No abstract

We have shown that in the presence of a reactive substrate, chlorinated organic compounds can be dehalogenated by mechanical treatment, and a specific reaction product can be obtained. We have used a ball milling process at low temperature and atmospheric pressure to produce a dechlorination of up to 100% for both liquid and solid chlorinated compounds. The products of the completed reaction for trials with hexachlorobenzene and chlorobenzene were both principally restricted to benzene and chloride salts. The use of CaH2 as a source of active hydrogen produces a much more specific reaction in significantly less time in comparison with CaO and MgO substrates reacted under hydrogen atmosphere. The process was found to depend on the injected mechanical energy and the collision frequency. In the case of hexachlorobenzene, an explosive-type reaction was observed to occur at specific milling times as a function of the kinetic energy employed.

Plasmodium falciparum parasites grew normally in glutathione (GSH)-depleted normal and G6PD-deficient (Mediterranean variant) erythrocytes (RBC). Growth inhibition was observed only at less than approximately 6^12% residual GSH. Parasites studied separately with the Sendai virus technique synthesized GSH de novo and regenerated reduced GSH 10^20 times faster than non-parasitized RBC. Electron spin resonance measurement of Tempol reduction indicated that the ability to reduce free radicals was restricted to the parasite. The marked efflux of oxidized GSH was mainly derived from the parasite. In conclusion, parasites are endowed with powerful and hostindependent mechanisms which de novo synthesize or regenerate GSH and allow undisturbed parasite development in GSHdepleted RBC.z 1998 Federation of European Biochemical Societies.

We report experimental evidence of transition scenarios during the chemical evolution in an unstirred closed Belousov−Zhabotinsky (BZ) system. We demonstrate that during its chemical evolution the system spontaneously gives the following sequence of dynamic behavior before reaching equilibrium:  period-1 → quasiperiodicity → chaos → quasiperiodicity → period-1. Two transition scenarios are observed:  at the onset of chaos and at its end. One appears as the mirror image of the other. Our observations support the view that closed chemical systems also are able to show chaotic behavior and the corresponding transition scenarios.

EPR and !H ENDOR Study of the Solution Equilibria of Bis(2-ethyl-2-hydroxybutanoato(2-) )oxochromate(V) and Bis(2-hydroxy-2-methylbutanoato(2-))oxochromate(V)