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Journal of Materials Science & Technology 2021年第18期77卷 38-46页

作者： y.Chew z.G.zhu f.Weng S.B.Gao f.L.ng B.y Lee G.J.Bi Singapore institute of Manufacturing Technology 73 Nanyang Drive637662Singapore School of Mechanical Aerospace Engineering Nanyang Technological University50 N any ang Avenue639798Singapore

Laser aided additive manufacturing(LAAM)was used to fabricate bulk fe_(49.5)Mn_(30)Co_(10)Cr_(10)C_(0.5)interstitial multicomponent alloy using pre-alloyed *** room temperature yield strength(σ_y),ultimate tensile strength(σ_(UTS))and elongation(ε_(UTS))were 645 MPa,917 MPa and 27.0%*** asbuilt sample consisted of equiaxed and dendritic cellular structures formed by elemental *** cellular structures together with oxide particle inclusions were deemed to strengthen the *** other contributing components include dislocation strengthening,friction stress and grain boundary *** highε_(UTS)was attributed to dislocation motion and activation of both twinning and transformation-induced plasticity(TWiP and TRiP).Tensile tests performed at-40℃and-130℃demonstrated superior tensile strength of 1041 MPa and 1267 MPa ***,almost no twinning was observed in the fractured sample tested at-40℃and-130℃.instead,higher fraction of strain-induced hexagonal close-packed(HCP)εphase transformation of 21.2%were observed for fractured sample tested at-40℃,compared with 6.3%in fractured room temperature sample.

关键词： Multicomponent alloys Laser aided additive manufacturing Additive manufacturing Microstructure Mechanical property

公元241~1912年中国河西走廊地区年际干湿变化与游牧战争的关系

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中国科学：地球科学 2024年第6期54卷 1950-1959页

作者：唐飞史志林田沁花杜小刚张永中国科学院地理科学与资源研究所陆地表层格局与模拟院重点实验室北京100101 兰州大学敦煌学研究所兰州730020 中国气象局国家气候中心北京100081 甘肃祁连山国家级自然保护区管护中心隆畅河自然保护站张掖734400 中国科学院大学北京100049

长期以来,气候与战争之间的关系一直是一个备受关注的科学和社会问题.在本研究中,探讨了公元241年以来中国河西走廊地区气候与战争爆发的可能关联.基于河西走廊地区树轮资料以及历史时期游牧战争数据,利用时序叠加分析方法,我们发现河... 详细信息

长期以来,气候与战争之间的关系一直是一个备受关注的科学和社会问题.在本研究中,探讨了公元241年以来中国河西走廊地区气候与战争爆发的可能关联.基于河西走廊地区树轮资料以及历史时期游牧战争数据,利用时序叠加分析方法,我们发现河西走廊地区年际干湿变化与游牧民族发动的战争之间存在明显的相关性,但是这种关系是动态的,并与该地区的政权格局有关.在河西走廊存在多个地方政权统治的时期,战争往往随着干旱的气候条件而发生,这可能是由于这些时期的异常干旱加剧了对资源和土地的争夺.相反,在统一王朝管理时期,气候湿润时更容易发生战争,因为牧场的扩大和资源的积累有助于游牧民族的对外征服.这些发现凸显了战争与气候变化之间关系的复杂性.为了更加全面地分析二者之间的关系,需要在更多地区建立覆盖范围更广、分布更均匀且连续的高分辨率历史温湿数据集.此外,对于具有独特特征的区域,需要收集更多的历史战争数据,进行分类讨论研究.

关键词：干旱年际干湿变化战争河西走廊树轮游牧民族

Effects of friction stir processing and nano-hydroxyapatite on the microstructure,hardness,degradation rate and in-vitro bioactivity of WE43 alloy for biomedical applications

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Journal of Magnesium and Alloys 2024年第1期12卷 209-224页

作者： Bo Wu farazila yusof fuguo Li Huan Miao A.R.Bushroa Mohd Ridha Bin Muhamad irfan Anjum Badruddin Mahmoud z.ibrahim Department of Mechanical Engineering Faculty of EngineeringUniversiti MalayaKuala Lumpur 50603Malaysia Centre of Advanced Manufacturing and Material Processing(AMMP Centre) Universiti MalayaKuala Lumpur 50603Malaysia Center of foundation studies in Science Universiti MalayaKuala Lumpur 50603Malaysia State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Mechanical Engineering Department College of EngineeringKing Khalid UniversityAbha 61421Saudi Arabia Design and Production Engineering Faculty of EngineeringAin Shams UniversityCairo 11517Egypt

nowadays,magnesium alloys are emerging in biomedical implants for their similar properties to natural ***,the rapid degradation of magnesium alloys in biological media hinders successful *** of microstructure,as well as reinforcement particles can significantly improve the degradation *** this work,multi-pass friction stir processing(fSP)was proposed to synthesize WE43/nano-hydroxyapatite(n HA)surface composite,the microstructure,reinforced particle distribution,micro-hardness,corrosion behavior and in-vitro bioactivity were *** subsequent fSP passes of WE43 alloy and WE43/n HA composite refined the grain size which was reduced by 94.29%and 95.92%(2.63 and 1.88μm,respectively)compared to base metal after three *** resulted in increasing the microhardness by 120%(90.86 HV0.1)and 135%(105.59 HV0.1)for the WE43 and WE43-n HA,*** is found that increasing fSP passes improved the uniform distribution of n HA particles within the composite matrix which led to improved corrosion resistance and less degradation *** corrosion rate of the fSPed WE43/n HA composite after three passes was reduced by 38.2%(4.13 mm/year)and the degradation rate was reduced by 69.7%(2.87 mm/y).This is attributed to secondary phase(Mg24y5and Mg41nd5)particle fragmentation and redistribution,as well as a homogeneous distribution of n ***,the growing Ca-P and Mg(OH)2layer formed on the surface represented a protective layer that reduced the degradation *** wettability test revealed a relatively hydrophilic surface with water contact angle of 49.1±2.2°compared to 71.2±2.1°for base ***,biomineralization test showed that apatite layer grew after immersion 7d in simulated body fluid with atomic ratio of Ca/P 1.60 approaching the stoichiometric ratio(1.67)indicating superior bioactivity of fSPed WE43/n HA composite after three *** results raise that the grain refinement by fSP and introduction of n HA partic

关键词： friction stir processing Magnesium-based composite nano-hydroxyapatite Corrosion behavior in-vitro bioactivity

Synthesis,Crystal Structure and Conformational Analysis of (E)-5-Methoxy-2-((4-methoxyphenylimino)methyl)phenol

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Chinese Journal of Structural Chemistry 2010年第3期29卷 359-364页

作者： ■AHn Onura ByKGngR Orhana ALBAyRAK i■demb ODABA■O■LU Mustafac Department of Physics Faculty of Arts and SciencesOndokuz Mayis University Department of Science Education Sinop University Chemistry Programme Pamukkale University

The title compound,（E）-5-methoxy-2-（（4-methoxyphenylimino）methyl）phenol（C15H15nO3）,crystallizes in monoclinic,space group P21/c with a=9.4361（6）,b=10.6212（5）,c=12.9338（9）,β=93.064（5）o,V=1294.41（14）3,z=4,Dc=1.320 g/cm3,f（000）=544,Rint=0.116,T=296 K,μ=0.09 mm-1,the final R=0.051 and wR=0.148 for 1836 observed reflections with i2σ（i）.An extensive two-dimensional network of C–H…O hydrogen bonds and π-ring interactions are responsible for the crystal *** hydrogen bonds and C–H…π interactions produce R22（14）,R44（30） and R44（31） *** addition to the molecular geometry from X-ray experiment,the molecular geometry of the title compound in the ground state has been calculated using the semi-empirical（AM1 and PM3） and density functional theory method（DfT）（B3LyP） with 6-31G（d） basis *** determine the conformational flexibility,molecular energy profile of the title compound was obtained by semi-empirical（PM3 and AM1） and DfT/B3LyP calculations with respect to the selected degree of torsional freedom,which varied from –180° to ＋180° in a step of 10°.

关键词： crystal structure Schiff base PM3 AM1 DfT conformational analysis

Ground state energy of excitons in quantum dot treated variationally via Hylleraas-like wavefunction

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Chinese Physics B 2009年第4期18卷 1578-1585页

作者： S. Sakiroglu . Dogan A. yιldιz K. Akgngr H. Epik y. Ergn H. Sarι . Skmen Physics Department Dokuz Eyll University Physics Department Anadolu University Physics Department Cumhuriyet University

in this work, the effects of quantum confinement on the ground state energy of a correlated electron-hole pair in a spherical and in a disc-like quantum dot have been investigated as a function of quantum dot size. Under parabolic confinement potential and within effective mass approximation Ritz＇s variational method is applied to Hylleraas-like trial wavefunction. An efficient method for reducing the main effort of the calculation of terms like τekh exp （-λτeh） is introduced. The main contribution of the present work is the introduction of integral transforms which provide the calculation of expectation value of energy and the related matrix elements to be done analytically over single-particle coordinates instead of Hvlleraas coordinates.

关键词： exciton parabolic confinement variational method Hylleraas coordinates

fourier transform technique in variational treatment of two-electron parabolic quantum dot

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Chinese Physics B 2009年第8期18卷 3508-3516页

作者： S.Sakiroglu A.yιldιz .Dogan K.Akgngr H.Epik y.Ergn H.Sarι .Skmen Physics Department Dokuz Eyll University Physics Department Anadolu University Physics Department Cumhuriyet University

in this work, we propose an efficient method of reducing the computational effort of variational calculation with a Hylleraas-like trial wavefunction. The method consists of introducing integral transforms for the terms as r12^κ exp （-λτ12） which provide the calculation of the expectation value of energy and the relevant matrix elements to be done analytically over single-electron coordinates instead of Hylleraas coordinates. We have used this method to calculate the ground state energy of a two-electron system in a spherical dot and a disk-like quantum dot separately. Under parabolic confinement potential and within effective mass approximation size and shape effects of quantum dots on the ground state energy of two electrons have been investigated. The calculation shows that our results even with a small number of basis states are in good agreement with previous theoretical results.

关键词： two-electron quantum dot parabolic confinement variational method Hylleraas coor- dinates

Photovoltaic enhancement of Si solar cells by assembled carbon nanotubes

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nano-Micro Letters 2010年第1期2卷 22-25页

作者： y.f.zhang y.f.Wang n.Chen y.y.Wang y.z.zhang z.H.zhou L.M.Wei Key laboratory for Thin film and Microfabrication of the Ministry of Education National Key Laboratory of Nano/Micro Fabrication Technology Research Institute of Micro/Nano Science and Technology Shanghai Jiao Tong University

Photovoltaic conversion was enhanced by directly assemble of a network of single-walled carbon nanotubes(SWnTs) onto the surface of n-p junction silicon solar cells. When the density of SWnTs increased from 50 to 400 tubes μm^(-2), an enhancement of 3.92% in energy conversion efficiency was typically obtained. The effect of the SWnTs network is proposed for trapping incident photons and assisting electronic transportation at the interface of silicon solar cells.

关键词： Solar cell Carbon nanotube Photovoltaic enhancement Heterojunction

High-Speed friction Stir Welding of T6-Treated B4Cp/6061Al Composite

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 67-74页

作者： y.z.Li y.n.zan Q.z.Wang B.L.Xiao z.y.Ma Key Laboratory of nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China Sheny.ng national Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China University of Science and Technology of China Shenyang 110016China

T6-treated 20 wt% B4 Cp/6061 Al sheets were joined under welding speeds of 400–1200 mm/min by friction stir welding(fSW) with a threaded cermet pin. The macro-defect-free fSW joints could be achieved at high welding speeds up to 1200 mm/min, but larger plunge depth was required at the welding speeds of 800 and 1200 mm/min to eliminate the tunnel defect. in the nugget zone(nz) of the joints, the B4 C particles were broken up and uniformly redistributed. The nz exhibited lower hardness than the base metal(BM), and the hardness value almost did not change with increasing welding speed, attributable to the dissolution of precipitates. Compared with the BM, the joints showed lower tensile strength. As the welding speed increased from 400 to 800 mm/min, the joint efficiencies were nearly the same and up to ~ 73%. When the welding speed increased up to 1200 mm/min, the tensile strength significantly decreased, due to the occurrence of kissing bond defect at the bottom of the nz. With increasing welding speed, the fracture location of the joints transferred gradually from the heat-affected zone to the nz due to the kissing bond defects.

关键词： Metal-matrix composites Microstructures Mechanical properties friction stir welding High-speed welding

Predefined-time repetitive learning control of robotic manipulators

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Kongz.i yu Juece/Control and Decision 2024年第11期39卷 3719-3726页

作者： Li y.-Q. Chen Q. Shi H.-H. zhang z.-H. Chen P. College of information Engineering Zhejiang University of Technology Hangzhou 310023 China

A backstepping-based predefined-time repetitive learning control scheme is proposed for uncertain robot manipulators to achieve rapid and high-precision tracking control performance. A non-singular predefined-time virtual controller is constructed to effectively avoid the singularity issues caused by the differentiation of the virtual controller in conventional finite-time backstepping design. it ensures that the tracking error of the robot manipulators joint positions converges to a neighborhood of the origin within the predefined time. Then, the lumped uncertainty of the manipulator is separated into periodic and non-periodic parts by considering the periodic characteristics of the desired trajectory. A fully saturated repetitive learning law is constructed to accurately estimate and compensate for the periodic uncertainty. Meanwhile, a robust control law is developed and the terminal attracting technique is applied to guarantee the effective compensation of the non-periodic uncertainty including external disturbances, such that the high-precision tracking of the robot manipulators joint positions is achieved. finally, the stability of the closed-loop system and the error convergence performance of the proposed scheme are analyzed through the Lyapunov stability synthesis. The effectiveness of the proposed control method is verified by comparative simulations. © 2024 northeast University. All rights reserved.

关键词： backstepping recursive algorithm periodic uncertainty predefined-time control repetitive learning law robot manipulator tracking control

Electrical stimulation with polypyrrole-coated polycaprolactone/silk fibroin scaffold promotes sacral nerve regeneration by modulating macrophage polarisation

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Biomaterials Translational 2024年第2期5卷 157-174页

作者： Cheng H. Bai J. zhou X. Chen n. Jiang Q. Ren z. Li X. Su T. Liang L. Jiang W. Wang y. Peng J. Shang A. School of Medicine Nankai University Tianjin China Department of neurosurgery Chinese PLA General Hospital Beijing China institute of Orthopedics Chinese PLA General Hospital Beijing Key Lab of Regenerative Medicine in Orthopedics Key Laboratory of Musculoskeletal Trauma and War Injuries PLA Beijing China Co-innovation Center of neuroregeneration Nantong University Jiangsu Province Nantong China Graduate School of Chinese PLA General Hospital Beijing China Department of Ultrasound Chinese PLA General Hospital Beijing China

Peripheral nerve injury poses a great threat to neurosurgery and limits the regenerative potential of sacral nerves in the neurogenic bladder. it remains unknown whether electrical stimulation can facilitate sacral nerve regeneration in addition to modulate bladder function. The objective of this study was to utilise electrical stimulation in sacra nerve crush injury with newly constructed electroconductive scaffold and explore the role of macrophages in electrical stimulation with crushed nerves. As a result, we generated a polypyrrole-coated polycaprolactone/silk fibroin scaffold through which we applied electrical stimulation. The electrical stimulation boosted nerve regeneration and polarised the macrophages towards the M2 phenotype. An in vitro test using bone marrow derived macrophages revealed that the pro-regenerative polarisation of M2 were significantly enhanced by electrical stimulation. Bioinformatics analysis showed that the expression of signal transducer and activator of transcriptions (STATs) was differentially regulated in a way that promoted M2-related genes expression. Our work indicated the feasibility of electricals stimulation used for sacral nerve regeneration and provided a firm demonstration of a pivotal role which macrophages played in electrical stimulation. © 2024, Chinese Medical Multimedia Press Co Ltd. All rights reserved.

关键词： electrical stimulation JAK-STAT signalling pathway macrophage polarisation peripheral nerve regeneration polypyrrole sacral nerve injury