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Effects of gravity on the microstructure of Zr_(41)Ti_(14)-Cu_(12.5)Ni_(10)Be_(2..5) bulk glass forming alloy

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chinese Science Bulletin 2001年第11期46卷 961-963页

作者： LI Gong, ZHAN Zaiji, WANG Limin, CAO Limin, SUN Liling, DAI Daoyang, ZHANG Jun & WANG Wenkuiinstitute of physics, Center for {2. matter physics, chinese academy of sciences, beijing 100080, china Department of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004, china institute of physics Center for Condensed Matter Physics Chinese Academy of Sciences Beijing China Department of Materials Science and Engineering Yanshan University Qinhuangdao China

The ZrTiCuNiBe alloy is melt and solidified by Bridgman unidirectional solidification on two gravity field orientations (the gravity field orientation is parallel and opposite to solidification direction). Effects of gravity on morphology and microstructure are investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD). When gravity field orientation is parallel to solidificationdirection, less needle-like primary phase is embedded in a matrix eutectic; when gravity field orientation is opposite to solidification direction, a large amount of coarser needle-like primary phases were observed.

关键词： gravity field unidirectional solidification bulk amor- phous alloy.

RecQ Helicase-catalyzed DNA Unwinding Detected by Fluorescence Resonance Energy Transfer

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Acta Biochimica et Biophysica Sinica 2005年第9期37卷 593-600页

作者： Xing-Dong ZHANG Shuo-Xing DOU Ping XIE Peng-Ye WANG Xu Guang XI Laboratory of Soft matter physics,{2. National Laboratory for condensed matter physics,institute of physics,chinese academy of sciences,{2. {12.,china Laboratoire de Biotechnologies et Pharmacologie Génétique Appliquée CNRS UMR 8113.Ecole Normale Supérieure de Cachan,61 Avenue du Président Wilson,942.5 Cachan cedex,France Laboratory of Soft matter physics Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of SciencesBeijing 100080 China Laboratoire de Biotechnologies et Pharmacologie Génétique Appliquée CNRS UMR 8113 Ecole Normale Supérieure de Cachan61 Avenue du Président Wilson 94235 Cachan cedex France

A fluorometric assay was used to study the DNA unwinding kinetics induced by Escherichiacoli RecQ *** assay was based on fluorescence resonance energy transfer and carried out onstopped-flow,in which DNA unwinding was monitored by fluorescence emission enhancement of fluoresceinresulting from helicase-catalyzed DNA *** this method,we determined the DNA unwinding rateof RecQ at different enzyme *** also studied the dependences of DNA unwinding magnitudeand rate on magnesium ion *** showed that this method could be used to determine thepolarity of DNA *** assay should greatly facilitate further study of the mechanism for RecQ-catalyzed DNA unwinding.

关键词： helicase DNA unwinding kinetics stopped-flow fluorescence resonance energy transfer (FRET)

Band gap anomaly and topological properties in lead chalcogenides

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chinese physics B 2016年第3期25卷 27-34页

作者：聂思敏许霄琰徐刚方忠 beijing National Laboratory for condensed {2. physics and Institute of Physics Chinese Academy of Sciences Beijing 1O0190 China Collaborative Innovation Center of Quantum matter Beijing 100084 China

Band gap anomaly is a well-known issue in lead chalcogenides PbX （X = S, Se, Te, Po）. Combining ab initio calculations and tight-binding （TB） method, we have studied the band evolution in PbX, and found that the band gap anomaly in PbTe is mainly related to the high on-site energy of Te 5s orbital and the large s-p hopping originated from the irregular extended distribution of Te 5s electrons. Furthermore, our calculations show that PbPo is an indirect band gap （6.5 meV） semiconductor with band inversion at L point, which clearly indicates that PbPo is a topological crystalline insulator （TCI）. The calculated mirror Chern number and surface states double confirm this conclusion.

关键词： band gap anomaly lead chalcogenides indirect band gap semiconductor topological crystallineinsulator

Fabrication and properties of the meander nanowires based on ultra-thin Nb films

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chinese physics B 2014年第8期23卷 521-526页

作者：赵璐金贻荣李洁邓辉郑东宁 beijing National Laboratory for condensed {2. physics Institute of Physics Chinese Academy of Sciences

We report the fabrication and the study of superconducting properties of ultra-thin Nb superconducting meander nanowires, which can be used as superconducting nanowire single-photon detectors （SNSPDs）. The ultra-thin （about 7- nm thick） Nb films are patterned into micro-bridges, and 100-nm wide meander nanowires by using e-beam lithography （EBL）. The average transition temperature （Tc） of the nanowires is about 4.8 K and the critical current density jc is about 2.8 × 10^6 A/cm2. Superconducting characteristics of the specimens at different applied magnetic fields up to 8 T （parallel or perpendicular to the specimen） are systematically investigated. The normalized temperature t （= T/Tc） dependences of the parallel critical field （HcⅡ） for both the micro-bridge and the meander nanowire are almost the same, following the Ginzburg and Landau （GL） formalism for ultra-thin films. However, in perpendicular field and in the vicinity of Tc （〉 0.95Tc）, the critical field Hc⊥ of the nanowire exhibits a down-turn curvature nonlinear temperature dependence while the micro-bridge displays a linear temperature dependence. The nonlinear behavior of Hc⊥ in the nanowire is believed to be due to the fact that in the vicinity of Tc the coherence length becomes larger than the line width. Additionally, the localization of carriers in the nanowire could also contribute to the nonlinear behavior. The resistive transitions could be described by the phase-slip model for quasi-one-dimensional system. Moreover, the hysteresis in I-V curve of the meander nanowires can be illustrated by a simple model of localized normal hotspot maintained by Joule heating.

关键词： Nb meander nanowire critical temperature critical field critical current

Spin-glass like behaviors in La_(1-x)Tb_xMnO_3 perovskite

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Science china(physics,Mechanics & Astronomy) 2009年第12期52卷 1893-1897页

作者： ZHANG YingTang1,2.3,WANG ChunChang2.4,LIU WeiBin1,WANG Zhong3,LU HuiBin2.& CHEN ZiYu1 1 Department of physics,beijing University of Aeronautics and Astronautics,beijing 100191 2.3} & Center for condensed matter physics,chinese academy of sciences,beijing 100190 3 School of Material Science & Engineering,Shaanxi University of Technology,Hanzhong 72.003 4 institute of Superconducting and Electronic Materials,Wollongong University,Northfield Ave,Gwynneville,NSW 2.2.,Australia Department of physics Beijing University of Aeronautics and Astronautics Beijing China institute of physics & Center for {2. matter physics Chinese Academy of Sciences Beijing China School of Material Science & Engineering Shaanxi University of Technology Hanzhong China institute of Superconducting and Electronic Materials Wollongong University Gwynneville Australia

A series of samples of La1-xTbxMnO3 (0≤x≤0.15) are prepared. The static and dynamic magnetizations of La1-xTbxMnO3 have been investigated. The results indicate that the spins with the short-range order are frozen into random direction at low enough temperatures which leads to the samples exhibiting the spin-glass like behavior. It is considered that the spin-glass like behavior originates from the competition between ferromagnetic double exchange among Mn3+ and Mn2. and antiferromagnetic superex-change among Mn3+ and Mn3+,as well as Tb3+ and Tb3+.

关键词： La1-xTbxMnO3 spin-glass-like behavior short-range order

RECOVERY OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)FILM UNIAXIALLY DRAWN JUST BELOW THE GLASS TRANSITION TEMPERATURE

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chinese Journal of Polymer Science 2000年第1期18卷 69-75页

作者： Nan-jian Sun Juan Yang De-yan Shen Ren-yuan Qian institute of Chemistry, chinese academy of sciences,{2., china 中科院化学所北京

Isothermal recovery in the macroscopic length of homogeneously deformed specimens of amorphous poly(ethylene terephthalate) (PET) film sample uniaxially drawn at 69 degrees C to the draw ratios lambda(0) = 1.2.-2.2. were studied at temperatures around the glass transition temperature (T-g = 73 degrees C). Experimental results indicate that the length recovery look place in two distinct steps: a fast first step (fast relaxation) followed by a slow second step (slow relaxation). The relaxation processes were accompanied by the reversion of trans-conformers (1340 cm(-1)) to gauche, and the dichroic function of the 1340 cm(-1) band characterizing the segmental orientation along the chain direction decreased to a very low value at the end of the fast relaxation. This fact led us to assign the fast relaxation as the segmental orientation while the slow relaxation as relaxation of the global chain orientation. It was found that the slow relaxation follows a single exponential function, with relaxation times strongly dependent on the temperature resembling the glass transition process. The fast relaxation does not follow a single exponential decay, presumably a distribution of relaxation times is involved.

关键词： poly(ethylene terephthalate) uniaxial drawing recovery orientation

THE SPHERULITE-LIKE STRUCTURE OF MAIN CHAIN THERMOTROPIC AROMATIC COPOLYESTERS

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chinese Journal of Polymer Science 1999年第3期17卷 245-251页

作者： Shou-xi Chen Hua-chun Zhai Yong-ze Jin institute of Chemistry, chinese academy of sciences,{2., china 中科院化学所北京 100080 中科院化学所北京

A new spherulite-like structure of main chain thermotropic aromatic copolyesters formed in solution cast specimens was observed and was studied by means of polarizing microscopy, X-ray diffraction, SEM and IR spectrometry. Results indicate that the spherulite-like structure of main chain thermotropic aromatic copolyesters formed from the casting solution (phenol/Cl2.H2.H2.l2. is not a real crystal but only a high oriented arrangement of the macromolecular chains as a spherulite. This resulted from the interaction between the needle-like crystal of phenol and the rigid mesomorphic groups of molecular chain. The parallel packing of extended copolyester molecules along the needle-like crystal of phenol leads to the formation of the spherulite-like structure.

关键词： spherulite-like structure thermotropic aromatic copolymer PET PHB

Relaxation of Chain Extension of Amorphous PET Fiber Above the Glass Transition Temperature

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chinese Chemical Letters 2000年第10期11卷 925-928页

作者： Xin LINGHU, Jun ZHAO, Rui SONG, Qing Rong FAN (Polymer physics Laboratory, Center of Molecular Science, institute of Chemistry,{2., beijing, 100080) Polymer physics Laboratory Center of Molecular Science Institute of Chemistry Beijing 100080 China

The recovery of amorphous PET fiber in global chain orientation but nearly random segmental orientation (GOLR) state was studied by the hot shrinkage measurement above the glass transition temperature. The relaxation curves in the form of di-exponential decay were acquired and the change of two special times with the variation of treating temperature and residual recovery ratio ' was discussed.

关键词： GOLR state PET recovery of chain extension hot shrinkage measurement.

Impurity in Pairwise Entanglement of Heisenberg XX Open Chain

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Communications in Theoretical physics 2007年第12期 1009-1016页

作者： XI Xiao-Qiang~(1,2.CHEN Wen-Xue~1 LIU Qi~3 and YUE Rui-Hong~3~1 Department of Applied Mathematics and physics,Xi’an institute of Posts and Telecommunications,Xi’an 710061,{2.~2.Joint Laboratory of Advanced Technology in Measurements,beijing National Laboratory for condensed matter physics,institute of physics,the chinese academy of sciences,beijing 100080,{2.~3 institute of Modern physics,North-West University,Xi’an 710069,{2. Department of Applied Mathematics and physics Xi'an Institute of Posts and Telecommunications Xi'an 710061 China Joint Laboratory of Advanced Technology in Measurements Beijing National Laboratory for Condensed Matter Physics Institute of Physics the Chinese Academy of Sciences Beijing 100080 China Department of Applied Mathematics and physics Xi'an Institute of Posts and Telecommunications Xi'an 710061 China institute of Modern physics North-West University Xi'an 710069 China

We calculate the concurrence of all pairwise entanglement of Heisenberg XX open chain with single systemimpurity in three-qubit and four-qubit cases,and find that the impurity parameter J_i has great effect on *** the proper parameter J_i,we can obtain the maximal pairwise entanglement of the nearestqubits and make the non-nearest qubits entangle.

关键词： system impurity pairwise entanglement Heisenberg XX chain