Electrochemical behavior of some triazine derivatives at glassy carbon electrode in non-aqueous media

Electroreduction of 4-amino-6-methyl-3-thio-1,2,4-triazine-5-one (I), 6-methyl-3-thio-1,2,4-triazine-5-one (II), and 2,4-dimethoxy-6-methyl-1,3,5-triazine (III) in dimethylformamide was investigated. Electrochemical techniques including differential pulse voltammetry (DPV), cyclic voltammetry (CV), chronoamperometry, and coulometry were employed to study the mechanism of the electrode process. From the analysis of the voltammetric and spectroscopic experiments a mechanism was proposed for the electroreduction of thio-triazine and triazine compounds. Compounds I and II having thiol groups exhibited similar redox behavior. Both compounds displayed two cathodic peaks, whereas the third compound (III), with no thiol group, showed only one cathodic peak in the same potential range as the second peak of compounds I and II.The results of this study show that in the former wave, the one electron reduction of thiol led to a dimer (disulfide) species and in the latter, the triazine ring was reduced in a two-electron process. The effects of various physical and electrochemical parameters were studied and the electrochemical behavior of the monomers was reported as a function of these parameters. A completely irreversible behavior was observed from cyclic voltammograms obtained under different conditions. Furthermore, in this study some numerical constants, such as diffusion constant, transfer coefficient, and rate constant of coupled chemical reaction were determined.     

Area Analysis for On-chip Routers with Different Data-link Widths

Compared with the traditional and inter-chip networks, on-chip networks （NoCs） have enormous wire resources which can be traded for improving other performance requirements. This means that much wider data links can be used for NoCs. This paper focuses on the area costs for on-chip routers under four different data-link widths： 8 bits, 16 bits, 128 bits, and 256bits. Firstly, a virtual-channel based on-chip router is introduced. Secondly, the components of the router are implemented by Verilog HDL models and synthesized by Quartus II 4.0 in a FPGA device. Finally, the area costs are analyzed. It can be seen from the results that data-link width has great influence on area costs of buffers and crossbar while has no influence on area costs of arbiter.     

Eliminating the Interference of Ascorbic Acid and Uric Acid to the Amperometric Glucose Biosensor by Cation Exchangers Membrane and Size Exclusion Membrane

The characteristics of a multiuse planar amperometric biosensor modified with Nafion and/or polyion membrane were investigated. A new enzyme immobilization process was proposed, in which the polyvinyl alcohol bearing a styrylpyridinium (SbQ)/glucose oxidase composite was treated with glutaraldehyde vapor prior to the photocrosslinking reaction. The resulting planar enzyme electrode remains active for at least 150 days. Compared with poly‐L ‐lysine/poly (4‐stryenesulfonate) polyion complex membrane the Nafion membrane showed marked effect to reduce the electrochemical response of the modified planar enzyme electrode to the biological interferents, such as ascorbic acid and uric acid. Furthermore, Nafion membrane can effective restricting the oxidized anionic interferent to adhear on its surface, thereby the fouling of the electrode was avoided.     

Differential Pulse Anodic Stripping Voltammetric Determination of Lead with Heparin Modified Electrode

Introduction Overall exposure to lead is of public health concern because of several hazardous effects that may occur to human beings. Lead poisoning may provoke irritability, anorexia, malaise and headache. Intoxication progress may lead to attacks of abdominal pain until coma and death.1 The determination of trace lead in variety of en-vironmental samples is of great importance since lead is recognized as a cumulative poison to animals and hu-mans. There is a constant demand for improved an…     

高性能PTCR电极浆料生产工艺的改进

通过增加分散剂松香的用量，提高了欧姆银浆的关键中间体材料银泥的质量稳定性。将压滤法应用于银泥洗涤工艺，既节省了设备投资，又避免了设备腐蚀。在欧姆银浆中掺入１０％的活性铝粉，降低了浆料成本，而且增强了浆料的工艺适应性。表层银浆的配制采用辊轧工艺替代球磨工艺，并对有机载体进行了调整，提高了生产效率，改善了膜层光洁度。     

金属蒸气合成法制备燃料电池电极催化剂Ⅰ.Ag_n/C电极的制备及性质

金属蒸气合成法(MVS)已用于新材料的制备。我们曾报道用此法制备负载型金属催化剂。本文报道用MVS法制备的Ag_n/C燃料电池电极的结构与催化性能。     

Biodegradation of soluble redox polymers. Part 2: (0.017ferrocene)amylose at a rotating disk electrode

The behavior of (ferrocene)amylose (FA), in the presence of amylolytic depolymerases (α-amylase from Aspergillus oryzae and human saliva), has been investigated by cyclic voltammetry at a rotating disk electrode (CVA/RDE). Growth of the limiting current with time in the presence of the enzymes is proportional to the amount of enzyme introduced. The quantitative data treatment to assay the endoamylolytic activity of enzymes at CVA/RDE involves plotting (i_dt/i_d0)^4.5 against time; the slope of the linear plot being equal to (rate) M_n0C⁻¹, where i_dt and i_d0 are the limiting currents at time t and 0, respectively, (rate) is the enzymatic activity, M_n0 is the number averaged molecular weight of FA at t = 0, and c is its concentration. The comparison of CVA/RDE with the 3,5-dinitrosalicylic acid and the Somogyi–Nelson reducing saccharides procedures shows advantages of the former, especially in assaying small quantities of enzymes. Also the CVA/RDE approach is simpler and takes place under much milder conditions. The main disadvantage of CVA/RDE is the inhibiting effect of Triton X-100 in the reaction between FA and the amylases which is not observed in the case of native, ferrocene-free amylose. In general, CVA/RDE appears to be an attractive analytical method for monitoring diverse enzymatic depolymerization reactions.     

Electrical Control of Urease Activity Immobilized to the Conducting Polymer on the Carbon Felt Electrode

The activity of urease varies by its redox reaction. Active urease has an SH group that is essential to exhibit its activity, however, oxidation agents such as quinone compounds can oxidize the SH group in urease and a S–S bond is produced, resulting in the loss of enzyme activity. The reduction potential of cystine was almost the same as that of the recovery of urease activity. In this work, it has been found that the SH group of urease can be oxidized by not only chemical reaction but also by the direct electrode oxidation of urease and the produced S–S bond can be reduced to SH group by chemical and electrode reactions, and the original enzyme activity is recovered. This research shows that the regulation of urease activity is easily possible by changing the electrode potential of the porous carbon felt immobilized urease. The variation of urease activity was monitored by ammonia or carbon dioxide electrode equipped with the urease immobilized carbon felt, and the ammonia or carbon oxide generated from urea can transfer through the carbon felt to reach the each gas permeable membrane. The combination of gas electrode with porous conducting material such as carbon can supply the novel device for the electrochemical investigation of enzyme activity.     

Nafion雷尼替丁离子选择电极的研制及应用

本文报道了 Nafion 雷尼替丁离子选择电极的研制及其应用。该电极与一般高聚物膜传感电极相比,无需合成活性物,简化了操作过程,避免了活性物流失,延长了电极寿命,且具有较好的响应性能。用于雷尼替丁测定,线性范围为10~(-1)～5×10~(-5)mol/L。同一批号药剂测定6次,相对标准偏差为0.62%,平均回收率为99.9%。     

Direct Bioelectrocatalysis by NADP‐Reducing Hydrogenase from Pyrococcus furiosus

The direct bioelectrocatalysis by an NAD(P)‐reducing hydrogenase is reported for the first time. In contrast to previous attempts to involve similar enzymes in bioelectrocatalysis [1–4], which were in fact unsuccessful, in our report an effective electrocatalysis by Pyrococcus furiosus hydrogenase is convincingly shown by (i) achievement of the hydrogen equilibrium potential and (ii) a high current of hydrogen oxidation (0.3 mA cm^?2 at 100 mV overpotential and at 75 °C). The latter is just a few times lower compared to enzyme electrodes based on NAD(P)‐independent hydrogenases.