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Effect of Phase Structure Evolution on Thermal Expansion and Toughness of (Nd1-xScx)2Zr2O7 (x = 0, 0.025, 0.05, 0.075, 0.1 ) Ceramics

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Journal of Materials Science & Technology 2017年第2期33卷 192-197页

作者： Xiaoxiang Zhao Lei Guo caimei wang Yu Zhang Fuxing Ye School of Materials Science and Engineering Tianjin University Tianjin 300072 China Tianjin Key Laboratory of Advanced Joining Technology Tianjin University Tianjin 300072 China Key Lab of Advanced Ceramics and Machining Technology of Ministry of Education Tianjin University Tianjin 300072 China

Nd2Zr2O7 is being explored as an alternate thermal barrier coating （TBC） material for operating above 1300 ℃, and great effort has been made to enlarge its thermal expansion coefficient （TEC） and improve its toughness. In this study, Sc203 vvas doped to Nd2Zr2O7. The phase structure, TECs and toughness of （Nd1-xScx）2Zr2O7 （x = 0, 0.025, 0.05, 0.075, 0.1 ） compounds were investigated. （Nd1-xScx）2Zr2O7 （x = 0, 0.025, 0.05, 0,075） exhibited pyrochlore structure, while （Nd0.9Sc0.1）2Zr2O7 consisted of pyrochlore and fluorite phases. With the increase of the Sc203 content, the ordering degree of the pyrochlore in the compounds decreased. In （Nd1-xScx）2Zr2O7 series, （Nd0.925Sc0.075）2Zr2O7 exhibited the largest TEC, while the toughness of the compounds increased with increasing the Sc2O3 content. The related mechanisms were discussed based on the crystal structure analysis. Considering the TEC and toughness, 10 mol% Sc2O3 was sug- gested as the optimal doping content for Nd2Zr2O7 ceramic.

关键词： Thermal harrier coating Nd2Zr2O7 Doping Phase structure Thermal expansion coefficient Toughness

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Personalized Privacy-Preserving Trajectory Data Publishing

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Chinese Journal of Electronics 2017年第2期26卷 285-291页

作者： LU Qiwei wang caimei XIONG Yan XIA Huihua HUANG Wenchao GONG Xudong School of Computer Science and Technology University of Science and Technology of China Department of Computer Science and Engineering Hefei University

Due to the popularity of mobile internet and location-aware devices,there is an explosion of location and tra jectory data of moving objects.A few proposals have been proposed for privacy preserving tra jectory data publishing,and most of them assume the attacks with the same adversarial background *** practice,different users have different privacy *** non-personalized privacy assumption does not meet the personalized privacy requirements,meanwhile,it looses the chance to achieve better utility by taking advantage of differences of users’ privacy *** study the personalized tra jectory k-anonymity criterion for trajectory data ***,we explore and propose an overall framework which provides privacy preserving services based on users’ personal privacy requests,including tra jectory clustering,editing and *** demonstrate the efficiency and effectiveness of our scheme through experiments on real world dataset.

关键词： Personalization Tra jectory data Privacy-preserving data publishing

High temperature oxidation treated 3D printed anatomical WE43 alloy scaffolds for repairing periarticular bone defects:In vitro and in vivo studies

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Bioactive Materials 2024年第2期32卷 177-189页

作者： Bingchuan Liu Jinge Liu Chaoxin wang Zhengguang wang Shuyuan Min caimei wang Yufeng Zheng Peng Wen Yun Tian Department of Orthopaedics Peking University Third HospitalBeijing100191China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing100191China The State Key Laboratory of Tribology Tsinghua UniversityBeijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing100084China Beijing AKEC Medical Co. Ltd.Beijing102200China School of Materials Science and Engineering Peking UniversityBeijing100871China

Reconstruction of subarticular bone defects is an intractable challenge in *** simultaneous repair of cancellous defects,fractures,and cartilage damage is an ideal surgical outcome.3D printed porous anatomical WE43(magnesium with 4 wt%yttrium and 3 wt%rare earths)scaffolds have many advantages for repairing such bone defects,including good biocompatibility,appropriate mechanical strength,customizable shape and structure,and *** a previous investigation,we successfully enhanced the corrosion resistance of WE43 samples via high temperature oxidation(HTO).In the present study,we explored the feasibility and effectiveness of HTO-treated 3D printed porous anatomical WE43 scaffolds for repairing the cancellous bone defects accompanied by split fractures via in vitro and in vivo *** HTO treatment,a dense oxidation layer mainly composed of Y2O3 and Nd2O3 formed on the surface of *** addition,the majority of the grains were equiaxed,with an average grain size of 7.4μ*** and rabbit experiments confirmed the non-cytotoxicity and biocompatibility of the HTO-treated WE43 *** the implantation of scaffolds inside bone defects,their porous structures could be maintained for more than 12 weeks without penetration and for more than 6 weeks with *** the postoperative follow-up period for up to 48 weeks,radiographic examinations and histological analysis revealed that abundant bone gradually regenerated along with scaffold degradation,and stable osseointegration formed between new bone and scaffold *** images further demonstrated no evidence of any obvious damage to the cartilage,ligaments,or menisci,confirming the absence of traumatic ***,finite element analysis and biomechanical tests further verified that the scaffolds was conducive to a uniform mechanical *** conclusion,applying the HTO-treated 3D printed porous anatomical WE43 scaffolds exhibited favorable repa

关键词： Periarticular bone defects 3D printing technology Magnesium alloy High temperature oxidation Osseointegration

Influence of layer thickness on formation quality,microstructure,mechanical properties,and corrosion resistance of WE43 magnesium alloy fabricated by laser powder bed fusion

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Journal of Magnesium and Alloys 2024年第4期12卷 1367-1385页

作者： Bangzhao Yin Jinge Liu Bo Peng Mengran Zhou Bingchuan Liu Xiaolin Ma caimei wang Peng Wen Yun Tian Yufeng Zheng State Key Laboratory of Tribology in Advanced Equipment Beijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Institute for Precision Medicine Tsinghua UniversityBeijing102218China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Beijing AKEC Medical Co. Ltd.Beijing 102200China School of Materials Science and Engineering Peking UniversityBeijing 100871China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing 100191China

Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical *** thickness(LT)is of great significance to the L-PBF process but has not been studied for Mg *** this study,WE43 Mg alloy bulk cubes,porous scaffolds,and thin walls with layer thicknesses of 10,20,30,and 40μm were *** required laser energy input increased with increasing layer thickness and was different for the bulk cubes and porous *** tended to occur at the connection joints in porous scaffolds for LT40 and could be eliminated by reducing the laser energy *** thin wall parts,a large overhang angle or a small wall thickness resulted in porosity when a large layer thicknesses was used,and the porosity disappeared by reducing the layer thickness or laser energy input.A deeper keyhole penetration was found in all occasions with porosity,explaining the influence of layer thickness,geometrical structure,and laser energy input on the *** the samples achieved a high fusion quality with a relative density of over 99.5%using the optimized laser energy *** increased layer thickness resulted to more precipitation phases,finer grain sizes and decreased grain *** the similar high fusion quality,the tensile strength and elongation of bulk samples were significantly improved from 257 MPa and 1.41%with the 10μm layer to 287 MPa and 15.12%with the 40μm layer,in accordance with the microstructural *** effect of layer thickness on the compressive properties of porous scaffolds was ***,the corrosion rate of bulk samples accelerated with increasing the layer thickness,mainly attributed to the increased number of precipitation phases.

关键词： Magnesium alloy WE43 Laser powder bed fusion Layer thickness Process optimization

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Improving corrosion resistance of additively manufactured WE43 magnesium alloy by high temperature oxidation for biodegradable applications

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Journal of Magnesium and Alloys 2024年第3期12卷 940-953页

作者： Jinge Liu Bangzhao Yin Fei Song Bingchuan Liu Bo Peng Peng Wen Yun Tian Yufeng Zheng Xiaolin Ma caimei wang State Key Laboratory of Tribology in Advanced Equipment Beijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Department of Orthopaedics Beijing Tsinghua Changgung HospitalInstitute for Precision MedicineTsinghua UniversityBeijing102218China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing 100191China School of Materials Science and Engineering Peking UniversityBeijing 100871China Beijing AKEC Medical Co. Ltd.Beijing 102200China

Laser powder bed fusion(L-PBF)has been employed to additively manufacture WE43 magnesium(Mg)alloy biodegradable implants,but WE43 L-PBF samples exhibit excessively rapid *** this work,dense WE43 L-PBF samples were built with the relativity density reaching 99.9%.High temperature oxidation was performed on the L-PBF samples in circulating air via various heating temperatures and holding *** oxidation and diffusion at the elevated temperature generated a gradient structure composed of an oxide layer at the surface,a transition layer in the middle and the *** oxide layer consisted of rare earth(RE)oxides,and became dense and thick with increasing the holding *** matrix was composed ofα-Mg,RE oxides and Mg_(24)RE_(5) *** precipitates almost disappeared in the transition *** passivation effect was observed in the samples treated by a suitable high temperature *** original L-PBF samples lost 40%weight after 3-day immersion in Hank’s solution,and broke into fragments after 7-day *** casted and solution treated samples lost roughly half of the weight after 28-day *** high temperature oxidation samples,which were heated at 525℃ for 8 h,kept the structural integrity,and lost only 6.88%weight after 28-day *** substantially improved corrosion resistance was contributed to the gradient structure at the *** one hand,the outmost dense layer of RE oxides isolated the corrosive medium;on the other hand,the transition layer considerably inhibited the corrosion owing to the lack of ***,high temperature oxidation provides an efficient,economic and safe approach to inhibit the corrosion of WE43 L-PBF samples,and has promising prospects for future clinical applications.

关键词： Laser powder bed fusion Biodegradable magnesium alloy High temperature oxidation Corrosion resistance WE43.

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The effect of pore size on the mechanical properties, biodegradation and osteogenic effects of additively manufactured magnesium scaffolds after high temperature oxidation: An in vitro and in vivo study

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Bioactive Materials 2023年第10期28卷 537-548页

作者： Chaoxin wang Jinge Liu Shuyuan Min Yu Liu Bingchuan Liu Yuanyu Hu Zhengguang wang Fengbiao Mao caimei wang Xiaolin Ma Peng Wen Yufeng Zheng Yun Tian Department of Orthopedics Peking University Third HospitalBeijing100191China Engineering Research Center of Bone and Joint Precision Medicine Ministry of EducationBeijing100191China Department of Mechanical Engineering Tsinghua UniversityBeijing100084China Institute of Medicine Innovation and Research Peking University Third HospitalBeijing100191China Beijing AKEC Medical Co. Ltd.Beijing102200China School of Materials Science and Engineering Peking UniversityBeijing100871China

The effects of pore size in additively manufactured biodegradable porous magnesium on the mechanical properties and biodegradation of the scaffolds as well as new bone formation have rarely been reported. In this work, we found that high temperature oxidation improves the corrosion resistance of magnesium scaffold. And the effects of pore size on the mechanical characteristics and biodegradation of scaffolds, as well as new bone formation, were investigated using magnesium scaffolds with three different pore sizes, namely, 500, 800, and 1400 μm (P500, P800, and P1400). We discovered that the mechanical characteristics of the P500 group were much better than those of the other two groups. In vitro and in vivo investigations showed that WE43 magnesium alloy scaffolds supported the survival of mesenchymal stem cells and did not cause any local toxicity. Due to their larger specific surface area, the scaffolds in the P500 group released more magnesium ions within reasonable range and improved the osteogenic differentiation of bone mesenchymal stem cells compared with the other two scaffolds. In a rabbit femoral condyle defect model, the P500 group demonstrated unique performance in promoting new bone formation, indicating its great potential for use in bone defect regeneration therapy.

关键词： Pore size Additive manufacturing WE43 alloy Magnesium alloy

Surface treatment of 3D printed porous Ti6Al4V implants by ultraviolet photofunctionalization for improved osseointegration

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Bioactive Materials 2022年第1期7卷 26-38页

作者： Chuan Yin Teng Zhang Qingguang Wei Hong Cai Yan Cheng Yun Tian Huijie Leng caimei wang Shiqing Feng Zhongjun Liu Department of Orthopedics Peking University Third HospitalBeijing100191People’s Republic of China Department of Orthopedics Qilu Hospital of Shandong UniversityJinan250012People’s Republic of China Center for Biomedical Materials and Tissue Engineering Academy for Advanced Interdisciplinary StudiesPeking UniversityBeijing100871People’s Republic of China Beijing AKEC Medical Company Ltd. Beijing102200People’s Republic of China

Three-dimensional(3D)-printed porous Ti6Al4V implants play an important role in the reconstruction of bone ***,its osseointegration capacity needs to be further improved,and related methods are inadequate,especially lacking customized surface treatment ***,we aimed to design an omnidirectional radiator based on ultraviolet(UV)photofunctionalization for the surface treatment of 3D-printed porous Ti6Al4V implants,and studied its osseointegration promotion effects in vitro and in vivo,while elucidating related *** UV treatment,the porous Ti6Al4V scaffolds exhibited significantly improved hydrophilicity,cytocompatibility,and alkaline phosphatase activity,while preserving their original mechanical *** increased osteointegration strength was further proven using a rabbit condyle defect model in vivo,in which UV treatment exhibited a high efficiency in the osteointegration enhancement of porous Ti6Al4V scaffolds by increasing bone ingrowth(BI),the bone-implant contact ratio(BICR),and the mineralized/osteoid bone *** advantages of UV treatment for 3D-printed porous Ti6Al4V implants using the omnidirectional radiator in the study were as follows:1)it can significantly improve the osseointegration capacity of porous titanium implants despite the blocking out of UV rays by the porous structure;2)it can evenly treat the surface of porous implants while preserving their original topography or other morphological features;and 3)it is an easy-to-operate low-cost process,making it worthy of wide clinical application.

关键词： Three-dimensional-printed porous implants UV photofunctionalization Omnidirectional UV radiator Osseointegration

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

Simultaneous Determination of Chloropropanol Fatty Acid Esters in Refined Corn Oil Using GC-MS

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Simultaneous Determination of Chloropropanol Fatty Acid Este...