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The Portevin-Le Chatelier effect of gradient nanostructured 5182 aluminum alloy by surface mechanical attrition treatment

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Journal of materials science & Technology 2018年第12期34卷 2307-2315页

作者： Xiangchen Meng Bei Liu Lan Luo Yan Ding Xi-Xin Rao Bin Hu Yong Liu Jian Lu Key Laboratory of Lightweight and High Strength Structural Materials of Jiangxi Province Nanchang University School of Materials Science & Engineering Nanchang University China Science Lab. General Motors Research & Development Department of Mechanical and Biomedical Engineering City University of Hong Kong Centre for Advanced Structural Materials City University of Hong KongShenzhen Research Institute

Nanocrystalline surface layers and gradient nanostructure in 5182 aluminum alloy have been produced through surface mechanical attrition treatment(SMAT). The results indicate that the gradient nanostructure can not only improve the mechanical properties of 5182 Al alloy, but also has a certain effect on the Portevin-Le Chatelier(PLC) effect. The yield and ultimate tensile strength of 5182 Al alloy with SMAT are significantly improved combining with the decrease of fracture elongation compared with the as-received one. The PLC effect of 5182 Al alloy could be effectively postponed by the formation of gradient nanostructure after SMAT. It leads to the increase of critical strain of the PLC effect, more concentrated distribution of serrated strain, and increase of average stress amplitude in special strain range. The influence of grain size and gradient nanostructure on the PLC effect of 5182 Al alloy was also discussed in detail. Grain refinement could sharply increase the density of dislocations and hinder the movement of dislocations, which results in the decrease of moving speed of dislocations and the more concentrated distribution of solute atoms. The solute atoms would aggregate to form nano precipitates and further impede movement of dislocation. The stronger interaction between the dislocations and the nano precipitates is the main mechanism of postponed PLC effect.

关键词： Aluminum alloy Portevin-Le Chatelier effect Serrated yielding Surface mechanical attrition treatment Gradient nanostructure

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Evaluation of T-72 tank driver seat based on anthropometric dimensions of Ethiopian military tank drivers

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AIP Conference Proceedings 2022年第1期2648卷

作者： Aliyi Umer Dereje Engida G. M. Sayeed Ahmed U. Pranavi 1College of Engineering Defence University Bishoftu Ethiopia 2Addis Ababa Science and Technology University Addis Ababa Ethiopia 3Program of Mechanical Design and Manufacturing Engineering School of Mechanical Chemical and Materials Engineering (SoMCME) ASTU ADAMA Ethiopia.P.O.Box:1888 4Center of Excellence for Advanced Manufacturing Engineering Program of Mechanical Design Ethiopia.P.O.Box:1888 5Department of Mechanical Engineering Vardhaman College of Engineering Hyderabad-501218 India

In the world it is difficult to design in terms of average dimension. For this reason anthropometric plays a great rule in the world in design of products. In Ethiopia T-72 tanks are the most important weapons that give a strong support to the ground force in the battle field. So the question of the correct ergonomically design and analysis of the driver seat especially in terms of comfort is mandatory so due to this fact, study anthropometric of driver's seat is very important. It is necessary to define the drivers’ space and seat dimensions by considering the size of the average people according to their body dimensions. The basic questions for this research are (i) To what extent the soviet fabricated tank driver's seat is comfortable to Ethiopia army, (ii) Is there significant different between the body size dimension of soviet and Ethiopian army, and (iii) The Ethiopian military derivers have awareness of the comfort. The main goal of this paper is to conduct descriptive survey on an ergonomics assessment of driver's seat of T72 tank. Following sitting height, popliteal height, sitting to shoulder height, shoulder breadth, buttocks to popliteal length, and hip breadth seated anthropometric dimensions were measured of 45 subjects / respondents (35 males, 10 females) randomly selected from the field study. Mean, standard deviation, and T-test were calculated based on anthropometric data of subjects. Results revealed suggest a mismatch among the dimensions of current T-72 Russian fabricated tank motive force seat and the anthropometric dimensions of military staffs. This recommends that anthropometric information of the Ethiopian army tank drivers changed into not working in the design and manufacturing of the seats. This research is may be cautioned that tank driving force seat of T-72 tank and tank drivers anthropometric measurements are at variance. Therefore, the paper presents anthropometric statistics that may be utilized by the Russian manufacturers of tank

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Erratum to “Ros-responsive nanocomposite scaffolds for sustained releasing puerarin to achieve chondroprotection in OA rats” [Mater. Des. 233 (2023) 112214]

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materials & Design 2024年 244卷

作者： Depeng Fang Zainen Qin Li Zheng Pek Yin Michelle Yew Xianfang Jiang Dan Kai Fangming Song Jinmin Zhao Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration The First Affiliated Hospital of Guangxi Medical University Guangxi Medical University Nanning 530021 China Guangxi Key Laboratory of Regenerative Medicine Guangxi Collaborative Innovation Center of Regenerative Medicine and Medical Bioresource Development and Application The First Affiliated Hospital of Guangxi Medical University Nanning 530021 China Department of Biomedical Engineering Faculty of Engineering National University of Singapore Singapore 117583 Singapore Institute of Materials Research and Engineering Agency for Science Technology and Research (A*STAR) 2 Fusionopolis Way Innovis #08-03 138634 Singapore Guangxi Key Laboratory of Oral and Maxillofacial Rehabilitation and Reconstruction College of Stomatology Hospital of Stomatology Guangxi Medical University Nanning 530021 China Institute of Sustainability for Chemicals Energy and Environment (ISCE2) Agency for Science Technology and Research (A*STAR) 2 Fusionopolis Way Innovis #08-03 138634 Singapore Department of Orthopedics Trauma and Hand Surgery The First Affiliated Hospital of Guangxi Medical University Guangxi Medical University Nanning 530021 China

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Front Cover: Emergence of Non-photoresponsive Catalytic Techniques for Environmental Remediation and Energy Generation (Chem. Asian J. 9/2023)

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Chemistry – An Asian Journal 2023年第9期18卷

作者： Manish Kumar Sharma Dr. Imran Khan Kuldeep Kaswan Dr. Snigdha Roy Barman Prof. Dr. Subhajit Saha Wu-Chiao Hsieh Prof. Dr. Yu-Lun Chueh Prof. Dr. Yu-Lin Wang Prof. Dr. Sangmin Lee Prof. Dr. Dukhyun Choi Prof. Dr. Zong-Hong Lin Department of Materials Science and Engineering National Tsing Hua University Hsinchu 30013 Taiwan Institute of NanoEngineering and Microsystems National Tsing Hua University Hsinchu 30013 Taiwan International Intercollegiate PhD Program National Tsing Hua University Hsinchu 30013 Taiwan Department of Renewable Energy Maulana Abul Kalam Azad University of Technology West Bengal 741249 India Department of Obstetrics and Gynecology Chang Gung Memorial Hospital and College of Medicine Chang Gung University Taoyuan 333 Taiwan Frontier Research Center on Fundamental and Applied Sciences of Matters National Tsing Hua University Hsinchu 30013 Taiwan School of Mechanical Engineering Chung-Ang University Seoul 06974 South Korea Department of Mechanical Engineering Sungkyunkwan University Suwon 16419 South Korea Department of Biomedical Engineering National Taiwan University Taipei 10617 Taiwan

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Hypoxia and matrix viscoelasticity sequentially regulate endothelial progenitor cluster-based vasculogenesis 42

Hypoxia and matrix viscoelasticity sequentially regulate end...

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42nd Society for Biomaterials Annual Meeting and Exposition 2019: The Pinnacle of Biomaterials Innovation and Excellence

作者： Blatchley, Michael R. Hall, Franklyn Wang, Songnan Pruitt, Hawley C. Gerecht, Sharon Department of Biomedical Engineering BaltimoreMD United States Department of Chemical and Biomolecular Engineering Johns Hopkins Physical Sciences–Oncology Center and Institute for NanoBioTechnology BaltimoreMD United States Department of Materials Science and Engineering Johns Hopkins University and Johns Hopkins School of Medicine BaltimoreMD United States Department of Oncology Johns Hopkins University and Johns Hopkins School of Medicine BaltimoreMD United States

ISBN: (纸本)9781510883901

Statement of Purpose: The mechanisms governing postnatal vasculogenesis have begun to be uncovered in the last several decades. These mechanisms have informed the design of numerous therapeutics, seeking to regenerate or control the formation of new vasculature following loss-of-function diseases, such as peripheral and coronary artery diseases, as well as provide an understanding of tumor angiogenesis. The processes which govern vascular regeneration in such clinical pathologies involve complex spatiotemporal interplay between physical and biochemical cues. The plenary work of several groups has described one mechanism by which blood vessels may form de novo. In this body of work, new blood vessels are formed through intracellular changes in a population wide phenomenon that leads to branching/sprouting through coalescence of single cells to form multicellular, luminal vessels. In addition to these works, a handful of observational reports in hypoxic tissues in vivo have indicated the presence of a secondary mechanism. However, an understanding of the regulatory mechanism governing this process is limited, due to a shortage in model systems that recapitulate the complex pathological microenvironmental cues. © 2019 Omnipress - All rights reserved.

关键词： Blood vessels

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Elastic colloidal monopoles and reconfigurable self-assembly in liquid crystals

arXiv

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arXiv 2020年

作者： Yuan, Ye Liu, Qingkun Senyuk, Bohdan Smalyukh, Ivan I. Department of Physics University of Colorado BoulderCO80309 United States Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program and Soft Materials Research Center University of Colorado BoulderCO80309 United States Renewable and Sustainable Energy Institute National Renewable Energy Laboratory University of Colorado BoulderCO80309 United States

Monopole-like electrostatic interactions are ubiquitous in biology1 and condensed matter2-4, but they are often screened by counter-ions and cannot be switched from attractive to repulsive. In colloidal science, where the prime goal is to develop colloidal particles2,3 that mimic and exceed the diversity and length-scales of atomic and molecular assembly, electrostatically charged particles cannot change the sign of their surface charge or transform from monopoles to higher-order multipoles4. In liquid-crystal colloids5-7, elastic interactions between particles arise to minimize the free energy associated with elastic distortions in the long-range alignment of rod-like molecules around the particles5. In dipolar6,8, quadrupolar8-12 and hexadecapolar13 nematic colloids, the symmetries of such elastic distortions mimic both electrostatic multipoles14 and the outmost occupied electron shells of atoms7,15,16. Electric and magnetic switching17,18, spontaneous transformations19 and optical control20 of elastic multipoles, as well as their interactions with topological defects and surface boundary conditions, have been demonstrated in such colloids21-23. However, it has long been understood5,24 that elastic monopoles should relax to uniform or higher-order multipole states because of the elastic torques that they induce5,7. Here we develop nematic colloids with strong elastic monopole moments and with elastic torques balanced by optical torques exerted by ambient light. We demonstrate the monopole-to-quadrupole reconfiguration of these colloidal particles by unstructured light, which resembles the driving of atoms between the ground state and various excited states. We show that the sign of the elastic monopoles can be switched, and that like-charged monopoles attract whereas oppositely charged ones repel, unlike in electrostatics14. We also demonstrate the out-of-equilibrium dynamic assembly of these colloidal particles. This diverse and surprising behaviour is explained

关键词： Electrostatics

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Phase equilibrium of water with hexagonal and cubic ice using the SCAN functional

arXiv

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arXiv 2021年

作者： Piaggi, Pablo Miguel Panagiotopoulos, Athanassios Z. Debenedetti, Pablo G. Car, Roberto Department of Chemistry Princeton University PrincetonNJ08544 United States Department of Chemical and Biological Engineering Princeton University PrincetonNJ08544 United States Princeton Institute for the Science and Technology of Materials Princeton University PrincetonNJ08544 United States Department of Physics Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Machine learning models are rapidly becoming widely used to simulate complex physicochemical phenomena with ab initio accuracy. Here, we use one such model as well as direct density functional theory (DFT) calculations to investigate the phase equilibrium of water, hexagonal ice (Ih), and cubic ice (Ic), with an eye towards studying ice nucleation. The machine learning model is based on deep neural networks and has been trained on DFT data obtained using the SCAN exchange and correlation functional. We use this model to drive enhanced sampling simulations aimed at calculating a number of complex properties that are out of reach of DFT-driven simulations and then employ an appropriate reweighting procedure to compute the corresponding properties for the SCAN functional. This approach allows us to calculate the melting temperature of both ice polymorphs, the driving force for nucleation, the heat of fusion, the densities at the melting temperature, the relative stability of ice Ih and Ic, and other properties. We find a correct qualitative prediction of all properties of interest. In some cases, quantitative agreement with experiment is better than for state-of-the-art semiempirical potentials for water. Our results also show that SCAN correctly predicts that ice Ih is more stable than ice Ic. Copyright © 2021, The Authors. All rights reserved.

关键词： Ice

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Ultra-Efficient Resistance Switching between Charge Ordered Phases in 1T-TaS2 with a Single Picosecond Electrical Pulse

arXiv

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arXiv 2022年

作者： Venturini, Rok Mraz, Anže Vaskivskyi, Igor Vaskivskyi, Yevhenii Svetin, Damjan Mertelj, Tomaž Pavlovič, Leon Cheng, Jing Chen, Genyu Amarasinghe, Priyanthi Qadri, Syed B. Trivedi, Sudhir B. Sobolewski, Roman Mihailovic, Dragan Jožef Stefan Institute Jamova 39 LjubljanaSI-1000 Slovenia Faculty of Mathematics and Physics University of Ljubljana Jadranska 19 LjubljanaSI-1000 Slovenia Faculty for Electrical Engineering University of Ljubljana Tržaška 25 LjubljanaSI-1000 Slovenia CENN Nanocenter Jamova 39 LjubljanaSI-1000 Slovenia ELEP Electronics LjubljanaSI-1000 Slovenia Materials Science Program Laboratory for Laser Energetics University of Rochester New York14627 United States Brimrose Technology Corporation SparksMD21152 United States U.S. Naval Research Laboratory WashingtonDC United States Department of Electrical and Computer Engineering Department of Physics and Astronomy University of Rochester New York14627 United States

Progress in high-performance computing demands significant advances in memory technology. Among novel memory technologies that promise efficient device operation on a sub-ns timescale, resistance switching between charge ordered phases of 1T-TaS2 has shown to be potentially useful for development of high-speed, energy efficient non-volatile memory devices. Measurement of the electrical operation of such devices in the picosecond regime is technically challenging and hitherto still largely unexplored. Here we use an optoelectronic "laboratory-on-a-chip" experiment for measurements of ultrafast memory switching, enabling accurate measurement of electrical switching parameters with 100 fs temporal resolution. Photoexcitation and electro-optic sampling on a (Cd,Mn)Te substrate are used to generate and, subsequently, measure electrical pulse propagation, with intra-band excitation and sub-gap probing, respectively. We demonstrate high contrast non-volatile resistance switching from high to low resistance states of a 1T-TaS2 device using single sub-2ps electrical pulses. Using detailed modeling we find that the switching energy density per unit area is exceptionally small, EA = 9.4 fJ/µm2. The speed and energy efficiency of an electronic "write" process, place the 1T-TaS2 devices into a category of their own among new generation non-volatile memory devices. Copyright © 2022, The Authors. All rights reserved.

关键词： Switching

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Ambient Monitoring of Gait and Machine Learning Models for Dynamic and Short-Term Falls Risk Assessment in People With Dementia

TechRxiv

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TechRxiv 2021年

作者： Adeli, Vida Korhani, Navid Sabo, Andrea Mehdizadeh, Sina Flint, Alastair Mansfield, Avril Iaboni, Andrea Taati, Babak TorontoON Canada The Institute of Biomedical Engineering University of Toronto TorontoON Canada The Department of Computer Science University of Toronto TorontoON Canada Department of Physical Therapy University of Toronto TorontoON Canada The Evaluative Clinical Sciences Hurvitz Brain Sciences Program Sunnybrook Research Institute TorontoON Canada The Department of Psychiatry University of Toronto TorontoON Canada Center for Mental Health University Health Network TorontoON Canada The Centre for Mental Health UHN TorontoON Canada

Falls are a leading cause of morbidity and mortality in older adults with dementia residing in long-term care. Having access to a frequently updated and accurate estimate of the likelihood of a fall over a short time frame for each resident will enable care staff to provide targeted interventions to prevent falls and resulting injuries. To this end, machine learning models to estimate and frequently update the risk of a fall within the next 4 weeks were trained on longitudinal data from 54 older adult participants with dementia. Data from each participant included baseline clinical assessments of gait, mobility, and fall risk at the time of admission, daily medication intake in three medication categories, and frequent assessments of gait performed via a computer vision-based ambient monitoring system. Systematic ablations investigated the effects of various hyperparameters and feature sets and experimentally identified differential contributions from baseline clinical assessments, ambient gait analysis, and daily medication intake. In leave-one-subject-out cross-validation, the best performing model predicts the likelihood of a fall over the next 4 weeks with a sensitivity and specificity of 72.8 and 73.2, respectively, and achieved an area under the receiver operating characteristic curve (AUROC) of 76.2. By contrast, the best model excluding ambient gait features achieved an AUROC of 56.2 with a sensitivity and specificity of 51.9 and 54.0, respectively. Future research will focus on externally validating these findings to prepare for the implementation of this technology to reduce fall and fall-related injuries in long-term care. © 2021, CC BY.

关键词： Machine learning

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Three-Dimensional Dynamics of a Magnetic Hopfion Driven by Spin Transfer Torque

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Physical Review Letters 2020年第12期124卷 127204-127204页

作者： Yizhou Liu Wentao Hou Xiufeng Han Jiadong Zang Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China Department of Physics and Astronomy University of New Hampshire Durham New Hampshire 03824 USA Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 China Songshan Lake Materials Laboratory Dongguan Guangdong 523808 China Materials Science Program University of New Hampshire Durham New Hampshire 03824 USA

Magnetic hopfion is a three-dimensional (3D) topological soliton with novel spin structure that would enable exotic dynamics. Here, we study the current-driven 3D dynamics of a magnetic hopfion with a unit Hopf index in a frustrated magnet. Attributed to the spin Berry phase and symmetry of the hopfion, the phase space entangles multiple collective coordinates, thus the hopfion exhibits rich dynamics including longitudinal motion along the current direction, transverse motion perpendicular to the current direction, rotational motion, and dilation. Furthermore, the characteristics of hopfion dynamics is determined by the ratio between the nonadiabatic spin transfer torque parameter and the damping parameter. Such peculiar 3D dynamics of magnetic hopfion could shed light on understanding the universal physics of hopfions in different systems and boost the prosperous development of 3D spintronics.

关键词： Frustrated magnetism Spin texture Spin transfer torque Solitons

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