检索结果-南通市图书馆

Mechanochemical effect on the microstructure and mechanical properties in ultraprecision machining of AA6061 alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第10期69卷 228-238页

作者： Jiayi Zhang yan jin lee Hao Wang Department of Mechanical Engineering Faculty of EngineeringNational University of Singapore9 Engineering Drive 1Singapore 117575Singapore

The mechanochemical effect on the microcutting of AA6061 alloy is studied through characterization on the microgroove *** is a reduction in cutting and thrust forces with the application of ink during ***,the microhardness of the ink-affected microgroove is lower than that of the ink-free *** substructured grains exist in the ink-affected microgroove zone whilst deformed grains dominate in the ink-free microgroove zone produced by ***,the mechanochemical effect can facilitate the nucleation of precipitates in the microgroove zone and induce the formation of subgrains with multiple *** to the analysis and calculation,the main texture components of the ink-affected sample are Goss{110}and R{124},and that of the ink-free sample are Brass{110},Copper{112}and S{123}.Besides,a clear difference of slip systems is found between the ink-free and ink-affected microgrooves,and the results show that R texture is easier to form on the ink-affected microgroove.

关键词： Mechanochemical effect Microhardness Texture Nucleation Microcutting

Effect of a weak magnetic field on ductile-brittle transition in micro-cutting of single-crystal calcium fluoride

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第17期112卷 96-113页

作者： Yunfa Guo yan jin lee Yu Zhang Anastassia Sorkin Sergei Manzhos Hao Wang Department of Mechanical Engineering National University of Singapore9 Engineering Drive 1Singapore 117575Singapore School of Materials and Chemical Technology Tokyo Institute of TechnologyOokayama 2-12-1Meguro-kuTokyo 152-8552Japan

Magneto-plasticity occurs when a weak magnetic field alters material plasticity and offers a viable solution to enhance ductile-mode cutting of brittle *** study demonstrates the susceptibility of non-magnetic single-crystal calcium fluoride(CaF_(2))to the magneto-plastic *** influence of magneto-plasticity on CaF_(2) was confirmed in micro-deformation tests under a weak magnetic field of 20 *** surface pile-up effect was weakened by 10-15 nm along with an enlarged plastic zone and suppressed crack propagation under the influence of the magnetic ***-cutting tests along different crystal orientations on the(111)plane of CaF_(2) revealed an increase in the ductile-brittle transition of the machined surface with the aid of magneto-plasticity where the largest increase in ductile-brittle transition occurred along the[112]orientation from 512 nm to a range of 664-806 ***,the subsurface damage layer was concurrently thinner under magnetic *** anisotropic influence of the magnetic field relative to the single-crystal orientation and the cutting direction was also *** analytical model was derived to determine an orientation factor M that successfully describes the anisotropy while considering the single-crystal dislocation behaviour,material fracture toughness,and the orientation of the magnetic *** suggested theoretical mechanism of magneto-plasticity via formation of non-singlet electronic states in defected configurations was confirmed with density functional theory *** successful findings on the influence of a weak magnetic field on plasticity present an opportunity for the adoption of magnetic-assisted micro-cutting of non-magnetic materials.

关键词： Magneto-plasticity Weak magnetic field Brittle material Ductile-brittle transition Micro-cutting

Magneto-plasticity in micro-cutting of single-crystal copper

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第29期124卷 121-134页

作者： Yunfa Guo yanjin lee Yu Zhang Hao Wang Department of Mechanical Engineering National University of Singapore9 Engineering Drive 1Singapore 117575Singapore

The plasticity of metals can be significantly affected by the application of a magnetic field,otherwise known as the magneto-plastic *** paper investigates the magneto-plastic effect in the microcutting of a non-magnetic ductile material,single-crystal copper,under a weak magnetic field and reports the influence of the phenomenon on the cutting forces and machined surface quality.A softening effect was observed from the large reduction in cutting forces from 3.2 N to 1.5 N under the magnetic *** compared to the magnetic field intensity and polarity,the variation in magnetic field orientations with respect to the cutting direction exhibited a stronger influence on the cutting force,chip morphology,machined surface texture,subsurface microstructure,surface roughness,and machined surface microhardness of the copper *** analytical model was developed based on the geometry of the cutting chips to correlate the orientation-dependent influence of the magnetic field on the cutting *** the surface quality,excessive folds with four different types of morphology produced under magnetic-free cutting were suppressed after applying the magnetic field with the most significant improvement achieved with the 90°magnetic field *** magnetic-assisted changes in machined surface morphology also led to the reduction in machined surface roughness and *** optimistic micro-cutting outcomes in this work establish a greater understanding of the magneto-plastic effect and demonstrate the applicability of magneto-plasticity in ultraprecision manufacturing.

关键词： Micro-cutting Magnetic field Plasticity Mechanical response Anisotropy

Twist monomials of binary delta-matroids

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2025年

作者： Qi yan Xian'an jin School of Mathematics and Statistics Lanzhou University School of Mathematical Sciences Xiamen University

Recently, we introduced the twist polynomials of delta-matroids and gave a characterization of even normal binary delta-matroids whose twist polynomials have only one term and posed a problem:what would happen for odd binary delta-matroids? In this paper, we show that a normal binary deltamatroid whose twist polynomials have only one term if and only if each connected component of the intersection graph of the delta-matroid is either a complete graph of odd order or a single vertex with a loop.

关键词：

Trinuclear gold-catalyzed site-selective alkylation of peptides

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 249-256页

作者： Qing-Yun Fang Chengyihan Gu Yinghan Chen Wencheng yan Yong Liang Weipeng Li Chengjian Zhu Jie Han jin Xie State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (Chem BIC) School of Chemistry and Chemical Engineering Nanjing University Green Catalysis Center College of Chemistry Zhengzhou University State Key Laboratory of Natural Medicines China Pharmaceutical University

Selective modification of peptides has always been a challenging issue. The selective alkylation of peptides can alter the biological activity and physical properties of molecules, and it has gained significant research interest. We herein disclose an intriguing gold-catalyzed alkylation of peptides using bench-stable unactivated alkyl bromides under photoredox catalysis. A wide range of structurally diverse primary, secondary and tertiary alkyl bromides serve as effective coupling partners to precisely connect with the α-C(sp3)–H in glycine residue of peptides. This protocol demonstrates an exceptionally broad scope for alkyl halides and excellent tolerance for a wide range of useful functional groups. A series of relay transformations to construct cyclic peptides, to proceed click reaction and to realize peptide fluorescence labeling further enhance its synthetic practicality. In addition, mechanistic studies and density functional theory(DFT) calculations reveal an inner-sphere and subsequent outersphere single electron transfer(SET) mechanism.

关键词： gold catalysis peptide alkylation C-C coupling radical

同方期刊数据库

Bending Stiffness of Concrete-Filled Steel Tube and Its Influence on Concrete Placement Timing of Composite Beam-String Structure

在线全文

学校读者我要写书评

暂无评论

Structural Durability & Health Monitoring 2025年第1期19卷 55-75页

作者： Zhenyu Zhang Quan jin Haitao Zhang Zhao Liu Yuyang Wu Longfei Zhang Renzhang yan CCCC Third Highway Engineering Co. Ltd.Beijing101300China School of Civil Engineering Chongqing Jiaotong UniversityChongqing400074China

When the upper chord beam of the beam-string structure(BSS)is made of concrete-filled steel tube(CFST),its overall stiffness will change greatly with the construction of concrete placement,which will have an impact on the design of the tensioning plans and selection of control measures for the *** order to accurately obtain the bending stiffness of CFST beam and clarify its impact on the mechanical properties of composite BSS during construction,the influence of some factors such as height-width ratio,wall thickness of steel tube,elasticity modulus of concrete,and friction coefficient on the bending stiffness are analyzed parametrically by the numerical simulation technology based on an actual *** calculation formula of the equivalent bending stiffness of CFST is also established through mathematical statistical ***,the equivalent bending stiffness is introduced into the construction and use stages of the composite BSS,respectively,and the mechanical properties such as prestress-tensioning control value,structural deformation,and internal force of key members are comparatively analyzed when adopting two different construction ***,the optimal construction plan of concrete placement first and then prestress-tensioning is proposed.

关键词： Concrete panels freeze-thaw damage compression-shear crack tension-shear crack

Potassium ions and cyano group modified g-C3N4 for effective generation of H2O2 through two-electron oxygen reduction

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 192-200页

作者： Dongying Wang Shulan Pu Yongmin Chen Ke Lei Yujie Duan Linjiao Mao Xuhui Zeng Xi Luo Yuntao Zhang Yuqin Dong jin Zhong Zhang yan Sun School of Mechanical Engineering Chengdu University Department of Chemistry and Biochemistry University of California

Potassium ions （K+） doped graphitic carbon nitride （g-C3N4） was prepared by a thermal etching method using potassium hydroxide （KOH） as an ion *** transform infrared spectroscopy （FTIR） and X-ray photoelectron spectroscopy （XPS）results showed that the generation of the cyano group was detected while introducing K+.Under simulated sunlight irradiation,the sample with a K+doping amount of 10%showed the highest hydrogen peroxide （H2O2） generation rate of2,140.2μmol *** apparent quantum yield （AQY） at 400 nm and the solar-to-chemical conversion （SCC） are 4.35%and1.23%,respectively.K+acted as a bridge between g-C3N4layers,which enhanced charge transfer ***,the cyano group enhanced the adsorption capacity of protons （H+） and promoted the yield of *** catalyst exhibited excellent photocatalytic stability based on four-cycle *** addition,a mechanism study showed that superoxide radicals （·O2-）were the most important active species in the reaction *** production of H2O2was achieved through consecutive single-electron *** study deepens the understanding of the oxygen reduction reaction process and opens up a new venue for improving H2O2generation.

关键词： photocatalysis hydrogen peroxide oxygen reduction reaction potassium doping cyano group

Broadband low-frequency sound absorption of multifunctional composite metastructure

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Technological Sciences 2025年

作者： Yilong yanG Shanshan LIU yan LI Tong GAO Yongdong PAN Yong LI Yabin jin School of Aerospace Engineering and Applied Mechanics Tongji University Institute of Acoustics School of Physics Science and Engineering Tongji University Shanghai Institute of Aircraft Mechanics and Control State International Joint Research Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical University Shanghai Key Laboratory of Intelligent Sensing and Detection Technology School of Mechanical and Power Engineering East China University of Science and Technology

In this study, we fabricated multifunctional metastructures from carbon fiber-reinforced plastic composites using additive manufacturing technology. These metastructures are characterized by their lightweight, load-bearing capacity, and broadband low-frequency sound absorption properties. The metastructure consists of 36 unit cells, and non-local coupling mechanism was considered for designing the sound absorption performance. We developed an acoustic impedance theory tailored for the metastructure, facilitating an analysis of thermal and viscous dissipation mechanisms. It is proven theoretically and experimentally that the proposed composite metastructure can achieve a noise reduction with an average sound absorption coefficient greater than 0.9 across frequencies in the rage of 330–1500 Hz. We also studied the metastructure’s quasi-static and cyclic compression performance, confirming its efficient absorption capabilities after cyclic compression. The proposed design and additive manufacturing method for composite metastructures provides a novel pathway for creating lightweight, multifunctional structures with diverse applications, such as aerospace engineering.

关键词：

Recent progress on photoactive nonprecious transition-metal complexes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 46-95页

作者： Zhong-Liang Gong Hong-Jie Zhang yan Cheng Jianxun Liu Yuhan Ai Yaqin Li Zhihui Feng Qiong Zhang Shaolong Gong Yong Chen Chang-Jiang Yao Yuan-Yuan Zhu Liang-jin Xu Yu-Wu Zhong CAS Key Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences State Key Laboratory of Structural Cemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences School of Chemistry and Chemical Engineering Anhui Key Laboratory of Advanced Catalytic Materials and Reaction EngineeringHefei University of Technology State Key Laboratory of Explosion Science and Safety Protection School of Mechatronical Engineering Beijing Institute of Technology College of Chemistry and Molecular Sciences Hubei Key Lab on Organic and Polymeric Optoelectronic Materials Wuhan University School of Chemistry and Chemical Engineering Anhui University Key Laboratory of Photochemical Conversion and Optoelectronic Materials & CAS-HKU Joint Laboratory on New Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Photoactive complexes of nonprecious transition metals, mainly including those in the first-row and partially the second-row of the Periodic table of elements, have received increasing attention in view of their low cost and long-term sustainability. They are recognized as promising alternatives to noble transition metal complex congeners that have been extensively studied in optoelectronic devices, artificial photosynthesis, photocatalysis, biodiagnostics, and therapeutics, etc. This review is devoted to a comprehensive summary on the classical and recent advances on photoactive nonprecious transition metal complexes, including photoactive Zr, V, Cr, Mo, and W complexes, Mn complexes and hybrids, Fe, Co, Ni, and Cu complexes, and Zn and Cd complexes and hybrids. A particular focus is given on the molecular design, modulation of photophysical and photochemical properties, and applications of the representative and lately-developed nonprecious metal complexes. In addition, a perspective on the future development in this field is provided at the end of this review.

关键词： photoactive metal complexes earth-abundant metals nonprecious metal complexes luminescence photochemistry