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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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Starting materials, processes and characteristics of bio-based foams: A review

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Journal of Bioresources and Bioproducts 2024年第2期9卷 160-173页

作者： Xiaohan Wang Jinwon Jang Yanqun su jingang Liu Hongjie Zhang Zhibin He Yonghao Ni National Engineering Laboratory for Pulp and Paper China National Pulp and Paper Research Institute Co.Ltd.Beijing 100102China Limerick Pulp and Paper Centre and Department of Chemical Engineering University of New BrunswickNew Brunswick E3B 5A3Canada

Biofoam products have attracted considerable attention lately because there is a growing demand for green/sustainable products.To this end,various biobased foams have either been developed or are currently in development,e.g.,bio-based polyurethanes(PUs),polylactic acid(PLA),starch,and polyhydroxyalkanotates(PHAs).Indeed,significant progress has been made;however,chal-lenges still persist,for example,biobased foam products have poor processability,inferior com-patibility,thermal and strength properties.In this review,we focus on five biofoam products:namely bio-based PUs,PLA,starch,PHAs,and cellulose biofoam products,along with their prop-erties and performance,as well as their manufacturing processes.Further efforts are still needed to unlock the full potential of these bio-based products and meet the goal of complementing and gradually replacing some of their fossil-based counterparts.Finally,the challenges,as well as arising opportunities of future research directions are discussed.

关键词： Biofoam Bio-based polyurethanes Polylactic acid Polyhydroxyalkanotate Starch Cellulose Manufacturing process

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Multi‐type defect detection and location based on non‐destructive impedance spectrum measurement for underground power cables

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High Voltage 2023年第5期8卷 977-985页

作者： jingang su Liqiang Wei Peng Zhang Yan Li Yunpeng Liu Electric Power Research Institute of State Grid Hebei Electric Power supply Co.Ltd. ShijiazhuangChina School of Electrical and Electronic Engineering North China Electric Power UniversityBaodingChina

Power cable defect detection and location is a crucial aspect in power asset maintenance.Impedance spectrum measurement can be used as a non‐destructive tool for cable monitoring.Defects from overheating and moisture ingress are investigated by the authors,and it is shown that multi‐type cable defects can be detected and located by this methodology.With both electromagnetic analysis and experimental investigation,the relation between impedance variation and the dielectric permittivity is studied to reveal the method's mechanism.An approach to implement such impedance measurement online is proposed and its perspectives in terms of sensitivity is investigated by field scale tests.It is shown that 2%impedance variation due to defect should be detectable.Field scale tests show perspectives for online application with signal coupling through a highfrequency current transformer with focus on the differences in waveforms obtained from the impedance measurements.

关键词： power impedance defect

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Electrical tree degradation in high-voltage cable insulation:progress and challenges

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High Voltage 2020年第4期5卷 353-364页

作者： jingang su Boxue Du Jin Li Zhonglei Li Electric Power Research Institute of State Grid Hebei Electric Power supply Co.Ltd. Shijiazhuang 050021People's Republic of China School of Electrical and Information Engineering Tianjin UniversityWeijin Road 92Tianjin 300072People's Republic of China

High-voltage direct current(HVDC)and high-voltage alternating current(HVAC)cables are the most important equipment for high-voltage,large-capacity and long-distance power transmission.Electrical tree is a pre-breakdown phenomenon leading to failure of insulation materials,and it is the major issue that threatens the safe and stable operation of HVDC and HVAC cable systems.This study summarises and analyses the achievements in the research of electrical tree for HVDC and HVAC cables.The initiation mechanisms of the electrical tree,including Maxwell electro-mechanical stress,charge injection-extraction,charge trapping and electroluminescence theories,are elaborated for fully understanding the electrical degradation process in insulation materials.Then,the influences of the high electric field,high temperature and mechanical stress on electrical tree behaviours are discussed,and the relationship between charge transport and the electrical tree is analysed and illustrated.The suppression methods of the electrical tree are put forward by introducing inorganic and organic additives into insulation materials,and the suppression mechanisms are presented from the viewpoints of the structure-property and microscale-macroscale relationships.Recently,the electrical tree research studies are focused on the high-precision of initiation models,high-dependence of multi-physical fields and high-efficiency of suppression methods.The achievements provide theoretical support for improving the electrical performance of insulation materials,while it is a practical problem to explore their application feasibility in HVDC and HVAC cable.

关键词： insulation Electrical tree

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税收服务高水平对外开放的路径选择

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国际税收 2024年第6期 39-46页

作者：张国梁杨素孙金刚代志新国家税务总局税务干部学院中国人民大学财政金融学院国家税务总局广州市税务局

作为国家宏观调控的重要工具,税收在服务推进高水平对外开放进程中扮演着重要角色,能够在统筹国内国际两个市场两种资源、增强国际经济合作与竞争新优势方面发挥关键作用。本文基于税收服务高水平对外开放的内在逻辑,分析既往的成功实... 详细信息

作为国家宏观调控的重要工具,税收在服务推进高水平对外开放进程中扮演着重要角色,能够在统筹国内国际两个市场两种资源、增强国际经济合作与竞争新优势方面发挥关键作用。本文基于税收服务高水平对外开放的内在逻辑,分析既往的成功实践和当前面临的现实挑战,从继续完善现行税制体系、探索开放型税收制度创新、积极谋求国际税收合作、深度融入国际税收治理等四个方面,提出税收服务高水平对外开放的政策建议。

关键词：税收高水平对外开放国际税收合作国国际税收治理

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Research Status and Prospects of Bio-based Materials for Grease Barrier Coatings on Paper Food Packaging

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Paper And Biomaterials 2023年第4期8卷 44-54页

作者： Qi Chen Ruijuan Zhang Yanqun su Tao Zhao Qi Du jingang Liu Patent Office China National Intellectual Property AdministrationBeijing100088China China National Pulp and Paper Research Institute Co. Ltd.Beijing100102China Sinolight Specialty Fiber Products Co. Ltd.LangfangHebei Province065008China

Increased environmental and health concerns over the use of plastic packaging or fluorine-containing coatings,in combination with increased market demand for products with a longer shelf life,make bio-based materials one of the most important research candidates for alternative paper packaging materials for oil resistance.These bio-based materials have excellent oxygen and oil barriers,which are critical for food packaging.Moreover,they are biodegradable,naturally renewable,and safe.In this artical,two main groups of bio-based oil repellents for paper food packaging,including polysaccharide-based biopolymers and protein-based biopolymers,are enumerated,and the advantages and weaknesses of bio-based oil repellents are discussed,and effective solutions are proposed.Finally,research status and prospects on the development of bio-based oil-resistant coatings for the food packaging industry are presented.

关键词： bio-based materials grease barrier properties paper food packaging

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Degradable Foam Tray Based on High-concentration Dispersed Cellulose Fibers Obtained by a Hot-press Baking Process

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Paper And Biomaterials 2023年第4期8卷 20-26页

作者： Ruijuan Zhang Yanqun su Tao Zhao jingang Liu Hongjie Zhang Leilei Hou Xianling Fu Qi Chen China National Pulp and Paper Research Institute Co. Ltd.Beijing100102China National Engineering Lab for Pulp and Paper Beijing100102China Sinolight Specialty Fiber Products Co. Ltd.LangfangHebei Province065008China China National Intellectual Property Administration Beijing100088China

Degradable industrial packaging foam trays made from cellulose fibers were fabricated using a hot-press baking process.Bleached softwood pulp fibers with a concentration of 30%were dispersed at a high speed under the action of a dispersant.The effects of the dispersant dosage of the fibers on the porosity,foam density,and static compression characteristics were discussed.Furthermore,the effects of the reinforcing adhesive including polyvinyl alcohol(PVA),and cassava starch on the physical and mechanical properties of the foam trays were studied,as well as the relationship between these properties and the microstructure of the foam trays.The dispersant enhanced the rheological and blistering properties of the fiber dispersion.As the dispersant dosage increased from 2%to 4%,the foam density gradually increased and the compressive strain performance and residual compressive strain of the foam trays decreased.Under the condition of constant dosage of dispersant,increasing the fiber proportion from 67%to 77%improved the porosity and foam density and slightly reduced the static compression performance.In additioton,the static compression resistance of the foamed materials was improved by increasing the PVA dosage since PVA was beneficial for improving the strength of the foam trays.

关键词： degradable foam cellulose fiber dispersion cassava starch polyvinyl alcohol

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Different Kinds of Microfibrillated Cellulose as Coating Layers Providing Fiber-based Barrier Properties

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Paper And Biomaterials 2021年第1期6卷 33-40页

作者： Ruijuan Zhang Yanqun su jingang Liu China National Pulp and Paper Research Institute Co. Ltd.Beijing100102China National Engineering Lab for Pulp and Paper Beijing100102China

In this study,we investigated the barrier properties of different kinds of microfibrillated cellulose(MFC)coating layers.The air,oxygen,and water vapor permeability,as well as the water contact angles(WCA),were measured to quantify the barrier efficacy of the applied coatings.The WCA data showed that the surfaces of MFC-coated cardboards are more hydrophilic than those of uncoated cardboards.However,different MFC coatings realize different oxygen transmission rates(OTRs)and water vapor transmission rates(WVTRs).The MFC coating derived from bleached bamboo pulp subjected to carboxyethylation pretreatment(MFCCBP)gave the best oxygen and water vapor barrier performances.The OTR of the virgin cardboard(>16500 cm^(3)/(m^(2)·24 h))decreased to 4638 cm^(3)/(m^(2)·24 h)after coating with the MFCCBP.The WVTR similarly decreased from 1016.7 g/(m^(2)·24 h)to 603.2 g/(m^(2)·24 h).

关键词： microfibrillated cellulose coating performance surface properties barrier properties

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Overexpression of Sirt6 ameliorates sleep deprivation induced-cognitive impairment by modulating glutamatergic neuron function

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Neural Regeneration Research 2023年第11期18卷 2449-2458页

作者： Jinpiao Zhu Chang Chen Zhen Li Xiaodong Liu jingang He Ziyue Zhao Mengying He Binbin Nie Zili Liu Yingying Chen Kuanpin su Xiang Li Juxiang Chen Hongbing Xiang Fuqiang Xu Kangguang Lin Zongze Zhang Jie Wang Department of Anesthesiology Brain Research CenterDepartment of NeurosurgeryZhongnan HospitalWuhan UniversityWuhanHubei ProvinceChina Department of Anesthesiology and Pain Medicine Tongji Hospital of Tongji Medical CollegeHuazhong University of Science and TechnologyWuhanHubei ProvinceChina Department of Anesthesia and Intensive Care Peter Hung Pain Research InstituteThe Chinese University of Hong KongHong Kong Special Administration RegionChina Key Laboratory of Magnetic Resonance in Biological Systems State Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsNational Center for Magnetic Resonance in WuhanWuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of Sciences-Wuhan National Laboratory for OptoelectronicsWuhanHubei ProvinceChina Key Laboratory of Nuclear Radiation and Nuclear Energy Technology Institute of High Energy PhysicsChinese Academy of SciencesBeijingChina The Brain Cognition and Brain Disease Institute(BCBDI) NMPA Key Laboratory for Research and Evaluation of Viral Vector Technology in Cell and Gene Therapy Medicinal ProductsShenzhen Key Laboratory of Viral Vectors for BiomedicineShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research InstitutionsShenzhenGuangdong ProvinceChina Mind-Body Interface Research Center(MBI-Lab) China Medical University HospitalTaichungTaiwanChina An-Nan Hospital China Medical UniversityTainanTaiwanChina Department of Neurosurgery Changhai HospitalNaval Medical UniversityShanghaiChina Department of Affective Disorders The Affiliated Brain Hospital of Guangzhou Medical UniversityGuangzhouGuangdong ProvinceChina Institute of Neuroscience and Brain Diseases Xiangyang Central HospitalAffiliated Hospital of Hubei University of Arts and ScienceXiangyangHubei ProvinceChina University of Chinese Academy of Sciences BeijingChina

Sleep benefits the restoration of energy metabolism and thereby suppo rts neuronal plasticity and cognitive behaviors.Sirt6 is a NAD+-dependent protein deacetylase that has been recognized as an essential regulator of energy metabolism because it modulates various transcriptional regulators and metabolic enzymes.The aim of this study was to investigate the influence of Sirt6 on cerebral function after chronic sleep deprivation(CSD).We assigned C57BL/6J mice to control or two CSD groups and subjected them to AAV2/9-CMV-EGFP or AAV2/9-CMV-Sirt6-EGFP infection in the prelimbic cortex(PrL).We then assessed cerebral functional connectivity(FC) using resting-state functional MRI,neuron/astrocyte metabolism using a metabolic kinetics analysis;dendritic spine densities using sparse-labeling;and miniature excitato ry postsynaptic currents(mEPSCs) and action potential(AP) firing rates using whole-cell patchclamp recordings.In addition,we evaluated cognition via a comprehensive set of behavioral tests.Compared with controls,Sirt6 was significantly decreased(Psular cortex,and cerebellum.Sirt6 ove rexpression reve rsed CSD-induced cognitive impairment and reduced FC.Our analysis of metabolic kinetics using [1-13C] glucose and [2-13C] acetate showed that CSD reduced neuronal Glu4and GABA2synthesis,which could be fully restored via forced Sirt6 expression.Furthermore,Sirt6 ove rexpression reversed CSD-induced decreases in AP firing rates as well as the frequency and amplitude of mEPSCs in PrL pyramidal neurons.These data indicate that Sirt6 can improve cognitive impairment after CSD by regulating the PrL-associated FC network,neuronal glucose metabolism,and glutamatergic neurotransmission.Thus,Sirt6 activation may have potential as a novel strategy for treating sleep disorder-related diseases.

关键词： chronic sleep deprivation cognitive impairment functional connectivity glutamatergic neurons metabolic kinetics neuronal-astrocytic glucose metabolism prelimbic cortex REM sleep Sirt6 synaptic function

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Applications of nanogenerators for biomedical engineering and healthcare systems

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InfoMat 2022年第2期4卷 53-109页

作者： Wanli Wang Jinbo Pang Jie su Fujiang Li Qiang Li Xiaoxiong Wang jingang Wang Bergoi Ibarlucea Xiaoyan Liu Yufen Li Weijia Zhou Kai Wang Qingfang Han Lei Liu Ruohan Zang Mark HRümmeli Yang Li Hong Liu Han Hu Gianaurelio Cuniberti College of Electrical Engineering Qingdao UniversityQingdaoChina Collaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of Shandong Institute for Advanced Interdisciplinary Research(iAIR)University of JinanJinanChina College of Electronic Information Qingdao UniversityQingdaoChina Department of Pediatric surgery The Affiliated Hospital of Qingdao UniversityQingdaoChina College of Physics Qingdao UniversityQingdaoChina Institute for Materials Science and Max Bergmann Center of Biomaterials Technische Universität DresdenDresdenGermany Center for Advancing Electronics Dresden Technische Universität DresdenDresdenGermany College of Biological Science and Technology University of JinanJinanChina School of Chemistry and Chemical Engineering University of JinanShandongJinanChina College of Energy Soochow Institute for Energy and Materials InnovationsSoochow UniversitySuzhouChina Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province Soochow UniversitySuzhouChina Centre of Polymer and Carbon Materials Polish Academy of SciencesZabrzePoland Institute for Complex Materials IFW DresdenDresdenGermany Institute of Environmental Technology VŠB-Technical University of OstravaOstravaCzech Republic School of Information Science and Engineering University of JinanJinanChina Shandong Provincial Key Laboratory of Network Based Intelligent Computing University of JinanJinanChina State Key Laboratory of Crystal Materials Center of Bio&Micro/Nano Functional MaterialsShandong UniversityJinanChina College of Chemical Engineering China University of Petroleum(East China)QingdaoChina Dresden Center for Computational Materials Science Technische Universität DresdenDresdenGermany The Dresden Center for Intelligent Materials(DCIM) Technische Universität DresdenDresdenGermany

The dream of human beings for long living has stimulated the rapid development of biomedical and healthcare equipment.However,conventional biomedical and healthcare devices have shortcomings such as short service life,large equipment size,and high potential safety hazards.Indeed,the power supply for conventional implantable device remains predominantly batteries.The emerging nanogenerators,which harvest micro/nanomechanical energy and thermal energy from human beings and convert into electrical energy,provide an ideal solution for self-powering of biomedical devices.The combination of nanogenerators and biomedicine has been accelerating the development of self-powered biomedical equipment.This article first introduces the operating principle of nanogenerators and then reviews the progress of nanogenerators in biomedical applications,including power supply,smart sensing,and effective treatment.Besides,the microbial disinfection and biodegradation performances of nanogenerators have been updated.Next,the protection devices have been discussed such as face mask with air filtering function together with real-time monitoring of human health from the respiration and heat emission.Besides,the nanogenerator devices have been categorized by the types of mechanical energy from human beings,such as the body movement,tissue and organ activities,energy from chemical reactions,and gravitational potential energy.Eventually,the challenges and future opportunities in the applications of nanogenerators are delivered in the conclusive remarks.

关键词： biomedical engineering healthcare implantable devices nanogenerators self-powered devices sensors

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