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Dielectric composites with a high and temperature-independent dielectric constant

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Journal of Advanced Ceramics 2012年第4期1卷 310-316页

作者： Xiaobing SHAN Lin ZHANG Xiqiao YANG Z-Y.CHENG materials research and education center Auburn UniversityAuburnAL 36849USA

Dielectric composites made using P(VDF-CTFE)88/12 mol%as polymer matrix and both micro-sized and nano-sized CaCu3Ti4O12(CCTO)particles as filler are *** composites exhibit high dielectric constant with a small dielectric *** importantly,it is found that the dielectric constant of these composites is almost independent of temperature from 25℃to 125℃.Comparing the composites made using micro-sized CCTO particles,the composites made using nano-sized CCTO particles exhibit a smaller dielectric *** dielectric properties of these composites indicate that the nano-sized CCTO particles have a smaller dielectric constant than the micro-sized CCTO particles.

关键词： dielectric constant composite CCTO P(VDF-CTFE) temperature dependence

Highly mass activity electrocatalysts with ultralow Pt loading on carbon black for hydrogen evolution reaction

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International Journal of Minerals,Metallurgy and materials 2025年第1期32卷 182-190页

作者： Shaorou Ke Yajing Zhao Xin Min Yanghong Li Ruiyu Mi Yangai Liu Xiaowen Wu Minghao Fang Zhaohui Huang Engineering research center of Ministry of education for Geological Carbon Storage and Low Carbon Utilization of Resources Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid WastersNational Laboratory of Mineral MaterialsSchool of Materials Science and TechnologyChina University of Geosciences(Beijing)Beijing 100083China

Pt-based nanocatalysts offer excellent prospects for various ***,the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable *** this study,nanocatalysts with ultralow Pt content,excellent performance,and carbon black as support were prepared through in-situ ***~2-nm particles uniformly and stably dispersed on carbon black because of the strong s-p-d orbital hybridizations between carbon black and Pt,which suppressed the agglomeration of Pt *** unique structure is beneficial for the hydrogen evolution *** catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction,exhibiting a potential of 100 mV at 100 mA·cm^(-2),which is comparable to those of commercial Pt/C *** activity(1.61 A/mg)was four times that of a commercial Pt/C catalyst(0.37 A/mg).The ultralow Pt loading(6.84wt%)paves the way for the development of next-generation electrocatalysts.

关键词： hydrogen evolution reaction ultralow platinum in-situ synthesis ultrasound

Physical aspects of 0-3 dielectric composites

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Journal of Advanced Dielectrics 2015年第2期5卷 53-60页

作者： Lin Zhang Patrick Bass Z.-Y.Cheng materials research and education center auburn university AuburnAL 36849USA

0-3 dielectric composites with high dielectric constants have received great interest for various technological *** achievements have been made in the development of high performance of 0-3 composites,which can be classified into dielectric–dielectric(DDCs)and conductor–dielectric composites(CDCs).However,predicting the dielectric properties of a composite is still a challenging problem of both theoretical and practical ***,the physical aspects of 0-3 dielectric composites are *** limitation of current understanding and new developments in the physics of dielectric properties for dielectric composites are *** is indicated that the current models cannot explain well the physical aspects for the dielectric properties of 0-3 dielectric *** the CDCs,experimental results show that there is a need to find new equations/models to predict the percolative behavior incorporating more parameters to describe the behavior of these *** the DDCs,it is indicated that the dielectric loss of each constituent has to be considered,and that it plays a critical role in the determination of the dielectric response of these types of *** differences in the loss of the constituents can result in a higher dielectric constant than both of the constituents combined,which breaks the Wiener limits.

关键词： 0-3 Composites dielectric properties model

Time-dependence of the electromechanical bending actuation observed in ionic-electroactive polymers

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Journal of Advanced Dielectrics 2017年第2期7卷 1-6页

作者： Patrick S.Bass Lin Zhang Z.-Y.Cheng materials research and education center Auburn UniversityAuburnAL 36849USA

The characteristics of the electromechanical response observed in an ionic-electroactive polymer(i-EAP)are represented by the time(t)dependence of its bending actuation(y).The electromechanical response of a typical i-EAP—poly(ethylene oxide)(PEO)doped with lithium perchlorate(LP)—is *** shortcomings of all existing models describing the electromechanical response obtained in i-EAPs are discussed.A more reasonable model:y=y_(max)^(e-T/t)is introduced to characterize this time dependence for all *** advantages and correctness of this model are confirmed using results obtained in PEO-LP actuators with different LP contents and at different *** applicability and universality of this model are validated using the reported results obtained from two different i-EAPs:one is Flemion and the other is polypyrrole actuators.

关键词： i-EAP PEO electromechanical response model

Copper homeostasis and neurodegenerative diseases

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Neural Regeneration research 2025年第11期20卷 3124-3143页

作者： Yuanyuan Wang Daidi Li Kaifei Xu Guoqing Wang Feng Zhang International research Laboratory of Ethnomedicine of Ministry of education Key Laboratory of Basic Pharmacology of Ministry of EducationLaboratory Animal Center and Key Laboratory of Basic Pharmacology of Guizhou ProvinceZunyi Medical UniversityZunyiGuizhou ProvinceChina

Copper,one of the most prolific transition metals in the body,is required for normal brain physiological activity and allows various functions to work normally through its range of *** homeostasis is meticulously maintained through a complex network of copper-dependent proteins,including copper transporters(CTR1 and CTR2),the two copper ion transporters the Cu-transporting ATPase 1(ATP7A)and Cu-transporting beta(ATP7B),and the three copper chaperones ATOX1,CCS,and *** in copper homeostasis can lead to either the deficiency or accumulation of copper in brain *** evidence suggests that abnormal copper metabolism or copper binding to various proteins,including ceruloplasmin and metallothionein,is involved in the pathogenesis of neurodegenerative ***,the exact mechanisms underlying these processes are not *** is a potent oxidant that increases reactive oxygen species production and promotes oxidative *** reactive oxygen species levels may further compromise mitochondrial integrity and cause mitochondrial *** oxygen species serve as key signaling molecules in copper-induced neuroinflammation,with elevated levels activating several critical inflammatory ***,copper can bind aberrantly to several neuronal proteins,including alphasynuclein,tau,superoxide dismutase 1,and huntingtin,thereby inducing neurotoxicity and ultimately cell *** study focuses on the latest literature evaluating the role of copper in neurodegenerative diseases,with a particular focus on copper-containing metalloenzymes and copper-binding proteins in the regulation of copper homeostasis and their involvement in neurodegenerative disease *** synthesizing the current findings on the functions of copper in oxidative stress,neuroinflammation,mitochondrial dysfunction,and protein misfolding,we aim to elucidate the mechanisms by which copper contributes to a wide range of heredit

关键词： Alzheimer's disease amyotrophic lateral sclerosis disease copper homeostasis copper toxicity Huntington's disease Menkes'disease multiple sclerosis neurodegenerative disease Parkinson's disease Wilson's disease

Robust interface and excellent as-built mechanical properties of Ti–6Al–4V fabricated through laser-aided additive manufacturing with powder and wire

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International Journal of Minerals,Metallurgy and materials 2025年第1期32卷 154-168页

作者： Fei Weng Guijun Bi Youxiang Chew Shang Sui Chaolin Tan Zhenglin Du Jinlong Su Fern Lan Ng Key Laboratory for Liquid-Solid Structural Evolution and Processing of materials Ministry of EducationShandong Engineering&Technology Research Center for Superhard MaterialSchool of Materials Science and EngineeringShandong UniversityJinan 250061China Institute of Intelligent Manufacturing Guangdong Academy of SciencesGuangzhou 510095China Singapore Institute of Manufacturing Technology 5 Cleantech Loop636732Singapore

The feasibility of manufacturing Ti-6Al-4V samples through a combination of laser-aided additive manufacturing with powder(LAAM_(p))and wire(LAAM_(w))was explored.A process study was first conducted to successfully circumvent defects in Ti-6Al-4V deposits for LAAM_(p) and LAAM_(w),*** the optimized process parameters,robust interfaces were achieved between powder/wire deposits and the forged substrate,as well as between powder and wire *** characterization results revealed the epitaxial prior β grains in the deposited Ti-6Al-4V,wherein the powder deposit was dominated by a finerα′microstructure and the wire deposit was characterized by lamellar α *** mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and *** mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications(AMS 6932)even without post heat *** fracture occurred within the interfacial area,further suggesting the robust *** findings of this study highlighted the feasibility of combining LAAM_(p) and LAAM_(w) in the direct manufacturing of Ti-6Al-4V parts in accordance with the required dimensional resolution and deposition rate,together with sound strength and ductility balance in the as-built condition.

关键词： laser-aided additive manufacturing powder deposition wire deposition interfacial characteristic mechanical behavior

Preparation of FeCoNi medium entropy alloy from Fe^(3+)-Co^(2+)-Ni^(2+)solution system

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International Journal of Minerals,Metallurgy and materials 2025年第1期32卷 92-101页

作者： Zongyou Cheng Qing Zhao Mengjie Tao Jijun Du Xingxi Huang Chengjun Liu Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of education) Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China Engineering research center of Frontier Technologies for Low-carbon Steelmaking(Ministry of education) Shenyang 110819China

In recent years,medium entropy alloys have become a research hotspot due to their excellent physical and chemical *** controlling reasonable elemental composition and processing parameters,the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower *** this paper,a FeCoNi medium entropy alloy precursor was prepared via sol-gel and coprecipitation methods,respectively,and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen *** phases and magnetic properties of FeCoNi medium entropy alloy were *** showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500℃.Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal *** alloy prepared by hydrogen reduction was uniform and showed a relatively high ***,the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.

关键词： medium entropy alloy sol-gel co-precipitation carbothermal hydrogen reduction

research status and prospects of the fractal analysis of metal material surfaces and interfaces

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International Journal of Minerals,Metallurgy and materials 2025年第1期32卷 20-38页

作者： Qinjin Dai Xuefeng Liu Xin Ma Shaojie Tian Qinghe Cui Beijing Advanced Innovation center for materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China Laboratory for Advanced materials Processing of Ministry of education University of Science and Technology BeijingBeijing 100083China School of Mechanical and Electrical Engineering Xinjiang Institute of EngineeringUrumqi 830023China

As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine *** analysis has been used to characterize the shapes of metal materials at various scales and *** methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and ***,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal *** the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear *** relationship between the fractal dimensions and properties of metal material surfaces and interfaces is *** from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be *** is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.

关键词： metal material surfaces and interfaces fractal analysis fractal dimension homogeneity

Electrocaloric devices part Ⅰ:Analytical solution of one-dimensional transient heat conduction in a multilayer electrocaloric system

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Journal of Advanced Dielectrics 2020年第6期10卷 19-28页

作者： Farrukh Najmi Wenxian Shen Lorenzo Cremaschi Z.-Y.Cheng materials research and education center Auburn University AuburnAL 36849USA Department of Mathematics and Statistics Auburn UniversityAuburnAL 36849USA Department of Mechanical Engineering Auburn University AuburnAL 36849USA

The analytical solution is reported for one-dimensional(1D)dynamic conduction heat transfer within a mulilayer system that is the typical structure of electrocaloric ***,the multilayer structure of typical electrocaloric devices is simplified as four layers in which two layers of electrocaloric materials(ECMs)are sandwiched between two semi infinite bodies representing the thermal sink and *** temperature of electrocaloric layers can be instantaneously changed by extemal electic field to establish the initial temperature *** analytical solution includes the temperatures in four bodies as a function of both time and location and heat flux through each of the three interfaces as a function of *** of these analytical solutions includes five infinite *** is proved that each of these series is convergent so that the sum of each series can be calculated using the first N terms of the *** formula for calculating the value of N is presented so that the simulation of an electrocaloric device,such as the temperature distribution and heat transferred from one body to another can be *** value of N is dependent on the thickness of electrocaloric material layers,the time of heat conduction,and thermal properties of the materials *** on a case study,it is concluded that the N is mostly less than 20 and barely reaches more than *** application of the analytical solutions for the simulation of real electrocaloric devices is discussed.

关键词： Thermal conduction multilayer structure electrocaloric effect heat pump