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Atomically dispersed materials:Ideal catalysts in atomic era

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Nano Research 2024年第1期17卷 18-38页

作者： tao Gan Dingsheng Wang Department of Chemistry Tsinghua UniversityBeijing 100084China

Catalysts can accelerate the chemical reaction rate and effectively promote the molecules transformation,which is of great significance in the research of chemical industry and material science.The extreme utilization of reactive sites has led to the emergence and development of atomically dispersed materials(ADMs).The highly active coordination unsaturated metal sites and fully utilized metal atoms make ADMs show great potential in catalytic reactions.The adjustment of coordination environment and electronic structure provides more possibilities for constructing reactive centers with different properties.This review summarized the application and research progress of ADMs in different fields.The design strategy and structure–activity relationship of ADMs for specific reactions were summarized and analyzed.Moreover,we also provided advices for the challenges and opportunities faced by ADMs in catalytic reactions.

关键词： atomically dispersed materials catalysis organic synthesis battery sensor enzyme

Theoretical analysis of the double-differential cross-sections of neutron,proton,deuteron,^(3)He,andαfor the p+^(6) Li reaction

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Nuclear Science and Techniques 2024年第3期35卷 181-197页

作者： Fang-Lei Zou Xiao-Jun Sun Jing-Shang Zhang Hai-Rui Guo Yin-Lu Han Rui-Rui Xu Xi tao Ji-Min Wang Xiao-Dong Sun Yuan Tian tao Ye yong-Li Xu Chun-Tian Liang College of Physics Guangxi Normal University541004 GuilinChina Guangxi Key Laboratory of Nuclear Physics and Nuclear Technology 541004 GuilinChina China Institute of Atomic Energy P.O.Box 275(41)102413 BeijingChina Institute of Applied Physics and Computational Mathematics 10094 BeijingChina College of Physics and Electronic Shanxi Datong University037009 DatongChina School of Science Tianjin Chengjian University300384 TianjinChina

Based on the unified Hauser–Feshbach and exciton model,which can describe the particle emission processes between discrete energy levels with energy,angular momentum,and parity conservations,a statistical theory of light nucleus reaction(STLN)is developed to calculate the double-differential cross-sections of the outgoing neutron and light charged particles for the proton-induced^(6) Li reaction.A significant difference is observed between the p+^(6) Li and p+^(7) Li reactions owing to the discrepancies in the energy-level structures of the targets.The reaction channels,including sequential and simultaneous emission processes,are analyzed in detail.Taking the double-differential cross-sections of the outgoing proton as an example,the influence of contaminations(such as^(1) H,^(7)Li,^(12)C,and^(16)O)on the target is identified in terms of the kinetic energy of the first emitted particles.The optical potential parameters of the proton are obtained by fitting the elastic scattering differential cross-sections.The calculated total double-differential cross-sections of the outgoing proton and deuteron at E_(p)=14 MeV agree well with the experimental data for different outgoing angles.Simultaneously,the mixed double differential cross-sections of^(3) He andαare in good agreement with the measurements.The agreement between the measured data and calculated results indicates that the two-body and three-body breakup reactions need to be considered,and the pre-equilibrium reaction mechanism dominates the reaction processes.Based on the STLN model,a PLUNF code for the p+^(6) Li reaction is developed to obtain an ENDF-6-formatted file of the double-differential cross-sections of the nucleon and light composite charged particles.

关键词： Statistical theory of light nucleus reaction p+^(6)Li reaction Light composite charged particle Double-differential cross-sections Two-body breakup Three-body breakup

H?lder continuous weak solutions of the 2D Boussinesq equation with thermal diffusion

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Science China Mathematics 2024年第8期67卷 1777-1806页

作者： Tianwen Luo tao tao Liqun Zhang Yau Mathematical Sciences Center Tsinghua University School of Mathematics Shandong University Institute of Mathematics Academy of Mathematics and Systems ScienceChinese Academy of Sciences School of Mathematical Sciences University of Chinese Academy of Sciences

We show the existence of H?lder continuous periodic weak solutions of the 2D Boussinesq equation with thermal diffusion which satisfy the prescribed kinetic energy. More precisely, for any smooth e(t):[0, 1]→■ and ... 详细信息

关键词： 2D Boussinesq equation with thermal diffusion Hölder continuous periodic weak solutions prescribed kinetic energy

Positive definiteness of real quadratic forms resulting from the variable-step L1-type approximations of convolution operators

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Science China Mathematics 2024年第2期67卷 237-252页

作者： Hong-Lin Liao tao Tang tao Zhou School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Division of Science and Technology BNU-HKBU United International CollegeZhuhai 519087China SUSTech International Center for Mathematics Shenzhen 518055China NCMIS&LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

The positive definiteness of real quadratic forms with convolution structures plays an important rolein stability analysis for time-stepping schemes for nonlocal operators. In this work, we present a novel analysistool to handle discrete convolution kernels resulting from variable-step approximations for convolution operators.More precisely, for a class of discrete convolution kernels relevant to variable-step L1-type time discretizations, weshow that the associated quadratic form is positive definite under some easy-to-check algebraic conditions. Ourproof is based on an elementary constructing strategy by using the properties of discrete orthogonal convolutionkernels and discrete complementary convolution kernels. To our knowledge, this is the first general result onsimple algebraic conditions for the positive definiteness of variable-step discrete convolution kernels. Using theunified theory, we obtain the stability for some simple nonuniform time-stepping schemes straightforwardly.

关键词： discrete convolution kernels positive definiteness variable time-stepping orthogonal convolution kernels complementary convolution kernels

The infection kinetics and transmission potential of two Guaico Culex viruses in Culex quinquefasciatus mosquitoes

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Virologica Sinica 2024年第2期39卷 228-234页

作者： Ru-Yi Chen Teng Zhao Jing-Jing Guo Feng Zhu Na-Na Zhang Xiao-Feng Li Hai-tao Liu Fei Wang yong-Qiang Deng Cheng-Feng Qin College of Bioscience and Bioengineering Jiangxi Agricultural UniversityNanchang330045China State Key Laboratory of Pathogen and Biosecurity Beijing Institute of Microbiology and EpidemiologyAMMSBeijing100071China School of Life Sciences Southwest Forestry UniversityKunming650224China

Guaico Culex virus(GCXV)is a newly identified segmented Jingmenvirus from Culex spp.mosquitoes in Central and South America.The genome of GCXV is composed of four or five single-stranded positive RNA segments.However,the infection kinetics and transmission capability of GCXV in mosquitoes remain unknown.In this study,we used reverse genetics to rescue two GCXVs(4S and 5S)that contained four and five RNA segments,respectively,in C6/36 cells.Further in vitro characterization revealed that the two GCXVs exhibited comparable replication kinetics,protein expression and viral titers.Importantly,GCXV RNAs were detected in the bodies,salivary glands,midguts and ovaries of Culex quinquefasciatus at 4–10 days after oral infection.In addition,two GCXVs can colonize Cx.quinquefasciatus eggs,resulting in positive rates of 15%–35%for the second gonotrophic cycle.In conclusion,our results demonstrated that GCXVs with four or five RNA segments can be detected in Cx.quinquefasciatus eggs during the first and second gonotrophic cycles after oral infection.

关键词： Guaico Culex virus(GCXV) Jingmenvirus Culex quinquefasciatus Vertical transmission

Feedback linearization and equivalent-disturbance compensation control strategy for piezoelectric stage

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Nanotechnology and Precision Engineering 2024年第2期7卷 49-59页

作者： tao Huang Yingbin Wang Zhihong Luo Huajun Cao Guibao tao Mingxiang Ling State Key Laboratory of Mechanical Transmissions for Advanced Equipment Chongqing UniversityChongqing 400044China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing 400044China Hongdu Aviation Industry Group NanchangJiangxi 330000China Robotics and Microsystems Center Soochow UniversitySuzhou 215123China

Piezoelectric stages use piezoelectric actuators and flexure hinges as driving and amplifying mechanisms,respectively.These systems have high positioning accuracy and high-frequency responses,and they are widely used in various precision/ultra-precision positioning fields.However,the main challenge with these devices is the inherent hysteresis nonlinearity of piezoelectric actuators,which seriously affects the tracking accuracy of a piezoelectric stage.Inspired by this challenge,in this work,we developed a Hammerstein model to describe the hysteresis nonlinearity of a piezoelectric stage.In particular,in our proposed scheme,a feedback-linearization algorithm is used to eliminate the static hysteresis nonlinearity.In addition,a composite controller based on equivalent-disturbance compensation was designed to counteract model uncertainties and external disturbances.An analysis of the stability of a closed-loop system based on this feedback-linearization algorithm and composite controller was performed,and this was followed by extensive comparative experiments using a piezoelectric stage developed in the laboratory.The experimental results confirmed that the feedback-linearization algorithm and the composite controller offer improved linearization and trajectory-tracking performance.

关键词： Piezoelectric stage Hysteresis nonlinearity Feedback linearization Equivalent-disturbance compensation

A Comprehensive Overview of the Neural Mechanisms of Light Therapy

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Neuroscience Bulletin 2024年第3期40卷 350-362页

作者： Xiaodan Huang Qian tao Chaoran Ren Guangdong-Hongkong-Macao Institute of CNS Regeneration Ministry of Education CNS Regeneration Collaborative Joint LaboratoryJinan UniversityGuangzhou 510632China Psychology Department School of MedicineJinan UniversityGuangzhou 510632China

Light is a powerful environmental factor influencing diverse brain functions.Clinical evidence supports the beneficial effect of light therapy on several diseases,including depression,cognitive dysfunction,chronic pain,and sleep disorders.However,the precise mechanisms underlying the effects of light therapy are still not well understood.In this review,we critically evaluate current clinical evidence showing the beneficial effects of light therapy on diseases.In addition,we introduce the research progress regarding the neural circuit mechanisms underlying the modulatory effects of light on brain functions,including mood,memory,pain perception,sleep,circadian rhythm,brain development,and metabolism.

关键词： Light therapy Neural circuit Mood Cognition Pain Sleep Development Metabolism

Effective Capacity of URLLC over Parallel Fading Channels with Imperfect Channel State Information

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China Communications 2024年第5期21卷 45-63页

作者： Peng Hongsen tao Meixia Department of Electronic Engineering and the Cooperative Medianet Innovation Center Shanghai Jiao Tong UniversityShanghai 200240China

This paper investigates the effective capacity of a point-to-point ultra-reliable low latency communication(URLLC)transmission over multiple parallel sub-channels at finite blocklength(FBL)with imperfect channel state information(CSI).Based on reasonable assumptions and approximations,we derive the effective capacity as a function of the pilot length,decoding error probability,transmit power and the sub-channel number.Then we reveal significant impact of the above parameters on the effective capacity.A closed-form lower bound of the effective capacity is derived and an alternating optimization based algorithm is proposed to find the optimal pilot length and decoding error probability.Simulation results validate our theoretical analysis and show that the closedform lower bound is very tight.In addition,through the simulations of the optimized effective capacity,insights for pilot length and decoding error probability optimization are provided to evaluate the optimal parameters in realistic systems.

关键词： effective capacity finite blocklength regime imperfect CSI parallel fading channels URLLC

Heat Transfer and Friction Characteristics of Printed Circuit Heat Exchangers with Different Channel Structures for S-CO_(2) Power System

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Journal of Thermal Science 2024年第3期33卷 1132-1147页

作者： JIANG tao LI Mingjia Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an710049China School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China

Printed circuit heat exchanger(PCHE)has been widely used in supercritical carbon dioxide(S-CO_(2))power systems because of its high heat transfer efficiency and good compactness.However,due to the large variety of PCHE configurations,channel selection in practical applications lacks a basis.Therefore,this paper discussed the heat transfer and friction characteristics and the synergy of three fields in the channel under the guidance of the field synergy principle for four typical PCHE channels.Additionally,the comprehensive performance of four channels was compared.Finally,the heat transfer and friction factor correlations for S-CO_(2)in four channels were established.The findings demonstrate that the synergy of velocity and pressure fields of the straight channel PCHE is better(β≈180°),so its resistance loss is relatively small.The zigzag and sinusoidal wavy channels and the airfoil fins can reduce the angle a between the temperature gradient and velocity,thus enhancing the heat transfer.The sinusoidal wavy channel can reduce flow resistance compared to the zigzag channel due to the rounded corners.The streamlined airfoil structure can guide the flow and reduce backflow,thus reducing resistance losses.In the range of Re studied in this paper,the maximum error of the proposed heat transfer and friction factor correlations of PCHE is 7.0%,which shows good fitting accuracy.The research in this paper can provide a reference for the selection and design of PCHE with different channel configurations.

关键词： printed circuit heat exchanger supercritical carbon dioxide typical channel structure field synergy analysis