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Anomalous dielectric behavior in nanocrystalline γ-Fe_2O_3

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chinese Science Bulletin 1999年第2期44卷 186-189页

作者： YE Xisheng , SHA Jian , CHEN Bin , JIAO Zhengkuan ZHANG LideDepartment of physics, Zhejiang University, Hangzhou 310027, china Northwest institute of Nuclear Technology, Xi’ an 710024, china institute of Theoretical physics, chinese academy of sciences, Beijing 100080, china institute of Solid State physics, chinese academy of sciences, hefei 230031, china Department of physics Zhejiang University Hangzhou China Northwst institute of Nuclear Technology Xi’an China institute of Theoretical physics Chinese Academy of Sciences Beijing China institute of Solid State physics Chinese Academy of Sciences Hefie China

The measurements of electric capacities and dielectric loss angles for nanocrystalline yFe2O3 under air and vacuum atmospheres have been conducted by using ac LRC method, and the conductivity and the polarization relaxation time have also been calculated from the frequency spectra of real and imaginary parts of the dielectric constants. The anomalous dielectric behavior implies the existence of two kinds of polarization mechanisms with different relaxation times, which are caused by the defects and the dangling bonds in the interfaces, respectively. The experimental and calculated results indicated that the polarization loss and the conductance loss are dominant in air atmosphere and vacuum, respectively.

关键词： nanocrystalline γ-Fe2O3 dielectric behavior polarization mechanism.

Fabrication of Ni-decorated helical ribbon composite microstructure from self-assembled lipid tubule by electroless metallization

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Science china Chemistry 2006年第3期49卷 238-245页

作者： FU Yubin1,2, ZHANG Lide1 & ZHENG Jiyong2 1. institute of Solid State physics, china academy of sciences, hefei 230031, china 2. Luoyang Ship Material Research institute, Luoyang 471039, china institute of Solid State physics China Academy of Sciences Hefei China Luoyang Ship Material Research institute Luoyang China

Lipid molecules can self-assemble into a tubular structure, which is formed by tightly wound helical ribbons. Lipid tubules are utilized as a precursor to fabricate a novel Ni-decorated helical ribbon composite microstructure in a high yield by electroless deposition. The microstructure carries Ni nanoparticles on the flat face and wires at the edge of helical ribbon, in which the average size of nanoparticles is about 40―60 nm, and the wires are of a layered structure strongly correlated with a multi-bilayer structure in the lipid membrane. Compared with the tubular precursor, the Ni-decorated composite microstructure becomes short and irregular shapes due to the breakage in the deposition, and its formation is largely bound up with the tubular helical structure and the different catalytic process. Finally, the helical composite microstructure would have a potential application in the development of electric active materials.

关键词： molecular self-assembly, lipid tubule, helical ribbon, electroless deposition, nanoparticles and wires, composite microstructure.

The lepton flavor violating signal of the extra gauge boson Z′in photon-photon collision at the ILC

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1992-1997页

作者： LIU GuoLi 1,2 1 physics Department,Zhengzhou University,Zhengzhou 450001,china 2 Kavli institute for Theoretical physics china,chinese academy of sciences,Beijing 100190,china physics Department Zhengzhou University Zhengzhou China Kavli institute for Theoretical physics china Chinese Academy of Sciences Beijing China

The hitherto unconstrained lepton flavor mixings,induced by the new gauge boson Z ,which are the prediction of many new physics models,such as topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models,may lead to the lepton flavor violating productions of τμˉ,τeˉ and μeˉ in photon-photon collision at the proposed International Linear Collider (ILC).Through a comparative analysis of these processes,we find that the better channel to probe the new physics models is the production of τμˉ or τeˉ which occurs at a much higher rate than μeˉ production due to the large mixing angle and the large flavor changing coupling,and may reach the detectable level of the ILC for a large part of the parameter *** the rates predicted by the Standard Model are far below the detectable level,these processes may serve as a sensitive probe for such new physics models.

关键词： new gauge boson Z lepton flavor violating processes photon-photon

Co-genotoxic Effects of Diesel Particulate Extract and Ultraviolet A Radiation in Mammalian Cells

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生物物理学报 2009年第S1期25卷 153-154页

作者： Xu A, Bao LZ, and Wu LJ Key Laboratory of Ion Beam Bioengineering, institute of plasma physics, chinese academy of sciences, hefei, Anhui, P.R.china, 230031

Diesel exhaust (Diesel exhaust particles, DEPs, and their extracts, DPE) and ultraviolet A are two ubiquitous environmental factors that have been identified as essential risk factors

关键词： co-genotoxic effects diesel particulate extract and ultraviolet A radiation mammalian cells

Studies on BEPC upgrade from pretzel to double-ring

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 2084-2089页

作者： ZHANG Chuang institute of High Energy physics,chinese academy of sciences,Beijing 100049,china institute of High Energy physics Chinese Academy of Sciences Beijing China

physics opportunity in the charm and τ energy region calls for higher luminosity of the Beijing Electron-Positron Collider (BEPC).The BEPC has experienced continuous improvement since its completion in ***,as a major upgrading project of the BEPC,aims at enhancing its luminosity of factor 30–100,following the principle of "one machine,two purposes" as adopted in BEPC,so that both high energy physics and synchrotron radiation experiments can be carried out with *** the BEPC to BEPCII,the double-ring scheme with multi-bunch e +-e-collision in the large crossing angle was studied in comparison with the single-ring pretzel *** the dedicated synchrotron radiation operation,artful "bridges" are designed to connect two halves of the outer ring in both the southern and the northern crossing *** paper reviews the studies on the BEPC upgrade from pretzel to double-ring structure of BEPCII.

关键词： collider storage ring high energy physics synchrotron radiation

Recent Beijing Spectroscopy (BES) results

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Science china(physics,Mechanics & Astronomy) 2008年第6期51卷 567-576页

作者： LI WeiGuo institute of High Energy physics, chinese academy of sciences, Beijing 100049, china institute of High Energy physics Chinese Academy of Sciences Beijing China

Recent experimental results from Beijing Spectroscopy (BES) are reviewed, including the hadron spectroscopy from J/ψ decays, and a number of new states are found or confirmed, including σ, κ, X(1835), ωφ threshold enhancement in J/ψ→γωφ, a broad resonance in J/ψ→K + K ? π 0, decay studies of ψ(2S) and χ CJ , as well as the results of ψ(3770) non-D $ \bar D $ decays. The current status of BEPCII/BESIII, the major upgrade of BEPC/BESII, is also reported.

关键词： Beijing Spectroscopy hadron spectroscopy charm physics BEPCII

The mechanism of the effects of the upwelling mean on the ENSO event mature phase locking

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Science china Earth sciences 2007年第8期50卷 1266-1272页

作者： YAN BangLiang CMSR, institute of Atmospheric physics, chinese academy of sciences, Beijing 100029, china CMSR Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China

The mechanism of the effects of the upwelling mean on the ENSO event mature phase locking is ex-amined by using a mixed-mode model. The results show that the positive feedback process of the ef-fects of the seasonal variation of the upwelling mean on the Kelvin wave is the mechanism of the locking of the event mature phase to the end of the calendar year. The memory of the Rossby waves for the sign-shifting of the sea surface temperature anomaly from positive to negative 6 months before the cold peak time is the other mechanism of the locking of the La Nia event mature phase to the end of the calendar year. The results here are different from previous ones which suggest that the balance between cold and warm trends of sea surface temperature anomaly is the mechanism involved. The cold trend is caused by the upwelling Kelvin wave from upwelling Rossby wave reflected at the western boundary, excited by the westerly anomaly stress over the central Pacific and amplified by the seasonal variation of the coupled strength in its way propagating westward. The warm trend is caused by the Kelvin wave forced by the western wind stress over the middle and eastern equatorial Pacific. The cause of the differences is due to the opposite phase of the seasonal variation of the upwelling mean to that in the observation and an improper parameterization scheme for the effects of the seasonal varia-tion of the upwelling mean on the ENSO cycle in previous studies.

关键词： Kelvin wave Rossby wave interaction between atmosphere and sea positive feedback

Repetition Operation of Flashlamp Pumped Ti: sapphire Laser

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chinese Journal of Lasers 1996年第6期B5卷 492-496页

作者： LI Ziyao GAO Guochang YIN Shaotang (Anhui institute of Optics and Fine Mechanics,chinese academy of sciences, hefei 230031, china) Anhui Inst of Optics and Fine Mechanics Hefei China

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ＲｅｐｅｔｉｔｉｏｎＯｐｅｒａｔｉｏｎｏｆＦｌａｓｈｌａｍｐＰｕｍｐｅｄＴｉ：ｓａｐｐｈｉｒｅＬａｓｅｒ￥ＬＩＺｉｙａｏ；ＧＡＯＧｕｏｃｈａｎｇ；ＹＩＮＳｈａｏｔａｎｇ（ＡｎｈｕｉＩｎｓｔｉｔｕｔｅｏｆＯｐｔｉｃｓａｎｄＦｉｎｅＭｅｃｈａｎｉｃｓ，Ｃ...

关键词： Ti:sapphire laser flashlamp pumped repetition operation

Effects of Nitrogen Doping on Microstructures and Irradiation Resistance of Ti-Zr-Nb-V-Mo Refractory High-Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第6期37卷 1007-1018页

作者： Huanzhi Zhang Tianxin Li Qianqian Wang Zhenbo Zhu hefei Huang Yiping Lu Engineering Research Center of High Entropy Alloy Materials(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian116024China Shanghai institute of Applied physics Chinese Academy of Sciences(CAS)Shanghai201800China

Interstitial strengthening with nitrogen(N)is one of the effective ways to improve the mechanical properties of HEAs,but the effects of N on the microstructures and mechanical properties of the irradiated HEAs have not been studied ***,the microstructures and mechanical properties of N-free and N-doped Ti_(2)ZrNbV_(0.5)Mo_(0.2)HEAs before and after He irradiation were *** results showed that the solid solution strengthening caused by interstitial N improved the yield strength at room temperature and 1023 K without significantly reducing plasticity.N doping significantly promoted the growth,aggregation and wider spatial distribution of He bubbles by enhancing the mobility of He atoms/He-vacancy complexes,with the average size of He bubbles increasing from 10.4 nm in N-free HEA to 31.0 nm in N-doped *** addition,N-doped HEA showed a much higher irradiation hardness increment and hardening fraction than N-free *** to conventional materials doped with N,the introduction of N into Ti_(2)ZrNbV_(0.5)Mo_(0.2)HEA had adverse effects on its resistance to He bubble growth and irradiation *** results of this study indicated that N doping may not improve the irradiation resistance of HEAs.

关键词： High-entropy alloys Nitrogen doping Mechanical properties Helium bubbles Irradiation resistance