细菌Enterobacter dissolvens的直流电解刺激过程

以葡萄糖为唯一碳源,研究了细菌Enterobacter dissolvens在直流电条件下的生长和代谢过程. 实验结果表明,当使用盐桥屏蔽电极反应时,细胞生长曲线和葡萄糖代谢速率基本不受电流强度的影响,而当采用铂丝电极时,反应体系中发生水解反应,采用10 mA电流通电12 h后,菌液中细胞的脱氢酶比活力和葡萄糖降解率分别为对照的1.98倍和1.48倍,细胞生长亦有所加快,但在其活力下降时出现大量死亡. 扫描电镜照片显示细胞结构受到明显破坏,并发生细胞膜穿孔现象,这表明可能受到了过氧化氢等阳极水解中间产物的刺激作用.     

微生物燃料电池的研究进展

根据有无电子传递中间体的参与,微生物燃料电池可分为两大类：直接和间接微生物燃料电池. 简要介绍了其工作原理及发展历史,归纳了近年来国内外对这两种类型电池的研究现状,特别概括了直接微生物燃料电池的研究进展以及存在的问题和工作方向. 最后展望了微生物燃料电池的应用前景.     

Influence of the acid–base/redox properties of TiOx-sepiolite supported vanadium oxide catalysts in the gas-phase selective oxidation of toluene

Catalytic behaviour in the selective oxidation of toluene of a series of vanadium systems supported on TiO_x-coated sepiolite (6, 12 and 25 wt.% TiO₂) with a vanadia loading around the theoretical monolayer (10 wt.%) has been investigated. The surface acid–base/redox properties of the solids were also evaluated by using 2-propanol conversion and pyridine chemisorption. The reducibility of surface vanadia species was studied by H₂-TPR. Surface properties of vanadia species and, consequently, their catalytic behaviour were influenced by titania loading on sepiolite. Thus, the vanadium systems with the highest titania loading were the most active and selective in toluene oxidation. Furthermore, this behaviour seems to be mainly related to the density of the active sites capable of being reduced and producing propanone in the vanadium systems.     

国产络合铁法液相氧化还原硫磺回收脱硫溶剂研究及工业应用

通过实验室模拟性质和组成相似的炼油厂酸性气,在类似于LO-CAT硫磺回收装置工艺操作条件下,对国产络合铁法液相氧化还原催化剂进行了适应性研究。在陕西延长石油(集团)有限责任公司炼化公司延安炼油厂LO-CAT硫磺回收装置进行了工业试用,结果表明,国产络合铁法液相氧化还原催化剂完全可以替代国外专用脱硫溶剂,净化后尾气硫化氢平均含量3.2×10-6,硫回收率大于99.95%,每吨硫磺加工成本降低10%,各项技术经济指标均优于进口脱硫溶剂。     

Robust proton exchange membrane for vanadium redox flow batteries reinforced by silica-encapsulated nanocellulose

High ion selectivity and mechanical strength are critical properties for proton exchange membranes in vanadium redox flow batteries. In this work, a novel sulfonated poly(ether sulfone) hybrid membrane reinforced by core-shell structured nanocellulose (CNC-SPES) is prepared to obtain a robust and high-performance proton exchange membrane for vanadium redox flow batteries. Membrane morphology, proton conductivity, vanadium permeability and tensile strength are investigated. Single cell tests at a range of 40–140 mA cm⁻² are carried out. The performance of the sulfonated poly(ether sulfone) membrane reinforced by pristine nanocellulose (NC-SPES) and Nafion® 212 membranes are also studied for comparison. The results show that, with the incorporation of silica-encapsulated nanocellulose, the membrane exhibits outstanding mechanical strength of 54.5 MPa and high energy efficiency above 82% at 100 mA cm⁻², which is stable during 200 charge-discharge cycles.     

Reconstructing a Flavodoxin Oxidoreductase with Early Amino Acids

Primitive proteins are proposed to have utilized organic cofactors more frequently than transition metals in redox reactions. Thus, an experimental validation on whether a protein constituted solely by early amino acids and an organic cofactor can perform electron transfer activity is an urgent challenge. In this paper, by substituting “late amino acids (C, F, M, T, W, and Y)” with “early amino acids (A, L, and V)” in a flavodoxin, we constructed a flavodoxin mutant and evaluated its characteristic properties. The major results showed that: (1) The flavodoxin mutant has structural characteristics similar to wild-type protein; (2) Although the semiquinone and hydroquinone flavodoxin mutants possess lower stability than the corresponding form of wild-type flavodoxin, the redox potential of double electron reduction E_m,7 (fld) reached −360 mV, indicating that the flavodoxin mutant constituted solely by early amino acids can exert effective electron transfer activity.     

导电塑料作为钒电池集流板的研究

以聚乙烯为基体、炭黑为导电填料制备导电塑料板,研究了该导电塑料板导电性、力学性能以及在钒电池电解液中的电化学行为.导电塑料板与铜网复合后与石墨毡组成复合电极作为钒电池的正负极,考察了经过试验电池反复充放电后导电塑料集流板导电性与表面形貌的变化.研究结果表明导电塑料板可以代替石墨用作钒电池的集流板.当钒电池正极存在析氧过程时,会造成导电塑料集流板中的碳流失.     

The 31 Helix-Coil Transition for Polypeptides.: Circular Dichroism Studies

Abstract

Circular dichroism has become a popular method for following conformational transitions induced in optically active polymers. Recent refinement of experimental spectra obtained from model polypeptides by computer fitting to spectra obtained from solutions of proteins of known conformation has verified the applicability of the models chosen for the α helical and β conformations. However, the spectrum required for disordered regions was in conflict with much of the literature and agrees with our assignment based on studies of collagen and collagen models at elevated temperature. This spectrum consists of two troughs, one at ~225 nm and the other at ~200 nm. The latter had previously been associated with random polypeptides and we have shown the former to be sensitive to disorder in polymers approaching the 3₁ helical conformation. This paper presents the results from a study of three polypeptides which undergo a 3₁ helix → disorder transition.