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Effect of milling process on the core-shell structures and dielectric properties of fine-grained BaTiO_3-based X7R ceramic materials

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 345-348页

作者： tian wang xiao-hui wang Hai Wen Long-tu Li State Key Laboratory of New Ceramics and Fine Processing Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

Fine-grained BaTiO3-based X7R ceramic materials were prepared and the effects of milling process on the core-shell structures and dielectric properties were investigated using scanning electron microscope, transmission electron microscope, and energy dispersive spectroscopy （EDS）. As the milling time extends, the dielectric constant of the ceramics increases, whereas the temperature coefficient of capacitance at 125℃ drops quickly. The changes in dielectric properties are considered relevant to the microstructure evolution caused by the milling process. Defects on the surface of BaTiO3 particles increase because of the effects of milling process, which will make it easier for additives to diffuse into the interior grains. As the milling time increases, the shell region gets thicker and the core region gets smaller; however, EDS results show that the chemical inhomogeneity between grain core and grain shell becomes weaker.

关键词： fine-grain barium titanate core-shell structure milling process microstructure capacitor

Negative Thermal Expansion of the Dy_2Fe_(16)Cr Compound

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Chinese Physics Letters 2019年第6期36卷 41-43页

作者： Li-Yu HAO Tie YANG xiao-tian wang Ming TAN School of Physical Science and Technology Southwest University College of Science Henan Agricultural University

Structural, thermal expansion, and magnetic properties of the Dy_2Fe_(16)Cr compound are investigated by means of x-ray diffraction and magnetization measurements. The Dy_2Fe_(16)Cr compound has a hexagonal Th_2Ni_(17)-type structure. There exists a negative thermal expansion resulting from a strong spontaneous magnetostriction in the magnetic state of the Dy_2Fe_(16)Cr compound. The average thermal expansion coefficient is-0.794 × 10^(-5)/K in the temperature range 292–407 K. The spontaneous magnetostrictive deformation and the Curie temperature are discussed.

关键词： Negative Thermal Expansion Dy2Fe16Cr Compound magnetic state

Homocysteine-Induced Disturbances in DNA Methylation Contribute to Development of Stress-Associated Cognitive Decline in Rats

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Neuroscience Bulletin 2022年第8期38卷 887-900页

作者： Shi-Da wang Xue wang Yun Zhao Bing-Hua Xue xiao-tian wang Yu-Xin Chen Zi-Qian Zhang Ying-Rui tian Fang Xie Ling-Jia Qian Institute of Military Cognitive and Brain Sciences Academy of Military Medical SciencesBeijing100850China 8th People’s Hospital of Qingdao Qingdao266041China School of Public Health Lanzhou UniversityLanzhou730000China

Chronic stress is generally accepted as the main risk factor in the development of cognitive decline;however,the underlying mechanisms remain *** data have demonstrated that the levels of homocysteine(Hcy)are significantly elevated in the plasma of stressed animals,which suggests that Hcy is associated with stress and cognitive *** test this hypothesis,we analyzed the cognitive function,plasma concentrations of Hcy,and brain-derived neurotropic factor(BDNF)levels in rats undergoing chronic unpredicted mild stress(CUMS).The results showed that decreased cognitive behavioral performance and decreased BDNF transcription and protein expression were correlated with hyperhomocysteinemia(HHcy)levels in stressed ***-induced HHcy mimicked the cognitive decline and BDNF downregulation in the same manner as CUMS,while Hcy reduction(by means of vitamin B complex supplements)alleviated the cognitive deficits and BDNF reduction in CUMS ***,we also found that both stress and HHcy disturbed the DNA methylation process in the brain and induced DNA hypermethylation in the BDNF *** contrast,control of Hcy blocked BDNF promoter methylation and upregulated BDNF levels in the *** results imply the possibility of a causal role of Hcy in stress-induced cognitive *** also used ten-eleven translocation(TET1),an enzyme that induces DNA demethylation,to verify the involvement of Hcy and DNA methylation in the regulation of BDNF expression and the development of stress-related cognitive *** data showed that TET1-expressing viral injection into the hippocampus inhibited BDNF promoter methylation and significantly mitigated the cognitive decline in HHcy *** together,novel evidence from the present study suggests that Hcy is likely involved in chronic stress-induced BDNF reduction and related cognitive *** addition,the negative side-effects of HHcy may be associated with Hcy-induced DNA hypermethylation in the BDN

关键词： Stress-associated cognitive decline Homocysteine DNA methylation BDNF

Design of a shielding collimator device for a small-angle monoenergetic neutron source

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Nuclear Science and Techniques 2018年第8期29卷 201-209页

作者： Wen-Hui Lü Hui-Ping Guo Ning Lü Kuo Zhao xiao-tian wang Yi-Jie Hou Xi'an Research Institute of Hi-Tech Xi'an 710025China Key Laboratory of Particle and Radiation Imaging(Ministryof Education)and Department of Engineering Physics Tsinghua UniversityBeijing 100083China

To obtain a small-angle monoenergetic neutron source,a shielding collimator device is designed for the neutron source generated by a neutron *** device is divided into the collimator and the capture *** collimator is made of three layers of stainless steel and borated polyethylene and is used to constrain neutrons in a small *** capture cave is used to increase the number of times neutron inelastic scattering occurs in the opposite direction of the radiation field,thereby reducing the proportion of scattered neutrons in the radiation *** thickness,aperture size,and the optimum structure of the capture cave were simulated using *** design features a neutron emission angle within a range of 3° and neutron fluxes in the radiation field,which are higher by two orders of magnitude than those outside the radiation *** research has practical value for the generation of monoenergetic small-angle neutron sources and neutron applications.

关键词：小角度中子设备设计防护不锈钢聚乙烯俘获

Three-dimensional topological insulators:case of quaternary Heusler compounds

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Rare Metals 2021年第5期40卷 1219-1223页

作者： xiao-tian wang Xue-Fang Dai Hong-Ying Jia Li-Ying wang Guo-Dong Liu Xi-Feng Liu Wen Yuan Yu-Ting Cui School of Material Sciences and Engineering Hebei University of TechnologyTianjin 300130China College of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082China Department of Chemistry Michigan State UniversityEast LansingMichigan 48824USA School of Physics and Electronic Engineering Chongqing Normal UniversityChongqing 400044China

The feasibility of converting quaternary Heusler compounds XX’MZ(X=Sc,La;X’=Sc,Y;M=Ru,Fe;Z=Pb)into three-dimensional topological insulators was investigated by first-principle *** is found that the topological insulating state can be achieved in these quaternary Heusler compounds by the proper strain engineering or the substitution of *** of these compounds investigated in this paper have a negative formation energy,which implies that they are possible to be synthesized in reality.

关键词： Topological insulator Heusler compound Electronic structure

Chemical derivatization strategies for enhancing the HPLC analytical performance of natural active triterpenoids

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Journal of Pharmaceutical Analysis 2024年第3期14卷 295-307页

作者： xiao-Feng Huang Ying Xue Li Yong tian-tian wang Pei Luo Lin-Sen Qing Chengdu Institute of Biology Chinese Academy of SciencesChengdu610041China State Key Laboratory for Quality Research in Chinese Medicines Macao University of Science and TechnologyMacaoChina Sichuan Center for Disease Control and Prevention Chengdu610041China University of Chinese Academy of Sciences Beijing100049China

Triterpenoids widely exist in nature,displaying a variety of pharmacological *** triterpenoids in different matrices,especially in biological samples holds great ***-performance liquid chromatography(HPLC)has become the predominant method for triterpenoids analysis due to its exceptional analytical ***,due to the structural similarities among botanical samples,achieving effective separation of each triterpenoid proves challenging,necessitating significant improvements in analytical ***,triterpenoids are characterized by a lack of ultraviolet(UV)absorption groups and chromophores,along with low ionization efficiency in mass ***,routine HPLC analysis suffers from poor *** derivatization emerges as an indispensable technique in HPLC analysis to enhance its *** the structural characteristics of triterpenoids,various derivatization reagents such as acid chlorides,rhodamines,isocyanates,sulfonic esters,and amines have been employed for the derivatization analysis of *** review comprehensively summarized the research progress made in derivatization strategies for HPLC detection of ***,the limitations and challenges encountered in previous studies are discussed,and future research directions are proposed to develop more effective derivatization methods.

关键词： Triterpenoid HPLC Derivatization Quantification

Numerical simulation on sand sedimentation and erosion characteristics around HDPE sheet sand barrier under different wind angles

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Journal of Mountain Science 2024年第2期21卷 538-554页

作者： ZHANG Kai ZHANG Peili ZHANG Hailong tian Jianjin wang Zhenghui xiao Jianhua College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

For the safety of railroad operations,sand barriers are utilized to mitigate wind-sand disaster *** disasters,characterized by multi-directional wind patterns,result in diverse angles among the *** this study,using numerical simulations,we examined the behavior of High Density Polyethylene(HDPE)sheet sand barriers under different wind angles,focusing on flow field distribution,windproof efficiency,and sedimentation erosion *** study discovered that at a steady wind speed,airflow velocity varies as the angle between the airflow and the HDPE barrier ***,a 90°angle results in the widest low-speed airflow area on the barrier’s downwind *** the airflow is not perpendicular to the barrier,it prompts a lateral airflow movement which decreases as the angle *** windproof efficiency correlates directly with this angle but inversely with the wind’s ***,with a wind angle of 90°,wind speed drops by 81%.The minimum wind speed is found at 5.1H(the sand barrier height)on the barrier’s downwind *** the angle grows,the barrier’s windproof efficiency improves,extending its protective *** is most prominent on the barrier’s downwind side,as the wind angle shifts from 30°to 90°,the sand sedimentation area on the barrier’s downwind side enlarges by *** the angle grows,sedimentation intensifies,eventually overtakes the forward erosion and enlarges the sedimentation area.

关键词： Multi-wind direction HDPE sheet sand barrier Numerical simulation Windproof efficiency Sedimentation erosion

Large-inductance superconducting microstrip photon detector enabling 10 photon-number resolution

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Advanced Photonics 2024年第1期6卷 96-105页

作者： Ling-Dong Kong tian-Zhu Zhang xiao-Yu Liu Hao Li Zhen wang xiao-Ming Xie Li-Xing You Chinese Academy of Sciences(CAS) Shanghai Institute of Microsystem and Information TechnologyNational Key Laboratory of Materials for Integrated CircuitsShanghaiChina CAS Center for Excellence in Superconducting Electronics ShanghaiChina University of Chinese Academy of Sciences Center of Materials Science and Optoelectronics EngineeringBeijingChina

Efficient and precise photon-number-resolving detectors are essential for optical quantum information *** this,very few detectors have been able to distinguish photon numbers with both high fidelity and a large dynamic range,all while maintaining high speed and high timing *** nanostrip-based detectors excel at counting single photons efficiently and rapidly,but face challenges in balancing dynamic range and ***,we have pioneered the demonstration of 10 true photon-number resolution using a superconducting microstrip detector,with readout fidelity reaching an impressive 98%and 90%for 4-photon and 6-photon events,***,our proposed dual-channel timing setup drastically reduces the amount of data acquisition by 3 orders of magnitude,allowing for real-time photon-number *** then demonstrate the utility of our scheme by implementing a quantum random-number generator based on sampling the parity of a coherent state,which guarantees inherent unbiasedness,robustness against experimental imperfections and environmental noise,as well as invulnerability to *** solution boasts high fidelity,a large dynamic range,and real-time characterization for photon-number resolution and simplicity with respect to device structure,fabrication,and readout,which may provide a promising avenue towards optical quantum information science.

关键词： superconducting microstrips single-photon detector photon-number resolution quantum random number

Quantum squeezing induced nonreciprocal phonon laser

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 20-30页

作者： tian-Xiang Lu Yan wang Keyu Xia Xing xiao Le-Man Kuang Hui Jing College of Physics and Electronic Information Gannan Normal UniversityGanzhou 341000China Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education Department of Physics and Synergetic Innovation Center for Quantum Effects and ApplicationsHunan Normal UniversityChangsha 410081China Academy for Quantum Science and Technology Zhengzhou University of Light IndustryZhengzhou 450002China College of Engineering and Applied Sciences National Laboratory of Solid State Microstructuresand Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing 210023China

Phonon lasers or coherent amplifications of mechanical oscillations are powerful tools for fundamental studies on coherent acoustics and hold potential for diverse applications,ranging from ultrasensitive force sensing to phononic information ***,we propose the use of an optomechanical resonator coupled to a nonlinear optical resonator for directional phonon *** find that by pumping the nonlinear optical resonator,directional optical squeezing can occur along the pump *** a result,we can achieve the directional mechanical gain using directional optical squeezing,thereby leading to nonreciprocal phonon lasing with a well-tunable directional power *** work proposes a feasible way to build nonreciprocal phonon lasers with various nonlinear optical media,which are important for a wide range of applications,such as directional acoustic amplifiers,invisible sound sensing or imaging,and one-way phononic networks.

关键词： nonreciprocal phonon laser directional quantum squeezing optomechanics