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Acta Mechanica Solida Sinica 2012年第6期25卷 562-570页

作者： Guobin gong Peng Lin Yawei Qin jun Wei Department of Civil Engineering Shantou University School of Civil and Environmental Engineering Shenzhen Graduate SchoolHarbin Institute of Technology School of Civil Engineering and Mechanics Huazhong University of Science and Technology Hubei Key Laboratory of Control Structure Huazhong University of Science and Technology School of Civil Engineering Central South University

Based on three dimensional （3D） Discrete Element Method （DEM）, the paper presents simulation results of undrained tests on loose assemblies of polydisperse spheres under axisymmet- ric compression and plane strain conditions using a periodic cell. In the present work, undrained tests were modelled by deforming the samples under constant volume conditions. The undrained （effective） stress paths are shown to be qualitatively similar to experimental results in literature. A microscopic parameter in terms of redundancy factor （RF） is used to identify the onset of lique- faction （or temporary liquefaction）, with the condition of RF equal to unity defining the transition from ＇solid-like＇ to ＇liquid-like＇ behaviour. It is found that the undrained behaviour is governed by the evolution of redundancy factor under both undrained axisymmetric compression and plane strain conditions, and a reversal of deviatoric stress in stress path for medium loose systems oc- curs due to the fact that the system becomes a structural mechanism （RF 〈 1） transiently at the microscopic level during the evolution.

关键词： discrete element deviatoric stress periodic cell liquefaction redundancy factor

Microbiological synthesis of nanophase PbS by Desulfotomaculum sp.

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Science China(Technological Sciences) 2007年第3期50卷 302-307页

作者： gong jun ZHANG ZhaoMing BAI HongJuan YANG GuanE Life Science and Technology Institute Shanxi UniversityTaiyuan 030006China Department of Environmental Economics Shanxi University of Finance and EconomicsTaiyuan 030006China

The uniform nanoparticles PbS with diameters about 13 nm could be synthesized by Desulfotomaculum sp. under mild condition. The effects of the processing vari-ables such as pH and temperature were investigated. The obtained products were in detailed by means of transmission electron microscopy(TEM) and X-ray diffraction(XRD) ,respectively. The results revealed that the PbS crystallites were identical in structure,shape and size under different temperatures while their morphology changed from rod to spheroidal with pH increasing. In the biological synthetic process for PbS nanoparticles,Desulfotomaculum sp. can use sulfate as a terminal electron acceptor to produce sulfide which acts as the source of sulfur for the formation of PbS nanoparticles.

关键词： lead sulfide microbial method nanoparticles transmission electron microscopy X-ray diffraction

Glacial Refugia of Ginkgo biloba and Human Impact on Its Genetic Diversity:Evidence from Chloroplast DNA

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Journal of Integrative Plant Biology 2008年第3期50卷 368-374页

作者： Wei gong Zhen Zeng ye-ye Chen Chuan Chen Ying-Xiong Qiu Cheng-Xin Fu Laboratory of Systematic Evolutionary Botany and Biodiversity and State Conservation Center for Gene Resources of Endangered Wildlife College of Life Sciences Zhejiang University Hangzhou 310058 China

Variations in the trnK region of chloroplast DNA were investigated in the present study using polymerase chain reactionrestriction fragment length polymorphism to detect the genetic structure and to infer the possible glacial refugia of Ginkgo biloba L. in China. In total, 220 individuals from 12 populations in China and three populations outside China were analyzed, representing the largest number of populations studied by molecular markers to date. Nineteen haplotypes were produced and haplotype A was found in all populations. Populations in south-western China, including WC, JF, PX, and SP, contained 14 of the 19 haplotypes and their genetic diversity ranged from 0.771 4 to 0.867 6. The TM population from China also showed a high genetic diversity （H = 0.848 5）. Most of the genetic variation existed within populations and the differentiation among populations was low （GsT = 0.2）. According to haplotype distribution and the historical record, we suggest that populations of G. biloba have been subjected to extensive human impact, which has compounded our attempt to infer glacial refugia for Ginkgo. Nevertheless, the present results suggest that the center of genetic diversity of Ginkgo is mainly in south-western China and in situ conservation is needed to protect and preserve the genetic resources.

关键词： chloroplast DNA Ginkgo biloba glacial refugia human activities polymerase chain reaction-restriction fragment length polymorphism

Rhodium（lll）/Amine Synergistically Catalyzed Enantioselective Alkylation of Aldehydes with α,β-Unsaturated 2-Acyl Imidazoles

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Chinese Journal of Chemistry 2016年第12期34卷 1225-1235页

作者： jun gong Kuan Li Saira Qurban Qiang Kang Key Laboratory of Coal to Ethylene Glycol and Its Related Technology Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 China Department of Chemistry Fuzhou University Fuzhou Fujian 350108 China

A synergistic catalysis combination of chiral-at-metal rhodium complex and amine catalyst was developed for enantioselective alkylation of aldehydes with α,β-unsaturated 2-acyl imidazoles. The corresponding adducts ... 详细信息

关键词： alkylation of aldehyde chiral-at-metal complex synergistic catalysis

DIRECT MEASUREMENT OF WEAK DEPLETION FORCE BETWEEN TWO SURFACES

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Chinese Journal of Polymer Science 2011年第1期29卷 1-11页

作者： Xiang-jun gong Xiao-chen Xing Xiao-ling Wei To Ngai Department of Chemistry the Chinese University ofHong Kong Shatin N.T. Hong Kong China Department of Physics the Chinese University ofHong Kong Shatin N.T. Hong Kong China

In a mixture of colloidal particles and polymer molecules, the particles may experience an attractive ＂depletion force＂ if the size of the polymer molecule is larger than the interparticle separation. This is because individual polymer molecules experience less conformational entropy if they stay between the particles than they escape the inter-particle space, which results in an osmotic pressure imbalance inside and outside the gap and leads to interparticle attraction. This depletion force has been the subject of several studies since the 1980s, but the direct measurement of this force is still experimentally challenging as it requires the detection of energy variations of the order of kBT and beyond. We present here our results for applying total internal reflection microscopy （TIRM） to directly measure the interaction between a free-moving particle and a flat surface in solutions consisting of small water-soluble organic molecules or polymeric surfactants. Our results indicate that stable nanobubbles （ca. 150 nm） exist free in the above aqueous solutions. More importantly, the existence of such nanobubbles induces an attraction between the spherical particle and flat surface. Using TIRM, we are able to directly measure such weak interaction with a range up to 100 nm. Furthermore, we demonstrate that by employing thermo^sensitive microgel particles as a depleting agent, we are able to quantitatively measure and reversibly control kBT-scale depletion attraction as function of solution pH.

关键词： Depletion interaction Total internal reflection microscopy (TIRM) Nanobubbles Microgel particles

TiAlN/Cu Nanocomposite Coatings Deposited by Filtered Cathodic Arc Ion Plating

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Journal of Materials Science & Technology 2017年第1期33卷 111-116页

作者： Lei Chen Zhiliang Pei Jinquan Xiao jun gong Chao Sun institute of metal research chinese academy of sciencesShenyang 110016China

TiAIN]Cu nanocomposite coatings with Cu concentration of 0-1.4 at.% were deposited on the high- speed steel （HSS） substrates by filtered cathodic arc ion plating technique. The chemical composition, microstructure, morphology, adhesion strength, mechanical and tribological properties of the TiAIN/Cu coatings were characterized and analyzed. The results reveal that the coating structure and properties depend on not only the Cu concentration, hut also the deposition condition. The addition of Cu significantly decreases the grain size and weakens the texture in the TiAlN/Cu coatings. With increasing the Cu concentration, the coating hardness decreases slightly from 30.7 GPa of the pure TiAlN coating to 28.5 GPa of the TiAlN/Cu coating with 1.4 at,% Cu. All the TiAlN/Cu coatings present sufficient adhesion strength. In addition, the existing state of additive Cu in the TiAlN/Cu coatings is also investigated.

关键词： TiAlN TiAIN/Cu Nanocomposite coating Filtered cathodic arc ion plating Co-deposition

Ten years after Hurricane Katrina： monitoring recovery in New Orleans and the surrounding areas using remote sensing

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Science Bulletin 2016年第18期61卷 1460-1470页

作者： Xuecao Li Le Yu Yidi Xu jun Yang Peng gong Ministry of Education Key Laboratory for Earth System Modeling Center for Earth System Science Tsinghua University Beijing 100084 China Joint Center for Global Change Studies Beijing 100875 China School of Geographic Sciences East China Normal UniversityShanghai 200241 China

Remote sensing data have been widely used in pre-hazard prevention/preparation, emergency response and post-hazard recovery monitoring. Hurricane Katrina caused serious damage to the environment, society and economy in the southern United States in 2005. On the 10 th anniversary of Hurricane Katrina, we monitored the recovery process in New Orleans and the surrounding area based on remote sensing. Results from multi-source remote sensing data indicated that the average vegetation conditions of the affected areas have not fully recovered compared with the pre-disaster conditions, especially in the hurricane's landfall area. Analysis from moderate resolution Landsat data showed that many civil engineering works have been undertaken in the city of New Orleans to prevent future disasters. Frequent observation using highresolution images recorded the progress of some of these civil construction projects(e.g. the 17 th Street Canal pumping station) in New Orleans. In this case study, we illustrated the capabilities of remote sensing techniques in recovery monitoring following a natural disaster. International/institutional cooperation is suggested to improve Earth observation capability in hazard monitoring. More Chinese Earth observation data are expected to be used in international monitoring.

关键词： MODIS Landsat High-resolutionimages Change detection Natural hazard

Enhancing the terrain adaptability of a multirobot cooperative transportation system via novel connectors and optimized cooperative strategies

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Frontiers of Mechanical Engineering 2023年第3期18卷 79-97页

作者： Quan LIU Zhao gong Zhenguo NIE Xin-jun LIU State Key Laboratory of Tribology in Advanced Equipment&Institute of Manufacturing Engineering Department of Mechanical EngineeringTsinghuaUniversityBeijing 100084China Beijing Key Laboratory of Precision/Ultra-precision Manufacturing Equipments and Control Tsinghua UniversityBejing 100084China

Given limited terrain adaptability,most existing multirobot cooperative transportation systems(MRCTSs)mainly work on flat pavements,restricting their outdoor *** connectors'finite deformation capability and the control strategies'limitations are primarily responsible for this *** study proposes a novel MRCTS based on tracked mobile robots(TMRs)to improve terrain adaptability and expand the application scenarios of *** structure design,we develop a novel 6-degree-of-freedom passive adaptive connector to link multiple TMRs and the transported object(the communal payload).In addition,the connector is set with sensors to measure the position and orientation of the robot with respect to the object for feedback *** the control strategy,we present a virtual leader-physical follower collaborative *** leader robot is imaginary to describe the movement of the entire system and manage the follower *** the TMRs in the system act as follower robots to transport the object *** divided the whole control structure into the leader robot level and the follower robot level,we convert the motion control of the two kinds of robots to trajectory tracking control problems and propose a novel double closed-loop kinematics control ***,a control law satisfying saturation constraints is derived to ensure transportation *** adaptive control algorithm processes the wheelbase uncertainty of the ***,we develop a prototype of the TMR-based MRCTS for *** the trajectory tracking experiment,the developed MRCTS with the proposed control scheme can converge to the reference trajectory in the presence of initial tracking errors in a finite *** the outdoor experiment,the proposed MRCTS consisting of four TMRs can successfully transport a payload weighing 60 kg on an uneven road with the single TMR's maximum load limited to 15 *** experimental results demonstrate the effectiveness of

关键词： multirobot system cooperative transportation terain adaptability trajectory tracking collaborative paradigm uneven road

Sea Cucumber-like Polyaniline Nanofibers Synthesized by Aqueous Solution Method

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Journal of Materials Science & Technology 2010年第1期26卷 39-44页

作者： Baoyun Liu Li Liu Nanlin Shi jun gong Chao Sun State Key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences 72 Wenhua Road Shenyang 110016 China Graduate School of Chinese Academy of Sciences Beijing 100039 China

The preparation of polyaniline nanofibers in aqueous solution was studied as functions of the concentrations and ratios of reactants. The morphology and microstructure of polyaniline nanofibers are affected by the concentrations and proportions of the reactants. A special kind of sea cucumber-like polyaniline nanofibers can be prepared under control of reaction conditions. Secondary growth is the formation mechanism. In addition, the bulk electrical conductivity of these sea cucumber-like polyaniline nanofibers was higher than that of other common polyaniline nanofibers.

关键词： Polyaniline Nanofiber Aqueous solution method Morphology Electrical conductivity

Effect of Heat Treatment on the Microstructure and Residual Stresses in (Ti,Al)N Films

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Journal of Materials Science & Technology 2011年第5期27卷 385-392页

作者： Ving Yang Shengsheng Zhao jun gong Xin Jiang Chao Sun State Key Laboratory of Corrosion and Protection Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China Instituteof Materials Engineering University of Siegen Paul-Bonatz-Str. 9-11 Siegen 57076 Germany

（Ti,AI）N films were fabricated by arc ion plating （ALP） and then annealed within a range of temperatures from 200 to 500℃ for 30 rain in vacuum. The results indicate that the average residual stresses decrease slightly from -5.84 to -4.98 GPa with increasing annealing temperature. The stress depth distribution evolves from a sharp ＂bell＂ shape to a mild ＂bell＂ shape, suggesting a more uniform stress state in the annealed films. The microstructure of the films was also investigated in detail. The as-deposited film consists of fine columnar crystals with an amorphous phase at the interface. During heat treatment, the columnar subgrain growth was observed; meanwhile, the phenomenon of crystallization has been identified at the interface. Further more, the relationship between the residual stresses and the microstructure of the films was explored and highlighted. In addition, there is no hardness degradation of the films during heat treatment.

关键词： Arc ion plating Heat treatment Microstructure Stress distribution (Ti,AI)N