Photosensitizers neutral red (type I) and rose bengal (type II) cause light-dependent toxicity in Chlamydomonas reinhardtii and induce the Gpxh gene via increased singlet oxygen formation

The connection between the mode of toxic action and the genetic response caused by the type I photosensitizer and photosynthesis inhibitor neutral red (NR) and the type II photosensitizer rose bengal (RB) was investigated in the green alga Chlamydomonas reinhardtii. For both photosensitizers, a light intensity-dependent increase in toxicity and expression of the glutathione peroxidase homologous gene (Gpxh) was found. The toxicity of RB was reduced by the singlet oxygen (1O2) quenchers 1,4-diazabicyclo[2.2.2]octane and L-histidine, and the RB-induced Gpxh expression was stimulated in deuterium oxide-supplemented growth medium. These observations clearly indicate the involvement of 1O2 in both toxicity and the genetic response caused by RB. NR up-regulated the expression of typical oxidative and general stress response genes, probably by a type I mechanism, and also strongly induced the Gpxh expression. The stimulating effect of deuterium oxide in the growth medium suggested the involvement of 1O2 also in the NR-induced response. Indeed, an increased 1O2 formation was detected with EPR-spin trapping in NR-treated spinach thylakoids. However, none of the 102 quenchers could reduce the light-dependent toxicity of NR in C. reinhardtii, indicating that NR has a different mode of toxic action than RB.     

车站地下方厅浅埋施工中监控量测技术

根据以往地铁施工经验,结合北京城市铁路东直门车站地下方厅工程实际施工情况,用有限元分析法分析地表位移,对围岩受力进行监控,根据结果指导施工,保证施工安全.     

Differential mobility spectrometry of isomeric protonated dipeptides: modifier and field effects on ion mobility and stability

The ability to resolve isomeric protonated dipeptides was investigated with the new technique of differential ion mobility mass spectrometry that uses "modifier" molecules to enhance differential mobility. Two pairs of protonated peptides [glycine-alanine (GlyAla) and alanine-glycine (AlaGly), glycine-serine (GlySer) and serine-glycine (SerGly)] and eight different modifiers (water, 2-propanol, 1,5-hexadiene, 2-chloropropane, chlorobenzene, dichloromethane, acetonitrile, and cyclohexane) were used in the initial study. Separation of the protonated peptides was found to be dependent on the mass and proton affinity of the modifier and combinations of functionalities present in the modifier and the analyte ion. Six of the eight modifiers (water, 2-propanol, chlorobenzene, cyclohexane, dichloromethane, and acetonitrile) were able to separate the protonated isomeric peptide pairs, and generally, modifiers with electron-rich groups performed the best. In the presence of some modifiers, a reduction of ion current was observed under the highest field conditions (>115 Td). Dopant-catalyzed isomerization, likely by proton-transport catalysis, and field-induced fragmentation may have contributed to these losses. Two high vapor pressure modifiers, 1,5-hexadiene and 2-chloropropane, significantly influenced ion formation leading to the formation of stable cluster populations that could be observed in the mass spectrometer. Although not a major concern, both fragmentation and influence of modifier evaporation warrant further studies in order to fully understand and possibly eliminate them.     

107工作面超高巷道治理技术

滕东煤矿3下107两顺槽有部分巷道超高,巷道高度4200～5000mm,宽度4200～4600mm,巷道坡度5-16°。通过在超高处装设连体木垛,使巷道顶板更加完整,有效地防治冲击地压,促进了安全生产。     

光度分选机——加工含金矿石有希望的设备

光度分选机是高新技术型设备，其工艺流程简单，灵敏度高，生产能力为１５０ｔ／ｈ，可加工含金贫矿石和平衡表外矿石，对生态无危害。