近红外区N－H和O－H振动吸收谱带在定性定量分析中的应用

本研究介绍了如何应用近红外光谱对Ｎ─Ｈ、Ｏ─Ｈ等官能团进行定量分析，以及如何应用近红外光谱法研究金属氧化物的表面羟基与其催化活性的关系。     

Fabrication and magnetic properties of Co nanowire arrays of different crystal structures

It is important to find some developing high-density magnetic recording materials in magnetic recording field with the development of information and technique, in which vertical magnetic recording is a very important way and has received considerable attention[1—3]. The vertical magnetic recording materials require high squareness, suitable coercivity, and small size of storage element[4]. Someone used nanoporous anodic aluminum oxide as templates to fabricate uniform arrays of multi magneti…     

Novel aspects of glypican glycobiology

Mutations in glypican genes cause dysmorphic and overgrowth syndromes in men and mice, abnormal development in flies and worms, and defective gastrulation in zebrafish and ascidians. All glypican core proteins share a characteristic pattern of 14 conserved cysteine residues. Upstream from the C-terminal membrane anchorage are 3–4 heparan sulfate attachment sites. Cysteines in glypican-1 can become nitrosylated by nitric oxide in a copper-dependent reaction. When glypican-1 is exposed to ascorbate, nitric oxide is released and participates in deaminative cleavage of heparan sulfate at sites where the glucosamines have a free amino group. This process takes place while glypican-1 recycles via a nonclassical, caveolin-1-associated route. Glypicans are involved in growth factor signalling and transport, e.g. of polyamines. Cargo can be unloaded from heparan sulfate by nitric oxide-dependent degradation. How glypican and its degradation products and the cargo exit from the recycling route is an enigma.Received 27 November 2003; received after revision 8 January 2004; accepted 13 January 2004     

Nitric oxide mediates histamine induced down-regulation of H<Subscript>2</Subscript> receptor mRNA and internalization of the receptor protein (R1)

During agonist-dependent long-term stimulation of cells, histamine receptor subtypes are frequently down-regulated. However, the mechanisms underlying the modulation of receptor expression during long-term histamine stimulation have yet to be resolved. Based on our recently reported results showing an H₁-mediated down-regulation of histamine H₂ receptor mRNA in endothelial cells, our aim was to characterize the mechanism controlling rapid and long-term histamine-mediated modulation of H₂ receptor expression in more detail. We were able to show that the histamine-induced down-regulation of H₂ receptor mRNA and cell surface expression lasting for 24 h was accompanied by augmentation of the receptor protein level in the cytoplasmatic fraction of endothelial cells for this time period. Furthermore, changes in receptor protein levels in whole-cell lysate were negligible, indicating that the rapid and prolonged modulation of cell surface H₂ receptor levels by histamine was regulated solely via internalization. The role of nitric oxide (NO) as a key mediator in histamine-stimulated cell responses was underlined by subsequent studies showing the attenuation of histamine-induced H₂ receptor mRNA down-regulation and protein trafficking following NO synthase isozyme inhibition.Received 11 March 2003; received after revision 11 June 2003; accepted 17 June 2003     

Involvement of nitric oxide in the signal transduction of salicylic acid regulating stomatal movement

The effects and the relationship between sali-cylic acid(SA)and nitric oxide(NO) on Vicia faba L.stomatal movement were studied.The results here showed that exogenous SA and NO induced stomatal closure,100μmol/L SA induced a rapid and striking NO increase in the cytosol of guard cells.This phenomenon was largely prevented by 2000μmol/L 2-phenyl-4,4,5,5-tetramethylimidazoline-l-oxyl-3-oxide(PTIO),a specific NO scavenger,and 25μmol/L N^G-nitro-L-Arg-methyl eater (L-NAME),an inhibitor of NO synthase(NOS) in mammalian cells that also inhibits plant NOS.In addition,SA-induced stomatal closure was largely prevented by PTIO and L-NAME.These results provide evidence that guard cells generate NO in response to SA via NOS-like activity,and that such NO production is required for full stomatal closure in response to SA.H-(1,2,4)-oxadiazole-[4,3-α]quinoxalin-l-one(ODQ),an inhibitor of guanylate cyclase,and nicotinamide,an antagonist of cADPR production,inhibited the effects of SA-and NO-induced stomatal closure.It suggests that both cGMP and cADPR might mediate the signal transduction of SA and NO-induced stomatal closure.     

Homocysteine increases the synthesis of adrenomedullin in vascular fibroblasts of rats

Homocysteine (Hcy), a highly reactive sulfur- containing amino acid, is an intermediate product of methionine metabolism. Elevation of plasma Hcy has been widely studied as an independent risk factor for many cardiovascular diseases such as atherosclerosis, thrombosis, etc.[1]. Inherited hyperhomocysteinemia cases usually suffer from occlusion or thrombosis in arteries and large veins before the age of 20. Hyperhomocysteinemia significantly reduces the survival rate[2] and dilatation functi…     

纳米ZnO光催化有机磷农药降解的研究

研究纳米氧化锌对三种有机磷农药的降解情况，考查了催化剂及其用量、光照时间、pH值的影响，结果表明纳米氧化锌能使有机磷农药发生降解。实验结果还表明不同形貌的氧化锌在降解有机磷农药时其效果不一样，网状比粒状所需要时间要短，这可能因为网状的粒径比较小，与降解体系接触空间更大。     

氧化锌催化合成松香甘油酯的最佳工艺条件

本文用氧化锌作催化剂,松香与甘油为原料进行酯化反应,合成松香甘油酯.实验首先通过反应温度、反应时间、醇酸比等单一因素对酯化反应的大致影响.然后采用正交实验法,考虑三个因素,三个水平对产物的影响,得出最佳的反应条件：反应温度为270℃、反应时间为8h、松香与甘油的物质的量比2.5：1.该条件下,产品的酸值为8.94mgKOH/g,酯化率为94.4%.最后,用红外光谱对产品作出相应的分析.氧化锌具有催化活性大,选择性高,不腐蚀设备等优点,适合现代工业的需要,是一种良好的催化剂.     

YSZ包覆NiO阳极的SOFC发电性能(英文)

采用NH3·H2O-NH4HCO3为缓冲溶液,共沉淀法制备YSZ包覆NiO的NiO-YSZ阳极材料,分析了材料的物相和粒径大小。分别以YSZ包覆的NiO、商用NiO/YSZ为阳极,LSM为阴极,制作YSZ电解质支撑的板状固体氧化物燃料电池,进行发电性能比较。以YSZ包覆的NiO为阳极的电池,功率密度高、极限电流密度大。扫描电镜观察表明,YSZ包覆的NiO制作的阳极表面形成了的网状结构。阳极三相界面、孔隙率提高,是电池性能提高的原因。     

静电纺氧化铝纳米纤维研究

采用溶胶-凝胶法,以聚乙烯醇、硝酸铝、水为原料配制出了硝酸铝/聚乙烯醇溶胶-凝胶纺丝液,并通过静电纺丝技术纺制了Al(NO3)3/PVA有机-无机杂化纤维,经高温锻烧后得到了平均直径约为50～250nm无机纳米氧化铝纤维。