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Experimental and molecular level analysis of natural ester delaying degradation of cellulose insulation polymer

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High Voltage 2022年第5期7卷 1001-1015页

作者： Jian Hao Wenyu Ye Chenyu Gao mengzhao zhu Lijun Yang Ruijin Liao State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqingChina State Grid Shandong Electric Power Co. Shandong Electric Power Research InstituteJinanChina

Developing green insulation materials has become an important direction for future *** a new environmental insulation liquid,natural ester can effectively delay cellulose insulation polymer *** the mechanism of natural ester delaying the cellulose ageing could promote its application in power *** this study,based on the accelerated thermal ageing of pressboard immersed in natural ester and 25#mineral oil at 120°C for 221 days,the thermal ageing rate and the levelling off degree of polymerisation(LODP)for two kinds of oil-impregnated pressboards were *** molecular level mechanism of natural ester delaying cellulose degradation and keeping higher LODP value was proposed using molecular dynamics *** the early stage of thermal ageing,cellulose with a higher degree of polymerisation(DP)can form many hydrogen bonds with hydronium ions,and their binding energy is stronger,which can accelerate the acid hydrolysis of cellulose,causing the DP of pressboard immersed in natural ester and mineral oil to decrease *** the breaking of the cellulose molecular chain,the number of hydrogen bonds and binding energy between cellulose and hydronium ions becomes smaller and the thermal ageing rate decreases *** the end stage of ageing,it is difficult for the hydronium ions to enter the crystalline cellulose,acid hydrolysis of crystalline cellulose is hard to conduct,leading to the occurrence of the LODP *** degradation rate of cellulose in natural ester is only 50%of that in mineral *** cellulose LODP value in natural ester is over 200 larger than that in mineral *** with the mineral oil-cellulose system,natural ester can form hydrogen bonds with hydronium ions and lead to fewer hydronium ions in cellulose,fewer hydrogen bonds and smaller binding energy between cellulose and hydronium ions,which can reduce the acid hydrolysis reaction of *** study provides a theoretical explanation for

关键词： insulation delay cellulose

Structural revolution of atomically dispersed Mn sites dictates oxygen reduction performance

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Nano Research 2021年第12期14卷 4512-4519页

作者： Zhengkun Yang Xiaolin Wang mengzhao zhu Xinyan Leng Wenxing Chen Wenyu Wang Qian Xu Li-Ming Yang Yuen Wu School of Chemistry and Materials Science iChEMHefei National Laboratory for Physical Sciences at the MicroscaleUniversity of Science and Technology of ChinaHefei230026China Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica Key Laboratory of Material Chemistry for Energy Conversion and StorageMinistry of EducationHubei Key Laboratory of Materials Chemistry and Service FailureHubei Engineering Research Center for Biomaterials and Medical Protective MaterialsSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan430074China Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials(Anhui University)Ministry of EducationAnhui Graphene Engineering LaboratoryAnhui UniversityHefei230601China Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications School of Materials Science and EngineeringBeijing Institute of TechnologyBeijing100081China National Synchrotron Radiation Laboratory(NSRL) Hefei230026China

An efficient preparation and local coordination environment regulation of isolated single-atom sites catalysts(ISASC)for improved activity is still ***,we develop a solid phase thermal diffusion strategy to synthesize Mn ISASC on highly uniform nitrogen-doped carbon nanotubes by employing MnO_(2) nanowires@ZIF-8 core-shell *** high-temperature,the Mn species break free from core-MnO_(2) lattice,which will be trapped by carbon defects derived from shell-ZIF-8 carbonization,and immobilized within carbon ***,the poly-dispersed Mn sites with two nitrogen-coordinated centers can be controllably renovated into four-nitrogen-coordinated Mn sites using NH3 treatment *** experimental and computational investigations indicate that the symmetric coordinated Mn sites manifest outstanding oxygen reduction activity and superior stability in alkaline and acidic *** work not only provides efficient way to regulate the coordination structure of ISASC to improve catalytic performance but also paves the way to reveal its significant promise for commercial application.

关键词： thermal diffusion coordination repairing single-atom manganese oxygen reduction catalysis fuel cells

The promoting effect of interstitial hydrogen on the oxygen reduction performance of PtPd alloy nanotubes for fuel cells

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Nano Research 2023年第2期16卷 2366-2372页

作者： Tingting Chao Xuan Luo mengzhao zhu Yanmin Hu Yida Zhang Yunteng Qu Hantao Peng Xiaoshuang Shen Xusheng Zheng Liang Zhang Xun Hong Center of Advanced Nanocatalysis(CAN) Department of Applied ChemistryUniversity of Science and Technology of ChinaHefei 230026China Country Center for Combustion Energy and School of Vehicle and Mobility Tsinghua UniversityBeijing 100084China National Synchrotron Radiation Laboratory(NSRL) University of Science and Technology of ChinaHefei 230029China Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China School of Physical Science and Technology Yangzhou UniversityYangzhou 225002China

Highly efficient and stable oxygen reduction reaction(ORR)electrocatalysts are remarkably important but challenging for advancing the large-scale commercialization of practical proton exchange membrane fuel cells(PEMFCs).In this work,we report that the introduction of interstitial hydrogen atoms into PtPd nanotubes can significantly promote ORR performance without scarifying the *** enhanced mass activity was 8.8 times higher than that of commercial Pt/*** accelerated durability test showed negligible activity attenuation after 30,000 ***,H2/O2 fuel cell tests further verified the excellent activity of PtPd-H nanotubes with a maximum power density of 1.32 W·cm^(−2),superior to that of commercial Pt/C(1.16 W·cm^(−2)).Density functional theory calculations demonstrated the incorporation of hydrogen atoms gives rise to the broadening of Pt d-band and the downshift of d-band center,which consequently leads to the weaker intermediates binding and enhanced ORR activity.

关键词： hydrogen atoms incorporation alloy d-band structure regulation oxygen reduction reaction fuel cell

Influence of Vegetable Oil on the Thermal Aging Rate of Kraft Paper and its Mechanism

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高电压技术 2012年第8期38卷 2059-2067页

作者： YANG Lijun DENG Bangfei LIAO Ruijin SUN Caixin zhu mengzhao the State Key Laboratory of Transmission&Distribution Equipments and Power System Safety and New Technology Chongqing University Chongqing 400030 China~ Chongqing Electric Power Test&Research Chongqing 400015 China

With the development of new insulation materials,vegetable oil-the best substitute for mineral oil-has gradually been widely used in the liquid insulation of *** investigate the influence of vegetable oil on the thermal aging rate of oil paper,Kraft paper impregnated with mineral oil and vegetable oil have been underwent thermally accelerated aging at three different *** degree of polymerization(DP) of Kraft paper was measured to indicate the aging degree of insulation *** aging rate of Kraft paper in mineral oil and vegetable oil was compared quantitatively,and results showed that vegetable oil retarded paper’s degradation rate and extended its useful *** reasons contributing to such phenomena were analyzed using X-ray Photoelectron Spectroscopy(XPS) and molecular simulation *** paper in vegetable oil had larger activation *** to the larger interaction force between water and natural ester molecules,water molecules were easily bonded with natural ester,weakening the hydrolysis process of *** was chemically modified by natural ester during the thermal aging process,and the reactive-OH(hydroxyl) groups on the cellulose became esterified with fatty acid *** molecules were firmly bounded to the ester groups on glucose produced by *** long-chain fatty acid esterified to cellulose was parallel with cellulose chains and acted as a "water barrier" to further weaken the hydrolysis process.

关键词：局部放电射频信号放电量高电压技术

Integrating single Ni site and PtNi alloy on two-dimensional porous carbon nanosheet for efficient catalysis in fuel cell

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Nano Research 2024年第8期17卷 6916-6921页

作者： Fangyao Zhou Yaner Ruan Feng Li Lin Tian mengzhao zhu Wenan Tie Xiaoyan Tian Bo Wang Peigen Liu Jie Xu Xiaoping Gao Peng Li Huang Zhou Yuen Wu Key Laboratory of Precision and Intelligent Chemistry University of Science and Technology of ChinaHefei 230026China Shanxi Yanchang Petroleum(Group)Co.Ltd. Xian 710065China College of Chemistry and Materials Engineering Wenzhou UniversityWenzhou 325035China

The performance of catalyst depends on the intrinsic activity of active sites and the structural characteristics of the ***,we simultaneously integrate single nickel(Ni)sites and platinum-nickel(PtNi)alloy nanoparticles(NPs)on a two-dimensional(2D)porous carbon nanosheet,demonstrating remarkable catalytic performance in the oxygen reduction reaction(ORR).The single Ni sites can activate the oxygen molecules into key oxygen-containing intermediate that is further efficiently transferred to the adjacent PtNi alloy NPs and rapidly reduced to H_(2)O,which establishes a relay catalysis between active *** porous structure on the carbon nanosheet support promotes the transfer of active intermediates between these active sites,which assists the relay catalysis by improving mass ***,the obtained catalyst demonstrates a half-wave potential of up to 0.942 V,a high mass activity of 0.54 A·mgPt^(−1),and negligible decay of activity after 30,000 cycles,which are all superior to the commercial Pt/C catalysts with comparable loading of *** theoretical calculation results reveal that the obtained catalyst with defect structure of carbon support presents enhanced relay catalytic effect of PtNi alloy NPs and single Ni sites,ultimately realizing improved catalytic *** work provides valuable inspiration for developing low platinum loading catalyst,integrating single atoms and alloy with outstanding performance in fuel cell.

关键词： two-dimensional porous carbon nanosheet Pt-based alloy single atom catalysts relay effect proton-exchange membrane fuel cells

Exogenous melatonin enhances heat stress tolerance in sweetpotato by modulating antioxidant defense system,osmotic homeostasis and stomatal traits

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Horticultural Plant Journal 2025年第1期11卷 431-445页

作者： Sunjeet Kumar Rui Yu Yang Liu Yi Liu Mohammad Nauman Khan Yonghua Liu mengzhao Wang Guopeng zhu School of Breeding and Multiplication(Sanya Institute of Breeding and Multiplication) Hainan UniversitySanyaHainan 572025China Key Laboratory for Quality Regulation of Tropical Horticultural Crops of Hainan Province Hainan UniversityHaikouHainan 570228China

Heat stress hinders the growth and productivity of sweetpotato plants,predominantly through oxidative damage to cellular ***,the development of efficient approaches for mitigating heat-related impairments is essential for the long-term production of *** has been recognised for its capacity to assist plants in dealing with abiotic stress *** research aimed to investigate how different doses of exogenous melatonin influence heat damage in sweetpotato *** stress drastically affected shoot and root fresh weight by 31.8 and 44.5%,*** reduction resulted in oxidative stress characterised by increased formation of hydrogen peroxide(H_(2)O_(2))by 804.4%,superoxide ion(O_(2)^(·-))by 211.5%and malondialdehyde(MDA)by 234.2%.Heat stress also reduced chlorophyll concentration,photosystemⅡefficiency(F_v/F_m)by 15.3%and gaseous ***,pre-treatment with 100μmol L^(-1)melatonin increased growth and reduced oxidative damage to sweetpotato plants under heat *** particular,melatonin decreased H_(2)O_(2),O_(2)^(·-)and MDA by 64.8%,42.7%and 38.2%,*** also mitigated the decline in chlorophyll levels and improved stomatal traits,gaseous exchange and F_(v)/F_(m)(13%).Results suggested that the favorable outcomes of melatonin treatment can be associated with elevated antioxidant enzyme activity and an increase in non-enzymatic antioxidants and ***,these findings indicate that exogenous melatonin can improve heat stress tolerance in *** stu dy will assist re searchers in further investigating how melatonin makes sweetpotatoes more resistant to heat stress.

关键词： Sweetpotato Heat stress Melatonin Oxidative damage Antioxidant defense system Stomatal traits

Profile of Dr. Jiaojun zhu

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Science China(Life Sciences) 2025年第2期68卷 311-313页

作者： zhu, Jiaojun

Dr. Jiaojun zhu is the director general of Institute of Applied Ecology(IAE), Chinese Academy of Sciences(CAS)(2018 to present). He received his B.S. degree in Forest Science from Shenyang Agricultural University, China in July 1987, and subsequently joined Institute of Forestry and Soil, CAS(now known as the IAECAS) to pursue his M.S. degree in *** graduation, he served as a research assistant and an associate research fellow in the IAE-CAS from 1990 to 1996.

关键词： Forest pursue assistant

基于油中溶解气监测的变压器在线半监督故障诊断方法研究

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电网技术 2023年第3期47卷 1031-1037页

作者：朱庆东朱文兵王浩哲顾朝亮徐冉朱孟兆国网山东省电力公司电力科学研究院山东省济南市市250002

变压器是电力系统中的核心设备,其运行的可靠性直接影响着整个电力系统的稳定与安全,因此对变压器运行状态进行实时分析并进行准确的故障诊断非常重要。针对变压器运行状态数据难以收集、故障数据缺乏而导致故障分析模型泛化能力差的问... 详细信息

变压器是电力系统中的核心设备,其运行的可靠性直接影响着整个电力系统的稳定与安全,因此对变压器运行状态进行实时分析并进行准确的故障诊断非常重要。针对变压器运行状态数据难以收集、故障数据缺乏而导致故障分析模型泛化能力差的问题,该文提出了一种半监督流形嵌入(semi-supervised manifold embedding,SSME)学习的变压器在线故障诊断方法。该方法使用变压器油中H2、CH4、C2H6、C2H4和C2H25种不同气体的浓度特征和运行状态类别的有限样本,联合大量在线监测获得的气体浓度样本数据,建立一种在线的半监督故障诊断模型来分析变压器的运行状态,该模型能在0.1s内完成700条在线监测数据的状态检测,其性能可以达到在线诊断的要求。结合实例,对所设计的变压器故障诊断模型的准确性和诊断效率进行了对比分析实验。实验结果表明,该文提出的方法的故障诊断准确率高于经典的深度置信网络(deep belief network,DBN)、k-近邻(k-nearby network,KNN)和随机森林(random forest,RF)分类算法。该方法能为电力变压器的稳定运行提供了有效参考依据。

关键词：在线监测变压器故障诊断半监督学习

绝缘纸中水分扩散及其对绝缘纸机械性能影响的仿真研究

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电工技术学报 2015年第10期30卷 338-345页

作者：朱孟兆廖瑞金杜修明周加斌朱文兵国网山东省电力公司电力科学研究院济南250002 重庆大学电气工程学院重庆400030

利用分子动力学方法绝缘纸中水分的扩散其及影响因素和水分对绝缘纸的机械性能时行了研究。模拟结果表明,不同水分含量的扩散系数受水分与纤维素的相互作用、相对自由体积共同影响。水分的扩散系数与水分和纤维素的相互作用及每个水分... 详细信息

利用分子动力学方法绝缘纸中水分的扩散其及影响因素和水分对绝缘纸的机械性能时行了研究。模拟结果表明,不同水分含量的扩散系数受水分与纤维素的相互作用、相对自由体积共同影响。水分的扩散系数与水分和纤维素的相互作用及每个水分子与纤维素形成的氢键数表现出了极强的相关性,而与相对自由体积的相关性并不强。水分的加入使纤维素材料的机械性能在逐步的下降,而塑性增加。随着水分含量的增加,纤维素内聚能密度和溶解度参数均在减小,与纤维素的力学参数的变化规律相似。通过对链间距的分析发现,随着水分的增加,链间距在增大,表明水分弱化了纤维素分子间作用,从而导致了纤维素材料整体的机械性能的下降。

关键词：扩散相互作用机械性能链间距