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APPLICATION OF ELECTRON DIFFRACTION IN THE STRUCTURE CHARACTERIZATION OF POLYMER CRYSTALS

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Chinese Journal of Polymer Science 2013年第6期31卷 841-841,842-852页

作者： Jiang wu hai-xin Zhou Qi Liu 闫寿科 Kunming University of Science and Technology State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology

The dependence of properties on the structure and morphology of semicrystalline polymers offers an effective way to tailor the properties of these materials through structure control. To this end, establishing the structure and property relationship is of great importance. For a right characterization of the crystal structure, several techniques can be used. Among these techniques, electron diffraction has its advantage for determining the crystal structure related to specific formation condition since it can combine with bright and dark fields observation of the sample. This feature article describes the application of electron diffraction in determining the crystal structure of semicrystalline polymers with elaborately selected examples. We focus on how the electron diffraction can be used to disclose the crystal structure, mutual orientation of different crystals, as well as the disorders included in the polymer crystals.

关键词： Electron diffraction Semicrystalline polymer Crystal structure Orientation Defect.

Ag/AgX nanostructures serving as antibacterial agents:achievements and challenges

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Rare Metals 2022年第2期41卷 519-539页

作者： Pei-Pei Li hai-Xia wu Alideertu Dong College of Chemistry and Chemical Engineering Engineering Research Center of Dairy Quality and Safety Control TechnologyMinistry of EducationInner Mongolia UniversityHohhot 010021China

Bacterial infections,especially the frequently emerging "superbugs",seriously affect the quality of human life and even threaten human *** the emerging antimicrobial agents that effectively eradicate pathogens,nanomaterials have been widely explored due to their effectiveness against wide-spectrum bacteria and“superbugs”.Of them,Ag/AgX nanostructures(X representing Cl,Br or I)have emerged as an excellent antibacterial agent because of their excellent photocatalytic performance in inactivating pathogens under light irradiation,which provides a new opportunity for the development of high-efficient visible-light driven photocatalytic *** date,Ag/AgX nanostructures have been widely employed in antibacterial associated fields because they are efficient in producing reactive oxygen species(ROS)and reactive chlorine species(RCS)under visible light *** this review,we summarized the recent progress of Ag/AgX nanostructures as plasmonic photocatalysts in the antibacterial field,focusing on the antibacterial effects and mechanisms of Ag/AgX nanostructures,as well as their potent ***,the challenges and prospects of Ag/AgX nanostructures acting as active antibacterial agents were discussed.

关键词： Ag/AgX Photocatalytic Antibacterial Nanostructure Nanoengineering

Improving color rendering index of Mn-doped ZnO nanorods on silicon-based substrate

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Rare Metals 2017年第9期36卷 711-717页

作者： Zheng-Long wu Bin Tian hai-Jun Xu Analytical and Testing Center Beijing Normal University State Key Laboratory of Chemical Resource Engineering and School of Science Beijing University of Chemical Technology

Porous silicon pillar array（PSPA） samples which are ideal substantial materials with dominant electronic and luminescence properties were prepared by surface etching method. ZnO nanorods with or without Mn doping grown uniformly and aligned onto PSPA regardless of lattice matching show various photoluminescence（PL）properties. The doped Mn ions in ZnO nanorods were directly observed by X-ray photoelectron spectroscopy（XPS）,and ZnO structures were detected by X-ray diffraction（XRD）. As the doping concentration increases,XRD peaks of ZnO nanorods shift to low angle. The influences of doping Mn ions on luminescence properties of ZnO nanorods were investigated. Except for the ultraviolet（UV） PL band, the broad PL band is observed at visible region. The band could be divided into three separate bands（orange, green and red） by Lorentzian deconvolution. The intensity of orange PL band firstly increases then decreases, and then gets the maximum at the doping Mn-to-Zn molar ratio of 2.0：100.0 which is the most effective doping concentration. The green PL band is attributed to zinc vacancy of ZnO, the orange PL band to Mn ions recombination of itself, and the red PL band to oxygen vacancy of ZnO, respectively. As the Mn-doped ZnO nanorods could emit yellow green luminescence excited by UV radiation, and doped Mn ions could improve the color rendering index of the luminescence, the nanorods could be used as promising white-light emitters in the future.

关键词： ZnO/Mn nanorod arrays Photoluminescence White light Hydrothermal synthesis

Fault-tolerant finite-time dynamical consensus of double-integrator multi-agent systems with partial agents subject to synchronous self-sensing function failure

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Chinese Physics B 2022年第12期31卷 719-725页

作者： Zhi-hai wu Lin-Bo Xie Engineering Research Center of Internet of Things Technology Applications of MOE School of Internet of Things EngineeringJiangnan UniversityWuxi 214122China

This paper investigates fault-tolerant finite-time dynamical consensus problems of double-integrator multi-agent systems(MASs)with partial agents subject to synchronous self-sensing function failure(SSFF).A strategy of recovering the connectivity of network topology among normal agents based on multi-hop communication and a fault-tolerant finitetime dynamical consensus protocol with time-varying gains are proposed to resist synchronous *** is proved that double-integrator MASs with partial agents subject to synchronous SSFF using the proposed strategy of network topology connectivity recovery and fault-tolerant finite-time dynamical consensus protocol with the proper time-varying gains can achieve finite-time dynamical *** simulations are given to illustrate the effectiveness of the theoretical results.

关键词： multi-agent systems synchronous self-sensing function failure finite-time dynamical consensus network topology connectivity recovery

Hydrothermal synthesis and characterization of NiS flower-like architectures

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Particuology 2012年第6期10卷 783-788页

作者： hai Zhou Baoliang Lv Dong wu Yuhan Sun Key Laboratory of Carbon Materials Institute of Coal ChemistryChinese Academy of Sciences Graduate University of the Chinese Academy of Science Low Carbon Conversion Center Shanghai Advanced Research InstituteChinese Academy of Sciences

Under the influence of thiocyanate anions （SCN-） and cetyltrimethyl ammonium bromide （CTAB）, NiS flower-like architectures were successfully synthesized by a one-step hydrothermal method. The syn-thesized flower-like architectures, with a multilayered and highly ordered texture, have diameters of several micrometers. X-ray powder diffraction （XRD） shows that the NiS flower-like architectures are rhombohedral crystalline. On the basis of condition-dependent experiments, the diffusion-limited aggregation （DLA） model and cage effect were used to explain the growth process of rhombohedral crystalline NiS flower-like architectures. Magnetic measurements showed that the coercivity （He） of the as-obtained NiS flower-like architectures was 102.14 Oe.

关键词： Nanostructures Chemical synthesis Electron microscopy Magnetic properties

Dinosaur-associated Poaceae epidermis and phytoliths from the Early Cretaceous of China

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National Science Review 2018年第5期5卷 721-727页

作者： Yan wu hai-Lu You Xiao-Qiang Li Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences Institute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of Sciences CAS Center for Excellence in Life and Paleoenvironment College of Earth Sciences University of Chinese Academy of Sciences

Grasses(Poaceae) are human’s most important crop plants and among the most important extant clades of vascular plants. However, the origin and early evolution of grasses are controversial, with estimated ages from molecular dating ranging between 59 and 129 Ma(million years ago). Here we report the discovery of basalmost grasses from the late Early Cretaceous(Albian, 113-101 Ma) of China based on microfossils(silicified epidermal pieces and phytoliths) extracted from a special structure along the dentition of a basal hadrosauroid(duck-billed dinosaur). Thus, this discovery represents the earliest known grass fossils, and is congruent with previous estimations on grass origin and early evolution calibrated by oldest known fossil grasses, highlighting the role of fossils in molecular dating. This discovery also indicates deep-diverging grasses probably gained broad distribution across both Laurasian and Gondwanan continents during the Barremian(129-125 Ma).

关键词： Poaceae dinosaur phytolith epidermis Early Cretaceous

Large-eddy simulation of suspended sediment transport in turbulent channel flow

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Journal of Hydrodynamics 2013年第1期25卷 48-55页

作者： ZHU hai WANG Ling-ling TANG Hong-wu College of Water Conservancy and Hydropower Engineering Hohai University

The numerical simulation of the non-cohesive sediment transport in a turbulent channel flow with a high concentration is a challenging but practical task. A modified coherent dynamic eddy model of the Large Eddy Simulation （LES） with a pick-up function is used in the present study to simulate the sediment erosion and the deposition in a turbulent channel flow. The rough wall model is used instead of the LES with the near-wall resolution to obtain the reasonable turbulent flow characteristics while avoiding the high costs in the computation. Good results are obtained, and are used to analyze the sediment transport properties. The results show that the streamwise vortices play an important role in the riverbed erosion and the sediment pick-up, which may serve as guidelines for the sediment management and the water environment protection engineering.

关键词： Large Eddy Simulation (LES) sediment suspension pick-up function turbulent channel flow

Vortex-Induced Vibrations of A Free-Spanning Pipe Based on A Nonlinear Hysteretic Soil Model at the Shoulders

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China Ocean Engineering 2020年第3期34卷 328-340页

作者： GAO Xi-feng XIE wu-de XU Wan-hai State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China

The pipe-soil interactions at shoulders can significantly affect the vortex-induced vibrations (VIV) of free-spanning pipes in the subsea. In this paper, the seabed soil reacting force on the pipe is directly calculated with a nonlinear hysteretic soil model. For the VIV in the middle span, a classic van der Pol wake oscillator is adopted. Based on the Euler-Bernoulli beam theory, the vibration equations of the pipe are obtained which are different in the middle span and at the two end shoulders. The static configuration of the pipe is firstly calculated and then the VIV is *** present model is validated with the comparisons of VIV experiment, pipe-soil interaction experiment and the simulation results of VIV of free-spanning pipes in which the seabed soil is modelled with spring-dashpots. With the present model, the influence of seabed soil on the VIV of a free-spanning pipe is analyzed. The parametric studies show that when the seabed soil has a larger suction area, the pipe vibrates with smaller bending stresses and is *** with the increase of the shear strength of the seabed soil, the bending stresses increase and the pipe faces more danger.

关键词： free-spanning pipe vortex-induced vibrations nonlinear hysteretic soil model bending stresses

An improved analysis method for assessing the nuclear-heating impact on the stability of toroidal field magnets in fusion reactors

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Nuclear Science and Techniques 2024年第6期35卷 163-176页

作者： Yu-Dong Lu Jin-Xing Zheng Xu-Feng Liu Huan wu Jian ge Kun Xu Ming Li hai-Yang Liu Lei Zhu Fei Liu Institute of Plasma Physics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China

The superconducting magnet system of a fusion reactor plays a vital role in plasma confinement,a process that can be dis-rupted by various operational factors.A critical parameter for evaluating the temperature margin of superconducting magnets during normal operation is the nuclear heating caused by D-T *** study investigates the impact of nuclear heat-ing on a superconducting magnet system by employing an improved analysis method that combines neutronics and thermal *** the magnet system,toroidal field(TF)magnets are positioned closest to the plasma and bear the highest nuclear-heat load,making them prime candidates for evaluating the influence of nuclear heating on *** enhance the modeling accuracy and facilitate design modifications,a parametric TF model that incorporates heterogeneity is established to expedite the optimization design process and enhance the accuracy of the computations.A comparative analysis with a homogeneous TF model reveals that the heterogeneous model improves accuracy by over 12%.Considering factors such as heat load,magnetic-field strength,and cooling conditions,the cooling circuit facing the most severe conditions is selected to calculate the temperature of the *** selection streamlines the workload associated with thermal-hydraulic *** approach enables a more efficient and precise evaluation of the temperature margin of TF ***,it offers insights that can guide the optimization of both the structure and cooling strategy of superconducting magnet systems.

关键词： Superconducting magnet Nuclear heating Neutronics Thermal hydraulics