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Mechanism of Polymorph Selection during Crystallization of Random Butene-1/Ethylene Copolymer

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Chinese Journal of Polymer Science 2016年第8期34卷 1014-1020页

作者： yao-tao Wang Pei-ru Liu Ying Lu 门永锋 State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

Starting from an initial sample of butene-1/ethylene copolymer with stable form I＇, we examined the nucleation of different crystalline polymorphs （here metastable form II and stable form I＇） at different isothermal crystallization temperatures after being melted at different melt temperature （Tmelt）. When Tmelt was just above the melting temperature （Tm） of the crystallites, self-seeding took place. There, residue crystallites served as nuclei leading to the crystallization of the same crystalline phase. When Tmelt was a few degrees above the Tin, self-seeding was disabled due to complete melting of the initial crystals. Upon crystallization, the selection of the different polymorphs in this random copolymer was found to depend on an interplay between the domain size of segregated long crystallizable sequences and the size and energy barrier of the critical nucleus of the respective crystalline forms. Our results provide a clear understanding of the polymorphs selection during crystallization of a random copolymer as well as homo-polymers under confinement.

关键词： Crystallization Random copolymer Polybutene-1 Polymorphism.

OBSERVATION AND ANALYSIS ON CHARACTERISTIC OF NATURAL RIVERS

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Journal of Hydrodynamics 2005年第5期17卷 615-620页

作者： LU Jin-you XU Hai-tao yao Shi-ming Yangtze River Scientific Research Institute Wuhan 430010 China

Based on the previous study on turbulent structure, field experiments on fluctuation velocity were carried out in section Huanglingmiao of main stream of Yangtze River with a 3-D Doppler velocimeter. And a number of data such as velocity of different discharge and different vertical line were obtained. According to the field experiment data, period, frequency, period function and probability density function of large-scale coherent structure in natural river were prescribed by means of quantitative analysis. And the problem about distribution of time average velocity, turbulent intensity and Reynolds stress along depth were further analyzed and calculated. The results in this paper will deepen the understand of large-scale turbulent structure in natural river and so make the base for applying“turbulence theory” to water conservancy, hydroelectric, environment engineering and so on.

关键词： natural river large scale turbulence turbulent mechanism

A flexible and smart shape memory alloy composite sheet based on efficient and bidirectional thermal management

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International Journal of Smart and Nano Materials 2022年第2期13卷 315-329页

作者： Yang Yang Yongquan Wang tao yao Xiaojuan Feng School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an People’s Republic of China Shanghai Marine Diesel Engine Research Institute Shanghai People’s Republic of China

Leveraging advances in shape memory alloys(SMAs)and flexible thermoelectric devices(f-TEDs),this paper presents a structural and functional integrity composite sheet to address the inefficient and bulky activation of 2-D SMAs.A series of experimental tests were performed to reveal the generation,change,and transfer mechan-isms of different types of electrically-induced heat in the f-TED,as well as the temperature-induced SMA phase transformation *** results show that the composite sheet exhibited good bidirectional thermal management *** austenite defor-mation can be completed within 10s at an operating current of 2 *** cooling recovery,in particular,performs much better than in conventional modes(the temperature declines exponentially with time).Finally,through two functional prototypes,a light switch and a flexible gripper,the application potential of the proposed com-posite was further experimentally demonstrated.

关键词： Shape memory alloy flexible thermoelectric device bidirectional thermal management actuator thermomechanical

Synthesis and Characterization of the Copper Complex Pearlescent Pigment

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Journal of Harbin Institute of Technology(New Series) 2013年第1期20卷 42-45页

作者： Yong-tao yao Guo-Jun Yan Science and Technology on Advanced Composites in Special Environments Laboratory Harbin Institute of Technology

The copper complex pearlescent pigment was synthesized by the two steps diazotization and azo coupling. The crystal phases and the microstructure of the copper complex pearlescent pigment powders were characterized through a combination of DSC, FT-IR and SEM analysis after purification. The results indicated that the copper complex pearlescent pigment has very good thermal stability and the fine particle size is uniformly distributed, and the average grain size is around 15 μm.

关键词： pearlescent pigment copper complex pigment azo coupling

Absence of hexavalent chromium in marine carbonates:implications for chromium isotopes as paleoenvironment proxy

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National Science Review 2021年第3期8卷 151-158页

作者： Ziyao Fang Liping Qin Wei Liu tao yao Xiaoyan Chen Shiqiang Wei CAS Key Laboratory of Crust-Mantle Materials and Environments University of Science and Technology of China CAS Center for Excellence in Comparative Planetology National Synchrotron Radiation Laboratory University of Science and Technology of China

The oxygenation of Earth’s atmosphere is widely regarded to have played an important role in early-life ***(Cr) isotopes recorded in sedimentary rocks have been used to constrain the atmospheric oxygen level(AOL) over geological times based on the fact that a positive Cr isotopic signature is linked to the presence of Cr(Ⅵ) as a result of oxidative continental ***,there is no direct evidence of the presence of Cr(Ⅵ) in sedimentary rocks *** are most widely distributed over geological times and were thought to have incorporated Cr(Ⅵ) directly from ***,we present results of Cr valence states in carbonates which show Cr(Ⅲ) is the dominant species in all samples spanning a wide range of geological *** findings indicate that Cr(Ⅵ) in seawater was reduced either before or after carbonate precipitation,which might have caused Cr isotopic fractionation between seawater and carbonates,or marine carbonates preferentially uptake Cr(Ⅲ) from *** Cr(Ⅲ) can come from non-redox Cr cycling,which also can cause isotopic fractionation,we suggest that positively fractionated Cr isotopic values do not necessarily correspond to the rise in AOL.

关键词： Cr isotopes XANES speciation atmospheric oxygen level

Methods for Force Analysis of Overconstrained Parallel Mechanisms： A Review

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Chinese Journal of Mechanical Engineering 2017年第6期30卷 1460-1472页

作者： Wen-Lan Liu Yun-Dou Xu Jian-tao yao Yong-Sheng Zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao 066004 China Key Laboratory of Advanced Forging and StampingTechnology and Science of Ministry of National Education Yanshan University Qinhuangdao 066004 China

The force analysis of overconstrained PMs is relatively complex and difficult, for which the methods have always been a research hotspot. However, few liter- atures analyze the characteristics and application scopes of the various methods, which is not convenient for researchers and engineers to master and adopt them prop- erly. A review of the methods for force analysis of both passive and active overconstrained PMs is presented. The existing force analysis methods for these two kinds of overconstrained PMs are classified according to their main ideas. Each category is briefly demonstrated and evaluated from such aspects as the calculation amount, the compre- hensiveness of considering limbs＇ deformation, and the existence of explicit expressions of the solutions, which provides an important reference for researchers and engi- neers to quickly find a suitable method. The similarities and differences between the statically indeterminate prob- lem of passive overconstrained PMs and that of active overconstrained PMs are discussed, and a universal method for these two kinds of overconstrained PMs is pointed out. The existing deficiencies and development directions of the force analysis methods for overconstrained systems are indicated based on the overview.

关键词： Redundantly actuated PM ~ Passiveoverconstrained PM ~ Statically indeterminate problemForce analysis ~ Weighted generalized inverse

Analysis and Optimization of a Spatial Parallel Mechanism for a New 5-DOF Hybrid Serial-Parallel Manipulator

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Chinese Journal of Mechanical Engineering 2018年第3期31卷 60-68页

作者： Dong-Sheng Zhang Yun-Dou Xu Jian-tao yao Yong-Sheng Zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University

Hybrid manipulators have potentially application in machining industries and attract extensive attention from many researchers on the basis of high sti ness and high dexterity. Therefore,in order to expand the application prospects of hybrid manipulator,a novel 5?degree?of?freedom(DOF) hybrid serial?parallel manipulator(HSPM) is proposed. Firstly,the design plan of this manipulator is introduced. Secondly,the analysis of this manipulator is carried out in detail,including kinematics analysis,statics analysis,and workspace analysis. Especially,an amplitude equivalent method of disposing the over?constrained force/couple to the non?overconstrained force/couple is used in the statics analysis. Then,three performance indices are used to optimize the PM. Two of them have been widely used,and the third one is a new index which considers the characteristics of the actuated force. Based on the performance indices,the performance atlas is drawn and the optimal design of the PM is investigated. In order to satisfy the anticipant kinetic characteristics of the PM,the verification of the optimized physical dimension is done and the workspace based on the optimized physical dimension is carried out. This paper will lay good theoretical foundations for application of this novel HSPM and also can be applied to other hybrid manipulators.

关键词： Parallel mechanism Performance indices Optimal design Performance atlas

Coordinately unsaturated nickel single atom electrocatalyst for efficient CO_(2)conversion

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Nano Research 2023年第8期16卷 10873-10880页

作者： Wei Zhang Dong Liu Tong Liu Chenglong Ding tao Chen Yanming Li Xiaokang Liu Lan Wang Changli Li Jingfu He tao Ding tao yao School of Materials Sun Yat-Sen UniversityGuangzhou 510275China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China School of National Defense Science and Technology Southwest University of Science and TechnologyMianyang621010China

Single-atom catalysts(SACs)have shown unexpected catalytic activity due to their unique electronic structure and coordination ***,the synthesis of an atomically precise low-coordination single-atom catalyst remains a grand ***,we report a coordinately unsaturated Ni-N_(3)single-atom electrocatalyst using a metal-organic framework(MOF)derived N-C support with abundant exposed N for excellent electrochemical CO_(2)*** obtained Ni-N_(3)/NC active site exhibited highly efficient CO_(2)-to-CO conversion with a Faradaic efficiency of 94.6%at the current density of 100 mA/cm^(2).In situ X-ray absorption spectroscopy(XAS)measurement suggested that the Ni atomic center with unsaturated coordination had the lower initial chemical state and higher charge transfer *** situ Fourier transform infrared(FT-IR)and theoretical calculation results revealed that the unsaturated catalytically active center could facilitate activation of CO_(2)and thus heighten CO_(2)electroreduction *** findings provided insights into the rational design of definitive coordination structure of SACs for boosting activity and selectivity.

关键词： Ni single atom electrocatalyst in situ X-ray absorption spectroscopy in situ Fourier transform infrared

Recent advances in regulating the local environment of M-N_(4) structure for tailored chemical reactions

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Nano Research 2023年第7期16卷 8596-8613页

作者： Lan Wang Honglei Chen Yi Wang Xiaokang Liu Changli Li Jingfu He tao yao School of Materials Shenzhen Campus of Sun Yat-sen UniversityShenzhen 518107China National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Reactor Operation and Application Research Sub-Institute Nuclear Power Institute of ChinaChengdu 610041China

Single-atom catalysts(SACs)with M-N_(4)structure have drawn significant attention due to the facile preparation,maximum atom efficiency,unique electronic properties,uniform active sites,and excellent *** catalysts integrated the merits of traditional homogeneous and heterogeneous catalysts effectively solve the cost,activity,and reuse *** importantly,the M-N_(4)structure is flexible and other species like atoms,groups,and particles can be added to precisely control the local environment of M-N_(4)to further improve the catalytic *** unprecedented progress has been made,it remains difficulties in the rational design and controllable synthesis of a suitable SAC for a certain *** review introduces the progress of M-N_(4)catalysts and summarizes the strategies to modulate the M-N_(4)structure,including changing the coordination number,tailoring the coordination structure,coordinating with groups,creating dual-atom catalysts(DACs),and coexisting of SAC with DAC and *** emphasis is placed on the preparation,structure characterization,and reaction mechanism of M-N_(4)-derived ***,the current challenges of these catalysts are also discussed to provide guidelines for the future design of efficient catalysts.

关键词： M-N_(4)single-atom catalyst dual single-atom catalyst local environment structure-activity relationship