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A general and simple method for evaluating the electrical transport performance of graphene by the van der Pauw–Hall measurement

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Science Bulletin 2018年第22期63卷 1521-1526页

作者： Fangzhu Qing Yang Shu Linsen Qing Yuting Niu He Guo Shuyi Zhang Chunlin Liu Changqing Shen Wanli Zhang Samuel S.Mao Wenjuan Zhu Xuesong Li State Key Laboratory of Electronic Thin Films and Integrated Devices &School of Electronic Science and engineering University of Electronic Science and Technology of ChinaChengdu 610054China Chengdu Institute of Biology Chinese Academy of SciencesChengdu 610041China national engineering research center of electromagnetic radiation control materials University of Electronic Science and Technology of ChinaChengdu 610054China Institute of New Energy Shenzhen 518031China Department of Mechanical engineering University of California at BerkeleyBerkeleyCA 94720USA Department of Electrical and Computer engineering University of Illinois at Urbana-ChampaignUrbanaIL 61801USA

Expected for many promising applications in the field of electronics and optoelectronics, a reliable method for the characterization of graphene electrical transport properties is desired to predict its device performance or provide feedback for its synthesis.However, the commonly used methods of extracting carrier mobility from graphene field effect transistor or Hall-bar is time consuming, expensive, and significantly affected by the device fabrication process other than graphene itself.Here we reported a general and simple method to evaluate the electrical transport performance of graphene by the van der Pauw–Hall measurement.By annealing graphene in vacuum to remove the adsorbed dopants and then exposing it in ambient surroundings, carrier mobility as a function of density can be measured with the increase of carrier density due to the dopant re-adsorption from the surroundings.Further, the relationship between the carrier mobility and density can be simply fitted with a power equation to the first level approximation, with which any pair of measured carrier mobility and density can be normalized to an arbitrary carrier density for comparison.We experimentally demonstrated the reliability of the method, which is much simpler than making devices and may promote the standard making for graphene characterization.

关键词： Graphene Van der Pauw Hall Chemical vapor deposition (CVD)

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Omnidirectional Antenna Diversity System for High-Speed Onboard Communication

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engineering 2022年第4期8卷 72-79页

作者： Yongjian Zhang Yue Li Weiquan Zhang Zhijun Zhang Zhenghe Feng Department of Electronic engineering Tsinghua UniversityBeijing 100084China Beijing national research center for Information Science and Technology Tsinghua UniversityBeijing 100084China

In this article,an omnidirectional dual-polarized antenna with synergetic electromagnetic and aerodynamic properties is propounded for high-speed diversity systems.The propounded antenna comprises a probe-fed cavity for horizontally polarized radiation and a microstrip-fed slot for vertical polarization.Double-layer metasurfaces are properly designed as artificial magnetic conductor boundaries with direct metal-mountable onboard installation and compact sizes.An attached wedge-shaped block is utilized for windage reduction in hydrodynamics.The propounded antenna is fabricated for design verification,and the experimental results agree well with the simulated ones.For vertical polarization,the operating bandwidth is in the range of 2.37–2.55 GHz,and the realized gain variation in the azimuthal radiation pattern is 3.67 decibels(dB).While an impedance bandwidth in the range of 2.45–2.47 GHz and a gain variation of 3.71 dB are also achieved for horizontal polarization.A port isolation more than 33 dB is obtained in a compact volume of 0.247λ_(0)×0.345λ_(0)×0.074λ_(0),whereλ_(0)represents the wavelength in vacuum at the center frequency,wherein the wedge-shaped block is included.The propounded diversity antenna has electromagnetic and aerodynamic merits,and exhibits an excellent potential for high-speed onboard communication.

关键词： Antenna diversity system Aerodynamics electromagnetics Omnidirectional radiation High-speed onboard communication

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Heat Leakage Numerical Investigation of a Compound Parabolic ConcentratorPulsating Heat Pipe Solar Collector

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Journal of Thermal Science 2022年第5期31卷 1318-1326页

作者： XU Rongji CHEN Jingyan ZHANG Xiaohui WANG Ruixiang XU Shuhui Beijing engineering research center of Sustainable Energy and Buildings Beijing University of Civil Engineering and ArchitectureBeijing100044China

As a new type of equipment for solar medium temperature utilization, the compound parabolic concentrator-pulsating heat pipe solar collector(CPC-PHPSC) uses pulsating heat pipe(PHP) as an endotherm, which can realize efficient energy conversion. The design of proper concentration ratio of compound parabolic concentrator(CPC) ensures that the incident sunlight can be concentrated on the evaporator section surface of PHP without solar tracking system. The objective of the present work is to study the influence of solar radiation intensity, air speed, material thickness(glass and insulation board) and tilt angle on the thermal performance of the new collector, which is difficult to control in the experiment. The heat leakage process and characteristics of the CPC-PHPSC were numerically studied by establishing a 3D numerical model of the collector unit. The results show that the theoretical collector efficiency of CPC-PHPSC reaches 74.5%, which is consistent with the experimental results. During operation, the heat collection performance is the best when the tilt angle is 45° and the solar radiation intensity is 1000 W/m^(2), while the excessive air speed will increase the convective heat loss. Increasing the thickness of insulation board and glass has little effect on the collector efficiency.

关键词： solar collector CPC(Compound Parabolic Concentrator) pulsating heat pipe solar irradiation intensity glass thickness

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Enhancement of Swimming Endurance by Herbal Supplement M3P

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Chinese Journal of Integrative Medicine 2022年第8期28卷 725-729页

作者： CHU Chien-ming CHI Chih-wen HUANG Chih-hung CHEN Yu-jen Graduate Institute of Biochemical and Biomedical engineering National Taipei University of TechnologyTaipeiTaiwan10608China BioMedical Development center MacKay Memorial HospitalNew Taipei CityTaiwan25160China Department of Medical research MacKay Memorial HospitalNew Taipei CityTaiwan25160China Department of radiation Oncology MacKay Memorial HospitalTaipeiTaiwan10449China

Objective:To investigate the effect of M3P(containing Deer antler,Cordyceps sinensis,Rhodiola rosea,and Panax ginseng);an herbal remedy with the function of tonifying Kidney(Shen)and invigorating Spleen(Pi),replenishing qi and nourishing blood;on fatigue alleviation,endurance capacity and toxicity.Methods:Swimming with weight-loading of 24 male ICR mice was used to evaluate the endurance capacity,and fatiguerelated plasma biomarkers were determined.Mice were randomly assigned to control or M3P treatment groups with 6 mice for each group and were orally administered with M3P everyday for 8 weeks at doses 0,10,33 or 100 mg/kg.Swimming time to exhaustion was measured in a specialized water tank.Lliver and kidney functions,body weight,and hematological profile were determined to evaluate the safety and toxicity after long-term M3P administration.Results:M3P supplementation 100 mg/kg significantly increased swimming endurance time up to approximate 2.4 folds of controls(P0.05).The liver and kidney functions muscle damage biomarker creatine,body weight,and hemograms were not altered in M3P supplementation(P>0.05).Conclusion:M3P supplementation may improve swimming endurance accompanied by increasing hepatic glycogen content and serum cortisol level without major toxicity.

关键词： swimming endurance fatigue tonifying Kidndy(Shen)and invigorating Spleen(Pi) replenishing qi and nourishing blood M3P mice Chinese medicine

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织构与磁体积效应协同作用诱导Mn_(x)Fe_(5-x)Si_(3)合金产生二维零热膨胀

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Science China materials 2022年第7期65卷 1912-1919页

作者：余成意林鲲曹宜力李文杰 Yan Chen Ke An Chin-Wei Wang Kenichi Kato 李强邓金狭邢献然 Beijing Advanced Innovation center for materials Genome engineering Institute of Solid State ChemistryDepartment of Physical ChemistryUniversity of Science and Technology BeijingBeijing 100083 Neutron Scattering Division Oak Ridge National LaboratoryOak RidgeTN 37831 Neutron Group National Synchrotron Radiation Research CenterHsinchu 30076 RIKEN SPring-8 center Hyogo 679-5148

零热膨胀合金在精密控制工程中具有独特的应用.然而,实现零热膨胀的苛刻条件,即自旋、晶格和电荷之间存在的适当耦合,使得零热膨胀合金的种类稀少.在这项工作中,我们报告了一种在体积表现为正热膨胀合金中,通过调节晶体学取向和磁体积... 详细信息

零热膨胀合金在精密控制工程中具有独特的应用.然而,实现零热膨胀的苛刻条件,即自旋、晶格和电荷之间存在的适当耦合,使得零热膨胀合金的种类稀少.在这项工作中,我们报告了一种在体积表现为正热膨胀合金中,通过调节晶体学取向和磁体积效应来实现二维零热膨胀行为的途径.基于此,我们在MnFe4Si3中获得了宽温度区间(10-310 K)的具有热膨胀系数α_(1)=0.45×10^(-7)K^(-1)的二维零热膨胀合金.同步加速器X射线衍射、中子衍射、电镜和磁性测试的结果表明,这种零热膨胀行为由6g位置上的Fe在a-b面内的磁矩以及块体织构共同决定.此外,Mn_(1.5)Fe_(3.5)Si_(3)和Mn_(2)Fe_(3)Si_(3)化合物表现出混磁性和负热膨胀行为,这起源于Fe_(4d)-Fe_(6g)(J_(FM))铁磁性和Mn_(4d)-Mn_(6g)(J_(AFM))反铁磁性相互作用之间的竞争.这种方法能够扩展到其他磁性或铁电材料中,以设计新的低膨胀或负膨胀块体材料.

关键词： zero thermal expansion crystallographic texture microstructure magneto-volume effect

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Moiré-driven electromagnetic responses and magic angles in a sandwiched hyperbolic metasurface

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Photonics research 2022年第9期10卷 2056-2065页

作者： YI LIU CHUNMEI OUYANG QUAN XU XIAOQIANG SU QUANLONG YANG JIAJUN MA YANFENG LI ZHEN TIAN JIANQIANG GU LIYUAN LIU JIAGUANG HAN YUNLONG SHI WEILI ZHANG center for Terahertz Waves and College of Precision Instrument and Optoelectronics engineering Key Laboratory of Optoelectronic Information Technology(Ministry of Education of China)Tianjin UniversityTianjin 300072China Institute of Solid State Physics College of Physics and Electronic ScienceShanxi Province Key Laboratory of Microstructure Electromagnetic Functional MaterialsShanxi Datong UniversityDatong 037009China Nonlinear Physics Centre Australian National UniversityCanberraACT 2601Australia School of Electrical and Computer engineering Oklahoma State UniversityStillwaterOklahoma 74078USA

Recent moiréconfigurations provide a new platform for tunable and sensitive photonic responses,as their enhanced light–matter interactions originate from the relative displacement or rotation angle in a stacking bilayer or multilayer periodic array.However,previous findings are mostly focused on atomically thin condensed matter,with limitations on the fabrication of multilayer structures and the control of rotation angles.Structured microwave moiréconfigurations are still difficult to realize.Here,we design a novel moiréstructure,which presents unprecedented capability in the manipulation of light–matter interactions.Based on the effective medium theory and S-parameter retrieval process,the rotation matrix is introduced into the dispersion relation to analyze the underlying physical mechanism,where the permittivity tensor transforms from a diagonal matrix to a fully populated one,whereas the permeability tensor evolves from a unit matrix to a diagonal one and finally becomes fully filled,so that the electromagnetic responses change drastically as a result of stacking and rotation.Besides,the experiment and simulation results reveal hybridization of eigenmodes,drastic manipulation of surface states,and magic angle properties by controlling the mutual rotation angles between two isolated layers.Here,not only a more precisely controllable bilayer hyperbolic metasurface is introduced to moiréphysics,the findings also open up a new avenue to realize flat bands at arbitrary frequencies,which shows great potential in active engineering of surface waves and designing multifunctional plasmonic devices.

关键词： rotation hyperbolic diagonal

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Enhanced electromagnetic Interference Shielding of Mg–Zn–Zr Alloy by Ce Addition

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Acta Metallurgica Sinica(English Letters) 2015年第4期28卷 492-498页

作者： Xian-Hua Chen Li-Zi Liu Juan Liu Fu-Sheng Pan College of materials Science and engineering Chongqing University national engineering research center for Magnesium Alloys Chongqing University Chongqing Academy of Science and Technology

The effects of Ce addition on microstructure and electromagnetic interference （EMI） shielding response of Mg- 6Zn-0.5Zr （ZK60） alloy have been investigated. Ce addition resulted in grain refinement and higher density of Mg-Zn-Ce and MgZn2 intermetallic particles in the alloy. In particular, this was substantially remarkable as the addition of Ce was up to 1.0 wt%. It is interesting to note that as-extruded ZK60 alloy with 1.0 wt% Ce addition exhibited an EMI shielding effectiveness （SE） exceeding 70 dB at the frequency range of 30-1,500 MHz, which was significantly higher than that of ZK60 alloy without Ce addition and reached the requirement of high protection. The superior SE was probably related to the increased reflection and multiple reflection of electromagnetic radiation induced by Ce addition. Direct artificial aging at 150 ℃ for 25 or 50 h led to a further increase of 7-10 dB in the SE of the alloy with 1.0 wt% Ce addition. The advantages of excellent shielding capacity and favorable mechanical strength make the Mg-Zn-Zr-Ce alloy an attractive shielding candidate material for a variety of technological applications.

关键词： Magnesium alloys Ce Shielding effectiveness electromagnetic interference Intermetallicparticles

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A new Chinese standard for testing of quality control in medical proton/heavy ion beam radiotherapy equipment

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radiation Medicine and Protection 2023年第4期4卷 177-181页

作者： Jilong Yuan Xiangjie Ma Quanfu Sun Haikuan Liu Shouping Xu Yinxiangzi Sheng Xiaoyun Ma Xiangkui Mu Xinguo Liu Tao Yang Xin Zhang Hsiao-Ming Lu Jinsheng Cheng Key Laboratory of Radiological Protection and Nuclear Emergency China CDCNational Institute for Radiological ProtectionChinese Center for Disease Control and PreventionWHO Collaboration Center for Radiation and HealthBeijing 100088China Institute of radiation Medicine Fudan UniversityShanghai 200032China national Cancer center/national Clinical research center for Cancer/Cancer Hospital Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021China Department of Medical Physics Shanghai Proton and Heavy Ion center Shanghai Engineering Research Center of Proton and Heavy Ion Radiation TherapyShanghai 201315China Heavy Ion center of Wuwei Cancer Hospital Gansu Wuwei Academy of Medical SciencesGansu Wuwei Tumor HospitalWuwei 733000China Department of radiation Oncology Shandong Cancer Hospital and InstituteShandong First Medical University and Shandong Academy of Medical SciencesJinan 250117China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Department of radiation Oncology The First Medical Center of Chinese PLA General HospitalBeijing 100853China Varian Medical Systems China Co. LtdBeijing 100176China Hefei Ion Medical center Hefei230088China Ion Medical research Institute University of Science and Technology of ChinaHefei 230088China

With the development of social economy and radiotherapy technique,proton/heavy ion radiotherapy has been applied widely to clinical practices.At present,there are at least 29 hospitals in China at various stages of planning,construction,commissioning or clinical operation of medical proton/heavy ion beam radiotherapy equipment.Compared with common radiotherapy accelerators used in conventional external beam radiotherapy,the proton/heavy ion therapy system has more stringent requirements for quality control so as to achieve an optimum therapeutic effect.In order to protect the health rights of patients undergoing radiotherapy,to facilitate the relevant administrative supervision departments to carry out standard-based approval and routine supervision and to promote the development of related medical undertakings,the standard for testing of quality control for medical proton/heavy ion beam radiotherapy equipment is drafted to fill the gap in this regard in China and even worldwide.The standard contains five indicators and corresponding testing methods for radiological protection and safety and 16 indicators for quality control of equipment performance.The standard is a mandatory standard and is based on the relevant Chinese legal requirements for the testing of radiotherapy equipment,so all the indicators listed in the standard shall be tested.During the drafting of the standard,the opinions from hospitals that are currently using proton/heavy ion medical accelerators for radiotherapy purpose and from the related equipment manufacturers were taken into account.The draft standard was revised with reference to these opinions and the feasibility of the related quality control requirements.The official version of the standard was released on March 7,2023,and implementation is scheduled to begin on March 1,2024.

关键词： Chinese standard Proton Heavy ion Radiotherapy Quality control

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Synthesis of Spherical (Y,Gd)BO_3:Eu^(3+)Phosphor Using W/O Emulsion System

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Journal of Rare Earths 2006年第6期24卷 719-723页

作者：崔向中庄卫东张熙莹夏天龙震鱼志坚赵春雷黄小卫 national engineering research center for Rare Earth materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd. Beijing 100088 China

Spherical （Y, Gd）BO3：Eu^3＋ phosphor particles with a narrow size distribution（2 -4 μm） was obtained by firing the Y-Gd-Eu-BO3 precursor prepared in a W/O style emulsion system. In the W/O emulsion system, kerosene, used as oil phase, was mixed with Span 80 and Tween 80 compounds which were employed as the emulsifier with an HLB （hydrophile-lipophile balance） value of 5.2- 5.3. Both rare earths （Y, Gd and Eu） nitrate and boric acid solution or ammonia solution were used as aqueous phase. The synthesis conditions, such as emulsion composition, emulsifying style, precipitation reaction process, reaction temperature, morphology control, and so on, were investigated, and the optimum synthesis conditions for preparing spherical （Y, Gd）BO3：Eu^3＋ phosphor was obtained. The phosphor was characterized by XRD, SEM, laser particle size analysis, emission and excitation spectrum under vacuum ultraviolet （VUV）, and so on. The phosphor synthesized using the water-in-oil emulsion method with median diameter （D50） of 2 - 4 μm shows agreeable photoluminescence （PL） property and sphericity. The main emission peak appears at about 593 nm, which corresponds to ^5D0→^7F1 transition （magnetic-dipole transition） of the Eu^3＋ ion. The cell parameters and powder diffraction data were indexed. The structure of the phosphor belongs to the hexagonal system with space group P63/m.

关键词： emulsion W/O PDP phosphor photoluminescence （PL） property VUV rare earths

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Isolation of ^(212)Pb from natural thorium for targeted alpha-therapy

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Chinese Chemical Letters 2022年第7期33卷 3474-3477页

作者： Junyi Chen Mengxin Xu Yu Liu Dongban Duan Yuxiang Han Zhibo Liu Beijing national Laboratory for Molecular Sciences Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental ScienceCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China Peking-Tsinghua center for Life Sciences Peking UniversityBeijing 100871China

Targeted alpha-therapy(TAT) is increasingly attractive due to its extraordinary antitumor efficacy.However,the supply of α-emitters for TAT is insufficient and under control by a limited number of countries.^(212)Pb is a promising α-emitter with an optimal half-life(10.6 h) and favored decay chain.Of interest,^(212)Pb can be extracted directly from natural thorium,which may be abundant in the mining waste of rare-earth,uranium,etc.Indeed,radioactive thorium waste has been a longstanding environmental challenge that needs immediate action.Developing an on-demand and facile process to isolate ^(212)Pb from natural thorium would be ideal to meet the above challenges,yet is difficult.In theory,the ratio of ^(212)Pb tonatTh is below 10^(-13)in commercially available thorium salts.As a pilot study,2.2 MBq of ^(212)Pb was successfully extracted from a 5 L solution of thorium nitrate by using a Pb-selective resin.The radiochemical purity of ^(212)Pb is over 99.9% according to gamma-ray analysis.The purified^(212)Pb was applied to radiolabel a couple of peptides used in clinics(i.e.PSMA,TATE and FAPI-04),and the radiochemical yields are>85%.Of note,^(212)Pb can be repeatedly separated from the thorium solution every 2 days.In summary,a practical and scalable method was developed to isolate^(212)Pb for potentially clinical use,which may be of great importance as it does not require either cyclotron or nuclear reactor.

关键词： ^(212)Pb Targeted alpha-therapy Radiolabeling Radionuclide generator Solid-phase extraction

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