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Atomic-scale dissecting the formation mechanism of gradient nanostructured layer on Mg alloy processed by a novel high-speed machining technique

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Journal of Materials Science & Technology 2021年第23期82卷 227-238页

作者： Hui Fu Xiaoye Zhou Bo Wu Lei Qian xu-sheng Yang State Key Laboratory of Ultra-precision Machining Technology Advanced Manufacturing Technology Research CentreDepartment of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute ShenzhenChina Guangdong Province Key Laboratory of Durability for Marine Civil Engineering School of Civil EngineeringShenzhen UniversityShenzhen 518060China

Severe plastic deformation(SPD)-induced gradient nanostructured(GNS)metallic materials exhibit superior mechanical performance,especially the high strength and good *** this study,a novel high-speed machining SPD technique,namely single point diamond turning(SPDT),was developed to produce effectively the GNS layer on the hexagonal close-packed(HCP)structural Mg *** high-resolution transmission electron microscopy observations and atomistic molecular dynamics simulations were mainly performed to atomic-scale dissect the grain refinement process and corresponding plastic deformation mechanisms of the GNS *** was found that the grain refinement process for the formation of the GNS Mg alloy layer consists of elongated coarse grains,lamellar fine grains with deformation-induced-tension twins and contraction twins,ultrafine grains,and nanograins with the grain size of~70 nm along the direction from the inner matrix to ***,experiment results and atomistic simulations reveal that these deformation twins are formed by gliding twinning partial dislocations that are dissociated from the lattice dislocations piled up at grain *** corresponding deformation mechanisms were evidenced to transit from the deformation twinning to dislocation slip when the grain size was below 2.45μ***,the Hall-Petch relationship plot and the surface equivalent stress along the gradient direction estimated by finite element analysis for the SPDT process were incorporated to quantitatively elucidate the transition of defo rmation mechanisms during the grain refinement *** findings have implications for the development of the facile SPD technique to construct high strength-ductility heterogeneous GNS metals,especially for the HCP metals.

关键词： Gradient nanostructured Mg alloy High-speed machining Deformation twinning High-resolution transition electron microscopy Hall-Petch relationship

Modeling and Validation of Indentation Depth of Abrasive Grain into Lithium Niobate Wafer by Fixed-Abrasive Lapping

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第1期34卷 97-104页

作者： Zhu Nannan Zhu Yongwei xu Jun Wang Zhankui xu sheng Zuo Dunwen College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

The prediction of indentation depth of abrasive grain in hydrophilic fixed-abrasive(FA)lapping is crucial for controlling material removal rate and surface quality of the work-piece being *** applying the theory of contact mechanics,a theoretical model of the indentation depth of abrasive grain was developed and the relationships between indentation depth and properties of contact pairs and abrasive back-off were ***,the average surface roughness(Ra)of lapped wafer was approximately calculated according to the obtained indentation *** verify the rationality of the proposed model,a series of lapping experiments on lithium niobate(LN)wafers were carried out,whose average surface roughness Ra was measured by atomic force microscope(AFM).The experimental results were coincided with the theoretical predictions,verifying the rationality of the proposed *** is concluded that the indentation depth of the fixed abrasive was primarily affected by the applied load,wafer micro hardness and pad Young′s modulus and so ***,the larger the applied load,the more significant the back-off of the abrasive *** model established in this paper is helpful to the design of FA pad and its machining parameters,and the prediction of Ra as well.

关键词： fixed-abrasive lapping indentation depth abrasive back-off lithium niobate wafer average surface roughness

Two New Furostanol Saponins from Tribulus Terrestris L.

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Chemical Research in Chinese Universities 2010年第1期26卷 46-49页

作者： xu Ya-juan xu Tun-hai XIE sheng-xu SI Yun-shan xu Dong-ming Institute of Traditional Chinese Medicine Academy of Traditional Chinese Medicine and Material Mediea of Jilin Province Changchun 130021 P. R. China Department of Traditional Chinese Medicine Chemistry School of Traditional Chinese Medicine Beijing University of Chinese Medicine Beijing 100102 P. R China Traditional Chinese Medicine College Tianjin University of Traditional Chinese Medicine Tianjin 300193 P R. China

Two new furostanol glucosides, named tribufurosides G and H, were isolated from Tribulus terrestris L. The structures of the two new furostanol glucosides were elucidated as 26-O-β-D-glucopyranosyl-（25R）-5α-furost12-one-3β,22α,26-tetraol-3-O-β-D-glucopyranosyl-（ 1→2 ）-β-D-glucopyranosyl-（ 1→4 ）-β-D-galactopyranoside（ 1 ） and 26-O-β-D-glucopyranosyl-（25S）-5 α- 12-one-2 α,3,8,22 α,26-tetraol-3 -O-β-D-glucopyranosyl-（ 1 → 2 ）-β-D-glucopyranosyl-（1→4）-β-D-galactopyranoside（2） by 1 D, 2D NMR techniques, ESI-MS analysis as well as chemical methods.

关键词： Tribulus terrestris L. Furostanol saponin Tribufurosides G and H

Brain changes detected by functional magnetic resonance imaging and spectroscopy in patients with Crohn's disease

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World Journal of Gastroenterology 2017年第20期23卷 3607-3614页

作者： Kun Lv Yi-Hong Fan Li xu Mao-sheng xu The First Clinical Medical College of Zhejiang Chinese Medical University Department of Radiology The First Affiliated Hospital of Zhejiang Chinese Medical University Department of Gastroenterology The First Affiliated Hospital of Zhejiang Chinese Medical University Department of Coloproctology The First Affiliated Hospital of Zhejiang Chinese Medical University

Crohn’s disease(CD)is a chronic,non-specific granulomatous inflammatory disorder that commonly affects the small intestine and is a phenotype of inflammatory bowel disease(IBD).CD is prone to relapse,and its incidence displays a persistent increase in developing ***,the pathogenesis of CD is poorly understood,with some studies emphasizing the link between CD and the intestinal ***,studies point to the brain-gut-enteric microbiota axis as a key player in the occurrence and development of ***,investigations have shown whitematter lesions and neurologic deficits in patients with *** on these findings,brain activity changes in CD patients have been detected by blood oxygenation level dependent functional magnetic resonance imaging(BOLD-f MRI).BOLD-f MRI functions by detecting a local increase in relative blood oxygenation that results from neurotransmitter activity and thus reflects local neuronal firing ***,biochemical concentrations of neurotransmitters or metabolites may change in corresponding brain regions of CD *** further study this phenomenon,brain changes of CD patients can be detected non-invasively,effectively and accurately by BOLD-f MRI combined with magnetic resonance spectroscopy(MRS).This approach can further shed light on the mechanisms of the occurrence and development of neurological ***,this paper reviews the current status and prospects on fMRI and MRS for evaluation of patients with CD based on the brain-gut-enteric microbiota axis.

关键词： Brain-gut-enteric microbiota axis Crohn’s disease Functional magnetic resonance spectroscopy Functional magnetic resonance imaging Gut microbiota Inflammatory bowel disease Metabolite Spectroscopy

Research progress on multiscale structural characteristics and characterization methods of iron ore sinter

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Journal of Iron and Steel Research International 2020年第4期27卷 367-379页

作者： Wei Wang xu-heng Chen Run-sheng xu Jun Li Wen-jun Shen Su-ping Wang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina Wuhan Branch of Baosteel Central Research Institute Wuhan 430083HubeiChina

At present,blast furnace ironmaking is still the main process for producing molten iron,and sinters are the main raw material for blast furnace ironmaking.A sinter with good metallurgical performance can not only ensure smooth operation of the blast furnace but also reduce the blast furnace fuel ratio and increase the molten iron *** is the most important factor affecting the metallurgical properties of the ***,the research progress of sinter pore and mineral phase structures was reviewed and the mechanism by which they influence sinter properties was *** characterization methods for the sinter and their advantages and disadvantages were introduced,and the future research direction of sinter was discussed.

关键词： Iron ore sinter Pore structure Mineral phase structure Characterization method Multiscale characterization

Obstacle avoidance in human-robot cooperative transportation with force constraint

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Science China(Information Sciences) 2023年第1期66卷 334-335页

作者： Ying ZHANG Chenguang YANG sheng xu Yongsheng OU College of Automation Science and Engineering South China University of Technology Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institutes of Advanced TechnologyChinese Academy of Sciences

Dear editor,Robots are often conceived as human-like machines that can interact with humans naturally and safely. Human-robot interaction means that robots can communicate with people,understand their needs, and act accordingly [1]. This interaction is critical when two people are needed to finish a task cooperatively.

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Changes of tear film and tear secretion after phacoemulsification in diabetic patients

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2008年第4期9卷 324-328页

作者： Xi LIU Yang-shun GU Ye-sheng xu Ophthalmology Center the First Affiliated Hospital School of Medicine Zhejiang University Hangzhou 310003 China

Objective: To evaluate tear film stability and tear secretion in patients with diabetes after phacoemulsification. Methods: Twenty-five diabetic cataract patients and 20 age-matched non-diabetic cataract patients as control underwent pha- coemulsification. Tear film break-up time (TFBUT), Schirmer I test (SIT), corneal fluorescein staining, and dry eye symptoms were measured pre- and postoperatively. Results: Diabetics had a decreased preoperative TFBUT and SIT. TFBUT was reduced on Day 1 and recovered on Day 180 postoperatively in both groups. SIT was increased after phacoemulsification, but returned to preoperative levels by Day 180 in non-diabetics, whereas it was lower than preoperative level in diabetics. Positive corneal fluo- rescein staining was elevated in both groups, and returned to preoperative levels only in controls. Dry eye symptoms were similar to fluorescein staining in both groups. Conclusion: Tear secretion was reduced in diabetic cataract patients after phacoe- mulsification, which worsened dry eye symptoms and predisposed those patients to ocular damage.

关键词： Phacoemulsification Diabetes Cataract Tear

Uniform Rice-like CdS Particles Prepared from Water-in-oil Microemulsions

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Chemical Research in Chinese Universities 2006年第1期22卷 11-13页

作者： ZHOU Hai-cheng xu sheng PENG Qing LI Ya-dong The Key Laboratory of Atomic ＆ Molecular Nanosciences of the Ministry of Education Department of ChemistryTsinghua UniversityBeijing100084P.R.China Department of Chemistry and Engineering Shandong University of Technology Zibo 255000 P. R. China

Uniform rice-like CdS particles were synthesized in cyclohexane/Triton X-100/n-pentanol/water quaternary microemulsions. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscopy, and electron diffraction. The results indicate that the size and the shape of the rice-like CdS particles can be influenced by the molar ratio of water to the surfactant（w value） and the reactant concentrations.

关键词： W/O microemulsion Rice-like CdS nanoparticle Value of w Morphology

Adaptive Algorithms of Nonlinear Approximation with Finite Terms

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Acta Mathematica Sinica,English Series 2007年第9期23卷 1663-1672页

作者： Wen Bin WEI Yue sheng xu Pei Xin YE Department 4 Air Force Radar Academy Wuhan 430019 P. R. China Institute of Mathematics Chinese Academy of Sciences Beijing 100080 P. R. China Department of Mathematics Nankai University Tianjin 300000 P. R. China

This paper deals with realizable adaptive algorithms of the nonlinear approximation with finite terms based on wavelets. We present a concrete algorithm by which we may find the required index set Am for the greedy algorithm Gm^P（., Ψ）. This makes the greedy algorithm realize the near best approximation in practice. Moreover, we study the efficiency of the finite-term approximation of another Mgorithm introduced by Birge and Massart.

关键词： nonlinear approximation dictionary Haar system adaptive algorithm near best approximation