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Refractive index changes induced by sheet beams with various intensity distributions in LiNbO_(3):Fe crystal

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science{1.(Physics,Mechanics & Astronomy) 2005年第4期48卷 399-412页

作者： ZHANG peng1. {1. Jianlin1. XU Honglai1. SUN Yidong2, YANG Dexing1.& WANG Meirong1.1. Institute of Optical Information science and Technology, school of science, Northwestern Polytechnical university, Xi’an 71.072, china 2. school of science, Xi’an Jiaotong university, Xi’an 71.049, china 1. Institute of Optical Information science and Technology School of Science Northwestern Polytechnical University 710072 Xi’an China 2. school of {1. Xi’an Jiaotong University 710049 Xi’an China

According to the Kukhtarev equations and a simplified model based on the photovoltaic charge carriers transport mechanism, the distributions of the index changes (DICs) in LiNbO3:Fe crystals induced by sheet beams with various intensity profiles are theoretically analyzed. The numerically simulated results coincide with the analytic expressions deduced from the simplified model. The DICs in a LiNbO3:Fe crystal induced by sheet beams with rectangular, Gaussian and square law profiles are measured by using the interferometric method. By employing the analytic expressions, the experimental data points are well fitted. By utilizing the angular spectrum theory and the ray equation, the uniformities of the intensity profiles of the writing beams along the propagation directions and the influences of the self-defocusing effect of the crystal are numerically simulated, respectively. The results show that the experimental results are reliable. The numerically simulated method and the analytic expressions can be both employed to predict the DICs induced by sheet beams with various light intensity profiles. Furthermore, utilizing writing beams with proper intensity profiles, any desired index distributions could be obtained.

关键词： LiNbO3:Fe crystal, light intensity profile, distribution of refractive index changes, sheet beam.

Capped carbon nanotube-based molecular switch

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science Bulletin 2010年第13期55卷 1227-1230页

作者： zhao {1.1. WANG PeiJi1. ZHANG Zhong1.& liu desheng2 1.school of science, university of Jinan, Jinan 250022, china 2 school of Physics, State Key Laboratory of Crystal Materials, Shandong university, Jinan 2501.0, china school of {1. University of Jinan Jinan 250022 China school of Physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

Using the Landauer formalism that combines both the non-equilibrium Green's function (NEGF) and first-principles density functional theory (DFT), the electron transport characteristics of one-dimensional molecular switching device based on the capped carbon nanotubes have been investigated. The results show that the transmission can be efficiently tuned within two orders of magnitude just by changing 0.2 nm of the tube-tube separation. Moreover, the electron transport is insensitive to the topology of the facing conformations which can improve the practical stability of the chosen system as a molecular switch.

关键词： carbon nanotube molecular switch non-equilibrium Green function density functional theory

Novel stacking models based on SMOTE for the prediction of rockburst grades at four deep gold mines

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Underground Space 2024年第6期19卷 169-188页

作者： peng Xiao Zida {1. Guoyan zhao pengzhi Pan State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071China school of Resources and Safety Engineering Central South UniversityChangsha 410083China

Rockburst is a frequently encountered hazard during the production of deep gold *** prediction of rockburst is an important measure to prevent rockburst in gold *** study considers seven indicators to evaluate rockburst at four deep gold *** research and rock tests were performed at two gold mines in china to collect these seven indicators and rockburst *** collected database was oversampled by the synthetic minority oversampling technique(SMOTE)to balance the categories of rockburst *** models combining tree-based models and logistic regression(LR)were established by the balanced *** datasets from another two deep gold mines were implemented to verify the applicability of the predictive *** stacking model combining extremely randomized trees and LR based on SMOTE(SMOTE-ERT-LR)was the best model,and it obtained a training accuracy of 1.0%and an evaluation accuracy of 1.0%.Moreover,model evaluation suggested that SMOTE can enhance the prediction performance for weak rockburst,thereby improving the overall ***,sensitivity analysis was performed for *** results indicated that the SMOTE-ERT-LR model can achieve satisfactory performance when only depth,maximum tangential stress index,and linear elastic energy index were available.

关键词： Rockburst prediction Gold mine Stacking model SMOTE

Negative differential resistance in molecular devices: the role of molecule-electrode coupling

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science{1.(Physics,Mechanics & Astronomy) 2011年第8期Mechanics & Astronomy) .卷 1455-1460页

作者： ZHAI YaXin1, JI GuoMin1, FANG ChangFeng1, CUI Bin1, zhao peng2 & liu desheng1,3, 1.school of Physics, State Key Laboratory of Crystal Materials, Shandong university, Jinan 250100, china 2 school of science, university of Jinan, Jinan 250022, china 3 Department of Physics and Information Engineering, Jining university, Qufu 273100, china 1. school of Physics State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China2. School of Science University of Jinan Jinan 250022 China3. Department of Physics and Information Engineering Jining University Qufu 273100 China

By applying nonequilibrium Green's function formalism combined with the first-principles density functional theory, we investigate the electronic transport in two molecular junctions constituted by a substituted oligo (phenylene ehtynylene) sand-wiched between two Au electrodes. Our calculations show that the weak molecule-electrode coupling is responsible for the observation of the negative differential resistance (NDR) effect in experiments. When the coupling is weak, the projected density of states (PDOS) of the molecule and the electrodes undergoes a mismatch-match-mismatch procedure, which increases and then decreases the transmission peak intensities, leading to a NDR effect. We also find that the localization/delocalization of the molecular orbitals and the change of charge state of the molecule have no direct relation with the NDR effect, because they change little as the voltage increases.

关键词： negative differential resistance substituted oligo (phenylene ehtynylene) molecular junction density functional theory nonequilibrium Green’s function formalism

Polycistronic strategy for cyanobacterial expression vector construction: Co-transcription of a human gene and a selective marker gene

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Progress in Natural science:Materials International 2005年第9期15卷 798-803页

作者： ZHANG Yukun1. SHI Dingji2, zhao Feifei1. YU Meimin1.and RU Binggen1.1. College of Life {1., Peking university, Beijing 1.0871. china 2. College of Marine {1.s & Engineering, Tianjin university of {1. & Technology, Tianjin 300450, china) College of Life science Peking University Beijing 100871 China. College of Marine sciences & Engineering Tianjin University of Science & Technology Tianjin 300450 China

A polycistronic expression vector, pKGA-NTF1. was constructed for the cyanobacterium. Within this vector, the spectinomycin/streptomycin resistance gene (aadA) facilitated the selection of transformants when co-transcribed with favorite genes. A natural glnA gene was selected as the platform to introduce the plasmid into a neutral site of the Synechococcus sp. PCC 7002 chromosome. Function of the vector was demonstrated by the insertion of a modified human Trefoil factor 3 gene (NTF1. to upstream of the aadA gene and by the analyses of the transformed strains. Antibiotics resistance assays showed that the dicistronic expression cassette conferred high spectinomycin resistance to both the E. coli cells and the Synechococcus cells. PCR analysis and Western-blot analysis were carried out to confirm the integration and expression of the NTF1.gene, respectively. Through simple molecular manipulations, the artificial polycistronic structure described here can be conveniently used to express other favorable genes or operons in cyanobacteria, and to study the cyanobacterial gene expression as well.

关键词： cyanobacterial transformation human Trefoil factor 3 polycistronic expression Synechococcus sp. PCC 7002 vector construction.

Research on nonlinear constitutive relationship of permanent deformation in asphalt pavements

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science{1.(Physics,Mechanics & Astronomy) 2006年第6期49卷 671-682页

作者： peng Miaojuan1.& XU Zhihong2 1. Department of Civil Engineering,Shanghai {1.,Shanghai 200072,china 2. school of Transportation Engineering,Tongji {1.,Shanghai 200092,china 1. Department of Civil Engineering Shanghai University Shanghai 200072 China 2. school of Transportation Engineering Tongji University Shanghai 200092 China

To predict correctly the rut depths in asphalt pavements,a new nonlinear viscoelastic-elastoplastic constitutive model of permanent deformation in asphalt pave-ments is presented. The model combines a generalized Maxwell model with an elasto-plastic one. Then from the creep theory,the linear and nonlinear constitutive equations of the generalized Maxwell model are obtained. From the nonlinear finite element method for the rutting of the asphalt pavement,the rut depths of 4 asphalt-aggregate mixtures are obtained. And the results are compared with the ones from the finite element method by SHRP and the experiments by SWK/UN. The results in this paper are better than the ones by SHRP,and agree with the ones of the experiment by SWK/UN. This shows that the nonlinear viscoelastic-elastoplastic constitutive model,which is presented in this paper for the rutting of the asphalt pavement,is effective. The properties,such as nonlinear elastic-ity,plasticity,viscoelasticity and nonlinear viscoelasticity,which affect the rutting of an asphalt pavement,can be shown in the model. And the characteristics of the permanent deformation of the asphalt pavement can be presented entirely in the model.

关键词： asphalt pavement,permanent deformation,nonlinear viscoelastic-elastoplastic constitutive relationship,generalized Maxwell model,creep compliance.

Theoretical study on the reaction mechanism of (CH3)3CO(.) radical with NO

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science{1. Chemistry 2004年第4期47卷 289-294页

作者： zhao Hongmei1.2, {1. Kun1. SUN Chengke1.& LI Zonghe1.1. Department of Chemistry, Beijing Normal university, Beijing 1.0875, china 2. Department of Chemistry, Beihua university, Jilin 1.201., china 1. Department of Chemistry Beijing Normal University 100875 Beijing China 2. Department of Chemistry Beihua University 132013 Jilin China

The reaction mechanism of (CH3)3CO? radical with NO is theoretically investigated at the B3LYP/6-31.* level. The results show that the reaction is multi-channel in the single state and triplet state. The potential energy surfaces of reaction paths in the single state are lower than that in the triple state. The balance reaction: (CH3)3CONO(CH3)3CO?+NO, whose potential energy surface is the lowest in all the reaction paths, makes the probability of measuring (CH3)3CO? radical increase. So NO may be considered as a stabilizing reagent for the (CH3)3CO? radical.

关键词： (CH3)3CO. radical DFT reaction mechanism NO

A spatio-velocity model based semantic event detection algorithm for traffic surveillance video

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science{1.(Technological sciences) 2010年第S1期53卷 120-125页

作者： SHENG Hao 1.zhao HuiJie 1.HUANG Jian 2 & LI Na 1.{1. of Instrument science and Opto-Electro Engineering,Beihang university,Beijing 1.01.1.china 2 school of Software,Beihang university,Beijing 1.01.1.china 1. school of Instrument {1. and Opto-Electro Engineering Beijing University Beijing 100191 China 2. school of Software Beijing University Beijing 100191 China

Detection of vehicle events is a research hotspot in digital *** this paper,an approach is proposed to detect vehicle events with semantic analysis of traffic surveillance video using spatio-velocity statistic *** approach includes two successive phases:trajectory clustering and semantic events *** trajectory clustering,a statistic model of vehicle trajectories are presented,for which a spatio-velocity model is trained by analyzing the trajectories of moving vehicles in the *** on the trajectory,which represents both the position of the vehicle and its instantaneous velocity,a trajectory similarity measure is ***,an improved hierarchical clustering algorithm is adopted to cluster the trajectories according to different spatial and velocity *** each cluster,trajectories that are spatially close have similar velocities of motion and represent one type of activity *** the semantic events detection phase,statistic models of semantic regions in the scene are generated by estimating the probability density and velocity distributions of each type of activity ***,semantic events are detected by the proposed spatio-velocity statistic *** paper also presents experiments using real video sequence to verify the effectiveness of the proposed method.

关键词： trajectory clustering spatio-velocity statistic model event detection digital traffic

Fluorescence response of hypocrellin B to the environmental changes in a mimic biological membrane——liposome

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science{1. Chemistry 2004年第4期47卷 335-339页

作者： JIN Xuanye1.2, zhao Yuewei1. XIE Jie1.& zhao Jingquan1.1. CAS Key Laboratory of Photochemistry, Center for Molecular science, Institute of Chemistry, Chinese Academy of science, Beijing 1.0080, china 2. school of Earth sciences and Resources, china university of Geosciences, Beijing 1.0083, china 1. CAS Key Laboratory of Photochemistry Center for Molecular Science Institute of Chemistry Chinese Academy of Science 100080 Beijing China 2. school of Earth {1.s and Resources China University of Geosciences 100083 Beijing China

Liposome is well known as not only a drug-delivery system but also a simple model for biological membranes. It was reported that fluorescence properties of hypocrellins were changeable over some extreme pH values. In the current work, the effects of the microenvironments on the fluorescence properties of HB in liposome, including approximately physiological range of pH values pH = 6.0-8.0, concentration of cholesterols and ionic strength of the solution, were studied. It was found that the fluorescence intensity of HB was sensitive to and also regulated by the microenvironments. When concentration of cholesterols and ionic strength keep invariable in PBS solution, there exists the maximum for the fluorescence of HB-liposome at pH 7.4 while the minimum for that of HB at pH 7.0. In addition, when pH value keeps constant (7.2), there exists the maximum at the ionic strength of 0.1. mol/kg while that at the concentration of 6×1.?4 mol/L for cholesterols. On the other hand, in PBS solution, the lower the ionic strength is, the higher the fluorescence intensity is. The environment-sensitive fluorescence may be potentially applicable to probe some specific environmental features in cells or tissues.

关键词： microenvironment hypocrellin B liposome fluorescence