An approach to decontamination of biological endospores is discussed. Specifically, the performance of an aqueous modified Fenton reagent is examined. A modified Fenton reagent formulation of cupric chloride, ascorbic acid, and sodium chloride is shown to be an effective sporicide under aerobic conditions. The traditional Fenton reaction involves the conversion of hydrogen peroxide to hydroxyl radical by aqueous ionic catalysts such as the transition metal ions. Our modified Fenton reaction involves the conversion of aqueous dissolved oxygen to hydrogen peroxide by an ionic catalyst (Cu 2؉ ) and then subsequent conversion to hydroxyl radicals. Results are given for the modified Fenton reagent deactivating spores of Bacillus globigii. A biocidal mechanism is proposed that is consistent with our experimental results and independently derived information found in the literature. This mechanism requires diffusion of relatively benign species into the interior of the spore, where dissolved O 2 is then converted through a series of reactions which ultimately produce hydroxyl radicals that perform the killing action.

In PEM fuel cells, cerium migration is influenced by proton flux,as well as gradients in electric potential, ion concentration, andwater content. These factors were investigated in ex situexperiments and in operating fuel cells. Potential-inducedmigration was measured ex situ in hydrated window cells. CeriumcontainingMEAs were also fabricated and tested under ASTs.MEA disassembly and subsequent XRF analysis were used toobserve rapid cerium migration within the MEA. During MEA hotpressing, humidification, and low RH operation at OCV, ionicdiffusion causes uniform migration from the membrane into thecatalyst layers. During high RH operation at OCV, in-plane ceriumgradients arise due to variations in water content. These gradientsmay diminish the scavenging efficacy of cerium by reducing itsproximity to generated radicals.

Accelerated Stress Tests (ASTs) to characterize carbon corrosion were performed on MEAs based on 3 different carbon supports. High surface area carbon exhibited the best initial performance but the fastest degradation rate. On the other hand, highly graphitized carbon exhibiting the slowest degradation rate but had the lowest initial performance. TEM analysis of the MEAs after corrosion indicated Pt particle size growth in all the catalyst layers in addition to significant thinning of the high surface area carbon-based catalyst layers. Voltage loss breakdown identified mass transport losses resulting from a compaction of the catalyst layer porosity as the greatest contributor to performance loss. Three different membrane ASTs were performed on 2 distinct MEAs (designated P5 and HD6) from Ballard Power Systems and the degradation compared to that observed in the field. The membrane chemical degradation AST resulted in significant membrane thinning not observed in the field. The membrane mechanical degradation AST was able to reproduce the degradation phenomenon observed in the field but had little ability to distinguish between various membranes. A combined mechanical/chemical AST was examined to better simulate the degradation rates observed in the field.

The DOE Fuel Cell technical team recommended ASTs were performed on 2 different MEAs (designated P5 and HD6) from Ballard Power Systems. These MEAs were also incorporated into stacks and operated in fuel cell bus modules that were either operated in the field (three P5 buses) in Hamburg, or on an Orange county transit authority drive cycle in the laboratory (HD6 bus module). Qualitative agreement was found in the degradation mechanisms and rates observed in the AST and in the field. The HD6 based MEAs exhibited lower voltage degradation rates (due to catalyst corrosion) and slower membrane degradation rates in the field as reflected by their superior performance in the high potential hold and open-circuit potential AST tests. The quantitative correlation of the degradation rates will have to take into account the various stressors in the field including temperature, relative humidity, start/stops and voltage cycles.

Issues associated with deactivating clumped spores of a biological pathogen are discussed within the context of decontaminating a civil facility using reactive gases. It is argued that gases wiH prove necessary to hlly complete a decontamination and restoration operation following contamhation with a biological pathogen. This is simply due to the fact that pathogenic agents may have found their way into hidden and otherwise inaccessible spaces, such as air ducts and cracks, where liquid-based reagents may prove impractical to employ. Results are given for ozone de-activating both clumped and dirty spores of the pathogen surrogate B. globigii. Re-hydration of dry spores is found to greatly enhance the effectiveness of ozone. The re-hydration process is found to require hours if moist air is employed'as the source of water. At high relative humidity, capillary condensation of water within spore clumps is found to adversely effect the global deactivation rate in clumped spores. The cleanliness of the spores did not significantly affect the global kinetics. Using selected electronic materials, estimates of collateral damage induced by the reactive gas are also reported. I