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Synthesis and Crystal Structure of a Novel 3D Magnesium(II) Coordination Polymer Constructed by Flexible Benzene-1,4-dioxyacetate

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Chinese Journal of Structural Chemistry 2005年第6期24卷 629-632页

作者： GAOShan HUOLi-Hua chengxiao-Li LIUJi-Wei LabortatoryofFunctionalMaterials SchoolofChemistryandMaterialsScienceHeilongjiangUniversityHarbin150080China

A novel coordination polymer of [Mg(1,4-BDOA)(CH3OH)2]n (1,4-BDOA2– = benzene-1,4-dioxyacetate dianion) has been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The crystal crystallizes in monoclinic system, space group P21/c, with a = 12.070(2), b = 7.7088(15), c = 7.3332(15) ?, β = 91.42(3)o, V = 682.1(2) ?3, Z = 2, Mr = 312.56, Dc = 1.522 g/cm3, μ = 0.168 mm–1, F(000) = 328, the final R = 0.0628 and wR = 0.1591 for 1082 observed reflections with I > 2σ(I). The Mg(II) atom and 1,4-BDOA2– ligand lie in different inversion centers. The Mg(II) atom shows an octahedral geometry defined by four carboxyl O atoms from four different 1,4-BDOA2– ligands and two hydroxyl O atoms from two methanol molecules. The Mg(II) atoms are bridged by 1,4-BDOA2– ligands, leading to a 3D infinite network structure.

关键词： magnesium(II) complex benzene-1,4-dioxyacetic acid synthesis crystal structure

Monte Carlo Hamiltonian： Inverse Potential

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Communications in Theoretical Physics 2004年第4期41卷 509-512页

作者： LUOXiang-Qian chengxiao-Ni HelmutKROeGER DepartmentofPhysics ZhongshanUniversityGuangzhou510275China DépartementdePhysique UniversitéLavalQuébecQuébecG1K7P4Canada

The Monte Carlo Hamiltonian method developed recently allows to investigate the ground state and low-lying excited states of a quantum system,using Monte Carlo(MC)algorithm with importance ***,conventional MC algorithm has some difficulties when applied to inverse *** propose to use effective potential and extrapolation method to solve the *** present examples from the hydrogen system.

关键词： Monte Carlo method quantum mechanics computational physics

Compound-mode crack propagation law of PMMA semicirculararch roadway specimens under impact loading

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International Journal of Coal Science & Technology 2021年第6期8卷 1302-1315页

作者： chengxiao Li Dongming Guo Yuantong Zhang Chen An School of Mechanics and Civil Engineering China University of Mining and Technology-BeijingBeijing 100083China

An underground roadway usually contains defects of various types,and when the roadway is subjected to external loading,the locations of those defects influence the roadway by differing *** this study,to study how the locations of defects affect crack propagation in a roadway,specimens with tunnel-type voids were made using polymethyl methacrylate,and the stress wave produced by a bullet impacting an incident rod was used as the impact ***,the variations in crack speed,displacement,and dynamic stress intensity factor during crack propagation were obtained using an experimental system of digital laser dynamic caustics,and the commercial software ABAQUS was used for numerical *** the experiments and numerical simulations,the crack propagation path was verified and the impact fracture behavior of a semicircular-arch roadway with different defect positions was *** results show that when the pre-fabricated crack is on the central axis of the sample,the crack propagation is purely mode I;when the pre-fabricated crack is 5 mm from the central axis,the crack propagation alternates between mode I and a mixture of modes I and II;when the pre-fabricated crack is at the edge of the semicircular-arch roadway,the crack propagation follows the I-II mixed mode.

关键词： Defect location Dynamic caustics Polymethyl methacrylate ABAQUS Semicircular-arch roadway

Hepatic progenitor cells in human liver cirrhosis:Immunohistochemical,electron microscopic and immunofluorencence confocal microscopic findings

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World Journal of Gastroenterology 2004年第8期10卷 1208-1211页

作者： Jia-chengxiao Xiao-LongJin PeterRuck AnneAdam EdwinKaiserling DepartmentofPathology RuijinHospitalShanghai2adMedicalUniversityShanghai200025China

AIM:To investigate whether hepatic progenitor cells(HPC), that reveal the features of oval cells in rodents and small epithelial cells(SEC)in certain human liver disease,were also found in human liver cirrhosis(HLC). METHODS:Surgical liver specimens from 20 cases of hepatitis B virus-positive HLC(15 cases containing hepatocellular carcinoma)were investigated by light microscopic immunohistochemistry(LM-IHC).Among them specimens from 15 cases were investigated by electron microscopy(EM) and those from 5 cases by immunofluorencence confocal laser scanning microscopy(ICLSM).Antibodies against cytokeratin 7 and albumin were used and single and/or double labelling were performed respectively. RESULTS:LM-IHC showed that at the margins of regenerating nodules and in the fibrous septae,a small number of cells in the proliferating bile ductules were positive for CK7 and *** the EM level these HPC were morphologically similar to the SEC described previously,and also similar to the oval cells seen in experimental hepatocarcinogenesis. They were characterized by their small size,oval shape,a high nucleus/cytoplasm ratio,a low organelle content in cytoplasm,and existence of tonofilaments and intercellular *** revealed that HPC expressed both cytokeratin 7 and albumin. CONCLUSION:HPC with ultrastructural and immunophenotypical features of oval cells,i.e.,hepatic stem cell-like cells as noted in other liver diseases,were found in *** findings further support the hypothesis that bipotent hepatic stem cells,that may give rise to biliary epithelial cells and hepatocytes,exist in human livers.

关键词：肝祖细胞肝硬化免疫组织化学电子显微镜免疫荧光法超微结构

Research on Eddy Current Testing System of the Carburized Layer Depth of 20CrMnTi Steel

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材料热处理学报 2004年第5期25卷 409-411页

作者： chengxiao-min LINa WUXin-wen FANGHua-bin SchoolofMaterialsScienceandEngineering WuhanUniversityofTechnologyWuhanChina SchoolofMaterialsScienceandEngineering ShanghaiJiaoTongUniversityShanghaiChina

In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current testing system of the case depth of this carburized steel was built by using ANSYS software as second development platform.

关键词： 20CrMnTi钢渗碳渗碳层厚度涡流试验有限元

Synergism of 1D CdS/2D Modified Ti_(3)C_(2)T_(x) MXene Heterojunctions for Boosted Photocatalytic Hydrogen Production

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Chinese Journal of Structural Chemistry 2022年第8期41卷 58-64页

作者： Shi Cheng Qianqian Xiong chengxiao Zhao Xiaofei Yang College of Science Nanjing Forestry UniversityNanjing 210037China

Rational design and controllable synthesis of visible-light-responsive photocatalysts that exhibit both good hydrogen-producing efficiency and stability in the water splitting reaction are undoubtedly a challenge. Here we report an integrated CdS nanorod/oxygen-terminated Ti_(3)C_(2)T_(x) MXene nanosheet heterojunction with a high catalytic hydrogen evolution reaction(HER) activity. By incorporating one-dimensional(1D)CdS nanorods onto annealed ultrathin two-dimensional(2D) MXene nanosheets, the mixed-dimensional 1D/2D heterojunction achieved a hydrogen-evolving rate of 8.87 mmol·g^(-1)·h^(-1), much higher than that of bulk CdS and CdS/unmodified MXene hybrid catalysts. The enhanced HER activity and stability of the designed heterojunction catalyst are attributed to the presence of oxygen-containing terminal groups on the surface of thermally treated Ti_(3)C_(2)T_(x) MXene, extended light absorption spectra as well as the precisely constructed intimate Schottky contact, implying an accelerated interfacial charge transfer and efficient, long-term photocatalytic hydrogen production performance. The results demonstrate that oxygen-terminated 2D MXene can be well utilized as a functional platform for the development of novel heterojunction photocatalysts.

关键词： CdS MXene heterojunction water splitting hydrogen evolution reaction

MEC-Empowered Non-Terrestrial Network for 6G Wide-Area Time-Sensitive Internet of Things

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Engineering 2022年第1期8卷 96-107页

作者： chengxiao Liu Wei Feng Xiaoming Tao Ning Ge Department of Electronic Engineering Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China

In the upcoming sixth-generation(6G)era,the demand for constructing a wide-area time-sensitive Internet of Things(IoT)continues to *** conventional cellular technologies are difficult to directly use for wide-area time-sensitive IoT,it is beneficial to use non-terrestrial infrastructures,including satellites and unmanned aerial vehicles(UAVs).Thus,we can build a non-terrestrial network(NTN)using a cell-free *** by the time-sensitive requirements and uneven distribution of IoT devices,the NTN must be empowered using mobile edge computing(MEC)while providing oasisoriented on-demand coverage for ***,communication and MEC systems are coupled with each other under the influence of a complex propagation environment in the MEC-empowered NTN,which makes it difficult to coordinate the *** this study,we propose a process-oriented framework to design communication and MEC systems in a time-division *** this framework,large-scale channel state information(CSI)is used to characterize the complex propagation environment at an affordable cost,where a nonconvex latency minimization problem is ***,the approximated problem is provided,and it can be decomposed into *** sub-problems are then solved *** simulation results demonstrated the superiority of the proposed process-oriented scheme over other algorithms,implied that the payload deployments of UAVs should be appropriately predesigned to improve the efficiency of using resources,and confirmed that it is advantageous to integrate NTN with MEC for wide-area time-sensitive IoT.

关键词： Cell-free Mobile edge computing Non-terrestrial networks Sixth-generation Wide-area time-sensitive IoT

Fairness-Oriented Hybrid Precoding for Massive MIMO Maritime Downlink Systems with Large-Scale CSIT

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China Communications 2018年第1期15卷 52-61页

作者： chengxiao Liu Wei Feng Te Wei Ning Ge Tsinghua National Laboratory for Information Science and Technology Tsinghua University

Different from conventional cellular networks, a maritime communication base station(BS) has to cover a much wider area due to the limitation of available BS sites. Accordingly the performance of users far away from the BS is poor in general. This renders the fairness among users a challenging issue for maritime communications. In this paper, we consider a practical massive MIMO maritime BS with hybrid digital and analog precoding. Only the large-scale channel state information at the transmitter(CSIT) is considered so as to reduce the implementation complexity and overhead of the system. On this basis, we address the problem of fairness-oriented precoding design. A max-min optimization problem is formulated and solved in an iterative way. Simulation results demonstrate that the proposed scheme performs much better than conventional hybrid precoding algorithms in terms of minimum achievable rate of all the users, for the typical three-ray maritime channel model.

关键词： maritime communication massive MIMO hybrid precoding large-scale channel state information at the transmitter(CSIT) max-min fairness

Intermolecular　Interaction　Potentials　of　CH4-Ne　Complex　Calculated　with　Local　Density　Approximation　Methods

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Chinese Physics Letters 2004年第6期21卷 1048-1050页

作者： BAIYu-Lin chengxiao-Hong CHENXiang-Rong YANGXiang-Dong ZHUJun InstituteofAtomicandMolecularPhysics SichuanUniversityChengdu610065 DepartmentofElectronicInformationScienceandTechnology YibinUniversityYibin644000

The intermolecular interactions potentials for two configurations of CH4–Ne complex are calculated with local density approximation methods in the frame of density functional theory. It is found that the calculated potentials have two minima when the distance between the carbon atom of CH4 and the Ne atom takes R = 5.80a.u. and 6.20a.u. for both the two configurations. For the edge configuration, the corresponding depth of the potential is 0.0669536eV and 0.0671416eV. For the face configuration, the corresponding depth of the potential is 0.0737956eV and 0.0645506eV. The global minimum occurs at R = 5.80a.u. for the face configuration with a depth of the potential 0.0737956eV. The depths of our calculation are in better agreement with the experimental data than the quantum chemical calculation approach, while the position of minimum potential for our calculation is underestimated.

关键词： Local density approximation