Nitric oxide synthase reduces nitrite to NO under anoxia

Cultured bEND.3 endothelial cells show a marked increase in NO production when subjected to anoxia, even though the normal arginine pathway of NO formation is blocked due to absence of oxygen. The rate of anoxic NO production exceeds basal unstimulated NO synthesis in normoxic cells. The anoxic release of NO is mediated by endothelial nitric oxide synthase (eNOS), can be abolished by inhibitors of NOS and is accompanied by consumption of intracellular nitrite. The anoxic NO release is unaffected by the xanthine oxidase inhibitor oxypurinol. The phenomenon is attributed to anoxic reduction of intracellular nitrite by eNOS, and its magnitude and duration suggests that the nitrite reductase activity of eNOS is relevant for fast NO delivery in hypoxic vascular tissues. Received 20 August 2006; received after revision 21 September 2006; accepted 8 November 2006     

The interaction of superoxide with nitric oxide destabilizes hypoxia-inducible factor-1α

In renal carcinoma cells (RCC4) hypoxia inducible factor-1 (HIF-1) is constitutively expressed due to a von Hippel Lindau protein deficiency, but can be degraded by calpain, independently of the 26S proteasome, when exposed to hypoxia/nitric oxide (NO). In this study we examined molecular mechanisms to explain calpain activation. The inability of hypoxia/NO to degrade HIF-1α in respiratory-deficient RCC4-ρ0 cells pointed to the requirement for mitochondria-derived reactive oxygen species. A prerequisite for O ₂ ⁻ in combination with NO to destabilize HIF-1α was corroborated in RCC4-p0 cells, when the redox cycler 2,3-dimethoxy-1,4-naphthoquinone was used as a source of superoxide. Degradation of HIF-1α required intracellular calcium transients and calpain activation. Using uric acid to interfere with signal transmission elicited by NO/O ₂ ⁻ blocked HIF-1α degradation and attenuated a calcium increase. We conclude that an oxidative signal as a result of NO/O ₂ ⁻ coformation triggers a calcium increase that activates calpain to degrade HIF-1α, independently of the proteasome. Received 14 August 2007; received after revision 4 October 2007; accepted 22 October 2007     

镀锌层军绿色钝化工艺研究

采用铬酐、磷酸二氢钠、硫酸氢钠、OP-10为主要原料,加入合适的添加剂XY-03B,研究成功了一种锌镀层军绿色钝化工艺,探讨了主要成分和工艺条件对钝化膜质量的影响,检测了钝化膜的有关性能,结果表明:所形成的钝化膜为军绿色,膜层光亮鲜艳,附着力好,装饰性好,耐蚀性好,主要性能指标与铬酸盐彩色钝化膜相当.且钝化液稳定,可调性好,钝化液使用寿命长,生产成本低,因而具有较高的应用价值.     

非离子型乳化剂对聚丙烯酸酯乳液性能的影响

在非离子型表面活性剂用量和聚氧乙烯(EO)链长数目变化的条件下制备了纯丙烯酸酯聚合物乳液(简称纯丙乳液),考查了非离子型乳化剂用量和EO链长对乳液聚合稳定性及乳液冻融稳定性,Ca2 稳定性,玻璃化温度(Tg),粒径和黏度的影响.实验结果表明,非离子乳化剂用量和EO链长的增加,有助于乳液聚合反应的平稳进行,得到的乳液粒径较小,黏度较大,Tg较低,乳液的冻融稳定性和Ca2 稳定性显著提高.     

纳米复合Li2SO4质子传导膜H2S中温燃料电池

开发了一种制备纳米复合Li_2SO_4质子传导电解质和膜电极组装(MEA)的工艺.与传统的丝网涂布工艺不同,新的制备工艺是将阳极、阴极催化剂与纳米复合电解质同时一次压制成MEA.这就使得MEA的设计具有某些结构上的特点,由于膜厚减少和电极与电解质之间的接触良好,可以降低电解质与电极之间的欧姆电阻,提高其机械和导电性能,增加膜的质子传导性以及改善电池的性能.用电子扫描电镜(SEM)和电化学阻抗分析技术对电解质薄膜进行了表征,结果表明,纳米复合材料改善了MEA的总体性能.由于膜的致密性和不透气性,不会发生气体穿透过膜的现象.MEA在H_2S环境中很稳定.电池结构为H_2S,(MoS_2/NiS Ag 电解质量 淀粉) /Li_2SO_4 Al_2O_3/(NiO Ag 电解质量 淀粉),空气、MEA厚为0.8mm、电解质组成为65% Li_2SO_4 35% Al_2O_3的单电池在680℃时产生最大功率密度为130mW/cm~2,相应的电流密度为200mW/cm~2.     

4ZnO·B2O3·H2O微米棒的水热合成及阻燃性能

在表面活性剂三乙醇胺存在的条件下,以Zn(NO3)2.6H2O和H3BO3为原料,利用水热反应制备出分散均匀的4ZnO.B2O3.H2O微米棒.利用X-射线粉末衍射、热重-差示扫描量热、红外及扫描和透射电镜对微米棒的物相、组成、表面结构及形貌进行了分析.研究表明:所制备的硼酸锌微米棒分散均匀,直径为0.2~0.5μm,长度为5~10μm;400℃时,添加10%(质量分数)的硼酸锌微米棒可使杨木粉的残炭量比未添加硼酸锌的提高18.69%,极限氧指数达43.2,说明硼酸锌微米棒具有良好的阻燃性能.     

铜(Ⅱ)和锌(Ⅱ) 的二烷基膦酸萃取平衡研究

针对萃取溶剂对萃合物组成的影响，研究了（ＮＨ４）２ＳＯ４介质中二（２－乙基己基）膦酸的ＮａｐｈｔｅｚｏｌＭ溶液对铜（Ｉ）和锌（Ｉ）的萃取平衡，测得其ｐＨ０．５值分别为２．２４和３．７３，籍助斜率分析和数值计算法确定了萃合物组成分别为（ＺｎＲ２·２ＨＲ）２，（ＺｎＲ２·６ＨＲ）２，（ＣｕＲ２·２ＨＲ）２和（ＣｕＲ２·６ＨＲ）２，并计算了对应的萃取平衡常数。     

稀释剂对HEHEHP萃取锌（Ⅱ）的影响

研究了不同稀释剂中，２－乙基己基膦酸单（２－乙基己基）酯从硝酸介质中对Ｚｎ（Ⅱ）的萃取，其萃取能力在不同稀释剂中按正己烷〉四氢化碳〉苯〉氯仿的顺序变化。萃取平衡常数与稀释剂的极性参数ＤＰ、Ｓ间呈线性关系。     

光合成环氧丙烷新技术研究进展

文章介绍了光氧化或光催化氧化丙烯合成环氧丙烷新技术及其进展，这种新技术具有洁净、安全、操作简单的优点