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Direct observation of Pt nanocrystal coalescence induced by electron-ex.itation-enhanced van der Waals interactions

Nano Research 2014年第3期7卷 308-314页

作者： Ying Jiang Yong Wang Yu Yang Zhang Zhengfei Zhang Wentao Yuan Chenghua Sun x.ao Wei Casey N. Brodsky Chia-Kuang Tsung Jix.e Li x.aofeng Zhang scott x. mao Shengbai Zhang Ze Zhang Center of Electron Microscopy and State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute Troy New York 12180 USA Centre for Computational Molecular Science Australian Institute for Bioengineering and Nanotechnology University of Queensland St Lucia QLD 4072 Australia Department of Chemistry Boston College Chestnut Hill MA 02467 USA Hitachi High Technologies America Pleasanton CA 94588 USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh PA 15261 USA

Nanocrystal coalescence has attracted paramount attention in nanostructure fabrication in the past decades. Tremendous endeavor and progress have been made in understanding its mechanisms, benefiting from the development of transmission electron microscopy. However, many mechanisms still remain unclear, especially for nanocrystals that lack a permanent dipole moment standing on a solid substrate. Here, we report an in situ coalescence of Pt nanocrystals on an amorphous carbon substrate induced by electron-ex.itation- enhanced van der Waals interactions studied by transmission electron microscopy and first principles calculations. It is found that the electron-beam-induced ex.itation can significantly enhance the van der Waals interaction between Pt nanocrystals and reduce the binding energy between Pt nanocrystals and the carbon substrate, both of which promote the coalescence. This work ex.ends our understanding of the nanocrystal coalescence observed in a transmission electron microscope and sheds light on a potential pathway toward practical electron- beam-controlled nanofabrication.

关键词： Pt nanocrystals coalescence electron ex.itation van der Waals interactions

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In situ observation of sublimation-enhanced magnesium ox.dation at elevated temperature

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Nano Research 2016年第9期9卷 2796-2802页

作者： Zijiao Zhang x.aoqian Fu Minmin mao Qian Yu scott x.mao Jix.e Li Ze Zhang Center of Electron Microscopy and State Key Laboratory of Silicon Materials Department of Materials Science & EngineeringZhejiang UniversityHangzhou 310027China Department of Mechanical Engineering & Materials Science University of PittsburghPittsburghPA 15261USA

Ox.dation plays a tremendous role in the long-term performance of metals. As an important lightweight metal for industrial applications, magnesium suffers from its high reactivity with ox.gen and increased evaporation at high temperatures. To understand the ox.dation mechanism of magnesium at elevated temperatures, in situ environmental transmission electron microscopy (E-TEM) was performed on magnesium nanoparticles. At a relatively low temperature, the growth of a MgO lamellae via the outward diffusion of bulk magnesium atoms dominated the ox.dation process. In contrast, a sublimation-enhanced ox.dation via gas phase reaction occurred at 200 °C, leading to the growth of MgO dendrites over the particle that finally leads to the degradation of the magnesium structure. This study provides a direct observation and model of the ox.dation mechanism of a direct gas–gas reaction that improves our understanding of the ox.dation mechanism at elevated temperatures. [Figure not available: see fulltex..] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

关键词： ox.dation magnesium sublimation nanoparticle

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In situ atomistic observation of the deformation mechanism of Au nanowires with twin–twin intersection

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Journal of Materials Science & Technology 2020年第18期52卷 118-125页

作者： Shuchun Zhao Qi Zhu x.anghai An Hua Wei Kex.ng Song scott x.mao Jiangwei Wang Center of Electron Microscopy and State Key Laboratory of Silicon Materials School of Materials Science&EngineeringZhejiang UniversityHangzhou 310027China School of Aerospace Mechanical&Mechatronic EngineeringThe University of SydneySydney 2006Australia Center for Hypergravity Ex.erimental and Interdisciplinary Research.Zhejiang University Hangzhou 310027China School of Materials Science&Engineering Henan University of Science and TechnologyLuoyang 471023China Department of Mechanical Engineering and Materials Science University of PittsburghPittsburgh Pennsylvania15261USA

Twin–twin intersections are often observed in face-centered cubic(FCC)metallic nanostructures,which have important contributions to the plastic deformation and strengthening of FCC metals with low stacking fault ***,a deep insight into the underlying mechanism involved in the formation and evolution of twin–twin intersections remains largely lacking,especially in ***,by conducting the in situ straining ex.eriments under high resolution transmission electron microscope(TEM),we directly visualize the dynamic evolution of a twin–twin intersection in Au nanowire at the *** shows that dislocations in the incoming twin can either glide onto or transmit across the barrier twin via dislocation interaction with the twin boundary,resulting in the twin–twin *** twinning and de-twinning of the twin–twin intersection govern the whole deformation of the *** findings reveal the dynamic behaviors of twin–twin intersection under mechanical loading,which benefits further ex.loration of FCC metals and engineering alloys with twin–twin intersection structures.

关键词： In situ TEM Twin-twin intersection Au nanowire Twinning/de-twinning Dislocation-twin interaction

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Discrete twinning dynamics and size-dependent dislocation-to twin transition in body-centred cubic tungsten

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Journal of Materials Science & Technology 2022年第11期106卷 33-40页

作者： Jiangwei Wang Anik H.M.Faisal x.yao Li Youran Hong Qi Zhu Hongbin Bei Ze Zhang scott x.mao Christopher R.Weinberger Center of Electron Microscopy and State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China Department of Mechanical Engineering Colorado State UniversityCO 80523USA School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Department of Mechanical Engineering and Materials Science University of PittsburghPittsburghPA 15261USA Wenzhou Key Laboratory of Novel Optoelectronic and Nano Materials Institute of WenzhouZhejiang UniversityWenzhou 325006China

Body-centred cubic(BCC) metals are known to have unstable intrinsic stacking faults and high resistance to deformation twinning, which can strongly influence their twinning behaviour. Though twinning mechanisms of BCC metals have been investigated for more than 60 years, the atomistic level dynamics of twinning remains under debate, especially regarding its impact on competition between twinning and slip. Here, we investigate the atomistic level dynamics of twinning in BCC tungsten(W) nanowires using in situ nanomechanical testing. Quantitative ex.erimental studies directly visualize that deformation twins in W nanowires have a minimum size of six.layers and grow in increments of approx.mately three-layers at a time, in contrast to the layer-by-layer growth of deformation twins in face-centred cubic metals. These unique twinning dynamics induces a strong competition with ordinary dislocation slip,as ex.ibited by a size-dependent dislocation-to-twin transition in W nanowires, with a transition size of ~40 nm. Our work provides physical insight into the dynamics of twinning at the atomic level, as well as a size-dependent dislocation-twinning competition, which have important implications for the plastic deformation in a broad class of BCC metals and alloys.

关键词： Body-centred cubic Deformation twin Twinning dynamics Dislocation-to-twin transition In situ nanomechanical testing

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Environmental landscape determinants of max.mum forest canopy height of boreal forests

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Journal of Plant Ecology 2019年第1期12卷 96-102页

作者： Lingfeng mao Christopher W.Bater John JStadt Barry White Piotr Tompalski Nicholas C.Coops scott E.Nielsen Department of Renewable Resources University of AlbertaEdmontonAlberta T6G 2H1Canada Forest Management Branch Forestry DivisionAlberta Agriculture and ForestryEdmontonAlberta T5K 2M4Canada Department of Forest Resource Management University of British ColumbiaVancouverBritish Columbia V6T 1Z4Canada

Aims Canopy height is a key driver of forest biodiversity and carbon *** estimates of canopy height are needed for assess-ing mechanisms relating to ecological patterns and processes of tree height *** global scales forest canopy height patterns are largely controlled by climate,while local variation at fine scales is due to differences in disturbance history and local patterns in envir-onmental *** relative effect of local environmental driv-ers on canopy height is poorly understood partly due to gaps in data on canopy height and methods for ex.mining limiting ***,we used airborne laser scanning(ALS)data on vegetation structure of boreal forests to ex.mine the effects of environmental factors on potential max.mum forest canopy *** Relationships between max.mum canopy height from ALS meas-ures and environmental variables were ex.mined to assess factors limiting tree ***,we used quantile regression at the 0.90 quantile to relate max.mum canopy height with environmental characteristics of climate(*** annual temperature[MAT]and mean annual precipitation),terrain(***)and depth-to-water(DTW)across a 33000 km2 multiple use boreal forest landscape in northeast Alberta,*** Findings Max.mum canopy height was positively associated with MAT,ter-rain slope and terrain-derived DTW,collectively ex.laining 33.2%of the variation in *** strongest ex.lanatory variable was DTW ex.laining 26%of canopy height variation with peatland forests having naturally shorter max.mum canopy heights,but also more sites currently at their max.mum potential *** con-trast,the most productive forests(*** to x.ric upland forests)had the fewest sites at their potential max.mum height,illustrating the effects of long-term forest management,wildfires and general anthropogenic footprints on reducing the ex.ent and abundance of older,taller forest habitat in Alberta’s boreal forest.

关键词： forest succession vegetation structure quantile regression remote sensing airborne laser scanning(ALS)

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Epidemiology, causes, clinical manifestation and diagnosis, prevention and control of coronavirus disease (COVID-19) during the early outbreak period: a scoping review

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Infectious Diseases of Poverty 2020年第2期9卷 90-91页

作者： Sasmita Poudel Adhikari Sha Meng Yu-Ju Wu Yu-Ping mao Rui-x.e Ye Qing-Zhi Wang Chang Sun Sean Sylvia scott Rozelle Hein Raat Huan Zhou West China School of Public Health and West China Fourth Hospital Sichuan UniversityChengduChina 不详

Background:The coronavirus disease(COVID-19)has been identified as the cause of an outbreak of respiratory illness in Wuhan,Hubei Province,China beginning in December *** of 31 January 2020,this epidemic had spread to 19 countries with 11791 confirmed cases,including 213 *** World Health Organization has declared it a Public Health Emergency of International ***:A scoping review was conducted following the methodological framework suggested by Arksey and O'*** this scoping review,65 research articles published before 31 January 2020 were analyzed and discussed to better understand the epidemiology,causes,clinical diagnosis,prevention and control of this *** research domains,dates of publication,journal language,authors'affiliations,and methodological characteristics were included in the *** the findings and statements in this review regarding the outbreak are based on published information as listed in the ***:Most of the publications were written using the English language(89.2%).The largest proportion of published articles were related to causes(38.5%)and a majority(67.7%)were published by Chinese *** articles initially focused on causes,but over time there was an increase of the articles related to prevention and *** thus far have shown that the virus7 origination is in connection to a seafood market in Wuhan,but specific animal associations have not been *** symptoms include fever,cough,fatigue,pneumonia,headache,diarrhea,hemoptysis,and *** measures such as masks,hand hygiene practices,avoidance of public contact,case detection,contact tracing,and quarantines have been discussed as ways to reduce *** date,no specific antiviral treatment has proven effective;hence,infected people primarily rely on symptomatic treatment and supportive ***:There has been a rapid surge in research in response to the outbreak of *** t

关键词： COVID-19 Epidemiology Causes Prevention and control Review

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Meet Uniform Continuous Posets

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Journal of Mathematical Research with Applications 2019年第5期39卷 459-468页

作者： x.x.n mao Luoshan x. College of Science Nanjing University of Aeronautics and Astronautics Department of Mathematics Yangzhou University

In this paper, as a generalization of uniform continuous posets, the concept of meet uniform continuous posets via uniform scott sets is introduced. Properties and characterizations of meet uniform continuous posets are presented. The main results are:(1) A uniform complete poset L is meet uniform continuous iff ↑(U ∩↓ x. is a uniform scott set for each x.∈ L and each uniform scott set U;(2) A uniform complete poset L is meet uniform continuous iff for each∨∨x. L and each uniform subset S, one has x.∧S ={x.∧ s | s ∈ S}. In particular, a complete lattice L is meet uniform continuous iff L is a complete Heyting algebra;(3) A uniform complete poset is meet uniform continuous iff every principal ideal is meet uniform continuous iff all closed intervals are meet uniform continuous iff all principal filters are meet uniform continuous;(4) A uniform complete poset L is meet uniform continuous if L1 obtained by adjoining a top element1 to L is a complete Heyting algebra;(5) Finite products and images of uniform continuous projections of meet uniform continuous posets are still meet uniform continuous.

关键词： uniform set uniform scott set complete Heyting algebra meet uniform continuous poset principal ideal uniform continuous projection

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Emerging contaminants:A One Health perspective

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The Innovation 2024年第4期5卷 140-170,139页

作者： Fang Wang Leilei x.ang Kelvin Sze-Yin Leung Martin Elsner Ying Zhang Yuming Guo Bo Pan Hongwen Sun Taicheng An Guangguo Ying Bryan WBrooks Deyi Hou Damian EHelbling Jianqiang Sun Hao Qiu Timothy MVogel Wei Zhang Yanzheng Gao Myrna JSimpson Yi Luo scott x.hang Guanyong Su Bryan MWong Tzung-May Fu Dong Zhu Karl JJobst Chengjun Ge Frederic Coulon Jean Damascene Harindintwali x.ankui Zeng Haijun Wang Yuhao Fu Zhong Wei Rainer Lohmann Changer Chen Yang Song Concepcion Sanchez-Cid Yu Wang Ali El-Naggar Yiming Yao Yanran Huang Japhet Cheuk-Fung Law Chenggang Gu Huizhong Shen Yanpeng Gao Chao Qin Hao Li Tong Zhang Natàlia Corcoll Min Liu Daniel SAlessi Hui Li Kristian KBrandt Yolanda Pico Cheng Gu Jianhua Guo Jianqiang Su Philippe Corvini mao Ye Teresa Rocha-Santos Huan He Yi Yang Meiping Tong Weina Zhang Fidèle Suanon Ferdi Brahushi Zhenyu Wang Syed AHashsham Marko Virta Qingbin Yuan Gaofei Jiang Louis A.Tremblay Qingwei Bu Jichun Wu Willie Peijnenburg Edward Topp x.nde Cao x.n Jiang Minghui Zheng Taolin Zhang Yongming Luo Lizhong Zhu x.angdong Li DamiàBarceló Jianmin Chen Baoshan x.ng Wulf Amelung Zongwei Cai Ravi Naidu Qirong Shen Janusz Pawliszyn Yong-guan Zhu Andreas Schaeffer Matthias C.Rillig Fengchang Wu Gang Yu James M.Tiedje State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Beijing 100049China Department of Chemistry Hong Kong Baptist UniversityHong KongChina HKBU Institute of Research and Continuing Education Shenzhen Virtual University ParkShenzhenChina Technical University of Munich TUM School of Natural SciencesInstitute of Hydrochemistry85748 GarchingGermany School of Resources&Environment Northeast Agricultural UniversityHarbin 150030China Climate Air Quality Research UnitSchool of Public Health and Preventive MedicineMonash UniversityMelbourneVICAustralia Faculty of Environmental Science&Engineering Kunming University of Science&TechnologyKunming 650500China Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria College of Environmental Science and EngineeringNankai UniversityTianjin 300350China Guangdong Key Laboratory of Environmental Catalysis and Health Risk Control School of Environmental Science and EngineeringInstitute of Environmental Health and Pollution ControlGuangdong University of TechnologyGuangzhou 510006China Ministry of Education Key Laboratory of Environmental Theoretical Chemistry South China Normal UniversityGuangzhouGuangdong 510006China Department of Environmental Science Baylor UniversityWacoTXUSA Center for Reservoir and Aquatic Systems Research(CRASR) Baylor UniversityWacoTXUSA School of Environment Tsinghua UniversityBeijing 100084China School of Civil and Environmental Engineering Cornell UniversityIthacaNY 14853USA Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province Zhejiang University of TechnologyHangzhou 310014China School of Environmental Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Laboratoire d’Ecologie Microbienne Universite Claude Bernard Lyon 1UMR CNRS 5557UMR INRAE 1418VetAgro Sup69622 VilleurbanneFrance Department of Pla

Environmental pollution is escalating due to rapid global development that often prioritizes human needs over planetary *** global efforts to mitigate legacy pollutants,the continuous introduction of new substances remains a major threat to both people and the *** response,global initiatives are focusing on risk assessment and regulation of emerging contaminants,as demonstrated by the ongoing efforts to establish the UN’s Intergovernmental Science-Policy Panel on Chemicals,Waste,and Pollution *** review identifies the sources and impacts of emerging contaminants on planetary health,emphasizing the importance of adopting a One Health *** for monitoring and addressing these pollutants are discussed,underscoring the need for robust and socially equitable environmental policies at both regional and international *** actions are needed to transition toward sustainable pollution management practices to safeguard our planet for future generations.

关键词： pollution planet contaminants

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GATSBY-A MODERN AMERICAN DON QUIx.TE

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西南大学学报(社会科学版) 1986年第S1期 93-98页

作者： mao Ruix.an

Francis scott Fitzgerald (1896—1940) won his international fame with hisThe Great Gatsby,which was published in 1925 but has always been somethingnew and ex.iting to literary critics and readers of many *** successfulportrayal of Jay Gatsby has made the fictional character a household name,alegendary figure,a symbol,and a modern American Don *** story takes place in the early 20’*** was then booming in thereestablished international order after World War I,yet it could hardly afford to

关键词： GATSBY-A MODERN AMERICAN DON QUIx.TE World DON

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锂离子电池电极材料力学问题研究

锂离子电池电极材料力学问题研究

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中国力学大会——2013

作者： He Yu Wang Yanhong Zheng Jieyun Zheng Hao Luo Fei Fan Feifei Zhu Ting Wang Jiangwei mao scott x. Aifantis K.E. Li Hong Chen Liquan Huang x.ejie 中国科学院物理研究所

将基于在高容量硅负极方面的与力学行为有关的几个研究,包括:(1)致密硅薄膜的裂纹演化;(2)无定形Ti-Si复合膜的裂纹演化;(3)微柱与微孔膜的裂纹演化;(4)硅微柱体积变化的有限元模拟;(5)采用扫描探针显微技术中力曲线模式实现Si表面固体...

将基于在高容量硅负极方面的与力学行为有关的几个研究,包括:(1)致密硅薄膜的裂纹演化;(2)无定形Ti-Si复合膜的裂纹演化;(3)微柱与微孔膜的裂纹演化;(4)硅微柱体积变化的有限元模拟;(5)采用扫描探针显微技术中力曲线模式实现Si表面固体电解质膜杨氏模量三维分布的测量等,结合文献工作,分析锂离子电池中的力学问题。

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