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Superconductivity of small metal grains

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Science china(physics,Mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 CHEN Zhiqian2.& ZHU Shunquan1,3.1. department of physics, {2. Normal University, {2. 2.02.4, china 2. department of physics, Southwest Normal University, Chongqing 400715, china 3. department of Computer and Electric Technology, {2. Business School, {2. 2.1400, china 1. department of physics Shanghai Normal University 200234 Shanghai China 2. department of physics Southwest Normal University 400715 Chongqing China 3. department of Computer and Electric Technology Shanghai Business School 201400 Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.

Ultrafast excitation relaxation in light-harvesting complex LH2.from *** 601

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Science china Chemistry 2004年第3期47卷 192-199页

作者： GUO Lijun1,2. LIU Yuan3. LIU Weimin2. GUO Junhua1, XU Chunhe3.& QIAN Shixiong2.1. School of {3. and Information Optoelectronics, Henan University, Kaifeng 475001, china {2., fudan University, shanghai 2.043., china 3. shanghai Institute of Plant Physiology, Chinese Academy of Sciences, shanghai 2.003.0} china 1. School of physics and Information Optoelectronics Henan University 475001 Kaifeng China 2. physics department Fudan University 200433 Shanghai China 3. shanghai Institute of Plant Physiology Chinese Academy of Sciences 200032 Shanghai China

The energy relaxation and kinetic evolution of transient spectra of bacteriochloro- phylls (BChls) in light-harvesting complex LH2.from Rb. sphaeroides 601 were investigated using femtosecond pump-probe technique. Upon 783.nm excitation, the energy at B800 BChls ex-periences an intramolecular redistribution with 0.3. ps time constant before transferring to B850 BChls. With tuning the excitation wavelength, the dynamical evolution of excited BChls was clearly observed, which indicates an obvious competition between the ground state bleaching and excited state absorption (ESA) of BChls involved and an isosbestic point near 818 nm, and also demonstrates that from the lower electronic excited state of B800 BChls to the higher exci-tonic state of B850 BChls is an efficient routine for energy transfer. The excitation energy in higher excitonic states of B850 BChls relaxes rapidly to the next lowest excitonic state by inter-conversion, delocalization to adjacent molecular, populating the lowest excitonic state and the change of molecular conformation.

关键词： photosynthesis, light-harvesting complex, energy transfer, ultrafast, dynamics, purple bacteria.

CMC surfaces in the hyperbolic 3.space

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Chinese Science Bulletin 1998年第7期43卷 547-550页

作者： YU Zuhuan 1, 2.and LI Zhenqi 1, 3.1. Institute of Mathematics, fudan University, shanghai 2.043.,{2. 2. department of Mathematics,Sichuan Union University, Chengdu 610064,{2. 3. department of Mathematics, Nanchang University, Nanchang 3. nstitute of Mathemalics Fudan University Shanghai China department of Mathematics Sichuan Union University Chengdu China department of Mathematics Nanchang University Nanchang China

CMC-H surfaces satisfying H≥1 are studied. It is proved that these surfaces possess a natural representation which is a generalization of the Bryant’s result.

关键词： hyperbolic space CMC surface Weierstrass representation.

PIXE and INAA studies on ancient potteries from Guangfulin relics in shanghai

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Progress in Natural Science:Materials International 2007年第11期17卷 1348-1356页

作者： Lin Jiawei1, Cheng Huansheng1, Zhang Zhengquan1, Zhang Bin1, Feng Songlin2. Song Jian3. Gao Menghe4 and Zhu Dan1(1. Applied Ion Beam physics Laboratory, Key Laboratory of the Ministry of Education, Institute of Modern physics, {2. University, shanghai 2.043., china 2. Key Laboratory of Nuclear Analytical Techniques, Institute of High Energy physics, Beijing 10003., china 3. shanghai Museum, shanghai 2.0003. china 4. {13. of Cultural Heritage and Museology, {2. University, shanghai 2.043., china) Applied Ion Beam physics Laboratory Key Laboratory of the Ministry of Education Institute of Modern Physics Fudan University Shanghai 200433 China Key Laboratory of Nuclear Analytical Techniques Institute of High Energy Physics Beijing 100039 China shanghai Museum Shanghai 200003 China department of Cultural Heritage and Museology Fudan University Shanghai 200433 China

This paper reports the study of ancient potteries unearthed from the Guangfulin site in shanghai. From the external features of these potteries, archeologists can classify them into two different cultural types: Liangzhu culture (local culture) and a new culture which might be derived elsewhere, but they can not recognize whether they were produced in the same place. Proton induced X-ray emission (PIXE) and instrumental neutron activation analysis (INAA) were used to measure the chemical compositions of the samples and the results were analyzed using multivariate statistics. We found that the two methods can complement each other and their database can be mutually referenced in the study of ancient potteries. Experimental results show that the compositions of the potteries from the two cultural types are different, which means that the materials for ancient potteries of new culture originate from elsewhere. This supports the archaeologists’ speculation that a group of ancient people migrated to shanghai from some other places 4000 years ago.

关键词： PIXE INAA factor analysis Guangfulin ancient pottery

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 73.000,{3. 2. Nuclear physics department,{3. Institute of Atomic Energy, Beijing 102.13.{3. 3. department of Technical physics, Peking University, Beijing 100871,{3. 4. {13. Institute for Nuclear Research, {13. 2.1800,{3. 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―2.04, 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 92.h as well as the predicted “waiting point” nuclei 89Ru and 93.d 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 142.o and 12.Pm. 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.

I-V and C-V properties of TiO_2.thin film by pulsed-laser reactive deposition

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Chinese Science Bulletin 1998年第16期43卷 1344-1349页

作者： FU Zhengwen 1, ZHOU Mingfei 1, ZHANG Shengkun 2.CHEN Lianyao 2.and QIN Qizong 1 1. Laser Chemistry Institute, fudan University,{3.,{2. 2. department of physics, fudan University,{3.,{2. Laser Chemistry Institute Fudan University Shanghai China department of Pnysics Fudan University Shanghai China

TiO-2.thin films have bee deposited on p-Si(111) substrates by pulsed-laser ablation of metallic Ti target in the O-3.ambient. The current-voltage and capacitance-voltage of the Al/TiO-2.Si capacitors are measured. The results show that the dielectric constant of thin film after being annealed at 700℃ is found to be 46, and the border trap density and the interface state density at the TiO-2.p-Si interface are 1.8×10 12.cm -2.and 2.10 12.eV -1·cm -2. respectively. The conduction mechanisms of as-deposited films are also discussed.

关键词： TiO-2 dielectric properties electrical properties pulsed-laser deposition.

Local and non-local sources of airborne particulate pollution at Beijing——The ratio of Mg/Al as an element tracer for estimating the contributions of mineral aerosols from outside Beijing

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Science china Chemistry 2005年第3期48卷 253-264页

作者： HAN Lihui1, ZHUANG Guoshun1,2.3. SUN Yele1 & WANG Zifa3.1. The Center for Atmospheric Environmental Study, department of Chemistry, Beijing Normal University, Beijing 100875, china 2. Center for Atmospheric Chemistry Study, department of Environmental Science & Engineering, fudan University, shanghai 2.043., china 3. LAPC/NZC, Institute of Atmospheric physics, CAS, Beijing 10002., china 1. The Center for Atmospheric Environmental Study Department of Chemistry Beijing Normal University 100875 Beijing China 2. Center for Atmospheric Chemistry Study Department of Environmental Science & Engineering Fudan University 200433 Shanghai China 3. Institute of Atmospheric physics CAS LAPC/NZC 100029 Beijing China

A new element tracer technique has firstly been established to estimate the contri-butions of mineral aerosols from both inside and outside Beijing. The ratio of Mg/Al in aerosol is a feasible element tracer to distinguish between the sources of inside and outside Beijing. Mineral aerosol, inorganic pollution aerosol mainly as sulfate and nitrate, and organic aerosol are the major components of airborne particulates in Beijing, of which mineral aerosol accounted for 3.0}―67% of total suspended particles （TSP）, 10%―70% of fine particles （PM2.5）, and as high as 74% and 90% of TSP and PM2.5, respectively, in dust storm. The sources from outside Beijing contributed 62. （3.%―86%） of the total mineral aerosols in TSP, 69% （52.―90%） in PM10, and 76% （59%―93.） in PM2.5 in spring, and 69% （52.―83.）, 79% （52.―93.）, and 45% （7%―79%） in TSP, PM10, and PM2.5, respectively, in winter, while only2.% in summer and autumn. The sources from outside Beijing contributed as high as 97% during dust storm and were the dominant source of airborne particulates in Beijing. The contributions from outside Bei-jing in spring and winter are higher than those in summer, indicating clearly that it was related to the various meteorological factors.

关键词： mineral aerosol local sources non-local sources dust storm re-suspended dust element tracer technique.

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural Science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2. Wu Yigen3.and Guo Shengli3.1. College of Life Sciences, Zhejiang University, Hangzhou 3.0058, china 2. Imaging {3. of Tongji Hospital of Tongji University, {2. 2.0065, china 3. College of Mathematics and physics, Nanjing University of Information Science and Technology, Nanjing 2.0044, china) College of Life Sciences Zhejiang University Hangzhou 310058 China Imaging department Tongji Hospital Tongji University Shanghai 200065 China College of Mathematics and physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

Proton induced X-ray emission (PIXE) analysis of sources of porcelain body of Ru Guan and Jun Guan porcelains

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Science china(physics,Mechanics & Astronomy) 2006年第4期49卷 411-420页

作者： LI Guoxia1, ZHAO Weijuan1, LI Rongwu2. SUN Hongwei1, GUO Min1, WANG Yanfang1, LIU Hui1, ZHAO Qingyun3. SUN Xinmin3. ZHAO Wenjun3.& CHENG Huansheng4 1. Faculty of Physical Engineering, Zhengzhou University, Zhengzhou 450052. china 2. department of {2., Beijing Normal University, Beijing 100875, china 3. Institute of Cultural Relic and Archaeology of Henan Province, Zhengzhou 450000, china 4. Institute of Modern {2., fudan University, shanghai 2.043., china Faculty of Physical Engineering Zhengzhou University Zhengzhou 450052 China department of physics Beijing Normal University Beijing 100875 China Institute of Cultural Relic Archaeology of Henan Province Zhengzhou 450000 China Institute of Modern physics Fudan University Shanghai 200433 China

3. samples of Ru Guan porcelain body and 50 samples of Jun Guan porcelain body (both kinds being in different body colors) were selected with the purpose of finding out the source of raw materials and their classification relationship so as to search for ways of non-destructive discrimination. Proton induced X-ray emission (PIXE) has been applied to these samples to determine their chemical elements. The data of seven major chemical elements collected from these samples were further studied through fuzzy cluster analysis. Results indicate that the origin of raw materials of Jun Guan porcelain body samples is comparatively more concentrated in certain places, while that of Ru Guan porcelain body samples is scattered about. The places of origin of raw materials of the majority of Ru Guan and Jun Guan porcelain body samples have something in common, but some differences still exist. It might be an important way for non-destructive discrimination among Ru Guan and Jun Guan porcelains by combining PIXE with fuzzy cluster analysis.

关键词： Ru Guan and Jun Guan porcelain, source of porcelain body, PIXE, fuzzy cluster analysis, non-destructive discrimination.