优化微软网络浏览服务性能

本文介绍了微软网络下的浏览服务。讨论了通用网络环境下,常遇到的浏览问题及解决方法。     

A novel TiN coated CNTs nanocomposite CNTs@TiN supported Pt electrocatalyst with enhanced catalytic activity and durability for methanol oxidation reaction

The application of direct methanol fuel cells (DMFCs) is hampered by not only low activity but also poor stability and poor CO tolerance by the Pt catalyst. Herein, a novel titanium nitride coated multi-walled carbon nanotubes (CNTs@TiN) hybrid support was successfully synthesized by a facile solvothermal process followed by a nitriding process, and this hybrid support was used as Pt support for the oxidation of methanol. The structure, morphology and composition of the synthesized CNTs@TiN exhibits a uniform particle perfect coating with high purity and interpenetrating network structure. Notably, Pt/CNTs@TiN also showed excellent stability, experiencing only a slight performance loss after 5000 potential cycles. The onset potential (0.34 V) of CO oxidation on Pt/CNTs@TiN is obviously more negative than that on the Pt/TiN (0.38 V) and Pt/CNTs (0.48 V) in the first forward scan. In the Pt 4f XPS spectra, plentiful Pt atoms existed as Pt(II) in the Pt/CNTs and Pt/TiN catalysts, while a relatively smaller amount of Pt(II) was observed in the Pt/CNTs@TiN catalyst. The synthetic Pt/CNTs@TiN catalyst was studied with respect to its electrocatalytic activity and durability and CO tolerance toward methanol oxidation might be mainly attributed to the strongly coupled Pt–TiN and the fast electron-transport network structure. This work may provide more insight into developing novel catalyst supports of various transition metal nitrides coated CNTs for DMFCs with high activity and good durability and excellent CO tolerance.     

钒掺杂孔洞空壳二氧化钛的制备及光催化性能

以硫酸氧钛为钛源,偏钒酸钠为掺杂离子前驱体,尿素为形貌控制剂,通过水热法直接一步合成钒掺杂孔洞空壳TiO_2(V/TiO_2)的光催化剂。采用X射线衍射(XRD)、扫描电镜(SEM)、X射线能量色散谱(EDS)、紫外-可见吸收光谱(UV-vis)等技术对样品进行表征。研究表明,钒元素能够可控地掺杂到TiO_2孔洞空壳结构中,并且不影响其形貌。紫外可见光谱表明钒元素的掺入导致吸收峰红移。对V/TiO_2降解甲基橙的光催化进行了研究,实验表明V/TiO_2孔洞空壳结构拥有更好的光催化性能。     

低浓度钴溶液的除铁镁和富集钴的研究

介绍了用黄钠铁矾法和氟盐沉析法从低浓度钴溶液中除铁，镁的净化处理，以及用离子交换 法富集钴的工艺流程和基本操作条件，结果溶液中钴的含量由原来的１．８ｇ／Ｌ提高到到８．０ｇ／Ｌ，为制备钴皂系列产品提供了原料。     

阻抗蛋白质吸附材料研究进展

蛋白质是两亲大分子,对材料表面具有亲和性,易被吸附并污染材料。阻抗蛋白质吸附的无污染表面在生物医药、船体涂层、生物芯片等领域具有广泛重要的应用。本文对聚合物材料表面阻抗蛋白质吸附的机理进行了归纳,介绍了阻抗蛋白质吸附的材料制备及表面修饰的相关研究进展。     

Effects of the Correlated Hopping on the d-Wave Superconductivity

A superconducting ground state has been obtained within a two-dimensional (2D) generalized Hubbard model, in which a next-nearest-neighbor correlated-hopping interaction is included. In spite of its smaller strength in comparison with other terms of the model, we found its key participation in the d-channel hole pairing. The hole singlet ground-state phase diagram shows a large d-symmetry pairing region that is enhanced by the on-site repulsive Coulomb interaction. For finite density of holes (n _h), the mean-field BCS theory is applied to the model. The results show a maximum d-wave critical temperature (T _c) around n _h = 0.35, and this T _c is favored by the presence of an antiferromagnetic background.     

纳米二氧化铈的电化学制备与表征

在铈盐溶液中用电解的方法制备了CeO2 纳米粉体。X 射线衍射表明 ,所得产物为立方晶系CeO2 ;SEM分析表明 ,CeO2 纳米粒子呈球形 ,晶粒度约 10nm ;TEM分析表明 ,粒径分布均匀 ,粒子不发生团聚 ;电子衍射表明 ,CeO2 纳米粒子为多晶结构。实验探讨了溶液浓度、电流密度等因素对CeO2 质量和产量的影响