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concentration

中学生英语(高中版) 2011年第11期 41-41页

作者：邓子暄武汉市外语学校高一(四)班

concentration PARTITION OF PROTEIN SOLUTION IN A MICROPORE:EFFECT OF ELECTROSTATIC INTERACTION

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Chinese Journal of Chemical Engineering 1996年第2期4卷 21-28页

作者：何志敏张海洋余国琮 Diego Barba Daniela Spera Department of Chemical Engineering University of L'Aquila 67100 L'Aquila Italy Consortium for Applied Research in Biotechnology 67051 Avezzano Italy

A theory for calculating the electrostatic interaction between protein molecules and the wallof a liquid-filled micropore is established in terms of solving the Laplace and the linearPoisson-Boltzmann *** surface charge of protein molecules is measured by theelectrophoresis velocity,whilethe charge of the pore wall is obtained by the ionic Donnan *** theory is then used to study the influence of solute-pore electrostatic interaction on theconcentration partition of protein solution in a micropore under different solution ***-mental verification is performed by detecting the hindered diffusion of bovine serum albumin in thetrack-etched polycarbonate membranes.A good consistence between the theoretical and experimentaldata is being achieved.

关键词： protein concentration partition micropore electrostatic interaction

concentration control of volatile organic compounds by ionic liquid absorption and desorption

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Chinese Journal of Chemical Engineering 2019年第10期27卷 2383-2389页

作者： Xiaobin Ma MinyanWu Shuo Liu Jinxing Huang Bin Sun Ying Zhou Qiulian Zhu Hanfeng Lu Institute of Catalytic Reaction Engineering College of Chemical EngineeringZhejiang University of TechnologyHangzhou 310014China Hangzhou Runxin Technology Co.Ltd. Hangzhou 310014China

Volatile organic compounds(VOCs)are difficult to be eliminated safely and effectively because of their large concentration ***,maintaining a stable concentration of VOCs is a significant *** this research,H2O,Tween-80,[Emim]BF4,[Emim]PF6,and[Hnmp]HSO4 were applied to absorb and desorb simulated *** ionic liquid[Emim]BF4 demonstrated the best performance and was thus selected for further *** the ionic liquid acted as a buffer,the toluene concentration with a fluctuation of 2000–20000 mg·m-3 was stabilized at 6000–12000 mg·*** distillation(90°C)was highly efficient to recover[Emim]BF4 from *** regenerated[Emim]BF4 could retain its initial absorption capacity even after multiple ***,[Emim]BF4 had the same buffer function on various aromatic hydrocarbons.

关键词： Volatile organic compounds concentration fluctuation Absorb and desorb Ionic liquid Buffer

concentration of mixed acid by electrodialysis for the intensification of absorption process in acrylic acid production

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Chinese Journal of Chemical Engineering 2021年第8期34卷 10-18页

作者： Hanxiao Du Lixin Xie Jie Liu Shichang Xu School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Membrane Science and Desalination Technology State Key Laboratory of Chemical EngineeringTianjin UniversityTianjin 300072China School of Chemical Engineering and Technology Hebei University of TechnologyTianjin 300130China Engineering Research Center of Seawater Utilization Ministry of EducationTianjin 300130China

The absorption process in acrylic acid production was *** concentration of acrylic acid before distillation process was low,which induced to large amount of wastewater and enormous energy *** this work,a new method was proposed to concentrate the side stream of absorption column and thus increase the concentration in bottom product by *** influence of operating conditions on concentration rate and specific energy consumption were investigated by a laboratory-scale *** the voltage drop was 1 V·cP^(-1)(1 cP=10^(-3) Pa·s),flow velocity was 3 cm·s^(-1) and the temperature was 35℃,the concentration rates of acrylic acid and acetic acid could be 203.3%and 156.6%in the continual-ED *** on the experimental data,the absorption process combined with ED was simulated,in which the diluted solution from ED process was used as spray water and the concentrated solution was feed back to the absorption *** results shown that the flow rate of spray water was decreased by 37.1%,and the acrylic acid concentration at the bottom of the tower was increased by 4.56%.The ions exchange membranes before and after use 1200 h were tested by membrane surface morphology(scanning electron microscope),membrane chemical groups(infrared spectra),ion exchange capacity,and membrane area resistance,which indicated the membrane were stable in the acid *** method provides new method for energy conservation and emission reduction in the traditional chemical industry.

关键词： Acrylic acid production Electrodialysis concentration Membranes Absorption Mixtures

concentration of nitrogen molecules needed by nitrogen nanobubbles existing in bulk water

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Applied Mathematics and Mechanics(English Edition) 2013年第12期34卷 1433-1438页

作者：张萌涂育松方海平 Shanghai Institute of Applied Physics Chinese Academy of Sciences Institute of Systems Biology Shanghai University

This paper investigates the stability of nitrogen nanobubbles under dif~ ferent concentrations of nitrogen molecules by molecular dynamics simulations. It is found that the stability of nanobubbles is very sensitive to the concentration of nitrogen molecules in water. A sharp transition between disperse states and assemble states of nitrogen molecules is observed when the concentration of nitrogen molecules is changed. The relevant critical concentration of nitrogen molecules needed by the existing nitrogen nanobubbles is analyzed.

关键词： nanobubble concentration stability

concentration polarization of atherogenic lipids in the arterial system

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Science China(Life Sciences) 2003年第2期46卷 153-164页

作者：邓小燕王贵学 Key Lab for Biomechanics & Tissue Engineering of Ministry of Education Chongqing University Chongqing 400044 ChinaState Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116023 China Key Lab for Biomechanics & Tissue Engineering of Ministry of Education Chongqing University Chongqing 400044 China

The transport of atherogenic lipids (LDL) in a straight segment of an artery with a semi-permeable wall was simulated numerically. The numerical analysis predicted that a mass transport phenomenon called 慶oncentration polarization?of LDL might occur in the arterial system. Under normal physiological flow conditions, the luminal surface LDL concentration was 5%—14% greater than the bulk concentration in a straight segment of an artery. The luminal surface LDL concentration at the arterial wall was flow-dependent, varying linearly with the filtration rate across the arterial wall and inversely with wall shear rate. At low wall shear rate, the luminal surface LDL concentration was very sensitive to changes in flow conditions, decreasing sharply as wall shear rate increased. In order to verify the numerical analysis, the luminal surface concentration of bo-vine serum albumin (as a tracer macromolecule) in the canine carotid artery was measured in vitro by directly taking liquid samples from the luminal surface of the artery. The experimental result was in very good agreement with the numerical analysis. The authors believe that the mass transport phenomenon of 慶oncentration polarization?may indeed exist in the human circulation and play an important role in the localization of atherosclerosis.

关键词： mass transport, concentration polarization, wall shear rate, atherosclerosis.

concentration difference of auxin involved in stem development in soybean

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Journal of Integrative Agriculture 2020年第4期19卷 953-964页

作者： JIANG Zhen-feng LIU Dan-dan WANG Tian-qiong LIANG Xi-long CUI Yu-hai LIU Zhi-hua LI Wen-bin Key Laboratory of Soybean Biology Ministry of Education/Soybean Research InstituteNortheast Agricultural UniversityHarbin 150030P.R.China College of Agronomy Heilongjiang Bayi Agricultural UniversityDaqing 163311P.R.China London Research and Development Center Agriculture and Agri-food CanadaLondon N5V 4T3Canada College of Resources and Environment Northeast Agricultural UniversityHarbin 150030P.R.China

Auxin regulates cell division and elongation of the primordial cells through its concentration and then shaped the plant architecture. Cell division and elongation form the internode of soybean and result in different plant heights and lodging resistance. Yet the mechanisms behind are unclear in soybean. To elucidate the mechanism of the concentration difference of auxin related to stem development in soybean, samples of apical shoot, elongation zone, and mature zone from the developing stems of soybean seedlings, Charleston, were harvested and measured for auxin concentration distributions and metabolites to identify the common underlying mechanisms responsible for concentration difference of auxin. Distribution of indole-3-acetic acid(IAA), indole-3-butyric acid(IBA), and methylindole-3-acetic acid(Me-IAA) were determined and auxin concentration distributions were found to have a complex regulation mechanism. The concentrations of IAA and Me-IAA in apical shoot were significantly different between elongation zone and mature zone resulting in an IAA gradient. Tryptophan dependent pathway from tryptamine directly to IAA or through indole-3-acetonitrile to IAA and from indole-3-propionic acid(IPA) to IAA were three primary IAA synthesis pathways. Moreover, some plant metabolites from flavonoid and phenylpropanoid synthesis pathways showed similar or reverse gradient and should involve in auxin homeostasis and concentration difference. All the data give the first insight in the concentration difference and homeostasis of auxin in soybean seedlings and facilitate a deeper understanding of the molecular mechanism of stem development and growth. The gathered information also helps to elucidate how plant height is formed in soybean and what strategy should be adopted to regulate the lodging resistance in soybean.

关键词： soybean concentration difference of auxin stem development metabolites

concentration and environmental significance of lead in surface snow of Antarctic ice sheet (III)

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Science China Chemistry 1995年第5期38卷 632-640页

作者：秦大河任贾文孙俊英陈瓞延文克玲李良权 Lanzhou Institute of Glaciology and Geocryology Chinese Academy of Sciences Lanzhou 730000. China Department of Modern Applied Physics Tsinghua University Beijing 100084 China

Lead as an ultra-trace heavy metal becomes one of popular topics in glaciochemistry of the Antarctic ice sheet, because of its very low concertration (pg·g-1) and background and its sensitivity to the quality of the environment. The lead concentration of surface snow of the Antarctic ice sheet (corresponding to modern precipitation) applying LEAF technique by Chinese scholars has systematically been studied for the first time in the world. The distribution principle of lead concentration of surface snow of the Antarctic ice sheet is 'low in the west and high in the east' along the route of 1990 International Trans-Antarctic Expedition (ITAE). The concentration of lead in East Antarctica is 2 - 3 fold higher than that in Larsen ice shelf and Antarctic Peninsula, which majorly results from the activity of pre-Soviet Antarctic Expedition The concentration of lead in Larsen ice shelf and Antarctic Peninsula can be regarded as the background value of modern precipitation of the Antarctic ice sheet in the end of 1980s

关键词： Antarctic ice sheet LEAF analysis lead concentration anthropogenic pollution geographic distribution.

concentration, Distribution, and Occurrence of REEs in Coals from Chongqing,Southwest China

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Journal of China University of Mining and Technology 2005年第3期15卷 227-233页

作者： LI Da-hua TANG Yue-gang CHEN Kun DENG Tao CHENG Fang-ping LIU Dong Department of Resources and Earth Science China University of Mining ＆ Technology Beijing 100083 China Chongqing Coal Geology Institute Chongqing 400042 China

The concentration, distribution, and occurrence of rare earth elements (REEs) in coals as well as stone coalsin different geological periods from Chongqing were studied. The results show that the REE content in coals fromChongqing is much higher than that of the ordinary Chinese coals, the Late Paleozoic coals from North China, UScoals, and the world coals. Although the concentration of light rare earth elements (LREE) is higher than that of heavyrare earth elements (HREE), the ratio of LREE to HREE is as low as 5.11. The REE content decreases with thecoal-formation periods from old to new. The REE content in the Sinian stone coal is the highest, but it is the lowest inEarly Jurassic coals. The similar REE contents in bituminous coals and anthracite show that the metamorphism has alittle influence on REE content in coal. In addition, silicate association dominates the occurrence mode of REEs incoals from Chongqing.

关键词： coal rare earth elements concentration Chongqing