Pt—Rh合金电极上氢的吸附过程的研究

采用快速阴极动电位扫描方法对Ｐｔ－Ｒｈ合金电极上氢的吸附过程进行了研究。随着合金当中Ｒｈ含量的增加，氢的强键吸附峰值逐渐减少，在Ｗ（Ｒｈ）＝５０％－６０％合金 已表现为象肩膀一样的平台，而到百分之百的Ｒｈ时完全消失。     

标准氢电极的探讨

本文指出了标准氢电极存在的问题,讨论了选择标准氢电极的电子导体问题,建议采用氢电极为电极电势的参考电极,这种氢电极是由浸在H~+离子溶液中的镀铂黑的铂片构成,H~+离子的浓度是每千克水中有1摩尔氢离子,氢气泡的压力为1大气压     

尼古丁-FET传感器的研制

尼古丁是烟草中最重要的生物碱。本文报导以四苯硼酸尼古丁缔合物为活性材料,研制了尼古丁场效应管传感器,测试了器件的性能参数,获得满意的结果。其线性范围在10~(-1)～10~(-4)mol/l,斜率为56±1mV/pc,适用的 pH 范围在5.5～7.5之间。     

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     

Electrocatalytic oxidation of H<Subscript>2</Subscript>O<Subscript>2</Subscript> at a carbon paste electrode modified with a nickel (II)-5, 11, 17, 23-tetra-tert-butyl-25, 27-bis(Diethylcarbamoylmethoxy) calix[4] arene complex and its application

Electrochemical behavior of a carbon paste electrode (CPE) modified with nickel(II)-5, 11, 17, 23-tetra-tert-butyl-25, 27-bis(diethylcarbamoylmethoxy) calix[4]arene (Ni (II)-L) complex and its electrocatalytic activity towards the oxidation of hydrogen peroxide were investigated by cyclic voltammetric technique in a 5.0×10⁻² mol/L NaClO₄+1.0×10⁻³ mol/L NaOH solution. It was found that Ni(II)-L acts as an effective catalyst for the oxidation of hydrogen peroxide. The modified electrode exhibited a linear response over a hydrogen peroxide concentrations in the range of 2.0×10⁻⁵−1.0×10⁻⁴ mol/L with a detection limit as low as 1.0×10⁻⁶ mol/L. The relative standard deviation was 3.5% for 5 successive determinations of H₂O₂ at 1.0×10⁻⁵ mol/L. The modified electrode was used successfully in rainwater analysis. Foundation item: Supported by the Natural Science Foundation of Hubei Province (98J040). Biography: Li Chun ya(1972-), Ph. D. candidate, research direction: electroanalysis and electrosynthesis.     

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     

圆柱形和三角形电极的EHD强化管内沸腾换热试验研究

以R-123为工质,对圆柱形电极和三角形电极进行了电水动力学(EHD)强化管内核沸腾换热试验研究。试验换热管为垂直套管式,外层为加热水路,内层为工质回路,中心布置着电极。电场强度范围为0～2.133MV/m,热流密度范围为1.5～10.0kW/m2,换热系数的误差为±9.7%;相应的强化因数的误差为±12.2%。结果表明:两种电极的最大强化因数接近,分别为2.15和2.11;在达到最大强化因数时,三角形电极所需要施加的平均电场强度和能耗比圆柱电极低得多。     

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…