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Sy.thesis and characterization of Ca0.9Mg0.1TiO3：Pr3＋,Ag＋ phosphor

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Journal of Rare Earths 2018年第2期36卷 125-129页

作者： Rui chen Donghua chen College of Chemistry.and Chemical Engineering Yunnan Normal University Kunming 650500 China Hubei Key.Laboratory.for Cataly.is and Material Science College of Chemistry and Material Science South Central University for Nationalities Wuhan 430074 China

Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋）,Ag~＋ phosphors were sy.thesized by.solid-state reaction technique. The cry.talline phase and luminescence performances of Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋）,Ag~＋ were observed by.X-ray powder diffractometer（XRD）, transmission electron microscope（TEM）, photoluminescence spectrometer and brightness meter, respectively. The addition of Ag~＋ can diminish in the cry.tal particle sizes of Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋）. Because Ag＋ can reduce the concentration of the undesirable defects in the phosphor, luminescence intensity.of Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋）,Ag~＋ is 2.3 times as high as that of Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋）at the same preparation condition. The effect of Ag＋ on the persistent afterglow properties is to deepen the energy.storage traps and enhance the energy.transfer efficiency.from Ca_（0.9）Mg_（0.1）TiO_3 to Pr^（3＋）. The persistent afterglow properties of Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋）,Ag~＋ are better than those of Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋） at the same preparation condition. In conclusion,Ca_（0.9）Mg_（0.1）TiO_3：Pr^（3＋）,Ag~＋ phosphor with molar ratio of Ag~＋to Pr^（3＋） 3：1 obtained at 900 ℃ for 4 h exhibits the optimal photoluminescence performances.

关键词： Phosphor Transmission electron microscope Lumine scence X-ray diffraction Afterglow Rare earths

Optimal Design of Thermal Dissipation for the Array Power LED by.using the RSM with Genetic Algorithm

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Modeling and Numerical Simulation of Material Science 2013年第1期3卷 12-26页

作者： Rongsheng chen Hsin-En cheng Chihuang Huang ray-Wen Wu Department of Engineering Science National Cheng Kung University Tainan Chinese Taipei

In accordance with the enhancement for luminous efficiency.improving, LED (Light Emitting Diode) has been gradually.developed by.combining the characteristics of small volume, impact resistance, good reliability. long life, low power consumption with multiple purposes for energy.saving and environmental protection. Therefore, the array LED has been widely.applied in human livings nowaday.. This study.applies the finite element analy.is software ANSy. to analy.e the thermal behavior of the array power LED work lamp which is modeled by.four same-size LED with MCPCB (Metal Core Print Circuit Board) mounted on a base heat-sink. The Flotran heat flow analy.is is applied to obtain the natural convection of air coefficient, while the convection value can be confirmed by.the iterative method since it is set as the boundary.condition for ANSy. thermal analy.is to obtain the temperature distribution, accordingly.the chip junction temperature and the base heat-sink temperature were followed through experiments in order to check if the simulation results meet the design requirements and coincide with the power LED product design specification. Prior to the optimal design process for chip junction temperature, the most significant parameters were first chosen by.the fractional factorial design. The regressive models were respectively.setup by.the dual response surface method (RSM) and the mixed response surface method. Furthermore, the genetic algorithm combined with response surface method was applied to acquire the optimal design parameters, and the results were obtained from both methods, which are reviewed for comparison. Afterwards, the mixed response surface method is adopted to investigate the effects of interactions among various factors on chip junction temperature. In conclusion, it is found that the thermal conductivity.of MCPCB and the height of base heat-sink are the two major significant factors. In addition, the interactive effects between chip size and thermal co

关键词： Array Power Light Emitting Diode Fractional Factorial Design Response Surface Method Genetic Algorithm

Morphology.modulation of artificial muscles by.thermody.amic-twist coupling

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National Science Review 2023年第1期10卷 17-27页

作者： Xiaoy. Hu Jiatian Li Sitong Li Guanghao Zhang Run Wang Zhongsheng Liu Mengmeng chen Wenqian He Kaiqing y. Wenzhong Zhai Weiqiang Zhao Abdul Qadeer Khan Shaoli Fang ray H.Baughman Xiang Zhou Zunfeng Liu State Key.Laboratory.of Medicinal Chemical Biology College of Chemistry and College of Pharmacy Key Laboratory of Functional Polymer Materials Frontiers Science Center for New Organic MatterNankai University Alan G.Mac Diarmid Nano Tech Institute University of Texas at Dallas Department of Science China Pharmaceutical University

Human muscles can grow and change their length with body.development;therefore,artificial muscles that modulate their morphology.according to changing needs are *** this paper,we report a strategy.to transform an artificial muscle into a new muscle with a different morphology.by.thermody.amic-twist coupling,and illustrate its structural evolution during *** muscle length can be continuously.modulated over a large temperature range,and actuation occurs by.continuously.changing the *** strategy.is applicable to different actuation modes,including tensile elongation,tensile contraction and torsional *** is realized by.twist insertion into a fibre to produce torsional *** anne aling causes partial thermody.amic relaxation of the spiral molecular chains,which serves as internal tethering and inhibits fibre twist release,thus producing a self-supporting artificial muscle that actuates under *** a sufficiently.high temperature,further relaxation of the spiral molecular chains occurs,resulting in a new mus cle with a different length.A structural study.provides an understanding of the thermo dy.amic-twist *** work provides a new design strategy.for intelligent materials.

关键词： artificial muscle actuator twist functional fibres bio-mimetic thermody.amic-twist coupling smart materials

Studies of short-time and high-temperature annealing and magnetic property.of LaFe_(11.4)Si_(1.6) compound

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Acta Metallurgica Sinica(English Letters) 2011年第5期24卷 390-398页

作者： Xiang chen y.ngui chen y.ngbo TANG School of Materials Science and Engineering Sichuan University Chengdu 610065 China Department of Phy.ics and Electronic Informational Engineering Neijiang Teachers College Neijiang 641002 China

The LaFe11.4Si1.6 compounds are prepared by.arc-melting and then annealed at different high temperatures from 1323 K （5 h） to 1623 K （2 h）. The powder X-ray diffraction （XRD） and microstructure observations show that large amount of 1：13 phase begins to appear in the LaFe11.4Si1.6 compound annealed at 1423 K （5 h）. In the temperature range from 1423 K to 1523 K, the α-Fe and LaFeSi phases rapidly.decrease to form 1：13 phase. The LaFeSi phase is rarely.observed by.XRD when the as-cast compound is annealed at 1523 K （5 h）. With annealing temperature increasing to 1573 K, LaFeSi phase is detected again in LaFe11.4Si1.6 compound. In LaFe11.4Si1.6 compounds annealed at 1523 K （5 h）, at 1373 K （2 h）＋1523 K （5 h）, and 1523 K （7 h）＋1373 K （2 h）, the impurity.phases including small amount of α-Fe and LaFeSi phase reduce in turn. The magnetic measurement shows that LaFe11.4Si1.6 compounds annealed by.above three processes keep the first-order of magnetic transition behavior, and Tc are both at about 200 K. But the values of the maximal ASM（T, H） of has large difference, they.are 9.94, 12.66, and 13.96 J/（kg.K） under a magnetic field of 0- 2 T, respectively.

关键词： LaFe11.4Sil.6 compound Short-time and high-temperature an-nealing Phase transition Magnetic property

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基于电光聚合物材料的光圆偏振调制器的研制

光电子．激光 2003年第12期14卷 1258-1262页

作者：杨建义 ZHOU Qing-jun 江晓清王明华 ray T.chen 浙江大学信息与电子工程学系浙江杭州310027 DepartmentofElectrical&ComputerEngineering/MicroelectronicsResearchCenter

设计并研制了基于电光聚合物光波导的光圆偏振调制器(CPM)。所研制器件的TE TM偏振模式均衡器部分能够实现TE模与TM模间90%的偏振转换效率,这为器件输出光波的偏振分量均衡提供了相当大的调节范围。在均衡了波导中TE模与TM模的基础上,... 详细信息

设计并研制了基于电光聚合物光波导的光圆偏振调制器(CPM)。所研制器件的TE TM偏振模式均衡器部分能够实现TE模与TM模间90%的偏振转换效率,这为器件输出光波的偏振分量均衡提供了相当大的调节范围。在均衡了波导中TE模与TM模的基础上,实验表明,器件的TE TM相位差调制器部分实现了很好的光波圆偏振调制输出特性。所测得的输出线偏振光中,45°与-45°斜角方向偏振分量的消光比大于25dB。基于接触式电极化法所获得的电光特性,TE TM偏振模式均衡器部分的偏振转换周期电压约为230V,TE TM相位差调制器部分的调制特性曲线周期约为192V。

关键词：电光聚合物材料光圆偏振调制器光波导集成光学

Interface Structure of Ag/SnO_2 Nanocomposite Fabricated by.Reactive Sy.thesis

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Journal of Materials Science & Technology 2010年第1期26卷 49-55页

作者： Jingchao chen Jing Feng B. Xiao K.H. Zhang y.P. Du Z.J. Hong R. Zhou Key.Laboratory.of Advanced Materials of Precious-Nonferrous Metals Education Ministry of China and Key Lab of Advanced Materials of Yunnan Province Kunming University of Science and Technology Kunming 650093 China State Key.Laboratory.of Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 China

The electric contact material of Ag/SnO2 composite was achieved by.reactive sy.thesis method. The compositions and microstructure of Ag/SnO2 composite were analy.ed and characterized by.X-ray diffraction （XRD）, scanning electron microscopy.（SEM）, and high-resolution electron microscopy.（HRTEM）. The struc- tural feature was ty.ical of the particle reinforced composites. The HRTEM images revealed that the observed Ag/SnO2 interface was absence of the precipitated phase and the lattice contrast across the interface was clear and sharp. The average particle size of SnO2 in composite was near 50 nm and it was well dispersed in spherical shape. The thermody.amic mechanism of reactive sy.thesis method was also discussed. The electronic density.distribution analy.is of the interface showed the charges of Ag atoms transmitted to 0 atoms and the conductivity.of the material was also affected. No extra compounds expected such as AgxOy.formed at interface. The distribution of electrons was of inequality.near the interface which explained why.the mechanical property.of the metal/ceramic materials was improved but the machining property.declined.

关键词： Metal-matrix composites Electric contact material Interface In situ

Microstructures and mechanical properties of Ti3Al/Ni-based superalloy.joints brazed with AuNi filler metal

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Journal of Materials Science & Technology 2019年第9期35卷 2070-2078页

作者： H.S. Ren H.P.Xiong W.M. Long B. chen y.X. Shen J. Pang Welding and Plastic Forming Division Beijing Institutes of Aeronautical MatericalBeijing 100095China State Key.Laboratory.of Advanced Brazing Filler Metals and Technology Zhengzhou Research Institute of Mechanical EngineeringZhengzhou 450001 China Department of Material Science and Engineering Beihang UniversityBeijing 100191China

For the purpose of high-temperature service and the weight reduction in aviation engineering applications, the dissimilar joining of Ti3Al-based alloy.to Ni-based superalloy.(GH536) was conducted using Au-17.5Ni (wt%) brazing filler metal. The microstructure and chemical composition at the interfaces were investigated by.scanning electron microscope, X-ray diffraction and transmission electron microscope. The diffusion behaviors of elements were analy.ed as well. The results indicated that the Ti3Al/GH536 joint microstructure was characterized by.multiple lay.r structures. Element Ni from Au-Ni filler metal reacted with Ti3Al base metal, leading to the formation of AlNi2Ti and NiTi compounds. Element Ni from Ti3Al base metal reacted with Ni and thus Ni3Nb phase was detected in the joint central area. Due to the dissolution of Ni-based superalloy.(Ni,Au) solid solution ((Ni,Au)ss) and Ni-rich phase were visible adjacent to the superalloy.side. The average tensile strength of all the joints brazed at 1253 K for 5-20 min was above 356 MPa at room-temperature. In particular, the joints brazed at 1253 K/15 min presented the maximum tensile strength of434 MPa at room-temperature, and the strength of 314 MPa was maintained at 923 K. AlNi2Ti compound resulted in the highest hardness area and the fracture of the samples subjected to the tensile test mainly.occurred in this zone.

关键词： Ti3Al-based alloy Ni-based superalloy Brazing Microstructure Tensile strength

Diagnosis of pulmonary.tuberculosis among asy.ptomatic HIV＋ patients in Guangxi, China

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Chinese Medical Journal 2010年第23期123卷 3400-3405页

作者： ZHANG y.o y. Lan TANG Zhi-rong HUANG Shao-biao ZHENG y.an-jia MENG Zhi-hao SUN Kai WANG Li-ming ray y.chen ZHANG Fu-jie Division of Treatment and Care National Center for AIDS/STD Control and Prevention Chinese Center for Diseases Control and Prevention Beijing 100050 China Beijing Ditan Hospital Beijing 100015 China Provincial Center of Diseases Control and Prevention NaningGuangxi 53000 China Nanning 4th People's Hospital Nanning Guangxi 530000 China Center for Diseases Control and Prevention of Liuzhou City Liuzhou Guangxi 545000 China Liuzhou Longtan Hospital Liuzhou Guangxi 545000 China University.of North Carolina Chapel Hill USA Washington University.in St. Louis School of Medicine St. LouisUSA Global AIDS Program U.S. Centers for Disease Control andPrevention Beijing 100600 China The Office of Global Research National Institute of Allergy andInfectious Diseases US National Institutes of Health Beijing100600 Chin

Background Pulmonary.tuberculosis （PTB） among asy.ptomatic Chinese patients with HIV infection has not been investigated despite high tuberculosis burden in China. This study.was aimed to evaluate the prevalence, risk factors and clinical outcomes of PTB among asy.ptomatic patients with HIV/AIDS in Guangxi to facilitate the development of diagnostic and treatment *** All asy.ptomatic adult HIV-infected patients with CD4 ＜350 cells/μl who attended four HIV clinics in Guangxi between August 2006 and March 2008 were evaluated for active PTB with phy.ical examination, chest X-ray （CXR）,sputum smear and/or sputum liquid culture. Data were described using median （interquartile range, IQR） and *** and multivariate Logistic regression analy.es were performed to identify.risk factors associated with *** Among 340 asy.ptomatic subjects, 15 （4%） were diagnosed with PTB, with 4 （27%） sputum smear positive and 8 （53%） sputum culture positive. CXR has higher diagnostic sensitivity.（87%） than sputum smear （25%） and sputum culture （67%）, but lower specificity.（56%） compared with sputum smear （99%） and culture （100%）. In univariate analy.is,injection drug user, body.mass index （BMI）＜18 kg/m2, CD4 ＜50 cells/μl and presence of peripheral ly.phadenopathy.were associated with an increased risk of asy.ptomatic PTB, while in multivariate analy.is only.peripheral ly.phadenopathy.maintained statistical significance （OR=7.6, 95% CI 1.4-40）. Patients with negative smear and minor or no abnormalities on CXR had longer interval between screening and TB *** PTB was relatively.common in this group of HIV＋ asy.ptomatic Chinese patients. Diagnosis is challenging especially.where sputum culture is unavailable. These findings suggest that an enhanced evaluation for PTB needs to be integrated with HIV care in China and transmission prevention in China to control at both households and health care facilities, especially.for patients with fact

关键词： tuberculosis human immunodeficiency.virus diagnosis

Hot Deformation and Work Hardening Behavior of an Extruded Mg–Zn–Mn–y.Alloy

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Journal of Materials Science & Technology 2015年第12期31卷 1161-1170页

作者： N.Tahreen D.F.Zhang F.S.Pan X.Q.Jiang D.y.Li D.L.chen Department of Mechanical and Industrial Engineering Ryerson University College of Materials Science and Engineering Chongqing University National Engineering Research Center for Magnesium Alloy. Chongqing University Advanced Materials Research Center Chongqing Academy of Science and Technology Faculty.of Materials and Energy Southwest University Department of Chemical and Materials Engineering University of Alberta

The aim of this study.was to evaluate the strain hardening and hot deformation behavior of asextruded Mg-Zn-Mn （ZM31） magnesium alloy.with vary.ng y.contents （0.3, 3.2, and 6 wt%） via compression testing along the extrusion direction at room temperature, 200℃ and 300 ℃. Texture and phases were identified by.X-ray diffraction. Alloy.ZM31 ＋ 0.3y.consisted of a mixture of fine equiaxed grains and elon- gated grains with 1-phase （Mg3y.no）; alloy.ZM31 ＋ 3.2y.contained 1-phase and W-phase （Mg3y.Zn3）; alloy.ZM31 ＋ 6y.had long-period stacking-ordered （LPSO） X-phase （Mg12y.n） and Mg24y. particles. With increasing y.content the basal texture became weakened significantly. While alloy. ZM31 ＋ 0.3y.and ZM31 ＋ 3.2y.exhibited a skewed true stress-true stain curve with a three-stage strain hardening feature caused by.the occurrence of {1072} extension twinning, the true stress-true stain curve of alloy.ZM31 ＋ 6y.was normal due to the dislocation slip during compression. With increasing temperature the extent of skewness decreased. While the compressive y.eld stress, ultimate compressive stress, strain hardening exponent, and hardening capacity.all decreased as the temperature increased, the retention of the high- temperature deformation resistance increased with increasing y.content mainly.due to the presence of thermally.stable LPSO X-ohase.

关键词： Magnesium alloy y.trium effect Temperature effect Strain hardening I and W-phase LPSO X-phase