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DFT Study on Homolytic Dissociation Enthalpies of C-I Bonds

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Chinese Journal of Chemical Physics 2013年第5期26卷 541-548,I0003页

作者： Wen-rui Zheng Zhi-chong Chen Wu-xia xu Department of Chemistry and Chemical Engineering Shanghai University of Engineering ScienceShanghai 201620 China

The C-I bond dissociation enthalpies （BDE） of various organic iodides were calculated using high-level theoretical methods including MP2 and CCSD（T） with extrapolated basis set as well as a number of density functional theory methods. After systematic evaluation of the theoretical results against available experimental C-I BDEs, it was found that the MPW LYPIM method gave the lowest root mean square error. We, therefore, used this method to examine the substituent effects on different categories of C（sp3）-I and C（sp2）-I bonds. Fur thermore, the remote substituent effects on the C-I BDEs of substituted iodobenzenes and substituted （iodomethyl）benzenes were also investigated at the same level. The C-I BDEs of typical heteroaromatic iodides including five-membered and six-membered heterocyclic iodides were also examined.

关键词： C'I bond Bond dissociation enthalpy Density functional theory

Global Asymptotics of Orthogonal Polynomials Associated with a Generalized Freud Weight

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Chinese Annals of Mathematics,Series B 2018年第3期39卷 553-596页

作者： Zhi-Tao WEN Roderick WONG Shuai-xia xu Department of Mathematics Taiyuan University of TechnologyTaiyuan 030024China Liu Bie Ju Centre for Mathematical Sciences City University of Hong KongHong KongChina Institut Franco-Chinois de l’Energie Nucleaire Sun Yat-sen UniversityGuangzhou 510275China

In this paper, the authors consider the asymptotic behavior of the monic polynomials orthogonal with respect to the weight function w（x） = /x/2αe-（x4＋tx2）, x ∈R, where α is a constant larger than - 1/2 and t is any real number. They consider this problem in three separate cases：（i） c 〉 -2, （ii） c = -2, and （iii） c 〈 -2, where c ：= tN-1/2 is a constant, N = n ＋ a and n is the degree of the polynomial. In the first two cases, the support of the associated equilibrium measure μ is a single interval, whereas in the third case the support of μt consists of two intervals. In each case, globally uniform asymptotic expansions are obtained in several regions. These regions together cover the whole complex plane. The approach is based on a modified version of the steepest descent method for Riemann-Hilbert problems introduced by Deift and Zhou （1993）.

关键词： Orthogonal polynomials Globally uniform asymptotics Riemann-Hilbertproblems The second Painlev6 transcendent Theta function

Mitofusion 2 Overexpression Decreased Proliferation of Human Embryonic Lung Fibroblasts in Acute Respiratory Distress Syndrome through Inhibiting RAS-RAF-1-ERK1/2 Pathway

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Current Medical Science 2020年第6期40卷 1092-1098页

作者： Juan LI Mei-xia xu Zhong DAI Tao xu Department of Critical Care Medicine Wuhan Fourth Hospital(Puai Hospital)Tongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430030China

Acute respiratory distress syndrome(ARDS)is one of the most fatal diseases *** fibrosis occurs early in ARDS,and its severity plays a crucial role in ARDS mortality *** studies suggested that fibroproliferation is an essential mechanism in ***2(Mfn2)overexpression plays a role in inhibiting cell ***,the role and potential mechanism of Mfn2 on the proliferation of fibroblasts is still *** this study,we aimed at exploring the effect of Mfn2 on the human embryonic lung fibroblasts(HELF)and discussed its related *** HELF were treated with the Mfn2 overexpressing lentivirus(adv-Mfn2).The cell cycle was detected by flow ***,PCR and Western blotting were used to investigate the effect of Mfn2 on the proliferation of the HELF,collagen expression,the RAS-RAF-1-ERK1/2 pathway and the expression of cycle-related proteins(p21,p27,Rb,Raf-1,p-Raf-1,Erk1/2 and p-Erk1/2).The co-immunoprecipitation assay was used to explore the interaction between Mfn2 and *** results showed that the overexpression of Mfn2 inhibited the proliferation of the HELF and induced the cell cycle arrest at the G0/G1 ***,Mfn2 also inhibited the expression of collagen I,p-Erk and *** addition,an interaction between Mfn2 and Ras existed in the *** study suggests that the overexpression of Mfn2 can decrease the proliferation of HELF in ARDS,which was associated with the inhibition of the RAS-RAF-1-ERK1/2 *** results may offer a potential therapeutic intervention for patients with ARDS.

关键词： Mitofusion2 human embryonic lung fibroblasts acute respiratory distress syndrome RAS-RAF-1-ERK1/2 pathway

Discovering Functional Organized Keyword Recommendation Point of Interest Groups for Spatial

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Journal of Computer Science & Technology 2018年第4期33卷 697-710页

作者： Yan-xia xu Wei Chen Jia-Jie xu Zhi-xu Li Guan-Feng Liu Lei Zhao School of Computer Science and Technology Soochow University Suzhou 215006 China

A point of interest （POI） is a specific point location that someone may find useful. With the development of urban modernization, a large number of functional organized POI groups （FOPGs）, such as shopping malls, electronic malls, and snacks streets, are springing up in the city. They have a great influence on people＇s lives. We aim to discover functional organized POI groups for spatial keyword recommendation because FOPGs-based recommendation is superior to POIs-based recommendation in efficiency and flexibility. To discover FOPGs, we design clustering algorithms to obtain organized POI groups （OPGs） and utilize OPGs-LDA （Latent Dirichlet Allocation） model to reveal functions of OPGs for further recommendation. To the best of our knowledge, we are the first to study functional organized POI groups which have important applications in urban planning and social marketing.

关键词： functional organized point of interest (POI) group POI clustering OPG-LDA (organized point of interest group-latent Dirichlet allocation) model spatial keyword recommendation

Analysis on the Spatio-Temporal Changes of Sustainable Land Use in Tibet

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Wuhan University Journal of Natural Sciences 2006年第4期11卷 937-944页

作者： GU Shixian xu xia LIU Shuzhen Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 Sichuan China Graduated University of Chinese Academy of Sciences Beijing 100049 China School of Geography Beijing Normal University Beijing 100875 China

By constructing evaluation indicator system of sustainable land use of Tibet from three aspects of ecological environment, economic development, resources and social advancement, this article studies the following contents respectively in two dimensions of time and space： the changes of sustainable land use of Tibet in recent 20 years and spatial characteristics of sustainable land use of Tibet in 2002. The following conclusions can be drawn from evaluation results .① With regard to com- prehensive evaluation value of sustainable land use, the trend of Tibet sustainable land use evaluation values from 1983 to 2002 are very close to the comprehensive evaluation values of ecological environment, which is up trend; ② sustainable utilization degree of land use in eastern region of Tibet is much higher than that of western region. ③ the sustainable land use evaluation value of Nyingtri County is the highest, and the counties with relatively higher land sustainable use values include Lhasa, Lhoka, Chamdo. While Nakchu, Ngari, Shigatse counties have the relatively lower evaluation values; ④ By analyzing each evaluation indicator＇s weight on sustainable land use, it can be concluded that the key limiting factors of sustainable Tibet land resource utilization are land desertification, grassland degradation and low economic level.

关键词： spatio-temporal changes sustainable land use ecological environment economic development resources and social advancement

Reduction of the Differential Light Shift by the Spatial Periodicity in an Optical Lattice

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Chinese Physics Letters 2013年第10期30卷 85-88页

作者： YUE xu-Guang xu xia CHEN xu-Zong ZHOU xiao-Ji School of Electronics Engineering&Computer Science Peking UniversityBeijing 100871

We study the spatial periodicity effects on the differential light shift of noninteracting atoms in an optical *** the Rabi-spectrum approach,when the wavelength of the optical lattice is not magic,a reduction to the differential light shift is *** reduction results from the Bloch bands induced by the quantized motion in the periodic *** the microwave transition of rubidium atoms as an example,this reduction at some wavelengths can reach one order of magnitude,compared to the data without considering the spatial profile of the optical *** the atomic temperature is considered,the differential light shift increases or decreases with temperature,depending on the wavelength of the *** results should be beneficial for microwave optical lattice clock and precision measurements.

关键词： potential microwave lattice

Korteweg de Vries Description of One-Dimensional Superfluid Fermi Gases

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Chinese Physics Letters 2011年第12期28卷 199-202页

作者： xu Yan-xia DUAN Wen-Shan College of Physics and Electronic Engineering Northwest Normal UniversityLanzhou 730070

We study one-dimensional matter-wave pulses in cigar-shaped superfluid Fermi gases,including the linear and nonlinear waves of the system.A Korteweg de Vries(KdV)solitary wave is obtained for the superfluid Fermi gases in the limited case of a BEC regime,a BCS regime and *** dependences of the propagation velocity,amplitude and the width of the solitary wave on the dimensionless interaction parameter y=1/(kF asc)are given for the limited cases of BEC and unitarity.

关键词： Fermi gases solitary

Biomimetic mineralization and cytocompatibility of nanorod hydroxyapatite/graphene oxide composites

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Frontiers of Chemical Science and Engineering 2018年第4期12卷 798-805页

作者： Peizhen Duan Juan Shen Guohong Zou xu xia Bo Jin School of Materials Science and Engineering Southwest University of Science and TechnologyMianyang 621010China State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials Southwest University of Science and Technology Mianyang 621010China

Nanorod hydroxyapatite (NRHA)/graphene oxide (GO) composites with weight ratios of 0.4, 1.5, and 5 have been fabricated by a facile ultrasonic-assisted method at room temperature and atmospheric pressure. The chemical structure properties and morphology of the composites were characterized by field emission source scanning electron microscope, X-ray diffraction, transmission electron microscopy, and high-resolution transmission electron microscopy. The results indicate that the NRHA/ GO composites have an irregular surface with different degree wrinkles and are stable, and NRHA are well combined with GO. In addition, the biomimetic mineralization mechanism of hydroxyapatite on the NRHA/GO composites in simulated body fluid (SBF) is presented. The presence of a bone-like apatite layer on the composite surface indicate that the NRHA/GO composites facilitate the nucleation and growth of hydroxyapatite crystals in SBF for biomimetic mineralization. Moreover, the NRHA- 1.5/GO composite and pure GO were cultured with MC3T3-E1 cells to investigate the proliferation and adhesion of cells. In vitro cytocompatibility evaluation demonstrated that the NRHA/GO composite can act as a good template for the growth and adhesion of cells. Therefore, the NRHA/GO composite could be applied as a GO-based, free-template, non-toxic, and bioactive composite to substitute for a damaged or defect bone.

关键词： hydroxyapatite graphene oxide biomimetic mineralization cytocompatibility

Predicted Critical State Based on Invariance of the Lyapunov Exponent in Dual Spaces

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Chinese Physics Letters 2024年第1期41卷 68-76页

作者：刘通夏旭 Department of Applied Physics School of ScienceNanjing University of Posts and TelecommunicationsNanjing 210003China Academy of Mathematics and System Sciences Chinese Academy of SciencesBeijing 100190China

Critical states in disordered systems,fascinating and subtle eigenstates,have attracted a lot of research ***,the nature of critical states is difficult to describe quantitatively,and in general,it cannot predict a system that hosts the critical *** propose an explicit criterion whereby the Lyapunov exponent of the critical state should be 0 simultaneously in dual spaces,namely the Lyapunov exponent remains invariant under the Fourier *** this criterion,we can exactly predict a one-dimensional quasiperiodic model which is not of self-duality,but hosts a large number of critical ***,we perform numerical verification of the theoretical prediction and display the self-similarity of the critical *** to computational complexity,calculations are not performed for higher dimensional ***,since the description of extended and localized states by the Lyapunov exponent is universal and dimensionless,utilizing the Lyapunov exponent of dual spaces to describe critical states should also be ***,we conjecture that some kind of connection exists between the invariance of the Lyapunov exponent and conformal invariance,which can promote the research of critical phenomena.

关键词： state exponent critical