Enhanced electrocatalytic activity of nickel particles electrodeposited onto poly (m-toluidine) film prepared in presence of CTAB surfactant on carbon paste electrode for formaldehyde oxidation in alkaline medium

In this work, carbon paste electrode is coated with poly (m-toluidine) film by potentiodynamic electropolymerization of m-toluidine monomer in the presence of cetyltrimethyl ammonium bromide (CTAB-PMT/MCPE). Then electrolysis at fixed potential (−1.0 V versus reference electrode for 15 min) is employed for electrodepositing of Ni from 1.5 M NiSO₄ acidic solution at the surface of polymer-modified electrode for preparation of Ni/CTAB-PMT/MCPE. The general electrochemical behaviors of these modified electrodes are characterized by cyclic voltammetry in alkaline media. In alkaline medium (i.e. NaOH 0.1 M) a good redox behavior of Ni(III)/Ni(II) couple at the surface of these electrodes can be observed. The nickel particles electrodeposited at the surface of Ni/CTAB-PMT/MCPE exhibits a significant electrocatalytic activity towards oxidation of formaldehyde. Moreover, the effects of various parameters such as concentration of CTAB, concentration of formaldehyde, film thickness and monomer concentration on the electrooxidation of formaldehyde as well as long-term stability of the Ni/CTAB-PMT/MCPE have also been investigated.     

Immobilization of 1,2-naphthoquinone-4-sulfonic acid on gold electrode: application for cysteamine detection using Michael addition

Fabrication and electrochemical characterization of adsorbed 1,2-naphthoquinone-4-sulfonic acid sodium (Nq)-modified gold electrode is described in a wide pH range (3.00–9.00) in 0.1 M phosphate buffer solution using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and double-step potential chronoamperometry methods. The resulting Nq thin film-modified gold electrode (Nq/Au) was tested successfully to recognize cysteamine in an aqueous solution. It is found that cysteamine participates in Michael addition reaction with adsorbed Nq on gold electrode to form the corresponding thioquinone derivative. The reoxidation of the adduct at a potential of about 650 mV less positive than cysteamine at the surface of the bare Au electrode leads to an increase in the oxidative current, which is proportional to the concentration of cysteamine. The calibration plot for cysteamine was found to be linear in the ranges of 6.0 × 10⁻⁵–4.5 × 10⁻³ M and 8.0 × 10⁻⁶–5.5 × 10⁻⁴ by CV and DPV, respectively.     

去除局部破损混凝土后钢筋混凝土梁受弯性能理论分析

在钢筋混凝土梁修复加固的过程中 ,常常可能去除梁上部分破损的混凝土 ,使钢筋外露 ,在荷载作用下 ,造成梁的力学性能发生变化。基于对钢筋混凝土梁变形分析 ,利用数值分析方法 ,详细讨论了在忽略梁剪切变形的条件下 ,去除局部破损混凝土、受拉钢筋暴露的钢筋混凝土梁的理论分析方法。给出了计算去除局部破损混凝土、部分受拉钢筋暴露的钢筋混凝土简支梁挠度和承载力的具体分析步骤和计算公式 ,计算结果和试验结果吻合良好。