A strategy for the electro-organic synthesis of new hydrocaffeic acid derivatives

Electrochemical treatment processes can significantly contribute to the protection of the environment through the minimization of waste and toxic materials in effluents. From a pharmaceutical point of view and due to the existing resemblance between the electrochemical and biological reactions, it can be assumed that the oxidation mechanisms on the electrode and in the body share similar principles. In this paper, the application of electrochemical studies in the design of an environmentally friendly method was delineated for the new hydrocaffeic acid (HCA, 3,4-dihydroxy hydrocinnamic acid) derivatives synthesis at carbon electrodes in an undivided cell. In this cell, the EC mechanism reaction was involved, comprising two steps alternatively; (1) electrochemical oxidation and (2) chemical reaction. In particular, the electro-organic reactions of HCA, an important biological molecule, were studied in a water–acetonitrile (90:10 v/v) mixture in the presence of benzenesulfinic acid (3) and p-toluenesulfinic acid (4). The research included the use of a variety of experimental techniques, such as cyclic voltammetry, controlled-potential electrolysis and product spectroscopic identification.     

The mechanism and kinetics of the electrochemical cleavage of azo bond of 2-hydroxy-5-sulfophenyl-azo-benzoic acids

The electrochemical reduction of 2-hydroxy-5-[(4-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(3-sulfophenyl)azo]benzoic acid, 2-hydroxy-5-[(2-sulfophenyl)azo]benzoic acid and 2-hydroxy-5-azo-benzoic acid has been carried out in aqueous solutions at glassy carbon electrode using cyclic voltammetry and chronoamperometry. The position of sulfo substituent relative to azo bridge as well as pH of the solution have significant impact on the electrochemical behavior of these compounds. It has been proposed that these compounds are reduced predominantly as hydrazone tautomers resulting in corresponding hydrazo compounds. The overall electrochemical reduction follows DISP2 mechanism, ultimately leading to the 5-amino salicylic acid and sulfanilic acid. The rate determining step is the homogenous redox reaction between intermediate hydrazo compound and 5-amino salicylic acid quinoneimine. The mechanism is proposed in which activated complex of 5-amino salicylic acid quinoneimine and intermediate hydrazo compound is formed with the simultaneous loss of one proton.     

电化学除盐对混凝土微观结构的影响

设计了一套钢筋混凝土的电化学除盐循环装置,研究了用0.001 mol/L Li2B4O7 氢氧化钙饱和溶液、氢氧化钙溶液以及蒸馏水作电解液的除盐效率,并用SEM和EDS等方法进行微观结构分析,结果表明:用0.001 mol/L Li2B4O7 氢氧化钙饱和溶液作电解液最有利于混凝土中Cl-的排除,并且经电化学除盐处理后混凝土水化产物中C-S-H凝胶分解,Ca(OH)2增多,并在孔壁形成沉淀,堵塞毛细孔,使表层混凝土孔隙率降低,而钢筋与混凝土界面Ca/Si增大。     

The electroreduction of alkyl iodides and polyiodides: The kinetic model of EC(C)E and ECE-EC(C)E mechanisms with included transfer coefficient variability

The cyclic voltammetry electroreduction of seven alkyl iodides was investigated in 0.3 M TBAP/DMF on glassy carbon electrode. The influence of carbon chain length and the number of iodine atoms in the molecule was examined. The two-electron reductive cleavage with iodine elimination was numerically resolved into one-electron consecutive steps. The mechanism of the process was discussed applying the mathematical EC(C)E and ECE-EC(C)E kinetic models with included transfer coefficient variability for one stage electroreduction of RI and two stage electroreduction of RI₂, respectively. For electroreduction of diiodomethane the discrimination of elementary alpha parameter between two reduction stages was determined.     

对某城市越野车车外加速噪声的降噪试验研究

针对某城市越野车车外加速噪声超出欧标ECE R51-02的规定限值的状况,通过试验研究,综合运用噪声源识别方法,识别出进气系统噪声和动力总成系统噪声是造成车外加速噪声偏高的主要原因。根据噪声源的特性采取降噪措施,使被测车辆车外加速噪声下降了5.33dB(A),满足了ECE R51-02对该类车车外加速噪声限值的要求。     

欧美摩托车前照灯配光性能要求异同分析

摩托车前照灯配光性能是关系车辆行车安全的重要性能指标,本文介绍了欧洲法规及美国标准配光性能要求及测试方法,并详细分析两者之间的异同。     

聚碳酸酯快中子反冲径迹的电化学蚀刻研究

我们研制了一台供扩大固体内核径迹用的电化学蚀刻装置。它可以输出电压和频率皆可调的正弦波(电压0—1100伏,频率50—5000赫)。采用聚碳酸酯膜记录快中子引起的反冲核径迹。对径迹蚀刻的几个主要参量如电场强度、频率、蚀刻时间和蚀刻液的浓度等进行了研究,还对聚碳酸酯的中子灵敏度、能量响应、方向响应、径迹稳定性及本底进行了测量。对于180微米厚的聚碳酸酯膜,实验确定的最佳蚀刻条件为:电场强度13.5千伏/厘米,电场交变频率2.5千赫,6N KOH,15℃,5小时。在此条件下,电化学蚀刻的快中子反冲径迹平均直径约为50微米;对~(252)Cf、AmBe、4.0和14.8兆电子伏中子的灵敏度分别是2.7×10~(-7)、1.8×10~(-6)、2.2×10~(-6)和3.7×10~(-6)(径迹/中子);经预蚀刻的本底径迹密度约为8(径迹/厘米~2)。实验表明,固体核径迹探测器电化学蚀刻方法的显著优点是,它能把反冲核径迹放大成清晰可见的放电蚀坑,从而使径迹测量变得相当简单、快速和可靠。     

Estimation of magnetic island width by the fluctuations of electron cyclotron emission radiometer on J-TEXT

The width of a magnetic island is an important parameter for the quantitative analysis of magnetohydrodynamic-related physics. An electron cyclotron emission radiometer(ECE) is a powerful tool that can be used to obtain this width, which can usually be determined from the flat temperature distribution at the O-point phase or the maxima temperature perturbation. An improved method to estimate the width of a magnetic island is proposed in this paper, and it is independent of calibration. With this method and the existing 24-channel ECE system, the width of a rotation magnetic island can be estimated. Additionally, by filtering the fluctuation ECE signal, the evolution of the magnetic island can be obtained. The results of this method are consistent with those of the integrated magnetic probe signals, which represent the relative change of the magnetic island.     

电化学除盐对钢筋——混凝土界面粘结力的影响

应用钢筋混凝土圆柱体试件,研究了电化学除盐对钢筋—混凝土界面粘结力的影响。研究结果表明:除盐电流是导致钢筋—混凝土界面粘结力下降的主要原因,但在采用小电流(1 A/m2~4 A/m2)的情况下,粘结力的损失并不明显。     

欧盟电动汽车技术法规研究

从电动汽车的电气安全、电磁兼容、刹车要求、乘员保护等方面,围绕EC指令和ECE法规的修订工作,全面阐述了欧盟关于电动汽车的技术要求,总结了相关技术法规的修订和起草现状,给出了欧盟电动汽车相关技术立法的阶段性发展趋势。