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Effect of nucleating agents on the electrical properties of cross-linked polyethylene under tensile stress

High Voltage 2024年第2期9卷 429-439页

作者： Yunqi Xing Jiahao liu Jingang Su Junwei Zha Guochang Li Ze Guo Xiaozhen Zhao mengjia Feng State Key Laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjinChina Electric Power Research Institute of State Grid Hebei Electric Power Supply Co. Ltd.ShijiazhuangChina Beijing Advanced Innovation Center for Materials Genome Engineering School of Chemistry and Biological EngineeringUniversity of Science&Technology BeijingBeijingChina Institute of Advanced Electrical Materials Qingdao University of Science and TechnologyQingdaoChina

During the operation of high-voltage cables,external stress and residual stress can affect the aggregated structure of insulating materials and lead to significant deterioration in their electrical performance.To investigate the evolution characteristics of the electrical properties of cross-linked polyethylene(XLPE)under mechanical stress,this paper ex-plains the relationship between the aggregated structure of XLPE and its electrical properties and proposes a method for improving insulation performance under me-chanical stress.The results show that metallocene polyethylene used as a nucleating agent can promote crystallisation through heterogeneous nucleation and increase Young's modulus by non-uniform nucleation,increasing crystallinity and reducing interplanar spacing,resulting in more complete crystal forms and reduced damage to the aggregated structure during the tensile process.After nucleating agent modification,the XLPE crystallisation becomes more uniform,and interfacial adhesion forces increase.The weakened interface damage process between the amorphous and crystalline regions under tensile stress effectively inhibits the process of molecular chain polarisation turning and reduces trap density.The modified XLPE crystal structure shows a tendency towards densification and enhanced molecular chain interactions,which can reduce the damage to the aggregated structure under tensile stress,while the reduced free volume inside the material and the shortened average free path of carriers can weaken the damage of high-energy electrons to molecular chains,thereby inhibiting the process of electrical tree degradation.The results show that nucleating agents have great potential for maintaining the stable operation of XLPE cables under mechanical stress.

关键词： stress electrical damage

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Epidemiological characteristics and disease burden of infectious mononucleosis in hospitalized children in China:A nationwide retrospective study

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Virologica Sinica 2022年第5期37卷 637-645页

作者： mengjia liu Xinyu Wang Linlin Zhang Guoshuang Feng Yueping Zeng Ran Wang Zhengde Xie Beijing Key Laboratory of Pediatric Respiratory Infectious Diseases Key Laboratory of Major Diseases in ChildrenMinistry of EducationNational Clinical Research Center for Respiratory DiseasesLaboratory of Infection and VirologyBeijing Pediatric Research InstituteBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijing100045China Research Unit of Critical Infection in Children 2019RU016Chinese Academy of Medical SciencesBeijingChina Big Data Center Beijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijing100045China Medical Record Management Office Beijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijing100045China

Epstein-Barr virus(EBV)is very common,with the infection rate in adults over 90%worldwide.Infectious mononucleosis(IM)is caused by primary infection with EBV.Most IM patients are generally considered to have a favorable prognosis,but a few patients will also develop complications.Children with severe symptoms will require hospitalization.However,the disease burden of children hospitalized with IM in China has been rarely described.In this study,we included the Face sheets of discharge medical records from 27 member children's hospitals of Futang Research Center of Pediatric Development from Jan 1st,2016 to Dec 31st,2020,and medical information such as gender,age,region,time of admission,length of stay and expenditure were extracted.There were 24,120 IM cases,which accounted for 0.42%(24,120/5,693,262)of all hospitalized cases during this period.The ratio of male to female was 1.48:1.Hospitalization for IM in the 4-6 years age group was the highest among inpatients of all age groups.Case numbers increased year by year between 2016 and 2020,and the monthly hospitalization was generally high from Jul to Sep but reduced from Jan to Feb per year.Bronchitis/pneumonia and hepatic dysfunction were two common complications in hospitalized IM patients.The median length of stay was 8 days,and the median cost of hospitalization was 970.59 US dollars.This study will help understand the epidemiological characteristics and disease burden of hospitalized children with IM in China.

关键词： Epstein-Barr virus(EBV) Infectious mononucleosis(IM) Children Epidemiological characteristics Disease burden

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Synthesis and characterization of fluorescence active G_(4)-quartet and direct evaluation of self-assembly impact on emission

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Chinese Chemical Letters 2022年第9期33卷 4203-4207页

作者： Ying He mengjia liu Shun Teng Lukasz Wojtas Guangxin Gu Xiaodong Shi Department of Chemistry University of South FloridaTampaFL 33620United States Department of Materials Science Fudan UniversityShanghai 200438China

Fluorescence(FL)active 8-aryl guanosine derivatives were prepared and applied for cation mediated self-assembly to form the H-bonded G_(8)-quadruplexes.The p-cyano(p-CN)and 8-anthracene(8-An)substituted guanosines were identified to give the strongest fluorescence with the formation of G_(8)-octamers(G_(8))both in solution(NMR)and solid state(X-ray).This well-defined G_(8)-octamer system has provided the first direct evidence on the self-assembled G-quadruplex fluorescence emission with aggregation-induced emission(AIE),which could be applied as the foundation for FL molecular probe design toward G-quadruplex recognition.

关键词： Self-assembly H-bonding G_(4)-quartet Fluorescence Aggregation induced emission

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钻井液漏斗黏度和密度自动检测仪的研制与应用

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煤田地质与勘探 2024年第3期52卷 176-183页

作者：谢辉郑立群刘福林梁梦佳刘璇蔡记华杨现禹侯继武武汉誉城千里建工有限公司湖北武汉430051 中国地质大学(武汉)工程学院湖北武汉430074

近年来,国内外对钻井液性能自动检测技术的研究取得了长足进步。针对现有钻井液自动检测仪器成本高、结构复杂和工作环境受限等问题,研制了钻井液漏斗黏度和密度自动在线检测仪。使用可编程逻辑控制器、物联网模组、压力传感器、超声传... 详细信息

近年来,国内外对钻井液性能自动检测技术的研究取得了长足进步。针对现有钻井液自动检测仪器成本高、结构复杂和工作环境受限等问题,研制了钻井液漏斗黏度和密度自动在线检测仪。使用可编程逻辑控制器、物联网模组、压力传感器、超声传感器、蠕动泥浆泵、电动球阀和隔膜泵等,搭建取浆模块、检测模块、清洗模块和控制模块,实现了对钻井液漏斗黏度和密度的自动检测、移动端设备数据查看和操作等功能。采用传感器数据融合和滤波算法等方法提高仪器精度和稳定性,对不同钻井液体系性能测试验证,漏斗黏度误差控制在±1 s,密度误差控制在±0.01 g/cm^(3),且可连续地对钻井液性能进行自动测试。室内测试和现场试验结果表明,该仪器具有操作方便、测试结果准确、可重复性高、人为测量误差小和节约人工等优点,能满足实际钻井施工过程中对钻井液性能检测的要求,具有较强的普适性和广泛的应用前景。

关键词：钻井液自动检测漏斗黏度密度

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“90后”员工离职倾向影响因素研究

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长春大学学报 2024年第1期34卷 18-27页

作者：刘富成韩梦佳长春大学管理学院长春130022

在竞争激烈的商业环境中,90后员工离职成为大多数企业面临的挑战。通过问卷调查,从员工需求与激励、工作与生活平衡、工作前景与预期这3个维度运用SPSS探究90后员工离职倾向的影响因素。研究发现:本科学历的90后员工对工作的前景与预期... 详细信息

在竞争激烈的商业环境中,90后员工离职成为大多数企业面临的挑战。通过问卷调查,从员工需求与激励、工作与生活平衡、工作前景与预期这3个维度运用SPSS探究90后员工离职倾向的影响因素。研究发现:本科学历的90后员工对工作的前景与预期更高;需求与激励因素对90后员工离职倾向影响最大。因此,企业应该采取措施如建立并完善激励机制、为90后布置个性化任务和采取弹性工作制等减少员工离职现象发生。

关键词： 90后员工离职倾向影响因素

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长江口—东海内陆架悬浮重矿物组成与颗粒特征

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古地理学报 2024年第2期26卷 431-445页

作者：刘梦佳黄湘通连尔刚胡忠亚岳伟王中波杨守业同济大学海洋地质国家重点实验室上海200092 江苏师范大学地理测绘与城乡规划学院江苏徐州221116 汕头大学海洋科学研究院海洋灾害预警与防护广东省重点实验室广东汕头515000 生态环境监测与科学研究中心生态环境部太湖流域东海海域生态环境监督管理局上海200125

沉积物重矿物矿物组成和颗粒大小对揭示沉积物源和水动力分选过程具有重要指示意义。然而,受研究手段的制约,对于长江细粒沉积的重矿物组成和物源、水动力分选之间关系的探究还尚属空白。本研究利用自动定量矿物分析系统(TIMA)对长江口... 详细信息

沉积物重矿物矿物组成和颗粒大小对揭示沉积物源和水动力分选过程具有重要指示意义。然而,受研究手段的制约,对于长江细粒沉积的重矿物组成和物源、水动力分选之间关系的探究还尚属空白。本研究利用自动定量矿物分析系统(TIMA)对长江口—东海内陆架不同水层悬浮物的重矿物组成和颗粒大小进行了研究,同时,结合电子探针分析对细粒级重矿物自动识别结果进行了验证。研究表明,长江口悬浮物中特征重矿物组合为角闪石—绿帘石—铁质金属矿物,与长江下游沉积物特征重矿物组合一致。长江口悬浮物与长江下游沉积物的重矿物组成具有极好的相关性,指示其来源与长江有关。而长江口外悬浮物中赤/磁铁矿相对富集,可能是强潮作用导致的中等密度重矿物再搬运和扩散的结果。值得关注的是,在舟山群岛附近站位悬浮物样品中发现了铬铁矿的异常富集,推测与海区人类生产活动有关。长江口悬浮重矿物颗粒绝大部分为粗粉砂—极细砂,富集在悬浮物中的较粗粒级(Φ

关键词：长江口东海内陆架细粒沉积物重矿物 TIMA技术

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Molecular dynamics study on mechanical behaviors of Ti/Ni nanolaminate with a pre-existing void

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Nano Materials Science 2022年第2期4卷 113-125页

作者： mengjia Su Qiong Deng Lanting liu Lianyang Chen He He Yinggang Miao Joint International Research Laboratory of Impact Dynamics and Its Engineering Applications School of AeronauticsNorthwestern Polytechnical UniversityXi'anShaanxi 710072China

Metallic nanolaminated materials possess excellent mechanical properties due to their unique modulation structures and interfacial properties.However,how microdefects affect their mechanical properties is still uncertain.To evaluate the influences of void location(in the crystalline layer and the Ti/Ni interface),void diameter(d)and thickness of the intermediate layer(h)on overall tensile behaviors,various types of defective Ti/Ni nanolaminates with pre-existing void are established by the molecular dynamics method in this work.The results indicate that the strength and plastic deformation mechanisms are strongly dependent on those determinants.Yield stresses of Ti/Ni nanolaminates decrease distinctly with increasing void diameter,while peak stresses with a void in the crystalline layer decrease with increasing d/h.Different void locations lead eventually to disparate initial plastic deformation carriers around the void,and various evolutions in the microstructure of the defective Ti/Ni nanolaminates.The Ti/Ni interface plays a significant role in the tensile process.The semi-coherent interface impedes new grains and lattice dislocations from passing across the interface,while the incoherent interface facilitates dislocations generating and sliding along the interface,and absorbs the dislocations moving to the interface.The results also indicate that the strain rate significantly affects the evolution of the microstructure and the tensile properties of defective Ti/Ni nanolaminates.

关键词： Defective Ti/Ni nanolaminate Pre-existing void Interface Tensile behaviors Molecular dynamics

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Atomic layer deposition for quantum dots based devices

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Opto-Electronic Advances 2020年第9期3卷 1-14页

作者： Binze Zhou mengjia liu Yanwei Wen Yun Li Rong Chen State Key Laboratory of Digital Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Materials Processing and Die&Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Quantum dots(QDs)are promising candidates for the next-generation optical and electronic devices due to the outstanding photoluminance efficiency,tunable bandgap and facile solution synthesis.Nevertheless,the limited optoelectronic performance and poor lifetime of QDs devices hinder their further applications.As a gas-phase surface treatment method,atomic layer deposition(ALD)has shown the potential in QDs surface modification and device construction owing to the atomic-level control and excellent uniformity/conformality.In this perspective,the attempts to utilize ALD techniques in QDs modification to improve the photoluminance efficiency,stability,carrier mobility,as well as interfacial carrier utilization are introduced.ALD proves to be successful in the photoluminance quantum yield(PLQY)enhancement due to the elimination of QDs surface dangling bonds and defects.The QDs stability and devices lifetime are improved greatly through the introduction of ALD barrier layers.Furthermore,the carrier transport is ameliorated efficiently by infilling interstitial spaces during ALD process.Attributed to the ultra-thin and dense coating on the interface,the improvement on optoelectronic performance is achieved.Finally,the challenges of ALD applications in QDs at present and several prospects including ALD process optimization,in-situ characterization and computational simulations are proposed.

关键词： atomic layer deposition quantum dots surface passivation stability carrier transport interface engineering

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Achieving high-strain-rate and low-temperature superplasticity in an ECAP-processed Mg-Y-Er-Zn alloy via Ag addition

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Journal of Magnesium and Alloys 2023年第10期11卷 3765-3778页

作者： Haoran Wu Jinghua Jiang Zhenquan Yang mengjia Li He Huang Ningfei Ge Aibin Ma Huan liu College of Mechanicals and Materials Hohai UniversityNanjing 210000China Suqian Institute Hohai UniversitySuqian 223800China Center of Advanced Analysis and Gene Sequencing Zhengzhou UniversityZhengzhou 450003China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450003China Faculty of Georesources and Materials Engineering RWTH Aachen University52062Germany

The effect of adding a small amount of Ag on the microstructure evolution and superplastic properties of Mg-Y-Er-Zn(WEZ612) alloys was systematically studied.The basal texture of the refined WEZ612 alloy produced by equal channel angular pressing was altered to a non-basal structure upon the addition of Ag.Ag addition also refined the grain size and promoted the formation of a large number of nano-14H-long period stacking ordered phases.Using high-resolution transmission electron microscopy,many nano-precipitated phases were detected on the basal plane of the Mg-Y-Er-Zn-1Ag(WEZ612-1Ag) alloy,The nano-precipitated phases on the basal plane improved the thermal stability of the alloy,lowered the deformation activation energy(Q),and improved the stress sensitivity index(m).At 523 K with a strain rate of 10^(-2) s^(-1),the Q value of WEZ612 was higher than that of WEZ612-1Ag(299.14 and 128.5 kJ mol^(-1),respectively).In contrast,the m value of the WEZ612 alloy(0.16) was lower than that of the WEZ612-1Ag alloy(0.46).At 623 K with a tensile rate of 10^(-2) s^(-1),the WEZ612 and WEZ612-1Ag alloys were elongated by 182% and 495%,respectively,with the latter exhibiting high-strain-rate and low-temperature superplasticity.The improved superplasticity of the WEZ612-1Ag alloy is attributed to the nano-precipitated phases,which effectively limit the cavity extension during superplastic deformation.

关键词： Magnesium alloys Long period stacking ordered(LPSO) Ag addition Nano-precipitates Superplastic behavior

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混合磨玻璃结节实性成分的CT定量参数对肺腺癌组织分化的预测价值

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影像科学与光化学 2024年第2期42卷 128-133页

作者：张利霞刘海霞王梦家常利明河北省唐山市工人医院CT室河北唐山063000

探讨肺部混合磨玻璃结节(mGGN)实性成分的三维CT定量参数预测浸润性非黏液腺癌(IAC)组织分化程度的价值。回顾性分析99例术后病理证实为IAC患者的临床及影像资料。依据国际肺癌研究学会病理新分级系统分为:高分化IAC(53例)、中分化IAC(3... 详细信息

探讨肺部混合磨玻璃结节(mGGN)实性成分的三维CT定量参数预测浸润性非黏液腺癌(IAC)组织分化程度的价值。回顾性分析99例术后病理证实为IAC患者的临床及影像资料。依据国际肺癌研究学会病理新分级系统分为:高分化IAC(53例)、中分化IAC(31例)、低分化IAC(15例)。观察实性成分的三维CT定量参数与IAC组织分化程度之间的相关性。结果显示:实性成分体积、体积占比、平均CT值、平均直径在不同组织分化程度之间的差异均具有统计学意义(P<0.001)。多重比较结果显示,低分化IAC的实性成分体积、体积占比、平均CT值、平均直径均大于中高分化IAC;而中分化与高分化IAC之间仅体积占比有统计学意义。将高分化IAC与中分化IAC合并纳入A组,低分化IAC纳入B组,预测低分化IAC的ROC曲线结果显示实性成分体积、体积占比、平均CT值、平均直径的cut-off值分别为341.5 mm~3、52.9%、-116.5 HU、9.65 mm。总之,mGGN实性成分的三维CT定量参数对IAC的组织分化程度有较高的预测价值,对选择诊治方案和判断患者预后有较大的指导意义。

关键词：混合磨玻璃结节浸润性肺腺癌实性成分组织分化定量参数

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