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The mathematical model of wetting angle of heterogeneous nucleation

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science china(Technological sciences) 2004年第4期47卷 391-397页

作者： HUANG Cheng1, SONG Bo1, MAO Jinghong2.& ZHAO Pei3.1. School of Metallurgical and Ecological Engineering, university of {2. and technology Beijing, Beijing 100083.{3. 2. School of Material {2., university of {2. and technology Beijing, Beijing 100083.{3. 3. Central Iron and Steel Research Institute, Beijing 100081,{3. 1. School of Metallurgical and Ecological Engineering University of Science and Technology Beijing 100083 Beijing China 2. School of Material science University of Science and Technology Beijing 100083 Beijing China 3. Central Iron and Steel Research Institute 100081 Beijing China

The heterogeneous nucleation has been analyzed in terms of the thermodynamic theory, and the mathematical model of wetting angle of heterogeneous nucleation has been developed based on the dynamic requirements of hetero- and homogeneous nucleation. With the wetting angel model, the wetting angles of different catalysts in liquid iron have been calculated. The result shows that the wetting angle of most catalysts is smaller than 40, and the value of f() is far less than 1. The wetting angles of TiN, TiC and RE2.3.are smaller, while the wetting angle of MnO is bigger among the ordinary nucleation catalysts. The wetting angles calculated by this model are in agreement with the results of other research work.

关键词： heterogeneous nucleation, mathematical model, wetting angle, undercooling.

Formation and Characterization of Bone-like Nanoscale Hydroxyapatite in Glass Bone Cement

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Journal of Materials science & technology 2004年第6期20卷 772-774页

作者： Qiang FU, Nai ZHOU, Wenhai HUANG, Deping WANG and Liying ZHANGSchool of Materials science and Engineering, tongji university,{2.,{3. Sch. of Mat. Sci. and Eng. Tongji Univ. Shanghai 200092 China

Glass based bone cement (GBC) was synthesized by mixing CaO-SiO2.P2.5 based glass powder with ammonium phosphate liquid medium. Bone-like hydroxyapatite (HAP, Ca10(PO4)6(OH)2. was found to form after GBC was immersed in simulated body fluid (SBF). HAP crystal grew with an increasing time along c axle and reached about 2.0 nm in length after 3. days, however, the end plane granularity remained 3.-50 nm. The chemical composition, crystal structure and morphology of HAP formed from GBC were proved to have great resemblance with living HAP. It is believed that GBC was a desirabie biomedicai material with high bioactivity. Furthermore, the high compressive strength guaranteed the possibility of GBC in clinical application.

关键词： Bioactivity Bone cement Hydroxyapatite Microstructure

Paleoceanographic evolution recorded in the northern South china Sea since 4 Ma

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science china Earth sciences 2005年第12期48卷 2166-2173页

作者： HUANG Baoqi1,2. JIAN Zhimin2.& WANG Pinxian2.1. School of Earth and Space sciences, Peking university, Beijing 100871,{2. 2. Laboratory of Marine Geology,{3., shanghai 200092,{2. 1. School of Earth and Space sciences Peking University 100871 Beijing China 2. Laboratory of Marine Geology Tongji University 200092 Shanghai China

Upper water structure over the last 4 million years in the northern South china Sea (SCS) was reconstructed by sea surface temperature (SST) and primary productivity estimated by changes in the abundance of planktonic foraminifer, planktonic foraminifer transfer function, and the accumulation rate of benthic foraminifera. Results of SST and primary productivity show that SST gradually decreased since 4 Ma, but differential seasonal temperature and primary productivity increased in steps mainly at about 3.1, 2.7, 2.1, 1.6, 0.9 and 0.5 Ma. Comparison with tectonics and orbital variations indicates that phased rising of the Tibet since 3.6 Ma, closing of Panama and Indonesian seaways, and orbital changes were responsible for the changes of upper water structure in the SCS, respectively.

关键词： northern South china Sea, upper water structure, Late Pliocene, planktonic foraminifer, ODP 1146.

A multi-layer model for early diagenesis

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Chinese science Bulletin 1997年第16期42卷 1385-1387页

作者： MEI HongmingDepartment of Marine Geology, tongji university, shanghai 200092,{2. Department of Marine Geology Tongji University Shanghai China

EARLY diagenesis is defined here as a series of physical, chemical and biological reactions operating between depositional particles, porewaters and environmental water medium in the processes of deposition and shallow burial. Early diagenesis can produce geochemical succession within deposits, which can be divided from top to bottom into oxidation zone (OX), sulphate reduction zone (SR) and methanogenesis zone (ME). Part of the reaction

关键词： early diagenesis biogeochemical zone multi-layer model.

Nitrogen isotopic geochemical characteristics of crude oils in several basins of china

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science china Earth sciences 2005年第8期48卷 1211-1219页

作者： CHEN Chuanping1,2. MEI Bowen1 & CAO Yacheng3.1. Jianghan Petroleum university, Jingzhou 43.100, china 2. Huazhong university of {3. and technology, Wuhan 43.047, china 3. Nanjing Institute of Soil {3., Chinese Academy of {3.s, Nanjing 2.0008, china 1. Jianghan Petroleum university 434100 Jingzhou China 2. Huazhong university of science and {2. 430047 Wuhan China 3. Nanjing Institute of Soil science Chinese Academy of Sciences 210008 Nanjing China

Nitrogen isotopic ratios of crude oils with different physical and chemical properties in several basins of china have been measured and their geochemistry has been studied ele-mentally combined with molecular organic geochemistry methods. The data indicate that δ 15N is in the range of ?6‰-2.‰. They vary with the oils in different sedimentary types of basins. The oils forming in the limnic environment have lower δ 15N with the value of about 1‰-5‰ whereas the oils in saline or semi-saline environment have higher δ 15N, with most samples being above 10‰ and some exceeding 17‰. The average nitrogen isotopic ratio of oils from the Ordovician formation in the Tarim Basin is the lowest, with most samples having δ 15N below zero, which reflects possibly the characteristic of the oils originating mainly from the organic matter formed in marine carbonate sedimentary environment. The δ 15N distribution can be altered by fractionation. It increases obviously because of biodegradation and decreases during hydrocarbon migration. However, the effect of nitrogen isotopic fractionation in the short distance migration is uncon-spicuous.

关键词： nitrogen isotope, crude oil, sedimentary environment, isotopic fractionation, china.

A computer simulation of nucleation and growth of thin films

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science china(Physics,Mechanics & Astronomy) 2004年第4期47卷 442-451页

作者： ZHENG Xiaoping1,ZHANG Peifeng2.HE Deyan2.LIU Jun2. MA Jiantai3.1. Key Laboratory of Opto-Electronic technology and Intelligent Control, Ministry of Education, Lanzhou Jiaotong {2., Lanzhou 73.070, china 2. School of Physical {3. and technology, Lanzhou {2., Lanzhou 73.000, china 3. School of Chemistry and Chemistry Engineering, Lanzhou {2., Lanzhou 73.000, china 1. Key Laboratory of Opto-Electronic technology and Intelligent Control Ministry of Education Lanzhou Jiaotong University 730070 Lanzhou China 2. School of Physical science and technology Lanzhou University 730000 Lanzhou China 3. School of Chemistry and Chemistry Engineering Lanzhou University 730000 Lanzhou China

A three-dimensional kinetic Monte Carlo technique has been developed for simulating the nucleation and growth of thin films. This model involves incident atom attachment, surface diffusion of the atoms on the growing surface and atom detachment from the growing surface. It takes some new effects into account, such as a significant improvement in calculation of activation energy for the atom diffusion, which renders the model more reasonable. In addition three optimum temperatures and the consistency of their dependence on deposition rate have been found out; the dependence of the surface roughness and relative density on the deposition rate has been discussed; and the approximation of freezing neighbour atoms and periodic boundary conditions has been applied.

关键词： Monte Carlo, thin film, nucleation, surface roughness, relative density.

A NUMERICAL METHOD FOR DETERMINING THE OPTIMAL EXERCISE PRICE TO AMERICAN OPTIONS

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Journal of Computational Mathematics 2003年第3期21卷 305-310页

作者： Xiong-hua Wu Xiu-juan Feng (Department of Applied Mathematics, tongji university, shanghai 200092,{2. ) Department of Applied Mathematics Tongji University 上海 800092

American options can be exercised prior to the date of expiration, the valuation of American options then constitutes a free boundary value problem. How to determine the free boundary, i.e. the optimal exercise price, is a key problem. In this paper, a nonlinear equation is given. The free boundary can be obtained by solving the nonlinear equation and the numerical results are better.

关键词： American options Free boundary Optimal exercise price Nonlinear equation.

pH-Dependent Stability of EGX, A Multi-functional Cellulase from Mollusca, Ampullaria crossean

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Acta Biochimica et Biophysica Sinica 2004年第9期36卷 603-608页

作者： Wen-Ying LI2. Ji WANG1, Yan-Hong LI1, Ming DING1, Gen-Jun XU1,3. Lan-Ying LIU2. and Fu-Kun ZHAO1,3. 1Key Laboratory of Proteomics, Institute of Biochemistry and Cell Biology, {2. Institutes for Biological sciences, the Chinese Academy of sciences,Graduate School of the Chinese Academy of sciences, {2. 2.003., china 2.ollege of life science, Jilin university, Changchun 13.02.0} china College of life science, Zhejiang university of science and technology, Hangzhou 3.0018, china Key Laboratory ofProteomics Institute of Biochemistry and Cell BiologyShanghai Institutes for Biological Sciencesthe Chinese Academy of SciencesGraduate School of the Chinese Academy of SciencesShanghai 200031China

The cellulase activity and stability of EGX, a multi-functional cellulase previously purified from the mollusca Ampullaria crossean, was systematically studied under different pH. The pH induced con- formation and stability change of EGX have been investigated by using the intrinsic fluorescence, ANS fluorescence and CD spectrum. It has been found that the conformation and activity of this cellulase were strongly dependent on the pH. EGX was stable for both the enzyme activity and the conformation from pH 5.6 to pH 7.4. As shown by intrinsic and ANS fluorescence, no red shift of emission maximum occurred and a negligible intensity change was observed at pH 5.6–7.4. The activity of EGX remained about 80% in pH 5.6–7.4 and obviously decreased out of side the pH range. Urea-induced changes in EGX at pH 5.4 and pH 8.0 were measured by intrinsic fluorescence and CD spectrum. At pH 5.4, a significantly red shift of emission maximum occurred when the concentration of urea was 5 M compared to the concentration was 3.M at pH 8.0. The α-helix at pH 5.4 was 40.51% in the absence of urea and 3..04% in the presence of 4 M urea. At pH 8.0 the α-helix was 7.2.0} in the presence of 4 M urea. The data indicated that EGX was much susceptible to urea-induced unfolding at pH 8.0 and much stable at pH 5.4. The greater pH dependent stability of EGX may allow the enzyme to adequately catalyze the hydrolysis of cellulosic materials under natural or industrial extreme conditions.

关键词： multi-functional cellulase stability Ampullaria crossean fluorescence spectroscopy pH-dependent structural change CD spectrum

Nonlinear constitutive law for ferroelectric/ferroelastic material and its finite element realization

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science china(Physics,Mechanics & Astronomy) 2007年第1期50卷 70-86页

作者： LI YaoChen Department of Aerospace Engineering and Applied Mechanics,tongji university,{2. {3.,china Department of Aerospace Engineering and Applied Mechanics Tongji UniversityShanghai 200092 China

The hysteresis phenomena of ferroelectric/ferroelastic material in polarization procedure are investigated. Some assumptions are presented based on the published experimental data. The electrical yielding criterion, mechanical yielding criterion and isotropic hardening model are established. The flow theory in incremental forms in polarization procedure is presented. The nonlinear constitutive law for electrical-mechanical coupling is proposed phenomenologically. Finally, the nonlinear constitutive law expressed in a form of matrices and vectors, which is immediately associated with finite element analysis, is formulated. In the example problem of a rectangular specimen subjected to a uniaxial electric field, the procedure from virgin state to fully polarized state is simulated. Afterward, a uniaxial compressive loading is applied to depolarizing the specimen. Results are in agreement with the experimental data.

关键词： ferroelectric/ferroelastic material constitutive law nonlinear finite element method.