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Electronic structure and magnetism of R(Fe,Si)_(12. (R=Y,Nd)

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Science China(physics,Mechanics & Astronomy) 2006年第2期49卷 195-202页

作者： SUN Guang’ai1, CHEN Bo1, DU Honglin2. FAN Zhijian1, GAO Tao3 & QI Xinhua31. Institute of Nuclear physics and Chemistry, China Academy of engineering physics, Mianyang 62.900, China 2. department of physics, Peking university, beijing 100871, China 3. Institute of Atomic and Molecular physics, Sichuan university, Chengdu 610065, China 1. Institute of Nuclear physics and Chemistry China Academy of Engineering Physics Mianyang 621900 China 2. department of physics Peking university Beijing 100871 China 3. Institute of Atomic and Molecular physics Sichuan University Chengdu 610065 China

The newly developed full-potential linearized augmented plane wave (LAPW) and local orbitals (lo) based on standard APW methods are briefly introduced, and the structure and magnetic properties of R(Fe, Si)12.compounds (R = Y, Nd) are calculated using the method. The distribution of Si at different sites is analyzed based on total energy of one crystal unit with structure having been optimized. The characters of magnetic mo-ments, total density of states (TDOS) and partial density of states (PDOS) for different crystal sites Si occupies are obtained and analyzed. The results show that the total mag-netic moments of RFe10Si2.(R = Y, Nd) are larger than those of RFe10M2.(M = Ti, V, Cr, Mn, Mo and W) and the hybridization mechanism is seen as follows. Si(8j) reduce the mag-netic moments of Fe at three sites, however, Si(8f) mainly reduce the magnetic moments of Fe(8i) and Fe(8j) atoms. The Curie temperature is markedly enhanced by the introduc-tion of Si atoms according to spin fluctuation of DOS at Fermi level.

关键词： (L)APW+lo method R(Fe Si)12.R = Y Nd) magnetic moment Density of state.

The effect of hydrogen on the electronic structure of kink in bcc iron

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Science China(Technological Sciences) 2009年第5期52卷 1212-1218页

作者： CHEN LiQun1,QIU ZhengChen1,YU Tao2.& WANG ChongYu2.3,4 1 College of Sciences,Central South university of Forestry and Technology,Changsha 410004,China 2.Central Iron and Steel Research Institute,beijing 100081,China 3 {2. of physics,tsinghua university,beijing 100084,China 4 International center for Materials physics,Chinese Academy of Sciences,Shenyang 110016,China 1. College of Sciences Central South University of Forestry and Technology Changsha 410004 China 2. Central Iron and Steel Research Institute Beijing 100081 China 3. department of physics Tsinghua University Beijing 100084 China 4. International center for Materials physics Chinese Academy of Sciences Shenyang 110016 China

The electronic structures of kinks in the [100](010) and 1/2.111](-110) edge dislocations in bcc iron containing hydrogen are investigated by means of the first-principles DMol method and the discrete variational *** effects of hydrogen on the kinks are *** results show that hydro-gen forms weak bonding states with its neighboring host atoms,and since hydrogen draws charge from its neighboring host atoms,the interactions between most of the host atoms are weakened com-pared with those of the corresponding atomic pairs in the clean *** indicates that the migration of kink,*** motion of dislocation,is easier in the doping hydrogen kink than in the clean kink,which may be the solid solution softening effect resulting from the impurity hydrogen.

关键词： electronic structure dislocation kink impurity

Molecular dynamics simulation of kink in 〈100〉 edge dislocation in body centred cubic iron

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Chinese Science Bulletin 2007年第16期52卷 2291-2296页

作者： CHEN LiQun1,2.WANG ChongYu2.3,4 & YU Tao2.1 College of Sciences,Central South university of Forestry & Technology,Changsha 410004,China 2.Central Iron and Steel Research Institute,beijing 100081,China 3 {2. of physics,tsinghua university,beijing 100084,China 4 International center for Materials physics,Chinese Academy of Sciences,Shenyang 110016,China College of Sciences Central South University of Forestry and Technology Changsha 410004 China

Using the molecular dynamics method,we have constructed two kink models corresponding to the 〈100〉{010} and 〈100〉{011} edge dislocations (EDs) in body centred cubic (bcc) Fe. It is found that the geometric structure of a kink depends on the type of edge dislocation and the structural energies of the atoms sites in the dislocation core region. The formation energies,migration energies and widths of the kinks in different types of EDs are calculated. The results show that formation and migration of the kink in the 〈100〉{010} edge dislocation are difficult. The 〈100〉{011} edge dislocation moves primarily through kink nucleation,rather than kink migration.

关键词：分子动力学边缘位移铁纽结结构

Discovery of a high confidence soft lag from an X-ray flare of Markarian 42.

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Science China(physics,Mechanics & Astronomy) 2010年第S1期53卷 224-227页

作者： ZHANG YouHong1,HOU ZhengTian2.SHAO Li3 & ZHANG Peng1 1 department of physics and {2. center for astrophysics(THCA),tsinghua university,beijing 100084,China 2.Group of Mathematics and physics,Shangqiu Medical College,Shangqiu 476100,China 3 Max-Planck-Institut für extraterrestrische Physik,Postfach 1312.Garching 85741,Germany 1. department of physics and {2. center for astrophysics (THCA) Tsinghua University Beijing 100084 China 2. Group of Mathematics and physics Shangqiu Medical College Shangqiu 476100 China 3. Max-Planck-Institut für extraterrestrische Physik Postfach 1312 Garching 85741 Germany

We present the X-ray variability properties of the X-ray and TeV bright blazar Mrk 42. with a-60 ks long XMM-Newton observation performed on November 9-10,*** source experienced a pronounced flare,of which the inter-band time lags were determined with a very high confidence *** soft(0.6-0.8 keV) X-ray variations lagged the hard(4-10 keV) ones by 1.09+0.11-0.12.ks,and the soft lag increases with increasing difference in the photon *** energy-dependent soft lags can be well fitted with the difference of the energy-dependent cooling timescales of the relativistic electron distribution responsible for the observed X-ray emission,which constrains the magnetic field strength and Doppler factor of the emitting region to be Bδ 1/3-1.78 Gauss.

关键词： BL Lacertae objects:individual:Mrk-42. galaxies:active radiation mechanisms:non-thermal X-rays:galaxies

Interannual variability of Antarctic Oscillation and its influence on East Asian climate during boreal winter and spring

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Science China Earth Sciences 2006年第5期49卷 554-560页

作者： FAN Ke1,2.3 & WANG Huijun2.1. Nansen-Zhu International Research center, Institute of Atmospheric physics, Chinese Academy of Sciences, {2. 10002., China 2. department of Atmospheric Science, Yunnan university, Kunming 650091, China 3. Graduate university of the Chinese Academy of Sciences, {2. 100049, China 1. Nansen-Zhu International Research center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China 2. department of Atmospheric Science Yunnan University Kunming 650091 China 3. Graduate university of the Chinese Academy of Sciences Beijing 100049 China

The interannual variability of Antarctic Oscillation (AAO) and its influence on East Asian climate during both boreal winter and spring are addressed. The results show that the positive AAO anomaly decreases the cold activity over East Asia during both boreal winter and spring. AAO-related barotropic meridional teleconnection from Antarctic to Arctic is found through analysis of mean me- ridional circulations. This meridional teleconnection is remarkable over Eurasia during boreal winter and over the Pacific Ocean during boreal spring. The results also show that zonal mean zonal wind at high latitudes in Southern Hemisphere has well positive correlation with that of Eurasia during boreal winter and has negative correlation with Pacific North American teleconnection (PNA) during boreal spring, which again display the meridional teleconnection. Thus, local meridional teleconnection is a possible linkage for interaction of circulations at mid-high latitudes between both hemispheres.

关键词： Antarctic Oscillation, Eurasian west wind, meridional teleconnection, mean meridional circulation.

The size effect on transport properties of colossal magnetoresistance materials La_(0.67)Ca_(0.33)MnO_3

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Science China(physics,Mechanics & Astronomy) 2008年第3期51卷 251-257页

作者： LI PeiGang1,2.LEI Ming1,2.GUO YanFeng2.GUO Xi2.CHEN LeiMing2. TANG WeiHua1,2.SONG PengYun3 & CHEN JinPing3 1 department of physics,{2. for Optoelectronics Materials and Devices,Zhejiang Sci-Tech university,Hangzhou 310018,China 2.National Laboratory for Condensed Matter physics,Institute of physics,Chinese Academy of Sciences,beijing 100080,China 3 department of physics,Peking university,beijing 100875,China 1. department of physics Center for Optoelectronics Materials and Devices Zhejiang Sci-Tech University Hangzhou 310018 China 2. National Laboratory for Condensed Matter physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China 3. department of physics Peking University Beijing 100875 China

High quality La0.67Ca0.33MnO3 (LCMO) film was deposited via a novel pulsed electron deposition technique on SrTiO3(100) single crystal substrate. The micro-bridge with different widths was fabricated by using electron beam lithography (EBL) technique and their transport properties were studied. For the micro-bridges with width of 2.and 1.5 μm,the insulator-to-metal transition temperature (TP) keeps un-changed compared with the film. For the micro-bridges with width of 1 μm,the TP shifts towards the lower temperature by 50 K. When the width decreases down to 500 nm,the insulator-to-metal transition disappears. The magnetoresistance be-havior of these micro-bridges was studied,and the results show that the low field magnetoresistance (LFMR) decreases and the high field magnetoresistances (HFMR) keep almost unchanged as the width of micro-bridge is reduced.

关键词： colossal magnetoresistance pulsed electron deposition electron beam lithography electrical transport properties

Approaches to improving critical current density of YBCO superconducting thick films deposited by electrophoresis

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Science China(physics,Mechanics & Astronomy) 2004年第2期47卷 165-172页

作者： ZHU Yabin1,2. ZHOU Yueliang2. LIU Zhen2. WANG Shufang2. CHEN Zhenghao2. L?Huibin2. YANG Guozhen2. XIAO Ling3, REN Hongtao3, JIAO Yulei3 & ZHENG Minghui3 1. department of physics, College of Science, {2. Jiaotong university, {2. 100044, China 2. Laboratory of Optical physics, Institute of physics and center for Condensed Matter physics, Chinese Academy of Sciences, {2. 100080, China 3. General Research Institute for Nonferrous Metals, {2. 100088, China Correspondence should be addressed to Zhu Yabin (email: ybzhu@***) 1. department of physics College of Science Beijing Jiaotong University 100044 Beijing China 2. Laboratory of Optical physics Institute of physics and {2. for Condensed Matter physics Chinese Academy of Sciences 100080 Beijing China 3. General Research Institute for Nonferrous Metals 100088 Beijing China

Fabrication of YBCO superconducting thick films by electrophoresis has been widely reported. However, the value of critical current density (J c) is far from what the practical application requires. The superconducting thick films are obtained using top-seeded melt growth method with different proportional Y2.aCuO5 (Y2.1) addition. High-pressure oxygen has been used in the annealing process to improve the uniformity of the oxygen content in the superconducting thick films. When 40mol% Y2.1 powder is added to the YBa2.u3O7–5 (Y12.) powder,J c for the superconducting thick film by approaches described above reaches 7.008×103 A/cm2.(77 K, 0 T), which is greater than the value ever reported.

关键词： YBCO thick films, electrophoretic deposition, melt-textured.

Solvation effects on brain uptakes of isomers of ^(99m)Tc brain imaging agents

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Chinese Science Bulletin 2002年第21期47卷 1786-1791页

作者： JIA Hongmei, MA Xiaohui, WANG Cunxin & LIU Boli1. department of Chemistry, beijing Normal {2., beijing 100875, China 2. center for Biomedical engineering, beijing Polytechnic {2., beijing 10002., China 1. department of Chemistry Beijing Normal University Beijing 100875 China 2. center for Biomedical engineering Beijing Polytechnic University Beijing 100022 China

Analysis of electrostatic hydration free energies of the isomers of the 99mTc-BAT and 99mTc-DADT complexes is carried out using the computer simulation technique. The results show that not only a correlation exists between the logarithm of the brain uptake and the electrostatic hydration free energy for the isomers of 99mTc-brain radiopharmaceu-ticals, but also a linear relationship exists between the logarithm of the ratio of the brain uptake of the syn isomer to that of the anti one and the difference between the electrostatic hydration free energy of the syn-isomer and that of the anti one. Furthermore, the investigation on the important factors influencing the brain uptakes of 99mTc-radiophar-maceuticals and the reasons of the different biodistribution of the isomers of the 99mTc-complexes is explored at the molecular level. The results may provide a reference for the rational drug design of brain imaging agents.

关键词： 99mTc-brain imaging agent isomer brain uptake electro-static hydration free energy.

Physically-based approach to analyze rainfall-triggered landslide using hydraulic gradient as slide direction

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Journal of Zhejiang university-Science A(Applied physics & {2.) 2012年第12期13卷 943-957页

作者： Qi-hua RAN1,Dan-yang SU1,Qun QIAN1,Xu-dong FU2.Guang-qian WANG1,2.Zhi-guo HE3 (1department of Hydraulic engineering,Zhejiang {2.,Hangzhou 310058,China) (2.tate Key Laboratory of Hydroscience and engineering,tsinghua university,beijing 100084,China) (3department of Ocean Science and engineering,Zhejiang {2.,Hangzhou 310058,China) 1. department of Hydraulic engineering Zhejiang University Hangzhou 310058 China 2. State Key Laboratory of Hydroscience and engineering Tsinghua University Beijing 100084 China 3. department of Ocean Science and engineering Zhejiang University Hangzhou 310058 China

An infinite slope stability numerical model driven by the comprehensive physically-based integrated hydrology model(InHM) is *** this approach,the failure plane is assumed to be parallel to the hydraulic gradient instead of the slope *** method helps with irregularities in complex terrain since depressions and flat areas are allowed in the *** present model has been tested for two synthetic single slopes and a small catchment in the Mettman Ridge study area in Oregon,United States,to estimate the shallow landslide *** results show that the present approach can reduce the simulation error of hydrological factors caused by the rolling topography and depressions,and is capable of estimating spatial-temporal variations for landslide susceptibilities at simple slopes as well as at catchment scale,providing a valuable tool for the prediction of shallow landslides.

关键词： Shallow landslide Infinite slope stability model Hydraulic gradient Physically-based hydrology model Integrated hydrology model(InHM)