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Biodegradable magnesium alloy WE43 porous scaffolds fabricated by laser powder bed fusion for orthopedic applications:Process optimization,in vitro and in vivo investigation

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Bioactive materials 2022年第10期7卷 301-319页

作者： Jinge Liu Bingchun Liu Shuyuan Min Bangzhao Yin Bo Peng Zishi Yu Caimei Wang Xiaolin Ma Peng Wen Yun Tian Yufeng Zheng The State Key Laboratory of Tribology Tsinghua UniversityBeijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing100084China Department of Orthopaedics Peking University Third HospitalBeijing100191China School of Materials Science and Engineering Peking UniversityBeijing100871China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing100191China Beijing AKEC Medical Co. Ltd.Beijing102200China

Laser powder bed fusion(L-PBF)of magnesium(Mg)alloy porous scaffolds is expected to solve the dual challenges from customized structures and biodegradable functions required for repairing bone ***,one of the key technical difficulties lies in the poor L-PBF process performance of Mg,contributed by the high susceptibility to oxidation,vaporization,thermal expansion,and powder attachment *** work investigated the influence of L-PBF energy input and scanning strategy on the formation quality of porous scaffolds by using WE43 powder,and characterized the microstructure,mechanical properties,biocompatibility,biodegradation and osteogenic effect of the as-built WE43 porous *** the customized energy input and scanning strategy,the relative density of struts reached over 99.5%,and the geometrical error between the designed and the fabricated porosity declined to below 10%.Massive secondary phases including intermetallic precipitates and oxides were *** compressive strength(4.37-23.49 MPa)and elastic modulus(154.40-873.02 MPa)were comparable to those of cancellous *** biocompatibility was observed by in vitro cell viability and in vivo *** biodegradation of as-built porous scaffolds promoted the osteogenic effect,but the structural integrity devastated after 12 h by the immersion tests in Hank’s solution and after 4 weeks by the implantation in rabbits’femur,indicating an excessively rapid degradation rate.

关键词： Additive manufacturing Biodegradable metal Laser powder bed fusion Magnesium alloy Porous scaffold WE43

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Modelling Growth, Remodelling and Damage of a Thick-Walled Fibre-Reinforced Artery with Active Response: Application to Cerebral Vasospasm and Treatment

SSRN

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SSRN 2024年

作者： Pederzani, Giulia Grytsan, Andrii Hoekstra, Alfons G. Robertson, Anne M. Watton, Paul N. Computational Science Lab Instituut voor Informatica Universiteit van Amsterdam Netherlands Department of Mechanical Engineering University of Sheffield United Kingdom Department of Computer Science University of Sheffield United Kingdom INSIGNEO Institute of in silico Medicine University of Sheffield United Kingdom Department of Mechanical Engineering and Materials Science University of Pittsburgh United States

Background: Cerebral vasospasm, a prolonged constriction of cerebral arteries, is the first cause of morbidity and mortality for patients who survive hospitalisation after aneurysmal subarachnoid haemorrhage. Recently, it has been observed that (low pressure) stent-retrievers can be used to successfully treat the disease which has challenged a widely held viewpoint that damage to the extracellular matrix is necessary to mechanically resolve the ***: We apply a 3D finite element rate-based constrained mixture model (rb-CMM) approach to simulate the artery, vasospasm, remodelling and treatment with stents. The artery is modelled as a thick-walled fibre-reinforced constrained mixture subject to physiological pressure and axial stretch. The model accounts for distributions of collagen fibre homeostatic stretches, VSMC active response, remodelling and damage. After simulating vasospasm and subsequent remodelling of the artery to a new homeostatic state, we simulate treatment with commonly available stent-retrievers. Subsequently, we perform a parameter study to examine how arterial diameter and thickness affect the success of stent ***: The model predictions on the amount of pressure required to mechanically resolve the constriction are consistent with those applied by stent-retrievers. In agreement with reported clinical observations, our model predicts that stent-retrievers tend to be effective in arteries of up to about 3mm original diameter, but usually fail in larger ones. In addition, we observe that accounting for (physiological) variations in arterial wall thickness, the stent pressure requirement may need to double to successfully treat ***: We have developed a novel rb-CMM that accounts for VSMC active response, remodelling and damage. Consistent with clinical observations, simulations predict that stent-retrievers can mechanically resolve vasospasm. Moreover, accounting for a patient’s arterial properties is imp

关键词： Stents

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Enabling highly efficient and broadband electromagnetic wave absorption by tuning impedance match in high-entropy transition metal diborides (HETMB_(2))

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Journal of Advanced Ceramics 2021年第6期10卷 1299-1316页

作者： Weiming ZHANG Fu-Zhi DAI Huimin XIANG Biao ZHAO Xiaohui WANG Na NI Rajamallu KARRE Shijiang WU Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Henan Key Laboratory of Aeronautical Materials and Application Technology School of Material Science and EngineeringZhengzhou University of AeronauticsZhengzhou 450046China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Lab of Education Ministry for Power Machinery and Engineering School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Zibo Firststar New Material Incorporated Co. Ltd.Zibo 255000China

The advance in communication technology has triggered worldwide concern on electromagnetic wave *** cope with this challenge,exploring high-performance electromagnetic(EM)wave absorbing materials with dielectric and magnetic losses coupling is urgently *** the EM wave absorbers,transition metal diborides(TMB2)possess excellent dielectric loss ***,akin to other single dielectric materials,poor impedance match leads to inferior ***-entropy engineering is expected to be effective in tailoring the balance between dielectric and magnetic losses through compositional ***,three HE TMB2 powders with nominal equimolar TM including HE TMB2-I(TM=Zr,Hf,Nb,Ta),HE TMB2-2(TM=Ti,Zr,Hf,Nb,Ta),and HE TMB2-3(TM=Cr,Zr,Hf,Nb,Ta)have been designed and prepared by one-step boro/carbothermal *** a result of synergistic effects of strong attenuation capability and impedance match,HE TMB2-1 shows much improved performance with the optimal minimum reflection loss(RL_(min))of-59.6 dB(8.48 GHz,2.68 mm)and effective absorption bandwidth(EAB)of 7.6 GHz(2.3 mm).Most impressively,incorporating Cr in HE TMB2-3 greatly improves the impedance match over 1-18 GHz,thus achieving the RLmin of-56.2 dB(8.48 GHz,2.63 mm)and the EAB of 11.0 GHz(2.2 mm),which is superior to most other EM wave absorbing *** work reveals that constructing high-entropy compounds,especially by incorporating magnetic elements,is effectual in tailoring the impedance match for highly conductive compounds,i.e.,tuning electrical conductivity and boosting magnetic loss to realize highly efficient and broadband EM wave absorption with dielectric and magnetic coupling in single-phase materials.

关键词： transition metal diboride(TMB2) high-entropy(HE)ceramics electronic structure microwave absorption dielectric and magnetic losses coupling

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Determining Response Differences to Microgravity in Male and Female Bioengineered Cartilage Tissues 73

Determining Response Differences to Microgravity in Male and...

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73rd International Astronautical Congress, IAC 2022

作者： Dhunnoo, Kirtan Aissiou, Amira Jha, Shankar Ravin, Rahul Wong, Kinston Adesida, Adetola Department of Mechanical Engineering Faculty of Engineering University of Alberta EdmontonAB Canada Department of Medicine Faculty of Medicine and Dentistry University of Alberta EdmontonAB Canada Institute for Aerospace Studies Faculty of Applied Science & Engineering University of Toronto TorontoON Canada Department of Chemical and Materials Engineering Faculty of Engineering University of Alberta Canada Department of Surgery Faculty of Medicine & Dentistry University of Alberta Canada

As humanity pushes further into the unknown, astronauts will be faced with heightened risks of physiological issues during long-term missions. Bone mass loss seen in astronauts is proportional to the time spent in zero-gravity, and increases the chance of osteoarthritis (OA), a disease that affects around 240 million people worldwide. OA occurs when the protective cartilage cushioning the joints degrades over time, and interestingly presents itself in women almost twice as much as in men. Knee osteoarthritis (KOA) is the most common form of OA and is used to study its pathogenesis. Several astronaut studies have already shown that prolonged periods of zero-gravity contribute directly to cartilage degradation in various measurable fashions. Others have investigated cartilage tissue behaviour inside artificial biological environments and centrifuges. The next step is to explore minute changes in cartilage tissue in microgravity, such as during a parabolic flight, to generate a deeper molecular and genetic understanding of OA pathogenesis. Flying aboard the Canadian Space Agency's Falcon-20 parabolic aircraft, this experiment evaluated the molecular differences between female and male bioengineered cartilage samples when exposed to microgravity, while also for the first time attempted to explore the role of metabolites (the intermediate products of metabolism) in KOA pathogenesis. Metabolite activity responds to gravitational changes on a per-second basis and thus shows exact variations in cartilage tissue metabolism and degradation over time more accurately than before. Until now, such a focus on metabolites has not been conducted in this context. Sample groups were subject to set parabola quantities to determine the effect of repeated microgravity exposures. Hydraulic systems to promote the transfer of nutrient solution (to maintain sample health) and RNAlater reagent (to freeze the samples' molecular activity in time) were implemented, operated by two mission specia

关键词： Microgravity

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Predicting Ion Sequestration in Charged Polymers with the Steepest-Entropy-Ascent Quantum Thermodynamic Framework

arXiv

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arXiv 2023年

作者： McDonald, Jared von Spakovsky, Michael R. Reynolds, William T. Materials Science & Engineering Department Virginia Tech BlacksburgVA24061 United States Mechanical Engineering Department Virginia Tech BlacksburgVA24061 United States

The steepest-entropy-ascent quantum thermodynamic framework is used to investigate the effectiveness of multi-chain polyethyleneimine-methylenephosphonic acid in sequestering rare-earth ions (Eu+3) from aqueous solutions. The framework applies a thermodynamic equation of motion to a discrete energy eigenstructure to model the binding kinetics of europium ions to reactive sites of the polymer chains. The energy eigenstructure is generated using a non-Markovian Monte Carlo model that estimates energy level degeneracies. The equation of motion is used to determine the occupation probability of each energy level, describing the unique path through thermodynamic state space by which the polymer system sequesters rare-earth ions from solution. A second Monte Carlo simulation is conducted to relate the kinetic path in state space to physical descriptors associated with the polymer, including the radius of gyration, tortuosity, and Eu-neighbor distribution functions. These descriptors are used to visualize the evolution of the polymer during the sequestration process. The fraction of sequestered Eu+3 ions depends upon the total energy of the system, with lower energy resulting in higher sequestration. The kinetics of the overall sequestration are dependent on the steepest-entropy-ascent principle used by the equation of motion to generate a unique kinetic path from an initial non-equilibrium state. © 2023, CC BY-NC-ND.

关键词： Entropy

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Flexural and free vibration responses of thick isotropic bridge deck using a novel two variable refined plate theory

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Structural engineering and Mechanics 2022年第6期82卷 725-734页

作者： Djidar, Fatima Zohra Hebali, Habib Amara, Khaled Tounsi, Abdelouahed Bendaho, Boudjema Ghazwani, M.H. Hussain, Muzamal Smart Structures Laboratory University of Ain Témouchent Faculty of Science and Technology Civil Engineering Department Algeria Material and Hydrology Laboratory Civil Engineering Department Faculty of Technology University of Sidi Bel Abbes Algeria Civil Engineering Department Faculty of Science and Technology University of Mascara Algeria Engineering and Sustainable Development Laboratory University of Ain Temouchent Ain Temouchent46000 Algeria Yonsei University Seoul Korea Republic of Department of Civil and Environmental Engineering King Fahd University of Petroleum and Minerals Eastern Province Dhahran31261 Saudi Arabia Interdisciplinary Research Center for Construction and Building Materials KFUPM Dhahran31261 Saudi Arabia Department of Mechanical Engineering Faculty of Engineering Jazan University P.O Box 45124 Jazan Saudi Arabia Department of Mathematics Govt. College University Faisalabad Faisalabad38000 Pakistan

This work presents a simple exponential shear deformation theory for the flexural and free vibration responses of thick bridge deck. Contrary to the existing higher order shear deformation theories (HSDT) and the first shear deformation theory (FSDT), the proposed model uses a new displacement field which incorporates undetermined integral terms and involves only two variables. Governing equations and boundary conditions of the theory are derived by the principle of virtual work. The simply supported thick isotropic square and rectangular plates are considered for the detailed numerical studies. Results of displacements, stresses and frequencies are compared with those of other refined theories and exact theory to show the efficiency of the proposed theory. Good agreement is achieved of the present results with those of higher order shear deformation theory (HSDT) and elasticity theory. Moreover, results demonstrate that the developed two variable refined plate theory is simple for solving the flexural and free vibration responses of thick bridge deck and can achieve the same accuracy of the existing HSDTs which have more number of variables. Copyright © 2022 Techno-Press, Ltd.

关键词： Shear stress

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Localized Accelerated Degradation of Magnesium: A New Insight into the Mechanism of its Biomedical Degradation

SSRN

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SSRN 2024年

作者： Zhang, Yue Yan, Kai Xu, Wen Wang, Cheng Qian, Kun Shao, Yi Jiang, Genzhi Liu, Huan Ju, Jia Höche, Daniel An, X.L. Huang, Yuanding Willumeit-Römer, Regine Xue, Feng Hort, Norbert Bai, Jing Chu, Chenglin School of Materials Science and Engineering Jiangsu Key Laboratory for Advanced Metallic Materials Southeast University Nanjing211189 China Institute of Metallic Biomaterials Helmholtz-Zentrum Hereon Geesthacht21502 Germany College of Mechanical Engineering Yangzhou University Yangzhou225127 China Institute of Surface Science Helmholtz-Zentrum Hereon Geesthacht21502 Germany Institute of Biomedical Devices Southeast University Suzhou215163 China College of Materials Science and Engineering Hohai University Nanjing211100 China Jiangsu Key Laboratory for Light Metal Alloys Nanjing211212 China Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology School of Materials Science and Engineering Nanjing Institute of Technology Nanjing211167 China School of Materials Science and Engineering

Inhomogeneous degradation of Mg results in a potential safety risk for the application of its implants. The particular concern is the occurrence of localized accelerated degradation of Mg under the relatively enclosed condition. The present work investigated such a phenomenon using the Mg-4Zn tube in artificial blood plasma. Its occurrence mechanism was explored through elaborate experiments, including the hydrodynamic platform, real-time electrochemical detection, COMSOL simulation, and morphological observations. It is found the deficiency of Ca2+ and PO43+ in the localized solution induced by the excessively high pH value was responsible for its occurrence. © 2024, The Authors. All rights reserved.

关键词： Blood

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Multiple molecular chains grafted graphene oxide chelated with cerium cation towards anti-corrosion and anti-wear application

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Applied Surface science 2025年 703卷

作者： Liu, Yue Cai, Meng Xie, ZhiHui Xiong, Liangliang Fan, Xiaoqiang Zhu, Minhao School of Materials Science and Engineering Southwest Jiaotong University Chengdu610031 China Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province College of Chemistry and Chemical Engineering China West Normal University Nanchong637002 China Tribology Research Institute School of Mechanical Engineering Southwest Jiaotong University Chengdu610031 China

Graphene Oxide (GO) nanosheets show great potential in the field of corrosion protection owing to their lamellar structure and remarkable mechanical features. However, these nanosheets are highly susceptible to agglomerating in waterborne epoxy resin (EP) matrix, which results in their structure degradation and restricts their application in anti-corrosion field. To address this challenge, a novel approach is employed in this study, involving the synthesis of multiple molecular chains (PEI and EDTA) grafted GO nanosheets (designated as EAGO), and subsequently chelated with cerium cations (CEAGO). The grafting of multiple molecular chains solves the agglomeration phenomenon of GO nanosheets during the coating preparation process. Such an advanced structural design is crucial for corrosion protective coatings since the unique structure of grafted EDTA enables effective chelating of corrosion inhibitors to provide anti-corrosion and self-healing features, while the steric hindrance effect of multiple molecular chains restricts the mobility of EP molecular chains, thereby enhancing anti-wear properties. The CEAGO/EP coating achieves a corrosion protection efficiency of up to 96.53%, and the wear rate of the CEAGO/EP coating is approximately 62.88% lower than that of pure EP. Electrochemical Impedance Spectroscopy (EIS) and White-light interferometer (WLI) results demonstrated that the epoxy coating loaded with CEAGO nanosheets could provide robust corrosion protection and wear resistance for 6082 aluminum alloy. © 2025

关键词： Corrosion resistant coatings

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Development of a Life Prediction Model of Ti-6Al-4V obtained by Additive Manufacturing

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Procedia Structural Integrity 2024年 53卷 236-245页

作者： João Alves Teresa Morgado Ivan Galvão António Pereira Manuel Pereira Lisbon School of Engineering of Polytechnic Institute of Lisbon Portugal UNIDEMI - Research & Development Unit in Mechanical and Industrial Engineering Department of Mechanical and Industrial Engineering FCT NOVA - Faculty of Science and Technology Universidade Nova de Lisboa Almada Portugal Intelligent Systems Associate Laboratory Guimarães Portugal Navy Research Center Almada Portugal CEMMPRE – Centre for Mechanical Engineering Materials and Processes Department of Mechanical Engineering University of Coimbra Coimbra Portugal CDRsp & ESTG - Centre for Rapid and Sustainable Product Development & School of Technology and Management of Institute Polytechnic of Leiria Leiria Portugal CERENA- Center of Natural Resources and Environment Univerdade Lisboa Lisboa Portugal

The present study aimed to develop a new life prediction model of a Ti-6Al-4V alloy obtained by additive manufacturing (AM). The Selective Laser Melting (SLM) method was used to obtain specimens. This study contemplates four phases. The first phase encompasses an analysis of the manufacturing process, including the raw materials cycle, specimen design, and the cutting process. In the second phase, tensile and fatigue tests are conducted to obtain the elastic and plastic proprieties and fatigue parameters (S-N Curve). The third phase involves an analytical and quantitative study of the manufacturing intrinsic defects of the SLM process, using optical microscopy, micro and nanotomography, and image treatment. The last phase focused on developing a life prediction model for Ti-6Al-4V based on experimental findings from the preceding steps. In conclusion, Ti-6Al-4V alloy obtained by additive manufacturing showed better overall mechanical properties when compared to the same alloy produced by a traditional method, exhibiting robust plastic behaviour and good ductility. Concerning life prediction models, two new models were developed to predict the fatigue limit of a Ti-6Al-4V obtained by additive manufacturing based on two different defect quantification methods.

关键词： Ti-6Al-4V Additive Manufacturing Selective Laser Melting Life Prediction Modelos Tomography

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Design and Dynamic Analysis of a Two-Degree-of-Freedom Pneumatic-Electromagnetic Hybrid Actuator Using Bellows Pneumatic Actuator

Design and Dynamic Analysis of a Two-Degree-of-Freedom Pneum...

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Annual Conference of Industrial Electronics Society

作者： Akira Heya Keita Taki Yoshihiro Nakata Tsuyoshi Inoue Katsuhiro Hirata Department of Mechanical Systems Engineering Nagoya University Nagoya Japan Division of Materials and Manufacturing Science Osaka University Suita Japan Department of Mechanical and Intelligent Systems Engineering The University of Electro-Communications Chofu Japan

Various actuators have been developed to improve the performance of cooperative robots. Multi-degree-of-freedom (multi-DOF) electromagnetic actuators can rotate multi-DOF by a direct drive and can contribute to system miniaturization and higher precision. However, the biggest challenge is to increase the output because the torque cannot be amplified using a reduction gear. To solve this problem, this paper focuses on a hybrid actuation with a pneumatic actuator, which has a large output density. In this study, we propose a two-DOF pneumatic-electromagnetic hybrid actuator that integrates a bellows pneumatic actuator and a two-DOF electromagnetic actuator. First, the concept, design, and operating principle are presented. Next, the torque control method, dynamic model, and attitude control system are shown. In the torque analysis, the maximum torque of the proposed actuator is four times larger compared with a conventional two-DOF electromagnetic actuator of the same size. The dynamic simulation results show that attitude control is possible with hybrid actuation. Based on the results, a hybrid multi-DOF actuator using multiple drive sources is proposed for the first time.

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