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Anomalous magnetotransport in LaMn_(1-x)Te_xO_3

Science china(physics,Mechanics & Astronomy) 2009年第7期52卷 987-992页

作者： TAN GuoTai1,2, CHEN ZhengHao3 & ZHANG XiaoZhong4,5 1 key laboratory of Beam technology & Materials Modification of the Ministry of Education, Institute of Low Energy nuclear physics, beijing Normal university, beijing 100875, china 2 beijing Radiation Center, beijing 100875, china 3 laboratory of Optical physics, Institute of physics, Chinese Academy of Sciences, beijing 100080, china 4 key laboratory of Advanced Materials of the Ministry of Education, Department of Materials Science and Engineering, Tsinghua university, beijing 100084, china 5 beijing National Center for Electron Microscopy, Tsinghua university, beijing 100084, china 1. key laboratory of Beam technology & Materials Modification of the Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing 100875 China 2. beijing Radiation Center Beijing 100875 China 3. laboratory of Optical physics Institute of Physics Chinese Academy of Sciences Beijing 100080 China 4. key laboratory of Advanced Materials of the Ministry of Education Department of Materials Science and Engineering Tsinghua University Beijing 100084 China 5. beijing National Center for Electron Microscopy Tsinghua University Beijing 100084 China

The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2+ and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2+, Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2+ and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2+ and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.

关键词： colossal magnetoresistance La-Te-Mn-O magnetotransport

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Collision dynamics of He@C_(60)+He@C_(60) at low energies

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Science china(physics,Mechanics & Astronomy) 2008年第7期51卷 765-772页

作者： ZHAO Qiang1,2, ZHANG FengShou1,2,3 & ZHOU HongYu1,2 1 key laboratory of Beam technology and Material Modification of Ministry of Education, Institute of Low Energy nuclear physics, beijing Normal university, beijing 100875, china 2 beijing Radiation Center, beijing 100875, china 3 Center of Theoretical nuclear physics, National laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000, china 1. key laboratory of Beam technology and Material Modification of Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing 100875 China 2. beijing Radiation Center Beijing 100875 China 3. Center of Theoretical nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou 730000 China

A semi-empirical molecular dynamics model is developed. The central collisions of C60+C60 and He@C60+He@C60 at different incident energies are investigated based on this model. It is found that the dimer structures have been produced at proper incident energies and these fullerene dimers could be formed by a self-assembly of C60 fullerene and He@C60. The He atom has a significant effect at higher incident energy and this embedded He atom can enhance the stability of the dimer structure.

关键词： C60 He@C60 collision molecular dynamics

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A novel method for evaluating and improving the 1H-MRSI glioma data quality

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Progress in Natural Science:Materials International 2005年第8期15卷 765-768页

作者： YUAN Kehong 1,2, LU Hongyu2, BAO Shanglian2*, CHEN Qiansheng1, LI Shaowu3 and DUAN Chaijie2(1. key laboratory of Pure and Applied Mathematics, school of Mathematical Sciences, beijing 100871, china 2. The Research Center for Tumor Diagnosis and Therapeutical physics & the beijing key laboratory of Medical physics and Engineering, peking university, beijing 100871, china 3. The Tian Tan Hospital, beijing 100050, china) key laboratory of Pure and Applied Mathematics School of Mathematical Sciences Beijing 100871 China. The Research Center for Tumor Diagnosis and Therapeutical physics & the beijing key laboratory of Medical physics and Engineering Peking University Beijing 100871 China. The Tian Tan Hospital Beijing 100050 China

Metabolic information obtained by proton magnetic resonance spectroscopic imaging (1H-MRSI) has been approved to be a powerful tool to identify either benign or malignant glioma, as well as to confirm the tumor level. However, 1H-MRSI data are affected by various factors, such as the thermal noise, eddy currents, susceptibility artifacts, and rigid body motion. To get accurate quantitative metabolic information, the key problem is to assess the 1H-MRSI data quality. In this paper, we introduce a new evaluating system to filter the data, and a new method, called wavelet denoising method, to improve the data quality under the evaluating system. Experimental results on 1H-MRSI glioma data demonstrate that preprocessing is prerequisite and the proposed algorithm with evaluating system is effective.

关键词： 1H-MRSI evaluating system glioma data quality wavelet denoising

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Study of the structure of borromean nucleus 17Ne

Study of the structure of borromean nucleus 17Ne

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第十三届全国核结构研讨会暨第九次全国“核结构与量子力学”专题讨论会

作者： WANG Enhong (school of physics and state key laboratory of nuclear physics and technology,peking university,beijing 100871,china)

In the present research,we used the Ne beam with 30.8 MeV/u to bombard the 43mg/cm C target and measured angular correlations between the fragment and emitted *** the breakup reaction of Ne,one-proton knockout will result in an unstable nucleus F,which will further decay by the proton *** measured angular correlation between the momenta of F and its decay products has been compared with the theoretical calculations and indicate that the valuence proton in Ne has the most probility to situate in the S orbital with a small admixture of the d *** present reaults suggest that Ne has halo structure.

关键词： 17Ne two proton halo angular correlation break-up reaction

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Analysis of junction temperatures in high-power GaN-based LEDs

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Science china(Technological Sciences) 2010年第2期53卷 297-300页

作者： JIANG YuXuan1, LI Zheng1, SUN YongJian1, YU TongJun1, CHEN ZhiZhong1, ZHANG GuoYi1, ZHANG GuangChen2 & FENG ShiWei2 1 state key laboratory of Artificial Microstructure and Mesoscopic physics, school of physics, peking university, beijing 100871, china 2 school of Electronic Information & Control Engineering, beijing university of technology, beijing 100124, china 1. state key laboratory of Artificial Microstructure and Mesoscopic physics School of Physics Peking University Beijing 100871 China2. School of Electronic Information & Control Engineering Beijing University of Technology Beijing 100124 China

We presented the analysis of the incomplete conduction in bonding medium in high power GaN-based light-emitting diode (LED) packages. A numerical study was carried out with parametric model to understand the junction temperature variation due to bonding medium defects. Transient thermal measurement was performed to evaluate LED’s junction temperature. Thermal resistance from chip to lead frame was 20 K/W in our sample LED. It was suggested that only 60% of the surface area of the bonding medium was involved in the thermal conduction. This result was also supported by the SEM image. Blocking of thermal path induced by ineffective area of the bonding medium was regarded as a factor of its thermal resistance. Thus, the effective area of the bonding medium should be included in the FEM model and considered as another important factor in high power LED’s thermal management.

关键词： junction temperature bonding medium FEM simulation effective area

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β-delayed proton decays near the proton drip line

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Science china(physics,Mechanics & Astronomy) 2005年第3期48卷 257-267页

作者： XU Shuwei 1 , LI Zhankui 1 , XIE Yuanxiang 1 , HUANG Wenxue 1 , SHU Nengchuan 2 , CHEN Yongshou 2 , XU Furong 3 , WANG Kun 4 , PAN Qiangyan 1 , WANG Xudong 1 , YU Yong 1 & XING Yebing 1 1. Institute of Modern physics, Chinese Academy of Sciences, Lanzhou 730000, china 2. nuclear physics Department, china Institute of Atomic Energy, beijing 102413, china 3. Department of Technical physics, peking university, beijing 100871, china 4. Shanghai Institute for nuclear Research, Shanghai 201800, china 1. Institute of Modern physics Chinese Academy of Sciences 730000 Lanzhou China 2. nuclear physics Department China Institute of Atomic Energy 102413 Beijing China 3. Department of Technical physics Peking University 100871 Beijing China 4. Shanghai Institute for nuclear Research 201800 Shanghai China

We briefly reviewed the experimental study on a-delayed proton decays near the proton drip line published by our group during the period of 1996―2004, namely the first observation of the a-delayed proton decays of 9 new nuclides in the rare-earth region and the new measurements of a-delayed proton decays of 5 nuclides in the mass ～90 region near the N = Z line with the aid of the “p-?” coincidence in combination with a He-jet tape transport system. In the meantime some important experimental technique details were supplemented. The experimental results, including the half -lives, spins, parities, deformations and production reaction cross sections for the 14 nuclei were summarized and compared with the current nuclear-model predictions, and then the following points were represented. (1) The experimental half-lives for 85Mo and 92Rh as well as the predicted “waiting point” nuclei 89Ru and 93Pd are 5―10 times longer than the theoretical predictions given by M?ller et al. using a macroscopic-microscopic model. It considerably influences the predictions of the abundances of the nuclides produced in the rp-process. (2) The current-model predictions are not consistent with the experimental assignments of the spins and parities for the proton drip-line nuclei 142Ho and 128Pm. However, the nuclear potential energy surface (PES) calculated by using a Woods- Saxon-Strutinsky method reproduced the experimental results. (3) The Alice code overestimated the production reaction cross sections of the studied 9 rare-earth nuclei by one order of magnitude or two, while HIVAP code overestimated them by one order of magnitude approximately.

关键词： proton drip line, β-delayed proton decay, He-jet tape transport system, "p-γ" coincidence, spin, parity, deformation, production reaction cross section.

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STUDY OF Ag DIFFUSION INTO Cu SINGLE CRYSTALS BY RUTHERFORD BACKSCATTERING SPECTROMETRY

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Acta Metallurgica Sinica(English Letters) 2003年第5期16卷 332-334页

作者： R.Wang 1) key laboratory of Beam technology and Materials Modification, Ministry of Education, beijing 100875, china2) Institute of Low Energy nuclear physics, beijing Normal university, beijing 100875, china3) beijing Radiation Center, beijing 100875, china key laboratory of Beam technology and Materials Modification Ministry of Education Beijing 100875China Institute of Low Energy nuclear physics Beijing Normal University Beijing 100875 China beijing Radiation Center Beijing 100875 China

4.0Me V 7Li++ RBS was used for investigations of thermal diffusion of Ag in Cu single crystals. The annealing of samples was carried out in vacuum in the temperature range from 498K to 613K. The element depth concentration profiles transformed from RBS spectra indicate that the diffusion of Ag into Cu is a typical volume diffusion. The Arrhenius parameters corresponding to the diffusion were obtained.

关键词： Ag diffusion single crystal

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Structure and optical properties of the Ge and Sn quantum-dots

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nuclear Science and Techniques 2000年第2期11卷 119-123页

作者： HAN Zhao-Hui ZHAO Zi-Qiang(Institute of Heavy Ion physics, Technical physics Depariment, peking university,beijing 100871) 北京大学北京 100871

Embedded cluster samples Ge:CaF2 and Sn:CaF2 with different sizes less than 8nm were produced and their optical properties were *** diffraction reveals that the clusters’ structures are crystallites and compared with the bulk Germanium and Stannum, lattice constants expand about 4.7% in the case of Ge:CaF2 and 5.2% of Sn:CaF2. Optical absorption and photoluminescence spectra of these samples show good agreement with the Quantum-Confinement-Effect(QCE) theory. With the decreasing of the cluster’s size, the energy gap broadens and the absorption edge blueshift is observed, and the absorption edge also shifts with the changing of the fraction of Sn and Ge. The XPS results show that in the cluster state,the binding energy becomes higher.

关键词：锗微晶锡微晶半导体 X射线光电子能谱结构光学性质电子衍射氟化钙

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Fabrication of dodecagonal pyramid on nitrogen face GaN and its effect on the light extraction

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Science china(Technological Sciences) 2010年第3期53卷 769-771页

作者： QI ShengLi,CHEN ZhiZhong,SUN YongJian,FANG Hao,TAO YueBin,SANG LiWen,TIAN PengFei,DENG JunJing,ZHAO LuBing,YU TongJun,QIN ZhiXin&ZHANG GuoYi state key laboratory for Artificial Microstructure and Mesoscopic physics,school of physics,peking university,beijing 100871,china 1. state key laboratory for Artificial Microstructure and Mesoscopic physics School of Physics Peking University Beijing 100871 China

Wet etching has been widely used in defect evaluation for Ga-face GaN and surface roughness for N-face GaN dodecagonal pyramids has been fabricated on laser-lift-off N-face GaN by hot phosphor acid *** dodecagonal pyramid shows twelve facets including six{20-2-3}and six{22-4-5}*** cross-sectional TEM image,it is shown that the pyramid corresponds to the top of the edge *** with hexagonal pyramid-surface light emitting diodes(LEDs)etched by commonly used photoelectrochemical(PEC)process in KOH aqueous,the dodecagonal pyramid-surface LEDs show improved light extraction efficiency because of more facets,which effectively reduces the total internal reflection.

关键词： GaN N face wet etching H3PO4 dodecagonal pyramid light extraction

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Correlation of Behavior Changes and BOLD Signal in Alzheimer-like Rat Model

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Acta Biochimica et Biophysica Sinica 2004年第12期36卷 803-810页

作者： Zheng-Hui HU#, Xiao-Chuan WANG1#, Li-Yun LI3, Mai-Li LIU3, Rong LIU1, Zhiqun LING1, Qing TIAN1, Xiao-Wei TANG, Yi-Gen WU2*, and Jian-Zhi WANG1* Department of physics and Bio-X disciplinary laboratory, Zhejiang university, Hangzhou 310027,china 1 Department of Pathophysiology, Tongji Medical College, Huazhong university of Science and technology, Wuhan 430030, china 2Institute of High Energy physics and key laboratory of nuclear Analysis Techniques, Chinese Academy of Sciences, P.O. Box 918, beijing 100039, china 3Wuhan Institute of physics and Mathematics, state key laboratory of Magnetic Resonance and Atomic and Molecular physics, Chinese Academy of Sciences, Wuhan 430071, china Department of physics and Bio-X disciplinary laboratory Zhejiang UniversityHangzhou 310027China Department of Pathophysiology Tongji Medical College Huazhong University of Science and TechnologyWuhan 430030 China Wuhan Institute of physics and Mathematics State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Chinese Academy of SciencesWuhan 430071 China Institute of High Energy physics and key laboratory of nuclear Analysis Techniques Chinese Academy of SciencesP.O. Box 918 Beijing 100039 China

To explore a potential means for the early diagnosis of Alzheimer disease, we studied the relationship of resting T2* signal and tau hyperphosphorylation/spatial memory deficit. The rat model with tau hyperphosphorylation and spatial memory deficit was established by bilateral hippocampi injection of isoproterenol (IP). Then, the correlative alteration between resting T2* signal and spatial memory retention was assessed with blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) study and Morris Water Maze test, and Western blot was employed to confirm tau hyperphosphorylation. The analysis showed following results. (1) Tau phosphorylation at Ser396/Ser404 and Ser199/Ser202 was signifi- cantly increased in IP-injected rats as detected by PHF-1 and tau-1, respectively. (2) An AD-like spatial memory retention disturbance was induced at 24 h after isoproterenol injection. (3) A sensitivity threshold of resting T2* signal intensity, which separated the IP-treated rats from vehicle control, was obtained by applying linear regression analysis, and an estimated sensitivity statistical threshold was at 32.62. These results suggest that resting T2* signal may serve as a noninvasive quantitative marker in predicting AD-like spatial memory deficits and tau hyperphosphorylation.

关键词： Alzheimer disease (AD) functional magnetic resonance imaging (fMRI) isoproterenol (IP) Morris Water Maze diagnosis

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