检索结果-南通市图书馆

Ligand-Controlled Palladium-Catalyzed Regiodivergent Defluorinative Allylation of gem-Difluorocyclopropanes viaσ-Bond Activation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2022年第19期40卷 2345-2355页

作者： Lei Wu Minyan wang Yong liang Zhuangzhi shi State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringNanjing UniversityNanjingJiangsu210093 China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiangHenan453007 China

Monofluoroalkenes are important and versatile privileged components in pharmacologically relevant molecules.Here,we report a method for the selective construction of these compounds in a diversity-oriented fashion through regiodivergent cross-coupling of gem-difluorocyclopropanes with allylboronates by employing a palladium catalyst with two different ligands,in which gem-difluorocyclopropanes were used as allyl electrophiles by C—C and C—F bond activation.In the presence of 2-biphenylyl(diphenyl)phosphine as ligand,the linear-selective allyl–allyl bond formation is highly obtained,while utilizing the sterically hindered BrettPhos(dicyclohexyl[3,6-dimethoxy-2',4',6'-tris(1-methylethyl)[1,1'-biphenyl]-2-yl]phosphine)as the ligand favors the generation of the branched-selective product.Experimental and computational studies investigated the key steps of the cross-coupling reactions,revealing the origin of the ligand-controlled regiodivergence.

关键词： Allylation C-C activation Cross-coupling gem-Difluorocyclopropanes Defluorination

Three-dimensional composite Li metal anode by simple mechanical modification for high-energy batteries

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers in Energy 2023年第5期17卷 569-584页

作者： Min HONG Zhiyong wang Zhangqin shi Zheng liang Frontiers Science Center for Transformative Molecules School of Chemistry and Chemical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Lithium(Li)metal is believed to be the“Holy Grail”among all anode materials for next-generation Li-based batteries due to its high theoretical specific capacity(3860 mAh/g)and lowest redox potential(−3.04 V).Disappointingly,uncontrolled dendrite formation and“hostless”deposition impede its further development.It is well accepted that the construction of three-dimensional(3D)composite Li metal anode could tackle the above problems to some extent by reducing local current density and maintaining electrode volume during cycling.However,most strategies to build 3D composite Li metal anode require either electrodeposition or melt-infusion process.In spite of their effectiveness,these procedures bring multiple complex processing steps,high temperature,and harsh experimental conditions which cannot meet the actual production demand in consideration of cost and safety.Under this condition,a novel method to construct 3D composite anode via simple mechanical modification has been recently proposed which does not involve harsh conditions,fussy procedures,or fancy equipment.In this mini review,a systematic and in-depth investigation of this mechanical deformation technique to build 3D composite Li metal anode is provided.First,by summarizing a number of recent studies,different mechanical modification approaches are classified clearly according to their specific procedures.Then,the effect of each individual mechanical modification approach and its working mechanisms is reviewed.Afterwards,the merits and limits of different approaches are compared.Finally,a general summary and perspective on construction strategies for next-generation 3D composite Li anode are presented.

关键词： lithium(Li)-ion battery(LIB) Li metal battery three-dimensional(3D)composite Li metal anode mechanical modification reducing local current density

Inference for accelerated bivariate dependent competing risks model based on Archimedean copulas under progressive censoring

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2023年第4期38卷 475-492页

作者： ZHANG Chun-fang shi Yi-min wang liang School of Mathematics and Statistics Xidian UniversityXi'an 710126China School of Mathematics and Statistics Northwestern Polytechnical UniversityXi'an 710129China School of Mathematics Yunnan Normal UniversityKunming 650500China

Dependent competing risks model is a practical model in the analysis of lifetime and failure modes.The dependence can be captured using a statistical tool to explore the re-lationship among failure causes.In this paper,an Archimedean copula is chosen to describe the dependence in a constant-stress accelerated life test.We study the Archimedean copula based dependent competing risks model using parametric and nonparametric methods.The parametric likelihood inference is presented by deriving the general expression of likelihood function based on assumed survival Archimedean copula associated with the model parameter estimation.Combining the nonparametric estimation with progressive censoring and the non-parametric copula estimation,we introduce a nonparametric reliability estimation method given competing risks data.A simulation study and a real data analysis are conducted to show the performance of the estimation methods.

关键词： dependent competing risks model accelerated life tests Archimedean copula nonparametric reliability estimation

Estimation for constant-stress accelerated life test from generalized half-normal distribution

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2017年第4期28卷 810-816页

作者： liang wang Yimin shi School of Mathematics and Statistics Xidian University Department of Applied Mathematics Northwestern Polytechnical University

In the constant-stress accelerated life test, estimation issues are discussed for a generalized half-normal distribution under a log-linear life-stress model. The maximum likelihood estimates with the corresponding fixed point type iterative algorithm for unknown parameters are presented, and the least square estimates of the parameters are also proposed. Meanwhile, confidence intervals of model parameters are constructed by using the asymptotic theory and bootstrap technique. Numerical illustration is given to investigate the performance of our methods.

关键词： accelerated life test maximum likelihood estimation least square method bootstrap technique asymptotic distribution

Dependence Rayleigh competing risks model with generalized censored data

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2020年第4期31卷 852-858页

作者： wang liang MA Jin’ge shi Yimin School of Mathematics and Statistics Xi’an Jiaotong UniversityXi’an 710049China School of Mathematics Yunnan Normal UniversityKunming 650500China School of Mathematics and Statistics Xidian UniversityXi’an 710071China Department of Applied Mathematics Northwestern Polytechnical UniversityXi’an 710072China

The inference for the dependent competing risks model is studied and the dependent structure of failure causes is modeled by a Marshall-Olkin bivariate Rayleigh distribution. Under generalized progressive hybrid censoring(GPHC), maximum likelihood estimates are established and the confidence intervals are constructed based on the asymptotic theory. Bayesian estimates and the highest posterior density credible intervals are obtained by using Gibbs sampling. Simulation and a real life electrical appliances data set are used for practical illustration.

关键词： dependence competing risks bivariate distribution generalized progressive hybrid censoring(GPHC) likelihood estimation Bayesian analysis

Advances of high-performance LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathode materials and their precursor particles via co-precipitation process

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第3期86卷 67-85页

作者： Wenbiao liang Yin Zhao Liyi shi Zhuyi wang Yi wang Meihong Zhang Shuai Yuan School of Materials Science and Engineering Shanghai UniversityShanghai200444China Research Center of Nanoscience and Nanotechnology Shanghai UniversityShanghai200444China Emerging Industries Institute Shanghai UniversityJiaxingZhejiang314006China

Layered LiNi_(1-x-y)Co_(x)M_(y)O_(2)(M=Mn or Al)is a promising cathode material for lithium-ion batteries due to its high specific capacity and acceptable manufacturing cost.However,the polycrystalline LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathode material suffers from disordered orientation of primary particles and poor geometric symmetry of secondary particles,which severely hampers the migration of Lit ions.Furthermore,the resulting anisotropy accelerates the disintegration of the secondary particle structure,significantly affecting the electrochemical performance of the polycrystalline cathode.In spite of less grain boundary,the single-crystal LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathodes still suffer from severe microcracks generated by repeated planar gliding during cycling,which poses a great challenge to the cycling stability of single-crystal materials.It's worth noting that the microstructure of the cathode material is mainly inherited from its precursor.Therefore,it is necessary to deeply understand the influence of the microstructure of Ni_(1-x-y)Co_(x)M_(y)(OH)2 on the electrochemical properties of LiNi_(1-x-y)Co_(x)M_(y)O_(2) cathode materials,so as to optimize the production process of preparing high-performance cathode precursors.In this review,we summarize recent advances in the research and development of Ni-rich cathode precursor materials.Firstly,the challenges faced by the Ni-rich hydroxide precursor materials are presented,including the effect of primary particle morphology and arrangement on the electrochemical performance of cathode materials,the influence of secondary particle morphology on lithium insertion reactions in cathode,and the effect of particle size on the microcracking of single-crystal particles.Secondly,the presentation of the conventional co-precipitation reactor,the mechanism of precursor particle growth,and the influence of coprecipitation parameters are described in detail.Finally,the strategies are systematically discussed to solve the challenges of hydroxide precursors,such as the inno

关键词： Lithium-ion batteries Cathode materials Co-precipitation Ni-rich layered oxides Single crystal Precursor particles

Observational Subseasonal Variability of the PM_(2.5) Concentration in the Beijing-Tianjin-Hebei Area during the January 2021 Sudden Stratospheric Warming

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2022年第10期39卷 1623-1636页

作者： Qian LU Jian RAO Chunhua shi Dong GUO Ji wang Zhuoqi liang Tian wang Key Laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing 210044China Key Laboratory of Meteorology and Ecological Environment of Hebei Province Shijiazhuang 050021China Beijing Regional Climate Center Beijing 100089China

It is still not well understood if subseasonal variability of the local PM_(2.5) in the Beijing-Tianjin-Hebei(BTH)region is affected by the stratospheric state.Using PM_(2.5) observations and the ERA5 reanalysis,the evolution of the air quality in BTH during the January 2021 sudden stratospheric warming(SSW)is explored.The subseasonal variability of the PM_(2.5) concentration after the SSW onset is evidently enhanced.Stratospheric circumpolar easterly anomalies lasted for 53 days during the January-February 2021 SSW with two evident stratospheric pulses arriving at the ground.During the tropospheric wave weakening period and the intermittent period of dormant stratospheric pulses,the East Asian winter monsoon weakened,anomalous temperature inversion developed in the lower troposphere,anomalous surface southerlies prevailed,atmospheric moisture increased,and the boundary layer top height lowered,all of which favor the accumulation of pollutant particulates,leading to two periods of pollution processes in the BTH region.In the phase of strengthened East Asian winter monsoon around the very beginning of the SSW and another two periods when stratospheric pulses had reached the near surface,opposite-signed circulation patterns and meteorological conditions were observed,which helped to dilute and diffuse air pollutants in the BTH region.As a result,the air quality was excellent during the two periods when the stratospheric pulse had reached the near surface.The increased subseasonal variation of the regional pollutant particulates after the SSW onset highlights the important role of the stratosphere in the regional environment and provides implications for the environmental prediction.

关键词： sudden stratospheric warming(SSW) PM_(2.5) Beijing-Tianjin-Hebei(BTH) East Asian winter monsoon boundary layer meteorological conditions

Electrocatalytic Oxygen Reduction to Produce Hydrogen Peroxide:Rational Design from Single‑Atom Catalysts to Devices

在线全文

学校读者我要写书评

暂无评论

Electrochemical Energy Reviews 2022年第3期5卷 71-104页

作者： Yueyu Tong Liqun wang Feng Hou shi Xue Dou Ji liang Technology of Ministry of Education School of Materials Science and EngineeringTianjin UniversityTianjinChina Institute for Superconducting and Electronic Materials Australian Institute of Innovative MaterialsUniversity of WollongongInnovation CampusSquires WayNorth WollongongNSW 2500Australia Applied Physics Department College of Physics and Materials ScienceTianjin Normal UniversityTianjinChina

Electrocatalytic production of hydrogen peroxide(H_(2)O_(2))via the 2e^(-) transfer route of the oxygen reduction reaction(ORR)offers a promising alternative to the energy-intensive anthraquinone process,which dominates current industrial-scale production of H_(2)O_(2).The availability of cost-effective electrocatalysts exhibiting high activity,selectivity,and stability is imperative for the practical deployment of this process.Single-atom catalysts(SACs)featuring the characteristics of both homogeneous and heterogeneous catalysts are particularly well suited for H_(2)O_(2) synthesis and thus,have been intensively investigated in the last few years.Herein,we present an in-depth review of the current trends for designing SACs for H_(2)O_(2) production via the 2e^(-)ORR route.We start from the electronic and geometric structures of SACs.Then,strategies for regulating these isolated metal sites and their coordination environments are presented in detail,since these fundamentally determine electrocatalytic performance.Subsequently,correlations between electronic structures and electrocatalytic performance of the materials are discussed.Furthermore,the factors that potentially impact the performance of SACs in H_(2)O_(2)production are summarized.Finally,the challenges and opportunities for rational design of more targeted H_(2)O_(2)-producing SACs are highlighted.We hope this review will present the latest developments in this area and shed light on the design of advanced materials for electrochemical energy conversion.

关键词： Single-atom catalyst design Electrocatalytic H_(2)O_(2)production Oxygen reduction reaction Two-electron process

Biomaterial strategies for the application of reproductive tissue engineering

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Bioactive Materials 2022年第8期7卷 86-96页

作者： Xuemin Liu Kai Wu liang Gao Liping wang Xuetao shi National Engineering Research Centre for Tissue Restoration and Reconstruction and School of Material Science and Engineering South China University of TechnologyGuangzhou510640PR China School of Biomedical Science and Engineering South China University of TechnologyGuangzhou510640PR China School of Chemical Engineering and Light Industry Guangdong University of TechnologyGuangzhou510006PR China First Affiliated Hospital of Shenzhen University Reproductive Medicine CentreShenzhen Second People’s HospitalShenzhen518035PR China Key Laboratory of Biomedical Engineering of Guangdong Province South China University of TechnologyGuangzhou510006PR China

Human reproductive organs are of vital importance to the life of an individual and the reproduction of human populations.So far,traditional methods have a limited effect in recovering the function and fertility of reproductive organs and tissues.Thus,aim to replace and facilitate the regrowth of damaged or diseased tissue,various biomaterials are developed to offer hope to overcome these difficulties and help gain further research progress in reproductive tissue engineering.In this review,we focus on the biomaterials and their four main applications in reproductive tissue engineering:in vitro generation and culture of reproductive cells;development of reproductive organoids and models;in vivo transplantation of reproductive cells or tissues;and regeneration of reproductive tissue.In reproductive tissue engineering,designing biomaterials for different applications with different mechanical properties,structure,function,and microenvironment is challenging and important,and deserves more attention.

关键词： Biomaterials Reproductive tissue engineering Organoids and models