrophil-depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, DMSO, dimethylthiourea, Resveratrol, and N-acetyl-L-cysteine (NAC). The last compd. showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement-mediated pathways and the generation by neutrophils of toxic oxygen species. The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber, Ellen; McGuire, Raymond. Lawrence Livermore National Laboratory, Environment Protection Department, University of California, Livermore, CA, USA. Journal of Hazardous Materials (2002), 93(3), 339-352. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 137:374412 AN 2002:558690 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A decontamination method was developed using a single reagent that is effective both against chem. warfare (CW) and biol. warfare (BW) agents. The new reagent, L-Gel, consists of an aq. soln. of a mild com. oxidizer, Oxone, together with a com. fumed silica gelling agent, Cab-O-Sil EH 5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. This reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Expts. to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Lab. and independently at 4 other locations. L-Gel was tested against all classes of chem. warfare agents and against various biol. warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biol. agents. Testing showed that L-Gel is as effective against chem. agents and biol. materials, including spores, as the best military decontaminants.

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Synthesis, Characterization, and Adsorption Studies of Nanocrystalline Aluminum Oxide and a Bimetallic Nanocrystalline Aluminum Oxide/Magnesium Oxide. Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J.; Bonevich, John. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry of Materials (2002), 14(7), 2922-2929. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 137:128541 AN 2002:469813 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of Al2O3 and Al2O3/MgO have been produced by a modified aerogel synthesis involving the corresponding aluminum tri-tert-butoxide, magnesium methoxide, toluene, methanol, ethanol, and water. The resulting oxides are in the form of powders having crystallites of .ltorsim.2 nm. These crystallites have been studied by TEM and BET methods, and were found to possess high surface areas and pore vols. (800 m2/g for Al2O3 and 790 m2/g for Al2O3/MgO, compared to 450 m2/g for MgO). As seen with other metal oxides, once they are produced as nanoparticles, their reactivity is greatly enhanced on a per unit surface area basis. This is thought to be due to morphol. differences, whereas larger crystallites have only a small percentage of reactive sites on the surface, smaller crystallites possess much higher surface concn. of such sites per unit surface area. Elemental anal., X-ray diffraction, and IR spectroscopy have been used to characterize these nanoparticles, and reactions with CCl4, SO2, and Paraoxon have demonstrated significantly enhanced reactivity and/or capacity compared with common com. forms of the oxide powders. A significant feature is that, by a cogellation synthesis, Al2O3 and MgO have been intermingled, which engenders enhanced reactivity/capacity over the pure forms of nanoscale Al2O3 or MgO toward a chem. warfare surrogate (Paraoxon) and an acid gas (SO2). This serves as an example where tailored synthesis of a nanostructured formulation can yield special benefits.

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Nanocrystalline metal oxides as destructive adsorbents for organophosphorus compounds at ambient temperatures. Rajagopalan, Shyamala; Koper, Olga; Decker, Shawn; Klabunde, Kenneth J. Nanoscale Materials, Inc., Manhattan, KS, USA. Chemistry--A European Journal (2002), 8(11), 2602-2607. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 137:191092 AN 2002:451335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nanocrystals of magnesium oxide react with organophosphorus compds. at room temp. by dissociative chemisorption, which we term "destructive adsorption". This process involves cleavage of P-O and P-F bonds (but not P-C bonds) and immobilization of the resultant mol. fragments. These ultrafine powders have unusual cryst. shapes and possess high surface concns. of reactive edge/corner and defect sites, and thereby display higher surface reactivity, normalized for surface area, than typical polycryst. material. This high surface reactivity coupled with high surface area allows their use for effective decontamination of chem. warfare agents and related toxic substances. Herein data is presented for paraoxon, diisopropylfluorophosphate (DFP), and (CH3CH2O)2P(O)CH2SC6H5 (DEPTMP). Solid-state NMR and IR spectroscopy indicate that all OR and F groups dissoc.; this leaves bound -PO4%
2C -F, and -OR groups for paraoxon, DFP, and DEPTMP, resp. For paraoxon, it was shown that one monolayer reacts. For DEPTMP, the OR groups dissoc., but not the P-CH2SC6H5 group. The nanocryst. MgO reacts much faster and in higher capacity than typical activated carbon samples, which physisorb but do not destructively adsorb these phosphorous compds.

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Routes of photocatalytic destruction of chemical warfare agent simulants. Vorontsov, Alexandre V.; Davydov, Lev; Reddy, Ettireddy P.; Lion, Claude; Savinov, Eugenii N.; Smirniotis, Panagiotis G. Boreskov Institute of Catalysis, Novosibirsk, Russia. New Journal of Chemistry (2002), 26(6), 732-744. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 137:236738 AN 2002:427511 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Selected imitants of chem. warfare agents such as di-Me methylphosphonate (DMMP), di-Et phosphoramidate (DEPA), pinacolyl methylphosphonate (PMP), and butylaminoethanethiol (BAET) were subjected to photocatalytic and sonophotocatalytic treatment in aq. suspensions of TiO2. Complete conversion of the same mass of imitants to inorg. products was obtained within 600 min for DMMP, DEPA, PMP, but required a longer time for BAET. Sonolysis accelerated photodegrdn. of DMMP. No degrdn. was obsd. without UV illumination. Final products of degrdn. were PO43-, CO2 for DMMP and PMP, PO43-, NO3- (25%), NH4+ (75%), CO2 for DEPA, and SO42-, NH4+, CO2 for BAET. The no. of main detected intermediate products increases in the order DMMP (7), DEPA (9), PMP (21), and exceeds 34 for BAET. Degrdn. of DMMP mainly proceeds through consecutive oxidn. of methoxy groups and then the Me group. Di-Me hydroxymethylphosphonate and dimethylphosphate testify to the parallel oxidn. of the Me group. Destruction of DEPA mainly starts with cleavage of the P-NH2 bond to form di-Et phosphate, which transforms further into Et phosphate. Oxidn. of  and  carbons of ethoxy groups to form ethylphosphonoamidate, hydroxyethyl ethylphosphonoamidate and other products also contributes to the destruction. Photocatalytic degrdn. of PMP mainly starts with oxidn. of the pinacolyl fragment, methylphosphonic acid and acetone being the major products. Oxidn. of BAET begins with dark dimerization to disulfide, which undergoes oxidn. of sulfur forming sulfinic and sulfonic acids as well as oxidn. of carbons to form butanal, aminobutane, etc., and cyclic products such as 2-propylthiazole. A scheme of degrdn. was proposed for DMMP and DEPA, and starting routes for PMP and BAET. Quantum efficiencies of complete mineralization calcd. as reaction rate to photon flux ratio approx. 10-3%.

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Solvent Effects on the Heterogeneous Adsorption and Reactions of (2-Chloroethyl) ethyl Sulfide on Nanocrystalline Magnesium Oxide. Narske, Richard M.; Klabunde, Kenneth J.; Fultz, Shawn. Department of Chemistry, Augustana College, Rock Island, IL, USA. Langmuir (2002), 18(12), 4819-4825. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:62952 AN 2002:360518 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The noncatalytic destructive adsorption of (2-chloroethyl) Et sulfide (2-CEES), a mimic of bis(2-chloroethyl) sulfide (HD or Mustard Gas), on nanocryst. Mg oxide (AP-MgO) was studied in several solvents from pentane to methanol. The decompn. products formed in these reactions were vinyl Et sulfide and (2-hydroxyethyl) Et sulfide. Reactions in pentane allowed the highest reaction rates, while THF and methanol gave results quite different from those for the hydrocarbon solvent. Reactions in methanol yielded (methoxyethyl) Et sulfide and not the vinyl Et sulfide and (2-hydroxyethyl) Et sulfide compds. These studies showed that the MgO-2-CEES reaction chem. is significantly affected by the solvent present and can be enhanced by choice of solvent and the addn. of small amts. of water. Interestingly, the least polar, least reactive solvent (pentane) allowed the most rapid 2-CEES reactions, indicating that the solvent simply aided material transfer to the reactive surface sites without blocking these sites. Rate changes upon water addn., coupled with FTIR studies, indicate that isolated surface OH groups are important reactive sites. These results indicate that the use of certain inert solvents greatly aids material transfer, and thereby the reaction rates of the sorbent with the toxin are significantly enhanced.

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Adsorption and Reaction of Diethyl Sulfide on Active Carbons with and without Impregnants under Static Conditions. Prasad, G. K.; Singh, Beer; Saradhi, U. V. R.; Suryanarayana, M. V. S.; Pandey, D. Defence Research and Development Establishment, Gwalior, India. Langmuir (2002), 18(11), 4300-4306. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 137:52819 AN 2002:306380 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Active carbons of different grades with and without impregnants were studied for the adsorption of di-Et sulfide (DES), the simulant of S mustard, under static conditions at 36  1. Kinetics of the adsorption were studied using linear driving force (LDF) and the Fickian diffusion model. The kinetic parameters such as equilibration time, equilibration capacity, equilibration const., diffusional exponent, and adsorbate-adsorbent interaction const. (K) were detd. The diffusional exponent (n), being <0.5, indicated a Fickian mode of diffusion of DES in the studied C. Chem. interaction also seemed to be the 2nd mechanism (although minor) involved in the DES uptake rate (the 1st being simple Fickian diffusion). The adsorbate-adsorbent interaction const. did not vary significantly indicating that probably DES chem. interacts to a small extent with the metal salts present on the surface of active C as impregnants. However, the characterization of reaction products, after extn. in CH2Cl2, using GC/MS indicated that the system CrO3/NaOH/C (C impregnated with Cr(VI) plus NaOH) only reacted with DES to give di-Et sulfone.

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An improved brain slice model of nerve agent-induced seizure activity. Wood, Sebastien J.; Tattersall, John E. H. Biomedical Sciences Department, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(Suppl. 1), S83-S86. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:290254 AN 2002:246280 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice prepn. Soman (1 M) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice prepn. is a suitable model for investigating the origin and propagation of nerve agent-induced seizures within the limbic system.

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The NMDA receptor ion channel: a site for binding of huperzine A. Gordon, Richard K.; Nigam, Savita V.; Weitz, Julie A.; Dave, Jitendra R.; Doctor, Bhupendra P.; Ved, Haresh S. Division of Biochemistry, Walter Reed Army Institute of Research, Washington, DC, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S47-S51. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:397222 AN 2002:246274 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Huperzine A (HUP-A), first isolated from the Chinese club moss Huperzia serrata, is a potent, reversible and selective inhibitor of acetylcholinesterase (AChE) over butyrylcholinesterase (BChE) (Life Sci. 54: 991-997). Because HUP-A has been shown to penetrate the blood-brain barrier, is more stable than the carbamates used as pretreatments for organophosphate poisoning (OP) and the HUP-A:AChE complex has a longer half-life than other prophylactic sequestering agents, HUP-A has been proposed as a pretreatment drug for nerve agent toxicity by protecting AChE from irreversible OP-induced phosphonylation. More recently (NeuroReport 8: 963-968), pretreatment of embryonic neuronal cultures with HUP-A reduced glutamate-induced cell death and also decreased glutamate-induced calcium mobilization. These results suggest that HUP-A might interfere with and be beneficial for excitatory amino acid overstimulation, such as seen in ischemia, where persistent elevation of internal calcium levels by activation of the N-methyl-D-aspartate (NMDA) glutamate subtype receptor is found. The authors have now investigated the interaction of HUP-A with glutamate receptors. Freshly frozen cortex or synaptic plasma membranes were used, providing 60-90% specific radioligand binding. Huperzine A (100 M) had no effect on the binding of [3H]glutamate (low- and high-affinity glutamate sites), [3H]MDL 105,519 (NMDA glycine regulatory site), [3H]ifenprodil (NMDA polyamine site) or [3H]CGS 19755 (NMDA antagonist). In contrast with these results, HUP-A non-competitively (Hill slope < 1) inhibited [3H]MK-801 and [3H]TCP binding (co-located NMDA ion channel PCP site) with pseudo Ki .apprx. 6 M. Furthermore, when neuronal cultures were pretreated with HUP-A for 45 min prior to NMDA exposure, HUP-A dose-dependently inhibited the NMDA-induced toxicity.
Although HUP-A has been implicated to interact with cholinergic receptors, it was without effect at 100 M on muscarinic (measured by inhibition of [3H]QNB or [3H]NMS binding) or nicotinic [3H]epibatidine binding) receptors; also, HUP-A did not perturb adenosine receptor binding [3H]PIA or [3H]NECA). Therefore, HUP-A most likely attenuates excitatory amino acid toxicity by blocking the NMDA ion channel and subsequent Ca2+ mobilization at or near the PCP and MK-801 ligand sites. Thus, on the one hand, HUP-A could be used as a pretreatment against OPs and it might also be a valuable therapeutic intervention in a variety of acute and chronic disorders by protecting against overstimulation of the excitatory amino acid pathway. By blocking NMDA ion channels without psychotomimetic side-effects, HUP-A may protect against diverse neurodegenerative states obsd. during ischemia or Alzheimer's disease.

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Army medical laboratory telemedicine: role of mass spectrometry in telediagnosis for chemical and biological defense. Smith, J. Richard; Shih, Ming L.; Price, Elvis O.; Platoff, Gennady E.; Schlager, John J. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S35-S41. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365032 AN 2002:246272 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An army medical field lab. presently has the capability of performing std. protocols developed at the US Army Medical Research Institute of Chem. Defense for verification of nerve agent or sulfur mustard exposure. The protocols analyze hydrolysis products of chem. warfare agents using gas chromatog./mass spectrometry. Addnl., chem. warfare agents can produce alkylated or phosphorylated proteins following human exposure that have long biol. half-lives and can be used as diagnostic biomarkers of chem. agent exposure. An anal. technique known as matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) currently is being examd. for its potential to analyze these biomarkers. The technique is capable of detecting large biomols. and modifications made to them. Its fast anal. time makes MALDI-TOF/MS technol. suitable for screening casualties from chem. or biol. attacks. Basic operation requires minimal training and the instrument has the potential to become field-portable. The limitation of the technique is that the generated data may require considerable expertise from knowledgeable personnel for consultation to ensure correct interpretation. The interaction between research scientists and field personnel in the acquisition of data and its interpretation via advanced digital telecommunication technologies can enhance rapid diagnosis and subsequently improve patient care in remote areas.

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Analysis of the degradation compounds of chemical warfare agents using liquid chromatography/mass spectrometry. Smith, J. Richard; Shih, Ming L. Pharmacology Division, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S27-S34. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365031 AN 2002:246271 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of the degrdn. products of chem. warfare (CW) agents has been a challenge to analysts. The low volatility of these compds. makes them unsuitable for direct gas chromatog. anal. without prior derivatization. Lack of a chromophore causes difficulties with classic detection methods after liq. chromatog. sepn. With the recent development of various interfaces that allow for the introduction of a liq. solvent stream into the mass spectrometer, the task of directly analyzing these compds. has become easier. For this report, the authors examd. three different liq. chromatog./mass spectrometry (LC/MS) interfaces for their suitability for the anal. of CW degrdn. compds. The interface types examd. were particle beam electron impact ionization (PBI), electrospray ionization (ESI) and atm. pressure chem. ionization (APCI). Several alkylphosphonates and thiodiglycol analogs that are produced from the degrdn. of organophosphorus nerve agents and sulfur mustard, resp., were analyzed using each of the three techniques. Electron impact ionization following gas chromatog. or particle beam introduction typically generates very reproducible, library-searchable mass spectra. Most of the CW breakdown compds. examd. using the PBI interface did not produce a mol. ion. Despite the lack of a mol. ion, the mass spectra of the various compds. contained enough different structural information from fragment ions for the pos. identification of each. The mass spectra generated using ESI are generally limited to protonated mol. ions with little or no fragmentation. For pos. identification and confirmation, tandem mass spectrometry techniques quite often must be used. Many of the compds. in this study were characterized by prominent sodiated adducts along with the protonated mol. ion. Methylphosphonic acid produced protonated dimers, trimers, etc. Although the various adduct ions can be used for addnl. confirmation of the mol. wt. of a compd., the adducts also can result in suppression of ionization of the compd.
and thus reduce sensitivity. Another "soft" ionization technique that results in abundant protonated mol. ions is APCI. The mass spectra of the breakdown compds. produced using APCI were characterized generally by either a prominent protonated mol. ion or a dehydrated form of it. In addn., a no. of structurally significant fragment ions were obsd. and their relative abundances could be adjusted by altering the APCI conditions. The data presented here indicate that each of the three techniques can be used successfully for direct liq. introduction and anal. of the non-volatile compds. produced from the degrdn. of CW agents. The mass spectra produced using each technique are quite different and could be utilized as addnl. confirmation of compd. identity.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller, Jennifer K.; Lenz, David E. Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S23-S26. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:336395 AN 2002:246270 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-mol.-wt. compds. is effected by the use of chromatog. techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the anal. To overcome those drawbacks, the authors were involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compds. such as pinacolylmethyl phosphonofluoridate (soman), which is a chem. warfare agent. Prior ests. suggested that it is necessary to be able to detect soman at a concn. below 2.5  10-7 M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The min. required assay time was 2.0-2.5 h with no loss in sensitivity. To det. the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogs were 5  10-7 M for 4-nitrophenylpinacolylmethylphosphonate, 8  10-7 M for dipinacolylmethylphosphonate, 2  10-6 M for diisopropylmethylphosphonate, 3  10-5 M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5  10-5 M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman mol., were effective inhibitors. Compds., which contained predominately arom. groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to det. its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman.

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The active site of human paraoxonase (PON1). Josse, Denis; Lockridge, Oksana; Xie, Weihua; Bartels, Cynthia F.; Schopfer, Lawrence M.; Masson, Patrick. Eppley Institute, University of Nebraska Medical Center, Omaha, NE, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S7-S11. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365079 AN 2002:246267 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ideally the authors would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman. However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4  106 M-1 min-1, and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, the authors have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw, M. D.; Hayes, T. L.; Miller, T. L.; Shannon, C. M. Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH, USA. Journal of Applied Toxicology (2001), 21(Suppl. 1), S3-S6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 136:365078 AN 2002:246266 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) iso-Bu methylphosphonothiolate-a V-type nerve agent developed by the former Soviet Union-in the environment is an important parameter in threat assessment anal. and for the detn. of use, prodn., testing and storage of this chem. warfare agent. S-(N,N-Diethylaminoethyl) iso-Bu methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same mol. formula, it is expected that their phys. and chem. properties would be different. This preliminary investigation was undertaken to det. the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compd. at approx. 1 mg ml-1 in unbuffered water at pH 7 was detd. side-by-side. The half-lives for VXA and VX were detd. to be 12.4 days and 4.78 days, resp. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chem. Weapons Convention.

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Synthesis of high surface area monoclinic WO3 particles using organic ligands and emulsion based methods. Lu, Zhixiang; Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST), University of Maine, Orono, ME, USA. Journal of Materials Chemistry (2002), 12(4), 983-989. CODEN: JMACEP ISSN: 0959-9428. Journal written in English. CAN 136:389533 AN 2002:226497 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several synthetic approaches have been used to obtain nano-sized monoclinic WO3 (m-WO3) powders. All of these methods begin with a std. preparative method where H2WO4 is first generated by passing a Na2WO4 soln. through a cation-exchange resin. It is shown that high surface area particles are produced by dripping the H2WO4 exiting from the ion-exchange column into a soln. contg. oxalate and acetate exchange ligands or alternatively, into a water-in-oil (w/o) based emulsion. In comparison to com. WO3 powders, the surface area of the m-WO3 powders were higher by factors of 10 and 20 times when prepd. in the presence of acetate/oxalate chelating agents and w/o emulsions, resp. The much higher surface areas enable IR spectroscopic identification of surface sites along with detection and monitoring of gaseous reactions and adsorbed species on the surface of this metal oxide. This is demonstrated with the adsorption of a nerve agent simulant, di-Me Me phosphonate. In general, little is known about the reactions of gaseous mols. on m-WO3 surfaces and the fabrication of high surface area m-WO3 particles will aid in gaining an understanding of the chem. processes occurring in WO3 based sensors.

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Prefiltering Strategies for Metal Oxide Based Sensors: The Use of Chemical Displacers to Selectively Dislodge Adsorbed Organophosphonates from Silica Surfaces. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2002), 18(3), 722-728. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 136:173252 AN 2002:22837 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

IR spectroscopy is used to monitor the competitive adsorption/desorption behavior of the nerve gas simulants, di-Me methylphosphonate (DMMP), tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on SiO2. All 4 compds. molecularly adsorb via hydrogen bonds (H-bonds) with the surface hydroxyl groups. The adsorption strength depends on 2 factors: the specific functional group H-bonded to the surface hydroxyl groups and the no. of such bonds per mol. The phosphonates are molecularly displaced from the SiO2 surface by chem. displacers. By judiciously selecting chem. displacers as dictated by the 2 factors, (i.e., type and no. of functional groups H-bonded to the surface silanols) it is possible to selectively and sequentially dislodge each of the 4 phosphonate compds. adsorbed on SiO2. Specifically, the relative adsorption strength of the phosphonate compds. and the chem. displacers (labeled A-C) follows the order: TCP < MDCP < A < DMMP < B < TMP < C, where A = NEt3 (TEA), B = 2-pyridyl MeCN (2-PyAN), and C= ethylenediamine (EDA). AM1 semiempirical calcns. show that the toxic nerve agent, sarin, would position itself between MDCP and DMMP in the above order. The implications of using chem. displacers in filtering applications with metal oxide based sensors are discussed.

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New -phthalimidoperoxyalkanoic acids in decontamination. Destruction of some toxic organophosphorus and organosulfur pollutants. Lion, Claude; Da Conceicao, Louis; Delmas, Gerard; Magnaud, Gilbert. Institut de Topologie et de Dynamique des Systemes, Universite de Paris 7, Paris, Fr. New Journal of Chemistry (2001), 25(9), 1182-1184. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 136:90120 AN 2001:726141 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (chem. warfare agents and/or insecticides) is of increasing importance. We report the use of -phthalimidoperoxyalkanoic acids in the destruction of paraoxon (di-Et p-nitrophenyl phosphate), a well-known insecticide, and 2-chloro-2'-phenyldiethyl sulfide (a half mustard). We show that while all the peroxy acids used in this series allow the destruction of toxic compds., the length n of the alkanoic side chain is important to the choice of the optimal industrial compd., which is 6-phthalimidoperoxyhexanoic acid (n = 5).

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig ear skin. Chilcott, R. P.; Jenner, J.; Hotchkiss, S. A. M.; Rice, P. Department of Biomedical Sciences, CBD Porton Down, Salisbury, UK. Journal of Applied Toxicology (2001), 21(4), 279-283. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:191481 AN 2001:616748 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chem. warfare agent sulfur mustard (SM). The in vitro absorption rates of SM through heat-sepd. human (15766 g cm-2 h-1) and pig-ear (411175 g cm-2 h-1) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 g cm-2 h-1, resp. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig ear epidermal membranes measured in vitro. Thus, although pig ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells contg. human epidermal membranes as a model for predicting in vivo human skin absorption.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen, J.; Riikonen, K.; Nikmo, J.; Jappinen, A.; Nieminen, K. Air Quality Research, Finnish Meteorological Institute, Helsinki, Finland. Journal of Hazardous Materials (2001), 85(3), 165-179. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 136:41716 AN 2001:572441 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Math. models were developed to evaluate the atm. dispersion of selected chem. warfare agents (CWA), including evapn. and settling of pollutant liq. droplets. The presented models and numerical results may be used to design protection and control measures against the conceivable use of CWA. The model, AERCLOUD (AERosol CLOUD), was extended to treat 2 nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodn. evolution of a 5-component aerosol mixt., consisting of 2-component droplets together with the surrounding 3-component gas. Numerical computations were performed using this model on the evapn. and settling of airborne sarin droplets in characteristic dispersion and atm. conditions. In particular, the max. radii (rM) of a totally evapg. droplet, in terms of the ambient temp. and pollutant vapor concn., were evaluated. The radii rM were .apprx.15-80 m for sarin droplets for selected ambient conditions and initial heights. Deposition fractions in terms of initial droplet size were also evaluated.

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Oxidation of triphenylarsine to triphenylarsine oxide by Trichoderma harzianum and other fungi. Hofmann, K.; Hammer, E.; Kohler, M.; Bruser, V. URST Umwelt- und Rohstoff-Technologie GmbH Greifswald, Greifswald, Germany. Chemosphere (2001), 44(4), 697-700. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 135:254254 AN 2001:483254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Arsenic resistant strains of bacteria and fungi were isolated from soil contaminated by chem. warfare agents. Until now, no metabolic products of microbial attack against the Ph residues of the model substrate triphenylarsine (TP) were found if it was incubated together with these strains in liq. culture assays. However, one of the isolated fungi, Trichoderma harzianum As 11, was found to oxidize TP to triphenylarsine oxide (TPO). The yeast Trichosporon mucoides SBUG 801 and the white-rot fungus Phanerochaete chrysosporium were also able to oxidize the As(III) in TP. In addn., P. chrysosporium transformed phenylarsine oxide (PAO) to phenylarsonic acid (PAA) under O2-atmosphere. By means of a respirometer system, the oxidn. of TP by T. harzianum As 11 was confirmed by a significantly higher consumption of oxygen in the presence of these compds. HPLC anal. of the oxidn. products TPO and PAA in the medium of the assays provided evidence for the transfer reaction of As(III) to As(V) in org. bonds. The oxidn. products TPO and PAA are more hydrophilic than TP and PAO. Therefore, it was concluded that particular fungi contribute to the mobilization of arsenic in soil contaminated by chem. warfare agents.

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Nanocrystalline metal oxides as unique chemical reagents/sorbents. Lucas, Erik; Decker, Shawn; Khaleel, Abbas; Seitz, Adam; Fultz, Shawn; Ponce, Aldo; Li, Weifeng; Carnes, Corrie; Klabunde, Kenneth J. Department of Chemistry, Kansas State University, Manhattan, KS, USA. Chemistry--A European Journal (2001), 7(12), 2505-2510. CODEN: CEUJED ISSN: 0947-6539. Journal; General Review written in English. CAN 135:216336 AN 2001:471452 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 29 refs. A new family of porous inorg. solids based on nanocryst. metal oxides is discussed. These materials, made up of 4-7 nm MgO, CaO, Al2O3, ZnO, and others, exhibit unparalleled destructive adsorption properties for acid gases, polar orgs., and even chem./biol. warfare agents. These unique sorption properties are due to nanocrystal shape, polar surfaces, and high surface areas. Free-flowing powders or consolidated pellets are effective, and pore structure can be controlled by consolidation pressures. Chem. properties can be adjusted by choice of metal oxide as well as by incorporating other oxides as monolayer films.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price, Elvis O.; Smith, J. Richard; Clark, Connie R.; Schlager, John J.; Shih, Ming L. Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S193-S197. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:206570 AN 2001:455416 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The continual threat of chem. and biol. warfare has prompted the need for unambiguous anal. methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with Hb and metallothioneins were conducted. In vitro expts. with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to det. the extent of alkylation and occurrence of HD crosslinking using the MALDI-ToF/MS technique. In a typical expt., 50 mL of 5 mM HD in acetonitrile was added to an equal vol. of 0.5 mM Hb in deionized water followed by vortexing and incubation at room temp. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES expts. These results demonstrate that MALDI-ToF/MS is a useful anal. technique to investigate the interaction of HD with biomols. and may be employed potentially as a diagnostic tool for the confirmation of exposure to chem. warfare agents.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham, John S.; Reid, Frances M.; Smith, J. Richard; Stotts, Richard R.; Tucker, F. Steven; Shumaker, Shawn M.; Niemuth, Nancy A.; Janny, Stephen J. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S161-S172. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72547 AN 2001:455411 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chem. warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clin. pathol. findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liq. on the ventral surface for 2 h, generating six 3-cm diam. full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematol. and serum chem. examns. Urine was collected in metab. cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatog./mass spectrometry. Examn. of clin. pathol. parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clin. significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 g ml-1 with a mean of 2.14 g ml-1. Thiodiglycol concns. were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml-1. Mean levels remained 10-40 ng ml-1 for the remainder of the 7-day observation period, with the highest individual concn. noted during this period of 132 ng ml-1. Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other lab. animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 wk. Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h.
Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin, M. C.; Ricketts, K.; Skvorak, J. P.; Gazaway, M.; Mitcheltree, L. W.; Casillas, R. P. Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S141-S144. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72425 AN 2001:455408 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quant. edema response as well as histopathol. and biochem. endpoints as measurements of inflammation and tissue damage following exposure to the chem. warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal sepn. This study evaluated the protective effects of three of these pharmacol. compds. when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver an s.c. dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 l of a 195 mM (0.16 mg) soln. of sulfur mustard (d. = 1.27 g ml-1; MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathol. damage (necrosis, epidermal-dermal sepn.). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant redn. in edema (24%, 26% and 22%, resp.) from the pos. control. Compared to HD-pos. controls, hydrocortisone, indomethacin and olvanil caused a significant redn. in subepidermal blisters (71%, 52% and 57%, resp.) whereas only hydrocortisone produced a significant redn. in contralateral epidermal necrosis (41%). The authors show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins, Kevin B.; Lodhi, Irfan J.; Hurley, Lauren L.; Hinshaw, Daniel B. University of Michigan Medical School, Ann Arbor, MI, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S125-S128. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72423 AN 2001:455404 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chem. warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells. Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 M HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 M buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 M HD for 5-6 h. Externally applied GSH up to a concn. of 5 mM had no toxic effect on the cells. Mild toxicity was assocd. with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examd. the hypothesis that HD may activate the nuclear transcription factor NFB by performing EMSAs with nuclear exts. of endothelial cells following exposure to 0, 250 or 500 M HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFB binding to its consensus sequence induced by 500 M HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFB, although HD-induced activation of NFB was partially suppressed by NAC at 5 h. Factor NFB is an important transcription factor for a no. of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFB activity. The NFB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction assocd. with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha, M.; Bowers, W., Jr.; Kohl, J.; DuBose, D.; Walker, J.; Alkhyyat, A.; Wong, G. US Army Research Institute of Environmental Medicine, Natick, MA, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S101-S108. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72420 AN 2001:455401 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl Et sulfide (CEES, 1-2 mg l-1 min-1) in humidified air or to humidified air alone. Tissues were evaluated histol., ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histol. showed that CEES induced the sepn. of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histol. and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1 (IL-1), prostaglandin-E2 (PGE2) and esp. IL-1 receptor antagonist (IL-1Ra) release (56334 vs. 84614 pg ml-1), but decreased interleukin-6 (IL-6, 4755 vs. 351 pg ml-1). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracellular IL-1 (371 vs. 92 pg ml-1). Extracellular IL-1Ra greatly increased (2375 vs. 24875 pg ml-1), whereas cellular levels decreased (165425 vs. 96625 pg ml-1). Extracellular (224 vs. 68 pg ml-1) and intracellular (485 vs. 233 pg ml-1) sol. interleukin-1 receptor II (sIL-1RII) decreased. Prostanglandin E2 increased (1835 vs. 2582 pg ml-1), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57000 vs. 96000 pg ml-1). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Intervention of sulfur mustard toxicity by down-regulation of cell proliferation and metabolic rates. Ray, R.; Benton, B. J.; Anderson, D. R.; Byers, S. L.; Petrali, J. P. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S87-S91. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72419 AN 2001:455399 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chem. warfare compd. HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37) first in keratinocyte growth medium (KGM) contg. BAPTA AM (10-40 M) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concn.-dependent manner with some cellular degeneration above 30 M (light microscopy). At 20-30 M, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 545%), [3H]-uridine (RNA synthesis, 296%) and [14C]-valine (protein synthesis, 122%) as well as a lower protein content per culture (303%) compared with corresponding untreated controls. However, 20-30 M BAPTA AM did not cause any demonstrable cytopathol. based on morphol. (electron microscopy) as well as biochem. (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Calmodulin, poly(ADP-ribose)polymerase and p53 are targets for modulating the effects of sulfur mustard. Rosenthal, Dean S.; Simbulan-Rosenthal, Cynthia M.; Iyer, Sudha; Smith, William J.; Ray, Radharaman; Smulson, Mark E. Department of Biochemistry and Molecular Biology, Georgetown University School of Medicine, Washington, DC, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S43-S49. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72546 AN 2001:455392 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

We describe two pathways by which the vesicating agent sulfur mustard (HD) may cause basal cell death and detachment: induction of terminal differentiation and apoptosis. Following treatment of normal human epidermal keratinocytes (NHEK) with 10 or 100 M HD, the differentiation-specific keratin pair K1/K10 was induced and the cornified envelope precursor protein, involucrin, was crosslinked by epidermal transglutaminase. Fibronectin levels were reduced in a time- and dose-dependent manner. The rapid increase in p53 and decrease in Bcl-2 levels was consistent not only with epidermal differentiation but with apoptosis as well. Further examn. of biochem. markers of apoptosis following treatment of either NHEK or human papillomavirus (HPV)-immortalized keratinocytes revealed a burst of poly(ADP-ribose) synthesis, specific cleavage of poly(ADP-ribose)polymerase (PARP) in vivo and in vitro into characteristic 89 and 24 kDa fragments, processing of caspase-3 into its active form and the formation of DNA ladders. The intracellular calcium chelator BAPTA suppressed the differentiation markers, whereas antisense oligonucleotides and chem. inhibitors specific for calmodulin blocked both markers of differentiation and apoptosis. Modulation of p53 levels utilizing retroviral constructs expressing the E6, E7 or E6 + E7 genes of HPV-16 revealed that HD-induced apoptosis was partially p53-dependent. Finally, immortalized fibroblasts derived from PARP -/- "knockout mice" were exquisitely sensitive to HD-induced apoptosis. These cells became HD resistant when wild-type PARP was stably expressed in these cells. These results indicate that HD exerts its effects via calmodulin, p53 and PARP-sensitive pathways.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser, Janet; Meier, Henry L. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S23-S30. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72413 AN 2001:455389 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chem. warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compds. in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell prepns. were exposed to various concns. of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these expts. suggest that, with increasing HD concn. and time, NHEK will fragment irresp. of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains const. over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concn.- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, resp., is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concns. that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers, S.; Anderson, D.; Brobst, D.; Cowan, F. Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (2000), 20(Suppl. 1), S19-S22. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 135:72270 AN 2001:455388 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chem. warfare compd., has been shown to deplete the NAD (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compds. To examine NAD+ levels, an automated method based on the alc. dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clin. analyzer has been developed. Automation of this assay led to smaller sample vols. and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD-exposed group. This assay appears to be useful for testing potential antivesicant compds. using both in vivo and in vitro exposure systems.

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Effects of Lewisite on cell membrane integrity and energy metabolism in human keratinocytes and SCL II cells. Kehe, K.; Flohe, S.; Krebs, G.; Kreppel, H.; Reichl, F. X.; Liebl, B.; Szinicz, L. Institute of Pharmacology and Toxicology, FAF Medical Academy, Munich, Germany. Toxicology (2001), 163(2-3), 137-144. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:133255 AN 2001:448571 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite is a highly toxic arsenic compd. which can cause skin damage. In the present study effects of Lewisite on cell membrane integrity and energy metab. as well as antidotal effects of DL-2,3-dimercaptopropanesulfonate (DMPS), and meso-2,3-dimercaptosuccinic acid (m-DMSA) were investigated in a keratinocyte derived cell line (SCL II) and primary human keratinocytes (HK). Cells were incubated in Lewisite (60 M) contg. medium for 5 min. During the following 6 h lactate dehydrogenase (LDH) activity in the supernatant, intracellular ATP content, tetrazolium redn., glucose consumption and lactate formation were measured. Glucose consumption and lactate prodn. were decreased in both cell lines after Lewisite exposure. In SCL II cells an increase of LDH activity in the supernatant, a decrease of ATP content, and an impaired ability to reduce tetrazolium was found 3 h after Lewisite exposure. In HK cultures tetrazolium redn. was significantly decreased already after 2 h, whereas LDH increase in the supernatant and ATP content decrease occurred only at 6 h after Lewisite exposure. When DMPS or m-DMSA was added directly after Lewisite exposure to SCL II cells, glucose consumption and lactate formation were restored and LDH leakage was prevented. SCL II cells might be more prone to membrane damage whereas in keratinocytes mitochondrial impairment seems to be the predominant effect of Lewisite.

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Prophylactic efficacy of amifostine and its analogues against sulphur mustard toxicity. Vijayaraghavan, R.; Kumar, P.; Joshi, U.; Raza, S. K.; Lakshmana Rao, P. V.; Malhotra, R. C.; Jaiswal, D. K. Defence Research and Development Establishment, Gwalior, India. Toxicology (2001), 163(2-3), 83-91. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 135:299804 AN 2001:448565 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The successful implication of the chem. weapons convention stimulated research with a new vigor on the destruction of the stockpiled sulfur mustard (SM). A prophylactic agent for SM will be very useful for personnel engaged in the destruction of SM and during inspections by the Organization for the Prohibition of Chem. Weapons. Due to simple method of prepn., SM can be used clandestinely during war or by terrorist groups. Inspite of research over several decades no satisfactory prophylactic or treatment regimen has evolved for SM. Amifostine an organophosphorothioate, originally developed as a radioprotector, and its analogs were evaluated as a prophylactic agent for SM. Three analogs by varying the chain length and substitution at the sulfur atom were synthesized and coded as DRDE-06, DRDE-07 and DRDE-08. LD50 of amifostine and its analogs were estd. through i.p. route. For the protection studies, amifostine and its analogs were administered i.p. in mice, 30 min before dermal (percutaneous) application of SM. The dose of the prophylactic agent was 0.2 LD50 (i.p.) and that of SM was 152 mg/kg (undiluted) equal to 19-fold LD50 of SM. Amifostine and one of its analogs, DRDE-07 gave significant protection. Further studies were carried out using amifostine and DRDE-07, and both of them significantly protected mice against SM (155 mg/kg, in PEG 300, equal to 19 LD50) when they were administered i.p. either 30 min before or simultaneously. LD50 of amifostine and DRDE-07 were also estd. through the oral route (1049 or 1248 mg/kg, resp.). Prophylactically administered amifostine and DRDE-07 (0.2 LD50, p.o.) significantly protected the mice against dermally applied SM (155 mg/kg, in PEG 300, equal to 19 LD50). The protection offered by DRDE-07 was better than that of amifostine by the oral route. DRDE-07 (0.2 LD50, p.o.) also protected significantly with respect to the decrease in body wt. and the depletion of GSH induced by SM.
DNA damage induced by SM was also significantly reduced by amifostine and DRDE-07 (0.2 LD50, p.o.). Further studies are in progress on the various pharmacol. and toxicol. properties of DRDE-07.

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Adsorption of Organic Contaminants from Water Using Tailored ACFs. Mangun, Christian L.; Yue, Zhongren; Economy, James; Maloney, Stephen; Kemme, Patricia; Cropek, Donald. Department of Materials Science and Engineering, University of Illinois, Urbana, IL, USA. Chemistry of Materials (2001), 13(7), 2356-2360. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 135:200059 AN 2001:428900 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Six activated carbon fibers (ACFs) with different chem. and phys. properties were prepd. by 1st curing a phenolic resin-coated glass fiber, followed by activation and post-treatment. Their adsorption properties were studied to evaluate the removal of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and the chem. warfare simulants diisopropylmethyl phosphonate (DIMP) and half mustard (HM) from water. The adsorption isotherms showed that ACF SL-2 (activated with CO2/H2O at 800) has a higher adsorption capacity for BTEX, DIMP, and HM than other ACFs. This suggests that the high adsorption affinity of SL-2 is related to its higher surface area, larger av. micropore size of 11.6 .ANG. (esp. effective for the adsorption of DIMP), and lower O content of the surface. The adsorption isotherms are well represented by the Freundlich equation. For BTEX, the adsorption parameters based on C coating showed that, in all cases, ACFs have a higher K value than the best available data obtained on granulated activated C. The adsorption isotherms of DIMP and HM on ACFs are presented.

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The U.S. Army reactive topical skin protectant (rTSP): challenges and successes. Hobson, Stephen T.; Lehnert, Erich K.; Braue, Ernest H., Jr. Drug Assessment Division, U. S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Materials Research Society Symposium Proceedings (2001), 628(Organic/Inorganic Hybrid Materials), CC10.8.1-CC10.8.8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 135:118044 AN 2001:354344 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In 1994, the U.S. Army initiated a research effort towards an effective material that acts both as a protective barrier and as an active destructive matrix against chem. warfare agents (CWA). We report results on our prepn. and evaluation of Reactive Topical Skin Protectants (rTSP's). These creams are composite materials consisting of a base material (TSP) and a reactive moiety. Using an established base of perfluorinated-polyether and perfluoropolyethylene solids we incorporated over 60 reactive components. Classes tested include org. polymers, org./inorg. hybrid materials, polyoxometallates (POM's), enzymes, inorg. oxides, metal alloys and small mols. We characterized these materials by light microscopy and FTIR. We detd. the efficacy of these materials against both sulfur mustard (HD) and a representative nerve agent, soman (GD), using a penetration cell model coupled to a continuous air monitor and also by in vivo testing. Composite materials with optimum reactive compds. exhibit a 94% redn. of GD vapor break-through after 20 h (from 9458 ng to 581 ng) and a 3.6 fold increase (from 162 min to 588 min) in the time 1000 ng of GD liq. penetrates through the material. Similar composite materials show a 99% redn. in HD vapor break-through after 20 h (from 4040 ng to 16 ng), a 2.3 fold increase (from 524 min to > 1200 min) in the time 1000 ng of HD vapor penetrates through the material, and an elimination of erythema vs. control in an HD vapor challenge. These results indicate that an rTSP that protects against sulfur mustard and nerve agents is within reach.

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Inhibition and promotion of combustion by organophosphorus compounds added to flames of CH4 or H2 in O2 and Ar. Korobeinichev, O. P.; Bolshova, T. A.; Shvartsberg, V. M.; Chernov, A. A. Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Siberian Branch, Novosibirsk, Russia. Combustion and Flame (2001), 125(1/2), 744-751. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 134:328437 AN 2001:309769 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Early in evaluating the destruction mechanisms of a no. of organophosphorus compds. (OPCs), such as tri-Me phosphate (TMP), di-Me methylphosphonate, and diisopropyl methylphosphonate, in connection with the disposal of chem. warfare agents, the promotion and inhibition effects of OPCs on stabilized flat flames of H2 +O2 were studied. Because OPCs were demonstrated to be more effective fire suppressants than CF3Br (Halon 1301) and due to the need for replacing the currently used Halon 1301, further investigation of the effects of the OPCs on flames is of interest. Thus a lean flame of CH4/O2/Ar (0.078/0.222/0.7) with and without TMP added, stabilized on a flat burner at 0.1 bar, was studied by mol. beam mass spectrometry (MBMS) and computer modeling using PREMIX and CHEMKIN codes. An exptl. study of this flame revealed that TMP increases the width of the reaction zone by inhibiting the flame.

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An Infrared Study of Adsorbed Organophosphonates on Silica: A Prefiltering Strategy for the Detection of Nerve Agents on Metal Oxide Sensors. Kanan, Sofian M.; Tripp, Carl P. Laboratory for Surface Science and Technology (LASST) and Department of Chemistry, University of Maine, Orono, ME, USA. Langmuir (2001), 17(7), 2213-2218. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 134:349067 AN 2001:156303 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The gas-phase adsorption of the nerve gas simulant di-Me methylphosphonate (DMMP) along with tri-Me phosphate (TMP), Me dichlorophosphate (MDCP), and trichlorophosphate (TCP) on silica have been studied using IR spectroscopy. Each phosphonate compd. adsorbs through a different no. of H-bonds of the methoxy and P:O moieties with the surface hydroxyl groups on silica. The strength of the adsorption depends on the no. and type of the H-bonds and follows the order TCP < MDCP < DMMP < TMP. TCP is completely removed from silica by evacuation at room temp., adsorbed MDCP is removed by evacuation at 150 C, DMMP requires an evacuation temp. of 300 C, and TMP is eliminated at 400 C. All phosphonate compds. molecularly desorb, and the silica returns to its original state. The differences in the reactivity of phosphonate compds. on silica from other oxides demonstrate the potential use of silica in prefiltering/preconcg. strategies for semiconductive metal oxide based sensing devices. Specifically, it is shown that silica can be used to selectively adsorb DMMP from a gas stream contg. methanol/DMMP mixts.

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Reactions of VX, GB, GD, and HD with Nanosize Al2O3. Formation of Aluminophosphonates. Wagner, George W.; Procell, Lawrence R.; O'Connor, Richard J.; Munavalli, Shekar; Carnes, Corrie L.; Kapoor, Pramesh N.; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, MD, USA. Journal of the American Chemical Society (2001), 123(8), 1636-1644. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 134:276643 AN 2001:85006 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of VX, GB, GD, and HD with nanosize Al2O3 (AP-Al2O3) have been characterized by 31P, 13C, and 27Al MAS NMR. Nerve agents VX, GB, and GD hydrolyze to yield surface-bound complexes of their corresponding nontoxic phosphonates. At sufficiently high loadings, discreet aluminophosphonate complexes, Al[OP(O)(CH3)OR]3, are generated which are identical to synthesized model compds. Thus, the reaction with phosphonic acids is not just surface-limited, but can continue to the core of alumina particles. HD mainly hydrolyzes at lower loadings to yield thiodiglycol (TG, 71%) and a minor amt. of the CH-TG sulfonium ion (12%), although some elimination of HCl is also obsd. (17%). The reactive capacity for HD is evidently exceeded at high loadings, where complete conversion to TG is hindered. However, addn. of excess water results in the quant. hydrolysis of sorbed HD to CH-TG. On AP-Al2O3 dried to remove physisorbed water, 13C CP-MAS NMR detects a surface alkoxide consistent with that of TG.

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New microemulsions for oxidative decontamination of mustard gas analogues and polymer-thickened half-mustard. Gonzaga, Ferdinand; Perez, Emile; Rico-Lattes, Isabelle; Lattes, Armand. Laboratoire des Interactions Moleculaires et Reactivite Chimique et Photochimique (CNRS UMR 5623), Universite Paul Sabatier, Toulouse, Fr. New Journal of Chemistry (2001), 25(1), 151-155. CODEN: NJCHE5 ISSN: 1144-0546. Journal written in English. CAN 134:232826 AN 2001:12053 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. decontamination of toxic compds. (warfare agents and pesticides) is of increasing importance. In this study, we report the oxidn. of mustard gas analogs in microemulsion media. A first formulation, very well-suited for stock-pile destruction, allows a fast, quant. and chemoselective oxidn. of the analogs. In a second formulation, the choice of microemulsion components used allowed us to study the oxidn. of a polymer-thickened half-mustard (2-chloroethylphenyl sulfide), opening the field of application of these microemulsions to on-site decontamination. These results confirm both the efficiency and potential of microemulsions for mustard gas destruction/decontamination in essentially aq. systems.

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Bacterial release of arsenic ions and organoarsenic compounds from soil contaminated by chemical warfare agents. Kohler, Manfred; Hofmann, Klaus; Volsgen, Fernando; Thurow, Kerstin; Koch, Andreas. URST Umwelt- und Rohstoff-Technologie GmbH, Greifswald, Germany. Chemosphere (2000), Volume Date 2001, 42(4), 425-429. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 134:60919 AN 2000:878002 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The objective was to study possible participation of microorganisms in the release of sol. arsenical compds. from organoarsenic warfare agents in contaminated soil. A no. of bacterial strains were isolated with high resistance against As5+ ions which are able to degrade the water insol. compds. triphenylarsine (TP) and triphenylarsineoxide (TPO). Release of As and sol. organoarsenic compds. from soil by the activity of autochthonic soil bacteria and a mixt. of the isolated pure cultures was demonstrated by percolation expts. with undisturbed soil samples (core drills) from the contaminated site. This release increased after addnl. of nutrients (mineral N and P, Na acetate and ethanol) and is nearly independent of the percolation temp. (5 and 22). These results show that bacteria play an important role in the release of arsenical compds. from organoarsenic warfare agent contaminated soil. This release is limited by shortage of water and, above all, of nutrients for the microorganisms in the sandy forest soil. These results are important both for the management and security and possibly for bioremediation of military waste sites contg. similar contaminations.

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The chemistry of the destruction of organophosphorus compounds in flames-IV: destruction of DIMP in a flame of H2 + O2 + Ar. Korobeinichev, O. P.; Chernov, A. A.; Bolshova, T. A. Institute of Chemical Kinetics and Combustion, Siberian Branch Russian Academy of Sciences, Novosibirsk, Russia. Combustion and Flame (2000), 123(3), 412-420. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 133:285779 AN 2000:714913 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mol. beam mass spectrometry with electron impact ionization at 11-70 eV and an electron energy spread of  0.25 eV was used to study the structure of a premixed H2/O2/Ar (0.26/0.13/0.61) flame without any additives and with 0.14% of diisopropylmethylphosphonate (DIMP), stabilized on a flat-flame burner at 62 mbar. Stable species (H2, O2, H2O), as well as atoms and radicals (H, O, OH) were monitored, including phosphorus-contg. compds.: DIMP and some intermediates of its destruction, phosphorus oxides and acids. The profiles of the mole fractions of most species, including those of atoms and free radicals were obtained. The calibration coeffs. for some species were detd. exptl., and estd. for others. Isopropylmethylphosphonate was detected as a main primary phosphorus-contg. product of the destruction of DIMP. It has been shown that bimol. reactions with hydroxyl radicals and hydrogen atoms, rather than a unimol. decompn., provide the crucial initial steps in the destruction of DIMP. A detailed mechanism for the destruction of DIMP in H2/O2/Ar flames is suggested.

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Cytotoxicity of the MEIC reference chemicals in rat hepatoma-derived Fa32 cells. Dierickx, P. J. Laboratorium Biochemische Toxikologie, Afdeling Toxikologie, Instituut voor Volksgezondheid, Brussels, Belg. Toxicology (2000), 150(1-3), 159-169. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 134:1437 AN 2000:660792 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The cytotoxicity of the MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) ref. chems. was investigated in rat hepatoma-derived Fa32 cells. The total protein content was measured as an endpoint after exposure times of 30 min and 24 h, both in normal and glutathione-depleted cells. The neutral red uptake inhibition and the MTT conversion were also measured after 30 min. On av., the cytotoxicity was higher in glutathione-depleted cells when compared to normal cells, and was lower after 30 min than after 24 h. Evidence was obtained for lysosomal attack (of five chems.) or mitochondrial dysfunction (of six chems.) as the primary intoxication mechanism. Malathion and mercuric chloride belong to both series of chems. Good to excellent correlations were obsd. when the 50% inhibitory concns. of the six different in vitro assays were compared. When the six in vitro assays in Fa32 cells were compared with the human toxicity, the correlation coeff. was almost always identical to that obtained previously in human hepatoma-derived Hep G2 cells. The latter was the best acute in vitro assay for the prediction of human toxicity within the MEIC study. Altogether the results integrate very well with the basal cytotoxicity concept (B. Ekwall; 1995).

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The role of time in toxicology or Haber's ct product. Rozman, K. K. Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, KS, USA. Toxicology (2000), 149(1), 35-42. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 133:306404 AN 2000:589244 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It happened exactly 100 yr ago that Warren established for the first time a quant. link between dose and time while studying the toxicity of sodium chloride in Daphnia magna (Straus). During this century many toxicologists in different contexts returned to this idea, which has become known as Haber's rule of inhalation toxicol. Most attempts to explore this relationship ended in frustration because of the supposed occurrence of exceptions. Thus, toxicologists concd. on the quant. relationship between dose and effect under mostly isotemporal conditions while time took a back seat and was assigned such arbitrary, semiquant. designations as acute, subacute, subchronic and chronic. Time itself as a quantifiable variable of toxicity was seldom studied and when it was studied, it was often not under isodosic (steady state) conditions as required by theory. A recent anal. of toxicol. time indicated the impact of three independent time scales (toxicokinetic, toxicodynamic, exposure frequency/duration) in toxicol. studies, which interact with dose and effect to yield the enormous complexity known to every toxicologist. Based on prototypical examples when toxicokinetic (dioxins), toxicodynamic (nitrosamines, benzene) or exposure frequency (methylene chloride, chloroacetic acid, HgCl2, CdCl2, etc.) represent the crit. time scale, the general validity of the ct=k concept will be discussed as a starting point for a theory of toxicol. As endpoints of toxicity, (delayed) acute toxicity, blood dyscrasias and cancer will be used to illustrate the crit. conditions needed to demonstrate the validity of this theory.

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Detection of Fluorophosphonate Chemical Warfare Agents by Catalytic Hydrolysis with a Porous Silicon Interferometer. Sohn, Honglae; Letant, Sonia; Sailor, Michael J.; Trogler, William C. Department of Chemistry and Biochemistry, University of California at San Diego, CA, USA. Journal of the American Chemical Society (2000), 122(22), 5399-5400. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 133:100551 AN 2000:335868 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The detection of a fluorophosphonate nerve chem. warfare agent can be achieved with an oxidized porous silicon interferometer film contg. a Cu(II) hydrolysis catalyst and surfactant (CTAB). Hydrolysis of the nerve agent produces HF gas, which removes the silicon oxide as SiF4(g) and induces both a blue-shift and a decrease in intensity of the Fabry-Perot fringes. Significant changes in these 2 parameters are detected after 5 min of DFP vapor (800 ppm) exposure.

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Reactions of VX, GD, and HD with Nanosize CaO: Autocatalytic Dehydrohalogenation of HD. Wagner, George W.; Koper, Olga B.; Lucas, Erik; Decker, Shawn; Klabunde, Kenneth J. Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, MD, USA. Journal of Physical Chemistry B (2000), 104(21), 5118-5123. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 133:30783 AN 2000:281288 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Room-temp. reactions of the chem. warfare agents VX, GD, and HD with nanosize CaO (AP-CaO), and HD with com. CaO were studied using solid-state MAS NMR. VX and GD hydrolyze to yield surface-bound complexes of nontoxic Et methylphosphonate and pinacolyl methylphosphonate, resp. The kinetics were characterized by an initial fast reaction followed by a slower, diffusion-limited reaction. Similar behavior is obsd. for HD on either dried or hydrated AP-CaO and CaO. On partially hydrated AP-CaO (but not CaO), a rather fast steady-state elimination of HCl occurs after an induction period. This behavior is attributed to acid-catalyzed surface reconstruction (to regenerate fresh surface) and the formation of CaCl2, which is known to be more reactive than CaO. The product distribution for HD is .apprx.80% divinyl sulfide and 20% thiodiglycol and/or sulfonium ions, which apparently reside as surface alkoxides. Such kinetic behavior was not evident for the common mustard simulant 2-chloroethyl Et sulfide (CEES) on partially hydrated AP-CaO, which exhibited only the typical fast/diffusion-limited reaction.

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Design and synthesis of an ,-difluorophosphinate hapten for antibody-catalyzed hydrolysis of organophosphorus nerve agents. Vayron, Philippe; Renard, Pierre-Yves; Valleix, Alain; Mioskowski, Charles. CEA, Service des Molecules Marquees, CE-Saclay, Gif sur Yvette, Fr. Chemistry--A European Journal (2000), 6(6), 1050-1063. CODEN: CEUJED ISSN: 0947-6539. Journal written in English. CAN 133:13524 AN 2000:214064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

In a new approach to the safe neutralization of organophosphorus chem. weapons, we designed a hapten to elicit catalytic antibodies with phosphatase activity. Here we report the synthesis of this ,-difluorophosphinate hapten 6. Various methods for the introduction of the key ,-difluoromethyl feature into the phosphinate hapten are discussed. The best results were obtained with the electrophilic gem-difluorinating agent N-fluorobenzenesulfonimide.

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Equilibria, Kinetics, and Mechanism in the Bicarbonate Activation of Hydrogen Peroxide: Oxidation of Sulfides by Peroxymonocarbonate. Richardson, David E.; Yao, Huirong; Frank, Karen M.; Bennett, Deon A. Center for Catalysis Department of Chemistry, University of Florida, Gainesville, FL, USA. Journal of the American Chemical Society (2000), 122(8), 1729-1739. CODEN: JACSAT ISSN: 0002-7863. Journal written in English. CAN 132:222157 AN 2000:94955 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Bicarbonate ion is an effective activator for hydrogen peroxide in the oxidn. of sulfides. Kinetic and spectroscopic results support the formation of peroxymonocarbonate ion (HCO4-) as the oxidant in the catalytic reactions. The reaction of hydrogen peroxide and bicarbonate to form HCO4- occurs rapidly at 25 (t1/2  300 s) near neutral pH in aq. soln. and alc./water mixts., and an equil. anal. of the reaction by 13C NMR leads to an est. of the electrode potential for the HCO4-/HCO3- couple (1.8 V vs NHE). Soly. of the bicarbonate catalyst is enhanced by the use of NH4HCO3 rather than by the use of group 1 salts, which tend to have lower soly. in the mixed solvents and can lead to phase sepn. Rate laws and mechanistic analyses are presented for the oxidn. of Et Ph sulfide and related sulfides. The second-order rate consts. for sulfide oxidns. by HCO4- are .apprx.300-fold greater than those for H2O2, and this increase is consistent with expectations based on a Bronsted anal. of the kinetics for other heterolytic peroxide oxidns. At high concns. of H2O2, a pathway that is second order in H2O2 is significant, and this path is interpreted as a general acid catalysis by H2O2 of carbonate displacement accompanying substrate attack at the electrophilic oxygen of HCO4-. Increasing water content up to 80% in the solvent increases the rate of oxidn. The BAP (bicarbonate-activated peroxide) oxidn. system is a simple, inexpensive, and relatively nontoxic alternative to other oxidants and peroxyacids, and it can be used in a variety of oxidns. where a mild, neutral pH oxidant is required. Variation of bicarbonate source and the cosolvent can allow optimization of substrate soly. and oxidn. rates for applications such as org. synthesis and chem. warfare agent decontamination.

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Synthesis and Characterization of a Functionalized Double-Chain Surfactant and Its Cleavage of O-Methyl S-Benzyl Phenylphosphonothioate. Jaeger, David A.; Li, Bei. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (2000), 16(1), 5-10. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 132:24141 AN 1999:379097 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant 2-hydrazino-N-methyl-N,N-didodecyl-2-oxoethanaminium bromide (I) was synthesized, and its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry. In a pH 9.0 borate buffer at 25, vesicular I and O-Me S-benzyl phenylphosphonothioate (II), a simulant for the chem. warfare agent VX [O-Et S-(2-N,N-diisopropylamino)ethyl methylphosphonothioate] reacted to give anion S-benzyl phenylphosphonothioate (III) and 3 cations (2-(2-N-methylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, 2-(2-N,N-dimethylhydrazino)-N'-methyl-N',N'-didodecyl-2-oxoethanaminium, and 2-[1-hydroxy-2-(N-methyl-N,N-didodecylammonio)ethylidene]-N',N',N'-trimethylhydrazinium, resp.) by SN2 substitution on the Me group of II. This reaction was accompanied by the pptn. of anion III with surfactant cations, which resulted in wounding/destruction of the vesicles. The combination of vesicle damage and reaction of II suggests the potential of vesicular systems for simultaneous signaling and decontamination of chem. agents. Ester II hydrolyzed in 0.10 M NaOH at 25 to give anions III and O-Me phenylphosphonothioate in a 38:62 ratio, resp.

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Reactivation kinetics of acetylcholinesterase from different species inhibited by highly toxic organophosphates. Worek F; Reiter G; Eyer P; Szinicz L Sanitatsakademie der Bundeswehr, Institut fur Pharmakologie und Toxikologie, Neuherbergstrasse 11, 80937 Munich, Germany. fworek@lrz.uni-muenchen.de Archives of toxicology (2002 Sep), 76(9), 523-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242610 AN 2002479746 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Standard treatment of poisoning by organophosphates (OP) includes the administration of an antimuscarinic agent, e.g. atropine, and of an acetylcholinesterase (AChE) reactivator (oxime). The presently available oximes, obidoxime and pralidoxime (2-PAM), are considered to be insufficient for highly toxic OPs, e.g. sarin. In the past decades numerous oximes were prepared and tested for their efficacy in OP poisoning, mostly in animal experiments. However, data indicate that the reactivating potency of oximes may be different in humans and animal species, which may hamper the extrapolation of animal data to humans and may pose a problem in the drug licensing of new compounds. In order to provide data for a better evaluation of the reactivating potency of oximes, experiments were undertaken to determine the reactivation rate constants of several oximes with human, rabbit, rat and guinea-pig AChE inhibited by the OPs sarin, cyclosarin and VX. The results show marked differences among the species, depending on the inhibitor and on the oxime, and indicate that the findings from animal experiments need careful evaluation before extrapolating these data to humans.

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Skin toxicokinetics of mustard gas in the guinea pig: effect of hypochlorite and safety aspects. Wormser Uri; Brodsky Berta; Sintov Amnon Faculty of Sciences,The Hebrew University, Edmond Safra Campus, Givat Ram, Jerusalem, Israel. wormser@cc.huji.ac.il Archives of toxicology (2002 Sep), 76(9), 517-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12242609 AN 2002479745 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (SM, mustard gas) is a chemical warfare vesicant that rapidly penetrates the skin due to its hydrophobicity. This study measured the rate of SM disappearance from the skin after topical application of the vesicant. In both fur-covered and hairless animals, the remaining toxicant levels measured 60 min after exposure to undiluted SM were 0.6% and 0.3%, respectively, of the initially applied SM amount. However, SM concentration reached 0.4% of the initial dose 3 h following exposure in female fur-covered guinea pigs. SM quantities extracted from skin of male fur-covered and hairless guinea pigs immediately after 16 min of exposure to SM vapor were 12.2 and 21.8 microg, respectively; levels declined to 1.6 and 1.7 microg at 30 and 15 min following termination of exposure of male fur-covered and hairless guinea pigs, respectively. Three swabbing treatments of undiluted SM-exposed skin with gauze pads soaked in 0.5% hypochlorite caused 68% reduction in skin SM content. Similar findings were obtained when hypochlorite was replaced by water (64% reduction). SM content in the gauze pads was 59, 38 and 25 microg, respectively, for the first, second and third decontamination processes with water. No SM was detected in the gauze pads soaked with hypochlorite. In vitro studies showed that incubation of SM with 0.5% hypochlorite at a ratio of 10:1 (v/v) did not cause SM inactivation, whereas 4% hypochlorite reduced SM levels by 17%. However, at a decontaminant:SM ratio of 1000:1, 0.5% and 4% hypochlorite reduced SM levels by 92% and 99%, respectively. These findings are important for health authorities and regulatory agencies in planning precautionary steps to be taken in case of emergency and in routine laboratory work.

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Protection from half-mustard-gas-induced acute lung injury in the rat. McClintock Shannon D; Till Gerd O; Smith Milton G; Ward Peter A Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602, USA Journal of applied toxicology : JAT (2002 Jul-Aug), 22(4), 257-62. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12210543 AN 2002449749 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The chemical warfare agent analog, 2-chloroethyl ethyl sulfide, known as 'half-mustard gas' (HMG), is less toxic and less of an environmental hazard than the full molecule and has been shown to produce an acute lung injury in rats when instilled via intrapulmonary injection. This injury is characterized by massive, localized hemorrhage and edema into the alveolar compartment and can be quantitated by measuring extravasation of (125)I-bovine serum albumin into the extravascular compartment. Employing this rat model of HMG-induced lung injury, we observed significant attenuation of the pulmonary injury when experimental animals were complement or neutrophil depleted prior to HMG challenge. Significant protection also was provided by the use of antioxidants such as catalase, dimethyl sulfoxide, dimethyl thiourea, resveratrol and N-acetyl-L-cysteine (NAC). The last compound showed protection from lung injury as high as 70% and was still effective even when given up to 90 min after exposure of the lungs to HMG. These data suggest that acute lung injury caused by exposure to HMG may be related partially to complement mediated pathways and the generation by neutrophils of toxic oxygen species The data indicate that NAC is an effective antidote against HMG-induced acute lung injury in the rat. Copyright 2002 John Wiley & Sons, Ltd.

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Oxidative decontamination of chemical and biological warfare agents using L-Gel. Raber Ellen; McGuire Raymond Environment Protection Department, Lawrence Livermore National Laboratory, University of California, P.O. Box 808, L-626, Livermore, CA 94551, USA Journal of hazardous materials (2002 Aug 5), 93(3), 339-52. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12137994 AN 2002389537 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A decontamination method has been developed using a single reagent that is effective both against chemical warfare (CW) and biological warfare (BW) agents. The new reagent, "L-Gel", consists of an aqueous solution of a mild commercial oxidizer, Oxone, together with a commercial fumed silica gelling agent, Cab-O-Sil EH-5. L-Gel is non-toxic, environmentally friendly, relatively non-corrosive, maximizes contact time because of its thixotropic nature, clings to walls and ceilings, and does not harm carpets or painted surfaces. The new reagent also addresses the most demanding requirements for decontamination in the civilian sector, including availability, low maintenance, ease of application and deployment by a variety of dispersal mechanisms, minimal training and acceptable expense. Experiments to test the effectiveness of L-Gel were conducted at Lawrence Livermore National Laboratory and independently at four other locations. L-Gel was tested against all classes of chemical warfare agents and against various biological warfare agent surrogates, including spore-forming bacteria and non-virulent strains of real biological agents. Testing showed that L-Gel is as effective against chemical agents and biological materials, including spores, as the best military decontaminants.

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Adamantyl tenocyclidines--adjuvant therapy in poisoning with organophosphorus compounds and carbamates. Erratum in: Arch Toxicol 2002 Sep;76(9):552 Skare Danko; Radic Bozica; Lucic Ana; Peraica Maja; Domijan Ana-Marija; Milkovic-Kraus Sanja; Bradamante Vlasta; Jukic Ivan Institute Ruder Boskovic, Bijenicka c. 54, 10000 Zagreb, Croatia. skare@rudjer.irb.hr Archives of toxicology (2002 Apr), 76(3), 173-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11967623 AN 2002328057 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The objective of this study was to evaluate the efficacy of thienyl phencyclidine (tenocyclidine, TCP) and its newly synthesized adamantyl derivatives containing piperidine (TAPIP), pyrolidine (TAPIR) and morpholine (TAMORF) groups, which were tested with or without standard therapy in mice poisoned with organophosphates (OPs) and carbamates. These compounds with potential activity at the N-methyl- D-aspartate and muscarinic receptors showed low acute toxicity, having LD50 values varying from 106.00 mg/kg (TCP) to >504.00 mg/kg body weight (TAMORF). TCP and its adamantyl derivatives were administered intraperitoneally (2.5 mg/kg body weight) together with atropine (10.0 mg/kg body weight) and with or without 1/4 LD50 of the oxime HI-6. Each compound administered with atropine had a therapeutic effect against poisoning with carbamates propoxur, aldicarb and Ro 02-0683 (protective ratio of tenocyclidines was from 3.99 LD50 of aldicarb to >16.00 LD50 for propoxur). However, the efficacy of those compounds in combination with atropine was lower against poisoning with the OP insecticide dichlorvos (DDVP) and chemical warfare agents soman and tabun. In soman-poisoned mice, the best therapeutic effects were obtained with the combination of HI-6 plus atropine and test compounds, with protective ratios being from 5.40 to 7.12 LD50 of soman. The results suggest that TCP and adamantyl tenocyclidines could be used in combination with atropine as antidotes in carbamate poisoning and as adjuvant therapy to HI-6 and atropine in soman poisoning.

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Site-specific percutaneous absorption of methyl salicylate and VX in domestic swine. Duncan E J Scott; Brown April; Lundy Paul; Sawyer Thomas W; Hamilton Murray; Hill Ira; Conley John D Chemical Biological Defence Section, Defence Research Establishment, Suffield, PO Box 4000, Station Main, Medicine Hat, Alberta, Canada T1A 8K6 Journal of applied toxicology : JAT (2002 May-Jun), 22(3), 141-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 12015792 AN 2002313565 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The site specificity of the percutaneous absorption of methyl salicylate (MeS) and the organophosphate nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothioate) was examined in anaesthetized domestic swine that were fully instrumented for physiological endpoints. Four different anatomical sites (ear, perineum, inguinal crease and epigastrium) were exposed to the MeS and the serum levels were measured over a 6-h time period. The dose absorbed at the ear region was 11 microg cm(-2) with an initial flux of 0.063 microg cm(-2)min(-1), whereas at the epigastrium region the dose absorbed was 3 microg cm(-2) with an initial flux of 0.025 microg cm(-2)min(-1). For this reason further studies were carried out with VX on the ear and the epigastrium only. In animals treated with agent on the epigastrium, blood cholinesterase (ChE) activity began to drop 90 min after application and continued to decline at a constant rate for the remainder of the experiment to ca. 25% of awake control activity. At this time there were negligible signs of poisoning and the medical prognosis was judged to be good. In contrast, the ChE activity in animals receiving VX on the ear decreased to 25% of awake control values within 45 min and levelled out at 5-6% by 120 min. Clinical signs of VX poisoning paralleled the ChE inhibition, progressing in severity over the duration of the exposure. It was judged that these animals would not survive. The dramatic site dependence of agent absorption leading to vastly different toxicological endpoints demonstrated in this model system has important ramifications for chemical protective suit development, threat assessment, medical countermeasures and contamination control protocols. Copyright 2002 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.

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An improved brain slice model of nerve agent-induced seizure activity. Wood S J; Tattersall J E Biomedical Sciences Department, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S83-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920926 AN 2002191151 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A brain slice model was developed to investigate the mechanisms of seizure activity induced by soman and the effectiveness of potential anticonvulsant drugs. Unlike previously reported slice studies with nerve agents, this model contains the entorhinal cortex as well as the hippocampus. This allows the study of the spread of seizure discharges within the limbic system and the development of prolonged, sustained discharges that are rarely seen in the simple hippocampal slice preparation. Soman (1 microM) induced a second population spike in the evoked field potential in the CA1 or CA3 region within 15-20 min. In almost all the slices tested, this developed into spontaneous seizure activity within 30-40 min. As well as interictal bursts, many slices also showed longer periods of high-frequency bursting analogous to ictal seizure activity that originated in the entorhinal cortex. This activity appeared similar to that induced by the muscarinic agonist pilocarpine. Both the second population spike and the spontaneous discharges could be blocked by diazepam and by AMPA/kainate antagonists, but not by the NMDA antagonists AP5 and MK-801. This study confirms that the combined hippocampal-entorhinal cortex slice preparation is a suitable model for investigating the origin and propagation of nerve-agent-induced seizures within the limbic system. Copyright 2001 John Wiley & Sons, Ltd.

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Cardiopulmonary effects of HI-6 treatment in soman intoxication. Goransson-Nyberg A; Cassel G Division of NBC Defence, Department of Medical Counter Measures, Swedish Defence Research Agency, SE-90182 Umea, Sweden Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S79-81. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920925 AN 2002191150 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The cardiopulmonary effects of HI-6, together with atropine and soman, were studied in the rat. HI-6 is an effective antidote in acute poisoning with the nerve agent soman. The therapeutic efficiency of HI-6 is still unclear and cannot be explained entirely by the HI-6 reactivating ability of acetylcholinesterase (AChE). Other non-cholinergic factors must be involved. One possible detoxifying process might be an effect of HI-6 on the blood flow to sensitive organs. The purpose of the present study was to investigate 1) whether soman per se induces changes in regional blood flow and 2) whether the blood flow to different organs is affected when HI-6 (50 mg x kg(-1) i.m.) and atropine (10 mg x kg(-1) i.m.) are given either before or immediately after soman intoxication (90 microg x kg(-1) s.c.). For regional blood flow determinations the microsphere method was used with male Wistar rats weighing 300-400 g. The rats were anaesthetised and breathed spontaneously during the experiment. Three different blood flow measurements were made in the same animal and concomitant physiological parameters such as mean arterial blood pressure and respiratory rate were recorded. The blood AChE activity was followed throughout the experiment. Our results show that when HI-6 is given after intoxication with soman, dramatic changes in blood flow occur with a significant decrease in both respiratory rate and blood AChE activity. If HI-6 is given prior to the intoxication, however, all rats are unaffected and none of the parameters measured are changed. Copyright 2001 John Wiley & Sons, Ltd.

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Prophylaxis against organophosphate poisoning by sustained release of scopolamine and physostigmine. Meshulam Y; Cohen G; Chapman S; Alkalai D; Levy A Department of Pharmacology, Israel Institute for Biological Research (IIBR), PO Box 19, 70450 Ness-Ziona, Israel Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S75-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920924 AN 2002191149 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Protection efficacy of continuous prophylactic administration of physostigmine and scopolamine against sarin-induced toxicity was evaluated previously in guinea pigs. The present study in large animals used Beagle dogs, that serve as an animal model with cholinergic sensitivity similar to that of humans. Pretreatment with physostigmine salicylate and scopolamine hydrochloride at dose rates of 2.5 and 1 microg x kg(-1) x h(-1), respectively, was administered via Alzet mini-osmotic pumps. At the time of exposure, the physostigmine salicylate concentration in plasma was 0.7 ng x ml(-1) and the scopolamine hydrochloride concentration was ca. 0.2 ng x ml(-1), both of which are levels known to be well tolerated in humans. Whole-blood cholinesterase inhibition was 15-20%. This regimen conferred full protection against 2.5 x LD50 i.v. of sarin. Albeit the high-dose exposure, cholinergic toxicity symptoms were mild with no convulsions. About 11-14 min following poisoning the treated animals started to walk and 15-20 min following exposure full recovery was observed and the dogs behaved normally. With higher dose rates of physostigmine salicylate and scopolamine hydrochloride, at plasma concentrations of 2.1 and 0.6 ng x ml(-1), respectively, treated dogs regained normal posture 6-10 min after exposure. Copyright 2001 John Wiley & Sons, Ltd.

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Intramuscular diazepam pharmacokinetics in soman-exposed guinea pigs. Capacio B R; Whalley C E; Byers C E; McDonough J H Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S67-74. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920923 AN 2002191148 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Intramuscular (i.m.) diazepam is included by the US military as an anticonvulsant in the standard therapeutic regimen for organophosphorus nerve agent intoxication. In this study we investigated the pharmacokinetics of diazepam after i.m. administration while monitoring pharmacodynamic (electroencephalogram, EEG) data in soman-exposed guinea pigs. Prior to experiments the animals were surgically implanted with EEG leads to monitor seizure activity. For the study, animals were administered pyridostigmine (0.026 mg x kg(-1) i.m.) 30 min prior to soman (56 microg x kg(-1), 2 x LD50; subcutaneously, s.c.), which was followed in 1 min by atropine sulfate (2 mg x kg(-1) i.m.) and pralidoxime chloride (25 mg x kg(-1) i.m.). All animals receiving this regimen developed seizure activity. Diazepam (10 mg x kg(-1) i.m.) was administered 5 min after onset of seizure activity. Based on EEG data, animals were categorized as either seizure terminated or not terminated at 30 min after diazepam. Serial blood samples were obtained from each animal. Diazepam (10 mg x kg(-1) i.m.) terminated seizure activity in 52% of the animals within 30 min. The pharmacokinetics were characterized by a one-compartment model with first-order absorption and elimination. The maximum plasma concentrations (Cmax) were 991 and 839 ng x ml(-1) for seizure terminated and not terminated, respectively. Mean plasma concentrations of diazepam were significantly different (P < 0.05) for seizure terminated vs not terminated groups at 30 min. The plasma Cmax in seizure-terminated animals in this study is similar to the minimum range of plasma diazepam (200-800 ng x ml(-1)) reported to suppress seizure activity in humans. It has been reported in an earlier study that the minimum effective i.m. dose (0.1 mg x kg(-1)) required to prevent soman-induced convulsions in Rhesus monkeys produces a mean Cmax of 50 ng x ml(-1) for diazepam.
The data from our current study suggest that a higher dose (and corresponding Cmax) is necessary to terminate ongoing seizure activity. Copyright 2001 John Wiley & Sons, Ltd.

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Combination anticonvulsant treatment of soman-induced seizures. Koplovitz I; Schulz S; Shutz M; Railer R; Macalalag R; Schons M; McDonough J Drug Assessment Division, US Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010, USA. Koplovitz@asia.apgea.army.mil Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S53-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920921 AN 2002191147 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures. Copyright 2001 John Wiley & Sons, Ltd.

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Soman-induced seizures: limbic activity, oxidative stress and neuroprotective proteins. Pazdernik T L; Emerson M R; Cross R; Nelson S R; Samson F E Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City, KS 66160, USA. tpazdern@kumc.edu Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S87-94. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920927 AN 2002185330 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman, a potent acetylcholinesterase inhibitor, induces status epilepticus in rats followed by conspicuous neuropathology, most prominent in piriform cortex and the CA3 region of the hippocampus. Cholinergic seizures originate in striatal-nigral pathways and with fast-acting agents (soman) rapidly spread to limbic related areas and finally culminate in a full-blown status epilepticus. This leads to neurochemical changes, some of which may be neuroprotective whereas others may cause brain damage. Pretreatment with lithium sensitizes the brain to cholinergic seizures. Likewise, other agents that increase limbic hyperactivity may sensitize the brain to cholinergic agents. The hyperactivity associated with the seizure state leads to an increase in intracellular calcium, cellular edema and metal delocalization producing an oxidative stress. These changes induce the synthesis of stress-related proteins such as heat shock proteins, metallothioneins and heme oxygenases. We show that soman-induced seizures cause a depletion in tissue glutathione and an increase in tissue 'catalytic' iron, metallothioneins and heme oxygenase-1. The oxidative stress induces the synthesis of stress-related proteins, which are indicators of 'stress' and possibly provide neuroprotection. These findings suggest that delocalization of iron may catalyze Fenton-like reactions, causing progressive cellular damage via free radical products. Copyright 2001 John Wiley & Sons, Ltd.

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Beneficial effects of TCP on soman intoxication in guinea pigs: seizures, brain damage and learning behaviour. de Groot D M; Bierman E P; Bruijnzeel P L; Carpentier P; Kulig B M; Lallement G; Melchers B P; Philippens I H; van Huygevoort A H TNO Nutrition and Food Research, PO Box 360, 3700 AJ Zeist, The Netherlands Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S57-65. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920922 AN 2002185328 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Poisoning with the potent nerve agent soman produces a cascade of central nervous system (CNS) effects characterized by severe convulsions and eventually death. In animals that survive a soman intoxication, lesions in the amygdala, piriform cortex, hippocampus and thalamus can be observed. In order to examine the mechanisms involved in the effects of soman and to evaluate possible curative interventions, a series of behavioural, electrophysiological and neuropathological experiments were carried out in the guinea pig using the NMDA antagonist N-[1-(2-thienyl)cyclohexyl] piperidine (TCP) in conjunction with atropine and pyridostigmine. The NMDA antagonist TCP appeared to be very effective in the treatment of casualties who suffered from soman-induced seizures for 30 min: (i)Seizures were arrested within minutes after the TCP injection, confirmed by quantitative electroencephalogram (EEG), after fast Fourier analysis. Three hours after TCP the quantitative EEGs were completely normal in all frequency bands and remained normal during the entire 3-week intoxication period. The power shift to the lower (delta) frequency bands, indicative for neuropathology and found in control animals intoxicated only by soman, was not observed in the soman-TCP group. (ii)The gross neuropathology found in soman control animals within 48 h after soman was prevented in soman-TCP animals and was still absent in 3-week survivors. Instead, ultrastructural changes were observed, indicative of defense mechanisms of the cell against toxic circumstances. (iii)Twenty-four hours after soman, soman-TCP animals were able to perform in the shuttle box and Morris water maze. The beneficial effects of TCP on the performance in these tests during the 3-week intoxication period were very impressive, notwithstanding (minor) deficits in memory and learning. (iv)The increase in excitability after TCP was confirmed by an increase in the acoustic startle response.
Taken together, these results confirmed the involvement of NMDA receptors in the maintenance of soman-induced seizures and the development of brain damage. They underline the current hypothesis that cholinergic mechanisms are responsible for eliciting seizure activity after soman and that, most likely, the subsequent recruitment of other excitatory neurotransmitters and loss of inhibitory control are responsible for the maintenance of seizures and the development of subsequent brain damage. Copyright 2001 John Wiley & Sons, Ltd.

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Comparison of the hydrolytic stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate with VX in dilute solution. Crenshaw M D; Hayes T L; Miller T L; Shannon C M Medical Research and Evaluation Facility, Battelle Memorial Institute, JM-3, Columbus, OH 43201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S3-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920912 AN 2002185325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The stability of S-(N,N-diethylaminoethyl) isobutyl methylphosphonothiolate--a V-type nerve agent developed by the former Soviet Union--in the environment is an important parameter in threat assessment analysis and for the determination of use, production, testing and storage of this chemical warfare agent. S-(N,N-Diethylaminoethyl) isobutyl methylphosphonothiolate is a structural isomer of the nerve agent VX developed by the USA and the UK and will be referred to as VXA (VX analog) in this presentation. Because VXA and VX differ structurally, even though they do have the same molecular formula, it is expected that their physical and chemical properties would be different. This preliminary investigation was undertaken to determine the relative hydrolysis rate of VXA compared with VX. The hydrolysis of each compound at approximately 1 mg x ml(-1) in unbuffered water at pH 7 was determined side-by-side. The half-lives for VXA and VX were determined to be 12.4 days and 4.78 days, respectively. Agent VXA hydrolyzed 2.6 times more slowly than VX, and each agent followed second-order hydrolysis kinetics. These results imply that VXA is more persistent in the environment and therefore poses a greater threat. These results also imply that VXA is more likely to be detected, if present, during an inspection in support of the Chemical Weapons Convention. Copyright 2001 John Wiley & Sons, Ltd.

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Development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds. Miller J K; Lenz D E Department of OCBS, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD 21201, USA Journal of applied toxicology : JAT (2001 Dec), 21 Suppl 1 S23-6. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11920916 AN 2002185323 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Currently, diagnosis of exposure to toxic low-molecular-weight compounds is effected by the use of chromatographic techniques. Such an approach is limited by the need for expensive equipment and sample clean-up before carrying out the analysis. To overcome those drawbacks, we have been involved in the development of an immunoassay for diagnosis of exposure to toxic organophosphorus compounds such as pinacolylmethyl phosphonofluoridate (soman), which is a chemical warfare agent. Prior estimates suggested that it is necessary to be able to detect soman at a concentration below 2.5 x 10(-7) M. Using four previously developed monoclonal antibodies, an enzyme-linked immunosorbant assay (ELISA) was used to optimize assay conditions and identify the antibody with the highest apparent affinity. The minimum required assay time was 2.0-2.5 h with no loss in sensitivity. To determine the specificity of the highest affinity antibody, a competitive inhibition enzyme immunoassay (CIEIA) was performed with six structural analogs of soman. The IC50 values for these analogues were 5 x 10(-7) M for 4-nitrophenylpinacolylmethylphosphonate, 8 x 10(-7) M for dipinacolylmethylphosphonate, 2 x 10(-6) M for diisopropylmethylphosphonate, 3 x 10(-5) M for 4-nitrophenylmethyl(phenylphosphinate) and 6.5 x 10(-5) M for 4-nitrophenylethyl(phenyl)phosphinate. 4-Nitrophenyl-di(n-butyl)phosphinate did not inhibit binding. Those inhibitors with branched alkyl side-chains, similar to the soman molecule, were effective inhibitors. Compounds, which contained predominately aromatic groups, were poor inhibitors. We are continuing to probe the binding specificity of the monoclonal antibody to determine its utility in further assay development. Our present results suggest that the antibody chosen may have the appropriate specificity and affinity for immunodiagnosis of exposure to soman. Copyright 2001 John Wiley & Sons, Ltd.

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Protective action of the serine protease inhibitor N-tosyl-L-lysine chloromethyl ketone (TLCK) against acute soman poisoning. Cowan F M; Broomfield C A; Lenz D E; Shih T M Biochemical Pharmacology and Neurotoxicology Branches, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 293-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481662 AN 2002027826 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Soman-poisoned rats display cholinergic crisis, a systemic mast cell degranulation characteristic of anaphylactic reactions and an excitotoxin-like sequential seizure and neuronal degeneration. The protection of guinea pigs from soman lethality by prophylactic administration of the serine protease inhibitor suramin suggests a possible proteolytic component in soman poisoning. The present study tested the effect of N-tosyl-L-lysine chloromethyl ketone (TLCK), an inhibitor of trypsin-like serine proteases, on soman-induced toxic signs (convulsions, righting reflex) and survival time. Nine control guinea pigs receiving 2 x LD(50) (56 microg kg(-1), s.c.) of soman immediately followed by a therapeutic dose of atropine sulfate (17.4 mg kg(-1) i.m.) experienced severe convulsions, and 8/9 lost the righting reflex. Six of these nine animals expired within 65 min; the three remaining animals survived 24 h to termination of the experiment. When a second group of animals were given TLCK (12 mg kg(-1), i.p.) 30 min prior to a 2 x LD(50) soman challenge and atropine-sulfate therapy, 5/9 experienced convulsions and only 3/9 lost the righting reflex. All nine animals survived beyond 4 h, with six surviving to 24 h. Compared with soman controls, prophylaxis with TLCK significantly prevented the loss of righting reflex (P = 0.05) and enhanced 4-h survival (P = 0.005). Although, convulsions were reduced and 24-h survival was improved in TLCK-treated animals, these results were not statistically significant. The protection from soman toxicity by chemically distinct protease inhibitors such as suramin and TLCK suggests a role for pathological proteolytic pathways in soman intoxication. Copyright 2001 John Wiley & Sons, Ltd.

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In vitro skin absorption and decontamination of sulphur mustard: comparison of human and pig-ear skin. Chilcott R P; Jenner J; Hotchkiss S A; Rice P Department of Biomedical Sciences, CBD Porton Down, Salisbury, Wiltshire SP4 0JQ, UK Journal of applied toxicology : JAT (2001 Jul-Aug), 21(4), 279-83. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11481660 AN 2002027824 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The aim of this study was to evaluate the use of an in vitro skin diffusion cell system as a model for assessing decontaminants against the chemical warfare agent sulphur mustard (SM). The in vitro absorption rates of SM through heat-separated human (157 +/- 66 microg cm(-2) h(-1)) and pig-ear (411 +/- 175 microg cm(-2) h(-1)) epidermal membranes were in agreement with previous in vivo studies that quoted skin absorption rates of 150 and 366 microg cm(-2) h(-1), respectively. Decontaminants (fuller's earth, Ambergard and BDH spillage granules) were ranked in order of effectiveness by measuring the skin absorption rates and the percentage of applied dose of SM that penetrated human and pig-ear epidermal membranes. The effectiveness of fuller's earth measured in this in vitro study using human epidermal membranes was in agreement with a previous in vivo human volunteer study. Similarly, the effectiveness of fuller's earth and Ambergard measured in vitro with pig-ear epidermal membranes was in agreement with a previous in vivo study conducted on rats. However, there was complete disparity in the ranking of decontaminants between human and pig-ear epidermal membranes measured in vitro. Thus, although pig-ear skin may be a relatively good model for predicting the human skin absorption of SM, it is a poor model for testing decontamination systems. The results of this study further validate the use of Franz-type glass diffusion cells containing human epidermal membranes as a model for predicting in vivo human skin absorption. Copyright 2001 John Wiley & Sons, Ltd.

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Modelling aerosol processes related to the atmospheric dispersion of sarin. Kukkonen J; Riikonen K; Nikmo J; Jappinen A; Nieminen K Air Quality Research, Finnish Meteorological Institute, Sahaajankatu 20 E, FIN-00810, Helsinki, Finland. jaakko.kukkonen@fmi.fi Journal of hazardous materials (2001 Aug 17), 85(3), 165-79. Journal code: 9422688. ISSN:0304-3894. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11489522 AN 2001443815 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

We have developed mathematical models for evaluating the atmospheric dispersion of selected chemical warfare agents (CWA), including the evaporation and settling of contaminant liquid droplets. The models and numerical results presented may be utilised for designing protection and control measures against the conceivable use of CWA's. The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. This model evaluates the thermodynamical evolution of a five-component aerosol mixture, consisting of two-component droplets together with the surrounding three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in characteristic dispersal and atmospheric conditions. In particular, we have evaluated the maximum radii (r(M)) of a totally evaporating droplet, in terms of the ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 microm for sarin droplets for the selected ambient conditions and initial heights. We have also evaluated deposition fractions in terms of the initial droplet size.

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Effects of iodine on inducible nitric oxide synthase and cyclooxygenase-2 expression in sulfur mustard-induced skin. Nyska A; Lomnitski L; Maronpot R; Moomaw C; Brodsky B; Sintov A; Wormser U Laboratory of Experimental Pathology, National Institutes of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA. nyska@niehs.nih.gov Archives of toxicology (2001 Feb), 74(12), 768-74. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11305779 AN 2001394179 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

In a previous study we demonstrated the protective effect of topical iodine as postexposure treatment for sulfur mustard (SM) application. The iodine treatment results in significantly reduced inflammation and necrosis and increased epidermal hyperplasia. The expression and localization of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) in paraffin-embedded skin samples from that study were evaluated in the present investigation. We compared the immunoreactivity of iNOS and COX-2 using five samples from each of the following four test sites: untreated control sites, SM-exposed sites, sites treated with iodine mixture 15 min after SM exposure, and sites treated with iodine 30 min after SM exposure. All animals were killed 2 days after irritant exposure. iNOS immunoreactivity was present only in skin sites exposed to SM without iodine treatment. The ulcerated skin was covered with a relatively thick band of exudate composed of iNOS-immunostained polymorphonuclear cells and macrophages. In untreated skin, COX-2 immunostaining was limited to the thin suprabasal epidermal layer. In SM-exposed skin, induction of COX-2 was noted in inflammatory cells located close to the site of epidermal injury. In skin sites treated with iodine 15 or 30 min after SM exposure, the regenerating hyperplastic epithelium showed moderate cytoplasmic staining localized to the epithelium overlying the basal layer. This pattern of staining was also present in the nearby dermal fibroblasts. Thus, in contrast to the skin samples exposed to SM without iodine treatment, the epidermal layer expressing immunohistochemical positivity for COX-2 was thicker and corresponded to the epidermal hyperplasia noted in samples treated with iodine. It is well documented that prostaglandins (PGs) promote epidermal proliferation, thereby contributing to the repair of injured skin. That the induction of the COX-2 shown in our study may also play a role in the healing process is indicated by the present evidence.
The results suggest that nitric oxide radicals (NO*) are involved in mediating the damage induced by the SM and that iodine-related reduction in acute epidermal inflammation is associated with reduced iNOS expression.

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Intervention of sulfur mustard toxicity by downregulation of cell proliferation and metabolic rates. Ray R; Benton B J; Anderson D R; Byers S L; Petrali J P US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA. radharaman.ray@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S87-91. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428650 AN 2001371709 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Metabolically active and proliferating basal cells in the skin are most sensitive to the potent skin blistering chemical warfare compound HD (bis-(2-chloroethyl) sulfide). We previously described a Ca2+-dependent mechanism of HD (0.3-1 mM) toxicity that was inhibited by the cell-permeant Ca2+ chelator BAPTA AM (1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester). We describe some cellular effects of BAPTA AM that suggest a mechanism for its protective action. Monolayer log-phase normal human epidermal keratinocytes were incubated (37 degrees C) first in keratinocyte growth medium (KGM) containing BAPTA AM (10-40 microM) for 30 min and then in KGM alone overnight prior to evaluation. The BAPTA AM inhibited cell growth in a concentration-dependent manner with some cellular degeneration above 30 microM (light microscopy). At 20-30 microM, BAPTA AM also inhibited cellular metabolic processes, as evidenced by a lower incorporation of [3H]-thymidine (DNA synthesis, 54 +/- 5%), [3H]-uridine (RNA synthesis, 29 +/- 6%) and [14C]-valine (protein synthesis, 12 +/- 2%) as well as a lower protein content per culture (30 +/- 3%) compared with corresponding untreated controls. However, 20-30 microM BAPTA AM did not cause any demonstrable cytopathology based on morphological (electron microscopy) as well as biochemical (lactate dehydrogenase release, an indicator of cell viability loss) criteria, indicating a lack of acute toxicity. These results suggest that a mechanism of protection by BAPTA AM against HD may be via decreasing some metabolic, and therefore proliferative, rates.

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Comparison of cell size in sulfur mustard-induced death of keratinocytes and lymphocytes. Moser J; Meier H L Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S23-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428638 AN 2001371697 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD) is a vesicant chemical warfare agent that directly alkylates cellular DNA and produces DNA strand breaks. To identify cellular models for in vitro screening of antivesicant compounds in DNA repair assays, we compared the mechanism of HD-induced cell death in cultured adult normal human epidermal keratinocytes (NHEK) and peripheral blood lymphocytes (PBL). One parameter that we used to distinguish apoptotic from necrotic cell death was the change in cell size due to HD. In the presence or absence of a poly(ADP-ribose) polymerase inhibitor (PARPI), cell preparations were exposed to various concentrations of HD (0.01-1.0 mM) and harvested at selected times after exposure (up to 24 h). Results from these experiments suggest that, with increasing HD concentration and time, NHEK will fragment irrespective of the presence or absence of PARPI, with cell fragmentation presumably preceded by necrosis. In the absence of PARPI, PBL size initially decreases and then remains constant over time. Previous DNA fragmentation studies indicate that both apoptosis and necrosis occur in HD-exposed PBL in a time-dependent manner. In the presence of PARPI, there is a HD concentration- and time-dependent decrease in PBL size that is characteristic of apoptosis. The shift in the mechanism of HD-induced PBL death from apoptosis followed by necrosis to exclusively apoptosis in the absence and presence of PARPI, respectively, is in agreement with previous findings on HD-induced changes in membrane integrity, energy levels and DNA fragmentation. Considering that NHEK fragment early after exposure to HD concentrations that produce vesication in human skin, PBL may be a more appropriate model for use in DNA repair assays.

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MALDI-ToF/MS as a diagnostic tool for the confirmation of sulfur mustard exposure. Price E O; Smith J R; Clark C R; Schlager J J; Shih M L Pharmacology Division, Applied Pharmacology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S193-7. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428636 AN 2001371695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The continual threat of chemical and biological warfare has prompted the need for unambiguous analytical methods for the confirmation of agent exposure. In this paper, we have investigated the use of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF/MS) as a diagnostic tool for this purpose. Mass spectral studies of the interaction of sulfur mustard (bis-(2-chloroethyl) sulfide, HD) with hemoglobin and metallothioneine were conducted. In vitro experiments with purified proteins were performed, using both HD and chloroethylethyl sulfide (CEES), in an effort to determine the extent of alkylation and occurrence of HD cross-linking using the MALDI-ToF/MS technique. In a typical experiment, 50 ml of 5 mM HD in acetonitrile was added to an equal volume of 0.5 mM hemoglobin in deionized water followed by vortexing and incubation at room temperature. After 24 h, the samples were analyzed by MALDI-ToF/MS. Mass spectral results indicated the presence of at least two distinct alkylation adducts for both HD and CEES experiments. These results demonstrate that MALDI-ToF/MS is a useful analytical technique to investigate the interaction of HD with biomolecules and may be employed potentially as a diagnostic tool for the confirmation of exposure to chemical warfare agents.

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Automated assay for nicotinamide adenine dinucleotide (NAD+). Byers S; Anderson D; Brobst D; Cowan F Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S19-22. Journal code: 8109495. ISSN:0260-437X. (EVALUATION STUDIES); Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428635 AN 2001371694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (HD), a vesicating chemical warfare compound, has been shown to deplete the nicotinamide adenine dinucleotide (NAD+) content in several cell systems and tissues. This NAD+ depletion has been proposed as an indicator of HD exposure and can be used to evaluate potential antivesicant compounds. To examine NAD+ levels, an automated method based on the alcohol dehydrogenase cycling assay of Jacobson and Jacobson and utilizing a Cobas FARA clinical analyzer has been developed. Automation of this assay led to smaller sample volumes and more efficient use of personnel and resources. The usefulness of this automated method was tested by evaluating the protection, if any, by the topical application of vitamin D or betamethasone against HD-induced NAD+ depletion in skin punches from the hairless guinea pig. The results showed that the samples exposed to HD exhibited significant decreases in NAD+ levels when compared with controls. However, neither vitamin D nor betamethasone demonstrated protection against HD-induced NAD+ depletion. In fact, betamethasone exacerbated the NAD+ depletion when compared with the HD exposed group. This assay appears to be useful for testing potential antivesicant compounds using both in vivo and in vitro exposure systems.

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A cutaneous full-thickness liquid sulfur mustard burn model in weanling swine: clinical pathology and urinary excretion of thiodiglycol. Graham J S; Reid F M; Smith J R; Stotts R R; Tucker E S; Shumaker S M; Niemuth N A; Janny S J US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S161-72. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428630 AN 2001371689 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulfur mustard (bis(2-chloroethyl)sulfide, HD) is a well-known blistering chemical warfare agent. We have developed a cutaneous full-thickness HD burn model in weanling pigs for efficacy testing of candidate treatment regimens. This report addresses clinical pathology findings and the urinary excretion profile of a major HD metabolite (thiodiglycol, TDG) in this model. Six female Yorkshire pigs were exposed to HD liquid on the ventral surface for 2 h, generating six 3-cm diameter full-thickness dermal lesions per pig. Blood samples were collected throughout a 7-day observation period for hematology and serum chemistry examinations. Urine was collected in metabolism cages. Routine urinalysis was performed and the urine analyzed for TDG using gas chromatography/mass spectrometry. Examination of clinical pathology parameters revealed subtle HD-related changes that are suggestive of a mild hemolytic episode. No other signs of clinically significant systemic toxicities were noted, including bone marrow suppression. Thiodiglycol was detected at the earliest time point tested (6-8 h post-exposure) at levels ranging from 0.66 to 4.98 microg ml(-1) with a mean of 2.14 microg ml(-1). Thiodiglycol concentrations were the highest for half of the animals at this earliest time point and at 24-48 h for the others. By the evening of day 3, the mean level had reached 50 ng ml(-1). Mean levels remained 10-40 ng ml(-1) for the remainder of the 7-day observation period, with the highest individual concentration noted during this period of 132 ng ml(-1). Our results are in general agreement with the TDG excretion profiles previously described for rodent models and humans. Urinary excretion of absorbed HD in our weanling pig wound healing model appears to follow the same pattern as is seen in other laboratory animals models. In general, urinary excretion of TDG appears to peak within the first 1-4 days following exposure, with detectable levels after 1 week.
Relatively high urinary TDG levels may thus indicate agent exposure within the previous 96 h. Low levels significantly above natural background levels may indicate either exposure to low levels of agent or exposure that occurred more than 4 days prior to collection of the sample.

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Systemic administration of candidate antivesicants to protect against topically applied sulfur mustard in the mouse ear vesicant model (MEVM). Babin M C; Ricketts K; Skvorak J P; Gazaway M; Mitcheltree L W; Casillas R P Drug Assessment and Comparative Medicine Divisions, United States Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010, USA. Michael.Babin@amedd.army.mil Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S141-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428627 AN 2001371686 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The mouse ear vesicant model (MEVM) provides a quantitative edema response as well as histopathological and biochemical endpoints as measurements of inflammation and tissue damage following exposure to the chemical warfare agent sulfur mustard (HD). In the MEVM, several topically applied anti-inflammatory agents provided a significant degree of protection against HD-induced edema and dermal-epidermal separation. This study evaluated the protective effects of three of these pharmacological compounds when administered systemically in the MEVM. Alzet osmotic pumps were used to deliver a subcutaneous dose of the appropriate anti-inflammatory agent, starting 24 h before exposure to sulfur mustard and continuing until 24 h post-exposure to HD. Twenty-four hours after pump implantation, 5 microl of a 195 mM (0.16 mg) solution of sulfur mustard (density = 1.27 g ml(-1); MW = 159; purity = 97.5%) in methylene chloride was applied to the inner surface of the right ear of each mouse. Sulfur mustard injury in the mouse ear was measured by both edema response (fluid accumulation) and histopathological damage (necrosis, epidermal-dermal separation). The systemic administration of hydrocortisone, indomethacin and olvanil provided a significant reduction in edema (24%, 26% and 22%, respectively) from the positive control. Compared to HD-positive controls, hydrocortisone, indomethacin and olvanil caused a significant reduction in subepidermal blisters (71%, 52% and 57%, respectively) whereas only hydrocortisone produced a significant reduction in contralateral epidermal necrosis (41%). We show here that these anti-inflammatory drugs are effective when administered systemically in the MEVM.

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N-acetylcysteine and endothelial cell injury by sulfur mustard. Atkins K B; Lodhi I J; Hurley L L; Hinshaw D B University of Michigan Medical School, Ann Arbor 48105, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S125-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428622 AN 2001371681 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Understanding the underlying mechanisms of cell injury and death induced by the chemical warfare vesicant sulfur mustard (HD) will be extremely helpful in the development of effective countermeasures to this weapon of terror. We have found recently that HD induces both apoptosis and necrosis in endothelial cells (Toxicol. Appl. Pharmacol. 1996; 141: 568-583). Pretreatment of the endothelial cells for 20 h with the redox-active agent N-acetyl-L-cysteine (NAC) selectively prevented apoptotic death induced by HD. In this study, we tested the hypotheses that pretreatment with NAC acts through two different pathways to minimize endothelial injury by HD: NAC pretreatment acts via a glutathione (GSH)-dependent pathway; and NAC pretreatment acts to suppress HD-induced activation of the nuclear transcription factor NFkappaB. We used a fluorescence microscopic assay of apoptotic nuclear features to assess viability and electrophoretic mobility shift assays (EMSAs) to assess the activity of NFkappaB following exposure to HD. The cells were treated with 0-10 mM GSH for 1 h prior to and during exposure to 0 or 500 microM HD for 5-6 h. Cells were also treated with 50 mM NAC or 200 microM buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, alone or in combination overnight prior to exposure to 0 or 500 microM HD for 5-6 h. Externally applied GSH up to a concentration of 5 mM had no toxic effect on the cells. Mild toxicity was associated with 10 mM GSH alone. There was a dose-related enhancement of viability when 2.5 and 5 mM GSH were present during the HD exposure. Pretreatment with BSO alone had no discernible toxicity. However, pretreatment with this inhibitor of GSH synthesis potentiated the toxicity of HD. Pretreatment with 50 mM NAC, as previously reported, provided substantial protection. Combining pretreatment with both BSO and NAC eliminated the protective effect of NAC pretreatment alone on HD injury.
These observations are highly suggestive that NAC enhances endothelial survival via GSH-dependent effects and confirms and extends the work of others with different models that externally supplied GSH alone may be a fairly effective countermeasure against HD injury of endothelium. We next examined the hypothesis that HD may activate the nuclear transcription factor NFkappaB by performing EMSAs with nuclear extracts of endothelial cells following exposure to 0, 250 or 500 microM HD. This demonstrated an up to 2.5-fold increase (scanning densitometry) in activation of NFkappaB binding to its consensus sequence induced by 500 microM HD after 5 h of HD exposure. Paradoxically, treatment of the endothelial cells alone with 50 mM NAC activated NFkappaB, although HD-induced activation of NFkappaB was partially suppressed by NAC at 5 h. Factor NFkappaB is an important transcription factor for a number of cytokine genes (e.g. tumor necrosis factor, TNF), which can be activated following stress in endothelial cells. Taken together, these observations suggest that the protective effects of NAC may be mediated by enhanced GSH synthesis. The increased GSH may act to scavenge HD and also prevent oxidative activation of NFkappaB. Under some conditions, NAC may act as an oxidizing agent and thus increase NFkappaB activity. The NFkappaB-dependent gene expression may be important in inducing endothelial cell death as well as in generating a local inflammatory reaction associated with the release of endothelial-derived cytokines.

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Effects of CEES on inflammatory mediators, heat shock protein 70A, histology and ultrastructure in two skin models. Blaha M; Bowers W Jr; Kohl J; DuBose D; Walker J; Alkhyyat A; Wong G US Army Research Institute of Environmental Medicine, Natick, MA 01760, USA Journal of applied toxicology : JAT (2000 Dec), 20 Suppl 1 S101-8. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11428619 AN 2001371678 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Chemical warfare threats require the development of diverse models for the assessment of countermeasures. Human skin products, Skin2 (differentiating keratinocytes on a fibroblast-collagen matrix) and EpiDerm (differentiating keratinocytes) were exposed (2 h) to the sulfur mustard 2-chloroethyl ethyl sulfide (CEES, 1-2 mg l(-1) min(-1)) in humidified air or to humidified air alone. Tissues were evaluated histologically, ultrastructurally and for viability 22 h later; media and tissues were also analyzed for inflammatory mediators. Histology showed that CEES induced the separation of dermal and epidermal regions in Skin2 with severe damage to basal keratinocytes. Histology and electron microscopy of both products revealed condensation of nuclear chromatin, retraction of spinous processes, collapse of the tonofibrillar network and cytoplasmic vacuolization and blebbing in those cells with loss of pseudobasement membrane integrity. Exposure of Skin2 to CEES increased extracellular interleukin-1alpha (IL-1alpha), prostaglandin-E2 (PGE2) and especially IL-1 receptor antagonist (IL-1Ra) release (56,334 vs 84,614 pg ml(-1)), but decreased interleukin-6 (IL-6, 4,755 vs 351 pg ml(-1)). Exposure of EpiDerm to CEES led to unaffected extracellular and reduced intracelluar IL-1alpha (371 vs 92 pg ml(-1)). Extracellular IL-1Ra greatly increased (2,375 vs 24,875 pg ml(-1)), whereas cellular levels decreased (16,5425 vs 96,625 pg ml(-1)). Extracellular (224 vs 68 pg ml(-1)) and intracellular (485 vs 233 pg ml(-1)) soluble interleukin-1 receptor H (sIL-1RII) decreased. Prostanglandin E2 increased (1,835 vs 2,582 pg ml(-1)), whereas heat shock protein 70A (Hsp70A) remained statistically unchanged (57,000 vs 96,000 pg ml(-1)). Failure to obtain a heat shock response to CEES may contribute to the susceptibility of tissue to the alkylating agent. Consistent and marked responses of cellular and extracellular IL-1Ra to CEES suggest a potential for use as a tissue status marker and primary antiinflammatory regulator in skin.

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Correlation of a specific mitochondrial phospholipid-phosgene adduct with chloroform acute toxicity. Di Consiglio E; De Angelis G; Testai E; Vittozzi L Biochemical Toxicology Unit, Department of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanita, Viale Regina Elena 299, I-00161, Rome, Italy Toxicology (2001 Feb 21), 159(1-2), 43-53. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11250054 AN 2001195862 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The dose and time dependence of formation of a specific adduct between mitochondrial phospholipid and phosgene have been determined in the liver of Sprague-Dawley (SD) rats as well as in the liver and kidney of B6C3F1 mice after dosing with chloroform. Rats were induced with phenobarbital or non-induced. Determination of tissue glutathione (GSH) and of serum markers of hepatotoxicity and nephrotoxicity was also carried out. With dose-dependence experiments, a strong correlation between the formation of the specific phospholipid adduct, GSH depletion and organ toxicity could be evidenced in all the organs studied. With non-induced SD rats, no such effects could be induced up to a dose of 740 mg/kg. Time-course studies with B6C3F1 mice indicated that the specific adduct formation took place at very early times after chloroform dosing and was concurrent with GSH depletion. The adduct formed during even transient GSH depletion (residual level: 30% of control) and persisted after restoration of GSH levels. Following a chloroform dose at the hepatotoxicity threshold (150 mg/kg), the elimination of the adduct in the liver occurred within 24 h and correlated with the recovery of ALT, which was slightly increased (12 times) after treatment. Following a moderately nephrotoxic dose (60 mg/kg), the renal adduct persisted longer than 48 h, when a 100% increase in blood urea nitrogen and a 40% increase in serum creatinine indicated the onset of organ damage. The formation of the adduct in the liver mitochondria of B6C3F1 mice was associated with the decrease of phosphatidyl-ethanolamine (PE), in line with previous results in rat liver indicating that the adduct results from the reaction of phosgene with PE. The adduct levels implicated the reaction of phosgene with about 50% PE molecules in the liver mitochondrial membrane of phenobarbital-induced SD rats and of about 10% PE molecules of the inner mitochondrial membrane of the liver of B6C3F1 mice.
The association of this adduct with the toxic effects of chloroform makes it a very good candidate as the primary critical alteration in the sequence of events leading to cell death caused by chloroform.

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The influence of anticholinergic drug selection on the efficacy of antidotal treatment of soman-poisoned rats. Kassa J; Fusek J Purkyne Military Medical Academy, PO Box 35/T, 500 01, Hradec Kralove, Czech Republic. kassa@pmfhk.cz Toxicology (2000 Nov 23), 154(1-3), 67-73. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 11118671 AN 2001083637 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The influence of some anticholinergic drugs (atropine, benactyzine, biperiden, scopolamine) on the efficacy of antidotal treatment to eliminate soman (O-pinacolyl methylphosphonofluoridate)-induced disturbance of respiration and circulation and to protect experimental animals poisoned with supralethal dose of soman (1.5 x LD(50)) was investigated in a rat model with on-line monitoring of respiratory and circulatory parameters. While the oxime HI-6 in combination with atropine prevented soman-induced changes in monitored physiological parameters insufficiently and very shortly, the combination of HI-6 with benactyzine or biperiden is able to prevent soman-induced alteration of respiration and circulation much more longer. Nevertheless, only rats treated with HI-6 in combination with scopolamine were fully protected against the lethal toxic effects of soman within 2 h following soman challenge. Our findings confirm that anticholinergic drugs with the strong central antimuscarinic activity, such as benactyzine, biperiden and especially scopolamine, seem to be more effective adjuncts to HI-6 treatment of severe acute soman-induced poisoning than atropine.

[megalomania]

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Reactions of sulfides with S-330, a potential decontaminant of sulfur mustard in formulations. Shih, Ming L.; Korte, William D.; Smith, J. Richard; Szafraniec, Linda L. US Army Medical Research Institute of Chemical Defense, APG, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S83-S88. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:289769 AN 2000:132684 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Because the vesicant sulfur mustard (HD) remains a major chem. threat from either domestic terrorists or countries in conflict, topical prepns. are being evaluated as protectants from HD exposure. The objective of this study was to evaluate the effectiveness of chloroamide S-330 as a potential reactive component in topical formulations. Therefore, the rate, mechanism and byproducts of the oxidn. reactions of sulfides by S-330 in solvent media or specific formulation vehicles were investigated. Using NMR, LC, LC-MS and GC-MS, the reactions of S-330 with HD, di-Bu sulfide (DBS) and Me Ph sulfide (MPS) were studied in acetonitrile, chloroform and perfluoropolyether (PFPE) oil. The oxidn. of the three sulfides with S-330 was very rapid and completed in <4 min in acetonitrile-water or PFPE oil, but the rates of reaction in chloroform were significantly slower. In a large excess of S-330, the major products resulted from chlorination of the side chains. At a high HD/S-330 ratio, the major product was HD sulfoxide. Under both conditions, only a trace of HD sulfone, also a blistering agent, was obsd. Reactions with DBS and MPS primarily gave sulfoxides and sulfones, with less side-chain chlorination. The chloroamide S-330 appeared to be a rapid and effective decontaminant of HD in either polar media or in a PFPE oil. The two alkyl and aryl sulfides are suitable simulants of HD for the initial screening and evaluation of S-330 or other similar oxidizing agents.

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Polyoxometalate oxidation of chemical warfare agent simulants in fluorinated media. Johnson, Rhoma P.; Hill, Craig L. Department of Chemistry, Emory University, Atlanta, GA, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S71-S75. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 133:1581 AN 2000:132682 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this research is to det. if appropriate polyoxometalates (POMs) could be added to perfluoropolyether topical skin protectants (TSPs) currently available or under development to give these TSPs the addnl. capability of detecting and in some cases catalytically decontaminating sulfur mustard (HD) and perhaps other chem. warfare agents (CWAs) at ambient temps. Detection would be based on significant color changes in the POM upon redn. by the CWA whereas catalytic decontamination would be based on the ability of some families of POMs to catalyze O2-based oxidns. by more than one mechanism. Five POMs (10-25% by wt.) were each suspended in .apprx.5 g of the perfluoropolyether (PFPE, CF3O[-CF(CF3)CF2O-]x(-CF2O-)yCF3) "barrier" cream. A stoichiometric amt. of HD sulfide simulant was layered on top of each POM-cream mixt. The short reaction times were recorded for each system. Mechanistic studies were conducted using an PFPE oil analog of the barrier cream in a microemulsion with the sulfide simulant, POM, PFPE surfactant and 2,2,2-trifluoroethanol co-surfactant.

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Development of reactive topical skin protectants against sulfur mustard and nerve agents. Koper, Olga; Lucas, Eric; Klabunde, Kenneth J. Nantek, Inc., Manhattan, KS, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S59-S70. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:261513 AN 2000:132681 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The potential for highly reactive nanoparticles (RNP) to absorb destructively, i.e. to neutralize highly toxic substances such as the warfare agents GA, GB, HD and VX, has been demonstrated in the lab. Reactive nanoparticles represent a new class of nanoscale particles of metals and metal oxides that differ from other nanoparticles in reactivity and cryst. morphol. The potential for incorporating RNP into a protective barrier skin cream also has been demonstrated. Preliminary studies indicate that RNP are phys. and chem. compatible with a base cream provided by the Army Medical Research Office and, importantly, remain reactive with chem. agents while promising to be compatible with skin contact.

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Development of a reactive topical skin protectant. Braue, Ernest H., Jr. Advanced Assessment Branch, Drug Assessment Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S47-S53. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:289768 AN 2000:132679 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The use of a topical skin protectant (TSP) as a means of protecting troops from percutaneous chem. warfare agent (CWA) exposure has been proposed since these weapons were first used during World War I. The TSP is applied to vulnerable skin surfaces prior to entry into a chem. combat area. In 1990, the US Army Medical Research Institute of Chem. Defense transferred two non-reactive TSPs into advanced development. Following US Food and Drug Administration approval, the final product is expected to be available to soldiers in 1999. A continuing research effort is designed to develop a second-generation TSP that will increase effectiveness and also decontaminate CWAs into non-toxic products. We identified a list of 29 reactive moieties as potential additives to the TSP formulation. All candidate formulations are evaluated in a decision tree network, consisting of a series of 11 efficacy testing models. A prototype formulation (ICD 2701) contg. the reactive ingredient S-330 has dramatically improved the protection against satd. sulfur mustard vapor. In addn., we have discovered a compd. (ICD 2837) that significantly increases the skin's natural resistance to CWA penetration. Our goal is to transfer a significantly improved TSP formulation into advanced development by 1999.

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Efficacy of the topical skin protectant in advanced development. Liu, Dai Kee; Wannemacher, Robert W.; Snider, Thomas H.; Hayes, Timothy L. US Army Medical Material Development Activity, Fort Detrick, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S41-S45. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:261511 AN 2000:132678 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A topical skin protectant (TSP) (ICD 2289) is being developed to protect service members from exposure to chem. warfare agents (CWA). The TSP is designed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clin. studies, is a cream contg. two chem. inert substances: perfluoroalkylpolyether and polytetrafluoroethylene. Animal data showed that the TSP was effective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by preventing the development of erythema and edema. The insect repellent N,N-diethyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protection was sustained when DEET was removed with a dry gauze prior to TSP application. The TSP was also effective against percutaneous exposure of nerve agents-thickened (with 5% Me methacrylamide) soman and VX by reducing the mortality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when DEET was applied prior to TSP application. Because human efficacy studies using CWA cannot be conducted, the efficacy will be demonstrated by the level of protection against poison ivy (urushiol) contact dermatitis in humans.

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Sulfur mustard induced DNA damage in mice after dermal and inhalation exposure. Lakshmana Rao, P. V.; Vijayaraghavan, R.; Bhaskar, A. S. B. Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India. Toxicology (1999), 139(1-2), 39-51. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 132:162248 AN 1999:746442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (SM) is a chem. warfare agent of the blistering agent category for which there is still no effective therapy. SM, being a strong electrophile, readily reacts with a wide range of cellular macromols. including DNA, RNA and protein. Since the main intoxication routes for SM are inhalation and dermal penetration, in the present study we have exposed female mice to different concns. of SM by dermal and inhalation exposures and estd. the DNA damage in different organs viz., liver, lung, spleen and thymus. SM was applied at 38.7, 77.4, 154.7 mg/kg body wt., on the hair-clipped skin (dermal exposure) equiv. to 0.25, 0.5 and 1.0 of the LD50. Inhalation exposure was carried out at 10.6, 21.2 and 42.3 mg/m3 for 1 h duration equiv. to 0.25, 0.5 and 1.0 LC50. SM induced a dose-dependent DNA damage in all the organs except the lung in dermal exposure. Similarly the inhalation exposure resulted in dose- and time-dependent effect in all the organs including lung. By both routes of exposure liver was the most affected organ followed by spleen, thymus and lung in decreasing order. The quant. data were corroborated by qual. anal. of DNA on agarose gel electrophoresis. The genomic DNA anal. of the organs had revealed random nuclear DNA fragmentation resulting in a 'smear' typical of necrotic form of cell death. Since DNA damage is not reversible esp. in liver, this can be used as a marker for SM exposure through either the dermal or inhalation route.

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Synthesis and mass spectral characterization of diisopropylamino-ethanethiol, -sulfides and -disulfides and vinyl sulfides. Rohrbauch, D. K.; Berg, F. J.; Szafraniec, L. J.; Rossman, D. I.; Durst, H. D.; Munavalli, S. Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, U.S. Army, Aberdeen, MD, USA. Phosphorus, Sulfur and Silicon and the Related Elements (1999), 149 95-106. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 132:49741 AN 1999:681810 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The sulfur contg. chem. agent, O-ethyl-S-2-(diisopropylaminoethyl)methylphosphonothiolate, is an extremely potent inhibitor of the enzyme acetylcholinesterase and exhibits extended neurol. effects. It undergoes degrdn. on standing alone or in the environment. Hence, identification of its primary degrdn. products assumes considerable importance. The synthesis and mass spectral fragmentation behavior of the title compds., some of which are present in the O-ethyl-S-2-(diisopropylaminoethyl)methylphosphonothiolate degrdn. products, has not received much attention. This communication describes the synthesis and mass spectral characterization of the title compds.

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Reaction of Bis(2-chloroethyl) Sulfide with N,N'-Dichlorobis(2,4,6-trichlorophenyl)urea. Dubey, D. K.; Malhotra, R. C.; Vaidyanathaswamy, R.; Vijayaraghavan, R. Defence R. & D. Establishment, Gwalior, India. Journal of Organic Chemistry (1999), 64(21), 8031-8033. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 132:12186 AN 1999:629651 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The reaction of bis(2-chloroethyl)sulfide (warfare agent) with N,N'-dichloro-N,N'-bis(2,4,6-trichlorophenyl)urea was describe with the aim of using the latter as a decontamination agent.

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Reactions of VX, HD, and Their Simulants with NaY and AgY Zeolites. Desulfurization of VX on AgY. Wagner, George W.; Bartram, Philip W. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Langmuir (1999), 15(23), 8113-8118. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 131:299202 AN 1999:577485 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The room-temp. reactions of the chem. warfare agents VX (O-Et S-2-(diisopropylamino)ethyl methylphosphonothioate), HD (2,2'-dichloroethyl sulfide, or mustard), and their common simulants, O,S-di-Et phenylphosphonothioate (DEPPT) and 2-chloroethyl Ph sulfide (CEPS), with NaY and silver-exchanged (AgY) zeolites have been studied using solid-state magic angle spinning NMR. VX hydrolyzes via exclusive cleavage of the P-S bond on both NaY and AgY to yield Et methylphosphonate (EMPA). The reaction is significantly faster on AgY than on NaY, suggesting catalysis by silver. On AgY, an intermediate silver salt of EMPA is apparently formed which is slowly converted to Et 2-(diisopropylamino)ethyl methylphosphonate (QB, the desulfurized analog of VX) in about a 78% yield. DEPPT similarly hydrolyzes via P-S cleavage on AgY to yield an apparent silver salt of Et phenylphosphonate, which does not undergo further reaction to the desulfurized analog. No reaction is obsd. for DEPPT on NaY. HD on AgY forms both vinyl sulfide and the cyclic ether 1,4-thioxane. HD reacts faster on NaY to exclusively form the CH-TG sulfonium ion (HOCH2CH2SCH2CH2S+[CH2CH2OH]2). CEPS also reacts faster on NaY, forming 2-hydroxyethyl Ph sulfide. On AgY, CEPS does not give the vinyl product, but does yield the ether product PhSCH2CH2OCH2CH2SPh. A mechanism is proposed for the silver-catalyzed hydrolysis of VX, the desulfurization of the cleaved thiol, and the formation of QB.

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Reaction of a Vesicular Functionalized Surfactant with 2-Chloroethyl Phenyl Sulfide, a Mustard Simulant. Jaeger, David A.; Schilling, Curtis L. III; Zelenin, Alexander K.; Li, Bei; Kubicz-Loring, Elzbieta. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (1999), 15(21), 7180-7185. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 131:233071 AN 1999:505232 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant, potassium O,O'-didodecylphosphorodithioate (I) was synthesized. Its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry and its giant vesicles by phase-contrast optical microscopy. Also, I's giant vesicles contg. fluorescent dye, 5-carboxyfluorescein or 5-(dodecanamido)fluorescein, were characterized by epifluorescence microscopy. In a pH 9.0 borate buffer at 25, vesicular I reacted with 2-(2-chloroethyl Ph sulfide), a simulant for the chem. warfare agent mustard [bis(2-chloroethyl) sulfide], to give 5-[S-[(2-phenylthio)ethyl]O,O'-didodecylphosphorodithioate] (II), involving capture of reactive intermediate cation 1-phenylthiocyclopropane by the anion of I. This reaction was accompanied by the pptn. of II, which resulted in wounding/destruction of the vesicles and the release of dye 5-carboxyfluorescein (from giant vesicles). The combination of the conversion and dye release suggests the potential of vesicular systems for simultaneous decontamination and signaling of chem. agents. 2-(2-Chloroethyl Ph sulfide) hydrolyzed to give only 2-(phenylthio)ethanol in the pH 9.0 buffer at 25.

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Two-generation reproduction study of lewisite in rats. Sasser, L. B.; Cushing, J. A.; Lindenmeier, C. W.; Mellick, P. W.; Dacre, J. C. Battelle, Richland, WA, USA. Journal of Applied Toxicology (1999), 19(4), 229-235. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 131:253491 AN 1999:485887 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite, a potent toxic vesicant and chem. warfare agent, is used in a no. of research labs., is stored in large quantities at depot sites throughout the USA and is occasionally transported to distant sites. Thus, the potential for environmental or occupational exposure exists where lewisite is present. A 42-wk two-generation study was conducted to det. the reproductive consequences of lewisite in parental male and female rats and their offspring. Rats were administered lewisite in sesame oil (0, 0.10, 0.25 or 0.60 mg kg-1 day-1 for 5 days a week) via intragastric intubation before mating, during mating and after mating until the birth of their offspring. The dams continued to receive lewisite during lactation. At weaning, male and female offspring of each group were selected to continue the study, receiving lewisite during adolescence, mating and throughout gestation and lactation. Lewisite had no adverse effect on reprodn. performance, fertility or reproductive organ wts. of male or female rats through two consecutive generations. No adverse effects to offspring were attributed to lewisite exposure. Minor changes in growth were the only maternal effects obsd. Lewisite exposure of parental rats caused no gross or microscopic lesion in testes, epididymis, prostate, seminal vesicles, ovaries, uterus or vagina. The no-observable-effect level (NOEL) for the reproductive effects of Lewisite would be >0.60 mg kg-1 day-1.

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Chemistry and toxicology of sulfur mustard-a review. Malhotra, R. C.; Ganesan, K.; Sugendran, K.; Swamy, R. V. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1999), 49(2), 97-116. CODEN: DSJOAA ISSN: 0011-748X. Journal; General Review written in English. CAN 131:112423 AN 1999:324517 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review and discussion with 124 refs. Bis(2-chloroethyl) sulfide commonly known as sulfur mustard (SM) is highly reactive bifunctional compd., documented as antimitotic, mutagenic, carcinogenic, teratogenic and cytotoxic agent. It is a powerful vesicant and has been employed as a chem. warfare agent. Skin, eyes and respiratory tract are the principal target organs and the DNA is the most important mol. target of SM toxicity. There is no specific antidote for SM injury. Treatment to SM toxicity is symptomatic.

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Surrogate burns in deactivation furnace system. Shah, Jay K. Science Applications International, Tooele, UT, USA. Journal of Hazardous Materials (1999), 66(3), 279-290. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 131:35263 AN 1999:308797 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The deactivation furnace system at the Deseret Chem. Depot in Utah is designed for processing explosive components from munitions contg. nerve and mustard agents. The Utah Division of Solid and Hazardous Waste (UDSHW) required that trial burns be conducted using surrogate chems. prior to introducing chem. agents into the system. Three surrogate runs of the selected surrogate chems. monochlorobenzene and hexachloroethane based on the criteria established by the UDSHW were conducted. The gaseous emissions and liq. and solid effluents were sampled and analyzed using approved EPA methods. The trial burns demonstrated the desirable destruction and removal efficiency for the selected surrogate chems. The pollution abatement system demonstrated the desired scrubbing efficiency for acid gases generated during incineration of chlorinated surrogate chems. The particulate removal efficiency during the trial burns was also considerably higher than required by regulations. After comprehensive survey of the performance of the deactivation furnace system during the surrogate trial burns, UDSHW approved introduction of GB nerve agent into the system to prep. it for agent trial burns.

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Reactions of VX, GD, and HD with Nanosize MgO. Wagner, George W.; Bartram, Philip W.; Koper, Olga; Klabunde, Kenneth J. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Journal of Physical Chemistry B (1999), 103(16), 3225-3228. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 130:337750 AN 1999:218187 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The room-temp. reactions of the chem. warfare agents VX (O-Et S-2-(diisopropylamino)ethyl methylphosphonothioate), GD (3,3-dimethyl-2-Bu methylphosphonofluoridate, or Soman), and HD (2,2'-dichloroethyl sulfide, or mustard) with nanosize MgO have been studied using solid-state MAS NMR. All three agents hydrolyze on the surface of the very reactive MgO nanoparticles. VX yields Et methylphosphonic acid (EMPA) and methylphosphonic acid (MPA), but no toxic S-(2-diisopropylamino)ethyl methylphosphonothioate (EA-2192). GD forms both GD-acid and MPA. For HD, in addn. to hydrolysis to thiodiglycol, about 50% elimination to divinyl sulfide occurs. The reaction kinetics for all three agents are characterized by a fast initial reaction followed by gradual slowing to a steady-state reaction with first-order behavior. The fast reaction is consistent with liq. spreading through the porous nanoparticle aggregates. The steady-state reaction is identified as a gas-phase reaction, mediated by evapn., once the liq. achieves its vol. in the smallest available pores.

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Cleavage of VX Simulants by Micellar Iodoso- and Iodoxybenzoate. Moss, Robert A.; Morales-Rojas, Hugo; Zhang, Hongmei; Park, Byeong-Deog. Department of Chemistry, Rutgers The State University of New Jersey, New Brunswick, NJ, USA. Langmuir (1999), 15(8), 2738-2744. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:328660 AN 1999:197621 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

O,S-Di-Et phenylphosphonothioate and S-Ph and S-Et diphenylthiophosphinate were efficiently cleaved by 3-fold excess o-iodosobenzoate (IBA) in aq. micellar cetyltrimethylammonium chloride solns. at pH 9.5. The max. obsd. rate consts. (monitored by HPLC aliquot procedures) were 1.09  10-3 s-1 for O,S-Di-Et phenylphosphonothioate and 6.0  10-3 s-1 for S-Et diphenylthiophosphinate with 0.06 M IBA at 25. S-Ph diphenylthiophosphinate cleaved too rapidly to follow by the aliquot method. With equimolar quantities of O,S-Di-Et phenylphosphonothioate and IBA, cleavage was slower and incomplete because of the redn. of the IBA to iodobenzoate by the EtSH liberated in the cleavage step. Mixts. of IBA and o-iodoxybenzoate (IBX) efficiently cleaved O,S-Di-Et phenylphosphonothioate, even though IBX was not reactive toward O,S-Di-Et phenylphosphonothioate, because the IBX competitively oxidized the EtSH, mitigating its reaction with IBA, while simultaneously affording addnl. IBA as the IBX was reduced. Studies of IBA and IBX redox reactions with EtSH are also included.

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Kinetic model for the decomposition of DMMP in a hydrogen/oxygen flame. Werner, James H.; Cool, Terrill A. School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. Combustion and Flame (1999), 117(1/2), 78-98. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 130:112199 AN 1999:101405 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A kinetic model of the combustion chem. of a hydrogen/oxygen base flame, doped with di-Me methylphosphonate (DMMP), a useful simulant for chem. warfare agents (CWAs), has been developed to assist in the controlled thermal destruction of CWA stockpiles. Laser-ionization mass spectrometry is employed to record concn. profiles of radical intermediates in a low-pressure premixed laminar flame. These measurements, combined with ab initio ests. of thermochem. properties of organophosphorus compds., lead to a kinetic model incorporating several key reaction intermediates, which include Me metaphosphate CH3OPO2, Me dioxophosphorane CH3PO2, and monomethyl methylphosphonate PO(OH)(CH3)(OCH3).

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Deactivation of Mustard and Nerve Agent Models via Low-Temperature Microemulsions. Menger, Fredric M.; Rourk, Michael J. Department of Chemistry, Emory University, Atlanta, GA, USA. Langmuir (1999), 15(2), 309-313. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:164143 AN 1998:796211 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

New low-temp. oil-in-water (O/W) type microemulsions that resist freezing and phase sepn. at -18 have been developed. These systems were shown to simultaneously destroy, via oxidative and hydrolytic mechanisms, simulants of three chem. warfare agents. Reactions, monitored at 25 by gradient elution high-performance liq. chromatog., took place instantly or over many minutes, depending upon the particular simulant. Neglecting reaction products, the low-temp. microemulsions contained 11 components: propylene glycol, water, base, oxidant/nucleophile, surfactant, cosurfactant, oil, stabilizer, two nerve agent simulants, and a mustard simulant. Only by virtue of self-aggregation does this extraordinarily complex chem. system adopt a useful mol. organization and, in this limited sense, the microemulsion chem. resembles what happens in a living cell. Substantial practical issues remain: rates for a recalcitrant VX simulant should be increased and overoxidn. of the mustard simulant to a sulfone retarded. Nonetheless, the new system demonstrates once again the potential of microemulsions in carrying out useful org. reactions at realistic substrate concns. in aq. solvents.

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Treatment for sulfur mustard poisoning - a review. Sugendran, K.; Kumar, Pravin; Vijayaraghavan, R. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1998), 48(2), 155-162. CODEN: DSJOAA ISSN: 0011-748X. Journal; General Review written in English. CAN 130:164031 AN 1998:781689 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review and discussion with 39 refs. Sulfur mustard (SM) is a chem. warfare agent of historical and current interest. It is a well known blistering agent or vesicant. SM was extensively used in world war I as a chem. weapon and has been stockpiled by several countries since that time. SM serves as an ideal war gas and is favored militarily for its ability to incapacitate rather than to kill. Its use resulted in large nos. of casualties requiring prolonged and intensive medical care. Despite Geneva Protocol of 1925, which categorically banned the prodn., stockpiling and use of chem. weapons in wars, SM has been used in several wars, including the Iran-Iraq war during the 1980s, which renewed interest in it. Though, the chem. weapons convention was signed by more than 160 countries in 1993 and was subsequently ratified by several countries, the threat from this agent persists due to its clandestine usage during war and also by terrorist groups. There is no effective and specific antidote for local and systemic toxicity of SM despite scientific research for more than 75 yr. Many compds. were tested as antidotes for SM, but very few of them have been shown to provide some protection. The present review is aimed at evaluating the treatment regime and other clin. measures used to treat SM victims and the various drugs and chems. screened as antidotes for SM poisoning in exptl. animals.

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Evaluation of neutralized chemical agent identification sets (CAIS) for skin injury with an overview of the vesicant potential of agent degradation products. Olajos, E. J.; Olson, C. T.; Salem, H.; Singer, A. W.; Hayes, T. L.; Menton, R. G.; Miller, T. L.; Rosso, T.; MacIver, B. Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1998), 18(6), 409-420. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 130:106238 AN 1998:750883 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Vesication and skin irritation studies were conducted in hairless guinea-pigs to det. the vesicant and skin irritation potential of chem.-neutralized Chem. Agent Identification Sets (CAIS). The CAIS are training items that contain chem. warfare-related material-sulfur mustard (HD), nitrogen mustard (HN) or lewisite (L)-and were declared obsolete in 1971. Animals were dosed topically with "test article"-neat HD, 10% agent/chloroform solns. or product solns. (waste-streams) from neutralized CAIS-and evaluated for skin-damaging effects (gross and microscopic). Product solns. from the chem. neutralization of neat sulfur mustard resulted in microvesicle formation. All agent-dosed (HD or agent/chloroform solns.) sites manifested microblisters as well as other histopathol. lesions of the skin. Waste-streams from the neutralization of agent (agent/chloroform or agent/charcoal) were devoid of vesicant activity. Cutaneous effects (erythema and edema) were consistent with the skin-injurious activity assocd. with the neutralizing reagent 1,3-dichloro-5,5-dimethylhydantoin (DCDMH). Chem. neutralization of CAIS was effective in eliminating/reducing the vesicant property of CAIS contg. agent in chloroform or agent on charcoal but was inefficient in reducing the vesicant potential of CAIS contg. neat sulfur mustard.

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Degradation and fate of mustard in soil as determined by 13C MAS NMR. Wagner, George W.; MacIver, Brian K. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Langmuir (1998), 14(24), 6930-6934. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:91384 AN 1998:713429 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The environmental fate of chem. warfare agents is a current concern, and the notorious persistency of mustard in soil is well-known. The current study utilizes 13C MAS NMR as an in situ method to study the behavior of mustard, and the common simulants 2-chloroethyl Me sulfide (CEMS) and 2-chloroethyl Ph sulfide (CEPS), in a sandy loam soil. Spreading of these water-insol. liqs. and surface sorption on the dry soil particles is observable, as is the recoalescence of liq. droplets and/or hydrolysis in the presence of added water. The relative hydrolysis rates are in agreement with those obsd. in soln. CEMS, possessing the shortest aq. half-life, hydrolyzes without droplet reformation. But mustard and CEPS, possessing much longer aq. half-lives, do not substantially hydrolyze prior to droplet reformation. For mustard, this behavior is crucial to its longevity in soil. Hydrolysis of CEMS and CEPS in the sandy loam soil yields predominately their corresponding alcs., with some ether formation for the latter. Mustard hydrolysis in the sandy loam soil results in the nearly exclusive formation of the branched sulfonium ion HOCH2CH2SCH2CH2S+(CH2CH2OH)2 (CH-TG). A simple model based on droplet size is presented to explain the persistency of mustard in soil.

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Old arsenical munitions: methods for destruction and site cleanup. Beletskaya; Bilger; Boronin; Bunnett; Costantino; Cullen; Dominas; Goessler; Haiduc; Maeda; Martens. Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 177-183. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42626 AN 1998:702909 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 11 refs. concerning methods to destroy and clean-up sites polluted by old arsenical munitions is given. Topics discussed include: spilled arsenical agents (natural chem. transformations in-situ, biotransformation, decontamination of soil contg. arsenical agents, removing polluted soil for treatment elsewhere); destruction of arsenical agents in munition containers or storage tanks (incorporation into concrete, incineration, reactions with alkalies, Na cleavage, hydrogenolysis, novel methods from Russia, oxidn. in water solns., oxidn. under UV irradn., Ag2+ oxidn., other technologies, biodegrdn); and need for research.

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Old "mustard" or yperite munitions: methods for destruction and container detoxification. Koch, E.; Koch, M.; Leslie; Mikolajczyk; Modena; Mulbry; Petrosyan; Sokolowski; Yang. Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 175-176. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42704 AN 1998:702908 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Problems assocd. with disposal of mustard chem. warfare agent, particularly the presence of materials other than the pure chem. compd., bis(2-chloroethyl)sulfide, greatly affects the suitability of processes which may be proposed for their destruction. Thus, destruction of mustard involved the conversion of a multitude of chem. species into material suitable for ultimate disposal; overall destruction also requires the material be presented in the correct form to the reaction stage of the process. Currently, only high temp. oxidn., i.e., incineration, is demonstrated bot be suitable for large-scale destruction of all materials collectively referred to as mustard. For a no. of reasons and public opposition, incineration may not be appropriate or acceptable for destruction of mustard at some locations. Technologies which for one reason or another were not pursued or were disregarded should be reconsidered in light of the wide range of problems that exist for destruction of mustard. Research into clean-up of contaminated sites is also necessary, including bioremediation of soil and chem. transformations in soil.

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Breakdown of sulfur "mustard" by phase transfer catalyzed HCl elimination, A potential destruction method for "mustard" stocks. Koch, Ernst - Christian. ABC- und Selbstschutzschule, Sonthofen, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 169-174. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42625 AN 1998:702907 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 56 refs. concerning sulfur mustard breakdown by phase transfer-catalyzed HCl elimination is given. Topics discussed include: mustard destruction; problem; process results and discussion; summary; instrumentation; and exptl.

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Reductive decomposition of deposits in old "mustard" munitions. Bunnett, Joseph F. University of California, Santa Cruz, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 163-164. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42703 AN 1998:702905 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The nature of gelled or solid deposits in decades-old mustard tanks or munitions is uncertain. Some possibilities which may occur alone or in combination include: polysulfonium salts; poly(ethylenesulfide); elemental S; di- or oligo-sulfide polymers; and Fe compds. from container corrosion. All these structural types are vulnerable to attack by strong reducing agents: Na in liq. NH3; electrochem. cleaving; S reaction with Na; Fe salt redn. by Na; and alkyl halide cleavage by Na. In the lab., conducting such reactions in liq. NH3 is attractive because solns. of Na in NH3 are stable for hours or days. Thus, factory-type installations using Na in liq. NH3 to clean out old mustard munitions with gelled or solid deposits should be feasible. After munitions have been opened and drained of liq. mustard, liq. NH3 could be added followed by pieces of Na metal to react with and destroy the deposits. Munitions so treated would be safe to ship to a furnace to burn out remaining traces. For field situations, a promising alternative is using Na in ethanol; Na reacts with ethanol to release H gas. Addnl. research is needed to confirm that compds. modeling the various suggested structures for gelled or solid mustard are reactive with Na in ethanol as expected.

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Electrochemical and biological approach to the destruction of Lewisite and "Mustard". Boronin, Alexander M.; Sakharovski, Valentin G.; Starovoitov, Ivan I.; Kashparov, Konstantin I.; Shvetsov, Valery N.; Morozova, Ksenija M.; Nechaev, Igor A.; Tugoshov, Vladimir I.; Kuzmin, Nikolai P.; Kochergin, Alexander I. Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 159-162. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42702 AN 1998:702904 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ecol. benign destruction of lewisite and mustard was achieved by electrochem. pretreatment of their neutralization products followed by biol. oxidn. of the waste stream. The process, reaction products, and results are discussed.

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Destruction of Adamsite by sodium. Sokolowski, M.; Bilger, E. Military Institute of Chemistry and Radiometry, Warsaw, Pol. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 157-158. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42701 AN 1998:702903 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sodium destroys chem. weapons, such as adamsite in a liq., dissolved, or gaseous state, with a special form of metallic, high surface Na, either on supports or as a dispersion in oil to yield inorg. Na salts and small org. mols. with little or no toxicity. Adamsite is destroyed by reacting with Na at low and even ambient temps. within a short time. Most of the originally org.-bonded As is transformed into inorg. As (ionic) and therefore can be pptd. as an insol. sulfide. After completing adamsite decompn., water contg. sodium sulfide is added in a closed compartment to initiate hydrolysis of org. Na compds. and ppt. As2S3.

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A method for mutual disposal of old chemical weapons. Chimishkyan, Alexander L. D. Mendeleev University of Chemical Technology, Moscow, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 155-156. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42700 AN 1998:702902 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It is known that HCl destroys adamsite with formation of diphenylamine and AsCl3, and that the reaction of diphenylamine with another toxic agent, phosgene, is a method to produce acridone-9. These two reactions were used for the mutual disposal of adamsite and phosgene. Preliminary results showed the best results are obtained when phosgene is passed through an adamsite/paraffin melt. At the high temp. of the process (190-200), AsCl3 vapors are removed from the reaction mass where acridone-9 accumulates. It was also obsd. that tetraphenylurea is present in the reaction mass. This process guarantees a high yield of AsCl3.

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HPLC-ICP-MS methods for the determination of inorganic and organic arsenic compound. Goessler, W.; Kuehnelt, D.; Irgolic, K. J. Institute for Analytical Chemistry, Karl-Frazens-Universitat, Graz, Austria. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 151-154. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:62116 AN 1998:702901 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To improve the detection limits, a hydraulic high-pressure nebulizer was substituted for the normal pneumatic nebulizer. Chromatog. conditions for the sepn. of inorg. and org. arsenic compds. are identified. Characteristic chromatograms are presented. The combination of the hydraulic high-pressure nebulizer with the inductively coupled plasma mass spectrometer enables the sepn. and detection of arsenic at the sub ng/mL level. These methods can certainly be used to identify and quantify arsenic compds. in soil samples suspected of contamination with arsenic-contg. chem. warfare agents.

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Practical actions of Russia on preparations for destruction of stockpiled Lewisite and "Mustard". Petrov, S. V.; Kholstov, V. I.; Zoubrilin, V. P.; Zavialova, N. V. Ministry Of Defence Of Russian Federation, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 79-90. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42697 AN 1998:702894 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To meet its international obligations while pursuing national policy, Russia has given priority to destroying its chem. warfare agent stockpiles as a major national objective. A mobile chem. warfare agent destruction mobile complex was constructed. It was necessary to first destroy stockpiled mustard-lewisite mixts. stored in high tonnage containers. The next priority is design and construction of a facility for organophosphorus agent destruction. This will be conducted simultaneously with work on blister agent destruction. This required site selection and submission to proper authorities and to the public for approval. Topics discussed include: Russian chem. weapons stockpiles; technol. aspects of lewisite and mustard destruction (lewisite stockpile destruction technologies [S treatment, lewisite interaction with ethylene glycol monomethacrylate ester and its subsequent polymn., chlorination, alk. hydrolysis, alcoholysis, high temp. oxidn., hydrogenolysis, NH3 redn.], mustard stockpile destruction technologies, mustard-lewisite mixts. destruction); and provisions for ecol. safe destruction of stockpiled lewisite and mustard.

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The problem of old chemical weapons which contain "mustard gas" or organoarsenic compounds: an overview. Manley, Ron G. Chemical Demilitarisation Branch, Provisional Technical Secretariat of the Preparatory Commission for the Organisation for the Prohibition of Chemical Weapons, Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 1-16. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42622 AN 1998:702891 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 26 refs. of problems related to old and/or abandoned chem. weapons and the practicalities assocd. with their recovery and safe disposal. Emphasis is placed on weapons contg. either thickened or polymd. mustard gas and/or org. arsenicals, as these pose some of the most difficult disposal problems.

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Cardiorespiratory effects of O-isobutyl S-[2-(diethylamino)-ethyl] methylphosphonothioate - a structural isomer of VX. Chang, F.-C. T.; Gouty, S. C.; Eder, L. C.; Hoffman, B. E.; Maxwell, D. M.; Brecht, K. M. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1998), 18(5), 337-347. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 130:34271 AN 1998:676630 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

O-Iso-Bu S-[2-(diethylamino)ethyl]methylphosphonothioate (VR) is a structural isomer of a more well-known chem. warfare agent, O-Et S-[2-(diisopropylamino)ethyl]methylphosphonothioate (code designation VX). In this study, cardiorespiratory and central nervous system (CNS) effects of VR (2LD50 or 22.6 g kg-1; s.c.) were evaluated in urethane-anesthetized (Group 1) and unanesthetized (Group 2) guinea pigs instrumented for concurrent recordings of electrocorticogram (ECoG) and a variety of cardiorespiratory activities. The first sign of intoxication was a state of progressive bradycardia, vascular hypotension and arrhythmia (Group 1, .apprx. 13 min post-VR; Group 2, .apprx.6 min post-VR). Bradypnea, excessive salivation and compensatory changes in blood pressure typically did not emerge until 3-5 min prior to apnea (Group 1, .apprx.28 min post-VR; Group 2, .apprx.15 min post-VR). An idioventricular rhythm, which signaled a failing myocardium, appeared at the same time or shortly after the development of a bradypneic profile. Another notable toxicity component of VR, based on arterial pH, pO2/pCO2 and bicarbonate (HCO3-) level data, was a state of combined hypercapnia, acidemia and hypoxemia during the development of bradypnea. Taken together, findings from this study indicated that changes in medullary respiratory unit activity and ECoG data displayed little, if any, notable signs of CNS perturbation prior to the terminal stage (.apprx.1 min prior to respiratory failure). Thus, in addn. to displaying a greater sensitivity to perturbation by VR, the peripheral cardiorespiratory system components also appeared to play a more important role in pptg. a progressively dysfunctional cardiorespiratory status that ultimately led to collapse of central respiratory mechanisms and death.

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Gas-phase pyrolysis of diisopropyl methylphosphonate. Zegers, E. J. P.; Fisher, E. M. Sibley Sch. Mechanical and Aerospace Eng., Cornell Univ., Ithaca, NY, USA. Combustion and Flame (1998), 115(1/2), 230-240. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 129:58161 AN 1998:377527 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gas-phase pyrolysis studies of diisopropyl methylphosphonate (DIMP) in nitrogen have been conducted to gain insight into the decompn. behavior of organophosphorus chem. warfare nerve agents. Expts. were conducted in a quartz-lined atm. flow reactor between 700 and 800 K, at residence times ranging from 15 to 90 ms. Propylene, isopropanol, iso-Pr methylphosphonate (IMP), and methylphosphonic acid (MPA) were identified as decompn. products of DIMP. FTIR spectrometry was used to quantify parent, propylene, and isopropanol mole fractions in the reactor. The proposed pyrolysis mechanism for DIMP comprises two stages. The first corresponds to the unimol. decompn. of the parent into IMP and propylene. The second involves two competing pathways for the unimol. decompn. of IMP, one leading to isopropanol and the very reactive Me dioxophosphorane; the other to propylene once again and MPA. In the range of temps. studied, an isopropanol to propylene mole fraction ratio close to 0.25 suggests a branching ratio of 1.5 between these two pathways in favor of propylene prodn. The Arrhenius expression for the unimol. decompn. of DIMP was found to be: k[s-1]=10(12.01.5)[s-1] exp(-36.74.9[kcal.mole-1]/(RT)). Pyrolysis expts. with iso-Pr and t-Bu acetates, which have well-known decompn. rates, were performed to illustrate the ability of the app. to produce valid chem. kinetic data. An investigation of the effects of surface to vol. ratio on the DIMP decompn. process shows that wall reactions are significant in a 4-mm i.d. quartz tube, but less important in an 8-mm i.d. tube. Their effects are expected to be small in the 45-mm i.d. reactor.

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GC/MS screening of alkyl methylphosphonofluoridates and alkyl methylphosphonic acids. Rohrbaugh, Dennis K.; Sarver, Emory W. U.S. Army Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 313-347. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:18255 AN 1997:713947 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gas chromatog.-mass spectrometry (GC-MS) and GC-MS-MS techniques, including electron impact, CH4 chem. ionization, and NH3 chem. ionization, were examd. for their use as potential screening techniques to monitor and detect Schedule 1A1 C1-10-alkyl and cycloalkyl methylphosphonofluoridates and the corresponding Schedule 2 hydrolysis products. These compds. [the methylphosphonofluoridates, of general formula MeP(:O)F(OR), and MeP(:O)OH(OR), R = Et, iso-Pr, iso-Bu, pinacolyl, and cyclohexyl] are, or are derived from, common chem. warfare agents. The base peak for all methylphosphonofluoridates in electron-impact mass spectrometry was at m/e 99. Because of low volatility, the methylphosphonic acids were not amenable to GC anal. However, electron impact mass spectra of their trimethylsilyl (TMS) derivs. gave a base peak at m/e 153 and a dominant peak (10-50% of base peak) at m/e 169 for all compds. Chem. ionization mass spectrometry with CH4 and NH3 can not only be used to also screen samples, but it can give information on mol. wt. of specific compds.

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Possibilities of incorporation of the CO2 DIAL detector into the system of atmospheric quality monitoring associated with storing and destruction of chemical weapons. Kadlcak, J.; Dubina, P.; Safar, B. Military Technical Institute of Protection Brno, Brno, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 255-263. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350239 AN 1997:713942 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The CO2 DIAL system is capable of detecting GB and other chem. warfare agents over a distance of 600 m, theor. up to 3.5 km. In addn., the CO2 DIAL system is able to follow the changes in the concn. of monitored species in a cloud. The detection limit with which the concn. of these compds. could be measured is limited by the min. changes in the differential absorption LIDAR returns that could be distinguished from background fluctuations.

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A data analysis routine to protect confidential information during GC-MS analysis. Mcguire, Raymond R.; Martin, Walter H. Arms Control and Treaty Verification Program Lawrence Livermore National laboratory, Livermore, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 229-240. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:9885 AN 1997:713940 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A shell program, MASK was added to the std. GC-MS data anal. code M CODE to protect confidentiality of information not relevant to the Chem. Weapons Convention. This program was demonstrated to work well where high total ion counts are available. A subroutine for blind background subtraction needs to be added for cases where the peak is only slightly above baseline.

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The application of LC/ES-MS in the OPCW/PTS inter-laboratory comparison test. Peng, Lixin; Xu, Danian. Research Institute of Chemical Defence, Beijing, Peop. Rep. China. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 225-228. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350237 AN 1997:713939 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Structural identification of several Chem. Warfare Convention-related compds., (R)P(O)(OH)2, (CH3)p(O)(OH)(OR), bis(2-chloroethyl)ethylamine, o-cyclopentyl-S-2-(diethylamino)ethylmethylphosphonothiolate, N,N-diethylaminoethanol, and ethyldiethanolamine, using HPLC/emission spectroscopy-mass spectrometry is presented, and the main fragmentation pattern under ES-MS is discussed. LC/ES-MS can det. high wt. mol. and structural anal. of polar, low mol. wt. analytes, esp. phosphonic acid.

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Air monitoring equipment for CW destruction facilities with special emphasis on OCW destruction. Starrock, Volker; Doering, Hans Ruediger. German Armed Forces NBC Defence Establishment, Munster, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 157-180. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350386 AN 1997:713936 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A discussion is given on the air monitoring system in chem. warfare agent destruction site. It includes monitoring system, destruction activities, and anal.

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GCQ GC/MS system: preliminary experiences. Cermak, J. CETA Analytical Department, Research Institute for Organic Syntheses, Pardubice - Rybitvi, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 133-146. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350634 AN 1997:713934 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A discussion is given on the GC/MS system in relation to destruction of chem. warfare agents.

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GC/MS investigation of Ethyl S-2-diisopropyl aminoethyl methylphosphonothiolate (VX) age decomposition products. Sliwakowski, M. Military Institute of Chemistry and Radiometry, Warsaw, Pol. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 127-132. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:39042 AN 1997:713933 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sample of VX stored for a long time in glass container was investigated using GC/MS system. A variety of age decompn. products including O-alkyl and N,N-diisopropylamino- substituted thiophosphonic esters and acids as well as phosphonic anhydrides were identified. Diazomethane methylation was used to obtain derivs. convenient to GC process. Retention parameters and EI-MS spectra were obtained and presented.

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Chemical ionization and electron impact mass spectrometry of some methylphosphonothiolates. Podborsky, V.; Stein, V. Military Technical Institute of Protection, Brno, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 109-125. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:3728 AN 1997:713932 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mass spectrometric data of 18 organophosphorus compds. from the family of V-agents were studied. MS spectra of S-2-dimethyl-, S-2-diethyl-, S-2-dipropyl-, S-2-diisopropyl- and S-2-dibutylaminoethyl O-alkyl methylphosphonothiolates were measured in EI and CI modes. MS spectra were completed with some toxicol. data of these organophosphorus compds.

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Application of some modern sample introduction techniques and Poraplot Q GC column in the analysis of volatile toxic compounds. Bardarov, V.; Tashkov, V. Military Medical Academy, Sofia, Bulg. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 77-97. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350235 AN 1997:713929 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. of toxic substances is difficult due to the complexity of the matrixes and usual requirements of multi-component anal. leading to application of chromatog. sepn. The greatest part of chem. warfare agents, their precursors, and degrdn. products demonstrate significant vapor pressure and cause measurable concns. in the gaseous environment at ambient or slightly increased temps. This results in problems for sampling and sample prepn., but favorable distribution of analytes and matrix components among the matrix or suitable sorbent and the gaseous environment may occur and can be used in some techniques to combine sampling, sample prepn., and sample introduction when analyzed using gas chromatog. These techniques, headspace, thermodesorption, and gas extn., realized using different instrument variants in combination with gas chromatog. sepn., are discussed.

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On-site sample work-up procedures to isolate chemical warfare related compounds using solid phase extraction and solid phase microextraction technology. Alcaraz, A.; Hulsey, S. S.; Whipple, R. E.; Andresen, B. D. Lawrence Livermore National Laboratory, Forensic Science Center, Livermore, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 65-76. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350879 AN 1997:713928 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To rapidly prep. and accurately analyze suspect samples for on-site investigations of chem. warfare agents, new methods and field portable equipment, including collection, prepn., and anal. of suspect samples, were required. Using solid phase extn., sample prepn. time was greatly reduced and cumbersome lab. equipment was eliminated. Three different portable modules to achieve on-site field anal. capability were developed. The first consisted of pre-cleaned, sealed sample collection equipment capable of obtaining any type of sample. The second module allowed for complete chem. work-up of collected samples to prep. them for instrumental anal. The third module contained anal. instrumentation necessary for chem. identification, including gas chromatog.-flame photometric detection and gas chromatog.-mass spectrometry for pos. compd. identification. Two field exercises were conducted to provide information on detection limits of on-site anal. approach for soil, water, and swipe samples. Both exercises showed the on-site anal. equipment can be easily deployed. All chem. warfare-related compds. were readily identified using the solid phase extn. technol. and portable anal. equipment. Results were later confirmed by analysts in inhouse labs.

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Super Toxic Analytical Glovebox System (STAGS). Henry, Charles E.; Heyl, Monica; Reutter, Dennis; Diez, Hernan; Landy, Keith. U.S. ARMY, ERDEC, AMC Treaty Laboratory, AMSCB-ACL, APG-EA, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 59-63. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350413 AN 1997:713927 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The US Army was directed to dispose of the stockpile of unitary chem. weapons by Public Law 99-145 and subsequent amendments. This stockpile consists primarily of the agents, VX, HD, and GB, contained in a variety of munitions and bulk containers. To minimize the total risk to the public and the environment posed by chem. weapons storage and disposal, the National Research Council recommended the Army continue the current baseline incineration program while evaluating alternative technologies as replacements for the liq. incinerator used in agent destruction. To accomplish research necessary to det. the efficiency of neutralization, field grade chem. agents were characterized on-site in their natural environment. An on-site purity anal. for ton container survey at 3 storage sites was conducted. Super toxic anal. glovebox system (STAGS), an anal. equipment platformed within a regulated enclosure was designed to successfully perform super toxic work in the field. Development and initial testing of STAGS is discussed.

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Analytical control for destruction of chemical weapons. Requirements and organization. Myasoedov, B. F. V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 39-58. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350412 AN 1997:713926 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An effectively operating anal. control system for chem. weapons destruction in Russia is discussed. The Russian chem. weapons stockpile identified for destruction includes V-gas, sarin, soman, mustard gas, lewisite, and mustard gas-lewisite mixts. amounting to 40,000 tons of chem. warfare agents. Key problems include safety provisions for humans and the environment regarding chem. weapons storage, transportation, and destruction; neutralization of detoxification products; use of solid wastes; and physicochem. parameters of chem. warfare prodn. testing; and disposal of chem. warfare agents and sites. To meet these requirements, an effective system of anal. control coupled with a computer-assisted information system capable of providing expert with high quality reliable data is essential. The operation and elements of this control system are discussed.

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Development of analytical technologies for the alternatives to incineration program. Reutter, Dennis J.; Sumpter, Kenneth; Vickers, Eugene; Simak, Richard; Henry, Charles; Hoffland, Lynn; Smith, Philip B.; Brickhouse, Mark. U.S. Army, ERDEC, AMC Treaty Laboratory, AMSCB-ACL, APG-EA, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 27-38. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:336178 AN 1997:713925 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various aspects of the destruction of chem. weapons are discussed using VX as an example including the development of anal. technologies for the alternatives to incineration program .

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Project SWIFTSURE: destruction of chemical agents at Defense Research Establishment Suffield. Mcandless, John M.; Boulet, Camille A. Defence Research Establishment Suffield, Medicine Hat, AB, Can. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 1-14. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 127:350492 AN 1997:713923 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 11 refs., on the project location, waste inventory, operational concept, environmental monitoring, and destruction of chem. agents.

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Pyrethroid decrease in central nervous system from nerve agent pretreatment. Buchholz, Bruce A.; Pawley, Norma H.; Vogel, John S.; Mauthe, Robert J. Lawrence Livermore National Laboratory, Livermore, CA, USA. Journal of Applied Toxicology (1997), 17(4), 231-234. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 127:172426 AN 1997:560828 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors studied the effect of pyridostigmine bromide, a nerve agent prophylactic, on the central nervous system (CNS) uptake of [14C]permethrin, a pyrethroid insecticide, at scaled human-equiv. exposures in rats using accelerator mass spectrometry (AMS). AMS detects 14C at attomole sensitivities and dets. the tissue distribution of 14C-labeled compds. Pyridostigmine bromide in chow at 7.75 mg kg-1 per day lowered the CNS tissue levels of permethrin, dosed at 4.75 g kg-1, in the CNS of rats by 30%. These results are inconsistent with hypothesized synergy of such compds. as a precursor to "Gulf War syndrome".

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Sulchem process for treatment of chemical weapons-related wastes. Berkey, Edgar; Paff, Stephen W.; King, A. Bruce. Center for Hazardous Materials Research, University of Pittsburgh Applied Research Center, Pittsburgh, PA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 129-148. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:180466 AN 1997:545010 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The Sulchem process is a chem. treatment process that uses elemental S at elevated temps. in an O-free environment to clean up soil contaminated with org. and metallic waste. The process relies on the high reactivity of S and its ability to oxidize org. compds. rapidly and non-selectively at reaction conditions. Org. compds. react with the S to form an inert fine solid of C and S, as well as a variety of simple gases whose compn. varies with the waste material being treated. Byproduct gases may be scrubbed or treated to recover elemental S using an auxiliary process unit. Heavy metals contained in the soil react to form insol. sulfides that become immobilized. The process is potentially applicable to a variety of chem. weapons-related wastes, including soil contaminated with chem. agents, nerve agents, or energetics. The Sulchem process is operated as a 2-stage system at 300-350. Org. compds. that are not volatilized from the soil are completely destroyed in the 1st reactor, in which the insol. metallic sulfides are also formed. A 2nd stage S/vapor reactor is used to destroy orgs. desorbed from the soil reactor. A series of bench-scale and pilot-scale test have been conducted that support feasibility of the process. Projected remediation costs using the process are estd. at $105-$183/ton based on site size, reactor configuration, and processing rate.

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The application of the Silver II electrochemical oxidation process for the demilitarization of non-stockpile material. Batey, W.; Warren, N. AEA Technology, Caithness, UK. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 103-127. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:194862 AN 1997:545009 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The Silver II Process is a recognized alternative technol. to incineration for the demilitarization of chem. munitions. This paper describes an integrated electrochem. cutting method for the breakdown of munitions with the Silver II Process being used to demilitarize the recovered org. material and decontaminate the shell casing. The Silver II Process is a low temp. and pressure electrochem. oxidn. process which stops when the electrochem. cell current is stopped. The offgases comply with environmental discharge stds. All liq. wastes are stored on-site pending return to a central depot for regeneration. The liq. wastes from the regeneration plant are discharged at the central depot once they have been confirmed to be free of chem. agent. The proposed concept provides a mobile soln. for the demilitarization of recovered buried conventional and chem. weapons. The concept is applicable to the remediation of small and large formerly used defense sites.

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Chemical detoxification of chemical weapons applying sodium-technology. Bilger, Edgar. c/o Dr. Bilger Umweltconsulting GmbH, Freigericht, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 71-82. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:194861 AN 1997:545008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A cost-effective chem. method to destroy chem. weapons in a mobile unit using Na is described. Case studies for the destruction of Adamsite or mustard are highlighted. Using Na technol., the chem. can be controlled and analyses can be made at any stage of treatment since all substances are kept in closed compartments until the products are released after thorough final anal. Advantages of the Na technol. include: low temp.; chem. weapon mineralization; low investment cost; inexpensive reagents; no formation of dioxins or furans (vs. incineration); prodn. of solid or dissolved reaction products; no hazardous gases released; and mobile detoxification units.

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Cryofracture as a mobile demilitarization technology for non-stockpile chemical munitions. Spritzer, M. H.; Johnson, L. D. General Atomics, San Diego, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 19-39. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:180485 AN 1997:545005 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Cryofracture is a demilitarization process that has been under development for chem. agent munitions for over 12 yr. Cryofracture uses liq. N to pre-cool munitions prior to fracturing in a hydraulic press. Cryofracture exposes the chem. agents and explosives for subsequent destruction by other means such as thermal or chem. treatment. The cryofracture process is designed to demilitarize projectiles, cartridges, mortar rounds, mines and rockets. Over $60 million has been spent by the US Army to develop cryofracture for demilitarization of chem. agent munitions stored at stockpile sites in the US. Extensive tests have been performed with live explosives and simulant agents, and the test results verify all key aspects of the process. More recently, the cryofracture process has been applied to conventional munitions with the same good results. The process is also likely to find application for non-stockpile chem. munitions in the US and throughout the world. A description of the process and the results of extensive testing are presented, with particular emphasis on the adaptation of cryofracture to non-stockpile chem. munitions.

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Radial Heterogeneity of Impregnated Active Carbon Particles. Buczek, B.; Zietek, S.; Swiatkowski, A. University of Mining and Metallurgy, Krakow, Pol. Langmuir (1997), 13(5), 1342-1344. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 126:122909 AN 1997:126980 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Texture and sorptive properties of the active carbon, before and after impregnation with the soln. of Cr, Cu, and Ag salts, were investigated. Initial active carbon and the impregnated one were sep. subjected to abrasion in a spouted bed, thus obtaining core samples with different degrees of external layers removed. They were analyzed by means of densimetry, mercury porosimetry, and adsorption techniques. The pore vol. was detd. from measurements of true and real densities. Mercury porosimetry was used to est. vol. pores in the macropore range. Mesopore and micropore structures were detd. using benzene adsorption/desorption isotherms. Both the active carbon and impregnated active carbon showed radial changes in the micro-, meso-, and macropore structure. For impregnated active carbon samples the amt. of deposited material and sorption of ClCN were measured. The outer regions of particles were richer in active material whose distribution was analyzed. Samples with removed external layers exhibited substantially higher protective efficiency against cyanogen chloride.

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Comparative evaluation of benzodiazepines for control of soman-induced seizures. McDonough J H Jr; McMonagle J; Copeland T; Zoeffel D; Shih T M Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Archives of toxicology (1999 Nov), 73(8-9), 473-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10650919 AN 2000114341 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This study evaluated the ability of six benzodiazepines to stop seizures produced by exposure to the nerve agent soman. Guinea pigs, previously prepared with electrodes to record electroencephalographic (EEG) activity, were pretreated with pyridostigmine (0.026 mg/kg, i.m.) 30 min before challenge with soman (56 microg/kg, s.c.) and then treated 1 min after soman exposure with atropine (2.0 mg/kg, i.m.) and pralidoxime chloride (2-PAM Cl; 25 mg/kg, i.m.). All animals developed seizures following this treatment. Benzodiazepines (avizafone, clonazepam, diazepam, loprazolam, lorazepam, and midazolam) were given i.m. 5 or 40 min after seizure onset. All benzodiazepines were effective in stopping soman-induced seizures, but there were marked differences between drugs in the rapidity of seizure control. The 50% effective dose (ED50) values and latencies for anticonvulsant effect for a given benzodiazepine were the same at the two times of treatment delay. Midazolam was the most potent and rapidly acting compound at both treatment times. Since rapid seizure control minimizes the chance of brain damage, use of midazolam as an anticonvulsant may lead to improved clinical outcome in the treatment of nerve agent seizures.

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Sulphur mustard induced DNA damage in mice after dermal and inhalation exposure. Lakshmana Rao P V; Vijayaraghavan R; Bhaskar A S Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India. drde@gwr1.dot.net.in Toxicology (1999 Nov 29), 139(1-2), 39-51. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10614687 AN 2000080350 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulphur mustard (SM) is a chemical warfare agent of the blistering agent category for which there is still no effective therapy. SM, being a strong electrophile, readily reacts with a wide range of cellular macromolecules including DNA, RNA and protein. Since the main intoxication routes for SM are inhalation and dermal penetration, in the present study we have exposed female mice to different concentrations of SM by dermal and inhalation exposures and estimated the DNA damage in different organs viz., liver, lung, spleen and thymus. SM was applied at 38.7, 77.4, 154.7 mg/kg body weight, on the hair-clipped skin (dermal exposure) equivalent to 0.25, 0.5 and 1.0 of the LD50. Inhalation exposure was carried out at 10.6, 21.2 and 42.3 mg/m3 for 1 h duration equivalent to 0.25, 0.5 and 1.0 LC50. SM induced a dose-dependent DNA damage in all the organs except the lung in dermal exposure. Similarly the inhalation exposure resulted in dose- and time-dependent effect in all the organs including lung. By both routes of exposure liver was the most affected organ followed by spleen, thymus and lung in decreasing order. The quantitative data were corroborated by qualitative analysis of DNA on agarose gel electrophoresis. The genomic DNA analysis of the organs had revealed random nuclear DNA fragmentation resulting in a 'smear' typical of necrotic form of cell death. Since DNA damage is not reversible especially in liver, this can be used as a marker for SM exposure through either the dermal or inhalation route.

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Development of reactive topical skin protectants against sulfur mustard and nerve agents. Koper O; Lucas E; Klabunde K J Nantek, Inc., 1500 Hayes Drive, and Department of Chemistry, Kansas State University, Manhattan, KS 66502, USA Journal of applied toxicology : JAT (1999 Dec), 19 Suppl 1 S59-70. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10594903 AN 2000062800 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The potential for highly reactive nanoparticles (RNP) to absorb destructively, i.e. to neutralize highly toxic substances such as the warfare agents GA, GB, HD and VX, has been demonstrated in the laboratory. Reactive nanoparticles represent a new class of nanoscale particles of metals and metal oxides that differ from other nanoparticles in reactivity and crystalline morphology. The potential for incorporating RNP into a protective barrier skin cream also has been demonstrated. Preliminary studies indicate that RNP are physically and chemically compatible with a base cream provided by the Army Medical Research Office and, importantly, remain reactive with chemical agents while promising to be compatible with skin contact. Copyright 1999 John Wiley & Sons, Ltd.

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Efficacy of the topical skin protectant in advanced development. Liu D K; Wannemacher R W; Snider T H; Hayes T L US Army Medical Material Development Activity, 622 Neiman Street, Fort Detrick, MD 21702-5009, USA Journal of applied toxicology : JAT (1999 Dec), 19 Suppl 1 S40-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10594900 AN 2000062797 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A topical skin protectant (TSP) (ICD 2289) is being developed to protect service members from exposure to chemical warfare agents (CWA). The TSP is designed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clinical studies, is a cream containing two chemically inert substances: perfluoroalkylpolyether and polytetrafluoroethylene. Animal data showed that the TSP was effective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by preventing the development of erythema and edema. The insect repellent N,N-diethyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protection was sustained when DEET was removed with a dry gauze prior to TSP application. The TSP was also effective against percutaneous exposure of nerve agents-thickened (with 5% methyl methacrylamide) soman (TGD) and VX (O-ethyl-S-[2-(diisopropylamino)ethyl]methylphosphonothioate )-by reducing the mortality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when DEET was applied prior to TSP application. Because human efficacy studies using CWA cannot be conducted, the efficacy will be demonstrated by the level of protection against poison ivy (urushiol) contact dermatitis in humans.

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Two-generation reproduction study of lewisite in rats. Sasser L B; Cushing J A; Lindenmeier C W; Mellick P W; Dacre J C Molecular Bioscience Department, Battelle, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1999 Jul-Aug), 19(4), 229-35. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10439336 AN 1999368191 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Lewisite, a potent toxic vesicant and chemical warfare agent, is used in a number of research laboratories, is stored in large quantities at depot sites throughout the USA and is occasionally transported to distant sites. Thus, the potential for environmental or occupational exposure exists where lewisite is present. A 42-week two-generation study was conducted to determine the reproductive consequences of lewisite in parental male and female rats and their offspring. Rats were administered lewisite in sesame oil (0, 0.10, 0.25 or 0.60 mg kg-1 day-1 for 5 days a week) via intragastic intubation before mating, during mating and after mating until the birth of their offspring. The dams continued to receive lewisite during lactation. At weaning, male and female offspring of each group were selected to continue the study, receiving lewisite during adolescence, mating and throughout gestation and lactation. Lewisite had no adverse effect on reproduction performance, fertility or reproductive organ weights of male or female rats through two consecutive generations. No adverse effects to offspring were attributed to lewisite exposure. Minor changes in growth were the only maternal effects observed. Lewisite exposure of parental rats caused no gross or microscopic lesion in testes, epididymis, prostate, seminal vesicles, ovaries, uterus or vagina. The no-observable-effect level (NOEL) for the reproductive effects of Lewisite would be > 0.60 mg kg-1 day-1.

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Effect of lowered temperature on the toxicity of sulphur mustard in vitro and in vivo. Sawyer T W; Risk D Therapy Group, Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada. thomas.sawyer@dres.dnd.ca Toxicology (1999 May 3), 134(1), 27-37. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10413186 AN 1999339531 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Primary cultures of chick embryo neurons were exposed to sulphur mustard (HD) and L-nitroarginine methyl ester (L-NAME) and then incubated at either 25 or 37 degrees C. Lowering the temperature of the cultures decreased the 24-h toxicity of HD, but did not increase the efficacy of L-NAME protection. However, the length of time post-HD treatment in which L-NAME was maximally effective in protecting against HD toxicity was dramatically enhanced, out to 12 h after HD exposure. In addition, the persistence of L-NAME protection of the cells against HD was significantly lengthened. Tests conducted in human skin keratinocytes also showed that lowering the incubation temperature of actively proliferating, just-confluent or post-confluent cultures significantly and persistently decreased the cytotoxicity of HD. The persistence of L-NAME protection was increased in non-proliferating cells. Finally, cooling of HD-vapour exposed sites on hairless guinea pigs for 4.5 h decreased the severity of the resultant lesions out to 72 h post-exposure.

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The interaction of sarin and soman with plasma proteins: the identification of a novel phosphonylation site. Black R M; Harrison J M; Read R W DERA, CBD Porton Down, Salisbury, Wilts, UK Archives of toxicology (1999 Mar), 73(2), 123-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10350193 AN 1999277696 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Incubation of both sarin and soman with human plasma has shown that binding occurs to a tyrosine residue. Similar binding occurs when sarin and soman are incubated with human serum albumin. This binding may provide an important biological marker, which retains full structural information concerning the identity of the agent, in cases of allegations of chemical warfare use.

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Acute soman poisoning in primates neither pretreated nor receiving immediate therapy: value of gacyclidine (GK-11) in delayed medical support. Lallement G; Clarencon D; Galonnier M; Baubichon D; Burckhart M F; Peoc'h M Unite de Neuropharmacologie, CRSSA-BP, La Tronche, France. 100437,201@compuserve.com Archives of toxicology (1999 Mar), 73(2), 115-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10350192 AN 1999277695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Organophosphorus (OP) nerve agents are still used as warfare and terrorism compounds. Classical delayed treatment of victims of organophosphate poisoning includes combined i.v. administration of a cholinesterase reactivator (an oxime), a muscarinic cholinergic receptor antagonist (atropine) and a benzodiazepine anticonvulsant (diazepam). The objective of this study was to evaluate, in a realistic setting, the therapeutic benefit of administration of GK-11 (gacyclidine), an antiglutamatergic compound, as a complement to the above therapy against organophosphate poisoning. Gacyclidine was injected (i.v.) in combination with atropine/diazepam/pralidoxime at man-equivalent doses after a 45- or 30-min latency period to intoxicated primates (2 LD50). The effects of gacyclidine on the animals' survival, electroencephalographic (EEG) activity, signs of toxicity, recovery after challenge and central nervous system histology were examined. The present data demonstrated that atropine/diazepam/pralidoxime alone or combined with gacyclidine did not prevent signs of soman toxicity when treatment was delayed 45 min after poisoning. Atropine/diazepam/pralidoxime also did not control seizures or prevent neuropathology in primates exhibiting severe signs of poisoning when treatment was commenced 30 min after intoxication. However, in this latter case, EEG recordings revealed that additional treatment with gacyclidine was able to stop soman-induced seizures and restore normal EEG activity. This drug also totally prevented the neuropathology observed 5 weeks after soman exposure in animals treated with atropine/diazepam/pralidoxime alone. Overall, in the case of severe OP-poisoning, gacyclidine represents a promising adjuvant therapy to the currently available polymedication to ensure optimal management of organophosphate poisoning in man. This drug is presently being evaluated in a human clinical trial for a different neuroprotective indication.
However, it should always be kept in mind that, in the case of severe OP-poisoning, medical intervention must be conducted as early as possible.

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Evaluation of neutralized chemical agent identification sets (CAIS) for skin injury with an overview of the vesicant potential of agent degradation products. Olajos E J; Olson C T; Salem H; Singer A W; Hayes T L; Menton R G; Miller T L; Rosso T; MacIver B Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD 21010, USA Journal of applied toxicology : JAT (1998 Nov-Dec), 18(6), 409-20. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9840748 AN 1999054483 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Vesication and skin irritation studies were conducted in hairless guinea-pigs to determine the vesicant and skin irritation potential of chemically-neutralized Chemical Agent Identification Sets (CAIS). The CAIS are training items that contain chemical warfare-related material--sulfur mustard (HD), nitrogen mustard (HN) or lewisite (L)--and were declared obsolete in 1971. Animals were dosed topically with 'test article'--neat HD, 10% agent/chloroform solutions or product solutions (waste-streams) from neutralized CAIS--and evaluated for skin-damaging effects (gross and microscopic). Product solutions from the chemical neutralization of neat sulfur mustard resulted in microvesicle formation. All agent-dosed (HD or agent/chloroform solutions) sites manifested microblisters as well as other histopathological lesions of the skin. Waste-streams from the neutralization of agent (agent/chloroform or agent/charcoal) were devoid of vesicant activity. Cutaneous effects (erythema and edema) were consistent with the skin-injurious activity associated with the neutralizing reagent 1,3-dichloro-5,5-dimethylhydantoin (DCDMH). Chemical neutralization of CAIS was effective in eliminating/reducing the vesicant property of CAIS containing agent in chloroform or agent on charcoal but was inefficient in reducing the vesicant potential of CAIS containing neat sulfur mustard.

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Inhibition, reactivation and aging kinetics of cyclohexylmethylphosphonofluoridate-inhibited human cholinesterases. Worek F; Eyer P; Szinicz L Institut fur Pharmakologie und Toxikologie, Sanitatsakademie der Bundeswehr, Garching, Germany Archives of toxicology (1998 Sep), 72(9), 580-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9806430 AN 1999021267 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (cyclosarin) is a highly toxic organophosphate, which was shown to be rather resistant to conventional oxime therapy. To give more insight into the inhibition, reactivation and aging kinetics, human acetyl-(AChE) and butyrylcholinesterase (BChE) were inhibited by cyclosarin (k2 of 7.4 and 3.8 x 10(8) M(-1) min(-1), respectively; pH 7.4, 37 degrees C) and reactivated with obidoxime, pralidoxime and three experimental oximes. The new oxime HLo 7 (1-[[[4-aminocarbonyl)-pyridinio]-methoxy]-methyl]-2,4-bis-[ (hydroxyimino)methyl] pyridinium dimethanesulphonate) was shown to be superior to the other oximes. At oxime concentrations anticipated to be relevant in humans, obidoxime and pralidoxime were extremely weak reactivators of AChE. Aging velocity of BChE was almost fourfold higher compared to AChE (ka of 0.32 h(-1) and 0.08 h(-1), respectively). A substantial spontaneous reactivation was observed with AChE. These results support previous in vivo findings that obidoxime and pralidoxime are insufficient antidotes in cyclosarin poisoning. By contrast, HLo 7 was shown to be an extremely potent reactivator of human AChE and BChE, which supports its position as a broad-spectrum oxime.

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Acute inhalation toxicity of neutralized chemical agent identification sets (CAIS) containing agent in chloroform. Olajos E J; Morgan E W; Renne R A; Salem H; McVeety B; Johnson R; Phelps R L Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD 21010-5423, USA Journal of applied toxicology : JAT (1998 Sep-Oct), 18(5), 363-71. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9804437 AN 1999019582 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

An acute head-only inhalation study was conducted in rats exposed for 1 h to product solution (wastestream) resultant from the chemical neutralization of Chemical Agent Identification Sets (CAIS) containing agent (sulfur mustard (HD), nitrogen mustard (HN-1) or lewisite (L)) in chloroform. Groups of Sprague-Dawley rats were exposed to varying concentrations (24000, 18000, 12000 or 6000 ppm) of CAIS wastestream. An additional group was exposed to the vehicle (chloroform/t-butanol) only, at a concentration equivalent to the concentration of vehicle at the highest exposure level. Animals were evaluated for toxic effects, including assessment of toxicant-induced alterations to the ocular and respiratory systems. Mortality on exposure to 24000 ppm of test article or to vehicle alone was high. Mortality in the other exposure groups was roughly proportional to the concentration of test article (wastestream). Toxic signs were consistent with exposure to solvent system components (chloroform/t-butanol) and to agent decomposition products/by-products. Incidence and severity of ocular effects were similar in vehicle control and treatment groups. The salient respiratory effect observed was a decreased minute volume, which was also noted in vehicle and treatment groups.

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Cardiorespiratory effects of O-isobutyl S-[2-(diethylamino)-ethyl] methylphosphonothioate -- a structural isomer of VX. Chang F C; Gouty S C; Eder L C; Hoffman B E; Maxwell D M; Brecht K M US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1998 Sep-Oct), 18(5), 337-47. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9804434 AN 1999019579 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

O-Isobutyl S-[2-(diethylamino)ethyl]methylphosphonothioate (VR) is a structural isomer of a more well-known chemical warefare agent, O-ethyl S-[2(diisopropylamino)ethyl]methylphosphonothioate (code designation VX). In this study, cardiorespiratory and central nervous system (CNS) effects of VR (2LD50 or 22.6 microg kg(-1); s.c.) were evaluated in urethane-anesthetized (Group 1) and unanesthetized (Group 2) guinea pigs instrumented for concurrent recordings of electrocorticogram (ECoG) and a variety of cardiorespiratory activities. The first sign of intoxication was a state of progressive bradycardia, vascular hypotension and arrhythmia (Group 1, approximately 13 min post-VR; Group 2, approximately 6 min post-VR). Bradypnea, excessive salivation and compensatory changes in blood pressure typically did not emerge until 3-5 min prior to apnea (Group 1, approximately 28 min post-VR; Group 2, approximately 15 min post-VR). An idioventricular rhythm, which signalled a failing myocardium, appeared at the same time or shortly after the development of a bradypneic profile. Another notable toxicity component of VR, based on arterial pH, pO2/pCO2 and bicarbonate (HCO3-) level data, was a state of combined hypercapnia, acidemia and hypoxemia during the development of bradypnea. Taken together, findings from this study indicated that changes in medullary respiratory unit activity and ECoG data displayed little, if any, notable signs of CNS perturbation prior to the terminal stage (approximately 1 min prior to respiratory failure). Thus, in addition to displaying a greater sensitivity to perturbation by VR, the peripheral cardiorespiratory system components also appeared to play a more important role in precipitating a progressively dysfunctional cardiorespiratory status that ultimately led to collapse of central respiratory mechanisms and death.

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Effect of sulphur mustard inhalation exposure on some urinary variables in mice. Kumar O; Vijayaraghavan R Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India Journal of applied toxicology : JAT (1998 Jul-Aug), 18(4), 257-9. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9719425 AN 1998383930 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The effect of sulphur mustard (2,2'-dichlorodiethyl sulphide) exposure through inhalation at 0.5. 1.0 and 2.0 LC50 (21.2, 42.3 and 84.6 mg m(-3) for 1 h) on some urinary variables was studied in female mice at 6, 24 and 48 h and 7 days post-exposure. The urinary excretion and circulatory blood accumulation of uric acid increased significantly. The level of creatine was also elevated significantly as compared to the control at 2 LC50. It is concluded that sulphur mustard alkylates DNA and triggers catabolism of apurinated purine bases in a very short time. The increase in uric acid excretion in urine can be detected only when the exposure concentration is high.

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Nerve agent poisoning in primates: antilethal, anti-epileptic and neuroprotective effects of GK-11. Lallement G; Clarencon D; Masqueliez C; Baubichon D; Galonnier M; Burckhart M F; Peoc'h M; Mestries J C Unite de Neurotoxicologie, CRSSA, La Tronche, France Archives of toxicology (1998), 72(2), 84-92. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9456079 AN 1998115614 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Organophosphorus nerve agents are still in use today in warfare and as terrorism compounds. Classical emergency treatment of organophosphate poisoning includes the combined administration of a cholinesterase reactivator (an oxime), a muscarinic cholinergic receptor antagonist (atropine) and a benzodiazepine anticonvulsant (diazepam). However, recent experiments with primates have demonstrated that such treatment, even when administered immediately after organophosphate exposure, does not rapidly restore normal electroencephalographic (EEG) activity and fails to totally prevent neuronal brain damage. The objective of this study was to evaluate, in a realistic setting, the therapeutic benefit of administration of GK-11 (gacyclidine), an antiglutamatergic compound, as a complement to the available emergency therapy against organophosphate poisoning. GK-11 was injected at a dose of 0.1 mg/kg (i.v) after a 45-min latency period to heavily intoxicated (8 LD50) primates. Just after intoxication, man-equivalent doses of one autoinjector containing atropine/pralidoxime/diazepam were administered. The effects of GK-11 were examined on survival, EEG activity, signs of toxicity, recovery after challenge and central nervous system histology. The present data demonstrate that treatment with GK-11 prevents the mortality observed after early administration of classical emergency medication alone. EEG recordings and clinical observations also revealed that GK-11 prevented soman-induced seizures and motor convulsions. EEG analysis within the classical frequency bands (beta, theta, alpha, delta) demonstrated that central activity was totally restored to normal after GK-11 treatment, but remained profoundly altered in animals receiving atropine/pralidoxime/diazepam alone. GK-11 also markedly accelerated clinical recovery of soman-challenged primates. Lastly, this drug totally prevented the neuropathology observed 3 weeks after soman exposure in animals treated with classical emergency treatment alone.
GK-11 represents a promising adjuvant therapy to the currently available emergency polymedication to ensure optimal management of organophosphate poisoning in man. This drug is presently being evaluated in a human clinical trial for a different neuroprotective indication.

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A model for quantitative measurement of sulfur mustard skin lesions in the rabbit ear. Zlotogorski A; Goldenhersh M; Shafran A Department of Dermatology, Hadassah University Hospital, Jerusalem, Israel. zloto@cc.huji.ac.il Toxicology (1997 Jun 27), 120(2), 105-10. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9184197 AN 97327530 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The search for treatment and protection against the vesicant and inflammatory skin lesions induced by sulfur mustard suffers from the lack of a good in vivo reproducible model. We applied sulfur mustard (25-500 microg/cm2) to the outer surface of the ears of 10 rabbits and measured the edema formation 12, 24 and 48 h post-application with a caliper especially designed for soft matter. There was a dose-dependent linear increase in edema magnitude in the range from 25 to 150 microg/cm2. Maximal edema was observed after 12 h. There was a 12% reduction in edema size 24 h after application and a further decrease after 48 h. Skin thickness, inflammatory cell infiltrate, necrosis and vesiculation were evaluated in biopsies taken after 24 h. We found the same dose-related increase both in skin thickness and in degree of blister formation. This simple dose-response in vivo model can be used for evaluation of the dermal inflammation induced by topical application of sulfur mustard. This model has the additional advantage of a built-in control, namely the untreated contralateral ear. Consequently, this model can serve as a useful tool for future screening of potential compounds for prevention and treatment of sulfur mustard-induced skin lesions.

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Effect of sulphur mustard on the expression of urokinase in cultured 3T3 fibroblasts. Detheux M; Jijakli H; Lison D Laboratory of Medical Toxicology, Catholic University of Louvain, Brussels, Belgium Archives of toxicology (1997), 71(4), 243-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9101041 AN 97255694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The expression of plasminogen activator (PA), a serine proteinase involved in the degradation of extracellular matrix proteins, has been investigated in 3T3 fibroblasts after in vitro exposure to sulphur mustard (SM). Expression of the cell-associated enzyme has been assessed with a synthetic substrate assay and at the mRNA level. Twenty-four hours after 100 microM SM, cell viability (monitored by MTT assay) was not significantly affected, but protein synthesis (tritiated leucine incorporation) was reduced to < 20% of the control value. PA activity was significantly increased compared to control cells with a 20-fold increase after 24 h. This up-regulation was independent of the cell density, occurred maximally between days 1 and 4 and persisted for at least 6 days after exposure. Lower concentrations of SM (< or = 10 microM) did not significantly affect PA activity. Northern blotting experiments revealed an increased expression of urokinase (u-PA) transcripts in cells treated with 100 microM SM, with a peak at 10 h after exposure. Conditioned culture medium from cell cultures treated with 100 microM SM did not affect the expression of PA activity in naive or SM-treated cultures. Thiodiglycol (100 microM), the main metabolite of SM, did not influence the expression of PA in the same system. Different compounds were tested for modulation of the PA upregulation after SM exposure. Nicotinamide (5 mM), vitamin D3 (10(-10)M), extracellular calcium (2 mM) or EGTA (5 mM) had no effect. Ryanodine (10 microM) amplified the PA up-regulation by a factor of 2 and vanadate (500 microM) reduced it by approximately 50%. Dexamethasone (1 microM) added directly after SM treatment almost completely prevented the induction of PA at both the protein and mRNA levels. Overall these results demonstrate an up-regulation of urokinase in 3T3 fibroblasts after treatment with SM, which is possibly mediated by intracellular calcium mobilization.
Further studies are needed to identify the significance of this proteolytic response in the pathogenesis of blistering and/or DNA repair mechanisms.

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Synthesis and mass spectrometric identification of the major amino acid adducts formed between sulphur mustard and haemoglobin in human blood. Noort D; Hulst A G; Trap H C; de Jong L P; Benschop H P Department of Chemical Toxicology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1997), 71(3), 171-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049054 AN 97201271 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

As part of a program to develop methods for the verification of alleged exposure to sulphur mustard, we synthesized and characterized three amino acid adducts presumably formed by alkylation of haemoglobin: 4-(2-hydroxyethylthioethyl)-L-aspartate, 5-(2-hydroxyethylthioethyl)L-glutamate and N1- and N3-(2-hydroxyethylthioethyl)-L-histidine. Suitable derivatization methods for GC/MS analysis were developed for these adducts as well as for the cysteine and the N-terminal valine adduct. Incubation of human blood with [35S]sulfur mustard in vitro followed by acidic hydrolysis of isolated globin and derivatization with Fmoc-Cl afforded three radioactive peaks upon HPLC analysis, one of which coeluted with the synthetic Fmoc derivative of N1/N3-(2-hydroxyethylthioethyl)-L-histidine. After pronase digestion of globin the adducts of histidine, glutamic acid, aspartic acid, cysteine and N-terminal valine could be tentatively identified and quantitated. Final identification was obtained from GC/MS analysis. The most abundant adduct, N1/N3-(2-hydroxyethylthioethyl)-L-histidine, could not be sensitively analysed by GC/MS. A convenient LC-tandem MS procedure was developed for this compound, enabling the detection of exposure of human blood to 10 microM sulphur mustard in vitro.

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Protective effect of povidone-iodine ointment against skin lesions induced by sulphur and nitrogen mustards and by non-mustard vesicants. Wormser U; Brodsky B; Green B S; Arad-Yellin R; Nyska A Department of Pharmacology, School of Pharmacy, Faculty of Medicine, Hebrew University of Jerusalem, Israel Archives of toxicology (1997), 71(3), 165-70. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049053 AN 97201270 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Mustard gas (sulphur mustard, SM) is a powerful vesicant employed as a chemical weapon. The present study demonstrates the effect of povidone iodine (PI) ointment against skin toxicity caused by SM. Gross and histopathological examinations showed that application of PI up to 20 min following exposure to the vesicant resulted in marked skin protection. The shorter the interval between exposure and treatment the better was the protection achieved. PI was also effective against other mustards such as carboxybutyl chloroethyl sulphide (CBCS) and mechlorethamine. The fact that PI protected the skin against agents which cannot be oxidized such as iodoacetic acid, divinylsulphone and cantharidine showed that the antidotal effect of PI was unrelated to oxidation of the nitrogen and sulphur atoms of the mustards. PI ointment is proposed as an efficient protective agent against skin toxicity caused by mustards and other alkylators.

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Modifications of breathing pattern induced by inhaled sulphur mustard in mice. Vijayaraghavan R Pharmacology and Toxicology Division, Defence Research and Development Establishment, Gwalior, India Archives of toxicology (1997), 71(3), 157-64. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049052 AN 97201269 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A head-only exposure assembly was used for exposing mice to vapours of sulphur mustard (SM). The respiration was monitored using an on-line computer program, capable of recognizing the breathing pattern as sensory irritation, airflow limitation and pulmonary irritation. SM was dissolved in acetone and vapourized using a compressed air nebulizer. Mice were exposed to the vapours (8.5, 16.9, 21.3, 26.8, 42.3 and 84.7 mg/m3) for 1 h in a body plethysmograph fitted with a 20-gauge needle and a microphone for sensing the respiratory flow signals. The signals were amplified, digitized and integrated to give tidal volume, and stored in a computer for further analysis. The respiration of the mice was followed for modifications in the breathing pattern until 7 days post-exposure. SM induced sensory irritation during exposure, and there was a concentration dependent decrease in the respiratory frequency and an increase in tidal volume. Lower concentrations showed recovery after stopping the exposure. RD50, the concentration that depresses 50% of the respiration was estimated to be 27.4 mg/m3. Following exposure to higher concentrations the animals started dying after 6 days. The LC50 was estimated to be 42.5 mg/m3 (14 days observation period). The respiratory frequency decreased on subsequent days of exposure depending upon the exposure concentration, and the breathing pattern was characteristic of airflow limitation. The ratio of flow/tidal volume was decreased following exposure to concentrations of 26.8 and 42.3 mg/m3. The ratio of flow/tidal volume may be a better measurement than the measurements based on flow alone for the assessment of airflow limitation. Pulmonary irritation was not observed showing that the lungs were not affected. The body weight of the animals decreased progressively. The present methodology will be useful for identifying the effects of SM on the respiratory system, one of the endpoints considered when establishing occupational exposure limits.

[megalomania]

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Reactions of sulfides with S-330, a potential decontaminant of sulfur mustard in formulations. Shih, Ming L.; Korte, William D.; Smith, J. Richard; Szafraniec, Linda L. US Army Medical Research Institute of Chemical Defense, APG, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S83-S88. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:289769 AN 2000:132684 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Because the vesicant sulfur mustard (HD) remains a major chem. threat from either domestic terrorists or countries in conflict, topical prepns. are being evaluated as protectants from HD exposure. The objective of this study was to evaluate the effectiveness of chloroamide S-330 as a potential reactive component in topical formulations. Therefore, the rate, mechanism and byproducts of the oxidn. reactions of sulfides by S-330 in solvent media or specific formulation vehicles were investigated. Using NMR, LC, LC-MS and GC-MS, the reactions of S-330 with HD, di-Bu sulfide (DBS) and Me Ph sulfide (MPS) were studied in acetonitrile, chloroform and perfluoropolyether (PFPE) oil. The oxidn. of the three sulfides with S-330 was very rapid and completed in <4 min in acetonitrile-water or PFPE oil, but the rates of reaction in chloroform were significantly slower. In a large excess of S-330, the major products resulted from chlorination of the side chains. At a high HD/S-330 ratio, the major product was HD sulfoxide. Under both conditions, only a trace of HD sulfone, also a blistering agent, was obsd. Reactions with DBS and MPS primarily gave sulfoxides and sulfones, with less side-chain chlorination. The chloroamide S-330 appeared to be a rapid and effective decontaminant of HD in either polar media or in a PFPE oil. The two alkyl and aryl sulfides are suitable simulants of HD for the initial screening and evaluation of S-330 or other similar oxidizing agents.

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Polyoxometalate oxidation of chemical warfare agent simulants in fluorinated media. Johnson, Rhoma P.; Hill, Craig L. Department of Chemistry, Emory University, Atlanta, GA, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S71-S75. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 133:1581 AN 2000:132682 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this research is to det. if appropriate polyoxometalates (POMs) could be added to perfluoropolyether topical skin protectants (TSPs) currently available or under development to give these TSPs the addnl. capability of detecting and in some cases catalytically decontaminating sulfur mustard (HD) and perhaps other chem. warfare agents (CWAs) at ambient temps. Detection would be based on significant color changes in the POM upon redn. by the CWA whereas catalytic decontamination would be based on the ability of some families of POMs to catalyze O2-based oxidns. by more than one mechanism. Five POMs (10-25% by wt.) were each suspended in .apprx.5 g of the perfluoropolyether (PFPE, CF3O[-CF(CF3)CF2O-]x(-CF2O-)yCF3) "barrier" cream. A stoichiometric amt. of HD sulfide simulant was layered on top of each POM-cream mixt. The short reaction times were recorded for each system. Mechanistic studies were conducted using an PFPE oil analog of the barrier cream in a microemulsion with the sulfide simulant, POM, PFPE surfactant and 2,2,2-trifluoroethanol co-surfactant.

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Development of reactive topical skin protectants against sulfur mustard and nerve agents. Koper, Olga; Lucas, Eric; Klabunde, Kenneth J. Nantek, Inc., Manhattan, KS, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S59-S70. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:261513 AN 2000:132681 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The potential for highly reactive nanoparticles (RNP) to absorb destructively, i.e. to neutralize highly toxic substances such as the warfare agents GA, GB, HD and VX, has been demonstrated in the lab. Reactive nanoparticles represent a new class of nanoscale particles of metals and metal oxides that differ from other nanoparticles in reactivity and cryst. morphol. The potential for incorporating RNP into a protective barrier skin cream also has been demonstrated. Preliminary studies indicate that RNP are phys. and chem. compatible with a base cream provided by the Army Medical Research Office and, importantly, remain reactive with chem. agents while promising to be compatible with skin contact.

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Development of a reactive topical skin protectant. Braue, Ernest H., Jr. Advanced Assessment Branch, Drug Assessment Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S47-S53. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:289768 AN 2000:132679 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The use of a topical skin protectant (TSP) as a means of protecting troops from percutaneous chem. warfare agent (CWA) exposure has been proposed since these weapons were first used during World War I. The TSP is applied to vulnerable skin surfaces prior to entry into a chem. combat area. In 1990, the US Army Medical Research Institute of Chem. Defense transferred two non-reactive TSPs into advanced development. Following US Food and Drug Administration approval, the final product is expected to be available to soldiers in 1999. A continuing research effort is designed to develop a second-generation TSP that will increase effectiveness and also decontaminate CWAs into non-toxic products. We identified a list of 29 reactive moieties as potential additives to the TSP formulation. All candidate formulations are evaluated in a decision tree network, consisting of a series of 11 efficacy testing models. A prototype formulation (ICD 2701) contg. the reactive ingredient S-330 has dramatically improved the protection against satd. sulfur mustard vapor. In addn., we have discovered a compd. (ICD 2837) that significantly increases the skin's natural resistance to CWA penetration. Our goal is to transfer a significantly improved TSP formulation into advanced development by 1999.

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Efficacy of the topical skin protectant in advanced development. Liu, Dai Kee; Wannemacher, Robert W.; Snider, Thomas H.; Hayes, Timothy L. US Army Medical Material Development Activity, Fort Detrick, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S41-S45. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:261511 AN 2000:132678 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A topical skin protectant (TSP) (ICD 2289) is being developed to protect service members from exposure to chem. warfare agents (CWA). The TSP is designed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clin. studies, is a cream contg. two chem. inert substances: perfluoroalkylpolyether and polytetrafluoroethylene. Animal data showed that the TSP was effective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by preventing the development of erythema and edema. The insect repellent N,N-diethyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protection was sustained when DEET was removed with a dry gauze prior to TSP application. The TSP was also effective against percutaneous exposure of nerve agents-thickened (with 5% Me methacrylamide) soman and VX by reducing the mortality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when DEET was applied prior to TSP application. Because human efficacy studies using CWA cannot be conducted, the efficacy will be demonstrated by the level of protection against poison ivy (urushiol) contact dermatitis in humans.

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Sulfur mustard induced DNA damage in mice after dermal and inhalation exposure. Lakshmana Rao, P. V.; Vijayaraghavan, R.; Bhaskar, A. S. B. Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India. Toxicology (1999), 139(1-2), 39-51. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 132:162248 AN 1999:746442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (SM) is a chem. warfare agent of the blistering agent category for which there is still no effective therapy. SM, being a strong electrophile, readily reacts with a wide range of cellular macromols. including DNA, RNA and protein. Since the main intoxication routes for SM are inhalation and dermal penetration, in the present study we have exposed female mice to different concns. of SM by dermal and inhalation exposures and estd. the DNA damage in different organs viz., liver, lung, spleen and thymus. SM was applied at 38.7, 77.4, 154.7 mg/kg body wt., on the hair-clipped skin (dermal exposure) equiv. to 0.25, 0.5 and 1.0 of the LD50. Inhalation exposure was carried out at 10.6, 21.2 and 42.3 mg/m3 for 1 h duration equiv. to 0.25, 0.5 and 1.0 LC50. SM induced a dose-dependent DNA damage in all the organs except the lung in dermal exposure. Similarly the inhalation exposure resulted in dose- and time-dependent effect in all the organs including lung. By both routes of exposure liver was the most affected organ followed by spleen, thymus and lung in decreasing order. The quant. data were corroborated by qual. anal. of DNA on agarose gel electrophoresis. The genomic DNA anal. of the organs had revealed random nuclear DNA fragmentation resulting in a 'smear' typical of necrotic form of cell death. Since DNA damage is not reversible esp. in liver, this can be used as a marker for SM exposure through either the dermal or inhalation route.

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Synthesis and mass spectral characterization of diisopropylamino-ethanethiol, -sulfides and -disulfides and vinyl sulfides. Rohrbauch, D. K.; Berg, F. J.; Szafraniec, L. J.; Rossman, D. I.; Durst, H. D.; Munavalli, S. Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, U.S. Army, Aberdeen, MD, USA. Phosphorus, Sulfur and Silicon and the Related Elements (1999), 149 95-106. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 132:49741 AN 1999:681810 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The sulfur contg. chem. agent, O-ethyl-S-2-(diisopropylaminoethyl)methylphosphonothiolate, is an extremely potent inhibitor of the enzyme acetylcholinesterase and exhibits extended neurol. effects. It undergoes degrdn. on standing alone or in the environment. Hence, identification of its primary degrdn. products assumes considerable importance. The synthesis and mass spectral fragmentation behavior of the title compds., some of which are present in the O-ethyl-S-2-(diisopropylaminoethyl)methylphosphonothiolate degrdn. products, has not received much attention. This communication describes the synthesis and mass spectral characterization of the title compds.

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Reaction of Bis(2-chloroethyl) Sulfide with N,N'-Dichlorobis(2,4,6-trichlorophenyl)urea. Dubey, D. K.; Malhotra, R. C.; Vaidyanathaswamy, R.; Vijayaraghavan, R. Defence R. & D. Establishment, Gwalior, India. Journal of Organic Chemistry (1999), 64(21), 8031-8033. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 132:12186 AN 1999:629651 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The reaction of bis(2-chloroethyl)sulfide (warfare agent) with N,N'-dichloro-N,N'-bis(2,4,6-trichlorophenyl)urea was describe with the aim of using the latter as a decontamination agent.

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Reactions of VX, HD, and Their Simulants with NaY and AgY Zeolites. Desulfurization of VX on AgY. Wagner, George W.; Bartram, Philip W. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Langmuir (1999), 15(23), 8113-8118. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 131:299202 AN 1999:577485 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The room-temp. reactions of the chem. warfare agents VX (O-Et S-2-(diisopropylamino)ethyl methylphosphonothioate), HD (2,2'-dichloroethyl sulfide, or mustard), and their common simulants, O,S-di-Et phenylphosphonothioate (DEPPT) and 2-chloroethyl Ph sulfide (CEPS), with NaY and silver-exchanged (AgY) zeolites have been studied using solid-state magic angle spinning NMR. VX hydrolyzes via exclusive cleavage of the P-S bond on both NaY and AgY to yield Et methylphosphonate (EMPA). The reaction is significantly faster on AgY than on NaY, suggesting catalysis by silver. On AgY, an intermediate silver salt of EMPA is apparently formed which is slowly converted to Et 2-(diisopropylamino)ethyl methylphosphonate (QB, the desulfurized analog of VX) in about a 78% yield. DEPPT similarly hydrolyzes via P-S cleavage on AgY to yield an apparent silver salt of Et phenylphosphonate, which does not undergo further reaction to the desulfurized analog. No reaction is obsd. for DEPPT on NaY. HD on AgY forms both vinyl sulfide and the cyclic ether 1,4-thioxane. HD reacts faster on NaY to exclusively form the CH-TG sulfonium ion (HOCH2CH2SCH2CH2S+[CH2CH2OH]2). CEPS also reacts faster on NaY, forming 2-hydroxyethyl Ph sulfide. On AgY, CEPS does not give the vinyl product, but does yield the ether product PhSCH2CH2OCH2CH2SPh. A mechanism is proposed for the silver-catalyzed hydrolysis of VX, the desulfurization of the cleaved thiol, and the formation of QB.

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Reaction of a Vesicular Functionalized Surfactant with 2-Chloroethyl Phenyl Sulfide, a Mustard Simulant. Jaeger, David A.; Schilling, Curtis L. III; Zelenin, Alexander K.; Li, Bei; Kubicz-Loring, Elzbieta. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (1999), 15(21), 7180-7185. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 131:233071 AN 1999:505232 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant, potassium O,O'-didodecylphosphorodithioate (I) was synthesized. Its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry and its giant vesicles by phase-contrast optical microscopy. Also, I's giant vesicles contg. fluorescent dye, 5-carboxyfluorescein or 5-(dodecanamido)fluorescein, were characterized by epifluorescence microscopy. In a pH 9.0 borate buffer at 25, vesicular I reacted with 2-(2-chloroethyl Ph sulfide), a simulant for the chem. warfare agent mustard [bis(2-chloroethyl) sulfide], to give 5-[S-[(2-phenylthio)ethyl]O,O'-didodecylphosphorodithioate] (II), involving capture of reactive intermediate cation 1-phenylthiocyclopropane by the anion of I. This reaction was accompanied by the pptn. of II, which resulted in wounding/destruction of the vesicles and the release of dye 5-carboxyfluorescein (from giant vesicles). The combination of the conversion and dye release suggests the potential of vesicular systems for simultaneous decontamination and signaling of chem. agents. 2-(2-Chloroethyl Ph sulfide) hydrolyzed to give only 2-(phenylthio)ethanol in the pH 9.0 buffer at 25.

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Two-generation reproduction study of lewisite in rats. Sasser, L. B.; Cushing, J. A.; Lindenmeier, C. W.; Mellick, P. W.; Dacre, J. C. Battelle, Richland, WA, USA. Journal of Applied Toxicology (1999), 19(4), 229-235. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 131:253491 AN 1999:485887 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite, a potent toxic vesicant and chem. warfare agent, is used in a no. of research labs., is stored in large quantities at depot sites throughout the USA and is occasionally transported to distant sites. Thus, the potential for environmental or occupational exposure exists where lewisite is present. A 42-wk two-generation study was conducted to det. the reproductive consequences of lewisite in parental male and female rats and their offspring. Rats were administered lewisite in sesame oil (0, 0.10, 0.25 or 0.60 mg kg-1 day-1 for 5 days a week) via intragastric intubation before mating, during mating and after mating until the birth of their offspring. The dams continued to receive lewisite during lactation. At weaning, male and female offspring of each group were selected to continue the study, receiving lewisite during adolescence, mating and throughout gestation and lactation. Lewisite had no adverse effect on reprodn. performance, fertility or reproductive organ wts. of male or female rats through two consecutive generations. No adverse effects to offspring were attributed to lewisite exposure. Minor changes in growth were the only maternal effects obsd. Lewisite exposure of parental rats caused no gross or microscopic lesion in testes, epididymis, prostate, seminal vesicles, ovaries, uterus or vagina. The no-observable-effect level (NOEL) for the reproductive effects of Lewisite would be >0.60 mg kg-1 day-1.

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Chemistry and toxicology of sulfur mustard-a review. Malhotra, R. C.; Ganesan, K.; Sugendran, K.; Swamy, R. V. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1999), 49(2), 97-116. CODEN: DSJOAA ISSN: 0011-748X. Journal; General Review written in English. CAN 131:112423 AN 1999:324517 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review and discussion with 124 refs. Bis(2-chloroethyl) sulfide commonly known as sulfur mustard (SM) is highly reactive bifunctional compd., documented as antimitotic, mutagenic, carcinogenic, teratogenic and cytotoxic agent. It is a powerful vesicant and has been employed as a chem. warfare agent. Skin, eyes and respiratory tract are the principal target organs and the DNA is the most important mol. target of SM toxicity. There is no specific antidote for SM injury. Treatment to SM toxicity is symptomatic.

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Surrogate burns in deactivation furnace system. Shah, Jay K. Science Applications International, Tooele, UT, USA. Journal of Hazardous Materials (1999), 66(3), 279-290. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 131:35263 AN 1999:308797 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The deactivation furnace system at the Deseret Chem. Depot in Utah is designed for processing explosive components from munitions contg. nerve and mustard agents. The Utah Division of Solid and Hazardous Waste (UDSHW) required that trial burns be conducted using surrogate chems. prior to introducing chem. agents into the system. Three surrogate runs of the selected surrogate chems. monochlorobenzene and hexachloroethane based on the criteria established by the UDSHW were conducted. The gaseous emissions and liq. and solid effluents were sampled and analyzed using approved EPA methods. The trial burns demonstrated the desirable destruction and removal efficiency for the selected surrogate chems. The pollution abatement system demonstrated the desired scrubbing efficiency for acid gases generated during incineration of chlorinated surrogate chems. The particulate removal efficiency during the trial burns was also considerably higher than required by regulations. After comprehensive survey of the performance of the deactivation furnace system during the surrogate trial burns, UDSHW approved introduction of GB nerve agent into the system to prep. it for agent trial burns.

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Reactions of VX, GD, and HD with Nanosize MgO. Wagner, George W.; Bartram, Philip W.; Koper, Olga; Klabunde, Kenneth J. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Journal of Physical Chemistry B (1999), 103(16), 3225-3228. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 130:337750 AN 1999:218187 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The room-temp. reactions of the chem. warfare agents VX (O-Et S-2-(diisopropylamino)ethyl methylphosphonothioate), GD (3,3-dimethyl-2-Bu methylphosphonofluoridate, or Soman), and HD (2,2'-dichloroethyl sulfide, or mustard) with nanosize MgO have been studied using solid-state MAS NMR. All three agents hydrolyze on the surface of the very reactive MgO nanoparticles. VX yields Et methylphosphonic acid (EMPA) and methylphosphonic acid (MPA), but no toxic S-(2-diisopropylamino)ethyl methylphosphonothioate (EA-2192). GD forms both GD-acid and MPA. For HD, in addn. to hydrolysis to thiodiglycol, about 50% elimination to divinyl sulfide occurs. The reaction kinetics for all three agents are characterized by a fast initial reaction followed by gradual slowing to a steady-state reaction with first-order behavior. The fast reaction is consistent with liq. spreading through the porous nanoparticle aggregates. The steady-state reaction is identified as a gas-phase reaction, mediated by evapn., once the liq. achieves its vol. in the smallest available pores.

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Cleavage of VX Simulants by Micellar Iodoso- and Iodoxybenzoate. Moss, Robert A.; Morales-Rojas, Hugo; Zhang, Hongmei; Park, Byeong-Deog. Department of Chemistry, Rutgers The State University of New Jersey, New Brunswick, NJ, USA. Langmuir (1999), 15(8), 2738-2744. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:328660 AN 1999:197621 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

O,S-Di-Et phenylphosphonothioate and S-Ph and S-Et diphenylthiophosphinate were efficiently cleaved by 3-fold excess o-iodosobenzoate (IBA) in aq. micellar cetyltrimethylammonium chloride solns. at pH 9.5. The max. obsd. rate consts. (monitored by HPLC aliquot procedures) were 1.09  10-3 s-1 for O,S-Di-Et phenylphosphonothioate and 6.0  10-3 s-1 for S-Et diphenylthiophosphinate with 0.06 M IBA at 25. S-Ph diphenylthiophosphinate cleaved too rapidly to follow by the aliquot method. With equimolar quantities of O,S-Di-Et phenylphosphonothioate and IBA, cleavage was slower and incomplete because of the redn. of the IBA to iodobenzoate by the EtSH liberated in the cleavage step. Mixts. of IBA and o-iodoxybenzoate (IBX) efficiently cleaved O,S-Di-Et phenylphosphonothioate, even though IBX was not reactive toward O,S-Di-Et phenylphosphonothioate, because the IBX competitively oxidized the EtSH, mitigating its reaction with IBA, while simultaneously affording addnl. IBA as the IBX was reduced. Studies of IBA and IBX redox reactions with EtSH are also included.

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Kinetic model for the decomposition of DMMP in a hydrogen/oxygen flame. Werner, James H.; Cool, Terrill A. School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. Combustion and Flame (1999), 117(1/2), 78-98. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 130:112199 AN 1999:101405 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A kinetic model of the combustion chem. of a hydrogen/oxygen base flame, doped with di-Me methylphosphonate (DMMP), a useful simulant for chem. warfare agents (CWAs), has been developed to assist in the controlled thermal destruction of CWA stockpiles. Laser-ionization mass spectrometry is employed to record concn. profiles of radical intermediates in a low-pressure premixed laminar flame. These measurements, combined with ab initio ests. of thermochem. properties of organophosphorus compds., lead to a kinetic model incorporating several key reaction intermediates, which include Me metaphosphate CH3OPO2, Me dioxophosphorane CH3PO2, and monomethyl methylphosphonate PO(OH)(CH3)(OCH3).

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Deactivation of Mustard and Nerve Agent Models via Low-Temperature Microemulsions. Menger, Fredric M.; Rourk, Michael J. Department of Chemistry, Emory University, Atlanta, GA, USA. Langmuir (1999), 15(2), 309-313. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:164143 AN 1998:796211 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

New low-temp. oil-in-water (O/W) type microemulsions that resist freezing and phase sepn. at -18 have been developed. These systems were shown to simultaneously destroy, via oxidative and hydrolytic mechanisms, simulants of three chem. warfare agents. Reactions, monitored at 25 by gradient elution high-performance liq. chromatog., took place instantly or over many minutes, depending upon the particular simulant. Neglecting reaction products, the low-temp. microemulsions contained 11 components: propylene glycol, water, base, oxidant/nucleophile, surfactant, cosurfactant, oil, stabilizer, two nerve agent simulants, and a mustard simulant. Only by virtue of self-aggregation does this extraordinarily complex chem. system adopt a useful mol. organization and, in this limited sense, the microemulsion chem. resembles what happens in a living cell. Substantial practical issues remain: rates for a recalcitrant VX simulant should be increased and overoxidn. of the mustard simulant to a sulfone retarded. Nonetheless, the new system demonstrates once again the potential of microemulsions in carrying out useful org. reactions at realistic substrate concns. in aq. solvents.

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Treatment for sulfur mustard poisoning - a review. Sugendran, K.; Kumar, Pravin; Vijayaraghavan, R. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1998), 48(2), 155-162. CODEN: DSJOAA ISSN: 0011-748X. Journal; General Review written in English. CAN 130:164031 AN 1998:781689 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review and discussion with 39 refs. Sulfur mustard (SM) is a chem. warfare agent of historical and current interest. It is a well known blistering agent or vesicant. SM was extensively used in world war I as a chem. weapon and has been stockpiled by several countries since that time. SM serves as an ideal war gas and is favored militarily for its ability to incapacitate rather than to kill. Its use resulted in large nos. of casualties requiring prolonged and intensive medical care. Despite Geneva Protocol of 1925, which categorically banned the prodn., stockpiling and use of chem. weapons in wars, SM has been used in several wars, including the Iran-Iraq war during the 1980s, which renewed interest in it. Though, the chem. weapons convention was signed by more than 160 countries in 1993 and was subsequently ratified by several countries, the threat from this agent persists due to its clandestine usage during war and also by terrorist groups. There is no effective and specific antidote for local and systemic toxicity of SM despite scientific research for more than 75 yr. Many compds. were tested as antidotes for SM, but very few of them have been shown to provide some protection. The present review is aimed at evaluating the treatment regime and other clin. measures used to treat SM victims and the various drugs and chems. screened as antidotes for SM poisoning in exptl. animals.

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Evaluation of neutralized chemical agent identification sets (CAIS) for skin injury with an overview of the vesicant potential of agent degradation products. Olajos, E. J.; Olson, C. T.; Salem, H.; Singer, A. W.; Hayes, T. L.; Menton, R. G.; Miller, T. L.; Rosso, T.; MacIver, B. Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1998), 18(6), 409-420. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 130:106238 AN 1998:750883 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Vesication and skin irritation studies were conducted in hairless guinea-pigs to det. the vesicant and skin irritation potential of chem.-neutralized Chem. Agent Identification Sets (CAIS). The CAIS are training items that contain chem. warfare-related material-sulfur mustard (HD), nitrogen mustard (HN) or lewisite (L)-and were declared obsolete in 1971. Animals were dosed topically with "test article"-neat HD, 10% agent/chloroform solns. or product solns. (waste-streams) from neutralized CAIS-and evaluated for skin-damaging effects (gross and microscopic). Product solns. from the chem. neutralization of neat sulfur mustard resulted in microvesicle formation. All agent-dosed (HD or agent/chloroform solns.) sites manifested microblisters as well as other histopathol. lesions of the skin. Waste-streams from the neutralization of agent (agent/chloroform or agent/charcoal) were devoid of vesicant activity. Cutaneous effects (erythema and edema) were consistent with the skin-injurious activity assocd. with the neutralizing reagent 1,3-dichloro-5,5-dimethylhydantoin (DCDMH). Chem. neutralization of CAIS was effective in eliminating/reducing the vesicant property of CAIS contg. agent in chloroform or agent on charcoal but was inefficient in reducing the vesicant potential of CAIS contg. neat sulfur mustard.

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Degradation and fate of mustard in soil as determined by 13C MAS NMR. Wagner, George W.; MacIver, Brian K. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Langmuir (1998), 14(24), 6930-6934. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:91384 AN 1998:713429 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The environmental fate of chem. warfare agents is a current concern, and the notorious persistency of mustard in soil is well-known. The current study utilizes 13C MAS NMR as an in situ method to study the behavior of mustard, and the common simulants 2-chloroethyl Me sulfide (CEMS) and 2-chloroethyl Ph sulfide (CEPS), in a sandy loam soil. Spreading of these water-insol. liqs. and surface sorption on the dry soil particles is observable, as is the recoalescence of liq. droplets and/or hydrolysis in the presence of added water. The relative hydrolysis rates are in agreement with those obsd. in soln. CEMS, possessing the shortest aq. half-life, hydrolyzes without droplet reformation. But mustard and CEPS, possessing much longer aq. half-lives, do not substantially hydrolyze prior to droplet reformation. For mustard, this behavior is crucial to its longevity in soil. Hydrolysis of CEMS and CEPS in the sandy loam soil yields predominately their corresponding alcs., with some ether formation for the latter. Mustard hydrolysis in the sandy loam soil results in the nearly exclusive formation of the branched sulfonium ion HOCH2CH2SCH2CH2S+(CH2CH2OH)2 (CH-TG). A simple model based on droplet size is presented to explain the persistency of mustard in soil.

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Old arsenical munitions: methods for destruction and site cleanup. Beletskaya; Bilger; Boronin; Bunnett; Costantino; Cullen; Dominas; Goessler; Haiduc; Maeda; Martens. Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 177-183. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42626 AN 1998:702909 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 11 refs. concerning methods to destroy and clean-up sites polluted by old arsenical munitions is given. Topics discussed include: spilled arsenical agents (natural chem. transformations in-situ, biotransformation, decontamination of soil contg. arsenical agents, removing polluted soil for treatment elsewhere); destruction of arsenical agents in munition containers or storage tanks (incorporation into concrete, incineration, reactions with alkalies, Na cleavage, hydrogenolysis, novel methods from Russia, oxidn. in water solns., oxidn. under UV irradn., Ag2+ oxidn., other technologies, biodegrdn); and need for research.

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Old "mustard" or yperite munitions: methods for destruction and container detoxification. Koch, E.; Koch, M.; Leslie; Mikolajczyk; Modena; Mulbry; Petrosyan; Sokolowski; Yang. Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 175-176. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42704 AN 1998:702908 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Problems assocd. with disposal of mustard chem. warfare agent, particularly the presence of materials other than the pure chem. compd., bis(2-chloroethyl)sulfide, greatly affects the suitability of processes which may be proposed for their destruction. Thus, destruction of mustard involved the conversion of a multitude of chem. species into material suitable for ultimate disposal; overall destruction also requires the material be presented in the correct form to the reaction stage of the process. Currently, only high temp. oxidn., i.e., incineration, is demonstrated bot be suitable for large-scale destruction of all materials collectively referred to as mustard. For a no. of reasons and public opposition, incineration may not be appropriate or acceptable for destruction of mustard at some locations. Technologies which for one reason or another were not pursued or were disregarded should be reconsidered in light of the wide range of problems that exist for destruction of mustard. Research into clean-up of contaminated sites is also necessary, including bioremediation of soil and chem. transformations in soil.

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Breakdown of sulfur "mustard" by phase transfer catalyzed HCl elimination, A potential destruction method for "mustard" stocks. Koch, Ernst - Christian. ABC- und Selbstschutzschule, Sonthofen, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 169-174. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42625 AN 1998:702907 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 56 refs. concerning sulfur mustard breakdown by phase transfer-catalyzed HCl elimination is given. Topics discussed include: mustard destruction; problem; process results and discussion; summary; instrumentation; and exptl.

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Reductive decomposition of deposits in old "mustard" munitions. Bunnett, Joseph F. University of California, Santa Cruz, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 163-164. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42703 AN 1998:702905 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The nature of gelled or solid deposits in decades-old mustard tanks or munitions is uncertain. Some possibilities which may occur alone or in combination include: polysulfonium salts; poly(ethylenesulfide); elemental S; di- or oligo-sulfide polymers; and Fe compds. from container corrosion. All these structural types are vulnerable to attack by strong reducing agents: Na in liq. NH3; electrochem. cleaving; S reaction with Na; Fe salt redn. by Na; and alkyl halide cleavage by Na. In the lab., conducting such reactions in liq. NH3 is attractive because solns. of Na in NH3 are stable for hours or days. Thus, factory-type installations using Na in liq. NH3 to clean out old mustard munitions with gelled or solid deposits should be feasible. After munitions have been opened and drained of liq. mustard, liq. NH3 could be added followed by pieces of Na metal to react with and destroy the deposits. Munitions so treated would be safe to ship to a furnace to burn out remaining traces. For field situations, a promising alternative is using Na in ethanol; Na reacts with ethanol to release H gas. Addnl. research is needed to confirm that compds. modeling the various suggested structures for gelled or solid mustard are reactive with Na in ethanol as expected.

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Electrochemical and biological approach to the destruction of Lewisite and "Mustard". Boronin, Alexander M.; Sakharovski, Valentin G.; Starovoitov, Ivan I.; Kashparov, Konstantin I.; Shvetsov, Valery N.; Morozova, Ksenija M.; Nechaev, Igor A.; Tugoshov, Vladimir I.; Kuzmin, Nikolai P.; Kochergin, Alexander I. Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 159-162. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42702 AN 1998:702904 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ecol. benign destruction of lewisite and mustard was achieved by electrochem. pretreatment of their neutralization products followed by biol. oxidn. of the waste stream. The process, reaction products, and results are discussed.

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Destruction of Adamsite by sodium. Sokolowski, M.; Bilger, E. Military Institute of Chemistry and Radiometry, Warsaw, Pol. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 157-158. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42701 AN 1998:702903 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sodium destroys chem. weapons, such as adamsite in a liq., dissolved, or gaseous state, with a special form of metallic, high surface Na, either on supports or as a dispersion in oil to yield inorg. Na salts and small org. mols. with little or no toxicity. Adamsite is destroyed by reacting with Na at low and even ambient temps. within a short time. Most of the originally org.-bonded As is transformed into inorg. As (ionic) and therefore can be pptd. as an insol. sulfide. After completing adamsite decompn., water contg. sodium sulfide is added in a closed compartment to initiate hydrolysis of org. Na compds. and ppt. As2S3.

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A method for mutual disposal of old chemical weapons. Chimishkyan, Alexander L. D. Mendeleev University of Chemical Technology, Moscow, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 155-156. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42700 AN 1998:702902 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It is known that HCl destroys adamsite with formation of diphenylamine and AsCl3, and that the reaction of diphenylamine with another toxic agent, phosgene, is a method to produce acridone-9. These two reactions were used for the mutual disposal of adamsite and phosgene. Preliminary results showed the best results are obtained when phosgene is passed through an adamsite/paraffin melt. At the high temp. of the process (190-200), AsCl3 vapors are removed from the reaction mass where acridone-9 accumulates. It was also obsd. that tetraphenylurea is present in the reaction mass. This process guarantees a high yield of AsCl3.

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HPLC-ICP-MS methods for the determination of inorganic and organic arsenic compound. Goessler, W.; Kuehnelt, D.; Irgolic, K. J. Institute for Analytical Chemistry, Karl-Frazens-Universitat, Graz, Austria. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 151-154. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:62116 AN 1998:702901 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To improve the detection limits, a hydraulic high-pressure nebulizer was substituted for the normal pneumatic nebulizer. Chromatog. conditions for the sepn. of inorg. and org. arsenic compds. are identified. Characteristic chromatograms are presented. The combination of the hydraulic high-pressure nebulizer with the inductively coupled plasma mass spectrometer enables the sepn. and detection of arsenic at the sub ng/mL level. These methods can certainly be used to identify and quantify arsenic compds. in soil samples suspected of contamination with arsenic-contg. chem. warfare agents.

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Practical actions of Russia on preparations for destruction of stockpiled Lewisite and "Mustard". Petrov, S. V.; Kholstov, V. I.; Zoubrilin, V. P.; Zavialova, N. V. Ministry Of Defence Of Russian Federation, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 79-90. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42697 AN 1998:702894 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To meet its international obligations while pursuing national policy, Russia has given priority to destroying its chem. warfare agent stockpiles as a major national objective. A mobile chem. warfare agent destruction mobile complex was constructed. It was necessary to first destroy stockpiled mustard-lewisite mixts. stored in high tonnage containers. The next priority is design and construction of a facility for organophosphorus agent destruction. This will be conducted simultaneously with work on blister agent destruction. This required site selection and submission to proper authorities and to the public for approval. Topics discussed include: Russian chem. weapons stockpiles; technol. aspects of lewisite and mustard destruction (lewisite stockpile destruction technologies [S treatment, lewisite interaction with ethylene glycol monomethacrylate ester and its subsequent polymn., chlorination, alk. hydrolysis, alcoholysis, high temp. oxidn., hydrogenolysis, NH3 redn.], mustard stockpile destruction technologies, mustard-lewisite mixts. destruction); and provisions for ecol. safe destruction of stockpiled lewisite and mustard.

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The problem of old chemical weapons which contain "mustard gas" or organoarsenic compounds: an overview. Manley, Ron G. Chemical Demilitarisation Branch, Provisional Technical Secretariat of the Preparatory Commission for the Organisation for the Prohibition of Chemical Weapons, Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 1-16. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42622 AN 1998:702891 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 26 refs. of problems related to old and/or abandoned chem. weapons and the practicalities assocd. with their recovery and safe disposal. Emphasis is placed on weapons contg. either thickened or polymd. mustard gas and/or org. arsenicals, as these pose some of the most difficult disposal problems.

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Cardiorespiratory effects of O-isobutyl S-[2-(diethylamino)-ethyl] methylphosphonothioate - a structural isomer of VX. Chang, F.-C. T.; Gouty, S. C.; Eder, L. C.; Hoffman, B. E.; Maxwell, D. M.; Brecht, K. M. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1998), 18(5), 337-347. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 130:34271 AN 1998:676630 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

O-Iso-Bu S-[2-(diethylamino)ethyl]methylphosphonothioate (VR) is a structural isomer of a more well-known chem. warfare agent, O-Et S-[2-(diisopropylamino)ethyl]methylphosphonothioate (code designation VX). In this study, cardiorespiratory and central nervous system (CNS) effects of VR (2LD50 or 22.6 g kg-1; s.c.) were evaluated in urethane-anesthetized (Group 1) and unanesthetized (Group 2) guinea pigs instrumented for concurrent recordings of electrocorticogram (ECoG) and a variety of cardiorespiratory activities. The first sign of intoxication was a state of progressive bradycardia, vascular hypotension and arrhythmia (Group 1, .apprx. 13 min post-VR; Group 2, .apprx.6 min post-VR). Bradypnea, excessive salivation and compensatory changes in blood pressure typically did not emerge until 3-5 min prior to apnea (Group 1, .apprx.28 min post-VR; Group 2, .apprx.15 min post-VR). An idioventricular rhythm, which signaled a failing myocardium, appeared at the same time or shortly after the development of a bradypneic profile. Another notable toxicity component of VR, based on arterial pH, pO2/pCO2 and bicarbonate (HCO3-) level data, was a state of combined hypercapnia, acidemia and hypoxemia during the development of bradypnea. Taken together, findings from this study indicated that changes in medullary respiratory unit activity and ECoG data displayed little, if any, notable signs of CNS perturbation prior to the terminal stage (.apprx.1 min prior to respiratory failure). Thus, in addn. to displaying a greater sensitivity to perturbation by VR, the peripheral cardiorespiratory system components also appeared to play a more important role in pptg. a progressively dysfunctional cardiorespiratory status that ultimately led to collapse of central respiratory mechanisms and death.

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Gas-phase pyrolysis of diisopropyl methylphosphonate. Zegers, E. J. P.; Fisher, E. M. Sibley Sch. Mechanical and Aerospace Eng., Cornell Univ., Ithaca, NY, USA. Combustion and Flame (1998), 115(1/2), 230-240. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 129:58161 AN 1998:377527 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gas-phase pyrolysis studies of diisopropyl methylphosphonate (DIMP) in nitrogen have been conducted to gain insight into the decompn. behavior of organophosphorus chem. warfare nerve agents. Expts. were conducted in a quartz-lined atm. flow reactor between 700 and 800 K, at residence times ranging from 15 to 90 ms. Propylene, isopropanol, iso-Pr methylphosphonate (IMP), and methylphosphonic acid (MPA) were identified as decompn. products of DIMP. FTIR spectrometry was used to quantify parent, propylene, and isopropanol mole fractions in the reactor. The proposed pyrolysis mechanism for DIMP comprises two stages. The first corresponds to the unimol. decompn. of the parent into IMP and propylene. The second involves two competing pathways for the unimol. decompn. of IMP, one leading to isopropanol and the very reactive Me dioxophosphorane; the other to propylene once again and MPA. In the range of temps. studied, an isopropanol to propylene mole fraction ratio close to 0.25 suggests a branching ratio of 1.5 between these two pathways in favor of propylene prodn. The Arrhenius expression for the unimol. decompn. of DIMP was found to be: k[s-1]=10(12.01.5)[s-1] exp(-36.74.9[kcal.mole-1]/(RT)). Pyrolysis expts. with iso-Pr and t-Bu acetates, which have well-known decompn. rates, were performed to illustrate the ability of the app. to produce valid chem. kinetic data. An investigation of the effects of surface to vol. ratio on the DIMP decompn. process shows that wall reactions are significant in a 4-mm i.d. quartz tube, but less important in an 8-mm i.d. tube. Their effects are expected to be small in the 45-mm i.d. reactor.

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GC/MS screening of alkyl methylphosphonofluoridates and alkyl methylphosphonic acids. Rohrbaugh, Dennis K.; Sarver, Emory W. U.S. Army Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 313-347. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:18255 AN 1997:713947 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gas chromatog.-mass spectrometry (GC-MS) and GC-MS-MS techniques, including electron impact, CH4 chem. ionization, and NH3 chem. ionization, were examd. for their use as potential screening techniques to monitor and detect Schedule 1A1 C1-10-alkyl and cycloalkyl methylphosphonofluoridates and the corresponding Schedule 2 hydrolysis products. These compds. [the methylphosphonofluoridates, of general formula MeP(:O)F(OR), and MeP(:O)OH(OR), R = Et, iso-Pr, iso-Bu, pinacolyl, and cyclohexyl] are, or are derived from, common chem. warfare agents. The base peak for all methylphosphonofluoridates in electron-impact mass spectrometry was at m/e 99. Because of low volatility, the methylphosphonic acids were not amenable to GC anal. However, electron impact mass spectra of their trimethylsilyl (TMS) derivs. gave a base peak at m/e 153 and a dominant peak (10-50% of base peak) at m/e 169 for all compds. Chem. ionization mass spectrometry with CH4 and NH3 can not only be used to also screen samples, but it can give information on mol. wt. of specific compds.

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Possibilities of incorporation of the CO2 DIAL detector into the system of atmospheric quality monitoring associated with storing and destruction of chemical weapons. Kadlcak, J.; Dubina, P.; Safar, B. Military Technical Institute of Protection Brno, Brno, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 255-263. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350239 AN 1997:713942 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The CO2 DIAL system is capable of detecting GB and other chem. warfare agents over a distance of 600 m, theor. up to 3.5 km. In addn., the CO2 DIAL system is able to follow the changes in the concn. of monitored species in a cloud. The detection limit with which the concn. of these compds. could be measured is limited by the min. changes in the differential absorption LIDAR returns that could be distinguished from background fluctuations.

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A data analysis routine to protect confidential information during GC-MS analysis. Mcguire, Raymond R.; Martin, Walter H. Arms Control and Treaty Verification Program Lawrence Livermore National laboratory, Livermore, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 229-240. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:9885 AN 1997:713940 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A shell program, MASK was added to the std. GC-MS data anal. code M CODE to protect confidentiality of information not relevant to the Chem. Weapons Convention. This program was demonstrated to work well where high total ion counts are available. A subroutine for blind background subtraction needs to be added for cases where the peak is only slightly above baseline.

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The application of LC/ES-MS in the OPCW/PTS inter-laboratory comparison test. Peng, Lixin; Xu, Danian. Research Institute of Chemical Defence, Beijing, Peop. Rep. China. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 225-228. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350237 AN 1997:713939 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Structural identification of several Chem. Warfare Convention-related compds., (R)P(O)(OH)2, (CH3)p(O)(OH)(OR), bis(2-chloroethyl)ethylamine, o-cyclopentyl-S-2-(diethylamino)ethylmethylphosphonothiolate, N,N-diethylaminoethanol, and ethyldiethanolamine, using HPLC/emission spectroscopy-mass spectrometry is presented, and the main fragmentation pattern under ES-MS is discussed. LC/ES-MS can det. high wt. mol. and structural anal. of polar, low mol. wt. analytes, esp. phosphonic acid.

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Air monitoring equipment for CW destruction facilities with special emphasis on OCW destruction. Starrock, Volker; Doering, Hans Ruediger. German Armed Forces NBC Defence Establishment, Munster, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 157-180. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350386 AN 1997:713936 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A discussion is given on the air monitoring system in chem. warfare agent destruction site. It includes monitoring system, destruction activities, and anal.

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GCQ GC/MS system: preliminary experiences. Cermak, J. CETA Analytical Department, Research Institute for Organic Syntheses, Pardubice - Rybitvi, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 133-146. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350634 AN 1997:713934 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A discussion is given on the GC/MS system in relation to destruction of chem. warfare agents.

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GC/MS investigation of Ethyl S-2-diisopropyl aminoethyl methylphosphonothiolate (VX) age decomposition products. Sliwakowski, M. Military Institute of Chemistry and Radiometry, Warsaw, Pol. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 127-132. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:39042 AN 1997:713933 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sample of VX stored for a long time in glass container was investigated using GC/MS system. A variety of age decompn. products including O-alkyl and N,N-diisopropylamino- substituted thiophosphonic esters and acids as well as phosphonic anhydrides were identified. Diazomethane methylation was used to obtain derivs. convenient to GC process. Retention parameters and EI-MS spectra were obtained and presented.

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Chemical ionization and electron impact mass spectrometry of some methylphosphonothiolates. Podborsky, V.; Stein, V. Military Technical Institute of Protection, Brno, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 109-125. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:3728 AN 1997:713932 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mass spectrometric data of 18 organophosphorus compds. from the family of V-agents were studied. MS spectra of S-2-dimethyl-, S-2-diethyl-, S-2-dipropyl-, S-2-diisopropyl- and S-2-dibutylaminoethyl O-alkyl methylphosphonothiolates were measured in EI and CI modes. MS spectra were completed with some toxicol. data of these organophosphorus compds.

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Application of some modern sample introduction techniques and Poraplot Q GC column in the analysis of volatile toxic compounds. Bardarov, V.; Tashkov, V. Military Medical Academy, Sofia, Bulg. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 77-97. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350235 AN 1997:713929 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. of toxic substances is difficult due to the complexity of the matrixes and usual requirements of multi-component anal. leading to application of chromatog. sepn. The greatest part of chem. warfare agents, their precursors, and degrdn. products demonstrate significant vapor pressure and cause measurable concns. in the gaseous environment at ambient or slightly increased temps. This results in problems for sampling and sample prepn., but favorable distribution of analytes and matrix components among the matrix or suitable sorbent and the gaseous environment may occur and can be used in some techniques to combine sampling, sample prepn., and sample introduction when analyzed using gas chromatog. These techniques, headspace, thermodesorption, and gas extn., realized using different instrument variants in combination with gas chromatog. sepn., are discussed.

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On-site sample work-up procedures to isolate chemical warfare related compounds using solid phase extraction and solid phase microextraction technology. Alcaraz, A.; Hulsey, S. S.; Whipple, R. E.; Andresen, B. D. Lawrence Livermore National Laboratory, Forensic Science Center, Livermore, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 65-76. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350879 AN 1997:713928 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To rapidly prep. and accurately analyze suspect samples for on-site investigations of chem. warfare agents, new methods and field portable equipment, including collection, prepn., and anal. of suspect samples, were required. Using solid phase extn., sample prepn. time was greatly reduced and cumbersome lab. equipment was eliminated. Three different portable modules to achieve on-site field anal. capability were developed. The first consisted of pre-cleaned, sealed sample collection equipment capable of obtaining any type of sample. The second module allowed for complete chem. work-up of collected samples to prep. them for instrumental anal. The third module contained anal. instrumentation necessary for chem. identification, including gas chromatog.-flame photometric detection and gas chromatog.-mass spectrometry for pos. compd. identification. Two field exercises were conducted to provide information on detection limits of on-site anal. approach for soil, water, and swipe samples. Both exercises showed the on-site anal. equipment can be easily deployed. All chem. warfare-related compds. were readily identified using the solid phase extn. technol. and portable anal. equipment. Results were later confirmed by analysts in inhouse labs.

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Super Toxic Analytical Glovebox System (STAGS). Henry, Charles E.; Heyl, Monica; Reutter, Dennis; Diez, Hernan; Landy, Keith. U.S. ARMY, ERDEC, AMC Treaty Laboratory, AMSCB-ACL, APG-EA, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 59-63. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350413 AN 1997:713927 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The US Army was directed to dispose of the stockpile of unitary chem. weapons by Public Law 99-145 and subsequent amendments. This stockpile consists primarily of the agents, VX, HD, and GB, contained in a variety of munitions and bulk containers. To minimize the total risk to the public and the environment posed by chem. weapons storage and disposal, the National Research Council recommended the Army continue the current baseline incineration program while evaluating alternative technologies as replacements for the liq. incinerator used in agent destruction. To accomplish research necessary to det. the efficiency of neutralization, field grade chem. agents were characterized on-site in their natural environment. An on-site purity anal. for ton container survey at 3 storage sites was conducted. Super toxic anal. glovebox system (STAGS), an anal. equipment platformed within a regulated enclosure was designed to successfully perform super toxic work in the field. Development and initial testing of STAGS is discussed.

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Analytical control for destruction of chemical weapons. Requirements and organization. Myasoedov, B. F. V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 39-58. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350412 AN 1997:713926 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An effectively operating anal. control system for chem. weapons destruction in Russia is discussed. The Russian chem. weapons stockpile identified for destruction includes V-gas, sarin, soman, mustard gas, lewisite, and mustard gas-lewisite mixts. amounting to 40,000 tons of chem. warfare agents. Key problems include safety provisions for humans and the environment regarding chem. weapons storage, transportation, and destruction; neutralization of detoxification products; use of solid wastes; and physicochem. parameters of chem. warfare prodn. testing; and disposal of chem. warfare agents and sites. To meet these requirements, an effective system of anal. control coupled with a computer-assisted information system capable of providing expert with high quality reliable data is essential. The operation and elements of this control system are discussed.

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Development of analytical technologies for the alternatives to incineration program. Reutter, Dennis J.; Sumpter, Kenneth; Vickers, Eugene; Simak, Richard; Henry, Charles; Hoffland, Lynn; Smith, Philip B.; Brickhouse, Mark. U.S. Army, ERDEC, AMC Treaty Laboratory, AMSCB-ACL, APG-EA, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 27-38. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:336178 AN 1997:713925 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various aspects of the destruction of chem. weapons are discussed using VX as an example including the development of anal. technologies for the alternatives to incineration program .

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Project SWIFTSURE: destruction of chemical agents at Defense Research Establishment Suffield. Mcandless, John M.; Boulet, Camille A. Defence Research Establishment Suffield, Medicine Hat, AB, Can. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 1-14. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 127:350492 AN 1997:713923 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 11 refs., on the project location, waste inventory, operational concept, environmental monitoring, and destruction of chem. agents.

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Pyrethroid decrease in central nervous system from nerve agent pretreatment. Buchholz, Bruce A.; Pawley, Norma H.; Vogel, John S.; Mauthe, Robert J. Lawrence Livermore National Laboratory, Livermore, CA, USA. Journal of Applied Toxicology (1997), 17(4), 231-234. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 127:172426 AN 1997:560828 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors studied the effect of pyridostigmine bromide, a nerve agent prophylactic, on the central nervous system (CNS) uptake of [14C]permethrin, a pyrethroid insecticide, at scaled human-equiv. exposures in rats using accelerator mass spectrometry (AMS). AMS detects 14C at attomole sensitivities and dets. the tissue distribution of 14C-labeled compds. Pyridostigmine bromide in chow at 7.75 mg kg-1 per day lowered the CNS tissue levels of permethrin, dosed at 4.75 g kg-1, in the CNS of rats by 30%. These results are inconsistent with hypothesized synergy of such compds. as a precursor to "Gulf War syndrome".

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Sulchem process for treatment of chemical weapons-related wastes. Berkey, Edgar; Paff, Stephen W.; King, A. Bruce. Center for Hazardous Materials Research, University of Pittsburgh Applied Research Center, Pittsburgh, PA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 129-148. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:180466 AN 1997:545010 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The Sulchem process is a chem. treatment process that uses elemental S at elevated temps. in an O-free environment to clean up soil contaminated with org. and metallic waste. The process relies on the high reactivity of S and its ability to oxidize org. compds. rapidly and non-selectively at reaction conditions. Org. compds. react with the S to form an inert fine solid of C and S, as well as a variety of simple gases whose compn. varies with the waste material being treated. Byproduct gases may be scrubbed or treated to recover elemental S using an auxiliary process unit. Heavy metals contained in the soil react to form insol. sulfides that become immobilized. The process is potentially applicable to a variety of chem. weapons-related wastes, including soil contaminated with chem. agents, nerve agents, or energetics. The Sulchem process is operated as a 2-stage system at 300-350. Org. compds. that are not volatilized from the soil are completely destroyed in the 1st reactor, in which the insol. metallic sulfides are also formed. A 2nd stage S/vapor reactor is used to destroy orgs. desorbed from the soil reactor. A series of bench-scale and pilot-scale test have been conducted that support feasibility of the process. Projected remediation costs using the process are estd. at $105-$183/ton based on site size, reactor configuration, and processing rate.

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The application of the Silver II electrochemical oxidation process for the demilitarization of non-stockpile material. Batey, W.; Warren, N. AEA Technology, Caithness, UK. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 103-127. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:194862 AN 1997:545009 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The Silver II Process is a recognized alternative technol. to incineration for the demilitarization of chem. munitions. This paper describes an integrated electrochem. cutting method for the breakdown of munitions with the Silver II Process being used to demilitarize the recovered org. material and decontaminate the shell casing. The Silver II Process is a low temp. and pressure electrochem. oxidn. process which stops when the electrochem. cell current is stopped. The offgases comply with environmental discharge stds. All liq. wastes are stored on-site pending return to a central depot for regeneration. The liq. wastes from the regeneration plant are discharged at the central depot once they have been confirmed to be free of chem. agent. The proposed concept provides a mobile soln. for the demilitarization of recovered buried conventional and chem. weapons. The concept is applicable to the remediation of small and large formerly used defense sites.

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Chemical detoxification of chemical weapons applying sodium-technology. Bilger, Edgar. c/o Dr. Bilger Umweltconsulting GmbH, Freigericht, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 71-82. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:194861 AN 1997:545008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A cost-effective chem. method to destroy chem. weapons in a mobile unit using Na is described. Case studies for the destruction of Adamsite or mustard are highlighted. Using Na technol., the chem. can be controlled and analyses can be made at any stage of treatment since all substances are kept in closed compartments until the products are released after thorough final anal. Advantages of the Na technol. include: low temp.; chem. weapon mineralization; low investment cost; inexpensive reagents; no formation of dioxins or furans (vs. incineration); prodn. of solid or dissolved reaction products; no hazardous gases released; and mobile detoxification units.

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Cryofracture as a mobile demilitarization technology for non-stockpile chemical munitions. Spritzer, M. H.; Johnson, L. D. General Atomics, San Diego, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 19-39. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:180485 AN 1997:545005 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Cryofracture is a demilitarization process that has been under development for chem. agent munitions for over 12 yr. Cryofracture uses liq. N to pre-cool munitions prior to fracturing in a hydraulic press. Cryofracture exposes the chem. agents and explosives for subsequent destruction by other means such as thermal or chem. treatment. The cryofracture process is designed to demilitarize projectiles, cartridges, mortar rounds, mines and rockets. Over $60 million has been spent by the US Army to develop cryofracture for demilitarization of chem. agent munitions stored at stockpile sites in the US. Extensive tests have been performed with live explosives and simulant agents, and the test results verify all key aspects of the process. More recently, the cryofracture process has been applied to conventional munitions with the same good results. The process is also likely to find application for non-stockpile chem. munitions in the US and throughout the world. A description of the process and the results of extensive testing are presented, with particular emphasis on the adaptation of cryofracture to non-stockpile chem. munitions.

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Radial Heterogeneity of Impregnated Active Carbon Particles. Buczek, B.; Zietek, S.; Swiatkowski, A. University of Mining and Metallurgy, Krakow, Pol. Langmuir (1997), 13(5), 1342-1344. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 126:122909 AN 1997:126980 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Texture and sorptive properties of the active carbon, before and after impregnation with the soln. of Cr, Cu, and Ag salts, were investigated. Initial active carbon and the impregnated one were sep. subjected to abrasion in a spouted bed, thus obtaining core samples with different degrees of external layers removed. They were analyzed by means of densimetry, mercury porosimetry, and adsorption techniques. The pore vol. was detd. from measurements of true and real densities. Mercury porosimetry was used to est. vol. pores in the macropore range. Mesopore and micropore structures were detd. using benzene adsorption/desorption isotherms. Both the active carbon and impregnated active carbon showed radial changes in the micro-, meso-, and macropore structure. For impregnated active carbon samples the amt. of deposited material and sorption of ClCN were measured. The outer regions of particles were richer in active material whose distribution was analyzed. Samples with removed external layers exhibited substantially higher protective efficiency against cyanogen chloride.

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Comparative evaluation of benzodiazepines for control of soman-induced seizures. McDonough J H Jr; McMonagle J; Copeland T; Zoeffel D; Shih T M Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Archives of toxicology (1999 Nov), 73(8-9), 473-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10650919 AN 2000114341 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This study evaluated the ability of six benzodiazepines to stop seizures produced by exposure to the nerve agent soman. Guinea pigs, previously prepared with electrodes to record electroencephalographic (EEG) activity, were pretreated with pyridostigmine (0.026 mg/kg, i.m.) 30 min before challenge with soman (56 microg/kg, s.c.) and then treated 1 min after soman exposure with atropine (2.0 mg/kg, i.m.) and pralidoxime chloride (2-PAM Cl; 25 mg/kg, i.m.). All animals developed seizures following this treatment. Benzodiazepines (avizafone, clonazepam, diazepam, loprazolam, lorazepam, and midazolam) were given i.m. 5 or 40 min after seizure onset. All benzodiazepines were effective in stopping soman-induced seizures, but there were marked differences between drugs in the rapidity of seizure control. The 50% effective dose (ED50) values and latencies for anticonvulsant effect for a given benzodiazepine were the same at the two times of treatment delay. Midazolam was the most potent and rapidly acting compound at both treatment times. Since rapid seizure control minimizes the chance of brain damage, use of midazolam as an anticonvulsant may lead to improved clinical outcome in the treatment of nerve agent seizures.

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Sulphur mustard induced DNA damage in mice after dermal and inhalation exposure. Lakshmana Rao P V; Vijayaraghavan R; Bhaskar A S Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India. drde@gwr1.dot.net.in Toxicology (1999 Nov 29), 139(1-2), 39-51. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10614687 AN 2000080350 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulphur mustard (SM) is a chemical warfare agent of the blistering agent category for which there is still no effective therapy. SM, being a strong electrophile, readily reacts with a wide range of cellular macromolecules including DNA, RNA and protein. Since the main intoxication routes for SM are inhalation and dermal penetration, in the present study we have exposed female mice to different concentrations of SM by dermal and inhalation exposures and estimated the DNA damage in different organs viz., liver, lung, spleen and thymus. SM was applied at 38.7, 77.4, 154.7 mg/kg body weight, on the hair-clipped skin (dermal exposure) equivalent to 0.25, 0.5 and 1.0 of the LD50. Inhalation exposure was carried out at 10.6, 21.2 and 42.3 mg/m3 for 1 h duration equivalent to 0.25, 0.5 and 1.0 LC50. SM induced a dose-dependent DNA damage in all the organs except the lung in dermal exposure. Similarly the inhalation exposure resulted in dose- and time-dependent effect in all the organs including lung. By both routes of exposure liver was the most affected organ followed by spleen, thymus and lung in decreasing order. The quantitative data were corroborated by qualitative analysis of DNA on agarose gel electrophoresis. The genomic DNA analysis of the organs had revealed random nuclear DNA fragmentation resulting in a 'smear' typical of necrotic form of cell death. Since DNA damage is not reversible especially in liver, this can be used as a marker for SM exposure through either the dermal or inhalation route.

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Development of reactive topical skin protectants against sulfur mustard and nerve agents. Koper O; Lucas E; Klabunde K J Nantek, Inc., 1500 Hayes Drive, and Department of Chemistry, Kansas State University, Manhattan, KS 66502, USA Journal of applied toxicology : JAT (1999 Dec), 19 Suppl 1 S59-70. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10594903 AN 2000062800 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The potential for highly reactive nanoparticles (RNP) to absorb destructively, i.e. to neutralize highly toxic substances such as the warfare agents GA, GB, HD and VX, has been demonstrated in the laboratory. Reactive nanoparticles represent a new class of nanoscale particles of metals and metal oxides that differ from other nanoparticles in reactivity and crystalline morphology. The potential for incorporating RNP into a protective barrier skin cream also has been demonstrated. Preliminary studies indicate that RNP are physically and chemically compatible with a base cream provided by the Army Medical Research Office and, importantly, remain reactive with chemical agents while promising to be compatible with skin contact. Copyright 1999 John Wiley & Sons, Ltd.

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Efficacy of the topical skin protectant in advanced development. Liu D K; Wannemacher R W; Snider T H; Hayes T L US Army Medical Material Development Activity, 622 Neiman Street, Fort Detrick, MD 21702-5009, USA Journal of applied toxicology : JAT (1999 Dec), 19 Suppl 1 S40-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10594900 AN 2000062797 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A topical skin protectant (TSP) (ICD 2289) is being developed to protect service members from exposure to chemical warfare agents (CWA). The TSP is designed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clinical studies, is a cream containing two chemically inert substances: perfluoroalkylpolyether and polytetrafluoroethylene. Animal data showed that the TSP was effective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by preventing the development of erythema and edema. The insect repellent N,N-diethyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protection was sustained when DEET was removed with a dry gauze prior to TSP application. The TSP was also effective against percutaneous exposure of nerve agents-thickened (with 5% methyl methacrylamide) soman (TGD) and VX (O-ethyl-S-[2-(diisopropylamino)ethyl]methylphosphonothioate )-by reducing the mortality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when DEET was applied prior to TSP application. Because human efficacy studies using CWA cannot be conducted, the efficacy will be demonstrated by the level of protection against poison ivy (urushiol) contact dermatitis in humans.

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Two-generation reproduction study of lewisite in rats. Sasser L B; Cushing J A; Lindenmeier C W; Mellick P W; Dacre J C Molecular Bioscience Department, Battelle, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1999 Jul-Aug), 19(4), 229-35. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10439336 AN 1999368191 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Lewisite, a potent toxic vesicant and chemical warfare agent, is used in a number of research laboratories, is stored in large quantities at depot sites throughout the USA and is occasionally transported to distant sites. Thus, the potential for environmental or occupational exposure exists where lewisite is present. A 42-week two-generation study was conducted to determine the reproductive consequences of lewisite in parental male and female rats and their offspring. Rats were administered lewisite in sesame oil (0, 0.10, 0.25 or 0.60 mg kg-1 day-1 for 5 days a week) via intragastic intubation before mating, during mating and after mating until the birth of their offspring. The dams continued to receive lewisite during lactation. At weaning, male and female offspring of each group were selected to continue the study, receiving lewisite during adolescence, mating and throughout gestation and lactation. Lewisite had no adverse effect on reproduction performance, fertility or reproductive organ weights of male or female rats through two consecutive generations. No adverse effects to offspring were attributed to lewisite exposure. Minor changes in growth were the only maternal effects observed. Lewisite exposure of parental rats caused no gross or microscopic lesion in testes, epididymis, prostate, seminal vesicles, ovaries, uterus or vagina. The no-observable-effect level (NOEL) for the reproductive effects of Lewisite would be > 0.60 mg kg-1 day-1.

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Effect of lowered temperature on the toxicity of sulphur mustard in vitro and in vivo. Sawyer T W; Risk D Therapy Group, Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada. thomas.sawyer@dres.dnd.ca Toxicology (1999 May 3), 134(1), 27-37. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10413186 AN 1999339531 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Primary cultures of chick embryo neurons were exposed to sulphur mustard (HD) and L-nitroarginine methyl ester (L-NAME) and then incubated at either 25 or 37 degrees C. Lowering the temperature of the cultures decreased the 24-h toxicity of HD, but did not increase the efficacy of L-NAME protection. However, the length of time post-HD treatment in which L-NAME was maximally effective in protecting against HD toxicity was dramatically enhanced, out to 12 h after HD exposure. In addition, the persistence of L-NAME protection of the cells against HD was significantly lengthened. Tests conducted in human skin keratinocytes also showed that lowering the incubation temperature of actively proliferating, just-confluent or post-confluent cultures significantly and persistently decreased the cytotoxicity of HD. The persistence of L-NAME protection was increased in non-proliferating cells. Finally, cooling of HD-vapour exposed sites on hairless guinea pigs for 4.5 h decreased the severity of the resultant lesions out to 72 h post-exposure.

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The interaction of sarin and soman with plasma proteins: the identification of a novel phosphonylation site. Black R M; Harrison J M; Read R W DERA, CBD Porton Down, Salisbury, Wilts, UK Archives of toxicology (1999 Mar), 73(2), 123-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10350193 AN 1999277696 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Incubation of both sarin and soman with human plasma has shown that binding occurs to a tyrosine residue. Similar binding occurs when sarin and soman are incubated with human serum albumin. This binding may provide an important biological marker, which retains full structural information concerning the identity of the agent, in cases of allegations of chemical warfare use.

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Acute soman poisoning in primates neither pretreated nor receiving immediate therapy: value of gacyclidine (GK-11) in delayed medical support. Lallement G; Clarencon D; Galonnier M; Baubichon D; Burckhart M F; Peoc'h M Unite de Neuropharmacologie, CRSSA-BP, La Tronche, France. 100437,201@compuserve.com Archives of toxicology (1999 Mar), 73(2), 115-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10350192 AN 1999277695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Organophosphorus (OP) nerve agents are still used as warfare and terrorism compounds. Classical delayed treatment of victims of organophosphate poisoning includes combined i.v. administration of a cholinesterase reactivator (an oxime), a muscarinic cholinergic receptor antagonist (atropine) and a benzodiazepine anticonvulsant (diazepam). The objective of this study was to evaluate, in a realistic setting, the therapeutic benefit of administration of GK-11 (gacyclidine), an antiglutamatergic compound, as a complement to the above therapy against organophosphate poisoning. Gacyclidine was injected (i.v.) in combination with atropine/diazepam/pralidoxime at man-equivalent doses after a 45- or 30-min latency period to intoxicated primates (2 LD50). The effects of gacyclidine on the animals' survival, electroencephalographic (EEG) activity, signs of toxicity, recovery after challenge and central nervous system histology were examined. The present data demonstrated that atropine/diazepam/pralidoxime alone or combined with gacyclidine did not prevent signs of soman toxicity when treatment was delayed 45 min after poisoning. Atropine/diazepam/pralidoxime also did not control seizures or prevent neuropathology in primates exhibiting severe signs of poisoning when treatment was commenced 30 min after intoxication. However, in this latter case, EEG recordings revealed that additional treatment with gacyclidine was able to stop soman-induced seizures and restore normal EEG activity. This drug also totally prevented the neuropathology observed 5 weeks after soman exposure in animals treated with atropine/diazepam/pralidoxime alone. Overall, in the case of severe OP-poisoning, gacyclidine represents a promising adjuvant therapy to the currently available polymedication to ensure optimal management of organophosphate poisoning in man. This drug is presently being evaluated in a human clinical trial for a different neuroprotective indication.
However, it should always be kept in mind that, in the case of severe OP-poisoning, medical intervention must be conducted as early as possible.

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Evaluation of neutralized chemical agent identification sets (CAIS) for skin injury with an overview of the vesicant potential of agent degradation products. Olajos E J; Olson C T; Salem H; Singer A W; Hayes T L; Menton R G; Miller T L; Rosso T; MacIver B Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD 21010, USA Journal of applied toxicology : JAT (1998 Nov-Dec), 18(6), 409-20. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9840748 AN 1999054483 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Vesication and skin irritation studies were conducted in hairless guinea-pigs to determine the vesicant and skin irritation potential of chemically-neutralized Chemical Agent Identification Sets (CAIS). The CAIS are training items that contain chemical warfare-related material--sulfur mustard (HD), nitrogen mustard (HN) or lewisite (L)--and were declared obsolete in 1971. Animals were dosed topically with 'test article'--neat HD, 10% agent/chloroform solutions or product solutions (waste-streams) from neutralized CAIS--and evaluated for skin-damaging effects (gross and microscopic). Product solutions from the chemical neutralization of neat sulfur mustard resulted in microvesicle formation. All agent-dosed (HD or agent/chloroform solutions) sites manifested microblisters as well as other histopathological lesions of the skin. Waste-streams from the neutralization of agent (agent/chloroform or agent/charcoal) were devoid of vesicant activity. Cutaneous effects (erythema and edema) were consistent with the skin-injurious activity associated with the neutralizing reagent 1,3-dichloro-5,5-dimethylhydantoin (DCDMH). Chemical neutralization of CAIS was effective in eliminating/reducing the vesicant property of CAIS containing agent in chloroform or agent on charcoal but was inefficient in reducing the vesicant potential of CAIS containing neat sulfur mustard.

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Inhibition, reactivation and aging kinetics of cyclohexylmethylphosphonofluoridate-inhibited human cholinesterases. Worek F; Eyer P; Szinicz L Institut fur Pharmakologie und Toxikologie, Sanitatsakademie der Bundeswehr, Garching, Germany Archives of toxicology (1998 Sep), 72(9), 580-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9806430 AN 1999021267 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (cyclosarin) is a highly toxic organophosphate, which was shown to be rather resistant to conventional oxime therapy. To give more insight into the inhibition, reactivation and aging kinetics, human acetyl-(AChE) and butyrylcholinesterase (BChE) were inhibited by cyclosarin (k2 of 7.4 and 3.8 x 10(8) M(-1) min(-1), respectively; pH 7.4, 37 degrees C) and reactivated with obidoxime, pralidoxime and three experimental oximes. The new oxime HLo 7 (1-[[[4-aminocarbonyl)-pyridinio]-methoxy]-methyl]-2,4-bis-[ (hydroxyimino)methyl] pyridinium dimethanesulphonate) was shown to be superior to the other oximes. At oxime concentrations anticipated to be relevant in humans, obidoxime and pralidoxime were extremely weak reactivators of AChE. Aging velocity of BChE was almost fourfold higher compared to AChE (ka of 0.32 h(-1) and 0.08 h(-1), respectively). A substantial spontaneous reactivation was observed with AChE. These results support previous in vivo findings that obidoxime and pralidoxime are insufficient antidotes in cyclosarin poisoning. By contrast, HLo 7 was shown to be an extremely potent reactivator of human AChE and BChE, which supports its position as a broad-spectrum oxime.

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Acute inhalation toxicity of neutralized chemical agent identification sets (CAIS) containing agent in chloroform. Olajos E J; Morgan E W; Renne R A; Salem H; McVeety B; Johnson R; Phelps R L Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD 21010-5423, USA Journal of applied toxicology : JAT (1998 Sep-Oct), 18(5), 363-71. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9804437 AN 1999019582 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

An acute head-only inhalation study was conducted in rats exposed for 1 h to product solution (wastestream) resultant from the chemical neutralization of Chemical Agent Identification Sets (CAIS) containing agent (sulfur mustard (HD), nitrogen mustard (HN-1) or lewisite (L)) in chloroform. Groups of Sprague-Dawley rats were exposed to varying concentrations (24000, 18000, 12000 or 6000 ppm) of CAIS wastestream. An additional group was exposed to the vehicle (chloroform/t-butanol) only, at a concentration equivalent to the concentration of vehicle at the highest exposure level. Animals were evaluated for toxic effects, including assessment of toxicant-induced alterations to the ocular and respiratory systems. Mortality on exposure to 24000 ppm of test article or to vehicle alone was high. Mortality in the other exposure groups was roughly proportional to the concentration of test article (wastestream). Toxic signs were consistent with exposure to solvent system components (chloroform/t-butanol) and to agent decomposition products/by-products. Incidence and severity of ocular effects were similar in vehicle control and treatment groups. The salient respiratory effect observed was a decreased minute volume, which was also noted in vehicle and treatment groups.

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Cardiorespiratory effects of O-isobutyl S-[2-(diethylamino)-ethyl] methylphosphonothioate -- a structural isomer of VX. Chang F C; Gouty S C; Eder L C; Hoffman B E; Maxwell D M; Brecht K M US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1998 Sep-Oct), 18(5), 337-47. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9804434 AN 1999019579 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

O-Isobutyl S-[2-(diethylamino)ethyl]methylphosphonothioate (VR) is a structural isomer of a more well-known chemical warefare agent, O-ethyl S-[2(diisopropylamino)ethyl]methylphosphonothioate (code designation VX). In this study, cardiorespiratory and central nervous system (CNS) effects of VR (2LD50 or 22.6 microg kg(-1); s.c.) were evaluated in urethane-anesthetized (Group 1) and unanesthetized (Group 2) guinea pigs instrumented for concurrent recordings of electrocorticogram (ECoG) and a variety of cardiorespiratory activities. The first sign of intoxication was a state of progressive bradycardia, vascular hypotension and arrhythmia (Group 1, approximately 13 min post-VR; Group 2, approximately 6 min post-VR). Bradypnea, excessive salivation and compensatory changes in blood pressure typically did not emerge until 3-5 min prior to apnea (Group 1, approximately 28 min post-VR; Group 2, approximately 15 min post-VR). An idioventricular rhythm, which signalled a failing myocardium, appeared at the same time or shortly after the development of a bradypneic profile. Another notable toxicity component of VR, based on arterial pH, pO2/pCO2 and bicarbonate (HCO3-) level data, was a state of combined hypercapnia, acidemia and hypoxemia during the development of bradypnea. Taken together, findings from this study indicated that changes in medullary respiratory unit activity and ECoG data displayed little, if any, notable signs of CNS perturbation prior to the terminal stage (approximately 1 min prior to respiratory failure). Thus, in addition to displaying a greater sensitivity to perturbation by VR, the peripheral cardiorespiratory system components also appeared to play a more important role in precipitating a progressively dysfunctional cardiorespiratory status that ultimately led to collapse of central respiratory mechanisms and death.

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Effect of sulphur mustard inhalation exposure on some urinary variables in mice. Kumar O; Vijayaraghavan R Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India Journal of applied toxicology : JAT (1998 Jul-Aug), 18(4), 257-9. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9719425 AN 1998383930 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The effect of sulphur mustard (2,2'-dichlorodiethyl sulphide) exposure through inhalation at 0.5. 1.0 and 2.0 LC50 (21.2, 42.3 and 84.6 mg m(-3) for 1 h) on some urinary variables was studied in female mice at 6, 24 and 48 h and 7 days post-exposure. The urinary excretion and circulatory blood accumulation of uric acid increased significantly. The level of creatine was also elevated significantly as compared to the control at 2 LC50. It is concluded that sulphur mustard alkylates DNA and triggers catabolism of apurinated purine bases in a very short time. The increase in uric acid excretion in urine can be detected only when the exposure concentration is high.

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Nerve agent poisoning in primates: antilethal, anti-epileptic and neuroprotective effects of GK-11. Lallement G; Clarencon D; Masqueliez C; Baubichon D; Galonnier M; Burckhart M F; Peoc'h M; Mestries J C Unite de Neurotoxicologie, CRSSA, La Tronche, France Archives of toxicology (1998), 72(2), 84-92. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9456079 AN 1998115614 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Organophosphorus nerve agents are still in use today in warfare and as terrorism compounds. Classical emergency treatment of organophosphate poisoning includes the combined administration of a cholinesterase reactivator (an oxime), a muscarinic cholinergic receptor antagonist (atropine) and a benzodiazepine anticonvulsant (diazepam). However, recent experiments with primates have demonstrated that such treatment, even when administered immediately after organophosphate exposure, does not rapidly restore normal electroencephalographic (EEG) activity and fails to totally prevent neuronal brain damage. The objective of this study was to evaluate, in a realistic setting, the therapeutic benefit of administration of GK-11 (gacyclidine), an antiglutamatergic compound, as a complement to the available emergency therapy against organophosphate poisoning. GK-11 was injected at a dose of 0.1 mg/kg (i.v) after a 45-min latency period to heavily intoxicated (8 LD50) primates. Just after intoxication, man-equivalent doses of one autoinjector containing atropine/pralidoxime/diazepam were administered. The effects of GK-11 were examined on survival, EEG activity, signs of toxicity, recovery after challenge and central nervous system histology. The present data demonstrate that treatment with GK-11 prevents the mortality observed after early administration of classical emergency medication alone. EEG recordings and clinical observations also revealed that GK-11 prevented soman-induced seizures and motor convulsions. EEG analysis within the classical frequency bands (beta, theta, alpha, delta) demonstrated that central activity was totally restored to normal after GK-11 treatment, but remained profoundly altered in animals receiving atropine/pralidoxime/diazepam alone. GK-11 also markedly accelerated clinical recovery of soman-challenged primates. Lastly, this drug totally prevented the neuropathology observed 3 weeks after soman exposure in animals treated with classical emergency treatment alone.
GK-11 represents a promising adjuvant therapy to the currently available emergency polymedication to ensure optimal management of organophosphate poisoning in man. This drug is presently being evaluated in a human clinical trial for a different neuroprotective indication.

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A model for quantitative measurement of sulfur mustard skin lesions in the rabbit ear. Zlotogorski A; Goldenhersh M; Shafran A Department of Dermatology, Hadassah University Hospital, Jerusalem, Israel. zloto@cc.huji.ac.il Toxicology (1997 Jun 27), 120(2), 105-10. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9184197 AN 97327530 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The search for treatment and protection against the vesicant and inflammatory skin lesions induced by sulfur mustard suffers from the lack of a good in vivo reproducible model. We applied sulfur mustard (25-500 microg/cm2) to the outer surface of the ears of 10 rabbits and measured the edema formation 12, 24 and 48 h post-application with a caliper especially designed for soft matter. There was a dose-dependent linear increase in edema magnitude in the range from 25 to 150 microg/cm2. Maximal edema was observed after 12 h. There was a 12% reduction in edema size 24 h after application and a further decrease after 48 h. Skin thickness, inflammatory cell infiltrate, necrosis and vesiculation were evaluated in biopsies taken after 24 h. We found the same dose-related increase both in skin thickness and in degree of blister formation. This simple dose-response in vivo model can be used for evaluation of the dermal inflammation induced by topical application of sulfur mustard. This model has the additional advantage of a built-in control, namely the untreated contralateral ear. Consequently, this model can serve as a useful tool for future screening of potential compounds for prevention and treatment of sulfur mustard-induced skin lesions.

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Effect of sulphur mustard on the expression of urokinase in cultured 3T3 fibroblasts. Detheux M; Jijakli H; Lison D Laboratory of Medical Toxicology, Catholic University of Louvain, Brussels, Belgium Archives of toxicology (1997), 71(4), 243-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9101041 AN 97255694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The expression of plasminogen activator (PA), a serine proteinase involved in the degradation of extracellular matrix proteins, has been investigated in 3T3 fibroblasts after in vitro exposure to sulphur mustard (SM). Expression of the cell-associated enzyme has been assessed with a synthetic substrate assay and at the mRNA level. Twenty-four hours after 100 microM SM, cell viability (monitored by MTT assay) was not significantly affected, but protein synthesis (tritiated leucine incorporation) was reduced to < 20% of the control value. PA activity was significantly increased compared to control cells with a 20-fold increase after 24 h. This up-regulation was independent of the cell density, occurred maximally between days 1 and 4 and persisted for at least 6 days after exposure. Lower concentrations of SM (< or = 10 microM) did not significantly affect PA activity. Northern blotting experiments revealed an increased expression of urokinase (u-PA) transcripts in cells treated with 100 microM SM, with a peak at 10 h after exposure. Conditioned culture medium from cell cultures treated with 100 microM SM did not affect the expression of PA activity in naive or SM-treated cultures. Thiodiglycol (100 microM), the main metabolite of SM, did not influence the expression of PA in the same system. Different compounds were tested for modulation of the PA upregulation after SM exposure. Nicotinamide (5 mM), vitamin D3 (10(-10)M), extracellular calcium (2 mM) or EGTA (5 mM) had no effect. Ryanodine (10 microM) amplified the PA up-regulation by a factor of 2 and vanadate (500 microM) reduced it by approximately 50%. Dexamethasone (1 microM) added directly after SM treatment almost completely prevented the induction of PA at both the protein and mRNA levels. Overall these results demonstrate an up-regulation of urokinase in 3T3 fibroblasts after treatment with SM, which is possibly mediated by intracellular calcium mobilization.
Further studies are needed to identify the significance of this proteolytic response in the pathogenesis of blistering and/or DNA repair mechanisms.

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Synthesis and mass spectrometric identification of the major amino acid adducts formed between sulphur mustard and haemoglobin in human blood. Noort D; Hulst A G; Trap H C; de Jong L P; Benschop H P Department of Chemical Toxicology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1997), 71(3), 171-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049054 AN 97201271 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

As part of a program to develop methods for the verification of alleged exposure to sulphur mustard, we synthesized and characterized three amino acid adducts presumably formed by alkylation of haemoglobin: 4-(2-hydroxyethylthioethyl)-L-aspartate, 5-(2-hydroxyethylthioethyl)L-glutamate and N1- and N3-(2-hydroxyethylthioethyl)-L-histidine. Suitable derivatization methods for GC/MS analysis were developed for these adducts as well as for the cysteine and the N-terminal valine adduct. Incubation of human blood with [35S]sulfur mustard in vitro followed by acidic hydrolysis of isolated globin and derivatization with Fmoc-Cl afforded three radioactive peaks upon HPLC analysis, one of which coeluted with the synthetic Fmoc derivative of N1/N3-(2-hydroxyethylthioethyl)-L-histidine. After pronase digestion of globin the adducts of histidine, glutamic acid, aspartic acid, cysteine and N-terminal valine could be tentatively identified and quantitated. Final identification was obtained from GC/MS analysis. The most abundant adduct, N1/N3-(2-hydroxyethylthioethyl)-L-histidine, could not be sensitively analysed by GC/MS. A convenient LC-tandem MS procedure was developed for this compound, enabling the detection of exposure of human blood to 10 microM sulphur mustard in vitro.

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Protective effect of povidone-iodine ointment against skin lesions induced by sulphur and nitrogen mustards and by non-mustard vesicants. Wormser U; Brodsky B; Green B S; Arad-Yellin R; Nyska A Department of Pharmacology, School of Pharmacy, Faculty of Medicine, Hebrew University of Jerusalem, Israel Archives of toxicology (1997), 71(3), 165-70. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049053 AN 97201270 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Mustard gas (sulphur mustard, SM) is a powerful vesicant employed as a chemical weapon. The present study demonstrates the effect of povidone iodine (PI) ointment against skin toxicity caused by SM. Gross and histopathological examinations showed that application of PI up to 20 min following exposure to the vesicant resulted in marked skin protection. The shorter the interval between exposure and treatment the better was the protection achieved. PI was also effective against other mustards such as carboxybutyl chloroethyl sulphide (CBCS) and mechlorethamine. The fact that PI protected the skin against agents which cannot be oxidized such as iodoacetic acid, divinylsulphone and cantharidine showed that the antidotal effect of PI was unrelated to oxidation of the nitrogen and sulphur atoms of the mustards. PI ointment is proposed as an efficient protective agent against skin toxicity caused by mustards and other alkylators.

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Modifications of breathing pattern induced by inhaled sulphur mustard in mice. Vijayaraghavan R Pharmacology and Toxicology Division, Defence Research and Development Establishment, Gwalior, India Archives of toxicology (1997), 71(3), 157-64. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049052 AN 97201269 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A head-only exposure assembly was used for exposing mice to vapours of sulphur mustard (SM). The respiration was monitored using an on-line computer program, capable of recognizing the breathing pattern as sensory irritation, airflow limitation and pulmonary irritation. SM was dissolved in acetone and vapourized using a compressed air nebulizer. Mice were exposed to the vapours (8.5, 16.9, 21.3, 26.8, 42.3 and 84.7 mg/m3) for 1 h in a body plethysmograph fitted with a 20-gauge needle and a microphone for sensing the respiratory flow signals. The signals were amplified, digitized and integrated to give tidal volume, and stored in a computer for further analysis. The respiration of the mice was followed for modifications in the breathing pattern until 7 days post-exposure. SM induced sensory irritation during exposure, and there was a concentration dependent decrease in the respiratory frequency and an increase in tidal volume. Lower concentrations showed recovery after stopping the exposure. RD50, the concentration that depresses 50% of the respiration was estimated to be 27.4 mg/m3. Following exposure to higher concentrations the animals started dying after 6 days. The LC50 was estimated to be 42.5 mg/m3 (14 days observation period). The respiratory frequency decreased on subsequent days of exposure depending upon the exposure concentration, and the breathing pattern was characteristic of airflow limitation. The ratio of flow/tidal volume was decreased following exposure to concentrations of 26.8 and 42.3 mg/m3. The ratio of flow/tidal volume may be a better measurement than the measurements based on flow alone for the assessment of airflow limitation. Pulmonary irritation was not observed showing that the lungs were not affected. The body weight of the animals decreased progressively. The present methodology will be useful for identifying the effects of SM on the respiratory system, one of the endpoints considered when establishing occupational exposure limits.

[megalomania]

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Reactions of sulfides with S-330, a potential decontaminant of sulfur mustard in formulations. Shih, Ming L.; Korte, William D.; Smith, J. Richard; Szafraniec, Linda L. US Army Medical Research Institute of Chemical Defense, APG, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S83-S88. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:289769 AN 2000:132684 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Because the vesicant sulfur mustard (HD) remains a major chem. threat from either domestic terrorists or countries in conflict, topical prepns. are being evaluated as protectants from HD exposure. The objective of this study was to evaluate the effectiveness of chloroamide S-330 as a potential reactive component in topical formulations. Therefore, the rate, mechanism and byproducts of the oxidn. reactions of sulfides by S-330 in solvent media or specific formulation vehicles were investigated. Using NMR, LC, LC-MS and GC-MS, the reactions of S-330 with HD, di-Bu sulfide (DBS) and Me Ph sulfide (MPS) were studied in acetonitrile, chloroform and perfluoropolyether (PFPE) oil. The oxidn. of the three sulfides with S-330 was very rapid and completed in <4 min in acetonitrile-water or PFPE oil, but the rates of reaction in chloroform were significantly slower. In a large excess of S-330, the major products resulted from chlorination of the side chains. At a high HD/S-330 ratio, the major product was HD sulfoxide. Under both conditions, only a trace of HD sulfone, also a blistering agent, was obsd. Reactions with DBS and MPS primarily gave sulfoxides and sulfones, with less side-chain chlorination. The chloroamide S-330 appeared to be a rapid and effective decontaminant of HD in either polar media or in a PFPE oil. The two alkyl and aryl sulfides are suitable simulants of HD for the initial screening and evaluation of S-330 or other similar oxidizing agents.

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Polyoxometalate oxidation of chemical warfare agent simulants in fluorinated media. Johnson, Rhoma P.; Hill, Craig L. Department of Chemistry, Emory University, Atlanta, GA, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S71-S75. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 133:1581 AN 2000:132682 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The aim of this research is to det. if appropriate polyoxometalates (POMs) could be added to perfluoropolyether topical skin protectants (TSPs) currently available or under development to give these TSPs the addnl. capability of detecting and in some cases catalytically decontaminating sulfur mustard (HD) and perhaps other chem. warfare agents (CWAs) at ambient temps. Detection would be based on significant color changes in the POM upon redn. by the CWA whereas catalytic decontamination would be based on the ability of some families of POMs to catalyze O2-based oxidns. by more than one mechanism. Five POMs (10-25% by wt.) were each suspended in .apprx.5 g of the perfluoropolyether (PFPE, CF3O[-CF(CF3)CF2O-]x(-CF2O-)yCF3) "barrier" cream. A stoichiometric amt. of HD sulfide simulant was layered on top of each POM-cream mixt. The short reaction times were recorded for each system. Mechanistic studies were conducted using an PFPE oil analog of the barrier cream in a microemulsion with the sulfide simulant, POM, PFPE surfactant and 2,2,2-trifluoroethanol co-surfactant.

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Development of reactive topical skin protectants against sulfur mustard and nerve agents. Koper, Olga; Lucas, Eric; Klabunde, Kenneth J. Nantek, Inc., Manhattan, KS, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S59-S70. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:261513 AN 2000:132681 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The potential for highly reactive nanoparticles (RNP) to absorb destructively, i.e. to neutralize highly toxic substances such as the warfare agents GA, GB, HD and VX, has been demonstrated in the lab. Reactive nanoparticles represent a new class of nanoscale particles of metals and metal oxides that differ from other nanoparticles in reactivity and cryst. morphol. The potential for incorporating RNP into a protective barrier skin cream also has been demonstrated. Preliminary studies indicate that RNP are phys. and chem. compatible with a base cream provided by the Army Medical Research Office and, importantly, remain reactive with chem. agents while promising to be compatible with skin contact.

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Development of a reactive topical skin protectant. Braue, Ernest H., Jr. Advanced Assessment Branch, Drug Assessment Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S47-S53. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:289768 AN 2000:132679 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The use of a topical skin protectant (TSP) as a means of protecting troops from percutaneous chem. warfare agent (CWA) exposure has been proposed since these weapons were first used during World War I. The TSP is applied to vulnerable skin surfaces prior to entry into a chem. combat area. In 1990, the US Army Medical Research Institute of Chem. Defense transferred two non-reactive TSPs into advanced development. Following US Food and Drug Administration approval, the final product is expected to be available to soldiers in 1999. A continuing research effort is designed to develop a second-generation TSP that will increase effectiveness and also decontaminate CWAs into non-toxic products. We identified a list of 29 reactive moieties as potential additives to the TSP formulation. All candidate formulations are evaluated in a decision tree network, consisting of a series of 11 efficacy testing models. A prototype formulation (ICD 2701) contg. the reactive ingredient S-330 has dramatically improved the protection against satd. sulfur mustard vapor. In addn., we have discovered a compd. (ICD 2837) that significantly increases the skin's natural resistance to CWA penetration. Our goal is to transfer a significantly improved TSP formulation into advanced development by 1999.

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Efficacy of the topical skin protectant in advanced development. Liu, Dai Kee; Wannemacher, Robert W.; Snider, Thomas H.; Hayes, Timothy L. US Army Medical Material Development Activity, Fort Detrick, MD, USA. Journal of Applied Toxicology (1999), 19(Suppl. 1), S41-S45. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 132:261511 AN 2000:132678 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A topical skin protectant (TSP) (ICD 2289) is being developed to protect service members from exposure to chem. warfare agents (CWA). The TSP is designed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clin. studies, is a cream contg. two chem. inert substances: perfluoroalkylpolyether and polytetrafluoroethylene. Animal data showed that the TSP was effective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by preventing the development of erythema and edema. The insect repellent N,N-diethyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protection was sustained when DEET was removed with a dry gauze prior to TSP application. The TSP was also effective against percutaneous exposure of nerve agents-thickened (with 5% Me methacrylamide) soman and VX by reducing the mortality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when DEET was applied prior to TSP application. Because human efficacy studies using CWA cannot be conducted, the efficacy will be demonstrated by the level of protection against poison ivy (urushiol) contact dermatitis in humans.

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Sulfur mustard induced DNA damage in mice after dermal and inhalation exposure. Lakshmana Rao, P. V.; Vijayaraghavan, R.; Bhaskar, A. S. B. Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India. Toxicology (1999), 139(1-2), 39-51. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 132:162248 AN 1999:746442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sulfur mustard (SM) is a chem. warfare agent of the blistering agent category for which there is still no effective therapy. SM, being a strong electrophile, readily reacts with a wide range of cellular macromols. including DNA, RNA and protein. Since the main intoxication routes for SM are inhalation and dermal penetration, in the present study we have exposed female mice to different concns. of SM by dermal and inhalation exposures and estd. the DNA damage in different organs viz., liver, lung, spleen and thymus. SM was applied at 38.7, 77.4, 154.7 mg/kg body wt., on the hair-clipped skin (dermal exposure) equiv. to 0.25, 0.5 and 1.0 of the LD50. Inhalation exposure was carried out at 10.6, 21.2 and 42.3 mg/m3 for 1 h duration equiv. to 0.25, 0.5 and 1.0 LC50. SM induced a dose-dependent DNA damage in all the organs except the lung in dermal exposure. Similarly the inhalation exposure resulted in dose- and time-dependent effect in all the organs including lung. By both routes of exposure liver was the most affected organ followed by spleen, thymus and lung in decreasing order. The quant. data were corroborated by qual. anal. of DNA on agarose gel electrophoresis. The genomic DNA anal. of the organs had revealed random nuclear DNA fragmentation resulting in a 'smear' typical of necrotic form of cell death. Since DNA damage is not reversible esp. in liver, this can be used as a marker for SM exposure through either the dermal or inhalation route.

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Synthesis and mass spectral characterization of diisopropylamino-ethanethiol, -sulfides and -disulfides and vinyl sulfides. Rohrbauch, D. K.; Berg, F. J.; Szafraniec, L. J.; Rossman, D. I.; Durst, H. D.; Munavalli, S. Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, U.S. Army, Aberdeen, MD, USA. Phosphorus, Sulfur and Silicon and the Related Elements (1999), 149 95-106. CODEN: PSSLEC ISSN: 1042-6507. Journal written in English. CAN 132:49741 AN 1999:681810 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The sulfur contg. chem. agent, O-ethyl-S-2-(diisopropylaminoethyl)methylphosphonothiolate, is an extremely potent inhibitor of the enzyme acetylcholinesterase and exhibits extended neurol. effects. It undergoes degrdn. on standing alone or in the environment. Hence, identification of its primary degrdn. products assumes considerable importance. The synthesis and mass spectral fragmentation behavior of the title compds., some of which are present in the O-ethyl-S-2-(diisopropylaminoethyl)methylphosphonothiolate degrdn. products, has not received much attention. This communication describes the synthesis and mass spectral characterization of the title compds.

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Reaction of Bis(2-chloroethyl) Sulfide with N,N'-Dichlorobis(2,4,6-trichlorophenyl)urea. Dubey, D. K.; Malhotra, R. C.; Vaidyanathaswamy, R.; Vijayaraghavan, R. Defence R. & D. Establishment, Gwalior, India. Journal of Organic Chemistry (1999), 64(21), 8031-8033. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 132:12186 AN 1999:629651 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The reaction of bis(2-chloroethyl)sulfide (warfare agent) with N,N'-dichloro-N,N'-bis(2,4,6-trichlorophenyl)urea was describe with the aim of using the latter as a decontamination agent.

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Reactions of VX, HD, and Their Simulants with NaY and AgY Zeolites. Desulfurization of VX on AgY. Wagner, George W.; Bartram, Philip W. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Langmuir (1999), 15(23), 8113-8118. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 131:299202 AN 1999:577485 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The room-temp. reactions of the chem. warfare agents VX (O-Et S-2-(diisopropylamino)ethyl methylphosphonothioate), HD (2,2'-dichloroethyl sulfide, or mustard), and their common simulants, O,S-di-Et phenylphosphonothioate (DEPPT) and 2-chloroethyl Ph sulfide (CEPS), with NaY and silver-exchanged (AgY) zeolites have been studied using solid-state magic angle spinning NMR. VX hydrolyzes via exclusive cleavage of the P-S bond on both NaY and AgY to yield Et methylphosphonate (EMPA). The reaction is significantly faster on AgY than on NaY, suggesting catalysis by silver. On AgY, an intermediate silver salt of EMPA is apparently formed which is slowly converted to Et 2-(diisopropylamino)ethyl methylphosphonate (QB, the desulfurized analog of VX) in about a 78% yield. DEPPT similarly hydrolyzes via P-S cleavage on AgY to yield an apparent silver salt of Et phenylphosphonate, which does not undergo further reaction to the desulfurized analog. No reaction is obsd. for DEPPT on NaY. HD on AgY forms both vinyl sulfide and the cyclic ether 1,4-thioxane. HD reacts faster on NaY to exclusively form the CH-TG sulfonium ion (HOCH2CH2SCH2CH2S+[CH2CH2OH]2). CEPS also reacts faster on NaY, forming 2-hydroxyethyl Ph sulfide. On AgY, CEPS does not give the vinyl product, but does yield the ether product PhSCH2CH2OCH2CH2SPh. A mechanism is proposed for the silver-catalyzed hydrolysis of VX, the desulfurization of the cleaved thiol, and the formation of QB.

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Reaction of a Vesicular Functionalized Surfactant with 2-Chloroethyl Phenyl Sulfide, a Mustard Simulant. Jaeger, David A.; Schilling, Curtis L. III; Zelenin, Alexander K.; Li, Bei; Kubicz-Loring, Elzbieta. Department of Chemistry, University of Wyoming, Laramie, WY, USA. Langmuir (1999), 15(21), 7180-7185. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 131:233071 AN 1999:505232 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Functionalized double-chain surfactant, potassium O,O'-didodecylphosphorodithioate (I) was synthesized. Its small unilamellar vesicles were characterized by dynamic laser light scattering and differential scanning calorimetry and its giant vesicles by phase-contrast optical microscopy. Also, I's giant vesicles contg. fluorescent dye, 5-carboxyfluorescein or 5-(dodecanamido)fluorescein, were characterized by epifluorescence microscopy. In a pH 9.0 borate buffer at 25, vesicular I reacted with 2-(2-chloroethyl Ph sulfide), a simulant for the chem. warfare agent mustard [bis(2-chloroethyl) sulfide], to give 5-[S-[(2-phenylthio)ethyl]O,O'-didodecylphosphorodithioate] (II), involving capture of reactive intermediate cation 1-phenylthiocyclopropane by the anion of I. This reaction was accompanied by the pptn. of II, which resulted in wounding/destruction of the vesicles and the release of dye 5-carboxyfluorescein (from giant vesicles). The combination of the conversion and dye release suggests the potential of vesicular systems for simultaneous decontamination and signaling of chem. agents. 2-(2-Chloroethyl Ph sulfide) hydrolyzed to give only 2-(phenylthio)ethanol in the pH 9.0 buffer at 25.

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Two-generation reproduction study of lewisite in rats. Sasser, L. B.; Cushing, J. A.; Lindenmeier, C. W.; Mellick, P. W.; Dacre, J. C. Battelle, Richland, WA, USA. Journal of Applied Toxicology (1999), 19(4), 229-235. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 131:253491 AN 1999:485887 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Lewisite, a potent toxic vesicant and chem. warfare agent, is used in a no. of research labs., is stored in large quantities at depot sites throughout the USA and is occasionally transported to distant sites. Thus, the potential for environmental or occupational exposure exists where lewisite is present. A 42-wk two-generation study was conducted to det. the reproductive consequences of lewisite in parental male and female rats and their offspring. Rats were administered lewisite in sesame oil (0, 0.10, 0.25 or 0.60 mg kg-1 day-1 for 5 days a week) via intragastric intubation before mating, during mating and after mating until the birth of their offspring. The dams continued to receive lewisite during lactation. At weaning, male and female offspring of each group were selected to continue the study, receiving lewisite during adolescence, mating and throughout gestation and lactation. Lewisite had no adverse effect on reprodn. performance, fertility or reproductive organ wts. of male or female rats through two consecutive generations. No adverse effects to offspring were attributed to lewisite exposure. Minor changes in growth were the only maternal effects obsd. Lewisite exposure of parental rats caused no gross or microscopic lesion in testes, epididymis, prostate, seminal vesicles, ovaries, uterus or vagina. The no-observable-effect level (NOEL) for the reproductive effects of Lewisite would be >0.60 mg kg-1 day-1.

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Chemistry and toxicology of sulfur mustard-a review. Malhotra, R. C.; Ganesan, K.; Sugendran, K.; Swamy, R. V. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1999), 49(2), 97-116. CODEN: DSJOAA ISSN: 0011-748X. Journal; General Review written in English. CAN 131:112423 AN 1999:324517 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review and discussion with 124 refs. Bis(2-chloroethyl) sulfide commonly known as sulfur mustard (SM) is highly reactive bifunctional compd., documented as antimitotic, mutagenic, carcinogenic, teratogenic and cytotoxic agent. It is a powerful vesicant and has been employed as a chem. warfare agent. Skin, eyes and respiratory tract are the principal target organs and the DNA is the most important mol. target of SM toxicity. There is no specific antidote for SM injury. Treatment to SM toxicity is symptomatic.

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Surrogate burns in deactivation furnace system. Shah, Jay K. Science Applications International, Tooele, UT, USA. Journal of Hazardous Materials (1999), 66(3), 279-290. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 131:35263 AN 1999:308797 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The deactivation furnace system at the Deseret Chem. Depot in Utah is designed for processing explosive components from munitions contg. nerve and mustard agents. The Utah Division of Solid and Hazardous Waste (UDSHW) required that trial burns be conducted using surrogate chems. prior to introducing chem. agents into the system. Three surrogate runs of the selected surrogate chems. monochlorobenzene and hexachloroethane based on the criteria established by the UDSHW were conducted. The gaseous emissions and liq. and solid effluents were sampled and analyzed using approved EPA methods. The trial burns demonstrated the desirable destruction and removal efficiency for the selected surrogate chems. The pollution abatement system demonstrated the desired scrubbing efficiency for acid gases generated during incineration of chlorinated surrogate chems. The particulate removal efficiency during the trial burns was also considerably higher than required by regulations. After comprehensive survey of the performance of the deactivation furnace system during the surrogate trial burns, UDSHW approved introduction of GB nerve agent into the system to prep. it for agent trial burns.

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Reactions of VX, GD, and HD with Nanosize MgO. Wagner, George W.; Bartram, Philip W.; Koper, Olga; Klabunde, Kenneth J. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Journal of Physical Chemistry B (1999), 103(16), 3225-3228. CODEN: JPCBFK ISSN: 1089-5647. Journal written in English. CAN 130:337750 AN 1999:218187 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The room-temp. reactions of the chem. warfare agents VX (O-Et S-2-(diisopropylamino)ethyl methylphosphonothioate), GD (3,3-dimethyl-2-Bu methylphosphonofluoridate, or Soman), and HD (2,2'-dichloroethyl sulfide, or mustard) with nanosize MgO have been studied using solid-state MAS NMR. All three agents hydrolyze on the surface of the very reactive MgO nanoparticles. VX yields Et methylphosphonic acid (EMPA) and methylphosphonic acid (MPA), but no toxic S-(2-diisopropylamino)ethyl methylphosphonothioate (EA-2192). GD forms both GD-acid and MPA. For HD, in addn. to hydrolysis to thiodiglycol, about 50% elimination to divinyl sulfide occurs. The reaction kinetics for all three agents are characterized by a fast initial reaction followed by gradual slowing to a steady-state reaction with first-order behavior. The fast reaction is consistent with liq. spreading through the porous nanoparticle aggregates. The steady-state reaction is identified as a gas-phase reaction, mediated by evapn., once the liq. achieves its vol. in the smallest available pores.

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Cleavage of VX Simulants by Micellar Iodoso- and Iodoxybenzoate. Moss, Robert A.; Morales-Rojas, Hugo; Zhang, Hongmei; Park, Byeong-Deog. Department of Chemistry, Rutgers The State University of New Jersey, New Brunswick, NJ, USA. Langmuir (1999), 15(8), 2738-2744. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:328660 AN 1999:197621 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

O,S-Di-Et phenylphosphonothioate and S-Ph and S-Et diphenylthiophosphinate were efficiently cleaved by 3-fold excess o-iodosobenzoate (IBA) in aq. micellar cetyltrimethylammonium chloride solns. at pH 9.5. The max. obsd. rate consts. (monitored by HPLC aliquot procedures) were 1.09  10-3 s-1 for O,S-Di-Et phenylphosphonothioate and 6.0  10-3 s-1 for S-Et diphenylthiophosphinate with 0.06 M IBA at 25. S-Ph diphenylthiophosphinate cleaved too rapidly to follow by the aliquot method. With equimolar quantities of O,S-Di-Et phenylphosphonothioate and IBA, cleavage was slower and incomplete because of the redn. of the IBA to iodobenzoate by the EtSH liberated in the cleavage step. Mixts. of IBA and o-iodoxybenzoate (IBX) efficiently cleaved O,S-Di-Et phenylphosphonothioate, even though IBX was not reactive toward O,S-Di-Et phenylphosphonothioate, because the IBX competitively oxidized the EtSH, mitigating its reaction with IBA, while simultaneously affording addnl. IBA as the IBX was reduced. Studies of IBA and IBX redox reactions with EtSH are also included.

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Kinetic model for the decomposition of DMMP in a hydrogen/oxygen flame. Werner, James H.; Cool, Terrill A. School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA. Combustion and Flame (1999), 117(1/2), 78-98. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 130:112199 AN 1999:101405 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A kinetic model of the combustion chem. of a hydrogen/oxygen base flame, doped with di-Me methylphosphonate (DMMP), a useful simulant for chem. warfare agents (CWAs), has been developed to assist in the controlled thermal destruction of CWA stockpiles. Laser-ionization mass spectrometry is employed to record concn. profiles of radical intermediates in a low-pressure premixed laminar flame. These measurements, combined with ab initio ests. of thermochem. properties of organophosphorus compds., lead to a kinetic model incorporating several key reaction intermediates, which include Me metaphosphate CH3OPO2, Me dioxophosphorane CH3PO2, and monomethyl methylphosphonate PO(OH)(CH3)(OCH3).

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Deactivation of Mustard and Nerve Agent Models via Low-Temperature Microemulsions. Menger, Fredric M.; Rourk, Michael J. Department of Chemistry, Emory University, Atlanta, GA, USA. Langmuir (1999), 15(2), 309-313. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:164143 AN 1998:796211 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

New low-temp. oil-in-water (O/W) type microemulsions that resist freezing and phase sepn. at -18 have been developed. These systems were shown to simultaneously destroy, via oxidative and hydrolytic mechanisms, simulants of three chem. warfare agents. Reactions, monitored at 25 by gradient elution high-performance liq. chromatog., took place instantly or over many minutes, depending upon the particular simulant. Neglecting reaction products, the low-temp. microemulsions contained 11 components: propylene glycol, water, base, oxidant/nucleophile, surfactant, cosurfactant, oil, stabilizer, two nerve agent simulants, and a mustard simulant. Only by virtue of self-aggregation does this extraordinarily complex chem. system adopt a useful mol. organization and, in this limited sense, the microemulsion chem. resembles what happens in a living cell. Substantial practical issues remain: rates for a recalcitrant VX simulant should be increased and overoxidn. of the mustard simulant to a sulfone retarded. Nonetheless, the new system demonstrates once again the potential of microemulsions in carrying out useful org. reactions at realistic substrate concns. in aq. solvents.

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Treatment for sulfur mustard poisoning - a review. Sugendran, K.; Kumar, Pravin; Vijayaraghavan, R. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1998), 48(2), 155-162. CODEN: DSJOAA ISSN: 0011-748X. Journal; General Review written in English. CAN 130:164031 AN 1998:781689 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review and discussion with 39 refs. Sulfur mustard (SM) is a chem. warfare agent of historical and current interest. It is a well known blistering agent or vesicant. SM was extensively used in world war I as a chem. weapon and has been stockpiled by several countries since that time. SM serves as an ideal war gas and is favored militarily for its ability to incapacitate rather than to kill. Its use resulted in large nos. of casualties requiring prolonged and intensive medical care. Despite Geneva Protocol of 1925, which categorically banned the prodn., stockpiling and use of chem. weapons in wars, SM has been used in several wars, including the Iran-Iraq war during the 1980s, which renewed interest in it. Though, the chem. weapons convention was signed by more than 160 countries in 1993 and was subsequently ratified by several countries, the threat from this agent persists due to its clandestine usage during war and also by terrorist groups. There is no effective and specific antidote for local and systemic toxicity of SM despite scientific research for more than 75 yr. Many compds. were tested as antidotes for SM, but very few of them have been shown to provide some protection. The present review is aimed at evaluating the treatment regime and other clin. measures used to treat SM victims and the various drugs and chems. screened as antidotes for SM poisoning in exptl. animals.

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Evaluation of neutralized chemical agent identification sets (CAIS) for skin injury with an overview of the vesicant potential of agent degradation products. Olajos, E. J.; Olson, C. T.; Salem, H.; Singer, A. W.; Hayes, T. L.; Menton, R. G.; Miller, T. L.; Rosso, T.; MacIver, B. Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1998), 18(6), 409-420. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 130:106238 AN 1998:750883 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Vesication and skin irritation studies were conducted in hairless guinea-pigs to det. the vesicant and skin irritation potential of chem.-neutralized Chem. Agent Identification Sets (CAIS). The CAIS are training items that contain chem. warfare-related material-sulfur mustard (HD), nitrogen mustard (HN) or lewisite (L)-and were declared obsolete in 1971. Animals were dosed topically with "test article"-neat HD, 10% agent/chloroform solns. or product solns. (waste-streams) from neutralized CAIS-and evaluated for skin-damaging effects (gross and microscopic). Product solns. from the chem. neutralization of neat sulfur mustard resulted in microvesicle formation. All agent-dosed (HD or agent/chloroform solns.) sites manifested microblisters as well as other histopathol. lesions of the skin. Waste-streams from the neutralization of agent (agent/chloroform or agent/charcoal) were devoid of vesicant activity. Cutaneous effects (erythema and edema) were consistent with the skin-injurious activity assocd. with the neutralizing reagent 1,3-dichloro-5,5-dimethylhydantoin (DCDMH). Chem. neutralization of CAIS was effective in eliminating/reducing the vesicant property of CAIS contg. agent in chloroform or agent on charcoal but was inefficient in reducing the vesicant potential of CAIS contg. neat sulfur mustard.

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Degradation and fate of mustard in soil as determined by 13C MAS NMR. Wagner, George W.; MacIver, Brian K. Geo-Centers Inc., Aberdeen Proving Ground, MD, USA. Langmuir (1998), 14(24), 6930-6934. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 130:91384 AN 1998:713429 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The environmental fate of chem. warfare agents is a current concern, and the notorious persistency of mustard in soil is well-known. The current study utilizes 13C MAS NMR as an in situ method to study the behavior of mustard, and the common simulants 2-chloroethyl Me sulfide (CEMS) and 2-chloroethyl Ph sulfide (CEPS), in a sandy loam soil. Spreading of these water-insol. liqs. and surface sorption on the dry soil particles is observable, as is the recoalescence of liq. droplets and/or hydrolysis in the presence of added water. The relative hydrolysis rates are in agreement with those obsd. in soln. CEMS, possessing the shortest aq. half-life, hydrolyzes without droplet reformation. But mustard and CEPS, possessing much longer aq. half-lives, do not substantially hydrolyze prior to droplet reformation. For mustard, this behavior is crucial to its longevity in soil. Hydrolysis of CEMS and CEPS in the sandy loam soil yields predominately their corresponding alcs., with some ether formation for the latter. Mustard hydrolysis in the sandy loam soil results in the nearly exclusive formation of the branched sulfonium ion HOCH2CH2SCH2CH2S+(CH2CH2OH)2 (CH-TG). A simple model based on droplet size is presented to explain the persistency of mustard in soil.

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Old arsenical munitions: methods for destruction and site cleanup. Beletskaya; Bilger; Boronin; Bunnett; Costantino; Cullen; Dominas; Goessler; Haiduc; Maeda; Martens. Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 177-183. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42626 AN 1998:702909 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 11 refs. concerning methods to destroy and clean-up sites polluted by old arsenical munitions is given. Topics discussed include: spilled arsenical agents (natural chem. transformations in-situ, biotransformation, decontamination of soil contg. arsenical agents, removing polluted soil for treatment elsewhere); destruction of arsenical agents in munition containers or storage tanks (incorporation into concrete, incineration, reactions with alkalies, Na cleavage, hydrogenolysis, novel methods from Russia, oxidn. in water solns., oxidn. under UV irradn., Ag2+ oxidn., other technologies, biodegrdn); and need for research.

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Old "mustard" or yperite munitions: methods for destruction and container detoxification. Koch, E.; Koch, M.; Leslie; Mikolajczyk; Modena; Mulbry; Petrosyan; Sokolowski; Yang. Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 175-176. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42704 AN 1998:702908 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Problems assocd. with disposal of mustard chem. warfare agent, particularly the presence of materials other than the pure chem. compd., bis(2-chloroethyl)sulfide, greatly affects the suitability of processes which may be proposed for their destruction. Thus, destruction of mustard involved the conversion of a multitude of chem. species into material suitable for ultimate disposal; overall destruction also requires the material be presented in the correct form to the reaction stage of the process. Currently, only high temp. oxidn., i.e., incineration, is demonstrated bot be suitable for large-scale destruction of all materials collectively referred to as mustard. For a no. of reasons and public opposition, incineration may not be appropriate or acceptable for destruction of mustard at some locations. Technologies which for one reason or another were not pursued or were disregarded should be reconsidered in light of the wide range of problems that exist for destruction of mustard. Research into clean-up of contaminated sites is also necessary, including bioremediation of soil and chem. transformations in soil.

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Breakdown of sulfur "mustard" by phase transfer catalyzed HCl elimination, A potential destruction method for "mustard" stocks. Koch, Ernst - Christian. ABC- und Selbstschutzschule, Sonthofen, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 169-174. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42625 AN 1998:702907 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 56 refs. concerning sulfur mustard breakdown by phase transfer-catalyzed HCl elimination is given. Topics discussed include: mustard destruction; problem; process results and discussion; summary; instrumentation; and exptl.

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Reductive decomposition of deposits in old "mustard" munitions. Bunnett, Joseph F. University of California, Santa Cruz, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 163-164. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42703 AN 1998:702905 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The nature of gelled or solid deposits in decades-old mustard tanks or munitions is uncertain. Some possibilities which may occur alone or in combination include: polysulfonium salts; poly(ethylenesulfide); elemental S; di- or oligo-sulfide polymers; and Fe compds. from container corrosion. All these structural types are vulnerable to attack by strong reducing agents: Na in liq. NH3; electrochem. cleaving; S reaction with Na; Fe salt redn. by Na; and alkyl halide cleavage by Na. In the lab., conducting such reactions in liq. NH3 is attractive because solns. of Na in NH3 are stable for hours or days. Thus, factory-type installations using Na in liq. NH3 to clean out old mustard munitions with gelled or solid deposits should be feasible. After munitions have been opened and drained of liq. mustard, liq. NH3 could be added followed by pieces of Na metal to react with and destroy the deposits. Munitions so treated would be safe to ship to a furnace to burn out remaining traces. For field situations, a promising alternative is using Na in ethanol; Na reacts with ethanol to release H gas. Addnl. research is needed to confirm that compds. modeling the various suggested structures for gelled or solid mustard are reactive with Na in ethanol as expected.

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Electrochemical and biological approach to the destruction of Lewisite and "Mustard". Boronin, Alexander M.; Sakharovski, Valentin G.; Starovoitov, Ivan I.; Kashparov, Konstantin I.; Shvetsov, Valery N.; Morozova, Ksenija M.; Nechaev, Igor A.; Tugoshov, Vladimir I.; Kuzmin, Nikolai P.; Kochergin, Alexander I. Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 159-162. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42702 AN 1998:702904 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ecol. benign destruction of lewisite and mustard was achieved by electrochem. pretreatment of their neutralization products followed by biol. oxidn. of the waste stream. The process, reaction products, and results are discussed.

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Destruction of Adamsite by sodium. Sokolowski, M.; Bilger, E. Military Institute of Chemistry and Radiometry, Warsaw, Pol. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 157-158. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42701 AN 1998:702903 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sodium destroys chem. weapons, such as adamsite in a liq., dissolved, or gaseous state, with a special form of metallic, high surface Na, either on supports or as a dispersion in oil to yield inorg. Na salts and small org. mols. with little or no toxicity. Adamsite is destroyed by reacting with Na at low and even ambient temps. within a short time. Most of the originally org.-bonded As is transformed into inorg. As (ionic) and therefore can be pptd. as an insol. sulfide. After completing adamsite decompn., water contg. sodium sulfide is added in a closed compartment to initiate hydrolysis of org. Na compds. and ppt. As2S3.

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A method for mutual disposal of old chemical weapons. Chimishkyan, Alexander L. D. Mendeleev University of Chemical Technology, Moscow, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 155-156. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42700 AN 1998:702902 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

It is known that HCl destroys adamsite with formation of diphenylamine and AsCl3, and that the reaction of diphenylamine with another toxic agent, phosgene, is a method to produce acridone-9. These two reactions were used for the mutual disposal of adamsite and phosgene. Preliminary results showed the best results are obtained when phosgene is passed through an adamsite/paraffin melt. At the high temp. of the process (190-200), AsCl3 vapors are removed from the reaction mass where acridone-9 accumulates. It was also obsd. that tetraphenylurea is present in the reaction mass. This process guarantees a high yield of AsCl3.

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HPLC-ICP-MS methods for the determination of inorganic and organic arsenic compound. Goessler, W.; Kuehnelt, D.; Irgolic, K. J. Institute for Analytical Chemistry, Karl-Frazens-Universitat, Graz, Austria. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 151-154. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:62116 AN 1998:702901 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To improve the detection limits, a hydraulic high-pressure nebulizer was substituted for the normal pneumatic nebulizer. Chromatog. conditions for the sepn. of inorg. and org. arsenic compds. are identified. Characteristic chromatograms are presented. The combination of the hydraulic high-pressure nebulizer with the inductively coupled plasma mass spectrometer enables the sepn. and detection of arsenic at the sub ng/mL level. These methods can certainly be used to identify and quantify arsenic compds. in soil samples suspected of contamination with arsenic-contg. chem. warfare agents.

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Practical actions of Russia on preparations for destruction of stockpiled Lewisite and "Mustard". Petrov, S. V.; Kholstov, V. I.; Zoubrilin, V. P.; Zavialova, N. V. Ministry Of Defence Of Russian Federation, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 79-90. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 130:42697 AN 1998:702894 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To meet its international obligations while pursuing national policy, Russia has given priority to destroying its chem. warfare agent stockpiles as a major national objective. A mobile chem. warfare agent destruction mobile complex was constructed. It was necessary to first destroy stockpiled mustard-lewisite mixts. stored in high tonnage containers. The next priority is design and construction of a facility for organophosphorus agent destruction. This will be conducted simultaneously with work on blister agent destruction. This required site selection and submission to proper authorities and to the public for approval. Topics discussed include: Russian chem. weapons stockpiles; technol. aspects of lewisite and mustard destruction (lewisite stockpile destruction technologies [S treatment, lewisite interaction with ethylene glycol monomethacrylate ester and its subsequent polymn., chlorination, alk. hydrolysis, alcoholysis, high temp. oxidn., hydrogenolysis, NH3 redn.], mustard stockpile destruction technologies, mustard-lewisite mixts. destruction); and provisions for ecol. safe destruction of stockpiled lewisite and mustard.

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The problem of old chemical weapons which contain "mustard gas" or organoarsenic compounds: an overview. Manley, Ron G. Chemical Demilitarisation Branch, Provisional Technical Secretariat of the Preparatory Commission for the Organisation for the Prohibition of Chemical Weapons, Neth. NATO ASI Series, Series 1: Disarmament Technologies (1998), 19(Arsenic and Old Mustard: Chemical Problems in the Destruction of Old Arsenical and Mustard Munitions), 1-16. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 130:42622 AN 1998:702891 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 26 refs. of problems related to old and/or abandoned chem. weapons and the practicalities assocd. with their recovery and safe disposal. Emphasis is placed on weapons contg. either thickened or polymd. mustard gas and/or org. arsenicals, as these pose some of the most difficult disposal problems.

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Cardiorespiratory effects of O-isobutyl S-[2-(diethylamino)-ethyl] methylphosphonothioate - a structural isomer of VX. Chang, F.-C. T.; Gouty, S. C.; Eder, L. C.; Hoffman, B. E.; Maxwell, D. M.; Brecht, K. M. US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1998), 18(5), 337-347. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 130:34271 AN 1998:676630 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

O-Iso-Bu S-[2-(diethylamino)ethyl]methylphosphonothioate (VR) is a structural isomer of a more well-known chem. warfare agent, O-Et S-[2-(diisopropylamino)ethyl]methylphosphonothioate (code designation VX). In this study, cardiorespiratory and central nervous system (CNS) effects of VR (2LD50 or 22.6 g kg-1; s.c.) were evaluated in urethane-anesthetized (Group 1) and unanesthetized (Group 2) guinea pigs instrumented for concurrent recordings of electrocorticogram (ECoG) and a variety of cardiorespiratory activities. The first sign of intoxication was a state of progressive bradycardia, vascular hypotension and arrhythmia (Group 1, .apprx. 13 min post-VR; Group 2, .apprx.6 min post-VR). Bradypnea, excessive salivation and compensatory changes in blood pressure typically did not emerge until 3-5 min prior to apnea (Group 1, .apprx.28 min post-VR; Group 2, .apprx.15 min post-VR). An idioventricular rhythm, which signaled a failing myocardium, appeared at the same time or shortly after the development of a bradypneic profile. Another notable toxicity component of VR, based on arterial pH, pO2/pCO2 and bicarbonate (HCO3-) level data, was a state of combined hypercapnia, acidemia and hypoxemia during the development of bradypnea. Taken together, findings from this study indicated that changes in medullary respiratory unit activity and ECoG data displayed little, if any, notable signs of CNS perturbation prior to the terminal stage (.apprx.1 min prior to respiratory failure). Thus, in addn. to displaying a greater sensitivity to perturbation by VR, the peripheral cardiorespiratory system components also appeared to play a more important role in pptg. a progressively dysfunctional cardiorespiratory status that ultimately led to collapse of central respiratory mechanisms and death.

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Gas-phase pyrolysis of diisopropyl methylphosphonate. Zegers, E. J. P.; Fisher, E. M. Sibley Sch. Mechanical and Aerospace Eng., Cornell Univ., Ithaca, NY, USA. Combustion and Flame (1998), 115(1/2), 230-240. CODEN: CBFMAO ISSN: 0010-2180. Journal written in English. CAN 129:58161 AN 1998:377527 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gas-phase pyrolysis studies of diisopropyl methylphosphonate (DIMP) in nitrogen have been conducted to gain insight into the decompn. behavior of organophosphorus chem. warfare nerve agents. Expts. were conducted in a quartz-lined atm. flow reactor between 700 and 800 K, at residence times ranging from 15 to 90 ms. Propylene, isopropanol, iso-Pr methylphosphonate (IMP), and methylphosphonic acid (MPA) were identified as decompn. products of DIMP. FTIR spectrometry was used to quantify parent, propylene, and isopropanol mole fractions in the reactor. The proposed pyrolysis mechanism for DIMP comprises two stages. The first corresponds to the unimol. decompn. of the parent into IMP and propylene. The second involves two competing pathways for the unimol. decompn. of IMP, one leading to isopropanol and the very reactive Me dioxophosphorane; the other to propylene once again and MPA. In the range of temps. studied, an isopropanol to propylene mole fraction ratio close to 0.25 suggests a branching ratio of 1.5 between these two pathways in favor of propylene prodn. The Arrhenius expression for the unimol. decompn. of DIMP was found to be: k[s-1]=10(12.01.5)[s-1] exp(-36.74.9[kcal.mole-1]/(RT)). Pyrolysis expts. with iso-Pr and t-Bu acetates, which have well-known decompn. rates, were performed to illustrate the ability of the app. to produce valid chem. kinetic data. An investigation of the effects of surface to vol. ratio on the DIMP decompn. process shows that wall reactions are significant in a 4-mm i.d. quartz tube, but less important in an 8-mm i.d. tube. Their effects are expected to be small in the 45-mm i.d. reactor.

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GC/MS screening of alkyl methylphosphonofluoridates and alkyl methylphosphonic acids. Rohrbaugh, Dennis K.; Sarver, Emory W. U.S. Army Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 313-347. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:18255 AN 1997:713947 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gas chromatog.-mass spectrometry (GC-MS) and GC-MS-MS techniques, including electron impact, CH4 chem. ionization, and NH3 chem. ionization, were examd. for their use as potential screening techniques to monitor and detect Schedule 1A1 C1-10-alkyl and cycloalkyl methylphosphonofluoridates and the corresponding Schedule 2 hydrolysis products. These compds. [the methylphosphonofluoridates, of general formula MeP(:O)F(OR), and MeP(:O)OH(OR), R = Et, iso-Pr, iso-Bu, pinacolyl, and cyclohexyl] are, or are derived from, common chem. warfare agents. The base peak for all methylphosphonofluoridates in electron-impact mass spectrometry was at m/e 99. Because of low volatility, the methylphosphonic acids were not amenable to GC anal. However, electron impact mass spectra of their trimethylsilyl (TMS) derivs. gave a base peak at m/e 153 and a dominant peak (10-50% of base peak) at m/e 169 for all compds. Chem. ionization mass spectrometry with CH4 and NH3 can not only be used to also screen samples, but it can give information on mol. wt. of specific compds.

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Possibilities of incorporation of the CO2 DIAL detector into the system of atmospheric quality monitoring associated with storing and destruction of chemical weapons. Kadlcak, J.; Dubina, P.; Safar, B. Military Technical Institute of Protection Brno, Brno, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 255-263. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350239 AN 1997:713942 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The CO2 DIAL system is capable of detecting GB and other chem. warfare agents over a distance of 600 m, theor. up to 3.5 km. In addn., the CO2 DIAL system is able to follow the changes in the concn. of monitored species in a cloud. The detection limit with which the concn. of these compds. could be measured is limited by the min. changes in the differential absorption LIDAR returns that could be distinguished from background fluctuations.

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A data analysis routine to protect confidential information during GC-MS analysis. Mcguire, Raymond R.; Martin, Walter H. Arms Control and Treaty Verification Program Lawrence Livermore National laboratory, Livermore, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 229-240. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:9885 AN 1997:713940 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A shell program, MASK was added to the std. GC-MS data anal. code M CODE to protect confidentiality of information not relevant to the Chem. Weapons Convention. This program was demonstrated to work well where high total ion counts are available. A subroutine for blind background subtraction needs to be added for cases where the peak is only slightly above baseline.

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The application of LC/ES-MS in the OPCW/PTS inter-laboratory comparison test. Peng, Lixin; Xu, Danian. Research Institute of Chemical Defence, Beijing, Peop. Rep. China. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 225-228. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350237 AN 1997:713939 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Structural identification of several Chem. Warfare Convention-related compds., (R)P(O)(OH)2, (CH3)p(O)(OH)(OR), bis(2-chloroethyl)ethylamine, o-cyclopentyl-S-2-(diethylamino)ethylmethylphosphonothiolate, N,N-diethylaminoethanol, and ethyldiethanolamine, using HPLC/emission spectroscopy-mass spectrometry is presented, and the main fragmentation pattern under ES-MS is discussed. LC/ES-MS can det. high wt. mol. and structural anal. of polar, low mol. wt. analytes, esp. phosphonic acid.

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Air monitoring equipment for CW destruction facilities with special emphasis on OCW destruction. Starrock, Volker; Doering, Hans Ruediger. German Armed Forces NBC Defence Establishment, Munster, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 157-180. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350386 AN 1997:713936 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A discussion is given on the air monitoring system in chem. warfare agent destruction site. It includes monitoring system, destruction activities, and anal.

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GCQ GC/MS system: preliminary experiences. Cermak, J. CETA Analytical Department, Research Institute for Organic Syntheses, Pardubice - Rybitvi, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 133-146. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350634 AN 1997:713934 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A discussion is given on the GC/MS system in relation to destruction of chem. warfare agents.

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GC/MS investigation of Ethyl S-2-diisopropyl aminoethyl methylphosphonothiolate (VX) age decomposition products. Sliwakowski, M. Military Institute of Chemistry and Radiometry, Warsaw, Pol. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 127-132. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:39042 AN 1997:713933 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Sample of VX stored for a long time in glass container was investigated using GC/MS system. A variety of age decompn. products including O-alkyl and N,N-diisopropylamino- substituted thiophosphonic esters and acids as well as phosphonic anhydrides were identified. Diazomethane methylation was used to obtain derivs. convenient to GC process. Retention parameters and EI-MS spectra were obtained and presented.

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Chemical ionization and electron impact mass spectrometry of some methylphosphonothiolates. Podborsky, V.; Stein, V. Military Technical Institute of Protection, Brno, Czech Rep. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 109-125. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 128:3728 AN 1997:713932 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Mass spectrometric data of 18 organophosphorus compds. from the family of V-agents were studied. MS spectra of S-2-dimethyl-, S-2-diethyl-, S-2-dipropyl-, S-2-diisopropyl- and S-2-dibutylaminoethyl O-alkyl methylphosphonothiolates were measured in EI and CI modes. MS spectra were completed with some toxicol. data of these organophosphorus compds.

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Application of some modern sample introduction techniques and Poraplot Q GC column in the analysis of volatile toxic compounds. Bardarov, V.; Tashkov, V. Military Medical Academy, Sofia, Bulg. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 77-97. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350235 AN 1997:713929 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. of toxic substances is difficult due to the complexity of the matrixes and usual requirements of multi-component anal. leading to application of chromatog. sepn. The greatest part of chem. warfare agents, their precursors, and degrdn. products demonstrate significant vapor pressure and cause measurable concns. in the gaseous environment at ambient or slightly increased temps. This results in problems for sampling and sample prepn., but favorable distribution of analytes and matrix components among the matrix or suitable sorbent and the gaseous environment may occur and can be used in some techniques to combine sampling, sample prepn., and sample introduction when analyzed using gas chromatog. These techniques, headspace, thermodesorption, and gas extn., realized using different instrument variants in combination with gas chromatog. sepn., are discussed.

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On-site sample work-up procedures to isolate chemical warfare related compounds using solid phase extraction and solid phase microextraction technology. Alcaraz, A.; Hulsey, S. S.; Whipple, R. E.; Andresen, B. D. Lawrence Livermore National Laboratory, Forensic Science Center, Livermore, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 65-76. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350879 AN 1997:713928 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

To rapidly prep. and accurately analyze suspect samples for on-site investigations of chem. warfare agents, new methods and field portable equipment, including collection, prepn., and anal. of suspect samples, were required. Using solid phase extn., sample prepn. time was greatly reduced and cumbersome lab. equipment was eliminated. Three different portable modules to achieve on-site field anal. capability were developed. The first consisted of pre-cleaned, sealed sample collection equipment capable of obtaining any type of sample. The second module allowed for complete chem. work-up of collected samples to prep. them for instrumental anal. The third module contained anal. instrumentation necessary for chem. identification, including gas chromatog.-flame photometric detection and gas chromatog.-mass spectrometry for pos. compd. identification. Two field exercises were conducted to provide information on detection limits of on-site anal. approach for soil, water, and swipe samples. Both exercises showed the on-site anal. equipment can be easily deployed. All chem. warfare-related compds. were readily identified using the solid phase extn. technol. and portable anal. equipment. Results were later confirmed by analysts in inhouse labs.

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Super Toxic Analytical Glovebox System (STAGS). Henry, Charles E.; Heyl, Monica; Reutter, Dennis; Diez, Hernan; Landy, Keith. U.S. ARMY, ERDEC, AMC Treaty Laboratory, AMSCB-ACL, APG-EA, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 59-63. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350413 AN 1997:713927 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The US Army was directed to dispose of the stockpile of unitary chem. weapons by Public Law 99-145 and subsequent amendments. This stockpile consists primarily of the agents, VX, HD, and GB, contained in a variety of munitions and bulk containers. To minimize the total risk to the public and the environment posed by chem. weapons storage and disposal, the National Research Council recommended the Army continue the current baseline incineration program while evaluating alternative technologies as replacements for the liq. incinerator used in agent destruction. To accomplish research necessary to det. the efficiency of neutralization, field grade chem. agents were characterized on-site in their natural environment. An on-site purity anal. for ton container survey at 3 storage sites was conducted. Super toxic anal. glovebox system (STAGS), an anal. equipment platformed within a regulated enclosure was designed to successfully perform super toxic work in the field. Development and initial testing of STAGS is discussed.

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Analytical control for destruction of chemical weapons. Requirements and organization. Myasoedov, B. F. V.I.Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, Russia. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 39-58. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:350412 AN 1997:713926 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An effectively operating anal. control system for chem. weapons destruction in Russia is discussed. The Russian chem. weapons stockpile identified for destruction includes V-gas, sarin, soman, mustard gas, lewisite, and mustard gas-lewisite mixts. amounting to 40,000 tons of chem. warfare agents. Key problems include safety provisions for humans and the environment regarding chem. weapons storage, transportation, and destruction; neutralization of detoxification products; use of solid wastes; and physicochem. parameters of chem. warfare prodn. testing; and disposal of chem. warfare agents and sites. To meet these requirements, an effective system of anal. control coupled with a computer-assisted information system capable of providing expert with high quality reliable data is essential. The operation and elements of this control system are discussed.

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Development of analytical technologies for the alternatives to incineration program. Reutter, Dennis J.; Sumpter, Kenneth; Vickers, Eugene; Simak, Richard; Henry, Charles; Hoffland, Lynn; Smith, Philip B.; Brickhouse, Mark. U.S. Army, ERDEC, AMC Treaty Laboratory, AMSCB-ACL, APG-EA, MD, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 27-38. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:336178 AN 1997:713925 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various aspects of the destruction of chem. weapons are discussed using VX as an example including the development of anal. technologies for the alternatives to incineration program .

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Project SWIFTSURE: destruction of chemical agents at Defense Research Establishment Suffield. Mcandless, John M.; Boulet, Camille A. Defence Research Establishment Suffield, Medicine Hat, AB, Can. NATO ASI Series, Series 1: Disarmament Technologies (1997), 13(Analytical Chemistry Associated with the Destruction of Chemical Weapons), 1-14. CODEN: NASTFP ISSN: 1383-715X. Journal; General Review written in English. CAN 127:350492 AN 1997:713923 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 11 refs., on the project location, waste inventory, operational concept, environmental monitoring, and destruction of chem. agents.

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Pyrethroid decrease in central nervous system from nerve agent pretreatment. Buchholz, Bruce A.; Pawley, Norma H.; Vogel, John S.; Mauthe, Robert J. Lawrence Livermore National Laboratory, Livermore, CA, USA. Journal of Applied Toxicology (1997), 17(4), 231-234. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 127:172426 AN 1997:560828 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors studied the effect of pyridostigmine bromide, a nerve agent prophylactic, on the central nervous system (CNS) uptake of [14C]permethrin, a pyrethroid insecticide, at scaled human-equiv. exposures in rats using accelerator mass spectrometry (AMS). AMS detects 14C at attomole sensitivities and dets. the tissue distribution of 14C-labeled compds. Pyridostigmine bromide in chow at 7.75 mg kg-1 per day lowered the CNS tissue levels of permethrin, dosed at 4.75 g kg-1, in the CNS of rats by 30%. These results are inconsistent with hypothesized synergy of such compds. as a precursor to "Gulf War syndrome".

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Sulchem process for treatment of chemical weapons-related wastes. Berkey, Edgar; Paff, Stephen W.; King, A. Bruce. Center for Hazardous Materials Research, University of Pittsburgh Applied Research Center, Pittsburgh, PA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 129-148. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:180466 AN 1997:545010 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The Sulchem process is a chem. treatment process that uses elemental S at elevated temps. in an O-free environment to clean up soil contaminated with org. and metallic waste. The process relies on the high reactivity of S and its ability to oxidize org. compds. rapidly and non-selectively at reaction conditions. Org. compds. react with the S to form an inert fine solid of C and S, as well as a variety of simple gases whose compn. varies with the waste material being treated. Byproduct gases may be scrubbed or treated to recover elemental S using an auxiliary process unit. Heavy metals contained in the soil react to form insol. sulfides that become immobilized. The process is potentially applicable to a variety of chem. weapons-related wastes, including soil contaminated with chem. agents, nerve agents, or energetics. The Sulchem process is operated as a 2-stage system at 300-350. Org. compds. that are not volatilized from the soil are completely destroyed in the 1st reactor, in which the insol. metallic sulfides are also formed. A 2nd stage S/vapor reactor is used to destroy orgs. desorbed from the soil reactor. A series of bench-scale and pilot-scale test have been conducted that support feasibility of the process. Projected remediation costs using the process are estd. at $105-$183/ton based on site size, reactor configuration, and processing rate.

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The application of the Silver II electrochemical oxidation process for the demilitarization of non-stockpile material. Batey, W.; Warren, N. AEA Technology, Caithness, UK. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 103-127. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:194862 AN 1997:545009 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The Silver II Process is a recognized alternative technol. to incineration for the demilitarization of chem. munitions. This paper describes an integrated electrochem. cutting method for the breakdown of munitions with the Silver II Process being used to demilitarize the recovered org. material and decontaminate the shell casing. The Silver II Process is a low temp. and pressure electrochem. oxidn. process which stops when the electrochem. cell current is stopped. The offgases comply with environmental discharge stds. All liq. wastes are stored on-site pending return to a central depot for regeneration. The liq. wastes from the regeneration plant are discharged at the central depot once they have been confirmed to be free of chem. agent. The proposed concept provides a mobile soln. for the demilitarization of recovered buried conventional and chem. weapons. The concept is applicable to the remediation of small and large formerly used defense sites.

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Chemical detoxification of chemical weapons applying sodium-technology. Bilger, Edgar. c/o Dr. Bilger Umweltconsulting GmbH, Freigericht, Germany. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 71-82. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:194861 AN 1997:545008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A cost-effective chem. method to destroy chem. weapons in a mobile unit using Na is described. Case studies for the destruction of Adamsite or mustard are highlighted. Using Na technol., the chem. can be controlled and analyses can be made at any stage of treatment since all substances are kept in closed compartments until the products are released after thorough final anal. Advantages of the Na technol. include: low temp.; chem. weapon mineralization; low investment cost; inexpensive reagents; no formation of dioxins or furans (vs. incineration); prodn. of solid or dissolved reaction products; no hazardous gases released; and mobile detoxification units.

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Cryofracture as a mobile demilitarization technology for non-stockpile chemical munitions. Spritzer, M. H.; Johnson, L. D. General Atomics, San Diego, CA, USA. NATO ASI Series, Series 1: Disarmament Technologies (1997), 12(Mobile Alternative Demilitarization Technologies), 19-39. CODEN: NASTFP ISSN: 1383-715X. Journal written in English. CAN 127:180485 AN 1997:545005 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Cryofracture is a demilitarization process that has been under development for chem. agent munitions for over 12 yr. Cryofracture uses liq. N to pre-cool munitions prior to fracturing in a hydraulic press. Cryofracture exposes the chem. agents and explosives for subsequent destruction by other means such as thermal or chem. treatment. The cryofracture process is designed to demilitarize projectiles, cartridges, mortar rounds, mines and rockets. Over $60 million has been spent by the US Army to develop cryofracture for demilitarization of chem. agent munitions stored at stockpile sites in the US. Extensive tests have been performed with live explosives and simulant agents, and the test results verify all key aspects of the process. More recently, the cryofracture process has been applied to conventional munitions with the same good results. The process is also likely to find application for non-stockpile chem. munitions in the US and throughout the world. A description of the process and the results of extensive testing are presented, with particular emphasis on the adaptation of cryofracture to non-stockpile chem. munitions.

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Radial Heterogeneity of Impregnated Active Carbon Particles. Buczek, B.; Zietek, S.; Swiatkowski, A. University of Mining and Metallurgy, Krakow, Pol. Langmuir (1997), 13(5), 1342-1344. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 126:122909 AN 1997:126980 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Texture and sorptive properties of the active carbon, before and after impregnation with the soln. of Cr, Cu, and Ag salts, were investigated. Initial active carbon and the impregnated one were sep. subjected to abrasion in a spouted bed, thus obtaining core samples with different degrees of external layers removed. They were analyzed by means of densimetry, mercury porosimetry, and adsorption techniques. The pore vol. was detd. from measurements of true and real densities. Mercury porosimetry was used to est. vol. pores in the macropore range. Mesopore and micropore structures were detd. using benzene adsorption/desorption isotherms. Both the active carbon and impregnated active carbon showed radial changes in the micro-, meso-, and macropore structure. For impregnated active carbon samples the amt. of deposited material and sorption of ClCN were measured. The outer regions of particles were richer in active material whose distribution was analyzed. Samples with removed external layers exhibited substantially higher protective efficiency against cyanogen chloride.

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Comparative evaluation of benzodiazepines for control of soman-induced seizures. McDonough J H Jr; McMonagle J; Copeland T; Zoeffel D; Shih T M Pharmacology Division, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5400, USA Archives of toxicology (1999 Nov), 73(8-9), 473-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10650919 AN 2000114341 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

This study evaluated the ability of six benzodiazepines to stop seizures produced by exposure to the nerve agent soman. Guinea pigs, previously prepared with electrodes to record electroencephalographic (EEG) activity, were pretreated with pyridostigmine (0.026 mg/kg, i.m.) 30 min before challenge with soman (56 microg/kg, s.c.) and then treated 1 min after soman exposure with atropine (2.0 mg/kg, i.m.) and pralidoxime chloride (2-PAM Cl; 25 mg/kg, i.m.). All animals developed seizures following this treatment. Benzodiazepines (avizafone, clonazepam, diazepam, loprazolam, lorazepam, and midazolam) were given i.m. 5 or 40 min after seizure onset. All benzodiazepines were effective in stopping soman-induced seizures, but there were marked differences between drugs in the rapidity of seizure control. The 50% effective dose (ED50) values and latencies for anticonvulsant effect for a given benzodiazepine were the same at the two times of treatment delay. Midazolam was the most potent and rapidly acting compound at both treatment times. Since rapid seizure control minimizes the chance of brain damage, use of midazolam as an anticonvulsant may lead to improved clinical outcome in the treatment of nerve agent seizures.

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Sulphur mustard induced DNA damage in mice after dermal and inhalation exposure. Lakshmana Rao P V; Vijayaraghavan R; Bhaskar A S Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India. drde@gwr1.dot.net.in Toxicology (1999 Nov 29), 139(1-2), 39-51. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10614687 AN 2000080350 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Sulphur mustard (SM) is a chemical warfare agent of the blistering agent category for which there is still no effective therapy. SM, being a strong electrophile, readily reacts with a wide range of cellular macromolecules including DNA, RNA and protein. Since the main intoxication routes for SM are inhalation and dermal penetration, in the present study we have exposed female mice to different concentrations of SM by dermal and inhalation exposures and estimated the DNA damage in different organs viz., liver, lung, spleen and thymus. SM was applied at 38.7, 77.4, 154.7 mg/kg body weight, on the hair-clipped skin (dermal exposure) equivalent to 0.25, 0.5 and 1.0 of the LD50. Inhalation exposure was carried out at 10.6, 21.2 and 42.3 mg/m3 for 1 h duration equivalent to 0.25, 0.5 and 1.0 LC50. SM induced a dose-dependent DNA damage in all the organs except the lung in dermal exposure. Similarly the inhalation exposure resulted in dose- and time-dependent effect in all the organs including lung. By both routes of exposure liver was the most affected organ followed by spleen, thymus and lung in decreasing order. The quantitative data were corroborated by qualitative analysis of DNA on agarose gel electrophoresis. The genomic DNA analysis of the organs had revealed random nuclear DNA fragmentation resulting in a 'smear' typical of necrotic form of cell death. Since DNA damage is not reversible especially in liver, this can be used as a marker for SM exposure through either the dermal or inhalation route.

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Development of reactive topical skin protectants against sulfur mustard and nerve agents. Koper O; Lucas E; Klabunde K J Nantek, Inc., 1500 Hayes Drive, and Department of Chemistry, Kansas State University, Manhattan, KS 66502, USA Journal of applied toxicology : JAT (1999 Dec), 19 Suppl 1 S59-70. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10594903 AN 2000062800 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The potential for highly reactive nanoparticles (RNP) to absorb destructively, i.e. to neutralize highly toxic substances such as the warfare agents GA, GB, HD and VX, has been demonstrated in the laboratory. Reactive nanoparticles represent a new class of nanoscale particles of metals and metal oxides that differ from other nanoparticles in reactivity and crystalline morphology. The potential for incorporating RNP into a protective barrier skin cream also has been demonstrated. Preliminary studies indicate that RNP are physically and chemically compatible with a base cream provided by the Army Medical Research Office and, importantly, remain reactive with chemical agents while promising to be compatible with skin contact. Copyright 1999 John Wiley & Sons, Ltd.

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Efficacy of the topical skin protectant in advanced development. Liu D K; Wannemacher R W; Snider T H; Hayes T L US Army Medical Material Development Activity, 622 Neiman Street, Fort Detrick, MD 21702-5009, USA Journal of applied toxicology : JAT (1999 Dec), 19 Suppl 1 S40-5. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10594900 AN 2000062797 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A topical skin protectant (TSP) (ICD 2289) is being developed to protect service members from exposure to chemical warfare agents (CWA). The TSP is designed for use on the skin at the overgarment closures and other vulnerable areas to enhance protection. The TSP, which is in phase II clinical studies, is a cream containing two chemically inert substances: perfluoroalkylpolyether and polytetrafluoroethylene. Animal data showed that the TSP was effective against percutaneous penetration of a blister agent, sulfur mustard (HD), by reducing the size of skin lesions and against T-2 mycotoxin by preventing the development of erythema and edema. The insect repellent N,N-diethyl-m-toluamide (DEET) reduced the TSP protection against HD regardless of the order of application on rabbit skin prior to dosing of HD. The protection was sustained when DEET was removed with a dry gauze prior to TSP application. The TSP was also effective against percutaneous exposure of nerve agents-thickened (with 5% methyl methacrylamide) soman (TGD) and VX (O-ethyl-S-[2-(diisopropylamino)ethyl]methylphosphonothioate )-by reducing the mortality rate and protecting the red blood cell acetylcholinesterase activity. The TSP was effective against VX when DEET was applied prior to TSP application. Because human efficacy studies using CWA cannot be conducted, the efficacy will be demonstrated by the level of protection against poison ivy (urushiol) contact dermatitis in humans.

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Two-generation reproduction study of lewisite in rats. Sasser L B; Cushing J A; Lindenmeier C W; Mellick P W; Dacre J C Molecular Bioscience Department, Battelle, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1999 Jul-Aug), 19(4), 229-35. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10439336 AN 1999368191 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Lewisite, a potent toxic vesicant and chemical warfare agent, is used in a number of research laboratories, is stored in large quantities at depot sites throughout the USA and is occasionally transported to distant sites. Thus, the potential for environmental or occupational exposure exists where lewisite is present. A 42-week two-generation study was conducted to determine the reproductive consequences of lewisite in parental male and female rats and their offspring. Rats were administered lewisite in sesame oil (0, 0.10, 0.25 or 0.60 mg kg-1 day-1 for 5 days a week) via intragastic intubation before mating, during mating and after mating until the birth of their offspring. The dams continued to receive lewisite during lactation. At weaning, male and female offspring of each group were selected to continue the study, receiving lewisite during adolescence, mating and throughout gestation and lactation. Lewisite had no adverse effect on reproduction performance, fertility or reproductive organ weights of male or female rats through two consecutive generations. No adverse effects to offspring were attributed to lewisite exposure. Minor changes in growth were the only maternal effects observed. Lewisite exposure of parental rats caused no gross or microscopic lesion in testes, epididymis, prostate, seminal vesicles, ovaries, uterus or vagina. The no-observable-effect level (NOEL) for the reproductive effects of Lewisite would be > 0.60 mg kg-1 day-1.

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Effect of lowered temperature on the toxicity of sulphur mustard in vitro and in vivo. Sawyer T W; Risk D Therapy Group, Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada. thomas.sawyer@dres.dnd.ca Toxicology (1999 May 3), 134(1), 27-37. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10413186 AN 1999339531 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Primary cultures of chick embryo neurons were exposed to sulphur mustard (HD) and L-nitroarginine methyl ester (L-NAME) and then incubated at either 25 or 37 degrees C. Lowering the temperature of the cultures decreased the 24-h toxicity of HD, but did not increase the efficacy of L-NAME protection. However, the length of time post-HD treatment in which L-NAME was maximally effective in protecting against HD toxicity was dramatically enhanced, out to 12 h after HD exposure. In addition, the persistence of L-NAME protection of the cells against HD was significantly lengthened. Tests conducted in human skin keratinocytes also showed that lowering the incubation temperature of actively proliferating, just-confluent or post-confluent cultures significantly and persistently decreased the cytotoxicity of HD. The persistence of L-NAME protection was increased in non-proliferating cells. Finally, cooling of HD-vapour exposed sites on hairless guinea pigs for 4.5 h decreased the severity of the resultant lesions out to 72 h post-exposure.

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The interaction of sarin and soman with plasma proteins: the identification of a novel phosphonylation site. Black R M; Harrison J M; Read R W DERA, CBD Porton Down, Salisbury, Wilts, UK Archives of toxicology (1999 Mar), 73(2), 123-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10350193 AN 1999277696 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Incubation of both sarin and soman with human plasma has shown that binding occurs to a tyrosine residue. Similar binding occurs when sarin and soman are incubated with human serum albumin. This binding may provide an important biological marker, which retains full structural information concerning the identity of the agent, in cases of allegations of chemical warfare use.

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Acute soman poisoning in primates neither pretreated nor receiving immediate therapy: value of gacyclidine (GK-11) in delayed medical support. Lallement G; Clarencon D; Galonnier M; Baubichon D; Burckhart M F; Peoc'h M Unite de Neuropharmacologie, CRSSA-BP, La Tronche, France. 100437,201@compuserve.com Archives of toxicology (1999 Mar), 73(2), 115-22. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 10350192 AN 1999277695 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Organophosphorus (OP) nerve agents are still used as warfare and terrorism compounds. Classical delayed treatment of victims of organophosphate poisoning includes combined i.v. administration of a cholinesterase reactivator (an oxime), a muscarinic cholinergic receptor antagonist (atropine) and a benzodiazepine anticonvulsant (diazepam). The objective of this study was to evaluate, in a realistic setting, the therapeutic benefit of administration of GK-11 (gacyclidine), an antiglutamatergic compound, as a complement to the above therapy against organophosphate poisoning. Gacyclidine was injected (i.v.) in combination with atropine/diazepam/pralidoxime at man-equivalent doses after a 45- or 30-min latency period to intoxicated primates (2 LD50). The effects of gacyclidine on the animals' survival, electroencephalographic (EEG) activity, signs of toxicity, recovery after challenge and central nervous system histology were examined. The present data demonstrated that atropine/diazepam/pralidoxime alone or combined with gacyclidine did not prevent signs of soman toxicity when treatment was delayed 45 min after poisoning. Atropine/diazepam/pralidoxime also did not control seizures or prevent neuropathology in primates exhibiting severe signs of poisoning when treatment was commenced 30 min after intoxication. However, in this latter case, EEG recordings revealed that additional treatment with gacyclidine was able to stop soman-induced seizures and restore normal EEG activity. This drug also totally prevented the neuropathology observed 5 weeks after soman exposure in animals treated with atropine/diazepam/pralidoxime alone. Overall, in the case of severe OP-poisoning, gacyclidine represents a promising adjuvant therapy to the currently available polymedication to ensure optimal management of organophosphate poisoning in man. This drug is presently being evaluated in a human clinical trial for a different neuroprotective indication.
However, it should always be kept in mind that, in the case of severe OP-poisoning, medical intervention must be conducted as early as possible.

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Evaluation of neutralized chemical agent identification sets (CAIS) for skin injury with an overview of the vesicant potential of agent degradation products. Olajos E J; Olson C T; Salem H; Singer A W; Hayes T L; Menton R G; Miller T L; Rosso T; MacIver B Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD 21010, USA Journal of applied toxicology : JAT (1998 Nov-Dec), 18(6), 409-20. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9840748 AN 1999054483 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Vesication and skin irritation studies were conducted in hairless guinea-pigs to determine the vesicant and skin irritation potential of chemically-neutralized Chemical Agent Identification Sets (CAIS). The CAIS are training items that contain chemical warfare-related material--sulfur mustard (HD), nitrogen mustard (HN) or lewisite (L)--and were declared obsolete in 1971. Animals were dosed topically with 'test article'--neat HD, 10% agent/chloroform solutions or product solutions (waste-streams) from neutralized CAIS--and evaluated for skin-damaging effects (gross and microscopic). Product solutions from the chemical neutralization of neat sulfur mustard resulted in microvesicle formation. All agent-dosed (HD or agent/chloroform solutions) sites manifested microblisters as well as other histopathological lesions of the skin. Waste-streams from the neutralization of agent (agent/chloroform or agent/charcoal) were devoid of vesicant activity. Cutaneous effects (erythema and edema) were consistent with the skin-injurious activity associated with the neutralizing reagent 1,3-dichloro-5,5-dimethylhydantoin (DCDMH). Chemical neutralization of CAIS was effective in eliminating/reducing the vesicant property of CAIS containing agent in chloroform or agent on charcoal but was inefficient in reducing the vesicant potential of CAIS containing neat sulfur mustard.

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Inhibition, reactivation and aging kinetics of cyclohexylmethylphosphonofluoridate-inhibited human cholinesterases. Worek F; Eyer P; Szinicz L Institut fur Pharmakologie und Toxikologie, Sanitatsakademie der Bundeswehr, Garching, Germany Archives of toxicology (1998 Sep), 72(9), 580-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9806430 AN 1999021267 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (cyclosarin) is a highly toxic organophosphate, which was shown to be rather resistant to conventional oxime therapy. To give more insight into the inhibition, reactivation and aging kinetics, human acetyl-(AChE) and butyrylcholinesterase (BChE) were inhibited by cyclosarin (k2 of 7.4 and 3.8 x 10(8) M(-1) min(-1), respectively; pH 7.4, 37 degrees C) and reactivated with obidoxime, pralidoxime and three experimental oximes. The new oxime HLo 7 (1-[[[4-aminocarbonyl)-pyridinio]-methoxy]-methyl]-2,4-bis-[ (hydroxyimino)methyl] pyridinium dimethanesulphonate) was shown to be superior to the other oximes. At oxime concentrations anticipated to be relevant in humans, obidoxime and pralidoxime were extremely weak reactivators of AChE. Aging velocity of BChE was almost fourfold higher compared to AChE (ka of 0.32 h(-1) and 0.08 h(-1), respectively). A substantial spontaneous reactivation was observed with AChE. These results support previous in vivo findings that obidoxime and pralidoxime are insufficient antidotes in cyclosarin poisoning. By contrast, HLo 7 was shown to be an extremely potent reactivator of human AChE and BChE, which supports its position as a broad-spectrum oxime.

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Acute inhalation toxicity of neutralized chemical agent identification sets (CAIS) containing agent in chloroform. Olajos E J; Morgan E W; Renne R A; Salem H; McVeety B; Johnson R; Phelps R L Edgewood Research Development and Engineering Center, Aberdeen Proving Ground, MD 21010-5423, USA Journal of applied toxicology : JAT (1998 Sep-Oct), 18(5), 363-71. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9804437 AN 1999019582 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

An acute head-only inhalation study was conducted in rats exposed for 1 h to product solution (wastestream) resultant from the chemical neutralization of Chemical Agent Identification Sets (CAIS) containing agent (sulfur mustard (HD), nitrogen mustard (HN-1) or lewisite (L)) in chloroform. Groups of Sprague-Dawley rats were exposed to varying concentrations (24000, 18000, 12000 or 6000 ppm) of CAIS wastestream. An additional group was exposed to the vehicle (chloroform/t-butanol) only, at a concentration equivalent to the concentration of vehicle at the highest exposure level. Animals were evaluated for toxic effects, including assessment of toxicant-induced alterations to the ocular and respiratory systems. Mortality on exposure to 24000 ppm of test article or to vehicle alone was high. Mortality in the other exposure groups was roughly proportional to the concentration of test article (wastestream). Toxic signs were consistent with exposure to solvent system components (chloroform/t-butanol) and to agent decomposition products/by-products. Incidence and severity of ocular effects were similar in vehicle control and treatment groups. The salient respiratory effect observed was a decreased minute volume, which was also noted in vehicle and treatment groups.

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Cardiorespiratory effects of O-isobutyl S-[2-(diethylamino)-ethyl] methylphosphonothioate -- a structural isomer of VX. Chang F C; Gouty S C; Eder L C; Hoffman B E; Maxwell D M; Brecht K M US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1998 Sep-Oct), 18(5), 337-47. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9804434 AN 1999019579 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

O-Isobutyl S-[2-(diethylamino)ethyl]methylphosphonothioate (VR) is a structural isomer of a more well-known chemical warefare agent, O-ethyl S-[2(diisopropylamino)ethyl]methylphosphonothioate (code designation VX). In this study, cardiorespiratory and central nervous system (CNS) effects of VR (2LD50 or 22.6 microg kg(-1); s.c.) were evaluated in urethane-anesthetized (Group 1) and unanesthetized (Group 2) guinea pigs instrumented for concurrent recordings of electrocorticogram (ECoG) and a variety of cardiorespiratory activities. The first sign of intoxication was a state of progressive bradycardia, vascular hypotension and arrhythmia (Group 1, approximately 13 min post-VR; Group 2, approximately 6 min post-VR). Bradypnea, excessive salivation and compensatory changes in blood pressure typically did not emerge until 3-5 min prior to apnea (Group 1, approximately 28 min post-VR; Group 2, approximately 15 min post-VR). An idioventricular rhythm, which signalled a failing myocardium, appeared at the same time or shortly after the development of a bradypneic profile. Another notable toxicity component of VR, based on arterial pH, pO2/pCO2 and bicarbonate (HCO3-) level data, was a state of combined hypercapnia, acidemia and hypoxemia during the development of bradypnea. Taken together, findings from this study indicated that changes in medullary respiratory unit activity and ECoG data displayed little, if any, notable signs of CNS perturbation prior to the terminal stage (approximately 1 min prior to respiratory failure). Thus, in addition to displaying a greater sensitivity to perturbation by VR, the peripheral cardiorespiratory system components also appeared to play a more important role in precipitating a progressively dysfunctional cardiorespiratory status that ultimately led to collapse of central respiratory mechanisms and death.

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Effect of sulphur mustard inhalation exposure on some urinary variables in mice. Kumar O; Vijayaraghavan R Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior, India Journal of applied toxicology : JAT (1998 Jul-Aug), 18(4), 257-9. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9719425 AN 1998383930 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The effect of sulphur mustard (2,2'-dichlorodiethyl sulphide) exposure through inhalation at 0.5. 1.0 and 2.0 LC50 (21.2, 42.3 and 84.6 mg m(-3) for 1 h) on some urinary variables was studied in female mice at 6, 24 and 48 h and 7 days post-exposure. The urinary excretion and circulatory blood accumulation of uric acid increased significantly. The level of creatine was also elevated significantly as compared to the control at 2 LC50. It is concluded that sulphur mustard alkylates DNA and triggers catabolism of apurinated purine bases in a very short time. The increase in uric acid excretion in urine can be detected only when the exposure concentration is high.

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Nerve agent poisoning in primates: antilethal, anti-epileptic and neuroprotective effects of GK-11. Lallement G; Clarencon D; Masqueliez C; Baubichon D; Galonnier M; Burckhart M F; Peoc'h M; Mestries J C Unite de Neurotoxicologie, CRSSA, La Tronche, France Archives of toxicology (1998), 72(2), 84-92. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9456079 AN 1998115614 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Organophosphorus nerve agents are still in use today in warfare and as terrorism compounds. Classical emergency treatment of organophosphate poisoning includes the combined administration of a cholinesterase reactivator (an oxime), a muscarinic cholinergic receptor antagonist (atropine) and a benzodiazepine anticonvulsant (diazepam). However, recent experiments with primates have demonstrated that such treatment, even when administered immediately after organophosphate exposure, does not rapidly restore normal electroencephalographic (EEG) activity and fails to totally prevent neuronal brain damage. The objective of this study was to evaluate, in a realistic setting, the therapeutic benefit of administration of GK-11 (gacyclidine), an antiglutamatergic compound, as a complement to the available emergency therapy against organophosphate poisoning. GK-11 was injected at a dose of 0.1 mg/kg (i.v) after a 45-min latency period to heavily intoxicated (8 LD50) primates. Just after intoxication, man-equivalent doses of one autoinjector containing atropine/pralidoxime/diazepam were administered. The effects of GK-11 were examined on survival, EEG activity, signs of toxicity, recovery after challenge and central nervous system histology. The present data demonstrate that treatment with GK-11 prevents the mortality observed after early administration of classical emergency medication alone. EEG recordings and clinical observations also revealed that GK-11 prevented soman-induced seizures and motor convulsions. EEG analysis within the classical frequency bands (beta, theta, alpha, delta) demonstrated that central activity was totally restored to normal after GK-11 treatment, but remained profoundly altered in animals receiving atropine/pralidoxime/diazepam alone. GK-11 also markedly accelerated clinical recovery of soman-challenged primates. Lastly, this drug totally prevented the neuropathology observed 3 weeks after soman exposure in animals treated with classical emergency treatment alone.
GK-11 represents a promising adjuvant therapy to the currently available emergency polymedication to ensure optimal management of organophosphate poisoning in man. This drug is presently being evaluated in a human clinical trial for a different neuroprotective indication.

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A model for quantitative measurement of sulfur mustard skin lesions in the rabbit ear. Zlotogorski A; Goldenhersh M; Shafran A Department of Dermatology, Hadassah University Hospital, Jerusalem, Israel. zloto@cc.huji.ac.il Toxicology (1997 Jun 27), 120(2), 105-10. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9184197 AN 97327530 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The search for treatment and protection against the vesicant and inflammatory skin lesions induced by sulfur mustard suffers from the lack of a good in vivo reproducible model. We applied sulfur mustard (25-500 microg/cm2) to the outer surface of the ears of 10 rabbits and measured the edema formation 12, 24 and 48 h post-application with a caliper especially designed for soft matter. There was a dose-dependent linear increase in edema magnitude in the range from 25 to 150 microg/cm2. Maximal edema was observed after 12 h. There was a 12% reduction in edema size 24 h after application and a further decrease after 48 h. Skin thickness, inflammatory cell infiltrate, necrosis and vesiculation were evaluated in biopsies taken after 24 h. We found the same dose-related increase both in skin thickness and in degree of blister formation. This simple dose-response in vivo model can be used for evaluation of the dermal inflammation induced by topical application of sulfur mustard. This model has the additional advantage of a built-in control, namely the untreated contralateral ear. Consequently, this model can serve as a useful tool for future screening of potential compounds for prevention and treatment of sulfur mustard-induced skin lesions.

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Effect of sulphur mustard on the expression of urokinase in cultured 3T3 fibroblasts. Detheux M; Jijakli H; Lison D Laboratory of Medical Toxicology, Catholic University of Louvain, Brussels, Belgium Archives of toxicology (1997), 71(4), 243-9. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9101041 AN 97255694 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The expression of plasminogen activator (PA), a serine proteinase involved in the degradation of extracellular matrix proteins, has been investigated in 3T3 fibroblasts after in vitro exposure to sulphur mustard (SM). Expression of the cell-associated enzyme has been assessed with a synthetic substrate assay and at the mRNA level. Twenty-four hours after 100 microM SM, cell viability (monitored by MTT assay) was not significantly affected, but protein synthesis (tritiated leucine incorporation) was reduced to < 20% of the control value. PA activity was significantly increased compared to control cells with a 20-fold increase after 24 h. This up-regulation was independent of the cell density, occurred maximally between days 1 and 4 and persisted for at least 6 days after exposure. Lower concentrations of SM (< or = 10 microM) did not significantly affect PA activity. Northern blotting experiments revealed an increased expression of urokinase (u-PA) transcripts in cells treated with 100 microM SM, with a peak at 10 h after exposure. Conditioned culture medium from cell cultures treated with 100 microM SM did not affect the expression of PA activity in naive or SM-treated cultures. Thiodiglycol (100 microM), the main metabolite of SM, did not influence the expression of PA in the same system. Different compounds were tested for modulation of the PA upregulation after SM exposure. Nicotinamide (5 mM), vitamin D3 (10(-10)M), extracellular calcium (2 mM) or EGTA (5 mM) had no effect. Ryanodine (10 microM) amplified the PA up-regulation by a factor of 2 and vanadate (500 microM) reduced it by approximately 50%. Dexamethasone (1 microM) added directly after SM treatment almost completely prevented the induction of PA at both the protein and mRNA levels. Overall these results demonstrate an up-regulation of urokinase in 3T3 fibroblasts after treatment with SM, which is possibly mediated by intracellular calcium mobilization.
Further studies are needed to identify the significance of this proteolytic response in the pathogenesis of blistering and/or DNA repair mechanisms.

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Synthesis and mass spectrometric identification of the major amino acid adducts formed between sulphur mustard and haemoglobin in human blood. Noort D; Hulst A G; Trap H C; de Jong L P; Benschop H P Department of Chemical Toxicology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1997), 71(3), 171-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049054 AN 97201271 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

As part of a program to develop methods for the verification of alleged exposure to sulphur mustard, we synthesized and characterized three amino acid adducts presumably formed by alkylation of haemoglobin: 4-(2-hydroxyethylthioethyl)-L-aspartate, 5-(2-hydroxyethylthioethyl)L-glutamate and N1- and N3-(2-hydroxyethylthioethyl)-L-histidine. Suitable derivatization methods for GC/MS analysis were developed for these adducts as well as for the cysteine and the N-terminal valine adduct. Incubation of human blood with [35S]sulfur mustard in vitro followed by acidic hydrolysis of isolated globin and derivatization with Fmoc-Cl afforded three radioactive peaks upon HPLC analysis, one of which coeluted with the synthetic Fmoc derivative of N1/N3-(2-hydroxyethylthioethyl)-L-histidine. After pronase digestion of globin the adducts of histidine, glutamic acid, aspartic acid, cysteine and N-terminal valine could be tentatively identified and quantitated. Final identification was obtained from GC/MS analysis. The most abundant adduct, N1/N3-(2-hydroxyethylthioethyl)-L-histidine, could not be sensitively analysed by GC/MS. A convenient LC-tandem MS procedure was developed for this compound, enabling the detection of exposure of human blood to 10 microM sulphur mustard in vitro.

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Protective effect of povidone-iodine ointment against skin lesions induced by sulphur and nitrogen mustards and by non-mustard vesicants. Wormser U; Brodsky B; Green B S; Arad-Yellin R; Nyska A Department of Pharmacology, School of Pharmacy, Faculty of Medicine, Hebrew University of Jerusalem, Israel Archives of toxicology (1997), 71(3), 165-70. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049053 AN 97201270 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Mustard gas (sulphur mustard, SM) is a powerful vesicant employed as a chemical weapon. The present study demonstrates the effect of povidone iodine (PI) ointment against skin toxicity caused by SM. Gross and histopathological examinations showed that application of PI up to 20 min following exposure to the vesicant resulted in marked skin protection. The shorter the interval between exposure and treatment the better was the protection achieved. PI was also effective against other mustards such as carboxybutyl chloroethyl sulphide (CBCS) and mechlorethamine. The fact that PI protected the skin against agents which cannot be oxidized such as iodoacetic acid, divinylsulphone and cantharidine showed that the antidotal effect of PI was unrelated to oxidation of the nitrogen and sulphur atoms of the mustards. PI ointment is proposed as an efficient protective agent against skin toxicity caused by mustards and other alkylators.

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Modifications of breathing pattern induced by inhaled sulphur mustard in mice. Vijayaraghavan R Pharmacology and Toxicology Division, Defence Research and Development Establishment, Gwalior, India Archives of toxicology (1997), 71(3), 157-64. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 9049052 AN 97201269 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A head-only exposure assembly was used for exposing mice to vapours of sulphur mustard (SM). The respiration was monitored using an on-line computer program, capable of recognizing the breathing pattern as sensory irritation, airflow limitation and pulmonary irritation. SM was dissolved in acetone and vapourized using a compressed air nebulizer. Mice were exposed to the vapours (8.5, 16.9, 21.3, 26.8, 42.3 and 84.7 mg/m3) for 1 h in a body plethysmograph fitted with a 20-gauge needle and a microphone for sensing the respiratory flow signals. The signals were amplified, digitized and integrated to give tidal volume, and stored in a computer for further analysis. The respiration of the mice was followed for modifications in the breathing pattern until 7 days post-exposure. SM induced sensory irritation during exposure, and there was a concentration dependent decrease in the respiratory frequency and an increase in tidal volume. Lower concentrations showed recovery after stopping the exposure. RD50, the concentration that depresses 50% of the respiration was estimated to be 27.4 mg/m3. Following exposure to higher concentrations the animals started dying after 6 days. The LC50 was estimated to be 42.5 mg/m3 (14 days observation period). The respiratory frequency decreased on subsequent days of exposure depending upon the exposure concentration, and the breathing pattern was characteristic of airflow limitation. The ratio of flow/tidal volume was decreased following exposure to concentrations of 26.8 and 42.3 mg/m3. The ratio of flow/tidal volume may be a better measurement than the measurements based on flow alone for the assessment of airflow limitation. Pulmonary irritation was not observed showing that the lungs were not affected. The body weight of the animals decreased progressively. The present methodology will be useful for identifying the effects of SM on the respiratory system, one of the endpoints considered when establishing occupational exposure limits.

[megalomania]

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Aluminum nitride defect chemistry dependence on sintering atmosphere. Chang, E. K.; Kirschner, M. J. BOC Group Technical Cent., Murray Hill, NJ, USA. Journal of Materials Science Letters (1996), 15(18), 1580-1581. CODEN: JMSLD5 ISSN: 0261-8028. Journal; General Review written in English. CAN 125:282600 AN 1996:614771 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 12 refs., of equations explaining theor. relations between aluminum nitride defect chem. and sintering atm.

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Microstructure, chemical reaction and mechanical properties of TiC/Si3N4 and TiN-coated TiC/Si3N4 composites. Huang, Jow-Lay; Lee, Ming-Tung; Lu, Horng-Hwa; Lii, Ding-Fwu. Dep. Material Science Eng., National Cheng-Kung Univ., Tainan, Taiwan. Journal of Materials Science (1996), 31(18), 4899-4906. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:254919 AN 1996:610489 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Silicon nitride contg. various compns. of as-received TiC and TiN-coated TiC, were hot pressed at 1800 C for 1 h in a nitrogen atm. In TiN-coated TiC/Si3N4 composites, TiC reacted first with the TiN coating to form a titanium carbonitride interlayer at 1450 C, which essentially reduced further reactions between TiC and Si3N4 and enhanced densification. TiN-coated TiC/Si3N4 composites exhibited better densification, hardness, flexural strength and fracture toughness than those of as-received TiC/Si3N4. The toughening mechanisms for as-received TiC/Si3N4 and TiN-coated TiC/Si3N4 composite were attributed to crack deflection, load transfer and crack interference by the compressive thermal residual stress.

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Wet chemical synthesis of ZrO2-SiO2 composite powders. Wang, Shi-Wei; Huang, Xiao-Xian; Guo, Jing-Kun. Shanghai Inst. Ceramics, Chinese Academy Sciences, Shanghai, Peop. Rep. China. Journal of the European Ceramic Society (1996), 16(10), 1057-1061. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 125:254896 AN 1996:596753 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of compn. xZrO2(I-x)SiO2, with x = 10, 20, 30 and 40 vol.%, have been prepd. by a wet chem. method using fumed silica and zirconyl chloride as precursors. Thermogravimetric anal. and differential thermal anal. (DTA) show that wt. loss is caused by release of the absorbed water and decompn. of the Zr(OH)4 gels. Gels were heat-treated for 2 h at 500, 700, 900, 1100 and 1350C, and the products examd. using IR spectroscopy. The increasing intensity of the peak at 800 cm-1 in the IR spectra with increasing temp. is attributed to the formation of Si-O-Si bonds among different SiO2 particles, which means that the SiO2 particles grow bigger with increasing temp. The DTA exothermic peak as well as the IR results reveal that the crystn. of tetragonal zirconia (t-ZrO2) begins at about 900C, which is confirmed by x-ray diffraction (XRD). XRD curves also suggest that the silica matrix contributes to the thermal stability of t-ZrO2. The stability of t-ZrO2 is interpreted by the particle-size effect.

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Structure-property relationship of ceramic coatings produced by laser processing. De Hosson, J. Th. M.; Zhou, X. B. Dep. Applied Physics, Univ. Groningen, Groningen, Neth. Materials Research Society Symposium Proceedings (1996), 397(Advanced Laser Processing of Materials--Fundamentals and Applications), 537-542. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:306847 AN 1996:579019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper deals with a well known puzzling observation that wetting in some instances is improved by a chem. reaction between a liq. and a solid substrate in laser processing while in other systems just the opposite effect takes place. Contact angles of liq. Al on SiO2 and liq. Ti on Al2O3 are reported and some results of laser melt injection of SiO2 particles into molten Al. The surface and interface structures were explored by SEM and energy dispersive x-ray spectrometry. According to the exptl. observations, it appears that the vol. change of ceramic substrates during reaction plays a key role in the effect of chem. reaction on wetting.

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Mechanical and thermal properties of SiC-SiC composites made with CVR SiC fibers. Kowbel, W.; Tsou, H. T.; Bruce, C. A.; Withers, J. C. MER Corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1996), 410(Covalent Ceramics III--Science and Technology of Non-Oxides), 417-422. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:202665 AN 1996:502987 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temps. up to 1600C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addn., enhancement of the composite through-the-thickness thermal cond. was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.

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The influence of surface kinetics in modeling chemical vapor deposition processes in porous preforms. Dekker, J. P.; Moene, R.; Schoonman, J. Lab. Appl. Inorg. Chem., Delft Univ. Technol., Delft, Neth. Journal of Materials Science (1996), 31(11), 3021-3033. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65201 AN 1996:378298 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The isothermal chem. vapor infiltration (ICVI) process is a well known technique for the prodn. of composites and the surface modification of porous preforms. Math. modeling of the process can provide a better understanding of the influence of individual process parameters on the deposition characteristics such as final porosity or deposition profiles in the pore network. The influence of different rate expressions for several binary compds. on the ICVI process is discussed. Exptl. work is used to validate the importance of correct kinetic expressions in a continuous ICVI model for cylindrical pores. The predicted infiltration characteristics are compared with exptl. results. The final densification and Thiele modulus, i.e. a no. which is a measure for the diffusion limitations in a pore, are used for the evaluation of the presented model, and conditions are given for an optimal densification of a porous preform by the ICVI process for several binary compds. The deposition profiles as predicted by the model calcns. are in agreement with the exptl. detd. deposition profiles of TiN and TiC in small tubes. Moreover, it can be concluded that the shape of the deposition profiles is detd. by the heterogeneous reaction kinetics. There is only a qual. agreement between the predicted densification and measured densification for the synthesis of TiN and TiB2 in sintered porous alumina. This mismatch can be explained in terms of a complexity of the pore network and differences in reaction kinetics. Model calcns. reveal that there is a scattering for the predicted residual porosity as a function of the Thiele modulus for TiN. Moreover, this Thiele modulus can not fully account for the changes in densification at different temps. Given these uncertainties it is likely that a residual porosity of less than one percent can be obtained if the Thiele modulus is smaller than 1  10-4. However, a CVI process with such a small Thiele modulus will not be practical, because of the concomitant long process times.
Therefore, more precise conditions for the individual process parameters, i.e. concn., reactor pressure, and temp. are deduced from the model calcns.

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Pressure-pulsed chemical vapor infiltration of TiN into SiC particulate preforms. Sugiyama, K.; Sugata, M. Dep. Appl. Chem., Aichi Inst. Technol., Toyota, Japan. Journal of Materials Science (1996), 31(11), 2945-2949. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65198 AN 1996:378286 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC particulate preforms were infiltrated by TiN matrix from a gas mixt. of TiCl4 (5%), nitrogen (30%) and hydrogen using a repeating pressure pulse between 760 and about 1 torr. SiC particle sizes of 5 and 20 m were used. For matrix packing into deep level, optimum temp. was detd. between 800 and 850, and the max. packing ratio reached 67% after 4  104 pulses at 850. The increase of TiCl4 concn. to 10% resulted in higher deposition rate and packing ratio. The decrease of nitrogen concn. led to slower deposition, i.e., a similar effect to temp. lowering. The max. flexural strength measured was 140 MPa.

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Synthesis of mullite coatings by chemical vapor deposition. Mulpuri, Rao P.; Sarin, Vinod K. Dep. Mfg. Eng., Boston Univ., Boston, MA, USA. Journal of Materials Research (1996), 11(6), 1315-1324. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 125:39956 AN 1996:366859 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Formation of mullite on ceramic substrates via chem. vapor deposition was investigated. Mullite is a solid soln. of Al2O3 and SiO2 with a compn. of 3Al2O32SiO2. Thermodn. calcns. performed on the AlCl3-SiCl4-CO2-H2 system were used to construct equil. chem. vapor deposition (CVD) phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were detd. Through process optimization, cryst. CVD mullite coatings have been successfully grown on SiC and Si3N4 substrates. Results from the thermodn. anal., process optimization, and effect of various process parameters on deposition rate and coating morphol. are discussed.

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Mixed chromium and aluminum oxides elaborated by a sol-gel process. I. Chemistry of the preparation. Rezgui, Saloua; Ghorbel, Abdelhamid; Henry, Marc. Lab. Chimie Materiaux Catalyse, Dep. Chimie, Tunisia. Journal of Materials Synthesis and Processing (1995), 3(6), 371-376. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 125:16967 AN 1996:331762 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of mixed chromium and aluminum oxide were prepd. by a sol-gel process. The precursor is a mixt. of Al(O-s-Bu)3 and Cr(acac)3 with a mass ratio Al/Cr = 10 in sec-butanol. Gelation occurred by adding acetic acid. The amt. of added acetic acid is represented by the ratio k = [CH3COOH]/[Al(O-s-Bu)3], with k varying between 0.5 and 3. Acetic acid played crucial roles in both hydrolysis and polycondensation, (1) producing water in situ by esterification, (2) modifying the precursor by substituting some of the O-s-Bu ligands by acetate ligands, and (3) catalyzing the polycondensation. The importance of each of these roles in the process as well as the nature of the products varied with the ratio k.

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Influence of alloying elements on the chemical reactivity between Si-Al-O-N ceramics and iron-based alloys. Vluegels, J.; Vandeperre, L.; Van Der Biest, O. Dep. Metallurgy Materials Eng., Katholieke Univ. Leuven, Leuvan, Belg. Journal of Materials Research (1996), 11(5), 1265-1276. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 124:323490 AN 1996:293140 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. interaction between two '-O' Si-Al-O-N ceramics and a no. of iron-based alloys is studied by means of static interaction couple expts. at 1100 and 1200 C. The onset temp. of reaction of Si3N4 with pure iron was 1095 C, which is in good agreement with a calcd. temp. of 1033 C. During the interaction, silicon and nitrogen from the ceramic dissolve and diffuse into the iron alloy, whereas the remaining aluminum and oxygen form Al2O3 particles. The interaction between the ceramic and iron alloy is reaction controlled. In the initial stage of the interaction, the dissocn. rate of the ceramic is the rate-controlling step. After the ceramic/metal interface is isolated from the furnace atm., the nitrogen soln. rate into the iron alloy becomes rate controlling. The influence of alloying elements on the reactivity could be related to their effect on the nitrogen soly. in the iron alloy. Ni, Si, and C decrease the nitrogen soly. and decrease the reactivity with the Sialon ceramic. Cr and Mo have the opposite effect. The thickness of the interaction layer on the ceramic side of the interaction couple was found to be a function of the calcd. nitrogen soly. in the iron alloy at 1 atm nitrogen pressure, making it possible to predict the relative chem. reactivity of a no. of iron-based alloys with the same Sialon ceramic.

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Preparation and pressureless sintering of chemical vapor deposited SiC-B composite powder. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Institute Materials Research, Tohoku University, Sendai, Japan. Jo
urnal of Materials Science (1996), 31(3), 679-83. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 124:239925 AN 1996:180535 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-B composite powder was prepd. by chem. vapor deposition (CVD) using (CH3)2SiCl2 + B2H6 + H2 as source gases at 1673 K. The powder was -type polycryst. silicon carbide contg. several per cents of boron and carbon. The boron content increased from 0 to 7.7 mass% as the B2H6 gas concn. increased from 0 to 0.7 mol%. Boron and carbon in amorphous form dispersed homogeneously in the -SiC polycryst. particles. The particles were spherical, non-agglomerated and uniform in size with an av. particle size of about 50 nm. Sintering tests were performed with the resulting composite powder without applying pressure. Powder contg. 1 mass% boron and 2 mass% carbon was sintered to a d. of 3.16 x 103 kg m-3 at 2273 K, and the Vickers hardness of the sintered body was 30 GPa. When the sintering temp. was higher than 2323 K, significant grain growth due to the phase transformation from  to  form occurred, which decreased bulk d. and Vickers hardness.

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Nanocrystalline metals, intermetallics, and a metal-matrix nanocomposite by solution-based chemical reductions. Buhro, W. E.; Haber, J. A.; Waller, B. E.; Trentler, T. J.; Suryanarayanan, R.; Frey, C. A.; Sastry, S. M. L. Department Chemistry, Washington University, St. Louis, MO, USA. Polymeric Materials Science and Engineering (1995), 73 39-40. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 124:123490 AN 1996:951 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A metal salt soln. was reduced to nanocryst. and nanocomposite. CuCl in THF was reduced with NaBH4 to form nanocrystal Cu, and Ni and Al can also be prepd. in similar manner. NiCl2 soln. was reduced with LiAlH4 ti NiAl intermetallic compds. of nano size. MoCl5 and SiCl4 were reduced with NaK to nanocryst. MoSi2 in ultrasound field. TiB2 nanocryst. particles were suspended in THF and CuCl was reduced to obtain a Cu-coated TiB2 nanocomposite.

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Preparation of low density free-standing shape of SiC by pressure-pulsed chemical vapor infiltration. Sugiyama, K.; Norizuki, K. Dep. Applied Chem., Aichi Inst. Technology, Toyoda, Japan. Journal of Materials Science Letters (1995), 14(23), 1720-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 124:64057 AN 1995:1000853 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of the conditions of pressure-pulsed chem. vapor infiltration (PCVI) on the deposition rate, ease of substrate oxidn., gross d., and flexural strength in prepn. of low-d. free-standing SiC shapes were examd. By selection of a porous carbon substrate, highly porous SiC shapes with a desirable pore distribution may be prepd. by the PCVI process.

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Identification of chemical and physical change during acid cleaning of ceramics. Johnson, Jessica S.; Erickson, Harold M.; Iceland, Harry. Texas Mem. Mus., Univ. Texas, Austin, TX, USA. Materials Research Society Symposium Proceedings (1995), 352(Materials Issues in Art and Archaeology 4), 831-7. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 124:54897 AN 1995:985335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This report describes the results of two expts. characterizing chem. and phys. change in ceramic constituents occurring from acid solns. commonly used to remove deposits from the surface of archaeol. ceramics. The first examines the chem. effects of hydrochloric acid, in an attempt to identify the yellow color, commonly known as "acid burn", often seen in museum collections on black-on-white sherds found in the Southwestern U.S. The compd. is identified as Fe2O3H2O. The second study compares the phys. effects of different acids on a group of Maya sherds. All acids tested in this study were found to cause phys. damage.

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Influence of particle characteristics on sintering behavior of alumina-zirconia composites. Balasubramanian, M.; Malhotra, S. K.; Gokularathnam, C. V. FRP Research Center, Indian Inst. of Technology, Madras, India. Journal of Materials Science Letters (1995), 14(21), 1484-5. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:347792 AN 1995:927403 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A uniform distribution of zirconia particles in an alumina matrix can be achieved by chem. processing methods. Three chem. processing routes were used to obtain better powders. The sintered d. and the tetragonal ZrO2 content of composites were correlated with powder size and morphol.

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Wet air oxidation of energetics and chemical agent surrogates. Copa, William M.; Momont, Joseph A. Zimpro Environmental Inc., Rothschild, WI, USA. Journal of Energetic Materials (1995), 13(3&4), 235-58. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295590 AN 1995:895724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Wet oxidn. studies have been conducted on a no. of energetic materials and wastewaters derived from energetic materials to demonstrate high destruction levels of specific energetic components. Triple-base propellant, OTTO Fuel (used as torpedo propellant) and hydrazine-based rocket fuel were energetics of interest. Triple-base propellant contain nitrocellulose, nitroglycerin, and nitroguanidine. OTTO Fuel contains substantial amts. of propylene glycol trinitrate. Hydrazine based rocket fuel contains hydrazine and 1,1-di-Me hydrazine (asym. di-Me hydrazine or UDMH). A bench scale wet air oxidn. study on alk. hydrolyzates of triple-base propellants indicated that essentially complete destruction of the reactive nitrogen components could be achieved at an oxidn. temp. of 280. Bench scale wet air oxidn. studies on OTTO Fuel wastewaters indicated that a >99% destruction of propylene glycol dinitrate can be achieved at 280. Processing OTTO Fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved even higher destruction levels. Bench scale wet air oxidn. studies on hydrazine-based rocket fuel wastewaters indicated that a 99.8% destruction of hydrazine and a >99.0% destruction of 1,1-dimethylhydrazine can be oxidized at 280. Again, processing of hydrazine-based rocket fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved similar destruction levels. The application of wet air oxidn. for the destruction of chem. agents has been made by the extrapolation of data from the wet air oxidn. of compds. with similar chem. structures or of surrogate compds. Sarin and V-agents are nerve agents which have an organo-phosphorus structure similar to that of contain commonly used pesticides. Pesticides such as glyphosate and malathion, which have a similar organo-phosphorus structure, are essentially completely destroyed (>99% destruction) by wet air oxidn. at 200-280. The chem. agent surrogate, di-Me Me phosphonate (DMMP) was wet air oxidized at 220-280. Alk.
hydrolyzed DMMP was wet air oxidized at 280. All of the oxidized effluents showed a >97.5% destruction efficiency for the DMMP. The blister agent, mustard (HD) is a chlorinated sulfide, bis(2-chloroethyl) sulfide. Org. sulfides such as mercaptans can be destroyed by wet air oxidn. at 260-280. It is concluded that the wet air oxidn. process is a promising alternative to incineration for disposal of energetics and chem. warfare agents.

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Molten salt oxidation of chemical munitions. Stewart, Albert; Schnittgrund, Gary. PyroPacific Processes, Grand Hills, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 213-34. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295589 AN 1995:895723 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molten salt oxidn. is reviewed as a potential near term alternative technol. for the destruction of chem. agents. Initial tests completed by the US Army in 1975 showed the promise of achieving very high removal efficiencies on actual agents. Recent testing by DOE has verified the potential for very low PIC and dioxin or furan releases. To further explore the possible application of this technol. to chem. agent destruction, a molten salt reactor and assocd. equipment was designed to process a nominal 50 kg/h of Sarin. Mass and energy balances are presented for process conditions representing a range of molten salt potential operational modes and schemes for enhancing plant capacity. Process economics are presented.

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Supercritical water oxidation of chemical agents, and solid propellants. Spritzer, M. H.; Hazlebeck, D. A.; Downey, K. W. San Diego, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 185-212. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295588 AN 1995:895722 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Supercrit. water oxidn. (SCWO), also referred to as hydrothermal oxidn. (HTO), is a developing technol. for the destruction of hazardous and nonhazardous wastes. SCWO destroys combustible materials using an oxidant in water at 350-600 and pressures of 17 MPa. General Atomics and its subcontractors are currently conducting 2 comprehensive research and demonstration programs geared toward the destruction of Department of Defense (DoD) wastes utilizing SCWO technol. Wastes of primary interest include chem. agents and solid propellants. Tech. challenges, particularly corrosion and solids handling, were overcome, and the destruction of chem. agents and solid propellants was demonstrated on a bench scale. SCWO results for chem. agents show destruction and removal efficiencies for GB, VX, and mustard agents to be in excess of 99.9999%, limited only by detection capability. SCWO results for hydrolyzed Class 1.1 solid propellant show destruction and removal efficiencies for total org. carbon (TOC) of >99.9%. Design and fabrication of a transportable SCWO pilot plant for chem. warfare agents, propellants and other DoD hazardous wastes and a prototype HTO system for solid rocket propellant disposal are complete and demonstration testing is underway.

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Pressure pulsed chemical vapor infiltration of SiC to two-dimensional-Tyranno/SiC-C preforms. Sygiyama, Kohzo; Yoshida, Yazutoshi. Department of Applied Chemistry, Aichi Institute of Technology, Toyoda, Japan. Journal of Materials Science (1995), 30(20), 5125-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:320390 AN 1995:894944 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preforms of two-dimensional Tyranno fiber (SiC base) of 7  20  1.3 mm3 were chem. vapor infiltrated with SiC at 850-1050C from a gas mixt. of CH3SiCl3 (6%)-H2 using pressure pulses between below 0.3 kPa and 0.1 MPa. Above 900C, films grew on the macrosurface dominantly. At 850C, residual porosity decreased to about 10% after 105 pulses, and three point flexural strength reached about 200 MPa. X-ray diffractograms on the surface showed the deposits to be -SiC only.

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Matrix characterization of fiber-reinforced SiC matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M.; More, K. L.; Sheldon, B. W.; Besmann, T. M.; Headinger, M. H.; Davis, R. F. Oak Ridge National Laboratory, Oak Ridge, TN, USA. Journal of Materials Science (1995), 30(17), 4279-85. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:206673 AN 1995:804167 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ceramic matrix composites (CMCs), that consist of silicon carbide (SiC) reinforced with continuous Nicalon or T-300 fibers, are being developed for many high-temp. structural applications. The large potential use of CMCs has prompted an in-depth investigation and characterization of these materials. Electron microscopy and micro-Raman spectroscopy were used to characterize and compare the SiC matrix crystal structure and morphol. of composite materials fabricated by two different chem. vapor infiltration (CVI) processes.

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Characterization of pseudo-porous SiC/C coatings on NextelTM 440 and NicalonTM fibers. Khasgiwale, N. R.; Butler, E. P.; Tsakalakos, L.; Hensley, D. A.; Cannon, W. R.; Danforth, S. C.; Gonczy, S. T. Center Ceramic Research, Rutgers University, Piscataway, NJ, USA. Materials Research Society Symposium Proceedings (1995), 365 395-400. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177329 AN 1995:774261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Pseudo-porous SiC/C coatings were deposited on NextelTM 440 and NicalonTM fibers by CVD. The morphol. and chem. of the coatings was evaluated, both before and after oxidn., using SEM, X-Ray Diffraction Anal. (XRD), XPS and Auger spectroscopy. Coated fibers were subjected to two different oxidn. treatments to assess coating stability: a) oxidn. at 600C for 20 h, and b) oxidn. at 1000C for 20 h. Pseudo-porous SiC/C on NicalonTM fibers appear to be more oxidn. resistant than the same coatings on NextelTM440 fibers.

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The preparation and economics of silicon carbide matrix composites by chemical vapor infiltration. Roman, Yvette G.; Stinton, David P. Centre Technical Ceramics-TNO, Eindhoven, Neth. Materials Research Society Symposium Proceedings (1995), 365 343-50. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 123:176964 AN 1995:774254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 35 refs. A no. of processing techniques that are currently in use for the development and prodn. of continuous fiber reinforced ceramic composite materials are described. The limited no. of available processing routes are compared with respect to the resulting material properties. The chem. vapor infiltration (CVI) technique is one of the most extensively developed methods. During the last decade, at least five different modifications of the isobaric isothermal CVI principle have been developed; each route having its own benefits. CVI techniques have now been developed to the extent that industrial commercialization is being realized. Projected cost aspects of the various CVI manufg. techniques are examd. and compared.

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Properties of SiC-SiC composites produced using CVR converted graphite cloth to SiC cloth. Kowbel, W.; Kyriacou, C.; Gao, F.; Bruce, C. A.; Withers, J. C. MER corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1995), 365 197-202. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177312 AN 1995:774236 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a new SiC reinforcement based upon a conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. This new SiC filaments exhibit an excellent creep resistance at temps. up to 1600C. Several SiC-SiC composites were fabricated using graphite fabric converted to SiC fabric utilizing the CVR process combined with a slurry infiltration and CVI densification. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites are discussed.

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Chemically bonded ceramic matrix composites: densification and conversion to diffusion bonding. Johnson, Bradley R.; Guelguen, Mehmet A.; Kriven, Waltraud, M. Department Materials Science and Engineering, University Illinois, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1995), 365 67-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177295 AN 1995:774216 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC's). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl2O4) powders were used as the chem. bonding matrix phase, while calcia-stabilized zirconia powders were the second phase material. Samples contg. up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal anal. (DTA/TGA). The phys. characteristics of this novel CMC were characterized by hardness, d., and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD.

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Oxidative catalytic decomposition of toxic gases using hydroxyapatite and fluorhydroxyapatite. Palucka, Timothy P.; Eror, Nicholas G.; McNamara, Thomas A. Department Materials Science and Engineering, University Pittsburgh, Pittsburgh, PA, USA. Materials Research Society Symposium Proceedings (1995), 368(Synthesis and Properties of Advanced Catalytic Materials), 275-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:151604 AN 1995:734790 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An oxidative catalytic route to decomp. nerve gases was studied using hydroxyapatite (HA, Ca10(PO4)6(OH)2) and its partially fluorinated analog fluorhydroxyapatite (FHA, Ca10(PO4)6Fx(OH)2-x). Samples were prepd. with surface areas of 34-238 m2/g to study surface area effects; 1.2 wt.% Pt was deposited on 1 substrate to study the effect of a transition metal on activity and selectivity. Reaction studies were performed using di-Me methylphosphonate, a nerve gas simulant, in a stream of 80% N and 20% O at 573 K and atm. pressure. High surface area FHA samples showed an increase in the protection period (period of 100% conversion) with increasing F substitution; such an increase was not seen for low surface area FHA samples. In the absence of Pt, the reaction products were CH3OH and di-Me ether; with Pt, CO2 was also obtained.

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Toxicity of sulfur mustard in adult rat lung organ culture. Sawyer, Thomas W.; Wilde, Paul E.; Rice, Paul; Weiss, M. Tracy. Medical Countermeasures Section, Defence Research Establishment Suffield, Box 4000, Medicine Hat, Alberta, Can. Toxicology (1995), 100(1-3), 39-49. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 123:104668 AN 1995:700024 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The toxicity of the chem. warfare agent sulfur mustard, (bis-(2-chloroethyl)sulfide, HD), was examd. in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concn. (LC50) of HD in these cultures was reproducible, and in the M range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathol. examn. of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochem., and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulfur mustard.

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Characterization and surface chemistry of uncoated and coated silicon nitride powders. Schmidt, H.; Nabert, G.; Ziegler, G.; Goretzki, H. Inst. Materialforschung, Univ. Bayreuth, Bayreuth, Germany. Journal of the European Ceramic Society (1995), 15(7), 667-74. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 123:90766 AN 1995:695131 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various Si3N4 powders, produced by different procedures, were characterized by imaging (TEM) and anal. methods (EDS, FT-IR, XPS) in the as-received state as well as after doping with a metal oxide (MgO). For the doping, an alternative procedure to the usual methods was applied based on sol. organometallic compds. Anal. TEM combined with lateral resoln. element anal. and XPS measurements was used for morphol., structural and anal. characterization. The distribution of the dopant was deduced from measurements of XPS sputter depth profiles. These investigations were supplemented by FT-IR measurements to det. qual. and semi-quant. the reactive groups on the particle surfaces of the as-received powders. For comparison, measurements were performed with Si3N4 powders which were doped by the above chem. procedure and by mech. mixing. The results of the various characterization methods are interpreted in the form of a model display for surface reactions of organometallic doping reagents on the surfaces of ceramic particles. The results show that Si3N4 powders with high concn. of OH groups on their particle surface reveal very good distribution of the fluxing element (layer-like coating).

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Influence of crystallographic orientation, chemical inhomogeneities, material transport anisotropy and elastic strain energy on the migration of grain boundaries in chromium-doped alumina during internal reduction. Backhaus-Ricoult, Monika; Peyrot-Chabrol, A.; Chiron, R.; Hagege, S. Cent. d'Etudes Chim. Metall., CNRS, Vitry, Fr. Materials Research Society Symposium Proceedings (1995), 357(Structure and Properties of Interfaces in Ceramics), 293-9. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:90732 AN 1995:685875 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Diffusion-induced grain boundary migration is obsd. during internal redn. of chromium-doped alumina. It occurs because grain boundary diffusion is fast compared to lattice diffusion of oxygen. The oxygen chem. potential relaxes between grain boundaries and adjacent grains. Migration to either side of the boundary is controlled by multiple factors: chem. compn. differences between adjacent grains, elastic strain energy differences on the two sides of the boundary plane or by more rapid oxygen relaxation when the c-axis of a grain is perpendicular to the boundary plane.

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Synthesis and chemical stability of NaSn2P3O12. Breval, E.; Harshe, G.; Agrawal, D. K.; Limaye, S. Y. Intercoll. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Journal of Materials Science Letters (1995), 14(10), 728-31. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:39204 AN 1995:606064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

NaSn2P3O12 and NaZr2P3O12 powders were prepd. by solid-state reaction methods and sintered at 1050-1200. The resulting pellets were characterized in terms of d., thermal expansion, and phase compn. before and after chem. stability tests. Chem. stability tests were performed in polethylene containers in 3 solns., H+ + SO42- (pH = 0.5), Na+ + H+ + SO42- (pH = 0.7), and Na+ + OH- (pH + 14.3). Results indicate that NaSn2P3O12 is a very stable NZP compd. in high and low pH solns. (pH + 0.5-14.3) as compared to the parent compn. NaZr2P3O12, which shows high losses, esp. in alk. leachants. The surface-to-vol. of a single phase NaSn2P3O12 material, sintered without sintering agents, hardly affects the dissoln. Use of a sintering agent may result in a highly reactive grain boundary phase, the amt. of which may exceed the amt. of added sintering aid.

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Low-level detection of chemical agent simulants in meat and milk by ion trap mass spectrometry. Buchanan, Michelle V.; Hettich, Robert L.; Xu, Jing Hai; Waters, Larry C.; Watson, Annetta. Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Building 5510, MS/6365, Oak Ridge, TN, USA. Journal of Hazardous Materials (1995), 42(1), 49-59. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 123:31526 AN 1995:596587 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. methods for the detection of two chem. warfare agent simulants, diisopropyl methylphosphonate and chloroethylethylsulfide, in beef tissue and milk were demonstrated to be effective to levels as low as 50-100 ppb. These methods are based upon thermal desorption into an ion trap mass spectrometer. Selective detection of the target compds. is achieved by isobutane chem. ionization in combination with collision-induced dissocn., which yields characteristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limits achieved with this method suggest that it may be possible to take small tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the anal. In addn., because the new methods may be performed more quickly than conventional methods requiring substantial sample prepn. and anal. time, more samples could be analyzed.

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The effect of ceria co-doping on chemical stability and fracture toughness of Y-TZP. Boutz, M. M. R.; Winnubst, A. j. a.; Van Langerak, B.; Scholtenhuis, R. J. M. Olde; Kreuwel, K.; Burggraaf, A. J. Faculty of Chemical Technology, University of Twente, Enschde, Neth. Journal of Materials Science (1995), 30(7), 1854-62. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 122:271892 AN 1995:504770 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and ageing resistance of yttria, ceria-stabilized tetragonal zirconia polycrystals (Y, Ce-TZP) were evaluated as a function of grain size and ceria content. Very fine grained, fully dense materials could be produced by sinter forging at relatively low temps. (1150-1200C). The aging resistance in hot water (185C) of 2 mol% Y2O3-stabilized TZP is strongly enhanced by alloying with ceria. The ceria content necessary to avoid degrdn. completely, decreases with grain size. The toughness of fully dense Y, Ce-TZP is 7-9 MPa m1/2 for grain sizes down to 0.2 m. No or very little transformation took place during fracturing and no clear variation with grain size was obsd. for the toughness at grain sizes up to 0.8 m. Reversible transformation and crack deflection may explain the obsd. toughness values.

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Microstructure and chemistry of second phases in MgO- and NiO-codoped alumina by analytical transmission electron microscopy. Park, K.; Vasilos, T.; Sung, C. Cent. Advanced Materials Dep. Chem. Nuclear Eng., Univ. Massachusetts, Lowell, MA, USA. Journal of Materials Science Letters (1995), 14(4), 261-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 122:167982 AN 1995:415637 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects MgO-NiO-codoping on microstructure and chem. of 2nd phases, segregated particles and cryst. defects in alumina ceramics were examd. MgO-NiO-codoping contributed significantly to the prepn. of dense fine-grained alumina. It appeared that Ni-Al and Ni-Mg-Al spinels, segregated Ni particles, and K-'' alumina ppts. were formed at triple points or at grain boundaries, because the concns. of the MgO and NiO dopants were higher than their solid solubilities. In particular, the codopants formed a Ni-Mg-Al spinel as well as a Ni-Al spinel, because Mg2+ and Ni2+ were partitioned in the cation position of the spinel structure.

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Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry. Bentley, J.; Horton, L. L.; McHargue, C. J.; McKernan, S.; Carter, C. B.; Revcolevschi, A.; Tanaka, S.; Davis, R. F. Metals and Ceramics Div.r., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1994), 332(Determining Nanoscale Physical Properties of Materials by Microscopy and Spectroscopy), 385-90. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:87360 AN 1995:266442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resoln. of <5 nm. Anal. of Fe L23 white lines indicates a low-spin state with a charge transfer of .apprx.1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2-5% in the Co:O stoichiometry were measured across 100-nm-thick Co3O4 layers in an oxidized directionally solidified CoO-ZrO2 eutectic, with the highest O levels near the ZrO2. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for Co3O4 have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid soly. occurred in an AlN-SiC film grown by low-temp. mol. beam epitaxy (MBE) on (6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycryst. AlN on SiC, interfacial 8H Sialon (aluminum silicon oxynitride) and pockets of Si3N4-rich '-Sialon in the SiC were detected.

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Chemically bonded ceramics as an alternative to high temperature composite processing. Gulgun, Mehmet A.; Johnson, Bradley R.; Kriven, Waltraud M. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1994), 346(Better Ceramics through Chemistry VI), 511-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:15230 AN 1995:174876 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Processing of multi-phase ceramic composite materials using chem. bonded ceramics as a binding agent appears to be a promising route for fabricating complex-shaped structures. In a zirconia-calcium aluminate ceramic matrix composite, the hydraulic property of fine, monocalcium aluminate (CaAl2O4) powders was used to prep. strong prefired bodies. The changes in the phys. characteristics of the composite during the conversion from a chem. bonded compact into a sintered composite were studied using thermogravimetric analyses (TGA), X-ray diffraction and SEM. The d. and the hardness of the chem. bonded and sintered composite were measured.

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Assessing delayed neurotoxicity in rodents after nerve gas exposure. Husain, K.; Pant, S. C.; Vijayaraghavan, R.; Singh, Ram. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(2), 161-4. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:294553 AN 1994:694553 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Delayed neurotoxicity of an organophosphorus nerve gas, Sarin (a chem. warfare agent) following repeated inhalation exposure in rats and mice, was studied by behavioral, biochem. and histopathol. analyses. Rats exposed to Sarin aerosols (12.5 mg/m3 for 20 min) daily for ten days did not exhibit any clin. sign of delayed neurotoxicity. Neurotoxic esterase (NTE) activity in the brain, spinal cord and platelets was significantly inhibited, but the inhibition was below the threshold. Histopathol. examn. of spinal cord did not show any axonal degeneration. Mice exposed to Sarin aerosols (5 mg/m3 for 20 min) daily for ten days developed mild ataxia and muscular weakness of the hind limb on 14th day after the start of exposure. NTE activity was significantly inhibited in brain, spinal cord and platelets. Histopathol. of spinal cord showed focal axonal degeneration. Acetyl-choline esterase activity in the platelets of both the animals was significantly inhibited. The authors conclude that mice are sensitive to delayed neurotoxicity induced by repeated exposure to Sarin whereas rats are insensitive.

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Clean-up of chemical warfare agents on soils using simple washing or chemical treatment processes. Amos, Denys; Leake, Brian. DSTO, Aeronautical and Maritime Research Laboratory, P.O. Box 4331, Melbourne, Victoria, Australia. Journal of Hazardous Materials (1994), 39(1), 107-17. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:262645 AN 1994:662645 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several simple processes have been studied for the destruction of chem. agents, Soman and Mustard, on soils. A double wash or an extended single wash with water was effective in removing Mustard and Soman from soil; addn. of either anionic or cationic surfactant did not improve removal efficiency. Soils with higher org. carbon content were more difficult to decontaminate. The most effective chem. process for the removal of Mustard was treatment with hypochlorite; treatment with Na2CO3 or NaOH were almost as effective as hypochlorite in cleaning Mustard contaminated soil. Soman was removed most effectively by treatment with Na2CO3. Overall the most efficient process for the destruction of both Mustard and Soman was treatment with Na2CO3 soln.

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Liquid phase sintering, electrical conductivity, and chemical stability of lanthanum chromite doped with calcium and nickel. Christie, G. M.; Middleton, P. H.; Steele, B. C. H. Dep. Mater., Imperial Coll. Sci., Tech. Med., London, UK. Journal of the European Ceramic Society (1994), 14(2), 163-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:236480 AN 1994:636480 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The substitution of 10 mol% nickel for chromium in calcium-doped lanthanum chromite has been shown to promote rapid densification of the compd. at low temps. in air by the form of a transient liq. phase. Liqs. were generated via the decompn. of CaCrO4 second phase material present in calcined powders. During elec. cond. measurements at 1000C, severe microstructural degrdn. occurred at atms. of H2 and CO2. The processes leading to chem. degrdn. are attributed to the pptn. of Ni from the (La,Ca)(Cr,Ni)O3 solid soln. and to the decompn. of small amts. of residual CaCrO4 which remains at grain boundaries and triple points after sintering. DTA studies on CaCrO4 in CO2 and H2 atms. suggested that the degrdn. due to CaCrO4 decompn. was primarily a result of the reaction of CaO with CO2 to form CaCO3. The presence of H2 gas is thought to catalyze this reaction via the formation of large amt. of CaO during the decompn. of CaCrO4. Degrdn. is more severe in atms. contg. a mixt. of CO2 and H2 gases than in either gas on its own.

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Photochemical degradation of a toxic organophosphorus analog (PMSF) in microemulsion media. Yang, Yun; Donegan, Sheila; Patel, Ramesh C.; Ward, Anthony J. I. Center for Advanced Materials Processing, Clarkson University, Potsdam, NY, USA. Chemosphere (1994), 28(11), 1967-76. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 121:217331 AN 1994:617331 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A study has been made of the photodegrdn. of an analog, phenylmethylsulfonyl fluoride (PMSF), of a toxic chem. warfare agent. The agent was solubilized in a water-in-oil surfactant stabilized microemulsion system comprising sodium dodecyl sulfate, pentanol and water. Loss of the parent PMSF mol. upon exposure of the system to UV irradn. was monitored by 19F NMR spectroscopy. Consideration of the changes in the chem. shifts, splittings in conjunction with GC/Mass spectroscopy data strongly suggest the degrdn. leads to partial fluorination of pentanol. Anal. of peak areas also indicates the formation of volatile degrdn. products such as HF. The addn. of TiO2 or hydroquinone to the system did not appreciably change the overall amts. of degrdn. The results are interpreted in terms of the possible radical based reaction pathways and show that such a microemulsion medium to have significant potential as a vehicle for effecting such a degrdn. process.

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Comparative evaluation of high protein against normal protein diet in combination with carbamates against organophosphorus intoxication in rats. Chatterjee, A.K.; Sikder, Nirmala; Sikder, A.K. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(1), 11-14. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:197892 AN 1994:597892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The relative efficacy of an isocaloric high protein diet (HPD) contg. 59 per cent protein, in comparison to a conventional diet contg. 21 per cent protein, as applied in the alleviation of toxicity of diisopropyl phosphorofluoridate (DFP) and Me iso-Pr phosphonofluoridate (sarin), has been reported. In combination with well-known prophylactics like carbamates and cholinolytics like atropine against nerve gas toxicity, HPD appears to be superior to the conventional diet as studied by survival time measurements. Apart from carbamates, atropine and mecamylamine, HPD may be treated as an addnl. prophylactic agent to guard against the toxicity of DFP and sarin, which are being used as war chems.

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The surface chemistry of silicon nitride powder in the presence of dissolved ions. Hackley, V. A.; Malghan, S. G. Ceram. Div., Natl. Inst. Standards and Technol., Gaithersburg, MD, USA. Journal of Materials Science (1994), 29(17), 4420-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 121:185440 AN 1994:585440 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Colloidal processing of silicon nitride (Si3N4) powders depends largely on the control of reactions at the solid-soln. interface. The role of dissolved ions in the surface chem. of Si3N4 powders has been investigated, and the implications of these results for the effects of impurities, contaminants and additives in processing are discussed. The interaction of ions at the solid-soln. interface was characterized by particle electrokinetic behavior detd. from electroacoustic measurements in moderately concd. suspensions. Ions were classified according to chem. similarity and surface specificity. Specific adsorption was inferred from the movement of the isoelec. point relative to the endemic "native" value. Most simple univalent electrolytes behaved indifferently towards the Si3N4 surface, with the exception of fluoride which specifically adsorbed and may have formed a strong complex with surface silicon sites. The alk.-earth cations exhibited a similar weak specificity. In the presence of hydrolyzable transition metal cations, powder surface chem. was controlled by the adsorption of hydroxy metal complexes and by the soly. of a surface-pptd. metal hydroxide phase. Oxo anions, such as sulfate and carbonate, adsorbed specifically on the Si3N4 surface, but the interactions were weaker than previously obsd. on metal oxide surfaces.

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X-ray photoelectron spectroscopy of uv laser irradiated sapphire and alumina. Pedraza, A. J.; Park, J. W.; Meyer, H. M., III; Braski, D. N. Dep. Materials Science Engineering, Univ. Tennessee, Knoxville, TN, USA. Journal of Materials Research (1994), 9(9), 2251-7. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 121:162453 AN 1994:562453 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

XPS was performed in as-received, thermally annealed, and laser-irradiated sapphire and alumina specimens to study the effects of the different treatments on surface chem. and properties. Laser irradiations with a 308 nm wavelength laser were performed in air and in a reducing atm. consisting of a mixt. of Ar and 4% hydrogen. The at. percentages of carbon, aluminum, and oxygen were measured in all the specimens. Particular attention was paid to the percentages of oxygen in the oxide and in a hydroxyl state. The XPS analyses clearly established that a very thin film of metallic aluminum is formed on the surface of both alumina and sapphire substrates when they are irradiated under a reducing atm. However, the film is discontinuous because it is elec. insulating. Substrates irradiated in air have metallic aluminum only for fluences below 0.4 J/cm2. The valence band photoemission spectra of as-received, annealed, and laser-irradiated specimens were measured. In irradiated specimens, the width of the valence band spectra was found to decrease by .apprx.10%. One possible cause of this decrease is the generation of point defects during laser irradn. Electroless copper deposition occurs on sapphire and alumina substrates if their surface has been activated by laser irradn. The time required for copper deposition was monitored by measuring the elec. resistivity in the irradiated area while the substrates were immersed in an electroless bath. The kinetics of deposition on laser-activated substrates and the XPS results show that the presence of metallic aluminum accelerates the deposition process. However, the presence of aluminum is not the sole reason for laser activation in alumina. Very strong metal-ceramic bonding is produced after thermal annealing of samples having preirradiated substrates. This result is explained in terms of the excess oxygen that is present at the ceramic surface after irradn.

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X-ray absorption spectroscopy study of the local structure and the chemical state of yttrium in polycrystalline -alumina. Loudjani, M. K.; Cortes, R. Lab. Metallurgie Structurale, CNRS, Orsay, Fr. Journal of the European Ceramic Society (1994), 14(1), 67-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:162396 AN 1994:562396 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. state and local structure around the yttrium ion in doped polycryst. -alumina (0.03  mol% Y2O3  1) system was examd. by extended x-ray absorption fine structure (EXAFS) measurements for yttrium K-edge energy. In the case of highly doped alumina samples (0.1 and 1 mol% Y2O3) most of the yttrium is pptd. as a Y3Al5O12 phase, whereas in the dil. doped alumina sample (0.03 mol% Y2O3) yttrium is in solid soln., being located on the octahedral aluminum sites. The yttrium ion size, comparatively greater than that of the aluminum ion, induces locally a significant distortion of the oxygen ion lattice. This effect creates point defects in the nearest neighbor shell of the yttrium: vacancy (Vo..) and interstitial (Oi'') oxygen point defects.

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Constitution of the -alumina phase in chemically produced mullite precursors. Schneider, H.; Voll, D.; Saruhan, B.; Schmucker, M. Inst. Mater. Res., German Aerosp. Res. Establ., Cologne, Germany. Journal of the European Ceramic Society (1993), 13(5), 441-8. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:89568 AN 1994:489568 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The temp. development of type II mullite precursor powders have been studied in the temp. range of 150C (as-received) and 1150C. X-ray diffraction measurements, IR and 29Si and 27Al NMR spectroscopy and anal. transmission electron microscopy have been performed on the heat-treated precursors. The investigations had the aim of contributing to the frequently discussed question, whether Si is incorporated into the -alumina spinel being formed as a transient phase in type II mullite precursors. The as-received precursors consist of relatively large spherical particles ( 05 m) of noncryst. SiO2 and of much finer-grained agglomerates of pseudo-boehmite crystals (-AlO(OH),  20 nm), which are embedded in a SiO2 matrix. Above 350C, pseudo-boehmite transforms to spinel-type alumina (-Al2O3). During this transformation, all Si existing in the SiO2 matrix of the pseudoboehmite agglomerates is incorporated into -Al2O3 corresponding to a SiO2 content of 12 mol% at 500C. Up to 750C, the SiO2 content of the -alumina remains const. but above this temp. it gradually rises and reaches a max. amt. of 18 mol% at 1150C. A marginal decompn. of the spherical non-cryst. SiO2 particles may be the sources to provide diffusion of Si species into the -alumina during a temp. increase above 750C. It is most likely that Si species diffuse into the -alumina crystals along the crystallite boundaries. The diffusion process and Si incorporation are facilitated with the temp. increase.

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Quantitative analysis of Si3N4 microstructure response on interface chemistry. Meissner, E.; Unger, S.; Kleebe, H.-J.; Ziegler, G. Univ. Bayreuth, Bayreuth, Germany. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 471-5. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:89560 AN 1994:489560 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. microstructure anal. was performed on gas-pressure sintered Si3N4 materials (SSN) by employing an image processing system. Variations in grain-diam. distribution and aspect-ratio distribution with changing additive compn. and annealing time, resp., were investigated. Clear evidence was found that both interface compn. and post-sintering anneal can strongly affect the matrix grain morphol. For the Y2O3-doped material, extended annealing time supported the formation of Si3N4 grains with increased diam. and length via Ostwald ripening. Moreover, the aspect-ratio distribution was shifted to higher values indicating anisotropic grain growth. The addn. of Al2O3 + ZrO2, compared to SSN doped with Y2O3, resulted in a finer microstructure with still high aspect ratios. This chem. effect is closely related to the viscosity of the liqs. at processing temps. Furthermore, ZrO2 addn. results in a more pronounced transgranular fracture mode, while Y2O3-contg. SSN predominantly revealed intergranular fracture. The influence of annealing time and interface chem. on both microstructure evolution and resulting fracture toughness is discussed.

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Surface chemical interactions of Si3N4 with polyelectrolyte deflocculants. Hackley, V.A.; Premachandran, R.; Malghan, S.G. Mater. Sci. Eng. Lab., Natl. Inst. Stand. Technol., Gaithersburg, MD, USA. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 679-82. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:41008 AN 1994:441008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interaction of org. polyelectrolyte deflocculants at the Si3N4 solid-soln. interface was investigated using electroacoustic measurements, polymer adsorption and particle size distribution anal. One cationic and two anionic polymers were studied: quaternized poly(diamine epoxychlorohydrin), ammonium poly(methacrylate) and poly(acrylic acid), resp. Electrostatic interactions are emphasized as a function of pH, concn. and mol. wt.

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Metabolite pharmacokinetics of soman, sarin and GF in rats and biological monitoring of exposure to toxic organophosphorus agents. Shih, Ming L.; McMonagle, Joseph D.; Dolzine, Theodore W.; Gresham, Vincent C. US Army Med. Res. Inst. Chem. Def., Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1994), 14(3), 195-9. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 121:28848 AN 1994:428848 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study reports on the pharmacokinetics of the elimination of the metabolites of three toxic organophosphorus compds. (soman, sarin and GF). Urine, blood and lung tissue were collected from rats dosed s.c. at 75 g kg-1. Urinary excretion of the metabolite was the major elimination route for these three compds. The major differences among them were primarily the extent and rate of excretion. The hydrolyzed form, alkylmethylphosphonic acid, was the single major metabolite formed and excreted in urine by a non-saturable mechanism. Nearly total recoveries of the given doses for sarin and GF in metabolite form were obtained from the urine. The terminal elimination half-lives in urine were 3.7  0.1 and 9.9  0.8 h for sarin and GF, resp. Soman metabolite showed a biphasic elimination curve with terminal half-lives of 18.5  2.7 and 3.6  2.2 h. Soman was excreted at a slower rate with a recovery of only 62%. Lung was the major organ of accumulation for soman. In blood the toxic agents were concd. more in red blood cells than in plasma. The acid metabolites can serve as a better chem. marker for monitoring organophosphorus exposure in humans via their higher concn. and longer half-life in urine than the parent compds.

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Movement of chemical warfare agent simulants through porous media. Jenkins, R. A.; Buchanan, M. V.; Merriweather, R.; Ilgner, R. H.; Gayle, T. M.; Watson, A. P. Analytical Chemistry Division, Oak Ridge National Laboratory, Building 4500S, MS-6120, P.O. Box 2008, Oak Ridge, TN, USA. Journal of Hazardous Materials (1994), 37(2), 303-25. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:16666 AN 1994:416666 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A measurement protocol is documented and data are presented to characterize the permeation of chem. warfare agent simulants through the porous construction materials brick, cinder block, gypsum wall board, and wood. These data will be used to develop guidelines for access ("reentry") to potentially contaminated properties if nerve or vesicant agents are released during any phase of the US Department of the Army's Chem. Stockpile Disposal Program. A novel permeation cell design allowed sampling of air vols. adjacent to the spiked face, breakthrough face, and lateral face of each test medium at two temps. Simulant movement through wood is nearly always in the direction of the wood grain. Two-dimensional breakthrough was obsd. in brick and gypsum wall board. The sulfur mustard simulant broke through all test media in less than 60 min; nerve agent simulant breakthrough required several hours. Surface decontamination of wood with high-test hypochlorite is 95% effective.

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Pharmacology of organophosphates. Koelle, George B. Med. Sch., Univ. Pennsylvania, Philadelphia, PA, USA. Journal of Applied Toxicology (1994), 14(2), 105-9. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 121:2654 AN 1994:402654 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 8 refs. The cholinergic nerve fibers, which employ acetylcholine (ACh) as a neurohumoral transmitter, and the results of their activation are listed. The reactions between the enzyme acetylcholinesterase (AChE), its natural substrate, ACh, and the various types of inhibitors are described. The limited therapeutic uses of the anticholinesterase (anti-ChE) agents are considered. The toxicol. effects encountered when the anti-ChE agents are employed as insecticides or as chem. warfare (CW) agents are discussed. Certain anti-ChE agents produce also a delayed neurotoxic effect which is apparently unrelated to the inhibition of AChE.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson, Barry W.; Kawakami, Thomas G.; Cone, Norman; Henderson, John D.; Rosenblatt, Leon S.; Goldman, Marvin; Dacre, Jack C. Inst. Toxicol., Univ. California, Davis, CA, USA. Toxicology (1994), 86(1-2), 1-12. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 120:263586 AN 1994:263586 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (tabun, phosphoramidocyanidic acid, dimethyl-, Et ester) as part of a program to demilitarize chem. warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but not in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only 3 of the 5 assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Effect of chemically added zirconia and yttria mechanical properties of zirconia-dispersed alumina. Ranjbar, Khalil; Rao, Boddapati T.; Mohan, Tallapragada R. Rama; Harendranath, Chilkunda S. Dep. Metall. Eng., Indian Inst. Technol., Bombay, India. American Ceramic Society Bulletin (1994), 73(2), 63-6. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 120:171374 AN 1994:171374 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Alumina powders dispersed with monoclinic, tetragonal, and cubic zirconia were prepd. by evapg. a colloidal dispersion of alumina powders in solns. contg. zirconium and yttrium salts. The dried and calcined powders were compacted, sintered, and characterized. The results demonstrated a clear toughening effect by the zirconia on the alumina ceramics. The alumina contg. 20-wt%-yttria-stabilized tetragonal zirconia had the max. toughness.

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Chemical vapor infiltration of silicon carbide with microwave heating. [Erratum to document cited in CA119(2):13852e]. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(12), 3251. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 120:141948 AN 1994:141948 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The errors were not reflected in the abstr. or the index entries.

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Chemical compatibility between silicon-based and titanium-based ceramics. Wang, L.; Wada, H. Dep. Mater. Sci. Eng., Univ. Michigan, Ann Arbor, MI, USA. Journal of Materials Synthesis and Processing (1993), 1(3), 181-93. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:277176 AN 1993:677176 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. compatibility between Si-based ceramics and Ti-based ceramics was studied to establish guidelines for the processing of related composites. Phase stabilities were calcd. for the Si-Ti-B-C, Si-Ti-B-N, and Si-Ti-B-C-N systems as a function of B activity and N pressure or C activity. SiC is compatible with TiC, TiN, or TiB2, depending on the range of these parameters. Si3N4 and TiN appear to be compatible in a certain range of N2 pressure and C activity, but Si3N4 and pure TiC will not coexist. However, the fact that TiC and TiN can form a solid soln., TiC1-xNx, suggests that Si3N4 and TiC1-xNx may be obsd. in the presence of both C and N2. The Si3N4 + TiB2 2-phase region is limited in such a narrow range of N2 pressure and B activity that processing and application of TiB2/Si3N4 composites would be very difficult. High-temp. solid-state expts. were carried out with selected systems to verify phase stability diagrams. The results of reactions were in agreement with the thermodn. prediction. A high-d. TiB2/SiC composite was prepd. as an example of the application of phase stability diagrams.

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Thermal and acid catalyzed conversion of organic phosphorus compounds. De Lijser, H. J. P.; Mulder, P.; Louw, R. Cent. Chem. Environ., Leiden Univ., Leiden, Neth. Chemosphere (1993), 27(5), 773-8. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:233159 AN 1993:633159 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The org. P compds. tri-Bu and tri-Me phosphate (I and II, resp.), tri-Me phosphite (III), and di-Me phosphonate (IV) were thermolyzed using a plug flow (gas-phase) reactor. I and II proved to be sensitive to acid (wall) catalysis and can be fully degraded at temps. of .mchlt.400. III can isomerize to II and IV. In contrast, IV requires a temp. of >750 for complete conversion; admixed with II it counteracts the smooth acid-mediated degrdn. of II. Unlike real thermolysis at elevated temps., preferably in a reducing atm. of hydrogen, mere acid catalysis is not generally applicable for effectively destroying a variety of ecotoxic org. P compds.

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Preparation of uniformly calcia-doped zirconia. Hill, J.; Newhouse, M.; Xue, J.; Dieckmann, R. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Journal of Materials Synthesis and Processing (1993), 1(2), 101-9. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:232072 AN 1993:632072 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The prepn. of dense samples of high-purity zirconia doped with varying, small contents of CaO has been explored by means of traditional ceramic techniques with sintering and hot-pressing as well as a chem. soln. method. First, CaO-doped samples were prepd. by traditional ceramic methods. Their homogeneities were checked by SEM with x-ray mapping. CaO-dopant distribution was not uniform in all samples with overall CaO contents below 7 mol%. The difficulty in prepg. uniformly doped zirconia with small CaO contents led to exploration of the use of chem. soln. processing techniques. When exploring such techniques, the products of each process step were characterized by x-ray diffraction and electron microprobe anal. The characterization results enabled identification of a processing route which is suitable for prepg. dense, high-purity zirconia uniformly doped with CaO at low concns.

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A model for the isothermal isobaric chemical vapor infiltration (CVI) in a straight cylindrical pore. Application to the CVI of silicon carbide. Fedou, R.; Langlais, F.; Naslain, R. Lab. Compos. Thermostruct., CNRS, Pessac, Fr. Journal of Materials Synthesis and Processing (1993), 1(2), 61-74. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:208796 AN 1993:608796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A previously described modeling of the chem. vapor infiltration (CVI) process in a straight cylindrical pore is applied to the deposition of SiC-based ceramics from MeSiCl3-H2 in the case of a 1st-order kinetic law with respect to MeSiCl3. The model gives concns. and deposit thickness profiles along the pore at any stage of the densification and, particularly, at the end of the process when the pore becomes sealed. The infiltration homogeneity is predicted to be improved by decreasing the aspect ratio of the pore and the CVI temp. and, under conditions of Fick diffusion, by decreasing the total pressure and the pore diam. The model is validated by the good fit between the deposit thickness profiles along the pore calcd. after adjustment of the kinetic data and exptl. profiles for a 34-m straight pore.

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Nicalon-fiber-reinforced silicon carbide composites via polymer solution infiltration and chemical vapor infiltration. Kim, Young Wook; Song, Jin Soo; Park, Sang Whan; Lee, Juen Gunn. Struct. Ceram. Lab., Korea Inst. Sci. Technol., Seoul, S. Korea. Journal of Materials Science (1993), 28(14), 3866-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 119:186895 AN 1993:586895 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A new, faster process was developed for the fabrication of Nicalon-fiber-reinforced SiC composites by combining polymer soln. infiltration (PSI) and chem. vapor infiltration (CVI). The process led to the near-net-shape fabrication of fiber-reinforced ceramic-matrix composites and reduced infiltration time. Typical flexural strength and fracture toughness of these composites were 296 MPa and 10.9 MPa.m1/2 at room temp. and 252 MPa and 9.6 MPa.m1/2 at 1000, resp. The composites exhibited load-carrying capability after crack initiation.

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The effect of glass chemistry on the microstructure and properties of self reinforced silicon nitride. Pyzik, Aleksander J.; Carroll, Daniel F.; Hwang, C. James. Adv. Ceram. Lab., Dow Chem. Co., Midland, MI, USA. Materials Research Society Symposium Proceedings (1993), 287(Silicon Nitride Ceramics), 411-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:186804 AN 1993:586804 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The advantage of self-reinforced silicon nitride is the in-situ control of the microstructure. This control is provided in large degree by the chem. of glassy phase which can be adjusted to tailor the morphol. of silicon nitride grains as well as the matrix-reinforcement interface. The presence of high aspect ratio silicon nitride grains is necessary but not sufficient condition to produce materials with optimum properties. For max. flexure strength and fracture toughness, an optimized glass matrix is required.

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Microwave assisted chemical vapor infiltration. Devlin, D. J.; Currier, R. P.; Barbero, R. S.; Espinoza, B. F.; Elliott, N. Mater. Sci. Technol. Div., Los Alamos Natl. Lab., Los Alamos, NM, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 245-50. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144800 AN 1993:544800 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A microwave-assisted process for prepn. of continuous fiber-reinforced ceramic-matrix composites is described. A simple app. combining a chem.-vapor-infiltration reactor with a conventional 700-W multimode oven is described. Microwave-induced inverted thermal gradients are exploited with the ultimate goal of reducing processing times on complex shapes. Thermal gradients in stacks of SiC (Nicalon) cloths have been measured using optical thermometry. Initial results on the inside-out deposition of SiC via decompn. of MeSiCl3 in H are presented. Several key processing issues are identified and discussed.

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Chemical vapor deposition of multiphase boron-carbon-silicon ceramics. Golda, E. Michael; Gallois, B. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 167-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144796 AN 1993:544796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Specific compns. of boron-carbon-silicon ceramics exhibit improved abrasive wear and good thermal shock resistance, but require bulk sintering at temps. in excess of 2100K. The formation of such phases by CVD was examd. at 1073-1573K. Methyltrichlorosilane (CH3SiCl3), boron trichloride, and methane were chosen as reactant gases, with hydrogen as a carrier gas and diluent. The coatings were deposited in a computer-controlled, hot-wall reactor at a pressure of 33 MPa. Below 1473K the coatings were amorphous. At higher temps. nonequil. reactions controlled the deposition process. The most common coating consisted of a silicon carbide matrix and a silicon boride, SiB6, dispersed phase. Multiphase coatings of B + B4C + SiB6 and SiC + SiB6 + SiB14 were also deposited by controlling the partial pressure of methane and boron trichloride. Non-equil. thermodn. anal. qual. predicted the exptl. deposited multiphase coatings.

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CVD of silicon nitride plate from trichlorosilane-ammonia-hydrogen mixtures. Lennartz, J. W.; Dowell, M. B. Union Carbide Coat. Serv. Corp., Parma, OH, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 161-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144795 AN 1993:544795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preferred conditions for deposition of thick -Si3N4 plate from HSiCl3-NH3-H2 on the vertical surfaces of a low-pressure, hot-wall CVD reactor were identified by means of a designed expt. The design included temp. range 1300-1500, pressures 0.5-2.0 torr, and residence times 0.01-1.0 s. The vertical deposition surfaces received a viscous, laminar flow of well mixed, thermally equilibrated reactants. Plates 0.05-0.5 mm thick were produced on multiple vertical substrates 350 cm2 in area at deposition rates 5-70 m/h. Plates 0.5-4.0 mm thick were produced on horizontal substrates at deposition rates of 60-120 m/h. When NH3 flows in stoichiometric excess, deposition rates on vertical surfaces increase approx. linearly with the flow rate of HSiCl3 but depend little on temp., as would be expected if the reaction proceeds under mass transport control with product depletion. Multiple correlation analyses show that thickness variations in the deposit are reduced by increasing the temp. and decreasing the gas residence time. CVD silicon nitride plate produced under the optimized conditions exhibits theor. d. and is free of pores and cracks. It exhibits a columnar morphol. in which the <222> and <101> crystallog. directions are oriented preferentially normal to a surface, which consists of well-defined trigonal facets 10-50 m across. Crystallite sizes detd. by x-ray line broadening range from 0.06-1.0 m. This CVD plate is gray and contains approx. 0.5 C and 0.5 wt.% 0 as principal impurities.

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Unequivocal evidence. Black, Robin M.; Pearson, Graham S. Chem. Biol. Def. Estab., Porton/Down/Salisbury Wiltshire, UK. Chemistry in Britain (1993), 29(7), 584-5, 587. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 119:123791 AN 1993:523791 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of chem. warfare agent, Sarin, in the Kurdush village of Birjinni, Iraq, was discussed.

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Bioanalysis of organophosphate nerve agents in soil samples. Sawyer, T. W.; Weiss, M. T. Biomed. Def. Sect., Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Chemosphere (1993), 26(11), 2023-9. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:94477 AN 1993:494477 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Four soil samples that may have been spiked with chem. warfare (CW) agents and their degrdn. products were received by Defense Research Establishment Suffield as part of a multinational round-robin exercise designed to evaluate lab. methodologies for the chem. detection of CW agents in soil. After chem. anal. revealed that VX (Et S-2-diisopropyl aminoethyl methylphosphorothiolate) was the CW agent "spike", the samples were also bioassayed for their VX content by assessing their anticholinesterase activities in primary chick embryo neuron cultures. Bioassay quantitation of VX contamination in the soil samples was in good agreement with the actual spike levels and generally better than the chem. anal. results. Sequential bioassay of the samples over a two week period showed that the VX content was rapidly degraded with time. This assay complements std. chem. anal. techniques for the detection and verification of organophosphate warfare agent use.

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The effect of trace element segregation to iron/sapphire interfaces. Pope, D. P.; Smith, M. A. Dep. Mater. Sci., Univ. Pennsylvania, Philadelphia, PA, USA. Materials Research Society Symposium Proceedings (1992), 238(Structure and Properties of Interfaces in Materials), 427-32. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:77041 AN 1993:477041 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of segregation of tramp impurities such as sulfur on metal/ceramic bonding is discussed. Microstructural and chem. information is given for the Fe/sapphire interface. The segregation behavior of the interface is evaluated between 500-800. The interfacial structure is important to the segregation behavior. A possible link between the segregation of sulfur and interface void formation is presented.

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Chemical vapor infiltration of silicon carbide with microwave heating. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(5), 1057-67. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 119:13852 AN 1993:413852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is presented to describe the interaction between transport/reaction processes and the evolution of porosity in chem. vapor infiltration with microwave heating (MCVI). The anal. includes a set of partial differential equations describing the spatiotemporal variation of gaseous species concn., composite temp., porosity, and stress. Maxwell's equations were used to det. the distribution of power dissipated inside the composite. The deposition of silicon carbide was selected as a model chem. system to explore the general features of MCVI. MCVI can provide a favorable temp. distribution in the composite yielding an inside-out deposition pattern, thereby preventing entrapment of accessible porosity. For this temp. profile, tensile stresses develop at the outer regions and compressive stresses are found in the composite core. For a given system there exists a min. value of the coeff. for heat transfer from the composite surface, h, below which accessible porosity is trapped within the composite. Similarly, there exists a max. value of the incident microwave energy flux, I0, above which accessible porosity is trapped within the composite. I0 and h can be optimized for a given preform to achieve complete densification with min. processing time. Using the technique of pulsed-power, the processing time can be reduced even further without compromising d. uniformity. Power dissipation profiles in the composite depend strongly on preform thickness, microwave frequency, and relative loss factor.

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Permeation measurements of chemical agent simulants through protective clothing materials. Pal, Tarasankar; Griffin, Guy D.; Miller, Gordon H.; Watson, Annetta P.; Daugherty, Mary Lou; Vo Dinh Tuan. Health Saf. Res. Dev., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Hazardous Materials (1993), 33(1), 123-41. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 118:239880 AN 1993:239880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A method was developed to study the permeation of chem. warfare (CW) agent simulants through chem. protective clothing (CPC) materials. The exptl. results characterize some com. available CPC materials. Thirteen different CPC materials having widely differing compns. were chosen to study the permeation of 4 different liq. CW simulants (di-Me methylphosphonate, diisopropyl methylphosphonate, malathion, and Bu2S) through these CPC materials at 25. This permeation study involved a newly developed anal. technique employing room temp. fluorescence quenching of an indicator compd., phenanthrene, on filter paper. Various exptl. factors such as breakthrough time, rate of permeation, and uptake were investigated. On the basis of breakthrough time, the 13 CPC materials could be divided into 3 groups: most resistant, moderately resistant, and least resistant. Materials in the most resistant category exhibited no permeation by any of the simulants for 24 h. Breakthrough occurred in the least resistant materials in generally less than an hour, and sometimes as soon as a few minutes.

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Interfacial structure of chemical vapor infiltration carbon fiber/silicon carbide composite. Araki, H.; Noda, T.; Abe, F.; Suzuki, H. Tsukuba Lab., Natl. Res. Inst. Met., Tsukuba, Japan. Journal of Materials Science Letters (1992), 11(23), 1582-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:44089 AN 1993:44089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure at the interface in carbon fiber-SiC matrix composites prepd. by chem. vapor infiltration from EtSiCl3 was examd., and the infiltration reaction is discussed. A graphite layer formed on the carbon fiber and the SiC-SiC interface as a result of thermal decompn. of silane gas before SiC infiltration. This graphite layer, of .apprx.500 nm thickness, is assumed to assist in the crystal growth of SiC, leading to structural stability of the composites.

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Comparative evaluation of carbamates as prophylactic agents against organophosphate intoxication in rats. Chatterjee, A. K. Def. Res. Dev. Establ., Gwalior, UK. Defence Science Journal (1992), 42(2), 85-7. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 118:34070 AN 1993:34070 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper investigates the effects of two well-known carbamates, physostigmine and pyridostigmine, against organophosphorus compd. and nerve gas toxicity. Physostigmine pretreatment for 30 min enhanced the survival time of rats against DFP intoxication, whereas it did not have any effect with sarin poisoning. However, pyridostigmine pretreatment did not produce any significant effect on survival time either against DFP or sarin intoxication. Treatment with atropine along with carbamates further enhanced significantly the survival time against DFP poisoning.

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On the influence of chemical processing in the crystallization behavior of zirconium titanate materials. Navio, J. A.; Macias, M.; Sanchez-Soto, P. J. Inst. Cienc. Mater., Univ. Sevilla, Seville, Spain. Journal of Materials Science Letters (1992), 11(23), 1570-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:26385 AN 1993:26385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The crystn. phenomena of ZrTiO4 powders prepd. from various gel precursors was related to the chem. processing. Correlation of data from the literature and further expt. indicated that the presence of H2O2 in the chem. processing of the amorphous precursors plays a key role in controlling the crystn. temp. The crystn. temp. can be as low as 640.

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Effect of dopants on the sintering behavior and stability of tetragonal zirconia ceramics. Theunissen, G. S. A. M.; Winnubst, A. J. A.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1992), 9(4), 251-63. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:54278 AN 1992:454278 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure development during nonisothermal and isothermal sintering was studied for tetragonal zirconia ceramics (TZP) contg. various amts. of Y, Ce, and Ti. Smaller grain sizes were obtained when Ce-TZP was doped with Y. This could be attributed to segregation of Y to the grain boundaries, thus causing an impurity drag. With increasing temp., the grain growth rate in the Ce-TZP samples increased which could be attributed to the absence of a dragging force. The slow grain growth at low temp. in the Ce-TZP samples could be attributed to the slow diffusion kinetics of the diffusing species (trivalent and tetravalent Ce). The crit. grain size for retainment of the tetragonal phase at room temp. is larger in the Y,Ce-TZP systems compared to the Y-TZP and Ce-TZP systems. The chem. stability increased by doping Y-TZP with Ce or Ti.

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Free radical-mediated lung response to the monofunctional sulfur mustard butyl 2-chloroethyl sulfide after subcutaneous injection. Elsayed, Nabil M.; Omaye, Stanley T.; Klain, George J.; Korte, Don W., Jr. Letterman Army Inst. Res., Presidio of San Francisco, CA, USA. Toxicology (1992), 72(2), 153-65. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 117:42116 AN 1992:442116 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors postulated that vesicants may cause free radical-mediated oxidative stress distal to the site of exposure. To test this postulate in the lung, the authors injected 3 groups of 5-mo-old, male, athymic, nude mice, weighing 30-35 g with a single s.c. dose (5 L/mouse) of Bu 2-chloroethyl sulfide (BCS). Total lung wt. was not altered after treatment, but the wet/dry wt. ratio decreased 18% and Hb content increased 50 and 36% at 1 and 24 h, resp. The activity of glucose 6-phosphate dehydrogenase increased significantly, 40% at 1 and 24 h and 84% at 48 h and that of glutathione S-transferases was 60%. Lipid peroxidn. (estd. by the thiobarbituric acid test) and total protein content increased 3-fold and 2-fold, at 1 and 24 h, resp. Total and oxidized glutathione contents were significantly elevated, 38% at 1 h and 64% at 24 h for the former and 45% at 24 h and 56% at 48 h for the latter. Because these changes are consistent with the cellular response to oxidative stress, it is concluded that BCS injected s.c. can cause changes in the lung possibly via a free radical-mediated mechanism.

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Effects of liquid environments on zirconia-toughened alumina. Part I. Chemical stability. Thompson, I.; Rawlings, R. D. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1992), 27(10), 2823-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:32321 AN 1992:432321 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The structural changes which occur in zirconia-toughened alumina when aged in a range of liq. environments (distd. water, ethylene glycol soln., and HCl at room temp., and ethylene glycol soln. at 80) are described. The changes were monitored by x-ray diffraction, surface anal., anal. of the aging solns., and microstructural observations. HCl induced significant proportions of the zirconia particles in the zirconia-toughened alumina to transform from the tetragonal to the monoclinic crystal structure. This transformation was accompanied by microcracking which eventually led to macrocracking after long periods of aging. The transformation is a consequence of the leaching of the yttrium from the zirconia particles, thereby reducing their stability.

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Binder chemistry, adhesion and structure of interfaces in thick-film metalized aluminum nitride substrates. Newberg, C. E.; Risbud, S. H. IBM Corp., East Fishkill, NY, USA. Journal of Materials Science (1992), 27(10), 2670-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:13161 AN 1992:413161 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Aluminum nitride substrates from 3 sources were metalized by std. thick-film processing using gold conductor pastes, Pd-Ag paste, and a ruthenium oxide resistor paste. Screen-printed pastes were fired in a typical 3-zone furnace to obtain metalized AlN substrates. Interfacial reaction zones were studied by microscopic (optical and SEM) and electron beam microprobe anal. techniques. The elements in the binder materials in thick-film pastes form amorphous phases at the interface which influence the adhesion of thick films to the AlN substrate. The lack of certain elements (Cd, Zn, Ca) in the binder of the gold thick-film paste led to weaker adhesion and severe degrdn. of the thick-film adhesion during thermal cycling.

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Preparation and characterization of a dispersion toughened ceramic for thermomechanical uses (ZTA). Part I. Material preparation. Characterization of microstructure. Leriche, A.; Moortgat, G.; Cambier, F.; Homerin, P.; Thevenot, F.; Orange, G.; Fantozzi, G. CRIBC, Mons, Belg. Journal of the European Ceramic Society (1992), 9(3), 169-76. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:13037 AN 1992:413037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Zirconia-toughened alumina (ZTA) materials contg. increasing amts. of zirconia (5-45 vol.%) and yttria (0-3 mol% zirconia) were prepd. from com. ceramic powders by different techniques of homogenization, shaping, and sintering. The powder mixts. were homogenized by a chem. method (addn. of dispersing agents at fixed pH), by a mech. method (attrition milling) and by combining the methods. The materials were formed and sintered by shaping by isostatic pressing or slip casting, followed by pressureless sintering, and by hot uniaxial pressing. The phys., crystallog. and microstructural properties of the materials prepd. following these different techniques are compared. The combined chem. and mech. dispersion method leads to the fabrication of dense composites presenting a fine and homogeneous zirconia dispersion required for effective toughening of the alumina matrix. The addn. of 3 mol% of yttria allows maintenance of a high tetragonal zirconia content because of a chem. stabilization of tetragonal zirconia and of a decrease of zirconia grain size. As the hot-pressing technique impedes the grain coarsening, the hot-pressed materials present the finest microstructure mainly for the compns. with <20 vol.% zirconia. The zirconia and alumina grain size vary from 0.5 to 0.9 m and from 0.9 to 1.6 m, resp., following the compn. Pressureless sintered materials also present a fine microstructure with submicron zirconia grains (0.6 m-0.9 m) and micron size alumina grains (1.0-1.9 m). These ZTA materials present all the microstructural characteristics necessary to obtain high mech. performances. The addn. of 3 mol% of yttria allows an increase of the zirconia content (45 vol.%) without a decrease of the relative tetragonal zirconia ratio occurring.

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Adsorption and decomposition of organophosphorus compounds on nanoscale metal oxide particles. In situ GC-MS studies of pulsed microreactions over magnesium oxide. Li, Yong Xi; Koper, Olga; Atteya, Maher; Klabunde, Kenneth J. Dep. Chem., Kansas State Univ., Manhattan, KS, USA. Chemistry of Materials (1992), 4(2), 323-30. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 116:200414 AN 1992:200414 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Using an in-situ pulse reactor-GC-mass spectrometric system, the thermal decompn. of organophosphorus compds. (as models of nerve agents) were compared with their destructive absorption on high-surface-area MgO. Dramatically lower temps. are required when MgO is present. Volatile products evolved were HCO2H, water, alcs., and alkenes. At higher temps., CO, CH4, and water predominated. The P residues remained completely immobilized. The addn. of water enhanced the facility of MgO to destroy these compds., and, in fact, water pulses were found to partially regenerate a spent MgO bed. Using 18O labeling, some aspects of the reaction mechanisms were clarified and in particular showed that O scrambling occurred. Surface OH and MgO groups transferred O in the formation of HCO2H, and the surface mobility and reactivity of absorbed groups were high. The substantial capacity of high-surface-area MgO for destruction and immobilization of such toxic substances makes it attractive for air purifn. schemes, as well as solid reagents for destruction and immobilization of bulk quantities of hazardous P compds. or organohalides.

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-(N,N-Dialkylamino)ethyl arylthiosulfonates: new simulants for O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate. Davis, Franklin A.; Ray, Jayanta K.; Kasperowicz, Steve; Przeslawski, Robert M.; Durst, H. Dupont. Dep. Chem., Drexel Univ., Philadelphia, PA, USA. Journal of Organic Chemistry (1992), 57(9), 2594-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 116:193819 AN 1992:193819 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Certain S-[2-(dialkylamino)]ethyl benzenesulfonothioates 4-XC6H4SO2SCH2CH2NR2 (I; X = Me, F; R = Me2CH) were prepd. as simulants for O-Et S-[(diisopropylamino)ethyl]methylphosphonothioate (VX) a chem. warfare nerve agent. I are useful simulants for the hydrolysis or oxidn. chem. of VX.

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Dissolution of sintered silicon nitride bulk specimens for elemental analysis. Homeier, E. H.; Bradley, S. A.; Karasek, K. R. UOP, Des Plaines, IL, USA. Journal of Materials Science (1992), 27(5), 1231-4. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:179524 AN 1992:179524 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Heating bulk, sintered Si3N4 samples in an aq. HF-HCl mixt. decomps. the Si3N4. Subsequent addn. of H2SO4 and volatilization of fluorides enables total dissoln. of the bulk specimens for anal. The elemental compns. that were detd. by inductively coupled plasma at. emission and at. absorption spectrometries agreed with the nominal sample compn. and confirmed analyses performed by scanning TEM. Neutron activation detns. on the same samples are not believed to be as accurate as the spectrometric detns. Furthermore, the precision of the neutron activation measurements were less satisfactory, esp. for key elements such as Y.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy, Paul M.; Hansen, Arnold S.; Hand, Brian T.; Boulet, Camille A. Def. Res. Establ. Suffield, Ralston, AB, Can. Toxicology (1992), 72(1), 99-105. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 116:168061 AN 1992:168061 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a std. set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI 6 > HLoe 7 > pyrimidoxine. Hloe 7 was very effective against tabun poisoning while HI 6 and pyrimidoxime were of moderate value. Against GF, HI 6 and HLoe 7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLoe-7 to a slightly lesser degree. The other oximes lacked the effects against one or more of the organophosphates.

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Chemical vapor deposition of copper via disproportionation of hexafluoroacetylacetonato(1,5-cyclooctadiene)copper(I), (hfac)Cu(1,5-COD). Jain, A.; Chi, K. M.; Hampden-Smith, M. J.; Kodas, T. T.; Farr, J. D.; Paffett, M. F. Dep. Chem. Eng., Univ. New Mexico, Albuquerque, NM, USA. Journal of Materials Research (1992), 7(2), 261-4. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 116:111299 AN 1992:111299 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hot- and cold-wall chem.-vapor deposition (CVD) using the volatile Cu(I) compd. (hfac)Cu(1,5-COD), where hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate and 1,5-COD = 1,5-cyclooctadiene, as a precursor was carried out in hot-wall and warm-wall, lamp-heated reactors using SiO2 substrates that were patterned with Pt or W at 120-250. Deposition was obsd. onto Pt, W, and SiO2 over this temp. range at rates of 3750 .ANG./min to give Cu films that contained no impurities detectable by AES and with resistivities of 1.9-5.7 ohm-cm. The volatile byproducts formed during deposition were 1,5-COD and Cu(hfac)2 and a mass balance was consistent with the quant. disproportionation reaction: 2(hfac)Cu(1,5-COD)  Cu + Cu(hfac)2 + 2(1,5-COD). The measured activation energy for this CVD reaction was 26(2) kcal/mol. The absence of selectivity for metal surfaces in the presence of SiO2 is in contrast to CVD results for the related compds. (-diketonate)Cu(PMe3) where -diketonate = hfac, 1,1,1-trifluoroacetylacetonate, and acetylacetonate (acac).

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer, Thomas W.; Weiss, M. Tracy; D'Agostino, Paul A.; Provost, Lionel R.; Hancock, James R. Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Journal of Applied Toxicology (1992), 12(1), 1-6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 116:105057 AN 1992:105057 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chem. warfare activity was subjected to chem. anal. and bioassay. Sarin and several related compds. were confirmed in the soil by capillary column gas chromatog.-mass spectrometry (GC-MS); however, the binding of these compds. to the soil hindered quantitation. The chem. results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified stds. in chick embryo neuron cultures, a reasonable agreement was found between the chem. and bioassay semiquant. ests. of sarin content in the soil ext. Furthermore, the in-vitro system appears to offer a sensitive technique for the estn. of sarin remaining bound to the soil following solvent extn. as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Pharmacological effects of oximes: how relevant are they?. van Helden H P; Busker R W; Melchers B P; Bruijnzeel P L Department of Pharmacology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1996), 70(12), 779-86. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 8911635 AN 97068325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The increased international concern about the threat of military and terroristic use of nerve agents, prompted us to critically consider the expected value of the currently available oxime treatment of nerve agent poisoning. Although oximes have been designed to reactivate the inhibited acetylcholinesterase (AChE), clinical experience has indicated that they are not always very effective as reactivators and at this very moment none of them can be regarded as a broad-spectrum antidote. In spite of this drawback, oximes are worth further investigating, since recent data derived from soman or tabun lethally intoxicated non-human primates suggest that the oxime HI-6 may exert a pharmacological effect that is not related to reactivation of inhibited AChE, but still leads to survival. This pharmacological effect causes recovery of neuronal transmission in the respiratory centres of the brain and recovery of neuromuscular transmission in the diaphragm. These findings have stimulated research to reveal the pharmacological basis of these effects in order to find drugs which could be more effective and less toxic than the available oximes. Since cholinergic drugs were able to exert this effect, a new concept for further treatment is suggested: maintenance of neuronal transmission in spite of continued AChE-inhibition by pharmacological manipulation of the cholinergic receptor. This should renew interest in the diverse pharmacological effects of oximes to reach a more effective treatment in the future.

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Evaluation of the therapeutic efficacy of some antimuscarinics against soman in vivo. Lau W M; Lewis K J; Dawson R M Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organization, Department of Defence, Melbourne, Victoria, Australia Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 423-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889794 AN 97044723 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The therapeutic efficacy of tacrine, atropine and glycopyrrolate alone or in combination with the oxime HI-6 against soman was evaluated in anaesthetized rats. Arterial blood pressure, heart rate, respiratory frequency and body temperature were monitored in vivo. Blood cholinesterases were determined after each drug or soman challenge. At the lowest concentration tested (2.5 mg kg-1), tacrine was effective in improving the survivability of the rat by a factor of 2.6 (protection ratio), whereas the protection by atropine or glycopyrrolate was either insignificant or only marginally effective (protection ratio ranged from 1.0 to 1.9). In combination with HI-6, atropine increased the ratio to 4.6. In contrast, tacrine with HI-6 failed to improve the efficacy of the regimen, while glycopyrrolate plus HI-6 showed only slight improvement. The four physiological parameters monitored were relatively constant during the time course of the experiment in both the control and those with drug therapy. The more noticeable changes occurred toward the end of the experiment when sufficient amount of soman was injected to cause lethality. Death of the animal was usually preceded by a surge of arterial blood pressure and heart rate and a decrease in respiratory frequency. These physiological parameters rapidly deteriorated to zero just before the animal died. Blood and plasma cholinesterases were significantly inhibited after the animal received a relatively small dose of soman (20 micrograms kg-1) and were almost completely inactivated after the lethal dose of soman was administered. However, these changes of enzyme activity did not correspond well with the survivability of the rat. The inclusion of HI-6 with the three antimuscarinics appeared to be capable of protecting some cholinesterases against soman.

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Efficacy of ibuprofen and pentoxifylline in the treatment of phosgene-induced acute lung injury. Sciuto A M; Stotts R R; Hurt H H Pathophysiology Division, United States Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 381-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889788 AN 97044717 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Phosgene, a highly reactive former warfare gas, is a deep lung irritant which produces adult respiratory distress syndrome (ARDS)-like symptoms following inhalation. Death caused by phosgene involves a latent, 6-24-h, fulminating non-cardiogenic pulmonary edema. The following dose-ranging study was designed to determine the efficacy of a non-steroidal anti-inflammatory drug, ibuprofen (IBU), and a methylxanthine, pentoxifylline (PTX). These drugs were tested singly and in combination to treat phosgene-induced acute lung injury in rats. Ibuprofen, in concentrations of 15-300 mg kg-1 (i.p.), was administered to rats 30 min before and 1 h after the start of whole-body exposure to phosgene (80 mg m-3 for 20 min). Pentoxifylline, 10-120 mg kg-1 (i.p.), was first administered 15 min prior to phosgene exposure and twice more at 45 and 105 min after the start of exposure. Five hours after phosgene inhalation, rats were euthanized, the lungs were removed and wet weight values were determined gravimetrically. Ibuprofen administered alone significantly decreased lung wet weight to body weight ratios compared with controls (P < or = 0.01) whereas PTX, at all doses tested alone, did not. In addition, the decrease in lung wet weight to body weight ratio observed with IBU+PTX could be attributed entirely to the dose of IBU employed. This is the first study to show that pre- and post-treatment with IBU can significantly reduce lung edema in rats exposed to phosgene.

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Subchronic toxicity evaluation of sulfur mustard in rats. Sasser L B; Miller R A; Kalkwarf D R; Cushing J A; Dacre J C Pacific Northwest Laboratory, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1996 Jan-Feb), 16(1), 5-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8821670 AN 96418885 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

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Acute toxicity of cyclohexylmethylphosphonofluoridate (CMPF) in rhesus monkeys: serum biochemical and hematologic changes. Young G D; Koplovitz I U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Archives of toxicology (1995), 69(6), 379-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7495375 AN 96114840 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Changes in serum biochemical and hematological parameters were studied in 20 male rhesus monkeys following acute poisoning by the organophosphate nerve agent cyclohexylmethylphosphonofluoridate (CMPF or GF). Animals were challenged with 5 x LD50 GF (233 micrograms/kg, IM) following pretreatment with pyridostigmine (0.3-0.7 mg/kg per 24 h) and treated with atropine (0.4 mg/kg, IM) and either 2-PAM (25.7 mg/kg, IM) or H16 (37.8 mg/kg, IM) at the onset of clinical signs or at 1 min after exposure. Muscle fasciculations, tremors, or convulsions occurred in 19 of 20 animals. Serum biochemical and hematologic parameters were analyzed 2 days and 7 days after exposure and compared to pre-exposure baseline values. Significant increases in creatine kinase (CK), lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase (ALT) and potassium ion (K+), associated with damage to striated muscle and metabolic acidosis, occurred in both oxime-treated groups 2 days after exposure. Total protein, albumin, red blood cell (RBC) count, hemoglobin concentration (Hb) and hematocrit (Hct), were decreased in both oxime-treated groups at 7 days. The results demonstrate that animals exposed to a single high dose of GF and treated with standard therapy exhibit changes in serum biochemical and hematological indices directly and indirectly associated with their clinical presentations.

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Production, characterization and application of monoclonal antibodies against the organophosphorus nerve agent Vx. Ci Y X; Zhou Y X; Guo Z Q; Rong K T; Chang W B Department of Chemistry, Peking University, Beijing, China Archives of toxicology (1995), 69(8), 565-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8534201 AN 96036122 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Two monoclonal antibodies (Vx-BB8 and Vx-EA11) to the chemical warfare agent Vx were produced and characterized. A competitive inhibition enzyme immunoassay was developed to detect Vx concentrations as low as 3.7 x 10(-7) - 3.7 x 10(-6) mol/l in biological samples. Vx-BB8 400 micrograms given intravenously immediately before 1 x LD95 Vx or 400 micrograms Vx-BB8 intraperitoneally 1.5 h-3 days before 1 x LD95 Vx could protect all the tested mice from death.

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Toxicity of sulphur mustard in adult rat lung organ culture. Sawyer T W; Wilde P E; Rice P; Weiss M T Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada Toxicology (1995 Jun 26), 100(1-3), 39-49. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7542806 AN 95350771 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of the chemical warfare agent sulphur mustard, (bis-(2-chloroethyl)sulphide, HD), was examined in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concentration (LC50) of HD in these cultures was reproducible, and in the microM range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathological examination of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochemically, and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulphur mustard.

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Toxicity of the combined nerve agents GB/GF in mice: efficacy of atropine and various oximes as antidotes. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Canada Archives of toxicology (1994), 68(1), 64-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166607 AN 94219995 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of a combination of isopropyl methylphosphonofluoridate (sarin; GB) and cyclohexyl methylphosphonofluoridate (GF) and the efficacy of various oxime reactivators in combination with atropine against the combined GB/GF challenge were evaluated in mice. The 24-h s.c. LD50 of the GB/GF combination was 1.15 mumol/kg (1.10-1.21; 95% confidence limits). Mice administered GB/GF displayed typical signs of nerve agent poisoning such as tremors and convulsions, with death most likely due to anoxia subsequent to respiratory arrest. The GB/GF LD50 value was comparable to the s.c. LD50 of 1.35 and 1.21 mumol/kg for GF and GB in mice, respectively. Combining the two nerve agents did not result in potentiation of the toxicity. In combination with atropine sulfate (17.4 mg/kg, i.p.), which alone did not reduce mortality, the oximes tested, 2-PAM, obidoxime and HI-6, were all effective when administered 5 min before 3 x LD50 dose of GB/GF with 24-h ED50 values of 102.5, 18.22 and 1.96 mumol/kg, respectively. Use of the GB/GF combination does not appear to confer any unique toxicity profile and appears to be easily treated with the standard therapy of a cholinolytic and oxime.

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Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs. Due A H; Trap H C; Langenberg J P; Benschop H P TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1994), 68(1), 60-3. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166606 AN 94219994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson B W; Kawakami T G; Cone N; Henderson J D; Rosenblatt L S; Goldman M; Dacre J C Department of Avian Sciences, University of California, Davis 95616-5224 Toxicology (1994 Jan 26), 86(1-2), 1-12. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8134917 AN 94182225 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (Tabun, phosphoramidocyanidic acid, dimethyl-, ethyl ester) as part of a program to demilitarize chemical warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only three of the five assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Evaluation of the toxicity, pathology, and treatment of cyclohexylmethylphosphonofluoridate (CMPF) poisoning in rhesus monkeys. Koplovitz I; Gresham V C; Dochterman L W; Kaminskis A; Stewart J R US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425 Archives of toxicology (1992), 66(9), 622-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1482284 AN 93129117 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (CMPF) is an organophosphate cholinesterase inhibitor with military significance. The purpose of these studies was 1) to determine the acute toxicity of CMPF in the male rhesus monkey, 2) to evaluate the efficacy of pyridostigmine (PYR) pretreatment plus atropine and oxime (2-PAM or H16) treatment, and 3) to evaluate the pathological consequences of acute poisoning. An i.m. LD50 of CMPF was estimated using an up-and-down dose selection procedure and 12 animals. The 48-h and 7-day LD50 was 46.6 micrograms/kg, i.m. In the protection experiments, pyridostigmine (0.3-0.7 mg/kg/24 h) was administered by surgically implanted osmotic minipumps for 3-12 days resulting in 21-65% inhibition of erythrocyte acetylcholinesterase activity. Animals were challenged with 5 x L50 CMPF (233 micrograms/kg) and treated with atropine (0.4 mg/kg) and either 2-PAM (25.7 mg/kg) or HI6 (37.8 mg/kg) at the onset of signs or 1 min after challenge. Osmotic pumps were removed within 30 min after agent challenge. Pyridostigmine, atropine, and either 2-PAM or H16 were completely effective against CMPF, saving ten of ten animals in each group. In comparison, three of five animals challenged with 5 x LD50 of soman and treated with atropine and 2-PAM survived 7 days. The primary histologic lesions in the acute toxicity group were neuronal degeneration/necrosis and spinal cord hemorrhage. The CMPF treated groups (total of 20 animals) had minimal nervous system changes with no significant lesion difference resulting from the different oxime therapies. The primary non-neural lesions were degenerative cardiomyopathy and skeletal muscle degeneration which occasionally progressed to necrosis and mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)

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Efficacy of various oximes against GF (cyclohexyl methylphosphonofluoridate) poisoning in mice. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Alta., Canada Archives of toxicology (1992), 66(2), 143-4. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1605730 AN 92296882 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The efficacy of oxime (HI-6, toxogonin or PAM Cl) therapy against GF (cyclohexyl methylphosphonofluoridate) poisoning was assessed in mice. It was found that the combinations of atropine and either toxogonin or HI-6 were effective therapies against GF poisoning. PAM therapy was ineffective. HI-6 was the only oxime which reactivated GF inhibited acetylcholinesterase. This might explain the reason why the HI-6 treated mice appeared to recover more quickly from the incapacitating effects following GF poisoning.

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer T W; Weiss M T; D'Agostino P A; Provost L R; Hancock J R Defence Research Establishment Suffield, Alberta, Canada Journal of applied toxicology : JAT (1992 Feb), 12(1), 1-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1564246 AN 92226402 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chemical warfare activity was subjected to chemical analysis and bioassay. Sarin and several related compounds were confirmed in the soil by capillary column gas chromatography-mass spectrometry (GC-MS); however, the binding of these compounds to the soil hindered quantitation. The chemical results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified standards in chick embryo neuron cultures, a reasonable agreement was found between the chemical and bioassay semi-quantitative estimates of sarin content in the soil extract. Furthermore, the in vitro system appears to offer a sensitive technique for the estimation of sarin remaining bound to the soil following solvent extraction as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy P M; Hansen A S; Hand B T; Boulet C A Defence Research Establishment Suffield, Ralston, Alberta, Canada Toxicology (1992), 72(1), 99-105. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1539175 AN 92169690 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a standard set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI-6 greater than HLo-7 greater than pyrimidoxime. HLo-7 was very effective against tabun poisoning while HI-6 and pyrimidoxime were of moderate value. Against GF, HI-6 and HLo-7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLo-7 to a slightly lesser degree. The other oximes suffered from their lack of effects against one or more of the organophosphates.

[megalomania]

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Aluminum nitride defect chemistry dependence on sintering atmosphere. Chang, E. K.; Kirschner, M. J. BOC Group Technical Cent., Murray Hill, NJ, USA. Journal of Materials Science Letters (1996), 15(18), 1580-1581. CODEN: JMSLD5 ISSN: 0261-8028. Journal; General Review written in English. CAN 125:282600 AN 1996:614771 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 12 refs., of equations explaining theor. relations between aluminum nitride defect chem. and sintering atm.

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Microstructure, chemical reaction and mechanical properties of TiC/Si3N4 and TiN-coated TiC/Si3N4 composites. Huang, Jow-Lay; Lee, Ming-Tung; Lu, Horng-Hwa; Lii, Ding-Fwu. Dep. Material Science Eng., National Cheng-Kung Univ., Tainan, Taiwan. Journal of Materials Science (1996), 31(18), 4899-4906. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:254919 AN 1996:610489 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Silicon nitride contg. various compns. of as-received TiC and TiN-coated TiC, were hot pressed at 1800 C for 1 h in a nitrogen atm. In TiN-coated TiC/Si3N4 composites, TiC reacted first with the TiN coating to form a titanium carbonitride interlayer at 1450 C, which essentially reduced further reactions between TiC and Si3N4 and enhanced densification. TiN-coated TiC/Si3N4 composites exhibited better densification, hardness, flexural strength and fracture toughness than those of as-received TiC/Si3N4. The toughening mechanisms for as-received TiC/Si3N4 and TiN-coated TiC/Si3N4 composite were attributed to crack deflection, load transfer and crack interference by the compressive thermal residual stress.

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Wet chemical synthesis of ZrO2-SiO2 composite powders. Wang, Shi-Wei; Huang, Xiao-Xian; Guo, Jing-Kun. Shanghai Inst. Ceramics, Chinese Academy Sciences, Shanghai, Peop. Rep. China. Journal of the European Ceramic Society (1996), 16(10), 1057-1061. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 125:254896 AN 1996:596753 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of compn. xZrO2(I-x)SiO2, with x = 10, 20, 30 and 40 vol.%, have been prepd. by a wet chem. method using fumed silica and zirconyl chloride as precursors. Thermogravimetric anal. and differential thermal anal. (DTA) show that wt. loss is caused by release of the absorbed water and decompn. of the Zr(OH)4 gels. Gels were heat-treated for 2 h at 500, 700, 900, 1100 and 1350C, and the products examd. using IR spectroscopy. The increasing intensity of the peak at 800 cm-1 in the IR spectra with increasing temp. is attributed to the formation of Si-O-Si bonds among different SiO2 particles, which means that the SiO2 particles grow bigger with increasing temp. The DTA exothermic peak as well as the IR results reveal that the crystn. of tetragonal zirconia (t-ZrO2) begins at about 900C, which is confirmed by x-ray diffraction (XRD). XRD curves also suggest that the silica matrix contributes to the thermal stability of t-ZrO2. The stability of t-ZrO2 is interpreted by the particle-size effect.

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Structure-property relationship of ceramic coatings produced by laser processing. De Hosson, J. Th. M.; Zhou, X. B. Dep. Applied Physics, Univ. Groningen, Groningen, Neth. Materials Research Society Symposium Proceedings (1996), 397(Advanced Laser Processing of Materials--Fundamentals and Applications), 537-542. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:306847 AN 1996:579019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper deals with a well known puzzling observation that wetting in some instances is improved by a chem. reaction between a liq. and a solid substrate in laser processing while in other systems just the opposite effect takes place. Contact angles of liq. Al on SiO2 and liq. Ti on Al2O3 are reported and some results of laser melt injection of SiO2 particles into molten Al. The surface and interface structures were explored by SEM and energy dispersive x-ray spectrometry. According to the exptl. observations, it appears that the vol. change of ceramic substrates during reaction plays a key role in the effect of chem. reaction on wetting.

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Mechanical and thermal properties of SiC-SiC composites made with CVR SiC fibers. Kowbel, W.; Tsou, H. T.; Bruce, C. A.; Withers, J. C. MER Corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1996), 410(Covalent Ceramics III--Science and Technology of Non-Oxides), 417-422. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:202665 AN 1996:502987 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temps. up to 1600C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addn., enhancement of the composite through-the-thickness thermal cond. was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.

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The influence of surface kinetics in modeling chemical vapor deposition processes in porous preforms. Dekker, J. P.; Moene, R.; Schoonman, J. Lab. Appl. Inorg. Chem., Delft Univ. Technol., Delft, Neth. Journal of Materials Science (1996), 31(11), 3021-3033. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65201 AN 1996:378298 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The isothermal chem. vapor infiltration (ICVI) process is a well known technique for the prodn. of composites and the surface modification of porous preforms. Math. modeling of the process can provide a better understanding of the influence of individual process parameters on the deposition characteristics such as final porosity or deposition profiles in the pore network. The influence of different rate expressions for several binary compds. on the ICVI process is discussed. Exptl. work is used to validate the importance of correct kinetic expressions in a continuous ICVI model for cylindrical pores. The predicted infiltration characteristics are compared with exptl. results. The final densification and Thiele modulus, i.e. a no. which is a measure for the diffusion limitations in a pore, are used for the evaluation of the presented model, and conditions are given for an optimal densification of a porous preform by the ICVI process for several binary compds. The deposition profiles as predicted by the model calcns. are in agreement with the exptl. detd. deposition profiles of TiN and TiC in small tubes. Moreover, it can be concluded that the shape of the deposition profiles is detd. by the heterogeneous reaction kinetics. There is only a qual. agreement between the predicted densification and measured densification for the synthesis of TiN and TiB2 in sintered porous alumina. This mismatch can be explained in terms of a complexity of the pore network and differences in reaction kinetics. Model calcns. reveal that there is a scattering for the predicted residual porosity as a function of the Thiele modulus for TiN. Moreover, this Thiele modulus can not fully account for the changes in densification at different temps. Given these uncertainties it is likely that a residual porosity of less than one percent can be obtained if the Thiele modulus is smaller than 1  10-4. However, a CVI process with such a small Thiele modulus will not be practical, because of the concomitant long process times.
Therefore, more precise conditions for the individual process parameters, i.e. concn., reactor pressure, and temp. are deduced from the model calcns.

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Pressure-pulsed chemical vapor infiltration of TiN into SiC particulate preforms. Sugiyama, K.; Sugata, M. Dep. Appl. Chem., Aichi Inst. Technol., Toyota, Japan. Journal of Materials Science (1996), 31(11), 2945-2949. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65198 AN 1996:378286 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC particulate preforms were infiltrated by TiN matrix from a gas mixt. of TiCl4 (5%), nitrogen (30%) and hydrogen using a repeating pressure pulse between 760 and about 1 torr. SiC particle sizes of 5 and 20 m were used. For matrix packing into deep level, optimum temp. was detd. between 800 and 850, and the max. packing ratio reached 67% after 4  104 pulses at 850. The increase of TiCl4 concn. to 10% resulted in higher deposition rate and packing ratio. The decrease of nitrogen concn. led to slower deposition, i.e., a similar effect to temp. lowering. The max. flexural strength measured was 140 MPa.

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Synthesis of mullite coatings by chemical vapor deposition. Mulpuri, Rao P.; Sarin, Vinod K. Dep. Mfg. Eng., Boston Univ., Boston, MA, USA. Journal of Materials Research (1996), 11(6), 1315-1324. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 125:39956 AN 1996:366859 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Formation of mullite on ceramic substrates via chem. vapor deposition was investigated. Mullite is a solid soln. of Al2O3 and SiO2 with a compn. of 3Al2O32SiO2. Thermodn. calcns. performed on the AlCl3-SiCl4-CO2-H2 system were used to construct equil. chem. vapor deposition (CVD) phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were detd. Through process optimization, cryst. CVD mullite coatings have been successfully grown on SiC and Si3N4 substrates. Results from the thermodn. anal., process optimization, and effect of various process parameters on deposition rate and coating morphol. are discussed.

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Mixed chromium and aluminum oxides elaborated by a sol-gel process. I. Chemistry of the preparation. Rezgui, Saloua; Ghorbel, Abdelhamid; Henry, Marc. Lab. Chimie Materiaux Catalyse, Dep. Chimie, Tunisia. Journal of Materials Synthesis and Processing (1995), 3(6), 371-376. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 125:16967 AN 1996:331762 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of mixed chromium and aluminum oxide were prepd. by a sol-gel process. The precursor is a mixt. of Al(O-s-Bu)3 and Cr(acac)3 with a mass ratio Al/Cr = 10 in sec-butanol. Gelation occurred by adding acetic acid. The amt. of added acetic acid is represented by the ratio k = [CH3COOH]/[Al(O-s-Bu)3], with k varying between 0.5 and 3. Acetic acid played crucial roles in both hydrolysis and polycondensation, (1) producing water in situ by esterification, (2) modifying the precursor by substituting some of the O-s-Bu ligands by acetate ligands, and (3) catalyzing the polycondensation. The importance of each of these roles in the process as well as the nature of the products varied with the ratio k.

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Influence of alloying elements on the chemical reactivity between Si-Al-O-N ceramics and iron-based alloys. Vluegels, J.; Vandeperre, L.; Van Der Biest, O. Dep. Metallurgy Materials Eng., Katholieke Univ. Leuven, Leuvan, Belg. Journal of Materials Research (1996), 11(5), 1265-1276. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 124:323490 AN 1996:293140 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. interaction between two '-O' Si-Al-O-N ceramics and a no. of iron-based alloys is studied by means of static interaction couple expts. at 1100 and 1200 C. The onset temp. of reaction of Si3N4 with pure iron was 1095 C, which is in good agreement with a calcd. temp. of 1033 C. During the interaction, silicon and nitrogen from the ceramic dissolve and diffuse into the iron alloy, whereas the remaining aluminum and oxygen form Al2O3 particles. The interaction between the ceramic and iron alloy is reaction controlled. In the initial stage of the interaction, the dissocn. rate of the ceramic is the rate-controlling step. After the ceramic/metal interface is isolated from the furnace atm., the nitrogen soln. rate into the iron alloy becomes rate controlling. The influence of alloying elements on the reactivity could be related to their effect on the nitrogen soly. in the iron alloy. Ni, Si, and C decrease the nitrogen soly. and decrease the reactivity with the Sialon ceramic. Cr and Mo have the opposite effect. The thickness of the interaction layer on the ceramic side of the interaction couple was found to be a function of the calcd. nitrogen soly. in the iron alloy at 1 atm nitrogen pressure, making it possible to predict the relative chem. reactivity of a no. of iron-based alloys with the same Sialon ceramic.

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Preparation and pressureless sintering of chemical vapor deposited SiC-B composite powder. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Institute Materials Research, Tohoku University, Sendai, Japan. Jo
urnal of Materials Science (1996), 31(3), 679-83. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 124:239925 AN 1996:180535 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-B composite powder was prepd. by chem. vapor deposition (CVD) using (CH3)2SiCl2 + B2H6 + H2 as source gases at 1673 K. The powder was -type polycryst. silicon carbide contg. several per cents of boron and carbon. The boron content increased from 0 to 7.7 mass% as the B2H6 gas concn. increased from 0 to 0.7 mol%. Boron and carbon in amorphous form dispersed homogeneously in the -SiC polycryst. particles. The particles were spherical, non-agglomerated and uniform in size with an av. particle size of about 50 nm. Sintering tests were performed with the resulting composite powder without applying pressure. Powder contg. 1 mass% boron and 2 mass% carbon was sintered to a d. of 3.16 x 103 kg m-3 at 2273 K, and the Vickers hardness of the sintered body was 30 GPa. When the sintering temp. was higher than 2323 K, significant grain growth due to the phase transformation from  to  form occurred, which decreased bulk d. and Vickers hardness.

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Nanocrystalline metals, intermetallics, and a metal-matrix nanocomposite by solution-based chemical reductions. Buhro, W. E.; Haber, J. A.; Waller, B. E.; Trentler, T. J.; Suryanarayanan, R.; Frey, C. A.; Sastry, S. M. L. Department Chemistry, Washington University, St. Louis, MO, USA. Polymeric Materials Science and Engineering (1995), 73 39-40. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 124:123490 AN 1996:951 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A metal salt soln. was reduced to nanocryst. and nanocomposite. CuCl in THF was reduced with NaBH4 to form nanocrystal Cu, and Ni and Al can also be prepd. in similar manner. NiCl2 soln. was reduced with LiAlH4 ti NiAl intermetallic compds. of nano size. MoCl5 and SiCl4 were reduced with NaK to nanocryst. MoSi2 in ultrasound field. TiB2 nanocryst. particles were suspended in THF and CuCl was reduced to obtain a Cu-coated TiB2 nanocomposite.

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Preparation of low density free-standing shape of SiC by pressure-pulsed chemical vapor infiltration. Sugiyama, K.; Norizuki, K. Dep. Applied Chem., Aichi Inst. Technology, Toyoda, Japan. Journal of Materials Science Letters (1995), 14(23), 1720-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 124:64057 AN 1995:1000853 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of the conditions of pressure-pulsed chem. vapor infiltration (PCVI) on the deposition rate, ease of substrate oxidn., gross d., and flexural strength in prepn. of low-d. free-standing SiC shapes were examd. By selection of a porous carbon substrate, highly porous SiC shapes with a desirable pore distribution may be prepd. by the PCVI process.

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Identification of chemical and physical change during acid cleaning of ceramics. Johnson, Jessica S.; Erickson, Harold M.; Iceland, Harry. Texas Mem. Mus., Univ. Texas, Austin, TX, USA. Materials Research Society Symposium Proceedings (1995), 352(Materials Issues in Art and Archaeology 4), 831-7. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 124:54897 AN 1995:985335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This report describes the results of two expts. characterizing chem. and phys. change in ceramic constituents occurring from acid solns. commonly used to remove deposits from the surface of archaeol. ceramics. The first examines the chem. effects of hydrochloric acid, in an attempt to identify the yellow color, commonly known as "acid burn", often seen in museum collections on black-on-white sherds found in the Southwestern U.S. The compd. is identified as Fe2O3H2O. The second study compares the phys. effects of different acids on a group of Maya sherds. All acids tested in this study were found to cause phys. damage.

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Influence of particle characteristics on sintering behavior of alumina-zirconia composites. Balasubramanian, M.; Malhotra, S. K.; Gokularathnam, C. V. FRP Research Center, Indian Inst. of Technology, Madras, India. Journal of Materials Science Letters (1995), 14(21), 1484-5. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:347792 AN 1995:927403 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A uniform distribution of zirconia particles in an alumina matrix can be achieved by chem. processing methods. Three chem. processing routes were used to obtain better powders. The sintered d. and the tetragonal ZrO2 content of composites were correlated with powder size and morphol.

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Wet air oxidation of energetics and chemical agent surrogates. Copa, William M.; Momont, Joseph A. Zimpro Environmental Inc., Rothschild, WI, USA. Journal of Energetic Materials (1995), 13(3&4), 235-58. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295590 AN 1995:895724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Wet oxidn. studies have been conducted on a no. of energetic materials and wastewaters derived from energetic materials to demonstrate high destruction levels of specific energetic components. Triple-base propellant, OTTO Fuel (used as torpedo propellant) and hydrazine-based rocket fuel were energetics of interest. Triple-base propellant contain nitrocellulose, nitroglycerin, and nitroguanidine. OTTO Fuel contains substantial amts. of propylene glycol trinitrate. Hydrazine based rocket fuel contains hydrazine and 1,1-di-Me hydrazine (asym. di-Me hydrazine or UDMH). A bench scale wet air oxidn. study on alk. hydrolyzates of triple-base propellants indicated that essentially complete destruction of the reactive nitrogen components could be achieved at an oxidn. temp. of 280. Bench scale wet air oxidn. studies on OTTO Fuel wastewaters indicated that a >99% destruction of propylene glycol dinitrate can be achieved at 280. Processing OTTO Fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved even higher destruction levels. Bench scale wet air oxidn. studies on hydrazine-based rocket fuel wastewaters indicated that a 99.8% destruction of hydrazine and a >99.0% destruction of 1,1-dimethylhydrazine can be oxidized at 280. Again, processing of hydrazine-based rocket fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved similar destruction levels. The application of wet air oxidn. for the destruction of chem. agents has been made by the extrapolation of data from the wet air oxidn. of compds. with similar chem. structures or of surrogate compds. Sarin and V-agents are nerve agents which have an organo-phosphorus structure similar to that of contain commonly used pesticides. Pesticides such as glyphosate and malathion, which have a similar organo-phosphorus structure, are essentially completely destroyed (>99% destruction) by wet air oxidn. at 200-280. The chem. agent surrogate, di-Me Me phosphonate (DMMP) was wet air oxidized at 220-280. Alk.
hydrolyzed DMMP was wet air oxidized at 280. All of the oxidized effluents showed a >97.5% destruction efficiency for the DMMP. The blister agent, mustard (HD) is a chlorinated sulfide, bis(2-chloroethyl) sulfide. Org. sulfides such as mercaptans can be destroyed by wet air oxidn. at 260-280. It is concluded that the wet air oxidn. process is a promising alternative to incineration for disposal of energetics and chem. warfare agents.

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Molten salt oxidation of chemical munitions. Stewart, Albert; Schnittgrund, Gary. PyroPacific Processes, Grand Hills, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 213-34. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295589 AN 1995:895723 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molten salt oxidn. is reviewed as a potential near term alternative technol. for the destruction of chem. agents. Initial tests completed by the US Army in 1975 showed the promise of achieving very high removal efficiencies on actual agents. Recent testing by DOE has verified the potential for very low PIC and dioxin or furan releases. To further explore the possible application of this technol. to chem. agent destruction, a molten salt reactor and assocd. equipment was designed to process a nominal 50 kg/h of Sarin. Mass and energy balances are presented for process conditions representing a range of molten salt potential operational modes and schemes for enhancing plant capacity. Process economics are presented.

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Supercritical water oxidation of chemical agents, and solid propellants. Spritzer, M. H.; Hazlebeck, D. A.; Downey, K. W. San Diego, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 185-212. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295588 AN 1995:895722 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Supercrit. water oxidn. (SCWO), also referred to as hydrothermal oxidn. (HTO), is a developing technol. for the destruction of hazardous and nonhazardous wastes. SCWO destroys combustible materials using an oxidant in water at 350-600 and pressures of 17 MPa. General Atomics and its subcontractors are currently conducting 2 comprehensive research and demonstration programs geared toward the destruction of Department of Defense (DoD) wastes utilizing SCWO technol. Wastes of primary interest include chem. agents and solid propellants. Tech. challenges, particularly corrosion and solids handling, were overcome, and the destruction of chem. agents and solid propellants was demonstrated on a bench scale. SCWO results for chem. agents show destruction and removal efficiencies for GB, VX, and mustard agents to be in excess of 99.9999%, limited only by detection capability. SCWO results for hydrolyzed Class 1.1 solid propellant show destruction and removal efficiencies for total org. carbon (TOC) of >99.9%. Design and fabrication of a transportable SCWO pilot plant for chem. warfare agents, propellants and other DoD hazardous wastes and a prototype HTO system for solid rocket propellant disposal are complete and demonstration testing is underway.

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Pressure pulsed chemical vapor infiltration of SiC to two-dimensional-Tyranno/SiC-C preforms. Sygiyama, Kohzo; Yoshida, Yazutoshi. Department of Applied Chemistry, Aichi Institute of Technology, Toyoda, Japan. Journal of Materials Science (1995), 30(20), 5125-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:320390 AN 1995:894944 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preforms of two-dimensional Tyranno fiber (SiC base) of 7  20  1.3 mm3 were chem. vapor infiltrated with SiC at 850-1050C from a gas mixt. of CH3SiCl3 (6%)-H2 using pressure pulses between below 0.3 kPa and 0.1 MPa. Above 900C, films grew on the macrosurface dominantly. At 850C, residual porosity decreased to about 10% after 105 pulses, and three point flexural strength reached about 200 MPa. X-ray diffractograms on the surface showed the deposits to be -SiC only.

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Matrix characterization of fiber-reinforced SiC matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M.; More, K. L.; Sheldon, B. W.; Besmann, T. M.; Headinger, M. H.; Davis, R. F. Oak Ridge National Laboratory, Oak Ridge, TN, USA. Journal of Materials Science (1995), 30(17), 4279-85. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:206673 AN 1995:804167 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ceramic matrix composites (CMCs), that consist of silicon carbide (SiC) reinforced with continuous Nicalon or T-300 fibers, are being developed for many high-temp. structural applications. The large potential use of CMCs has prompted an in-depth investigation and characterization of these materials. Electron microscopy and micro-Raman spectroscopy were used to characterize and compare the SiC matrix crystal structure and morphol. of composite materials fabricated by two different chem. vapor infiltration (CVI) processes.

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Characterization of pseudo-porous SiC/C coatings on NextelTM 440 and NicalonTM fibers. Khasgiwale, N. R.; Butler, E. P.; Tsakalakos, L.; Hensley, D. A.; Cannon, W. R.; Danforth, S. C.; Gonczy, S. T. Center Ceramic Research, Rutgers University, Piscataway, NJ, USA. Materials Research Society Symposium Proceedings (1995), 365 395-400. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177329 AN 1995:774261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Pseudo-porous SiC/C coatings were deposited on NextelTM 440 and NicalonTM fibers by CVD. The morphol. and chem. of the coatings was evaluated, both before and after oxidn., using SEM, X-Ray Diffraction Anal. (XRD), XPS and Auger spectroscopy. Coated fibers were subjected to two different oxidn. treatments to assess coating stability: a) oxidn. at 600C for 20 h, and b) oxidn. at 1000C for 20 h. Pseudo-porous SiC/C on NicalonTM fibers appear to be more oxidn. resistant than the same coatings on NextelTM440 fibers.

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The preparation and economics of silicon carbide matrix composites by chemical vapor infiltration. Roman, Yvette G.; Stinton, David P. Centre Technical Ceramics-TNO, Eindhoven, Neth. Materials Research Society Symposium Proceedings (1995), 365 343-50. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 123:176964 AN 1995:774254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 35 refs. A no. of processing techniques that are currently in use for the development and prodn. of continuous fiber reinforced ceramic composite materials are described. The limited no. of available processing routes are compared with respect to the resulting material properties. The chem. vapor infiltration (CVI) technique is one of the most extensively developed methods. During the last decade, at least five different modifications of the isobaric isothermal CVI principle have been developed; each route having its own benefits. CVI techniques have now been developed to the extent that industrial commercialization is being realized. Projected cost aspects of the various CVI manufg. techniques are examd. and compared.

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Properties of SiC-SiC composites produced using CVR converted graphite cloth to SiC cloth. Kowbel, W.; Kyriacou, C.; Gao, F.; Bruce, C. A.; Withers, J. C. MER corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1995), 365 197-202. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177312 AN 1995:774236 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a new SiC reinforcement based upon a conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. This new SiC filaments exhibit an excellent creep resistance at temps. up to 1600C. Several SiC-SiC composites were fabricated using graphite fabric converted to SiC fabric utilizing the CVR process combined with a slurry infiltration and CVI densification. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites are discussed.

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Chemically bonded ceramic matrix composites: densification and conversion to diffusion bonding. Johnson, Bradley R.; Guelguen, Mehmet A.; Kriven, Waltraud, M. Department Materials Science and Engineering, University Illinois, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1995), 365 67-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177295 AN 1995:774216 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC's). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl2O4) powders were used as the chem. bonding matrix phase, while calcia-stabilized zirconia powders were the second phase material. Samples contg. up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal anal. (DTA/TGA). The phys. characteristics of this novel CMC were characterized by hardness, d., and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD.

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Oxidative catalytic decomposition of toxic gases using hydroxyapatite and fluorhydroxyapatite. Palucka, Timothy P.; Eror, Nicholas G.; McNamara, Thomas A. Department Materials Science and Engineering, University Pittsburgh, Pittsburgh, PA, USA. Materials Research Society Symposium Proceedings (1995), 368(Synthesis and Properties of Advanced Catalytic Materials), 275-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:151604 AN 1995:734790 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An oxidative catalytic route to decomp. nerve gases was studied using hydroxyapatite (HA, Ca10(PO4)6(OH)2) and its partially fluorinated analog fluorhydroxyapatite (FHA, Ca10(PO4)6Fx(OH)2-x). Samples were prepd. with surface areas of 34-238 m2/g to study surface area effects; 1.2 wt.% Pt was deposited on 1 substrate to study the effect of a transition metal on activity and selectivity. Reaction studies were performed using di-Me methylphosphonate, a nerve gas simulant, in a stream of 80% N and 20% O at 573 K and atm. pressure. High surface area FHA samples showed an increase in the protection period (period of 100% conversion) with increasing F substitution; such an increase was not seen for low surface area FHA samples. In the absence of Pt, the reaction products were CH3OH and di-Me ether; with Pt, CO2 was also obtained.

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Toxicity of sulfur mustard in adult rat lung organ culture. Sawyer, Thomas W.; Wilde, Paul E.; Rice, Paul; Weiss, M. Tracy. Medical Countermeasures Section, Defence Research Establishment Suffield, Box 4000, Medicine Hat, Alberta, Can. Toxicology (1995), 100(1-3), 39-49. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 123:104668 AN 1995:700024 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The toxicity of the chem. warfare agent sulfur mustard, (bis-(2-chloroethyl)sulfide, HD), was examd. in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concn. (LC50) of HD in these cultures was reproducible, and in the M range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathol. examn. of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochem., and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulfur mustard.

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Characterization and surface chemistry of uncoated and coated silicon nitride powders. Schmidt, H.; Nabert, G.; Ziegler, G.; Goretzki, H. Inst. Materialforschung, Univ. Bayreuth, Bayreuth, Germany. Journal of the European Ceramic Society (1995), 15(7), 667-74. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 123:90766 AN 1995:695131 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various Si3N4 powders, produced by different procedures, were characterized by imaging (TEM) and anal. methods (EDS, FT-IR, XPS) in the as-received state as well as after doping with a metal oxide (MgO). For the doping, an alternative procedure to the usual methods was applied based on sol. organometallic compds. Anal. TEM combined with lateral resoln. element anal. and XPS measurements was used for morphol., structural and anal. characterization. The distribution of the dopant was deduced from measurements of XPS sputter depth profiles. These investigations were supplemented by FT-IR measurements to det. qual. and semi-quant. the reactive groups on the particle surfaces of the as-received powders. For comparison, measurements were performed with Si3N4 powders which were doped by the above chem. procedure and by mech. mixing. The results of the various characterization methods are interpreted in the form of a model display for surface reactions of organometallic doping reagents on the surfaces of ceramic particles. The results show that Si3N4 powders with high concn. of OH groups on their particle surface reveal very good distribution of the fluxing element (layer-like coating).

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Influence of crystallographic orientation, chemical inhomogeneities, material transport anisotropy and elastic strain energy on the migration of grain boundaries in chromium-doped alumina during internal reduction. Backhaus-Ricoult, Monika; Peyrot-Chabrol, A.; Chiron, R.; Hagege, S. Cent. d'Etudes Chim. Metall., CNRS, Vitry, Fr. Materials Research Society Symposium Proceedings (1995), 357(Structure and Properties of Interfaces in Ceramics), 293-9. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:90732 AN 1995:685875 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Diffusion-induced grain boundary migration is obsd. during internal redn. of chromium-doped alumina. It occurs because grain boundary diffusion is fast compared to lattice diffusion of oxygen. The oxygen chem. potential relaxes between grain boundaries and adjacent grains. Migration to either side of the boundary is controlled by multiple factors: chem. compn. differences between adjacent grains, elastic strain energy differences on the two sides of the boundary plane or by more rapid oxygen relaxation when the c-axis of a grain is perpendicular to the boundary plane.

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Synthesis and chemical stability of NaSn2P3O12. Breval, E.; Harshe, G.; Agrawal, D. K.; Limaye, S. Y. Intercoll. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Journal of Materials Science Letters (1995), 14(10), 728-31. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:39204 AN 1995:606064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

NaSn2P3O12 and NaZr2P3O12 powders were prepd. by solid-state reaction methods and sintered at 1050-1200. The resulting pellets were characterized in terms of d., thermal expansion, and phase compn. before and after chem. stability tests. Chem. stability tests were performed in polethylene containers in 3 solns., H+ + SO42- (pH = 0.5), Na+ + H+ + SO42- (pH = 0.7), and Na+ + OH- (pH + 14.3). Results indicate that NaSn2P3O12 is a very stable NZP compd. in high and low pH solns. (pH + 0.5-14.3) as compared to the parent compn. NaZr2P3O12, which shows high losses, esp. in alk. leachants. The surface-to-vol. of a single phase NaSn2P3O12 material, sintered without sintering agents, hardly affects the dissoln. Use of a sintering agent may result in a highly reactive grain boundary phase, the amt. of which may exceed the amt. of added sintering aid.

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Low-level detection of chemical agent simulants in meat and milk by ion trap mass spectrometry. Buchanan, Michelle V.; Hettich, Robert L.; Xu, Jing Hai; Waters, Larry C.; Watson, Annetta. Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Building 5510, MS/6365, Oak Ridge, TN, USA. Journal of Hazardous Materials (1995), 42(1), 49-59. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 123:31526 AN 1995:596587 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. methods for the detection of two chem. warfare agent simulants, diisopropyl methylphosphonate and chloroethylethylsulfide, in beef tissue and milk were demonstrated to be effective to levels as low as 50-100 ppb. These methods are based upon thermal desorption into an ion trap mass spectrometer. Selective detection of the target compds. is achieved by isobutane chem. ionization in combination with collision-induced dissocn., which yields characteristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limits achieved with this method suggest that it may be possible to take small tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the anal. In addn., because the new methods may be performed more quickly than conventional methods requiring substantial sample prepn. and anal. time, more samples could be analyzed.

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The effect of ceria co-doping on chemical stability and fracture toughness of Y-TZP. Boutz, M. M. R.; Winnubst, A. j. a.; Van Langerak, B.; Scholtenhuis, R. J. M. Olde; Kreuwel, K.; Burggraaf, A. J. Faculty of Chemical Technology, University of Twente, Enschde, Neth. Journal of Materials Science (1995), 30(7), 1854-62. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 122:271892 AN 1995:504770 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and ageing resistance of yttria, ceria-stabilized tetragonal zirconia polycrystals (Y, Ce-TZP) were evaluated as a function of grain size and ceria content. Very fine grained, fully dense materials could be produced by sinter forging at relatively low temps. (1150-1200C). The aging resistance in hot water (185C) of 2 mol% Y2O3-stabilized TZP is strongly enhanced by alloying with ceria. The ceria content necessary to avoid degrdn. completely, decreases with grain size. The toughness of fully dense Y, Ce-TZP is 7-9 MPa m1/2 for grain sizes down to 0.2 m. No or very little transformation took place during fracturing and no clear variation with grain size was obsd. for the toughness at grain sizes up to 0.8 m. Reversible transformation and crack deflection may explain the obsd. toughness values.

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Microstructure and chemistry of second phases in MgO- and NiO-codoped alumina by analytical transmission electron microscopy. Park, K.; Vasilos, T.; Sung, C. Cent. Advanced Materials Dep. Chem. Nuclear Eng., Univ. Massachusetts, Lowell, MA, USA. Journal of Materials Science Letters (1995), 14(4), 261-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 122:167982 AN 1995:415637 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects MgO-NiO-codoping on microstructure and chem. of 2nd phases, segregated particles and cryst. defects in alumina ceramics were examd. MgO-NiO-codoping contributed significantly to the prepn. of dense fine-grained alumina. It appeared that Ni-Al and Ni-Mg-Al spinels, segregated Ni particles, and K-'' alumina ppts. were formed at triple points or at grain boundaries, because the concns. of the MgO and NiO dopants were higher than their solid solubilities. In particular, the codopants formed a Ni-Mg-Al spinel as well as a Ni-Al spinel, because Mg2+ and Ni2+ were partitioned in the cation position of the spinel structure.

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Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry. Bentley, J.; Horton, L. L.; McHargue, C. J.; McKernan, S.; Carter, C. B.; Revcolevschi, A.; Tanaka, S.; Davis, R. F. Metals and Ceramics Div.r., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1994), 332(Determining Nanoscale Physical Properties of Materials by Microscopy and Spectroscopy), 385-90. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:87360 AN 1995:266442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resoln. of <5 nm. Anal. of Fe L23 white lines indicates a low-spin state with a charge transfer of .apprx.1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2-5% in the Co:O stoichiometry were measured across 100-nm-thick Co3O4 layers in an oxidized directionally solidified CoO-ZrO2 eutectic, with the highest O levels near the ZrO2. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for Co3O4 have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid soly. occurred in an AlN-SiC film grown by low-temp. mol. beam epitaxy (MBE) on (6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycryst. AlN on SiC, interfacial 8H Sialon (aluminum silicon oxynitride) and pockets of Si3N4-rich '-Sialon in the SiC were detected.

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Chemically bonded ceramics as an alternative to high temperature composite processing. Gulgun, Mehmet A.; Johnson, Bradley R.; Kriven, Waltraud M. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1994), 346(Better Ceramics through Chemistry VI), 511-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:15230 AN 1995:174876 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Processing of multi-phase ceramic composite materials using chem. bonded ceramics as a binding agent appears to be a promising route for fabricating complex-shaped structures. In a zirconia-calcium aluminate ceramic matrix composite, the hydraulic property of fine, monocalcium aluminate (CaAl2O4) powders was used to prep. strong prefired bodies. The changes in the phys. characteristics of the composite during the conversion from a chem. bonded compact into a sintered composite were studied using thermogravimetric analyses (TGA), X-ray diffraction and SEM. The d. and the hardness of the chem. bonded and sintered composite were measured.

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Assessing delayed neurotoxicity in rodents after nerve gas exposure. Husain, K.; Pant, S. C.; Vijayaraghavan, R.; Singh, Ram. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(2), 161-4. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:294553 AN 1994:694553 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Delayed neurotoxicity of an organophosphorus nerve gas, Sarin (a chem. warfare agent) following repeated inhalation exposure in rats and mice, was studied by behavioral, biochem. and histopathol. analyses. Rats exposed to Sarin aerosols (12.5 mg/m3 for 20 min) daily for ten days did not exhibit any clin. sign of delayed neurotoxicity. Neurotoxic esterase (NTE) activity in the brain, spinal cord and platelets was significantly inhibited, but the inhibition was below the threshold. Histopathol. examn. of spinal cord did not show any axonal degeneration. Mice exposed to Sarin aerosols (5 mg/m3 for 20 min) daily for ten days developed mild ataxia and muscular weakness of the hind limb on 14th day after the start of exposure. NTE activity was significantly inhibited in brain, spinal cord and platelets. Histopathol. of spinal cord showed focal axonal degeneration. Acetyl-choline esterase activity in the platelets of both the animals was significantly inhibited. The authors conclude that mice are sensitive to delayed neurotoxicity induced by repeated exposure to Sarin whereas rats are insensitive.

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Clean-up of chemical warfare agents on soils using simple washing or chemical treatment processes. Amos, Denys; Leake, Brian. DSTO, Aeronautical and Maritime Research Laboratory, P.O. Box 4331, Melbourne, Victoria, Australia. Journal of Hazardous Materials (1994), 39(1), 107-17. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:262645 AN 1994:662645 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several simple processes have been studied for the destruction of chem. agents, Soman and Mustard, on soils. A double wash or an extended single wash with water was effective in removing Mustard and Soman from soil; addn. of either anionic or cationic surfactant did not improve removal efficiency. Soils with higher org. carbon content were more difficult to decontaminate. The most effective chem. process for the removal of Mustard was treatment with hypochlorite; treatment with Na2CO3 or NaOH were almost as effective as hypochlorite in cleaning Mustard contaminated soil. Soman was removed most effectively by treatment with Na2CO3. Overall the most efficient process for the destruction of both Mustard and Soman was treatment with Na2CO3 soln.

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Liquid phase sintering, electrical conductivity, and chemical stability of lanthanum chromite doped with calcium and nickel. Christie, G. M.; Middleton, P. H.; Steele, B. C. H. Dep. Mater., Imperial Coll. Sci., Tech. Med., London, UK. Journal of the European Ceramic Society (1994), 14(2), 163-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:236480 AN 1994:636480 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The substitution of 10 mol% nickel for chromium in calcium-doped lanthanum chromite has been shown to promote rapid densification of the compd. at low temps. in air by the form of a transient liq. phase. Liqs. were generated via the decompn. of CaCrO4 second phase material present in calcined powders. During elec. cond. measurements at 1000C, severe microstructural degrdn. occurred at atms. of H2 and CO2. The processes leading to chem. degrdn. are attributed to the pptn. of Ni from the (La,Ca)(Cr,Ni)O3 solid soln. and to the decompn. of small amts. of residual CaCrO4 which remains at grain boundaries and triple points after sintering. DTA studies on CaCrO4 in CO2 and H2 atms. suggested that the degrdn. due to CaCrO4 decompn. was primarily a result of the reaction of CaO with CO2 to form CaCO3. The presence of H2 gas is thought to catalyze this reaction via the formation of large amt. of CaO during the decompn. of CaCrO4. Degrdn. is more severe in atms. contg. a mixt. of CO2 and H2 gases than in either gas on its own.

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Photochemical degradation of a toxic organophosphorus analog (PMSF) in microemulsion media. Yang, Yun; Donegan, Sheila; Patel, Ramesh C.; Ward, Anthony J. I. Center for Advanced Materials Processing, Clarkson University, Potsdam, NY, USA. Chemosphere (1994), 28(11), 1967-76. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 121:217331 AN 1994:617331 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A study has been made of the photodegrdn. of an analog, phenylmethylsulfonyl fluoride (PMSF), of a toxic chem. warfare agent. The agent was solubilized in a water-in-oil surfactant stabilized microemulsion system comprising sodium dodecyl sulfate, pentanol and water. Loss of the parent PMSF mol. upon exposure of the system to UV irradn. was monitored by 19F NMR spectroscopy. Consideration of the changes in the chem. shifts, splittings in conjunction with GC/Mass spectroscopy data strongly suggest the degrdn. leads to partial fluorination of pentanol. Anal. of peak areas also indicates the formation of volatile degrdn. products such as HF. The addn. of TiO2 or hydroquinone to the system did not appreciably change the overall amts. of degrdn. The results are interpreted in terms of the possible radical based reaction pathways and show that such a microemulsion medium to have significant potential as a vehicle for effecting such a degrdn. process.

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Comparative evaluation of high protein against normal protein diet in combination with carbamates against organophosphorus intoxication in rats. Chatterjee, A.K.; Sikder, Nirmala; Sikder, A.K. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(1), 11-14. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:197892 AN 1994:597892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The relative efficacy of an isocaloric high protein diet (HPD) contg. 59 per cent protein, in comparison to a conventional diet contg. 21 per cent protein, as applied in the alleviation of toxicity of diisopropyl phosphorofluoridate (DFP) and Me iso-Pr phosphonofluoridate (sarin), has been reported. In combination with well-known prophylactics like carbamates and cholinolytics like atropine against nerve gas toxicity, HPD appears to be superior to the conventional diet as studied by survival time measurements. Apart from carbamates, atropine and mecamylamine, HPD may be treated as an addnl. prophylactic agent to guard against the toxicity of DFP and sarin, which are being used as war chems.

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The surface chemistry of silicon nitride powder in the presence of dissolved ions. Hackley, V. A.; Malghan, S. G. Ceram. Div., Natl. Inst. Standards and Technol., Gaithersburg, MD, USA. Journal of Materials Science (1994), 29(17), 4420-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 121:185440 AN 1994:585440 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Colloidal processing of silicon nitride (Si3N4) powders depends largely on the control of reactions at the solid-soln. interface. The role of dissolved ions in the surface chem. of Si3N4 powders has been investigated, and the implications of these results for the effects of impurities, contaminants and additives in processing are discussed. The interaction of ions at the solid-soln. interface was characterized by particle electrokinetic behavior detd. from electroacoustic measurements in moderately concd. suspensions. Ions were classified according to chem. similarity and surface specificity. Specific adsorption was inferred from the movement of the isoelec. point relative to the endemic "native" value. Most simple univalent electrolytes behaved indifferently towards the Si3N4 surface, with the exception of fluoride which specifically adsorbed and may have formed a strong complex with surface silicon sites. The alk.-earth cations exhibited a similar weak specificity. In the presence of hydrolyzable transition metal cations, powder surface chem. was controlled by the adsorption of hydroxy metal complexes and by the soly. of a surface-pptd. metal hydroxide phase. Oxo anions, such as sulfate and carbonate, adsorbed specifically on the Si3N4 surface, but the interactions were weaker than previously obsd. on metal oxide surfaces.

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X-ray photoelectron spectroscopy of uv laser irradiated sapphire and alumina. Pedraza, A. J.; Park, J. W.; Meyer, H. M., III; Braski, D. N. Dep. Materials Science Engineering, Univ. Tennessee, Knoxville, TN, USA. Journal of Materials Research (1994), 9(9), 2251-7. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 121:162453 AN 1994:562453 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

XPS was performed in as-received, thermally annealed, and laser-irradiated sapphire and alumina specimens to study the effects of the different treatments on surface chem. and properties. Laser irradiations with a 308 nm wavelength laser were performed in air and in a reducing atm. consisting of a mixt. of Ar and 4% hydrogen. The at. percentages of carbon, aluminum, and oxygen were measured in all the specimens. Particular attention was paid to the percentages of oxygen in the oxide and in a hydroxyl state. The XPS analyses clearly established that a very thin film of metallic aluminum is formed on the surface of both alumina and sapphire substrates when they are irradiated under a reducing atm. However, the film is discontinuous because it is elec. insulating. Substrates irradiated in air have metallic aluminum only for fluences below 0.4 J/cm2. The valence band photoemission spectra of as-received, annealed, and laser-irradiated specimens were measured. In irradiated specimens, the width of the valence band spectra was found to decrease by .apprx.10%. One possible cause of this decrease is the generation of point defects during laser irradn. Electroless copper deposition occurs on sapphire and alumina substrates if their surface has been activated by laser irradn. The time required for copper deposition was monitored by measuring the elec. resistivity in the irradiated area while the substrates were immersed in an electroless bath. The kinetics of deposition on laser-activated substrates and the XPS results show that the presence of metallic aluminum accelerates the deposition process. However, the presence of aluminum is not the sole reason for laser activation in alumina. Very strong metal-ceramic bonding is produced after thermal annealing of samples having preirradiated substrates. This result is explained in terms of the excess oxygen that is present at the ceramic surface after irradn.

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X-ray absorption spectroscopy study of the local structure and the chemical state of yttrium in polycrystalline -alumina. Loudjani, M. K.; Cortes, R. Lab. Metallurgie Structurale, CNRS, Orsay, Fr. Journal of the European Ceramic Society (1994), 14(1), 67-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:162396 AN 1994:562396 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. state and local structure around the yttrium ion in doped polycryst. -alumina (0.03  mol% Y2O3  1) system was examd. by extended x-ray absorption fine structure (EXAFS) measurements for yttrium K-edge energy. In the case of highly doped alumina samples (0.1 and 1 mol% Y2O3) most of the yttrium is pptd. as a Y3Al5O12 phase, whereas in the dil. doped alumina sample (0.03 mol% Y2O3) yttrium is in solid soln., being located on the octahedral aluminum sites. The yttrium ion size, comparatively greater than that of the aluminum ion, induces locally a significant distortion of the oxygen ion lattice. This effect creates point defects in the nearest neighbor shell of the yttrium: vacancy (Vo..) and interstitial (Oi'') oxygen point defects.

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Constitution of the -alumina phase in chemically produced mullite precursors. Schneider, H.; Voll, D.; Saruhan, B.; Schmucker, M. Inst. Mater. Res., German Aerosp. Res. Establ., Cologne, Germany. Journal of the European Ceramic Society (1993), 13(5), 441-8. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:89568 AN 1994:489568 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The temp. development of type II mullite precursor powders have been studied in the temp. range of 150C (as-received) and 1150C. X-ray diffraction measurements, IR and 29Si and 27Al NMR spectroscopy and anal. transmission electron microscopy have been performed on the heat-treated precursors. The investigations had the aim of contributing to the frequently discussed question, whether Si is incorporated into the -alumina spinel being formed as a transient phase in type II mullite precursors. The as-received precursors consist of relatively large spherical particles ( 05 m) of noncryst. SiO2 and of much finer-grained agglomerates of pseudo-boehmite crystals (-AlO(OH),  20 nm), which are embedded in a SiO2 matrix. Above 350C, pseudo-boehmite transforms to spinel-type alumina (-Al2O3). During this transformation, all Si existing in the SiO2 matrix of the pseudoboehmite agglomerates is incorporated into -Al2O3 corresponding to a SiO2 content of 12 mol% at 500C. Up to 750C, the SiO2 content of the -alumina remains const. but above this temp. it gradually rises and reaches a max. amt. of 18 mol% at 1150C. A marginal decompn. of the spherical non-cryst. SiO2 particles may be the sources to provide diffusion of Si species into the -alumina during a temp. increase above 750C. It is most likely that Si species diffuse into the -alumina crystals along the crystallite boundaries. The diffusion process and Si incorporation are facilitated with the temp. increase.

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Quantitative analysis of Si3N4 microstructure response on interface chemistry. Meissner, E.; Unger, S.; Kleebe, H.-J.; Ziegler, G. Univ. Bayreuth, Bayreuth, Germany. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 471-5. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:89560 AN 1994:489560 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. microstructure anal. was performed on gas-pressure sintered Si3N4 materials (SSN) by employing an image processing system. Variations in grain-diam. distribution and aspect-ratio distribution with changing additive compn. and annealing time, resp., were investigated. Clear evidence was found that both interface compn. and post-sintering anneal can strongly affect the matrix grain morphol. For the Y2O3-doped material, extended annealing time supported the formation of Si3N4 grains with increased diam. and length via Ostwald ripening. Moreover, the aspect-ratio distribution was shifted to higher values indicating anisotropic grain growth. The addn. of Al2O3 + ZrO2, compared to SSN doped with Y2O3, resulted in a finer microstructure with still high aspect ratios. This chem. effect is closely related to the viscosity of the liqs. at processing temps. Furthermore, ZrO2 addn. results in a more pronounced transgranular fracture mode, while Y2O3-contg. SSN predominantly revealed intergranular fracture. The influence of annealing time and interface chem. on both microstructure evolution and resulting fracture toughness is discussed.

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Surface chemical interactions of Si3N4 with polyelectrolyte deflocculants. Hackley, V.A.; Premachandran, R.; Malghan, S.G. Mater. Sci. Eng. Lab., Natl. Inst. Stand. Technol., Gaithersburg, MD, USA. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 679-82. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:41008 AN 1994:441008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interaction of org. polyelectrolyte deflocculants at the Si3N4 solid-soln. interface was investigated using electroacoustic measurements, polymer adsorption and particle size distribution anal. One cationic and two anionic polymers were studied: quaternized poly(diamine epoxychlorohydrin), ammonium poly(methacrylate) and poly(acrylic acid), resp. Electrostatic interactions are emphasized as a function of pH, concn. and mol. wt.

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Metabolite pharmacokinetics of soman, sarin and GF in rats and biological monitoring of exposure to toxic organophosphorus agents. Shih, Ming L.; McMonagle, Joseph D.; Dolzine, Theodore W.; Gresham, Vincent C. US Army Med. Res. Inst. Chem. Def., Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1994), 14(3), 195-9. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 121:28848 AN 1994:428848 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study reports on the pharmacokinetics of the elimination of the metabolites of three toxic organophosphorus compds. (soman, sarin and GF). Urine, blood and lung tissue were collected from rats dosed s.c. at 75 g kg-1. Urinary excretion of the metabolite was the major elimination route for these three compds. The major differences among them were primarily the extent and rate of excretion. The hydrolyzed form, alkylmethylphosphonic acid, was the single major metabolite formed and excreted in urine by a non-saturable mechanism. Nearly total recoveries of the given doses for sarin and GF in metabolite form were obtained from the urine. The terminal elimination half-lives in urine were 3.7  0.1 and 9.9  0.8 h for sarin and GF, resp. Soman metabolite showed a biphasic elimination curve with terminal half-lives of 18.5  2.7 and 3.6  2.2 h. Soman was excreted at a slower rate with a recovery of only 62%. Lung was the major organ of accumulation for soman. In blood the toxic agents were concd. more in red blood cells than in plasma. The acid metabolites can serve as a better chem. marker for monitoring organophosphorus exposure in humans via their higher concn. and longer half-life in urine than the parent compds.

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Movement of chemical warfare agent simulants through porous media. Jenkins, R. A.; Buchanan, M. V.; Merriweather, R.; Ilgner, R. H.; Gayle, T. M.; Watson, A. P. Analytical Chemistry Division, Oak Ridge National Laboratory, Building 4500S, MS-6120, P.O. Box 2008, Oak Ridge, TN, USA. Journal of Hazardous Materials (1994), 37(2), 303-25. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:16666 AN 1994:416666 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A measurement protocol is documented and data are presented to characterize the permeation of chem. warfare agent simulants through the porous construction materials brick, cinder block, gypsum wall board, and wood. These data will be used to develop guidelines for access ("reentry") to potentially contaminated properties if nerve or vesicant agents are released during any phase of the US Department of the Army's Chem. Stockpile Disposal Program. A novel permeation cell design allowed sampling of air vols. adjacent to the spiked face, breakthrough face, and lateral face of each test medium at two temps. Simulant movement through wood is nearly always in the direction of the wood grain. Two-dimensional breakthrough was obsd. in brick and gypsum wall board. The sulfur mustard simulant broke through all test media in less than 60 min; nerve agent simulant breakthrough required several hours. Surface decontamination of wood with high-test hypochlorite is 95% effective.

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Pharmacology of organophosphates. Koelle, George B. Med. Sch., Univ. Pennsylvania, Philadelphia, PA, USA. Journal of Applied Toxicology (1994), 14(2), 105-9. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 121:2654 AN 1994:402654 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 8 refs. The cholinergic nerve fibers, which employ acetylcholine (ACh) as a neurohumoral transmitter, and the results of their activation are listed. The reactions between the enzyme acetylcholinesterase (AChE), its natural substrate, ACh, and the various types of inhibitors are described. The limited therapeutic uses of the anticholinesterase (anti-ChE) agents are considered. The toxicol. effects encountered when the anti-ChE agents are employed as insecticides or as chem. warfare (CW) agents are discussed. Certain anti-ChE agents produce also a delayed neurotoxic effect which is apparently unrelated to the inhibition of AChE.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson, Barry W.; Kawakami, Thomas G.; Cone, Norman; Henderson, John D.; Rosenblatt, Leon S.; Goldman, Marvin; Dacre, Jack C. Inst. Toxicol., Univ. California, Davis, CA, USA. Toxicology (1994), 86(1-2), 1-12. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 120:263586 AN 1994:263586 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (tabun, phosphoramidocyanidic acid, dimethyl-, Et ester) as part of a program to demilitarize chem. warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but not in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only 3 of the 5 assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Effect of chemically added zirconia and yttria mechanical properties of zirconia-dispersed alumina. Ranjbar, Khalil; Rao, Boddapati T.; Mohan, Tallapragada R. Rama; Harendranath, Chilkunda S. Dep. Metall. Eng., Indian Inst. Technol., Bombay, India. American Ceramic Society Bulletin (1994), 73(2), 63-6. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 120:171374 AN 1994:171374 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Alumina powders dispersed with monoclinic, tetragonal, and cubic zirconia were prepd. by evapg. a colloidal dispersion of alumina powders in solns. contg. zirconium and yttrium salts. The dried and calcined powders were compacted, sintered, and characterized. The results demonstrated a clear toughening effect by the zirconia on the alumina ceramics. The alumina contg. 20-wt%-yttria-stabilized tetragonal zirconia had the max. toughness.

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Chemical vapor infiltration of silicon carbide with microwave heating. [Erratum to document cited in CA119(2):13852e]. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(12), 3251. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 120:141948 AN 1994:141948 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The errors were not reflected in the abstr. or the index entries.

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Chemical compatibility between silicon-based and titanium-based ceramics. Wang, L.; Wada, H. Dep. Mater. Sci. Eng., Univ. Michigan, Ann Arbor, MI, USA. Journal of Materials Synthesis and Processing (1993), 1(3), 181-93. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:277176 AN 1993:677176 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. compatibility between Si-based ceramics and Ti-based ceramics was studied to establish guidelines for the processing of related composites. Phase stabilities were calcd. for the Si-Ti-B-C, Si-Ti-B-N, and Si-Ti-B-C-N systems as a function of B activity and N pressure or C activity. SiC is compatible with TiC, TiN, or TiB2, depending on the range of these parameters. Si3N4 and TiN appear to be compatible in a certain range of N2 pressure and C activity, but Si3N4 and pure TiC will not coexist. However, the fact that TiC and TiN can form a solid soln., TiC1-xNx, suggests that Si3N4 and TiC1-xNx may be obsd. in the presence of both C and N2. The Si3N4 + TiB2 2-phase region is limited in such a narrow range of N2 pressure and B activity that processing and application of TiB2/Si3N4 composites would be very difficult. High-temp. solid-state expts. were carried out with selected systems to verify phase stability diagrams. The results of reactions were in agreement with the thermodn. prediction. A high-d. TiB2/SiC composite was prepd. as an example of the application of phase stability diagrams.

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Thermal and acid catalyzed conversion of organic phosphorus compounds. De Lijser, H. J. P.; Mulder, P.; Louw, R. Cent. Chem. Environ., Leiden Univ., Leiden, Neth. Chemosphere (1993), 27(5), 773-8. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:233159 AN 1993:633159 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The org. P compds. tri-Bu and tri-Me phosphate (I and II, resp.), tri-Me phosphite (III), and di-Me phosphonate (IV) were thermolyzed using a plug flow (gas-phase) reactor. I and II proved to be sensitive to acid (wall) catalysis and can be fully degraded at temps. of .mchlt.400. III can isomerize to II and IV. In contrast, IV requires a temp. of >750 for complete conversion; admixed with II it counteracts the smooth acid-mediated degrdn. of II. Unlike real thermolysis at elevated temps., preferably in a reducing atm. of hydrogen, mere acid catalysis is not generally applicable for effectively destroying a variety of ecotoxic org. P compds.

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Preparation of uniformly calcia-doped zirconia. Hill, J.; Newhouse, M.; Xue, J.; Dieckmann, R. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Journal of Materials Synthesis and Processing (1993), 1(2), 101-9. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:232072 AN 1993:632072 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The prepn. of dense samples of high-purity zirconia doped with varying, small contents of CaO has been explored by means of traditional ceramic techniques with sintering and hot-pressing as well as a chem. soln. method. First, CaO-doped samples were prepd. by traditional ceramic methods. Their homogeneities were checked by SEM with x-ray mapping. CaO-dopant distribution was not uniform in all samples with overall CaO contents below 7 mol%. The difficulty in prepg. uniformly doped zirconia with small CaO contents led to exploration of the use of chem. soln. processing techniques. When exploring such techniques, the products of each process step were characterized by x-ray diffraction and electron microprobe anal. The characterization results enabled identification of a processing route which is suitable for prepg. dense, high-purity zirconia uniformly doped with CaO at low concns.

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A model for the isothermal isobaric chemical vapor infiltration (CVI) in a straight cylindrical pore. Application to the CVI of silicon carbide. Fedou, R.; Langlais, F.; Naslain, R. Lab. Compos. Thermostruct., CNRS, Pessac, Fr. Journal of Materials Synthesis and Processing (1993), 1(2), 61-74. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:208796 AN 1993:608796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A previously described modeling of the chem. vapor infiltration (CVI) process in a straight cylindrical pore is applied to the deposition of SiC-based ceramics from MeSiCl3-H2 in the case of a 1st-order kinetic law with respect to MeSiCl3. The model gives concns. and deposit thickness profiles along the pore at any stage of the densification and, particularly, at the end of the process when the pore becomes sealed. The infiltration homogeneity is predicted to be improved by decreasing the aspect ratio of the pore and the CVI temp. and, under conditions of Fick diffusion, by decreasing the total pressure and the pore diam. The model is validated by the good fit between the deposit thickness profiles along the pore calcd. after adjustment of the kinetic data and exptl. profiles for a 34-m straight pore.

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Nicalon-fiber-reinforced silicon carbide composites via polymer solution infiltration and chemical vapor infiltration. Kim, Young Wook; Song, Jin Soo; Park, Sang Whan; Lee, Juen Gunn. Struct. Ceram. Lab., Korea Inst. Sci. Technol., Seoul, S. Korea. Journal of Materials Science (1993), 28(14), 3866-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 119:186895 AN 1993:586895 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A new, faster process was developed for the fabrication of Nicalon-fiber-reinforced SiC composites by combining polymer soln. infiltration (PSI) and chem. vapor infiltration (CVI). The process led to the near-net-shape fabrication of fiber-reinforced ceramic-matrix composites and reduced infiltration time. Typical flexural strength and fracture toughness of these composites were 296 MPa and 10.9 MPa.m1/2 at room temp. and 252 MPa and 9.6 MPa.m1/2 at 1000, resp. The composites exhibited load-carrying capability after crack initiation.

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The effect of glass chemistry on the microstructure and properties of self reinforced silicon nitride. Pyzik, Aleksander J.; Carroll, Daniel F.; Hwang, C. James. Adv. Ceram. Lab., Dow Chem. Co., Midland, MI, USA. Materials Research Society Symposium Proceedings (1993), 287(Silicon Nitride Ceramics), 411-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:186804 AN 1993:586804 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The advantage of self-reinforced silicon nitride is the in-situ control of the microstructure. This control is provided in large degree by the chem. of glassy phase which can be adjusted to tailor the morphol. of silicon nitride grains as well as the matrix-reinforcement interface. The presence of high aspect ratio silicon nitride grains is necessary but not sufficient condition to produce materials with optimum properties. For max. flexure strength and fracture toughness, an optimized glass matrix is required.

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Microwave assisted chemical vapor infiltration. Devlin, D. J.; Currier, R. P.; Barbero, R. S.; Espinoza, B. F.; Elliott, N. Mater. Sci. Technol. Div., Los Alamos Natl. Lab., Los Alamos, NM, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 245-50. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144800 AN 1993:544800 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A microwave-assisted process for prepn. of continuous fiber-reinforced ceramic-matrix composites is described. A simple app. combining a chem.-vapor-infiltration reactor with a conventional 700-W multimode oven is described. Microwave-induced inverted thermal gradients are exploited with the ultimate goal of reducing processing times on complex shapes. Thermal gradients in stacks of SiC (Nicalon) cloths have been measured using optical thermometry. Initial results on the inside-out deposition of SiC via decompn. of MeSiCl3 in H are presented. Several key processing issues are identified and discussed.

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Chemical vapor deposition of multiphase boron-carbon-silicon ceramics. Golda, E. Michael; Gallois, B. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 167-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144796 AN 1993:544796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Specific compns. of boron-carbon-silicon ceramics exhibit improved abrasive wear and good thermal shock resistance, but require bulk sintering at temps. in excess of 2100K. The formation of such phases by CVD was examd. at 1073-1573K. Methyltrichlorosilane (CH3SiCl3), boron trichloride, and methane were chosen as reactant gases, with hydrogen as a carrier gas and diluent. The coatings were deposited in a computer-controlled, hot-wall reactor at a pressure of 33 MPa. Below 1473K the coatings were amorphous. At higher temps. nonequil. reactions controlled the deposition process. The most common coating consisted of a silicon carbide matrix and a silicon boride, SiB6, dispersed phase. Multiphase coatings of B + B4C + SiB6 and SiC + SiB6 + SiB14 were also deposited by controlling the partial pressure of methane and boron trichloride. Non-equil. thermodn. anal. qual. predicted the exptl. deposited multiphase coatings.

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CVD of silicon nitride plate from trichlorosilane-ammonia-hydrogen mixtures. Lennartz, J. W.; Dowell, M. B. Union Carbide Coat. Serv. Corp., Parma, OH, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 161-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144795 AN 1993:544795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preferred conditions for deposition of thick -Si3N4 plate from HSiCl3-NH3-H2 on the vertical surfaces of a low-pressure, hot-wall CVD reactor were identified by means of a designed expt. The design included temp. range 1300-1500, pressures 0.5-2.0 torr, and residence times 0.01-1.0 s. The vertical deposition surfaces received a viscous, laminar flow of well mixed, thermally equilibrated reactants. Plates 0.05-0.5 mm thick were produced on multiple vertical substrates 350 cm2 in area at deposition rates 5-70 m/h. Plates 0.5-4.0 mm thick were produced on horizontal substrates at deposition rates of 60-120 m/h. When NH3 flows in stoichiometric excess, deposition rates on vertical surfaces increase approx. linearly with the flow rate of HSiCl3 but depend little on temp., as would be expected if the reaction proceeds under mass transport control with product depletion. Multiple correlation analyses show that thickness variations in the deposit are reduced by increasing the temp. and decreasing the gas residence time. CVD silicon nitride plate produced under the optimized conditions exhibits theor. d. and is free of pores and cracks. It exhibits a columnar morphol. in which the <222> and <101> crystallog. directions are oriented preferentially normal to a surface, which consists of well-defined trigonal facets 10-50 m across. Crystallite sizes detd. by x-ray line broadening range from 0.06-1.0 m. This CVD plate is gray and contains approx. 0.5 C and 0.5 wt.% 0 as principal impurities.

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Unequivocal evidence. Black, Robin M.; Pearson, Graham S. Chem. Biol. Def. Estab., Porton/Down/Salisbury Wiltshire, UK. Chemistry in Britain (1993), 29(7), 584-5, 587. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 119:123791 AN 1993:523791 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of chem. warfare agent, Sarin, in the Kurdush village of Birjinni, Iraq, was discussed.

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Bioanalysis of organophosphate nerve agents in soil samples. Sawyer, T. W.; Weiss, M. T. Biomed. Def. Sect., Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Chemosphere (1993), 26(11), 2023-9. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:94477 AN 1993:494477 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Four soil samples that may have been spiked with chem. warfare (CW) agents and their degrdn. products were received by Defense Research Establishment Suffield as part of a multinational round-robin exercise designed to evaluate lab. methodologies for the chem. detection of CW agents in soil. After chem. anal. revealed that VX (Et S-2-diisopropyl aminoethyl methylphosphorothiolate) was the CW agent "spike", the samples were also bioassayed for their VX content by assessing their anticholinesterase activities in primary chick embryo neuron cultures. Bioassay quantitation of VX contamination in the soil samples was in good agreement with the actual spike levels and generally better than the chem. anal. results. Sequential bioassay of the samples over a two week period showed that the VX content was rapidly degraded with time. This assay complements std. chem. anal. techniques for the detection and verification of organophosphate warfare agent use.

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The effect of trace element segregation to iron/sapphire interfaces. Pope, D. P.; Smith, M. A. Dep. Mater. Sci., Univ. Pennsylvania, Philadelphia, PA, USA. Materials Research Society Symposium Proceedings (1992), 238(Structure and Properties of Interfaces in Materials), 427-32. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:77041 AN 1993:477041 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of segregation of tramp impurities such as sulfur on metal/ceramic bonding is discussed. Microstructural and chem. information is given for the Fe/sapphire interface. The segregation behavior of the interface is evaluated between 500-800. The interfacial structure is important to the segregation behavior. A possible link between the segregation of sulfur and interface void formation is presented.

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Chemical vapor infiltration of silicon carbide with microwave heating. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(5), 1057-67. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 119:13852 AN 1993:413852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is presented to describe the interaction between transport/reaction processes and the evolution of porosity in chem. vapor infiltration with microwave heating (MCVI). The anal. includes a set of partial differential equations describing the spatiotemporal variation of gaseous species concn., composite temp., porosity, and stress. Maxwell's equations were used to det. the distribution of power dissipated inside the composite. The deposition of silicon carbide was selected as a model chem. system to explore the general features of MCVI. MCVI can provide a favorable temp. distribution in the composite yielding an inside-out deposition pattern, thereby preventing entrapment of accessible porosity. For this temp. profile, tensile stresses develop at the outer regions and compressive stresses are found in the composite core. For a given system there exists a min. value of the coeff. for heat transfer from the composite surface, h, below which accessible porosity is trapped within the composite. Similarly, there exists a max. value of the incident microwave energy flux, I0, above which accessible porosity is trapped within the composite. I0 and h can be optimized for a given preform to achieve complete densification with min. processing time. Using the technique of pulsed-power, the processing time can be reduced even further without compromising d. uniformity. Power dissipation profiles in the composite depend strongly on preform thickness, microwave frequency, and relative loss factor.

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Permeation measurements of chemical agent simulants through protective clothing materials. Pal, Tarasankar; Griffin, Guy D.; Miller, Gordon H.; Watson, Annetta P.; Daugherty, Mary Lou; Vo Dinh Tuan. Health Saf. Res. Dev., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Hazardous Materials (1993), 33(1), 123-41. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 118:239880 AN 1993:239880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A method was developed to study the permeation of chem. warfare (CW) agent simulants through chem. protective clothing (CPC) materials. The exptl. results characterize some com. available CPC materials. Thirteen different CPC materials having widely differing compns. were chosen to study the permeation of 4 different liq. CW simulants (di-Me methylphosphonate, diisopropyl methylphosphonate, malathion, and Bu2S) through these CPC materials at 25. This permeation study involved a newly developed anal. technique employing room temp. fluorescence quenching of an indicator compd., phenanthrene, on filter paper. Various exptl. factors such as breakthrough time, rate of permeation, and uptake were investigated. On the basis of breakthrough time, the 13 CPC materials could be divided into 3 groups: most resistant, moderately resistant, and least resistant. Materials in the most resistant category exhibited no permeation by any of the simulants for 24 h. Breakthrough occurred in the least resistant materials in generally less than an hour, and sometimes as soon as a few minutes.

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Interfacial structure of chemical vapor infiltration carbon fiber/silicon carbide composite. Araki, H.; Noda, T.; Abe, F.; Suzuki, H. Tsukuba Lab., Natl. Res. Inst. Met., Tsukuba, Japan. Journal of Materials Science Letters (1992), 11(23), 1582-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:44089 AN 1993:44089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure at the interface in carbon fiber-SiC matrix composites prepd. by chem. vapor infiltration from EtSiCl3 was examd., and the infiltration reaction is discussed. A graphite layer formed on the carbon fiber and the SiC-SiC interface as a result of thermal decompn. of silane gas before SiC infiltration. This graphite layer, of .apprx.500 nm thickness, is assumed to assist in the crystal growth of SiC, leading to structural stability of the composites.

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Comparative evaluation of carbamates as prophylactic agents against organophosphate intoxication in rats. Chatterjee, A. K. Def. Res. Dev. Establ., Gwalior, UK. Defence Science Journal (1992), 42(2), 85-7. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 118:34070 AN 1993:34070 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper investigates the effects of two well-known carbamates, physostigmine and pyridostigmine, against organophosphorus compd. and nerve gas toxicity. Physostigmine pretreatment for 30 min enhanced the survival time of rats against DFP intoxication, whereas it did not have any effect with sarin poisoning. However, pyridostigmine pretreatment did not produce any significant effect on survival time either against DFP or sarin intoxication. Treatment with atropine along with carbamates further enhanced significantly the survival time against DFP poisoning.

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On the influence of chemical processing in the crystallization behavior of zirconium titanate materials. Navio, J. A.; Macias, M.; Sanchez-Soto, P. J. Inst. Cienc. Mater., Univ. Sevilla, Seville, Spain. Journal of Materials Science Letters (1992), 11(23), 1570-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:26385 AN 1993:26385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The crystn. phenomena of ZrTiO4 powders prepd. from various gel precursors was related to the chem. processing. Correlation of data from the literature and further expt. indicated that the presence of H2O2 in the chem. processing of the amorphous precursors plays a key role in controlling the crystn. temp. The crystn. temp. can be as low as 640.

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Effect of dopants on the sintering behavior and stability of tetragonal zirconia ceramics. Theunissen, G. S. A. M.; Winnubst, A. J. A.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1992), 9(4), 251-63. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:54278 AN 1992:454278 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure development during nonisothermal and isothermal sintering was studied for tetragonal zirconia ceramics (TZP) contg. various amts. of Y, Ce, and Ti. Smaller grain sizes were obtained when Ce-TZP was doped with Y. This could be attributed to segregation of Y to the grain boundaries, thus causing an impurity drag. With increasing temp., the grain growth rate in the Ce-TZP samples increased which could be attributed to the absence of a dragging force. The slow grain growth at low temp. in the Ce-TZP samples could be attributed to the slow diffusion kinetics of the diffusing species (trivalent and tetravalent Ce). The crit. grain size for retainment of the tetragonal phase at room temp. is larger in the Y,Ce-TZP systems compared to the Y-TZP and Ce-TZP systems. The chem. stability increased by doping Y-TZP with Ce or Ti.

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Free radical-mediated lung response to the monofunctional sulfur mustard butyl 2-chloroethyl sulfide after subcutaneous injection. Elsayed, Nabil M.; Omaye, Stanley T.; Klain, George J.; Korte, Don W., Jr. Letterman Army Inst. Res., Presidio of San Francisco, CA, USA. Toxicology (1992), 72(2), 153-65. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 117:42116 AN 1992:442116 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors postulated that vesicants may cause free radical-mediated oxidative stress distal to the site of exposure. To test this postulate in the lung, the authors injected 3 groups of 5-mo-old, male, athymic, nude mice, weighing 30-35 g with a single s.c. dose (5 L/mouse) of Bu 2-chloroethyl sulfide (BCS). Total lung wt. was not altered after treatment, but the wet/dry wt. ratio decreased 18% and Hb content increased 50 and 36% at 1 and 24 h, resp. The activity of glucose 6-phosphate dehydrogenase increased significantly, 40% at 1 and 24 h and 84% at 48 h and that of glutathione S-transferases was 60%. Lipid peroxidn. (estd. by the thiobarbituric acid test) and total protein content increased 3-fold and 2-fold, at 1 and 24 h, resp. Total and oxidized glutathione contents were significantly elevated, 38% at 1 h and 64% at 24 h for the former and 45% at 24 h and 56% at 48 h for the latter. Because these changes are consistent with the cellular response to oxidative stress, it is concluded that BCS injected s.c. can cause changes in the lung possibly via a free radical-mediated mechanism.

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Effects of liquid environments on zirconia-toughened alumina. Part I. Chemical stability. Thompson, I.; Rawlings, R. D. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1992), 27(10), 2823-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:32321 AN 1992:432321 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The structural changes which occur in zirconia-toughened alumina when aged in a range of liq. environments (distd. water, ethylene glycol soln., and HCl at room temp., and ethylene glycol soln. at 80) are described. The changes were monitored by x-ray diffraction, surface anal., anal. of the aging solns., and microstructural observations. HCl induced significant proportions of the zirconia particles in the zirconia-toughened alumina to transform from the tetragonal to the monoclinic crystal structure. This transformation was accompanied by microcracking which eventually led to macrocracking after long periods of aging. The transformation is a consequence of the leaching of the yttrium from the zirconia particles, thereby reducing their stability.

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Binder chemistry, adhesion and structure of interfaces in thick-film metalized aluminum nitride substrates. Newberg, C. E.; Risbud, S. H. IBM Corp., East Fishkill, NY, USA. Journal of Materials Science (1992), 27(10), 2670-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:13161 AN 1992:413161 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Aluminum nitride substrates from 3 sources were metalized by std. thick-film processing using gold conductor pastes, Pd-Ag paste, and a ruthenium oxide resistor paste. Screen-printed pastes were fired in a typical 3-zone furnace to obtain metalized AlN substrates. Interfacial reaction zones were studied by microscopic (optical and SEM) and electron beam microprobe anal. techniques. The elements in the binder materials in thick-film pastes form amorphous phases at the interface which influence the adhesion of thick films to the AlN substrate. The lack of certain elements (Cd, Zn, Ca) in the binder of the gold thick-film paste led to weaker adhesion and severe degrdn. of the thick-film adhesion during thermal cycling.

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Preparation and characterization of a dispersion toughened ceramic for thermomechanical uses (ZTA). Part I. Material preparation. Characterization of microstructure. Leriche, A.; Moortgat, G.; Cambier, F.; Homerin, P.; Thevenot, F.; Orange, G.; Fantozzi, G. CRIBC, Mons, Belg. Journal of the European Ceramic Society (1992), 9(3), 169-76. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:13037 AN 1992:413037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Zirconia-toughened alumina (ZTA) materials contg. increasing amts. of zirconia (5-45 vol.%) and yttria (0-3 mol% zirconia) were prepd. from com. ceramic powders by different techniques of homogenization, shaping, and sintering. The powder mixts. were homogenized by a chem. method (addn. of dispersing agents at fixed pH), by a mech. method (attrition milling) and by combining the methods. The materials were formed and sintered by shaping by isostatic pressing or slip casting, followed by pressureless sintering, and by hot uniaxial pressing. The phys., crystallog. and microstructural properties of the materials prepd. following these different techniques are compared. The combined chem. and mech. dispersion method leads to the fabrication of dense composites presenting a fine and homogeneous zirconia dispersion required for effective toughening of the alumina matrix. The addn. of 3 mol% of yttria allows maintenance of a high tetragonal zirconia content because of a chem. stabilization of tetragonal zirconia and of a decrease of zirconia grain size. As the hot-pressing technique impedes the grain coarsening, the hot-pressed materials present the finest microstructure mainly for the compns. with <20 vol.% zirconia. The zirconia and alumina grain size vary from 0.5 to 0.9 m and from 0.9 to 1.6 m, resp., following the compn. Pressureless sintered materials also present a fine microstructure with submicron zirconia grains (0.6 m-0.9 m) and micron size alumina grains (1.0-1.9 m). These ZTA materials present all the microstructural characteristics necessary to obtain high mech. performances. The addn. of 3 mol% of yttria allows an increase of the zirconia content (45 vol.%) without a decrease of the relative tetragonal zirconia ratio occurring.

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Adsorption and decomposition of organophosphorus compounds on nanoscale metal oxide particles. In situ GC-MS studies of pulsed microreactions over magnesium oxide. Li, Yong Xi; Koper, Olga; Atteya, Maher; Klabunde, Kenneth J. Dep. Chem., Kansas State Univ., Manhattan, KS, USA. Chemistry of Materials (1992), 4(2), 323-30. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 116:200414 AN 1992:200414 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Using an in-situ pulse reactor-GC-mass spectrometric system, the thermal decompn. of organophosphorus compds. (as models of nerve agents) were compared with their destructive absorption on high-surface-area MgO. Dramatically lower temps. are required when MgO is present. Volatile products evolved were HCO2H, water, alcs., and alkenes. At higher temps., CO, CH4, and water predominated. The P residues remained completely immobilized. The addn. of water enhanced the facility of MgO to destroy these compds., and, in fact, water pulses were found to partially regenerate a spent MgO bed. Using 18O labeling, some aspects of the reaction mechanisms were clarified and in particular showed that O scrambling occurred. Surface OH and MgO groups transferred O in the formation of HCO2H, and the surface mobility and reactivity of absorbed groups were high. The substantial capacity of high-surface-area MgO for destruction and immobilization of such toxic substances makes it attractive for air purifn. schemes, as well as solid reagents for destruction and immobilization of bulk quantities of hazardous P compds. or organohalides.

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-(N,N-Dialkylamino)ethyl arylthiosulfonates: new simulants for O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate. Davis, Franklin A.; Ray, Jayanta K.; Kasperowicz, Steve; Przeslawski, Robert M.; Durst, H. Dupont. Dep. Chem., Drexel Univ., Philadelphia, PA, USA. Journal of Organic Chemistry (1992), 57(9), 2594-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 116:193819 AN 1992:193819 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Certain S-[2-(dialkylamino)]ethyl benzenesulfonothioates 4-XC6H4SO2SCH2CH2NR2 (I; X = Me, F; R = Me2CH) were prepd. as simulants for O-Et S-[(diisopropylamino)ethyl]methylphosphonothioate (VX) a chem. warfare nerve agent. I are useful simulants for the hydrolysis or oxidn. chem. of VX.

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Dissolution of sintered silicon nitride bulk specimens for elemental analysis. Homeier, E. H.; Bradley, S. A.; Karasek, K. R. UOP, Des Plaines, IL, USA. Journal of Materials Science (1992), 27(5), 1231-4. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:179524 AN 1992:179524 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Heating bulk, sintered Si3N4 samples in an aq. HF-HCl mixt. decomps. the Si3N4. Subsequent addn. of H2SO4 and volatilization of fluorides enables total dissoln. of the bulk specimens for anal. The elemental compns. that were detd. by inductively coupled plasma at. emission and at. absorption spectrometries agreed with the nominal sample compn. and confirmed analyses performed by scanning TEM. Neutron activation detns. on the same samples are not believed to be as accurate as the spectrometric detns. Furthermore, the precision of the neutron activation measurements were less satisfactory, esp. for key elements such as Y.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy, Paul M.; Hansen, Arnold S.; Hand, Brian T.; Boulet, Camille A. Def. Res. Establ. Suffield, Ralston, AB, Can. Toxicology (1992), 72(1), 99-105. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 116:168061 AN 1992:168061 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a std. set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI 6 > HLoe 7 > pyrimidoxine. Hloe 7 was very effective against tabun poisoning while HI 6 and pyrimidoxime were of moderate value. Against GF, HI 6 and HLoe 7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLoe-7 to a slightly lesser degree. The other oximes lacked the effects against one or more of the organophosphates.

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Chemical vapor deposition of copper via disproportionation of hexafluoroacetylacetonato(1,5-cyclooctadiene)copper(I), (hfac)Cu(1,5-COD). Jain, A.; Chi, K. M.; Hampden-Smith, M. J.; Kodas, T. T.; Farr, J. D.; Paffett, M. F. Dep. Chem. Eng., Univ. New Mexico, Albuquerque, NM, USA. Journal of Materials Research (1992), 7(2), 261-4. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 116:111299 AN 1992:111299 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hot- and cold-wall chem.-vapor deposition (CVD) using the volatile Cu(I) compd. (hfac)Cu(1,5-COD), where hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate and 1,5-COD = 1,5-cyclooctadiene, as a precursor was carried out in hot-wall and warm-wall, lamp-heated reactors using SiO2 substrates that were patterned with Pt or W at 120-250. Deposition was obsd. onto Pt, W, and SiO2 over this temp. range at rates of 3750 .ANG./min to give Cu films that contained no impurities detectable by AES and with resistivities of 1.9-5.7 ohm-cm. The volatile byproducts formed during deposition were 1,5-COD and Cu(hfac)2 and a mass balance was consistent with the quant. disproportionation reaction: 2(hfac)Cu(1,5-COD)  Cu + Cu(hfac)2 + 2(1,5-COD). The measured activation energy for this CVD reaction was 26(2) kcal/mol. The absence of selectivity for metal surfaces in the presence of SiO2 is in contrast to CVD results for the related compds. (-diketonate)Cu(PMe3) where -diketonate = hfac, 1,1,1-trifluoroacetylacetonate, and acetylacetonate (acac).

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer, Thomas W.; Weiss, M. Tracy; D'Agostino, Paul A.; Provost, Lionel R.; Hancock, James R. Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Journal of Applied Toxicology (1992), 12(1), 1-6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 116:105057 AN 1992:105057 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chem. warfare activity was subjected to chem. anal. and bioassay. Sarin and several related compds. were confirmed in the soil by capillary column gas chromatog.-mass spectrometry (GC-MS); however, the binding of these compds. to the soil hindered quantitation. The chem. results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified stds. in chick embryo neuron cultures, a reasonable agreement was found between the chem. and bioassay semiquant. ests. of sarin content in the soil ext. Furthermore, the in-vitro system appears to offer a sensitive technique for the estn. of sarin remaining bound to the soil following solvent extn. as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Pharmacological effects of oximes: how relevant are they?. van Helden H P; Busker R W; Melchers B P; Bruijnzeel P L Department of Pharmacology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1996), 70(12), 779-86. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 8911635 AN 97068325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The increased international concern about the threat of military and terroristic use of nerve agents, prompted us to critically consider the expected value of the currently available oxime treatment of nerve agent poisoning. Although oximes have been designed to reactivate the inhibited acetylcholinesterase (AChE), clinical experience has indicated that they are not always very effective as reactivators and at this very moment none of them can be regarded as a broad-spectrum antidote. In spite of this drawback, oximes are worth further investigating, since recent data derived from soman or tabun lethally intoxicated non-human primates suggest that the oxime HI-6 may exert a pharmacological effect that is not related to reactivation of inhibited AChE, but still leads to survival. This pharmacological effect causes recovery of neuronal transmission in the respiratory centres of the brain and recovery of neuromuscular transmission in the diaphragm. These findings have stimulated research to reveal the pharmacological basis of these effects in order to find drugs which could be more effective and less toxic than the available oximes. Since cholinergic drugs were able to exert this effect, a new concept for further treatment is suggested: maintenance of neuronal transmission in spite of continued AChE-inhibition by pharmacological manipulation of the cholinergic receptor. This should renew interest in the diverse pharmacological effects of oximes to reach a more effective treatment in the future.

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Evaluation of the therapeutic efficacy of some antimuscarinics against soman in vivo. Lau W M; Lewis K J; Dawson R M Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organization, Department of Defence, Melbourne, Victoria, Australia Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 423-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889794 AN 97044723 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The therapeutic efficacy of tacrine, atropine and glycopyrrolate alone or in combination with the oxime HI-6 against soman was evaluated in anaesthetized rats. Arterial blood pressure, heart rate, respiratory frequency and body temperature were monitored in vivo. Blood cholinesterases were determined after each drug or soman challenge. At the lowest concentration tested (2.5 mg kg-1), tacrine was effective in improving the survivability of the rat by a factor of 2.6 (protection ratio), whereas the protection by atropine or glycopyrrolate was either insignificant or only marginally effective (protection ratio ranged from 1.0 to 1.9). In combination with HI-6, atropine increased the ratio to 4.6. In contrast, tacrine with HI-6 failed to improve the efficacy of the regimen, while glycopyrrolate plus HI-6 showed only slight improvement. The four physiological parameters monitored were relatively constant during the time course of the experiment in both the control and those with drug therapy. The more noticeable changes occurred toward the end of the experiment when sufficient amount of soman was injected to cause lethality. Death of the animal was usually preceded by a surge of arterial blood pressure and heart rate and a decrease in respiratory frequency. These physiological parameters rapidly deteriorated to zero just before the animal died. Blood and plasma cholinesterases were significantly inhibited after the animal received a relatively small dose of soman (20 micrograms kg-1) and were almost completely inactivated after the lethal dose of soman was administered. However, these changes of enzyme activity did not correspond well with the survivability of the rat. The inclusion of HI-6 with the three antimuscarinics appeared to be capable of protecting some cholinesterases against soman.

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Efficacy of ibuprofen and pentoxifylline in the treatment of phosgene-induced acute lung injury. Sciuto A M; Stotts R R; Hurt H H Pathophysiology Division, United States Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 381-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889788 AN 97044717 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Phosgene, a highly reactive former warfare gas, is a deep lung irritant which produces adult respiratory distress syndrome (ARDS)-like symptoms following inhalation. Death caused by phosgene involves a latent, 6-24-h, fulminating non-cardiogenic pulmonary edema. The following dose-ranging study was designed to determine the efficacy of a non-steroidal anti-inflammatory drug, ibuprofen (IBU), and a methylxanthine, pentoxifylline (PTX). These drugs were tested singly and in combination to treat phosgene-induced acute lung injury in rats. Ibuprofen, in concentrations of 15-300 mg kg-1 (i.p.), was administered to rats 30 min before and 1 h after the start of whole-body exposure to phosgene (80 mg m-3 for 20 min). Pentoxifylline, 10-120 mg kg-1 (i.p.), was first administered 15 min prior to phosgene exposure and twice more at 45 and 105 min after the start of exposure. Five hours after phosgene inhalation, rats were euthanized, the lungs were removed and wet weight values were determined gravimetrically. Ibuprofen administered alone significantly decreased lung wet weight to body weight ratios compared with controls (P < or = 0.01) whereas PTX, at all doses tested alone, did not. In addition, the decrease in lung wet weight to body weight ratio observed with IBU+PTX could be attributed entirely to the dose of IBU employed. This is the first study to show that pre- and post-treatment with IBU can significantly reduce lung edema in rats exposed to phosgene.

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Subchronic toxicity evaluation of sulfur mustard in rats. Sasser L B; Miller R A; Kalkwarf D R; Cushing J A; Dacre J C Pacific Northwest Laboratory, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1996 Jan-Feb), 16(1), 5-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8821670 AN 96418885 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

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Acute toxicity of cyclohexylmethylphosphonofluoridate (CMPF) in rhesus monkeys: serum biochemical and hematologic changes. Young G D; Koplovitz I U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Archives of toxicology (1995), 69(6), 379-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7495375 AN 96114840 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Changes in serum biochemical and hematological parameters were studied in 20 male rhesus monkeys following acute poisoning by the organophosphate nerve agent cyclohexylmethylphosphonofluoridate (CMPF or GF). Animals were challenged with 5 x LD50 GF (233 micrograms/kg, IM) following pretreatment with pyridostigmine (0.3-0.7 mg/kg per 24 h) and treated with atropine (0.4 mg/kg, IM) and either 2-PAM (25.7 mg/kg, IM) or H16 (37.8 mg/kg, IM) at the onset of clinical signs or at 1 min after exposure. Muscle fasciculations, tremors, or convulsions occurred in 19 of 20 animals. Serum biochemical and hematologic parameters were analyzed 2 days and 7 days after exposure and compared to pre-exposure baseline values. Significant increases in creatine kinase (CK), lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase (ALT) and potassium ion (K+), associated with damage to striated muscle and metabolic acidosis, occurred in both oxime-treated groups 2 days after exposure. Total protein, albumin, red blood cell (RBC) count, hemoglobin concentration (Hb) and hematocrit (Hct), were decreased in both oxime-treated groups at 7 days. The results demonstrate that animals exposed to a single high dose of GF and treated with standard therapy exhibit changes in serum biochemical and hematological indices directly and indirectly associated with their clinical presentations.

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Production, characterization and application of monoclonal antibodies against the organophosphorus nerve agent Vx. Ci Y X; Zhou Y X; Guo Z Q; Rong K T; Chang W B Department of Chemistry, Peking University, Beijing, China Archives of toxicology (1995), 69(8), 565-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8534201 AN 96036122 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Two monoclonal antibodies (Vx-BB8 and Vx-EA11) to the chemical warfare agent Vx were produced and characterized. A competitive inhibition enzyme immunoassay was developed to detect Vx concentrations as low as 3.7 x 10(-7) - 3.7 x 10(-6) mol/l in biological samples. Vx-BB8 400 micrograms given intravenously immediately before 1 x LD95 Vx or 400 micrograms Vx-BB8 intraperitoneally 1.5 h-3 days before 1 x LD95 Vx could protect all the tested mice from death.

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Toxicity of sulphur mustard in adult rat lung organ culture. Sawyer T W; Wilde P E; Rice P; Weiss M T Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada Toxicology (1995 Jun 26), 100(1-3), 39-49. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7542806 AN 95350771 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of the chemical warfare agent sulphur mustard, (bis-(2-chloroethyl)sulphide, HD), was examined in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concentration (LC50) of HD in these cultures was reproducible, and in the microM range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathological examination of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochemically, and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulphur mustard.

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Toxicity of the combined nerve agents GB/GF in mice: efficacy of atropine and various oximes as antidotes. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Canada Archives of toxicology (1994), 68(1), 64-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166607 AN 94219995 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of a combination of isopropyl methylphosphonofluoridate (sarin; GB) and cyclohexyl methylphosphonofluoridate (GF) and the efficacy of various oxime reactivators in combination with atropine against the combined GB/GF challenge were evaluated in mice. The 24-h s.c. LD50 of the GB/GF combination was 1.15 mumol/kg (1.10-1.21; 95% confidence limits). Mice administered GB/GF displayed typical signs of nerve agent poisoning such as tremors and convulsions, with death most likely due to anoxia subsequent to respiratory arrest. The GB/GF LD50 value was comparable to the s.c. LD50 of 1.35 and 1.21 mumol/kg for GF and GB in mice, respectively. Combining the two nerve agents did not result in potentiation of the toxicity. In combination with atropine sulfate (17.4 mg/kg, i.p.), which alone did not reduce mortality, the oximes tested, 2-PAM, obidoxime and HI-6, were all effective when administered 5 min before 3 x LD50 dose of GB/GF with 24-h ED50 values of 102.5, 18.22 and 1.96 mumol/kg, respectively. Use of the GB/GF combination does not appear to confer any unique toxicity profile and appears to be easily treated with the standard therapy of a cholinolytic and oxime.

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Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs. Due A H; Trap H C; Langenberg J P; Benschop H P TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1994), 68(1), 60-3. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166606 AN 94219994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson B W; Kawakami T G; Cone N; Henderson J D; Rosenblatt L S; Goldman M; Dacre J C Department of Avian Sciences, University of California, Davis 95616-5224 Toxicology (1994 Jan 26), 86(1-2), 1-12. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8134917 AN 94182225 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (Tabun, phosphoramidocyanidic acid, dimethyl-, ethyl ester) as part of a program to demilitarize chemical warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only three of the five assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Evaluation of the toxicity, pathology, and treatment of cyclohexylmethylphosphonofluoridate (CMPF) poisoning in rhesus monkeys. Koplovitz I; Gresham V C; Dochterman L W; Kaminskis A; Stewart J R US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425 Archives of toxicology (1992), 66(9), 622-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1482284 AN 93129117 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (CMPF) is an organophosphate cholinesterase inhibitor with military significance. The purpose of these studies was 1) to determine the acute toxicity of CMPF in the male rhesus monkey, 2) to evaluate the efficacy of pyridostigmine (PYR) pretreatment plus atropine and oxime (2-PAM or H16) treatment, and 3) to evaluate the pathological consequences of acute poisoning. An i.m. LD50 of CMPF was estimated using an up-and-down dose selection procedure and 12 animals. The 48-h and 7-day LD50 was 46.6 micrograms/kg, i.m. In the protection experiments, pyridostigmine (0.3-0.7 mg/kg/24 h) was administered by surgically implanted osmotic minipumps for 3-12 days resulting in 21-65% inhibition of erythrocyte acetylcholinesterase activity. Animals were challenged with 5 x L50 CMPF (233 micrograms/kg) and treated with atropine (0.4 mg/kg) and either 2-PAM (25.7 mg/kg) or HI6 (37.8 mg/kg) at the onset of signs or 1 min after challenge. Osmotic pumps were removed within 30 min after agent challenge. Pyridostigmine, atropine, and either 2-PAM or H16 were completely effective against CMPF, saving ten of ten animals in each group. In comparison, three of five animals challenged with 5 x LD50 of soman and treated with atropine and 2-PAM survived 7 days. The primary histologic lesions in the acute toxicity group were neuronal degeneration/necrosis and spinal cord hemorrhage. The CMPF treated groups (total of 20 animals) had minimal nervous system changes with no significant lesion difference resulting from the different oxime therapies. The primary non-neural lesions were degenerative cardiomyopathy and skeletal muscle degeneration which occasionally progressed to necrosis and mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)

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Efficacy of various oximes against GF (cyclohexyl methylphosphonofluoridate) poisoning in mice. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Alta., Canada Archives of toxicology (1992), 66(2), 143-4. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1605730 AN 92296882 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The efficacy of oxime (HI-6, toxogonin or PAM Cl) therapy against GF (cyclohexyl methylphosphonofluoridate) poisoning was assessed in mice. It was found that the combinations of atropine and either toxogonin or HI-6 were effective therapies against GF poisoning. PAM therapy was ineffective. HI-6 was the only oxime which reactivated GF inhibited acetylcholinesterase. This might explain the reason why the HI-6 treated mice appeared to recover more quickly from the incapacitating effects following GF poisoning.

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer T W; Weiss M T; D'Agostino P A; Provost L R; Hancock J R Defence Research Establishment Suffield, Alberta, Canada Journal of applied toxicology : JAT (1992 Feb), 12(1), 1-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1564246 AN 92226402 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chemical warfare activity was subjected to chemical analysis and bioassay. Sarin and several related compounds were confirmed in the soil by capillary column gas chromatography-mass spectrometry (GC-MS); however, the binding of these compounds to the soil hindered quantitation. The chemical results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified standards in chick embryo neuron cultures, a reasonable agreement was found between the chemical and bioassay semi-quantitative estimates of sarin content in the soil extract. Furthermore, the in vitro system appears to offer a sensitive technique for the estimation of sarin remaining bound to the soil following solvent extraction as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy P M; Hansen A S; Hand B T; Boulet C A Defence Research Establishment Suffield, Ralston, Alberta, Canada Toxicology (1992), 72(1), 99-105. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1539175 AN 92169690 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a standard set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI-6 greater than HLo-7 greater than pyrimidoxime. HLo-7 was very effective against tabun poisoning while HI-6 and pyrimidoxime were of moderate value. Against GF, HI-6 and HLo-7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLo-7 to a slightly lesser degree. The other oximes suffered from their lack of effects against one or more of the organophosphates.

[megalomania]

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Aluminum nitride defect chemistry dependence on sintering atmosphere. Chang, E. K.; Kirschner, M. J. BOC Group Technical Cent., Murray Hill, NJ, USA. Journal of Materials Science Letters (1996), 15(18), 1580-1581. CODEN: JMSLD5 ISSN: 0261-8028. Journal; General Review written in English. CAN 125:282600 AN 1996:614771 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 12 refs., of equations explaining theor. relations between aluminum nitride defect chem. and sintering atm.

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Microstructure, chemical reaction and mechanical properties of TiC/Si3N4 and TiN-coated TiC/Si3N4 composites. Huang, Jow-Lay; Lee, Ming-Tung; Lu, Horng-Hwa; Lii, Ding-Fwu. Dep. Material Science Eng., National Cheng-Kung Univ., Tainan, Taiwan. Journal of Materials Science (1996), 31(18), 4899-4906. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:254919 AN 1996:610489 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Silicon nitride contg. various compns. of as-received TiC and TiN-coated TiC, were hot pressed at 1800 C for 1 h in a nitrogen atm. In TiN-coated TiC/Si3N4 composites, TiC reacted first with the TiN coating to form a titanium carbonitride interlayer at 1450 C, which essentially reduced further reactions between TiC and Si3N4 and enhanced densification. TiN-coated TiC/Si3N4 composites exhibited better densification, hardness, flexural strength and fracture toughness than those of as-received TiC/Si3N4. The toughening mechanisms for as-received TiC/Si3N4 and TiN-coated TiC/Si3N4 composite were attributed to crack deflection, load transfer and crack interference by the compressive thermal residual stress.

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Wet chemical synthesis of ZrO2-SiO2 composite powders. Wang, Shi-Wei; Huang, Xiao-Xian; Guo, Jing-Kun. Shanghai Inst. Ceramics, Chinese Academy Sciences, Shanghai, Peop. Rep. China. Journal of the European Ceramic Society (1996), 16(10), 1057-1061. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 125:254896 AN 1996:596753 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of compn. xZrO2(I-x)SiO2, with x = 10, 20, 30 and 40 vol.%, have been prepd. by a wet chem. method using fumed silica and zirconyl chloride as precursors. Thermogravimetric anal. and differential thermal anal. (DTA) show that wt. loss is caused by release of the absorbed water and decompn. of the Zr(OH)4 gels. Gels were heat-treated for 2 h at 500, 700, 900, 1100 and 1350C, and the products examd. using IR spectroscopy. The increasing intensity of the peak at 800 cm-1 in the IR spectra with increasing temp. is attributed to the formation of Si-O-Si bonds among different SiO2 particles, which means that the SiO2 particles grow bigger with increasing temp. The DTA exothermic peak as well as the IR results reveal that the crystn. of tetragonal zirconia (t-ZrO2) begins at about 900C, which is confirmed by x-ray diffraction (XRD). XRD curves also suggest that the silica matrix contributes to the thermal stability of t-ZrO2. The stability of t-ZrO2 is interpreted by the particle-size effect.

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Structure-property relationship of ceramic coatings produced by laser processing. De Hosson, J. Th. M.; Zhou, X. B. Dep. Applied Physics, Univ. Groningen, Groningen, Neth. Materials Research Society Symposium Proceedings (1996), 397(Advanced Laser Processing of Materials--Fundamentals and Applications), 537-542. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:306847 AN 1996:579019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper deals with a well known puzzling observation that wetting in some instances is improved by a chem. reaction between a liq. and a solid substrate in laser processing while in other systems just the opposite effect takes place. Contact angles of liq. Al on SiO2 and liq. Ti on Al2O3 are reported and some results of laser melt injection of SiO2 particles into molten Al. The surface and interface structures were explored by SEM and energy dispersive x-ray spectrometry. According to the exptl. observations, it appears that the vol. change of ceramic substrates during reaction plays a key role in the effect of chem. reaction on wetting.

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Mechanical and thermal properties of SiC-SiC composites made with CVR SiC fibers. Kowbel, W.; Tsou, H. T.; Bruce, C. A.; Withers, J. C. MER Corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1996), 410(Covalent Ceramics III--Science and Technology of Non-Oxides), 417-422. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:202665 AN 1996:502987 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temps. up to 1600C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addn., enhancement of the composite through-the-thickness thermal cond. was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.

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The influence of surface kinetics in modeling chemical vapor deposition processes in porous preforms. Dekker, J. P.; Moene, R.; Schoonman, J. Lab. Appl. Inorg. Chem., Delft Univ. Technol., Delft, Neth. Journal of Materials Science (1996), 31(11), 3021-3033. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65201 AN 1996:378298 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The isothermal chem. vapor infiltration (ICVI) process is a well known technique for the prodn. of composites and the surface modification of porous preforms. Math. modeling of the process can provide a better understanding of the influence of individual process parameters on the deposition characteristics such as final porosity or deposition profiles in the pore network. The influence of different rate expressions for several binary compds. on the ICVI process is discussed. Exptl. work is used to validate the importance of correct kinetic expressions in a continuous ICVI model for cylindrical pores. The predicted infiltration characteristics are compared with exptl. results. The final densification and Thiele modulus, i.e. a no. which is a measure for the diffusion limitations in a pore, are used for the evaluation of the presented model, and conditions are given for an optimal densification of a porous preform by the ICVI process for several binary compds. The deposition profiles as predicted by the model calcns. are in agreement with the exptl. detd. deposition profiles of TiN and TiC in small tubes. Moreover, it can be concluded that the shape of the deposition profiles is detd. by the heterogeneous reaction kinetics. There is only a qual. agreement between the predicted densification and measured densification for the synthesis of TiN and TiB2 in sintered porous alumina. This mismatch can be explained in terms of a complexity of the pore network and differences in reaction kinetics. Model calcns. reveal that there is a scattering for the predicted residual porosity as a function of the Thiele modulus for TiN. Moreover, this Thiele modulus can not fully account for the changes in densification at different temps. Given these uncertainties it is likely that a residual porosity of less than one percent can be obtained if the Thiele modulus is smaller than 1  10-4. However, a CVI process with such a small Thiele modulus will not be practical, because of the concomitant long process times.
Therefore, more precise conditions for the individual process parameters, i.e. concn., reactor pressure, and temp. are deduced from the model calcns.

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Pressure-pulsed chemical vapor infiltration of TiN into SiC particulate preforms. Sugiyama, K.; Sugata, M. Dep. Appl. Chem., Aichi Inst. Technol., Toyota, Japan. Journal of Materials Science (1996), 31(11), 2945-2949. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65198 AN 1996:378286 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC particulate preforms were infiltrated by TiN matrix from a gas mixt. of TiCl4 (5%), nitrogen (30%) and hydrogen using a repeating pressure pulse between 760 and about 1 torr. SiC particle sizes of 5 and 20 m were used. For matrix packing into deep level, optimum temp. was detd. between 800 and 850, and the max. packing ratio reached 67% after 4  104 pulses at 850. The increase of TiCl4 concn. to 10% resulted in higher deposition rate and packing ratio. The decrease of nitrogen concn. led to slower deposition, i.e., a similar effect to temp. lowering. The max. flexural strength measured was 140 MPa.

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Synthesis of mullite coatings by chemical vapor deposition. Mulpuri, Rao P.; Sarin, Vinod K. Dep. Mfg. Eng., Boston Univ., Boston, MA, USA. Journal of Materials Research (1996), 11(6), 1315-1324. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 125:39956 AN 1996:366859 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Formation of mullite on ceramic substrates via chem. vapor deposition was investigated. Mullite is a solid soln. of Al2O3 and SiO2 with a compn. of 3Al2O32SiO2. Thermodn. calcns. performed on the AlCl3-SiCl4-CO2-H2 system were used to construct equil. chem. vapor deposition (CVD) phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were detd. Through process optimization, cryst. CVD mullite coatings have been successfully grown on SiC and Si3N4 substrates. Results from the thermodn. anal., process optimization, and effect of various process parameters on deposition rate and coating morphol. are discussed.

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Mixed chromium and aluminum oxides elaborated by a sol-gel process. I. Chemistry of the preparation. Rezgui, Saloua; Ghorbel, Abdelhamid; Henry, Marc. Lab. Chimie Materiaux Catalyse, Dep. Chimie, Tunisia. Journal of Materials Synthesis and Processing (1995), 3(6), 371-376. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 125:16967 AN 1996:331762 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of mixed chromium and aluminum oxide were prepd. by a sol-gel process. The precursor is a mixt. of Al(O-s-Bu)3 and Cr(acac)3 with a mass ratio Al/Cr = 10 in sec-butanol. Gelation occurred by adding acetic acid. The amt. of added acetic acid is represented by the ratio k = [CH3COOH]/[Al(O-s-Bu)3], with k varying between 0.5 and 3. Acetic acid played crucial roles in both hydrolysis and polycondensation, (1) producing water in situ by esterification, (2) modifying the precursor by substituting some of the O-s-Bu ligands by acetate ligands, and (3) catalyzing the polycondensation. The importance of each of these roles in the process as well as the nature of the products varied with the ratio k.

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Influence of alloying elements on the chemical reactivity between Si-Al-O-N ceramics and iron-based alloys. Vluegels, J.; Vandeperre, L.; Van Der Biest, O. Dep. Metallurgy Materials Eng., Katholieke Univ. Leuven, Leuvan, Belg. Journal of Materials Research (1996), 11(5), 1265-1276. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 124:323490 AN 1996:293140 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. interaction between two '-O' Si-Al-O-N ceramics and a no. of iron-based alloys is studied by means of static interaction couple expts. at 1100 and 1200 C. The onset temp. of reaction of Si3N4 with pure iron was 1095 C, which is in good agreement with a calcd. temp. of 1033 C. During the interaction, silicon and nitrogen from the ceramic dissolve and diffuse into the iron alloy, whereas the remaining aluminum and oxygen form Al2O3 particles. The interaction between the ceramic and iron alloy is reaction controlled. In the initial stage of the interaction, the dissocn. rate of the ceramic is the rate-controlling step. After the ceramic/metal interface is isolated from the furnace atm., the nitrogen soln. rate into the iron alloy becomes rate controlling. The influence of alloying elements on the reactivity could be related to their effect on the nitrogen soly. in the iron alloy. Ni, Si, and C decrease the nitrogen soly. and decrease the reactivity with the Sialon ceramic. Cr and Mo have the opposite effect. The thickness of the interaction layer on the ceramic side of the interaction couple was found to be a function of the calcd. nitrogen soly. in the iron alloy at 1 atm nitrogen pressure, making it possible to predict the relative chem. reactivity of a no. of iron-based alloys with the same Sialon ceramic.

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Preparation and pressureless sintering of chemical vapor deposited SiC-B composite powder. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Institute Materials Research, Tohoku University, Sendai, Japan. Jo
urnal of Materials Science (1996), 31(3), 679-83. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 124:239925 AN 1996:180535 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-B composite powder was prepd. by chem. vapor deposition (CVD) using (CH3)2SiCl2 + B2H6 + H2 as source gases at 1673 K. The powder was -type polycryst. silicon carbide contg. several per cents of boron and carbon. The boron content increased from 0 to 7.7 mass% as the B2H6 gas concn. increased from 0 to 0.7 mol%. Boron and carbon in amorphous form dispersed homogeneously in the -SiC polycryst. particles. The particles were spherical, non-agglomerated and uniform in size with an av. particle size of about 50 nm. Sintering tests were performed with the resulting composite powder without applying pressure. Powder contg. 1 mass% boron and 2 mass% carbon was sintered to a d. of 3.16 x 103 kg m-3 at 2273 K, and the Vickers hardness of the sintered body was 30 GPa. When the sintering temp. was higher than 2323 K, significant grain growth due to the phase transformation from  to  form occurred, which decreased bulk d. and Vickers hardness.

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Nanocrystalline metals, intermetallics, and a metal-matrix nanocomposite by solution-based chemical reductions. Buhro, W. E.; Haber, J. A.; Waller, B. E.; Trentler, T. J.; Suryanarayanan, R.; Frey, C. A.; Sastry, S. M. L. Department Chemistry, Washington University, St. Louis, MO, USA. Polymeric Materials Science and Engineering (1995), 73 39-40. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 124:123490 AN 1996:951 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A metal salt soln. was reduced to nanocryst. and nanocomposite. CuCl in THF was reduced with NaBH4 to form nanocrystal Cu, and Ni and Al can also be prepd. in similar manner. NiCl2 soln. was reduced with LiAlH4 ti NiAl intermetallic compds. of nano size. MoCl5 and SiCl4 were reduced with NaK to nanocryst. MoSi2 in ultrasound field. TiB2 nanocryst. particles were suspended in THF and CuCl was reduced to obtain a Cu-coated TiB2 nanocomposite.

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Preparation of low density free-standing shape of SiC by pressure-pulsed chemical vapor infiltration. Sugiyama, K.; Norizuki, K. Dep. Applied Chem., Aichi Inst. Technology, Toyoda, Japan. Journal of Materials Science Letters (1995), 14(23), 1720-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 124:64057 AN 1995:1000853 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of the conditions of pressure-pulsed chem. vapor infiltration (PCVI) on the deposition rate, ease of substrate oxidn., gross d., and flexural strength in prepn. of low-d. free-standing SiC shapes were examd. By selection of a porous carbon substrate, highly porous SiC shapes with a desirable pore distribution may be prepd. by the PCVI process.

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Identification of chemical and physical change during acid cleaning of ceramics. Johnson, Jessica S.; Erickson, Harold M.; Iceland, Harry. Texas Mem. Mus., Univ. Texas, Austin, TX, USA. Materials Research Society Symposium Proceedings (1995), 352(Materials Issues in Art and Archaeology 4), 831-7. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 124:54897 AN 1995:985335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This report describes the results of two expts. characterizing chem. and phys. change in ceramic constituents occurring from acid solns. commonly used to remove deposits from the surface of archaeol. ceramics. The first examines the chem. effects of hydrochloric acid, in an attempt to identify the yellow color, commonly known as "acid burn", often seen in museum collections on black-on-white sherds found in the Southwestern U.S. The compd. is identified as Fe2O3H2O. The second study compares the phys. effects of different acids on a group of Maya sherds. All acids tested in this study were found to cause phys. damage.

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Influence of particle characteristics on sintering behavior of alumina-zirconia composites. Balasubramanian, M.; Malhotra, S. K.; Gokularathnam, C. V. FRP Research Center, Indian Inst. of Technology, Madras, India. Journal of Materials Science Letters (1995), 14(21), 1484-5. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:347792 AN 1995:927403 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A uniform distribution of zirconia particles in an alumina matrix can be achieved by chem. processing methods. Three chem. processing routes were used to obtain better powders. The sintered d. and the tetragonal ZrO2 content of composites were correlated with powder size and morphol.

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Wet air oxidation of energetics and chemical agent surrogates. Copa, William M.; Momont, Joseph A. Zimpro Environmental Inc., Rothschild, WI, USA. Journal of Energetic Materials (1995), 13(3&4), 235-58. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295590 AN 1995:895724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Wet oxidn. studies have been conducted on a no. of energetic materials and wastewaters derived from energetic materials to demonstrate high destruction levels of specific energetic components. Triple-base propellant, OTTO Fuel (used as torpedo propellant) and hydrazine-based rocket fuel were energetics of interest. Triple-base propellant contain nitrocellulose, nitroglycerin, and nitroguanidine. OTTO Fuel contains substantial amts. of propylene glycol trinitrate. Hydrazine based rocket fuel contains hydrazine and 1,1-di-Me hydrazine (asym. di-Me hydrazine or UDMH). A bench scale wet air oxidn. study on alk. hydrolyzates of triple-base propellants indicated that essentially complete destruction of the reactive nitrogen components could be achieved at an oxidn. temp. of 280. Bench scale wet air oxidn. studies on OTTO Fuel wastewaters indicated that a >99% destruction of propylene glycol dinitrate can be achieved at 280. Processing OTTO Fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved even higher destruction levels. Bench scale wet air oxidn. studies on hydrazine-based rocket fuel wastewaters indicated that a 99.8% destruction of hydrazine and a >99.0% destruction of 1,1-dimethylhydrazine can be oxidized at 280. Again, processing of hydrazine-based rocket fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved similar destruction levels. The application of wet air oxidn. for the destruction of chem. agents has been made by the extrapolation of data from the wet air oxidn. of compds. with similar chem. structures or of surrogate compds. Sarin and V-agents are nerve agents which have an organo-phosphorus structure similar to that of contain commonly used pesticides. Pesticides such as glyphosate and malathion, which have a similar organo-phosphorus structure, are essentially completely destroyed (>99% destruction) by wet air oxidn. at 200-280. The chem. agent surrogate, di-Me Me phosphonate (DMMP) was wet air oxidized at 220-280. Alk.
hydrolyzed DMMP was wet air oxidized at 280. All of the oxidized effluents showed a >97.5% destruction efficiency for the DMMP. The blister agent, mustard (HD) is a chlorinated sulfide, bis(2-chloroethyl) sulfide. Org. sulfides such as mercaptans can be destroyed by wet air oxidn. at 260-280. It is concluded that the wet air oxidn. process is a promising alternative to incineration for disposal of energetics and chem. warfare agents.

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Molten salt oxidation of chemical munitions. Stewart, Albert; Schnittgrund, Gary. PyroPacific Processes, Grand Hills, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 213-34. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295589 AN 1995:895723 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molten salt oxidn. is reviewed as a potential near term alternative technol. for the destruction of chem. agents. Initial tests completed by the US Army in 1975 showed the promise of achieving very high removal efficiencies on actual agents. Recent testing by DOE has verified the potential for very low PIC and dioxin or furan releases. To further explore the possible application of this technol. to chem. agent destruction, a molten salt reactor and assocd. equipment was designed to process a nominal 50 kg/h of Sarin. Mass and energy balances are presented for process conditions representing a range of molten salt potential operational modes and schemes for enhancing plant capacity. Process economics are presented.

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Supercritical water oxidation of chemical agents, and solid propellants. Spritzer, M. H.; Hazlebeck, D. A.; Downey, K. W. San Diego, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 185-212. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295588 AN 1995:895722 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Supercrit. water oxidn. (SCWO), also referred to as hydrothermal oxidn. (HTO), is a developing technol. for the destruction of hazardous and nonhazardous wastes. SCWO destroys combustible materials using an oxidant in water at 350-600 and pressures of 17 MPa. General Atomics and its subcontractors are currently conducting 2 comprehensive research and demonstration programs geared toward the destruction of Department of Defense (DoD) wastes utilizing SCWO technol. Wastes of primary interest include chem. agents and solid propellants. Tech. challenges, particularly corrosion and solids handling, were overcome, and the destruction of chem. agents and solid propellants was demonstrated on a bench scale. SCWO results for chem. agents show destruction and removal efficiencies for GB, VX, and mustard agents to be in excess of 99.9999%, limited only by detection capability. SCWO results for hydrolyzed Class 1.1 solid propellant show destruction and removal efficiencies for total org. carbon (TOC) of >99.9%. Design and fabrication of a transportable SCWO pilot plant for chem. warfare agents, propellants and other DoD hazardous wastes and a prototype HTO system for solid rocket propellant disposal are complete and demonstration testing is underway.

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Pressure pulsed chemical vapor infiltration of SiC to two-dimensional-Tyranno/SiC-C preforms. Sygiyama, Kohzo; Yoshida, Yazutoshi. Department of Applied Chemistry, Aichi Institute of Technology, Toyoda, Japan. Journal of Materials Science (1995), 30(20), 5125-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:320390 AN 1995:894944 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preforms of two-dimensional Tyranno fiber (SiC base) of 7  20  1.3 mm3 were chem. vapor infiltrated with SiC at 850-1050C from a gas mixt. of CH3SiCl3 (6%)-H2 using pressure pulses between below 0.3 kPa and 0.1 MPa. Above 900C, films grew on the macrosurface dominantly. At 850C, residual porosity decreased to about 10% after 105 pulses, and three point flexural strength reached about 200 MPa. X-ray diffractograms on the surface showed the deposits to be -SiC only.

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Matrix characterization of fiber-reinforced SiC matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M.; More, K. L.; Sheldon, B. W.; Besmann, T. M.; Headinger, M. H.; Davis, R. F. Oak Ridge National Laboratory, Oak Ridge, TN, USA. Journal of Materials Science (1995), 30(17), 4279-85. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:206673 AN 1995:804167 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ceramic matrix composites (CMCs), that consist of silicon carbide (SiC) reinforced with continuous Nicalon or T-300 fibers, are being developed for many high-temp. structural applications. The large potential use of CMCs has prompted an in-depth investigation and characterization of these materials. Electron microscopy and micro-Raman spectroscopy were used to characterize and compare the SiC matrix crystal structure and morphol. of composite materials fabricated by two different chem. vapor infiltration (CVI) processes.

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Characterization of pseudo-porous SiC/C coatings on NextelTM 440 and NicalonTM fibers. Khasgiwale, N. R.; Butler, E. P.; Tsakalakos, L.; Hensley, D. A.; Cannon, W. R.; Danforth, S. C.; Gonczy, S. T. Center Ceramic Research, Rutgers University, Piscataway, NJ, USA. Materials Research Society Symposium Proceedings (1995), 365 395-400. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177329 AN 1995:774261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Pseudo-porous SiC/C coatings were deposited on NextelTM 440 and NicalonTM fibers by CVD. The morphol. and chem. of the coatings was evaluated, both before and after oxidn., using SEM, X-Ray Diffraction Anal. (XRD), XPS and Auger spectroscopy. Coated fibers were subjected to two different oxidn. treatments to assess coating stability: a) oxidn. at 600C for 20 h, and b) oxidn. at 1000C for 20 h. Pseudo-porous SiC/C on NicalonTM fibers appear to be more oxidn. resistant than the same coatings on NextelTM440 fibers.

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The preparation and economics of silicon carbide matrix composites by chemical vapor infiltration. Roman, Yvette G.; Stinton, David P. Centre Technical Ceramics-TNO, Eindhoven, Neth. Materials Research Society Symposium Proceedings (1995), 365 343-50. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 123:176964 AN 1995:774254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 35 refs. A no. of processing techniques that are currently in use for the development and prodn. of continuous fiber reinforced ceramic composite materials are described. The limited no. of available processing routes are compared with respect to the resulting material properties. The chem. vapor infiltration (CVI) technique is one of the most extensively developed methods. During the last decade, at least five different modifications of the isobaric isothermal CVI principle have been developed; each route having its own benefits. CVI techniques have now been developed to the extent that industrial commercialization is being realized. Projected cost aspects of the various CVI manufg. techniques are examd. and compared.

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Properties of SiC-SiC composites produced using CVR converted graphite cloth to SiC cloth. Kowbel, W.; Kyriacou, C.; Gao, F.; Bruce, C. A.; Withers, J. C. MER corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1995), 365 197-202. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177312 AN 1995:774236 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a new SiC reinforcement based upon a conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. This new SiC filaments exhibit an excellent creep resistance at temps. up to 1600C. Several SiC-SiC composites were fabricated using graphite fabric converted to SiC fabric utilizing the CVR process combined with a slurry infiltration and CVI densification. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites are discussed.

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Chemically bonded ceramic matrix composites: densification and conversion to diffusion bonding. Johnson, Bradley R.; Guelguen, Mehmet A.; Kriven, Waltraud, M. Department Materials Science and Engineering, University Illinois, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1995), 365 67-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177295 AN 1995:774216 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC's). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl2O4) powders were used as the chem. bonding matrix phase, while calcia-stabilized zirconia powders were the second phase material. Samples contg. up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal anal. (DTA/TGA). The phys. characteristics of this novel CMC were characterized by hardness, d., and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD.

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Oxidative catalytic decomposition of toxic gases using hydroxyapatite and fluorhydroxyapatite. Palucka, Timothy P.; Eror, Nicholas G.; McNamara, Thomas A. Department Materials Science and Engineering, University Pittsburgh, Pittsburgh, PA, USA. Materials Research Society Symposium Proceedings (1995), 368(Synthesis and Properties of Advanced Catalytic Materials), 275-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:151604 AN 1995:734790 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An oxidative catalytic route to decomp. nerve gases was studied using hydroxyapatite (HA, Ca10(PO4)6(OH)2) and its partially fluorinated analog fluorhydroxyapatite (FHA, Ca10(PO4)6Fx(OH)2-x). Samples were prepd. with surface areas of 34-238 m2/g to study surface area effects; 1.2 wt.% Pt was deposited on 1 substrate to study the effect of a transition metal on activity and selectivity. Reaction studies were performed using di-Me methylphosphonate, a nerve gas simulant, in a stream of 80% N and 20% O at 573 K and atm. pressure. High surface area FHA samples showed an increase in the protection period (period of 100% conversion) with increasing F substitution; such an increase was not seen for low surface area FHA samples. In the absence of Pt, the reaction products were CH3OH and di-Me ether; with Pt, CO2 was also obtained.

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Toxicity of sulfur mustard in adult rat lung organ culture. Sawyer, Thomas W.; Wilde, Paul E.; Rice, Paul; Weiss, M. Tracy. Medical Countermeasures Section, Defence Research Establishment Suffield, Box 4000, Medicine Hat, Alberta, Can. Toxicology (1995), 100(1-3), 39-49. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 123:104668 AN 1995:700024 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The toxicity of the chem. warfare agent sulfur mustard, (bis-(2-chloroethyl)sulfide, HD), was examd. in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concn. (LC50) of HD in these cultures was reproducible, and in the M range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathol. examn. of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochem., and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulfur mustard.

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Characterization and surface chemistry of uncoated and coated silicon nitride powders. Schmidt, H.; Nabert, G.; Ziegler, G.; Goretzki, H. Inst. Materialforschung, Univ. Bayreuth, Bayreuth, Germany. Journal of the European Ceramic Society (1995), 15(7), 667-74. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 123:90766 AN 1995:695131 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various Si3N4 powders, produced by different procedures, were characterized by imaging (TEM) and anal. methods (EDS, FT-IR, XPS) in the as-received state as well as after doping with a metal oxide (MgO). For the doping, an alternative procedure to the usual methods was applied based on sol. organometallic compds. Anal. TEM combined with lateral resoln. element anal. and XPS measurements was used for morphol., structural and anal. characterization. The distribution of the dopant was deduced from measurements of XPS sputter depth profiles. These investigations were supplemented by FT-IR measurements to det. qual. and semi-quant. the reactive groups on the particle surfaces of the as-received powders. For comparison, measurements were performed with Si3N4 powders which were doped by the above chem. procedure and by mech. mixing. The results of the various characterization methods are interpreted in the form of a model display for surface reactions of organometallic doping reagents on the surfaces of ceramic particles. The results show that Si3N4 powders with high concn. of OH groups on their particle surface reveal very good distribution of the fluxing element (layer-like coating).

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Influence of crystallographic orientation, chemical inhomogeneities, material transport anisotropy and elastic strain energy on the migration of grain boundaries in chromium-doped alumina during internal reduction. Backhaus-Ricoult, Monika; Peyrot-Chabrol, A.; Chiron, R.; Hagege, S. Cent. d'Etudes Chim. Metall., CNRS, Vitry, Fr. Materials Research Society Symposium Proceedings (1995), 357(Structure and Properties of Interfaces in Ceramics), 293-9. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:90732 AN 1995:685875 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Diffusion-induced grain boundary migration is obsd. during internal redn. of chromium-doped alumina. It occurs because grain boundary diffusion is fast compared to lattice diffusion of oxygen. The oxygen chem. potential relaxes between grain boundaries and adjacent grains. Migration to either side of the boundary is controlled by multiple factors: chem. compn. differences between adjacent grains, elastic strain energy differences on the two sides of the boundary plane or by more rapid oxygen relaxation when the c-axis of a grain is perpendicular to the boundary plane.

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Synthesis and chemical stability of NaSn2P3O12. Breval, E.; Harshe, G.; Agrawal, D. K.; Limaye, S. Y. Intercoll. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Journal of Materials Science Letters (1995), 14(10), 728-31. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:39204 AN 1995:606064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

NaSn2P3O12 and NaZr2P3O12 powders were prepd. by solid-state reaction methods and sintered at 1050-1200. The resulting pellets were characterized in terms of d., thermal expansion, and phase compn. before and after chem. stability tests. Chem. stability tests were performed in polethylene containers in 3 solns., H+ + SO42- (pH = 0.5), Na+ + H+ + SO42- (pH = 0.7), and Na+ + OH- (pH + 14.3). Results indicate that NaSn2P3O12 is a very stable NZP compd. in high and low pH solns. (pH + 0.5-14.3) as compared to the parent compn. NaZr2P3O12, which shows high losses, esp. in alk. leachants. The surface-to-vol. of a single phase NaSn2P3O12 material, sintered without sintering agents, hardly affects the dissoln. Use of a sintering agent may result in a highly reactive grain boundary phase, the amt. of which may exceed the amt. of added sintering aid.

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Low-level detection of chemical agent simulants in meat and milk by ion trap mass spectrometry. Buchanan, Michelle V.; Hettich, Robert L.; Xu, Jing Hai; Waters, Larry C.; Watson, Annetta. Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Building 5510, MS/6365, Oak Ridge, TN, USA. Journal of Hazardous Materials (1995), 42(1), 49-59. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 123:31526 AN 1995:596587 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. methods for the detection of two chem. warfare agent simulants, diisopropyl methylphosphonate and chloroethylethylsulfide, in beef tissue and milk were demonstrated to be effective to levels as low as 50-100 ppb. These methods are based upon thermal desorption into an ion trap mass spectrometer. Selective detection of the target compds. is achieved by isobutane chem. ionization in combination with collision-induced dissocn., which yields characteristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limits achieved with this method suggest that it may be possible to take small tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the anal. In addn., because the new methods may be performed more quickly than conventional methods requiring substantial sample prepn. and anal. time, more samples could be analyzed.

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The effect of ceria co-doping on chemical stability and fracture toughness of Y-TZP. Boutz, M. M. R.; Winnubst, A. j. a.; Van Langerak, B.; Scholtenhuis, R. J. M. Olde; Kreuwel, K.; Burggraaf, A. J. Faculty of Chemical Technology, University of Twente, Enschde, Neth. Journal of Materials Science (1995), 30(7), 1854-62. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 122:271892 AN 1995:504770 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and ageing resistance of yttria, ceria-stabilized tetragonal zirconia polycrystals (Y, Ce-TZP) were evaluated as a function of grain size and ceria content. Very fine grained, fully dense materials could be produced by sinter forging at relatively low temps. (1150-1200C). The aging resistance in hot water (185C) of 2 mol% Y2O3-stabilized TZP is strongly enhanced by alloying with ceria. The ceria content necessary to avoid degrdn. completely, decreases with grain size. The toughness of fully dense Y, Ce-TZP is 7-9 MPa m1/2 for grain sizes down to 0.2 m. No or very little transformation took place during fracturing and no clear variation with grain size was obsd. for the toughness at grain sizes up to 0.8 m. Reversible transformation and crack deflection may explain the obsd. toughness values.

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Microstructure and chemistry of second phases in MgO- and NiO-codoped alumina by analytical transmission electron microscopy. Park, K.; Vasilos, T.; Sung, C. Cent. Advanced Materials Dep. Chem. Nuclear Eng., Univ. Massachusetts, Lowell, MA, USA. Journal of Materials Science Letters (1995), 14(4), 261-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 122:167982 AN 1995:415637 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects MgO-NiO-codoping on microstructure and chem. of 2nd phases, segregated particles and cryst. defects in alumina ceramics were examd. MgO-NiO-codoping contributed significantly to the prepn. of dense fine-grained alumina. It appeared that Ni-Al and Ni-Mg-Al spinels, segregated Ni particles, and K-'' alumina ppts. were formed at triple points or at grain boundaries, because the concns. of the MgO and NiO dopants were higher than their solid solubilities. In particular, the codopants formed a Ni-Mg-Al spinel as well as a Ni-Al spinel, because Mg2+ and Ni2+ were partitioned in the cation position of the spinel structure.

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Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry. Bentley, J.; Horton, L. L.; McHargue, C. J.; McKernan, S.; Carter, C. B.; Revcolevschi, A.; Tanaka, S.; Davis, R. F. Metals and Ceramics Div.r., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1994), 332(Determining Nanoscale Physical Properties of Materials by Microscopy and Spectroscopy), 385-90. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:87360 AN 1995:266442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resoln. of <5 nm. Anal. of Fe L23 white lines indicates a low-spin state with a charge transfer of .apprx.1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2-5% in the Co:O stoichiometry were measured across 100-nm-thick Co3O4 layers in an oxidized directionally solidified CoO-ZrO2 eutectic, with the highest O levels near the ZrO2. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for Co3O4 have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid soly. occurred in an AlN-SiC film grown by low-temp. mol. beam epitaxy (MBE) on (6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycryst. AlN on SiC, interfacial 8H Sialon (aluminum silicon oxynitride) and pockets of Si3N4-rich '-Sialon in the SiC were detected.

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Chemically bonded ceramics as an alternative to high temperature composite processing. Gulgun, Mehmet A.; Johnson, Bradley R.; Kriven, Waltraud M. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1994), 346(Better Ceramics through Chemistry VI), 511-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:15230 AN 1995:174876 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Processing of multi-phase ceramic composite materials using chem. bonded ceramics as a binding agent appears to be a promising route for fabricating complex-shaped structures. In a zirconia-calcium aluminate ceramic matrix composite, the hydraulic property of fine, monocalcium aluminate (CaAl2O4) powders was used to prep. strong prefired bodies. The changes in the phys. characteristics of the composite during the conversion from a chem. bonded compact into a sintered composite were studied using thermogravimetric analyses (TGA), X-ray diffraction and SEM. The d. and the hardness of the chem. bonded and sintered composite were measured.

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Assessing delayed neurotoxicity in rodents after nerve gas exposure. Husain, K.; Pant, S. C.; Vijayaraghavan, R.; Singh, Ram. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(2), 161-4. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:294553 AN 1994:694553 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Delayed neurotoxicity of an organophosphorus nerve gas, Sarin (a chem. warfare agent) following repeated inhalation exposure in rats and mice, was studied by behavioral, biochem. and histopathol. analyses. Rats exposed to Sarin aerosols (12.5 mg/m3 for 20 min) daily for ten days did not exhibit any clin. sign of delayed neurotoxicity. Neurotoxic esterase (NTE) activity in the brain, spinal cord and platelets was significantly inhibited, but the inhibition was below the threshold. Histopathol. examn. of spinal cord did not show any axonal degeneration. Mice exposed to Sarin aerosols (5 mg/m3 for 20 min) daily for ten days developed mild ataxia and muscular weakness of the hind limb on 14th day after the start of exposure. NTE activity was significantly inhibited in brain, spinal cord and platelets. Histopathol. of spinal cord showed focal axonal degeneration. Acetyl-choline esterase activity in the platelets of both the animals was significantly inhibited. The authors conclude that mice are sensitive to delayed neurotoxicity induced by repeated exposure to Sarin whereas rats are insensitive.

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Clean-up of chemical warfare agents on soils using simple washing or chemical treatment processes. Amos, Denys; Leake, Brian. DSTO, Aeronautical and Maritime Research Laboratory, P.O. Box 4331, Melbourne, Victoria, Australia. Journal of Hazardous Materials (1994), 39(1), 107-17. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:262645 AN 1994:662645 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several simple processes have been studied for the destruction of chem. agents, Soman and Mustard, on soils. A double wash or an extended single wash with water was effective in removing Mustard and Soman from soil; addn. of either anionic or cationic surfactant did not improve removal efficiency. Soils with higher org. carbon content were more difficult to decontaminate. The most effective chem. process for the removal of Mustard was treatment with hypochlorite; treatment with Na2CO3 or NaOH were almost as effective as hypochlorite in cleaning Mustard contaminated soil. Soman was removed most effectively by treatment with Na2CO3. Overall the most efficient process for the destruction of both Mustard and Soman was treatment with Na2CO3 soln.

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Liquid phase sintering, electrical conductivity, and chemical stability of lanthanum chromite doped with calcium and nickel. Christie, G. M.; Middleton, P. H.; Steele, B. C. H. Dep. Mater., Imperial Coll. Sci., Tech. Med., London, UK. Journal of the European Ceramic Society (1994), 14(2), 163-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:236480 AN 1994:636480 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The substitution of 10 mol% nickel for chromium in calcium-doped lanthanum chromite has been shown to promote rapid densification of the compd. at low temps. in air by the form of a transient liq. phase. Liqs. were generated via the decompn. of CaCrO4 second phase material present in calcined powders. During elec. cond. measurements at 1000C, severe microstructural degrdn. occurred at atms. of H2 and CO2. The processes leading to chem. degrdn. are attributed to the pptn. of Ni from the (La,Ca)(Cr,Ni)O3 solid soln. and to the decompn. of small amts. of residual CaCrO4 which remains at grain boundaries and triple points after sintering. DTA studies on CaCrO4 in CO2 and H2 atms. suggested that the degrdn. due to CaCrO4 decompn. was primarily a result of the reaction of CaO with CO2 to form CaCO3. The presence of H2 gas is thought to catalyze this reaction via the formation of large amt. of CaO during the decompn. of CaCrO4. Degrdn. is more severe in atms. contg. a mixt. of CO2 and H2 gases than in either gas on its own.

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Photochemical degradation of a toxic organophosphorus analog (PMSF) in microemulsion media. Yang, Yun; Donegan, Sheila; Patel, Ramesh C.; Ward, Anthony J. I. Center for Advanced Materials Processing, Clarkson University, Potsdam, NY, USA. Chemosphere (1994), 28(11), 1967-76. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 121:217331 AN 1994:617331 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A study has been made of the photodegrdn. of an analog, phenylmethylsulfonyl fluoride (PMSF), of a toxic chem. warfare agent. The agent was solubilized in a water-in-oil surfactant stabilized microemulsion system comprising sodium dodecyl sulfate, pentanol and water. Loss of the parent PMSF mol. upon exposure of the system to UV irradn. was monitored by 19F NMR spectroscopy. Consideration of the changes in the chem. shifts, splittings in conjunction with GC/Mass spectroscopy data strongly suggest the degrdn. leads to partial fluorination of pentanol. Anal. of peak areas also indicates the formation of volatile degrdn. products such as HF. The addn. of TiO2 or hydroquinone to the system did not appreciably change the overall amts. of degrdn. The results are interpreted in terms of the possible radical based reaction pathways and show that such a microemulsion medium to have significant potential as a vehicle for effecting such a degrdn. process.

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Comparative evaluation of high protein against normal protein diet in combination with carbamates against organophosphorus intoxication in rats. Chatterjee, A.K.; Sikder, Nirmala; Sikder, A.K. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(1), 11-14. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:197892 AN 1994:597892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The relative efficacy of an isocaloric high protein diet (HPD) contg. 59 per cent protein, in comparison to a conventional diet contg. 21 per cent protein, as applied in the alleviation of toxicity of diisopropyl phosphorofluoridate (DFP) and Me iso-Pr phosphonofluoridate (sarin), has been reported. In combination with well-known prophylactics like carbamates and cholinolytics like atropine against nerve gas toxicity, HPD appears to be superior to the conventional diet as studied by survival time measurements. Apart from carbamates, atropine and mecamylamine, HPD may be treated as an addnl. prophylactic agent to guard against the toxicity of DFP and sarin, which are being used as war chems.

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The surface chemistry of silicon nitride powder in the presence of dissolved ions. Hackley, V. A.; Malghan, S. G. Ceram. Div., Natl. Inst. Standards and Technol., Gaithersburg, MD, USA. Journal of Materials Science (1994), 29(17), 4420-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 121:185440 AN 1994:585440 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Colloidal processing of silicon nitride (Si3N4) powders depends largely on the control of reactions at the solid-soln. interface. The role of dissolved ions in the surface chem. of Si3N4 powders has been investigated, and the implications of these results for the effects of impurities, contaminants and additives in processing are discussed. The interaction of ions at the solid-soln. interface was characterized by particle electrokinetic behavior detd. from electroacoustic measurements in moderately concd. suspensions. Ions were classified according to chem. similarity and surface specificity. Specific adsorption was inferred from the movement of the isoelec. point relative to the endemic "native" value. Most simple univalent electrolytes behaved indifferently towards the Si3N4 surface, with the exception of fluoride which specifically adsorbed and may have formed a strong complex with surface silicon sites. The alk.-earth cations exhibited a similar weak specificity. In the presence of hydrolyzable transition metal cations, powder surface chem. was controlled by the adsorption of hydroxy metal complexes and by the soly. of a surface-pptd. metal hydroxide phase. Oxo anions, such as sulfate and carbonate, adsorbed specifically on the Si3N4 surface, but the interactions were weaker than previously obsd. on metal oxide surfaces.

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X-ray photoelectron spectroscopy of uv laser irradiated sapphire and alumina. Pedraza, A. J.; Park, J. W.; Meyer, H. M., III; Braski, D. N. Dep. Materials Science Engineering, Univ. Tennessee, Knoxville, TN, USA. Journal of Materials Research (1994), 9(9), 2251-7. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 121:162453 AN 1994:562453 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

XPS was performed in as-received, thermally annealed, and laser-irradiated sapphire and alumina specimens to study the effects of the different treatments on surface chem. and properties. Laser irradiations with a 308 nm wavelength laser were performed in air and in a reducing atm. consisting of a mixt. of Ar and 4% hydrogen. The at. percentages of carbon, aluminum, and oxygen were measured in all the specimens. Particular attention was paid to the percentages of oxygen in the oxide and in a hydroxyl state. The XPS analyses clearly established that a very thin film of metallic aluminum is formed on the surface of both alumina and sapphire substrates when they are irradiated under a reducing atm. However, the film is discontinuous because it is elec. insulating. Substrates irradiated in air have metallic aluminum only for fluences below 0.4 J/cm2. The valence band photoemission spectra of as-received, annealed, and laser-irradiated specimens were measured. In irradiated specimens, the width of the valence band spectra was found to decrease by .apprx.10%. One possible cause of this decrease is the generation of point defects during laser irradn. Electroless copper deposition occurs on sapphire and alumina substrates if their surface has been activated by laser irradn. The time required for copper deposition was monitored by measuring the elec. resistivity in the irradiated area while the substrates were immersed in an electroless bath. The kinetics of deposition on laser-activated substrates and the XPS results show that the presence of metallic aluminum accelerates the deposition process. However, the presence of aluminum is not the sole reason for laser activation in alumina. Very strong metal-ceramic bonding is produced after thermal annealing of samples having preirradiated substrates. This result is explained in terms of the excess oxygen that is present at the ceramic surface after irradn.

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X-ray absorption spectroscopy study of the local structure and the chemical state of yttrium in polycrystalline -alumina. Loudjani, M. K.; Cortes, R. Lab. Metallurgie Structurale, CNRS, Orsay, Fr. Journal of the European Ceramic Society (1994), 14(1), 67-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:162396 AN 1994:562396 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. state and local structure around the yttrium ion in doped polycryst. -alumina (0.03  mol% Y2O3  1) system was examd. by extended x-ray absorption fine structure (EXAFS) measurements for yttrium K-edge energy. In the case of highly doped alumina samples (0.1 and 1 mol% Y2O3) most of the yttrium is pptd. as a Y3Al5O12 phase, whereas in the dil. doped alumina sample (0.03 mol% Y2O3) yttrium is in solid soln., being located on the octahedral aluminum sites. The yttrium ion size, comparatively greater than that of the aluminum ion, induces locally a significant distortion of the oxygen ion lattice. This effect creates point defects in the nearest neighbor shell of the yttrium: vacancy (Vo..) and interstitial (Oi'') oxygen point defects.

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Constitution of the -alumina phase in chemically produced mullite precursors. Schneider, H.; Voll, D.; Saruhan, B.; Schmucker, M. Inst. Mater. Res., German Aerosp. Res. Establ., Cologne, Germany. Journal of the European Ceramic Society (1993), 13(5), 441-8. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:89568 AN 1994:489568 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The temp. development of type II mullite precursor powders have been studied in the temp. range of 150C (as-received) and 1150C. X-ray diffraction measurements, IR and 29Si and 27Al NMR spectroscopy and anal. transmission electron microscopy have been performed on the heat-treated precursors. The investigations had the aim of contributing to the frequently discussed question, whether Si is incorporated into the -alumina spinel being formed as a transient phase in type II mullite precursors. The as-received precursors consist of relatively large spherical particles ( 05 m) of noncryst. SiO2 and of much finer-grained agglomerates of pseudo-boehmite crystals (-AlO(OH),  20 nm), which are embedded in a SiO2 matrix. Above 350C, pseudo-boehmite transforms to spinel-type alumina (-Al2O3). During this transformation, all Si existing in the SiO2 matrix of the pseudoboehmite agglomerates is incorporated into -Al2O3 corresponding to a SiO2 content of 12 mol% at 500C. Up to 750C, the SiO2 content of the -alumina remains const. but above this temp. it gradually rises and reaches a max. amt. of 18 mol% at 1150C. A marginal decompn. of the spherical non-cryst. SiO2 particles may be the sources to provide diffusion of Si species into the -alumina during a temp. increase above 750C. It is most likely that Si species diffuse into the -alumina crystals along the crystallite boundaries. The diffusion process and Si incorporation are facilitated with the temp. increase.

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Quantitative analysis of Si3N4 microstructure response on interface chemistry. Meissner, E.; Unger, S.; Kleebe, H.-J.; Ziegler, G. Univ. Bayreuth, Bayreuth, Germany. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 471-5. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:89560 AN 1994:489560 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. microstructure anal. was performed on gas-pressure sintered Si3N4 materials (SSN) by employing an image processing system. Variations in grain-diam. distribution and aspect-ratio distribution with changing additive compn. and annealing time, resp., were investigated. Clear evidence was found that both interface compn. and post-sintering anneal can strongly affect the matrix grain morphol. For the Y2O3-doped material, extended annealing time supported the formation of Si3N4 grains with increased diam. and length via Ostwald ripening. Moreover, the aspect-ratio distribution was shifted to higher values indicating anisotropic grain growth. The addn. of Al2O3 + ZrO2, compared to SSN doped with Y2O3, resulted in a finer microstructure with still high aspect ratios. This chem. effect is closely related to the viscosity of the liqs. at processing temps. Furthermore, ZrO2 addn. results in a more pronounced transgranular fracture mode, while Y2O3-contg. SSN predominantly revealed intergranular fracture. The influence of annealing time and interface chem. on both microstructure evolution and resulting fracture toughness is discussed.

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Surface chemical interactions of Si3N4 with polyelectrolyte deflocculants. Hackley, V.A.; Premachandran, R.; Malghan, S.G. Mater. Sci. Eng. Lab., Natl. Inst. Stand. Technol., Gaithersburg, MD, USA. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 679-82. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:41008 AN 1994:441008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interaction of org. polyelectrolyte deflocculants at the Si3N4 solid-soln. interface was investigated using electroacoustic measurements, polymer adsorption and particle size distribution anal. One cationic and two anionic polymers were studied: quaternized poly(diamine epoxychlorohydrin), ammonium poly(methacrylate) and poly(acrylic acid), resp. Electrostatic interactions are emphasized as a function of pH, concn. and mol. wt.

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Metabolite pharmacokinetics of soman, sarin and GF in rats and biological monitoring of exposure to toxic organophosphorus agents. Shih, Ming L.; McMonagle, Joseph D.; Dolzine, Theodore W.; Gresham, Vincent C. US Army Med. Res. Inst. Chem. Def., Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1994), 14(3), 195-9. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 121:28848 AN 1994:428848 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study reports on the pharmacokinetics of the elimination of the metabolites of three toxic organophosphorus compds. (soman, sarin and GF). Urine, blood and lung tissue were collected from rats dosed s.c. at 75 g kg-1. Urinary excretion of the metabolite was the major elimination route for these three compds. The major differences among them were primarily the extent and rate of excretion. The hydrolyzed form, alkylmethylphosphonic acid, was the single major metabolite formed and excreted in urine by a non-saturable mechanism. Nearly total recoveries of the given doses for sarin and GF in metabolite form were obtained from the urine. The terminal elimination half-lives in urine were 3.7  0.1 and 9.9  0.8 h for sarin and GF, resp. Soman metabolite showed a biphasic elimination curve with terminal half-lives of 18.5  2.7 and 3.6  2.2 h. Soman was excreted at a slower rate with a recovery of only 62%. Lung was the major organ of accumulation for soman. In blood the toxic agents were concd. more in red blood cells than in plasma. The acid metabolites can serve as a better chem. marker for monitoring organophosphorus exposure in humans via their higher concn. and longer half-life in urine than the parent compds.

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Movement of chemical warfare agent simulants through porous media. Jenkins, R. A.; Buchanan, M. V.; Merriweather, R.; Ilgner, R. H.; Gayle, T. M.; Watson, A. P. Analytical Chemistry Division, Oak Ridge National Laboratory, Building 4500S, MS-6120, P.O. Box 2008, Oak Ridge, TN, USA. Journal of Hazardous Materials (1994), 37(2), 303-25. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:16666 AN 1994:416666 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A measurement protocol is documented and data are presented to characterize the permeation of chem. warfare agent simulants through the porous construction materials brick, cinder block, gypsum wall board, and wood. These data will be used to develop guidelines for access ("reentry") to potentially contaminated properties if nerve or vesicant agents are released during any phase of the US Department of the Army's Chem. Stockpile Disposal Program. A novel permeation cell design allowed sampling of air vols. adjacent to the spiked face, breakthrough face, and lateral face of each test medium at two temps. Simulant movement through wood is nearly always in the direction of the wood grain. Two-dimensional breakthrough was obsd. in brick and gypsum wall board. The sulfur mustard simulant broke through all test media in less than 60 min; nerve agent simulant breakthrough required several hours. Surface decontamination of wood with high-test hypochlorite is 95% effective.

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Pharmacology of organophosphates. Koelle, George B. Med. Sch., Univ. Pennsylvania, Philadelphia, PA, USA. Journal of Applied Toxicology (1994), 14(2), 105-9. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 121:2654 AN 1994:402654 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 8 refs. The cholinergic nerve fibers, which employ acetylcholine (ACh) as a neurohumoral transmitter, and the results of their activation are listed. The reactions between the enzyme acetylcholinesterase (AChE), its natural substrate, ACh, and the various types of inhibitors are described. The limited therapeutic uses of the anticholinesterase (anti-ChE) agents are considered. The toxicol. effects encountered when the anti-ChE agents are employed as insecticides or as chem. warfare (CW) agents are discussed. Certain anti-ChE agents produce also a delayed neurotoxic effect which is apparently unrelated to the inhibition of AChE.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson, Barry W.; Kawakami, Thomas G.; Cone, Norman; Henderson, John D.; Rosenblatt, Leon S.; Goldman, Marvin; Dacre, Jack C. Inst. Toxicol., Univ. California, Davis, CA, USA. Toxicology (1994), 86(1-2), 1-12. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 120:263586 AN 1994:263586 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (tabun, phosphoramidocyanidic acid, dimethyl-, Et ester) as part of a program to demilitarize chem. warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but not in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only 3 of the 5 assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Effect of chemically added zirconia and yttria mechanical properties of zirconia-dispersed alumina. Ranjbar, Khalil; Rao, Boddapati T.; Mohan, Tallapragada R. Rama; Harendranath, Chilkunda S. Dep. Metall. Eng., Indian Inst. Technol., Bombay, India. American Ceramic Society Bulletin (1994), 73(2), 63-6. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 120:171374 AN 1994:171374 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Alumina powders dispersed with monoclinic, tetragonal, and cubic zirconia were prepd. by evapg. a colloidal dispersion of alumina powders in solns. contg. zirconium and yttrium salts. The dried and calcined powders were compacted, sintered, and characterized. The results demonstrated a clear toughening effect by the zirconia on the alumina ceramics. The alumina contg. 20-wt%-yttria-stabilized tetragonal zirconia had the max. toughness.

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Chemical vapor infiltration of silicon carbide with microwave heating. [Erratum to document cited in CA119(2):13852e]. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(12), 3251. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 120:141948 AN 1994:141948 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The errors were not reflected in the abstr. or the index entries.

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Chemical compatibility between silicon-based and titanium-based ceramics. Wang, L.; Wada, H. Dep. Mater. Sci. Eng., Univ. Michigan, Ann Arbor, MI, USA. Journal of Materials Synthesis and Processing (1993), 1(3), 181-93. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:277176 AN 1993:677176 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. compatibility between Si-based ceramics and Ti-based ceramics was studied to establish guidelines for the processing of related composites. Phase stabilities were calcd. for the Si-Ti-B-C, Si-Ti-B-N, and Si-Ti-B-C-N systems as a function of B activity and N pressure or C activity. SiC is compatible with TiC, TiN, or TiB2, depending on the range of these parameters. Si3N4 and TiN appear to be compatible in a certain range of N2 pressure and C activity, but Si3N4 and pure TiC will not coexist. However, the fact that TiC and TiN can form a solid soln., TiC1-xNx, suggests that Si3N4 and TiC1-xNx may be obsd. in the presence of both C and N2. The Si3N4 + TiB2 2-phase region is limited in such a narrow range of N2 pressure and B activity that processing and application of TiB2/Si3N4 composites would be very difficult. High-temp. solid-state expts. were carried out with selected systems to verify phase stability diagrams. The results of reactions were in agreement with the thermodn. prediction. A high-d. TiB2/SiC composite was prepd. as an example of the application of phase stability diagrams.

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Thermal and acid catalyzed conversion of organic phosphorus compounds. De Lijser, H. J. P.; Mulder, P.; Louw, R. Cent. Chem. Environ., Leiden Univ., Leiden, Neth. Chemosphere (1993), 27(5), 773-8. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:233159 AN 1993:633159 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The org. P compds. tri-Bu and tri-Me phosphate (I and II, resp.), tri-Me phosphite (III), and di-Me phosphonate (IV) were thermolyzed using a plug flow (gas-phase) reactor. I and II proved to be sensitive to acid (wall) catalysis and can be fully degraded at temps. of .mchlt.400. III can isomerize to II and IV. In contrast, IV requires a temp. of >750 for complete conversion; admixed with II it counteracts the smooth acid-mediated degrdn. of II. Unlike real thermolysis at elevated temps., preferably in a reducing atm. of hydrogen, mere acid catalysis is not generally applicable for effectively destroying a variety of ecotoxic org. P compds.

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Preparation of uniformly calcia-doped zirconia. Hill, J.; Newhouse, M.; Xue, J.; Dieckmann, R. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Journal of Materials Synthesis and Processing (1993), 1(2), 101-9. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:232072 AN 1993:632072 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The prepn. of dense samples of high-purity zirconia doped with varying, small contents of CaO has been explored by means of traditional ceramic techniques with sintering and hot-pressing as well as a chem. soln. method. First, CaO-doped samples were prepd. by traditional ceramic methods. Their homogeneities were checked by SEM with x-ray mapping. CaO-dopant distribution was not uniform in all samples with overall CaO contents below 7 mol%. The difficulty in prepg. uniformly doped zirconia with small CaO contents led to exploration of the use of chem. soln. processing techniques. When exploring such techniques, the products of each process step were characterized by x-ray diffraction and electron microprobe anal. The characterization results enabled identification of a processing route which is suitable for prepg. dense, high-purity zirconia uniformly doped with CaO at low concns.

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A model for the isothermal isobaric chemical vapor infiltration (CVI) in a straight cylindrical pore. Application to the CVI of silicon carbide. Fedou, R.; Langlais, F.; Naslain, R. Lab. Compos. Thermostruct., CNRS, Pessac, Fr. Journal of Materials Synthesis and Processing (1993), 1(2), 61-74. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:208796 AN 1993:608796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A previously described modeling of the chem. vapor infiltration (CVI) process in a straight cylindrical pore is applied to the deposition of SiC-based ceramics from MeSiCl3-H2 in the case of a 1st-order kinetic law with respect to MeSiCl3. The model gives concns. and deposit thickness profiles along the pore at any stage of the densification and, particularly, at the end of the process when the pore becomes sealed. The infiltration homogeneity is predicted to be improved by decreasing the aspect ratio of the pore and the CVI temp. and, under conditions of Fick diffusion, by decreasing the total pressure and the pore diam. The model is validated by the good fit between the deposit thickness profiles along the pore calcd. after adjustment of the kinetic data and exptl. profiles for a 34-m straight pore.

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Nicalon-fiber-reinforced silicon carbide composites via polymer solution infiltration and chemical vapor infiltration. Kim, Young Wook; Song, Jin Soo; Park, Sang Whan; Lee, Juen Gunn. Struct. Ceram. Lab., Korea Inst. Sci. Technol., Seoul, S. Korea. Journal of Materials Science (1993), 28(14), 3866-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 119:186895 AN 1993:586895 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A new, faster process was developed for the fabrication of Nicalon-fiber-reinforced SiC composites by combining polymer soln. infiltration (PSI) and chem. vapor infiltration (CVI). The process led to the near-net-shape fabrication of fiber-reinforced ceramic-matrix composites and reduced infiltration time. Typical flexural strength and fracture toughness of these composites were 296 MPa and 10.9 MPa.m1/2 at room temp. and 252 MPa and 9.6 MPa.m1/2 at 1000, resp. The composites exhibited load-carrying capability after crack initiation.

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The effect of glass chemistry on the microstructure and properties of self reinforced silicon nitride. Pyzik, Aleksander J.; Carroll, Daniel F.; Hwang, C. James. Adv. Ceram. Lab., Dow Chem. Co., Midland, MI, USA. Materials Research Society Symposium Proceedings (1993), 287(Silicon Nitride Ceramics), 411-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:186804 AN 1993:586804 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The advantage of self-reinforced silicon nitride is the in-situ control of the microstructure. This control is provided in large degree by the chem. of glassy phase which can be adjusted to tailor the morphol. of silicon nitride grains as well as the matrix-reinforcement interface. The presence of high aspect ratio silicon nitride grains is necessary but not sufficient condition to produce materials with optimum properties. For max. flexure strength and fracture toughness, an optimized glass matrix is required.

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Microwave assisted chemical vapor infiltration. Devlin, D. J.; Currier, R. P.; Barbero, R. S.; Espinoza, B. F.; Elliott, N. Mater. Sci. Technol. Div., Los Alamos Natl. Lab., Los Alamos, NM, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 245-50. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144800 AN 1993:544800 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A microwave-assisted process for prepn. of continuous fiber-reinforced ceramic-matrix composites is described. A simple app. combining a chem.-vapor-infiltration reactor with a conventional 700-W multimode oven is described. Microwave-induced inverted thermal gradients are exploited with the ultimate goal of reducing processing times on complex shapes. Thermal gradients in stacks of SiC (Nicalon) cloths have been measured using optical thermometry. Initial results on the inside-out deposition of SiC via decompn. of MeSiCl3 in H are presented. Several key processing issues are identified and discussed.

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Chemical vapor deposition of multiphase boron-carbon-silicon ceramics. Golda, E. Michael; Gallois, B. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 167-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144796 AN 1993:544796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Specific compns. of boron-carbon-silicon ceramics exhibit improved abrasive wear and good thermal shock resistance, but require bulk sintering at temps. in excess of 2100K. The formation of such phases by CVD was examd. at 1073-1573K. Methyltrichlorosilane (CH3SiCl3), boron trichloride, and methane were chosen as reactant gases, with hydrogen as a carrier gas and diluent. The coatings were deposited in a computer-controlled, hot-wall reactor at a pressure of 33 MPa. Below 1473K the coatings were amorphous. At higher temps. nonequil. reactions controlled the deposition process. The most common coating consisted of a silicon carbide matrix and a silicon boride, SiB6, dispersed phase. Multiphase coatings of B + B4C + SiB6 and SiC + SiB6 + SiB14 were also deposited by controlling the partial pressure of methane and boron trichloride. Non-equil. thermodn. anal. qual. predicted the exptl. deposited multiphase coatings.

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CVD of silicon nitride plate from trichlorosilane-ammonia-hydrogen mixtures. Lennartz, J. W.; Dowell, M. B. Union Carbide Coat. Serv. Corp., Parma, OH, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 161-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144795 AN 1993:544795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preferred conditions for deposition of thick -Si3N4 plate from HSiCl3-NH3-H2 on the vertical surfaces of a low-pressure, hot-wall CVD reactor were identified by means of a designed expt. The design included temp. range 1300-1500, pressures 0.5-2.0 torr, and residence times 0.01-1.0 s. The vertical deposition surfaces received a viscous, laminar flow of well mixed, thermally equilibrated reactants. Plates 0.05-0.5 mm thick were produced on multiple vertical substrates 350 cm2 in area at deposition rates 5-70 m/h. Plates 0.5-4.0 mm thick were produced on horizontal substrates at deposition rates of 60-120 m/h. When NH3 flows in stoichiometric excess, deposition rates on vertical surfaces increase approx. linearly with the flow rate of HSiCl3 but depend little on temp., as would be expected if the reaction proceeds under mass transport control with product depletion. Multiple correlation analyses show that thickness variations in the deposit are reduced by increasing the temp. and decreasing the gas residence time. CVD silicon nitride plate produced under the optimized conditions exhibits theor. d. and is free of pores and cracks. It exhibits a columnar morphol. in which the <222> and <101> crystallog. directions are oriented preferentially normal to a surface, which consists of well-defined trigonal facets 10-50 m across. Crystallite sizes detd. by x-ray line broadening range from 0.06-1.0 m. This CVD plate is gray and contains approx. 0.5 C and 0.5 wt.% 0 as principal impurities.

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Unequivocal evidence. Black, Robin M.; Pearson, Graham S. Chem. Biol. Def. Estab., Porton/Down/Salisbury Wiltshire, UK. Chemistry in Britain (1993), 29(7), 584-5, 587. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 119:123791 AN 1993:523791 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of chem. warfare agent, Sarin, in the Kurdush village of Birjinni, Iraq, was discussed.

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Bioanalysis of organophosphate nerve agents in soil samples. Sawyer, T. W.; Weiss, M. T. Biomed. Def. Sect., Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Chemosphere (1993), 26(11), 2023-9. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:94477 AN 1993:494477 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Four soil samples that may have been spiked with chem. warfare (CW) agents and their degrdn. products were received by Defense Research Establishment Suffield as part of a multinational round-robin exercise designed to evaluate lab. methodologies for the chem. detection of CW agents in soil. After chem. anal. revealed that VX (Et S-2-diisopropyl aminoethyl methylphosphorothiolate) was the CW agent "spike", the samples were also bioassayed for their VX content by assessing their anticholinesterase activities in primary chick embryo neuron cultures. Bioassay quantitation of VX contamination in the soil samples was in good agreement with the actual spike levels and generally better than the chem. anal. results. Sequential bioassay of the samples over a two week period showed that the VX content was rapidly degraded with time. This assay complements std. chem. anal. techniques for the detection and verification of organophosphate warfare agent use.

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The effect of trace element segregation to iron/sapphire interfaces. Pope, D. P.; Smith, M. A. Dep. Mater. Sci., Univ. Pennsylvania, Philadelphia, PA, USA. Materials Research Society Symposium Proceedings (1992), 238(Structure and Properties of Interfaces in Materials), 427-32. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:77041 AN 1993:477041 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of segregation of tramp impurities such as sulfur on metal/ceramic bonding is discussed. Microstructural and chem. information is given for the Fe/sapphire interface. The segregation behavior of the interface is evaluated between 500-800. The interfacial structure is important to the segregation behavior. A possible link between the segregation of sulfur and interface void formation is presented.

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Chemical vapor infiltration of silicon carbide with microwave heating. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(5), 1057-67. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 119:13852 AN 1993:413852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is presented to describe the interaction between transport/reaction processes and the evolution of porosity in chem. vapor infiltration with microwave heating (MCVI). The anal. includes a set of partial differential equations describing the spatiotemporal variation of gaseous species concn., composite temp., porosity, and stress. Maxwell's equations were used to det. the distribution of power dissipated inside the composite. The deposition of silicon carbide was selected as a model chem. system to explore the general features of MCVI. MCVI can provide a favorable temp. distribution in the composite yielding an inside-out deposition pattern, thereby preventing entrapment of accessible porosity. For this temp. profile, tensile stresses develop at the outer regions and compressive stresses are found in the composite core. For a given system there exists a min. value of the coeff. for heat transfer from the composite surface, h, below which accessible porosity is trapped within the composite. Similarly, there exists a max. value of the incident microwave energy flux, I0, above which accessible porosity is trapped within the composite. I0 and h can be optimized for a given preform to achieve complete densification with min. processing time. Using the technique of pulsed-power, the processing time can be reduced even further without compromising d. uniformity. Power dissipation profiles in the composite depend strongly on preform thickness, microwave frequency, and relative loss factor.

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Permeation measurements of chemical agent simulants through protective clothing materials. Pal, Tarasankar; Griffin, Guy D.; Miller, Gordon H.; Watson, Annetta P.; Daugherty, Mary Lou; Vo Dinh Tuan. Health Saf. Res. Dev., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Hazardous Materials (1993), 33(1), 123-41. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 118:239880 AN 1993:239880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A method was developed to study the permeation of chem. warfare (CW) agent simulants through chem. protective clothing (CPC) materials. The exptl. results characterize some com. available CPC materials. Thirteen different CPC materials having widely differing compns. were chosen to study the permeation of 4 different liq. CW simulants (di-Me methylphosphonate, diisopropyl methylphosphonate, malathion, and Bu2S) through these CPC materials at 25. This permeation study involved a newly developed anal. technique employing room temp. fluorescence quenching of an indicator compd., phenanthrene, on filter paper. Various exptl. factors such as breakthrough time, rate of permeation, and uptake were investigated. On the basis of breakthrough time, the 13 CPC materials could be divided into 3 groups: most resistant, moderately resistant, and least resistant. Materials in the most resistant category exhibited no permeation by any of the simulants for 24 h. Breakthrough occurred in the least resistant materials in generally less than an hour, and sometimes as soon as a few minutes.

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Interfacial structure of chemical vapor infiltration carbon fiber/silicon carbide composite. Araki, H.; Noda, T.; Abe, F.; Suzuki, H. Tsukuba Lab., Natl. Res. Inst. Met., Tsukuba, Japan. Journal of Materials Science Letters (1992), 11(23), 1582-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:44089 AN 1993:44089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure at the interface in carbon fiber-SiC matrix composites prepd. by chem. vapor infiltration from EtSiCl3 was examd., and the infiltration reaction is discussed. A graphite layer formed on the carbon fiber and the SiC-SiC interface as a result of thermal decompn. of silane gas before SiC infiltration. This graphite layer, of .apprx.500 nm thickness, is assumed to assist in the crystal growth of SiC, leading to structural stability of the composites.

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Comparative evaluation of carbamates as prophylactic agents against organophosphate intoxication in rats. Chatterjee, A. K. Def. Res. Dev. Establ., Gwalior, UK. Defence Science Journal (1992), 42(2), 85-7. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 118:34070 AN 1993:34070 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper investigates the effects of two well-known carbamates, physostigmine and pyridostigmine, against organophosphorus compd. and nerve gas toxicity. Physostigmine pretreatment for 30 min enhanced the survival time of rats against DFP intoxication, whereas it did not have any effect with sarin poisoning. However, pyridostigmine pretreatment did not produce any significant effect on survival time either against DFP or sarin intoxication. Treatment with atropine along with carbamates further enhanced significantly the survival time against DFP poisoning.

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On the influence of chemical processing in the crystallization behavior of zirconium titanate materials. Navio, J. A.; Macias, M.; Sanchez-Soto, P. J. Inst. Cienc. Mater., Univ. Sevilla, Seville, Spain. Journal of Materials Science Letters (1992), 11(23), 1570-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:26385 AN 1993:26385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The crystn. phenomena of ZrTiO4 powders prepd. from various gel precursors was related to the chem. processing. Correlation of data from the literature and further expt. indicated that the presence of H2O2 in the chem. processing of the amorphous precursors plays a key role in controlling the crystn. temp. The crystn. temp. can be as low as 640.

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Effect of dopants on the sintering behavior and stability of tetragonal zirconia ceramics. Theunissen, G. S. A. M.; Winnubst, A. J. A.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1992), 9(4), 251-63. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:54278 AN 1992:454278 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure development during nonisothermal and isothermal sintering was studied for tetragonal zirconia ceramics (TZP) contg. various amts. of Y, Ce, and Ti. Smaller grain sizes were obtained when Ce-TZP was doped with Y. This could be attributed to segregation of Y to the grain boundaries, thus causing an impurity drag. With increasing temp., the grain growth rate in the Ce-TZP samples increased which could be attributed to the absence of a dragging force. The slow grain growth at low temp. in the Ce-TZP samples could be attributed to the slow diffusion kinetics of the diffusing species (trivalent and tetravalent Ce). The crit. grain size for retainment of the tetragonal phase at room temp. is larger in the Y,Ce-TZP systems compared to the Y-TZP and Ce-TZP systems. The chem. stability increased by doping Y-TZP with Ce or Ti.

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Free radical-mediated lung response to the monofunctional sulfur mustard butyl 2-chloroethyl sulfide after subcutaneous injection. Elsayed, Nabil M.; Omaye, Stanley T.; Klain, George J.; Korte, Don W., Jr. Letterman Army Inst. Res., Presidio of San Francisco, CA, USA. Toxicology (1992), 72(2), 153-65. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 117:42116 AN 1992:442116 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors postulated that vesicants may cause free radical-mediated oxidative stress distal to the site of exposure. To test this postulate in the lung, the authors injected 3 groups of 5-mo-old, male, athymic, nude mice, weighing 30-35 g with a single s.c. dose (5 L/mouse) of Bu 2-chloroethyl sulfide (BCS). Total lung wt. was not altered after treatment, but the wet/dry wt. ratio decreased 18% and Hb content increased 50 and 36% at 1 and 24 h, resp. The activity of glucose 6-phosphate dehydrogenase increased significantly, 40% at 1 and 24 h and 84% at 48 h and that of glutathione S-transferases was 60%. Lipid peroxidn. (estd. by the thiobarbituric acid test) and total protein content increased 3-fold and 2-fold, at 1 and 24 h, resp. Total and oxidized glutathione contents were significantly elevated, 38% at 1 h and 64% at 24 h for the former and 45% at 24 h and 56% at 48 h for the latter. Because these changes are consistent with the cellular response to oxidative stress, it is concluded that BCS injected s.c. can cause changes in the lung possibly via a free radical-mediated mechanism.

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Effects of liquid environments on zirconia-toughened alumina. Part I. Chemical stability. Thompson, I.; Rawlings, R. D. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1992), 27(10), 2823-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:32321 AN 1992:432321 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The structural changes which occur in zirconia-toughened alumina when aged in a range of liq. environments (distd. water, ethylene glycol soln., and HCl at room temp., and ethylene glycol soln. at 80) are described. The changes were monitored by x-ray diffraction, surface anal., anal. of the aging solns., and microstructural observations. HCl induced significant proportions of the zirconia particles in the zirconia-toughened alumina to transform from the tetragonal to the monoclinic crystal structure. This transformation was accompanied by microcracking which eventually led to macrocracking after long periods of aging. The transformation is a consequence of the leaching of the yttrium from the zirconia particles, thereby reducing their stability.

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Binder chemistry, adhesion and structure of interfaces in thick-film metalized aluminum nitride substrates. Newberg, C. E.; Risbud, S. H. IBM Corp., East Fishkill, NY, USA. Journal of Materials Science (1992), 27(10), 2670-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:13161 AN 1992:413161 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Aluminum nitride substrates from 3 sources were metalized by std. thick-film processing using gold conductor pastes, Pd-Ag paste, and a ruthenium oxide resistor paste. Screen-printed pastes were fired in a typical 3-zone furnace to obtain metalized AlN substrates. Interfacial reaction zones were studied by microscopic (optical and SEM) and electron beam microprobe anal. techniques. The elements in the binder materials in thick-film pastes form amorphous phases at the interface which influence the adhesion of thick films to the AlN substrate. The lack of certain elements (Cd, Zn, Ca) in the binder of the gold thick-film paste led to weaker adhesion and severe degrdn. of the thick-film adhesion during thermal cycling.

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Preparation and characterization of a dispersion toughened ceramic for thermomechanical uses (ZTA). Part I. Material preparation. Characterization of microstructure. Leriche, A.; Moortgat, G.; Cambier, F.; Homerin, P.; Thevenot, F.; Orange, G.; Fantozzi, G. CRIBC, Mons, Belg. Journal of the European Ceramic Society (1992), 9(3), 169-76. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:13037 AN 1992:413037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Zirconia-toughened alumina (ZTA) materials contg. increasing amts. of zirconia (5-45 vol.%) and yttria (0-3 mol% zirconia) were prepd. from com. ceramic powders by different techniques of homogenization, shaping, and sintering. The powder mixts. were homogenized by a chem. method (addn. of dispersing agents at fixed pH), by a mech. method (attrition milling) and by combining the methods. The materials were formed and sintered by shaping by isostatic pressing or slip casting, followed by pressureless sintering, and by hot uniaxial pressing. The phys., crystallog. and microstructural properties of the materials prepd. following these different techniques are compared. The combined chem. and mech. dispersion method leads to the fabrication of dense composites presenting a fine and homogeneous zirconia dispersion required for effective toughening of the alumina matrix. The addn. of 3 mol% of yttria allows maintenance of a high tetragonal zirconia content because of a chem. stabilization of tetragonal zirconia and of a decrease of zirconia grain size. As the hot-pressing technique impedes the grain coarsening, the hot-pressed materials present the finest microstructure mainly for the compns. with <20 vol.% zirconia. The zirconia and alumina grain size vary from 0.5 to 0.9 m and from 0.9 to 1.6 m, resp., following the compn. Pressureless sintered materials also present a fine microstructure with submicron zirconia grains (0.6 m-0.9 m) and micron size alumina grains (1.0-1.9 m). These ZTA materials present all the microstructural characteristics necessary to obtain high mech. performances. The addn. of 3 mol% of yttria allows an increase of the zirconia content (45 vol.%) without a decrease of the relative tetragonal zirconia ratio occurring.

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Adsorption and decomposition of organophosphorus compounds on nanoscale metal oxide particles. In situ GC-MS studies of pulsed microreactions over magnesium oxide. Li, Yong Xi; Koper, Olga; Atteya, Maher; Klabunde, Kenneth J. Dep. Chem., Kansas State Univ., Manhattan, KS, USA. Chemistry of Materials (1992), 4(2), 323-30. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 116:200414 AN 1992:200414 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Using an in-situ pulse reactor-GC-mass spectrometric system, the thermal decompn. of organophosphorus compds. (as models of nerve agents) were compared with their destructive absorption on high-surface-area MgO. Dramatically lower temps. are required when MgO is present. Volatile products evolved were HCO2H, water, alcs., and alkenes. At higher temps., CO, CH4, and water predominated. The P residues remained completely immobilized. The addn. of water enhanced the facility of MgO to destroy these compds., and, in fact, water pulses were found to partially regenerate a spent MgO bed. Using 18O labeling, some aspects of the reaction mechanisms were clarified and in particular showed that O scrambling occurred. Surface OH and MgO groups transferred O in the formation of HCO2H, and the surface mobility and reactivity of absorbed groups were high. The substantial capacity of high-surface-area MgO for destruction and immobilization of such toxic substances makes it attractive for air purifn. schemes, as well as solid reagents for destruction and immobilization of bulk quantities of hazardous P compds. or organohalides.

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-(N,N-Dialkylamino)ethyl arylthiosulfonates: new simulants for O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate. Davis, Franklin A.; Ray, Jayanta K.; Kasperowicz, Steve; Przeslawski, Robert M.; Durst, H. Dupont. Dep. Chem., Drexel Univ., Philadelphia, PA, USA. Journal of Organic Chemistry (1992), 57(9), 2594-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 116:193819 AN 1992:193819 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Certain S-[2-(dialkylamino)]ethyl benzenesulfonothioates 4-XC6H4SO2SCH2CH2NR2 (I; X = Me, F; R = Me2CH) were prepd. as simulants for O-Et S-[(diisopropylamino)ethyl]methylphosphonothioate (VX) a chem. warfare nerve agent. I are useful simulants for the hydrolysis or oxidn. chem. of VX.

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Dissolution of sintered silicon nitride bulk specimens for elemental analysis. Homeier, E. H.; Bradley, S. A.; Karasek, K. R. UOP, Des Plaines, IL, USA. Journal of Materials Science (1992), 27(5), 1231-4. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:179524 AN 1992:179524 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Heating bulk, sintered Si3N4 samples in an aq. HF-HCl mixt. decomps. the Si3N4. Subsequent addn. of H2SO4 and volatilization of fluorides enables total dissoln. of the bulk specimens for anal. The elemental compns. that were detd. by inductively coupled plasma at. emission and at. absorption spectrometries agreed with the nominal sample compn. and confirmed analyses performed by scanning TEM. Neutron activation detns. on the same samples are not believed to be as accurate as the spectrometric detns. Furthermore, the precision of the neutron activation measurements were less satisfactory, esp. for key elements such as Y.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy, Paul M.; Hansen, Arnold S.; Hand, Brian T.; Boulet, Camille A. Def. Res. Establ. Suffield, Ralston, AB, Can. Toxicology (1992), 72(1), 99-105. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 116:168061 AN 1992:168061 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a std. set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI 6 > HLoe 7 > pyrimidoxine. Hloe 7 was very effective against tabun poisoning while HI 6 and pyrimidoxime were of moderate value. Against GF, HI 6 and HLoe 7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLoe-7 to a slightly lesser degree. The other oximes lacked the effects against one or more of the organophosphates.

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Chemical vapor deposition of copper via disproportionation of hexafluoroacetylacetonato(1,5-cyclooctadiene)copper(I), (hfac)Cu(1,5-COD). Jain, A.; Chi, K. M.; Hampden-Smith, M. J.; Kodas, T. T.; Farr, J. D.; Paffett, M. F. Dep. Chem. Eng., Univ. New Mexico, Albuquerque, NM, USA. Journal of Materials Research (1992), 7(2), 261-4. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 116:111299 AN 1992:111299 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hot- and cold-wall chem.-vapor deposition (CVD) using the volatile Cu(I) compd. (hfac)Cu(1,5-COD), where hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate and 1,5-COD = 1,5-cyclooctadiene, as a precursor was carried out in hot-wall and warm-wall, lamp-heated reactors using SiO2 substrates that were patterned with Pt or W at 120-250. Deposition was obsd. onto Pt, W, and SiO2 over this temp. range at rates of 3750 .ANG./min to give Cu films that contained no impurities detectable by AES and with resistivities of 1.9-5.7 ohm-cm. The volatile byproducts formed during deposition were 1,5-COD and Cu(hfac)2 and a mass balance was consistent with the quant. disproportionation reaction: 2(hfac)Cu(1,5-COD)  Cu + Cu(hfac)2 + 2(1,5-COD). The measured activation energy for this CVD reaction was 26(2) kcal/mol. The absence of selectivity for metal surfaces in the presence of SiO2 is in contrast to CVD results for the related compds. (-diketonate)Cu(PMe3) where -diketonate = hfac, 1,1,1-trifluoroacetylacetonate, and acetylacetonate (acac).

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer, Thomas W.; Weiss, M. Tracy; D'Agostino, Paul A.; Provost, Lionel R.; Hancock, James R. Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Journal of Applied Toxicology (1992), 12(1), 1-6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 116:105057 AN 1992:105057 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chem. warfare activity was subjected to chem. anal. and bioassay. Sarin and several related compds. were confirmed in the soil by capillary column gas chromatog.-mass spectrometry (GC-MS); however, the binding of these compds. to the soil hindered quantitation. The chem. results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified stds. in chick embryo neuron cultures, a reasonable agreement was found between the chem. and bioassay semiquant. ests. of sarin content in the soil ext. Furthermore, the in-vitro system appears to offer a sensitive technique for the estn. of sarin remaining bound to the soil following solvent extn. as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Pharmacological effects of oximes: how relevant are they?. van Helden H P; Busker R W; Melchers B P; Bruijnzeel P L Department of Pharmacology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1996), 70(12), 779-86. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 8911635 AN 97068325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The increased international concern about the threat of military and terroristic use of nerve agents, prompted us to critically consider the expected value of the currently available oxime treatment of nerve agent poisoning. Although oximes have been designed to reactivate the inhibited acetylcholinesterase (AChE), clinical experience has indicated that they are not always very effective as reactivators and at this very moment none of them can be regarded as a broad-spectrum antidote. In spite of this drawback, oximes are worth further investigating, since recent data derived from soman or tabun lethally intoxicated non-human primates suggest that the oxime HI-6 may exert a pharmacological effect that is not related to reactivation of inhibited AChE, but still leads to survival. This pharmacological effect causes recovery of neuronal transmission in the respiratory centres of the brain and recovery of neuromuscular transmission in the diaphragm. These findings have stimulated research to reveal the pharmacological basis of these effects in order to find drugs which could be more effective and less toxic than the available oximes. Since cholinergic drugs were able to exert this effect, a new concept for further treatment is suggested: maintenance of neuronal transmission in spite of continued AChE-inhibition by pharmacological manipulation of the cholinergic receptor. This should renew interest in the diverse pharmacological effects of oximes to reach a more effective treatment in the future.

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Evaluation of the therapeutic efficacy of some antimuscarinics against soman in vivo. Lau W M; Lewis K J; Dawson R M Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organization, Department of Defence, Melbourne, Victoria, Australia Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 423-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889794 AN 97044723 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The therapeutic efficacy of tacrine, atropine and glycopyrrolate alone or in combination with the oxime HI-6 against soman was evaluated in anaesthetized rats. Arterial blood pressure, heart rate, respiratory frequency and body temperature were monitored in vivo. Blood cholinesterases were determined after each drug or soman challenge. At the lowest concentration tested (2.5 mg kg-1), tacrine was effective in improving the survivability of the rat by a factor of 2.6 (protection ratio), whereas the protection by atropine or glycopyrrolate was either insignificant or only marginally effective (protection ratio ranged from 1.0 to 1.9). In combination with HI-6, atropine increased the ratio to 4.6. In contrast, tacrine with HI-6 failed to improve the efficacy of the regimen, while glycopyrrolate plus HI-6 showed only slight improvement. The four physiological parameters monitored were relatively constant during the time course of the experiment in both the control and those with drug therapy. The more noticeable changes occurred toward the end of the experiment when sufficient amount of soman was injected to cause lethality. Death of the animal was usually preceded by a surge of arterial blood pressure and heart rate and a decrease in respiratory frequency. These physiological parameters rapidly deteriorated to zero just before the animal died. Blood and plasma cholinesterases were significantly inhibited after the animal received a relatively small dose of soman (20 micrograms kg-1) and were almost completely inactivated after the lethal dose of soman was administered. However, these changes of enzyme activity did not correspond well with the survivability of the rat. The inclusion of HI-6 with the three antimuscarinics appeared to be capable of protecting some cholinesterases against soman.

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Efficacy of ibuprofen and pentoxifylline in the treatment of phosgene-induced acute lung injury. Sciuto A M; Stotts R R; Hurt H H Pathophysiology Division, United States Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 381-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889788 AN 97044717 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Phosgene, a highly reactive former warfare gas, is a deep lung irritant which produces adult respiratory distress syndrome (ARDS)-like symptoms following inhalation. Death caused by phosgene involves a latent, 6-24-h, fulminating non-cardiogenic pulmonary edema. The following dose-ranging study was designed to determine the efficacy of a non-steroidal anti-inflammatory drug, ibuprofen (IBU), and a methylxanthine, pentoxifylline (PTX). These drugs were tested singly and in combination to treat phosgene-induced acute lung injury in rats. Ibuprofen, in concentrations of 15-300 mg kg-1 (i.p.), was administered to rats 30 min before and 1 h after the start of whole-body exposure to phosgene (80 mg m-3 for 20 min). Pentoxifylline, 10-120 mg kg-1 (i.p.), was first administered 15 min prior to phosgene exposure and twice more at 45 and 105 min after the start of exposure. Five hours after phosgene inhalation, rats were euthanized, the lungs were removed and wet weight values were determined gravimetrically. Ibuprofen administered alone significantly decreased lung wet weight to body weight ratios compared with controls (P < or = 0.01) whereas PTX, at all doses tested alone, did not. In addition, the decrease in lung wet weight to body weight ratio observed with IBU+PTX could be attributed entirely to the dose of IBU employed. This is the first study to show that pre- and post-treatment with IBU can significantly reduce lung edema in rats exposed to phosgene.

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Subchronic toxicity evaluation of sulfur mustard in rats. Sasser L B; Miller R A; Kalkwarf D R; Cushing J A; Dacre J C Pacific Northwest Laboratory, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1996 Jan-Feb), 16(1), 5-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8821670 AN 96418885 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

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Acute toxicity of cyclohexylmethylphosphonofluoridate (CMPF) in rhesus monkeys: serum biochemical and hematologic changes. Young G D; Koplovitz I U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Archives of toxicology (1995), 69(6), 379-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7495375 AN 96114840 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Changes in serum biochemical and hematological parameters were studied in 20 male rhesus monkeys following acute poisoning by the organophosphate nerve agent cyclohexylmethylphosphonofluoridate (CMPF or GF). Animals were challenged with 5 x LD50 GF (233 micrograms/kg, IM) following pretreatment with pyridostigmine (0.3-0.7 mg/kg per 24 h) and treated with atropine (0.4 mg/kg, IM) and either 2-PAM (25.7 mg/kg, IM) or H16 (37.8 mg/kg, IM) at the onset of clinical signs or at 1 min after exposure. Muscle fasciculations, tremors, or convulsions occurred in 19 of 20 animals. Serum biochemical and hematologic parameters were analyzed 2 days and 7 days after exposure and compared to pre-exposure baseline values. Significant increases in creatine kinase (CK), lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase (ALT) and potassium ion (K+), associated with damage to striated muscle and metabolic acidosis, occurred in both oxime-treated groups 2 days after exposure. Total protein, albumin, red blood cell (RBC) count, hemoglobin concentration (Hb) and hematocrit (Hct), were decreased in both oxime-treated groups at 7 days. The results demonstrate that animals exposed to a single high dose of GF and treated with standard therapy exhibit changes in serum biochemical and hematological indices directly and indirectly associated with their clinical presentations.

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Production, characterization and application of monoclonal antibodies against the organophosphorus nerve agent Vx. Ci Y X; Zhou Y X; Guo Z Q; Rong K T; Chang W B Department of Chemistry, Peking University, Beijing, China Archives of toxicology (1995), 69(8), 565-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8534201 AN 96036122 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Two monoclonal antibodies (Vx-BB8 and Vx-EA11) to the chemical warfare agent Vx were produced and characterized. A competitive inhibition enzyme immunoassay was developed to detect Vx concentrations as low as 3.7 x 10(-7) - 3.7 x 10(-6) mol/l in biological samples. Vx-BB8 400 micrograms given intravenously immediately before 1 x LD95 Vx or 400 micrograms Vx-BB8 intraperitoneally 1.5 h-3 days before 1 x LD95 Vx could protect all the tested mice from death.

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Toxicity of sulphur mustard in adult rat lung organ culture. Sawyer T W; Wilde P E; Rice P; Weiss M T Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada Toxicology (1995 Jun 26), 100(1-3), 39-49. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7542806 AN 95350771 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of the chemical warfare agent sulphur mustard, (bis-(2-chloroethyl)sulphide, HD), was examined in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concentration (LC50) of HD in these cultures was reproducible, and in the microM range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathological examination of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochemically, and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulphur mustard.

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Toxicity of the combined nerve agents GB/GF in mice: efficacy of atropine and various oximes as antidotes. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Canada Archives of toxicology (1994), 68(1), 64-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166607 AN 94219995 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of a combination of isopropyl methylphosphonofluoridate (sarin; GB) and cyclohexyl methylphosphonofluoridate (GF) and the efficacy of various oxime reactivators in combination with atropine against the combined GB/GF challenge were evaluated in mice. The 24-h s.c. LD50 of the GB/GF combination was 1.15 mumol/kg (1.10-1.21; 95% confidence limits). Mice administered GB/GF displayed typical signs of nerve agent poisoning such as tremors and convulsions, with death most likely due to anoxia subsequent to respiratory arrest. The GB/GF LD50 value was comparable to the s.c. LD50 of 1.35 and 1.21 mumol/kg for GF and GB in mice, respectively. Combining the two nerve agents did not result in potentiation of the toxicity. In combination with atropine sulfate (17.4 mg/kg, i.p.), which alone did not reduce mortality, the oximes tested, 2-PAM, obidoxime and HI-6, were all effective when administered 5 min before 3 x LD50 dose of GB/GF with 24-h ED50 values of 102.5, 18.22 and 1.96 mumol/kg, respectively. Use of the GB/GF combination does not appear to confer any unique toxicity profile and appears to be easily treated with the standard therapy of a cholinolytic and oxime.

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Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs. Due A H; Trap H C; Langenberg J P; Benschop H P TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1994), 68(1), 60-3. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166606 AN 94219994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson B W; Kawakami T G; Cone N; Henderson J D; Rosenblatt L S; Goldman M; Dacre J C Department of Avian Sciences, University of California, Davis 95616-5224 Toxicology (1994 Jan 26), 86(1-2), 1-12. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8134917 AN 94182225 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (Tabun, phosphoramidocyanidic acid, dimethyl-, ethyl ester) as part of a program to demilitarize chemical warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only three of the five assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Evaluation of the toxicity, pathology, and treatment of cyclohexylmethylphosphonofluoridate (CMPF) poisoning in rhesus monkeys. Koplovitz I; Gresham V C; Dochterman L W; Kaminskis A; Stewart J R US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425 Archives of toxicology (1992), 66(9), 622-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1482284 AN 93129117 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (CMPF) is an organophosphate cholinesterase inhibitor with military significance. The purpose of these studies was 1) to determine the acute toxicity of CMPF in the male rhesus monkey, 2) to evaluate the efficacy of pyridostigmine (PYR) pretreatment plus atropine and oxime (2-PAM or H16) treatment, and 3) to evaluate the pathological consequences of acute poisoning. An i.m. LD50 of CMPF was estimated using an up-and-down dose selection procedure and 12 animals. The 48-h and 7-day LD50 was 46.6 micrograms/kg, i.m. In the protection experiments, pyridostigmine (0.3-0.7 mg/kg/24 h) was administered by surgically implanted osmotic minipumps for 3-12 days resulting in 21-65% inhibition of erythrocyte acetylcholinesterase activity. Animals were challenged with 5 x L50 CMPF (233 micrograms/kg) and treated with atropine (0.4 mg/kg) and either 2-PAM (25.7 mg/kg) or HI6 (37.8 mg/kg) at the onset of signs or 1 min after challenge. Osmotic pumps were removed within 30 min after agent challenge. Pyridostigmine, atropine, and either 2-PAM or H16 were completely effective against CMPF, saving ten of ten animals in each group. In comparison, three of five animals challenged with 5 x LD50 of soman and treated with atropine and 2-PAM survived 7 days. The primary histologic lesions in the acute toxicity group were neuronal degeneration/necrosis and spinal cord hemorrhage. The CMPF treated groups (total of 20 animals) had minimal nervous system changes with no significant lesion difference resulting from the different oxime therapies. The primary non-neural lesions were degenerative cardiomyopathy and skeletal muscle degeneration which occasionally progressed to necrosis and mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)

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Efficacy of various oximes against GF (cyclohexyl methylphosphonofluoridate) poisoning in mice. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Alta., Canada Archives of toxicology (1992), 66(2), 143-4. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1605730 AN 92296882 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The efficacy of oxime (HI-6, toxogonin or PAM Cl) therapy against GF (cyclohexyl methylphosphonofluoridate) poisoning was assessed in mice. It was found that the combinations of atropine and either toxogonin or HI-6 were effective therapies against GF poisoning. PAM therapy was ineffective. HI-6 was the only oxime which reactivated GF inhibited acetylcholinesterase. This might explain the reason why the HI-6 treated mice appeared to recover more quickly from the incapacitating effects following GF poisoning.

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer T W; Weiss M T; D'Agostino P A; Provost L R; Hancock J R Defence Research Establishment Suffield, Alberta, Canada Journal of applied toxicology : JAT (1992 Feb), 12(1), 1-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1564246 AN 92226402 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chemical warfare activity was subjected to chemical analysis and bioassay. Sarin and several related compounds were confirmed in the soil by capillary column gas chromatography-mass spectrometry (GC-MS); however, the binding of these compounds to the soil hindered quantitation. The chemical results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified standards in chick embryo neuron cultures, a reasonable agreement was found between the chemical and bioassay semi-quantitative estimates of sarin content in the soil extract. Furthermore, the in vitro system appears to offer a sensitive technique for the estimation of sarin remaining bound to the soil following solvent extraction as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy P M; Hansen A S; Hand B T; Boulet C A Defence Research Establishment Suffield, Ralston, Alberta, Canada Toxicology (1992), 72(1), 99-105. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1539175 AN 92169690 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a standard set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI-6 greater than HLo-7 greater than pyrimidoxime. HLo-7 was very effective against tabun poisoning while HI-6 and pyrimidoxime were of moderate value. Against GF, HI-6 and HLo-7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLo-7 to a slightly lesser degree. The other oximes suffered from their lack of effects against one or more of the organophosphates.

[megalomania]

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Aluminum nitride defect chemistry dependence on sintering atmosphere. Chang, E. K.; Kirschner, M. J. BOC Group Technical Cent., Murray Hill, NJ, USA. Journal of Materials Science Letters (1996), 15(18), 1580-1581. CODEN: JMSLD5 ISSN: 0261-8028. Journal; General Review written in English. CAN 125:282600 AN 1996:614771 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 12 refs., of equations explaining theor. relations between aluminum nitride defect chem. and sintering atm.

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Microstructure, chemical reaction and mechanical properties of TiC/Si3N4 and TiN-coated TiC/Si3N4 composites. Huang, Jow-Lay; Lee, Ming-Tung; Lu, Horng-Hwa; Lii, Ding-Fwu. Dep. Material Science Eng., National Cheng-Kung Univ., Tainan, Taiwan. Journal of Materials Science (1996), 31(18), 4899-4906. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:254919 AN 1996:610489 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Silicon nitride contg. various compns. of as-received TiC and TiN-coated TiC, were hot pressed at 1800 C for 1 h in a nitrogen atm. In TiN-coated TiC/Si3N4 composites, TiC reacted first with the TiN coating to form a titanium carbonitride interlayer at 1450 C, which essentially reduced further reactions between TiC and Si3N4 and enhanced densification. TiN-coated TiC/Si3N4 composites exhibited better densification, hardness, flexural strength and fracture toughness than those of as-received TiC/Si3N4. The toughening mechanisms for as-received TiC/Si3N4 and TiN-coated TiC/Si3N4 composite were attributed to crack deflection, load transfer and crack interference by the compressive thermal residual stress.

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Wet chemical synthesis of ZrO2-SiO2 composite powders. Wang, Shi-Wei; Huang, Xiao-Xian; Guo, Jing-Kun. Shanghai Inst. Ceramics, Chinese Academy Sciences, Shanghai, Peop. Rep. China. Journal of the European Ceramic Society (1996), 16(10), 1057-1061. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 125:254896 AN 1996:596753 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of compn. xZrO2(I-x)SiO2, with x = 10, 20, 30 and 40 vol.%, have been prepd. by a wet chem. method using fumed silica and zirconyl chloride as precursors. Thermogravimetric anal. and differential thermal anal. (DTA) show that wt. loss is caused by release of the absorbed water and decompn. of the Zr(OH)4 gels. Gels were heat-treated for 2 h at 500, 700, 900, 1100 and 1350C, and the products examd. using IR spectroscopy. The increasing intensity of the peak at 800 cm-1 in the IR spectra with increasing temp. is attributed to the formation of Si-O-Si bonds among different SiO2 particles, which means that the SiO2 particles grow bigger with increasing temp. The DTA exothermic peak as well as the IR results reveal that the crystn. of tetragonal zirconia (t-ZrO2) begins at about 900C, which is confirmed by x-ray diffraction (XRD). XRD curves also suggest that the silica matrix contributes to the thermal stability of t-ZrO2. The stability of t-ZrO2 is interpreted by the particle-size effect.

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Structure-property relationship of ceramic coatings produced by laser processing. De Hosson, J. Th. M.; Zhou, X. B. Dep. Applied Physics, Univ. Groningen, Groningen, Neth. Materials Research Society Symposium Proceedings (1996), 397(Advanced Laser Processing of Materials--Fundamentals and Applications), 537-542. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:306847 AN 1996:579019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper deals with a well known puzzling observation that wetting in some instances is improved by a chem. reaction between a liq. and a solid substrate in laser processing while in other systems just the opposite effect takes place. Contact angles of liq. Al on SiO2 and liq. Ti on Al2O3 are reported and some results of laser melt injection of SiO2 particles into molten Al. The surface and interface structures were explored by SEM and energy dispersive x-ray spectrometry. According to the exptl. observations, it appears that the vol. change of ceramic substrates during reaction plays a key role in the effect of chem. reaction on wetting.

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Mechanical and thermal properties of SiC-SiC composites made with CVR SiC fibers. Kowbel, W.; Tsou, H. T.; Bruce, C. A.; Withers, J. C. MER Corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1996), 410(Covalent Ceramics III--Science and Technology of Non-Oxides), 417-422. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:202665 AN 1996:502987 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temps. up to 1600C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addn., enhancement of the composite through-the-thickness thermal cond. was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.

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The influence of surface kinetics in modeling chemical vapor deposition processes in porous preforms. Dekker, J. P.; Moene, R.; Schoonman, J. Lab. Appl. Inorg. Chem., Delft Univ. Technol., Delft, Neth. Journal of Materials Science (1996), 31(11), 3021-3033. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65201 AN 1996:378298 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The isothermal chem. vapor infiltration (ICVI) process is a well known technique for the prodn. of composites and the surface modification of porous preforms. Math. modeling of the process can provide a better understanding of the influence of individual process parameters on the deposition characteristics such as final porosity or deposition profiles in the pore network. The influence of different rate expressions for several binary compds. on the ICVI process is discussed. Exptl. work is used to validate the importance of correct kinetic expressions in a continuous ICVI model for cylindrical pores. The predicted infiltration characteristics are compared with exptl. results. The final densification and Thiele modulus, i.e. a no. which is a measure for the diffusion limitations in a pore, are used for the evaluation of the presented model, and conditions are given for an optimal densification of a porous preform by the ICVI process for several binary compds. The deposition profiles as predicted by the model calcns. are in agreement with the exptl. detd. deposition profiles of TiN and TiC in small tubes. Moreover, it can be concluded that the shape of the deposition profiles is detd. by the heterogeneous reaction kinetics. There is only a qual. agreement between the predicted densification and measured densification for the synthesis of TiN and TiB2 in sintered porous alumina. This mismatch can be explained in terms of a complexity of the pore network and differences in reaction kinetics. Model calcns. reveal that there is a scattering for the predicted residual porosity as a function of the Thiele modulus for TiN. Moreover, this Thiele modulus can not fully account for the changes in densification at different temps. Given these uncertainties it is likely that a residual porosity of less than one percent can be obtained if the Thiele modulus is smaller than 1  10-4. However, a CVI process with such a small Thiele modulus will not be practical, because of the concomitant long process times.
Therefore, more precise conditions for the individual process parameters, i.e. concn., reactor pressure, and temp. are deduced from the model calcns.

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Pressure-pulsed chemical vapor infiltration of TiN into SiC particulate preforms. Sugiyama, K.; Sugata, M. Dep. Appl. Chem., Aichi Inst. Technol., Toyota, Japan. Journal of Materials Science (1996), 31(11), 2945-2949. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65198 AN 1996:378286 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC particulate preforms were infiltrated by TiN matrix from a gas mixt. of TiCl4 (5%), nitrogen (30%) and hydrogen using a repeating pressure pulse between 760 and about 1 torr. SiC particle sizes of 5 and 20 m were used. For matrix packing into deep level, optimum temp. was detd. between 800 and 850, and the max. packing ratio reached 67% after 4  104 pulses at 850. The increase of TiCl4 concn. to 10% resulted in higher deposition rate and packing ratio. The decrease of nitrogen concn. led to slower deposition, i.e., a similar effect to temp. lowering. The max. flexural strength measured was 140 MPa.

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Synthesis of mullite coatings by chemical vapor deposition. Mulpuri, Rao P.; Sarin, Vinod K. Dep. Mfg. Eng., Boston Univ., Boston, MA, USA. Journal of Materials Research (1996), 11(6), 1315-1324. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 125:39956 AN 1996:366859 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Formation of mullite on ceramic substrates via chem. vapor deposition was investigated. Mullite is a solid soln. of Al2O3 and SiO2 with a compn. of 3Al2O32SiO2. Thermodn. calcns. performed on the AlCl3-SiCl4-CO2-H2 system were used to construct equil. chem. vapor deposition (CVD) phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were detd. Through process optimization, cryst. CVD mullite coatings have been successfully grown on SiC and Si3N4 substrates. Results from the thermodn. anal., process optimization, and effect of various process parameters on deposition rate and coating morphol. are discussed.

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Mixed chromium and aluminum oxides elaborated by a sol-gel process. I. Chemistry of the preparation. Rezgui, Saloua; Ghorbel, Abdelhamid; Henry, Marc. Lab. Chimie Materiaux Catalyse, Dep. Chimie, Tunisia. Journal of Materials Synthesis and Processing (1995), 3(6), 371-376. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 125:16967 AN 1996:331762 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of mixed chromium and aluminum oxide were prepd. by a sol-gel process. The precursor is a mixt. of Al(O-s-Bu)3 and Cr(acac)3 with a mass ratio Al/Cr = 10 in sec-butanol. Gelation occurred by adding acetic acid. The amt. of added acetic acid is represented by the ratio k = [CH3COOH]/[Al(O-s-Bu)3], with k varying between 0.5 and 3. Acetic acid played crucial roles in both hydrolysis and polycondensation, (1) producing water in situ by esterification, (2) modifying the precursor by substituting some of the O-s-Bu ligands by acetate ligands, and (3) catalyzing the polycondensation. The importance of each of these roles in the process as well as the nature of the products varied with the ratio k.

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Influence of alloying elements on the chemical reactivity between Si-Al-O-N ceramics and iron-based alloys. Vluegels, J.; Vandeperre, L.; Van Der Biest, O. Dep. Metallurgy Materials Eng., Katholieke Univ. Leuven, Leuvan, Belg. Journal of Materials Research (1996), 11(5), 1265-1276. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 124:323490 AN 1996:293140 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. interaction between two '-O' Si-Al-O-N ceramics and a no. of iron-based alloys is studied by means of static interaction couple expts. at 1100 and 1200 C. The onset temp. of reaction of Si3N4 with pure iron was 1095 C, which is in good agreement with a calcd. temp. of 1033 C. During the interaction, silicon and nitrogen from the ceramic dissolve and diffuse into the iron alloy, whereas the remaining aluminum and oxygen form Al2O3 particles. The interaction between the ceramic and iron alloy is reaction controlled. In the initial stage of the interaction, the dissocn. rate of the ceramic is the rate-controlling step. After the ceramic/metal interface is isolated from the furnace atm., the nitrogen soln. rate into the iron alloy becomes rate controlling. The influence of alloying elements on the reactivity could be related to their effect on the nitrogen soly. in the iron alloy. Ni, Si, and C decrease the nitrogen soly. and decrease the reactivity with the Sialon ceramic. Cr and Mo have the opposite effect. The thickness of the interaction layer on the ceramic side of the interaction couple was found to be a function of the calcd. nitrogen soly. in the iron alloy at 1 atm nitrogen pressure, making it possible to predict the relative chem. reactivity of a no. of iron-based alloys with the same Sialon ceramic.

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Preparation and pressureless sintering of chemical vapor deposited SiC-B composite powder. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Institute Materials Research, Tohoku University, Sendai, Japan. Journal of Materials Science (1996), 31(3), 679-83. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 124:239925 AN 1996:180535 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-B composite powder was prepd. by chem. vapor deposition (CVD) using (CH3)2SiCl2 + B2H6 + H2 as source gases at 1673 K. The powder was -type polycryst. silicon carbide contg. several per cents of boron and carbon. The boron content increased from 0 to 7.7 mass% as the B2H6 gas concn. increased from 0 to 0.7 mol%. Boron and carbon in amorphous form dispersed homogeneously in the -SiC polycryst. particles. The particles were spherical, non-agglomerated and uniform in size with an av. particle size of about 50 nm. Sintering tests were performed with the resulting composite powder without applying pressure. Powder contg. 1 mass% boron and 2 mass% carbon was sintered to a d. of 3.16 x 103 kg m-3 at 2273 K, and the Vickers hardness of the sintered body was 30 GPa. When the sintering temp. was higher than 2323 K, significant grain growth due to the phase transformation from  to  form occurred, which decreased bulk d. and Vickers hardness.

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Nanocrystalline metals, intermetallics, and a metal-matrix nanocomposite by solution-based chemical reductions. Buhro, W. E.; Haber, J. A.; Waller, B. E.; Trentler, T. J.; Suryanarayanan, R.; Frey, C. A.; Sastry, S. M. L. Department Chemistry, Washington University, St. Louis, MO, USA. Polymeric Materials Science and Engineering (1995), 73 39-40. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 124:123490 AN 1996:951 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A metal salt soln. was reduced to nanocryst. and nanocomposite. CuCl in THF was reduced with NaBH4 to form nanocrystal Cu, and Ni and Al can also be prepd. in similar manner. NiCl2 soln. was reduced with LiAlH4 ti NiAl intermetallic compds. of nano size. MoCl5 and SiCl4 were reduced with NaK to nanocryst. MoSi2 in ultrasound field. TiB2 nanocryst. particles were suspended in THF and CuCl was reduced to obtain a Cu-coated TiB2 nanocomposite.

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Preparation of low density free-standing shape of SiC by pressure-pulsed chemical vapor infiltration. Sugiyama, K.; Norizuki, K. Dep. Applied Chem., Aichi Inst. Technology, Toyoda, Japan. Journal of Materials Science Letters (1995), 14(23), 1720-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 124:64057 AN 1995:1000853 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of the conditions of pressure-pulsed chem. vapor infiltration (PCVI) on the deposition rate, ease of substrate oxidn., gross d., and flexural strength in prepn. of low-d. free-standing SiC shapes were examd. By selection of a porous carbon substrate, highly porous SiC shapes with a desirable pore distribution may be prepd. by the PCVI process.

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Identification of chemical and physical change during acid cleaning of ceramics. Johnson, Jessica S.; Erickson, Harold M.; Iceland, Harry. Texas Mem. Mus., Univ. Texas, Austin, TX, USA. Materials Research Society Symposium Proceedings (1995), 352(Materials Issues in Art and Archaeology 4), 831-7. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 124:54897 AN 1995:985335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This report describes the results of two expts. characterizing chem. and phys. change in ceramic constituents occurring from acid solns. commonly used to remove deposits from the surface of archaeol. ceramics. The first examines the chem. effects of hydrochloric acid, in an attempt to identify the yellow color, commonly known as "acid burn", often seen in museum collections on black-on-white sherds found in the Southwestern U.S. The compd. is identified as Fe2O3H2O. The second study compares the phys. effects of different acids on a group of Maya sherds. All acids tested in this study were found to cause phys. damage.

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Influence of particle characteristics on sintering behavior of alumina-zirconia composites. Balasubramanian, M.; Malhotra, S. K.; Gokularathnam, C. V. FRP Research Center, Indian Inst. of Technology, Madras, India. Journal of Materials Science Letters (1995), 14(21), 1484-5. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:347792 AN 1995:927403 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A uniform distribution of zirconia particles in an alumina matrix can be achieved by chem. processing methods. Three chem. processing routes were used to obtain better powders. The sintered d. and the tetragonal ZrO2 content of composites were correlated with powder size and morphol.

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Wet air oxidation of energetics and chemical agent surrogates. Copa, William M.; Momont, Joseph A. Zimpro Environmental Inc., Rothschild, WI, USA. Journal of Energetic Materials (1995), 13(3&4), 235-58. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295590 AN 1995:895724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Wet oxidn. studies have been conducted on a no. of energetic materials and wastewaters derived from energetic materials to demonstrate high destruction levels of specific energetic components. Triple-base propellant, OTTO Fuel (used as torpedo propellant) and hydrazine-based rocket fuel were energetics of interest. Triple-base propellant contain nitrocellulose, nitroglycerin, and nitroguanidine. OTTO Fuel contains substantial amts. of propylene glycol trinitrate. Hydrazine based rocket fuel contains hydrazine and 1,1-di-Me hydrazine (asym. di-Me hydrazine or UDMH). A bench scale wet air oxidn. study on alk. hydrolyzates of triple-base propellants indicated that essentially complete destruction of the reactive nitrogen components could be achieved at an oxidn. temp. of 280. Bench scale wet air oxidn. studies on OTTO Fuel wastewaters indicated that a >99% destruction of propylene glycol dinitrate can be achieved at 280. Processing OTTO Fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved even higher destruction levels. Bench scale wet air oxidn. studies on hydrazine-based rocket fuel wastewaters indicated that a 99.8% destruction of hydrazine and a >99.0% destruction of 1,1-dimethylhydrazine can be oxidized at 280. Again, processing of hydrazine-based rocket fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved similar destruction levels. The application of wet air oxidn. for the destruction of chem. agents has been made by the extrapolation of data from the wet air oxidn. of compds. with similar chem. structures or of surrogate compds. Sarin and V-agents are nerve agents which have an organo-phosphorus structure similar to that of contain commonly used pesticides. Pesticides such as glyphosate and malathion, which have a similar organo-phosphorus structure, are essentially completely destroyed (>99% destruction) by wet air oxidn. at 200-280. The chem. agent surrogate, di-Me Me phosphonate (DMMP) was wet air oxidized at 220-280. Alk.
hydrolyzed DMMP was wet air oxidized at 280. All of the oxidized effluents showed a >97.5% destruction efficiency for the DMMP. The blister agent, mustard (HD) is a chlorinated sulfide, bis(2-chloroethyl) sulfide. Org. sulfides such as mercaptans can be destroyed by wet air oxidn. at 260-280. It is concluded that the wet air oxidn. process is a promising alternative to incineration for disposal of energetics and chem. warfare agents.

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Molten salt oxidation of chemical munitions. Stewart, Albert; Schnittgrund, Gary. PyroPacific Processes, Grand Hills, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 213-34. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295589 AN 1995:895723 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molten salt oxidn. is reviewed as a potential near term alternative technol. for the destruction of chem. agents. Initial tests completed by the US Army in 1975 showed the promise of achieving very high removal efficiencies on actual agents. Recent testing by DOE has verified the potential for very low PIC and dioxin or furan releases. To further explore the possible application of this technol. to chem. agent destruction, a molten salt reactor and assocd. equipment was designed to process a nominal 50 kg/h of Sarin. Mass and energy balances are presented for process conditions representing a range of molten salt potential operational modes and schemes for enhancing plant capacity. Process economics are presented.

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Supercritical water oxidation of chemical agents, and solid propellants. Spritzer, M. H.; Hazlebeck, D. A.; Downey, K. W. San Diego, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 185-212. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295588 AN 1995:895722 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Supercrit. water oxidn. (SCWO), also referred to as hydrothermal oxidn. (HTO), is a developing technol. for the destruction of hazardous and nonhazardous wastes. SCWO destroys combustible materials using an oxidant in water at 350-600 and pressures of 17 MPa. General Atomics and its subcontractors are currently conducting 2 comprehensive research and demonstration programs geared toward the destruction of Department of Defense (DoD) wastes utilizing SCWO technol. Wastes of primary interest include chem. agents and solid propellants. Tech. challenges, particularly corrosion and solids handling, were overcome, and the destruction of chem. agents and solid propellants was demonstrated on a bench scale. SCWO results for chem. agents show destruction and removal efficiencies for GB, VX, and mustard agents to be in excess of 99.9999%, limited only by detection capability. SCWO results for hydrolyzed Class 1.1 solid propellant show destruction and removal efficiencies for total org. carbon (TOC) of >99.9%. Design and fabrication of a transportable SCWO pilot plant for chem. warfare agents, propellants and other DoD hazardous wastes and a prototype HTO system for solid rocket propellant disposal are complete and demonstration testing is underway.

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Pressure pulsed chemical vapor infiltration of SiC to two-dimensional-Tyranno/SiC-C preforms. Sygiyama, Kohzo; Yoshida, Yazutoshi. Department of Applied Chemistry, Aichi Institute of Technology, Toyoda, Japan. Journal of Materials Science (1995), 30(20), 5125-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:320390 AN 1995:894944 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preforms of two-dimensional Tyranno fiber (SiC base) of 7  20  1.3 mm3 were chem. vapor infiltrated with SiC at 850-1050C from a gas mixt. of CH3SiCl3 (6%)-H2 using pressure pulses between below 0.3 kPa and 0.1 MPa. Above 900C, films grew on the macrosurface dominantly. At 850C, residual porosity decreased to about 10% after 105 pulses, and three point flexural strength reached about 200 MPa. X-ray diffractograms on the surface showed the deposits to be -SiC only.

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Matrix characterization of fiber-reinforced SiC matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M.; More, K. L.; Sheldon, B. W.; Besmann, T. M.; Headinger, M. H.; Davis, R. F. Oak Ridge National Laboratory, Oak Ridge, TN, USA. Journal of Materials Science (1995), 30(17), 4279-85. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:206673 AN 1995:804167 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ceramic matrix composites (CMCs), that consist of silicon carbide (SiC) reinforced with continuous Nicalon or T-300 fibers, are being developed for many high-temp. structural applications. The large potential use of CMCs has prompted an in-depth investigation and characterization of these materials. Electron microscopy and micro-Raman spectroscopy were used to characterize and compare the SiC matrix crystal structure and morphol. of composite materials fabricated by two different chem. vapor infiltration (CVI) processes.

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Characterization of pseudo-porous SiC/C coatings on NextelTM 440 and NicalonTM fibers. Khasgiwale, N. R.; Butler, E. P.; Tsakalakos, L.; Hensley, D. A.; Cannon, W. R.; Danforth, S. C.; Gonczy, S. T. Center Ceramic Research, Rutgers University, Piscataway, NJ, USA. Materials Research Society Symposium Proceedings (1995), 365 395-400. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177329 AN 1995:774261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Pseudo-porous SiC/C coatings were deposited on NextelTM 440 and NicalonTM fibers by CVD. The morphol. and chem. of the coatings was evaluated, both before and after oxidn., using SEM, X-Ray Diffraction Anal. (XRD), XPS and Auger spectroscopy. Coated fibers were subjected to two different oxidn. treatments to assess coating stability: a) oxidn. at 600C for 20 h, and b) oxidn. at 1000C for 20 h. Pseudo-porous SiC/C on NicalonTM fibers appear to be more oxidn. resistant than the same coatings on NextelTM440 fibers.

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The preparation and economics of silicon carbide matrix composites by chemical vapor infiltration. Roman, Yvette G.; Stinton, David P. Centre Technical Ceramics-TNO, Eindhoven, Neth. Materials Research Society Symposium Proceedings (1995), 365 343-50. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 123:176964 AN 1995:774254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 35 refs. A no. of processing techniques that are currently in use for the development and prodn. of continuous fiber reinforced ceramic composite materials are described. The limited no. of available processing routes are compared with respect to the resulting material properties. The chem. vapor infiltration (CVI) technique is one of the most extensively developed methods. During the last decade, at least five different modifications of the isobaric isothermal CVI principle have been developed; each route having its own benefits. CVI techniques have now been developed to the extent that industrial commercialization is being realized. Projected cost aspects of the various CVI manufg. techniques are examd. and compared.

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Properties of SiC-SiC composites produced using CVR converted graphite cloth to SiC cloth. Kowbel, W.; Kyriacou, C.; Gao, F.; Bruce, C. A.; Withers, J. C. MER corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1995), 365 197-202. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177312 AN 1995:774236 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a new SiC reinforcement based upon a conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. This new SiC filaments exhibit an excellent creep resistance at temps. up to 1600C. Several SiC-SiC composites were fabricated using graphite fabric converted to SiC fabric utilizing the CVR process combined with a slurry infiltration and CVI densification. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites are discussed.

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Chemically bonded ceramic matrix composites: densification and conversion to diffusion bonding. Johnson, Bradley R.; Guelguen, Mehmet A.; Kriven, Waltraud, M. Department Materials Science and Engineering, University Illinois, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1995), 365 67-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177295 AN 1995:774216 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC's). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl2O4) powders were used as the chem. bonding matrix phase, while calcia-stabilized zirconia powders were the second phase material. Samples contg. up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal anal. (DTA/TGA). The phys. characteristics of this novel CMC were characterized by hardness, d., and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD.

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Oxidative catalytic decomposition of toxic gases using hydroxyapatite and fluorhydroxyapatite. Palucka, Timothy P.; Eror, Nicholas G.; McNamara, Thomas A. Department Materials Science and Engineering, University Pittsburgh, Pittsburgh, PA, USA. Materials Research Society Symposium Proceedings (1995), 368(Synthesis and Properties of Advanced Catalytic Materials), 275-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:151604 AN 1995:734790 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An oxidative catalytic route to decomp. nerve gases was studied using hydroxyapatite (HA, Ca10(PO4)6(OH)2) and its partially fluorinated analog fluorhydroxyapatite (FHA, Ca10(PO4)6Fx(OH)2-x). Samples were prepd. with surface areas of 34-238 m2/g to study surface area effects; 1.2 wt.% Pt was deposited on 1 substrate to study the effect of a transition metal on activity and selectivity. Reaction studies were performed using di-Me methylphosphonate, a nerve gas simulant, in a stream of 80% N and 20% O at 573 K and atm. pressure. High surface area FHA samples showed an increase in the protection period (period of 100% conversion) with increasing F substitution; such an increase was not seen for low surface area FHA samples. In the absence of Pt, the reaction products were CH3OH and di-Me ether; with Pt, CO2 was also obtained.

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Toxicity of sulfur mustard in adult rat lung organ culture. Sawyer, Thomas W.; Wilde, Paul E.; Rice, Paul; Weiss, M. Tracy. Medical Countermeasures Section, Defence Research Establishment Suffield, Box 4000, Medicine Hat, Alberta, Can. Toxicology (1995), 100(1-3), 39-49. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 123:104668 AN 1995:700024 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The toxicity of the chem. warfare agent sulfur mustard, (bis-(2-chloroethyl)sulfide, HD), was examd. in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concn. (LC50) of HD in these cultures was reproducible, and in the M range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathol. examn. of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochem., and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulfur mustard.

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Characterization and surface chemistry of uncoated and coated silicon nitride powders. Schmidt, H.; Nabert, G.; Ziegler, G.; Goretzki, H. Inst. Materialforschung, Univ. Bayreuth, Bayreuth, Germany. Journal of the European Ceramic Society (1995), 15(7), 667-74. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 123:90766 AN 1995:695131 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various Si3N4 powders, produced by different procedures, were characterized by imaging (TEM) and anal. methods (EDS, FT-IR, XPS) in the as-received state as well as after doping with a metal oxide (MgO). For the doping, an alternative procedure to the usual methods was applied based on sol. organometallic compds. Anal. TEM combined with lateral resoln. element anal. and XPS measurements was used for morphol., structural and anal. characterization. The distribution of the dopant was deduced from measurements of XPS sputter depth profiles. These investigations were supplemented by FT-IR measurements to det. qual. and semi-quant. the reactive groups on the particle surfaces of the as-received powders. For comparison, measurements were performed with Si3N4 powders which were doped by the above chem. procedure and by mech. mixing. The results of the various characterization methods are interpreted in the form of a model display for surface reactions of organometallic doping reagents on the surfaces of ceramic particles. The results show that Si3N4 powders with high concn. of OH groups on their particle surface reveal very good distribution of the fluxing element (layer-like coating).

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Influence of crystallographic orientation, chemical inhomogeneities, material transport anisotropy and elastic strain energy on the migration of grain boundaries in chromium-doped alumina during internal reduction. Backhaus-Ricoult, Monika; Peyrot-Chabrol, A.; Chiron, R.; Hagege, S. Cent. d'Etudes Chim. Metall., CNRS, Vitry, Fr. Materials Research Society Symposium Proceedings (1995), 357(Structure and Properties of Interfaces in Ceramics), 293-9. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:90732 AN 1995:685875 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Diffusion-induced grain boundary migration is obsd. during internal redn. of chromium-doped alumina. It occurs because grain boundary diffusion is fast compared to lattice diffusion of oxygen. The oxygen chem. potential relaxes between grain boundaries and adjacent grains. Migration to either side of the boundary is controlled by multiple factors: chem. compn. differences between adjacent grains, elastic strain energy differences on the two sides of the boundary plane or by more rapid oxygen relaxation when the c-axis of a grain is perpendicular to the boundary plane.

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Synthesis and chemical stability of NaSn2P3O12. Breval, E.; Harshe, G.; Agrawal, D. K.; Limaye, S. Y. Intercoll. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Journal of Materials Science Letters (1995), 14(10), 728-31. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:39204 AN 1995:606064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

NaSn2P3O12 and NaZr2P3O12 powders were prepd. by solid-state reaction methods and sintered at 1050-1200. The resulting pellets were characterized in terms of d., thermal expansion, and phase compn. before and after chem. stability tests. Chem. stability tests were performed in polethylene containers in 3 solns., H+ + SO42- (pH = 0.5), Na+ + H+ + SO42- (pH = 0.7), and Na+ + OH- (pH + 14.3). Results indicate that NaSn2P3O12 is a very stable NZP compd. in high and low pH solns. (pH + 0.5-14.3) as compared to the parent compn. NaZr2P3O12, which shows high losses, esp. in alk. leachants. The surface-to-vol. of a single phase NaSn2P3O12 material, sintered without sintering agents, hardly affects the dissoln. Use of a sintering agent may result in a highly reactive grain boundary phase, the amt. of which may exceed the amt. of added sintering aid.

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Low-level detection of chemical agent simulants in meat and milk by ion trap mass spectrometry. Buchanan, Michelle V.; Hettich, Robert L.; Xu, Jing Hai; Waters, Larry C.; Watson, Annetta. Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Building 5510, MS/6365, Oak Ridge, TN, USA. Journal of Hazardous Materials (1995), 42(1), 49-59. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 123:31526 AN 1995:596587 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. methods for the detection of two chem. warfare agent simulants, diisopropyl methylphosphonate and chloroethylethylsulfide, in beef tissue and milk were demonstrated to be effective to levels as low as 50-100 ppb. These methods are based upon thermal desorption into an ion trap mass spectrometer. Selective detection of the target compds. is achieved by isobutane chem. ionization in combination with collision-induced dissocn., which yields characteristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limits achieved with this method suggest that it may be possible to take small tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the anal. In addn., because the new methods may be performed more quickly than conventional methods requiring substantial sample prepn. and anal. time, more samples could be analyzed.

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The effect of ceria co-doping on chemical stability and fracture toughness of Y-TZP. Boutz, M. M. R.; Winnubst, A. j. a.; Van Langerak, B.; Scholtenhuis, R. J. M. Olde; Kreuwel, K.; Burggraaf, A. J. Faculty of Chemical Technology, University of Twente, Enschde, Neth. Journal of Materials Science (1995), 30(7), 1854-62. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 122:271892 AN 1995:504770 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and ageing resistance of yttria, ceria-stabilized tetragonal zirconia polycrystals (Y, Ce-TZP) were evaluated as a function of grain size and ceria content. Very fine grained, fully dense materials could be produced by sinter forging at relatively low temps. (1150-1200C). The aging resistance in hot water (185C) of 2 mol% Y2O3-stabilized TZP is strongly enhanced by alloying with ceria. The ceria content necessary to avoid degrdn. completely, decreases with grain size. The toughness of fully dense Y, Ce-TZP is 7-9 MPa m1/2 for grain sizes down to 0.2 m. No or very little transformation took place during fracturing and no clear variation with grain size was obsd. for the toughness at grain sizes up to 0.8 m. Reversible transformation and crack deflection may explain the obsd. toughness values.

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Microstructure and chemistry of second phases in MgO- and NiO-codoped alumina by analytical transmission electron microscopy. Park, K.; Vasilos, T.; Sung, C. Cent. Advanced Materials Dep. Chem. Nuclear Eng., Univ. Massachusetts, Lowell, MA, USA. Journal of Materials Science Letters (1995), 14(4), 261-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 122:167982 AN 1995:415637 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects MgO-NiO-codoping on microstructure and chem. of 2nd phases, segregated particles and cryst. defects in alumina ceramics were examd. MgO-NiO-codoping contributed significantly to the prepn. of dense fine-grained alumina. It appeared that Ni-Al and Ni-Mg-Al spinels, segregated Ni particles, and K-'' alumina ppts. were formed at triple points or at grain boundaries, because the concns. of the MgO and NiO dopants were higher than their solid solubilities. In particular, the codopants formed a Ni-Mg-Al spinel as well as a Ni-Al spinel, because Mg2+ and Ni2+ were partitioned in the cation position of the spinel structure.

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Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry. Bentley, J.; Horton, L. L.; McHargue, C. J.; McKernan, S.; Carter, C. B.; Revcolevschi, A.; Tanaka, S.; Davis, R. F. Metals and Ceramics Div.r., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1994), 332(Determining Nanoscale Physical Properties of Materials by Microscopy and Spectroscopy), 385-90. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:87360 AN 1995:266442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resoln. of <5 nm. Anal. of Fe L23 white lines indicates a low-spin state with a charge transfer of .apprx.1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2-5% in the Co:O stoichiometry were measured across 100-nm-thick Co3O4 layers in an oxidized directionally solidified CoO-ZrO2 eutectic, with the highest O levels near the ZrO2. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for Co3O4 have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid soly. occurred in an AlN-SiC film grown by low-temp. mol. beam epitaxy (MBE) on (6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycryst. AlN on SiC, interfacial 8H Sialon (aluminum silicon oxynitride) and pockets of Si3N4-rich '-Sialon in the SiC were detected.

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Chemically bonded ceramics as an alternative to high temperature composite processing. Gulgun, Mehmet A.; Johnson, Bradley R.; Kriven, Waltraud M. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1994), 346(Better Ceramics through Chemistry VI), 511-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:15230 AN 1995:174876 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Processing of multi-phase ceramic composite materials using chem. bonded ceramics as a binding agent appears to be a promising route for fabricating complex-shaped structures. In a zirconia-calcium aluminate ceramic matrix composite, the hydraulic property of fine, monocalcium aluminate (CaAl2O4) powders was used to prep. strong prefired bodies. The changes in the phys. characteristics of the composite during the conversion from a chem. bonded compact into a sintered composite were studied using thermogravimetric analyses (TGA), X-ray diffraction and SEM. The d. and the hardness of the chem. bonded and sintered composite were measured.

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Assessing delayed neurotoxicity in rodents after nerve gas exposure. Husain, K.; Pant, S. C.; Vijayaraghavan, R.; Singh, Ram. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(2), 161-4. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:294553 AN 1994:694553 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Delayed neurotoxicity of an organophosphorus nerve gas, Sarin (a chem. warfare agent) following repeated inhalation exposure in rats and mice, was studied by behavioral, biochem. and histopathol. analyses. Rats exposed to Sarin aerosols (12.5 mg/m3 for 20 min) daily for ten days did not exhibit any clin. sign of delayed neurotoxicity. Neurotoxic esterase (NTE) activity in the brain, spinal cord and platelets was significantly inhibited, but the inhibition was below the threshold. Histopathol. examn. of spinal cord did not show any axonal degeneration. Mice exposed to Sarin aerosols (5 mg/m3 for 20 min) daily for ten days developed mild ataxia and muscular weakness of the hind limb on 14th day after the start of exposure. NTE activity was significantly inhibited in brain, spinal cord and platelets. Histopathol. of spinal cord showed focal axonal degeneration. Acetyl-choline esterase activity in the platelets of both the animals was significantly inhibited. The authors conclude that mice are sensitive to delayed neurotoxicity induced by repeated exposure to Sarin whereas rats are insensitive.

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Clean-up of chemical warfare agents on soils using simple washing or chemical treatment processes. Amos, Denys; Leake, Brian. DSTO, Aeronautical and Maritime Research Laboratory, P.O. Box 4331, Melbourne, Victoria, Australia. Journal of Hazardous Materials (1994), 39(1), 107-17. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:262645 AN 1994:662645 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several simple processes have been studied for the destruction of chem. agents, Soman and Mustard, on soils. A double wash or an extended single wash with water was effective in removing Mustard and Soman from soil; addn. of either anionic or cationic surfactant did not improve removal efficiency. Soils with higher org. carbon content were more difficult to decontaminate. The most effective chem. process for the removal of Mustard was treatment with hypochlorite; treatment with Na2CO3 or NaOH were almost as effective as hypochlorite in cleaning Mustard contaminated soil. Soman was removed most effectively by treatment with Na2CO3. Overall the most efficient process for the destruction of both Mustard and Soman was treatment with Na2CO3 soln.

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Liquid phase sintering, electrical conductivity, and chemical stability of lanthanum chromite doped with calcium and nickel. Christie, G. M.; Middleton, P. H.; Steele, B. C. H. Dep. Mater., Imperial Coll. Sci., Tech. Med., London, UK. Journal of the European Ceramic Society (1994), 14(2), 163-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:236480 AN 1994:636480 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The substitution of 10 mol% nickel for chromium in calcium-doped lanthanum chromite has been shown to promote rapid densification of the compd. at low temps. in air by the form of a transient liq. phase. Liqs. were generated via the decompn. of CaCrO4 second phase material present in calcined powders. During elec. cond. measurements at 1000C, severe microstructural degrdn. occurred at atms. of H2 and CO2. The processes leading to chem. degrdn. are attributed to the pptn. of Ni from the (La,Ca)(Cr,Ni)O3 solid soln. and to the decompn. of small amts. of residual CaCrO4 which remains at grain boundaries and triple points after sintering. DTA studies on CaCrO4 in CO2 and H2 atms. suggested that the degrdn. due to CaCrO4 decompn. was primarily a result of the reaction of CaO with CO2 to form CaCO3. The presence of H2 gas is thought to catalyze this reaction via the formation of large amt. of CaO during the decompn. of CaCrO4. Degrdn. is more severe in atms. contg. a mixt. of CO2 and H2 gases than in either gas on its own.

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Photochemical degradation of a toxic organophosphorus analog (PMSF) in microemulsion media. Yang, Yun; Donegan, Sheila; Patel, Ramesh C.; Ward, Anthony J. I. Center for Advanced Materials Processing, Clarkson University, Potsdam, NY, USA. Chemosphere (1994), 28(11), 1967-76. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 121:217331 AN 1994:617331 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A study has been made of the photodegrdn. of an analog, phenylmethylsulfonyl fluoride (PMSF), of a toxic chem. warfare agent. The agent was solubilized in a water-in-oil surfactant stabilized microemulsion system comprising sodium dodecyl sulfate, pentanol and water. Loss of the parent PMSF mol. upon exposure of the system to UV irradn. was monitored by 19F NMR spectroscopy. Consideration of the changes in the chem. shifts, splittings in conjunction with GC/Mass spectroscopy data strongly suggest the degrdn. leads to partial fluorination of pentanol. Anal. of peak areas also indicates the formation of volatile degrdn. products such as HF. The addn. of TiO2 or hydroquinone to the system did not appreciably change the overall amts. of degrdn. The results are interpreted in terms of the possible radical based reaction pathways and show that such a microemulsion medium to have significant potential as a vehicle for effecting such a degrdn. process.

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Comparative evaluation of high protein against normal protein diet in combination with carbamates against organophosphorus intoxication in rats. Chatterjee, A.K.; Sikder, Nirmala; Sikder, A.K. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(1), 11-14. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:197892 AN 1994:597892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The relative efficacy of an isocaloric high protein diet (HPD) contg. 59 per cent protein, in comparison to a conventional diet contg. 21 per cent protein, as applied in the alleviation of toxicity of diisopropyl phosphorofluoridate (DFP) and Me iso-Pr phosphonofluoridate (sarin), has been reported. In combination with well-known prophylactics like carbamates and cholinolytics like atropine against nerve gas toxicity, HPD appears to be superior to the conventional diet as studied by survival time measurements. Apart from carbamates, atropine and mecamylamine, HPD may be treated as an addnl. prophylactic agent to guard against the toxicity of DFP and sarin, which are being used as war chems.

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The surface chemistry of silicon nitride powder in the presence of dissolved ions. Hackley, V. A.; Malghan, S. G. Ceram. Div., Natl. Inst. Standards and Technol., Gaithersburg, MD, USA. Journal of Materials Science (1994), 29(17), 4420-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 121:185440 AN 1994:585440 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Colloidal processing of silicon nitride (Si3N4) powders depends largely on the control of reactions at the solid-soln. interface. The role of dissolved ions in the surface chem. of Si3N4 powders has been investigated, and the implications of these results for the effects of impurities, contaminants and additives in processing are discussed. The interaction of ions at the solid-soln. interface was characterized by particle electrokinetic behavior detd. from electroacoustic measurements in moderately concd. suspensions. Ions were classified according to chem. similarity and surface specificity. Specific adsorption was inferred from the movement of the isoelec. point relative to the endemic "native" value. Most simple univalent electrolytes behaved indifferently towards the Si3N4 surface, with the exception of fluoride which specifically adsorbed and may have formed a strong complex with surface silicon sites. The alk.-earth cations exhibited a similar weak specificity. In the presence of hydrolyzable transition metal cations, powder surface chem. was controlled by the adsorption of hydroxy metal complexes and by the soly. of a surface-pptd. metal hydroxide phase. Oxo anions, such as sulfate and carbonate, adsorbed specifically on the Si3N4 surface, but the interactions were weaker than previously obsd. on metal oxide surfaces.

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X-ray photoelectron spectroscopy of uv laser irradiated sapphire and alumina. Pedraza, A. J.; Park, J. W.; Meyer, H. M., III; Braski, D. N. Dep. Materials Science Engineering, Univ. Tennessee, Knoxville, TN, USA. Journal of Materials Research (1994), 9(9), 2251-7. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 121:162453 AN 1994:562453 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

XPS was performed in as-received, thermally annealed, and laser-irradiated sapphire and alumina specimens to study the effects of the different treatments on surface chem. and properties. Laser irradiations with a 308 nm wavelength laser were performed in air and in a reducing atm. consisting of a mixt. of Ar and 4% hydrogen. The at. percentages of carbon, aluminum, and oxygen were measured in all the specimens. Particular attention was paid to the percentages of oxygen in the oxide and in a hydroxyl state. The XPS analyses clearly established that a very thin film of metallic aluminum is formed on the surface of both alumina and sapphire substrates when they are irradiated under a reducing atm. However, the film is discontinuous because it is elec. insulating. Substrates irradiated in air have metallic aluminum only for fluences below 0.4 J/cm2. The valence band photoemission spectra of as-received, annealed, and laser-irradiated specimens were measured. In irradiated specimens, the width of the valence band spectra was found to decrease by .apprx.10%. One possible cause of this decrease is the generation of point defects during laser irradn. Electroless copper deposition occurs on sapphire and alumina substrates if their surface has been activated by laser irradn. The time required for copper deposition was monitored by measuring the elec. resistivity in the irradiated area while the substrates were immersed in an electroless bath. The kinetics of deposition on laser-activated substrates and the XPS results show that the presence of metallic aluminum accelerates the deposition process. However, the presence of aluminum is not the sole reason for laser activation in alumina. Very strong metal-ceramic bonding is produced after thermal annealing of samples having preirradiated substrates. This result is explained in terms of the excess oxygen that is present at the ceramic surface after irradn.

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X-ray absorption spectroscopy study of the local structure and the chemical state of yttrium in polycrystalline -alumina. Loudjani, M. K.; Cortes, R. Lab. Metallurgie Structurale, CNRS, Orsay, Fr. Journal of the European Ceramic Society (1994), 14(1), 67-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:162396 AN 1994:562396 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. state and local structure around the yttrium ion in doped polycryst. -alumina (0.03  mol% Y2O3  1) system was examd. by extended x-ray absorption fine structure (EXAFS) measurements for yttrium K-edge energy. In the case of highly doped alumina samples (0.1 and 1 mol% Y2O3) most of the yttrium is pptd. as a Y3Al5O12 phase, whereas in the dil. doped alumina sample (0.03 mol% Y2O3) yttrium is in solid soln., being located on the octahedral aluminum sites. The yttrium ion size, comparatively greater than that of the aluminum ion, induces locally a significant distortion of the oxygen ion lattice. This effect creates point defects in the nearest neighbor shell of the yttrium: vacancy (Vo..) and interstitial (Oi'') oxygen point defects.

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Constitution of the -alumina phase in chemically produced mullite precursors. Schneider, H.; Voll, D.; Saruhan, B.; Schmucker, M. Inst. Mater. Res., German Aerosp. Res. Establ., Cologne, Germany. Journal of the European Ceramic Society (1993), 13(5), 441-8. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:89568 AN 1994:489568 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The temp. development of type II mullite precursor powders have been studied in the temp. range of 150C (as-received) and 1150C. X-ray diffraction measurements, IR and 29Si and 27Al NMR spectroscopy and anal. transmission electron microscopy have been performed on the heat-treated precursors. The investigations had the aim of contributing to the frequently discussed question, whether Si is incorporated into the -alumina spinel being formed as a transient phase in type II mullite precursors. The as-received precursors consist of relatively large spherical particles ( 05 m) of noncryst. SiO2 and of much finer-grained agglomerates of pseudo-boehmite crystals (-AlO(OH),  20 nm), which are embedded in a SiO2 matrix. Above 350C, pseudo-boehmite transforms to spinel-type alumina (-Al2O3). During this transformation, all Si existing in the SiO2 matrix of the pseudoboehmite agglomerates is incorporated into -Al2O3 corresponding to a SiO2 content of 12 mol% at 500C. Up to 750C, the SiO2 content of the -alumina remains const. but above this temp. it gradually rises and reaches a max. amt. of 18 mol% at 1150C. A marginal decompn. of the spherical non-cryst. SiO2 particles may be the sources to provide diffusion of Si species into the -alumina during a temp. increase above 750C. It is most likely that Si species diffuse into the -alumina crystals along the crystallite boundaries. The diffusion process and Si incorporation are facilitated with the temp. increase.

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Quantitative analysis of Si3N4 microstructure response on interface chemistry. Meissner, E.; Unger, S.; Kleebe, H.-J.; Ziegler, G. Univ. Bayreuth, Bayreuth, Germany. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 471-5. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:89560 AN 1994:489560 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. microstructure anal. was performed on gas-pressure sintered Si3N4 materials (SSN) by employing an image processing system. Variations in grain-diam. distribution and aspect-ratio distribution with changing additive compn. and annealing time, resp., were investigated. Clear evidence was found that both interface compn. and post-sintering anneal can strongly affect the matrix grain morphol. For the Y2O3-doped material, extended annealing time supported the formation of Si3N4 grains with increased diam. and length via Ostwald ripening. Moreover, the aspect-ratio distribution was shifted to higher values indicating anisotropic grain growth. The addn. of Al2O3 + ZrO2, compared to SSN doped with Y2O3, resulted in a finer microstructure with still high aspect ratios. This chem. effect is closely related to the viscosity of the liqs. at processing temps. Furthermore, ZrO2 addn. results in a more pronounced transgranular fracture mode, while Y2O3-contg. SSN predominantly revealed intergranular fracture. The influence of annealing time and interface chem. on both microstructure evolution and resulting fracture toughness is discussed.

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Surface chemical interactions of Si3N4 with polyelectrolyte deflocculants. Hackley, V.A.; Premachandran, R.; Malghan, S.G. Mater. Sci. Eng. Lab., Natl. Inst. Stand. Technol., Gaithersburg, MD, USA. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 679-82. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:41008 AN 1994:441008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interaction of org. polyelectrolyte deflocculants at the Si3N4 solid-soln. interface was investigated using electroacoustic measurements, polymer adsorption and particle size distribution anal. One cationic and two anionic polymers were studied: quaternized poly(diamine epoxychlorohydrin), ammonium poly(methacrylate) and poly(acrylic acid), resp. Electrostatic interactions are emphasized as a function of pH, concn. and mol. wt.

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Metabolite pharmacokinetics of soman, sarin and GF in rats and biological monitoring of exposure to toxic organophosphorus agents. Shih, Ming L.; McMonagle, Joseph D.; Dolzine, Theodore W.; Gresham, Vincent C. US Army Med. Res. Inst. Chem. Def., Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1994), 14(3), 195-9. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 121:28848 AN 1994:428848 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study reports on the pharmacokinetics of the elimination of the metabolites of three toxic organophosphorus compds. (soman, sarin and GF). Urine, blood and lung tissue were collected from rats dosed s.c. at 75 g kg-1. Urinary excretion of the metabolite was the major elimination route for these three compds. The major differences among them were primarily the extent and rate of excretion. The hydrolyzed form, alkylmethylphosphonic acid, was the single major metabolite formed and excreted in urine by a non-saturable mechanism. Nearly total recoveries of the given doses for sarin and GF in metabolite form were obtained from the urine. The terminal elimination half-lives in urine were 3.7  0.1 and 9.9  0.8 h for sarin and GF, resp. Soman metabolite showed a biphasic elimination curve with terminal half-lives of 18.5  2.7 and 3.6  2.2 h. Soman was excreted at a slower rate with a recovery of only 62%. Lung was the major organ of accumulation for soman. In blood the toxic agents were concd. more in red blood cells than in plasma. The acid metabolites can serve as a better chem. marker for monitoring organophosphorus exposure in humans via their higher concn. and longer half-life in urine than the parent compds.

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Movement of chemical warfare agent simulants through porous media. Jenkins, R. A.; Buchanan, M. V.; Merriweather, R.; Ilgner, R. H.; Gayle, T. M.; Watson, A. P. Analytical Chemistry Division, Oak Ridge National Laboratory, Building 4500S, MS-6120, P.O. Box 2008, Oak Ridge, TN, USA. Journal of Hazardous Materials (1994), 37(2), 303-25. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:16666 AN 1994:416666 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A measurement protocol is documented and data are presented to characterize the permeation of chem. warfare agent simulants through the porous construction materials brick, cinder block, gypsum wall board, and wood. These data will be used to develop guidelines for access ("reentry") to potentially contaminated properties if nerve or vesicant agents are released during any phase of the US Department of the Army's Chem. Stockpile Disposal Program. A novel permeation cell design allowed sampling of air vols. adjacent to the spiked face, breakthrough face, and lateral face of each test medium at two temps. Simulant movement through wood is nearly always in the direction of the wood grain. Two-dimensional breakthrough was obsd. in brick and gypsum wall board. The sulfur mustard simulant broke through all test media in less than 60 min; nerve agent simulant breakthrough required several hours. Surface decontamination of wood with high-test hypochlorite is 95% effective.

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Pharmacology of organophosphates. Koelle, George B. Med. Sch., Univ. Pennsylvania, Philadelphia, PA, USA. Journal of Applied Toxicology (1994), 14(2), 105-9. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 121:2654 AN 1994:402654 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 8 refs. The cholinergic nerve fibers, which employ acetylcholine (ACh) as a neurohumoral transmitter, and the results of their activation are listed. The reactions between the enzyme acetylcholinesterase (AChE), its natural substrate, ACh, and the various types of inhibitors are described. The limited therapeutic uses of the anticholinesterase (anti-ChE) agents are considered. The toxicol. effects encountered when the anti-ChE agents are employed as insecticides or as chem. warfare (CW) agents are discussed. Certain anti-ChE agents produce also a delayed neurotoxic effect which is apparently unrelated to the inhibition of AChE.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson, Barry W.; Kawakami, Thomas G.; Cone, Norman; Henderson, John D.; Rosenblatt, Leon S.; Goldman, Marvin; Dacre, Jack C. Inst. Toxicol., Univ. California, Davis, CA, USA. Toxicology (1994), 86(1-2), 1-12. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 120:263586 AN 1994:263586 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (tabun, phosphoramidocyanidic acid, dimethyl-, Et ester) as part of a program to demilitarize chem. warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but not in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only 3 of the 5 assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Effect of chemically added zirconia and yttria mechanical properties of zirconia-dispersed alumina. Ranjbar, Khalil; Rao, Boddapati T.; Mohan, Tallapragada R. Rama; Harendranath, Chilkunda S. Dep. Metall. Eng., Indian Inst. Technol., Bombay, India. American Ceramic Society Bulletin (1994), 73(2), 63-6. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 120:171374 AN 1994:171374 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Alumina powders dispersed with monoclinic, tetragonal, and cubic zirconia were prepd. by evapg. a colloidal dispersion of alumina powders in solns. contg. zirconium and yttrium salts. The dried and calcined powders were compacted, sintered, and characterized. The results demonstrated a clear toughening effect by the zirconia on the alumina ceramics. The alumina contg. 20-wt%-yttria-stabilized tetragonal zirconia had the max. toughness.

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Chemical vapor infiltration of silicon carbide with microwave heating. [Erratum to document cited in CA119(2):13852e]. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(12), 3251. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 120:141948 AN 1994:141948 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The errors were not reflected in the abstr. or the index entries.

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Chemical compatibility between silicon-based and titanium-based ceramics. Wang, L.; Wada, H. Dep. Mater. Sci. Eng., Univ. Michigan, Ann Arbor, MI, USA. Journal of Materials Synthesis and Processing (1993), 1(3), 181-93. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:277176 AN 1993:677176 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. compatibility between Si-based ceramics and Ti-based ceramics was studied to establish guidelines for the processing of related composites. Phase stabilities were calcd. for the Si-Ti-B-C, Si-Ti-B-N, and Si-Ti-B-C-N systems as a function of B activity and N pressure or C activity. SiC is compatible with TiC, TiN, or TiB2, depending on the range of these parameters. Si3N4 and TiN appear to be compatible in a certain range of N2 pressure and C activity, but Si3N4 and pure TiC will not coexist. However, the fact that TiC and TiN can form a solid soln., TiC1-xNx, suggests that Si3N4 and TiC1-xNx may be obsd. in the presence of both C and N2. The Si3N4 + TiB2 2-phase region is limited in such a narrow range of N2 pressure and B activity that processing and application of TiB2/Si3N4 composites would be very difficult. High-temp. solid-state expts. were carried out with selected systems to verify phase stability diagrams. The results of reactions were in agreement with the thermodn. prediction. A high-d. TiB2/SiC composite was prepd. as an example of the application of phase stability diagrams.

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Thermal and acid catalyzed conversion of organic phosphorus compounds. De Lijser, H. J. P.; Mulder, P.; Louw, R. Cent. Chem. Environ., Leiden Univ., Leiden, Neth. Chemosphere (1993), 27(5), 773-8. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:233159 AN 1993:633159 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The org. P compds. tri-Bu and tri-Me phosphate (I and II, resp.), tri-Me phosphite (III), and di-Me phosphonate (IV) were thermolyzed using a plug flow (gas-phase) reactor. I and II proved to be sensitive to acid (wall) catalysis and can be fully degraded at temps. of .mchlt.400. III can isomerize to II and IV. In contrast, IV requires a temp. of >750 for complete conversion; admixed with II it counteracts the smooth acid-mediated degrdn. of II. Unlike real thermolysis at elevated temps., preferably in a reducing atm. of hydrogen, mere acid catalysis is not generally applicable for effectively destroying a variety of ecotoxic org. P compds.

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Preparation of uniformly calcia-doped zirconia. Hill, J.; Newhouse, M.; Xue, J.; Dieckmann, R. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Journal of Materials Synthesis and Processing (1993), 1(2), 101-9. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:232072 AN 1993:632072 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The prepn. of dense samples of high-purity zirconia doped with varying, small contents of CaO has been explored by means of traditional ceramic techniques with sintering and hot-pressing as well as a chem. soln. method. First, CaO-doped samples were prepd. by traditional ceramic methods. Their homogeneities were checked by SEM with x-ray mapping. CaO-dopant distribution was not uniform in all samples with overall CaO contents below 7 mol%. The difficulty in prepg. uniformly doped zirconia with small CaO contents led to exploration of the use of chem. soln. processing techniques. When exploring such techniques, the products of each process step were characterized by x-ray diffraction and electron microprobe anal. The characterization results enabled identification of a processing route which is suitable for prepg. dense, high-purity zirconia uniformly doped with CaO at low concns.

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A model for the isothermal isobaric chemical vapor infiltration (CVI) in a straight cylindrical pore. Application to the CVI of silicon carbide. Fedou, R.; Langlais, F.; Naslain, R. Lab. Compos. Thermostruct., CNRS, Pessac, Fr. Journal of Materials Synthesis and Processing (1993), 1(2), 61-74. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:208796 AN 1993:608796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A previously described modeling of the chem. vapor infiltration (CVI) process in a straight cylindrical pore is applied to the deposition of SiC-based ceramics from MeSiCl3-H2 in the case of a 1st-order kinetic law with respect to MeSiCl3. The model gives concns. and deposit thickness profiles along the pore at any stage of the densification and, particularly, at the end of the process when the pore becomes sealed. The infiltration homogeneity is predicted to be improved by decreasing the aspect ratio of the pore and the CVI temp. and, under conditions of Fick diffusion, by decreasing the total pressure and the pore diam. The model is validated by the good fit between the deposit thickness profiles along the pore calcd. after adjustment of the kinetic data and exptl. profiles for a 34-m straight pore.

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Nicalon-fiber-reinforced silicon carbide composites via polymer solution infiltration and chemical vapor infiltration. Kim, Young Wook; Song, Jin Soo; Park, Sang Whan; Lee, Juen Gunn. Struct. Ceram. Lab., Korea Inst. Sci. Technol., Seoul, S. Korea. Journal of Materials Science (1993), 28(14), 3866-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 119:186895 AN 1993:586895 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A new, faster process was developed for the fabrication of Nicalon-fiber-reinforced SiC composites by combining polymer soln. infiltration (PSI) and chem. vapor infiltration (CVI). The process led to the near-net-shape fabrication of fiber-reinforced ceramic-matrix composites and reduced infiltration time. Typical flexural strength and fracture toughness of these composites were 296 MPa and 10.9 MPa.m1/2 at room temp. and 252 MPa and 9.6 MPa.m1/2 at 1000, resp. The composites exhibited load-carrying capability after crack initiation.

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The effect of glass chemistry on the microstructure and properties of self reinforced silicon nitride. Pyzik, Aleksander J.; Carroll, Daniel F.; Hwang, C. James. Adv. Ceram. Lab., Dow Chem. Co., Midland, MI, USA. Materials Research Society Symposium Proceedings (1993), 287(Silicon Nitride Ceramics), 411-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:186804 AN 1993:586804 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The advantage of self-reinforced silicon nitride is the in-situ control of the microstructure. This control is provided in large degree by the chem. of glassy phase which can be adjusted to tailor the morphol. of silicon nitride grains as well as the matrix-reinforcement interface. The presence of high aspect ratio silicon nitride grains is necessary but not sufficient condition to produce materials with optimum properties. For max. flexure strength and fracture toughness, an optimized glass matrix is required.

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Microwave assisted chemical vapor infiltration. Devlin, D. J.; Currier, R. P.; Barbero, R. S.; Espinoza, B. F.; Elliott, N. Mater. Sci. Technol. Div., Los Alamos Natl. Lab., Los Alamos, NM, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 245-50. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144800 AN 1993:544800 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A microwave-assisted process for prepn. of continuous fiber-reinforced ceramic-matrix composites is described. A simple app. combining a chem.-vapor-infiltration reactor with a conventional 700-W multimode oven is described. Microwave-induced inverted thermal gradients are exploited with the ultimate goal of reducing processing times on complex shapes. Thermal gradients in stacks of SiC (Nicalon) cloths have been measured using optical thermometry. Initial results on the inside-out deposition of SiC via decompn. of MeSiCl3 in H are presented. Several key processing issues are identified and discussed.

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Chemical vapor deposition of multiphase boron-carbon-silicon ceramics. Golda, E. Michael; Gallois, B. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 167-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144796 AN 1993:544796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Specific compns. of boron-carbon-silicon ceramics exhibit improved abrasive wear and good thermal shock resistance, but require bulk sintering at temps. in excess of 2100K. The formation of such phases by CVD was examd. at 1073-1573K. Methyltrichlorosilane (CH3SiCl3), boron trichloride, and methane were chosen as reactant gases, with hydrogen as a carrier gas and diluent. The coatings were deposited in a computer-controlled, hot-wall reactor at a pressure of 33 MPa. Below 1473K the coatings were amorphous. At higher temps. nonequil. reactions controlled the deposition process. The most common coating consisted of a silicon carbide matrix and a silicon boride, SiB6, dispersed phase. Multiphase coatings of B + B4C + SiB6 and SiC + SiB6 + SiB14 were also deposited by controlling the partial pressure of methane and boron trichloride. Non-equil. thermodn. anal. qual. predicted the exptl. deposited multiphase coatings.

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CVD of silicon nitride plate from trichlorosilane-ammonia-hydrogen mixtures. Lennartz, J. W.; Dowell, M. B. Union Carbide Coat. Serv. Corp., Parma, OH, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 161-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144795 AN 1993:544795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preferred conditions for deposition of thick -Si3N4 plate from HSiCl3-NH3-H2 on the vertical surfaces of a low-pressure, hot-wall CVD reactor were identified by means of a designed expt. The design included temp. range 1300-1500, pressures 0.5-2.0 torr, and residence times 0.01-1.0 s. The vertical deposition surfaces received a viscous, laminar flow of well mixed, thermally equilibrated reactants. Plates 0.05-0.5 mm thick were produced on multiple vertical substrates 350 cm2 in area at deposition rates 5-70 m/h. Plates 0.5-4.0 mm thick were produced on horizontal substrates at deposition rates of 60-120 m/h. When NH3 flows in stoichiometric excess, deposition rates on vertical surfaces increase approx. linearly with the flow rate of HSiCl3 but depend little on temp., as would be expected if the reaction proceeds under mass transport control with product depletion. Multiple correlation analyses show that thickness variations in the deposit are reduced by increasing the temp. and decreasing the gas residence time. CVD silicon nitride plate produced under the optimized conditions exhibits theor. d. and is free of pores and cracks. It exhibits a columnar morphol. in which the <222> and <101> crystallog. directions are oriented preferentially normal to a surface, which consists of well-defined trigonal facets 10-50 m across. Crystallite sizes detd. by x-ray line broadening range from 0.06-1.0 m. This CVD plate is gray and contains approx. 0.5 C and 0.5 wt.% 0 as principal impurities.

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Unequivocal evidence. Black, Robin M.; Pearson, Graham S. Chem. Biol. Def. Estab., Porton/Down/Salisbury Wiltshire, UK. Chemistry in Britain (1993), 29(7), 584-5, 587. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 119:123791 AN 1993:523791 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of chem. warfare agent, Sarin, in the Kurdush village of Birjinni, Iraq, was discussed.

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Bioanalysis of organophosphate nerve agents in soil samples. Sawyer, T. W.; Weiss, M. T. Biomed. Def. Sect., Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Chemosphere (1993), 26(11), 2023-9. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:94477 AN 1993:494477 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Four soil samples that may have been spiked with chem. warfare (CW) agents and their degrdn. products were received by Defense Research Establishment Suffield as part of a multinational round-robin exercise designed to evaluate lab. methodologies for the chem. detection of CW agents in soil. After chem. anal. revealed that VX (Et S-2-diisopropyl aminoethyl methylphosphorothiolate) was the CW agent "spike", the samples were also bioassayed for their VX content by assessing their anticholinesterase activities in primary chick embryo neuron cultures. Bioassay quantitation of VX contamination in the soil samples was in good agreement with the actual spike levels and generally better than the chem. anal. results. Sequential bioassay of the samples over a two week period showed that the VX content was rapidly degraded with time. This assay complements std. chem. anal. techniques for the detection and verification of organophosphate warfare agent use.

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The effect of trace element segregation to iron/sapphire interfaces. Pope, D. P.; Smith, M. A. Dep. Mater. Sci., Univ. Pennsylvania, Philadelphia, PA, USA. Materials Research Society Symposium Proceedings (1992), 238(Structure and Properties of Interfaces in Materials), 427-32. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:77041 AN 1993:477041 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of segregation of tramp impurities such as sulfur on metal/ceramic bonding is discussed. Microstructural and chem. information is given for the Fe/sapphire interface. The segregation behavior of the interface is evaluated between 500-800. The interfacial structure is important to the segregation behavior. A possible link between the segregation of sulfur and interface void formation is presented.

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Chemical vapor infiltration of silicon carbide with microwave heating. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(5), 1057-67. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 119:13852 AN 1993:413852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is presented to describe the interaction between transport/reaction processes and the evolution of porosity in chem. vapor infiltration with microwave heating (MCVI). The anal. includes a set of partial differential equations describing the spatiotemporal variation of gaseous species concn., composite temp., porosity, and stress. Maxwell's equations were used to det. the distribution of power dissipated inside the composite. The deposition of silicon carbide was selected as a model chem. system to explore the general features of MCVI. MCVI can provide a favorable temp. distribution in the composite yielding an inside-out deposition pattern, thereby preventing entrapment of accessible porosity. For this temp. profile, tensile stresses develop at the outer regions and compressive stresses are found in the composite core. For a given system there exists a min. value of the coeff. for heat transfer from the composite surface, h, below which accessible porosity is trapped within the composite. Similarly, there exists a max. value of the incident microwave energy flux, I0, above which accessible porosity is trapped within the composite. I0 and h can be optimized for a given preform to achieve complete densification with min. processing time. Using the technique of pulsed-power, the processing time can be reduced even further without compromising d. uniformity. Power dissipation profiles in the composite depend strongly on preform thickness, microwave frequency, and relative loss factor.

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Permeation measurements of chemical agent simulants through protective clothing materials. Pal, Tarasankar; Griffin, Guy D.; Miller, Gordon H.; Watson, Annetta P.; Daugherty, Mary Lou; Vo Dinh Tuan. Health Saf. Res. Dev., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Hazardous Materials (1993), 33(1), 123-41. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 118:239880 AN 1993:239880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A method was developed to study the permeation of chem. warfare (CW) agent simulants through chem. protective clothing (CPC) materials. The exptl. results characterize some com. available CPC materials. Thirteen different CPC materials having widely differing compns. were chosen to study the permeation of 4 different liq. CW simulants (di-Me methylphosphonate, diisopropyl methylphosphonate, malathion, and Bu2S) through these CPC materials at 25. This permeation study involved a newly developed anal. technique employing room temp. fluorescence quenching of an indicator compd., phenanthrene, on filter paper. Various exptl. factors such as breakthrough time, rate of permeation, and uptake were investigated. On the basis of breakthrough time, the 13 CPC materials could be divided into 3 groups: most resistant, moderately resistant, and least resistant. Materials in the most resistant category exhibited no permeation by any of the simulants for 24 h. Breakthrough occurred in the least resistant materials in generally less than an hour, and sometimes as soon as a few minutes.

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Interfacial structure of chemical vapor infiltration carbon fiber/silicon carbide composite. Araki, H.; Noda, T.; Abe, F.; Suzuki, H. Tsukuba Lab., Natl. Res. Inst. Met., Tsukuba, Japan. Journal of Materials Science Letters (1992), 11(23), 1582-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:44089 AN 1993:44089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure at the interface in carbon fiber-SiC matrix composites prepd. by chem. vapor infiltration from EtSiCl3 was examd., and the infiltration reaction is discussed. A graphite layer formed on the carbon fiber and the SiC-SiC interface as a result of thermal decompn. of silane gas before SiC infiltration. This graphite layer, of .apprx.500 nm thickness, is assumed to assist in the crystal growth of SiC, leading to structural stability of the composites.

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Comparative evaluation of carbamates as prophylactic agents against organophosphate intoxication in rats. Chatterjee, A. K. Def. Res. Dev. Establ., Gwalior, UK. Defence Science Journal (1992), 42(2), 85-7. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 118:34070 AN 1993:34070 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper investigates the effects of two well-known carbamates, physostigmine and pyridostigmine, against organophosphorus compd. and nerve gas toxicity. Physostigmine pretreatment for 30 min enhanced the survival time of rats against DFP intoxication, whereas it did not have any effect with sarin poisoning. However, pyridostigmine pretreatment did not produce any significant effect on survival time either against DFP or sarin intoxication. Treatment with atropine along with carbamates further enhanced significantly the survival time against DFP poisoning.

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On the influence of chemical processing in the crystallization behavior of zirconium titanate materials. Navio, J. A.; Macias, M.; Sanchez-Soto, P. J. Inst. Cienc. Mater., Univ. Sevilla, Seville, Spain. Journal of Materials Science Letters (1992), 11(23), 1570-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:26385 AN 1993:26385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The crystn. phenomena of ZrTiO4 powders prepd. from various gel precursors was related to the chem. processing. Correlation of data from the literature and further expt. indicated that the presence of H2O2 in the chem. processing of the amorphous precursors plays a key role in controlling the crystn. temp. The crystn. temp. can be as low as 640.

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Effect of dopants on the sintering behavior and stability of tetragonal zirconia ceramics. Theunissen, G. S. A. M.; Winnubst, A. J. A.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1992), 9(4), 251-63. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:54278 AN 1992:454278 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure development during nonisothermal and isothermal sintering was studied for tetragonal zirconia ceramics (TZP) contg. various amts. of Y, Ce, and Ti. Smaller grain sizes were obtained when Ce-TZP was doped with Y. This could be attributed to segregation of Y to the grain boundaries, thus causing an impurity drag. With increasing temp., the grain growth rate in the Ce-TZP samples increased which could be attributed to the absence of a dragging force. The slow grain growth at low temp. in the Ce-TZP samples could be attributed to the slow diffusion kinetics of the diffusing species (trivalent and tetravalent Ce). The crit. grain size for retainment of the tetragonal phase at room temp. is larger in the Y,Ce-TZP systems compared to the Y-TZP and Ce-TZP systems. The chem. stability increased by doping Y-TZP with Ce or Ti.

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Free radical-mediated lung response to the monofunctional sulfur mustard butyl 2-chloroethyl sulfide after subcutaneous injection. Elsayed, Nabil M.; Omaye, Stanley T.; Klain, George J.; Korte, Don W., Jr. Letterman Army Inst. Res., Presidio of San Francisco, CA, USA. Toxicology (1992), 72(2), 153-65. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 117:42116 AN 1992:442116 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors postulated that vesicants may cause free radical-mediated oxidative stress distal to the site of exposure. To test this postulate in the lung, the authors injected 3 groups of 5-mo-old, male, athymic, nude mice, weighing 30-35 g with a single s.c. dose (5 L/mouse) of Bu 2-chloroethyl sulfide (BCS). Total lung wt. was not altered after treatment, but the wet/dry wt. ratio decreased 18% and Hb content increased 50 and 36% at 1 and 24 h, resp. The activity of glucose 6-phosphate dehydrogenase increased significantly, 40% at 1 and 24 h and 84% at 48 h and that of glutathione S-transferases was 60%. Lipid peroxidn. (estd. by the thiobarbituric acid test) and total protein content increased 3-fold and 2-fold, at 1 and 24 h, resp. Total and oxidized glutathione contents were significantly elevated, 38% at 1 h and 64% at 24 h for the former and 45% at 24 h and 56% at 48 h for the latter. Because these changes are consistent with the cellular response to oxidative stress, it is concluded that BCS injected s.c. can cause changes in the lung possibly via a free radical-mediated mechanism.

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Effects of liquid environments on zirconia-toughened alumina. Part I. Chemical stability. Thompson, I.; Rawlings, R. D. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1992), 27(10), 2823-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:32321 AN 1992:432321 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The structural changes which occur in zirconia-toughened alumina when aged in a range of liq. environments (distd. water, ethylene glycol soln., and HCl at room temp., and ethylene glycol soln. at 80) are described. The changes were monitored by x-ray diffraction, surface anal., anal. of the aging solns., and microstructural observations. HCl induced significant proportions of the zirconia particles in the zirconia-toughened alumina to transform from the tetragonal to the monoclinic crystal structure. This transformation was accompanied by microcracking which eventually led to macrocracking after long periods of aging. The transformation is a consequence of the leaching of the yttrium from the zirconia particles, thereby reducing their stability.

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Binder chemistry, adhesion and structure of interfaces in thick-film metalized aluminum nitride substrates. Newberg, C. E.; Risbud, S. H. IBM Corp., East Fishkill, NY, USA. Journal of Materials Science (1992), 27(10), 2670-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:13161 AN 1992:413161 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Aluminum nitride substrates from 3 sources were metalized by std. thick-film processing using gold conductor pastes, Pd-Ag paste, and a ruthenium oxide resistor paste. Screen-printed pastes were fired in a typical 3-zone furnace to obtain metalized AlN substrates. Interfacial reaction zones were studied by microscopic (optical and SEM) and electron beam microprobe anal. techniques. The elements in the binder materials in thick-film pastes form amorphous phases at the interface which influence the adhesion of thick films to the AlN substrate. The lack of certain elements (Cd, Zn, Ca) in the binder of the gold thick-film paste led to weaker adhesion and severe degrdn. of the thick-film adhesion during thermal cycling.

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Preparation and characterization of a dispersion toughened ceramic for thermomechanical uses (ZTA). Part I. Material preparation. Characterization of microstructure. Leriche, A.; Moortgat, G.; Cambier, F.; Homerin, P.; Thevenot, F.; Orange, G.; Fantozzi, G. CRIBC, Mons, Belg. Journal of the European Ceramic Society (1992), 9(3), 169-76. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:13037 AN 1992:413037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Zirconia-toughened alumina (ZTA) materials contg. increasing amts. of zirconia (5-45 vol.%) and yttria (0-3 mol% zirconia) were prepd. from com. ceramic powders by different techniques of homogenization, shaping, and sintering. The powder mixts. were homogenized by a chem. method (addn. of dispersing agents at fixed pH), by a mech. method (attrition milling) and by combining the methods. The materials were formed and sintered by shaping by isostatic pressing or slip casting, followed by pressureless sintering, and by hot uniaxial pressing. The phys., crystallog. and microstructural properties of the materials prepd. following these different techniques are compared. The combined chem. and mech. dispersion method leads to the fabrication of dense composites presenting a fine and homogeneous zirconia dispersion required for effective toughening of the alumina matrix. The addn. of 3 mol% of yttria allows maintenance of a high tetragonal zirconia content because of a chem. stabilization of tetragonal zirconia and of a decrease of zirconia grain size. As the hot-pressing technique impedes the grain coarsening, the hot-pressed materials present the finest microstructure mainly for the compns. with <20 vol.% zirconia. The zirconia and alumina grain size vary from 0.5 to 0.9 m and from 0.9 to 1.6 m, resp., following the compn. Pressureless sintered materials also present a fine microstructure with submicron zirconia grains (0.6 m-0.9 m) and micron size alumina grains (1.0-1.9 m). These ZTA materials present all the microstructural characteristics necessary to obtain high mech. performances. The addn. of 3 mol% of yttria allows an increase of the zirconia content (45 vol.%) without a decrease of the relative tetragonal zirconia ratio occurring.

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Adsorption and decomposition of organophosphorus compounds on nanoscale metal oxide particles. In situ GC-MS studies of pulsed microreactions over magnesium oxide. Li, Yong Xi; Koper, Olga; Atteya, Maher; Klabunde, Kenneth J. Dep. Chem., Kansas State Univ., Manhattan, KS, USA. Chemistry of Materials (1992), 4(2), 323-30. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 116:200414 AN 1992:200414 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Using an in-situ pulse reactor-GC-mass spectrometric system, the thermal decompn. of organophosphorus compds. (as models of nerve agents) were compared with their destructive absorption on high-surface-area MgO. Dramatically lower temps. are required when MgO is present. Volatile products evolved were HCO2H, water, alcs., and alkenes. At higher temps., CO, CH4, and water predominated. The P residues remained completely immobilized. The addn. of water enhanced the facility of MgO to destroy these compds., and, in fact, water pulses were found to partially regenerate a spent MgO bed. Using 18O labeling, some aspects of the reaction mechanisms were clarified and in particular showed that O scrambling occurred. Surface OH and MgO groups transferred O in the formation of HCO2H, and the surface mobility and reactivity of absorbed groups were high. The substantial capacity of high-surface-area MgO for destruction and immobilization of such toxic substances makes it attractive for air purifn. schemes, as well as solid reagents for destruction and immobilization of bulk quantities of hazardous P compds. or organohalides.

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-(N,N-Dialkylamino)ethyl arylthiosulfonates: new simulants for O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate. Davis, Franklin A.; Ray, Jayanta K.; Kasperowicz, Steve; Przeslawski, Robert M.; Durst, H. Dupont. Dep. Chem., Drexel Univ., Philadelphia, PA, USA. Journal of Organic Chemistry (1992), 57(9), 2594-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 116:193819 AN 1992:193819 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Certain S-[2-(dialkylamino)]ethyl benzenesulfonothioates 4-XC6H4SO2SCH2CH2NR2 (I; X = Me, F; R = Me2CH) were prepd. as simulants for O-Et S-[(diisopropylamino)ethyl]methylphosphonothioate (VX) a chem. warfare nerve agent. I are useful simulants for the hydrolysis or oxidn. chem. of VX.

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Dissolution of sintered silicon nitride bulk specimens for elemental analysis. Homeier, E. H.; Bradley, S. A.; Karasek, K. R. UOP, Des Plaines, IL, USA. Journal of Materials Science (1992), 27(5), 1231-4. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:179524 AN 1992:179524 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Heating bulk, sintered Si3N4 samples in an aq. HF-HCl mixt. decomps. the Si3N4. Subsequent addn. of H2SO4 and volatilization of fluorides enables total dissoln. of the bulk specimens for anal. The elemental compns. that were detd. by inductively coupled plasma at. emission and at. absorption spectrometries agreed with the nominal sample compn. and confirmed analyses performed by scanning TEM. Neutron activation detns. on the same samples are not believed to be as accurate as the spectrometric detns. Furthermore, the precision of the neutron activation measurements were less satisfactory, esp. for key elements such as Y.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy, Paul M.; Hansen, Arnold S.; Hand, Brian T.; Boulet, Camille A. Def. Res. Establ. Suffield, Ralston, AB, Can. Toxicology (1992), 72(1), 99-105. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 116:168061 AN 1992:168061 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a std. set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI 6 > HLoe 7 > pyrimidoxine. Hloe 7 was very effective against tabun poisoning while HI 6 and pyrimidoxime were of moderate value. Against GF, HI 6 and HLoe 7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLoe-7 to a slightly lesser degree. The other oximes lacked the effects against one or more of the organophosphates.

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Chemical vapor deposition of copper via disproportionation of hexafluoroacetylacetonato(1,5-cyclooctadiene)copper(I), (hfac)Cu(1,5-COD). Jain, A.; Chi, K. M.; Hampden-Smith, M. J.; Kodas, T. T.; Farr, J. D.; Paffett, M. F. Dep. Chem. Eng., Univ. New Mexico, Albuquerque, NM, USA. Journal of Materials Research (1992), 7(2), 261-4. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 116:111299 AN 1992:111299 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hot- and cold-wall chem.-vapor deposition (CVD) using the volatile Cu(I) compd. (hfac)Cu(1,5-COD), where hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate and 1,5-COD = 1,5-cyclooctadiene, as a precursor was carried out in hot-wall and warm-wall, lamp-heated reactors using SiO2 substrates that were patterned with Pt or W at 120-250. Deposition was obsd. onto Pt, W, and SiO2 over this temp. range at rates of 3750 .ANG./min to give Cu films that contained no impurities detectable by AES and with resistivities of 1.9-5.7 ohm-cm. The volatile byproducts formed during deposition were 1,5-COD and Cu(hfac)2 and a mass balance was consistent with the quant. disproportionation reaction: 2(hfac)Cu(1,5-COD)  Cu + Cu(hfac)2 + 2(1,5-COD). The measured activation energy for this CVD reaction was 26(2) kcal/mol. The absence of selectivity for metal surfaces in the presence of SiO2 is in contrast to CVD results for the related compds. (-diketonate)Cu(PMe3) where -diketonate = hfac, 1,1,1-trifluoroacetylacetonate, and acetylacetonate (acac).

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer, Thomas W.; Weiss, M. Tracy; D'Agostino, Paul A.; Provost, Lionel R.; Hancock, James R. Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Journal of Applied Toxicology (1992), 12(1), 1-6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 116:105057 AN 1992:105057 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chem. warfare activity was subjected to chem. anal. and bioassay. Sarin and several related compds. were confirmed in the soil by capillary column gas chromatog.-mass spectrometry (GC-MS); however, the binding of these compds. to the soil hindered quantitation. The chem. results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified stds. in chick embryo neuron cultures, a reasonable agreement was found between the chem. and bioassay semiquant. ests. of sarin content in the soil ext. Furthermore, the in-vitro system appears to offer a sensitive technique for the estn. of sarin remaining bound to the soil following solvent extn. as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Pharmacological effects of oximes: how relevant are they?. van Helden H P; Busker R W; Melchers B P; Bruijnzeel P L Department of Pharmacology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1996), 70(12), 779-86. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 8911635 AN 97068325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The increased international concern about the threat of military and terroristic use of nerve agents, prompted us to critically consider the expected value of the currently available oxime treatment of nerve agent poisoning. Although oximes have been designed to reactivate the inhibited acetylcholinesterase (AChE), clinical experience has indicated that they are not always very effective as reactivators and at this very moment none of them can be regarded as a broad-spectrum antidote. In spite of this drawback, oximes are worth further investigating, since recent data derived from soman or tabun lethally intoxicated non-human primates suggest that the oxime HI-6 may exert a pharmacological effect that is not related to reactivation of inhibited AChE, but still leads to survival. This pharmacological effect causes recovery of neuronal transmission in the respiratory centres of the brain and recovery of neuromuscular transmission in the diaphragm. These findings have stimulated research to reveal the pharmacological basis of these effects in order to find drugs which could be more effective and less toxic than the available oximes. Since cholinergic drugs were able to exert this effect, a new concept for further treatment is suggested: maintenance of neuronal transmission in spite of continued AChE-inhibition by pharmacological manipulation of the cholinergic receptor. This should renew interest in the diverse pharmacological effects of oximes to reach a more effective treatment in the future.

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Evaluation of the therapeutic efficacy of some antimuscarinics against soman in vivo. Lau W M; Lewis K J; Dawson R M Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organization, Department of Defence, Melbourne, Victoria, Australia Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 423-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889794 AN 97044723 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The therapeutic efficacy of tacrine, atropine and glycopyrrolate alone or in combination with the oxime HI-6 against soman was evaluated in anaesthetized rats. Arterial blood pressure, heart rate, respiratory frequency and body temperature were monitored in vivo. Blood cholinesterases were determined after each drug or soman challenge. At the lowest concentration tested (2.5 mg kg-1), tacrine was effective in improving the survivability of the rat by a factor of 2.6 (protection ratio), whereas the protection by atropine or glycopyrrolate was either insignificant or only marginally effective (protection ratio ranged from 1.0 to 1.9). In combination with HI-6, atropine increased the ratio to 4.6. In contrast, tacrine with HI-6 failed to improve the efficacy of the regimen, while glycopyrrolate plus HI-6 showed only slight improvement. The four physiological parameters monitored were relatively constant during the time course of the experiment in both the control and those with drug therapy. The more noticeable changes occurred toward the end of the experiment when sufficient amount of soman was injected to cause lethality. Death of the animal was usually preceded by a surge of arterial blood pressure and heart rate and a decrease in respiratory frequency. These physiological parameters rapidly deteriorated to zero just before the animal died. Blood and plasma cholinesterases were significantly inhibited after the animal received a relatively small dose of soman (20 micrograms kg-1) and were almost completely inactivated after the lethal dose of soman was administered. However, these changes of enzyme activity did not correspond well with the survivability of the rat. The inclusion of HI-6 with the three antimuscarinics appeared to be capable of protecting some cholinesterases against soman.

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Efficacy of ibuprofen and pentoxifylline in the treatment of phosgene-induced acute lung injury. Sciuto A M; Stotts R R; Hurt H H Pathophysiology Division, United States Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 381-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889788 AN 97044717 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Phosgene, a highly reactive former warfare gas, is a deep lung irritant which produces adult respiratory distress syndrome (ARDS)-like symptoms following inhalation. Death caused by phosgene involves a latent, 6-24-h, fulminating non-cardiogenic pulmonary edema. The following dose-ranging study was designed to determine the efficacy of a non-steroidal anti-inflammatory drug, ibuprofen (IBU), and a methylxanthine, pentoxifylline (PTX). These drugs were tested singly and in combination to treat phosgene-induced acute lung injury in rats. Ibuprofen, in concentrations of 15-300 mg kg-1 (i.p.), was administered to rats 30 min before and 1 h after the start of whole-body exposure to phosgene (80 mg m-3 for 20 min). Pentoxifylline, 10-120 mg kg-1 (i.p.), was first administered 15 min prior to phosgene exposure and twice more at 45 and 105 min after the start of exposure. Five hours after phosgene inhalation, rats were euthanized, the lungs were removed and wet weight values were determined gravimetrically. Ibuprofen administered alone significantly decreased lung wet weight to body weight ratios compared with controls (P < or = 0.01) whereas PTX, at all doses tested alone, did not. In addition, the decrease in lung wet weight to body weight ratio observed with IBU+PTX could be attributed entirely to the dose of IBU employed. This is the first study to show that pre- and post-treatment with IBU can significantly reduce lung edema in rats exposed to phosgene.

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Subchronic toxicity evaluation of sulfur mustard in rats. Sasser L B; Miller R A; Kalkwarf D R; Cushing J A; Dacre J C Pacific Northwest Laboratory, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1996 Jan-Feb), 16(1), 5-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8821670 AN 96418885 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

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Acute toxicity of cyclohexylmethylphosphonofluoridate (CMPF) in rhesus monkeys: serum biochemical and hematologic changes. Young G D; Koplovitz I U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Archives of toxicology (1995), 69(6), 379-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7495375 AN 96114840 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Changes in serum biochemical and hematological parameters were studied in 20 male rhesus monkeys following acute poisoning by the organophosphate nerve agent cyclohexylmethylphosphonofluoridate (CMPF or GF). Animals were challenged with 5 x LD50 GF (233 micrograms/kg, IM) following pretreatment with pyridostigmine (0.3-0.7 mg/kg per 24 h) and treated with atropine (0.4 mg/kg, IM) and either 2-PAM (25.7 mg/kg, IM) or H16 (37.8 mg/kg, IM) at the onset of clinical signs or at 1 min after exposure. Muscle fasciculations, tremors, or convulsions occurred in 19 of 20 animals. Serum biochemical and hematologic parameters were analyzed 2 days and 7 days after exposure and compared to pre-exposure baseline values. Significant increases in creatine kinase (CK), lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase (ALT) and potassium ion (K+), associated with damage to striated muscle and metabolic acidosis, occurred in both oxime-treated groups 2 days after exposure. Total protein, albumin, red blood cell (RBC) count, hemoglobin concentration (Hb) and hematocrit (Hct), were decreased in both oxime-treated groups at 7 days. The results demonstrate that animals exposed to a single high dose of GF and treated with standard therapy exhibit changes in serum biochemical and hematological indices directly and indirectly associated with their clinical presentations.

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Production, characterization and application of monoclonal antibodies against the organophosphorus nerve agent Vx. Ci Y X; Zhou Y X; Guo Z Q; Rong K T; Chang W B Department of Chemistry, Peking University, Beijing, China Archives of toxicology (1995), 69(8), 565-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8534201 AN 96036122 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Two monoclonal antibodies (Vx-BB8 and Vx-EA11) to the chemical warfare agent Vx were produced and characterized. A competitive inhibition enzyme immunoassay was developed to detect Vx concentrations as low as 3.7 x 10(-7) - 3.7 x 10(-6) mol/l in biological samples. Vx-BB8 400 micrograms given intravenously immediately before 1 x LD95 Vx or 400 micrograms Vx-BB8 intraperitoneally 1.5 h-3 days before 1 x LD95 Vx could protect all the tested mice from death.

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Toxicity of sulphur mustard in adult rat lung organ culture. Sawyer T W; Wilde P E; Rice P; Weiss M T Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada Toxicology (1995 Jun 26), 100(1-3), 39-49. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7542806 AN 95350771 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of the chemical warfare agent sulphur mustard, (bis-(2-chloroethyl)sulphide, HD), was examined in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concentration (LC50) of HD in these cultures was reproducible, and in the microM range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathological examination of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochemically, and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulphur mustard.

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Toxicity of the combined nerve agents GB/GF in mice: efficacy of atropine and various oximes as antidotes. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Canada Archives of toxicology (1994), 68(1), 64-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166607 AN 94219995 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of a combination of isopropyl methylphosphonofluoridate (sarin; GB) and cyclohexyl methylphosphonofluoridate (GF) and the efficacy of various oxime reactivators in combination with atropine against the combined GB/GF challenge were evaluated in mice. The 24-h s.c. LD50 of the GB/GF combination was 1.15 mumol/kg (1.10-1.21; 95% confidence limits). Mice administered GB/GF displayed typical signs of nerve agent poisoning such as tremors and convulsions, with death most likely due to anoxia subsequent to respiratory arrest. The GB/GF LD50 value was comparable to the s.c. LD50 of 1.35 and 1.21 mumol/kg for GF and GB in mice, respectively. Combining the two nerve agents did not result in potentiation of the toxicity. In combination with atropine sulfate (17.4 mg/kg, i.p.), which alone did not reduce mortality, the oximes tested, 2-PAM, obidoxime and HI-6, were all effective when administered 5 min before 3 x LD50 dose of GB/GF with 24-h ED50 values of 102.5, 18.22 and 1.96 mumol/kg, respectively. Use of the GB/GF combination does not appear to confer any unique toxicity profile and appears to be easily treated with the standard therapy of a cholinolytic and oxime.

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Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs. Due A H; Trap H C; Langenberg J P; Benschop H P TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1994), 68(1), 60-3. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166606 AN 94219994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson B W; Kawakami T G; Cone N; Henderson J D; Rosenblatt L S; Goldman M; Dacre J C Department of Avian Sciences, University of California, Davis 95616-5224 Toxicology (1994 Jan 26), 86(1-2), 1-12. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8134917 AN 94182225 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (Tabun, phosphoramidocyanidic acid, dimethyl-, ethyl ester) as part of a program to demilitarize chemical warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only three of the five assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Evaluation of the toxicity, pathology, and treatment of cyclohexylmethylphosphonofluoridate (CMPF) poisoning in rhesus monkeys. Koplovitz I; Gresham V C; Dochterman L W; Kaminskis A; Stewart J R US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425 Archives of toxicology (1992), 66(9), 622-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1482284 AN 93129117 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (CMPF) is an organophosphate cholinesterase inhibitor with military significance. The purpose of these studies was 1) to determine the acute toxicity of CMPF in the male rhesus monkey, 2) to evaluate the efficacy of pyridostigmine (PYR) pretreatment plus atropine and oxime (2-PAM or H16) treatment, and 3) to evaluate the pathological consequences of acute poisoning. An i.m. LD50 of CMPF was estimated using an up-and-down dose selection procedure and 12 animals. The 48-h and 7-day LD50 was 46.6 micrograms/kg, i.m. In the protection experiments, pyridostigmine (0.3-0.7 mg/kg/24 h) was administered by surgically implanted osmotic minipumps for 3-12 days resulting in 21-65% inhibition of erythrocyte acetylcholinesterase activity. Animals were challenged with 5 x L50 CMPF (233 micrograms/kg) and treated with atropine (0.4 mg/kg) and either 2-PAM (25.7 mg/kg) or HI6 (37.8 mg/kg) at the onset of signs or 1 min after challenge. Osmotic pumps were removed within 30 min after agent challenge. Pyridostigmine, atropine, and either 2-PAM or H16 were completely effective against CMPF, saving ten of ten animals in each group. In comparison, three of five animals challenged with 5 x LD50 of soman and treated with atropine and 2-PAM survived 7 days. The primary histologic lesions in the acute toxicity group were neuronal degeneration/necrosis and spinal cord hemorrhage. The CMPF treated groups (total of 20 animals) had minimal nervous system changes with no significant lesion difference resulting from the different oxime therapies. The primary non-neural lesions were degenerative cardiomyopathy and skeletal muscle degeneration which occasionally progressed to necrosis and mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)

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Efficacy of various oximes against GF (cyclohexyl methylphosphonofluoridate) poisoning in mice. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Alta., Canada Archives of toxicology (1992), 66(2), 143-4. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1605730 AN 92296882 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The efficacy of oxime (HI-6, toxogonin or PAM Cl) therapy against GF (cyclohexyl methylphosphonofluoridate) poisoning was assessed in mice. It was found that the combinations of atropine and either toxogonin or HI-6 were effective therapies against GF poisoning. PAM therapy was ineffective. HI-6 was the only oxime which reactivated GF inhibited acetylcholinesterase. This might explain the reason why the HI-6 treated mice appeared to recover more quickly from the incapacitating effects following GF poisoning.

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer T W; Weiss M T; D'Agostino P A; Provost L R; Hancock J R Defence Research Establishment Suffield, Alberta, Canada Journal of applied toxicology : JAT (1992 Feb), 12(1), 1-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1564246 AN 92226402 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chemical warfare activity was subjected to chemical analysis and bioassay. Sarin and several related compounds were confirmed in the soil by capillary column gas chromatography-mass spectrometry (GC-MS); however, the binding of these compounds to the soil hindered quantitation. The chemical results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified standards in chick embryo neuron cultures, a reasonable agreement was found between the chemical and bioassay semi-quantitative estimates of sarin content in the soil extract. Furthermore, the in vitro system appears to offer a sensitive technique for the estimation of sarin remaining bound to the soil following solvent extraction as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy P M; Hansen A S; Hand B T; Boulet C A Defence Research Establishment Suffield, Ralston, Alberta, Canada Toxicology (1992), 72(1), 99-105. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1539175 AN 92169690 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a standard set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI-6 greater than HLo-7 greater than pyrimidoxime. HLo-7 was very effective against tabun poisoning while HI-6 and pyrimidoxime were of moderate value. Against GF, HI-6 and HLo-7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLo-7 to a slightly lesser degree. The other oximes suffered from their lack of effects against one or more of the organophosphates.

[megalomania]

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Aluminum nitride defect chemistry dependence on sintering atmosphere. Chang, E. K.; Kirschner, M. J. BOC Group Technical Cent., Murray Hill, NJ, USA. Journal of Materials Science Letters (1996), 15(18), 1580-1581. CODEN: JMSLD5 ISSN: 0261-8028. Journal; General Review written in English. CAN 125:282600 AN 1996:614771 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 12 refs., of equations explaining theor. relations between aluminum nitride defect chem. and sintering atm.

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Microstructure, chemical reaction and mechanical properties of TiC/Si3N4 and TiN-coated TiC/Si3N4 composites. Huang, Jow-Lay; Lee, Ming-Tung; Lu, Horng-Hwa; Lii, Ding-Fwu. Dep. Material Science Eng., National Cheng-Kung Univ., Tainan, Taiwan. Journal of Materials Science (1996), 31(18), 4899-4906. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:254919 AN 1996:610489 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Silicon nitride contg. various compns. of as-received TiC and TiN-coated TiC, were hot pressed at 1800 C for 1 h in a nitrogen atm. In TiN-coated TiC/Si3N4 composites, TiC reacted first with the TiN coating to form a titanium carbonitride interlayer at 1450 C, which essentially reduced further reactions between TiC and Si3N4 and enhanced densification. TiN-coated TiC/Si3N4 composites exhibited better densification, hardness, flexural strength and fracture toughness than those of as-received TiC/Si3N4. The toughening mechanisms for as-received TiC/Si3N4 and TiN-coated TiC/Si3N4 composite were attributed to crack deflection, load transfer and crack interference by the compressive thermal residual stress.

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Wet chemical synthesis of ZrO2-SiO2 composite powders. Wang, Shi-Wei; Huang, Xiao-Xian; Guo, Jing-Kun. Shanghai Inst. Ceramics, Chinese Academy Sciences, Shanghai, Peop. Rep. China. Journal of the European Ceramic Society (1996), 16(10), 1057-1061. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 125:254896 AN 1996:596753 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of compn. xZrO2(I-x)SiO2, with x = 10, 20, 30 and 40 vol.%, have been prepd. by a wet chem. method using fumed silica and zirconyl chloride as precursors. Thermogravimetric anal. and differential thermal anal. (DTA) show that wt. loss is caused by release of the absorbed water and decompn. of the Zr(OH)4 gels. Gels were heat-treated for 2 h at 500, 700, 900, 1100 and 1350C, and the products examd. using IR spectroscopy. The increasing intensity of the peak at 800 cm-1 in the IR spectra with increasing temp. is attributed to the formation of Si-O-Si bonds among different SiO2 particles, which means that the SiO2 particles grow bigger with increasing temp. The DTA exothermic peak as well as the IR results reveal that the crystn. of tetragonal zirconia (t-ZrO2) begins at about 900C, which is confirmed by x-ray diffraction (XRD). XRD curves also suggest that the silica matrix contributes to the thermal stability of t-ZrO2. The stability of t-ZrO2 is interpreted by the particle-size effect.

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Structure-property relationship of ceramic coatings produced by laser processing. De Hosson, J. Th. M.; Zhou, X. B. Dep. Applied Physics, Univ. Groningen, Groningen, Neth. Materials Research Society Symposium Proceedings (1996), 397(Advanced Laser Processing of Materials--Fundamentals and Applications), 537-542. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:306847 AN 1996:579019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper deals with a well known puzzling observation that wetting in some instances is improved by a chem. reaction between a liq. and a solid substrate in laser processing while in other systems just the opposite effect takes place. Contact angles of liq. Al on SiO2 and liq. Ti on Al2O3 are reported and some results of laser melt injection of SiO2 particles into molten Al. The surface and interface structures were explored by SEM and energy dispersive x-ray spectrometry. According to the exptl. observations, it appears that the vol. change of ceramic substrates during reaction plays a key role in the effect of chem. reaction on wetting.

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Mechanical and thermal properties of SiC-SiC composites made with CVR SiC fibers. Kowbel, W.; Tsou, H. T.; Bruce, C. A.; Withers, J. C. MER Corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1996), 410(Covalent Ceramics III--Science and Technology of Non-Oxides), 417-422. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:202665 AN 1996:502987 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temps. up to 1600C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addn., enhancement of the composite through-the-thickness thermal cond. was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.

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The influence of surface kinetics in modeling chemical vapor deposition processes in porous preforms. Dekker, J. P.; Moene, R.; Schoonman, J. Lab. Appl. Inorg. Chem., Delft Univ. Technol., Delft, Neth. Journal of Materials Science (1996), 31(11), 3021-3033. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65201 AN 1996:378298 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The isothermal chem. vapor infiltration (ICVI) process is a well known technique for the prodn. of composites and the surface modification of porous preforms. Math. modeling of the process can provide a better understanding of the influence of individual process parameters on the deposition characteristics such as final porosity or deposition profiles in the pore network. The influence of different rate expressions for several binary compds. on the ICVI process is discussed. Exptl. work is used to validate the importance of correct kinetic expressions in a continuous ICVI model for cylindrical pores. The predicted infiltration characteristics are compared with exptl. results. The final densification and Thiele modulus, i.e. a no. which is a measure for the diffusion limitations in a pore, are used for the evaluation of the presented model, and conditions are given for an optimal densification of a porous preform by the ICVI process for several binary compds. The deposition profiles as predicted by the model calcns. are in agreement with the exptl. detd. deposition profiles of TiN and TiC in small tubes. Moreover, it can be concluded that the shape of the deposition profiles is detd. by the heterogeneous reaction kinetics. There is only a qual. agreement between the predicted densification and measured densification for the synthesis of TiN and TiB2 in sintered porous alumina. This mismatch can be explained in terms of a complexity of the pore network and differences in reaction kinetics. Model calcns. reveal that there is a scattering for the predicted residual porosity as a function of the Thiele modulus for TiN. Moreover, this Thiele modulus can not fully account for the changes in densification at different temps. Given these uncertainties it is likely that a residual porosity of less than one percent can be obtained if the Thiele modulus is smaller than 1  10-4. However, a CVI process with such a small Thiele modulus will not be practical, because of the concomitant long process times.
Therefore, more precise conditions for the individual process parameters, i.e. concn., reactor pressure, and temp. are deduced from the model calcns.

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Pressure-pulsed chemical vapor infiltration of TiN into SiC particulate preforms. Sugiyama, K.; Sugata, M. Dep. Appl. Chem., Aichi Inst. Technol., Toyota, Japan. Journal of Materials Science (1996), 31(11), 2945-2949. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65198 AN 1996:378286 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC particulate preforms were infiltrated by TiN matrix from a gas mixt. of TiCl4 (5%), nitrogen (30%) and hydrogen using a repeating pressure pulse between 760 and about 1 torr. SiC particle sizes of 5 and 20 m were used. For matrix packing into deep level, optimum temp. was detd. between 800 and 850, and the max. packing ratio reached 67% after 4  104 pulses at 850. The increase of TiCl4 concn. to 10% resulted in higher deposition rate and packing ratio. The decrease of nitrogen concn. led to slower deposition, i.e., a similar effect to temp. lowering. The max. flexural strength measured was 140 MPa.

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Synthesis of mullite coatings by chemical vapor deposition. Mulpuri, Rao P.; Sarin, Vinod K. Dep. Mfg. Eng., Boston Univ., Boston, MA, USA. Journal of Materials Research (1996), 11(6), 1315-1324. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 125:39956 AN 1996:366859 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Formation of mullite on ceramic substrates via chem. vapor deposition was investigated. Mullite is a solid soln. of Al2O3 and SiO2 with a compn. of 3Al2O32SiO2. Thermodn. calcns. performed on the AlCl3-SiCl4-CO2-H2 system were used to construct equil. chem. vapor deposition (CVD) phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were detd. Through process optimization, cryst. CVD mullite coatings have been successfully grown on SiC and Si3N4 substrates. Results from the thermodn. anal., process optimization, and effect of various process parameters on deposition rate and coating morphol. are discussed.

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Mixed chromium and aluminum oxides elaborated by a sol-gel process. I. Chemistry of the preparation. Rezgui, Saloua; Ghorbel, Abdelhamid; Henry, Marc. Lab. Chimie Materiaux Catalyse, Dep. Chimie, Tunisia. Journal of Materials Synthesis and Processing (1995), 3(6), 371-376. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 125:16967 AN 1996:331762 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of mixed chromium and aluminum oxide were prepd. by a sol-gel process. The precursor is a mixt. of Al(O-s-Bu)3 and Cr(acac)3 with a mass ratio Al/Cr = 10 in sec-butanol. Gelation occurred by adding acetic acid. The amt. of added acetic acid is represented by the ratio k = [CH3COOH]/[Al(O-s-Bu)3], with k varying between 0.5 and 3. Acetic acid played crucial roles in both hydrolysis and polycondensation, (1) producing water in situ by esterification, (2) modifying the precursor by substituting some of the O-s-Bu ligands by acetate ligands, and (3) catalyzing the polycondensation. The importance of each of these roles in the process as well as the nature of the products varied with the ratio k.

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Influence of alloying elements on the chemical reactivity between Si-Al-O-N ceramics and iron-based alloys. Vluegels, J.; Vandeperre, L.; Van Der Biest, O. Dep. Metallurgy Materials Eng., Katholieke Univ. Leuven, Leuvan, Belg. Journal of Materials Research (1996), 11(5), 1265-1276. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 124:323490 AN 1996:293140 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. interaction between two '-O' Si-Al-O-N ceramics and a no. of iron-based alloys is studied by means of static interaction couple expts. at 1100 and 1200 C. The onset temp. of reaction of Si3N4 with pure iron was 1095 C, which is in good agreement with a calcd. temp. of 1033 C. During the interaction, silicon and nitrogen from the ceramic dissolve and diffuse into the iron alloy, whereas the remaining aluminum and oxygen form Al2O3 particles. The interaction between the ceramic and iron alloy is reaction controlled. In the initial stage of the interaction, the dissocn. rate of the ceramic is the rate-controlling step. After the ceramic/metal interface is isolated from the furnace atm., the nitrogen soln. rate into the iron alloy becomes rate controlling. The influence of alloying elements on the reactivity could be related to their effect on the nitrogen soly. in the iron alloy. Ni, Si, and C decrease the nitrogen soly. and decrease the reactivity with the Sialon ceramic. Cr and Mo have the opposite effect. The thickness of the interaction layer on the ceramic side of the interaction couple was found to be a function of the calcd. nitrogen soly. in the iron alloy at 1 atm nitrogen pressure, making it possible to predict the relative chem. reactivity of a no. of iron-based alloys with the same Sialon ceramic.

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Preparation and pressureless sintering of chemical vapor deposited SiC-B composite powder. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Institute Materials Research, Tohoku University, Sendai, Japan. Journal of Materials Science (1996), 31(3), 679-83. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 124:239925 AN 1996:180535 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-B composite powder was prepd. by chem. vapor deposition (CVD) using (CH3)2SiCl2 + B2H6 + H2 as source gases at 1673 K. The powder was -type polycryst. silicon carbide contg. several per cents of boron and carbon. The boron content increased from 0 to 7.7 mass% as the B2H6 gas concn. increased from 0 to 0.7 mol%. Boron and carbon in amorphous form dispersed homogeneously in the -SiC polycryst. particles. The particles were spherical, non-agglomerated and uniform in size with an av. particle size of about 50 nm. Sintering tests were performed with the resulting composite powder without applying pressure. Powder contg. 1 mass% boron and 2 mass% carbon was sintered to a d. of 3.16 x 103 kg m-3 at 2273 K, and the Vickers hardness of the sintered body was 30 GPa. When the sintering temp. was higher than 2323 K, significant grain growth due to the phase transformation from  to  form occurred, which decreased bulk d. and Vickers hardness.

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Nanocrystalline metals, intermetallics, and a metal-matrix nanocomposite by solution-based chemical reductions. Buhro, W. E.; Haber, J. A.; Waller, B. E.; Trentler, T. J.; Suryanarayanan, R.; Frey, C. A.; Sastry, S. M. L. Department Chemistry, Washington University, St. Louis, MO, USA. Polymeric Materials Science and Engineering (1995), 73 39-40. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 124:123490 AN 1996:951 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A metal salt soln. was reduced to nanocryst. and nanocomposite. CuCl in THF was reduced with NaBH4 to form nanocrystal Cu, and Ni and Al can also be prepd. in similar manner. NiCl2 soln. was reduced with LiAlH4 ti NiAl intermetallic compds. of nano size. MoCl5 and SiCl4 were reduced with NaK to nanocryst. MoSi2 in ultrasound field. TiB2 nanocryst. particles were suspended in THF and CuCl was reduced to obtain a Cu-coated TiB2 nanocomposite.

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Preparation of low density free-standing shape of SiC by pressure-pulsed chemical vapor infiltration. Sugiyama, K.; Norizuki, K. Dep. Applied Chem., Aichi Inst. Technology, Toyoda, Japan. Journal of Materials Science Letters (1995), 14(23), 1720-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 124:64057 AN 1995:1000853 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of the conditions of pressure-pulsed chem. vapor infiltration (PCVI) on the deposition rate, ease of substrate oxidn., gross d., and flexural strength in prepn. of low-d. free-standing SiC shapes were examd. By selection of a porous carbon substrate, highly porous SiC shapes with a desirable pore distribution may be prepd. by the PCVI process.

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Identification of chemical and physical change during acid cleaning of ceramics. Johnson, Jessica S.; Erickson, Harold M.; Iceland, Harry. Texas Mem. Mus., Univ. Texas, Austin, TX, USA. Materials Research Society Symposium Proceedings (1995), 352(Materials Issues in Art and Archaeology 4), 831-7. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 124:54897 AN 1995:985335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This report describes the results of two expts. characterizing chem. and phys. change in ceramic constituents occurring from acid solns. commonly used to remove deposits from the surface of archaeol. ceramics. The first examines the chem. effects of hydrochloric acid, in an attempt to identify the yellow color, commonly known as "acid burn", often seen in museum collections on black-on-white sherds found in the Southwestern U.S. The compd. is identified as Fe2O3H2O. The second study compares the phys. effects of different acids on a group of Maya sherds. All acids tested in this study were found to cause phys. damage.

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Influence of particle characteristics on sintering behavior of alumina-zirconia composites. Balasubramanian, M.; Malhotra, S. K.; Gokularathnam, C. V. FRP Research Center, Indian Inst. of Technology, Madras, India. Journal of Materials Science Letters (1995), 14(21), 1484-5. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:347792 AN 1995:927403 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A uniform distribution of zirconia particles in an alumina matrix can be achieved by chem. processing methods. Three chem. processing routes were used to obtain better powders. The sintered d. and the tetragonal ZrO2 content of composites were correlated with powder size and morphol.

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Wet air oxidation of energetics and chemical agent surrogates. Copa, William M.; Momont, Joseph A. Zimpro Environmental Inc., Rothschild, WI, USA. Journal of Energetic Materials (1995), 13(3&4), 235-58. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295590 AN 1995:895724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Wet oxidn. studies have been conducted on a no. of energetic materials and wastewaters derived from energetic materials to demonstrate high destruction levels of specific energetic components. Triple-base propellant, OTTO Fuel (used as torpedo propellant) and hydrazine-based rocket fuel were energetics of interest. Triple-base propellant contain nitrocellulose, nitroglycerin, and nitroguanidine. OTTO Fuel contains substantial amts. of propylene glycol trinitrate. Hydrazine based rocket fuel contains hydrazine and 1,1-di-Me hydrazine (asym. di-Me hydrazine or UDMH). A bench scale wet air oxidn. study on alk. hydrolyzates of triple-base propellants indicated that essentially complete destruction of the reactive nitrogen components could be achieved at an oxidn. temp. of 280. Bench scale wet air oxidn. studies on OTTO Fuel wastewaters indicated that a >99% destruction of propylene glycol dinitrate can be achieved at 280. Processing OTTO Fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved even higher destruction levels. Bench scale wet air oxidn. studies on hydrazine-based rocket fuel wastewaters indicated that a 99.8% destruction of hydrazine and a >99.0% destruction of 1,1-dimethylhydrazine can be oxidized at 280. Again, processing of hydrazine-based rocket fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved similar destruction levels. The application of wet air oxidn. for the destruction of chem. agents has been made by the extrapolation of data from the wet air oxidn. of compds. with similar chem. structures or of surrogate compds. Sarin and V-agents are nerve agents which have an organo-phosphorus structure similar to that of contain commonly used pesticides. Pesticides such as glyphosate and malathion, which have a similar organo-phosphorus structure, are essentially completely destroyed (>99% destruction) by wet air oxidn. at 200-280. The chem. agent surrogate, di-Me Me phosphonate (DMMP) was wet air oxidized at 220-280. Alk.
hydrolyzed DMMP was wet air oxidized at 280. All of the oxidized effluents showed a >97.5% destruction efficiency for the DMMP. The blister agent, mustard (HD) is a chlorinated sulfide, bis(2-chloroethyl) sulfide. Org. sulfides such as mercaptans can be destroyed by wet air oxidn. at 260-280. It is concluded that the wet air oxidn. process is a promising alternative to incineration for disposal of energetics and chem. warfare agents.

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Molten salt oxidation of chemical munitions. Stewart, Albert; Schnittgrund, Gary. PyroPacific Processes, Grand Hills, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 213-34. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295589 AN 1995:895723 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molten salt oxidn. is reviewed as a potential near term alternative technol. for the destruction of chem. agents. Initial tests completed by the US Army in 1975 showed the promise of achieving very high removal efficiencies on actual agents. Recent testing by DOE has verified the potential for very low PIC and dioxin or furan releases. To further explore the possible application of this technol. to chem. agent destruction, a molten salt reactor and assocd. equipment was designed to process a nominal 50 kg/h of Sarin. Mass and energy balances are presented for process conditions representing a range of molten salt potential operational modes and schemes for enhancing plant capacity. Process economics are presented.

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Supercritical water oxidation of chemical agents, and solid propellants. Spritzer, M. H.; Hazlebeck, D. A.; Downey, K. W. San Diego, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 185-212. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295588 AN 1995:895722 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Supercrit. water oxidn. (SCWO), also referred to as hydrothermal oxidn. (HTO), is a developing technol. for the destruction of hazardous and nonhazardous wastes. SCWO destroys combustible materials using an oxidant in water at 350-600 and pressures of 17 MPa. General Atomics and its subcontractors are currently conducting 2 comprehensive research and demonstration programs geared toward the destruction of Department of Defense (DoD) wastes utilizing SCWO technol. Wastes of primary interest include chem. agents and solid propellants. Tech. challenges, particularly corrosion and solids handling, were overcome, and the destruction of chem. agents and solid propellants was demonstrated on a bench scale. SCWO results for chem. agents show destruction and removal efficiencies for GB, VX, and mustard agents to be in excess of 99.9999%, limited only by detection capability. SCWO results for hydrolyzed Class 1.1 solid propellant show destruction and removal efficiencies for total org. carbon (TOC) of >99.9%. Design and fabrication of a transportable SCWO pilot plant for chem. warfare agents, propellants and other DoD hazardous wastes and a prototype HTO system for solid rocket propellant disposal are complete and demonstration testing is underway.

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Pressure pulsed chemical vapor infiltration of SiC to two-dimensional-Tyranno/SiC-C preforms. Sygiyama, Kohzo; Yoshida, Yazutoshi. Department of Applied Chemistry, Aichi Institute of Technology, Toyoda, Japan. Journal of Materials Science (1995), 30(20), 5125-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:320390 AN 1995:894944 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preforms of two-dimensional Tyranno fiber (SiC base) of 7  20  1.3 mm3 were chem. vapor infiltrated with SiC at 850-1050C from a gas mixt. of CH3SiCl3 (6%)-H2 using pressure pulses between below 0.3 kPa and 0.1 MPa. Above 900C, films grew on the macrosurface dominantly. At 850C, residual porosity decreased to about 10% after 105 pulses, and three point flexural strength reached about 200 MPa. X-ray diffractograms on the surface showed the deposits to be -SiC only.

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Matrix characterization of fiber-reinforced SiC matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M.; More, K. L.; Sheldon, B. W.; Besmann, T. M.; Headinger, M. H.; Davis, R. F. Oak Ridge National Laboratory, Oak Ridge, TN, USA. Journal of Materials Science (1995), 30(17), 4279-85. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:206673 AN 1995:804167 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ceramic matrix composites (CMCs), that consist of silicon carbide (SiC) reinforced with continuous Nicalon or T-300 fibers, are being developed for many high-temp. structural applications. The large potential use of CMCs has prompted an in-depth investigation and characterization of these materials. Electron microscopy and micro-Raman spectroscopy were used to characterize and compare the SiC matrix crystal structure and morphol. of composite materials fabricated by two different chem. vapor infiltration (CVI) processes.

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Characterization of pseudo-porous SiC/C coatings on NextelTM 440 and NicalonTM fibers. Khasgiwale, N. R.; Butler, E. P.; Tsakalakos, L.; Hensley, D. A.; Cannon, W. R.; Danforth, S. C.; Gonczy, S. T. Center Ceramic Research, Rutgers University, Piscataway, NJ, USA. Materials Research Society Symposium Proceedings (1995), 365 395-400. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177329 AN 1995:774261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Pseudo-porous SiC/C coatings were deposited on NextelTM 440 and NicalonTM fibers by CVD. The morphol. and chem. of the coatings was evaluated, both before and after oxidn., using SEM, X-Ray Diffraction Anal. (XRD), XPS and Auger spectroscopy. Coated fibers were subjected to two different oxidn. treatments to assess coating stability: a) oxidn. at 600C for 20 h, and b) oxidn. at 1000C for 20 h. Pseudo-porous SiC/C on NicalonTM fibers appear to be more oxidn. resistant than the same coatings on NextelTM440 fibers.

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The preparation and economics of silicon carbide matrix composites by chemical vapor infiltration. Roman, Yvette G.; Stinton, David P. Centre Technical Ceramics-TNO, Eindhoven, Neth. Materials Research Society Symposium Proceedings (1995), 365 343-50. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 123:176964 AN 1995:774254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 35 refs. A no. of processing techniques that are currently in use for the development and prodn. of continuous fiber reinforced ceramic composite materials are described. The limited no. of available processing routes are compared with respect to the resulting material properties. The chem. vapor infiltration (CVI) technique is one of the most extensively developed methods. During the last decade, at least five different modifications of the isobaric isothermal CVI principle have been developed; each route having its own benefits. CVI techniques have now been developed to the extent that industrial commercialization is being realized. Projected cost aspects of the various CVI manufg. techniques are examd. and compared.

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Properties of SiC-SiC composites produced using CVR converted graphite cloth to SiC cloth. Kowbel, W.; Kyriacou, C.; Gao, F.; Bruce, C. A.; Withers, J. C. MER corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1995), 365 197-202. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177312 AN 1995:774236 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a new SiC reinforcement based upon a conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. This new SiC filaments exhibit an excellent creep resistance at temps. up to 1600C. Several SiC-SiC composites were fabricated using graphite fabric converted to SiC fabric utilizing the CVR process combined with a slurry infiltration and CVI densification. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites are discussed.

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Chemically bonded ceramic matrix composites: densification and conversion to diffusion bonding. Johnson, Bradley R.; Guelguen, Mehmet A.; Kriven, Waltraud, M. Department Materials Science and Engineering, University Illinois, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1995), 365 67-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177295 AN 1995:774216 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC's). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl2O4) powders were used as the chem. bonding matrix phase, while calcia-stabilized zirconia powders were the second phase material. Samples contg. up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal anal. (DTA/TGA). The phys. characteristics of this novel CMC were characterized by hardness, d., and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD.

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Oxidative catalytic decomposition of toxic gases using hydroxyapatite and fluorhydroxyapatite. Palucka, Timothy P.; Eror, Nicholas G.; McNamara, Thomas A. Department Materials Science and Engineering, University Pittsburgh, Pittsburgh, PA, USA. Materials Research Society Symposium Proceedings (1995), 368(Synthesis and Properties of Advanced Catalytic Materials), 275-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:151604 AN 1995:734790 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An oxidative catalytic route to decomp. nerve gases was studied using hydroxyapatite (HA, Ca10(PO4)6(OH)2) and its partially fluorinated analog fluorhydroxyapatite (FHA, Ca10(PO4)6Fx(OH)2-x). Samples were prepd. with surface areas of 34-238 m2/g to study surface area effects; 1.2 wt.% Pt was deposited on 1 substrate to study the effect of a transition metal on activity and selectivity. Reaction studies were performed using di-Me methylphosphonate, a nerve gas simulant, in a stream of 80% N and 20% O at 573 K and atm. pressure. High surface area FHA samples showed an increase in the protection period (period of 100% conversion) with increasing F substitution; such an increase was not seen for low surface area FHA samples. In the absence of Pt, the reaction products were CH3OH and di-Me ether; with Pt, CO2 was also obtained.

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Toxicity of sulfur mustard in adult rat lung organ culture. Sawyer, Thomas W.; Wilde, Paul E.; Rice, Paul; Weiss, M. Tracy. Medical Countermeasures Section, Defence Research Establishment Suffield, Box 4000, Medicine Hat, Alberta, Can. Toxicology (1995), 100(1-3), 39-49. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 123:104668 AN 1995:700024 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The toxicity of the chem. warfare agent sulfur mustard, (bis-(2-chloroethyl)sulfide, HD), was examd. in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concn. (LC50) of HD in these cultures was reproducible, and in the M range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathol. examn. of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochem., and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulfur mustard.

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Characterization and surface chemistry of uncoated and coated silicon nitride powders. Schmidt, H.; Nabert, G.; Ziegler, G.; Goretzki, H. Inst. Materialforschung, Univ. Bayreuth, Bayreuth, Germany. Journal of the European Ceramic Society (1995), 15(7), 667-74. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 123:90766 AN 1995:695131 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various Si3N4 powders, produced by different procedures, were characterized by imaging (TEM) and anal. methods (EDS, FT-IR, XPS) in the as-received state as well as after doping with a metal oxide (MgO). For the doping, an alternative procedure to the usual methods was applied based on sol. organometallic compds. Anal. TEM combined with lateral resoln. element anal. and XPS measurements was used for morphol., structural and anal. characterization. The distribution of the dopant was deduced from measurements of XPS sputter depth profiles. These investigations were supplemented by FT-IR measurements to det. qual. and semi-quant. the reactive groups on the particle surfaces of the as-received powders. For comparison, measurements were performed with Si3N4 powders which were doped by the above chem. procedure and by mech. mixing. The results of the various characterization methods are interpreted in the form of a model display for surface reactions of organometallic doping reagents on the surfaces of ceramic particles. The results show that Si3N4 powders with high concn. of OH groups on their particle surface reveal very good distribution of the fluxing element (layer-like coating).

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Influence of crystallographic orientation, chemical inhomogeneities, material transport anisotropy and elastic strain energy on the migration of grain boundaries in chromium-doped alumina during internal reduction. Backhaus-Ricoult, Monika; Peyrot-Chabrol, A.; Chiron, R.; Hagege, S. Cent. d'Etudes Chim. Metall., CNRS, Vitry, Fr. Materials Research Society Symposium Proceedings (1995), 357(Structure and Properties of Interfaces in Ceramics), 293-9. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:90732 AN 1995:685875 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Diffusion-induced grain boundary migration is obsd. during internal redn. of chromium-doped alumina. It occurs because grain boundary diffusion is fast compared to lattice diffusion of oxygen. The oxygen chem. potential relaxes between grain boundaries and adjacent grains. Migration to either side of the boundary is controlled by multiple factors: chem. compn. differences between adjacent grains, elastic strain energy differences on the two sides of the boundary plane or by more rapid oxygen relaxation when the c-axis of a grain is perpendicular to the boundary plane.

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Synthesis and chemical stability of NaSn2P3O12. Breval, E.; Harshe, G.; Agrawal, D. K.; Limaye, S. Y. Intercoll. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Journal of Materials Science Letters (1995), 14(10), 728-31. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:39204 AN 1995:606064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

NaSn2P3O12 and NaZr2P3O12 powders were prepd. by solid-state reaction methods and sintered at 1050-1200. The resulting pellets were characterized in terms of d., thermal expansion, and phase compn. before and after chem. stability tests. Chem. stability tests were performed in polethylene containers in 3 solns., H+ + SO42- (pH = 0.5), Na+ + H+ + SO42- (pH = 0.7), and Na+ + OH- (pH + 14.3). Results indicate that NaSn2P3O12 is a very stable NZP compd. in high and low pH solns. (pH + 0.5-14.3) as compared to the parent compn. NaZr2P3O12, which shows high losses, esp. in alk. leachants. The surface-to-vol. of a single phase NaSn2P3O12 material, sintered without sintering agents, hardly affects the dissoln. Use of a sintering agent may result in a highly reactive grain boundary phase, the amt. of which may exceed the amt. of added sintering aid.

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Low-level detection of chemical agent simulants in meat and milk by ion trap mass spectrometry. Buchanan, Michelle V.; Hettich, Robert L.; Xu, Jing Hai; Waters, Larry C.; Watson, Annetta. Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Building 5510, MS/6365, Oak Ridge, TN, USA. Journal of Hazardous Materials (1995), 42(1), 49-59. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 123:31526 AN 1995:596587 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. methods for the detection of two chem. warfare agent simulants, diisopropyl methylphosphonate and chloroethylethylsulfide, in beef tissue and milk were demonstrated to be effective to levels as low as 50-100 ppb. These methods are based upon thermal desorption into an ion trap mass spectrometer. Selective detection of the target compds. is achieved by isobutane chem. ionization in combination with collision-induced dissocn., which yields characteristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limits achieved with this method suggest that it may be possible to take small tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the anal. In addn., because the new methods may be performed more quickly than conventional methods requiring substantial sample prepn. and anal. time, more samples could be analyzed.

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The effect of ceria co-doping on chemical stability and fracture toughness of Y-TZP. Boutz, M. M. R.; Winnubst, A. j. a.; Van Langerak, B.; Scholtenhuis, R. J. M. Olde; Kreuwel, K.; Burggraaf, A. J. Faculty of Chemical Technology, University of Twente, Enschde, Neth. Journal of Materials Science (1995), 30(7), 1854-62. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 122:271892 AN 1995:504770 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and ageing resistance of yttria, ceria-stabilized tetragonal zirconia polycrystals (Y, Ce-TZP) were evaluated as a function of grain size and ceria content. Very fine grained, fully dense materials could be produced by sinter forging at relatively low temps. (1150-1200C). The aging resistance in hot water (185C) of 2 mol% Y2O3-stabilized TZP is strongly enhanced by alloying with ceria. The ceria content necessary to avoid degrdn. completely, decreases with grain size. The toughness of fully dense Y, Ce-TZP is 7-9 MPa m1/2 for grain sizes down to 0.2 m. No or very little transformation took place during fracturing and no clear variation with grain size was obsd. for the toughness at grain sizes up to 0.8 m. Reversible transformation and crack deflection may explain the obsd. toughness values.

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Microstructure and chemistry of second phases in MgO- and NiO-codoped alumina by analytical transmission electron microscopy. Park, K.; Vasilos, T.; Sung, C. Cent. Advanced Materials Dep. Chem. Nuclear Eng., Univ. Massachusetts, Lowell, MA, USA. Journal of Materials Science Letters (1995), 14(4), 261-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 122:167982 AN 1995:415637 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects MgO-NiO-codoping on microstructure and chem. of 2nd phases, segregated particles and cryst. defects in alumina ceramics were examd. MgO-NiO-codoping contributed significantly to the prepn. of dense fine-grained alumina. It appeared that Ni-Al and Ni-Mg-Al spinels, segregated Ni particles, and K-'' alumina ppts. were formed at triple points or at grain boundaries, because the concns. of the MgO and NiO dopants were higher than their solid solubilities. In particular, the codopants formed a Ni-Mg-Al spinel as well as a Ni-Al spinel, because Mg2+ and Ni2+ were partitioned in the cation position of the spinel structure.

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Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry. Bentley, J.; Horton, L. L.; McHargue, C. J.; McKernan, S.; Carter, C. B.; Revcolevschi, A.; Tanaka, S.; Davis, R. F. Metals and Ceramics Div.r., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1994), 332(Determining Nanoscale Physical Properties of Materials by Microscopy and Spectroscopy), 385-90. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:87360 AN 1995:266442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resoln. of <5 nm. Anal. of Fe L23 white lines indicates a low-spin state with a charge transfer of .apprx.1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2-5% in the Co:O stoichiometry were measured across 100-nm-thick Co3O4 layers in an oxidized directionally solidified CoO-ZrO2 eutectic, with the highest O levels near the ZrO2. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for Co3O4 have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid soly. occurred in an AlN-SiC film grown by low-temp. mol. beam epitaxy (MBE) on (6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycryst. AlN on SiC, interfacial 8H Sialon (aluminum silicon oxynitride) and pockets of Si3N4-rich '-Sialon in the SiC were detected.

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Chemically bonded ceramics as an alternative to high temperature composite processing. Gulgun, Mehmet A.; Johnson, Bradley R.; Kriven, Waltraud M. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1994), 346(Better Ceramics through Chemistry VI), 511-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:15230 AN 1995:174876 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Processing of multi-phase ceramic composite materials using chem. bonded ceramics as a binding agent appears to be a promising route for fabricating complex-shaped structures. In a zirconia-calcium aluminate ceramic matrix composite, the hydraulic property of fine, monocalcium aluminate (CaAl2O4) powders was used to prep. strong prefired bodies. The changes in the phys. characteristics of the composite during the conversion from a chem. bonded compact into a sintered composite were studied using thermogravimetric analyses (TGA), X-ray diffraction and SEM. The d. and the hardness of the chem. bonded and sintered composite were measured.

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Assessing delayed neurotoxicity in rodents after nerve gas exposure. Husain, K.; Pant, S. C.; Vijayaraghavan, R.; Singh, Ram. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(2), 161-4. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:294553 AN 1994:694553 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Delayed neurotoxicity of an organophosphorus nerve gas, Sarin (a chem. warfare agent) following repeated inhalation exposure in rats and mice, was studied by behavioral, biochem. and histopathol. analyses. Rats exposed to Sarin aerosols (12.5 mg/m3 for 20 min) daily for ten days did not exhibit any clin. sign of delayed neurotoxicity. Neurotoxic esterase (NTE) activity in the brain, spinal cord and platelets was significantly inhibited, but the inhibition was below the threshold. Histopathol. examn. of spinal cord did not show any axonal degeneration. Mice exposed to Sarin aerosols (5 mg/m3 for 20 min) daily for ten days developed mild ataxia and muscular weakness of the hind limb on 14th day after the start of exposure. NTE activity was significantly inhibited in brain, spinal cord and platelets. Histopathol. of spinal cord showed focal axonal degeneration. Acetyl-choline esterase activity in the platelets of both the animals was significantly inhibited. The authors conclude that mice are sensitive to delayed neurotoxicity induced by repeated exposure to Sarin whereas rats are insensitive.

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Clean-up of chemical warfare agents on soils using simple washing or chemical treatment processes. Amos, Denys; Leake, Brian. DSTO, Aeronautical and Maritime Research Laboratory, P.O. Box 4331, Melbourne, Victoria, Australia. Journal of Hazardous Materials (1994), 39(1), 107-17. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:262645 AN 1994:662645 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several simple processes have been studied for the destruction of chem. agents, Soman and Mustard, on soils. A double wash or an extended single wash with water was effective in removing Mustard and Soman from soil; addn. of either anionic or cationic surfactant did not improve removal efficiency. Soils with higher org. carbon content were more difficult to decontaminate. The most effective chem. process for the removal of Mustard was treatment with hypochlorite; treatment with Na2CO3 or NaOH were almost as effective as hypochlorite in cleaning Mustard contaminated soil. Soman was removed most effectively by treatment with Na2CO3. Overall the most efficient process for the destruction of both Mustard and Soman was treatment with Na2CO3 soln.

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Liquid phase sintering, electrical conductivity, and chemical stability of lanthanum chromite doped with calcium and nickel. Christie, G. M.; Middleton, P. H.; Steele, B. C. H. Dep. Mater., Imperial Coll. Sci., Tech. Med., London, UK. Journal of the European Ceramic Society (1994), 14(2), 163-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:236480 AN 1994:636480 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The substitution of 10 mol% nickel for chromium in calcium-doped lanthanum chromite has been shown to promote rapid densification of the compd. at low temps. in air by the form of a transient liq. phase. Liqs. were generated via the decompn. of CaCrO4 second phase material present in calcined powders. During elec. cond. measurements at 1000C, severe microstructural degrdn. occurred at atms. of H2 and CO2. The processes leading to chem. degrdn. are attributed to the pptn. of Ni from the (La,Ca)(Cr,Ni)O3 solid soln. and to the decompn. of small amts. of residual CaCrO4 which remains at grain boundaries and triple points after sintering. DTA studies on CaCrO4 in CO2 and H2 atms. suggested that the degrdn. due to CaCrO4 decompn. was primarily a result of the reaction of CaO with CO2 to form CaCO3. The presence of H2 gas is thought to catalyze this reaction via the formation of large amt. of CaO during the decompn. of CaCrO4. Degrdn. is more severe in atms. contg. a mixt. of CO2 and H2 gases than in either gas on its own.

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Photochemical degradation of a toxic organophosphorus analog (PMSF) in microemulsion media. Yang, Yun; Donegan, Sheila; Patel, Ramesh C.; Ward, Anthony J. I. Center for Advanced Materials Processing, Clarkson University, Potsdam, NY, USA. Chemosphere (1994), 28(11), 1967-76. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 121:217331 AN 1994:617331 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A study has been made of the photodegrdn. of an analog, phenylmethylsulfonyl fluoride (PMSF), of a toxic chem. warfare agent. The agent was solubilized in a water-in-oil surfactant stabilized microemulsion system comprising sodium dodecyl sulfate, pentanol and water. Loss of the parent PMSF mol. upon exposure of the system to UV irradn. was monitored by 19F NMR spectroscopy. Consideration of the changes in the chem. shifts, splittings in conjunction with GC/Mass spectroscopy data strongly suggest the degrdn. leads to partial fluorination of pentanol. Anal. of peak areas also indicates the formation of volatile degrdn. products such as HF. The addn. of TiO2 or hydroquinone to the system did not appreciably change the overall amts. of degrdn. The results are interpreted in terms of the possible radical based reaction pathways and show that such a microemulsion medium to have significant potential as a vehicle for effecting such a degrdn. process.

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Comparative evaluation of high protein against normal protein diet in combination with carbamates against organophosphorus intoxication in rats. Chatterjee, A.K.; Sikder, Nirmala; Sikder, A.K. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(1), 11-14. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:197892 AN 1994:597892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The relative efficacy of an isocaloric high protein diet (HPD) contg. 59 per cent protein, in comparison to a conventional diet contg. 21 per cent protein, as applied in the alleviation of toxicity of diisopropyl phosphorofluoridate (DFP) and Me iso-Pr phosphonofluoridate (sarin), has been reported. In combination with well-known prophylactics like carbamates and cholinolytics like atropine against nerve gas toxicity, HPD appears to be superior to the conventional diet as studied by survival time measurements. Apart from carbamates, atropine and mecamylamine, HPD may be treated as an addnl. prophylactic agent to guard against the toxicity of DFP and sarin, which are being used as war chems.

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The surface chemistry of silicon nitride powder in the presence of dissolved ions. Hackley, V. A.; Malghan, S. G. Ceram. Div., Natl. Inst. Standards and Technol., Gaithersburg, MD, USA. Journal of Materials Science (1994), 29(17), 4420-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 121:185440 AN 1994:585440 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Colloidal processing of silicon nitride (Si3N4) powders depends largely on the control of reactions at the solid-soln. interface. The role of dissolved ions in the surface chem. of Si3N4 powders has been investigated, and the implications of these results for the effects of impurities, contaminants and additives in processing are discussed. The interaction of ions at the solid-soln. interface was characterized by particle electrokinetic behavior detd. from electroacoustic measurements in moderately concd. suspensions. Ions were classified according to chem. similarity and surface specificity. Specific adsorption was inferred from the movement of the isoelec. point relative to the endemic "native" value. Most simple univalent electrolytes behaved indifferently towards the Si3N4 surface, with the exception of fluoride which specifically adsorbed and may have formed a strong complex with surface silicon sites. The alk.-earth cations exhibited a similar weak specificity. In the presence of hydrolyzable transition metal cations, powder surface chem. was controlled by the adsorption of hydroxy metal complexes and by the soly. of a surface-pptd. metal hydroxide phase. Oxo anions, such as sulfate and carbonate, adsorbed specifically on the Si3N4 surface, but the interactions were weaker than previously obsd. on metal oxide surfaces.

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X-ray photoelectron spectroscopy of uv laser irradiated sapphire and alumina. Pedraza, A. J.; Park, J. W.; Meyer, H. M., III; Braski, D. N. Dep. Materials Science Engineering, Univ. Tennessee, Knoxville, TN, USA. Journal of Materials Research (1994), 9(9), 2251-7. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 121:162453 AN 1994:562453 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

XPS was performed in as-received, thermally annealed, and laser-irradiated sapphire and alumina specimens to study the effects of the different treatments on surface chem. and properties. Laser irradiations with a 308 nm wavelength laser were performed in air and in a reducing atm. consisting of a mixt. of Ar and 4% hydrogen. The at. percentages of carbon, aluminum, and oxygen were measured in all the specimens. Particular attention was paid to the percentages of oxygen in the oxide and in a hydroxyl state. The XPS analyses clearly established that a very thin film of metallic aluminum is formed on the surface of both alumina and sapphire substrates when they are irradiated under a reducing atm. However, the film is discontinuous because it is elec. insulating. Substrates irradiated in air have metallic aluminum only for fluences below 0.4 J/cm2. The valence band photoemission spectra of as-received, annealed, and laser-irradiated specimens were measured. In irradiated specimens, the width of the valence band spectra was found to decrease by .apprx.10%. One possible cause of this decrease is the generation of point defects during laser irradn. Electroless copper deposition occurs on sapphire and alumina substrates if their surface has been activated by laser irradn. The time required for copper deposition was monitored by measuring the elec. resistivity in the irradiated area while the substrates were immersed in an electroless bath. The kinetics of deposition on laser-activated substrates and the XPS results show that the presence of metallic aluminum accelerates the deposition process. However, the presence of aluminum is not the sole reason for laser activation in alumina. Very strong metal-ceramic bonding is produced after thermal annealing of samples having preirradiated substrates. This result is explained in terms of the excess oxygen that is present at the ceramic surface after irradn.

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X-ray absorption spectroscopy study of the local structure and the chemical state of yttrium in polycrystalline -alumina. Loudjani, M. K.; Cortes, R. Lab. Metallurgie Structurale, CNRS, Orsay, Fr. Journal of the European Ceramic Society (1994), 14(1), 67-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:162396 AN 1994:562396 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. state and local structure around the yttrium ion in doped polycryst. -alumina (0.03  mol% Y2O3  1) system was examd. by extended x-ray absorption fine structure (EXAFS) measurements for yttrium K-edge energy. In the case of highly doped alumina samples (0.1 and 1 mol% Y2O3) most of the yttrium is pptd. as a Y3Al5O12 phase, whereas in the dil. doped alumina sample (0.03 mol% Y2O3) yttrium is in solid soln., being located on the octahedral aluminum sites. The yttrium ion size, comparatively greater than that of the aluminum ion, induces locally a significant distortion of the oxygen ion lattice. This effect creates point defects in the nearest neighbor shell of the yttrium: vacancy (Vo..) and interstitial (Oi'') oxygen point defects.

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Constitution of the -alumina phase in chemically produced mullite precursors. Schneider, H.; Voll, D.; Saruhan, B.; Schmucker, M. Inst. Mater. Res., German Aerosp. Res. Establ., Cologne, Germany. Journal of the European Ceramic Society (1993), 13(5), 441-8. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:89568 AN 1994:489568 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The temp. development of type II mullite precursor powders have been studied in the temp. range of 150C (as-received) and 1150C. X-ray diffraction measurements, IR and 29Si and 27Al NMR spectroscopy and anal. transmission electron microscopy have been performed on the heat-treated precursors. The investigations had the aim of contributing to the frequently discussed question, whether Si is incorporated into the -alumina spinel being formed as a transient phase in type II mullite precursors. The as-received precursors consist of relatively large spherical particles ( 05 m) of noncryst. SiO2 and of much finer-grained agglomerates of pseudo-boehmite crystals (-AlO(OH),  20 nm), which are embedded in a SiO2 matrix. Above 350C, pseudo-boehmite transforms to spinel-type alumina (-Al2O3). During this transformation, all Si existing in the SiO2 matrix of the pseudoboehmite agglomerates is incorporated into -Al2O3 corresponding to a SiO2 content of 12 mol% at 500C. Up to 750C, the SiO2 content of the -alumina remains const. but above this temp. it gradually rises and reaches a max. amt. of 18 mol% at 1150C. A marginal decompn. of the spherical non-cryst. SiO2 particles may be the sources to provide diffusion of Si species into the -alumina during a temp. increase above 750C. It is most likely that Si species diffuse into the -alumina crystals along the crystallite boundaries. The diffusion process and Si incorporation are facilitated with the temp. increase.

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Quantitative analysis of Si3N4 microstructure response on interface chemistry. Meissner, E.; Unger, S.; Kleebe, H.-J.; Ziegler, G. Univ. Bayreuth, Bayreuth, Germany. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 471-5. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:89560 AN 1994:489560 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. microstructure anal. was performed on gas-pressure sintered Si3N4 materials (SSN) by employing an image processing system. Variations in grain-diam. distribution and aspect-ratio distribution with changing additive compn. and annealing time, resp., were investigated. Clear evidence was found that both interface compn. and post-sintering anneal can strongly affect the matrix grain morphol. For the Y2O3-doped material, extended annealing time supported the formation of Si3N4 grains with increased diam. and length via Ostwald ripening. Moreover, the aspect-ratio distribution was shifted to higher values indicating anisotropic grain growth. The addn. of Al2O3 + ZrO2, compared to SSN doped with Y2O3, resulted in a finer microstructure with still high aspect ratios. This chem. effect is closely related to the viscosity of the liqs. at processing temps. Furthermore, ZrO2 addn. results in a more pronounced transgranular fracture mode, while Y2O3-contg. SSN predominantly revealed intergranular fracture. The influence of annealing time and interface chem. on both microstructure evolution and resulting fracture toughness is discussed.

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Surface chemical interactions of Si3N4 with polyelectrolyte deflocculants. Hackley, V.A.; Premachandran, R.; Malghan, S.G. Mater. Sci. Eng. Lab., Natl. Inst. Stand. Technol., Gaithersburg, MD, USA. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 679-82. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:41008 AN 1994:441008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interaction of org. polyelectrolyte deflocculants at the Si3N4 solid-soln. interface was investigated using electroacoustic measurements, polymer adsorption and particle size distribution anal. One cationic and two anionic polymers were studied: quaternized poly(diamine epoxychlorohydrin), ammonium poly(methacrylate) and poly(acrylic acid), resp. Electrostatic interactions are emphasized as a function of pH, concn. and mol. wt.

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Metabolite pharmacokinetics of soman, sarin and GF in rats and biological monitoring of exposure to toxic organophosphorus agents. Shih, Ming L.; McMonagle, Joseph D.; Dolzine, Theodore W.; Gresham, Vincent C. US Army Med. Res. Inst. Chem. Def., Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1994), 14(3), 195-9. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 121:28848 AN 1994:428848 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study reports on the pharmacokinetics of the elimination of the metabolites of three toxic organophosphorus compds. (soman, sarin and GF). Urine, blood and lung tissue were collected from rats dosed s.c. at 75 g kg-1. Urinary excretion of the metabolite was the major elimination route for these three compds. The major differences among them were primarily the extent and rate of excretion. The hydrolyzed form, alkylmethylphosphonic acid, was the single major metabolite formed and excreted in urine by a non-saturable mechanism. Nearly total recoveries of the given doses for sarin and GF in metabolite form were obtained from the urine. The terminal elimination half-lives in urine were 3.7  0.1 and 9.9  0.8 h for sarin and GF, resp. Soman metabolite showed a biphasic elimination curve with terminal half-lives of 18.5  2.7 and 3.6  2.2 h. Soman was excreted at a slower rate with a recovery of only 62%. Lung was the major organ of accumulation for soman. In blood the toxic agents were concd. more in red blood cells than in plasma. The acid metabolites can serve as a better chem. marker for monitoring organophosphorus exposure in humans via their higher concn. and longer half-life in urine than the parent compds.

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Movement of chemical warfare agent simulants through porous media. Jenkins, R. A.; Buchanan, M. V.; Merriweather, R.; Ilgner, R. H.; Gayle, T. M.; Watson, A. P. Analytical Chemistry Division, Oak Ridge National Laboratory, Building 4500S, MS-6120, P.O. Box 2008, Oak Ridge, TN, USA. Journal of Hazardous Materials (1994), 37(2), 303-25. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:16666 AN 1994:416666 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A measurement protocol is documented and data are presented to characterize the permeation of chem. warfare agent simulants through the porous construction materials brick, cinder block, gypsum wall board, and wood. These data will be used to develop guidelines for access ("reentry") to potentially contaminated properties if nerve or vesicant agents are released during any phase of the US Department of the Army's Chem. Stockpile Disposal Program. A novel permeation cell design allowed sampling of air vols. adjacent to the spiked face, breakthrough face, and lateral face of each test medium at two temps. Simulant movement through wood is nearly always in the direction of the wood grain. Two-dimensional breakthrough was obsd. in brick and gypsum wall board. The sulfur mustard simulant broke through all test media in less than 60 min; nerve agent simulant breakthrough required several hours. Surface decontamination of wood with high-test hypochlorite is 95% effective.

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Pharmacology of organophosphates. Koelle, George B. Med. Sch., Univ. Pennsylvania, Philadelphia, PA, USA. Journal of Applied Toxicology (1994), 14(2), 105-9. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 121:2654 AN 1994:402654 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 8 refs. The cholinergic nerve fibers, which employ acetylcholine (ACh) as a neurohumoral transmitter, and the results of their activation are listed. The reactions between the enzyme acetylcholinesterase (AChE), its natural substrate, ACh, and the various types of inhibitors are described. The limited therapeutic uses of the anticholinesterase (anti-ChE) agents are considered. The toxicol. effects encountered when the anti-ChE agents are employed as insecticides or as chem. warfare (CW) agents are discussed. Certain anti-ChE agents produce also a delayed neurotoxic effect which is apparently unrelated to the inhibition of AChE.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson, Barry W.; Kawakami, Thomas G.; Cone, Norman; Henderson, John D.; Rosenblatt, Leon S.; Goldman, Marvin; Dacre, Jack C. Inst. Toxicol., Univ. California, Davis, CA, USA. Toxicology (1994), 86(1-2), 1-12. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 120:263586 AN 1994:263586 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (tabun, phosphoramidocyanidic acid, dimethyl-, Et ester) as part of a program to demilitarize chem. warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but not in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only 3 of the 5 assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Effect of chemically added zirconia and yttria mechanical properties of zirconia-dispersed alumina. Ranjbar, Khalil; Rao, Boddapati T.; Mohan, Tallapragada R. Rama; Harendranath, Chilkunda S. Dep. Metall. Eng., Indian Inst. Technol., Bombay, India. American Ceramic Society Bulletin (1994), 73(2), 63-6. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 120:171374 AN 1994:171374 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Alumina powders dispersed with monoclinic, tetragonal, and cubic zirconia were prepd. by evapg. a colloidal dispersion of alumina powders in solns. contg. zirconium and yttrium salts. The dried and calcined powders were compacted, sintered, and characterized. The results demonstrated a clear toughening effect by the zirconia on the alumina ceramics. The alumina contg. 20-wt%-yttria-stabilized tetragonal zirconia had the max. toughness.

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Chemical vapor infiltration of silicon carbide with microwave heating. [Erratum to document cited in CA119(2):13852e]. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(12), 3251. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 120:141948 AN 1994:141948 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The errors were not reflected in the abstr. or the index entries.

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Chemical compatibility between silicon-based and titanium-based ceramics. Wang, L.; Wada, H. Dep. Mater. Sci. Eng., Univ. Michigan, Ann Arbor, MI, USA. Journal of Materials Synthesis and Processing (1993), 1(3), 181-93. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:277176 AN 1993:677176 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. compatibility between Si-based ceramics and Ti-based ceramics was studied to establish guidelines for the processing of related composites. Phase stabilities were calcd. for the Si-Ti-B-C, Si-Ti-B-N, and Si-Ti-B-C-N systems as a function of B activity and N pressure or C activity. SiC is compatible with TiC, TiN, or TiB2, depending on the range of these parameters. Si3N4 and TiN appear to be compatible in a certain range of N2 pressure and C activity, but Si3N4 and pure TiC will not coexist. However, the fact that TiC and TiN can form a solid soln., TiC1-xNx, suggests that Si3N4 and TiC1-xNx may be obsd. in the presence of both C and N2. The Si3N4 + TiB2 2-phase region is limited in such a narrow range of N2 pressure and B activity that processing and application of TiB2/Si3N4 composites would be very difficult. High-temp. solid-state expts. were carried out with selected systems to verify phase stability diagrams. The results of reactions were in agreement with the thermodn. prediction. A high-d. TiB2/SiC composite was prepd. as an example of the application of phase stability diagrams.

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Thermal and acid catalyzed conversion of organic phosphorus compounds. De Lijser, H. J. P.; Mulder, P.; Louw, R. Cent. Chem. Environ., Leiden Univ., Leiden, Neth. Chemosphere (1993), 27(5), 773-8. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:233159 AN 1993:633159 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The org. P compds. tri-Bu and tri-Me phosphate (I and II, resp.), tri-Me phosphite (III), and di-Me phosphonate (IV) were thermolyzed using a plug flow (gas-phase) reactor. I and II proved to be sensitive to acid (wall) catalysis and can be fully degraded at temps. of .mchlt.400. III can isomerize to II and IV. In contrast, IV requires a temp. of >750 for complete conversion; admixed with II it counteracts the smooth acid-mediated degrdn. of II. Unlike real thermolysis at elevated temps., preferably in a reducing atm. of hydrogen, mere acid catalysis is not generally applicable for effectively destroying a variety of ecotoxic org. P compds.

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Preparation of uniformly calcia-doped zirconia. Hill, J.; Newhouse, M.; Xue, J.; Dieckmann, R. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Journal of Materials Synthesis and Processing (1993), 1(2), 101-9. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:232072 AN 1993:632072 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The prepn. of dense samples of high-purity zirconia doped with varying, small contents of CaO has been explored by means of traditional ceramic techniques with sintering and hot-pressing as well as a chem. soln. method. First, CaO-doped samples were prepd. by traditional ceramic methods. Their homogeneities were checked by SEM with x-ray mapping. CaO-dopant distribution was not uniform in all samples with overall CaO contents below 7 mol%. The difficulty in prepg. uniformly doped zirconia with small CaO contents led to exploration of the use of chem. soln. processing techniques. When exploring such techniques, the products of each process step were characterized by x-ray diffraction and electron microprobe anal. The characterization results enabled identification of a processing route which is suitable for prepg. dense, high-purity zirconia uniformly doped with CaO at low concns.

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A model for the isothermal isobaric chemical vapor infiltration (CVI) in a straight cylindrical pore. Application to the CVI of silicon carbide. Fedou, R.; Langlais, F.; Naslain, R. Lab. Compos. Thermostruct., CNRS, Pessac, Fr. Journal of Materials Synthesis and Processing (1993), 1(2), 61-74. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:208796 AN 1993:608796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A previously described modeling of the chem. vapor infiltration (CVI) process in a straight cylindrical pore is applied to the deposition of SiC-based ceramics from MeSiCl3-H2 in the case of a 1st-order kinetic law with respect to MeSiCl3. The model gives concns. and deposit thickness profiles along the pore at any stage of the densification and, particularly, at the end of the process when the pore becomes sealed. The infiltration homogeneity is predicted to be improved by decreasing the aspect ratio of the pore and the CVI temp. and, under conditions of Fick diffusion, by decreasing the total pressure and the pore diam. The model is validated by the good fit between the deposit thickness profiles along the pore calcd. after adjustment of the kinetic data and exptl. profiles for a 34-m straight pore.

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Nicalon-fiber-reinforced silicon carbide composites via polymer solution infiltration and chemical vapor infiltration. Kim, Young Wook; Song, Jin Soo; Park, Sang Whan; Lee, Juen Gunn. Struct. Ceram. Lab., Korea Inst. Sci. Technol., Seoul, S. Korea. Journal of Materials Science (1993), 28(14), 3866-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 119:186895 AN 1993:586895 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A new, faster process was developed for the fabrication of Nicalon-fiber-reinforced SiC composites by combining polymer soln. infiltration (PSI) and chem. vapor infiltration (CVI). The process led to the near-net-shape fabrication of fiber-reinforced ceramic-matrix composites and reduced infiltration time. Typical flexural strength and fracture toughness of these composites were 296 MPa and 10.9 MPa.m1/2 at room temp. and 252 MPa and 9.6 MPa.m1/2 at 1000, resp. The composites exhibited load-carrying capability after crack initiation.

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The effect of glass chemistry on the microstructure and properties of self reinforced silicon nitride. Pyzik, Aleksander J.; Carroll, Daniel F.; Hwang, C. James. Adv. Ceram. Lab., Dow Chem. Co., Midland, MI, USA. Materials Research Society Symposium Proceedings (1993), 287(Silicon Nitride Ceramics), 411-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:186804 AN 1993:586804 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The advantage of self-reinforced silicon nitride is the in-situ control of the microstructure. This control is provided in large degree by the chem. of glassy phase which can be adjusted to tailor the morphol. of silicon nitride grains as well as the matrix-reinforcement interface. The presence of high aspect ratio silicon nitride grains is necessary but not sufficient condition to produce materials with optimum properties. For max. flexure strength and fracture toughness, an optimized glass matrix is required.

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Microwave assisted chemical vapor infiltration. Devlin, D. J.; Currier, R. P.; Barbero, R. S.; Espinoza, B. F.; Elliott, N. Mater. Sci. Technol. Div., Los Alamos Natl. Lab., Los Alamos, NM, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 245-50. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144800 AN 1993:544800 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A microwave-assisted process for prepn. of continuous fiber-reinforced ceramic-matrix composites is described. A simple app. combining a chem.-vapor-infiltration reactor with a conventional 700-W multimode oven is described. Microwave-induced inverted thermal gradients are exploited with the ultimate goal of reducing processing times on complex shapes. Thermal gradients in stacks of SiC (Nicalon) cloths have been measured using optical thermometry. Initial results on the inside-out deposition of SiC via decompn. of MeSiCl3 in H are presented. Several key processing issues are identified and discussed.

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Chemical vapor deposition of multiphase boron-carbon-silicon ceramics. Golda, E. Michael; Gallois, B. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 167-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144796 AN 1993:544796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Specific compns. of boron-carbon-silicon ceramics exhibit improved abrasive wear and good thermal shock resistance, but require bulk sintering at temps. in excess of 2100K. The formation of such phases by CVD was examd. at 1073-1573K. Methyltrichlorosilane (CH3SiCl3), boron trichloride, and methane were chosen as reactant gases, with hydrogen as a carrier gas and diluent. The coatings were deposited in a computer-controlled, hot-wall reactor at a pressure of 33 MPa. Below 1473K the coatings were amorphous. At higher temps. nonequil. reactions controlled the deposition process. The most common coating consisted of a silicon carbide matrix and a silicon boride, SiB6, dispersed phase. Multiphase coatings of B + B4C + SiB6 and SiC + SiB6 + SiB14 were also deposited by controlling the partial pressure of methane and boron trichloride. Non-equil. thermodn. anal. qual. predicted the exptl. deposited multiphase coatings.

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CVD of silicon nitride plate from trichlorosilane-ammonia-hydrogen mixtures. Lennartz, J. W.; Dowell, M. B. Union Carbide Coat. Serv. Corp., Parma, OH, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 161-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144795 AN 1993:544795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preferred conditions for deposition of thick -Si3N4 plate from HSiCl3-NH3-H2 on the vertical surfaces of a low-pressure, hot-wall CVD reactor were identified by means of a designed expt. The design included temp. range 1300-1500, pressures 0.5-2.0 torr, and residence times 0.01-1.0 s. The vertical deposition surfaces received a viscous, laminar flow of well mixed, thermally equilibrated reactants. Plates 0.05-0.5 mm thick were produced on multiple vertical substrates 350 cm2 in area at deposition rates 5-70 m/h. Plates 0.5-4.0 mm thick were produced on horizontal substrates at deposition rates of 60-120 m/h. When NH3 flows in stoichiometric excess, deposition rates on vertical surfaces increase approx. linearly with the flow rate of HSiCl3 but depend little on temp., as would be expected if the reaction proceeds under mass transport control with product depletion. Multiple correlation analyses show that thickness variations in the deposit are reduced by increasing the temp. and decreasing the gas residence time. CVD silicon nitride plate produced under the optimized conditions exhibits theor. d. and is free of pores and cracks. It exhibits a columnar morphol. in which the <222> and <101> crystallog. directions are oriented preferentially normal to a surface, which consists of well-defined trigonal facets 10-50 m across. Crystallite sizes detd. by x-ray line broadening range from 0.06-1.0 m. This CVD plate is gray and contains approx. 0.5 C and 0.5 wt.% 0 as principal impurities.

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Unequivocal evidence. Black, Robin M.; Pearson, Graham S. Chem. Biol. Def. Estab., Porton/Down/Salisbury Wiltshire, UK. Chemistry in Britain (1993), 29(7), 584-5, 587. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 119:123791 AN 1993:523791 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of chem. warfare agent, Sarin, in the Kurdush village of Birjinni, Iraq, was discussed.

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Bioanalysis of organophosphate nerve agents in soil samples. Sawyer, T. W.; Weiss, M. T. Biomed. Def. Sect., Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Chemosphere (1993), 26(11), 2023-9. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:94477 AN 1993:494477 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Four soil samples that may have been spiked with chem. warfare (CW) agents and their degrdn. products were received by Defense Research Establishment Suffield as part of a multinational round-robin exercise designed to evaluate lab. methodologies for the chem. detection of CW agents in soil. After chem. anal. revealed that VX (Et S-2-diisopropyl aminoethyl methylphosphorothiolate) was the CW agent "spike", the samples were also bioassayed for their VX content by assessing their anticholinesterase activities in primary chick embryo neuron cultures. Bioassay quantitation of VX contamination in the soil samples was in good agreement with the actual spike levels and generally better than the chem. anal. results. Sequential bioassay of the samples over a two week period showed that the VX content was rapidly degraded with time. This assay complements std. chem. anal. techniques for the detection and verification of organophosphate warfare agent use.

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The effect of trace element segregation to iron/sapphire interfaces. Pope, D. P.; Smith, M. A. Dep. Mater. Sci., Univ. Pennsylvania, Philadelphia, PA, USA. Materials Research Society Symposium Proceedings (1992), 238(Structure and Properties of Interfaces in Materials), 427-32. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:77041 AN 1993:477041 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of segregation of tramp impurities such as sulfur on metal/ceramic bonding is discussed. Microstructural and chem. information is given for the Fe/sapphire interface. The segregation behavior of the interface is evaluated between 500-800. The interfacial structure is important to the segregation behavior. A possible link between the segregation of sulfur and interface void formation is presented.

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Chemical vapor infiltration of silicon carbide with microwave heating. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(5), 1057-67. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 119:13852 AN 1993:413852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is presented to describe the interaction between transport/reaction processes and the evolution of porosity in chem. vapor infiltration with microwave heating (MCVI). The anal. includes a set of partial differential equations describing the spatiotemporal variation of gaseous species concn., composite temp., porosity, and stress. Maxwell's equations were used to det. the distribution of power dissipated inside the composite. The deposition of silicon carbide was selected as a model chem. system to explore the general features of MCVI. MCVI can provide a favorable temp. distribution in the composite yielding an inside-out deposition pattern, thereby preventing entrapment of accessible porosity. For this temp. profile, tensile stresses develop at the outer regions and compressive stresses are found in the composite core. For a given system there exists a min. value of the coeff. for heat transfer from the composite surface, h, below which accessible porosity is trapped within the composite. Similarly, there exists a max. value of the incident microwave energy flux, I0, above which accessible porosity is trapped within the composite. I0 and h can be optimized for a given preform to achieve complete densification with min. processing time. Using the technique of pulsed-power, the processing time can be reduced even further without compromising d. uniformity. Power dissipation profiles in the composite depend strongly on preform thickness, microwave frequency, and relative loss factor.

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Permeation measurements of chemical agent simulants through protective clothing materials. Pal, Tarasankar; Griffin, Guy D.; Miller, Gordon H.; Watson, Annetta P.; Daugherty, Mary Lou; Vo Dinh Tuan. Health Saf. Res. Dev., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Hazardous Materials (1993), 33(1), 123-41. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 118:239880 AN 1993:239880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A method was developed to study the permeation of chem. warfare (CW) agent simulants through chem. protective clothing (CPC) materials. The exptl. results characterize some com. available CPC materials. Thirteen different CPC materials having widely differing compns. were chosen to study the permeation of 4 different liq. CW simulants (di-Me methylphosphonate, diisopropyl methylphosphonate, malathion, and Bu2S) through these CPC materials at 25. This permeation study involved a newly developed anal. technique employing room temp. fluorescence quenching of an indicator compd., phenanthrene, on filter paper. Various exptl. factors such as breakthrough time, rate of permeation, and uptake were investigated. On the basis of breakthrough time, the 13 CPC materials could be divided into 3 groups: most resistant, moderately resistant, and least resistant. Materials in the most resistant category exhibited no permeation by any of the simulants for 24 h. Breakthrough occurred in the least resistant materials in generally less than an hour, and sometimes as soon as a few minutes.

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Interfacial structure of chemical vapor infiltration carbon fiber/silicon carbide composite. Araki, H.; Noda, T.; Abe, F.; Suzuki, H. Tsukuba Lab., Natl. Res. Inst. Met., Tsukuba, Japan. Journal of Materials Science Letters (1992), 11(23), 1582-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:44089 AN 1993:44089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure at the interface in carbon fiber-SiC matrix composites prepd. by chem. vapor infiltration from EtSiCl3 was examd., and the infiltration reaction is discussed. A graphite layer formed on the carbon fiber and the SiC-SiC interface as a result of thermal decompn. of silane gas before SiC infiltration. This graphite layer, of .apprx.500 nm thickness, is assumed to assist in the crystal growth of SiC, leading to structural stability of the composites.

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Comparative evaluation of carbamates as prophylactic agents against organophosphate intoxication in rats. Chatterjee, A. K. Def. Res. Dev. Establ., Gwalior, UK. Defence Science Journal (1992), 42(2), 85-7. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 118:34070 AN 1993:34070 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper investigates the effects of two well-known carbamates, physostigmine and pyridostigmine, against organophosphorus compd. and nerve gas toxicity. Physostigmine pretreatment for 30 min enhanced the survival time of rats against DFP intoxication, whereas it did not have any effect with sarin poisoning. However, pyridostigmine pretreatment did not produce any significant effect on survival time either against DFP or sarin intoxication. Treatment with atropine along with carbamates further enhanced significantly the survival time against DFP poisoning.

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On the influence of chemical processing in the crystallization behavior of zirconium titanate materials. Navio, J. A.; Macias, M.; Sanchez-Soto, P. J. Inst. Cienc. Mater., Univ. Sevilla, Seville, Spain. Journal of Materials Science Letters (1992), 11(23), 1570-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:26385 AN 1993:26385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The crystn. phenomena of ZrTiO4 powders prepd. from various gel precursors was related to the chem. processing. Correlation of data from the literature and further expt. indicated that the presence of H2O2 in the chem. processing of the amorphous precursors plays a key role in controlling the crystn. temp. The crystn. temp. can be as low as 640.

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Effect of dopants on the sintering behavior and stability of tetragonal zirconia ceramics. Theunissen, G. S. A. M.; Winnubst, A. J. A.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1992), 9(4), 251-63. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:54278 AN 1992:454278 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure development during nonisothermal and isothermal sintering was studied for tetragonal zirconia ceramics (TZP) contg. various amts. of Y, Ce, and Ti. Smaller grain sizes were obtained when Ce-TZP was doped with Y. This could be attributed to segregation of Y to the grain boundaries, thus causing an impurity drag. With increasing temp., the grain growth rate in the Ce-TZP samples increased which could be attributed to the absence of a dragging force. The slow grain growth at low temp. in the Ce-TZP samples could be attributed to the slow diffusion kinetics of the diffusing species (trivalent and tetravalent Ce). The crit. grain size for retainment of the tetragonal phase at room temp. is larger in the Y,Ce-TZP systems compared to the Y-TZP and Ce-TZP systems. The chem. stability increased by doping Y-TZP with Ce or Ti.

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Free radical-mediated lung response to the monofunctional sulfur mustard butyl 2-chloroethyl sulfide after subcutaneous injection. Elsayed, Nabil M.; Omaye, Stanley T.; Klain, George J.; Korte, Don W., Jr. Letterman Army Inst. Res., Presidio of San Francisco, CA, USA. Toxicology (1992), 72(2), 153-65. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 117:42116 AN 1992:442116 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors postulated that vesicants may cause free radical-mediated oxidative stress distal to the site of exposure. To test this postulate in the lung, the authors injected 3 groups of 5-mo-old, male, athymic, nude mice, weighing 30-35 g with a single s.c. dose (5 L/mouse) of Bu 2-chloroethyl sulfide (BCS). Total lung wt. was not altered after treatment, but the wet/dry wt. ratio decreased 18% and Hb content increased 50 and 36% at 1 and 24 h, resp. The activity of glucose 6-phosphate dehydrogenase increased significantly, 40% at 1 and 24 h and 84% at 48 h and that of glutathione S-transferases was 60%. Lipid peroxidn. (estd. by the thiobarbituric acid test) and total protein content increased 3-fold and 2-fold, at 1 and 24 h, resp. Total and oxidized glutathione contents were significantly elevated, 38% at 1 h and 64% at 24 h for the former and 45% at 24 h and 56% at 48 h for the latter. Because these changes are consistent with the cellular response to oxidative stress, it is concluded that BCS injected s.c. can cause changes in the lung possibly via a free radical-mediated mechanism.

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Effects of liquid environments on zirconia-toughened alumina. Part I. Chemical stability. Thompson, I.; Rawlings, R. D. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1992), 27(10), 2823-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:32321 AN 1992:432321 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The structural changes which occur in zirconia-toughened alumina when aged in a range of liq. environments (distd. water, ethylene glycol soln., and HCl at room temp., and ethylene glycol soln. at 80) are described. The changes were monitored by x-ray diffraction, surface anal., anal. of the aging solns., and microstructural observations. HCl induced significant proportions of the zirconia particles in the zirconia-toughened alumina to transform from the tetragonal to the monoclinic crystal structure. This transformation was accompanied by microcracking which eventually led to macrocracking after long periods of aging. The transformation is a consequence of the leaching of the yttrium from the zirconia particles, thereby reducing their stability.

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Binder chemistry, adhesion and structure of interfaces in thick-film metalized aluminum nitride substrates. Newberg, C. E.; Risbud, S. H. IBM Corp., East Fishkill, NY, USA. Journal of Materials Science (1992), 27(10), 2670-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:13161 AN 1992:413161 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Aluminum nitride substrates from 3 sources were metalized by std. thick-film processing using gold conductor pastes, Pd-Ag paste, and a ruthenium oxide resistor paste. Screen-printed pastes were fired in a typical 3-zone furnace to obtain metalized AlN substrates. Interfacial reaction zones were studied by microscopic (optical and SEM) and electron beam microprobe anal. techniques. The elements in the binder materials in thick-film pastes form amorphous phases at the interface which influence the adhesion of thick films to the AlN substrate. The lack of certain elements (Cd, Zn, Ca) in the binder of the gold thick-film paste led to weaker adhesion and severe degrdn. of the thick-film adhesion during thermal cycling.

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Preparation and characterization of a dispersion toughened ceramic for thermomechanical uses (ZTA). Part I. Material preparation. Characterization of microstructure. Leriche, A.; Moortgat, G.; Cambier, F.; Homerin, P.; Thevenot, F.; Orange, G.; Fantozzi, G. CRIBC, Mons, Belg. Journal of the European Ceramic Society (1992), 9(3), 169-76. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:13037 AN 1992:413037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Zirconia-toughened alumina (ZTA) materials contg. increasing amts. of zirconia (5-45 vol.%) and yttria (0-3 mol% zirconia) were prepd. from com. ceramic powders by different techniques of homogenization, shaping, and sintering. The powder mixts. were homogenized by a chem. method (addn. of dispersing agents at fixed pH), by a mech. method (attrition milling) and by combining the methods. The materials were formed and sintered by shaping by isostatic pressing or slip casting, followed by pressureless sintering, and by hot uniaxial pressing. The phys., crystallog. and microstructural properties of the materials prepd. following these different techniques are compared. The combined chem. and mech. dispersion method leads to the fabrication of dense composites presenting a fine and homogeneous zirconia dispersion required for effective toughening of the alumina matrix. The addn. of 3 mol% of yttria allows maintenance of a high tetragonal zirconia content because of a chem. stabilization of tetragonal zirconia and of a decrease of zirconia grain size. As the hot-pressing technique impedes the grain coarsening, the hot-pressed materials present the finest microstructure mainly for the compns. with <20 vol.% zirconia. The zirconia and alumina grain size vary from 0.5 to 0.9 m and from 0.9 to 1.6 m, resp., following the compn. Pressureless sintered materials also present a fine microstructure with submicron zirconia grains (0.6 m-0.9 m) and micron size alumina grains (1.0-1.9 m). These ZTA materials present all the microstructural characteristics necessary to obtain high mech. performances. The addn. of 3 mol% of yttria allows an increase of the zirconia content (45 vol.%) without a decrease of the relative tetragonal zirconia ratio occurring.

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Adsorption and decomposition of organophosphorus compounds on nanoscale metal oxide particles. In situ GC-MS studies of pulsed microreactions over magnesium oxide. Li, Yong Xi; Koper, Olga; Atteya, Maher; Klabunde, Kenneth J. Dep. Chem., Kansas State Univ., Manhattan, KS, USA. Chemistry of Materials (1992), 4(2), 323-30. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 116:200414 AN 1992:200414 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Using an in-situ pulse reactor-GC-mass spectrometric system, the thermal decompn. of organophosphorus compds. (as models of nerve agents) were compared with their destructive absorption on high-surface-area MgO. Dramatically lower temps. are required when MgO is present. Volatile products evolved were HCO2H, water, alcs., and alkenes. At higher temps., CO, CH4, and water predominated. The P residues remained completely immobilized. The addn. of water enhanced the facility of MgO to destroy these compds., and, in fact, water pulses were found to partially regenerate a spent MgO bed. Using 18O labeling, some aspects of the reaction mechanisms were clarified and in particular showed that O scrambling occurred. Surface OH and MgO groups transferred O in the formation of HCO2H, and the surface mobility and reactivity of absorbed groups were high. The substantial capacity of high-surface-area MgO for destruction and immobilization of such toxic substances makes it attractive for air purifn. schemes, as well as solid reagents for destruction and immobilization of bulk quantities of hazardous P compds. or organohalides.

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-(N,N-Dialkylamino)ethyl arylthiosulfonates: new simulants for O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate. Davis, Franklin A.; Ray, Jayanta K.; Kasperowicz, Steve; Przeslawski, Robert M.; Durst, H. Dupont. Dep. Chem., Drexel Univ., Philadelphia, PA, USA. Journal of Organic Chemistry (1992), 57(9), 2594-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 116:193819 AN 1992:193819 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Certain S-[2-(dialkylamino)]ethyl benzenesulfonothioates 4-XC6H4SO2SCH2CH2NR2 (I; X = Me, F; R = Me2CH) were prepd. as simulants for O-Et S-[(diisopropylamino)ethyl]methylphosphonothioate (VX) a chem. warfare nerve agent. I are useful simulants for the hydrolysis or oxidn. chem. of VX.

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Dissolution of sintered silicon nitride bulk specimens for elemental analysis. Homeier, E. H.; Bradley, S. A.; Karasek, K. R. UOP, Des Plaines, IL, USA. Journal of Materials Science (1992), 27(5), 1231-4. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:179524 AN 1992:179524 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Heating bulk, sintered Si3N4 samples in an aq. HF-HCl mixt. decomps. the Si3N4. Subsequent addn. of H2SO4 and volatilization of fluorides enables total dissoln. of the bulk specimens for anal. The elemental compns. that were detd. by inductively coupled plasma at. emission and at. absorption spectrometries agreed with the nominal sample compn. and confirmed analyses performed by scanning TEM. Neutron activation detns. on the same samples are not believed to be as accurate as the spectrometric detns. Furthermore, the precision of the neutron activation measurements were less satisfactory, esp. for key elements such as Y.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy, Paul M.; Hansen, Arnold S.; Hand, Brian T.; Boulet, Camille A. Def. Res. Establ. Suffield, Ralston, AB, Can. Toxicology (1992), 72(1), 99-105. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 116:168061 AN 1992:168061 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a std. set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI 6 > HLoe 7 > pyrimidoxine. Hloe 7 was very effective against tabun poisoning while HI 6 and pyrimidoxime were of moderate value. Against GF, HI 6 and HLoe 7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLoe-7 to a slightly lesser degree. The other oximes lacked the effects against one or more of the organophosphates.

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Chemical vapor deposition of copper via disproportionation of hexafluoroacetylacetonato(1,5-cyclooctadiene)copper(I), (hfac)Cu(1,5-COD). Jain, A.; Chi, K. M.; Hampden-Smith, M. J.; Kodas, T. T.; Farr, J. D.; Paffett, M. F. Dep. Chem. Eng., Univ. New Mexico, Albuquerque, NM, USA. Journal of Materials Research (1992), 7(2), 261-4. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 116:111299 AN 1992:111299 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hot- and cold-wall chem.-vapor deposition (CVD) using the volatile Cu(I) compd. (hfac)Cu(1,5-COD), where hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate and 1,5-COD = 1,5-cyclooctadiene, as a precursor was carried out in hot-wall and warm-wall, lamp-heated reactors using SiO2 substrates that were patterned with Pt or W at 120-250. Deposition was obsd. onto Pt, W, and SiO2 over this temp. range at rates of 3750 .ANG./min to give Cu films that contained no impurities detectable by AES and with resistivities of 1.9-5.7 ohm-cm. The volatile byproducts formed during deposition were 1,5-COD and Cu(hfac)2 and a mass balance was consistent with the quant. disproportionation reaction: 2(hfac)Cu(1,5-COD)  Cu + Cu(hfac)2 + 2(1,5-COD). The measured activation energy for this CVD reaction was 26(2) kcal/mol. The absence of selectivity for metal surfaces in the presence of SiO2 is in contrast to CVD results for the related compds. (-diketonate)Cu(PMe3) where -diketonate = hfac, 1,1,1-trifluoroacetylacetonate, and acetylacetonate (acac).

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer, Thomas W.; Weiss, M. Tracy; D'Agostino, Paul A.; Provost, Lionel R.; Hancock, James R. Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Journal of Applied Toxicology (1992), 12(1), 1-6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 116:105057 AN 1992:105057 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chem. warfare activity was subjected to chem. anal. and bioassay. Sarin and several related compds. were confirmed in the soil by capillary column gas chromatog.-mass spectrometry (GC-MS); however, the binding of these compds. to the soil hindered quantitation. The chem. results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified stds. in chick embryo neuron cultures, a reasonable agreement was found between the chem. and bioassay semiquant. ests. of sarin content in the soil ext. Furthermore, the in-vitro system appears to offer a sensitive technique for the estn. of sarin remaining bound to the soil following solvent extn. as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Pharmacological effects of oximes: how relevant are they?. van Helden H P; Busker R W; Melchers B P; Bruijnzeel P L Department of Pharmacology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1996), 70(12), 779-86. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 8911635 AN 97068325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The increased international concern about the threat of military and terroristic use of nerve agents, prompted us to critically consider the expected value of the currently available oxime treatment of nerve agent poisoning. Although oximes have been designed to reactivate the inhibited acetylcholinesterase (AChE), clinical experience has indicated that they are not always very effective as reactivators and at this very moment none of them can be regarded as a broad-spectrum antidote. In spite of this drawback, oximes are worth further investigating, since recent data derived from soman or tabun lethally intoxicated non-human primates suggest that the oxime HI-6 may exert a pharmacological effect that is not related to reactivation of inhibited AChE, but still leads to survival. This pharmacological effect causes recovery of neuronal transmission in the respiratory centres of the brain and recovery of neuromuscular transmission in the diaphragm. These findings have stimulated research to reveal the pharmacological basis of these effects in order to find drugs which could be more effective and less toxic than the available oximes. Since cholinergic drugs were able to exert this effect, a new concept for further treatment is suggested: maintenance of neuronal transmission in spite of continued AChE-inhibition by pharmacological manipulation of the cholinergic receptor. This should renew interest in the diverse pharmacological effects of oximes to reach a more effective treatment in the future.

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Evaluation of the therapeutic efficacy of some antimuscarinics against soman in vivo. Lau W M; Lewis K J; Dawson R M Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organization, Department of Defence, Melbourne, Victoria, Australia Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 423-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889794 AN 97044723 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The therapeutic efficacy of tacrine, atropine and glycopyrrolate alone or in combination with the oxime HI-6 against soman was evaluated in anaesthetized rats. Arterial blood pressure, heart rate, respiratory frequency and body temperature were monitored in vivo. Blood cholinesterases were determined after each drug or soman challenge. At the lowest concentration tested (2.5 mg kg-1), tacrine was effective in improving the survivability of the rat by a factor of 2.6 (protection ratio), whereas the protection by atropine or glycopyrrolate was either insignificant or only marginally effective (protection ratio ranged from 1.0 to 1.9). In combination with HI-6, atropine increased the ratio to 4.6. In contrast, tacrine with HI-6 failed to improve the efficacy of the regimen, while glycopyrrolate plus HI-6 showed only slight improvement. The four physiological parameters monitored were relatively constant during the time course of the experiment in both the control and those with drug therapy. The more noticeable changes occurred toward the end of the experiment when sufficient amount of soman was injected to cause lethality. Death of the animal was usually preceded by a surge of arterial blood pressure and heart rate and a decrease in respiratory frequency. These physiological parameters rapidly deteriorated to zero just before the animal died. Blood and plasma cholinesterases were significantly inhibited after the animal received a relatively small dose of soman (20 micrograms kg-1) and were almost completely inactivated after the lethal dose of soman was administered. However, these changes of enzyme activity did not correspond well with the survivability of the rat. The inclusion of HI-6 with the three antimuscarinics appeared to be capable of protecting some cholinesterases against soman.

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Efficacy of ibuprofen and pentoxifylline in the treatment of phosgene-induced acute lung injury. Sciuto A M; Stotts R R; Hurt H H Pathophysiology Division, United States Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 381-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889788 AN 97044717 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Phosgene, a highly reactive former warfare gas, is a deep lung irritant which produces adult respiratory distress syndrome (ARDS)-like symptoms following inhalation. Death caused by phosgene involves a latent, 6-24-h, fulminating non-cardiogenic pulmonary edema. The following dose-ranging study was designed to determine the efficacy of a non-steroidal anti-inflammatory drug, ibuprofen (IBU), and a methylxanthine, pentoxifylline (PTX). These drugs were tested singly and in combination to treat phosgene-induced acute lung injury in rats. Ibuprofen, in concentrations of 15-300 mg kg-1 (i.p.), was administered to rats 30 min before and 1 h after the start of whole-body exposure to phosgene (80 mg m-3 for 20 min). Pentoxifylline, 10-120 mg kg-1 (i.p.), was first administered 15 min prior to phosgene exposure and twice more at 45 and 105 min after the start of exposure. Five hours after phosgene inhalation, rats were euthanized, the lungs were removed and wet weight values were determined gravimetrically. Ibuprofen administered alone significantly decreased lung wet weight to body weight ratios compared with controls (P < or = 0.01) whereas PTX, at all doses tested alone, did not. In addition, the decrease in lung wet weight to body weight ratio observed with IBU+PTX could be attributed entirely to the dose of IBU employed. This is the first study to show that pre- and post-treatment with IBU can significantly reduce lung edema in rats exposed to phosgene.

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Subchronic toxicity evaluation of sulfur mustard in rats. Sasser L B; Miller R A; Kalkwarf D R; Cushing J A; Dacre J C Pacific Northwest Laboratory, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1996 Jan-Feb), 16(1), 5-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8821670 AN 96418885 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

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Acute toxicity of cyclohexylmethylphosphonofluoridate (CMPF) in rhesus monkeys: serum biochemical and hematologic changes. Young G D; Koplovitz I U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Archives of toxicology (1995), 69(6), 379-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7495375 AN 96114840 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Changes in serum biochemical and hematological parameters were studied in 20 male rhesus monkeys following acute poisoning by the organophosphate nerve agent cyclohexylmethylphosphonofluoridate (CMPF or GF). Animals were challenged with 5 x LD50 GF (233 micrograms/kg, IM) following pretreatment with pyridostigmine (0.3-0.7 mg/kg per 24 h) and treated with atropine (0.4 mg/kg, IM) and either 2-PAM (25.7 mg/kg, IM) or H16 (37.8 mg/kg, IM) at the onset of clinical signs or at 1 min after exposure. Muscle fasciculations, tremors, or convulsions occurred in 19 of 20 animals. Serum biochemical and hematologic parameters were analyzed 2 days and 7 days after exposure and compared to pre-exposure baseline values. Significant increases in creatine kinase (CK), lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase (ALT) and potassium ion (K+), associated with damage to striated muscle and metabolic acidosis, occurred in both oxime-treated groups 2 days after exposure. Total protein, albumin, red blood cell (RBC) count, hemoglobin concentration (Hb) and hematocrit (Hct), were decreased in both oxime-treated groups at 7 days. The results demonstrate that animals exposed to a single high dose of GF and treated with standard therapy exhibit changes in serum biochemical and hematological indices directly and indirectly associated with their clinical presentations.

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Production, characterization and application of monoclonal antibodies against the organophosphorus nerve agent Vx. Ci Y X; Zhou Y X; Guo Z Q; Rong K T; Chang W B Department of Chemistry, Peking University, Beijing, China Archives of toxicology (1995), 69(8), 565-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8534201 AN 96036122 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Two monoclonal antibodies (Vx-BB8 and Vx-EA11) to the chemical warfare agent Vx were produced and characterized. A competitive inhibition enzyme immunoassay was developed to detect Vx concentrations as low as 3.7 x 10(-7) - 3.7 x 10(-6) mol/l in biological samples. Vx-BB8 400 micrograms given intravenously immediately before 1 x LD95 Vx or 400 micrograms Vx-BB8 intraperitoneally 1.5 h-3 days before 1 x LD95 Vx could protect all the tested mice from death.

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Toxicity of sulphur mustard in adult rat lung organ culture. Sawyer T W; Wilde P E; Rice P; Weiss M T Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada Toxicology (1995 Jun 26), 100(1-3), 39-49. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7542806 AN 95350771 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of the chemical warfare agent sulphur mustard, (bis-(2-chloroethyl)sulphide, HD), was examined in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concentration (LC50) of HD in these cultures was reproducible, and in the microM range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathological examination of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochemically, and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulphur mustard.

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Toxicity of the combined nerve agents GB/GF in mice: efficacy of atropine and various oximes as antidotes. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Canada Archives of toxicology (1994), 68(1), 64-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166607 AN 94219995 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of a combination of isopropyl methylphosphonofluoridate (sarin; GB) and cyclohexyl methylphosphonofluoridate (GF) and the efficacy of various oxime reactivators in combination with atropine against the combined GB/GF challenge were evaluated in mice. The 24-h s.c. LD50 of the GB/GF combination was 1.15 mumol/kg (1.10-1.21; 95% confidence limits). Mice administered GB/GF displayed typical signs of nerve agent poisoning such as tremors and convulsions, with death most likely due to anoxia subsequent to respiratory arrest. The GB/GF LD50 value was comparable to the s.c. LD50 of 1.35 and 1.21 mumol/kg for GF and GB in mice, respectively. Combining the two nerve agents did not result in potentiation of the toxicity. In combination with atropine sulfate (17.4 mg/kg, i.p.), which alone did not reduce mortality, the oximes tested, 2-PAM, obidoxime and HI-6, were all effective when administered 5 min before 3 x LD50 dose of GB/GF with 24-h ED50 values of 102.5, 18.22 and 1.96 mumol/kg, respectively. Use of the GB/GF combination does not appear to confer any unique toxicity profile and appears to be easily treated with the standard therapy of a cholinolytic and oxime.

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Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs. Due A H; Trap H C; Langenberg J P; Benschop H P TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1994), 68(1), 60-3. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166606 AN 94219994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson B W; Kawakami T G; Cone N; Henderson J D; Rosenblatt L S; Goldman M; Dacre J C Department of Avian Sciences, University of California, Davis 95616-5224 Toxicology (1994 Jan 26), 86(1-2), 1-12. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8134917 AN 94182225 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (Tabun, phosphoramidocyanidic acid, dimethyl-, ethyl ester) as part of a program to demilitarize chemical warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only three of the five assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Evaluation of the toxicity, pathology, and treatment of cyclohexylmethylphosphonofluoridate (CMPF) poisoning in rhesus monkeys. Koplovitz I; Gresham V C; Dochterman L W; Kaminskis A; Stewart J R US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425 Archives of toxicology (1992), 66(9), 622-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1482284 AN 93129117 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (CMPF) is an organophosphate cholinesterase inhibitor with military significance. The purpose of these studies was 1) to determine the acute toxicity of CMPF in the male rhesus monkey, 2) to evaluate the efficacy of pyridostigmine (PYR) pretreatment plus atropine and oxime (2-PAM or H16) treatment, and 3) to evaluate the pathological consequences of acute poisoning. An i.m. LD50 of CMPF was estimated using an up-and-down dose selection procedure and 12 animals. The 48-h and 7-day LD50 was 46.6 micrograms/kg, i.m. In the protection experiments, pyridostigmine (0.3-0.7 mg/kg/24 h) was administered by surgically implanted osmotic minipumps for 3-12 days resulting in 21-65% inhibition of erythrocyte acetylcholinesterase activity. Animals were challenged with 5 x L50 CMPF (233 micrograms/kg) and treated with atropine (0.4 mg/kg) and either 2-PAM (25.7 mg/kg) or HI6 (37.8 mg/kg) at the onset of signs or 1 min after challenge. Osmotic pumps were removed within 30 min after agent challenge. Pyridostigmine, atropine, and either 2-PAM or H16 were completely effective against CMPF, saving ten of ten animals in each group. In comparison, three of five animals challenged with 5 x LD50 of soman and treated with atropine and 2-PAM survived 7 days. The primary histologic lesions in the acute toxicity group were neuronal degeneration/necrosis and spinal cord hemorrhage. The CMPF treated groups (total of 20 animals) had minimal nervous system changes with no significant lesion difference resulting from the different oxime therapies. The primary non-neural lesions were degenerative cardiomyopathy and skeletal muscle degeneration which occasionally progressed to necrosis and mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)

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Efficacy of various oximes against GF (cyclohexyl methylphosphonofluoridate) poisoning in mice. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Alta., Canada Archives of toxicology (1992), 66(2), 143-4. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1605730 AN 92296882 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The efficacy of oxime (HI-6, toxogonin or PAM Cl) therapy against GF (cyclohexyl methylphosphonofluoridate) poisoning was assessed in mice. It was found that the combinations of atropine and either toxogonin or HI-6 were effective therapies against GF poisoning. PAM therapy was ineffective. HI-6 was the only oxime which reactivated GF inhibited acetylcholinesterase. This might explain the reason why the HI-6 treated mice appeared to recover more quickly from the incapacitating effects following GF poisoning.

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer T W; Weiss M T; D'Agostino P A; Provost L R; Hancock J R Defence Research Establishment Suffield, Alberta, Canada Journal of applied toxicology : JAT (1992 Feb), 12(1), 1-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1564246 AN 92226402 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chemical warfare activity was subjected to chemical analysis and bioassay. Sarin and several related compounds were confirmed in the soil by capillary column gas chromatography-mass spectrometry (GC-MS); however, the binding of these compounds to the soil hindered quantitation. The chemical results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified standards in chick embryo neuron cultures, a reasonable agreement was found between the chemical and bioassay semi-quantitative estimates of sarin content in the soil extract. Furthermore, the in vitro system appears to offer a sensitive technique for the estimation of sarin remaining bound to the soil following solvent extraction as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy P M; Hansen A S; Hand B T; Boulet C A Defence Research Establishment Suffield, Ralston, Alberta, Canada Toxicology (1992), 72(1), 99-105. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1539175 AN 92169690 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a standard set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI-6 greater than HLo-7 greater than pyrimidoxime. HLo-7 was very effective against tabun poisoning while HI-6 and pyrimidoxime were of moderate value. Against GF, HI-6 and HLo-7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLo-7 to a slightly lesser degree. The other oximes suffered from their lack of effects against one or more of the organophosphates.

[megalomania]

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Aluminum nitride defect chemistry dependence on sintering atmosphere. Chang, E. K.; Kirschner, M. J. BOC Group Technical Cent., Murray Hill, NJ, USA. Journal of Materials Science Letters (1996), 15(18), 1580-1581. CODEN: JMSLD5 ISSN: 0261-8028. Journal; General Review written in English. CAN 125:282600 AN 1996:614771 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 12 refs., of equations explaining theor. relations between aluminum nitride defect chem. and sintering atm.

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Microstructure, chemical reaction and mechanical properties of TiC/Si3N4 and TiN-coated TiC/Si3N4 composites. Huang, Jow-Lay; Lee, Ming-Tung; Lu, Horng-Hwa; Lii, Ding-Fwu. Dep. Material Science Eng., National Cheng-Kung Univ., Tainan, Taiwan. Journal of Materials Science (1996), 31(18), 4899-4906. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:254919 AN 1996:610489 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Silicon nitride contg. various compns. of as-received TiC and TiN-coated TiC, were hot pressed at 1800 C for 1 h in a nitrogen atm. In TiN-coated TiC/Si3N4 composites, TiC reacted first with the TiN coating to form a titanium carbonitride interlayer at 1450 C, which essentially reduced further reactions between TiC and Si3N4 and enhanced densification. TiN-coated TiC/Si3N4 composites exhibited better densification, hardness, flexural strength and fracture toughness than those of as-received TiC/Si3N4. The toughening mechanisms for as-received TiC/Si3N4 and TiN-coated TiC/Si3N4 composite were attributed to crack deflection, load transfer and crack interference by the compressive thermal residual stress.

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Wet chemical synthesis of ZrO2-SiO2 composite powders. Wang, Shi-Wei; Huang, Xiao-Xian; Guo, Jing-Kun. Shanghai Inst. Ceramics, Chinese Academy Sciences, Shanghai, Peop. Rep. China. Journal of the European Ceramic Society (1996), 16(10), 1057-1061. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 125:254896 AN 1996:596753 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of compn. xZrO2(I-x)SiO2, with x = 10, 20, 30 and 40 vol.%, have been prepd. by a wet chem. method using fumed silica and zirconyl chloride as precursors. Thermogravimetric anal. and differential thermal anal. (DTA) show that wt. loss is caused by release of the absorbed water and decompn. of the Zr(OH)4 gels. Gels were heat-treated for 2 h at 500, 700, 900, 1100 and 1350C, and the products examd. using IR spectroscopy. The increasing intensity of the peak at 800 cm-1 in the IR spectra with increasing temp. is attributed to the formation of Si-O-Si bonds among different SiO2 particles, which means that the SiO2 particles grow bigger with increasing temp. The DTA exothermic peak as well as the IR results reveal that the crystn. of tetragonal zirconia (t-ZrO2) begins at about 900C, which is confirmed by x-ray diffraction (XRD). XRD curves also suggest that the silica matrix contributes to the thermal stability of t-ZrO2. The stability of t-ZrO2 is interpreted by the particle-size effect.

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Structure-property relationship of ceramic coatings produced by laser processing. De Hosson, J. Th. M.; Zhou, X. B. Dep. Applied Physics, Univ. Groningen, Groningen, Neth. Materials Research Society Symposium Proceedings (1996), 397(Advanced Laser Processing of Materials--Fundamentals and Applications), 537-542. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:306847 AN 1996:579019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper deals with a well known puzzling observation that wetting in some instances is improved by a chem. reaction between a liq. and a solid substrate in laser processing while in other systems just the opposite effect takes place. Contact angles of liq. Al on SiO2 and liq. Ti on Al2O3 are reported and some results of laser melt injection of SiO2 particles into molten Al. The surface and interface structures were explored by SEM and energy dispersive x-ray spectrometry. According to the exptl. observations, it appears that the vol. change of ceramic substrates during reaction plays a key role in the effect of chem. reaction on wetting.

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Mechanical and thermal properties of SiC-SiC composites made with CVR SiC fibers. Kowbel, W.; Tsou, H. T.; Bruce, C. A.; Withers, J. C. MER Corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1996), 410(Covalent Ceramics III--Science and Technology of Non-Oxides), 417-422. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 125:202665 AN 1996:502987 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention and dimensional change at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a SiC reinforcement based upon the conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. These new SiC filaments exhibit excellent creep resistance at temps. up to 1600C. SiC-SiC composites were fabricated using different types of graphite fabric converted to SiC fabric utilizing the CVR process combined with a polycarbosilane (PCS) infiltration and CVI densification. In addn., enhancement of the composite through-the-thickness thermal cond. was accomplished via boron doping of the matrix. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites will be presented.

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The influence of surface kinetics in modeling chemical vapor deposition processes in porous preforms. Dekker, J. P.; Moene, R.; Schoonman, J. Lab. Appl. Inorg. Chem., Delft Univ. Technol., Delft, Neth. Journal of Materials Science (1996), 31(11), 3021-3033. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65201 AN 1996:378298 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The isothermal chem. vapor infiltration (ICVI) process is a well known technique for the prodn. of composites and the surface modification of porous preforms. Math. modeling of the process can provide a better understanding of the influence of individual process parameters on the deposition characteristics such as final porosity or deposition profiles in the pore network. The influence of different rate expressions for several binary compds. on the ICVI process is discussed. Exptl. work is used to validate the importance of correct kinetic expressions in a continuous ICVI model for cylindrical pores. The predicted infiltration characteristics are compared with exptl. results. The final densification and Thiele modulus, i.e. a no. which is a measure for the diffusion limitations in a pore, are used for the evaluation of the presented model, and conditions are given for an optimal densification of a porous preform by the ICVI process for several binary compds. The deposition profiles as predicted by the model calcns. are in agreement with the exptl. detd. deposition profiles of TiN and TiC in small tubes. Moreover, it can be concluded that the shape of the deposition profiles is detd. by the heterogeneous reaction kinetics. There is only a qual. agreement between the predicted densification and measured densification for the synthesis of TiN and TiB2 in sintered porous alumina. This mismatch can be explained in terms of a complexity of the pore network and differences in reaction kinetics. Model calcns. reveal that there is a scattering for the predicted residual porosity as a function of the Thiele modulus for TiN. Moreover, this Thiele modulus can not fully account for the changes in densification at different temps. Given these uncertainties it is likely that a residual porosity of less than one percent can be obtained if the Thiele modulus is smaller than 1  10-4. However, a CVI process with such a small Thiele modulus will not be practical, because of the concomitant long process times.
Therefore, more precise conditions for the individual process parameters, i.e. concn., reactor pressure, and temp. are deduced from the model calcns.

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Pressure-pulsed chemical vapor infiltration of TiN into SiC particulate preforms. Sugiyama, K.; Sugata, M. Dep. Appl. Chem., Aichi Inst. Technol., Toyota, Japan. Journal of Materials Science (1996), 31(11), 2945-2949. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 125:65198 AN 1996:378286 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC particulate preforms were infiltrated by TiN matrix from a gas mixt. of TiCl4 (5%), nitrogen (30%) and hydrogen using a repeating pressure pulse between 760 and about 1 torr. SiC particle sizes of 5 and 20 m were used. For matrix packing into deep level, optimum temp. was detd. between 800 and 850, and the max. packing ratio reached 67% after 4  104 pulses at 850. The increase of TiCl4 concn. to 10% resulted in higher deposition rate and packing ratio. The decrease of nitrogen concn. led to slower deposition, i.e., a similar effect to temp. lowering. The max. flexural strength measured was 140 MPa.

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Synthesis of mullite coatings by chemical vapor deposition. Mulpuri, Rao P.; Sarin, Vinod K. Dep. Mfg. Eng., Boston Univ., Boston, MA, USA. Journal of Materials Research (1996), 11(6), 1315-1324. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 125:39956 AN 1996:366859 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Formation of mullite on ceramic substrates via chem. vapor deposition was investigated. Mullite is a solid soln. of Al2O3 and SiO2 with a compn. of 3Al2O32SiO2. Thermodn. calcns. performed on the AlCl3-SiCl4-CO2-H2 system were used to construct equil. chem. vapor deposition (CVD) phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were detd. Through process optimization, cryst. CVD mullite coatings have been successfully grown on SiC and Si3N4 substrates. Results from the thermodn. anal., process optimization, and effect of various process parameters on deposition rate and coating morphol. are discussed.

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Mixed chromium and aluminum oxides elaborated by a sol-gel process. I. Chemistry of the preparation. Rezgui, Saloua; Ghorbel, Abdelhamid; Henry, Marc. Lab. Chimie Materiaux Catalyse, Dep. Chimie, Tunisia. Journal of Materials Synthesis and Processing (1995), 3(6), 371-376. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 125:16967 AN 1996:331762 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Gels of mixed chromium and aluminum oxide were prepd. by a sol-gel process. The precursor is a mixt. of Al(O-s-Bu)3 and Cr(acac)3 with a mass ratio Al/Cr = 10 in sec-butanol. Gelation occurred by adding acetic acid. The amt. of added acetic acid is represented by the ratio k = [CH3COOH]/[Al(O-s-Bu)3], with k varying between 0.5 and 3. Acetic acid played crucial roles in both hydrolysis and polycondensation, (1) producing water in situ by esterification, (2) modifying the precursor by substituting some of the O-s-Bu ligands by acetate ligands, and (3) catalyzing the polycondensation. The importance of each of these roles in the process as well as the nature of the products varied with the ratio k.

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Influence of alloying elements on the chemical reactivity between Si-Al-O-N ceramics and iron-based alloys. Vluegels, J.; Vandeperre, L.; Van Der Biest, O. Dep. Metallurgy Materials Eng., Katholieke Univ. Leuven, Leuvan, Belg. Journal of Materials Research (1996), 11(5), 1265-1276. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 124:323490 AN 1996:293140 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. interaction between two '-O' Si-Al-O-N ceramics and a no. of iron-based alloys is studied by means of static interaction couple expts. at 1100 and 1200 C. The onset temp. of reaction of Si3N4 with pure iron was 1095 C, which is in good agreement with a calcd. temp. of 1033 C. During the interaction, silicon and nitrogen from the ceramic dissolve and diffuse into the iron alloy, whereas the remaining aluminum and oxygen form Al2O3 particles. The interaction between the ceramic and iron alloy is reaction controlled. In the initial stage of the interaction, the dissocn. rate of the ceramic is the rate-controlling step. After the ceramic/metal interface is isolated from the furnace atm., the nitrogen soln. rate into the iron alloy becomes rate controlling. The influence of alloying elements on the reactivity could be related to their effect on the nitrogen soly. in the iron alloy. Ni, Si, and C decrease the nitrogen soly. and decrease the reactivity with the Sialon ceramic. Cr and Mo have the opposite effect. The thickness of the interaction layer on the ceramic side of the interaction couple was found to be a function of the calcd. nitrogen soly. in the iron alloy at 1 atm nitrogen pressure, making it possible to predict the relative chem. reactivity of a no. of iron-based alloys with the same Sialon ceramic.

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Preparation and pressureless sintering of chemical vapor deposited SiC-B composite powder. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Institute Materials Research, Tohoku University, Sendai, Japan. Journal of Materials Science (1996), 31(3), 679-83. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 124:239925 AN 1996:180535 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-B composite powder was prepd. by chem. vapor deposition (CVD) using (CH3)2SiCl2 + B2H6 + H2 as source gases at 1673 K. The powder was -type polycryst. silicon carbide contg. several per cents of boron and carbon. The boron content increased from 0 to 7.7 mass% as the B2H6 gas concn. increased from 0 to 0.7 mol%. Boron and carbon in amorphous form dispersed homogeneously in the -SiC polycryst. particles. The particles were spherical, non-agglomerated and uniform in size with an av. particle size of about 50 nm. Sintering tests were performed with the resulting composite powder without applying pressure. Powder contg. 1 mass% boron and 2 mass% carbon was sintered to a d. of 3.16 x 103 kg m-3 at 2273 K, and the Vickers hardness of the sintered body was 30 GPa. When the sintering temp. was higher than 2323 K, significant grain growth due to the phase transformation from  to  form occurred, which decreased bulk d. and Vickers hardness.

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Nanocrystalline metals, intermetallics, and a metal-matrix nanocomposite by solution-based chemical reductions. Buhro, W. E.; Haber, J. A.; Waller, B. E.; Trentler, T. J.; Suryanarayanan, R.; Frey, C. A.; Sastry, S. M. L. Department Chemistry, Washington University, St. Louis, MO, USA. Polymeric Materials Science and Engineering (1995), 73 39-40. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 124:123490 AN 1996:951 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A metal salt soln. was reduced to nanocryst. and nanocomposite. CuCl in THF was reduced with NaBH4 to form nanocrystal Cu, and Ni and Al can also be prepd. in similar manner. NiCl2 soln. was reduced with LiAlH4 ti NiAl intermetallic compds. of nano size. MoCl5 and SiCl4 were reduced with NaK to nanocryst. MoSi2 in ultrasound field. TiB2 nanocryst. particles were suspended in THF and CuCl was reduced to obtain a Cu-coated TiB2 nanocomposite.

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Preparation of low density free-standing shape of SiC by pressure-pulsed chemical vapor infiltration. Sugiyama, K.; Norizuki, K. Dep. Applied Chem., Aichi Inst. Technology, Toyoda, Japan. Journal of Materials Science Letters (1995), 14(23), 1720-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 124:64057 AN 1995:1000853 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of the conditions of pressure-pulsed chem. vapor infiltration (PCVI) on the deposition rate, ease of substrate oxidn., gross d., and flexural strength in prepn. of low-d. free-standing SiC shapes were examd. By selection of a porous carbon substrate, highly porous SiC shapes with a desirable pore distribution may be prepd. by the PCVI process.

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Identification of chemical and physical change during acid cleaning of ceramics. Johnson, Jessica S.; Erickson, Harold M.; Iceland, Harry. Texas Mem. Mus., Univ. Texas, Austin, TX, USA. Materials Research Society Symposium Proceedings (1995), 352(Materials Issues in Art and Archaeology 4), 831-7. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 124:54897 AN 1995:985335 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This report describes the results of two expts. characterizing chem. and phys. change in ceramic constituents occurring from acid solns. commonly used to remove deposits from the surface of archaeol. ceramics. The first examines the chem. effects of hydrochloric acid, in an attempt to identify the yellow color, commonly known as "acid burn", often seen in museum collections on black-on-white sherds found in the Southwestern U.S. The compd. is identified as Fe2O3H2O. The second study compares the phys. effects of different acids on a group of Maya sherds. All acids tested in this study were found to cause phys. damage.

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Influence of particle characteristics on sintering behavior of alumina-zirconia composites. Balasubramanian, M.; Malhotra, S. K.; Gokularathnam, C. V. FRP Research Center, Indian Inst. of Technology, Madras, India. Journal of Materials Science Letters (1995), 14(21), 1484-5. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:347792 AN 1995:927403 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A uniform distribution of zirconia particles in an alumina matrix can be achieved by chem. processing methods. Three chem. processing routes were used to obtain better powders. The sintered d. and the tetragonal ZrO2 content of composites were correlated with powder size and morphol.

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Wet air oxidation of energetics and chemical agent surrogates. Copa, William M.; Momont, Joseph A. Zimpro Environmental Inc., Rothschild, WI, USA. Journal of Energetic Materials (1995), 13(3&4), 235-58. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295590 AN 1995:895724 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Wet oxidn. studies have been conducted on a no. of energetic materials and wastewaters derived from energetic materials to demonstrate high destruction levels of specific energetic components. Triple-base propellant, OTTO Fuel (used as torpedo propellant) and hydrazine-based rocket fuel were energetics of interest. Triple-base propellant contain nitrocellulose, nitroglycerin, and nitroguanidine. OTTO Fuel contains substantial amts. of propylene glycol trinitrate. Hydrazine based rocket fuel contains hydrazine and 1,1-di-Me hydrazine (asym. di-Me hydrazine or UDMH). A bench scale wet air oxidn. study on alk. hydrolyzates of triple-base propellants indicated that essentially complete destruction of the reactive nitrogen components could be achieved at an oxidn. temp. of 280. Bench scale wet air oxidn. studies on OTTO Fuel wastewaters indicated that a >99% destruction of propylene glycol dinitrate can be achieved at 280. Processing OTTO Fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved even higher destruction levels. Bench scale wet air oxidn. studies on hydrazine-based rocket fuel wastewaters indicated that a 99.8% destruction of hydrazine and a >99.0% destruction of 1,1-dimethylhydrazine can be oxidized at 280. Again, processing of hydrazine-based rocket fuel wastewaters in a continuous flow, full scale wet air oxidn. unit achieved similar destruction levels. The application of wet air oxidn. for the destruction of chem. agents has been made by the extrapolation of data from the wet air oxidn. of compds. with similar chem. structures or of surrogate compds. Sarin and V-agents are nerve agents which have an organo-phosphorus structure similar to that of contain commonly used pesticides. Pesticides such as glyphosate and malathion, which have a similar organo-phosphorus structure, are essentially completely destroyed (>99% destruction) by wet air oxidn. at 200-280. The chem. agent surrogate, di-Me Me phosphonate (DMMP) was wet air oxidized at 220-280. Alk.
hydrolyzed DMMP was wet air oxidized at 280. All of the oxidized effluents showed a >97.5% destruction efficiency for the DMMP. The blister agent, mustard (HD) is a chlorinated sulfide, bis(2-chloroethyl) sulfide. Org. sulfides such as mercaptans can be destroyed by wet air oxidn. at 260-280. It is concluded that the wet air oxidn. process is a promising alternative to incineration for disposal of energetics and chem. warfare agents.

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Molten salt oxidation of chemical munitions. Stewart, Albert; Schnittgrund, Gary. PyroPacific Processes, Grand Hills, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 213-34. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295589 AN 1995:895723 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Molten salt oxidn. is reviewed as a potential near term alternative technol. for the destruction of chem. agents. Initial tests completed by the US Army in 1975 showed the promise of achieving very high removal efficiencies on actual agents. Recent testing by DOE has verified the potential for very low PIC and dioxin or furan releases. To further explore the possible application of this technol. to chem. agent destruction, a molten salt reactor and assocd. equipment was designed to process a nominal 50 kg/h of Sarin. Mass and energy balances are presented for process conditions representing a range of molten salt potential operational modes and schemes for enhancing plant capacity. Process economics are presented.

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Supercritical water oxidation of chemical agents, and solid propellants. Spritzer, M. H.; Hazlebeck, D. A.; Downey, K. W. San Diego, CA, USA. Journal of Energetic Materials (1995), 13(3&4), 185-212. CODEN: JOEMDK ISSN: 0737-0652. Journal written in English. CAN 123:295588 AN 1995:895722 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Supercrit. water oxidn. (SCWO), also referred to as hydrothermal oxidn. (HTO), is a developing technol. for the destruction of hazardous and nonhazardous wastes. SCWO destroys combustible materials using an oxidant in water at 350-600 and pressures of 17 MPa. General Atomics and its subcontractors are currently conducting 2 comprehensive research and demonstration programs geared toward the destruction of Department of Defense (DoD) wastes utilizing SCWO technol. Wastes of primary interest include chem. agents and solid propellants. Tech. challenges, particularly corrosion and solids handling, were overcome, and the destruction of chem. agents and solid propellants was demonstrated on a bench scale. SCWO results for chem. agents show destruction and removal efficiencies for GB, VX, and mustard agents to be in excess of 99.9999%, limited only by detection capability. SCWO results for hydrolyzed Class 1.1 solid propellant show destruction and removal efficiencies for total org. carbon (TOC) of >99.9%. Design and fabrication of a transportable SCWO pilot plant for chem. warfare agents, propellants and other DoD hazardous wastes and a prototype HTO system for solid rocket propellant disposal are complete and demonstration testing is underway.

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Pressure pulsed chemical vapor infiltration of SiC to two-dimensional-Tyranno/SiC-C preforms. Sygiyama, Kohzo; Yoshida, Yazutoshi. Department of Applied Chemistry, Aichi Institute of Technology, Toyoda, Japan. Journal of Materials Science (1995), 30(20), 5125-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:320390 AN 1995:894944 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preforms of two-dimensional Tyranno fiber (SiC base) of 7  20  1.3 mm3 were chem. vapor infiltrated with SiC at 850-1050C from a gas mixt. of CH3SiCl3 (6%)-H2 using pressure pulses between below 0.3 kPa and 0.1 MPa. Above 900C, films grew on the macrosurface dominantly. At 850C, residual porosity decreased to about 10% after 105 pulses, and three point flexural strength reached about 200 MPa. X-ray diffractograms on the surface showed the deposits to be -SiC only.

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Matrix characterization of fiber-reinforced SiC matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M.; More, K. L.; Sheldon, B. W.; Besmann, T. M.; Headinger, M. H.; Davis, R. F. Oak Ridge National Laboratory, Oak Ridge, TN, USA. Journal of Materials Science (1995), 30(17), 4279-85. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 123:206673 AN 1995:804167 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ceramic matrix composites (CMCs), that consist of silicon carbide (SiC) reinforced with continuous Nicalon or T-300 fibers, are being developed for many high-temp. structural applications. The large potential use of CMCs has prompted an in-depth investigation and characterization of these materials. Electron microscopy and micro-Raman spectroscopy were used to characterize and compare the SiC matrix crystal structure and morphol. of composite materials fabricated by two different chem. vapor infiltration (CVI) processes.

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Characterization of pseudo-porous SiC/C coatings on NextelTM 440 and NicalonTM fibers. Khasgiwale, N. R.; Butler, E. P.; Tsakalakos, L.; Hensley, D. A.; Cannon, W. R.; Danforth, S. C.; Gonczy, S. T. Center Ceramic Research, Rutgers University, Piscataway, NJ, USA. Materials Research Society Symposium Proceedings (1995), 365 395-400. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177329 AN 1995:774261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Pseudo-porous SiC/C coatings were deposited on NextelTM 440 and NicalonTM fibers by CVD. The morphol. and chem. of the coatings was evaluated, both before and after oxidn., using SEM, X-Ray Diffraction Anal. (XRD), XPS and Auger spectroscopy. Coated fibers were subjected to two different oxidn. treatments to assess coating stability: a) oxidn. at 600C for 20 h, and b) oxidn. at 1000C for 20 h. Pseudo-porous SiC/C on NicalonTM fibers appear to be more oxidn. resistant than the same coatings on NextelTM440 fibers.

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The preparation and economics of silicon carbide matrix composites by chemical vapor infiltration. Roman, Yvette G.; Stinton, David P. Centre Technical Ceramics-TNO, Eindhoven, Neth. Materials Research Society Symposium Proceedings (1995), 365 343-50. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 123:176964 AN 1995:774254 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 35 refs. A no. of processing techniques that are currently in use for the development and prodn. of continuous fiber reinforced ceramic composite materials are described. The limited no. of available processing routes are compared with respect to the resulting material properties. The chem. vapor infiltration (CVI) technique is one of the most extensively developed methods. During the last decade, at least five different modifications of the isobaric isothermal CVI principle have been developed; each route having its own benefits. CVI techniques have now been developed to the extent that industrial commercialization is being realized. Projected cost aspects of the various CVI manufg. techniques are examd. and compared.

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Properties of SiC-SiC composites produced using CVR converted graphite cloth to SiC cloth. Kowbel, W.; Kyriacou, C.; Gao, F.; Bruce, C. A.; Withers, J. C. MER corp., Tucson, AZ, USA. Materials Research Society Symposium Proceedings (1995), 365 197-202. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177312 AN 1995:774236 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Nicalon fiber is the primary reinforcement in SiC-SiC composites currently produced by a variety of techniques including CVI and polymer infiltration. Low strength retention at high temps. of the Nicalon fibers limits the choice of manufg. processes which can be employed to produce low cost SiC-SiC composites. MER has developed a new SiC reinforcement based upon a conversion of low cost carbon fabric to SiC via a Chem. Vapor Reaction (CVR) process. This new SiC filaments exhibit an excellent creep resistance at temps. up to 1600C. Several SiC-SiC composites were fabricated using graphite fabric converted to SiC fabric utilizing the CVR process combined with a slurry infiltration and CVI densification. A correlation between processing conditions, microstructure and properties of the SiC-SiC composites are discussed.

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Chemically bonded ceramic matrix composites: densification and conversion to diffusion bonding. Johnson, Bradley R.; Guelguen, Mehmet A.; Kriven, Waltraud, M. Department Materials Science and Engineering, University Illinois, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1995), 365 67-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:177295 AN 1995:774216 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. bonded ceramics appear to be a promising alternative route for near-net shape fabrication of multi-phase ceramic matrix composites (CMC's). The hydraulic (and refractory) properties of fine mono-calcium aluminate (CaAl2O4) powders were used as the chem. bonding matrix phase, while calcia-stabilized zirconia powders were the second phase material. Samples contg. up to 70 wt% (55 vol%) zirconia have been successfully compacted and sintered. Various processing techniques were evaluated. Processing was optimized based on material properties, dilatometry and simultaneous thermal anal. (DTA/TGA). The phys. characteristics of this novel CMC were characterized by hardness, d., and fracture toughness testing. Microstructures were evaluated by SEM and phase identification was verified using XRD.

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Oxidative catalytic decomposition of toxic gases using hydroxyapatite and fluorhydroxyapatite. Palucka, Timothy P.; Eror, Nicholas G.; McNamara, Thomas A. Department Materials Science and Engineering, University Pittsburgh, Pittsburgh, PA, USA. Materials Research Society Symposium Proceedings (1995), 368(Synthesis and Properties of Advanced Catalytic Materials), 275-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:151604 AN 1995:734790 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

An oxidative catalytic route to decomp. nerve gases was studied using hydroxyapatite (HA, Ca10(PO4)6(OH)2) and its partially fluorinated analog fluorhydroxyapatite (FHA, Ca10(PO4)6Fx(OH)2-x). Samples were prepd. with surface areas of 34-238 m2/g to study surface area effects; 1.2 wt.% Pt was deposited on 1 substrate to study the effect of a transition metal on activity and selectivity. Reaction studies were performed using di-Me methylphosphonate, a nerve gas simulant, in a stream of 80% N and 20% O at 573 K and atm. pressure. High surface area FHA samples showed an increase in the protection period (period of 100% conversion) with increasing F substitution; such an increase was not seen for low surface area FHA samples. In the absence of Pt, the reaction products were CH3OH and di-Me ether; with Pt, CO2 was also obtained.

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Toxicity of sulfur mustard in adult rat lung organ culture. Sawyer, Thomas W.; Wilde, Paul E.; Rice, Paul; Weiss, M. Tracy. Medical Countermeasures Section, Defence Research Establishment Suffield, Box 4000, Medicine Hat, Alberta, Can. Toxicology (1995), 100(1-3), 39-49. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 123:104668 AN 1995:700024 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The toxicity of the chem. warfare agent sulfur mustard, (bis-(2-chloroethyl)sulfide, HD), was examd. in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concn. (LC50) of HD in these cultures was reproducible, and in the M range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathol. examn. of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochem., and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulfur mustard.

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Characterization and surface chemistry of uncoated and coated silicon nitride powders. Schmidt, H.; Nabert, G.; Ziegler, G.; Goretzki, H. Inst. Materialforschung, Univ. Bayreuth, Bayreuth, Germany. Journal of the European Ceramic Society (1995), 15(7), 667-74. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 123:90766 AN 1995:695131 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Various Si3N4 powders, produced by different procedures, were characterized by imaging (TEM) and anal. methods (EDS, FT-IR, XPS) in the as-received state as well as after doping with a metal oxide (MgO). For the doping, an alternative procedure to the usual methods was applied based on sol. organometallic compds. Anal. TEM combined with lateral resoln. element anal. and XPS measurements was used for morphol., structural and anal. characterization. The distribution of the dopant was deduced from measurements of XPS sputter depth profiles. These investigations were supplemented by FT-IR measurements to det. qual. and semi-quant. the reactive groups on the particle surfaces of the as-received powders. For comparison, measurements were performed with Si3N4 powders which were doped by the above chem. procedure and by mech. mixing. The results of the various characterization methods are interpreted in the form of a model display for surface reactions of organometallic doping reagents on the surfaces of ceramic particles. The results show that Si3N4 powders with high concn. of OH groups on their particle surface reveal very good distribution of the fluxing element (layer-like coating).

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Influence of crystallographic orientation, chemical inhomogeneities, material transport anisotropy and elastic strain energy on the migration of grain boundaries in chromium-doped alumina during internal reduction. Backhaus-Ricoult, Monika; Peyrot-Chabrol, A.; Chiron, R.; Hagege, S. Cent. d'Etudes Chim. Metall., CNRS, Vitry, Fr. Materials Research Society Symposium Proceedings (1995), 357(Structure and Properties of Interfaces in Ceramics), 293-9. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 123:90732 AN 1995:685875 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Diffusion-induced grain boundary migration is obsd. during internal redn. of chromium-doped alumina. It occurs because grain boundary diffusion is fast compared to lattice diffusion of oxygen. The oxygen chem. potential relaxes between grain boundaries and adjacent grains. Migration to either side of the boundary is controlled by multiple factors: chem. compn. differences between adjacent grains, elastic strain energy differences on the two sides of the boundary plane or by more rapid oxygen relaxation when the c-axis of a grain is perpendicular to the boundary plane.

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Synthesis and chemical stability of NaSn2P3O12. Breval, E.; Harshe, G.; Agrawal, D. K.; Limaye, S. Y. Intercoll. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Journal of Materials Science Letters (1995), 14(10), 728-31. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 123:39204 AN 1995:606064 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

NaSn2P3O12 and NaZr2P3O12 powders were prepd. by solid-state reaction methods and sintered at 1050-1200. The resulting pellets were characterized in terms of d., thermal expansion, and phase compn. before and after chem. stability tests. Chem. stability tests were performed in polethylene containers in 3 solns., H+ + SO42- (pH = 0.5), Na+ + H+ + SO42- (pH = 0.7), and Na+ + OH- (pH + 14.3). Results indicate that NaSn2P3O12 is a very stable NZP compd. in high and low pH solns. (pH + 0.5-14.3) as compared to the parent compn. NaZr2P3O12, which shows high losses, esp. in alk. leachants. The surface-to-vol. of a single phase NaSn2P3O12 material, sintered without sintering agents, hardly affects the dissoln. Use of a sintering agent may result in a highly reactive grain boundary phase, the amt. of which may exceed the amt. of added sintering aid.

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Low-level detection of chemical agent simulants in meat and milk by ion trap mass spectrometry. Buchanan, Michelle V.; Hettich, Robert L.; Xu, Jing Hai; Waters, Larry C.; Watson, Annetta. Chemical and Analytical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Building 5510, MS/6365, Oak Ridge, TN, USA. Journal of Hazardous Materials (1995), 42(1), 49-59. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 123:31526 AN 1995:596587 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Anal. methods for the detection of two chem. warfare agent simulants, diisopropyl methylphosphonate and chloroethylethylsulfide, in beef tissue and milk were demonstrated to be effective to levels as low as 50-100 ppb. These methods are based upon thermal desorption into an ion trap mass spectrometer. Selective detection of the target compds. is achieved by isobutane chem. ionization in combination with collision-induced dissocn., which yields characteristic fragment ions. Rapid sample clean-up steps were also devised to reduce interferences from the sample matrix. The low detection limits achieved with this method suggest that it may be possible to take small tissue samples from livestock by needle biopsy, without requiring animal sacrifice for the anal. In addn., because the new methods may be performed more quickly than conventional methods requiring substantial sample prepn. and anal. time, more samples could be analyzed.

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The effect of ceria co-doping on chemical stability and fracture toughness of Y-TZP. Boutz, M. M. R.; Winnubst, A. j. a.; Van Langerak, B.; Scholtenhuis, R. J. M. Olde; Kreuwel, K.; Burggraaf, A. J. Faculty of Chemical Technology, University of Twente, Enschde, Neth. Journal of Materials Science (1995), 30(7), 1854-62. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 122:271892 AN 1995:504770 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and ageing resistance of yttria, ceria-stabilized tetragonal zirconia polycrystals (Y, Ce-TZP) were evaluated as a function of grain size and ceria content. Very fine grained, fully dense materials could be produced by sinter forging at relatively low temps. (1150-1200C). The aging resistance in hot water (185C) of 2 mol% Y2O3-stabilized TZP is strongly enhanced by alloying with ceria. The ceria content necessary to avoid degrdn. completely, decreases with grain size. The toughness of fully dense Y, Ce-TZP is 7-9 MPa m1/2 for grain sizes down to 0.2 m. No or very little transformation took place during fracturing and no clear variation with grain size was obsd. for the toughness at grain sizes up to 0.8 m. Reversible transformation and crack deflection may explain the obsd. toughness values.

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Microstructure and chemistry of second phases in MgO- and NiO-codoped alumina by analytical transmission electron microscopy. Park, K.; Vasilos, T.; Sung, C. Cent. Advanced Materials Dep. Chem. Nuclear Eng., Univ. Massachusetts, Lowell, MA, USA. Journal of Materials Science Letters (1995), 14(4), 261-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 122:167982 AN 1995:415637 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects MgO-NiO-codoping on microstructure and chem. of 2nd phases, segregated particles and cryst. defects in alumina ceramics were examd. MgO-NiO-codoping contributed significantly to the prepn. of dense fine-grained alumina. It appeared that Ni-Al and Ni-Mg-Al spinels, segregated Ni particles, and K-'' alumina ppts. were formed at triple points or at grain boundaries, because the concns. of the MgO and NiO dopants were higher than their solid solubilities. In particular, the codopants formed a Ni-Mg-Al spinel as well as a Ni-Al spinel, because Mg2+ and Ni2+ were partitioned in the cation position of the spinel structure.

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Compositions and chemical bonding in ceramics by quantitative electron energy-loss spectrometry. Bentley, J.; Horton, L. L.; McHargue, C. J.; McKernan, S.; Carter, C. B.; Revcolevschi, A.; Tanaka, S.; Davis, R. F. Metals and Ceramics Div.r., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1994), 332(Determining Nanoscale Physical Properties of Materials by Microscopy and Spectroscopy), 385-90. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:87360 AN 1995:266442 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. electron energy-loss spectrometry was applied to a range of ceramic materials at a spatial resoln. of <5 nm. Anal. of Fe L23 white lines indicates a low-spin state with a charge transfer of .apprx.1.5 electrons/atom onto the Fe atoms implanted into (amorphized) silicon carbide. Gradients of 2-5% in the Co:O stoichiometry were measured across 100-nm-thick Co3O4 layers in an oxidized directionally solidified CoO-ZrO2 eutectic, with the highest O levels near the ZrO2. The energy-loss near-edge structures were dramatically different for the two cobalt oxides; those for Co3O4 have been incorrectly ascribed to CoO in the published literature. Kinetically stabilized solid soly. occurred in an AlN-SiC film grown by low-temp. mol. beam epitaxy (MBE) on (6H)-SiC, and no detectable interdiffusion occurred in couples of MBE-grown AlN on SiC following annealing at up to 1750C. In diffusion couples of polycryst. AlN on SiC, interfacial 8H Sialon (aluminum silicon oxynitride) and pockets of Si3N4-rich '-Sialon in the SiC were detected.

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Chemically bonded ceramics as an alternative to high temperature composite processing. Gulgun, Mehmet A.; Johnson, Bradley R.; Kriven, Waltraud M. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA. Materials Research Society Symposium Proceedings (1994), 346(Better Ceramics through Chemistry VI), 511-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 122:15230 AN 1995:174876 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Processing of multi-phase ceramic composite materials using chem. bonded ceramics as a binding agent appears to be a promising route for fabricating complex-shaped structures. In a zirconia-calcium aluminate ceramic matrix composite, the hydraulic property of fine, monocalcium aluminate (CaAl2O4) powders was used to prep. strong prefired bodies. The changes in the phys. characteristics of the composite during the conversion from a chem. bonded compact into a sintered composite were studied using thermogravimetric analyses (TGA), X-ray diffraction and SEM. The d. and the hardness of the chem. bonded and sintered composite were measured.

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Assessing delayed neurotoxicity in rodents after nerve gas exposure. Husain, K.; Pant, S. C.; Vijayaraghavan, R.; Singh, Ram. Defence Research and Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(2), 161-4. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:294553 AN 1994:694553 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Delayed neurotoxicity of an organophosphorus nerve gas, Sarin (a chem. warfare agent) following repeated inhalation exposure in rats and mice, was studied by behavioral, biochem. and histopathol. analyses. Rats exposed to Sarin aerosols (12.5 mg/m3 for 20 min) daily for ten days did not exhibit any clin. sign of delayed neurotoxicity. Neurotoxic esterase (NTE) activity in the brain, spinal cord and platelets was significantly inhibited, but the inhibition was below the threshold. Histopathol. examn. of spinal cord did not show any axonal degeneration. Mice exposed to Sarin aerosols (5 mg/m3 for 20 min) daily for ten days developed mild ataxia and muscular weakness of the hind limb on 14th day after the start of exposure. NTE activity was significantly inhibited in brain, spinal cord and platelets. Histopathol. of spinal cord showed focal axonal degeneration. Acetyl-choline esterase activity in the platelets of both the animals was significantly inhibited. The authors conclude that mice are sensitive to delayed neurotoxicity induced by repeated exposure to Sarin whereas rats are insensitive.

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Clean-up of chemical warfare agents on soils using simple washing or chemical treatment processes. Amos, Denys; Leake, Brian. DSTO, Aeronautical and Maritime Research Laboratory, P.O. Box 4331, Melbourne, Victoria, Australia. Journal of Hazardous Materials (1994), 39(1), 107-17. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:262645 AN 1994:662645 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Several simple processes have been studied for the destruction of chem. agents, Soman and Mustard, on soils. A double wash or an extended single wash with water was effective in removing Mustard and Soman from soil; addn. of either anionic or cationic surfactant did not improve removal efficiency. Soils with higher org. carbon content were more difficult to decontaminate. The most effective chem. process for the removal of Mustard was treatment with hypochlorite; treatment with Na2CO3 or NaOH were almost as effective as hypochlorite in cleaning Mustard contaminated soil. Soman was removed most effectively by treatment with Na2CO3. Overall the most efficient process for the destruction of both Mustard and Soman was treatment with Na2CO3 soln.

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Liquid phase sintering, electrical conductivity, and chemical stability of lanthanum chromite doped with calcium and nickel. Christie, G. M.; Middleton, P. H.; Steele, B. C. H. Dep. Mater., Imperial Coll. Sci., Tech. Med., London, UK. Journal of the European Ceramic Society (1994), 14(2), 163-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:236480 AN 1994:636480 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The substitution of 10 mol% nickel for chromium in calcium-doped lanthanum chromite has been shown to promote rapid densification of the compd. at low temps. in air by the form of a transient liq. phase. Liqs. were generated via the decompn. of CaCrO4 second phase material present in calcined powders. During elec. cond. measurements at 1000C, severe microstructural degrdn. occurred at atms. of H2 and CO2. The processes leading to chem. degrdn. are attributed to the pptn. of Ni from the (La,Ca)(Cr,Ni)O3 solid soln. and to the decompn. of small amts. of residual CaCrO4 which remains at grain boundaries and triple points after sintering. DTA studies on CaCrO4 in CO2 and H2 atms. suggested that the degrdn. due to CaCrO4 decompn. was primarily a result of the reaction of CaO with CO2 to form CaCO3. The presence of H2 gas is thought to catalyze this reaction via the formation of large amt. of CaO during the decompn. of CaCrO4. Degrdn. is more severe in atms. contg. a mixt. of CO2 and H2 gases than in either gas on its own.

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Photochemical degradation of a toxic organophosphorus analog (PMSF) in microemulsion media. Yang, Yun; Donegan, Sheila; Patel, Ramesh C.; Ward, Anthony J. I. Center for Advanced Materials Processing, Clarkson University, Potsdam, NY, USA. Chemosphere (1994), 28(11), 1967-76. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 121:217331 AN 1994:617331 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A study has been made of the photodegrdn. of an analog, phenylmethylsulfonyl fluoride (PMSF), of a toxic chem. warfare agent. The agent was solubilized in a water-in-oil surfactant stabilized microemulsion system comprising sodium dodecyl sulfate, pentanol and water. Loss of the parent PMSF mol. upon exposure of the system to UV irradn. was monitored by 19F NMR spectroscopy. Consideration of the changes in the chem. shifts, splittings in conjunction with GC/Mass spectroscopy data strongly suggest the degrdn. leads to partial fluorination of pentanol. Anal. of peak areas also indicates the formation of volatile degrdn. products such as HF. The addn. of TiO2 or hydroquinone to the system did not appreciably change the overall amts. of degrdn. The results are interpreted in terms of the possible radical based reaction pathways and show that such a microemulsion medium to have significant potential as a vehicle for effecting such a degrdn. process.

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Comparative evaluation of high protein against normal protein diet in combination with carbamates against organophosphorus intoxication in rats. Chatterjee, A.K.; Sikder, Nirmala; Sikder, A.K. Defence Research & Development Establishment, Gwalior, India. Defence Science Journal (1994), 44(1), 11-14. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 121:197892 AN 1994:597892 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The relative efficacy of an isocaloric high protein diet (HPD) contg. 59 per cent protein, in comparison to a conventional diet contg. 21 per cent protein, as applied in the alleviation of toxicity of diisopropyl phosphorofluoridate (DFP) and Me iso-Pr phosphonofluoridate (sarin), has been reported. In combination with well-known prophylactics like carbamates and cholinolytics like atropine against nerve gas toxicity, HPD appears to be superior to the conventional diet as studied by survival time measurements. Apart from carbamates, atropine and mecamylamine, HPD may be treated as an addnl. prophylactic agent to guard against the toxicity of DFP and sarin, which are being used as war chems.

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The surface chemistry of silicon nitride powder in the presence of dissolved ions. Hackley, V. A.; Malghan, S. G. Ceram. Div., Natl. Inst. Standards and Technol., Gaithersburg, MD, USA. Journal of Materials Science (1994), 29(17), 4420-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 121:185440 AN 1994:585440 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Colloidal processing of silicon nitride (Si3N4) powders depends largely on the control of reactions at the solid-soln. interface. The role of dissolved ions in the surface chem. of Si3N4 powders has been investigated, and the implications of these results for the effects of impurities, contaminants and additives in processing are discussed. The interaction of ions at the solid-soln. interface was characterized by particle electrokinetic behavior detd. from electroacoustic measurements in moderately concd. suspensions. Ions were classified according to chem. similarity and surface specificity. Specific adsorption was inferred from the movement of the isoelec. point relative to the endemic "native" value. Most simple univalent electrolytes behaved indifferently towards the Si3N4 surface, with the exception of fluoride which specifically adsorbed and may have formed a strong complex with surface silicon sites. The alk.-earth cations exhibited a similar weak specificity. In the presence of hydrolyzable transition metal cations, powder surface chem. was controlled by the adsorption of hydroxy metal complexes and by the soly. of a surface-pptd. metal hydroxide phase. Oxo anions, such as sulfate and carbonate, adsorbed specifically on the Si3N4 surface, but the interactions were weaker than previously obsd. on metal oxide surfaces.

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X-ray photoelectron spectroscopy of uv laser irradiated sapphire and alumina. Pedraza, A. J.; Park, J. W.; Meyer, H. M., III; Braski, D. N. Dep. Materials Science Engineering, Univ. Tennessee, Knoxville, TN, USA. Journal of Materials Research (1994), 9(9), 2251-7. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 121:162453 AN 1994:562453 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

XPS was performed in as-received, thermally annealed, and laser-irradiated sapphire and alumina specimens to study the effects of the different treatments on surface chem. and properties. Laser irradiations with a 308 nm wavelength laser were performed in air and in a reducing atm. consisting of a mixt. of Ar and 4% hydrogen. The at. percentages of carbon, aluminum, and oxygen were measured in all the specimens. Particular attention was paid to the percentages of oxygen in the oxide and in a hydroxyl state. The XPS analyses clearly established that a very thin film of metallic aluminum is formed on the surface of both alumina and sapphire substrates when they are irradiated under a reducing atm. However, the film is discontinuous because it is elec. insulating. Substrates irradiated in air have metallic aluminum only for fluences below 0.4 J/cm2. The valence band photoemission spectra of as-received, annealed, and laser-irradiated specimens were measured. In irradiated specimens, the width of the valence band spectra was found to decrease by .apprx.10%. One possible cause of this decrease is the generation of point defects during laser irradn. Electroless copper deposition occurs on sapphire and alumina substrates if their surface has been activated by laser irradn. The time required for copper deposition was monitored by measuring the elec. resistivity in the irradiated area while the substrates were immersed in an electroless bath. The kinetics of deposition on laser-activated substrates and the XPS results show that the presence of metallic aluminum accelerates the deposition process. However, the presence of aluminum is not the sole reason for laser activation in alumina. Very strong metal-ceramic bonding is produced after thermal annealing of samples having preirradiated substrates. This result is explained in terms of the excess oxygen that is present at the ceramic surface after irradn.

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X-ray absorption spectroscopy study of the local structure and the chemical state of yttrium in polycrystalline -alumina. Loudjani, M. K.; Cortes, R. Lab. Metallurgie Structurale, CNRS, Orsay, Fr. Journal of the European Ceramic Society (1994), 14(1), 67-75. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:162396 AN 1994:562396 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. state and local structure around the yttrium ion in doped polycryst. -alumina (0.03  mol% Y2O3  1) system was examd. by extended x-ray absorption fine structure (EXAFS) measurements for yttrium K-edge energy. In the case of highly doped alumina samples (0.1 and 1 mol% Y2O3) most of the yttrium is pptd. as a Y3Al5O12 phase, whereas in the dil. doped alumina sample (0.03 mol% Y2O3) yttrium is in solid soln., being located on the octahedral aluminum sites. The yttrium ion size, comparatively greater than that of the aluminum ion, induces locally a significant distortion of the oxygen ion lattice. This effect creates point defects in the nearest neighbor shell of the yttrium: vacancy (Vo..) and interstitial (Oi'') oxygen point defects.

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Constitution of the -alumina phase in chemically produced mullite precursors. Schneider, H.; Voll, D.; Saruhan, B.; Schmucker, M. Inst. Mater. Res., German Aerosp. Res. Establ., Cologne, Germany. Journal of the European Ceramic Society (1993), 13(5), 441-8. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 121:89568 AN 1994:489568 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The temp. development of type II mullite precursor powders have been studied in the temp. range of 150C (as-received) and 1150C. X-ray diffraction measurements, IR and 29Si and 27Al NMR spectroscopy and anal. transmission electron microscopy have been performed on the heat-treated precursors. The investigations had the aim of contributing to the frequently discussed question, whether Si is incorporated into the -alumina spinel being formed as a transient phase in type II mullite precursors. The as-received precursors consist of relatively large spherical particles ( 05 m) of noncryst. SiO2 and of much finer-grained agglomerates of pseudo-boehmite crystals (-AlO(OH),  20 nm), which are embedded in a SiO2 matrix. Above 350C, pseudo-boehmite transforms to spinel-type alumina (-Al2O3). During this transformation, all Si existing in the SiO2 matrix of the pseudoboehmite agglomerates is incorporated into -Al2O3 corresponding to a SiO2 content of 12 mol% at 500C. Up to 750C, the SiO2 content of the -alumina remains const. but above this temp. it gradually rises and reaches a max. amt. of 18 mol% at 1150C. A marginal decompn. of the spherical non-cryst. SiO2 particles may be the sources to provide diffusion of Si species into the -alumina during a temp. increase above 750C. It is most likely that Si species diffuse into the -alumina crystals along the crystallite boundaries. The diffusion process and Si incorporation are facilitated with the temp. increase.

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Quantitative analysis of Si3N4 microstructure response on interface chemistry. Meissner, E.; Unger, S.; Kleebe, H.-J.; Ziegler, G. Univ. Bayreuth, Bayreuth, Germany. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 471-5. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:89560 AN 1994:489560 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Quant. microstructure anal. was performed on gas-pressure sintered Si3N4 materials (SSN) by employing an image processing system. Variations in grain-diam. distribution and aspect-ratio distribution with changing additive compn. and annealing time, resp., were investigated. Clear evidence was found that both interface compn. and post-sintering anneal can strongly affect the matrix grain morphol. For the Y2O3-doped material, extended annealing time supported the formation of Si3N4 grains with increased diam. and length via Ostwald ripening. Moreover, the aspect-ratio distribution was shifted to higher values indicating anisotropic grain growth. The addn. of Al2O3 + ZrO2, compared to SSN doped with Y2O3, resulted in a finer microstructure with still high aspect ratios. This chem. effect is closely related to the viscosity of the liqs. at processing temps. Furthermore, ZrO2 addn. results in a more pronounced transgranular fracture mode, while Y2O3-contg. SSN predominantly revealed intergranular fracture. The influence of annealing time and interface chem. on both microstructure evolution and resulting fracture toughness is discussed.

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Surface chemical interactions of Si3N4 with polyelectrolyte deflocculants. Hackley, V.A.; Premachandran, R.; Malghan, S.G. Mater. Sci. Eng. Lab., Natl. Inst. Stand. Technol., Gaithersburg, MD, USA. Key Engineering Materials (1994), 89-91(Silicon Nitride 93), 679-82. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 121:41008 AN 1994:441008 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interaction of org. polyelectrolyte deflocculants at the Si3N4 solid-soln. interface was investigated using electroacoustic measurements, polymer adsorption and particle size distribution anal. One cationic and two anionic polymers were studied: quaternized poly(diamine epoxychlorohydrin), ammonium poly(methacrylate) and poly(acrylic acid), resp. Electrostatic interactions are emphasized as a function of pH, concn. and mol. wt.

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Metabolite pharmacokinetics of soman, sarin and GF in rats and biological monitoring of exposure to toxic organophosphorus agents. Shih, Ming L.; McMonagle, Joseph D.; Dolzine, Theodore W.; Gresham, Vincent C. US Army Med. Res. Inst. Chem. Def., Aberdeen Proving Ground, MD, USA. Journal of Applied Toxicology (1994), 14(3), 195-9. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 121:28848 AN 1994:428848 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This study reports on the pharmacokinetics of the elimination of the metabolites of three toxic organophosphorus compds. (soman, sarin and GF). Urine, blood and lung tissue were collected from rats dosed s.c. at 75 g kg-1. Urinary excretion of the metabolite was the major elimination route for these three compds. The major differences among them were primarily the extent and rate of excretion. The hydrolyzed form, alkylmethylphosphonic acid, was the single major metabolite formed and excreted in urine by a non-saturable mechanism. Nearly total recoveries of the given doses for sarin and GF in metabolite form were obtained from the urine. The terminal elimination half-lives in urine were 3.7  0.1 and 9.9  0.8 h for sarin and GF, resp. Soman metabolite showed a biphasic elimination curve with terminal half-lives of 18.5  2.7 and 3.6  2.2 h. Soman was excreted at a slower rate with a recovery of only 62%. Lung was the major organ of accumulation for soman. In blood the toxic agents were concd. more in red blood cells than in plasma. The acid metabolites can serve as a better chem. marker for monitoring organophosphorus exposure in humans via their higher concn. and longer half-life in urine than the parent compds.

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Movement of chemical warfare agent simulants through porous media. Jenkins, R. A.; Buchanan, M. V.; Merriweather, R.; Ilgner, R. H.; Gayle, T. M.; Watson, A. P. Analytical Chemistry Division, Oak Ridge National Laboratory, Building 4500S, MS-6120, P.O. Box 2008, Oak Ridge, TN, USA. Journal of Hazardous Materials (1994), 37(2), 303-25. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 121:16666 AN 1994:416666 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A measurement protocol is documented and data are presented to characterize the permeation of chem. warfare agent simulants through the porous construction materials brick, cinder block, gypsum wall board, and wood. These data will be used to develop guidelines for access ("reentry") to potentially contaminated properties if nerve or vesicant agents are released during any phase of the US Department of the Army's Chem. Stockpile Disposal Program. A novel permeation cell design allowed sampling of air vols. adjacent to the spiked face, breakthrough face, and lateral face of each test medium at two temps. Simulant movement through wood is nearly always in the direction of the wood grain. Two-dimensional breakthrough was obsd. in brick and gypsum wall board. The sulfur mustard simulant broke through all test media in less than 60 min; nerve agent simulant breakthrough required several hours. Surface decontamination of wood with high-test hypochlorite is 95% effective.

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Pharmacology of organophosphates. Koelle, George B. Med. Sch., Univ. Pennsylvania, Philadelphia, PA, USA. Journal of Applied Toxicology (1994), 14(2), 105-9. CODEN: JJATDK ISSN: 0260-437X. Journal; General Review written in English. CAN 121:2654 AN 1994:402654 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 8 refs. The cholinergic nerve fibers, which employ acetylcholine (ACh) as a neurohumoral transmitter, and the results of their activation are listed. The reactions between the enzyme acetylcholinesterase (AChE), its natural substrate, ACh, and the various types of inhibitors are described. The limited therapeutic uses of the anticholinesterase (anti-ChE) agents are considered. The toxicol. effects encountered when the anti-ChE agents are employed as insecticides or as chem. warfare (CW) agents are discussed. Certain anti-ChE agents produce also a delayed neurotoxic effect which is apparently unrelated to the inhibition of AChE.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson, Barry W.; Kawakami, Thomas G.; Cone, Norman; Henderson, John D.; Rosenblatt, Leon S.; Goldman, Marvin; Dacre, Jack C. Inst. Toxicol., Univ. California, Davis, CA, USA. Toxicology (1994), 86(1-2), 1-12. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 120:263586 AN 1994:263586 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (tabun, phosphoramidocyanidic acid, dimethyl-, Et ester) as part of a program to demilitarize chem. warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but not in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only 3 of the 5 assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Effect of chemically added zirconia and yttria mechanical properties of zirconia-dispersed alumina. Ranjbar, Khalil; Rao, Boddapati T.; Mohan, Tallapragada R. Rama; Harendranath, Chilkunda S. Dep. Metall. Eng., Indian Inst. Technol., Bombay, India. American Ceramic Society Bulletin (1994), 73(2), 63-6. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 120:171374 AN 1994:171374 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Alumina powders dispersed with monoclinic, tetragonal, and cubic zirconia were prepd. by evapg. a colloidal dispersion of alumina powders in solns. contg. zirconium and yttrium salts. The dried and calcined powders were compacted, sintered, and characterized. The results demonstrated a clear toughening effect by the zirconia on the alumina ceramics. The alumina contg. 20-wt%-yttria-stabilized tetragonal zirconia had the max. toughness.

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Chemical vapor infiltration of silicon carbide with microwave heating. [Erratum to document cited in CA119(2):13852e]. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(12), 3251. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 120:141948 AN 1994:141948 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The errors were not reflected in the abstr. or the index entries.

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Chemical compatibility between silicon-based and titanium-based ceramics. Wang, L.; Wada, H. Dep. Mater. Sci. Eng., Univ. Michigan, Ann Arbor, MI, USA. Journal of Materials Synthesis and Processing (1993), 1(3), 181-93. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:277176 AN 1993:677176 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. compatibility between Si-based ceramics and Ti-based ceramics was studied to establish guidelines for the processing of related composites. Phase stabilities were calcd. for the Si-Ti-B-C, Si-Ti-B-N, and Si-Ti-B-C-N systems as a function of B activity and N pressure or C activity. SiC is compatible with TiC, TiN, or TiB2, depending on the range of these parameters. Si3N4 and TiN appear to be compatible in a certain range of N2 pressure and C activity, but Si3N4 and pure TiC will not coexist. However, the fact that TiC and TiN can form a solid soln., TiC1-xNx, suggests that Si3N4 and TiC1-xNx may be obsd. in the presence of both C and N2. The Si3N4 + TiB2 2-phase region is limited in such a narrow range of N2 pressure and B activity that processing and application of TiB2/Si3N4 composites would be very difficult. High-temp. solid-state expts. were carried out with selected systems to verify phase stability diagrams. The results of reactions were in agreement with the thermodn. prediction. A high-d. TiB2/SiC composite was prepd. as an example of the application of phase stability diagrams.

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Thermal and acid catalyzed conversion of organic phosphorus compounds. De Lijser, H. J. P.; Mulder, P.; Louw, R. Cent. Chem. Environ., Leiden Univ., Leiden, Neth. Chemosphere (1993), 27(5), 773-8. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:233159 AN 1993:633159 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The org. P compds. tri-Bu and tri-Me phosphate (I and II, resp.), tri-Me phosphite (III), and di-Me phosphonate (IV) were thermolyzed using a plug flow (gas-phase) reactor. I and II proved to be sensitive to acid (wall) catalysis and can be fully degraded at temps. of .mchlt.400. III can isomerize to II and IV. In contrast, IV requires a temp. of >750 for complete conversion; admixed with II it counteracts the smooth acid-mediated degrdn. of II. Unlike real thermolysis at elevated temps., preferably in a reducing atm. of hydrogen, mere acid catalysis is not generally applicable for effectively destroying a variety of ecotoxic org. P compds.

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Preparation of uniformly calcia-doped zirconia. Hill, J.; Newhouse, M.; Xue, J.; Dieckmann, R. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Journal of Materials Synthesis and Processing (1993), 1(2), 101-9. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:232072 AN 1993:632072 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The prepn. of dense samples of high-purity zirconia doped with varying, small contents of CaO has been explored by means of traditional ceramic techniques with sintering and hot-pressing as well as a chem. soln. method. First, CaO-doped samples were prepd. by traditional ceramic methods. Their homogeneities were checked by SEM with x-ray mapping. CaO-dopant distribution was not uniform in all samples with overall CaO contents below 7 mol%. The difficulty in prepg. uniformly doped zirconia with small CaO contents led to exploration of the use of chem. soln. processing techniques. When exploring such techniques, the products of each process step were characterized by x-ray diffraction and electron microprobe anal. The characterization results enabled identification of a processing route which is suitable for prepg. dense, high-purity zirconia uniformly doped with CaO at low concns.

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A model for the isothermal isobaric chemical vapor infiltration (CVI) in a straight cylindrical pore. Application to the CVI of silicon carbide. Fedou, R.; Langlais, F.; Naslain, R. Lab. Compos. Thermostruct., CNRS, Pessac, Fr. Journal of Materials Synthesis and Processing (1993), 1(2), 61-74. CODEN: JMSPEI ISSN: 1064-7562. Journal written in English. CAN 119:208796 AN 1993:608796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A previously described modeling of the chem. vapor infiltration (CVI) process in a straight cylindrical pore is applied to the deposition of SiC-based ceramics from MeSiCl3-H2 in the case of a 1st-order kinetic law with respect to MeSiCl3. The model gives concns. and deposit thickness profiles along the pore at any stage of the densification and, particularly, at the end of the process when the pore becomes sealed. The infiltration homogeneity is predicted to be improved by decreasing the aspect ratio of the pore and the CVI temp. and, under conditions of Fick diffusion, by decreasing the total pressure and the pore diam. The model is validated by the good fit between the deposit thickness profiles along the pore calcd. after adjustment of the kinetic data and exptl. profiles for a 34-m straight pore.

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Nicalon-fiber-reinforced silicon carbide composites via polymer solution infiltration and chemical vapor infiltration. Kim, Young Wook; Song, Jin Soo; Park, Sang Whan; Lee, Juen Gunn. Struct. Ceram. Lab., Korea Inst. Sci. Technol., Seoul, S. Korea. Journal of Materials Science (1993), 28(14), 3866-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 119:186895 AN 1993:586895 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A new, faster process was developed for the fabrication of Nicalon-fiber-reinforced SiC composites by combining polymer soln. infiltration (PSI) and chem. vapor infiltration (CVI). The process led to the near-net-shape fabrication of fiber-reinforced ceramic-matrix composites and reduced infiltration time. Typical flexural strength and fracture toughness of these composites were 296 MPa and 10.9 MPa.m1/2 at room temp. and 252 MPa and 9.6 MPa.m1/2 at 1000, resp. The composites exhibited load-carrying capability after crack initiation.

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The effect of glass chemistry on the microstructure and properties of self reinforced silicon nitride. Pyzik, Aleksander J.; Carroll, Daniel F.; Hwang, C. James. Adv. Ceram. Lab., Dow Chem. Co., Midland, MI, USA. Materials Research Society Symposium Proceedings (1993), 287(Silicon Nitride Ceramics), 411-16. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:186804 AN 1993:586804 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The advantage of self-reinforced silicon nitride is the in-situ control of the microstructure. This control is provided in large degree by the chem. of glassy phase which can be adjusted to tailor the morphol. of silicon nitride grains as well as the matrix-reinforcement interface. The presence of high aspect ratio silicon nitride grains is necessary but not sufficient condition to produce materials with optimum properties. For max. flexure strength and fracture toughness, an optimized glass matrix is required.

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Microwave assisted chemical vapor infiltration. Devlin, D. J.; Currier, R. P.; Barbero, R. S.; Espinoza, B. F.; Elliott, N. Mater. Sci. Technol. Div., Los Alamos Natl. Lab., Los Alamos, NM, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 245-50. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144800 AN 1993:544800 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A microwave-assisted process for prepn. of continuous fiber-reinforced ceramic-matrix composites is described. A simple app. combining a chem.-vapor-infiltration reactor with a conventional 700-W multimode oven is described. Microwave-induced inverted thermal gradients are exploited with the ultimate goal of reducing processing times on complex shapes. Thermal gradients in stacks of SiC (Nicalon) cloths have been measured using optical thermometry. Initial results on the inside-out deposition of SiC via decompn. of MeSiCl3 in H are presented. Several key processing issues are identified and discussed.

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Chemical vapor deposition of multiphase boron-carbon-silicon ceramics. Golda, E. Michael; Gallois, B. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 167-72. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144796 AN 1993:544796 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Specific compns. of boron-carbon-silicon ceramics exhibit improved abrasive wear and good thermal shock resistance, but require bulk sintering at temps. in excess of 2100K. The formation of such phases by CVD was examd. at 1073-1573K. Methyltrichlorosilane (CH3SiCl3), boron trichloride, and methane were chosen as reactant gases, with hydrogen as a carrier gas and diluent. The coatings were deposited in a computer-controlled, hot-wall reactor at a pressure of 33 MPa. Below 1473K the coatings were amorphous. At higher temps. nonequil. reactions controlled the deposition process. The most common coating consisted of a silicon carbide matrix and a silicon boride, SiB6, dispersed phase. Multiphase coatings of B + B4C + SiB6 and SiC + SiB6 + SiB14 were also deposited by controlling the partial pressure of methane and boron trichloride. Non-equil. thermodn. anal. qual. predicted the exptl. deposited multiphase coatings.

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CVD of silicon nitride plate from trichlorosilane-ammonia-hydrogen mixtures. Lennartz, J. W.; Dowell, M. B. Union Carbide Coat. Serv. Corp., Parma, OH, USA. Materials Research Society Symposium Proceedings (1992), 250(Chemical Vapor Deposition of Refractory Metals and Ceramics II), 161-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:144795 AN 1993:544795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Preferred conditions for deposition of thick -Si3N4 plate from HSiCl3-NH3-H2 on the vertical surfaces of a low-pressure, hot-wall CVD reactor were identified by means of a designed expt. The design included temp. range 1300-1500, pressures 0.5-2.0 torr, and residence times 0.01-1.0 s. The vertical deposition surfaces received a viscous, laminar flow of well mixed, thermally equilibrated reactants. Plates 0.05-0.5 mm thick were produced on multiple vertical substrates 350 cm2 in area at deposition rates 5-70 m/h. Plates 0.5-4.0 mm thick were produced on horizontal substrates at deposition rates of 60-120 m/h. When NH3 flows in stoichiometric excess, deposition rates on vertical surfaces increase approx. linearly with the flow rate of HSiCl3 but depend little on temp., as would be expected if the reaction proceeds under mass transport control with product depletion. Multiple correlation analyses show that thickness variations in the deposit are reduced by increasing the temp. and decreasing the gas residence time. CVD silicon nitride plate produced under the optimized conditions exhibits theor. d. and is free of pores and cracks. It exhibits a columnar morphol. in which the <222> and <101> crystallog. directions are oriented preferentially normal to a surface, which consists of well-defined trigonal facets 10-50 m across. Crystallite sizes detd. by x-ray line broadening range from 0.06-1.0 m. This CVD plate is gray and contains approx. 0.5 C and 0.5 wt.% 0 as principal impurities.

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Unequivocal evidence. Black, Robin M.; Pearson, Graham S. Chem. Biol. Def. Estab., Porton/Down/Salisbury Wiltshire, UK. Chemistry in Britain (1993), 29(7), 584-5, 587. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 119:123791 AN 1993:523791 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The anal. of chem. warfare agent, Sarin, in the Kurdush village of Birjinni, Iraq, was discussed.

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Bioanalysis of organophosphate nerve agents in soil samples. Sawyer, T. W.; Weiss, M. T. Biomed. Def. Sect., Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Chemosphere (1993), 26(11), 2023-9. CODEN: CMSHAF ISSN: 0045-6535. Journal written in English. CAN 119:94477 AN 1993:494477 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Four soil samples that may have been spiked with chem. warfare (CW) agents and their degrdn. products were received by Defense Research Establishment Suffield as part of a multinational round-robin exercise designed to evaluate lab. methodologies for the chem. detection of CW agents in soil. After chem. anal. revealed that VX (Et S-2-diisopropyl aminoethyl methylphosphorothiolate) was the CW agent "spike", the samples were also bioassayed for their VX content by assessing their anticholinesterase activities in primary chick embryo neuron cultures. Bioassay quantitation of VX contamination in the soil samples was in good agreement with the actual spike levels and generally better than the chem. anal. results. Sequential bioassay of the samples over a two week period showed that the VX content was rapidly degraded with time. This assay complements std. chem. anal. techniques for the detection and verification of organophosphate warfare agent use.

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The effect of trace element segregation to iron/sapphire interfaces. Pope, D. P.; Smith, M. A. Dep. Mater. Sci., Univ. Pennsylvania, Philadelphia, PA, USA. Materials Research Society Symposium Proceedings (1992), 238(Structure and Properties of Interfaces in Materials), 427-32. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 119:77041 AN 1993:477041 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The effects of segregation of tramp impurities such as sulfur on metal/ceramic bonding is discussed. Microstructural and chem. information is given for the Fe/sapphire interface. The segregation behavior of the interface is evaluated between 500-800. The interfacial structure is important to the segregation behavior. A possible link between the segregation of sulfur and interface void formation is presented.

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Chemical vapor infiltration of silicon carbide with microwave heating. Morell, Jose I.; Economou, Demetre J.; Amundson, Neal R. Dep. Chem. Eng., Univ. Houston, Houston, TX, USA. Journal of Materials Research (1993), 8(5), 1057-67. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 119:13852 AN 1993:413852 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is presented to describe the interaction between transport/reaction processes and the evolution of porosity in chem. vapor infiltration with microwave heating (MCVI). The anal. includes a set of partial differential equations describing the spatiotemporal variation of gaseous species concn., composite temp., porosity, and stress. Maxwell's equations were used to det. the distribution of power dissipated inside the composite. The deposition of silicon carbide was selected as a model chem. system to explore the general features of MCVI. MCVI can provide a favorable temp. distribution in the composite yielding an inside-out deposition pattern, thereby preventing entrapment of accessible porosity. For this temp. profile, tensile stresses develop at the outer regions and compressive stresses are found in the composite core. For a given system there exists a min. value of the coeff. for heat transfer from the composite surface, h, below which accessible porosity is trapped within the composite. Similarly, there exists a max. value of the incident microwave energy flux, I0, above which accessible porosity is trapped within the composite. I0 and h can be optimized for a given preform to achieve complete densification with min. processing time. Using the technique of pulsed-power, the processing time can be reduced even further without compromising d. uniformity. Power dissipation profiles in the composite depend strongly on preform thickness, microwave frequency, and relative loss factor.

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Permeation measurements of chemical agent simulants through protective clothing materials. Pal, Tarasankar; Griffin, Guy D.; Miller, Gordon H.; Watson, Annetta P.; Daugherty, Mary Lou; Vo Dinh Tuan. Health Saf. Res. Dev., Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Hazardous Materials (1993), 33(1), 123-41. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 118:239880 AN 1993:239880 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A method was developed to study the permeation of chem. warfare (CW) agent simulants through chem. protective clothing (CPC) materials. The exptl. results characterize some com. available CPC materials. Thirteen different CPC materials having widely differing compns. were chosen to study the permeation of 4 different liq. CW simulants (di-Me methylphosphonate, diisopropyl methylphosphonate, malathion, and Bu2S) through these CPC materials at 25. This permeation study involved a newly developed anal. technique employing room temp. fluorescence quenching of an indicator compd., phenanthrene, on filter paper. Various exptl. factors such as breakthrough time, rate of permeation, and uptake were investigated. On the basis of breakthrough time, the 13 CPC materials could be divided into 3 groups: most resistant, moderately resistant, and least resistant. Materials in the most resistant category exhibited no permeation by any of the simulants for 24 h. Breakthrough occurred in the least resistant materials in generally less than an hour, and sometimes as soon as a few minutes.

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Interfacial structure of chemical vapor infiltration carbon fiber/silicon carbide composite. Araki, H.; Noda, T.; Abe, F.; Suzuki, H. Tsukuba Lab., Natl. Res. Inst. Met., Tsukuba, Japan. Journal of Materials Science Letters (1992), 11(23), 1582-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:44089 AN 1993:44089 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure at the interface in carbon fiber-SiC matrix composites prepd. by chem. vapor infiltration from EtSiCl3 was examd., and the infiltration reaction is discussed. A graphite layer formed on the carbon fiber and the SiC-SiC interface as a result of thermal decompn. of silane gas before SiC infiltration. This graphite layer, of .apprx.500 nm thickness, is assumed to assist in the crystal growth of SiC, leading to structural stability of the composites.

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Comparative evaluation of carbamates as prophylactic agents against organophosphate intoxication in rats. Chatterjee, A. K. Def. Res. Dev. Establ., Gwalior, UK. Defence Science Journal (1992), 42(2), 85-7. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 118:34070 AN 1993:34070 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

This paper investigates the effects of two well-known carbamates, physostigmine and pyridostigmine, against organophosphorus compd. and nerve gas toxicity. Physostigmine pretreatment for 30 min enhanced the survival time of rats against DFP intoxication, whereas it did not have any effect with sarin poisoning. However, pyridostigmine pretreatment did not produce any significant effect on survival time either against DFP or sarin intoxication. Treatment with atropine along with carbamates further enhanced significantly the survival time against DFP poisoning.

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On the influence of chemical processing in the crystallization behavior of zirconium titanate materials. Navio, J. A.; Macias, M.; Sanchez-Soto, P. J. Inst. Cienc. Mater., Univ. Sevilla, Seville, Spain. Journal of Materials Science Letters (1992), 11(23), 1570-2. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 118:26385 AN 1993:26385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The crystn. phenomena of ZrTiO4 powders prepd. from various gel precursors was related to the chem. processing. Correlation of data from the literature and further expt. indicated that the presence of H2O2 in the chem. processing of the amorphous precursors plays a key role in controlling the crystn. temp. The crystn. temp. can be as low as 640.

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Effect of dopants on the sintering behavior and stability of tetragonal zirconia ceramics. Theunissen, G. S. A. M.; Winnubst, A. J. A.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1992), 9(4), 251-63. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:54278 AN 1992:454278 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microstructure development during nonisothermal and isothermal sintering was studied for tetragonal zirconia ceramics (TZP) contg. various amts. of Y, Ce, and Ti. Smaller grain sizes were obtained when Ce-TZP was doped with Y. This could be attributed to segregation of Y to the grain boundaries, thus causing an impurity drag. With increasing temp., the grain growth rate in the Ce-TZP samples increased which could be attributed to the absence of a dragging force. The slow grain growth at low temp. in the Ce-TZP samples could be attributed to the slow diffusion kinetics of the diffusing species (trivalent and tetravalent Ce). The crit. grain size for retainment of the tetragonal phase at room temp. is larger in the Y,Ce-TZP systems compared to the Y-TZP and Ce-TZP systems. The chem. stability increased by doping Y-TZP with Ce or Ti.

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Free radical-mediated lung response to the monofunctional sulfur mustard butyl 2-chloroethyl sulfide after subcutaneous injection. Elsayed, Nabil M.; Omaye, Stanley T.; Klain, George J.; Korte, Don W., Jr. Letterman Army Inst. Res., Presidio of San Francisco, CA, USA. Toxicology (1992), 72(2), 153-65. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 117:42116 AN 1992:442116 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The authors postulated that vesicants may cause free radical-mediated oxidative stress distal to the site of exposure. To test this postulate in the lung, the authors injected 3 groups of 5-mo-old, male, athymic, nude mice, weighing 30-35 g with a single s.c. dose (5 L/mouse) of Bu 2-chloroethyl sulfide (BCS). Total lung wt. was not altered after treatment, but the wet/dry wt. ratio decreased 18% and Hb content increased 50 and 36% at 1 and 24 h, resp. The activity of glucose 6-phosphate dehydrogenase increased significantly, 40% at 1 and 24 h and 84% at 48 h and that of glutathione S-transferases was 60%. Lipid peroxidn. (estd. by the thiobarbituric acid test) and total protein content increased 3-fold and 2-fold, at 1 and 24 h, resp. Total and oxidized glutathione contents were significantly elevated, 38% at 1 h and 64% at 24 h for the former and 45% at 24 h and 56% at 48 h for the latter. Because these changes are consistent with the cellular response to oxidative stress, it is concluded that BCS injected s.c. can cause changes in the lung possibly via a free radical-mediated mechanism.

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Effects of liquid environments on zirconia-toughened alumina. Part I. Chemical stability. Thompson, I.; Rawlings, R. D. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1992), 27(10), 2823-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:32321 AN 1992:432321 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The structural changes which occur in zirconia-toughened alumina when aged in a range of liq. environments (distd. water, ethylene glycol soln., and HCl at room temp., and ethylene glycol soln. at 80) are described. The changes were monitored by x-ray diffraction, surface anal., anal. of the aging solns., and microstructural observations. HCl induced significant proportions of the zirconia particles in the zirconia-toughened alumina to transform from the tetragonal to the monoclinic crystal structure. This transformation was accompanied by microcracking which eventually led to macrocracking after long periods of aging. The transformation is a consequence of the leaching of the yttrium from the zirconia particles, thereby reducing their stability.

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Binder chemistry, adhesion and structure of interfaces in thick-film metalized aluminum nitride substrates. Newberg, C. E.; Risbud, S. H. IBM Corp., East Fishkill, NY, USA. Journal of Materials Science (1992), 27(10), 2670-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 117:13161 AN 1992:413161 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Aluminum nitride substrates from 3 sources were metalized by std. thick-film processing using gold conductor pastes, Pd-Ag paste, and a ruthenium oxide resistor paste. Screen-printed pastes were fired in a typical 3-zone furnace to obtain metalized AlN substrates. Interfacial reaction zones were studied by microscopic (optical and SEM) and electron beam microprobe anal. techniques. The elements in the binder materials in thick-film pastes form amorphous phases at the interface which influence the adhesion of thick films to the AlN substrate. The lack of certain elements (Cd, Zn, Ca) in the binder of the gold thick-film paste led to weaker adhesion and severe degrdn. of the thick-film adhesion during thermal cycling.

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Preparation and characterization of a dispersion toughened ceramic for thermomechanical uses (ZTA). Part I. Material preparation. Characterization of microstructure. Leriche, A.; Moortgat, G.; Cambier, F.; Homerin, P.; Thevenot, F.; Orange, G.; Fantozzi, G. CRIBC, Mons, Belg. Journal of the European Ceramic Society (1992), 9(3), 169-76. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 117:13037 AN 1992:413037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Zirconia-toughened alumina (ZTA) materials contg. increasing amts. of zirconia (5-45 vol.%) and yttria (0-3 mol% zirconia) were prepd. from com. ceramic powders by different techniques of homogenization, shaping, and sintering. The powder mixts. were homogenized by a chem. method (addn. of dispersing agents at fixed pH), by a mech. method (attrition milling) and by combining the methods. The materials were formed and sintered by shaping by isostatic pressing or slip casting, followed by pressureless sintering, and by hot uniaxial pressing. The phys., crystallog. and microstructural properties of the materials prepd. following these different techniques are compared. The combined chem. and mech. dispersion method leads to the fabrication of dense composites presenting a fine and homogeneous zirconia dispersion required for effective toughening of the alumina matrix. The addn. of 3 mol% of yttria allows maintenance of a high tetragonal zirconia content because of a chem. stabilization of tetragonal zirconia and of a decrease of zirconia grain size. As the hot-pressing technique impedes the grain coarsening, the hot-pressed materials present the finest microstructure mainly for the compns. with <20 vol.% zirconia. The zirconia and alumina grain size vary from 0.5 to 0.9 m and from 0.9 to 1.6 m, resp., following the compn. Pressureless sintered materials also present a fine microstructure with submicron zirconia grains (0.6 m-0.9 m) and micron size alumina grains (1.0-1.9 m). These ZTA materials present all the microstructural characteristics necessary to obtain high mech. performances. The addn. of 3 mol% of yttria allows an increase of the zirconia content (45 vol.%) without a decrease of the relative tetragonal zirconia ratio occurring.

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Adsorption and decomposition of organophosphorus compounds on nanoscale metal oxide particles. In situ GC-MS studies of pulsed microreactions over magnesium oxide. Li, Yong Xi; Koper, Olga; Atteya, Maher; Klabunde, Kenneth J. Dep. Chem., Kansas State Univ., Manhattan, KS, USA. Chemistry of Materials (1992), 4(2), 323-30. CODEN: CMATEX ISSN: 0897-4756. Journal written in English. CAN 116:200414 AN 1992:200414 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Using an in-situ pulse reactor-GC-mass spectrometric system, the thermal decompn. of organophosphorus compds. (as models of nerve agents) were compared with their destructive absorption on high-surface-area MgO. Dramatically lower temps. are required when MgO is present. Volatile products evolved were HCO2H, water, alcs., and alkenes. At higher temps., CO, CH4, and water predominated. The P residues remained completely immobilized. The addn. of water enhanced the facility of MgO to destroy these compds., and, in fact, water pulses were found to partially regenerate a spent MgO bed. Using 18O labeling, some aspects of the reaction mechanisms were clarified and in particular showed that O scrambling occurred. Surface OH and MgO groups transferred O in the formation of HCO2H, and the surface mobility and reactivity of absorbed groups were high. The substantial capacity of high-surface-area MgO for destruction and immobilization of such toxic substances makes it attractive for air purifn. schemes, as well as solid reagents for destruction and immobilization of bulk quantities of hazardous P compds. or organohalides.

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-(N,N-Dialkylamino)ethyl arylthiosulfonates: new simulants for O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate. Davis, Franklin A.; Ray, Jayanta K.; Kasperowicz, Steve; Przeslawski, Robert M.; Durst, H. Dupont. Dep. Chem., Drexel Univ., Philadelphia, PA, USA. Journal of Organic Chemistry (1992), 57(9), 2594-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 116:193819 AN 1992:193819 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Certain S-[2-(dialkylamino)]ethyl benzenesulfonothioates 4-XC6H4SO2SCH2CH2NR2 (I; X = Me, F; R = Me2CH) were prepd. as simulants for O-Et S-[(diisopropylamino)ethyl]methylphosphonothioate (VX) a chem. warfare nerve agent. I are useful simulants for the hydrolysis or oxidn. chem. of VX.

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Dissolution of sintered silicon nitride bulk specimens for elemental analysis. Homeier, E. H.; Bradley, S. A.; Karasek, K. R. UOP, Des Plaines, IL, USA. Journal of Materials Science (1992), 27(5), 1231-4. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:179524 AN 1992:179524 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Heating bulk, sintered Si3N4 samples in an aq. HF-HCl mixt. decomps. the Si3N4. Subsequent addn. of H2SO4 and volatilization of fluorides enables total dissoln. of the bulk specimens for anal. The elemental compns. that were detd. by inductively coupled plasma at. emission and at. absorption spectrometries agreed with the nominal sample compn. and confirmed analyses performed by scanning TEM. Neutron activation detns. on the same samples are not believed to be as accurate as the spectrometric detns. Furthermore, the precision of the neutron activation measurements were less satisfactory, esp. for key elements such as Y.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy, Paul M.; Hansen, Arnold S.; Hand, Brian T.; Boulet, Camille A. Def. Res. Establ. Suffield, Ralston, AB, Can. Toxicology (1992), 72(1), 99-105. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 116:168061 AN 1992:168061 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a std. set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI 6 > HLoe 7 > pyrimidoxine. Hloe 7 was very effective against tabun poisoning while HI 6 and pyrimidoxime were of moderate value. Against GF, HI 6 and HLoe 7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLoe-7 to a slightly lesser degree. The other oximes lacked the effects against one or more of the organophosphates.

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Chemical vapor deposition of copper via disproportionation of hexafluoroacetylacetonato(1,5-cyclooctadiene)copper(I), (hfac)Cu(1,5-COD). Jain, A.; Chi, K. M.; Hampden-Smith, M. J.; Kodas, T. T.; Farr, J. D.; Paffett, M. F. Dep. Chem. Eng., Univ. New Mexico, Albuquerque, NM, USA. Journal of Materials Research (1992), 7(2), 261-4. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 116:111299 AN 1992:111299 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hot- and cold-wall chem.-vapor deposition (CVD) using the volatile Cu(I) compd. (hfac)Cu(1,5-COD), where hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate and 1,5-COD = 1,5-cyclooctadiene, as a precursor was carried out in hot-wall and warm-wall, lamp-heated reactors using SiO2 substrates that were patterned with Pt or W at 120-250. Deposition was obsd. onto Pt, W, and SiO2 over this temp. range at rates of 3750 .ANG./min to give Cu films that contained no impurities detectable by AES and with resistivities of 1.9-5.7 ohm-cm. The volatile byproducts formed during deposition were 1,5-COD and Cu(hfac)2 and a mass balance was consistent with the quant. disproportionation reaction: 2(hfac)Cu(1,5-COD)  Cu + Cu(hfac)2 + 2(1,5-COD). The measured activation energy for this CVD reaction was 26(2) kcal/mol. The absence of selectivity for metal surfaces in the presence of SiO2 is in contrast to CVD results for the related compds. (-diketonate)Cu(PMe3) where -diketonate = hfac, 1,1,1-trifluoroacetylacetonate, and acetylacetonate (acac).

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer, Thomas W.; Weiss, M. Tracy; D'Agostino, Paul A.; Provost, Lionel R.; Hancock, James R. Def. Res. Establ. Suffield, Medicine Hat, AB, Can. Journal of Applied Toxicology (1992), 12(1), 1-6. CODEN: JJATDK ISSN: 0260-437X. Journal written in English. CAN 116:105057 AN 1992:105057 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chem. warfare activity was subjected to chem. anal. and bioassay. Sarin and several related compds. were confirmed in the soil by capillary column gas chromatog.-mass spectrometry (GC-MS); however, the binding of these compds. to the soil hindered quantitation. The chem. results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified stds. in chick embryo neuron cultures, a reasonable agreement was found between the chem. and bioassay semiquant. ests. of sarin content in the soil ext. Furthermore, the in-vitro system appears to offer a sensitive technique for the estn. of sarin remaining bound to the soil following solvent extn. as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Pharmacological effects of oximes: how relevant are they?. van Helden H P; Busker R W; Melchers B P; Bruijnzeel P L Department of Pharmacology, TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1996), 70(12), 779-86. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW); (REVIEW, TUTORIAL) written in English. PubMed ID 8911635 AN 97068325 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The increased international concern about the threat of military and terroristic use of nerve agents, prompted us to critically consider the expected value of the currently available oxime treatment of nerve agent poisoning. Although oximes have been designed to reactivate the inhibited acetylcholinesterase (AChE), clinical experience has indicated that they are not always very effective as reactivators and at this very moment none of them can be regarded as a broad-spectrum antidote. In spite of this drawback, oximes are worth further investigating, since recent data derived from soman or tabun lethally intoxicated non-human primates suggest that the oxime HI-6 may exert a pharmacological effect that is not related to reactivation of inhibited AChE, but still leads to survival. This pharmacological effect causes recovery of neuronal transmission in the respiratory centres of the brain and recovery of neuromuscular transmission in the diaphragm. These findings have stimulated research to reveal the pharmacological basis of these effects in order to find drugs which could be more effective and less toxic than the available oximes. Since cholinergic drugs were able to exert this effect, a new concept for further treatment is suggested: maintenance of neuronal transmission in spite of continued AChE-inhibition by pharmacological manipulation of the cholinergic receptor. This should renew interest in the diverse pharmacological effects of oximes to reach a more effective treatment in the future.

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Evaluation of the therapeutic efficacy of some antimuscarinics against soman in vivo. Lau W M; Lewis K J; Dawson R M Aeronautical and Maritime Research Laboratory, Defence Science and Technology Organization, Department of Defence, Melbourne, Victoria, Australia Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 423-30. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889794 AN 97044723 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The therapeutic efficacy of tacrine, atropine and glycopyrrolate alone or in combination with the oxime HI-6 against soman was evaluated in anaesthetized rats. Arterial blood pressure, heart rate, respiratory frequency and body temperature were monitored in vivo. Blood cholinesterases were determined after each drug or soman challenge. At the lowest concentration tested (2.5 mg kg-1), tacrine was effective in improving the survivability of the rat by a factor of 2.6 (protection ratio), whereas the protection by atropine or glycopyrrolate was either insignificant or only marginally effective (protection ratio ranged from 1.0 to 1.9). In combination with HI-6, atropine increased the ratio to 4.6. In contrast, tacrine with HI-6 failed to improve the efficacy of the regimen, while glycopyrrolate plus HI-6 showed only slight improvement. The four physiological parameters monitored were relatively constant during the time course of the experiment in both the control and those with drug therapy. The more noticeable changes occurred toward the end of the experiment when sufficient amount of soman was injected to cause lethality. Death of the animal was usually preceded by a surge of arterial blood pressure and heart rate and a decrease in respiratory frequency. These physiological parameters rapidly deteriorated to zero just before the animal died. Blood and plasma cholinesterases were significantly inhibited after the animal received a relatively small dose of soman (20 micrograms kg-1) and were almost completely inactivated after the lethal dose of soman was administered. However, these changes of enzyme activity did not correspond well with the survivability of the rat. The inclusion of HI-6 with the three antimuscarinics appeared to be capable of protecting some cholinesterases against soman.

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Efficacy of ibuprofen and pentoxifylline in the treatment of phosgene-induced acute lung injury. Sciuto A M; Stotts R R; Hurt H H Pathophysiology Division, United States Army Medical Research Institute of Chemical Defense Aberdeen Proving Ground, MD 21010-5425, USA Journal of applied toxicology : JAT (1996 Sep-Oct), 16(5), 381-4. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8889788 AN 97044717 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Phosgene, a highly reactive former warfare gas, is a deep lung irritant which produces adult respiratory distress syndrome (ARDS)-like symptoms following inhalation. Death caused by phosgene involves a latent, 6-24-h, fulminating non-cardiogenic pulmonary edema. The following dose-ranging study was designed to determine the efficacy of a non-steroidal anti-inflammatory drug, ibuprofen (IBU), and a methylxanthine, pentoxifylline (PTX). These drugs were tested singly and in combination to treat phosgene-induced acute lung injury in rats. Ibuprofen, in concentrations of 15-300 mg kg-1 (i.p.), was administered to rats 30 min before and 1 h after the start of whole-body exposure to phosgene (80 mg m-3 for 20 min). Pentoxifylline, 10-120 mg kg-1 (i.p.), was first administered 15 min prior to phosgene exposure and twice more at 45 and 105 min after the start of exposure. Five hours after phosgene inhalation, rats were euthanized, the lungs were removed and wet weight values were determined gravimetrically. Ibuprofen administered alone significantly decreased lung wet weight to body weight ratios compared with controls (P < or = 0.01) whereas PTX, at all doses tested alone, did not. In addition, the decrease in lung wet weight to body weight ratio observed with IBU+PTX could be attributed entirely to the dose of IBU employed. This is the first study to show that pre- and post-treatment with IBU can significantly reduce lung edema in rats exposed to phosgene.

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Subchronic toxicity evaluation of sulfur mustard in rats. Sasser L B; Miller R A; Kalkwarf D R; Cushing J A; Dacre J C Pacific Northwest Laboratory, Richland, WA 99352-0999, USA Journal of applied toxicology : JAT (1996 Jan-Feb), 16(1), 5-13. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8821670 AN 96418885 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Occupational exposure criteria have not been established for sulfur mustard (bis(2-chlorethyl) sulfide), a strong alkylating agent with known mutagenic properties. Seventy-two Sprague-Dawley rats of each sex, 6-7 weeks old, were divided into six groups (12 of each sex per group) and gavaged with 0, 0.003, 0.01, 0.03, 0.1 or 0.3 mg kg-1 sulfur mustard in sesame oil for 5 days a week for 13 weeks. No dose-related mortality was observed. A significant decrease (P > 0.05) in body weight was observed in both sexes of rats only in the 0.3 mg kg-1 group. Hematological evaluations and clinical chemistry measurements found non consistent treatment-related effects at the doses studied. The only treatment-related lesion associated with gavage exposure upon histopathological evaluation was epithelial hyperplasia of the forestomach of both sexes at 0.3 mg kg-1 and of males at 0.1 mg kg-1. The hyperplastic change was minimal and characterized by cellular disorganization of the basilar layer, apparent increase in mitotic activity of the basilar epithelial cells and thickening of the epithelial layer due to the apparent increase in cellularity. The estimated no-observed-effect level (NOEL) for sulfur mustard in this 90-day study was 0.1 mg kg-1 day-1 when administered orally.

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Acute toxicity of cyclohexylmethylphosphonofluoridate (CMPF) in rhesus monkeys: serum biochemical and hematologic changes. Young G D; Koplovitz I U.S. Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA Archives of toxicology (1995), 69(6), 379-83. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7495375 AN 96114840 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Changes in serum biochemical and hematological parameters were studied in 20 male rhesus monkeys following acute poisoning by the organophosphate nerve agent cyclohexylmethylphosphonofluoridate (CMPF or GF). Animals were challenged with 5 x LD50 GF (233 micrograms/kg, IM) following pretreatment with pyridostigmine (0.3-0.7 mg/kg per 24 h) and treated with atropine (0.4 mg/kg, IM) and either 2-PAM (25.7 mg/kg, IM) or H16 (37.8 mg/kg, IM) at the onset of clinical signs or at 1 min after exposure. Muscle fasciculations, tremors, or convulsions occurred in 19 of 20 animals. Serum biochemical and hematologic parameters were analyzed 2 days and 7 days after exposure and compared to pre-exposure baseline values. Significant increases in creatine kinase (CK), lactate dehydrogenase (LD), aspartate transaminase (AST), alanine transaminase (ALT) and potassium ion (K+), associated with damage to striated muscle and metabolic acidosis, occurred in both oxime-treated groups 2 days after exposure. Total protein, albumin, red blood cell (RBC) count, hemoglobin concentration (Hb) and hematocrit (Hct), were decreased in both oxime-treated groups at 7 days. The results demonstrate that animals exposed to a single high dose of GF and treated with standard therapy exhibit changes in serum biochemical and hematological indices directly and indirectly associated with their clinical presentations.

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Production, characterization and application of monoclonal antibodies against the organophosphorus nerve agent Vx. Ci Y X; Zhou Y X; Guo Z Q; Rong K T; Chang W B Department of Chemistry, Peking University, Beijing, China Archives of toxicology (1995), 69(8), 565-7. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8534201 AN 96036122 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Two monoclonal antibodies (Vx-BB8 and Vx-EA11) to the chemical warfare agent Vx were produced and characterized. A competitive inhibition enzyme immunoassay was developed to detect Vx concentrations as low as 3.7 x 10(-7) - 3.7 x 10(-6) mol/l in biological samples. Vx-BB8 400 micrograms given intravenously immediately before 1 x LD95 Vx or 400 micrograms Vx-BB8 intraperitoneally 1.5 h-3 days before 1 x LD95 Vx could protect all the tested mice from death.

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Toxicity of sulphur mustard in adult rat lung organ culture. Sawyer T W; Wilde P E; Rice P; Weiss M T Medical Countermeasures Section, Defence Research Establishment Suffield, Alberta, Canada Toxicology (1995 Jun 26), 100(1-3), 39-49. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 7542806 AN 95350771 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of the chemical warfare agent sulphur mustard, (bis-(2-chloroethyl)sulphide, HD), was examined in adult rat lung organ cultures. Assessment of HD-induced damage by the MTT cytotoxicity assay indicated that the median lethal concentration (LC50) of HD in these cultures was reproducible, and in the microM range. Damage to the lung slices was expressed only after a latent period of 48 h and did not increase significantly with longer expression times. Histopathological examination of HD-treated lung cultures showed that the structural changes in the lung tissue paralleled the toxicity measured biochemically, and were also similar to the damage found in animals and man exposed to HD in vivo. This in vitro model offers a useful tool with which to study the toxicity and mechanism of action of sulphur mustard.

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Toxicity of the combined nerve agents GB/GF in mice: efficacy of atropine and various oximes as antidotes. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Canada Archives of toxicology (1994), 68(1), 64-6. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166607 AN 94219995 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicity of a combination of isopropyl methylphosphonofluoridate (sarin; GB) and cyclohexyl methylphosphonofluoridate (GF) and the efficacy of various oxime reactivators in combination with atropine against the combined GB/GF challenge were evaluated in mice. The 24-h s.c. LD50 of the GB/GF combination was 1.15 mumol/kg (1.10-1.21; 95% confidence limits). Mice administered GB/GF displayed typical signs of nerve agent poisoning such as tremors and convulsions, with death most likely due to anoxia subsequent to respiratory arrest. The GB/GF LD50 value was comparable to the s.c. LD50 of 1.35 and 1.21 mumol/kg for GF and GB in mice, respectively. Combining the two nerve agents did not result in potentiation of the toxicity. In combination with atropine sulfate (17.4 mg/kg, i.p.), which alone did not reduce mortality, the oximes tested, 2-PAM, obidoxime and HI-6, were all effective when administered 5 min before 3 x LD50 dose of GB/GF with 24-h ED50 values of 102.5, 18.22 and 1.96 mumol/kg, respectively. Use of the GB/GF combination does not appear to confer any unique toxicity profile and appears to be easily treated with the standard therapy of a cholinolytic and oxime.

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Toxicokinetics of soman stereoisomers after subcutaneous administration to atropinized guinea pigs. Due A H; Trap H C; Langenberg J P; Benschop H P TNO Prins Maurits Laboratory, Rijswijk, The Netherlands Archives of toxicology (1994), 68(1), 60-3. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8166606 AN 94219994 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The toxicokinetics of the four stereoisomers of the nerve agent C(+/-)P(+/-)-soman were investigated after subcutaneous administration of a 6 LD50 dose (148 micrograms/kg) to anaesthetized, atropinized, and artificially ventilated guinea pigs. Whereas the relatively nontoxic C(+/-)P(+)-isomers were not detected in blood, the highly toxic C(+/-)P(-)-isomers appeared within 1 min in the general circulation and reached maximum levels of 10-15 ng/ml blood within a period of ca. 7 min. In this absorption phase the blood levels of the C(+)P(-)-isomer lag clearly behind those of the C(-)P(-)-isomer. The blood levels of both C(+/-)P(-)-isomers could be mathematically described using non-linear regression by a three-exponential equation, with one exponential term describing the rapid absorption phase and the other two terms describing distribution and elimination. A comparison with the toxicokinetics of the same isomers upon intravenous administration of the same dose shows that the systemic availability upon subcutaneous administration is in the range of 74-83%. Toxicologically relevant concentrations of the C(+/-)P(-)-isomers prevail almost twice as long after subcutaneous than after intravenous administration. From a toxicokinetic point of view, subcutaneous administration of C(+/-)P(+/-)-soman appears not to be a realistic model for the most relevant route of exposure to C(+/-)P(+/-)-soman in case of chemical warfare, i.e. short term respiratory exposure.

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Genotoxicity of the phosphoramidate agent tabun (GA). Wilson B W; Kawakami T G; Cone N; Henderson J D; Rosenblatt L S; Goldman M; Dacre J C Department of Avian Sciences, University of California, Davis 95616-5224 Toxicology (1994 Jan 26), 86(1-2), 1-12. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 8134917 AN 94182225 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Five mutagenicity tests were performed on Agent GA (Tabun, phosphoramidocyanidic acid, dimethyl-, ethyl ester) as part of a program to demilitarize chemical warfare agents. GA was mutagenic in Salmonella spp. assays with S-9 and it was a direct-acting mutagen to mouse lymphoma cells. GA did not promote unscheduled DNA synthesis in rat hepatocytes; it induced sister chromatid exchanges in mouse cells in vitro but in vivo. The conclusion that GA is a weakly acting mutagen is supported by the fact that it was mutagenic in only three of the five assays, and that increases in mutagenicity were often less than 2-fold the controls and occurred near toxic levels.

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Evaluation of the toxicity, pathology, and treatment of cyclohexylmethylphosphonofluoridate (CMPF) poisoning in rhesus monkeys. Koplovitz I; Gresham V C; Dochterman L W; Kaminskis A; Stewart J R US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425 Archives of toxicology (1992), 66(9), 622-8. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1482284 AN 93129117 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Cyclohexylmethylphosphonofluoridate (CMPF) is an organophosphate cholinesterase inhibitor with military significance. The purpose of these studies was 1) to determine the acute toxicity of CMPF in the male rhesus monkey, 2) to evaluate the efficacy of pyridostigmine (PYR) pretreatment plus atropine and oxime (2-PAM or H16) treatment, and 3) to evaluate the pathological consequences of acute poisoning. An i.m. LD50 of CMPF was estimated using an up-and-down dose selection procedure and 12 animals. The 48-h and 7-day LD50 was 46.6 micrograms/kg, i.m. In the protection experiments, pyridostigmine (0.3-0.7 mg/kg/24 h) was administered by surgically implanted osmotic minipumps for 3-12 days resulting in 21-65% inhibition of erythrocyte acetylcholinesterase activity. Animals were challenged with 5 x L50 CMPF (233 micrograms/kg) and treated with atropine (0.4 mg/kg) and either 2-PAM (25.7 mg/kg) or HI6 (37.8 mg/kg) at the onset of signs or 1 min after challenge. Osmotic pumps were removed within 30 min after agent challenge. Pyridostigmine, atropine, and either 2-PAM or H16 were completely effective against CMPF, saving ten of ten animals in each group. In comparison, three of five animals challenged with 5 x LD50 of soman and treated with atropine and 2-PAM survived 7 days. The primary histologic lesions in the acute toxicity group were neuronal degeneration/necrosis and spinal cord hemorrhage. The CMPF treated groups (total of 20 animals) had minimal nervous system changes with no significant lesion difference resulting from the different oxime therapies. The primary non-neural lesions were degenerative cardiomyopathy and skeletal muscle degeneration which occasionally progressed to necrosis and mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)

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Efficacy of various oximes against GF (cyclohexyl methylphosphonofluoridate) poisoning in mice. Clement J G Biomedical Defence Section, Defence Research Establishment Suffield, Ralston, Alta., Canada Archives of toxicology (1992), 66(2), 143-4. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1605730 AN 92296882 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

The efficacy of oxime (HI-6, toxogonin or PAM Cl) therapy against GF (cyclohexyl methylphosphonofluoridate) poisoning was assessed in mice. It was found that the combinations of atropine and either toxogonin or HI-6 were effective therapies against GF poisoning. PAM therapy was ineffective. HI-6 was the only oxime which reactivated GF inhibited acetylcholinesterase. This might explain the reason why the HI-6 treated mice appeared to recover more quickly from the incapacitating effects following GF poisoning.

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Bioassay of organophosphate nerve agents in soil using neuronal tissue cultures. Sawyer T W; Weiss M T; D'Agostino P A; Provost L R; Hancock J R Defence Research Establishment Suffield, Alberta, Canada Journal of applied toxicology : JAT (1992 Feb), 12(1), 1-6. Journal code: 8109495. ISSN:0260-437X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1564246 AN 92226402 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

A soil sample originating from an area of suspected chemical warfare activity was subjected to chemical analysis and bioassay. Sarin and several related compounds were confirmed in the soil by capillary column gas chromatography-mass spectrometry (GC-MS); however, the binding of these compounds to the soil hindered quantitation. The chemical results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified standards in chick embryo neuron cultures, a reasonable agreement was found between the chemical and bioassay semi-quantitative estimates of sarin content in the soil extract. Furthermore, the in vitro system appears to offer a sensitive technique for the estimation of sarin remaining bound to the soil following solvent extraction as well as for an assessment of the potential toxicity of the contaminated soil in vivo.

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Comparison of several oximes against poisoning by soman, tabun and GF. Lundy P M; Hansen A S; Hand B T; Boulet C A Defence Research Establishment Suffield, Ralston, Alberta, Canada Toxicology (1992), 72(1), 99-105. Journal code: 0361055. ISSN:0300-483X. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 1539175 AN 92169690 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

Abstract

Three oximes currently being evaluated for adoption as replacement nerve agent therapy by various countries were compared for therapeutic efficacy against the toxic organophosphate inhibitors soman and tabun under a standard set of conditions. These oximes together with PAM-Cl and toxogonin, were also compared for efficacy against GF, an agent weaponized by Iraq. The order of effectiveness against soman was HI-6 greater than HLo-7 greater than pyrimidoxime. HLo-7 was very effective against tabun poisoning while HI-6 and pyrimidoxime were of moderate value. Against GF, HI-6 and HLo-7 were extremely effective, toxogonin was moderately effective, and PAM-Cl and pyrimidoxime were the least effective. HI-6 provided a high level of protection against all of the agents tested as did HLo-7 to a slightly lesser degree. The other oximes suffered from their lack of effects against one or more of the organophosphates.

[simply RED]

Great!!! (no more comment i found)

Interesting to say:
GD is refered somewhere as soman and in some articles as
the GD 42 like compounds.

[ """"""rg - 42""""" (small symbols) is the cyriclic (bul, rus...) transcription of it. ]

[simply RED]

Great!!! (no more comment i found)

Interesting to say:
GD is refered somewhere as soman and in some articles as
the GD 42 like compounds.

[ """"""rg - 42""""" (small symbols) is the cyriclic (bul, rus...) transcription of it. ]

[simply RED]

Great!!! (no more comment i found)

Interesting to say:
GD is refered somewhere as soman and in some articles as
the GD 42 like compounds.

[ """"""rg - 42""""" (small symbols) is the cyriclic (bul, rus...) transcription of it. ]

[megalomania]

Bibliographic Information

Crystal chemistry and phase manipulation in Synroc. Vance, E. R.; Moricca, S.; Thorogood, G. J.; Lumpkin, G. R. Aust. Nucl. Sci. Technol. Organ., Menai, Australia. Key Engineering Materials (1991), 53-55(Austceram '90), 717-21. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 118:259605 AN 1993:259605 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The modification of the titanate ceramic Synroc was studied in terms of decreasing the unstable perovskite phase content, incorporation of process chems., and incorporation of Al-rich and actinide-rich nuclear wastes. A formulation of alkoxide-derived Al2O3 (7.8), BaO (11.7), CaO (8.3), TiO2 (54.1), and ZrO2 (18.1 wt.%) produced a mixt. of hollandite and zirconolite when sintered at 1200 in air, but .apprx.10 wt.% perovskite formed when hot pressed at 1200. A cor. formulation with 30 wt.% simulated high-level waste substitution for ZrO2 still produced a significant amt. of perovskite. Mg from fuel cladding was predicted to be incorporated in a MgTi2O5 phase which was demonstrated to be compatible with the other Synroc phases. P was incorporated in the alloy phase and as Ca3(PO4)2 at higher loadings. Satisfactory Cs leach rates were obtained when alkoxide-derived Synroc powders were hot pressed at 1400, but not all Al from the waste was incorporated in the Synroc phases at loadings as low as 10 wt.% Al2O3.

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Study of the efficacy of CC-2 and Fuller's earth combination as a decontaminant against sulfur mustard (mustard gas) dermal intoxication in mice. Kumar, Pravin; Sharma, U. S.; Vijayaraghavan, R. Def. Res. and Dev. Establ., Gwalior, India. Defence Science Journal (1991), 41(4), 363-6. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 116:189222 AN 1992:189222 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Decontamination efficacy of Fuller's earth and CC-2 independently; and in different combinations was evaluated against toxicity of sulfur mustard applied percutaneously on mice. Max. protection was obtained with fuller's earth and CC-2 in a combination of 80:20 (wt./wt.).

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Thermochemical analysis of chemical processes relevant to the stability and processing of silicon carbide-reinforced silicon nitride composites. Misra, A. K. NASA Lewis Res. Cent., Sverdrup Technol., Inc., Cleveland, OH, USA. Journal of Materials Science (1991), 26(24), 6591-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:65309 AN 1992:65309 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. processes relevant to the stability and processing of SiC-reinforced Si3N4 composites are examd. from a thermochem. point of view. The thermodn. stability of various interfaces, such as SiC-Si3N4, SiC-Si3N4-Si2ON2, and SiC-Si3N4-SiO2, is examd. as a function of temp. The temps. above which these interfaces become unstable are calcd., and the degrdn. of SiC during the processing of the composite is examd. The processing routes considered in this study include the reaction-bonded Si3N4 process, as well as pressure-assisted sintering processes in the presence of suitable sintering additives.

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Microstructural and chemical effects in alumina implanted with iron at 77 K and annealed in oxidizing or reducing atmospheres. McHargue, C. J.; Sklad, P. S.; White, C. W.; McCallum, J. C.; Perez, A.; Marest, G. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Materials Research (1991), 6(10), 2160-77. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 115:238068 AN 1991:638068 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Implantation of Fe (160 keV) into -Al2O3 at 77 K produces an amorphous surface layer for fluences 1016-1017 Fe ions/cm2. Measurements of short-range order were made by extended energy loss fine structure anal. The structure of amorphous Al2O3 produced by implantation of Fe at 77 K exhibits short-range order that differs from that produced by stoichiometric (Al + O) implants. This difference is manifested by changes in the Al-O near-neighbor bond length. The local environments of implanted Fe were detd. from conversion electron Moessbauer spectroscopy. The Fe resides in several different local environments consistent with the electronic states of Fe2+, Fe4+, and Fe0. The relative amt. of each environment depends on the concn. (fluence) of the implanted Fe ions. Regrowth of the amorphous zone during annealing occurs in the sequence amorphous Al2O3  -Al2O3  -Al2O3. The kinetics of regrowth and phase sepn. vary with implanted fluence with annealing atm. The higher the concn. of implanted Fe, the slower the formation of Fe-Al2O3 ppt. phases in oxidizing atmospheres and -Fe ppts. in reducing atmospheres.

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Microstructural and chemical effects in alumina implanted with iron at room temperature and annealed in oxidizing or reducing atmospheres. McHargue, C. J.; Sklad, P. S.; White, C. W.; Farlow, G. C.; Perez, A.; Marest, G. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Materials Research (1991), 6(10), 2145-59. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 115:238067 AN 1991:638067 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

RBS-ion channeling, TEM, and conversion electron Moessbauer spectroscopy were used to det. the structure of -Al2O3 implanted with Fe at room temp. Changes produced by post-implantation annealing in oxidizing and reducing atmospheres were followed using the same methods. Implantation of 160 keV Fe at room temp. produces a damaged but cryst. microstructure for fluences 1  1017 Fe ions/cm2. The Fe resides in a variety of local environments: 3 Fe2+ components, 1 Fe0 component, and 2 Fe4+ components. The relative amt. of each component varies with implantation fluence. Only the Fe0 component seems to be assocd. with 2nd-phase formation. In this case, 2 nm diam. -Fe particles were detected by TEM studies. Recovery of implantation-induced disorder in the Al- and O-sublattices occurs in 2 stages for annealing in O and in 1 continuous stage for H-annealing. The end state for Fe is Fe3+ for O anneals and Fe0 for H anneals. The pptd. phases obsd. are those to be expected from the equil. phase diagrams.

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Grain boundaries in high thermal conductivity aluminum nitride. McKernan, Stuart; Norton, M. Grant; Carter, C. Barry. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Materials Research Society Symposium Proceedings (1991), 203(Electron. Packag. Mater. Sci. 5), 229-34. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 115:237865 AN 1991:637865 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The benefits of AlN as a substrate material for the electronics packaging industry appear to be limited by the deleterious effects of boundaries in the polycryst. material. Some observations on different types of boundary in AlN using several complementary techniques are reported. Energy dispersive x-ray spectroscopy anal. of grain boundaries shows that there is O at the grain boundaries, in agreement with previous work. No variation in the grain-boundary chem. was detected in the proximity of Y2O3-rich particles. The apparent increase in the O peak is probably due to an increased width of the oxide layer close to the triple junction.

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Modified CVD of nanoscale structures in and EVD of thin layers on porous ceramic membranes. De Haart, L. G. J.; Lin, Y. S.; De Vries, K. J.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1991), 8(1), 59-70. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 115:213226 AN 1991:613226 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Expts. on the modified CVD and the electrochem. vapor deposition (EVD) of Y2O3-stabilized ZrO2 on porous substrates are reported. In the CVD stage, deposition occurs in a small (<20 m) region at the edge of the substrate, very likely leading to pore narrowing. This result illustrates the feasibility of the CVD technique for the modification of ceramic membranes to the (sub)nanometer scale. Film growth in the EVD stage is controlled by the in-pore diffusion of the O source reactant for short (<5 h) deposition times. The Y2O3/ZrO2 ratio in the deposited film is detd. by the ratio present in the vapor phase. Very thin (2 m) films can be deposited, which have a potential application in solid oxide fuel cells.

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Thermal stability of ceramic fiber in a CVI-processed silicon carbide matrix composite. Lin, W.; Yang, J. M. Dep. Mater. Sci. Eng., Univ. California, Los Angeles, CA, USA. Journal of Materials Science (1991), 26(15), 4116-22. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:140940 AN 1991:540940 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The thermal stability of the HPZ (Si-C-O-N system from hydridopolysilazane polymer precursor) fiber in a chem. vapor infiltration (CVI)-processed SiC matrix composite was studied. The mech. properties and fracture behavior of the untreated and SiC-coated fibers after thermal exposure at different temps. and atmospheres were characterized. At <1000, the strength degrdn. is negligible. However, severe degrdn. occurs at >1000 due to the evolution of CO, SiO, and other gaseous species. Also, pyrolytic C coating is needed to tailor the interfacial bond strength in the HPZ/SiC composites.

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Reaction chemistry at joined interfaces between silicon nitride and aluminum. Ning, X. S.; Okamoto, T.; Miyamoto, Y.; Koreeda, A.; Suganuma, K. Inst. Sci. Ind. Res., Osaka Univ., Osaka, Japan. Journal of Materials Science (1991), 26(15), 4142-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:118946 AN 1991:518946 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Joined interfaces of hot-isostatically pressed, additive-free Si3N4 ceramic/Al braze bonded at 1073 K for 18 ks or at 1473 K for 1.8 ks in a vacuum of 1.3 mPa and of -Si3N4 powder/Al powder interfaces bonded at 1073 K for 1.8 ks or 18 ks in the same vacuum were examd. by anal. TEM and x-ray diffraction. Mullite, some small crystals, and '-Sialon were detected at the interface of the ceramic/Al braze bonded at the low temp. and 15R AlN-polytype Sialon, '-Sialon, AlN, mullite, and SiO2-Al2O3 noncryst. material were detected at interfaces bonded at 1473 K. At the powder interface, AlN, and Si were also detected besides '-Sialon and the SiO2-Al2O3 noncryst. material, even though the bonding was conducted at the low temp. The interfacial reactions of the joints were affected not only by the bonding temp., but also by the oxide formed at the interface before bonding occurred.

Bibliographic Information

Thermo-mechanical properties and oxidation resistance of zirconia CVI matrix composites: 2 - thermal properties and oxidation resistance. Minet, J.; Langlais, F.; Naslain, R. Lab. Chim. Solide, Univ. Bordeaux, Talence, Fr. Journal of the European Ceramic Society (1991), 7(5), 283-93. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 115:118899 AN 1991:518899 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

ZrO2 matrix composites, prepd. by chem. vapor infiltration (CVI) from preforms (Al2O3 or C fibers) having a 2 (or pseudo-3-) dimensional character, were studied from a thermal behavior and resistance to oxidn. standpoint. The ZrO2 vol. fraction and residual porosity were within the 0.30-0.75 and 0.10-0.25 ranges, resp. The expts. were carried out 1500. Thermal expansion is low and almost reversible for the C-ZrO2 composites whereas it is more significant and partly irreversible for the Al2O3-ZrO2 composites. The Al2O3-ZrO2 composites exhibit an insulating character at >1000, comparable to that of sintered ZrO2, whereas the C-ZrO2 composites have a thermal cond. equal to that of sintered Al2O3 at >1000. The resistance to oxidn. by air is acceptable at moderate temps. and for short exposures. Under more severe conditions, damaging phenomena occur (i.e., grain growth, oxidn. of the C preform or BN interphase) which are detrimental to the mech. behavior.

Bibliographic Information

Efficacy of an oximate-based skin decontaminant against organophosphate nerve agents determined in vivo and in vitro. Sawyer, Thomas W.; Parker, Deborah; Thomas, Norleen; Weiss, M. Tracy; Bide, Richard W. Def. Res. Establ., Suffield/Ralston, AB, Can. Toxicology (1991), 67(3), 267-77. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 115:87007 AN 1991:487007 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Recent Canadian research efforts have been directed towards the development of a reactive skin decontaminant (RSD) lotion active against classical nerve agents and mustard. The formulation presently under study consists of a 1.25 m soln. of potassium 2,3-butanedione monoximate (KBDO) in polyethylene glycol Me ether 550. Although this formulation has shown good efficacy, concern has been expressed as to the potential toxicity of the reaction products of KBDO and organophosphate (OP) nerve agents. This report describes the high efficacy of this lotion in inactivating OPs as measured by the systemic toxicity of the OP/RSD mixts. in rats. In addn., primary cultures of chick embryo neurons were also used to test the efficacy of the RSD. By relating the anticholinesterase activity in these cultures of the OP/RSD mixt. to that of pure OP stds., a sensitive measure of the value of the RSD in inactivating tabun, sarin, soman and VX was obtained. Expts. with all 4 nerve agents in this in vitro system provided a good correlation with the in vivo data, and also indicated that the inactivation process was time- and agent-dependent and also related to the ratio of OP to RSD.

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Refractory ceramic foams: a novel, new high-temperature structure. Sherman, Andrew J.; Tuffias, Robert H.; Kaplan, Richard B. Ultramet Corp., Pacoima, CA, USA. American Ceramic Society Bulletin (1991), 70(6), 1025-7, 1029. CODEN: ACSBA7 ISSN: 0002-7812. Journal; General Review written in English. CAN 115:33992 AN 1991:433992 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 6 refs. Chem.-vapor infiltration (CVI) enables prepn. of the porous cellular structure. The fabrication of such a structure begins with the pyrolysis of a resin-impregnated thermosetting foam to obtain a reticulated C foam skeleton. The foam ligaments can then be coated with a variety of materials (metals, oxides, nitrides, carbides, borides, silicides, etc.), either singly or as hybrid, layered, alloyed, or graded structures. During this process, 10-1000 m of the desired material(s) are deposited onto the foam ligaments by CVI. The thermomech. properties of the resultant structure are dominated by the properties of the deposit, becoming independent of the c properties at very small material loadings. With precise control over the variables available, it is possible to obtain the simultaneous optimization of stiffness, strength, thermal cond., overall wt. and environmental resistance.

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Chemical control in precipitation of spherical zirconia particles. Lerot, L.; Legrand, F.; De Bruycker, P. Lab. Cent. Rech., Solvay et Cie, Brussels, Belg. Journal of Materials Science (1991), 26(9), 2353-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:13964 AN 1991:413964 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Monodisperse spherical ZrO2 particles were pptd. by hydrolysis of alc. solns. of Zr alkoxides in the presence of long-chain carboxylic acids. The particle size can be finely tuned from 0.1 to 2.5 m by controlling the concn. of Zr alkoxide, the water/Zr ratio, the nature of alc. from EtOH to BuOH, the nature of carboxylic acid from caproic to oleic acid, and its concn. The relations among the induction time before nucleation, the particle size, and all the above parameters are tentatively explained on the grounds of the soly. of the carboxy-alkoxide derivs. and their tendency to form micelles. Calcination of pptd. powders at 300-600 produces mixts. of varying compn. from cubic to monoclinic phases of small crystallite sizes and brings out the loss of surface area and org. content. Different conditions of drying powders lead to variously ordered microstructures.

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Stability of zirconia-ceria-yttria ceramics in hostile environments. Leach, C.; Khan, N. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1991), 26(8), 2026-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 114:212576 AN 1991:212576 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The phase chem., elec. cond. in air and forming gas, and stability in warm humid environments of ZrO2-CeO2-Y2O3 ceramics are described. The compns. studied lie between 12 mol% CeO2/88 mol% ZrO2 and 3 mol% Y2O3/97 mol% ZrO2 and fall within the tetragonal phase field of this ternary system. At 700, reducing atms. affected only the cond. of the end-member CeO2-ZrO2 ceramic, having no effect on the ternary compns. Compns. contg. >10 mol% CeO2 were more stable to stabilizer loss in water vapor at 132 than those contg. <10 mol% CeO2.

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A mathematical model for chemical vapor infiltration with microwave heating and external cooling. Gupta, Deepak; Evans, James W. Lawrence Berkeley Lab., Univ. California, Berkeley, CA, USA. Journal of Materials Research (1991), 6(4), 810-18. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 114:191000 AN 1991:191000 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model was used to compute temp. profiles in ceramic preforms that are heated by microwaves. The temp. profiles were then input to a 2nd part of the model describing chem. vapor infiltration of the preform, that is the diffusion of gaseous reactants, heterogeneous reaction, and evolution of the pore structure. Equations were solved numerically for parameters corresponding to the infiltration of SiC preforms by pyrolysis of MeSiCl3. While based on some simplifications, the model leads to the conclusion that infiltration proceeds more rapidly, and to a greater extent, with microwave heating/external cooling than in isothermal infiltration. The model suggests that infiltration might be optimized by manipulation of microwave power and external cooling. The computed extent of infiltration is very sensitive to the initial pore size.

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Preparation of silicon carbide powders by chemical-vapor deposition of the dichlorodimethylsilane-hydrogen system. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(11), 4614-21. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:236356 AN 1990:636356 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC powders were prepd. by chem.-vapor deposition using (Me)2SiCl2 and H2 as source gases at 1273-1673 K. Various kinds of SiC powders such as amorphous powder, -type single-phase powder, and composite powder were obtained. The composite powders contained free Si and/or free C phases of a few nanometers in diam. All the particles obsd. were spherical in shape and uniform in size. The particle size increased from 45 to 130 nm with decreasing reaction temp. and gas flow rate and with increasing reactant concn. The lattice parameter of the -SiC particles decreased with increasing reaction temp. All the lattice parameters were larger than those of bulk -SiC.

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Thermodynamics for the preparation of silicon carbide-carbon nanocomposites by chemical-vapor deposition. Wang, Y.; Sasaki, M.; Goto, T.; Hirai, T. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(11), 4607-13. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:236355 AN 1990:636355 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-C nanocomposites covering every possible combination of C and SiC were prepd. by chem.-vapor deposition. The specific compns. of the deposits were controlled by changing the Si/C molar ratio in the source gases at deposition temps. 1673-1873 K and total gas pressures 6.7-40 kPa using the SiCl4-C3H8-H2 system. The prediction, based on the thermodn. calcn. on compn., morphol. and deposition rate, was compared with exptl. results. The optimal deposition conditions predicted by the calcns. were nearly in agreement with the exptl. results.

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Thermomechanical properties and oxidation resistance of zirconia CVI-matrix composites: 1 - mechanical behavior. Minet, J.; Langlais, F.; Quenisset, J. M.; Naslain, R. Lab. Chim. Solide, Univ. Bordeaux, Talence, Fr. Journal of the European Ceramic Society (1989), 5(6), 341-56. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 113:216698 AN 1990:616698 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mech. behavior of various ZrO2-based fibrous composites was studied at ambient and high temps. The composites were prepd. by ZrO2-chem.-vapor infiltration (CVI) densification, from preforms made of Al2O3 or C fibers consolidated with a small amt. of Al2O3, pyrocarbon or hexagonal BN. When loaded under compression at room temp., 2-dimensional (2-D) C-C/ZrO2 composites exhibit mech. behavior similar to that already reported for the related 2-D-C-C/SiC, 2-D-C-C/B4C, 2-D-C-C/TiC or 2-D-C-C/BN materials with: a linear elastic domain, a damaging domain prior to failure, and an anisotropy which decreases as ZrO2 vol. fraction is raised. Under 3-point bending, the Al2O3-ZrO2 composites behave, at room temp., in a nonbrittle manner when the preform has been consolidated by BN, with crack deviation and pull-out phenomena. The variations of the stiffness and strength vs. ZrO2 vol. fraction obey exponential laws at room temp. Finally, the Al2O3-ZrO2 composites keep their strength and rigidity .ltorsim.1000 under an atm. of Ar/H.

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Low-temperature MOCVD of silicon-based ceramic films. Du, Honghua; Bae, Yongwoong; Gallois, Bernard; Gonsalves, Kenneth E. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 331-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196275 AN 1990:596275 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A liq. methylsilazane compd., [MeSiHNH]n, was used, with H2, NH3, and a 60%/40% NH3/H2 mixt., to deposit Si-based ceramic films in a metalorg. chem.-vapor-deposition (MOCVD) reactor at 873-1073 K. Characterization of the films by ellipsometry and FTIR and Auger electron spectrometry showed that the methylsilazane was pyrolyzed to form Si carbonitride in H2 and Si3N4 in both NH3 and NH3/H2, with the incorporation of appreciable amts. of O. The deposition rate increased and the activation energy decreased in order from NH3-, NH3/H2-, and H2-[MeSiHNH]n gas mixts. The temp. dependence of the structural d. of the films increased in the same order.

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Modeling transport, reaction, and pore structure evolution during densification of cellular or fibrous structures. Sotirchos, Stratis V.; Tomadakis, Manolis M. Dep. Chem. Eng., Univ. Rochester, Rochester, NY, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 73-8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196263 AN 1990:596263 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is developed to describe mass transport, reaction, and structure evolution during densification of porous media of initially fibrous or cellular structure. The use of Monte Carlo simulation procedures for detg. the variation of the local (av.) structural properties of the porous structure and of the effective diffusion coeffs. in the porous medium with the porosity is also discussed, and results are presented for Knudsen diffusion in cellular or fibrous media. The model is used to theor. study the transient behavior of the densification process during prepn. of SiC/SiC ceramic matrix composites by chem. vapor infiltration of porous preforms. Particular emphasis is placed on the investigation of the effects of pressure pulsing on the d. gradients in the densifying structure.

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Analytical simulation of an improved CVI [chemical vapor infiltration] process for forming highly densified ceramic composites. Tai, Nyan Hwa; Chou, Tsu Wei. Cent. Compos. Mater., Univ. Delaware, Newark, DE, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 61-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196261 AN 1990:596261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A model for chem.-vapor infiltration (CVI) under pressure and temp. gradients is applied to the study of deposition of SiC from the pyrolysis of MeSiCl3 within a 3-dimensional (3-D) woven fibrous preform. The model considers the infiltration of reactants into a preform with temp. gradients by applying a pressure gradient between the vapor inlet and outlet; it also takes into account the variation in concn. of the vapor precursor. A quasi-steady-state approach was adopted to stimulate the matrix deposition in a 3-D unit cell. The d. distribution, consolidation profile, and total fabrication period were theor. predicted.

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Formation of novel sintered composites by high-pressure crystallization of amorphous ceramics. Onodera, Akifumi; Takahashi, Norikazu; Yoshihara, Haruyuki; Nakae, Hiroyuki; Matsunami, Yukio; Hirai, Toshio. Fac. Eng. Sci., Osaka Univ., Toyonaka, Japan. Journal of Materials Science (1990), 25(9), 4157-61. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:176879 AN 1990:576879 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A combination of chem.-vapor deposition (CVD) and high-pressure (HP) sintering methods were used to prep. the zincblende form of BN (z-BN)-based ceramic composites. The CVD method provides amorphous B-N-X (X = Al, Si, or Ti). The HP method renders the amorphous samples cryst., and decompn. into z-BN plus the resp. nitride (e.g., -Si3N4) occurs. Compacts of the composites are obtained by in situ sintering under high pressure. The compacts exhibit peculiar microstructures composed of z-BN nanocrystals homogeneously dispersed in the nitride matrixes.

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Characterization of ceramic matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M., Jr.; More, K. L.; Sheldon, B. W.; Besmann, T. M. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 273-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:176787 AN 1990:576787 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A process for the prepn. of fiber-reinforced SiC composites by chem.-vapor deposition has been developed at Oak Ridge National Lab. Composites are prepd. by infiltrating fibrous preforms with reactant gases that decomp. at elevated temps. to deposit SiC between and around the fibers. Because the infiltration process utilizes both temp. and pressure gradients, SiC is deposited under conditions that vary considerably from the hot face to the cool face of the composite. Matrix characterization of composite samples by TEM and Raman spectroscopy are described.

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Analysis and testing of the metal parts furnace for the demilitarization of chemical warfare munitions. Fournier, Ronald L.; Horne, Deane A.; Rinker, Franklin G.; Jackson, Kerm. Dep. Chem. Eng., Univ. Toledo, Toledo, OH, USA. Journal of Hazardous Materials (1990), 23(1), 1-20. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 113:137967 AN 1990:537967 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At the Chem. Agent Munitions Disposal System (CAMDS) located to Tooele Army Depot, Utah, the munition metal parts contg. <5% residual agent are thermally decontaminated in roller hearth-type furnace, the Metal Parts Furnace (MPF). The drained munitions are heated to >1000F for 15 min to insure complete destruction of any remaining agent residue. During this heating process the residual agent vaporizes. The vaporized agent burns within the MPF and the MPF afterburner prior to treatment of the combustion product gases in the pollution abatement system. Agent vaporization is a rapid unsteady process with peak Btu loadings on the MPF of 10 million Btu/h. Since there are 14 different munition types contg. 3 different types of chem. agents, ranging from a load of 96 105-mm projectiles contg. as little as 0.08 lbs of the nerve agent GB per projectile to a ton container with 80 lbs of the nerve agent VX, the control system of the MPF system must be flexible enough to handle a wide variety of thermal loads. To evaluate and predict the performance of the MPF, tests were performed at CAMDS by using a variety of munitions contg. chem. agent simulants. The simulants were selected on the basis of comparable b.ps., heat of vaporization, and heat of combustion. A math. model of the MPF was developed to predict the heating rate of the munition and the vaporization profiles of the agents and their simulants. The results of the model were compared to simulant testing in ton containers at CAMDS. The results show good agreement with the math. model predictions.

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Powder preparation and compaction behavior of fine-grained yttria-doped tetragonal zirconia polycrystals (Y-TZP). Groot Zevert, W. F. M.; Winnubst, A. J. A.; Theunissen, G. S. A. M.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of Materials Science (1990), 25(8), 3449-55. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:119698 AN 1990:519698 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Two wet chem. prepn. methods are described for Y2O3-doped tetragonal ZrO2 powders. Both methods yield powders with an extremely small crystallite size (8 nm) and a narrow size distribution. The agglomerate and aggregate structure of these powders was investigated by several techniques. Gel pptn. from an alkoxide soln. in water (alkoxide synthesis) results in a ceramic powder with irregular-shaped weak and porous agglomerates, which are built up from dense aggregates with a size of 18 nm. Gel ppts. formed from a metal-chloride soln. in NH3 (chloride synthesis) do not contain aggregates. Both types of agglomerate are fractured during isostatic compaction. Hydrolysis and washing under (strong) basic conditions probably decrease the degree of aggregation. The aggregate morphol. and structure are key parameters in the microstructure development during sintering of a ceramic. Several characteristics of these powders are compared with those of a com. one (Toyo Soda TZ3Y).

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Preparation of titanium carbide plates by chemical vapor deposition. Jiang, Chorn Cherng; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(2A), 1086-93. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 112:144385 AN 1990:144385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Thick TeCx plates were prepd. by chem.-vapor deposition using TiCl4, CCl4, and H2 as source gases at deposition temps. (Tdep) 1573-1873 K, total gas pressures (Ptot) 4-40 kPa, and source gas molar ratio [CCl4/(TiCl4 + CCl4)] (mc) 0.13-0.91. The effects of deposition conditions on the microstructure, preferred orientation, deposition rate, lattice parameter, and compn. were studied. A plate-like TiCx was obtained at mc 0.5. The (110) plane was preferably oriented parallel to the deposition surface at Tdep 1673-1873 K. The deposition rates showed a strong mc dependence and the max. rate was found at mc = 0.3-0.5. The activation energies for the formation of TiCx plates were 86 kJ/mol at Ptot = 4 kPa and 95 kJ/mol at Ptot = 40 kPa. When mc values were 0.13-0.51, the lattice parameter increased with increasing mc >0.72 at all Tdep. The at. ratio (C:Ti) for TiCx was 0.6-1.0 depending on deposition conditions.

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Characterization and processing of CVD powders for fabrication of composite and compound ceramics. Hori, Saburo; Shigaki, Yoshiki; Hirata, Yoshihiro; Yoshimura, Masahiro; Somiya, Shigeyuki. Kureha Chem. Ind. Co., Ltd., Tokyo, Japan. Materials Research Society Symposium Proceedings (1989), 155(Process. Sci. Adv. Ceram.), 3-12. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 112:144279 AN 1990:144279 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Two-component oxide powders were prepd. in the systems Al2O3-ZrO2, AliO3-TiO2, and Al2O3-SiO2 by a chem.-vapor deposition (CVD) method using a combustion flame for the purpose of fabricating resp. composite or compd. ceramics. The CVD powders were spherical and ultrafine (av. 30-70 nm) with log-normal size distribution, and exhibited either very homogeneous or nanoheterogeneous structure and crystallog. metastability in phases and solid soln. By starting from these CVD powders, uniform microstructures were achieved in the sintered products and better sinterability and novel microstructure became possible due to the metastability which reflected the formation mechanism of 2-component powders at high temps. CVD powders, previously considered difficult to sinter, proved to be excellent starting materials for fabrication of composite and compd. ceramics when improved processing methods were applied.

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Preparation of silicon carbide powders by chemical vapor deposition from the silane-methane-hydrogen system. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1989), 24(11), 3824-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 112:41177 AN 1990:41177 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor deposition (CVD) from the SiH4 + CH4 + H2 system was used to prep. -SiC powders at 1523-1673 K. The powders obtained at 1673 K were single-phase -SiC contg. neither free Si or free C. The powders obtained at <1623 K were composite powders contg. free Si. The carburization ratio (SiC/SiC + Si)) increased with increasing reaction temp. and total gas flow rate, and with decreasing reactant concn. The av. particle sizes detd. by TEM were 46-114 nm. The particle size increased with increasing reaction temp. and gas concn. but decreased with increasing gas flow rate. The -SiC particles obtained at <1623 K consisted of a Si core and a -SiC shell, as opposed to the -SiC particles obtained at 1673 K, which were hollow. IR absorption peaks were obsd. at 940 and 810 cm-1 for particles contg. a Si core, whereas a single peak at .apprx.830 cm-1 with a shoulder at .apprx.930 cm-1 was obsd. for the -SiC hollow particles. The lattice parameter of -SiC having a carburization ratio <70 wt. %, was larger than that of bulk -SiC and decreased with increasing carburization ratio. However, when the carburization ratio was >70 wt.%, the lattice parameter became approx. equal to that of bulk -SiC.

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The interaction of chemical kinetics and diffusion in the dynamics of chemical vapor infiltration. Middleman, Stanley. Dep. Ames/Chem. Eng., Univ. California-San Diego, La Jolla, CA, USA. Journal of Materials Research (1989), 4(6), 1515-24. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 112:24678 AN 1990:24678 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The classical model of chem. vapor infiltration treats diffusion and surface reaction in a representative cylindrical pore. Two significant modifications to that approach are presented. One accounts for more complex chem. by allowing for both gas-phase and surface reactions which lead to film growth. The other couples the pore model to a reactor model for the region external to the porous preform. The results demonstrate that it is possible to select chem. schemes that yield densification from the interior to the exterior of the preform, thus avoiding premature trapping of interior voids.

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The colloid chemistry of ceramic membranes. Xu, Qunyin; Gieselmann, Mary J.; Anderson, Marc A. Water Chem. Program, Univ. Wisconsin, Madison, WI, USA. Polymeric Materials Science and Engineering (1989), 61 889-93. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 111:238343 AN 1989:638343 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The colloid chem. in sol-gel processing for prepg. particulate ceramic membranes is a key tool used for tailoring membrane structures. The chem.-phys. variables in hydrolysis and peptization processes control the particle nature in sols, which is directly related to the gelation process and particle packing geometry in the hydrogel. The pore structure of membranes is mainly detd. by the size of primary particles rather than by that of aggregates. TiO2 membranes with mean pore diam. 1.8-3.0 nm were prepd. from primary particles <10 nm. A larger variety of pore structures in membranes, including broader pore size range and more narrow size distributions, can be made by controlling sol-gel processing conditions to serve a large range of applications.

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Chemical vapor deposition of ultrafine ceramic structures. Gallois, B. M.; Mathur, R.; Lee, S. R.; Yoo, J. Y. Dep. Mater. Metall. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1989), Volume Date 1988, 132(Multicompon. Ultrafine Microstruct.), 49-60. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 111:238219 AN 1989:638219 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ultrafine ceramic structures based on the nitrides and carbides of Ti and Si were prepd. in a computer-controlled hot-wall chem.-vapor deposition (CVD) reactor. Layered deposits were produced by pulsing the reactant gases judiciously under software control. The development of a columnar structure which is endemic to most CVD materials was suppressed. Skeletal structures of filaments were grown with appropriate catalysts by the vapor-liq.-solid mechanism and immediately infiltrated in situ with different materials to produce filament-reinforced composite coatings. Ultrafine-grained C films and filaments were grown from CH4-H mixts. by plasma-assisted CVD. The microstructural features of these materials are of the order 20-100 nm. The subgrain structure detd. by Raman spectroscopy varies at 2-3 nm.

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Stability to moisture for chemically vapor-deposited boron nitride. Matsuda, T. Japan Met. and Chem. Co. Ltd., Gunma, Japan. Journal of Materials Science (1989), 24(7), 2353-7. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 111:82901 AN 1989:482901 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor-deposited BN (CVD-BN) plates, prepd. from the BCl3-NH3-H2 gas system, were studied in terms of stability to moisture by IR spectroscopic measurement, chem. anal., and TG. The synthesis conditions of CVD-BN plates have a large effect on their stability to moisture. The stability of CVD-BN plates prepd. under a total gas pressure (Ptot) of 10-60 torr degraded as the deposition temp. (Tdep) decreased. The CVD-BN plates with transparent and isotropic properties, which were prepd. at <1400 and >10 torr, showed poor stability to moisture. The CVD-BN plates synthesized under 5 torr had high moisture-resistance, even at a Tdep 1400. An IR absorption spectra revealed that the unstable species existing in CVD-BN plates had changed to ammonium borate hydrates by reacting with moisture in the atm. The stability to moisture for CVD-BN plates degraded as the deposition rate increased, esp. for the CVD-BN plates prepd. at 1400.

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Interfacial chemistry-structure and fracture of ceramic composites. Schoenlein, L. H.; Jones, R. H.; Henager, C. H.; Schilling, C. H.; Gac, F. Pac. Northwest Lab., Richland, WA, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 313-21. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119795 AN 1989:119795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interfacial chem. and phases of SiC-reinforced Si3N4 composites were studied by TEM with assocd. x-ray energy-dispersive spectroscopy microanal. and Auger electron spectroscopy. Hot-pressed Si3N4 (HPSN) composites reinforced with Nicalon SiC fibers or Tateho SiC whiskers and reaction-bonded Si3N4 (RBSN) composites reinforced with uncoated or coated VLS SiC whiskers were evaluated. In the Nicalon fiber-reinforced HPSN, an interfacial phase composed of a layer of amorphous C and an adjacent layer of graphitic C was obsd. and is believed to assist fiber pull-out during fracture of the composite. However, the fracture strength and toughness of these composites were considerably less than those of unreinforced HPSN. HPSN composites reinforced with Tateho SiC whiskers contained an interfacial phase believed to be similar to the intergranular phase found in the HPSN matrix. In RBSN composites fabricated with an Fe2O3 sintering aid, the VLS SiC whiskers were severely faceted by a reactive Fe silicide phase despite C, BN, or SiO2 coatings on the whiskers. When no sintering aid was used, the uncoated whiskers were not degraded and appeared to be strongly bounded to the RBSN matrix. The composites reinforced with SiO2-coated whiskers possessed the highest fracture strength and toughness, and the composites reinforced with the BN-coated whiskers possessed the lowest fracture strength and toughness.

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Theoretical analysis of chemical vapor infiltration in ceramic/ceramic composites. Tai, Nyan Hwa; Chou, Tsu Wei. Dep. Mech. Eng., Univ. Delaware, Newark, DE, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 185-92. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119788 AN 1989:119788 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A model for the deposition of Al2O3 and TiC with a ceramic fiber bundle from the chem. reactions was studied. The model considers vapor diffusion, chem. reaction on the inner surface of the capillary, deposition film growth, porosity, and effects of reactant compns. at various reactor temps. and pressures. Binary, multicomponent diffusion and Knudsen diffusion account for the different stages of the chem.-vapor-infiltration (CVI) process. Furthermore, both diffusion-controlled and reaction-controlled processes were examd. to det. the dominating process in CVI.

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Fracture behavior of 3-D braided Nicalon/silicon carbide composite. Yang, J. M.; Chou, J. C.; Burkland, C. V. Dep. Mater. Sci. Eng., Univ. California, Los Angeles, CA, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 163-8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119785 AN 1989:119785 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture behavior of a 3-dimensional (3-D) braided Nicalon fiber-reinforced SiC matrix composite processed by chem. vapor infiltration (CVI) was studied. The fracture toughness and thermal shock resistance under various thermomech. loadings were characterized. A tough and durable structural ceramic composite can be achieved through the combination of 3-D fiber architecture and the low-temp. CVI processing.

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Chemical interactions in ceramic and carbon-carbon composites. Luthra, Krishan L. Corp. Res. Dev., Gen. Electr. Co., Schenectady, NY, USA. Materials Research Society Symposium Proceedings (1988), 125(Mater. Stab. Environ. Degrad.), 53-60. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 110:119676 AN 1989:119676 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 10 refs. The useful lives of many ceramic composites are affected, if not controlled, by chem. interactions between various constituents and the gas environment. Thermochem. calcns. are extremely valuable in evaluating these concerns. Examples of many possible concerns are presented. The usefulness of a thermochem. approach is demonstrated by a somewhat detailed discussion of the oxidn. protection of C/C composites. This includes discussion of the various possible rate-limiting steps and the detrimental effects of CO gas formed as a result of C oxidn.

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Consolidation of silicon nitride (Si3N4) powder-preform by infiltration of boron nitride using the pulse CVI [chemical vapor infiltration] process. Sugiyama, Kohzo; Ohsawa, Yoshimi. Fac. Eng., Nagoya Univ., Nagoya, Japan. Journal of Materials Science Letters (1988), 7(11), 1221-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 110:62400 AN 1989:62400 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

BN infiltration into a Si3N4 powder preform, as a model of pulse chem.-vapor infiltration and means of consolidating powder preforms, is reported. The resulting samples were studied using SEM and electron microprobe x-ray microanal. and the effect on flexural strength was detd. The BN matrix deposits tightly among the particles of Si3N4.

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Bonding in aluminum phosphate ceramics prepared at low temperatures. Silsbee, Michael R.; Roy, D. M. Dep. Mater. Sci. Eng., Pennsylvania State Univ., University Park, PA, USA. Materials Research Society Symposium Proceedings (1988), 114(Bonding Cem. Compos.), 295-300. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 109:114885 AN 1988:514885 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The process of chem. binding involves the transformation of a powder into a single contiguous mass. This process is likely to involve considerable structural rearrangement. The presence of a liq. phase offers a low energy pathway for the movement of ions required to achieve this rearrangement. The presence of the liq. phase alone is not sufficient to insure a successful transformation. Thermodn. considerations govern the ultimate reaction products, and the structure and chem. reactivity of the starting materials play a major role in the binding reaction. The ability of the solid phases to release ions for transport is important. Al(OH)3 served as a source of Al ions that reacted with the phosphate ions already in soln. to form an amorphous phase binding the less reactive -Al2O3 and AlPO4 particles together. The addn. of relatively small amts. of amorphous SiO2 altered the reaction products rather drastically.

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Detectors in battle. Powell, R. J. UK. Chemistry in Britain (1988), 24(7), 665, 667, 669. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 109:78950 AN 1988:478950 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The operating principle and design of 2 chem. warfare agent detectors are discussed. Both of the detectors have electrochem. cells which respond to nerve agents (tabun, sarin, VX) and to HCN.

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Density and deposition rate of chemical-vapor-deposited boron nitride. Matsuda, Toshitsugu; Nakae, Hiroyuki; Hirai, Toshio. Japan Met. Chem. Co., Ltd., Gunma, Japan. Journal of Materials Science (1988), 23(2), 509-14. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 108:191407 AN 1988:191407 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The d. and deposition rate characteristics were studied of chem.-vapor-deposited BN (CVD-BN) plates synthesized by use of the BCl3-NH3-H2 system at deposition temp. (Idep) 1200-2000 and total gas pressure (Ptot) 5-60 torr. At Ptot, all the CVD-BN plates synthesized at each Tdep above 1300 had a d. >2.0 g/cm3 and thus showed no noticeable dependence on Idep. Over the Ptot range from 10-60 torr, on the other hand, the d. of the plates reached the max. of 2.08 g/cm3 at Tdep 2000. As Tdep was lowered, the d. decreased to a min. of 1.40 g/cm3. The deposition rate varied with both Tdep and Ptot and showed a max. value under a certain Ptot at a given Tdep. The value of Ptot where the deposition rate becomes max. changed depending on the Tdep. The max. deposition rate was 0.6 mm/h for the CVD-BN plates when the d. was <2.0 g/cm3 and 0.4 mm/h when the d. was >2.0 g/cm3. The effects of deposition conditions on the characteristics of the d. and deposition rate are discussed in terms of the structure and deposition mechanism.

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Synthesis and catalytic activity of surfactant analogs of 4-(dimethylamino)pyridine. Katritzky, Alan R.; Duell, Bradley L.; Durst, H. Dupont. Dep. Chem., Univ. Florida, Gainesville, FL, USA. Langmuir (1987), 3(6), 976-82. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 107:197237 AN 1987:597237 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Seven surfactants have been synthesized, each contg. a 4-(dialkylamino)pyridine moiety carrying an 8-10-carbon chain with an attached polar or charged group. Two of the compds. fall into the neutral charge category, two are cationic, two are zwitterionic, and one is anionic. Rates of hydrolysis of 4-nitrophenyl hexanoate and 1,2,2-trimethylpropyl methylphosphonofluoridate by each surfactant were measured, both with and without added cetyltrimethylammonium chloride (CTAC). The most active deriv. was sodium 10-[butyl(4-pyridinyl)amino]decyl sulfate. The present catalysts, in contrast to the iodosobenzoates, show poor rate enhancements in the hydrolysis of fluorophosphonates.

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High temperature evaporation characteristics of amorphous Si3N4-C composite prepared by chemical vapor deposition. Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1987), 22(8), 2842-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 107:119869 AN 1987:519869 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Evapn. characteristics of amorphous Si3N4 and amorphous Si3N4-C composite (6 wt.% C) prepd. by the chem.-vapor deposition (CVD) were studied at 1400-1650 in a vacuum of .apprx.10-6 torr. The wt. loss due to the evapn. was linear with time for all samples tested. The evapn. rate of the amorphous CVD-(Si3N4-C) composite was 50-70% of that for the amorphous CVD-Si3N4. The activation energy for evapn., calcd. from the temp. dependence of the evapn. rates, was .apprx.160 kcal/mol for both samples. The C dispersed in the amorphous CVD-(Si3N4-C) composite reacted at the time of heat-treatment with the amorphous Si3N4 matrix and formed -SiC particles. The -SiC particles were .apprx.100 nm in diam. and connected to form a 3-dimensional network structure.

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Influence of synthesis chemistry on alumina-zirconia powder characteristics. Debsikdar, J. C. Battelle Columbus Div., Columbus, OH, USA. Journal of Materials Science (1987), 22(6), 2237-47. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 107:44957 AN 1987:444957 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. polymn., destabilization of mixed sols, and copptn. chem. processes were used to synthesize 80Al2O3.20ZrO2 (wt.%) powders. The elementary particles produced by each of these processes were 1.5-3.0 nm in size and were amorphous to electron diffraction. The powders were evaluated in terms of wt. loss (TGA), thermal characteristics (DTA), surface area (Brunauer-Emmett-Teller equation), pore size distribution, d. at different temps., and crystn. behavior (x-ray diffraction). The physicochem. characteristics and crystn. behavior of these chem. derived powders were significantly affected by the chem. of the powder synthesis. The powders produced by the chem. polymn. and the colloidal processes retained the tetragonal ZrO2 phase during cooling from 1600, but significant transformation of tetragonal to monoclinic ZrO2 occurred in the copptd. powder under identical conditions. The 1550-calcined powder derived by the chem. polymn. process retained a substantial amt. of tetragonal ZrO2 after annealing at 1000 for 72 h. The av. Al2O3 and ZrO2 crystal size of the calcined powders, calcd. by the Scherrer equation, was 20-80 nm.

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Characterization of wurtzitic boron nitride compacts. Singh, Bhanu Pratap. Natl. Phys. Lab., New Delhi, India. Journal of Materials Science (1987), 22(2), 495-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 106:161234 AN 1987:161234 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The properties of sintered polycryst. wurtzitic BN compacts were studied including the cryst. phases that formed at high temp. and pressure, compn., BN and binder particle size distribution, and hardness. Wurtzitic BN, cubic BN, TiC/TiN solid soln., TiB, and TiB2 were the cryst. phases obsd. The BN and binder particle size distributions were comparable (1-5 m), with .apprx.80% of the particles 2-3 m. Wt. percentages of different elements present in these compacts were detd. The av. Knoop hardness values under 500 g load and the variation of hardness as a function of position on the specimen surface were studied.

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Morphological and mechanical characterization of ceramic composite materials. Chermant, J. L.; Gomina, M.; Osterstock, F. ISMRa, Univ. Caen, Caen, Fr. Materials Science Research (1986), 20(Tailoring Multiphase Compos. Ceram.), 615-29. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 106:124512 AN 1987:124512 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

C fiber-reinforced (chem. vapor-deposited SiC) ceramic composites were tested in 3-point bending in 3 orientations of the notch prior to the applied stress. For the 2 main orientations, load-unloading sequences were performed to investigate the rupture parameters using the M. Sakai et al. (1983) method. The very good mech. behavior of these materials are due to the energy dissipative effect of the reinforcement. For the weaker orientation, an empirical method is proposed to measure the compliance at any point of the load-displacement curve.

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Chemical vapor deposition of Si3N4 from a gas mixture of Si2Cl6, NH3 and H2. Motojima, Seiji; Iwamori, Noriyuki; Hattori, Tatsuhiko. Fac. Eng., Gifu Univ., Gifu, Japan. Journal of Materials Science (1986), 21(11), 3836-42. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 105:231265 AN 1986:631265 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Si3N4 layers were prepd. on a quartz substrate from a gas mixt. of Si2Cl6, NH3, and H2 under a reduced pressure and at 800-1300. Amorphous Si3N4 layers that were dense and adherent to the substrate were obtained at 800-1100. On the other hand, -Si3N4 layers were obtained at 1200 and a source-gas ratio (N/Si) of 1.33-1.77. The lowest deposition temp. of amorphous Si3N4 was .apprx.700. The microhardness of amorphous Si3N4 obtained at 800-1100 was 2400-2600 kg/mm2 (load: 50 g), and that of -Si3N4 obtained at 1200 was 3400 kg/mm2. Chlorine contents in the Si3N4 layer decreased with increasing deposition temp. and source-gas ratio (N/Si), and with decreasing total pressure.

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Innovative chemical/ceramic directions. Morgan, P. E. D. Rockwell Int. Sci. Cent., Thousand Oaks, CA, USA. Materials Research Society Symposium Proceedings (1986), 73(Better Ceram. Chem. 2), 751-63. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 105:213019 AN 1986:613019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 37 refs., of chem. methods of ceramic prepn. including discussions of the sol-gel process, nanostructures, polymer pyrolysis, fused salt synthesis of chalcogenides, transformation toughening, liq. boundary phases, and Si3N4 prepn. from SiCl4 and (SiS2 + SiCl4).

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Microhardness and internal stress of silicon nitride (Si3N4)-silicon carbide films prepared by plasma CVD. Kamata, Kiichiro; Aizawa, Naoyoshi; Moriyama, Minoru. Technol. Univ. Nagaoka, Nagaoka, Japan. Journal of Materials Science Letters (1986), 5(10), 1055-7. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 105:196083 AN 1986:596083 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microhardness and internal stress of Si3N4-SiC films prepd. by plasma chem.-vapor deposition were detd. in relation to use of the coatings for high strength and wear resistance. The films had compns. indicated by SiNxCy where x = 0-1.42 and y = 0-1.04. The relation between the crack length in a film coating on glass substrates (induced by a Vickers indentor) and the internal stress is discussed.

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Hybridization between silicon nitride (Si3N4) and silicon carbide films by plasma CVD. Kamata, Kiichiro; Maeda, Yuuji; Moriyama, Minoru. Technol. Univ. Nagaoka, Nagaoka, Japan. Journal of Materials Science Letters (1986), 5(10), 1051-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 105:196082 AN 1986:596082 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hybrid SiC-Si3N4 films were prepd. by charge-coupled plasma chem.-vapor deposition from SiH4, NH3, CH4 (or C2H4), and H2 reaction gases. Homogeneous amorphous films were easily obtained. The C, N, and Si contents of the films were detd. Grains or phase boundaries were not obsd. using TEM. The n, IR absorption peak position, and optical band gap of the films varied continuously with changing amts. of each component in the Si3N4-SiC films. These results and TEM observations indicate that the films are not a mixt. of Si3N4 and SiC clusters. but are hybrid materials in which Si, N, and C atoms are blended on an at. scale.

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Zirconia: ceramic engineering's toughness challenge. Fisher, Greg. Dir. Tech. Serv., ACerS, USA. American Ceramic Society Bulletin (1986), 65(10), 1355-60. CODEN: ACSBA7 ISSN: 0002-7812. Journal; General Review written in English. CAN 105:195989 AN 1986:595989 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 54 bibliog. refs., of the chem. and properties of ZrO2 ceramics and the relations of these characteristics to ceramic toughness.

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Hydrolysis of mustard derivatives in aqueous acetone-water and ethanol-water mixtures. Yang, Yu Chu; Ward, J. Richard; Luteran, Thomas. Res. Dir., U. S. Army Chem. Res. Dev. cent., Aberdeen Proving Ground, MD, USA. Journal of Organic Chemistry (1986), 51(14), 2756-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 105:42037 AN 1986:442037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Kinetic data for the hydrolysis of ClCH2CH2SR (R = Me, Et) in the title solvents were interpreted in terms of an SN1 mechanism with anchimeric assistance of the S atom to form a cyclic sulfonium ion as an intermediate. A finite and neg. Cp.thermod. was obsd.

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Synthesis of fiber-reinforced silicon carbide composites by chemical vapor infiltration. Stinton, David P.; Caputo, A. J.; Lowden, Richard A. Oak Ridge Natl. Lab, Oak Ridge, TN, USA. American Ceramic Society Bulletin (1986), 65(2), 347-50. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 104:93916 AN 1986:93916 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A process was developed for the fabrication of fiber-reinforced SiC composites by chem.-vapor infiltration. Infiltration times of the low-d. fibrous structures were reduced significantly from previous processes by utilizing simultaneously a thermal gradient and forced gas flow. Synthesis of composites in this fashion produced specimens with high flexural strengths and with strain tolerances which significantly exceeded that of monolithic SiC.

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Creep of chemically vapor deposited silicon carbide fibers. Dicarlo, James A. Lewis Res. Cent., Natl. Aeronaut. Space Adm., Cleveland, OH, USA. Journal of Materials Science (1986), 21(1), 217-24. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 104:55136 AN 1986:55136 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The creep, thermal expansion, and elastic modulus properties of chem. vapor-deposited SiC fibers were detd. at 1000-1500. Creep strain increased logarithmically with time, monotonically with temp., and linearly with tensile stress at 600 MPa. The controlling activation energy was 480  20 kJ/mol. Thermal pretreatments at .apprx.1200 and 1450 significantly reduced fiber creep. These results coupled with creep recovery observations indicate that at <1400 fiber creep is anelastic with a negligible plastic component. This allowed a simple predictive method to be developed for describing fiber total deformation as a function of time, temp., and stress. Mechanistic anal. of the property data suggests that fiber creep is the result of -SiC grain-boundary sliding, controlled by a small percentage of free Si in the grain boundaries.

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Mechanical properties of zirconia-toughened alumina ceramics from CVD powders. Hori, Saburo; Yoshimura, Masahiro; Somiya, Shigeyuki; Kurita, Ryuichi; Kaji, Hisatsugu. Res. Lab. Eng. Mater., Tokyo Inst. Technol., Yokohama, Japan. Journal of Materials Science Letters (1985), 4(4), 413-16. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 103:10304 AN 1985:410304 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and bending strength were measured on sintered ZrO2/-toughened Al2O3 samples which had been prepd. from a chem. vapor-deposited powder. Fracture toughness increased with ZrO2 addns. from 2.6 to 4.8 MPam1/2. Bending strength increased from 430 to 660 MPa with ZrO2 addns. up to 15 wt. % then droped to .simeq.500 MPa at 20-25 wt. % addn. X-ray anal. showed that the drop in bending strength corresponded to a drop in tetragonal phase content. Both the bending strength and fracture toughness increased .apprx.50% with 15 wt. % ZrO2 addn.

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Fracture energy of silicon nitride. Rice, R. W.; McKinney, K. R.; Wu, C. C.; Freiman, S. W.; Donough, W. J. M. Nav. Res. Lab., Washington, DC, USA. Journal of Materials Science (1985), 20(4), 1392-406. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 102:224933 AN 1985:224933 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture energy of Si3N4 made by hot pressing, reaction sintering, and chem. vapor deposition (CVD) was studied. Extrapolation of fracture energies to zero additive or porosity levels, as well as anal. of CVD Si3N4 all indicate an intrinsic fracture energy of 20-30 J/m. Higher fracture energies in dense bodies with increasing additive content, or in some more porous bodies (relative to expected porosity dependence) are assocd. with crack branching. In dense bodies such branching may arise due to microcracking from combined effects of crack tip stresses and mismatch stresses due to differences in properties, esp. thermal expansion, between Si3N4 and the additive or it reaction products. In porous bodies such branching appears to be due to spatial distribution of pores.

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A morphological study of silicon carbide prepared by chemical vapor deposition. Tsui, P.; Spear, K. E. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 371-80. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 102:171306 AN 1985:171306 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Surface morphologies of SiC deposits obtained via chem. vapor deposition (CVD) were studied as functions of substrate surface temp. and the concn. of the Si and C source material, MeSiCl3. Substrates of graphite and -SiC crystals were used. Explanations of the obsd. morphologies on graphite substrates and their marked changes with temp. are given in terms of chem. kinetics and mass transport arguments. The results of thermodn. calcns. were used to help explain the obsd. morphologies of the deposits on -SiC substrates.

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Preparation of amorphous silicon nitride-boron nitride composites by chemical vapor deposition. Hirai, Toshio; Goto, Takashi; Sakai, Tadashi. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 347-58. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 102:171304 AN 1985:171304 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor deposition of an Si-N-B system was studied by using SiCl4, NH3, H2 and B2H6 as source gases at deposition temps. of 1100-1300 and total gas pressures of 30-70 torr. The chem. compn. and d. of the deposits were measured. The structure of the deposits was investigated by x-ray diffraction and IR absorption techniques. The deposits were composed of amorphous Si3N4 and turbostratic BN.

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CVD of silicon nitride and its composites. Hirai, Toshio. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 329-45. CODEN: MTSRAY ISSN: 0076-5201. Journal; General Review written in English. CAN 102:171201 AN 1985:171201 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 33 refs., is given of the synthesis, structure, and some properties of Si3N4-based ceramics and composites prepd. by the chem.-vapor deposition process.

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Calculation of deposition conditions for silicon nitride from a SiL4-NH3 gas phase (L = H, Cl, Br, CH). Lartigue, J. F.; Ducarroir, M.; Armas, B. Lab. Ultra-Refract., CNRS, Odeillo/FontRomeu, Fr. Journal of Materials Science (1984), 19(9), 3079-89. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 102:11260 AN 1985:11260 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Deposition conditions yielding Si nitride are calcd. for a set of initial gaseous systems, by complex thermodn. equil. computations. The influence of temp., total pressure and reactant gas ratios on the compn. and yield of the condensed phase are shown for SiH4/NH3, SiCl4/NH3, SiBr4/NH3, Si(CH3)4/NH3, and SiH4/CH4/NH3 systems. The interest of such calcns. is to give an efficient approach for exptl. studies of vapor-deposition systems.

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Mechanical properties of chemically vapor deposited nonoxide ceramics. Niihara, Koichi. Tohoku Univ., Sendai, Japan. American Ceramic Society Bulletin (1984), 63(9), 1160-4. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 101:196815 AN 1984:596815 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Plates of chem. vapor-deposited nonoxide ceramics (Si3N4, SiC, and B4C) up to 3 mm thick were prepd. with high purity and d. at high deposition rates (>1 mm/h). High-resoln. electron microscopy of these materials reveals that there are no glassy layers or secondary phases at any grain boundaries and multiple-grain junctions. Thus, degrdn. of strength and toughness is not obsd. up to 1500; the strength and toughness of the Si3N4 and SiC increase with increasing temp. above 800 and 1100, resp. The effects of preferred orientation, grain size (residual internal stress), and stoichiometry on the mech. properties also were examd.

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Effects of water chemistry on the leach resistance of SYNROC C. Woolfrey, J. L.; Levins, D. M. Lucas Heights Res. Lab., Aust. Atomic Energy Comm., Sydney, Australia. Materials Research Society Symposium Proceedings (1984), 26(Sci. Basis Nucl. Waste Manage. 7), 663-70. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 101:62325 AN 1984:462325 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. durability of SYNROC-C was measured as a function of repository conditions, namely, temp., surface/vol. ratio, groundwater pH, and compn. The leach rate of SYNROC-C is less dependent on temp. than borosilicate glasses: activation energies range from 15-25 kJ mol-1 compared to 33-74 kJ mol-1 for glass. The rate of release from SYNROC-C is very low and independent of soln. compn. for the solns. studied. There is little variation in leach rate over the pH range 4-9, but at pH 2 the rate is up to 10 times higher. SYNROC-C leach rate is independent of flow rate or surface/vol. ratio for the mobile waste elements because of the unimportance of soln. satn. effects owing to the low concn. of dissolved solids. The differential leach rate decreases rapidly with time because, after initial leaching from grain boundaries and metastable minor phases, the highly insol. matrix protects the more leachable elements from further attack.

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Effects of variability of the base powder on the sintering of -silicon carbide. Williams, R. M.; Juterbock, B. N.; Peters, C. R.; Whalen, T. J. Ford Motor Co., Dearborn, MI, USA. Journal of Materials Science Letters (1984), 3(3), 265-7. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 100:160854 AN 1984:160854 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The importance of using starting powders with rigidly controlled chem. and crystallog. compn. and phys. characteristics for sintering of -SiC was investigated. Tests were conducted with 2 lots of sinterable -SiC from the same manufacturer and of the same grade. Differences in particle-size distribution, surface area, and chem. compn., most notably in free C and O contents, were obsd. The morphol. of the 2 materials was similar. The variations obsd. in the phys. properties of the ceramics and in temps. at which phase transformations occur were quite significant in comparison to the property differences of the starting materials.

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Microstructure of silicon nitride-titanium nitride composites prepared by chemical-vapor deposition. Hayashi, Shinsuke; Hirai, Toshio; Hiraga, Kenji; Hirabayashi, Makoto. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1982), 17(11), 3336-40. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 98:21091 AN 1983:21091 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The shapes and the distribution of TiN within Si3N4-TiN composites prepd. by the chem.-vapor deposition of a SiCl4-TiCl4-NH3-H2 system were examd. using an electron microscope. The TiN dispersion in the amorphous Si3N4 matrix was granular and its max. size was 3 nm. The TiN dispersions in - and -Si3N4 matrices were contained in their resp. crystal grains; however, the shape of the TiN dispersions in the -Si3N4 matrix was different from that in the -Si3N4 matrix. Granular TiN dispersions with an av. size of 10 nm were obsd. in the -Si3N4 matrix. The TiN dispersions in the -Si3N4 matrix were columnar with a diam. of several nm having its axis extended to the direction parallel to the c-axis of the -Si3N4 crystal.

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Density and deposition rates of amorphous CVD-silicon nitride (Si3N4) including carbon. Hirai, Toshio; Goto, Takashi. Res. Inst. Iron, Steel Other Metals, Tohoku Univ., Sendai, Japan. Journal of Materials Science (1981), 16(10), 2877-82. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 96:39625 AN 1982:39625 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Amorphous Si3N4 contg. uniformly distributed C was prepd. by chem. vapor deposition using SiCl4 vapor and NH3, H2, and C3H8 gases at desorption temps. (T) of 1100 to 1300 and at total gas pressures (P) of 30 to 70 torr. The d. of the amorphous Si3N4 deposit was 2.80-3.00 g/cm3, depending upon the deposition conditions. The rate of growth in thickness increased with increasing T and P and had the largest value of 0.6 mm/h at T = 1300, P = 70 torr, and C3H8 gas flow rates of 0 to 20 cm3/min. The activation energy of formation decreased from 38 to 20 kcal/mol with increasing P and C3H8 flow rate.

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The delayed neuropathic effects of nerve agents and some other organophosphorus compounds. Gordon J J; Inns R H; Johnson M K; Leadbeater L; Maidment M P; Upshall D G; Cooper G H; Rickard R L Archives of toxicology (1983 Feb), 52(2), 71-82. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 6847383 AN 83203413 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

[megalomania]

Bibliographic Information

Crystal chemistry and phase manipulation in Synroc. Vance, E. R.; Moricca, S.; Thorogood, G. J.; Lumpkin, G. R. Aust. Nucl. Sci. Technol. Organ., Menai, Australia. Key Engineering Materials (1991), 53-55(Austceram '90), 717-21. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 118:259605 AN 1993:259605 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The modification of the titanate ceramic Synroc was studied in terms of decreasing the unstable perovskite phase content, incorporation of process chems., and incorporation of Al-rich and actinide-rich nuclear wastes. A formulation of alkoxide-derived Al2O3 (7.8), BaO (11.7), CaO (8.3), TiO2 (54.1), and ZrO2 (18.1 wt.%) produced a mixt. of hollandite and zirconolite when sintered at 1200 in air, but .apprx.10 wt.% perovskite formed when hot pressed at 1200. A cor. formulation with 30 wt.% simulated high-level waste substitution for ZrO2 still produced a significant amt. of perovskite. Mg from fuel cladding was predicted to be incorporated in a MgTi2O5 phase which was demonstrated to be compatible with the other Synroc phases. P was incorporated in the alloy phase and as Ca3(PO4)2 at higher loadings. Satisfactory Cs leach rates were obtained when alkoxide-derived Synroc powders were hot pressed at 1400, but not all Al from the waste was incorporated in the Synroc phases at loadings as low as 10 wt.% Al2O3.

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Study of the efficacy of CC-2 and Fuller's earth combination as a decontaminant against sulfur mustard (mustard gas) dermal intoxication in mice. Kumar, Pravin; Sharma, U. S.; Vijayaraghavan, R. Def. Res. and Dev. Establ., Gwalior, India. Defence Science Journal (1991), 41(4), 363-6. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 116:189222 AN 1992:189222 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Decontamination efficacy of Fuller's earth and CC-2 independently; and in different combinations was evaluated against toxicity of sulfur mustard applied percutaneously on mice. Max. protection was obtained with fuller's earth and CC-2 in a combination of 80:20 (wt./wt.).

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Thermochemical analysis of chemical processes relevant to the stability and processing of silicon carbide-reinforced silicon nitride composites. Misra, A. K. NASA Lewis Res. Cent., Sverdrup Technol., Inc., Cleveland, OH, USA. Journal of Materials Science (1991), 26(24), 6591-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:65309 AN 1992:65309 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. processes relevant to the stability and processing of SiC-reinforced Si3N4 composites are examd. from a thermochem. point of view. The thermodn. stability of various interfaces, such as SiC-Si3N4, SiC-Si3N4-Si2ON2, and SiC-Si3N4-SiO2, is examd. as a function of temp. The temps. above which these interfaces become unstable are calcd., and the degrdn. of SiC during the processing of the composite is examd. The processing routes considered in this study include the reaction-bonded Si3N4 process, as well as pressure-assisted sintering processes in the presence of suitable sintering additives.

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Microstructural and chemical effects in alumina implanted with iron at 77 K and annealed in oxidizing or reducing atmospheres. McHargue, C. J.; Sklad, P. S.; White, C. W.; McCallum, J. C.; Perez, A.; Marest, G. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Materials Research (1991), 6(10), 2160-77. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 115:238068 AN 1991:638068 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Implantation of Fe (160 keV) into -Al2O3 at 77 K produces an amorphous surface layer for fluences 1016-1017 Fe ions/cm2. Measurements of short-range order were made by extended energy loss fine structure anal. The structure of amorphous Al2O3 produced by implantation of Fe at 77 K exhibits short-range order that differs from that produced by stoichiometric (Al + O) implants. This difference is manifested by changes in the Al-O near-neighbor bond length. The local environments of implanted Fe were detd. from conversion electron Moessbauer spectroscopy. The Fe resides in several different local environments consistent with the electronic states of Fe2+, Fe4+, and Fe0. The relative amt. of each environment depends on the concn. (fluence) of the implanted Fe ions. Regrowth of the amorphous zone during annealing occurs in the sequence amorphous Al2O3  -Al2O3  -Al2O3. The kinetics of regrowth and phase sepn. vary with implanted fluence with annealing atm. The higher the concn. of implanted Fe, the slower the formation of Fe-Al2O3 ppt. phases in oxidizing atmospheres and -Fe ppts. in reducing atmospheres.

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Microstructural and chemical effects in alumina implanted with iron at room temperature and annealed in oxidizing or reducing atmospheres. McHargue, C. J.; Sklad, P. S.; White, C. W.; Farlow, G. C.; Perez, A.; Marest, G. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Materials Research (1991), 6(10), 2145-59. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 115:238067 AN 1991:638067 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

RBS-ion channeling, TEM, and conversion electron Moessbauer spectroscopy were used to det. the structure of -Al2O3 implanted with Fe at room temp. Changes produced by post-implantation annealing in oxidizing and reducing atmospheres were followed using the same methods. Implantation of 160 keV Fe at room temp. produces a damaged but cryst. microstructure for fluences 1  1017 Fe ions/cm2. The Fe resides in a variety of local environments: 3 Fe2+ components, 1 Fe0 component, and 2 Fe4+ components. The relative amt. of each component varies with implantation fluence. Only the Fe0 component seems to be assocd. with 2nd-phase formation. In this case, 2 nm diam. -Fe particles were detected by TEM studies. Recovery of implantation-induced disorder in the Al- and O-sublattices occurs in 2 stages for annealing in O and in 1 continuous stage for H-annealing. The end state for Fe is Fe3+ for O anneals and Fe0 for H anneals. The pptd. phases obsd. are those to be expected from the equil. phase diagrams.

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Grain boundaries in high thermal conductivity aluminum nitride. McKernan, Stuart; Norton, M. Grant; Carter, C. Barry. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Materials Research Society Symposium Proceedings (1991), 203(Electron. Packag. Mater. Sci. 5), 229-34. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 115:237865 AN 1991:637865 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The benefits of AlN as a substrate material for the electronics packaging industry appear to be limited by the deleterious effects of boundaries in the polycryst. material. Some observations on different types of boundary in AlN using several complementary techniques are reported. Energy dispersive x-ray spectroscopy anal. of grain boundaries shows that there is O at the grain boundaries, in agreement with previous work. No variation in the grain-boundary chem. was detected in the proximity of Y2O3-rich particles. The apparent increase in the O peak is probably due to an increased width of the oxide layer close to the triple junction.

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Modified CVD of nanoscale structures in and EVD of thin layers on porous ceramic membranes. De Haart, L. G. J.; Lin, Y. S.; De Vries, K. J.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1991), 8(1), 59-70. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 115:213226 AN 1991:613226 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Expts. on the modified CVD and the electrochem. vapor deposition (EVD) of Y2O3-stabilized ZrO2 on porous substrates are reported. In the CVD stage, deposition occurs in a small (<20 m) region at the edge of the substrate, very likely leading to pore narrowing. This result illustrates the feasibility of the CVD technique for the modification of ceramic membranes to the (sub)nanometer scale. Film growth in the EVD stage is controlled by the in-pore diffusion of the O source reactant for short (<5 h) deposition times. The Y2O3/ZrO2 ratio in the deposited film is detd. by the ratio present in the vapor phase. Very thin (2 m) films can be deposited, which have a potential application in solid oxide fuel cells.

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Thermal stability of ceramic fiber in a CVI-processed silicon carbide matrix composite. Lin, W.; Yang, J. M. Dep. Mater. Sci. Eng., Univ. California, Los Angeles, CA, USA. Journal of Materials Science (1991), 26(15), 4116-22. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:140940 AN 1991:540940 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The thermal stability of the HPZ (Si-C-O-N system from hydridopolysilazane polymer precursor) fiber in a chem. vapor infiltration (CVI)-processed SiC matrix composite was studied. The mech. properties and fracture behavior of the untreated and SiC-coated fibers after thermal exposure at different temps. and atmospheres were characterized. At <1000, the strength degrdn. is negligible. However, severe degrdn. occurs at >1000 due to the evolution of CO, SiO, and other gaseous species. Also, pyrolytic C coating is needed to tailor the interfacial bond strength in the HPZ/SiC composites.

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Reaction chemistry at joined interfaces between silicon nitride and aluminum. Ning, X. S.; Okamoto, T.; Miyamoto, Y.; Koreeda, A.; Suganuma, K. Inst. Sci. Ind. Res., Osaka Univ., Osaka, Japan. Journal of Materials Science (1991), 26(15), 4142-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:118946 AN 1991:518946 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Joined interfaces of hot-isostatically pressed, additive-free Si3N4 ceramic/Al braze bonded at 1073 K for 18 ks or at 1473 K for 1.8 ks in a vacuum of 1.3 mPa and of -Si3N4 powder/Al powder interfaces bonded at 1073 K for 1.8 ks or 18 ks in the same vacuum were examd. by anal. TEM and x-ray diffraction. Mullite, some small crystals, and '-Sialon were detected at the interface of the ceramic/Al braze bonded at the low temp. and 15R AlN-polytype Sialon, '-Sialon, AlN, mullite, and SiO2-Al2O3 noncryst. material were detected at interfaces bonded at 1473 K. At the powder interface, AlN, and Si were also detected besides '-Sialon and the SiO2-Al2O3 noncryst. material, even though the bonding was conducted at the low temp. The interfacial reactions of the joints were affected not only by the bonding temp., but also by the oxide formed at the interface before bonding occurred.

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Thermo-mechanical properties and oxidation resistance of zirconia CVI matrix composites: 2 - thermal properties and oxidation resistance. Minet, J.; Langlais, F.; Naslain, R. Lab. Chim. Solide, Univ. Bordeaux, Talence, Fr. Journal of the European Ceramic Society (1991), 7(5), 283-93. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 115:118899 AN 1991:518899 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

ZrO2 matrix composites, prepd. by chem. vapor infiltration (CVI) from preforms (Al2O3 or C fibers) having a 2 (or pseudo-3-) dimensional character, were studied from a thermal behavior and resistance to oxidn. standpoint. The ZrO2 vol. fraction and residual porosity were within the 0.30-0.75 and 0.10-0.25 ranges, resp. The expts. were carried out 1500. Thermal expansion is low and almost reversible for the C-ZrO2 composites whereas it is more significant and partly irreversible for the Al2O3-ZrO2 composites. The Al2O3-ZrO2 composites exhibit an insulating character at >1000, comparable to that of sintered ZrO2, whereas the C-ZrO2 composites have a thermal cond. equal to that of sintered Al2O3 at >1000. The resistance to oxidn. by air is acceptable at moderate temps. and for short exposures. Under more severe conditions, damaging phenomena occur (i.e., grain growth, oxidn. of the C preform or BN interphase) which are detrimental to the mech. behavior.

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Efficacy of an oximate-based skin decontaminant against organophosphate nerve agents determined in vivo and in vitro. Sawyer, Thomas W.; Parker, Deborah; Thomas, Norleen; Weiss, M. Tracy; Bide, Richard W. Def. Res. Establ., Suffield/Ralston, AB, Can. Toxicology (1991), 67(3), 267-77. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 115:87007 AN 1991:487007 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Recent Canadian research efforts have been directed towards the development of a reactive skin decontaminant (RSD) lotion active against classical nerve agents and mustard. The formulation presently under study consists of a 1.25 m soln. of potassium 2,3-butanedione monoximate (KBDO) in polyethylene glycol Me ether 550. Although this formulation has shown good efficacy, concern has been expressed as to the potential toxicity of the reaction products of KBDO and organophosphate (OP) nerve agents. This report describes the high efficacy of this lotion in inactivating OPs as measured by the systemic toxicity of the OP/RSD mixts. in rats. In addn., primary cultures of chick embryo neurons were also used to test the efficacy of the RSD. By relating the anticholinesterase activity in these cultures of the OP/RSD mixt. to that of pure OP stds., a sensitive measure of the value of the RSD in inactivating tabun, sarin, soman and VX was obtained. Expts. with all 4 nerve agents in this in vitro system provided a good correlation with the in vivo data, and also indicated that the inactivation process was time- and agent-dependent and also related to the ratio of OP to RSD.

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Refractory ceramic foams: a novel, new high-temperature structure. Sherman, Andrew J.; Tuffias, Robert H.; Kaplan, Richard B. Ultramet Corp., Pacoima, CA, USA. American Ceramic Society Bulletin (1991), 70(6), 1025-7, 1029. CODEN: ACSBA7 ISSN: 0002-7812. Journal; General Review written in English. CAN 115:33992 AN 1991:433992 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 6 refs. Chem.-vapor infiltration (CVI) enables prepn. of the porous cellular structure. The fabrication of such a structure begins with the pyrolysis of a resin-impregnated thermosetting foam to obtain a reticulated C foam skeleton. The foam ligaments can then be coated with a variety of materials (metals, oxides, nitrides, carbides, borides, silicides, etc.), either singly or as hybrid, layered, alloyed, or graded structures. During this process, 10-1000 m of the desired material(s) are deposited onto the foam ligaments by CVI. The thermomech. properties of the resultant structure are dominated by the properties of the deposit, becoming independent of the c properties at very small material loadings. With precise control over the variables available, it is possible to obtain the simultaneous optimization of stiffness, strength, thermal cond., overall wt. and environmental resistance.

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Chemical control in precipitation of spherical zirconia particles. Lerot, L.; Legrand, F.; De Bruycker, P. Lab. Cent. Rech., Solvay et Cie, Brussels, Belg. Journal of Materials Science (1991), 26(9), 2353-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:13964 AN 1991:413964 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Monodisperse spherical ZrO2 particles were pptd. by hydrolysis of alc. solns. of Zr alkoxides in the presence of long-chain carboxylic acids. The particle size can be finely tuned from 0.1 to 2.5 m by controlling the concn. of Zr alkoxide, the water/Zr ratio, the nature of alc. from EtOH to BuOH, the nature of carboxylic acid from caproic to oleic acid, and its concn. The relations among the induction time before nucleation, the particle size, and all the above parameters are tentatively explained on the grounds of the soly. of the carboxy-alkoxide derivs. and their tendency to form micelles. Calcination of pptd. powders at 300-600 produces mixts. of varying compn. from cubic to monoclinic phases of small crystallite sizes and brings out the loss of surface area and org. content. Different conditions of drying powders lead to variously ordered microstructures.

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Stability of zirconia-ceria-yttria ceramics in hostile environments. Leach, C.; Khan, N. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1991), 26(8), 2026-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 114:212576 AN 1991:212576 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The phase chem., elec. cond. in air and forming gas, and stability in warm humid environments of ZrO2-CeO2-Y2O3 ceramics are described. The compns. studied lie between 12 mol% CeO2/88 mol% ZrO2 and 3 mol% Y2O3/97 mol% ZrO2 and fall within the tetragonal phase field of this ternary system. At 700, reducing atms. affected only the cond. of the end-member CeO2-ZrO2 ceramic, having no effect on the ternary compns. Compns. contg. >10 mol% CeO2 were more stable to stabilizer loss in water vapor at 132 than those contg. <10 mol% CeO2.

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A mathematical model for chemical vapor infiltration with microwave heating and external cooling. Gupta, Deepak; Evans, James W. Lawrence Berkeley Lab., Univ. California, Berkeley, CA, USA. Journal of Materials Research (1991), 6(4), 810-18. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 114:191000 AN 1991:191000 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model was used to compute temp. profiles in ceramic preforms that are heated by microwaves. The temp. profiles were then input to a 2nd part of the model describing chem. vapor infiltration of the preform, that is the diffusion of gaseous reactants, heterogeneous reaction, and evolution of the pore structure. Equations were solved numerically for parameters corresponding to the infiltration of SiC preforms by pyrolysis of MeSiCl3. While based on some simplifications, the model leads to the conclusion that infiltration proceeds more rapidly, and to a greater extent, with microwave heating/external cooling than in isothermal infiltration. The model suggests that infiltration might be optimized by manipulation of microwave power and external cooling. The computed extent of infiltration is very sensitive to the initial pore size.

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Preparation of silicon carbide powders by chemical-vapor deposition of the dichlorodimethylsilane-hydrogen system. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(11), 4614-21. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:236356 AN 1990:636356 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC powders were prepd. by chem.-vapor deposition using (Me)2SiCl2 and H2 as source gases at 1273-1673 K. Various kinds of SiC powders such as amorphous powder, -type single-phase powder, and composite powder were obtained. The composite powders contained free Si and/or free C phases of a few nanometers in diam. All the particles obsd. were spherical in shape and uniform in size. The particle size increased from 45 to 130 nm with decreasing reaction temp. and gas flow rate and with increasing reactant concn. The lattice parameter of the -SiC particles decreased with increasing reaction temp. All the lattice parameters were larger than those of bulk -SiC.

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Thermodynamics for the preparation of silicon carbide-carbon nanocomposites by chemical-vapor deposition. Wang, Y.; Sasaki, M.; Goto, T.; Hirai, T. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(11), 4607-13. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:236355 AN 1990:636355 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-C nanocomposites covering every possible combination of C and SiC were prepd. by chem.-vapor deposition. The specific compns. of the deposits were controlled by changing the Si/C molar ratio in the source gases at deposition temps. 1673-1873 K and total gas pressures 6.7-40 kPa using the SiCl4-C3H8-H2 system. The prediction, based on the thermodn. calcn. on compn., morphol. and deposition rate, was compared with exptl. results. The optimal deposition conditions predicted by the calcns. were nearly in agreement with the exptl. results.

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Thermomechanical properties and oxidation resistance of zirconia CVI-matrix composites: 1 - mechanical behavior. Minet, J.; Langlais, F.; Quenisset, J. M.; Naslain, R. Lab. Chim. Solide, Univ. Bordeaux, Talence, Fr. Journal of the European Ceramic Society (1989), 5(6), 341-56. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 113:216698 AN 1990:616698 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mech. behavior of various ZrO2-based fibrous composites was studied at ambient and high temps. The composites were prepd. by ZrO2-chem.-vapor infiltration (CVI) densification, from preforms made of Al2O3 or C fibers consolidated with a small amt. of Al2O3, pyrocarbon or hexagonal BN. When loaded under compression at room temp., 2-dimensional (2-D) C-C/ZrO2 composites exhibit mech. behavior similar to that already reported for the related 2-D-C-C/SiC, 2-D-C-C/B4C, 2-D-C-C/TiC or 2-D-C-C/BN materials with: a linear elastic domain, a damaging domain prior to failure, and an anisotropy which decreases as ZrO2 vol. fraction is raised. Under 3-point bending, the Al2O3-ZrO2 composites behave, at room temp., in a nonbrittle manner when the preform has been consolidated by BN, with crack deviation and pull-out phenomena. The variations of the stiffness and strength vs. ZrO2 vol. fraction obey exponential laws at room temp. Finally, the Al2O3-ZrO2 composites keep their strength and rigidity .ltorsim.1000 under an atm. of Ar/H.

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Low-temperature MOCVD of silicon-based ceramic films. Du, Honghua; Bae, Yongwoong; Gallois, Bernard; Gonsalves, Kenneth E. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 331-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196275 AN 1990:596275 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A liq. methylsilazane compd., [MeSiHNH]n, was used, with H2, NH3, and a 60%/40% NH3/H2 mixt., to deposit Si-based ceramic films in a metalorg. chem.-vapor-deposition (MOCVD) reactor at 873-1073 K. Characterization of the films by ellipsometry and FTIR and Auger electron spectrometry showed that the methylsilazane was pyrolyzed to form Si carbonitride in H2 and Si3N4 in both NH3 and NH3/H2, with the incorporation of appreciable amts. of O. The deposition rate increased and the activation energy decreased in order from NH3-, NH3/H2-, and H2-[MeSiHNH]n gas mixts. The temp. dependence of the structural d. of the films increased in the same order.

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Modeling transport, reaction, and pore structure evolution during densification of cellular or fibrous structures. Sotirchos, Stratis V.; Tomadakis, Manolis M. Dep. Chem. Eng., Univ. Rochester, Rochester, NY, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 73-8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196263 AN 1990:596263 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is developed to describe mass transport, reaction, and structure evolution during densification of porous media of initially fibrous or cellular structure. The use of Monte Carlo simulation procedures for detg. the variation of the local (av.) structural properties of the porous structure and of the effective diffusion coeffs. in the porous medium with the porosity is also discussed, and results are presented for Knudsen diffusion in cellular or fibrous media. The model is used to theor. study the transient behavior of the densification process during prepn. of SiC/SiC ceramic matrix composites by chem. vapor infiltration of porous preforms. Particular emphasis is placed on the investigation of the effects of pressure pulsing on the d. gradients in the densifying structure.

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Analytical simulation of an improved CVI [chemical vapor infiltration] process for forming highly densified ceramic composites. Tai, Nyan Hwa; Chou, Tsu Wei. Cent. Compos. Mater., Univ. Delaware, Newark, DE, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 61-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196261 AN 1990:596261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A model for chem.-vapor infiltration (CVI) under pressure and temp. gradients is applied to the study of deposition of SiC from the pyrolysis of MeSiCl3 within a 3-dimensional (3-D) woven fibrous preform. The model considers the infiltration of reactants into a preform with temp. gradients by applying a pressure gradient between the vapor inlet and outlet; it also takes into account the variation in concn. of the vapor precursor. A quasi-steady-state approach was adopted to stimulate the matrix deposition in a 3-D unit cell. The d. distribution, consolidation profile, and total fabrication period were theor. predicted.

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Formation of novel sintered composites by high-pressure crystallization of amorphous ceramics. Onodera, Akifumi; Takahashi, Norikazu; Yoshihara, Haruyuki; Nakae, Hiroyuki; Matsunami, Yukio; Hirai, Toshio. Fac. Eng. Sci., Osaka Univ., Toyonaka, Japan. Journal of Materials Science (1990), 25(9), 4157-61. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:176879 AN 1990:576879 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A combination of chem.-vapor deposition (CVD) and high-pressure (HP) sintering methods were used to prep. the zincblende form of BN (z-BN)-based ceramic composites. The CVD method provides amorphous B-N-X (X = Al, Si, or Ti). The HP method renders the amorphous samples cryst., and decompn. into z-BN plus the resp. nitride (e.g., -Si3N4) occurs. Compacts of the composites are obtained by in situ sintering under high pressure. The compacts exhibit peculiar microstructures composed of z-BN nanocrystals homogeneously dispersed in the nitride matrixes.

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Characterization of ceramic matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M., Jr.; More, K. L.; Sheldon, B. W.; Besmann, T. M. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 273-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:176787 AN 1990:576787 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A process for the prepn. of fiber-reinforced SiC composites by chem.-vapor deposition has been developed at Oak Ridge National Lab. Composites are prepd. by infiltrating fibrous preforms with reactant gases that decomp. at elevated temps. to deposit SiC between and around the fibers. Because the infiltration process utilizes both temp. and pressure gradients, SiC is deposited under conditions that vary considerably from the hot face to the cool face of the composite. Matrix characterization of composite samples by TEM and Raman spectroscopy are described.

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Analysis and testing of the metal parts furnace for the demilitarization of chemical warfare munitions. Fournier, Ronald L.; Horne, Deane A.; Rinker, Franklin G.; Jackson, Kerm. Dep. Chem. Eng., Univ. Toledo, Toledo, OH, USA. Journal of Hazardous Materials (1990), 23(1), 1-20. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 113:137967 AN 1990:537967 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At the Chem. Agent Munitions Disposal System (CAMDS) located to Tooele Army Depot, Utah, the munition metal parts contg. <5% residual agent are thermally decontaminated in roller hearth-type furnace, the Metal Parts Furnace (MPF). The drained munitions are heated to >1000F for 15 min to insure complete destruction of any remaining agent residue. During this heating process the residual agent vaporizes. The vaporized agent burns within the MPF and the MPF afterburner prior to treatment of the combustion product gases in the pollution abatement system. Agent vaporization is a rapid unsteady process with peak Btu loadings on the MPF of 10 million Btu/h. Since there are 14 different munition types contg. 3 different types of chem. agents, ranging from a load of 96 105-mm projectiles contg. as little as 0.08 lbs of the nerve agent GB per projectile to a ton container with 80 lbs of the nerve agent VX, the control system of the MPF system must be flexible enough to handle a wide variety of thermal loads. To evaluate and predict the performance of the MPF, tests were performed at CAMDS by using a variety of munitions contg. chem. agent simulants. The simulants were selected on the basis of comparable b.ps., heat of vaporization, and heat of combustion. A math. model of the MPF was developed to predict the heating rate of the munition and the vaporization profiles of the agents and their simulants. The results of the model were compared to simulant testing in ton containers at CAMDS. The results show good agreement with the math. model predictions.

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Powder preparation and compaction behavior of fine-grained yttria-doped tetragonal zirconia polycrystals (Y-TZP). Groot Zevert, W. F. M.; Winnubst, A. J. A.; Theunissen, G. S. A. M.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of Materials Science (1990), 25(8), 3449-55. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:119698 AN 1990:519698 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Two wet chem. prepn. methods are described for Y2O3-doped tetragonal ZrO2 powders. Both methods yield powders with an extremely small crystallite size (8 nm) and a narrow size distribution. The agglomerate and aggregate structure of these powders was investigated by several techniques. Gel pptn. from an alkoxide soln. in water (alkoxide synthesis) results in a ceramic powder with irregular-shaped weak and porous agglomerates, which are built up from dense aggregates with a size of 18 nm. Gel ppts. formed from a metal-chloride soln. in NH3 (chloride synthesis) do not contain aggregates. Both types of agglomerate are fractured during isostatic compaction. Hydrolysis and washing under (strong) basic conditions probably decrease the degree of aggregation. The aggregate morphol. and structure are key parameters in the microstructure development during sintering of a ceramic. Several characteristics of these powders are compared with those of a com. one (Toyo Soda TZ3Y).

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Preparation of titanium carbide plates by chemical vapor deposition. Jiang, Chorn Cherng; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(2A), 1086-93. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 112:144385 AN 1990:144385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Thick TeCx plates were prepd. by chem.-vapor deposition using TiCl4, CCl4, and H2 as source gases at deposition temps. (Tdep) 1573-1873 K, total gas pressures (Ptot) 4-40 kPa, and source gas molar ratio [CCl4/(TiCl4 + CCl4)] (mc) 0.13-0.91. The effects of deposition conditions on the microstructure, preferred orientation, deposition rate, lattice parameter, and compn. were studied. A plate-like TiCx was obtained at mc 0.5. The (110) plane was preferably oriented parallel to the deposition surface at Tdep 1673-1873 K. The deposition rates showed a strong mc dependence and the max. rate was found at mc = 0.3-0.5. The activation energies for the formation of TiCx plates were 86 kJ/mol at Ptot = 4 kPa and 95 kJ/mol at Ptot = 40 kPa. When mc values were 0.13-0.51, the lattice parameter increased with increasing mc >0.72 at all Tdep. The at. ratio (C:Ti) for TiCx was 0.6-1.0 depending on deposition conditions.

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Characterization and processing of CVD powders for fabrication of composite and compound ceramics. Hori, Saburo; Shigaki, Yoshiki; Hirata, Yoshihiro; Yoshimura, Masahiro; Somiya, Shigeyuki. Kureha Chem. Ind. Co., Ltd., Tokyo, Japan. Materials Research Society Symposium Proceedings (1989), 155(Process. Sci. Adv. Ceram.), 3-12. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 112:144279 AN 1990:144279 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Two-component oxide powders were prepd. in the systems Al2O3-ZrO2, AliO3-TiO2, and Al2O3-SiO2 by a chem.-vapor deposition (CVD) method using a combustion flame for the purpose of fabricating resp. composite or compd. ceramics. The CVD powders were spherical and ultrafine (av. 30-70 nm) with log-normal size distribution, and exhibited either very homogeneous or nanoheterogeneous structure and crystallog. metastability in phases and solid soln. By starting from these CVD powders, uniform microstructures were achieved in the sintered products and better sinterability and novel microstructure became possible due to the metastability which reflected the formation mechanism of 2-component powders at high temps. CVD powders, previously considered difficult to sinter, proved to be excellent starting materials for fabrication of composite and compd. ceramics when improved processing methods were applied.

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Preparation of silicon carbide powders by chemical vapor deposition from the silane-methane-hydrogen system. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1989), 24(11), 3824-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 112:41177 AN 1990:41177 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor deposition (CVD) from the SiH4 + CH4 + H2 system was used to prep. -SiC powders at 1523-1673 K. The powders obtained at 1673 K were single-phase -SiC contg. neither free Si or free C. The powders obtained at <1623 K were composite powders contg. free Si. The carburization ratio (SiC/SiC + Si)) increased with increasing reaction temp. and total gas flow rate, and with decreasing reactant concn. The av. particle sizes detd. by TEM were 46-114 nm. The particle size increased with increasing reaction temp. and gas concn. but decreased with increasing gas flow rate. The -SiC particles obtained at <1623 K consisted of a Si core and a -SiC shell, as opposed to the -SiC particles obtained at 1673 K, which were hollow. IR absorption peaks were obsd. at 940 and 810 cm-1 for particles contg. a Si core, whereas a single peak at .apprx.830 cm-1 with a shoulder at .apprx.930 cm-1 was obsd. for the -SiC hollow particles. The lattice parameter of -SiC having a carburization ratio <70 wt. %, was larger than that of bulk -SiC and decreased with increasing carburization ratio. However, when the carburization ratio was >70 wt.%, the lattice parameter became approx. equal to that of bulk -SiC.

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The interaction of chemical kinetics and diffusion in the dynamics of chemical vapor infiltration. Middleman, Stanley. Dep. Ames/Chem. Eng., Univ. California-San Diego, La Jolla, CA, USA. Journal of Materials Research (1989), 4(6), 1515-24. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 112:24678 AN 1990:24678 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The classical model of chem. vapor infiltration treats diffusion and surface reaction in a representative cylindrical pore. Two significant modifications to that approach are presented. One accounts for more complex chem. by allowing for both gas-phase and surface reactions which lead to film growth. The other couples the pore model to a reactor model for the region external to the porous preform. The results demonstrate that it is possible to select chem. schemes that yield densification from the interior to the exterior of the preform, thus avoiding premature trapping of interior voids.

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The colloid chemistry of ceramic membranes. Xu, Qunyin; Gieselmann, Mary J.; Anderson, Marc A. Water Chem. Program, Univ. Wisconsin, Madison, WI, USA. Polymeric Materials Science and Engineering (1989), 61 889-93. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 111:238343 AN 1989:638343 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The colloid chem. in sol-gel processing for prepg. particulate ceramic membranes is a key tool used for tailoring membrane structures. The chem.-phys. variables in hydrolysis and peptization processes control the particle nature in sols, which is directly related to the gelation process and particle packing geometry in the hydrogel. The pore structure of membranes is mainly detd. by the size of primary particles rather than by that of aggregates. TiO2 membranes with mean pore diam. 1.8-3.0 nm were prepd. from primary particles <10 nm. A larger variety of pore structures in membranes, including broader pore size range and more narrow size distributions, can be made by controlling sol-gel processing conditions to serve a large range of applications.

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Chemical vapor deposition of ultrafine ceramic structures. Gallois, B. M.; Mathur, R.; Lee, S. R.; Yoo, J. Y. Dep. Mater. Metall. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1989), Volume Date 1988, 132(Multicompon. Ultrafine Microstruct.), 49-60. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 111:238219 AN 1989:638219 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ultrafine ceramic structures based on the nitrides and carbides of Ti and Si were prepd. in a computer-controlled hot-wall chem.-vapor deposition (CVD) reactor. Layered deposits were produced by pulsing the reactant gases judiciously under software control. The development of a columnar structure which is endemic to most CVD materials was suppressed. Skeletal structures of filaments were grown with appropriate catalysts by the vapor-liq.-solid mechanism and immediately infiltrated in situ with different materials to produce filament-reinforced composite coatings. Ultrafine-grained C films and filaments were grown from CH4-H mixts. by plasma-assisted CVD. The microstructural features of these materials are of the order 20-100 nm. The subgrain structure detd. by Raman spectroscopy varies at 2-3 nm.

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Stability to moisture for chemically vapor-deposited boron nitride. Matsuda, T. Japan Met. and Chem. Co. Ltd., Gunma, Japan. Journal of Materials Science (1989), 24(7), 2353-7. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 111:82901 AN 1989:482901 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor-deposited BN (CVD-BN) plates, prepd. from the BCl3-NH3-H2 gas system, were studied in terms of stability to moisture by IR spectroscopic measurement, chem. anal., and TG. The synthesis conditions of CVD-BN plates have a large effect on their stability to moisture. The stability of CVD-BN plates prepd. under a total gas pressure (Ptot) of 10-60 torr degraded as the deposition temp. (Tdep) decreased. The CVD-BN plates with transparent and isotropic properties, which were prepd. at <1400 and >10 torr, showed poor stability to moisture. The CVD-BN plates synthesized under 5 torr had high moisture-resistance, even at a Tdep 1400. An IR absorption spectra revealed that the unstable species existing in CVD-BN plates had changed to ammonium borate hydrates by reacting with moisture in the atm. The stability to moisture for CVD-BN plates degraded as the deposition rate increased, esp. for the CVD-BN plates prepd. at 1400.

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Interfacial chemistry-structure and fracture of ceramic composites. Schoenlein, L. H.; Jones, R. H.; Henager, C. H.; Schilling, C. H.; Gac, F. Pac. Northwest Lab., Richland, WA, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 313-21. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119795 AN 1989:119795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interfacial chem. and phases of SiC-reinforced Si3N4 composites were studied by TEM with assocd. x-ray energy-dispersive spectroscopy microanal. and Auger electron spectroscopy. Hot-pressed Si3N4 (HPSN) composites reinforced with Nicalon SiC fibers or Tateho SiC whiskers and reaction-bonded Si3N4 (RBSN) composites reinforced with uncoated or coated VLS SiC whiskers were evaluated. In the Nicalon fiber-reinforced HPSN, an interfacial phase composed of a layer of amorphous C and an adjacent layer of graphitic C was obsd. and is believed to assist fiber pull-out during fracture of the composite. However, the fracture strength and toughness of these composites were considerably less than those of unreinforced HPSN. HPSN composites reinforced with Tateho SiC whiskers contained an interfacial phase believed to be similar to the intergranular phase found in the HPSN matrix. In RBSN composites fabricated with an Fe2O3 sintering aid, the VLS SiC whiskers were severely faceted by a reactive Fe silicide phase despite C, BN, or SiO2 coatings on the whiskers. When no sintering aid was used, the uncoated whiskers were not degraded and appeared to be strongly bounded to the RBSN matrix. The composites reinforced with SiO2-coated whiskers possessed the highest fracture strength and toughness, and the composites reinforced with the BN-coated whiskers possessed the lowest fracture strength and toughness.

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Theoretical analysis of chemical vapor infiltration in ceramic/ceramic composites. Tai, Nyan Hwa; Chou, Tsu Wei. Dep. Mech. Eng., Univ. Delaware, Newark, DE, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 185-92. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119788 AN 1989:119788 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A model for the deposition of Al2O3 and TiC with a ceramic fiber bundle from the chem. reactions was studied. The model considers vapor diffusion, chem. reaction on the inner surface of the capillary, deposition film growth, porosity, and effects of reactant compns. at various reactor temps. and pressures. Binary, multicomponent diffusion and Knudsen diffusion account for the different stages of the chem.-vapor-infiltration (CVI) process. Furthermore, both diffusion-controlled and reaction-controlled processes were examd. to det. the dominating process in CVI.

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Fracture behavior of 3-D braided Nicalon/silicon carbide composite. Yang, J. M.; Chou, J. C.; Burkland, C. V. Dep. Mater. Sci. Eng., Univ. California, Los Angeles, CA, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 163-8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119785 AN 1989:119785 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture behavior of a 3-dimensional (3-D) braided Nicalon fiber-reinforced SiC matrix composite processed by chem. vapor infiltration (CVI) was studied. The fracture toughness and thermal shock resistance under various thermomech. loadings were characterized. A tough and durable structural ceramic composite can be achieved through the combination of 3-D fiber architecture and the low-temp. CVI processing.

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Chemical interactions in ceramic and carbon-carbon composites. Luthra, Krishan L. Corp. Res. Dev., Gen. Electr. Co., Schenectady, NY, USA. Materials Research Society Symposium Proceedings (1988), 125(Mater. Stab. Environ. Degrad.), 53-60. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 110:119676 AN 1989:119676 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 10 refs. The useful lives of many ceramic composites are affected, if not controlled, by chem. interactions between various constituents and the gas environment. Thermochem. calcns. are extremely valuable in evaluating these concerns. Examples of many possible concerns are presented. The usefulness of a thermochem. approach is demonstrated by a somewhat detailed discussion of the oxidn. protection of C/C composites. This includes discussion of the various possible rate-limiting steps and the detrimental effects of CO gas formed as a result of C oxidn.

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Consolidation of silicon nitride (Si3N4) powder-preform by infiltration of boron nitride using the pulse CVI [chemical vapor infiltration] process. Sugiyama, Kohzo; Ohsawa, Yoshimi. Fac. Eng., Nagoya Univ., Nagoya, Japan. Journal of Materials Science Letters (1988), 7(11), 1221-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 110:62400 AN 1989:62400 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

BN infiltration into a Si3N4 powder preform, as a model of pulse chem.-vapor infiltration and means of consolidating powder preforms, is reported. The resulting samples were studied using SEM and electron microprobe x-ray microanal. and the effect on flexural strength was detd. The BN matrix deposits tightly among the particles of Si3N4.

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Bonding in aluminum phosphate ceramics prepared at low temperatures. Silsbee, Michael R.; Roy, D. M. Dep. Mater. Sci. Eng., Pennsylvania State Univ., University Park, PA, USA. Materials Research Society Symposium Proceedings (1988), 114(Bonding Cem. Compos.), 295-300. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 109:114885 AN 1988:514885 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The process of chem. binding involves the transformation of a powder into a single contiguous mass. This process is likely to involve considerable structural rearrangement. The presence of a liq. phase offers a low energy pathway for the movement of ions required to achieve this rearrangement. The presence of the liq. phase alone is not sufficient to insure a successful transformation. Thermodn. considerations govern the ultimate reaction products, and the structure and chem. reactivity of the starting materials play a major role in the binding reaction. The ability of the solid phases to release ions for transport is important. Al(OH)3 served as a source of Al ions that reacted with the phosphate ions already in soln. to form an amorphous phase binding the less reactive -Al2O3 and AlPO4 particles together. The addn. of relatively small amts. of amorphous SiO2 altered the reaction products rather drastically.

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Detectors in battle. Powell, R. J. UK. Chemistry in Britain (1988), 24(7), 665, 667, 669. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 109:78950 AN 1988:478950 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The operating principle and design of 2 chem. warfare agent detectors are discussed. Both of the detectors have electrochem. cells which respond to nerve agents (tabun, sarin, VX) and to HCN.

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Density and deposition rate of chemical-vapor-deposited boron nitride. Matsuda, Toshitsugu; Nakae, Hiroyuki; Hirai, Toshio. Japan Met. Chem. Co., Ltd., Gunma, Japan. Journal of Materials Science (1988), 23(2), 509-14. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 108:191407 AN 1988:191407 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The d. and deposition rate characteristics were studied of chem.-vapor-deposited BN (CVD-BN) plates synthesized by use of the BCl3-NH3-H2 system at deposition temp. (Idep) 1200-2000 and total gas pressure (Ptot) 5-60 torr. At Ptot, all the CVD-BN plates synthesized at each Tdep above 1300 had a d. >2.0 g/cm3 and thus showed no noticeable dependence on Idep. Over the Ptot range from 10-60 torr, on the other hand, the d. of the plates reached the max. of 2.08 g/cm3 at Tdep 2000. As Tdep was lowered, the d. decreased to a min. of 1.40 g/cm3. The deposition rate varied with both Tdep and Ptot and showed a max. value under a certain Ptot at a given Tdep. The value of Ptot where the deposition rate becomes max. changed depending on the Tdep. The max. deposition rate was 0.6 mm/h for the CVD-BN plates when the d. was <2.0 g/cm3 and 0.4 mm/h when the d. was >2.0 g/cm3. The effects of deposition conditions on the characteristics of the d. and deposition rate are discussed in terms of the structure and deposition mechanism.

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Synthesis and catalytic activity of surfactant analogs of 4-(dimethylamino)pyridine. Katritzky, Alan R.; Duell, Bradley L.; Durst, H. Dupont. Dep. Chem., Univ. Florida, Gainesville, FL, USA. Langmuir (1987), 3(6), 976-82. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 107:197237 AN 1987:597237 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Seven surfactants have been synthesized, each contg. a 4-(dialkylamino)pyridine moiety carrying an 8-10-carbon chain with an attached polar or charged group. Two of the compds. fall into the neutral charge category, two are cationic, two are zwitterionic, and one is anionic. Rates of hydrolysis of 4-nitrophenyl hexanoate and 1,2,2-trimethylpropyl methylphosphonofluoridate by each surfactant were measured, both with and without added cetyltrimethylammonium chloride (CTAC). The most active deriv. was sodium 10-[butyl(4-pyridinyl)amino]decyl sulfate. The present catalysts, in contrast to the iodosobenzoates, show poor rate enhancements in the hydrolysis of fluorophosphonates.

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High temperature evaporation characteristics of amorphous Si3N4-C composite prepared by chemical vapor deposition. Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1987), 22(8), 2842-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 107:119869 AN 1987:519869 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Evapn. characteristics of amorphous Si3N4 and amorphous Si3N4-C composite (6 wt.% C) prepd. by the chem.-vapor deposition (CVD) were studied at 1400-1650 in a vacuum of .apprx.10-6 torr. The wt. loss due to the evapn. was linear with time for all samples tested. The evapn. rate of the amorphous CVD-(Si3N4-C) composite was 50-70% of that for the amorphous CVD-Si3N4. The activation energy for evapn., calcd. from the temp. dependence of the evapn. rates, was .apprx.160 kcal/mol for both samples. The C dispersed in the amorphous CVD-(Si3N4-C) composite reacted at the time of heat-treatment with the amorphous Si3N4 matrix and formed -SiC particles. The -SiC particles were .apprx.100 nm in diam. and connected to form a 3-dimensional network structure.

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Influence of synthesis chemistry on alumina-zirconia powder characteristics. Debsikdar, J. C. Battelle Columbus Div., Columbus, OH, USA. Journal of Materials Science (1987), 22(6), 2237-47. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 107:44957 AN 1987:444957 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. polymn., destabilization of mixed sols, and copptn. chem. processes were used to synthesize 80Al2O3.20ZrO2 (wt.%) powders. The elementary particles produced by each of these processes were 1.5-3.0 nm in size and were amorphous to electron diffraction. The powders were evaluated in terms of wt. loss (TGA), thermal characteristics (DTA), surface area (Brunauer-Emmett-Teller equation), pore size distribution, d. at different temps., and crystn. behavior (x-ray diffraction). The physicochem. characteristics and crystn. behavior of these chem. derived powders were significantly affected by the chem. of the powder synthesis. The powders produced by the chem. polymn. and the colloidal processes retained the tetragonal ZrO2 phase during cooling from 1600, but significant transformation of tetragonal to monoclinic ZrO2 occurred in the copptd. powder under identical conditions. The 1550-calcined powder derived by the chem. polymn. process retained a substantial amt. of tetragonal ZrO2 after annealing at 1000 for 72 h. The av. Al2O3 and ZrO2 crystal size of the calcined powders, calcd. by the Scherrer equation, was 20-80 nm.

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Characterization of wurtzitic boron nitride compacts. Singh, Bhanu Pratap. Natl. Phys. Lab., New Delhi, India. Journal of Materials Science (1987), 22(2), 495-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 106:161234 AN 1987:161234 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The properties of sintered polycryst. wurtzitic BN compacts were studied including the cryst. phases that formed at high temp. and pressure, compn., BN and binder particle size distribution, and hardness. Wurtzitic BN, cubic BN, TiC/TiN solid soln., TiB, and TiB2 were the cryst. phases obsd. The BN and binder particle size distributions were comparable (1-5 m), with .apprx.80% of the particles 2-3 m. Wt. percentages of different elements present in these compacts were detd. The av. Knoop hardness values under 500 g load and the variation of hardness as a function of position on the specimen surface were studied.

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Morphological and mechanical characterization of ceramic composite materials. Chermant, J. L.; Gomina, M.; Osterstock, F. ISMRa, Univ. Caen, Caen, Fr. Materials Science Research (1986), 20(Tailoring Multiphase Compos. Ceram.), 615-29. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 106:124512 AN 1987:124512 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

C fiber-reinforced (chem. vapor-deposited SiC) ceramic composites were tested in 3-point bending in 3 orientations of the notch prior to the applied stress. For the 2 main orientations, load-unloading sequences were performed to investigate the rupture parameters using the M. Sakai et al. (1983) method. The very good mech. behavior of these materials are due to the energy dissipative effect of the reinforcement. For the weaker orientation, an empirical method is proposed to measure the compliance at any point of the load-displacement curve.

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Chemical vapor deposition of Si3N4 from a gas mixture of Si2Cl6, NH3 and H2. Motojima, Seiji; Iwamori, Noriyuki; Hattori, Tatsuhiko. Fac. Eng., Gifu Univ., Gifu, Japan. Journal of Materials Science (1986), 21(11), 3836-42. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 105:231265 AN 1986:631265 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Si3N4 layers were prepd. on a quartz substrate from a gas mixt. of Si2Cl6, NH3, and H2 under a reduced pressure and at 800-1300. Amorphous Si3N4 layers that were dense and adherent to the substrate were obtained at 800-1100. On the other hand, -Si3N4 layers were obtained at 1200 and a source-gas ratio (N/Si) of 1.33-1.77. The lowest deposition temp. of amorphous Si3N4 was .apprx.700. The microhardness of amorphous Si3N4 obtained at 800-1100 was 2400-2600 kg/mm2 (load: 50 g), and that of -Si3N4 obtained at 1200 was 3400 kg/mm2. Chlorine contents in the Si3N4 layer decreased with increasing deposition temp. and source-gas ratio (N/Si), and with decreasing total pressure.

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Innovative chemical/ceramic directions. Morgan, P. E. D. Rockwell Int. Sci. Cent., Thousand Oaks, CA, USA. Materials Research Society Symposium Proceedings (1986), 73(Better Ceram. Chem. 2), 751-63. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 105:213019 AN 1986:613019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 37 refs., of chem. methods of ceramic prepn. including discussions of the sol-gel process, nanostructures, polymer pyrolysis, fused salt synthesis of chalcogenides, transformation toughening, liq. boundary phases, and Si3N4 prepn. from SiCl4 and (SiS2 + SiCl4).

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Microhardness and internal stress of silicon nitride (Si3N4)-silicon carbide films prepared by plasma CVD. Kamata, Kiichiro; Aizawa, Naoyoshi; Moriyama, Minoru. Technol. Univ. Nagaoka, Nagaoka, Japan. Journal of Materials Science Letters (1986), 5(10), 1055-7. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 105:196083 AN 1986:596083 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microhardness and internal stress of Si3N4-SiC films prepd. by plasma chem.-vapor deposition were detd. in relation to use of the coatings for high strength and wear resistance. The films had compns. indicated by SiNxCy where x = 0-1.42 and y = 0-1.04. The relation between the crack length in a film coating on glass substrates (induced by a Vickers indentor) and the internal stress is discussed.

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Hybridization between silicon nitride (Si3N4) and silicon carbide films by plasma CVD. Kamata, Kiichiro; Maeda, Yuuji; Moriyama, Minoru. Technol. Univ. Nagaoka, Nagaoka, Japan. Journal of Materials Science Letters (1986), 5(10), 1051-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 105:196082 AN 1986:596082 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hybrid SiC-Si3N4 films were prepd. by charge-coupled plasma chem.-vapor deposition from SiH4, NH3, CH4 (or C2H4), and H2 reaction gases. Homogeneous amorphous films were easily obtained. The C, N, and Si contents of the films were detd. Grains or phase boundaries were not obsd. using TEM. The n, IR absorption peak position, and optical band gap of the films varied continuously with changing amts. of each component in the Si3N4-SiC films. These results and TEM observations indicate that the films are not a mixt. of Si3N4 and SiC clusters. but are hybrid materials in which Si, N, and C atoms are blended on an at. scale.

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Zirconia: ceramic engineering's toughness challenge. Fisher, Greg. Dir. Tech. Serv., ACerS, USA. American Ceramic Society Bulletin (1986), 65(10), 1355-60. CODEN: ACSBA7 ISSN: 0002-7812. Journal; General Review written in English. CAN 105:195989 AN 1986:595989 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 54 bibliog. refs., of the chem. and properties of ZrO2 ceramics and the relations of these characteristics to ceramic toughness.

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Hydrolysis of mustard derivatives in aqueous acetone-water and ethanol-water mixtures. Yang, Yu Chu; Ward, J. Richard; Luteran, Thomas. Res. Dir., U. S. Army Chem. Res. Dev. cent., Aberdeen Proving Ground, MD, USA. Journal of Organic Chemistry (1986), 51(14), 2756-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 105:42037 AN 1986:442037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Kinetic data for the hydrolysis of ClCH2CH2SR (R = Me, Et) in the title solvents were interpreted in terms of an SN1 mechanism with anchimeric assistance of the S atom to form a cyclic sulfonium ion as an intermediate. A finite and neg. Cp.thermod. was obsd.

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Synthesis of fiber-reinforced silicon carbide composites by chemical vapor infiltration. Stinton, David P.; Caputo, A. J.; Lowden, Richard A. Oak Ridge Natl. Lab, Oak Ridge, TN, USA. American Ceramic Society Bulletin (1986), 65(2), 347-50. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 104:93916 AN 1986:93916 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A process was developed for the fabrication of fiber-reinforced SiC composites by chem.-vapor infiltration. Infiltration times of the low-d. fibrous structures were reduced significantly from previous processes by utilizing simultaneously a thermal gradient and forced gas flow. Synthesis of composites in this fashion produced specimens with high flexural strengths and with strain tolerances which significantly exceeded that of monolithic SiC.

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Creep of chemically vapor deposited silicon carbide fibers. Dicarlo, James A. Lewis Res. Cent., Natl. Aeronaut. Space Adm., Cleveland, OH, USA. Journal of Materials Science (1986), 21(1), 217-24. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 104:55136 AN 1986:55136 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The creep, thermal expansion, and elastic modulus properties of chem. vapor-deposited SiC fibers were detd. at 1000-1500. Creep strain increased logarithmically with time, monotonically with temp., and linearly with tensile stress at 600 MPa. The controlling activation energy was 480  20 kJ/mol. Thermal pretreatments at .apprx.1200 and 1450 significantly reduced fiber creep. These results coupled with creep recovery observations indicate that at <1400 fiber creep is anelastic with a negligible plastic component. This allowed a simple predictive method to be developed for describing fiber total deformation as a function of time, temp., and stress. Mechanistic anal. of the property data suggests that fiber creep is the result of -SiC grain-boundary sliding, controlled by a small percentage of free Si in the grain boundaries.

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Mechanical properties of zirconia-toughened alumina ceramics from CVD powders. Hori, Saburo; Yoshimura, Masahiro; Somiya, Shigeyuki; Kurita, Ryuichi; Kaji, Hisatsugu. Res. Lab. Eng. Mater., Tokyo Inst. Technol., Yokohama, Japan. Journal of Materials Science Letters (1985), 4(4), 413-16. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 103:10304 AN 1985:410304 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and bending strength were measured on sintered ZrO2/-toughened Al2O3 samples which had been prepd. from a chem. vapor-deposited powder. Fracture toughness increased with ZrO2 addns. from 2.6 to 4.8 MPam1/2. Bending strength increased from 430 to 660 MPa with ZrO2 addns. up to 15 wt. % then droped to .simeq.500 MPa at 20-25 wt. % addn. X-ray anal. showed that the drop in bending strength corresponded to a drop in tetragonal phase content. Both the bending strength and fracture toughness increased .apprx.50% with 15 wt. % ZrO2 addn.

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Fracture energy of silicon nitride. Rice, R. W.; McKinney, K. R.; Wu, C. C.; Freiman, S. W.; Donough, W. J. M. Nav. Res. Lab., Washington, DC, USA. Journal of Materials Science (1985), 20(4), 1392-406. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 102:224933 AN 1985:224933 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture energy of Si3N4 made by hot pressing, reaction sintering, and chem. vapor deposition (CVD) was studied. Extrapolation of fracture energies to zero additive or porosity levels, as well as anal. of CVD Si3N4 all indicate an intrinsic fracture energy of 20-30 J/m. Higher fracture energies in dense bodies with increasing additive content, or in some more porous bodies (relative to expected porosity dependence) are assocd. with crack branching. In dense bodies such branching may arise due to microcracking from combined effects of crack tip stresses and mismatch stresses due to differences in properties, esp. thermal expansion, between Si3N4 and the additive or it reaction products. In porous bodies such branching appears to be due to spatial distribution of pores.

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A morphological study of silicon carbide prepared by chemical vapor deposition. Tsui, P.; Spear, K. E. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 371-80. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 102:171306 AN 1985:171306 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Surface morphologies of SiC deposits obtained via chem. vapor deposition (CVD) were studied as functions of substrate surface temp. and the concn. of the Si and C source material, MeSiCl3. Substrates of graphite and -SiC crystals were used. Explanations of the obsd. morphologies on graphite substrates and their marked changes with temp. are given in terms of chem. kinetics and mass transport arguments. The results of thermodn. calcns. were used to help explain the obsd. morphologies of the deposits on -SiC substrates.

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Preparation of amorphous silicon nitride-boron nitride composites by chemical vapor deposition. Hirai, Toshio; Goto, Takashi; Sakai, Tadashi. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 347-58. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 102:171304 AN 1985:171304 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor deposition of an Si-N-B system was studied by using SiCl4, NH3, H2 and B2H6 as source gases at deposition temps. of 1100-1300 and total gas pressures of 30-70 torr. The chem. compn. and d. of the deposits were measured. The structure of the deposits was investigated by x-ray diffraction and IR absorption techniques. The deposits were composed of amorphous Si3N4 and turbostratic BN.

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CVD of silicon nitride and its composites. Hirai, Toshio. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 329-45. CODEN: MTSRAY ISSN: 0076-5201. Journal; General Review written in English. CAN 102:171201 AN 1985:171201 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 33 refs., is given of the synthesis, structure, and some properties of Si3N4-based ceramics and composites prepd. by the chem.-vapor deposition process.

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Calculation of deposition conditions for silicon nitride from a SiL4-NH3 gas phase (L = H, Cl, Br, CH). Lartigue, J. F.; Ducarroir, M.; Armas, B. Lab. Ultra-Refract., CNRS, Odeillo/FontRomeu, Fr. Journal of Materials Science (1984), 19(9), 3079-89. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 102:11260 AN 1985:11260 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Deposition conditions yielding Si nitride are calcd. for a set of initial gaseous systems, by complex thermodn. equil. computations. The influence of temp., total pressure and reactant gas ratios on the compn. and yield of the condensed phase are shown for SiH4/NH3, SiCl4/NH3, SiBr4/NH3, Si(CH3)4/NH3, and SiH4/CH4/NH3 systems. The interest of such calcns. is to give an efficient approach for exptl. studies of vapor-deposition systems.

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Mechanical properties of chemically vapor deposited nonoxide ceramics. Niihara, Koichi. Tohoku Univ., Sendai, Japan. American Ceramic Society Bulletin (1984), 63(9), 1160-4. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 101:196815 AN 1984:596815 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Plates of chem. vapor-deposited nonoxide ceramics (Si3N4, SiC, and B4C) up to 3 mm thick were prepd. with high purity and d. at high deposition rates (>1 mm/h). High-resoln. electron microscopy of these materials reveals that there are no glassy layers or secondary phases at any grain boundaries and multiple-grain junctions. Thus, degrdn. of strength and toughness is not obsd. up to 1500; the strength and toughness of the Si3N4 and SiC increase with increasing temp. above 800 and 1100, resp. The effects of preferred orientation, grain size (residual internal stress), and stoichiometry on the mech. properties also were examd.

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Effects of water chemistry on the leach resistance of SYNROC C. Woolfrey, J. L.; Levins, D. M. Lucas Heights Res. Lab., Aust. Atomic Energy Comm., Sydney, Australia. Materials Research Society Symposium Proceedings (1984), 26(Sci. Basis Nucl. Waste Manage. 7), 663-70. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 101:62325 AN 1984:462325 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. durability of SYNROC-C was measured as a function of repository conditions, namely, temp., surface/vol. ratio, groundwater pH, and compn. The leach rate of SYNROC-C is less dependent on temp. than borosilicate glasses: activation energies range from 15-25 kJ mol-1 compared to 33-74 kJ mol-1 for glass. The rate of release from SYNROC-C is very low and independent of soln. compn. for the solns. studied. There is little variation in leach rate over the pH range 4-9, but at pH 2 the rate is up to 10 times higher. SYNROC-C leach rate is independent of flow rate or surface/vol. ratio for the mobile waste elements because of the unimportance of soln. satn. effects owing to the low concn. of dissolved solids. The differential leach rate decreases rapidly with time because, after initial leaching from grain boundaries and metastable minor phases, the highly insol. matrix protects the more leachable elements from further attack.

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Effects of variability of the base powder on the sintering of -silicon carbide. Williams, R. M.; Juterbock, B. N.; Peters, C. R.; Whalen, T. J. Ford Motor Co., Dearborn, MI, USA. Journal of Materials Science Letters (1984), 3(3), 265-7. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 100:160854 AN 1984:160854 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The importance of using starting powders with rigidly controlled chem. and crystallog. compn. and phys. characteristics for sintering of -SiC was investigated. Tests were conducted with 2 lots of sinterable -SiC from the same manufacturer and of the same grade. Differences in particle-size distribution, surface area, and chem. compn., most notably in free C and O contents, were obsd. The morphol. of the 2 materials was similar. The variations obsd. in the phys. properties of the ceramics and in temps. at which phase transformations occur were quite significant in comparison to the property differences of the starting materials.

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Microstructure of silicon nitride-titanium nitride composites prepared by chemical-vapor deposition. Hayashi, Shinsuke; Hirai, Toshio; Hiraga, Kenji; Hirabayashi, Makoto. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1982), 17(11), 3336-40. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 98:21091 AN 1983:21091 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The shapes and the distribution of TiN within Si3N4-TiN composites prepd. by the chem.-vapor deposition of a SiCl4-TiCl4-NH3-H2 system were examd. using an electron microscope. The TiN dispersion in the amorphous Si3N4 matrix was granular and its max. size was 3 nm. The TiN dispersions in - and -Si3N4 matrices were contained in their resp. crystal grains; however, the shape of the TiN dispersions in the -Si3N4 matrix was different from that in the -Si3N4 matrix. Granular TiN dispersions with an av. size of 10 nm were obsd. in the -Si3N4 matrix. The TiN dispersions in the -Si3N4 matrix were columnar with a diam. of several nm having its axis extended to the direction parallel to the c-axis of the -Si3N4 crystal.

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Density and deposition rates of amorphous CVD-silicon nitride (Si3N4) including carbon. Hirai, Toshio; Goto, Takashi. Res. Inst. Iron, Steel Other Metals, Tohoku Univ., Sendai, Japan. Journal of Materials Science (1981), 16(10), 2877-82. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 96:39625 AN 1982:39625 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Amorphous Si3N4 contg. uniformly distributed C was prepd. by chem. vapor deposition using SiCl4 vapor and NH3, H2, and C3H8 gases at desorption temps. (T) of 1100 to 1300 and at total gas pressures (P) of 30 to 70 torr. The d. of the amorphous Si3N4 deposit was 2.80-3.00 g/cm3, depending upon the deposition conditions. The rate of growth in thickness increased with increasing T and P and had the largest value of 0.6 mm/h at T = 1300, P = 70 torr, and C3H8 gas flow rates of 0 to 20 cm3/min. The activation energy of formation decreased from 38 to 20 kcal/mol with increasing P and C3H8 flow rate.

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The delayed neuropathic effects of nerve agents and some other organophosphorus compounds. Gordon J J; Inns R H; Johnson M K; Leadbeater L; Maidment M P; Upshall D G; Cooper G H; Rickard R L Archives of toxicology (1983 Feb), 52(2), 71-82. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 6847383 AN 83203413 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

[megalomania]

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Crystal chemistry and phase manipulation in Synroc. Vance, E. R.; Moricca, S.; Thorogood, G. J.; Lumpkin, G. R. Aust. Nucl. Sci. Technol. Organ., Menai, Australia. Key Engineering Materials (1991), 53-55(Austceram '90), 717-21. CODEN: KEMAEY ISSN: 1013-9826. Journal written in English. CAN 118:259605 AN 1993:259605 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The modification of the titanate ceramic Synroc was studied in terms of decreasing the unstable perovskite phase content, incorporation of process chems., and incorporation of Al-rich and actinide-rich nuclear wastes. A formulation of alkoxide-derived Al2O3 (7.8), BaO (11.7), CaO (8.3), TiO2 (54.1), and ZrO2 (18.1 wt.%) produced a mixt. of hollandite and zirconolite when sintered at 1200 in air, but .apprx.10 wt.% perovskite formed when hot pressed at 1200. A cor. formulation with 30 wt.% simulated high-level waste substitution for ZrO2 still produced a significant amt. of perovskite. Mg from fuel cladding was predicted to be incorporated in a MgTi2O5 phase which was demonstrated to be compatible with the other Synroc phases. P was incorporated in the alloy phase and as Ca3(PO4)2 at higher loadings. Satisfactory Cs leach rates were obtained when alkoxide-derived Synroc powders were hot pressed at 1400, but not all Al from the waste was incorporated in the Synroc phases at loadings as low as 10 wt.% Al2O3.

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Study of the efficacy of CC-2 and Fuller's earth combination as a decontaminant against sulfur mustard (mustard gas) dermal intoxication in mice. Kumar, Pravin; Sharma, U. S.; Vijayaraghavan, R. Def. Res. and Dev. Establ., Gwalior, India. Defence Science Journal (1991), 41(4), 363-6. CODEN: DSJOAA ISSN: 0011-748X. Journal written in English. CAN 116:189222 AN 1992:189222 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Decontamination efficacy of Fuller's earth and CC-2 independently; and in different combinations was evaluated against toxicity of sulfur mustard applied percutaneously on mice. Max. protection was obtained with fuller's earth and CC-2 in a combination of 80:20 (wt./wt.).

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Thermochemical analysis of chemical processes relevant to the stability and processing of silicon carbide-reinforced silicon nitride composites. Misra, A. K. NASA Lewis Res. Cent., Sverdrup Technol., Inc., Cleveland, OH, USA. Journal of Materials Science (1991), 26(24), 6591-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 116:65309 AN 1992:65309 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. processes relevant to the stability and processing of SiC-reinforced Si3N4 composites are examd. from a thermochem. point of view. The thermodn. stability of various interfaces, such as SiC-Si3N4, SiC-Si3N4-Si2ON2, and SiC-Si3N4-SiO2, is examd. as a function of temp. The temps. above which these interfaces become unstable are calcd., and the degrdn. of SiC during the processing of the composite is examd. The processing routes considered in this study include the reaction-bonded Si3N4 process, as well as pressure-assisted sintering processes in the presence of suitable sintering additives.

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Microstructural and chemical effects in alumina implanted with iron at 77 K and annealed in oxidizing or reducing atmospheres. McHargue, C. J.; Sklad, P. S.; White, C. W.; McCallum, J. C.; Perez, A.; Marest, G. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Materials Research (1991), 6(10), 2160-77. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 115:238068 AN 1991:638068 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Implantation of Fe (160 keV) into -Al2O3 at 77 K produces an amorphous surface layer for fluences 1016-1017 Fe ions/cm2. Measurements of short-range order were made by extended energy loss fine structure anal. The structure of amorphous Al2O3 produced by implantation of Fe at 77 K exhibits short-range order that differs from that produced by stoichiometric (Al + O) implants. This difference is manifested by changes in the Al-O near-neighbor bond length. The local environments of implanted Fe were detd. from conversion electron Moessbauer spectroscopy. The Fe resides in several different local environments consistent with the electronic states of Fe2+, Fe4+, and Fe0. The relative amt. of each environment depends on the concn. (fluence) of the implanted Fe ions. Regrowth of the amorphous zone during annealing occurs in the sequence amorphous Al2O3  -Al2O3  -Al2O3. The kinetics of regrowth and phase sepn. vary with implanted fluence with annealing atm. The higher the concn. of implanted Fe, the slower the formation of Fe-Al2O3 ppt. phases in oxidizing atmospheres and -Fe ppts. in reducing atmospheres.

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Microstructural and chemical effects in alumina implanted with iron at room temperature and annealed in oxidizing or reducing atmospheres. McHargue, C. J.; Sklad, P. S.; White, C. W.; Farlow, G. C.; Perez, A.; Marest, G. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Journal of Materials Research (1991), 6(10), 2145-59. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 115:238067 AN 1991:638067 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

RBS-ion channeling, TEM, and conversion electron Moessbauer spectroscopy were used to det. the structure of -Al2O3 implanted with Fe at room temp. Changes produced by post-implantation annealing in oxidizing and reducing atmospheres were followed using the same methods. Implantation of 160 keV Fe at room temp. produces a damaged but cryst. microstructure for fluences 1  1017 Fe ions/cm2. The Fe resides in a variety of local environments: 3 Fe2+ components, 1 Fe0 component, and 2 Fe4+ components. The relative amt. of each component varies with implantation fluence. Only the Fe0 component seems to be assocd. with 2nd-phase formation. In this case, 2 nm diam. -Fe particles were detected by TEM studies. Recovery of implantation-induced disorder in the Al- and O-sublattices occurs in 2 stages for annealing in O and in 1 continuous stage for H-annealing. The end state for Fe is Fe3+ for O anneals and Fe0 for H anneals. The pptd. phases obsd. are those to be expected from the equil. phase diagrams.

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Grain boundaries in high thermal conductivity aluminum nitride. McKernan, Stuart; Norton, M. Grant; Carter, C. Barry. Dep. Mater. Sci. Eng., Cornell Univ., Ithaca, NY, USA. Materials Research Society Symposium Proceedings (1991), 203(Electron. Packag. Mater. Sci. 5), 229-34. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 115:237865 AN 1991:637865 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The benefits of AlN as a substrate material for the electronics packaging industry appear to be limited by the deleterious effects of boundaries in the polycryst. material. Some observations on different types of boundary in AlN using several complementary techniques are reported. Energy dispersive x-ray spectroscopy anal. of grain boundaries shows that there is O at the grain boundaries, in agreement with previous work. No variation in the grain-boundary chem. was detected in the proximity of Y2O3-rich particles. The apparent increase in the O peak is probably due to an increased width of the oxide layer close to the triple junction.

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Modified CVD of nanoscale structures in and EVD of thin layers on porous ceramic membranes. De Haart, L. G. J.; Lin, Y. S.; De Vries, K. J.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of the European Ceramic Society (1991), 8(1), 59-70. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 115:213226 AN 1991:613226 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Expts. on the modified CVD and the electrochem. vapor deposition (EVD) of Y2O3-stabilized ZrO2 on porous substrates are reported. In the CVD stage, deposition occurs in a small (<20 m) region at the edge of the substrate, very likely leading to pore narrowing. This result illustrates the feasibility of the CVD technique for the modification of ceramic membranes to the (sub)nanometer scale. Film growth in the EVD stage is controlled by the in-pore diffusion of the O source reactant for short (<5 h) deposition times. The Y2O3/ZrO2 ratio in the deposited film is detd. by the ratio present in the vapor phase. Very thin (2 m) films can be deposited, which have a potential application in solid oxide fuel cells.

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Thermal stability of ceramic fiber in a CVI-processed silicon carbide matrix composite. Lin, W.; Yang, J. M. Dep. Mater. Sci. Eng., Univ. California, Los Angeles, CA, USA. Journal of Materials Science (1991), 26(15), 4116-22. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:140940 AN 1991:540940 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The thermal stability of the HPZ (Si-C-O-N system from hydridopolysilazane polymer precursor) fiber in a chem. vapor infiltration (CVI)-processed SiC matrix composite was studied. The mech. properties and fracture behavior of the untreated and SiC-coated fibers after thermal exposure at different temps. and atmospheres were characterized. At <1000, the strength degrdn. is negligible. However, severe degrdn. occurs at >1000 due to the evolution of CO, SiO, and other gaseous species. Also, pyrolytic C coating is needed to tailor the interfacial bond strength in the HPZ/SiC composites.

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Reaction chemistry at joined interfaces between silicon nitride and aluminum. Ning, X. S.; Okamoto, T.; Miyamoto, Y.; Koreeda, A.; Suganuma, K. Inst. Sci. Ind. Res., Osaka Univ., Osaka, Japan. Journal of Materials Science (1991), 26(15), 4142-9. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:118946 AN 1991:518946 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Joined interfaces of hot-isostatically pressed, additive-free Si3N4 ceramic/Al braze bonded at 1073 K for 18 ks or at 1473 K for 1.8 ks in a vacuum of 1.3 mPa and of -Si3N4 powder/Al powder interfaces bonded at 1073 K for 1.8 ks or 18 ks in the same vacuum were examd. by anal. TEM and x-ray diffraction. Mullite, some small crystals, and '-Sialon were detected at the interface of the ceramic/Al braze bonded at the low temp. and 15R AlN-polytype Sialon, '-Sialon, AlN, mullite, and SiO2-Al2O3 noncryst. material were detected at interfaces bonded at 1473 K. At the powder interface, AlN, and Si were also detected besides '-Sialon and the SiO2-Al2O3 noncryst. material, even though the bonding was conducted at the low temp. The interfacial reactions of the joints were affected not only by the bonding temp., but also by the oxide formed at the interface before bonding occurred.

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Thermo-mechanical properties and oxidation resistance of zirconia CVI matrix composites: 2 - thermal properties and oxidation resistance. Minet, J.; Langlais, F.; Naslain, R. Lab. Chim. Solide, Univ. Bordeaux, Talence, Fr. Journal of the European Ceramic Society (1991), 7(5), 283-93. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 115:118899 AN 1991:518899 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

ZrO2 matrix composites, prepd. by chem. vapor infiltration (CVI) from preforms (Al2O3 or C fibers) having a 2 (or pseudo-3-) dimensional character, were studied from a thermal behavior and resistance to oxidn. standpoint. The ZrO2 vol. fraction and residual porosity were within the 0.30-0.75 and 0.10-0.25 ranges, resp. The expts. were carried out 1500. Thermal expansion is low and almost reversible for the C-ZrO2 composites whereas it is more significant and partly irreversible for the Al2O3-ZrO2 composites. The Al2O3-ZrO2 composites exhibit an insulating character at >1000, comparable to that of sintered ZrO2, whereas the C-ZrO2 composites have a thermal cond. equal to that of sintered Al2O3 at >1000. The resistance to oxidn. by air is acceptable at moderate temps. and for short exposures. Under more severe conditions, damaging phenomena occur (i.e., grain growth, oxidn. of the C preform or BN interphase) which are detrimental to the mech. behavior.

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Efficacy of an oximate-based skin decontaminant against organophosphate nerve agents determined in vivo and in vitro. Sawyer, Thomas W.; Parker, Deborah; Thomas, Norleen; Weiss, M. Tracy; Bide, Richard W. Def. Res. Establ., Suffield/Ralston, AB, Can. Toxicology (1991), 67(3), 267-77. CODEN: TXCYAC ISSN: 0300-483X. Journal written in English. CAN 115:87007 AN 1991:487007 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Recent Canadian research efforts have been directed towards the development of a reactive skin decontaminant (RSD) lotion active against classical nerve agents and mustard. The formulation presently under study consists of a 1.25 m soln. of potassium 2,3-butanedione monoximate (KBDO) in polyethylene glycol Me ether 550. Although this formulation has shown good efficacy, concern has been expressed as to the potential toxicity of the reaction products of KBDO and organophosphate (OP) nerve agents. This report describes the high efficacy of this lotion in inactivating OPs as measured by the systemic toxicity of the OP/RSD mixts. in rats. In addn., primary cultures of chick embryo neurons were also used to test the efficacy of the RSD. By relating the anticholinesterase activity in these cultures of the OP/RSD mixt. to that of pure OP stds., a sensitive measure of the value of the RSD in inactivating tabun, sarin, soman and VX was obtained. Expts. with all 4 nerve agents in this in vitro system provided a good correlation with the in vivo data, and also indicated that the inactivation process was time- and agent-dependent and also related to the ratio of OP to RSD.

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Refractory ceramic foams: a novel, new high-temperature structure. Sherman, Andrew J.; Tuffias, Robert H.; Kaplan, Richard B. Ultramet Corp., Pacoima, CA, USA. American Ceramic Society Bulletin (1991), 70(6), 1025-7, 1029. CODEN: ACSBA7 ISSN: 0002-7812. Journal; General Review written in English. CAN 115:33992 AN 1991:433992 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 6 refs. Chem.-vapor infiltration (CVI) enables prepn. of the porous cellular structure. The fabrication of such a structure begins with the pyrolysis of a resin-impregnated thermosetting foam to obtain a reticulated C foam skeleton. The foam ligaments can then be coated with a variety of materials (metals, oxides, nitrides, carbides, borides, silicides, etc.), either singly or as hybrid, layered, alloyed, or graded structures. During this process, 10-1000 m of the desired material(s) are deposited onto the foam ligaments by CVI. The thermomech. properties of the resultant structure are dominated by the properties of the deposit, becoming independent of the c properties at very small material loadings. With precise control over the variables available, it is possible to obtain the simultaneous optimization of stiffness, strength, thermal cond., overall wt. and environmental resistance.

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Chemical control in precipitation of spherical zirconia particles. Lerot, L.; Legrand, F.; De Bruycker, P. Lab. Cent. Rech., Solvay et Cie, Brussels, Belg. Journal of Materials Science (1991), 26(9), 2353-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 115:13964 AN 1991:413964 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Monodisperse spherical ZrO2 particles were pptd. by hydrolysis of alc. solns. of Zr alkoxides in the presence of long-chain carboxylic acids. The particle size can be finely tuned from 0.1 to 2.5 m by controlling the concn. of Zr alkoxide, the water/Zr ratio, the nature of alc. from EtOH to BuOH, the nature of carboxylic acid from caproic to oleic acid, and its concn. The relations among the induction time before nucleation, the particle size, and all the above parameters are tentatively explained on the grounds of the soly. of the carboxy-alkoxide derivs. and their tendency to form micelles. Calcination of pptd. powders at 300-600 produces mixts. of varying compn. from cubic to monoclinic phases of small crystallite sizes and brings out the loss of surface area and org. content. Different conditions of drying powders lead to variously ordered microstructures.

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Stability of zirconia-ceria-yttria ceramics in hostile environments. Leach, C.; Khan, N. Dep. Mater., Imp. Coll. Sci., Technol. Med., London, UK. Journal of Materials Science (1991), 26(8), 2026-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 114:212576 AN 1991:212576 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The phase chem., elec. cond. in air and forming gas, and stability in warm humid environments of ZrO2-CeO2-Y2O3 ceramics are described. The compns. studied lie between 12 mol% CeO2/88 mol% ZrO2 and 3 mol% Y2O3/97 mol% ZrO2 and fall within the tetragonal phase field of this ternary system. At 700, reducing atms. affected only the cond. of the end-member CeO2-ZrO2 ceramic, having no effect on the ternary compns. Compns. contg. >10 mol% CeO2 were more stable to stabilizer loss in water vapor at 132 than those contg. <10 mol% CeO2.

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A mathematical model for chemical vapor infiltration with microwave heating and external cooling. Gupta, Deepak; Evans, James W. Lawrence Berkeley Lab., Univ. California, Berkeley, CA, USA. Journal of Materials Research (1991), 6(4), 810-18. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 114:191000 AN 1991:191000 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model was used to compute temp. profiles in ceramic preforms that are heated by microwaves. The temp. profiles were then input to a 2nd part of the model describing chem. vapor infiltration of the preform, that is the diffusion of gaseous reactants, heterogeneous reaction, and evolution of the pore structure. Equations were solved numerically for parameters corresponding to the infiltration of SiC preforms by pyrolysis of MeSiCl3. While based on some simplifications, the model leads to the conclusion that infiltration proceeds more rapidly, and to a greater extent, with microwave heating/external cooling than in isothermal infiltration. The model suggests that infiltration might be optimized by manipulation of microwave power and external cooling. The computed extent of infiltration is very sensitive to the initial pore size.

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Preparation of silicon carbide powders by chemical-vapor deposition of the dichlorodimethylsilane-hydrogen system. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(11), 4614-21. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:236356 AN 1990:636356 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC powders were prepd. by chem.-vapor deposition using (Me)2SiCl2 and H2 as source gases at 1273-1673 K. Various kinds of SiC powders such as amorphous powder, -type single-phase powder, and composite powder were obtained. The composite powders contained free Si and/or free C phases of a few nanometers in diam. All the particles obsd. were spherical in shape and uniform in size. The particle size increased from 45 to 130 nm with decreasing reaction temp. and gas flow rate and with increasing reactant concn. The lattice parameter of the -SiC particles decreased with increasing reaction temp. All the lattice parameters were larger than those of bulk -SiC.

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Thermodynamics for the preparation of silicon carbide-carbon nanocomposites by chemical-vapor deposition. Wang, Y.; Sasaki, M.; Goto, T.; Hirai, T. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(11), 4607-13. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:236355 AN 1990:636355 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

SiC-C nanocomposites covering every possible combination of C and SiC were prepd. by chem.-vapor deposition. The specific compns. of the deposits were controlled by changing the Si/C molar ratio in the source gases at deposition temps. 1673-1873 K and total gas pressures 6.7-40 kPa using the SiCl4-C3H8-H2 system. The prediction, based on the thermodn. calcn. on compn., morphol. and deposition rate, was compared with exptl. results. The optimal deposition conditions predicted by the calcns. were nearly in agreement with the exptl. results.

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Thermomechanical properties and oxidation resistance of zirconia CVI-matrix composites: 1 - mechanical behavior. Minet, J.; Langlais, F.; Quenisset, J. M.; Naslain, R. Lab. Chim. Solide, Univ. Bordeaux, Talence, Fr. Journal of the European Ceramic Society (1989), 5(6), 341-56. CODEN: JECSER ISSN: 0955-2219. Journal written in English. CAN 113:216698 AN 1990:616698 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The mech. behavior of various ZrO2-based fibrous composites was studied at ambient and high temps. The composites were prepd. by ZrO2-chem.-vapor infiltration (CVI) densification, from preforms made of Al2O3 or C fibers consolidated with a small amt. of Al2O3, pyrocarbon or hexagonal BN. When loaded under compression at room temp., 2-dimensional (2-D) C-C/ZrO2 composites exhibit mech. behavior similar to that already reported for the related 2-D-C-C/SiC, 2-D-C-C/B4C, 2-D-C-C/TiC or 2-D-C-C/BN materials with: a linear elastic domain, a damaging domain prior to failure, and an anisotropy which decreases as ZrO2 vol. fraction is raised. Under 3-point bending, the Al2O3-ZrO2 composites behave, at room temp., in a nonbrittle manner when the preform has been consolidated by BN, with crack deviation and pull-out phenomena. The variations of the stiffness and strength vs. ZrO2 vol. fraction obey exponential laws at room temp. Finally, the Al2O3-ZrO2 composites keep their strength and rigidity .ltorsim.1000 under an atm. of Ar/H.

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Low-temperature MOCVD of silicon-based ceramic films. Du, Honghua; Bae, Yongwoong; Gallois, Bernard; Gonsalves, Kenneth E. Dep. Mater. Sci. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 331-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196275 AN 1990:596275 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A liq. methylsilazane compd., [MeSiHNH]n, was used, with H2, NH3, and a 60%/40% NH3/H2 mixt., to deposit Si-based ceramic films in a metalorg. chem.-vapor-deposition (MOCVD) reactor at 873-1073 K. Characterization of the films by ellipsometry and FTIR and Auger electron spectrometry showed that the methylsilazane was pyrolyzed to form Si carbonitride in H2 and Si3N4 in both NH3 and NH3/H2, with the incorporation of appreciable amts. of O. The deposition rate increased and the activation energy decreased in order from NH3-, NH3/H2-, and H2-[MeSiHNH]n gas mixts. The temp. dependence of the structural d. of the films increased in the same order.

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Modeling transport, reaction, and pore structure evolution during densification of cellular or fibrous structures. Sotirchos, Stratis V.; Tomadakis, Manolis M. Dep. Chem. Eng., Univ. Rochester, Rochester, NY, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 73-8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196263 AN 1990:596263 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A math. model is developed to describe mass transport, reaction, and structure evolution during densification of porous media of initially fibrous or cellular structure. The use of Monte Carlo simulation procedures for detg. the variation of the local (av.) structural properties of the porous structure and of the effective diffusion coeffs. in the porous medium with the porosity is also discussed, and results are presented for Knudsen diffusion in cellular or fibrous media. The model is used to theor. study the transient behavior of the densification process during prepn. of SiC/SiC ceramic matrix composites by chem. vapor infiltration of porous preforms. Particular emphasis is placed on the investigation of the effects of pressure pulsing on the d. gradients in the densifying structure.

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Analytical simulation of an improved CVI [chemical vapor infiltration] process for forming highly densified ceramic composites. Tai, Nyan Hwa; Chou, Tsu Wei. Cent. Compos. Mater., Univ. Delaware, Newark, DE, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 61-6. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:196261 AN 1990:596261 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A model for chem.-vapor infiltration (CVI) under pressure and temp. gradients is applied to the study of deposition of SiC from the pyrolysis of MeSiCl3 within a 3-dimensional (3-D) woven fibrous preform. The model considers the infiltration of reactants into a preform with temp. gradients by applying a pressure gradient between the vapor inlet and outlet; it also takes into account the variation in concn. of the vapor precursor. A quasi-steady-state approach was adopted to stimulate the matrix deposition in a 3-D unit cell. The d. distribution, consolidation profile, and total fabrication period were theor. predicted.

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Formation of novel sintered composites by high-pressure crystallization of amorphous ceramics. Onodera, Akifumi; Takahashi, Norikazu; Yoshihara, Haruyuki; Nakae, Hiroyuki; Matsunami, Yukio; Hirai, Toshio. Fac. Eng. Sci., Osaka Univ., Toyonaka, Japan. Journal of Materials Science (1990), 25(9), 4157-61. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:176879 AN 1990:576879 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A combination of chem.-vapor deposition (CVD) and high-pressure (HP) sintering methods were used to prep. the zincblende form of BN (z-BN)-based ceramic composites. The CVD method provides amorphous B-N-X (X = Al, Si, or Ti). The HP method renders the amorphous samples cryst., and decompn. into z-BN plus the resp. nitride (e.g., -Si3N4) occurs. Compacts of the composites are obtained by in situ sintering under high pressure. The compacts exhibit peculiar microstructures composed of z-BN nanocrystals homogeneously dispersed in the nitride matrixes.

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Characterization of ceramic matrix composites fabricated by chemical vapor infiltration. Stinton, D. P.; Hembree, D. M., Jr.; More, K. L.; Sheldon, B. W.; Besmann, T. M. Oak Ridge Natl. Lab., Oak Ridge, TN, USA. Materials Research Society Symposium Proceedings (1990), 168(Chem. Vap. Deposition Refract. Met. Ceram.), 273-80. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 113:176787 AN 1990:576787 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A process for the prepn. of fiber-reinforced SiC composites by chem.-vapor deposition has been developed at Oak Ridge National Lab. Composites are prepd. by infiltrating fibrous preforms with reactant gases that decomp. at elevated temps. to deposit SiC between and around the fibers. Because the infiltration process utilizes both temp. and pressure gradients, SiC is deposited under conditions that vary considerably from the hot face to the cool face of the composite. Matrix characterization of composite samples by TEM and Raman spectroscopy are described.

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Analysis and testing of the metal parts furnace for the demilitarization of chemical warfare munitions. Fournier, Ronald L.; Horne, Deane A.; Rinker, Franklin G.; Jackson, Kerm. Dep. Chem. Eng., Univ. Toledo, Toledo, OH, USA. Journal of Hazardous Materials (1990), 23(1), 1-20. CODEN: JHMAD9 ISSN: 0304-3894. Journal written in English. CAN 113:137967 AN 1990:537967 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

At the Chem. Agent Munitions Disposal System (CAMDS) located to Tooele Army Depot, Utah, the munition metal parts contg. <5% residual agent are thermally decontaminated in roller hearth-type furnace, the Metal Parts Furnace (MPF). The drained munitions are heated to >1000F for 15 min to insure complete destruction of any remaining agent residue. During this heating process the residual agent vaporizes. The vaporized agent burns within the MPF and the MPF afterburner prior to treatment of the combustion product gases in the pollution abatement system. Agent vaporization is a rapid unsteady process with peak Btu loadings on the MPF of 10 million Btu/h. Since there are 14 different munition types contg. 3 different types of chem. agents, ranging from a load of 96 105-mm projectiles contg. as little as 0.08 lbs of the nerve agent GB per projectile to a ton container with 80 lbs of the nerve agent VX, the control system of the MPF system must be flexible enough to handle a wide variety of thermal loads. To evaluate and predict the performance of the MPF, tests were performed at CAMDS by using a variety of munitions contg. chem. agent simulants. The simulants were selected on the basis of comparable b.ps., heat of vaporization, and heat of combustion. A math. model of the MPF was developed to predict the heating rate of the munition and the vaporization profiles of the agents and their simulants. The results of the model were compared to simulant testing in ton containers at CAMDS. The results show good agreement with the math. model predictions.

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Powder preparation and compaction behavior of fine-grained yttria-doped tetragonal zirconia polycrystals (Y-TZP). Groot Zevert, W. F. M.; Winnubst, A. J. A.; Theunissen, G. S. A. M.; Burggraaf, A. J. Fac. Chem. Technol., Univ. Twente, Enschede, Neth. Journal of Materials Science (1990), 25(8), 3449-55. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 113:119698 AN 1990:519698 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Two wet chem. prepn. methods are described for Y2O3-doped tetragonal ZrO2 powders. Both methods yield powders with an extremely small crystallite size (8 nm) and a narrow size distribution. The agglomerate and aggregate structure of these powders was investigated by several techniques. Gel pptn. from an alkoxide soln. in water (alkoxide synthesis) results in a ceramic powder with irregular-shaped weak and porous agglomerates, which are built up from dense aggregates with a size of 18 nm. Gel ppts. formed from a metal-chloride soln. in NH3 (chloride synthesis) do not contain aggregates. Both types of agglomerate are fractured during isostatic compaction. Hydrolysis and washing under (strong) basic conditions probably decrease the degree of aggregation. The aggregate morphol. and structure are key parameters in the microstructure development during sintering of a ceramic. Several characteristics of these powders are compared with those of a com. one (Toyo Soda TZ3Y).

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Preparation of titanium carbide plates by chemical vapor deposition. Jiang, Chorn Cherng; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1990), 25(2A), 1086-93. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 112:144385 AN 1990:144385 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Thick TeCx plates were prepd. by chem.-vapor deposition using TiCl4, CCl4, and H2 as source gases at deposition temps. (Tdep) 1573-1873 K, total gas pressures (Ptot) 4-40 kPa, and source gas molar ratio [CCl4/(TiCl4 + CCl4)] (mc) 0.13-0.91. The effects of deposition conditions on the microstructure, preferred orientation, deposition rate, lattice parameter, and compn. were studied. A plate-like TiCx was obtained at mc 0.5. The (110) plane was preferably oriented parallel to the deposition surface at Tdep 1673-1873 K. The deposition rates showed a strong mc dependence and the max. rate was found at mc = 0.3-0.5. The activation energies for the formation of TiCx plates were 86 kJ/mol at Ptot = 4 kPa and 95 kJ/mol at Ptot = 40 kPa. When mc values were 0.13-0.51, the lattice parameter increased with increasing mc >0.72 at all Tdep. The at. ratio (C:Ti) for TiCx was 0.6-1.0 depending on deposition conditions.

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Characterization and processing of CVD powders for fabrication of composite and compound ceramics. Hori, Saburo; Shigaki, Yoshiki; Hirata, Yoshihiro; Yoshimura, Masahiro; Somiya, Shigeyuki. Kureha Chem. Ind. Co., Ltd., Tokyo, Japan. Materials Research Society Symposium Proceedings (1989), 155(Process. Sci. Adv. Ceram.), 3-12. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 112:144279 AN 1990:144279 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Two-component oxide powders were prepd. in the systems Al2O3-ZrO2, AliO3-TiO2, and Al2O3-SiO2 by a chem.-vapor deposition (CVD) method using a combustion flame for the purpose of fabricating resp. composite or compd. ceramics. The CVD powders were spherical and ultrafine (av. 30-70 nm) with log-normal size distribution, and exhibited either very homogeneous or nanoheterogeneous structure and crystallog. metastability in phases and solid soln. By starting from these CVD powders, uniform microstructures were achieved in the sintered products and better sinterability and novel microstructure became possible due to the metastability which reflected the formation mechanism of 2-component powders at high temps. CVD powders, previously considered difficult to sinter, proved to be excellent starting materials for fabrication of composite and compd. ceramics when improved processing methods were applied.

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Preparation of silicon carbide powders by chemical vapor deposition from the silane-methane-hydrogen system. Chen, Lidong; Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1989), 24(11), 3824-30. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 112:41177 AN 1990:41177 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor deposition (CVD) from the SiH4 + CH4 + H2 system was used to prep. -SiC powders at 1523-1673 K. The powders obtained at 1673 K were single-phase -SiC contg. neither free Si or free C. The powders obtained at <1623 K were composite powders contg. free Si. The carburization ratio (SiC/SiC + Si)) increased with increasing reaction temp. and total gas flow rate, and with decreasing reactant concn. The av. particle sizes detd. by TEM were 46-114 nm. The particle size increased with increasing reaction temp. and gas concn. but decreased with increasing gas flow rate. The -SiC particles obtained at <1623 K consisted of a Si core and a -SiC shell, as opposed to the -SiC particles obtained at 1673 K, which were hollow. IR absorption peaks were obsd. at 940 and 810 cm-1 for particles contg. a Si core, whereas a single peak at .apprx.830 cm-1 with a shoulder at .apprx.930 cm-1 was obsd. for the -SiC hollow particles. The lattice parameter of -SiC having a carburization ratio <70 wt. %, was larger than that of bulk -SiC and decreased with increasing carburization ratio. However, when the carburization ratio was >70 wt.%, the lattice parameter became approx. equal to that of bulk -SiC.

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The interaction of chemical kinetics and diffusion in the dynamics of chemical vapor infiltration. Middleman, Stanley. Dep. Ames/Chem. Eng., Univ. California-San Diego, La Jolla, CA, USA. Journal of Materials Research (1989), 4(6), 1515-24. CODEN: JMREEE ISSN: 0884-2914. Journal written in English. CAN 112:24678 AN 1990:24678 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The classical model of chem. vapor infiltration treats diffusion and surface reaction in a representative cylindrical pore. Two significant modifications to that approach are presented. One accounts for more complex chem. by allowing for both gas-phase and surface reactions which lead to film growth. The other couples the pore model to a reactor model for the region external to the porous preform. The results demonstrate that it is possible to select chem. schemes that yield densification from the interior to the exterior of the preform, thus avoiding premature trapping of interior voids.

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The colloid chemistry of ceramic membranes. Xu, Qunyin; Gieselmann, Mary J.; Anderson, Marc A. Water Chem. Program, Univ. Wisconsin, Madison, WI, USA. Polymeric Materials Science and Engineering (1989), 61 889-93. CODEN: PMSEDG ISSN: 0743-0515. Journal written in English. CAN 111:238343 AN 1989:638343 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The colloid chem. in sol-gel processing for prepg. particulate ceramic membranes is a key tool used for tailoring membrane structures. The chem.-phys. variables in hydrolysis and peptization processes control the particle nature in sols, which is directly related to the gelation process and particle packing geometry in the hydrogel. The pore structure of membranes is mainly detd. by the size of primary particles rather than by that of aggregates. TiO2 membranes with mean pore diam. 1.8-3.0 nm were prepd. from primary particles <10 nm. A larger variety of pore structures in membranes, including broader pore size range and more narrow size distributions, can be made by controlling sol-gel processing conditions to serve a large range of applications.

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Chemical vapor deposition of ultrafine ceramic structures. Gallois, B. M.; Mathur, R.; Lee, S. R.; Yoo, J. Y. Dep. Mater. Metall. Eng., Stevens Inst. Technol., Hoboken, NJ, USA. Materials Research Society Symposium Proceedings (1989), Volume Date 1988, 132(Multicompon. Ultrafine Microstruct.), 49-60. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 111:238219 AN 1989:638219 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Ultrafine ceramic structures based on the nitrides and carbides of Ti and Si were prepd. in a computer-controlled hot-wall chem.-vapor deposition (CVD) reactor. Layered deposits were produced by pulsing the reactant gases judiciously under software control. The development of a columnar structure which is endemic to most CVD materials was suppressed. Skeletal structures of filaments were grown with appropriate catalysts by the vapor-liq.-solid mechanism and immediately infiltrated in situ with different materials to produce filament-reinforced composite coatings. Ultrafine-grained C films and filaments were grown from CH4-H mixts. by plasma-assisted CVD. The microstructural features of these materials are of the order 20-100 nm. The subgrain structure detd. by Raman spectroscopy varies at 2-3 nm.

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Stability to moisture for chemically vapor-deposited boron nitride. Matsuda, T. Japan Met. and Chem. Co. Ltd., Gunma, Japan. Journal of Materials Science (1989), 24(7), 2353-7. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 111:82901 AN 1989:482901 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor-deposited BN (CVD-BN) plates, prepd. from the BCl3-NH3-H2 gas system, were studied in terms of stability to moisture by IR spectroscopic measurement, chem. anal., and TG. The synthesis conditions of CVD-BN plates have a large effect on their stability to moisture. The stability of CVD-BN plates prepd. under a total gas pressure (Ptot) of 10-60 torr degraded as the deposition temp. (Tdep) decreased. The CVD-BN plates with transparent and isotropic properties, which were prepd. at <1400 and >10 torr, showed poor stability to moisture. The CVD-BN plates synthesized under 5 torr had high moisture-resistance, even at a Tdep 1400. An IR absorption spectra revealed that the unstable species existing in CVD-BN plates had changed to ammonium borate hydrates by reacting with moisture in the atm. The stability to moisture for CVD-BN plates degraded as the deposition rate increased, esp. for the CVD-BN plates prepd. at 1400.

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Interfacial chemistry-structure and fracture of ceramic composites. Schoenlein, L. H.; Jones, R. H.; Henager, C. H.; Schilling, C. H.; Gac, F. Pac. Northwest Lab., Richland, WA, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 313-21. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119795 AN 1989:119795 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The interfacial chem. and phases of SiC-reinforced Si3N4 composites were studied by TEM with assocd. x-ray energy-dispersive spectroscopy microanal. and Auger electron spectroscopy. Hot-pressed Si3N4 (HPSN) composites reinforced with Nicalon SiC fibers or Tateho SiC whiskers and reaction-bonded Si3N4 (RBSN) composites reinforced with uncoated or coated VLS SiC whiskers were evaluated. In the Nicalon fiber-reinforced HPSN, an interfacial phase composed of a layer of amorphous C and an adjacent layer of graphitic C was obsd. and is believed to assist fiber pull-out during fracture of the composite. However, the fracture strength and toughness of these composites were considerably less than those of unreinforced HPSN. HPSN composites reinforced with Tateho SiC whiskers contained an interfacial phase believed to be similar to the intergranular phase found in the HPSN matrix. In RBSN composites fabricated with an Fe2O3 sintering aid, the VLS SiC whiskers were severely faceted by a reactive Fe silicide phase despite C, BN, or SiO2 coatings on the whiskers. When no sintering aid was used, the uncoated whiskers were not degraded and appeared to be strongly bounded to the RBSN matrix. The composites reinforced with SiO2-coated whiskers possessed the highest fracture strength and toughness, and the composites reinforced with the BN-coated whiskers possessed the lowest fracture strength and toughness.

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Theoretical analysis of chemical vapor infiltration in ceramic/ceramic composites. Tai, Nyan Hwa; Chou, Tsu Wei. Dep. Mech. Eng., Univ. Delaware, Newark, DE, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 185-92. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119788 AN 1989:119788 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A model for the deposition of Al2O3 and TiC with a ceramic fiber bundle from the chem. reactions was studied. The model considers vapor diffusion, chem. reaction on the inner surface of the capillary, deposition film growth, porosity, and effects of reactant compns. at various reactor temps. and pressures. Binary, multicomponent diffusion and Knudsen diffusion account for the different stages of the chem.-vapor-infiltration (CVI) process. Furthermore, both diffusion-controlled and reaction-controlled processes were examd. to det. the dominating process in CVI.

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Fracture behavior of 3-D braided Nicalon/silicon carbide composite. Yang, J. M.; Chou, J. C.; Burkland, C. V. Dep. Mater. Sci. Eng., Univ. California, Los Angeles, CA, USA. Materials Research Society Symposium Proceedings (1988), 120(High Temp./High Perform. Compos.), 163-8. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 110:119785 AN 1989:119785 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture behavior of a 3-dimensional (3-D) braided Nicalon fiber-reinforced SiC matrix composite processed by chem. vapor infiltration (CVI) was studied. The fracture toughness and thermal shock resistance under various thermomech. loadings were characterized. A tough and durable structural ceramic composite can be achieved through the combination of 3-D fiber architecture and the low-temp. CVI processing.

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Chemical interactions in ceramic and carbon-carbon composites. Luthra, Krishan L. Corp. Res. Dev., Gen. Electr. Co., Schenectady, NY, USA. Materials Research Society Symposium Proceedings (1988), 125(Mater. Stab. Environ. Degrad.), 53-60. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 110:119676 AN 1989:119676 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review with 10 refs. The useful lives of many ceramic composites are affected, if not controlled, by chem. interactions between various constituents and the gas environment. Thermochem. calcns. are extremely valuable in evaluating these concerns. Examples of many possible concerns are presented. The usefulness of a thermochem. approach is demonstrated by a somewhat detailed discussion of the oxidn. protection of C/C composites. This includes discussion of the various possible rate-limiting steps and the detrimental effects of CO gas formed as a result of C oxidn.

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Consolidation of silicon nitride (Si3N4) powder-preform by infiltration of boron nitride using the pulse CVI [chemical vapor infiltration] process. Sugiyama, Kohzo; Ohsawa, Yoshimi. Fac. Eng., Nagoya Univ., Nagoya, Japan. Journal of Materials Science Letters (1988), 7(11), 1221-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 110:62400 AN 1989:62400 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

BN infiltration into a Si3N4 powder preform, as a model of pulse chem.-vapor infiltration and means of consolidating powder preforms, is reported. The resulting samples were studied using SEM and electron microprobe x-ray microanal. and the effect on flexural strength was detd. The BN matrix deposits tightly among the particles of Si3N4.

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Bonding in aluminum phosphate ceramics prepared at low temperatures. Silsbee, Michael R.; Roy, D. M. Dep. Mater. Sci. Eng., Pennsylvania State Univ., University Park, PA, USA. Materials Research Society Symposium Proceedings (1988), 114(Bonding Cem. Compos.), 295-300. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 109:114885 AN 1988:514885 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The process of chem. binding involves the transformation of a powder into a single contiguous mass. This process is likely to involve considerable structural rearrangement. The presence of a liq. phase offers a low energy pathway for the movement of ions required to achieve this rearrangement. The presence of the liq. phase alone is not sufficient to insure a successful transformation. Thermodn. considerations govern the ultimate reaction products, and the structure and chem. reactivity of the starting materials play a major role in the binding reaction. The ability of the solid phases to release ions for transport is important. Al(OH)3 served as a source of Al ions that reacted with the phosphate ions already in soln. to form an amorphous phase binding the less reactive -Al2O3 and AlPO4 particles together. The addn. of relatively small amts. of amorphous SiO2 altered the reaction products rather drastically.

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Detectors in battle. Powell, R. J. UK. Chemistry in Britain (1988), 24(7), 665, 667, 669. CODEN: CHMBAY ISSN: 0009-3106. Journal written in English. CAN 109:78950 AN 1988:478950 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The operating principle and design of 2 chem. warfare agent detectors are discussed. Both of the detectors have electrochem. cells which respond to nerve agents (tabun, sarin, VX) and to HCN.

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Density and deposition rate of chemical-vapor-deposited boron nitride. Matsuda, Toshitsugu; Nakae, Hiroyuki; Hirai, Toshio. Japan Met. Chem. Co., Ltd., Gunma, Japan. Journal of Materials Science (1988), 23(2), 509-14. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 108:191407 AN 1988:191407 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The d. and deposition rate characteristics were studied of chem.-vapor-deposited BN (CVD-BN) plates synthesized by use of the BCl3-NH3-H2 system at deposition temp. (Idep) 1200-2000 and total gas pressure (Ptot) 5-60 torr. At Ptot, all the CVD-BN plates synthesized at each Tdep above 1300 had a d. >2.0 g/cm3 and thus showed no noticeable dependence on Idep. Over the Ptot range from 10-60 torr, on the other hand, the d. of the plates reached the max. of 2.08 g/cm3 at Tdep 2000. As Tdep was lowered, the d. decreased to a min. of 1.40 g/cm3. The deposition rate varied with both Tdep and Ptot and showed a max. value under a certain Ptot at a given Tdep. The value of Ptot where the deposition rate becomes max. changed depending on the Tdep. The max. deposition rate was 0.6 mm/h for the CVD-BN plates when the d. was <2.0 g/cm3 and 0.4 mm/h when the d. was >2.0 g/cm3. The effects of deposition conditions on the characteristics of the d. and deposition rate are discussed in terms of the structure and deposition mechanism.

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Synthesis and catalytic activity of surfactant analogs of 4-(dimethylamino)pyridine. Katritzky, Alan R.; Duell, Bradley L.; Durst, H. Dupont. Dep. Chem., Univ. Florida, Gainesville, FL, USA. Langmuir (1987), 3(6), 976-82. CODEN: LANGD5 ISSN: 0743-7463. Journal written in English. CAN 107:197237 AN 1987:597237 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Seven surfactants have been synthesized, each contg. a 4-(dialkylamino)pyridine moiety carrying an 8-10-carbon chain with an attached polar or charged group. Two of the compds. fall into the neutral charge category, two are cationic, two are zwitterionic, and one is anionic. Rates of hydrolysis of 4-nitrophenyl hexanoate and 1,2,2-trimethylpropyl methylphosphonofluoridate by each surfactant were measured, both with and without added cetyltrimethylammonium chloride (CTAC). The most active deriv. was sodium 10-[butyl(4-pyridinyl)amino]decyl sulfate. The present catalysts, in contrast to the iodosobenzoates, show poor rate enhancements in the hydrolysis of fluorophosphonates.

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High temperature evaporation characteristics of amorphous Si3N4-C composite prepared by chemical vapor deposition. Goto, Takashi; Hirai, Toshio. Inst. Mater. Res., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1987), 22(8), 2842-6. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 107:119869 AN 1987:519869 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Evapn. characteristics of amorphous Si3N4 and amorphous Si3N4-C composite (6 wt.% C) prepd. by the chem.-vapor deposition (CVD) were studied at 1400-1650 in a vacuum of .apprx.10-6 torr. The wt. loss due to the evapn. was linear with time for all samples tested. The evapn. rate of the amorphous CVD-(Si3N4-C) composite was 50-70% of that for the amorphous CVD-Si3N4. The activation energy for evapn., calcd. from the temp. dependence of the evapn. rates, was .apprx.160 kcal/mol for both samples. The C dispersed in the amorphous CVD-(Si3N4-C) composite reacted at the time of heat-treatment with the amorphous Si3N4 matrix and formed -SiC particles. The -SiC particles were .apprx.100 nm in diam. and connected to form a 3-dimensional network structure.

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Influence of synthesis chemistry on alumina-zirconia powder characteristics. Debsikdar, J. C. Battelle Columbus Div., Columbus, OH, USA. Journal of Materials Science (1987), 22(6), 2237-47. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 107:44957 AN 1987:444957 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. polymn., destabilization of mixed sols, and copptn. chem. processes were used to synthesize 80Al2O3.20ZrO2 (wt.%) powders. The elementary particles produced by each of these processes were 1.5-3.0 nm in size and were amorphous to electron diffraction. The powders were evaluated in terms of wt. loss (TGA), thermal characteristics (DTA), surface area (Brunauer-Emmett-Teller equation), pore size distribution, d. at different temps., and crystn. behavior (x-ray diffraction). The physicochem. characteristics and crystn. behavior of these chem. derived powders were significantly affected by the chem. of the powder synthesis. The powders produced by the chem. polymn. and the colloidal processes retained the tetragonal ZrO2 phase during cooling from 1600, but significant transformation of tetragonal to monoclinic ZrO2 occurred in the copptd. powder under identical conditions. The 1550-calcined powder derived by the chem. polymn. process retained a substantial amt. of tetragonal ZrO2 after annealing at 1000 for 72 h. The av. Al2O3 and ZrO2 crystal size of the calcined powders, calcd. by the Scherrer equation, was 20-80 nm.

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Characterization of wurtzitic boron nitride compacts. Singh, Bhanu Pratap. Natl. Phys. Lab., New Delhi, India. Journal of Materials Science (1987), 22(2), 495-8. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 106:161234 AN 1987:161234 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The properties of sintered polycryst. wurtzitic BN compacts were studied including the cryst. phases that formed at high temp. and pressure, compn., BN and binder particle size distribution, and hardness. Wurtzitic BN, cubic BN, TiC/TiN solid soln., TiB, and TiB2 were the cryst. phases obsd. The BN and binder particle size distributions were comparable (1-5 m), with .apprx.80% of the particles 2-3 m. Wt. percentages of different elements present in these compacts were detd. The av. Knoop hardness values under 500 g load and the variation of hardness as a function of position on the specimen surface were studied.

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Morphological and mechanical characterization of ceramic composite materials. Chermant, J. L.; Gomina, M.; Osterstock, F. ISMRa, Univ. Caen, Caen, Fr. Materials Science Research (1986), 20(Tailoring Multiphase Compos. Ceram.), 615-29. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 106:124512 AN 1987:124512 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

C fiber-reinforced (chem. vapor-deposited SiC) ceramic composites were tested in 3-point bending in 3 orientations of the notch prior to the applied stress. For the 2 main orientations, load-unloading sequences were performed to investigate the rupture parameters using the M. Sakai et al. (1983) method. The very good mech. behavior of these materials are due to the energy dissipative effect of the reinforcement. For the weaker orientation, an empirical method is proposed to measure the compliance at any point of the load-displacement curve.

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Chemical vapor deposition of Si3N4 from a gas mixture of Si2Cl6, NH3 and H2. Motojima, Seiji; Iwamori, Noriyuki; Hattori, Tatsuhiko. Fac. Eng., Gifu Univ., Gifu, Japan. Journal of Materials Science (1986), 21(11), 3836-42. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 105:231265 AN 1986:631265 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Si3N4 layers were prepd. on a quartz substrate from a gas mixt. of Si2Cl6, NH3, and H2 under a reduced pressure and at 800-1300. Amorphous Si3N4 layers that were dense and adherent to the substrate were obtained at 800-1100. On the other hand, -Si3N4 layers were obtained at 1200 and a source-gas ratio (N/Si) of 1.33-1.77. The lowest deposition temp. of amorphous Si3N4 was .apprx.700. The microhardness of amorphous Si3N4 obtained at 800-1100 was 2400-2600 kg/mm2 (load: 50 g), and that of -Si3N4 obtained at 1200 was 3400 kg/mm2. Chlorine contents in the Si3N4 layer decreased with increasing deposition temp. and source-gas ratio (N/Si), and with decreasing total pressure.

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Innovative chemical/ceramic directions. Morgan, P. E. D. Rockwell Int. Sci. Cent., Thousand Oaks, CA, USA. Materials Research Society Symposium Proceedings (1986), 73(Better Ceram. Chem. 2), 751-63. CODEN: MRSPDH ISSN: 0272-9172. Journal; General Review written in English. CAN 105:213019 AN 1986:613019 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 37 refs., of chem. methods of ceramic prepn. including discussions of the sol-gel process, nanostructures, polymer pyrolysis, fused salt synthesis of chalcogenides, transformation toughening, liq. boundary phases, and Si3N4 prepn. from SiCl4 and (SiS2 + SiCl4).

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Microhardness and internal stress of silicon nitride (Si3N4)-silicon carbide films prepared by plasma CVD. Kamata, Kiichiro; Aizawa, Naoyoshi; Moriyama, Minoru. Technol. Univ. Nagaoka, Nagaoka, Japan. Journal of Materials Science Letters (1986), 5(10), 1055-7. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 105:196083 AN 1986:596083 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The microhardness and internal stress of Si3N4-SiC films prepd. by plasma chem.-vapor deposition were detd. in relation to use of the coatings for high strength and wear resistance. The films had compns. indicated by SiNxCy where x = 0-1.42 and y = 0-1.04. The relation between the crack length in a film coating on glass substrates (induced by a Vickers indentor) and the internal stress is discussed.

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Hybridization between silicon nitride (Si3N4) and silicon carbide films by plasma CVD. Kamata, Kiichiro; Maeda, Yuuji; Moriyama, Minoru. Technol. Univ. Nagaoka, Nagaoka, Japan. Journal of Materials Science Letters (1986), 5(10), 1051-4. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 105:196082 AN 1986:596082 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Hybrid SiC-Si3N4 films were prepd. by charge-coupled plasma chem.-vapor deposition from SiH4, NH3, CH4 (or C2H4), and H2 reaction gases. Homogeneous amorphous films were easily obtained. The C, N, and Si contents of the films were detd. Grains or phase boundaries were not obsd. using TEM. The n, IR absorption peak position, and optical band gap of the films varied continuously with changing amts. of each component in the Si3N4-SiC films. These results and TEM observations indicate that the films are not a mixt. of Si3N4 and SiC clusters. but are hybrid materials in which Si, N, and C atoms are blended on an at. scale.

Bibliographic Information

Zirconia: ceramic engineering's toughness challenge. Fisher, Greg. Dir. Tech. Serv., ACerS, USA. American Ceramic Society Bulletin (1986), 65(10), 1355-60. CODEN: ACSBA7 ISSN: 0002-7812. Journal; General Review written in English. CAN 105:195989 AN 1986:595989 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 54 bibliog. refs., of the chem. and properties of ZrO2 ceramics and the relations of these characteristics to ceramic toughness.

Bibliographic Information

Hydrolysis of mustard derivatives in aqueous acetone-water and ethanol-water mixtures. Yang, Yu Chu; Ward, J. Richard; Luteran, Thomas. Res. Dir., U. S. Army Chem. Res. Dev. cent., Aberdeen Proving Ground, MD, USA. Journal of Organic Chemistry (1986), 51(14), 2756-9. CODEN: JOCEAH ISSN: 0022-3263. Journal written in English. CAN 105:42037 AN 1986:442037 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Kinetic data for the hydrolysis of ClCH2CH2SR (R = Me, Et) in the title solvents were interpreted in terms of an SN1 mechanism with anchimeric assistance of the S atom to form a cyclic sulfonium ion as an intermediate. A finite and neg. Cp.thermod. was obsd.

Bibliographic Information

Synthesis of fiber-reinforced silicon carbide composites by chemical vapor infiltration. Stinton, David P.; Caputo, A. J.; Lowden, Richard A. Oak Ridge Natl. Lab, Oak Ridge, TN, USA. American Ceramic Society Bulletin (1986), 65(2), 347-50. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 104:93916 AN 1986:93916 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A process was developed for the fabrication of fiber-reinforced SiC composites by chem.-vapor infiltration. Infiltration times of the low-d. fibrous structures were reduced significantly from previous processes by utilizing simultaneously a thermal gradient and forced gas flow. Synthesis of composites in this fashion produced specimens with high flexural strengths and with strain tolerances which significantly exceeded that of monolithic SiC.

Bibliographic Information

Creep of chemically vapor deposited silicon carbide fibers. Dicarlo, James A. Lewis Res. Cent., Natl. Aeronaut. Space Adm., Cleveland, OH, USA. Journal of Materials Science (1986), 21(1), 217-24. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 104:55136 AN 1986:55136 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The creep, thermal expansion, and elastic modulus properties of chem. vapor-deposited SiC fibers were detd. at 1000-1500. Creep strain increased logarithmically with time, monotonically with temp., and linearly with tensile stress at 600 MPa. The controlling activation energy was 480  20 kJ/mol. Thermal pretreatments at .apprx.1200 and 1450 significantly reduced fiber creep. These results coupled with creep recovery observations indicate that at <1400 fiber creep is anelastic with a negligible plastic component. This allowed a simple predictive method to be developed for describing fiber total deformation as a function of time, temp., and stress. Mechanistic anal. of the property data suggests that fiber creep is the result of -SiC grain-boundary sliding, controlled by a small percentage of free Si in the grain boundaries.

Bibliographic Information

Mechanical properties of zirconia-toughened alumina ceramics from CVD powders. Hori, Saburo; Yoshimura, Masahiro; Somiya, Shigeyuki; Kurita, Ryuichi; Kaji, Hisatsugu. Res. Lab. Eng. Mater., Tokyo Inst. Technol., Yokohama, Japan. Journal of Materials Science Letters (1985), 4(4), 413-16. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 103:10304 AN 1985:410304 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture toughness and bending strength were measured on sintered ZrO2/-toughened Al2O3 samples which had been prepd. from a chem. vapor-deposited powder. Fracture toughness increased with ZrO2 addns. from 2.6 to 4.8 MPam1/2. Bending strength increased from 430 to 660 MPa with ZrO2 addns. up to 15 wt. % then droped to .simeq.500 MPa at 20-25 wt. % addn. X-ray anal. showed that the drop in bending strength corresponded to a drop in tetragonal phase content. Both the bending strength and fracture toughness increased .apprx.50% with 15 wt. % ZrO2 addn.

Bibliographic Information

Fracture energy of silicon nitride. Rice, R. W.; McKinney, K. R.; Wu, C. C.; Freiman, S. W.; Donough, W. J. M. Nav. Res. Lab., Washington, DC, USA. Journal of Materials Science (1985), 20(4), 1392-406. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 102:224933 AN 1985:224933 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The fracture energy of Si3N4 made by hot pressing, reaction sintering, and chem. vapor deposition (CVD) was studied. Extrapolation of fracture energies to zero additive or porosity levels, as well as anal. of CVD Si3N4 all indicate an intrinsic fracture energy of 20-30 J/m. Higher fracture energies in dense bodies with increasing additive content, or in some more porous bodies (relative to expected porosity dependence) are assocd. with crack branching. In dense bodies such branching may arise due to microcracking from combined effects of crack tip stresses and mismatch stresses due to differences in properties, esp. thermal expansion, between Si3N4 and the additive or it reaction products. In porous bodies such branching appears to be due to spatial distribution of pores.

Bibliographic Information

A morphological study of silicon carbide prepared by chemical vapor deposition. Tsui, P.; Spear, K. E. Mater. Res. Lab., Pennsylvania State Univ., University Park, PA, USA. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 371-80. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 102:171306 AN 1985:171306 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Surface morphologies of SiC deposits obtained via chem. vapor deposition (CVD) were studied as functions of substrate surface temp. and the concn. of the Si and C source material, MeSiCl3. Substrates of graphite and -SiC crystals were used. Explanations of the obsd. morphologies on graphite substrates and their marked changes with temp. are given in terms of chem. kinetics and mass transport arguments. The results of thermodn. calcns. were used to help explain the obsd. morphologies of the deposits on -SiC substrates.

Bibliographic Information

Preparation of amorphous silicon nitride-boron nitride composites by chemical vapor deposition. Hirai, Toshio; Goto, Takashi; Sakai, Tadashi. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 347-58. CODEN: MTSRAY ISSN: 0076-5201. Journal written in English. CAN 102:171304 AN 1985:171304 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Chem. vapor deposition of an Si-N-B system was studied by using SiCl4, NH3, H2 and B2H6 as source gases at deposition temps. of 1100-1300 and total gas pressures of 30-70 torr. The chem. compn. and d. of the deposits were measured. The structure of the deposits was investigated by x-ray diffraction and IR absorption techniques. The deposits were composed of amorphous Si3N4 and turbostratic BN.

Bibliographic Information

CVD of silicon nitride and its composites. Hirai, Toshio. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Materials Science Research (1984), 17(Emergent Process Methods High-Technol. Ceram.), 329-45. CODEN: MTSRAY ISSN: 0076-5201. Journal; General Review written in English. CAN 102:171201 AN 1985:171201 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

A review, with 33 refs., is given of the synthesis, structure, and some properties of Si3N4-based ceramics and composites prepd. by the chem.-vapor deposition process.

Bibliographic Information

Calculation of deposition conditions for silicon nitride from a SiL4-NH3 gas phase (L = H, Cl, Br, CH). Lartigue, J. F.; Ducarroir, M.; Armas, B. Lab. Ultra-Refract., CNRS, Odeillo/FontRomeu, Fr. Journal of Materials Science (1984), 19(9), 3079-89. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 102:11260 AN 1985:11260 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Deposition conditions yielding Si nitride are calcd. for a set of initial gaseous systems, by complex thermodn. equil. computations. The influence of temp., total pressure and reactant gas ratios on the compn. and yield of the condensed phase are shown for SiH4/NH3, SiCl4/NH3, SiBr4/NH3, Si(CH3)4/NH3, and SiH4/CH4/NH3 systems. The interest of such calcns. is to give an efficient approach for exptl. studies of vapor-deposition systems.

Bibliographic Information

Mechanical properties of chemically vapor deposited nonoxide ceramics. Niihara, Koichi. Tohoku Univ., Sendai, Japan. American Ceramic Society Bulletin (1984), 63(9), 1160-4. CODEN: ACSBA7 ISSN: 0002-7812. Journal written in English. CAN 101:196815 AN 1984:596815 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Plates of chem. vapor-deposited nonoxide ceramics (Si3N4, SiC, and B4C) up to 3 mm thick were prepd. with high purity and d. at high deposition rates (>1 mm/h). High-resoln. electron microscopy of these materials reveals that there are no glassy layers or secondary phases at any grain boundaries and multiple-grain junctions. Thus, degrdn. of strength and toughness is not obsd. up to 1500; the strength and toughness of the Si3N4 and SiC increase with increasing temp. above 800 and 1100, resp. The effects of preferred orientation, grain size (residual internal stress), and stoichiometry on the mech. properties also were examd.

Bibliographic Information

Effects of water chemistry on the leach resistance of SYNROC C. Woolfrey, J. L.; Levins, D. M. Lucas Heights Res. Lab., Aust. Atomic Energy Comm., Sydney, Australia. Materials Research Society Symposium Proceedings (1984), 26(Sci. Basis Nucl. Waste Manage. 7), 663-70. CODEN: MRSPDH ISSN: 0272-9172. Journal written in English. CAN 101:62325 AN 1984:462325 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The chem. durability of SYNROC-C was measured as a function of repository conditions, namely, temp., surface/vol. ratio, groundwater pH, and compn. The leach rate of SYNROC-C is less dependent on temp. than borosilicate glasses: activation energies range from 15-25 kJ mol-1 compared to 33-74 kJ mol-1 for glass. The rate of release from SYNROC-C is very low and independent of soln. compn. for the solns. studied. There is little variation in leach rate over the pH range 4-9, but at pH 2 the rate is up to 10 times higher. SYNROC-C leach rate is independent of flow rate or surface/vol. ratio for the mobile waste elements because of the unimportance of soln. satn. effects owing to the low concn. of dissolved solids. The differential leach rate decreases rapidly with time because, after initial leaching from grain boundaries and metastable minor phases, the highly insol. matrix protects the more leachable elements from further attack.

Bibliographic Information

Effects of variability of the base powder on the sintering of -silicon carbide. Williams, R. M.; Juterbock, B. N.; Peters, C. R.; Whalen, T. J. Ford Motor Co., Dearborn, MI, USA. Journal of Materials Science Letters (1984), 3(3), 265-7. CODEN: JMSLD5 ISSN: 0261-8028. Journal written in English. CAN 100:160854 AN 1984:160854 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The importance of using starting powders with rigidly controlled chem. and crystallog. compn. and phys. characteristics for sintering of -SiC was investigated. Tests were conducted with 2 lots of sinterable -SiC from the same manufacturer and of the same grade. Differences in particle-size distribution, surface area, and chem. compn., most notably in free C and O contents, were obsd. The morphol. of the 2 materials was similar. The variations obsd. in the phys. properties of the ceramics and in temps. at which phase transformations occur were quite significant in comparison to the property differences of the starting materials.

Bibliographic Information

Microstructure of silicon nitride-titanium nitride composites prepared by chemical-vapor deposition. Hayashi, Shinsuke; Hirai, Toshio; Hiraga, Kenji; Hirabayashi, Makoto. Res. Inst. Iron, Steel Other Met., Tohoku Univ., Sendai, Japan. Journal of Materials Science (1982), 17(11), 3336-40. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 98:21091 AN 1983:21091 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

The shapes and the distribution of TiN within Si3N4-TiN composites prepd. by the chem.-vapor deposition of a SiCl4-TiCl4-NH3-H2 system were examd. using an electron microscope. The TiN dispersion in the amorphous Si3N4 matrix was granular and its max. size was 3 nm. The TiN dispersions in - and -Si3N4 matrices were contained in their resp. crystal grains; however, the shape of the TiN dispersions in the -Si3N4 matrix was different from that in the -Si3N4 matrix. Granular TiN dispersions with an av. size of 10 nm were obsd. in the -Si3N4 matrix. The TiN dispersions in the -Si3N4 matrix were columnar with a diam. of several nm having its axis extended to the direction parallel to the c-axis of the -Si3N4 crystal.

Bibliographic Information

Density and deposition rates of amorphous CVD-silicon nitride (Si3N4) including carbon. Hirai, Toshio; Goto, Takashi. Res. Inst. Iron, Steel Other Metals, Tohoku Univ., Sendai, Japan. Journal of Materials Science (1981), 16(10), 2877-82. CODEN: JMTSAS ISSN: 0022-2461. Journal written in English. CAN 96:39625 AN 1982:39625 CAPLUS (Copyright 2005 ACS on SciFinder (R))

Abstract

Amorphous Si3N4 contg. uniformly distributed C was prepd. by chem. vapor deposition using SiCl4 vapor and NH3, H2, and C3H8 gases at desorption temps. (T) of 1100 to 1300 and at total gas pressures (P) of 30 to 70 torr. The d. of the amorphous Si3N4 deposit was 2.80-3.00 g/cm3, depending upon the deposition conditions. The rate of growth in thickness increased with increasing T and P and had the largest value of 0.6 mm/h at T = 1300, P = 70 torr, and C3H8 gas flow rates of 0 to 20 cm3/min. The activation energy of formation decreased from 38 to 20 kcal/mol with increasing P and C3H8 flow rate.

Bibliographic Information

The delayed neuropathic effects of nerve agents and some other organophosphorus compounds. Gordon J J; Inns R H; Johnson M K; Leadbeater L; Maidment M P; Upshall D G; Cooper G H; Rickard R L Archives of toxicology (1983 Feb), 52(2), 71-82. Journal code: 0417615. ISSN:0340-5761. Journal; Article; (JOURNAL ARTICLE) written in English. PubMed ID 6847383 AN 83203413 MEDLINE (Copyright 2005 U.S. National Library of Medicine on SciFinder (R))

[FUTI]

Mega when a tool as SciDirect or something alike tries to truncate the list I prefer to use PDF995 and print option, and of course print to file. I never tried to look for CAS list though. What search tool/method do you used for this?

[FUTI]

Mega when a tool as SciDirect or something alike tries to truncate the list I prefer to use PDF995 and print option, and of course print to file. I never tried to look for CAS list though. What search tool/method do you used for this?

[FUTI]

Mega when a tool as SciDirect or something alike tries to truncate the list I prefer to use PDF995 and print option, and of course print to file. I never tried to look for CAS list though. What search tool/method do you used for this?

[megalomania]

I used a subscription access to SciFinder Scholar to search the CAS database. The online CAS database can only search back to 1966 or 1967, even though CAS has been around since 1909. A ton of the good old stuff is left off because of that. Of course for any new chemicals make in the past 50 years there is nothing better to search through. I would prefer to use Crossfire as well, but I don't have that (yet).

The CAS database does have every abstract going back to 1909, you just have to have the specific article title and author to get it before the 60s. Maybe they will include the older abstracts someday.

[megalomania]

I used a subscription access to SciFinder Scholar to search the CAS database. The online CAS database can only search back to 1966 or 1967, even though CAS has been around since 1909. A ton of the good old stuff is left off because of that. Of course for any new chemicals make in the past 50 years there is nothing better to search through. I would prefer to use Crossfire as well, but I don't have that (yet).

The CAS database does have every abstract going back to 1909, you just have to have the specific article title and author to get it before the 60s. Maybe they will include the older abstracts someday.

[megalomania]

I used a subscription access to SciFinder Scholar to search the CAS database. The online CAS database can only search back to 1966 or 1967, even though CAS has been around since 1909. A ton of the good old stuff is left off because of that. Of course for any new chemicals make in the past 50 years there is nothing better to search through. I would prefer to use Crossfire as well, but I don't have that (yet).

The CAS database does have every abstract going back to 1909, you just have to have the specific article title and author to get it before the 60s. Maybe they will include the older abstracts someday.

[FUTI]

I think I have or had Crossfire (Beilstein) somewhere sometime ago. And it is an old story...where is that CD? Sometime I think that I will have to find a wife to sort my things up;)
but then again how on earth I'm going to find a wife who will understand/tolerate my hobbies:D. It seems I'm bound to exist in status nascendi. So noble (or not;)) of me. I look up and tell you in a day or two.

[FUTI]

I think I have or had Crossfire (Beilstein) somewhere sometime ago. And it is an old story...where is that CD? Sometime I think that I will have to find a wife to sort my things up;)
but then again how on earth I'm going to find a wife who will understand/tolerate my hobbies:D. It seems I'm bound to exist in status nascendi. So noble (or not;)) of me. I look up and tell you in a day or two.

[FUTI]

I think I have or had Crossfire (Beilstein) somewhere sometime ago. And it is an old story...where is that CD? Sometime I think that I will have to find a wife to sort my things up;)
but then again how on earth I'm going to find a wife who will understand/tolerate my hobbies:D. It seems I'm bound to exist in status nascendi. So noble (or not;)) of me. I look up and tell you in a day or two.