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Effect of electric field,stress and environment on delayed fracture of a PZT-5 ferroelectric ceramic

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science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 89-100页

作者： WANG Yi, SU Yanjing, CHU Wuyang & QIAO Lijie department of Material Physics, university of science and Technology beijing, beijing 100083, china school of Mechanic and Electric Control Engineering, beijing Jiaotong university, beijing 100044, china 1. department of Material Physics University of Science and Technology Beijing 100083 Beijing China 2. school of Mechanic and Electric Control Engineering Beijing Jiaotong University 100044 Beijing China

The combined effect of electric and mechanical loading on fracture of a PZT-5 ferroelectric ceramic in silicone oil has been investigated using a single edge notched specimen. The results show that the fracture toughness and the threshold stress intensity factor of delayed fracture in silicone oil, i.e. stress corrosion cracking, decrease linearly with the increasing applied electric field, either positive or negative. For the PZT-5 ferroelectric ceramics, delayed fracture in silicone oil under sustained positive or negative field can occur, and the threshold field for delayed fracture under sustained positive or negative field decreases linearly with applied stress intensity factor. The combined effect of electric and mechanical loading on delayed fracture in silicone oil includes fieldenhancing delayed fracture under sustained load and stress-enhancing delayed fracture in silicone oil under sustained field.

关键词： PZT-5 ferroelectric ceramics, fracture toughness, delayed fracture under sustained load, delayedfracture under sustained electric field.

Existence of entire explosive positive radial solutions of sublinear elliptic systems

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Communications in Nonlinear science and Numerical Simulation 2001年第2期6卷 88-92页

作者： Zuodong YANG and Qishao LU department of Applied Mathematics, peking university of Aeronautics and Astronautics, beijing 100083, china department of Applied Mathematics Peking University of Aeronautics and Astronautics Beijing 100083 China

In this paper, our main purpose is to establish the existence of entire explosive positive radial solutions of quasilinear elliptic systems. The main results of the present paper are new and extend the previously know... 详细信息

关键词： quasilinear elliptic system entire explosive positive solution existence

Colloidal Alumina-bonded TiB_2 Coating on Cathode Carbon Blocks in Aluminum Cells

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Rare Metals 2001年第2期20卷 101-106页

作者： Huimin Lu, Lanlan Yu, Chao Wang, Peng Sun (department of Nonferrous Metallurgy, university of science and Teclmology beijing, beijing 100083, china) Univ Sci & Technol beijing Dept Nonferrous Met Beijing 100083 Peoples R China

Self-propagating high-temperature synthesis (SHS) with reduction process was used to fabricate TiB2 powder from TiO2-B2O3-Mg system. The colloidal alumina-bonded TiB2 paste was prepared and coated on the cathode carbon blocks. Various properties of the baked paste such as the corrosive resistance, thermal expansion and wettability were tested. Experimental results showed that the colloidal alumina-bonded TiB2 coating could be well wetted by liquid aluminum; and the thermal expansion coefficient of the coated material was 5.8x10(-6) degreesC(-1) at 20-1000 degreesC, which was close to that of the traditional anthracite block cathode (4x10(-6) degreesC(-1)); the electrical resistivity was 8 mu Omega (.)m at 900 degreesC when the content of alumina in the coated material was about 9% in mass fraction. In addition, some other good results such as sodium resistance were also reported.

关键词： self-propagating high-temperature synthesis reduction process colloidal alumina-bonded TiB2 coating carbon cathode aluminum reduction cell

p38 MAPK mediates cardiovascular and behavioral responses induced by central IL-1β and footshock in conscious rats

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Acta Pharmacologica Sinica 2004年第3期25卷 12-16页

作者： Rui-mao ZHENG,Chang-jiang ZOU,Shi-gong ZHU2 department of Physiology and Pathophysiology,Health science Center,peking university,beijing 100083,china department of Physiology and Pathophysiology Health Science Center Peking University Beijing 100083 China

AIM: To investigate the roles of p38 mitogen-activated protein kinase (p38 MAPK) in the cardiovascular and behavioral responses induced by intracerebral ventricular injection (icv) of interleukin-1β (IL-1β) or footshock. METHODS: We examined the effects of p38 MAPK on mean artery blood pressure (mABP), heart rate (HR), and motor activity (MA) during central administration of IL-1β, or footshock after icv SB203580 (a specific inhibitor of the p38 MAPK) with Cardiovascular and Behavior Telemetry System in conscious SD rats. RESULTS: (1) IL-1β (icv) or footshock remarkably rise the mABP, and the maximal changes are (7.8±1.8) and (12.3±3.5) mmHg, respectively, which was abrogated by the pretreatment with p38 inhibitor SB203580 intracerebroventricularly. (2) Compared with icv saline group, the motor activity was significantly decreased in SB203580 group with maximal changes (-7.6±1.1) counts/min after footshock. CONCLUSION: p38 MAPK plays an important role in the pres- sor response induced by central administration of IL-1β or footshock and change of motor activity after footshock in conscious rats.

关键词： mitogen-activated protein kinase p38 interleukin-1 blood pressure motor activity

A quantification model for apoptosis in mouse embryos in the early stage of fetation

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science china(Life sciences) 2009年第10期52卷 922-927页

作者： WANG PengFei1, FU JianHua1, MA WanYun1, CHEN DieYan1, Lü DanYu2 & BAI WenJia3 1 Key Laboratory for Atomic and Molecular Nanosciences of Education Ministry, department of Physics, Tsinghua university, beijing 100084, china 2 department of Anatomy & Histology and Embryology, school of Basic Medical sciences peking university Health science Center, beijing 100083, china 3 department of Automation, Tsinghua university, beijing 100084, china 1. Key Laboratory for Atomic and Molecular Nanosciences of Education Ministry Department of Physics Tsinghua University Beijing 100084 China 2. department of Anatomy & Histology and Embryology School of Basic Medical Sciences Peking University Health Science Center Beijing 100083 China 3. department of Automation Tsinghua University Beijing 100084 China

Apoptosis is the most important inducement and modulator for embryos in the early stage of fetation, i.e. after the 8-cell stage, mostly the morula and blastula stage, to proceed to the stage of nonlinear development. Using a two-photon laser scanning microscopy (TPLSM) system, we obtained 3-dimensional (3D) fluorescent images of preimplantation mouse embryos. A model for quantification was established. The statistical results for the spatial location of apoptosis bodies in embryos was obtained following image processing, as well as investigation of the kinetics of apoptosis. It was found that most (70%) apoptosis occurred in the trophectoderm, and the departure between the centroid and geometric center of embryos had a step transition when embryos developed into the 32-cell stage, which was consistent with the theoretical prediction that the blastocele would induce a symmetry break of the distribution of cells in embryos.

关键词： apoptosis preimplantation mouse embryo TPLSM quantification model

Crystallization Kinetics of NiTi Films with Different Ni Contents

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Journal of Materials science & Technology 2001年第4期17卷 421-424页

作者： Xunyong JIANG, Huibin XU and Shengkai GONG department of Materials science and Engineering, beijing university of Aeronautics and Astronautics, beijing 100083, china beijing Univ Aeronaut & Astronaut Dept Mat Sci & Engn Beijing 100083 Peoples R China

Three kinds of NiTi films with different Ni contents were prepared by DC magnetron sputtering. The crystallization kinetics of amorphous films was determined by using non-isothermal single- scan techniques. The results show that the activation energy of crystallization of Ni-rich NiTi film(Ni 51.10 at. pct, Ti 48.90 at. pct) is 715 kJ/mol; while that of Ti-rich films are similar: one is 445 kJ/mol (Ni 46.74 at. pct. Ti 53.26 at. pct), the other is 418 kJ/mol (Ni 43.21 at. pct, Ti 56.7g at. pct), which i5 lower than Ni-rich film. The Avrami parameter n of different films are 0.92 and 0.74 for Ni-rich film and Ti-rich films, respectively. The difference of kinetic parameters for NiTi films with various Ni contents implies that the crystallization behaviors of these films are distinct, which is confirmed by the calculated isothermal kinetics at different temperatures. The thorough research on this phenomenon is in progress.

关键词： NiTi Crystallization Kinetics of NiTi Films with Different Ni Contents

Current Efficiency of Low Temperature Aluminum Electrolysis Studied by Neural Network

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International Journal of Minerals,Metallurgy and Materials 1999年第2期13卷 107-110页

作者： Huimin Lu Zuxian Qiu Keming Fang Fuming Wang Yanruo Hong( Metallurgy school, university of science and Technology beijing, beijing 100083, china)( department of Nonferrous Metallurgy, Northeastern university, Shenyang 110006, china) Metallurgy school University of Science and Technology Beijing Beijing 100083 China department of Nonferrous Metallurgy Northeastern University Shenyang 110006 China

A prediction model for Current Efficiency (CE) of low temperature aluminum electrolysis (LTAE) with the low molar ratioelectfolyte of Na3AIF6-AIF3 - CaF2-MgF2-LiF -Al2O3 system was investigated based on artificial neural network principles. The nonlinearmapping between CE of LATE and various electrolytic conditions was obtained from a number of experimental data and used to predictCE of LATE. The trsined neural networks possessed high precision and resulted in a good predicting effect. As a result, attificial neuralnetworks as a new cooperating and predicting technology provide a new approach to the further studies on low temperature aluminumelectrolysis.

关键词： low temperatre aluminum electrolysis current efficiency neural network prediction model low molar ratio electrolyte

A Discussion on Evolution of Microstructures and Influence Factors during Continuous Rolling of Compact Strip Production

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Journal of Materials science & Technology 2004年第3期20卷 274-278页

作者： Hongbo DONG Yonglin KANG Hao YU department of Materials Processing and Controlling, university of science and Technology beijing, beijing 100083, china Dept. of Mat. Proc. and Control Univ. of Sci. and Technol. Beijing Beijing 100083 China

The evolution of microstructures and influence factors of ultrathin hot strips of low carbon steel produced by compactstrip production (CSP) techniques were investigated. The steel blocking samples of CSP six-passes were obtained,and microstructures at the different positions of workpiece for each pass were studied. At the same time, anexplicit finite element technique was used to reveal the continuous rolling process. By combining experiment resultswith simulation analysis, the effects of plastic strain, temperature, precipitation and interval time on evolution andrefinement of crystal grains have been investigated. The results are useful for the development of high strength hotstrips.

关键词： CSP Microstructure Strain Temperature Precipitation

Nucleation of Cold Rolled FeCo Alloy during Annealing and Its Influence on the Formation of Recrystallization Texture

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Journal of Materials science & Technology 2000年第5期16卷 543-545页

作者： Guohui ZHU, Weimin MAO+ and Yongning YU (department of Metal Materials, university of science and Technology beijing, beijing 100083, china) department of Metal Materials University of Science and Technology Beijing Beijing 100083 China

The orientation distribution of recrystallization grains formed during annealing, as well as their misorientation relationship to the deformation matrix in cold rolled FeCo alloy have been investigated. It was found that most of the recrystallization nuclei were located near the boundary area with rather random orientations, and their misorientation angles to the deformation matrix were generally very high. However a few nuclei were also observed inside the deformation grains, to which they had very similar orientations. Therefore the misorientation angles between the nuclei and the deformation matrix were generally very low. The orientation and the misorientation distributions of the nuclei have very strong influence on the recrystallization process which could result in a very weak recrystallization texture. The corresponding mechanism is discussed.

关键词： In Nucleation of Cold Rolled FeCo Alloy during Annealing and Its Influence on the Formation of Recrystallization Texture