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

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 Engineering, Beijing Institute of {2., Beijing 100081, China 2. school of Material science and Engineering, Central South university, Changsha 410083, China 3. school of Material science and Engineering, Beijing university of Aeronautics and Astronautics, Beijing 100083, China 1. school of Material science and Engineering Beijing Institute of Technology Beijing 100081 China 2. school of Material science and Engineering Central South University Changsha 410083 China 3. school of Material science and Engineering 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

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Preparation of PLL-PEG-PLL and its application to DNA encapsulation

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science China Chemistry 2006年第4期49卷 357-362页

作者： YANG Zigang1, ZHOU Fen1, YUAN Jianjun1, MA Lixin2. ZHAI Chao2.& CHENG Shiyuan1 1. school of Chemistry and Materials science, Hubei {2., Wuhan 430062. China 2. school of Life science, Hubei {2., Wuhan 430062. China 1. school of Chemistry and Materials science Hubei University Wuhan 430062 China 2. school of Life science Hubei University Wuhan 430062 China

PLL-PEG-PLL was synthesized by deprotection of the amino group of PLL(Z)-PEG-PLL(Z). The properties of the polyion complex (PIC) micelles comprising of PLL-PEG-PLL and DNA were investigated. The results showed that the core of PIC was formed by PLL and DNA through electrostatic interactions, and PEG was shell of PIC, so PIC micelles in aque- ous medium were homogenous with no precipitation even under the neutral condition, and PIC had the characteristic of stability, which were very important in gene therapy. At the same time, the results showed PLL-PEG-PLL could condense DNA, longer PLL blocks were generally more effective at condensation, and the nuclease resistance of DNA was increased remarkably. PIC was spherical with diameter of 10―35 nm, which could be easily taken up by cells. Transfection experiments in vitro showed that the DNA encapsulated could be expressed in the cell line SF9.

关键词： poly(L-Lysine), poly(ethylene glycol), block copolymer, DNA, polyion complex micelles (PIC).

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Effect of Nd_2.e_(14)B/α-Fe Nanocomposite Permanent Magnets with a Combined Co and Nb Additions

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Journal of Wuhan university of technology(Materials {2.) 2009年第5期24卷 725-727页

作者：马瑞 school of Materials science and Metallurgy Engineering Guizhou University

Influence of Co＋Nb on the Nd8Fe82.o3Nb1B6 nanocomposite magnets was investigated by adding Co element combined with Nb element. Results show that the high temperature stability of two phases is increased. Adding Co＋Nb could improve the glass forming ability of the alloy, reduce the size of grains, increase the exchange coupling ability of two phases, and obviously increase the magnetic properties of the alloy. The optimal magnetic properties are Br=1.14 T, Hcj=32. kA/m, （BH）max=109.3 kJ/m^3

关键词： nanocomposite permanent magnets glass forming ability exchange coupling ability magnetic properties

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Electronic Structure of Doped Trans-Polyacetylene

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Wuhan university Journal of Natural sciences 2002年第1期7卷 51-53页

作者： Ren Da-zhi 1,2. Zhuang Wei 2. Wang Jun 2.1. Wuhan university Journals Press,Wuhan 430072.Hubei,China 2. school of Physics and {2., Wuhan university, Wuhan 430072.Hubei,China Wuhan university Journals Press Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Wuhan university School of Physics and Technology Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Wuhan university School of Physics and Technology Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

The behavior of electronic structures of doped trans-polyacetylene is revealed by a simple method. (C2.H2.)+n is used to simulate p-type doped trans-polyacetylene at various doping concentrations. The electronic structure is calculated, by CNDO/2.method. These calculations show that at low doping level, the decrease of electronic energy compensates the increase of elastic energy, thus the bond alternation exists, and the charge carriers are solitons. When doping level is high, the increase of elastic energy is larger than the decrease, of electronic energy, the bond alternation disappears, solitons no longer exist, and polyacetylene is in a metalic state.

关键词： trans polyacetylene CNDO/2 electronic structure doped

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Research progress in the inner surface modification of metal tubes by plasma processing

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Progress in Natural science:Materials International 2006年第11期16卷 1119-1126页

作者： ZHANG Guling~ 1,2.**, WU Xingfang~1, GU Weichao~2. CHEN Guangliang~2. FENG Wenran~2. NIU Erwu~2. LI Li~2. L Guohua~2. CHEN Huan~2. FAN Songhua~2. LIU Chizi~2.and YANG Size~2.1. school of Material science and Engineering, {2. of science and technology Beijing, Beijing 100083, China 2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of sciences, Beijing 100080, China) school of Material science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China

The recent progress in inner surface hardening of tubes by plasma processing is summerized. Several techniques of inner surface plasma source ion implantation and deposition are introduced, and their advantages and disadvantages are discussed. The basic principles, technical features and new progress of inner surface plasma source ion implantation methods for metal tubes, which were developed in our laboratory, are described in detail. And perspectives of the future technical development for inner surface ion implantation of tubes are presented.

关键词： PSII metal tubes inner surface surface modification.

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Mechanical Property and Microstructural Characterization of C-Mn-Al-Si Hot Dip Galvanizing TRIP Steel

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Journal of Iron and Steel Research International 2012年第8期19卷 29-36页

作者： JIANG Hai-tao1, DING Wei1,2. TANG Di1, HUANG Wei1 (1. National Engineering Research Center for Advanced Rolling technology, university of {2. and technology Beijing, Beijing 100083, China 2. school of Material and Metallurgy, Inner Mongolia university of {2. and technology, Baotou 014010, Inner Mongolia, China) [a] National Engineering Research Center for Advanced Rolling technology University of Science and Technology Beijing Beijing 100083 China [b] school of Material and Metallurgy Inner Mongolia University of Science and Technology Baotou 014010 Inner Mongolia China

Mechanical properties and microstructure in high strength hot dip galvanizing TRIP steel were investigated by optical microscope (OM), transmission electron microscope (TEM), X-ray diffraction (XRD), dilatometry and mechanical testing. On the heat treatment process of different intercritical annealing (IA) temperatures, isothermal bainitic transformation (IBT) temperatures and IBT time, this steel shows excellent mechanical properties with tensile strength over 780 MPa and elongation more than 2.%. IBT time is a crucial factor in determining the mechanical properties as it confirms the bainite transformation process, as well as the microstructure of the steel. The microstructure of the hot dip galvanizing TRIP steel consisted of ferrite, bainite, retained austenite and martensite during the short IBT time. The contents of ferrite, bainite, retained austenite and martensite with different IBT time were calculated. The results showed that when IBT time increased from 2. to 60 s, the volume of bainite increased from 14.31% to 16.95% and the volume of retained austenite increased from 13.64% to 16.2.%; meanwhile, the volume of martensite decreased from 7.18% to 1.89%. Both the transformation induced plasticity of retained austenite and the hardening of martensite are effective, especially, the latter plays a dominant role in the steel containing 7.18% martensite which shows similar strength characteristics as dual-phase steel, but a better elongation. When martensite volume decreases to 1.89%, the steel shows typical mechanical properties of TRIP, as so small amount of martensite has no obvious effect on the mechanical properties.

关键词： TRIP steel isothermal bainitic transformation martensite mechanical property

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The low-lying rotational bands of the neutron-rich nucleus ^(172.Tm

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science China(Physics,Mechanics & Astronomy) 2009年第10期52卷 1542-1547页

作者： CHEN BaoRen1,LI Tao1 & LIU ShuXin1,2.1 school of Physics,Peking university,Beijing 100871,China 2.Center of Theoretical Nuclear Physics,National Laboratory of Heavy Ion Collisions,{2. 730000,China school of Physics Peking University Beijing 100871 China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Collisions Lanzhou 730000 China

The microscopic mechanism of four experimentally observed bands in 172.m is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring *** experimental results,including the moments of inertia and angular momentum alignments of four bands in 172.m are reproduced well by the particle-number conserving *** ω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are *** unobserved low-lying bands of 2.quansiparticles in 172.m are predicted.

关键词： neutron-rich nucleus rare earth rotational band

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Three-dimensional elasticity solution of simple-supported rectangular plate on point supports, line supports and elastic foundation

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science China(Technological sciences) 2009年第3期52卷 584-589页

作者： XU YePeng1 & ZHOU Ding2.1 school of science, Nanjing {2. of science and technology, Nanjing 2.0094, China 2.College of Civil Engineering, Nanjing {2. of technology, Nanjing 2.0009, China 1. school of science Nanjing University of Science and Technology Nanjing 210094 China 2. College of Civil Engineering Nanjing University of Technology Nanjing 210009 China

This paper studies the bending of simple-supported rectangular plate on point supports, line supports and elastic foundation. On the basis of three-dimensional elasticity theory, the exact expressions of the displacement functions, which satisfy the governing differential equations and the simply supported boundary conditions at four edges of the plate, are analytically derived. The reaction forces of the in- termediate supports are regarded as the unknown external forces acting on the lower surface of the plate. The unknown coefficients are then determined by the boundary conditions on the upper and lower surfaces of the plate. Comparing the numerical results obtained from the proposed method to those obtained from Kirchhoff plate theory, Mindlin plate theory and those obtained from the commer- cial finite element software ANSYS, the high accuracy of the present method has been demonstrated.

关键词： rectangular plate point support line support elastic foundation displacement stress three-dimensional elasticity solution

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Ni60-SiC Coating Prepared by Plasma Spraying, Plasma Re-melting and Plasma Spray Welding on Surface of Hot Forging Die

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Journal of Wuhan university of technology(Materials {2.) 2011年第4期26卷 715-718页

作者：王洪福 school of Mechanical Engineering and Automation North University of China

In order to produce the hear-resistant inner layer of hot-forging die, plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2. including 10%, 2.%, 30% SiC ceramic powder used as coating material to obtain different Ni-based SiC alloys coating. Micro-structure and micro-hardness analysis of the coating layer were followed, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70% Ni60, 30% SiC powder has best properties with plasma spray welding, in which the micro-hardness can achieve 1100 HV, meanwhile can improve the thermal property of hot-forging die dramatically.

关键词： hot forging die plasma spraying plasma re-melting plasma spray welding thermo- physical properties

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Transitional function of DG to CA3 in the hippocampus

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Progress in Natural science:Materials International 2007年第12期17卷 1436-1444页

作者： Yan Chuankui1 and Liu Shenquan2.1. Department of Mathematics, Hangzhou Normal university, Hangzhou 310036, China 2. Department of Applied Mathematics, school of Mathematical {2.s, South China university of technology, Guangzhou 510640, China) Department of Mathematics Hangzhou Normal University Hangzhou 310036 China Department of Applied Mathematics School of Mathematical Sciences South China University of Technology Guangzhou 510640 China

Using single cell channel model, the transmission features of CA3-DG network in the hippocampus are investigated. The influence of the stimulation on discharge pattern of pyramidal neurons is analyzed, which shows that it starts with period spiking discharges, followed by period-doubling bifurcation to chaos, and period 3 discharge evolving into chaos, and ultimately a period of bursting discharges. By the synaptic model, the CA3-DG network model is constructed, which analyzes the summation of postsynaptic currents in the network, the influence of postsynaptic current on discharge rhythm as well as the mechanism of bursting discharges. The strong capacity of spatiotemporal encoding in the network indicates the features of CA3 network during the information transmission process in the hippocampus. The modeling result with time delay of the synaptic transmission is in accordance with the experimental phenomena of action potential in the hippocampus.

关键词： hippocampus CA3-DG period-doubling bifurcation chaos.

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