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Science china Chemistry 2006年第6期49卷 492-498页

作者： QI Yuanhua1.2. GUAN Daren1.& LIU Chengbu1.1. Institute of Theoretical Chemistry, shandong University, {1. 2.01.0, china 2. school of Physics and Microelectronics, shandong University, {1. 2.0061. china 1. Institute of Theoretical Chemistry Shandong University Jinan 250100 China 2. school of Physics and Microelectronics Shandong University Jinan 250061 China

The density functional theory (DFT) combining with the non-equilibrium Green functions (NEGF) method is applied to the study of the electronic transport properties for a Di-thiol-benzene (DTB) molecule coupled to two Au(1.1. surfaces. The dependence of the transport properties on the bias, the coupling geometry of the molecule-electrode interface, and the intermolecular interaction are examined in detail. The results show that the existence of the hydrogen atom at the end of the DTB molecule would significantly decrease the transmission coefficients, and then the differential conductance (dI/dV). By changing the position of the DTB molecule located between two electrodes a maximum value of calculated current is observed. It is also found that the intermolecular interaction will strongly influence the transport properties of the system studied.

关键词： non-equilibrium Green functions method, transmission spectrum, the molecular projected selfconsistent Hamiltonian, projected density of state.

Mechanical model of vulnerable atherosclerotic plaque rupture

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Science china(Physics,Mechanics & Astronomy) 2004年第4期47卷 452-462页

作者： SU Haijun1. ZHANG Mei2.& ZHANG Yun2.1. {2. of Mathematics and System Science, {1. University, jinan 2.01.0, china 2. Qilu Hospital, {1. University, jinan 2.001., china 1. school of Mathematics and System Science Shandong University 250100 Jinan China 2. Qilu Hospital Shandong University 250012 Jinan China

Rupture of atherosclerotic plaque is the main trigger of acute cardiovascular events, but the mechanism of plaque rupture is still unknown. We have constructed a model describing the motion of the fibrous cap of the plaque using the theory of elastic mechanics and studied the stability of the plaque theoretically. It has shown that plaque rupture is the result of a dynamic interplay between factors intrinsic to the plaque itself and extrinsic factors. We have proposed a new mechanism of plaque rupture, given a new explanation about the nonlinear dynamic progress of atherosclerosis and suggested a method to identify the vulnerable plaques to manage atherosclerosis.

关键词： fibrous cap, parametric resonance, stability, mechanism, identification.

Prediction for RNA planar pseudoknots

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Progress in Natural Science:Materials International 2007年第6期17卷 717-724页

作者： Li Hengwu1.2. Zhu Daming1. Liu Zhendong1.and Li Hong2.1. school of Computer Science and Technology, {1. University, jinan 2.01.0, china 2. Department of Computer, {1. Economic University, jinan 2.001., china) [a]school of Computer science and Technology Shandong University Jinan China [b]Department of Computer Shandong Economic University Jinan China

Based on m-stems and semi-extensible structure, a model is presented to represent RNA planar pseudoknots, and corresponding dynamic programming algorithm is designed and implemented to predict arbitrary planar pseudoknots and simple non-planar pseudoknots with O(n4) time and O(n3) space. The algorithm folds total 2.5 sequences in the Pseudobase database, and the test results indicate that the algorithm has good accuracy, sensitivity and specificity.

关键词： algorithm RNA secondary structure pseudoknot dynamic programming.

Ground state and polaron and bipolaron excited states in polydiacetylene

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Science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 430-439页

作者： LI Yuan1. HU Guichao1. XIA Caijuan1. LIU Desheng1.2.& XIE Shijie1.2.1. school of Physics and Microelectronics, {1. University, jinan 2.01.0, china 2. National Key Laboratory of Crystal Materials, {1. University, jinan 2.01.0, china 1. school of Physics and Microelectronics Shandong University Jinan 250100 China 2. National Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

The electronic properties of ground state and charged excited states of nondegenerate polydiacetylene were investigated by means of a tight-binding model. The parameters of the model were obtained by comparison of the experimental and other theoretical results. It was found that there is a stable dimerized structure of polydiacetylene in ground state and the doping induces the nonlinear excitations, such as polarons and bipolarons. In order to compare the stability of polaron and bipolaron, the creation energy and binding energy were separately defined. By neglecting the electron-electron Coulomb interaction, a bipolaron is more stable than two independent polarons.

关键词： dimerization, polaron, bipolaron, binding energy.

Study on the cluster of floating dross before nucleating during hot-dipping process

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Science china Chemistry 2005年第1期48卷 83-88页

作者： WEI Yunhe1. ZHANG Changqiao1. QIN Jingyu2.& LIU Chengbu1.1. school of Chemistry and Chemical Engineering, {1. University, jinan 2.01.0, china 2. The Key Laboratory of Liquid Structure and Heredity of Materials of Ministry of Education, {1. University, jinan 2.0061. china 1. school of Chemistry and Chemical Engineering Shandong University 250100 Jinan China 2. The Key Laboratory of Liquid Structure and Heredity of Materials of Ministry of Education Shandong University 250061 Jinan China

During hot-dipping in molten Zn-55Al, the forming of “floating” dross is closely re- lated with the interaction between the Al and the Fe atoms. Utilizing the thita-thita X-ray diffraction and the Percus-Yevick hard sphere model, this paper investigates the structure of molten Al3Fe that is an approximant of partial melt in practical Zn-55Al alloy melt. It is found that in the melt there exist clusters that resemble the structure of intermetallic compound Al3Fe. The strong in- teraction between Al and Fe atoms is also indicated by the deficiency of the coordination number from 1. and the shrinkage of averaged atomic diameter. Based on such information, it is specu- lated that in the molten Zn-55Al, with the accumulation of Fe, Al3Fe-like clusters form with priority, then grow into dross. On the other hand, after deflating of the effective hard sphere diameter of pure Al atom and enlarging that of the pure Fe atom, the modified model can achieve reasonable fit to the experimental structure factor. Hard sphere modeling also gave a good estimation of the mass density 3.65 g/cm3 of liquid Al3Fe alloy at 1.50℃. Compared with the density of 3.7 g/cm3 of Zn-55Al, the reason for dross floating is satisfactorily understood.

关键词： hot-dipping, dross, Al3Fe alloy, molten structure, P-Y model.

The influence of laser pulse on the photoabsorption spectra of Li atom in strong external field

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Science china(Physics,Mechanics & Astronomy) 2006年第2期49卷 178-186页

作者： WANG Dehua1.& LIN Shenglu2.1. {2. of Physics and Electronic Engineering, Yantai Normal University, Yantai 2.402.,{1. 2. Department of Physics, shandong Normal University, jinan 2.001.,{1. 1. school of Physics and Electronic Engineering Yantai Normal University Yantai 264025 China 2. Department of Physics Shandong Normal University Jinan 250014 China

Using the time-dependent perturbation theory and the calculation formula of the single- and double-pulse absorption spectra of the atom in strong external fields, we calculate the single- and double-pulse absorption spectra of Li atom in strong magnetic field for different pulse widths. The results show that a pulse of some width can reduce the contribution of the short period closed orbits and eliminate the contribution of the long period orbits. Compared with the single-pulse absorption spectra, we found that for some phase differences, the double-pulse laser absorption spectra are strengthened; while for others, they are reduced. Therefore, we can use the pulse laser to control the oscillation of the absorption spectra and obtain the optimization object.

关键词： laser pulse closed orbit absorption spectra.

Diffusion and Oxidation Wear of PCBN Tool based on Thermodynamics

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Journal of Wuhan University of Technology(Materials Science) 2010年第2期25卷 265-271页

作者：邵芳 Binzhou Vacational College school of Mechanical Engineering Shandong University

The rules of diffusion wear and oxidation wear for PCBN cutting tools were analyzed based on thermodynamics theory. Dissolution concentrations in typical normal workpice materials of PCBN tool material at different temperature were then calculated. Diffusion reaction rules in high temperature were developed and analyzed using the Gibbs free energy criterion. The machining tests were conducted using the PCBN tools at different cutting speeds of 50, 95,1.0 and 1.0 m/min, feed of 0.1. 0.2.and depth of cut of 0.1. 0.8, 1. and 1.5 mm respectively on a PUMA300LM numerically-controlled lathe. It was found that the theoretical results were uniform with the experimental data, and the results will provide useful references for tool material design and selection.

关键词： thermodynamics PCBN tool diffusion wear oxidation wear

Synthesis and structural characterization of Zn_3N_2.powder

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Science china(Physics,Mechanics & Astronomy) 2005年第2期48卷 201-210页

作者： ZONG Fujian1. MA Honglei1. XUE Chengshan2. ZHUANG Huizhao2. ZHANG Xijian1. MA Jin1. JI Feng1.& XIAO Hongdi1.1. school of Physics and Microelectronics, {1. University, jinan 2.01.0, china 2. Institute of Semiconductor, {1. Normal University, jinan 2.001., china school of Physics and Microelectronics Shandong University Jinan 250100 China Institute of Semiconductor Shandong Normal University Jinan 250014 China

Zinc nitride (Zn3N2. powder has been synthesized through the nitridation reaction of Zn powder with NH3 gas (at the flow rate of 500 ml/min) at the nitridation temperature of 600℃ for 1.0 min. X-ray diffraction (XRD) indicates that Zn3N2.is cubic in structure with the lattice constant being a = 0.9788 nm. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that Zn3N2.powder has surface morphology of various types. X-ray photoelectron spectroscopy (XPS) shows the differences in chemical bonding states between Zn3N2.and ZnO, and confirms the formation of N–Zn bonds. Observation through high resolution transmission electron microscopy (HRTEM) also indicates that the computer simulation of the structure of Zn3N2.is consistent with the structural model put forward by Partin.

关键词： nitridation, Zn3N2 powder, structure, XRD, SEM, TEM, HRTEM, XPS.

Adaptive bidirectional diffusion for image restoration

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Science china(Information Sciences) 2010年第12期53卷 2452-2460页

作者： FU ShuJun 1.2.& ZHANG CaiMing 1.1.school of Computer Science and Technology, {1. University, jinan 2.01.1. china 2.school of Mathematics, {1. University, jinan 2.01.0, china 1. school of Computer Science and Technology Shandong University Jinan 250101 China2. School of Mathematics Shandong University Jinan 250100 China

A large number of applications in image processing and computer vision depend on image quality. In this paper, combining the forward diffusion with the backward diffusion by different weights, we present an adaptive bidirectional diffusion method for image denoising and deblurring simultaneously. Further, we introduce a gradient factor into the data fidelity term, which forms a spatially varying constraint and allows a better restoration of image edges and fine details. In order to obtain a stable solution, we develop a numerically stable scheme and give its theoretical analysis. Finally, we show advantages of this method in deblurring edges, denoising and restoring fine details of image compared with other related methods in experiments.

关键词： image restoration bidirectional diffusion inverse diffusion anisotropic diffusion stabilizing scheme spatially varying constraint

Electronic structure and magnetic properties of metastable SmCo_(7) compound

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Science china(Physics,Mechanics & Astronomy) 2005年第3期48卷 325-335页

作者： ZHANG Changwen 1., LI Hua 1., DONG Jianmin 1., WANG Yongjuan 1., PAN Fengchun 1., ZHANG Jian 1., GUO Yongquan 2.& LI Wei 2.1. school of Physics and Microelectronics, {1. University, jinan 2.01.0, china 2. Institute of Functional Materials, Central Iron and Steel Research Institute, Beijing 1.0081. china 1. school of Physics and Microelectronics Shandong University 250100 Jinan China 2. Institute of Functional Materials Central Iron and Steel Research Institutes 100081 Beijing China

The electronic density of states, spin-splittings and atomic magnetic moments of SmCo 7 compound have been studied using spin-polarized MS-Xα method. The results show that a few of electrons are transferred to Sm(5d 0 ) orbital because of orbital hybridization between Sm and Co atoms in the compound. The exchange interactions between 3d and 5d electrons lead to the magnetic coupling between Sm and Co, and therefore, result in the long-range ferromagnetic order inside the SmCo 7 compound. There are negative exchange couplings occurring at some levels, which weakens the strength of average coupling around Co lattice. So, the Curie temperature and Co-moment of SmCo 7 decrease distinctly compared with pure Co. Compared with SmCo 5 compound, the disordered substitution of Co-Co “dumbbell-atom” pairs for Sm changes the local environment of Co lattice, which makes the 2. site bear negative magnetic moment. The strength of hybridization near Fermi level weakens and the free energy of the compound increases obviously. Thus, SmCo 7 is a metastable compound at room temperature. Considering the localization of 4f electrons and a few of 5d electrons arising from the orbital hybridization, the magnetic moment of Sm atom will be 1.61. B in SmCo 7 compound, which is in agreement with the experimental values of Sm 3+ ion- moment and Sm atom-moment in metals.

关键词： electronic structure, spin polarization, atomic magnetic moment, exchange coupling, Curie temperature.