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Anisotropic corrosion behavior of hot-rolled Mg-8 wt.%Li alloy

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Journal of Materials Science & Technology 2020年第18期52卷 102-111页

作者： Baojie Wang kai xu Daokui xu Xiang Cai Yanxin Qiao Liyuan Sheng School of Environmental and Chemical Engineering Shenyang Ligong University.Shenyang.110159China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang212003China Peking University Shenzhen InstituteShenzhen Key Lab Human Tissue Regenerate RepairShenzhen518057China

By performing the immersion,hydrogen evolution and electrochemical corrosion testing in a 0.1 mol/L NaCl solution,the corrosion performance of differently oriented samples cut from an as-rolled Mg-8wt.%Li alloy plate has been investigated and *** demonstrated that obvious anisotropy in corrosion resistance existed between the sample surfaces with different *** them,the corrosion rate of"ND"(the normal direction)samples with their surfaces perpendicular to the normal direction of the plate was the *** corrosion rate of"TD"(the transverse direction)samples with their surfaces perpendicular to the transverse direction of the plate took the second *** the"RD"(the rolling direction)samples with their surfaces perpendicular to the rolling direction of the plate,they had the lowest corrosion *** all the samples,their corrosion performance and the pitting severity were mainly ascribed to the crystallographic texture ofα-Mg matrix phases because the formed surface films onβ-Li phases could provide good protection to the *** the"ND"and"TD"samples,the exposed surfaces were composed of{0002},{1010}and{1120}planes ofα-Mg phases and subsequently resulted in their severe corrosion attack due to the corrosion couples between basal and prism *** the crystallographic planes of exposedα-Mg phases on the surfaces of"RD"samples were mainly{1010}and{1120}prism planes,the pitting severity was the weakest.

关键词： Mg-Li alloys Texture Anisotropic corrosion Pitting Crystallographic plane

Molecular Dynamics Study of Star Polymer Melts under Start-up Shear

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Chinese Journal of Polymer Science 2022年第7期40卷 807-816页

作者： Dong-Dong Wang kai-Feng Yu Xiao-Lei xu Wen-Sheng xu Key Laboratory of Automobile Materials Ministry of Education and College of Materials Science and EngineeringJilin UniversityChangchun130025China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun130022China

It has been established that star polymers with a large number of arms display both the conventional chain relaxation and a slower interchain relaxation due to the formation of hard cores,which is called the local structural ***,we demonstrate that this unique relaxation property of multi-arm stars leads to unusual rheological *** study the response of star polymer melts with various arm numbers to start-up shear flow via nonequilibrium molecular dynamics *** simulation results indicate that the stress-strain response of multi-arm star polymer melts differs from that of star polymers with a small number of arms in both quantitative and qualitative *** the multi-arm star polymer melts exhibit an overshoot peak in the stress-strain curve both at relatively small and sufficiently large shear rates,two overshoot peaks appear when the flow strength is comparable to the relaxation time of the star *** double stress overshoot is absent in linear polymers and star polymers with a small number of arms and is evidently related to the presence of the local structural relaxation in star polymers with a large number of *** present a detailed analysis of the conformational and dynamical properties of star polymer melts under start-up shear to gain a molecular understanding of their stress response.

关键词： Simulation Star polymer Start-up shear

Practical privacy-preserving compressed sensing image recovery in the cloud

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Science China(Information Sciences) 2017年第9期60卷 277-285页

作者： kai HUANG Ming xu Shaojing FU Dongsheng WANG College of Computer National University of Defense Technology State Key Laboratory of Cryptology

Imaging technology plays a significant role in various fields such as astronomy,monitoring,and medical *** traditional Shannon/Nyquist sampling theorem specifies that one must sample at least two times faster than the signal bandwidth to avoid loss of information when capturing an *** makes compression a necessity prior to storage or transmission[1]and may be

关键词： OMP Practical privacy-preserving compressed sensing image recovery in the cloud

Fast and furious:insights of back splicing regulation during nascent RNA synthesis

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Science China(Life Sciences) 2021年第7期64卷 1050-1061页

作者： Wei xue xu-kai Ma Li Yang CAS Key Laboratory of Computational Biology Shanghai Institute of Nutrition and HealthUniversity of Chinese Academy of SciencesChinese Academy of SciencesShanghai 200031China School of Life Science and Technology ShanghaiTech UniversityShanghai 201210China

Alternative splicing of eukaryotic precursor(messenger)RNAs in the nucleus not only increases transcriptomic complexity,but also expands proteomic and functional *** addition to basic types of alternative splicing,recent transcriptome-wide analyses have also suggested other new types of non-canonical splicing,such as back splicing and recursive splicing,and their widespread expression across *** lines of evidence have suggested mechanisms for back splicing,including insights from analyses of nascent RNA *** this review,we discuss our current understanding of back splicing regulation,and highlight its distinct characteristics in processing during nascent RNA synthesis by taking advantage of metabolic tagging nascent RNA *** of recursive splicing are also discussed in the perspective of nascent RNA sequencing.

关键词： alternative splicing back splicing deep sequencing nascent RNA-seq metabolic tagging 4sUDRB-seq transcription recursive splicing

Quantitative ^(31)P NMR Analysis of Lignocellulosic Materials in Ionic Liquids

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Chemical Research in Chinese Universities 2010年第3期26卷 488-490页

作者： SUN Hui xu Ying-kai xu Guo-zhi Department of Materials Science and Engineering National Center for Quality Supervision and Test of Plastic Products Beijing Technology and Business University Beijing 100048 P R. China Department of Surgery University of Pittsburgh Pennsylvania 15213 USA

In an effort to utilize NMR technique for the analysis of the structural components of wood and biomasses such as lignin, we made a comparative study of lignin contents of several types of lignocellulosie materials both before and after enzymatic hydrolyses. To this end, Eucalyptus Globulus, Norway spruce thermomeehanieal pulp（TMP） corn stover and Eucalyptus kraft pulp were ball-milled and treated with cellulase to prepare materials with high lignin contents. These materials were analyzed via ^31p NMR in ionic liquids. The results show that the contents of various functional groups for the lignocellulosic materials after enzymatic hydrolyses are generally in agreement with those from their corresponding enzymatic mild acidolysis liginins（EMALs）, indicating that ^31p NMR analysis of lignocellulosic materials in ionic liquids is a promising method for quantitative characterization of lignocellulosic materials.

关键词： Structural characterization ^31p NMR Enzymatic mild acidolysis lignin(EMAL)

Skeleton-Based Human Action Recognition via Screw Matrices

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Chinese Journal of Electronics 2017年第4期26卷 790-796页

作者： DING Wenwen LIU kai xu Biao CHENG Fei School of Computer Science and Technology Xidian University School of Mathematical Sciences Huaibei Normal University

With the recent advent of low-cost acquisition depth cameras, extracting 3D body skeleton has become relatively easier, which significantly lighten many difficulties in 2D videos including occlusions, shadows and background extraction, etc. Directly perceived features,for example points, lines and planes, can be easily extracted from 3D videos such that we can employ rigid motions to represent skeletal motions in a geometric *** apply screw matrices, acquired by using rotations and translations in 3D space, to model single and multi-body rigid motion. Since screw matrices are members of the special Euclidean group SE(3), an action can be represented as a point on a Lie group, which is a differentiable manifold. Using Lie-algebraic properties of screw algebra, isomorphic to se(3), the classical algorithms of machine learning in vector space can be expanded to manifold space. We evaluate our approached on three public3 D action datasets: MSR Action3 D dataset, UCF Kinect dataset and Florence3D-Action Dataset. The experimental results show that our approaches either match or exceed state-of-the-art skeleton-based human action recognition approaches.

关键词： Skeleton joints Human activity recogni tion Screw algebra Lie group Lie algebra

A robotic laparoscopic tool with enhanced capabilities and modularactuation

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Science China(Technological Sciences) 2019年第1期62卷 47-59页

作者： DAI ZhengChen WU ZhongHao ZHAO JiangRan xu kai The RII Lab(Lab of Robotics Innovation and Intervention) UM-SJTU Joint Institute Shanghai Jiao Tong University State Key Laboratory of Mechanical System and Vibration School of Mechanical Engineering Shanghai Jiao Tong University

Due to the improved treatment outcomes, research on robotic MIS(Minimally Invasive Surgery) thrived in the past decades. A benchmark example is the da Vinci system that dominates robotic laparoscopy via its technology excellence and strong holding of intellectual properties. This study provides an alternative approach to realize robotic laparoscopic surgeries, by presenting the development and experimentation of the SMARLT(Strengthened Modularly Actuated Robotic Laparoscopic Tool) for MIS. A dual continuum mechanism is used in the design to achieve enhanced distal dexterity, improved reliability, increased payload capability, and actuation modularity. With kinematics modelling and actuation compensation, the SMARLT can be manipulated by a generic manipulator to carry out typical laparoscopic MIS tasks, such as tissue peeling, suturing, and knot tying. Payload capability was also experimentally characterized. The SMARLT-manipulator system essentially formed a continuum-rigid hybrid structure that makes full use of the advantages from each component: the continuum mechanism as a wrist for distal dexterity and other rigid parts for position accuracy and payload capability. With the experimental demonstration of the desired functionalities, the SMARLT design can lead to promising opportunities for commercialization.

关键词： dexterous wrist dual continuum mechanism medical robotics modular laparoscopic tools surgical instruments

Isolation of Hemicellulose from Wood Chips via Extraction with Kraft Green Liquor

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Chemical Research in Chinese Universities 2010年第4期26卷 667-671页

作者： SUN Hui xu Ying-kai xu Guo-zhi Department of Material Science and Engineering China National Center for Quality Supervison ＆ Test of Plastic Products Beo＇ing Technology and Business University Beijing 100048 P. R. China Department of Surgery University of Pittsburg 3459 Fifth Avenue Pittsburgh PA USA

The present paper covers the extraction of hemicelluloses from woods, i.e., Eucalyptus Globulus, white fir and Douglas fir via green liquor pretreatment and alkali post-treatment with sodium hydroxide. The effects of such extraction conditions as extraction time, temperature on the yields of hemicellulose and the degree of deliginification were investigated. Sugar analyses using Dionex indicate that xylose, glucose and mannose are the main sugar types present in the hemicellulose from Eucalyptus. Other sugar components such as arabinose and galactose were also found in Dogulas fir hemicellulose. The highest yield of hemicellulose was 8.4% for Eucalyptus extracted with green liquor at 130 ℃ for 3.5 h. Further sodium hydroxide extraction for 5 h gave a hemicellulose yield of about 20%. The use of green liquor for the extraction of wood hemicellulose is believed to be the first attempt.

关键词： Hemicellulose Lignin Wood Green liquor Alkali extraction

Experimental study of wave propagation characteristics on a simplified coral reef

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Journal of Hydrodynamics 2020年第2期32卷 385-397页

作者： Jia-yi xu Shu-xue Liu Jin-xuan Li Wei Jia State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian116024China

The wave transformation over slope topography is widely studied,but most of studies are for common coastal *** paper presents an experimental study of 2-D regular and irregular wave transformations on a simplified coral reef with a steep slope of 1:5 and a horizontal reef flat,focusing on the characteristics of the waves that break on the reef *** analyzed results show that the estimates of the wave breaking made by using the well-known previous formulae do not agree completely with the experimental *** the waves break on a reef flat,the relative breaking wave height(H/d)b is related to the incident deep-water wave steepness and the relative water depth db/***,a new criterion for breaking waves on a reef flat is ***,in view of the fact that the local Ursell number is commonly used to parameterize the wave nonlinearity,the relationships among the skewness,the asymmetry,and the local Ursell number are also *** data confirm that when the Ursell number is greater than 30,the absolute values of the skewness and the asymmetry on a reef flat are greater than those on a steep slope.

关键词： Coral reef bathymetry wave breaking wave height attenuation representative wave parameter nonlinear parameters