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Size distributions and magic number characteristics of cluster configurations formed during solidification processes of liquid metal Al

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science china(Technological sciences) 2006年第2期49卷 172-187页

作者： LIU Rangsu1, LIU Fengxiang1, DONG Kejun1, ZHENG Caixing1, LIU Hairong2. PENG Ping2.& LI Jiyong3 1. department of Physics, hunan University,{2. 2. department of material science and engineering, hunan University,{2. 3. department of Chemistry, hunan University,{2. 1. department of Physics Hunan University Changsha 410082 China 2. department of material science and engineering Hunan University Changsha 410082 China 3. department of Chemistry Hunan University Changsha 410082 China

A molecular dynamics simulation study has been performed for a large systemconsisting of 100000 liquid metal Al atoms to investigate the formation and magic numbercharacteristics of the cluster configurations formed during the rapid solidification processes. Thecluster-type index method (CTIM) has been adopted to describe various types of clusterconfigurations. The results indicate that the icosahedral clusters (12.0 12.0) and theircombinations play the most important role in the rnicrostructure transitions during solidificationprocesses; for the cluster configurations of different levels formed by various combinations withdiffering numbers of basic clusters, their size distributions possess obvious magic number sequencewhich is in turn as 13(13), 19(2.), 2.-2.(2.), 32.33(32., 39-40, 43-44, 48..., (those in bracket arethe corresponding value in liquid state); the magic numbers correspond to the peak value positionsof the cluster numbers for corresponding level formed with various combinations by 1, 2. 3, 4, 5, 6,7, ...basic clusters, respectively. This magic number sequence is in good agreement with theexperimental results obtained by Harris et al. At the same time, this simulation study also gives ascientific and reasonable explanation to these experimental results.

关键词： liquid metal, solidification processes, cluster configuration, magic numbers, computer simulation.

A new orthogonality relationship for orthotropic thin plate theory and its variational principle

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science china(Physics,Mechanics & Astronomy) 2005年第3期48卷 371-380页

作者： LUO Jianhui 1 , LONG Yuqiu 2.& LIU Guangdong 1 1. College of Civil engineering, hunan University,{2. 2. department of Civil engineering, Tsinghua University, Beijing 100084, china 1. College of Civil engineering Hunan University 410082 Changsha China 2. department of Civil engineering Tsinghua University 100084 Beijing China

The thought how dual vectors are constructed in a new orthogonality relationship for theory of elasticity is generalized into orthotropic thin plate bending problems by using the analogy theory between plane elasticity problems and plate bending problems. Dual differential equations are directly obtained by using a mixed variables method. A dual differential matrix to be derived possesses a peculiarity of which principal diagonal sub-matrixes are zero matrixes. Two independently and symmetrically orthogonality sub-relationships are discovered. By using the integral form for elastic bending theory of orthotropic thin plate the orthogonality relationship is demonstrated. By selecting felicitous dual vectors a new orthogonality relationship for theory of elasticity can be generalized into elastic bending theory of orthotropic thin plate. By using the integral form a variational principle which is relative to differential form and a whole function expression are proposed.

关键词： theory of elasticity, thin plate theory, dual vectors, orthogonality relationship, orthotropic, variational principle.

Effect of static magnetic field on activity of immobilized α-amylase

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Chinese science Bulletin 1997年第2期42卷 127-130页

作者： YAN Liushui, ZHU Yuanbao, HE-Shuang’e and CAO Zhixiang1 department of Chemical engineering, Nanchang Institute of Aeronautical Technology, Nanchang 330034, {2. 2. department of Chemistry and Chemical engineering, hunan University, changsha 410082. china department of Chemical engineering Nanchang Institute of Aenwututical Techndogy Nanchang China department of Chemistry and Chemical engineering Hunan University Changsha China

BIOLOGICAL effect of magnetic field is one of the three major subjects of contemporary biomagnetism, and is also the basis of applied biomagnetism. In order to explore magnetic biological effects, the influence of various sorts of magnetic field on many living systems as well as their different constructural levels has been extensively studied. However, only a few studies with in vitro enzyme have been reported, and few researches concerning the influence of magnetic field on immobilized enzyme reactions have been published. This note describes

关键词： static magnetic field immobilized α-amylase enzyme activity oscillatory behaviour.

A Series Piezoelectric Quartz Crystal Response Kinetics for *** Growth in the Presence of Cu(Ⅱ)

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Journal of Central South University 2000年第1期12卷 15-19页

作者： CHAI Li yuan 1,2.,WEI Wan zhi 2.YAO Shou zhuo 2.1. department of Metallurgical science and {2., Central South University of Technology, changsha 410083, china 2. College of Chemistry and Chemical {2., hunan University, changsha 1. department of Metallurgical science and {2. Central South University of Technology 410083 Changsha China 2. College of Chemistry and Chemical engineering Hunan University 410082 Changsha China

The kinetics on the growth of *** in the presence of Cu(Ⅱ) was studied using of series piezoelectric quartz crystal (SPQC). Arsenic ion inhibits the growth of *** , which is consistent with the previous results by other measuring methods. This further demonstrates that the SPQC can monitor the chemical activity of *** growth. Cupric ion accelerates the growth of *** . The mechanism was discussed, i. e., copper promotes the protein enzyme of *** , rusticyanin, to form over the range of cupric ion concentration studied. The reaction order of cupric ion in accelerating the bacterial growth is 0.067. The growth of *** is dependent on temperature, the apparent reaction activation energy decreases from 2..56 kJ/mol to 18.32.kJ/mol because of the addition of 10 mg/L Cu(Ⅱ) to the bacterial growth solution of pH 2.0 at initial inoculum of 10%.

关键词： series piezoelectric quartz crystal T.ferrooxidans growth kinetics sigmoid curve cupric ion

Formation and evolution mechanisms of large-clusters during rapid solidification process of liquid metal Al

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science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 101-112页

作者： LIU Rangsu, DONG Kejun, LIU Fengxiang, ZHENG Caixing, LIU Hairong & LI Jiyong department of Applied Physics, hunan University,{2. College of materials science and engineering, hunan University,{2. College of Chemistry and Chemical engineering, hunan University,{2. 1. department of Applied Physics Human University 410082 Changsha China 2. College of materials science and {2. Hunan University 410082 Changsha China 3. College of Chemistry and Chemical engineering Hunan University 410082 Changsha China

A molecular dynamics simulation study has been performed for the formation and evolution characteristics of nano-clusters in a large-scale system consisting of 400000 atoms of liquid metal Al. The center-atom method combined with pair-bond analysis technique and cluster-type index method (CTIM) has been applied here to describe the structural configurations of various basic clusters. It is demonstrated that both the 1551 bond-type and the icosahedral cluster (12.0 12.0) constructed by 1551 bond-types are dominant among all the bond-types and cluster-types, respectively, in the system and play a critical role in the microstructure transitions of liquid metal Al. The nano-clusters (containing up to 150 atoms) are formed by the combination of some middle and small clusters with distinctly different sizes, through mutual competition by unceasing annex and evolution in a seesaw manner (in turn of obtaining and losing),which do not occur as the multi-shell structures accumulated with an atom as the center and the surrounding atoms are arranged according to a certain rule. This is the essential distinction of nano-cluster in liquid metal from those obtained by gaseous deposition, ionic spray methods, and so on. Though the nano-clusters differ from each other in shape and size, all of them possess protruding corners that could become the starting points of various dendrite structures in the solidification processes of liquid metals.

关键词： liquid metal, solidification process, large-cluster configuration, evolution mechanism, computer simulation.

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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science china(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2. CAI Hongnian1, ZHANG Xinming2. WANG Fuchi1 & TAN Chengwen1,3 1. School of material science and {2., Beijing Institute of Technology, Beijing 100081, china 2. School of material science and {2., Central South University, changsha 410083, china 3. School of material science and {2., Beijing University of Aeronautics and Astronautics, Beijing 100083, china 1. School of material science and {2. Beijing Institute of Technology Beijing 100081 China 2. School of material science and {2. Central South University Changsha 410083 China 3. School of material science and {2. Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112.and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

INTERVAL FINITE VOLUME METHOD FOR UNCERTAINTY SIMULATION OF TWO-DIMENSIONAL RIVER WATER QUALITY

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Journal of Hydrodynamics 2004年第4期16卷 455-463页

作者： HELi ZENGGuang-ming] HUANGGuo-he LUHong-wei departmentofEnvironmentalSystemengineering UniversityofReginaSaskatchewanS4S0A2Canada departmentofEnvironmentalscienceand{2. HunanUniversityChangsha410082China

Under the interval uncertainties, by incorporating the discretization form offinite volume method and interval algebra theory, an Interval Finite Volume Method (IF-VM) wasdeveloped to solve water quality simulation issues for two-dimensional river when lacking effectivedata of flow velocity and flow quantity. The IFVM was practically applied to a segment of theXiangjiang River because the Project of hunan Inland Waterway Multipurpose must be started workingafter the environmental impact assessment for it. The simulation results suggest that there existrather apparent pollution zones of BOD_5 downstream the Dongqiaogang discharger and that of CODdownstream Xiaoxiangjie discharger, but the pollution sources have no impact on the safety of thethree water plants located in this river segment. Although the developed IFVM is to be perfected, itis still a powerful tool under interval uncertainties for water environmental impact assessment,risk analysis, and water quality planning, etc. besides water quality simulation studied in thispaper.

关键词： interval finite volume method (IFVM) uncertainty simulation water quality

Effect of pyrolysis temperature and hold time on the characteristic parameters of adsorbent derived from sewage sludge

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Journal of Environmental sciences 2004年第4期16卷 683-686页

作者： ZHAI Yun-bo, WEI Xian-xun, ZENG Guang-ming (department of Environmental science and {2.,hunan University, changsha 410082. china. department of Environmental science and {2. Hunan University Changsha 410082 China. ybzhai@***

According to the Doehlert’s matrix method, the adsorbent derived from sewage sludge was prepared through chemical activation under controlling the pyrolysis temperature and hold time. The characteristic parameters including the total yield, adsorption of methylene blue, adsorption of iodine, BET surface area, micro-pore volume are 35%—49%, 16.5—38 mg/g, 2.5—362.mg/g, 185—359 m2.g, and 0.112.0.2.4 m3/g, respectively. According to the experimental data, the multi-linear regression method was adopted to fit the relations between the characteristic parameters and influential factors. At final, through optimization method, the optimal adsorbent is obtained when using 62.min as hold time and 1105K as pyrolysis temperature. Under the conditions, the adsorbent was produced and compared the characteristic parameters with model forecast value, the coherence is satisfied.

关键词： adsorbent sewage sludge pyrolysis temperature hold time Doehlert’s matrix

Physicochemical and microbiological effects of biosurfactant on the remediation of HOC-contaminated soil

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Progress in Natural science:materials International 2005年第7期15卷 577-585页

作者： ZENG Guangming , ZHONG Hua, HUANG Guohe and FU Haiyan ( department of Environmental science and {2., hunan University, changsha 410082. china Faculty of {2., University of Regina, Regina, Saskatoon S4S0A2. Canada) department of Environmental science and {2. Hunan University Changsha 410082 China. Faculty of engineering University of Regina Regina Saskatoon S4S0A2 Canada

Remediation of soil contaminated by hydrophobia organic compounds using biosurfactants as additives involves interactions between soil matrix, hydrophobic organic compound contaminants, biosurfactants and microorganisms. In this paper, the mechanism for biosurfactants to enhance the contaminant degradation is basically revealed. Biosurfactants can enhance solubilization of the contaminants in the soil matrix, change their mass transfer properties into the aqueous phase, as well as affect their sorption properties. Furthermore, biosurfactants can act on microorganisms and change their surface properties, accordingly cause new growth and uptake behavior of the bacteria in the soil matrix. Both the physicochemical and the microbiological effects can basically increase the bioavailability of the contaminants and enhance their degradation.

关键词： bioavailability physicochemical effects microbiological effect hydropbobic organic compounds biosurfactants.