O2 and H2S coexistence in stromatolites

The coexistence of O₂ and H₂S in recent microbial mats is demonstrated. Oxygen and H₂S are not only coexisting in considerable concentrations within recent stromatolites but high concentrations of the respective gases occur in alternating laminae. This “sandwich structure” is produced by alternating populations of oxygenic and anoxygenic photosynthetic bacteria and cyanobaeteria. The finding of such conditions may explain the alternation of oxidized and reduced iron minerals in Precambrian stromatolites and possibly also in the banded iron formations (BIFs).     

Identification and electrophysiological studies of (4S,5S)-5-hydroxy-4-methyl-3-heptanone and 4-methyl-3,5-heptanedione in male lucerne weevils

An investigation to identify a sex or aggregation pheromone of Sitona discoideus Gyllenhål (Coleoptera: Curculionidae) is presented. Antenna flicking and attraction behaviors evoked by conspecifics of both sexes were recorded in arena bioassays, where attraction of females to males was observed. Air entrainment of both males and females was conducted in separate chambers. Gas chromatographic–mass spectrometric analysis of headspace volatiles revealed that two male-specific compounds, 4-methyl-3,5-heptanedione (major) and (4S,5S)-5-hydroxy-4-methyl-3-heptanone (minor), were emitted during the autumnal post-aestivatory flight period. The stereoisomers of the minor component were separated by enantioselective gas chromatography and their absolute configurations assigned by NMR (diastereomers) and the known preference of enantioselective transesterification reactions catalyzed by Candida antarctica lipase B. Electroantennogram and single sensillum recording studies indicate that 4-methyl-3,5-heptanedione as well as all individual stereoisomers of 5-hydroxy-4-methyl-3-heptanone are detected by the antennae of male and female S. discoideus. Further, single sensillum recordings suggest that both sexes of S. discoideus have specialized olfactory receptor neurons (ORNs) for detecting 4-methyl-3,5-heptanedione and different populations of stereoselective ORNs for detecting the stereoisomers of 5-hydroxy-4-methyl-3-heptanone. Some of these stereoselective ORNs appear to be sex-specific in S. discoideus.     

Cu2+/Na2S2O8体系中自由基的研究

利用自由基与乙醇和叔丁醇之间反应速率差异,研究在不同条件下Cu2+/Na2S2O8体系中产生自由基的状况.实验研究表明:Na2S2O8体系会产生·OH和SO-4由于Cu2+的催化作用,使用Cu2+Na2S2O8体系比单独使用Na2S2O8能产生更多的自由基·OH和SO-4.研究还发现:pH值降低能促进Na2S2O8分解产生自由基,但是会抑制SO-4转化为·OH;温度升高,Na2S2O8分解产生的·OH和SO-4均增加.     

H2S废气处理研究进展

回顾了国外近几年的硫化氢（H2S）废气处理方法及未来研究方向。研究表明,生物法、吸收法、吸附法依然占据主导地位,但研究内容更为深入,涉及面更广泛。有关H2S在环境中的逸散模型的建立和降解反应机理模型表述亦受到关注,这对于环境中H2S浓度的预测、采取相应的处理方法和提高环境管理水平有着深远的意义。     

汽车4S店有机废气治理技术分析

总结了汽车4S店废气中挥发性有机物来源及危害,在评价常规有机废气治理技术基础上,对比分析了催化燃烧、光催化、等离子体技术的成本,并提出适合处理4S废气的组合工艺。