Electrochemical Determination of Superoxide Based on Cytochrome c Immobilized on DDAB‐Modified Powder Microelectrode

Abstract

Cytochrome c was immobilized at didodecyldimethylammonium bromide (DDAB)‐modified powder microelectrode and presented quasi‐reversible electrochemistry. The apparent surface coverage of cytochrome c is greatly enhanced by using powder microelectrode technique, which is 1.21×10^?8 mol/cm², more than one to three orders of magnitude larger than that obtained with thiol and DNA‐modified Au electrode. The cytochrome c modified powder microelectrode was applied for the amperometric determination of superoxide generated by the reaction of hypoxanthine with xanthine oxidase (XOD) in the presence of dioxygen.

The detection sensitivity of the modified powder microelectrode is 0.74 µA/cm² µM, which is larger than that reported in previous publications. The detection limit of the modified powder microelectrode (PME) is 0.5 µM, and the linear detection range is 0.86～5.93 µM (values of the concentration are all in terms of hypoxanthine concentration in the solution).     

Nondestructive Quantitative Analysis of Analgini Powder Pharmaceutical by Near-Infrared Spectroscopy and Artifical Neural Network Technique

ABSTRACT

This paper demonstrates the usefulness of near-infrared (NIR) spectra and artificial neural network (ANN) in nondestructive quantitative analysis of pharmaceuticals. Real data sets from near-infrared reflectance spectra of analgini powder pharmaceutical were used to build up an artificial neural network to predict unknown samples. The parameters affecting the network were discussed. A new network evaluation criterion, the degree of approximation, was employed. The overfitting was discussed. Owing to the good nonlinear multivariate calibration nature of ANN, the predicted result was reliable and precise. The relative error of unknown samples was less than 2.5%     

Synthesis,characterization and XRPD studies of the bioactive complex of 2-hydroxy-3,5-dimethyl acetophenoneoxime (HDMAOX) with oxovanadium(IV)

The complex of 2-hydroxy-3,5-dimethyl acetophenoneoxime (HDMAOX, HL) with VO(IV) has been synthesized and characterized by different physical techniques. Infrared spectra indicate deprotonation and coordination of the phenolic OH, and nitrogen of the oximino group. Electronic spectra and magnetic susceptibility measurements support square-pyramidal geometry around the metal ion. The elemental analyses and mass spectral data indicate ML₂ composition. Thermodynamic activation parameters were computed from the thermal data using the Coats and Redfern method. The crystal data for C₂₀H₂₄N₂O₅V are: tetragonal, space group P4/m, a?=?11.76975?Å, b?=?11.76975?Å, c?=?18.89209?Å, V?=?2617.06?A³, Z?=?4. The free ligand (HDMAOX) and its oxovanadium complex have been tested in vitro against Alternaria alternate, Aspergillus flavues, Aspergillus nidulans and Aspergillus niger fungi and Streptococcus, Staph, Staphylococuss and Escherchia coli bacteria in order to assess their antimicrobial potential. The results indicate that the ligand and its metal complex have antimicrobial properties.     

Pressure‐Induced Enhancement of Magnetic‐Ordering Temperature in an Organic Radical to 70 K: A Magnetostructural Correlation

The structure of the canted antiferromagnet β‐p‐NCC₆F₄CNSSN ( 1 ) was determined from synchrotron powder‐diffraction studies in the pressure range 0–21.6 kbar. Radical 1 crystallizes in the orthorhombic space group Fdd2, but undergoes an asymmetric contraction of the unit‐cell size with increasing pressure. At the molecular level, this contraction of the unit cell is simultaneously accommodated by: 1) an increase in twist angle between aryl and heterocyclic rings; and 2) a shortening of the intermolecular S ??? N contacts, which propagate the magnetic‐exchange pathway. DFT calculations based on the structures in this pressure range revealed an increase in the magnetic‐exchange interaction (J) with increasing pressure, and an excellent correlation was observed between J and the magnetic‐ordering temperature, which increased from 36 K at ambient pressure up to 70 K at 16 kbar.     

溶剂热法合成In2S3/CuSe核壳结构粉体

本文以氯化铜、氯化铟、硫脲、亚硒酸以及硒粉为原料,乙二醇及乙二胺为溶剂,采用常压溶剂热法制备了硫化铟为核硒化铜为壳(In2S3/CuSe)的核壳结构复合粉体。主要探讨了反应温度、不同反应原料以及不同表面活性剂对产物物相以及形貌的影响。通过采用X射线衍射(XRD)、扫描电镜(SEM)对产物的物相、形貌以及组成进行了表征。实验结果表明:常压溶剂热条件下可以制备得In2S3/CuSe复合粉体,其最佳反应工艺参数是:于160℃下合成In2S3粉体为核,于100℃下合成包裹在In2S3表面的CuSe粉体从而获得In2S3/CuSe核壳结构复合粉。在该工艺参数下合成产物的形貌主要由圆球状颗粒组成,粉体的粒径分布在1~2μm。此外,本文也通过添加不同种类表面活性剂对产物的形貌进行了控制。     

Mn2O3微纳米粉体的配合物热解制备与电化学性质（英文）

利用液相扩散法制备了异烟酸锰超分子配合物,通过将其在空气中高温煅烧制备了Mn2O3微纳米粉体。利用FTIR、TG-DTA、XRD、TEM和FESEM对产物进行了表征。电化学测试表明,Mn2O3微纳米粉体在0.5 mol.L-1Na2SO4电解液中表现出良好的电化学电容特性,在电流密度为0.5 A.g-1时其单电极比容量可达到88 F.g-1,循环3 000次后容量保持率可达到80%。     

气相色谱-三重四极杆质谱测定中老年奶粉中甲基硒代半胱氨酸

采用气相色谱-三重四极杆质谱联用仪对中老年奶粉中的甲基硒代半胱氨酸进行定性确证和定量分析。样品经三氯乙酸和乙腈提取后,用氯甲酸乙酯在乙醇吡啶介质中衍生,衍生物经HP-5MS色谱柱分离并使用多反应监测模式进行定性和定量分析。甲基硒代半胱氨酸的线性范围为0.005～1.0 mg/L,方法检出限和定量下限分别为0.01、0.05 mg/kg。奶粉样品在0.05、0.2、0.4 mg/kg 3个加标水平下的平均回收率为79%～86%,相对标准偏差为2.8%～4.0%。该方法能满足中老年奶粉中甲基硒代半胱氨酸的质量控制需要。     

锆酸钙基高温质子导体材料

锆酸钙基材料具有优良的热、机械、发光、介电性能,是先进的耐火、发光、铁电材料。自1991年Iwahara等发现锆酸钙基材料在高温下具有质子导电性以来,锆酸钙基电解质陶瓷的研究取得重大进展。本文结合本实验室的研究分别从材料制备、陶瓷烧结、质子传输机理及影响质子传输的因素等4个方面就20年来锆酸钙基质子导体材料的研究进展进行了综述,并对其未来发展进行了展望。     

PVDF粉体60^Co-γ，射线共辐射接枝NVP

采用60^Co-γ射线共辐射接枝聚合法,将N-乙烯基-2-吡咯烷酮（NVP）接枝到聚偏氟乙烯（PVDF）粉体上,以改善其亲水性。考察了反应过程中各种因素对接枝率（FI）G）的影响,并对接枝产物进行了表征。结果表明：通过60^Co-γ射线共辐射可有效实现NVP在PVDF粉体上的接枝。当辐射吸收剂量为40kGy,阻聚剂六水合硫酸亚铁铵浓度为3mmol／L,NVP体积分数为15％,甲醇为溶剂时,rDG达到18．6％,且接枝后PVDF粉体的亲水性明显提高。     

Carbon Paste Electrodes in Facts,Numbers, and Notes: A Review on the Occasion of the 50‐Years Jubilee of Carbon Paste in Electrochemistry and Electroanalysis

This article reviews the electrochemistry and electroanalytical applications of carbon paste‐based electrodes, sensors, and detectors on the occasion of the half‐of‐century anniversary since the discovery of carbon paste. The review (with 333 references) has been prepared in the form of a retrospective compilation presenting the field by means of various facts, notes, data, surveys, and summaries, including numerous rarities or curiosities that illustrate the individual achievements and milestones. Carbon paste‐based electrodes are discussed in their entirety by covering all important areas of the field, starting from basic characterization of carbon paste as the electrode material, via its typical physicochemical and electrochemical properties or specific features, up to a representative documentation of their applicability in electrochemical and electroanalytical measurements.