Amperometric enzyme sensor for glucose based on graphite paste-modified electrodes

Amperometric enzyme electrode for glucose is described based on the incorporation of glucose oxidase (GOD) into graphite paste modified with tetracyanoquinodimethane (TCNQ). The incorporated enzyme exhibits high activity and long-term stability over the earlier TCNQ-based glucose sensor (1). The sensor provides a linear response to glucose over a wide concentration range. The response time of the sensor is 15-50 sec, and the detection limit is 0.5 mM. Stable response to the substrate was obtained during a period of 35 d. Application of the sensor in the plasma analysis is reported.     

On the nonequilibrium statistical mechanics of a binary mixture. I. The distribution functions

In this paper, we obtain the generalization of the BBGKY hierarchy for a binary mixture of chemically neutral particles. Using modified boundary conditions different from the ones proposed by Bogoliubov, we solve the hierarchy, and obtain explicitly the set of two-particle distribution functions for the several species of the mixture, up to first order in the density.     

Effect of L‐Aspartate Concentration on the Response of the Amperometric L‐Glutamate Sensor for the Measurement of L‐Glutamate and Aspartate Aminotransferase Activity in Serum

Abstract

L‐glutamate oxidase was immobilized in a photo‐cross‐linkable polymer membrane on a palladium strip electrode for the amperometric measurement of aspartate aminotransferas eactivity. The sample, serum for example, was injected into a buffered L‐aspartate and α‐ketoglutarate solution. L‐aspartate is the essential substrate and can transfer to L‐glutamate via the aspartate aminotransferase catalyzing reaction. Aspartate aminotransferase activity can be measured by determining the increasing rate of L‐glutamate. Under the optimal condition, the current increasing rate was proportional to the aspartate aminotransferase activity of the sample in the range of 8–200 U/L. The data are in good correlation (R²= 0.998) with data from a commercial aspartate aminotransferase assay kit. Good reproducibility (relative standard deviation=3.03%, n=8) was obtained from a sample with 50 U/L aspartate aminotransferase activity. The sensor is expectable to be applied in a clinical point‐of‐care diagnosis.     

Effect of the molecular weight and architecture on the size and glass transition of arborescent polyisobutylenes

This article discusses the characterization of arborescent (hyperbranched) polyisobutylenes (arb‐PIBs) by size exclusion chromatography and differential scanning calorimetry, in comparison with linear PIB standards. The radius of gyration (〈r〉^1/2 = R_z), measured from the angle dependence of light scattering of high‐molecular‐weight arb‐PIBs, was significantly larger than the hydrodynamic radius (R_h) from size exclusion chromatography/viscometry, and the R_h values were significantly smaller than R_h of linear PIBs. The glass‐transition temperature of arb‐PIBs having a branch molecular weight higher than the critical entanglement molecular weight was dependent on both the total number‐average molecular weight and BR up to BR ～ 15. A modified Fox–Flory equation is proposed to describe the effect of architecture on the thermal transition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1770–1776, 2006     

Ugi amine-derived P,N- and P,P-ligands with N-alkyltriethoxysilyl tethers: synthesis and evaluation of mesoporous silica-supported Pd complexes in asymmetric allylic substitution reactions

A facile approach to the synthesis of several types of chiral P,N- and P,P-ligands bearing triethoxysilyl groups starting from N,N-diemthyl-1-ferrocenylethylamine (Ugi amine) has been developed. Allyl palladium complexes of these ligands have been prepared, characterized, and grafted on mesoporous silica. The resulting silica-supported complexes have been shown to catalyze asymmetric allylic alkylation and aminations reactions with moderate enantioselectivities.     

镍纳米线电极对乙醇的电催化氧化动力学参数的测定

循环伏安实验表明,以多孔氧化铝膜为模板制备出的镍纳米线电极对乙醇的电化学催化氧化具有很高的催化活性.用强制对流流体动力学的方法求算出乙醇在镍纳米线电极上的电子传递过程的速率常数高于许多文献报导值,而电子传递过程的随后步骤的速率常数相近.     

A NEW MODEL FOR CONCENTRATION DEPENDENCE OF POLYMER CHAIN DIMENSIONS

A new model for concentration dependence of polymer chain dimensions over the wholeconcentration range was proposed. The hydrodynamic volume of a solvated macromoleculewas found to be a universal function of the degree of coil overlapping (c/c~*). The radiusof gyration (R_g) and the expansion coefficient (α) of polymer in solution or in bulk. pre-dicted by this model are much better in agreement with the experimental data of small angleX-ray scattering and neutron scattering from literature, than with the values predicted byother models and theories.     

流体动力色谱法和障碍色谱法及其应用

介绍了流体动力色谱(HDC)和障碍色谱(SC)及其在生物、化工分离中的研究进展,着重于它们的分离原理、理论发展及二者之间的联系与转化,引用52篇文献.