富氧底吹鼓风还原系统高温电除尘器

铅是热和电的不良导体 ,铅烟尘是工业炉窑中很难净化的烟尘。为解决这一难题 ,对富氧底吹鼓风还原工艺中的静电除尘器进行了整改 ,取得了较好的效果。

硒蛋白的抗氧化作用

硒的抗氧化作用与机体的免疫、衰老、疾病、凋亡等方面密切相关,并且由于缺硒而导致的疾病中,大部分是由于氧化损伤导致的。为此,对硒及硒蛋白的抗氧化作用进行了综述。

镰刀菌酸毒素对西瓜幼苗根细胞跨膜电位及叶细胞有关抗逆酶的抑制

【目的】了解引起连作西瓜严重枯萎病的尖孢镰刀菌毒素对西瓜幼苗根和叶细胞有关生理功能的影响。【方法】用从尖孢镰刀菌西瓜专化型菌株提取的真菌毒素镰刀菌酸处理西瓜幼苗,考察其对细胞根系跨膜电位和叶片中相关抗逆酶的影响。【结果】高浓度镰刀菌酸处理西瓜幼苗12h后,根部细胞跨膜电位比对照下降61.9%～81.8%。不同浓度的毒素处理24h后,根系脱氢酶活性减少35.9%～90.9%。镰刀菌酸明显加速了叶片细胞膜脂质过氧化,24h后叶片丙二醛含量是对照的5.2～11.0倍。叶片中的苯丙氨酸解氨酶活性先增加,然后减少,6～12h活性最高,为对照的7.2～10.5倍。过氧化氢酶、超氧化物岐化酶、过氧化物酶也是先上升然后下降。过氧化氢酶活性在毒素处理3h后达到高峰,但再过3h后下降18.6%～52.5%。超氧化物岐化酶和过氧化物酶在毒素处理12h后达到最大,然后下降。叶片中的β-1,3-葡聚糖酶和几丁质酶在毒素处理后先快速上升,然后下降,最大活性分别出现在处理后12h和3h,分别是对照的10和15～30倍。【结论】镰刀菌酸强烈抑制了西瓜幼苗的根和叶细胞正常生理功能。破坏了叶片细胞的正常防卫系统和根细胞吸水和运输功能,引起细胞膜脂质过氧化生成大量的丙二醛,细胞结构遭受严重破坏,导致发病甚至细胞死亡。

Effect of osmotic shock on the redox system in plasma membrane of Dunaliella salina

The unicellular halotolerant alga Dunaliella salina had the ability to oxidize NADH and reduce Fe(CN)63-. The redox reactions were to some extent stimulated by slight hyperosmotic shock (2.0 mol/L → 2.6 mol/L NaCl), butmarkably inhibited by abrupt hyperosmotic shock (2.0mol/L → 3.5 mol/L NaCl) and hypoosmotic shock (2.0mol/L → 1.0 mol/L NaCl; 2.0 mol/L→0.67 mol/L NaCl).With the adaptation of algal cells to osmotic shock by accumulating or degrading intracellular glycerol, the plasmalemma redox activities were also restored. The O2 uptake stimulated by NADH could be promoted by FA and SHAM. Hypoosmotic shock increases the basal respiration rate of alga cells, but weakened the stimulating effects of NADH, FA and SHAM on O2 uptake. On the other hand, hyperosmotic shock reduced the basal respiration rate, but relatively enhanced the above effects of NADH, FA and SHAM. H+ extrusion of alga cells was inhibited by NADH and stimulated by Fe(CN)63- Vanadate and DES could inhibit H+ efflux, but had little effect in the presence of NADH and Fe(CN)63-. Both hyperand hypoosmotic shock stimulated H+ extrusion. This effect could be totally inhibited by vanadate and DES, but almost unaffected by 8-hydroxyquinoline. It was suggested that H+-ATPase probably played a more important role in H+ extrusion and osmoregulation under the conditions of osmotic shock.

Investigation of the redox status in H22 hepatocellular carcinoma xenografts treated by a novel anticancer drug-ethaselen

We investigated the redox status of H22 hepatocellular carcinoma xenografts treated with various doses of ethaselen, a novel anticancer drug targeting thioredoxin reductase （TrxR）. The concentrations of low molecular weight antioxidant g!utathione （GSH） and malondialdehyde （MDA）, a product of lipid peroxidation, as well as the activities of important antioxidant enzymes were measured for elucidating the redox status of H22 tumor tissues. We found that the decreased GSH level, decreased thioredoxin reductase and superoxide dismutase （SOD） activities as well as increased MDA content were closely related to the tumor growth inhibition and ethaselen doses. Glutathione peroxidase （GPx） and glutathinne reductase （GR） activities are also affected by ethaselen treatment. However, the catalase （CAT） activity remains unchanged. Finally, we studied the relationship of tumor growth inhibition caused by ethaselen with these redox factors. This study showed that ethaselen could elevate the oxidative stress to suppress the H22 tumor growth in mice model.

Synthesis of NAD analogs to develop bioorthogonal redox system

Three new nicotinamide adenine dinucleotide(NAD) analogs were synthesized,and their characteristics as cofactors for Escherichia coli malic enzyme(ME) and its double mutant ME L310R/Q401C were analyzed.Each pair of the NAD analog and the double mutant showed good orthogonality to the natural pair of NAD and ME in terms of catalyzing oxidative decarboxylation of L-malic acid.Results indicated that molecular interactions between redox enzyme and cofactor could be further explored to generate new bioorthogonal redox systems.

Driving mechanisms of nitrogen transport and transformation in lacustrine wetlands

As an essential component of proteins and genetic material for all organisms, nitrogen(N) is one of the major limiting factors that control the dynamics, biodiversity and functioning of lacustrine wetlands, in which intensified N biogeochemical activities take place. Reactive N loaded into wetland ecosystems has been doubled due to various human activities, including industrial, agricultural activities and urbanization. The main driving mechanisms of N transport and transformation in lacustrine wetlands are categorized to pushing forces and pulling forces in this study. Geomorphology, wetland age, N concentrations, and temperature are the main pushing forces(passive forces); whereas water table variation, oxygen concentration, other elements availability, oxidation-reduction potential(Eh) and p H, and microorganisms are the predominant pulling forces(active forces). The direction and kinetic energy of reactions are determined by pulling forces and then are stimulated by pushing forces. These two types of forces are analyzed and discussed separately. Based on the analysis of driving mechanisms, possible solutions to wetland N pollutions are proposed at individual, regional and global scales, respectively. Additional research needs are addressed to obtain a thorough understanding of N transport and transformations in wetlands and to reduce detrimental impacts of excessive N on such fragile ecosystems.

Studies on the roles of vanadyl sulfate and sodium nitrite in catalytic oxidation of benzyl alcohol with molecular oxygen

An efficient catalytic system consisting of vanadyl sulfate/sodium nitrite was disclosed previously for the oxidation of benzylic alcohols into aldehydes with molecular oxygen.However,the roles of catalyst components were not investigated.In this paper,we examined catalytic oxidation of benzyl alcohol as a model reaction,especially by infrared spectroscopy.The role of each component is discussed including nitrite,vanadyl,sulphate,and water.Sodium nitrite could be converted into nitrate and nitric acid.The vanadium(IV)could be smoothly oxidized into vanadium(V)under mild and acidic conditions without any organic ligands.The transformation of sulfate and bisulfate,the cessation of an induction period,and the oxidation of benzyl alcohol were closely interrelated.The multiple roles of water are discussed,including reduction of the induction period,participation in redox cycles of nitric compounds,deactivation of vanadium,and as a byproduct of oxidation.This study contributes to further development of aerobic oxidation using vanadium based catalysts.