生物小分子的电分析化学研究 Ⅱ.鸟嘌呤、腺嘌呤和次黄嘌呤在粗热解石墨电极上的分子定向和表面相互作用

本文讨论了鸟嘌呤、腺嘌呤和次黄嘌呤等嘌呤类生物小分子在几种电极上的反应活性,并选用粗热解石墨电极研究了它们的电化学性质.实验结果表明它们的电极过程是受吸附作用控制的.在粗热解石墨电极上鸟嘌呤以C(2)-NH~2、腺嘌呤以C(6)-NH~2、次黄嘌呤以N(1)-H基团按垂直方向吸附于电极表面,电极表面分子间存在着相斥的相互作用.鸟嘌呤、腺嘌呤和次黄嘌呤的吸附平衡常数分别为:(3.34±1.00)×10^5,和(4.38±1.20)×10^5和(4.13±1.21)×10^5;吸附能分别为:(31.5±0.77),(32.1±0.70)和(32.0±0.75)kJ/mol.这些数值表明它们在粗热解石墨电极上具有中等偏强的物理吸附作用.     

(R)-N-(β-三氯锗丙酰基)四氢噻唑-2-硫酮-4-羧酸甲酯的合成及其晶体结构

三氯锗丙酰氯与(R)-四氢噻唑-2-硫酮-4-羧酸甲酯反应, 得到标题化合物1, [α]~D^2^0-89.40°。经水解得到取代丙酰四氢噻唑-2-硫酮-4-羧酸甲酯基锗倍半氧化物2, X射线衍射法测出标题化合物的晶体结构, 属于正交晶系, 晶胞参数: a=0.6192(1)nm,b=1.1147(4)nm,c=2.1796(8)nm, V=1.5045nm^3, Z=4, 空间群P2~12~12~1。分子中酰胺羰基C=O与C=S基团处于C(4)NC(3)键两侧呈反式。用MNDO分子轨道方法研究了该化合物的电子结构, 电荷和键序分布,前沿轨道性质,讨论了电子光谱性质。     

利凡诺的吸附溶出伏安法研究

在NH~3-NH~4Cl底液中,利凡诺(RIL)在汞电极上有一线性扫描还原峰,E~P~C=-1.42V(vs.饱和Ag/AgCl电极).该峰具有明显的吸附性.当RIL浓度较小,扫描速度较快,搅拌富集时间较长时,电极反应完全为吸附态的RIL的还原所控制.吸附粒子为RIL中的二氨基乙氧基丫啶中性分子.测得RIL在汞电极上的饱和吸附量为4.0×10^- ^1^0mol·cm^-^2,每个RIL分子所占电极面积为0.42nm^2,电子转移数n为2, 不可逆吸附的转移系数α为0.71.探讨了RIL在汞电极上还原的机理. 并建立了吸附溶出伏安法测定RIL的最佳条件,最低检测限为1.0×10^-^9mol·dm^-^3     

稀土-铋复合氧化物体系的研究

本文讨论了稀土-铋复合氧化物的制备及其某些性质的变化规律。稀土与三价金属的复合氧化物的制备与性质已做了大量工作,然而关于稀土-铋复合氧化物的热稳定性、磁性和反射光谱及其变化规律文献报道不多。在1200℃空气中制备的稀土-铋复合氧化物的晶体结构可分为三种类型,其中三价轻稀土(RE=La,Nd,Sm,Eu和Gd)-铋复合氧化物为菱形结构的固溶体,属于三方晶系Pr~6.O~11.(Bi~2O~3)~1.88和(Tb~4O~7)~1.5.(Bi~2O~3)~1.68为萤石型结构的固溶体,属立方晶系,其余的3RE~2O~3.nBi~2O~3(RE=Ce,Dy,Ho,Er,Tm,Yb,Lu和Y,n分别为0.80,1.68,.60,1.30,0.94,0.82,0.12和1.34)复合氧化物为萤石型的固溶体和C-型RE~2O~3的混相.这些固溶体的晶胞参数随着原子序数的增加而减少,这种变化规律是由镧系收缩引起。随着稀土原子序的增加,稀土-铋复合氧化物的热稳定性降低,并在钆处出现转折,它们磁化率呈现具有两个极大值的周期变化.由于Bi-O键的存在,在它们的反射光谱中有一个宽的紫外吸收带,因此它们可能应用为着色透镜玻璃和紫外吸收材料。     

Study on Electrical Conductivity and Mechanical Performance of Polymeric Composite Flow Field Plates for Fuel Cell Applications

Fuel cell technology has received a great deal of attention as a candidate for an alternative power source due to its environmental benefits compared to conventional sources. Flow-field plates are one of the most important components of the Proton Exchange Membrane (PEM) and Direct Methanol (DM) fuel cells technology, which is expected to possess high electrical and thermal conductivity, low hydrogen permeability, and good mechanical performance. In this study, a systematic investigation was carried out to formulate and fabricate electrically conductive polymer composites to be used in production of flow field plates using a simple low temperature, single step moulding process. It focused on the careful selection of both materials and processing methodology. ElectroPhen^? binders, various concentrations of graphite powder and enhanced dispersion agents were employed to make composite plates with high electrical conductivity and satisfactory mechanical performance. Electrical conductivity measurements were carried out using purpose-built in-plane and through-plane electrical conductivity test kits. Flexural tests were carried out to evaluate the mechanical performance of the composites. It has been found that polymer composite flow field plates can attain the electrical conductivity and mechanical performance requirements for commercial fuel cell applications without requiring a high temperature multi-step production process.     

New Fillers for PBI-Based Composite Electrolytes in Polymer Fuel Cells

Nafion and derived perfluorinated polymers seem to be the most reliable materials in PEMFCs, despite a number of disadvantages, such as low operation conditions (T < 100°C) and high cost. In recent years, new classes of proton conducting membranes have been investigated. PBI membranes showed some advantages: high working temperatures; good chemical resistance; promising durability. Proton carriers are supplied by the presence of phosphoric acid in the membranes. Despite the good conductivity (about 0.1 S/cm at 80°C and RH = 80%) one of the main drawbacks is the leaching of the phosphoric acid under working conditions. In this work two different silica-based fillers, derivatised with phosphoric acid and imidazole-containing units, respectively, were prepared via sol–gel route and characterised from a thermal analyses (TGA-DTA), structural (XRD, IR and solid state NMR) and microstructural (BET) point of view. Impedance spectroscopy scans were carried out on PBI-based membranes filled with derivatised silica up to a content of 30 wt% in order to evaluate the role of the filler in the free phosphoric acid retention capability. The best scores in terms of permanent proton conductivity and acid doping level after leaching were obtained in case of imidazole-functionalised silica, which improves the basicity of the doped polymer system.     

生物分子电催化的研究 Ⅰ.电子传递媒介体甲酚固紫电化学行为的研究

本文以直流极谱、脉冲极谱、Kalousek极谱、交流极谱、交流伏安和循环伏安等多种电化学分析方法对甲酚固紫的极谱伏安性质进行了研究,在pH3～11范围内甲酚固紫在汞电极上发生两电子可逆反应,同时有两个质子参加,其反应物和产物均能吸附在电极表面.研究结果还表明,在一定的条件下甲酚固紫可在电极表面形成双层吸附,吸附层厚度的改变对伏安曲线的形状产生明显的影响,各吸附层显示了不同的电化学性质.     

THE UNIT BALL OF C*-ALGEBRA AND DIFFERENTIABILITY OF SUPPORT FUNCTION

In this paper we show that the unit ball of an infinite dimensional commutative C-algebra lacks strongly exposed points, so they have no predual. Also in the second part, we use the concept of strongly exposed points in the Frechet differentiability of support convex functions.