检索结果-南通市图书馆

Enabling highly efficient and broadband electromagnetic wave absorption by tuning impedance match in high-entropy transition metal diborides (HETMB_(2))

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2021年第6期10卷 1299-1316页

作者： Weiming ZHANG Fu-Zhi DAI Huimin XIANG Biao ZHAO Xiaohui WANG Na NI Rajamallu KARRE Shijiang WU yanchun zhou Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Henan Key Laboratory of Aeronautical Materials and Application Technology School of Material Science and EngineeringZhengzhou University of AeronauticsZhengzhou 450046China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Lab of Education Ministry for Power Machinery and Engineering School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Zibo Firststar New Material Incorporated Co. Ltd.Zibo 255000China

The advance in communication technology has triggered worldwide concern on electromagnetic wave pollution.To cope with this challenge,exploring high-performance electromagnetic(EM)wave absorbing materials with dielectric and magnetic losses coupling is urgently required.Of the EM wave absorbers,transition metal diborides(TMB2)possess excellent dielectric loss capability.However,akin to other single dielectric materials,poor impedance match leads to inferior performance.High-entropy engineering is expected to be effective in tailoring the balance between dielectric and magnetic losses through compositional design.Herein,three HE TMB2 powders with nominal equimolar TM including HE TMB2-I(TM=Zr,Hf,Nb,Ta),HE TMB2-2(TM=Ti,Zr,Hf,Nb,Ta),and HE TMB2-3(TM=Cr,Zr,Hf,Nb,Ta)have been designed and prepared by one-step boro/carbothermal reduction.As a result of synergistic effects of strong attenuation capability and impedance match,HE TMB2-1 shows much improved performance with the optimal minimum reflection loss(RL_(min))of-59.6 dB(8.48 GHz,2.68 mm)and effective absorption bandwidth(EAB)of 7.6 GHz(2.3 mm).Most impressively,incorporating Cr in HE TMB2-3 greatly improves the impedance match over 1-18 GHz,thus achieving the RLmin of-56.2 dB(8.48 GHz,2.63 mm)and the EAB of 11.0 GHz(2.2 mm),which is superior to most other EM wave absorbing materials.This work reveals that constructing high-entropy compounds,especially by incorporating magnetic elements,is effectual in tailoring the impedance match for highly conductive compounds,i.e.,tuning electrical conductivity and boosting magnetic loss to realize highly efficient and broadband EM wave absorption with dielectric and magnetic coupling in single-phase materials.

关键词： transition metal diboride(TMB2) high-entropy(HE)ceramics electronic structure microwave absorption dielectric and magnetic losses coupling

在线全文

学校读者我要写书评

暂无评论

乳酸调控巨噬细胞功能促进登革病毒2型感染

中华微生物学和免疫学杂志 2024年第5期44卷 396-405页

作者：胡欢覃燕春黄贞植周璐吴家红商正玲贵州医科大学基础医学院免疫学教研室安顺550025 贵州医科大学基础医学院寄生虫教研室安顺550025

目的探究外源性乳酸对Raw264.7细胞、小鼠骨髓来源巨噬细胞(mouse bone marrow-derived macrophages,BMDMs)及THP-1细胞中登革病毒2型(dengue virus type 2,DENV-2)复制的影响及乳酸与细胞活化之间的关系。方法培养和诱导BALB/c小鼠骨... 详细信息

目的探究外源性乳酸对Raw264.7细胞、小鼠骨髓来源巨噬细胞(mouse bone marrow-derived macrophages,BMDMs)及THP-1细胞中登革病毒2型(dengue virus type 2,DENV-2)复制的影响及乳酸与细胞活化之间的关系。方法培养和诱导BALB/c小鼠骨髓中的BMDMs,流式细胞术检测F4/80+CD11b+细胞纯度。qRT-PCR检测不同时间点DENV-2感染BMDMs中葡萄糖转运体1(glucose transporter type 1,GLUT1)、己糖激酶2(hexokinase 2,HK2)、乳酸转运体4(monocarboxylate transporters 4,MCT4)的mRNA表达水平,比色法检测细胞上清液中乳酸含量。使用CCK-8法评估不同浓度乳酸对Raw264.7细胞、BMDMs及THP-1细胞活力的影响,qRT-PCR检测不同浓度乳酸对不同MOI DENV-2感染细胞中病毒E基因、CD163、TGF-β、CD86、视黄酸诱导基因Ⅰ(retinoic acid-inducible geneⅠ,RIG-Ⅰ)、IFN-β、干扰素刺激基因15(interferon-stimulated gene 15,ISG15)及ISG56的mRNA表达水平,流式细胞术检测CD86和CD206蛋白的表达。结果BMDMs纯度为(87.53±1.66)%。DENV-2(MOI=3)感染BMDMs后,GLUT1 mRNA转录水平在12 h一过性增高,在24 h降低(P0.05)。结论本研究发现外源性乳酸能促进DENV-2在人源及鼠源巨噬细胞中的感染,该现象与细胞M2型极化有关。

关键词：乳酸巨噬细胞登革病毒病毒复制 M2型极化干扰素信号通路

(Ca,Sr,Ba)ZrO_(3):A promising entropy-stabilized ceramic for titanium alloys smelting

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第6期65卷 82-88页

作者： Shuaihang Qiu Mingliang Li Gang Shao Hailong Wang Jinpeng Zhu Wen Liu Bingbing Fan Hongliang Xu Hongxia Lu yanchun zhou Rui Zhang School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Zhengzhou University of Aeronautics Zhengzhou 450046China

A novel entropy-stabilized(ES)(Ca,Sr,Ba)ZrO_(3) ceramic has been designed and synthesized by pressureless sintering of CaZr03,SrZr03 and BaZr03 powders mixtures at 1450℃,1500℃and 1550℃for 3 h.X-ray diffraction,scanning electron microscopy and transmission electron microscopy analyses collectively indicate that a single solid solution is formed with a homogeneous distribution of metal elements after sintering at 1550℃.The relative density and hardness of the ES(Ca,Sr,Ba)ZrO_(3) ceramic sintered at 1550℃are 97.79%and 10.840.33 GPa,re s pectively.This ES(Ca,Sr,Ba)ZrO_(3) exhibits lower thermal conductivity from 373 K to 1073 K than their constituting zirconates,CaZrO_(3),SrZrO_(3) and BaZrO_(3).Most importantly,the ES(Ca,Sr,Ba)ZrO_(3) ceramic possesses good corrosion resistance to TiNi alloy melt and no distinct reaction layer exists between TiNi alloy and ES(Ca,Sr,Ba)ZrO_(3) ceramic in the contact region.The combination of these properties indicates that ES(Ca,Sr,Ba)ZrO_(3) ceramic is promising for use as a novel crucible material for the melting of titanium alloys.

关键词： Entropy-stabilized ceramics (Ca Sr Ba)ZrO_(3) Corrosion resistance Pressureless sintering Thermal conductivity

超声处理对山羊奶酪蛋白理化和功能特性的影响

在线全文

学校读者我要写书评

暂无评论

食品工业科技 2024年第11期45卷 118-124页

作者：李金李蕾戴智勇张岩春罗洁刘成国周辉湖南农业大学食品科学技术学院湖南长沙410128 澳优乳业(中国)有限公司湖南长沙410005 湖南羴牧营养品科技有限公司湖南邵阳422500

以山羊奶酪蛋白为原料,利用不同强度超声处理山羊奶酪蛋白,探究超声处理对山羊奶酪蛋白的pH和电导率、Zeta电位、浊度等理化指标以及乳化性和起泡性等功能特性的影响。结果表明,与未处理相比,超声处理后山羊奶酪蛋白pH下降,电导率变化... 详细信息

以山羊奶酪蛋白为原料,利用不同强度超声处理山羊奶酪蛋白,探究超声处理对山羊奶酪蛋白的pH和电导率、Zeta电位、浊度等理化指标以及乳化性和起泡性等功能特性的影响。结果表明,与未处理相比,超声处理后山羊奶酪蛋白pH下降,电导率变化不显著(P>0.05);Zeta电位绝对值在400 W处理2 min时达到最大值27.85±1.55 mV;浊度值与未处理相比显著性降低(P<0.05);与未处理相比,超声处理可以减小蛋白平均粒径,并在700 W处理6 min时达到最低值,由383.20±13.07 nm减少至176.17±4.28 nm;扫描电镜结果表明超声改变了酪蛋白原有表观形态,导致不规则碎片的产生;超声处理后的酪蛋白乳化性在100 W处理10 min时提高了41.44%。在400 W处理10 min时起泡性和泡沫稳定性显著增加(P<0.05),分别达到最大值32.88%±0.07%和91.93%±0.19%。综上,超声处理产生的空化效应以及机械作用可以为山羊奶酪蛋白提供更好的理化特性和功能特性。

关键词：超声处理理化特性功能特性山羊奶酪蛋白

Theoretical prediction,synthesis,and crystal structure determination of new MAX phase compound V2SnC

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2020年第4期9卷 481-492页

作者： Qiang Xu yanchun zhou Haiming Zhang Anna Jiang Quanzheng Tao Jun Lu Johanna Rosén Yunhui Niu Salvatore Grasso Chunfeng Hu Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu610031China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing100076China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China Thin Film Physics Division Department of PhysicsChemistryand Biology(IFM)Linköping UniversityLinköpingSE-58183Sweden State Key Laboratory of Environment-friendly Energy Materials Southwest University of Science and TechnologyMianyang621010China

Guided by the theoretical prediction,a new MAX phase V2SnC was synthesized experimentally for the first time by reaction of V,Sn,and C mixtures at 1000°C.The chemical composition and crystal structure of this new compound were identified by the cross-check combination of first-principles calculations,X-ray diffraction(XRD),energy dispersive X-ray spectroscopy(EDS),and high resolution scanning transmission electron microscopy(HR-STEM).The stacking sequence of V2C and Sn layers results in a crystal structure of space group P63/mmc.The a-and c-lattice parameters,which were determined by the Rietveld analysis of powder XRD pattern,are 0.2981(0)nm and 1.3470(6)nm,respectively.The atomic positions are V at 4f(1/3,2/3,0.0776(5)),Sn at 2d(2/3,1/3,1/4),and C at 2a(0,0,0).A new set of XRD data of V2SnC was also obtained.Theoretical calculations suggest that this new compound is stable with negative formation energy and formation enthalpy,satisfied Born-Huang criteria of mechanical stability,and positive phonon branches over the Brillouin zone.It also has low shear deformation resistance c44(second-order elastic constant,cij)and shear modulus(G),positive Cauchy pressure,and low Pugh’s ratio(G/B=0.500<0.571),which is regarded as a quasi-ductile MAX phase.The mechanism underpinning the quasi-ductility is associated with the presence of a metallic bond.

关键词： V2SnC new MAX phase compound crystal structure first-principles calculations

(Y0.25Yb0.25Er0.25Lu0.25)2(Zr0.5Hf0.5)2O7: A defective fluorite structured high entropy ceramic with low thermal conductivity and close thermal expansion coefficient to Al2O3

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第4期39卷 167-172页

作者： Zifan Zhao Heng Chen Huimin Xiang Fu-Zhi Dai Xiaohui Wang Wei Xu Kuang Sun Zhijian Peng yanchun zhou School of Engineering and Technology China University of GeosciencesBeijing 100083China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Shanghai Chenhua Science and Technology Corporation Limted Shanghai 201804China

Al2O3f/Al2O3 ceramic matrix composites(CMC)are promising candidate materials of blades and combustor liners of future gas turbines in light of their higher temperature capability,higher environmental stability and oxidizing-free capacity[1–3].Nevertheless,grain growth,sintering and creep deformation at high operation temperatures are still serious problems for Al2O3f/Al2O3 ceramic matrix composites,which can lead to a reduction in the strength and damage tolerance[2].Moreover,Al2O3 can be corroded by the high temperature water vapor in combustion environments and yields volatile products,such as Al(OH)3[4].Consequently,environmental barrier coatings(EBCs)are necessary for Al2O3f/Al2O3 ceramic matrix composites,which can protect Al2O3f/Al2O3 CMC from high temperature and flowing combustion gas corrosion and thus increase the high temperature capability and the service life of components.

关键词： Al2O3f/Al2O3 ceramic matrix conductivity close thermal expansion

C&T和政府补贴下的绿色技术选择与产品定价研究

在线全文

学校读者我要写书评

暂无评论

中国管理科学 2024年第2期32卷 99-107页

作者：潘燕春马晓晨深圳大学管理学院广东深圳518060 深圳大学中国经济特区研究中心广东深圳518060

本文以碳排放总量控制与交易(C&T)为政策背景,通过构建政府福利最大化与控排企业利润最大化的Stackelberg博弈模型,探讨政府不同补贴方式(单位产品补贴和绿色技术成本补贴)下控排企业绿色技术选择以及产品定价决策,并进一步分析不同政... 详细信息

本文以碳排放总量控制与交易(C&T)为政策背景,通过构建政府福利最大化与控排企业利润最大化的Stackelberg博弈模型,探讨政府不同补贴方式(单位产品补贴和绿色技术成本补贴)下控排企业绿色技术选择以及产品定价决策,并进一步分析不同政府补贴方式对控排企业碳排放以及社会福利的影响。研究结果表明:与绿色技术成本补贴相比,单位产品补贴下的最优价格更高,而且会导致更多的绿色生产和消费。而绿色技术成本补贴下的碳排放更低,企业利润更高;政府补贴总预算相同时,绿色技术成本补贴更有可能激励企业投资绿色技术。研究结果也表明,政府补贴并不能保证控排企业投资绿色技术和总碳排放减少,而是取决于绿色技术成本的范围、碳减排率以及控排企业的碳排放强度。此外,单位产品补贴下的社会福利要优于绿色技术成本补贴下的社会福利。数值实验验证了本文的有关研究结果。最后给出了政府补贴政策的相关建议。

关键词： C&T 政府补贴定价绿色消费偏好绿色技术选择

政府回应性、政治支持与政治参与的影响关系——基于济世兴邦政治价值观的调节分析

在线全文

学校读者我要写书评

暂无评论

厦门大学学报（哲学社会科学版） 2024年第2期74卷 37-48页

作者：郑建君高妍春中国社会科学院大学政府管理学院北京102488 中国社会科学院政治学研究所北京100732

制度化政治参与是推进国家治理体系与治理能力现代化的应有之义和必然要求,而政府的回应性对公众制度化政治参与具有重要的影响作用。但是,既有文献对于政府回应性在何种条件下如何影响公民政治参与这一问题的分析和讨论仍相对缺乏。基... 详细信息

制度化政治参与是推进国家治理体系与治理能力现代化的应有之义和必然要求,而政府的回应性对公众制度化政治参与具有重要的影响作用。但是,既有文献对于政府回应性在何种条件下如何影响公民政治参与这一问题的分析和讨论仍相对缺乏。基于公共选择理论和自我决定理论,构建政府回应性与公众政治参与之间的理论模型,并运用31个省(自治区、直辖市)的11000份有效数据,通过结构方程模型和Bootstrap法对其进行检验,研究结果显示:政府回应性正向影响公民政治参与,政治支持在政府回应性与政治参与影响关系中发挥中介效应,济世兴邦政治价值观反向调节政府回应性与政治支持的影响关系;政治支持在政府回应性对公民政治参与影响关系中的中介作用受到个体济世兴邦政治价值观的反向调节影响。从“政府行为—公民体验”视角研究政府回应性对政治参与的作用机制,拓展和增强了公共选择理论、自我决定理论的应用情境和检验效力,为促进政府有效回应、增进公民政治支持、推动政民互动等提供实证研究依据和实践方向指导。

关键词：政府回应性政治支持制度化政治参与济世兴邦政治价值观

基于知识图谱的GitHub层次化学习和检索服务

在线全文

学校读者我要写书评

暂无评论

计算机工程 2024年第5期50卷 16-25页

作者：江惠珍孙艳春黄罡北京大学计算机学院高可信软件技术教育部重点实验室北京100871 数据空间技术与系统全国重点实验室北京100091

GitHub是全球最大的在线代码托管平台,为软件开发学习者提供了丰富的学习资源,然而面对丰富而繁杂的GitHub内容,软件开发初学者在使用GitHub的搜索功能搜索所需的学习资源时,由于需求不明确或缺乏相关知识和经验,常会遇到难以构建合适... 详细信息

GitHub是全球最大的在线代码托管平台,为软件开发学习者提供了丰富的学习资源,然而面对丰富而繁杂的GitHub内容,软件开发初学者在使用GitHub的搜索功能搜索所需的学习资源时,由于需求不明确或缺乏相关知识和经验,常会遇到难以构建合适的搜索文本进行有效搜索的问题。针对该问题,利用GitHub主题潜在的层次结构,结合Wikipedia软件开发领域知识,设计GitHub软件开发领域知识图谱,在此基础上提出一种基于知识图谱的GitHub层次化学习和检索服务。通过对比实验和调查问卷的方式验证了提出的层次化学习和检索服务的可行性和有效性。

关键词： GitHub平台维基百科知识图谱层次化学习检索服务