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A thin-layer spectroelectrochemical study of 3,3',5,5'-tetramethylbenzidine at SnO_2.F film optically transparent electrode

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Science china Chemistry 2004年第4期47卷 267-275页

作者： JIAO Kui1. YANG Tao2.& NIU Shuyan1.2.1. College of Chemistry and Molecular engineering, Qingdao university of Science and Technology, Qingdao 2.6042.{2. 2. College of Chemistry and Chemical engineering, Ocean university of{2., Qingdao 2.6003,{2. Correspondence should be addressed to Jiao Kui 1. College of Chemistry and Molecular engineering Qingdao University of Science and Technology 266042 Qingdao China 2. College of Chemistry and Chemical {1. Ocean University of China 266003 Qingdao China

The electrooxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) is dependent on the pH value of Britton-Robinson (B-R) buffer solution. In this work, the electrooxidation behavior of TMB was investigated with a SnO2.F film optically transparent thin-layer spectroelectrochemical cell. TMB underwent one two-electron electrooxidation process in the pH range from 2.0 to < 4.0, and two successive one-electron electrooxidation processes in the pH range from 4.0 to < 7.0 in the B-R buffer solution. At pH 6.5, the electrooxidative product of TMB generated a subsequent chemical reaction to yield an azo compound. Several spectroelectrochemical techniques, such as thin-layer cyclic voltammetry, thin-layer cyclic voltabsorptometry, thin-layer potential-controlled electrolysis absorptometry, thin-layer single-potential-step chronoabsorptometry, thin-layer dou-ble-potential-step chronoabsorptometry, thin-layer single-potential-step open-circuit relaxation chronoabsorptometry, were applied to this investigation. The formal potential E0’ and the electron transfer number corresponding to the electrooxidation of TMB in B-R buffer solution, and the reaction rate constant of the subsequent chemical reaction were determined.

关键词： 3,3′,5,5′-tetramethylbenzidine tin oxide film optically transparent electrode thin-layer spectroelectro-chemistry electrooxidation

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The numerical method for three-dimensional impact with friction of multi-rigid-body system

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Science china(Physics,Mechanics & Astronomy) 2006年第1期49卷 102-118页

作者： ZHAO Zhen1.2. LIU Caishan2.& CHEN Bin2.1. Beijing Institute of Graphic Communication, Beijing 1.2.00, china 2. Department of Mechanics & engineering Science, Peking {2., Beijing 1.0871. china Beijing Institute of Graphic Communication Beijing 102600 China Department of Mechanics & engineering Science Peking University Beijing 100871 China

The differential equations for planar impacts reduce to an algebraic form, and can be easily solved. For three dimensional impacts with friction, there is no closed-form solution, and numerical integration is required due to the swerve behavior of tangential impulse during collisions. The dynamic governing equations in the impact process are built up in impulse space based on the Lagrangian equation in this paper. The coefficient of restitution defined by Poisson is used as the condition of impact termination. A valid nu- merical method for solving three-dimensional frictional impact of multi-rigid body system is established. The singular cases of tangential movement in sticking point are especially noticed and analyzed. Several examples are present to reveal the different kinds of tan- gential movement modes varied with the normal impulse during collision.

关键词： multi-rigid body, impact, friction.

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Silylated and acetylated β-cyclodextrins for gas chromatographic stationary phases

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Journal of Central South university of Technology 2001年第4期8卷 239-243页

作者： TANG Ke wen 1.2.,YI Jian ming 2.ZHOU Chun shan 1.ZHONG Shi an 1.(1. College of Chemistry and Chemical engineering, Central South university, Changsha 41.083,{2. 2. College of Chemistry and Chemical engineering, Yueyang Normal university 1. College of Chemistry and Chemical engineering Central South University 410083 Changsha China 2. College of Chemistry and Chemical {1. Yueyang Normal University 414000 Yueyang China

Two new chiral stationary phases, 2.3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2.6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 41.3 and 392., the column efficiencies are respectively 3084 and 41.8, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1. and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.2. and 1.01..

关键词： capillary gas chromatography silylated and acetylated β-cyclodextrins enantiomeric separation

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A preliminary study on vegetation-erosion dynamics and its applications

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Science china Earth Sciences 2005年第5期48卷 689-700页

作者： WANG Zhaoyin 1.2., WANG Guangqian 1., LI Changzhi 1.& WANG Feixin 1.1. Department of Hydraulic {1., Tsinghua university, Beijing 1.0084,{2. 2. International Research and Training Center on Erosion and Sedimentation, Beijing 1.0084,{2. 1. Department of Hydraulic engineering Tsinghua University 100084 Beijing China 2. International Research and Training Center on Erosion and Sedimentation 100084 Beijing China

Vegetation-erosion dynamics is a new interdisciplinary science, studying the laws of evolution of watershed vegetation under the action of various ecological stresses. Introducing a qualitative expression of ecological stresses in this paper, the present authors establish the cou- pled differential equations for the vegetation-erosion process and derive a theoretical solution. The model is applied to the Anjiagou watershed on the Loess Pateau and the Xiaojiang water- shed and its sub-watersheds on the Yunnan Plateau. The calculated results agree well with the vegetation development processes. Abstracted from the differential equations the so-called vegetation-erosion chart is worked out, with which we can predict the development trend of vegetation under no human stresses. It is demonstrated that the erosion control is important for vegetation development and reforestation must be a long-term strategy. On the Yunnan Plateau with relatively high precipitation and temperature, vegetation can be greatly improved if erosion is controlled. On the dry and cold Loess Pateau suffering from high rate of soil erosion, however, vegetation can effectively control erosion but erosion reduction exhibits low effectiveness on vegetation development. Vegetation in the area is not stable and management is always needed to maintain the vegetation.

关键词： vegetation-erosion dynamics, human activities, coupled differential equations, erosion control, vigor ofvegetation.

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Effect and mechanism of stresses on rock permeability at different scales

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Science china Earth Sciences 2006年第7期49卷 714-723页

作者： YIN Shangxian1.& WANG Shangxu2.1. Safety {1. College, North china Institute of Science and Technology, Yanjiao, Beijing 1.1.01. china 2. Key Laboratory of Geophysics Exploration, china university of Petroleum, Beijing 1.0083, china 1. Safety engineering College North China Institute of Science and Technology Yanjiao Beijing 101601 China 2. Key Laboratory of Geophysics Exploration China University of Petroleum Beijing 100083 China

The effect of geo-stress fields on macroscopic hydro-geological conditions or micro-cosmic permeability of water-bearing media should follow some laws or principles. Cases study and tests show that: (1. At macro-geologic large scale, deformed and crashed rocks which were induced by geo-stress fields changing provided space for groundwater storage and flow. Groundwater adjusts water-bearing space and dilatants fractures by flowing and press transferring. Coupling of liquid and solid can be implemented for rocks and groundwater. Although tectonic fields witness several times of change and build-up in geological time, stress fields forming regional tectonic framework are coherent with seepage fields, orientation of the maximum horizontal stress demonstrates main seepage direc-tions. (2. At macro-geologic middle scale, zones of stresses changing sharply, quite low stresses, stress or shear concentration can be used to show locations and types of main fractures, zones of geo-stresses changing equably can be acted as normal base media zones of tri-porosity media. (3) At micro-geologic small scale, tri-porosity media include fractured rocks, porous rocks and capillary rocks. Investigations indicate that porosity or permeability is functions of effective stresses, and po-rosity or permeability changing rules of porous rocks with variation of effective stresses can be de-scribed as the index model, the model of power exponent functions is suitable for those of fractured rocks, the model of the second power parabola for capillary rocks. The porosity and permeability loss in fractured rocks, which are greater than that in porous rocks, are shown by calculation of effective compressive coefficient and closing pressure in cracks. The calculations can also explain the mecha-nism why porosity changes are always larger than permeability changes. It is proved by the thick wall cylinder theory that the second power parabola relation between porosity or permeability loss and effective

关键词： geo-stress fields, seepage fields, tri-porosity media, effective stresses, permeability, porosity,scale.

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Relationship between surface subsidence factor and mining depth of strip pillar mining

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中国有色金属学会会刊：英文版 2011年第S3期21卷 594-598页

作者： GUO Wen-bing1. 2. HOU Quan-lin 1. ZOU You-feng2.1. College of Earth Science, Graduate university of Chinese Academy of Sciences, Beijing 1.0049, china 2. School of Energy Science and {2., Henan Polytechnic university, Jiaozuo 454000, china Chinese Acad Sci Coll Earth Sci Grad Univ Beijing 100049 Peoples R China Henan Polytech Univ Sch Energy Sci & Engn Jiaozuo 454000 Peoples R China

Strip pillar mining is one of the most important technical measures to control mining subsidence in china. Mining depth is one of the most important factors that can affect the mining subsidence in strip pillar mining. Six numerical simulation models were set up to simulate the surface subsidence of strip pillar mining in different mining depths. The mining depth in these six models ranges from 300 to 800 m. The simulated results were compared and analyzed. The formula was established based on the simulated results. It demonstrated that the subsidence of strip pillar mining method is related to mining depth. While the other conditions are the same, the subsidence of strip pillar mining increases with the increase of mining depth by logarithmic relationship.

关键词： subsidence factor strip pillar mining mining depth numerical simulation

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A novel algorithm of artificial immune system for high-dimensional function numerical optimization

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Progress in Natural Science:Materials International 2005年第5期15卷 463-471页

作者： DU Haifeng 1.2.*, GONG Maoguo1. JIAO Licheng1.and LIU Ruochen1.1. Institute of Intelligent Information Processing and Key Laboratory of Radar Signal Processing, Xidian {1., Xi'an 71.071. china 2. School of Mechanical {2., Xi'an Jiaotong {1., Xi'an 71.049, china) Institute of Intelligent Information Processing and Key Laboratory of Radar Signal Processing Xidian University Xi''an 710071 China School of Mechanical engineering Xi''an Jiaotong University Xi''an 710049 China

Based on the clonal selection theory and immune memory theory, a novel artificial immune system algorithm, immune memory clonal programming algorithm (IMCPA), is put forward. Using the theorem of Markov chain, it is proved that IMCPA is convergent. Compared with some other evolutionary programming algorithms (like Breeder genetic algorithm), IMCPA is shown to be an evolutionary strategy capable of solving complex machine learning tasks, like high-dimensional function optimization, which maintains the diversity of the population and avoids prematurity to some extent, and has a higher convergence speed.

关键词： clonal selection immune memory artificial immune system evolutionary algorithms Markov chain.

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Molecular dynamics simulation of thermal stability of nanocrystalline vanadium

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Science china(Technological Sciences) 2006年第4期49卷 400-407页

作者： WEI Mingzhi1. XIAO Shifang1. YUAN Xiaojian2.& HU Wangyu1.2.1. Material Science and engineering College, Hunan university, Changsha 41.082.{2. 2. Department of Applied Physics, Hunan university, Changsha 41.082.{2. Material Science engineering College Hunan University Changsha 410082 China Department of Applied Physics Hunan University Changsha 410082 China

The microstructure and thermal stability of nanocrystalline vanadium with an average grain size ranging from 2.86 to 7.50 nm are calculated by means of the analytic embedded-atom method and molecular dynamics. The grain boundary and nanocrystal- line grain atoms are differentiated by the common neighbor analysis method. The results indicate that the fraction of grain boundary increases with the grain size decreasing, and the mean energy of atoms is higher than that of coarse crystals. The thermal-stable tem- peratures of nanocrystalline vanadium are determined from the evolution of atomic energy, fraction of grain boundary and radial distribution function. It is shown that the stable tem- perature decreases obviously with the grain size decreasing. In addition the reasons which cause the grain growth of nanocrystalline vanadium are discussed.

关键词： nanocrystalline, embedded-atom method, molecular dynamics, thermal stability.

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Study on impurity desorption induced by femtosecond pulse laser based on a stochastic process model

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Science china(Technological Sciences) 2006年第1期49卷 78-88页

作者： CHI Yinsheng1. LIN Xiaohui1. ZHUANG Ping1.& CHEN Yunfei1.2.1. Department of Mechanical {1., Southeast university, Nanjing 2.0096,{2. 2. Key Laboratory of MEMS of{2. Educational Ministry, Southeast university, Nanjing 2.0096,{2. Department of Mechanical engineering Southeast University Nanjing 210096 China Key Laboratory of MEMS of china Educational Ministry Southeast University Nanjing 210096 China

With the advantages on non-equilibrium heating and desorption induced by electronic transition, the femtosecond pulse laser introduces a new way for solving the problem of impurity pollution adsorbed on a solid thin film in micro-electro-mechanical systems (MEMS). A model based on stochastic processes was established for stimulated desorption induced by the femtosecond pulse laser to interpret the interaction of the opti-cally excited hot electrons with the adsorbed molecules in a metal substrate. Numerical simulation results reveal a time-dependent desorption probability of adsorbed molecules and indicate that how key parameters of femtosecond pulse laser, such as incident laser energy flux, pulse duration, and wavelength of pulse, have a great effect on the desorption probability.

关键词： desorption, femtosecond pulse laser, stochastic process.

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Microstructural Evolution of Surface Layer of TWIP Steel Deformed by Mechanical Attrition Treatment

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Journal of Iron and Steel Research International 2012年第3期19卷 38-46页

作者： LI Da-zhao1.2. WEI Ying-hui1. HOU Li-feng1. LIN Wan-ming1.(1. College of Materials and {1., Taiyuan university of Technology, Taiyuan 03002., Shanxi,{2. 2. College of Materials and {1., North university of{2., Taiyuan 030051. Shanxi,{2.) [a] College of Materials and engineering Taiyuan University of Technology Taiyuan 030024 Shanxi China [b] College of Materials and engineering North University of China Taiyuan 030051 Shanxi China

A nanocrystalline layer was synthesized on the surface of TWIP steel samples by surface mechanical attri- tion treatment （SMAT） under varying durations. Microhardness variation was examined along the depth of the de- formation layer. Microstructural characteristics of the surface at the TWIP steel SMATed for 90 min were observed and analyzed by optical microscope, x-ray diffraction, transmission and high-resolution electron microscope. The re- sults show that the orientation of austenite grains weakens, and a-martensite transformation occurs during SMAT. During the process of SMAT, the deformation twins generate and divide the austenite grains firstly~ then a-martens- ite transformation occurs beside and between the twin bundles~ after that the martensite and austenite grains rotate to accommodate deformation, and the orientations of martensite and between martensite and residual austenite increase; lastly the randomly oriented and uniform-sized nanocrystallir^e layers are formed under continuous deformation.

关键词： SMAT technology twinning stacking fault energy deformation twin

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