检索结果-南通市图书馆

Homologous and heterologous interactions between catalytic and regulatory subunits of Escherichia coli acetohydroxyacid synthaseⅠand Ⅲ

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2009年第9期52卷 1362-1371页

作者： NIU CongWei, FENG Wei, ZHOU YanFei, WEN Xin & XI Zhen State Key Laboratory of Elemento-Organic Chemistry and Department of chemical Biology, Nankai University, tianjin 300071,{2. State Key Laboratory of Elemento-Organic Chemistry and Department of chemical Biology Nankai University Tianjin China

Homologous and heterologous interactions between acetohydroxyacid synthase (AHAS) I and Ⅲ from E. coli have been studied by surface plasmon resonance (SPR). The catalytic and regulatory subunits association for AHAS I (KD = 1.13 × 10-7 M) was stronger than that for AHAS Ⅲ (KD = 5.2. × 10-7 M). A strong heterologous association between regulatory and catalytic subunits and heterologous activation of catalytic subunits were observed. SPR results combined with enzyme kinetics indicate that the reconstituted heterologous enzymes had similar kinetic properties as homologous enzymes, implying that the regulatory subunit of AHAS I could be replaced by the regulatory subunit of AHAS Ⅲ and vice versa. This work may be useful to further understandings of the mechanism of regulation of AHAS.

关键词： acetohydroxyacid synthase subunit interaction surface plasmon resonance

REMOVAL OF VOCs FROM THE AQUEOUS SOLUTIONS BY PERVAPORATION USING A FILLING-TYPE MEMBRANE

在线全文

学校读者我要写书评

暂无评论

化工学报 2000年第S1期51卷 335-337页

作者： Jiang Zhongyi, Xu Haiquan, Ding Yuhui and Liu Jiaqi (School of chemical Engineering and Technology, tianjin University tianjin 300072.

The membranes were prepared by the incorporation of highly hydrophobic silicalite and carbon molecular sieves (CMS) from different precursors into the PDMS casting solutions. The pervaporative removal of VOCs, such as benzene, from aqueous solutions was carried out using the separation factor and permeation flux as the evaluating parameters. The effects of the CMS types and structures, feed concentrations on the pervaporation performance were preliminarily investigated.

关键词： Removal Benzene aqueous solution Pervaporation

Synthesis and characterization of magnetic polymer microspheres with a core-shell structure

在线全文

学校读者我要写书评

暂无评论

Particuology 2007年第Z1期 180-185页

作者： Ming Lu, Shu Bai, Kun Yang, Yan Sun Department of Biochemical Engineering, School of chemical Engineering and Technology, {2. University, {2. 300072. china

Non-porous magnetic polymer microspheres with a core-shell structure were prepared by a novel micro-suspension polymerization technique. A stable iron oxide ferrofluid was used to supply the magnetic core, and the polymeric shell was made of glycidyl methacrylate (GMA monomer) and ethylene dimethacrylate (cross-linker). In the preparation, polyvinyl alcohol was used as the stabilizer, and a lauryl alcohol mixture as the dispersant. The influence of various conditions such as aqueous phase volume, GMA and initiator amounts, reaction time and stirring speed on the character of the microspheres was investigated. The magnetic microspheres were then characterized briefly. The results indicate that the microspheres with active epoxy groups had a narrow size distribution range from 1 to 10 m with a volume-weighted mean diameter of 4.5 m. The saturation magnetization reached 19.9 emu/g with little coercivity and remanence.

关键词： Ferrofluid Micro-suspension polymerization Magnetic microspheres Particle size Magnetization

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

锰铈混和氧化物气凝胶催化剂的研究

燃料化学学报 2004年第1期32卷 93-97页

作者：孙海龙刘源刘少文天津大学材料科学与工程学院天津300072 天津大学化工学院天津300072

采用溶胶凝胶法和超临界干燥技术制备出CeO2.Ce1 xMnxO2.x分别为0 05,0 10,0 15,0 2.)气凝胶。以硝酸锰浸渍制得的氧化铈气凝胶Mn/CeO2.用TEM、BET、一氧化碳催化氧化活性评价和H2.TPR对所制备的催化剂进行了研究。TEM、BET的结果表明... 详细信息

采用溶胶凝胶法和超临界干燥技术制备出CeO2.Ce1 xMnxO2.x分别为0 05,0 10,0 15,0 2.)气凝胶。以硝酸锰浸渍制得的氧化铈气凝胶Mn/CeO2.用TEM、BET、一氧化碳催化氧化活性评价和H2.TPR对所制备的催化剂进行了研究。TEM、BET的结果表明,随着锰含量的增加,氧化铈气凝胶的粒度减小,表面积增大。一氧化碳催化氧化活性评价显示,氧化铈中添加锰制得的催化剂的一氧化碳低温催化氧化的活性比未添加锰的氧化铈提高。且锰加入量为15mol%时,气凝胶的催化活性最高。锰的引入方式不同,气凝胶的催化活性不同。浸渍方式负载锰所制备的Mn/CeO2.凝胶的一氧化碳催化氧化活性低于Ce1 xMnxO2.x分别为0,0 05,0 10,0 15,0 2.)气凝胶。TPR实验发现,与氧化锰相同,氧化铈上负载的锰的还原也分三步进行。

关键词：氧化铈气凝胶氧化锰一氧化碳氧化 TPR

NUMERICAL SIMULATION OF THE FLOW FIELD IN A REACTOR FOR TITANIUM DIOXIDE PRODUCTION

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 1988年第2期4卷 124-133页

作者： Zhao Guoying Zhu Chingwen, Institute of Mechanics, Chinese Academy of SciencesWan Chongyun, china tianjin {2. Engineering Corp. Institute of Mechanics Chinese Academy of Sciences China china tianjin {2. Engineering Corp China

A physicochemical and fluid dynamic model is formulated for the numerical simulation of theflow field in a reactor for titanium dioxide production, the turbulence motion is described by the K-εequation, the governing equations are solved by the SIMPLER algorithm devised by Partankar and *** velocity, tmperature and concentration fields are obtained for three eases: A) with chemical reaction andthermal insulation on the walls; B) with chemical reaction and wall temperature is 450K; C) without chemicalreaction and thermal insulation on the walls, and the physicochemical numerical simulation for the titaniumdioxide production has been done. The results of the paper can be used as a theoretical guide for the engineersin the design of such reactors.

关键词： Numerical simulation of a reactor Model of a reactor Plasma reactor Titanium dioxide reactor

非均相成核中间相炭微球的形成过程及其结构演变

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

新型炭材料 2004年第4期19卷 281-288页

作者：李同起王成扬郑嘉明王慧天津大学化工学院天津300072 天津大学分析中心天津300072

　以含有喹啉不溶物的煤焦油沥青为原料,在410℃、不同反应时间下获得一系列中间相炭微球(MCMB)和小于0.5μm的碳质颗粒(SCP)。通过对中间相沥青的软化点、族组成和MCMB、SCP的形貌及MCMB断面结构的分析,认为非均相成核MCMB的形成和生... 详细信息

　以含有喹啉不溶物的煤焦油沥青为原料,在410℃、不同反应时间下获得一系列中间相炭微球(MCMB)和小于0.5μm的碳质颗粒(SCP)。通过对中间相沥青的软化点、族组成和MCMB、SCP的形貌及MCMB断面结构的分析,认为非均相成核MCMB的形成和生长过程不同于均相成核的融并生长过程,而是SCP碳质颗粒的构筑过程,我们称之为"球形基本单元构筑"过程。在MCMB生长过程中,体系的黏度对SCP的形成和MCMB的生长起着重要的作用。非均相成核MCMB的内部结构不是三种模型结构("地球仪"型、"洋葱"型和"同心圆"型)中的任一种,而是炭层具有收缩点的复杂结构,并且球体的结构不具有"继承性",即随着反应时间的延长而不断发生变化和调整。MCMB内部分子在球体生长过程中的主要变化趋势是分子的不断缩合长大,而不是分子片层的平行趋向。

关键词：中间相炭微球煤焦油沥青结构缺陷非均相成核碳质颗粒

NUMERICAL ANALYSIS OF THE PERFORMANCE OF HORIZONTAL AND WAVY SUBSURFACE FLOW CONSTRUCTED WETLANDS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2011年第3期23卷 339-347页

作者： WANG Jun HUANG Sui-liang HE Cheng-da NG Chiu-On College of Environmental Science and Engineering Nankai University Tianjin 300071 China Numerical Simulation Group for Water Environment Key Laboratory of Pollution Processes and EnvironmentalCriteria of Ministry of Education Tianjin Key Laboratory of Environmental Remediation and Pollution ControlCollege of Environmental Science and Engineering Nankai University Tianjin 300071 China College of Environmental Science and Engineering Yangzhou University Yangzhou 225009 China Department of Mechanical Engineering The University of Hong Kong Hong Kong China

A three-dimensional numerical model is proposed for modeling the TP transport in the Horizontal Subsurface Flow （HSSF） and Wavy subsurface Flow （WSSF） constructed wetland in this article. Both numerical simulations and physical experiments indicate that the removal efficiency of WSSF is higher than that of HSSF. The difference ofperforrnance in removing pollutants, e.g., Total Phosphorus （TP）, between HSSF and WSSF is numerically analyzed from three interactive aspects, that is, the hydraulic behavior, the substrate and the plant roots. It is shown that the dead zone volume in WSSF is smaller than in HSSF with less short circuiting. The soil in the top layer is more used in WSSF than in HSSF. The TP uptake by the plant roots in WSSF is higher than that in HSSF.

关键词： numerical model constructed wetland hydraulic behavior Retention Time Distribution (RTD) removal efficiency

Equations and their physical interpretation in numerical modeling of heavy metals in fluvial rivers

在线全文

学校读者我要写书评

暂无评论

中国科学：技术科学英文版 2010年第2期53卷 548-557页

作者： HUANG SuiLiang Numerical Simulation Group for Water Environment, tianjin Key Laboratory of Environmental Remediation and Pollution Control, Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education College of Environmental Science and Engineering, Nankai University, tianjin 300071,{2. Numerical Simulation Group for Water Environment Tianjin Key Laboratory of Environmental Remediation and Pollution Control Key Laboratory of Pollution Processes and Environmental Criteria of the Ministry of Education College of Environmental Science an

Based on the previous work on the transport-transformation of heavy metal pollutants in fluvial rivers, this paper presented the formulation of a two-dimensional model to describe heavy metal transport-transformation in fluvial rivers by considering basic principles of environmental chemistry, hydraulics, mechanics of sediment transport and recent developments along with three very simplified test cases. The model consists of water flow governing equations, sediment transport governing equations, transport-transformation equation of heavy metal pollutants, and convection-diffusion equations of adsorption-desorption kinetics of particulate heavy metal concentrations on suspended load, bed load and bed sediment. The heavy metal transport-transformation equation is basically a mass balance equation, which demonstrates how sediment transport affects transport-transformation of heavy metals in fluvial rivers. The convection-diffusion equations of adsorption-desorption kinetics of heavy metals, being an extension of batch reactor experimental results and a major advancement of the previous work, take both physical transport, i.e. convection and diffusion and chemical reactions, i.e. adsorption-desorption into account. Effects of sediment transport on heavy metal transport-transformation were clarified through three examples. Specifically, the transport-transformation of heavy metals in a steady, uniform and equilibrium sediment-laden flow was calculated by applying this model, and results were shown to be rational. Both theoretical analysis and numerical simulation indicated that the transport-transformation of heavy metals in sediment-laden flows with clay-enriched riverbed possesses not only the generality of common tracer pollutants, but also characteristics of transport-transformation induced by sediment motion. Future work will be conducted to present validation/application of the model with available data.

关键词： heavy metals transport-transformation water-sediment-pollutants interaction fluvial rivers numerical modeling

Optimization of a synthetic medium for ethanol production by xylose-fermenting Zymomonas mobilis using response surface methodology

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2012年第Z2期 3782-3789页

作者： DONG HuiNa 1,2.4,5,ZHAO XueMing 2.4,5,MA YuanYuan 1* & ZHANG MinHua 1,3 1 tianjin University R&D Center for Petrochemical Technology,tianjin University,tianjin 300072.china 2.Department of Biochemical Engineering,School of chemical Engineering and Technology,tianjin University,tianjin 300072.china 3 State Key Laboratory of Engines,tianjin University,tianjin 300072.china 4 Key Laboratory of Systems Bioengineering,Ministry of Education,tianjin University,tianjin 300072.china 5 Edinburgh-tianjin Joint Research centre for Systems Biology and Synthetic Biology,tianjin University,tianjin 300072.china

A synthetic medium for ethanol production by recombinant xylose-fermenting Zymomonas mobilis was optimized using Plackett-Burman(PB) design and response surface methodology(RSM).The effects of 19 medium components were investigated by PB *** of these components were determined to have significant effects on ethanol *** statistical model was constructed via central composite design(CCD) using five selected variables,including xylose,trisodium citrate,choline chloride,pyridoxine,and *** validity of the developed model was *** ethanol concentration in the optimized medium was 6.7% higher than in the RM *** optimized medium was then simplified to give the final synthetic medium(S2.,in which the ethanol concentration was 2..7% higher than in the RM *** and trisodium citrate were the key medium components influencing ethanol production,while calcium pantothenate was the only growth factor required by recombinant *** production and growth response were directly proportional to the logarithm of the concentration of trisodium citrate in the range of 0.1-1.6 g/L.

关键词： recombinant Zymomonas mobilis synthetic medium ethanol production response surface methodology trisodium citrate xylose