Aging of soman-inhibited acetylcholinesterase: PH-rate profiles and temperature dependence in absence and in presence of effectors.

The influence of pH and temperature upon the dealkylation (aging) of soman-inhibited acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) was investigated. The pH-rate profile, as measured at 5 degrees C, shows a maximum aging rate at pH 5.0 and indicates the involvement of two ionizable groups with pKa values of 6.0 and 4.5. The pH-rate profile was not changed essentially by the two effector compounds, semicarbazide and HH54. the activation energy of aging at pH 7.0 was determined as to 6.12 x 10(4) J/mol; it was lowered by the accelerator of aging semicarbazide to 5.28 x 10(4) J/mol and increased to 9.42 x 10(4) J/mol by the retarding compound HH54.

Concentrations of selected contaminants in cabin air of airbus aircrafts.

The concentrations of selected air quality parameters in aircraft cabins were investigated including particle numbers in cabin air compared to fresh air and recirculation air, the microbiological contamination and the concentration of volatile organic compounds (VOC). The Airbus types A310 of Swissair and A340 of Lufthansa were used for measurements. The particles were found to be mainly emitted by the passengers, especially by smokers. Depending on recirculation filter efficiency the recirculation air contained a lower or equal amount of particles compared to the fresh air, whereas the amount of bacteria exceeded reported concentrations within other indoor spaces. The detected species were mainly non-pathogenic, with droplet infection over short distances identified as the only health risk. The concentration of volatile organic compounds (VOC) were well below threshold values. Ethanol was identified as the compound with the highest amount in cabin air. Further organics were emitted by the passengers--as metabolic products or by smoking--and on ground as engine exhaust (bad airport air quality). Cleaning agents may be the source of further compounds.