Some notes on the impedance method for mechanistic studies of electrode reactions

Conditions for obtaining high precision impedance data on electrochemical metal/electrolyte interfaces are discussed and some results pertaining to several electrode reactions presented. The importance of the dropping mercury electrode is stressed. Published in Elektrokhimiya in Russian, 2009, vol. 45, No. 1, pp. 28–31. Dedicated to Professor B.V. Ershler on the occasion of the Centenary of his birth. The text was submitted by author in English.     

Study on thermal decomposition kinetics of N,N′-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxan-2-yl)ethylenediamine in air

The thermal decomposition kinetics of the N,N′-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxan-2-yl) ethylenediamine (DPTDEDA) in air were studied by TGDTG techniques. The kinetic parameters of the decomposition process for the title compound in the two main thermal decomposition steps were calculated through the Friedman and Flynn-Wall-Ozawsa (FWO) methods and the thermal decomposition mechanism of DPTDEDA was also studied with the Coats-Redfern and Achar methods. The results show that the activation energies for the two main thermal decomposition steps are 128.03 and 92.59 kJ·mol⁻¹ with the Friedman method, and 138.75 and 106.78 kJ·mol⁻¹ with the FWO method, respectively. Although there are two main thermal decomposition steps for DPTDEDA in air, the thermal decomposition mechanism of DPTDEDA in the two steps are the same, i.e. f(α) = 3/2(1 − α)^4/3[(1 − α)^−1/3 − 1]⁻¹. __________ Translated from Acta Chimica Sinica, 2008, 66(9) (in Chinese)     

氨基硅球表面印迹牛血清白蛋白分离条件的初步探讨

采用固定模板蛋白表面印迹的方法,在氨丙基衍生的硅球表面制备溶胶-凝胶印迹聚合物识别牛血清白蛋白.以该体系为例对制备蛋白质印迹聚合物的各个基本参数与分离选择性的关系进行研究.结果表明,用正辛基三甲氧基硅烷、氨丙基三乙氧基硅烷、四乙氧基硅烷在摩尔比为42.5:42.5:15,酸度为pH 7.0时进行聚合,并采用01 mol/L NaOH与10%(V/V) HAc-10%(m/V) SDS联用的方法洗脱固定的模板蛋白,由此制备的印迹聚合物的分离选择性能较好;并初步讨论了识别蛋白质的机理.     

Preparation of dendritic‐like CdS by hydrothermal method and its photocatalytic performance

In this article, dendritic‐like CdS has been prepared by a hydrothermal method using thiourea as the sulfur source, and the effects of experimental conditions on the morphologies of CdS have been investigated. The performances of CdS have been analyzed by X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and the fluorescence and photodegradation properties of CdS have also been investigated. The XRD result indicates that the dendritic‐like CdS are of hexagonal phase and they are highly crystallized. Also, the FESEM results show that the ratio of raw material affects the yield of CdS, the reaction time affects the morphology of CdS. The best morphology of CdS is dendritic structures and the length is about 6 μm. The fluorescence spectrum shows three peaks at 470 nm, 513 nm and 547 nm, which indicates that the dendritic‐like CdS mainly emits green and blue fluorescence. Moreover, the dendritic‐like CdS exhibits good photocatalytic activity and its photodegradation rate to methylene blue can reach 92%. The growth mechanism for the formation of CdS with dendritic structure is also described.     

Single‐crystalline gold microplates grown on substrates by solution‐phase synthesis

Chemically synthesized single‐crystalline gold microplates have been attracting increasing interest because of their potential as high‐quality gold films for nanotechnology. We present the growth of tens of nanometers thick and tens of micrometers large single‐crystalline gold plates directly on solid substrates by solution‐phase synthesis. Compared to microplates deposited on substrates from dispersion phase, substrate‐grown plates exhibit significantly higher quality by avoiding severe small‐particle contamination and aggregation. Substrate‐grown gold plates also open new perspectives to study the growth mechanism via step‐growth and observation cycles of a large number of individual plates. Growth models are proposed to interpret the evolution of thickness, area and shape of the plates. It is found that the plate surface remains smooth after regrowth, implying the applicability of regrowth for producing giant plates as well as unique single‐crystalline nano‐structures.     

Mass Spectrometric Studies on Metal-hexafluorobenzene Anionic Complexes（M=Ag, Au, Pd, Pt, Pb and Bi）

The anionic products from the reactions between metal(M=Ag, Au, Pd, Pt, Pb and Bi) vapour produced by laser ablation and hexafluorobenzene seeded in carrier gas(Ar) were studied by means of a homemade reflectron time-of-flight mass spectrometry(RTOF-MS). Experimental results show that the dominant products were [MmC6F6]-complexes for the reactions of Ag, Au, Pd and Pt with C6F6, while the dominant products were [MmC6F5]-complexes for the reactions of Pb and Bi with C6F6. The formation mechanisms of the prod...     

基于SD-GM理论的城市交通拥堵收费模型研究

随着中国城市化建设步伐的不断加快,交通拥堵在不断地加剧。同时,因机动车污染物的排放,每年将产生大量的NO_x,从而又会引起严重的大气污染(如“雾霾”污染)。针对这些问题,本文从环境和社会的角度出发,采用系统动力学与灰色系统相结合的方法(SD-GM),构建了城市交通拥堵收费模型,并对模型中主要变量进行动态仿真和决策分析,以此来寻找缓解交通拥堵和减少机动车尾气排放的可行策略。通过现实性测试和敏感性测试,得到拥堵收费的范围不超过100元/天*辆。通过进一步的仿真和结果分析可得到以下结论:(1)在区间[25,40] 内,随着拥堵收费的提高,NO_x存量,机动车出行吸引度和交通拥堵程度都呈下降趋势,而车均道路面积呈上升趋势。(2)但并非拥堵收费越高越好, 超过40 元/天*辆,会产生相反的效果。最后,通过比较分析,得到NO_x存量,机动车出行量,机动车出行吸引度和交通拥堵程度分别下降了约33.76%,39.64%,43.26%,82.25%,而车均道路面积提高了大约65.68%,进而验证了模型的有效性和实用性。     

基于TAM理论的顾客心理契约形成机理研究——B2C情景下的实证研究

基于TAM理论研究了B2C情景下顾客心理契约的形成机理。通过相关文献评述,提出了B2C情景下顾客心理契约形成机理模型及假设,通过实证分析验证模型及假设。结果表明:感知易用和感知风险对感知有用具有显著的影响作用;感知有用以及感知易用通过顾客价值观/态度对顾客心理契约具有显著的影响;同时,感知风险和感知易用对顾客心理契约具有显著的直接影响作用。研究结论对B2C情景下服务商保持和维护客户关系具有积极作用,为网络商家建立积极地调控干预机制,促进顾客心理契约正效应感知提供参考。     

The nature of ionic conduction of phases based on calcium thioytterbiate

The CaYb₂S₄ compound and the phases based on it are fabricated. The ranges of solid solutions of CaS and Yb₂S₃ in calcium thioytterbiate are determined using the methods of x-ray diffraction analysis and conductometry. Average ionic, electronic, cationic, and anionic transport numbers and the coefficients of self-diffusion and diffusion of majority carrier in the Yb₂S₃ solid solution based on CaYb₂S₄ are determined by the modified emf method, the polarization Hebb-Wagner method, and potentiostatic chronoammetry. To discuss the mechanism of ionic transfer, the data on the pycnometric and X-ray densities are compared.     

毛细管电泳氨类手性药物对映体拆分机理研究

手性药物及其对映体在药理上可表现出较大的差异,对它们进行研究将具有重要的理论意义和实用价值[1,2].毛细管区带电泳因其分离效率高、药品和试剂用量少、方法简单而成为目前手性拆分鉴定的重要方法之一[3].