Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.Howe...Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.展开更多
Biodegradable magnesium(Mg)alloy has been considered as a new generation of orthopedic implant ma-terial.Nevertheless,local corrosion usually occurs since the severe micro-galvanic behavior amongα-Mg and precipitates...Biodegradable magnesium(Mg)alloy has been considered as a new generation of orthopedic implant ma-terial.Nevertheless,local corrosion usually occurs since the severe micro-galvanic behavior amongα-Mg and precipitates,and results in too rapid degradation.In this study,porous Mg-Zn-Gd part was fabricated using laser additive manufacturing combined with solution heat treatment.During heat treatment,the precipitatedβ-(Mg,Zn)_(3) Gd phase dissolved inα-Mg,and reduced the energy threshold of stacking faults on basal planes,which finally triggered the formation of long period stacking ordered(LPSO)phase.The LPSO phases owned minor potential difference withα-Mg,thus causing less micro-galvanic corrosion ten-dency as compared toβ-(Mg,Zn)_(3) Gd phase.More importantly,they were uniformly distributed within theα-Mg grains and showed different orientations between adjacent grains.As a result,the LPSO-reinforced Mg-Zn-Gd tended to expand laterally during corrosion evolution,and achieved uniform degradation with a considerably reduced degradation rate of 0.34 mm/year.Moreover,in-vitro cell tests further proved its favorable biocompatibility.This work highlighted the additively manufactured Mg-Zn-Gd with LPSO structure showed great potential for orthopedic application.展开更多
Biomedical magnesium(Mg)alloys have garnered significant attention because of their unique biodegradability,favorable biocompatibility,and suitable mechanical properties.The incorporation of rare earth(RE)elements,wit...Biomedical magnesium(Mg)alloys have garnered significant attention because of their unique biodegradability,favorable biocompatibility,and suitable mechanical properties.The incorporation of rare earth(RE)elements,with their distinct physical and chemical properties,has greatly contributed to enhancing the mechanical performance,degradation behavior,and biological performance of biomedical Mg alloys.Currently,a series of RE-Mg alloys are being designed and investigated for orthopedic implants and cardiovascular stents,achieving substantial and encouraging research progress.In this work,a comprehensive summary of the state-of-the-art in biomedical RE-Mg alloys is provided.The physiological effects and design standards of RE elements in biomedical Mg alloys are discussed.Particularly,the degradation behavior and mechanical properties,including their underlying action are studied in-depth.Furthermore,the preparation techniques and current application status of RE-Mg alloys are reviewed.Finally,we address the ongoing challenges and propose future prospects to guide the development of high-performance biomedical Mg-RE alloys.展开更多
Biomedical implants and devices for tissue engineering in clinics,mainly made of polymers and stiff metallic materials,require possibly secondary surgery or life-long medicine.Biodegradable metals for biomedical impla...Biomedical implants and devices for tissue engineering in clinics,mainly made of polymers and stiff metallic materials,require possibly secondary surgery or life-long medicine.Biodegradable metals for biomedical implants and devices exhibit huge potential to improve the prognosis of patients.In this work,we developed a new type of biodegradable binary zinc(Zn)alloys with 16 rare earth elements(REEs)including Sc,Y,La to Nd,and Sm to Lu,respectively.The effects of REEs on the alloy microstructure,mechanical properties,corrosion behavior and in vitro and in vivo biocompatibility of Zn were systematically investigated using pure Zn as control.All Zn-RE alloys generally exhibited improved mechanical properties,and biocompatibilities compared to pure Zn,especially the tensile strength and ductility of Zn-RE alloys were dramatically enhanced.Among the Zn-RE alloys,different REEs presented enhancement effects at varied extent.Y,Ho and Lu were the three elements displaying greatest improvements in majority of alloys properties,while Eu,Gd and Dy exhibited least improvement.Furthermore,the Zn-RE alloys were comparable with other Zn alloys and also exhibited superior properties to Mg-RE alloys.The in vivo experiment using Zn-La,Zn-Ce,and Zn-Nd alloys as tibia bone implants in rabbit demonstrated the excellent tissue biocompatibility and much more obvious osseointegration than the pure Zn control group.This work presented the significant potential of the developed Zn-RE binary alloys as novel degradable metal for biomedical implants and devices.展开更多
In the present study,a new biodegradable Mg-Zn-Cu magnesium alloy was introduced for biological applications.The microstructural analysis showed the formation of Mg Zn Cu intermetallics for the Mg-2Zn-0.1Cu alloy and ...In the present study,a new biodegradable Mg-Zn-Cu magnesium alloy was introduced for biological applications.The microstructural analysis showed the formation of Mg Zn Cu intermetallics for the Mg-2Zn-0.1Cu alloy and also the Mg(Zn,Cu);compounds for the Mg-2 Zn alloys with higher Cu contents.Moreover,the hot extrusion was applied for the grain refinement and changing the distribution of intermetallics.In vitro immersion tests,electrochemical and corroded surface analyses represented the enhancement of corrosion resistance with 0.1 wt.%Cu addition.Furthermore,the extruded alloys demonstrated more corrosion resistance behavior than that of the cast alloys.By considering the improved tensile properties of Mg-2Zn-0.1Cu alloy,this alloy was regarded as the potential candidate for use as the biodegradable magnesium implant.展开更多
Considering the serious barriers/issues induced by the accumulated starch generated in white water system of old corrugated cardboard(OCC)pulping process,large amounts of accumulated starch in white water would be dec...Considering the serious barriers/issues induced by the accumulated starch generated in white water system of old corrugated cardboard(OCC)pulping process,large amounts of accumulated starch in white water would be decomposed by microorganisms and could not be utilized,thereby resulting in severe resource wastage and environmental pollution.This study mainly explored the effects of biodegradation/hydrolysis conditions of the two types of starch substrates(native starch and enzymatically(α-amylase)hydrolyzed starch),which were treated via microorganism degradation within the simulated white water from OCC pulping system and their biodegradation products on the key properties were characterized via X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),and gel permeation chromatography(GPC)technologies.The effects of system temperature,pH value,starch concentration,and biodegradation time on starch biodegradation ratio and the characteristics of obtained biodegradated products from the two types of starches were studied.In addition,the effect ofα-amylase dosage on the biodegradation ratio of enzymatically hydrolyzed starch and its properties was investigated.It was found that the native starch presented a maximal degradation ratio at a system temperature of 55℃and pH value range of 5-7,respectively,the corresponding starch concentration within simulated white water system was 200 mg/L.Whereas the enzymatically hydrolyzed starch exhibited a highest degradation ratio at a system temperature of 50℃and pH value of 5.5,respectively,and the corresponding starch concentration within simulated white water system was 100 mg/L.It was verified that native starch is more readily bio-hydrolyzed and biodegradation-susceptive by microorganisms in simulated white water system of OCC pulping process,while the enzymatically hydrolyzed starch exhibits better biodegradation/hydrolysis resistance to the microbial degradation than that of native starch.This study provides a practical and interesting approach to inves展开更多
基金supported by the following funds:National Natural Science Foundation of China(51935014,52165043)Jiangxi Provincial Cultivation Program for Academic and Technical Leaders of Major Subjects(20225BCJ23008)+1 种基金Jiangxi Provincial Natural Science Foundation(20224ACB204013,20224ACB214008)Scientific Research Project of Anhui Universities(KJ2021A1106)。
文摘Magnesium(Mg)alloys are considered to be a new generation of revolutionary medical metals.Laser-beam powder bed fusion(PBF-LB)is suitable for fabricating metal implants withpersonalized and complicated structures.However,the as-built part usually exhibits undesirable microstructure and unsatisfactory performance.In this work,WE43 parts were firstly fabricated by PBF-LB and then subjected to heat treatment.Although a high densification rate of 99.91%was achieved using suitable processes,the as-built parts exhibited anisotropic and layeredmicrostructure with heterogeneously precipitated Nd-rich intermetallic.After heat treatment,fine and nano-scaled Mg24Y5particles were precipitated.Meanwhile,theα-Mg grainsunderwent recrystallization and turned coarsened slightly,which effectively weakened thetexture intensity and reduced the anisotropy.As a consequence,the yield strength and ultimate tensile strength were significantly improved to(250.2±3.5)MPa and(312±3.7)MPa,respectively,while the elongation was still maintained at a high level of 15.2%.Furthermore,the homogenized microstructure reduced the tendency of localized corrosion and favoredthe development of uniform passivation film.Thus,the degradation rate of WE43 parts was decreased by an order of magnitude.Besides,in-vitro cell experiments proved their favorable biocompatibility.
基金National Natural Science Foundation of China (Nos.51935014,52165043,82072084)JiangXi Provincial Natural Science Foundation of China (No.20212BAB214026)Jiangsu Provincial Key Research and Development Program (No.BE2019002).
文摘Biodegradable magnesium(Mg)alloy has been considered as a new generation of orthopedic implant ma-terial.Nevertheless,local corrosion usually occurs since the severe micro-galvanic behavior amongα-Mg and precipitates,and results in too rapid degradation.In this study,porous Mg-Zn-Gd part was fabricated using laser additive manufacturing combined with solution heat treatment.During heat treatment,the precipitatedβ-(Mg,Zn)_(3) Gd phase dissolved inα-Mg,and reduced the energy threshold of stacking faults on basal planes,which finally triggered the formation of long period stacking ordered(LPSO)phase.The LPSO phases owned minor potential difference withα-Mg,thus causing less micro-galvanic corrosion ten-dency as compared toβ-(Mg,Zn)_(3) Gd phase.More importantly,they were uniformly distributed within theα-Mg grains and showed different orientations between adjacent grains.As a result,the LPSO-reinforced Mg-Zn-Gd tended to expand laterally during corrosion evolution,and achieved uniform degradation with a considerably reduced degradation rate of 0.34 mm/year.Moreover,in-vitro cell tests further proved its favorable biocompatibility.This work highlighted the additively manufactured Mg-Zn-Gd with LPSO structure showed great potential for orthopedic application.
基金supported by National Key Research and Development Program of China[2023YFB4605800]National Natural Science Foundation of China[51935014,52165043]+3 种基金JiangXi Provincial Natural Science Foundation of China[20224ACB204013,20224ACB214008]Jiangxi Provincial Cultivation Program for Academic and Technical Leaders of Major Subjects[20225BCJ23008]Anhui Provincial Natural Science Foundation[2308085ME171]The University Synergy Innovation Program of Anhui Province[GXXT-2023-025,GXXT-2023-026].
文摘Biomedical magnesium(Mg)alloys have garnered significant attention because of their unique biodegradability,favorable biocompatibility,and suitable mechanical properties.The incorporation of rare earth(RE)elements,with their distinct physical and chemical properties,has greatly contributed to enhancing the mechanical performance,degradation behavior,and biological performance of biomedical Mg alloys.Currently,a series of RE-Mg alloys are being designed and investigated for orthopedic implants and cardiovascular stents,achieving substantial and encouraging research progress.In this work,a comprehensive summary of the state-of-the-art in biomedical RE-Mg alloys is provided.The physiological effects and design standards of RE elements in biomedical Mg alloys are discussed.Particularly,the degradation behavior and mechanical properties,including their underlying action are studied in-depth.Furthermore,the preparation techniques and current application status of RE-Mg alloys are reviewed.Finally,we address the ongoing challenges and propose future prospects to guide the development of high-performance biomedical Mg-RE alloys.
基金supported by the National Key R&D Program of China[2018YFE0104200]the National Natural Science Foundation of China[51931001,52171233,52271243,U22A20121]+2 种基金the INTERNATIONAL COOPERATION and Exchange project of NSFC-RFBR[52111530042]the Beijing Natural Science Foundation[L212014]the Beijing Nova Program.
文摘Biomedical implants and devices for tissue engineering in clinics,mainly made of polymers and stiff metallic materials,require possibly secondary surgery or life-long medicine.Biodegradable metals for biomedical implants and devices exhibit huge potential to improve the prognosis of patients.In this work,we developed a new type of biodegradable binary zinc(Zn)alloys with 16 rare earth elements(REEs)including Sc,Y,La to Nd,and Sm to Lu,respectively.The effects of REEs on the alloy microstructure,mechanical properties,corrosion behavior and in vitro and in vivo biocompatibility of Zn were systematically investigated using pure Zn as control.All Zn-RE alloys generally exhibited improved mechanical properties,and biocompatibilities compared to pure Zn,especially the tensile strength and ductility of Zn-RE alloys were dramatically enhanced.Among the Zn-RE alloys,different REEs presented enhancement effects at varied extent.Y,Ho and Lu were the three elements displaying greatest improvements in majority of alloys properties,while Eu,Gd and Dy exhibited least improvement.Furthermore,the Zn-RE alloys were comparable with other Zn alloys and also exhibited superior properties to Mg-RE alloys.The in vivo experiment using Zn-La,Zn-Ce,and Zn-Nd alloys as tibia bone implants in rabbit demonstrated the excellent tissue biocompatibility and much more obvious osseointegration than the pure Zn control group.This work presented the significant potential of the developed Zn-RE binary alloys as novel degradable metal for biomedical implants and devices.
文摘In the present study,a new biodegradable Mg-Zn-Cu magnesium alloy was introduced for biological applications.The microstructural analysis showed the formation of Mg Zn Cu intermetallics for the Mg-2Zn-0.1Cu alloy and also the Mg(Zn,Cu);compounds for the Mg-2 Zn alloys with higher Cu contents.Moreover,the hot extrusion was applied for the grain refinement and changing the distribution of intermetallics.In vitro immersion tests,electrochemical and corroded surface analyses represented the enhancement of corrosion resistance with 0.1 wt.%Cu addition.Furthermore,the extruded alloys demonstrated more corrosion resistance behavior than that of the cast alloys.By considering the improved tensile properties of Mg-2Zn-0.1Cu alloy,this alloy was regarded as the potential candidate for use as the biodegradable magnesium implant.
基金financial support from the China Postdoctoral Science Foundation (No. 2022M712379, No. 2021M692401)National Natural Science Foundation of China (No. 32101470)+3 种基金Foundation (No. 2021KF37) of Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control,College of Light Industry and Food Engineering, Guangxi UniversityFoundation of Tianjin Key Laboratory of Pulp & Paper of Tianjin University of Science & Technology (No. 202003, No. 202106)Research Foundation from the University of New BrunswickPost-Doctoral Fellow Programs from Zhejiang Jingxing Paper Co., Ltd
文摘Considering the serious barriers/issues induced by the accumulated starch generated in white water system of old corrugated cardboard(OCC)pulping process,large amounts of accumulated starch in white water would be decomposed by microorganisms and could not be utilized,thereby resulting in severe resource wastage and environmental pollution.This study mainly explored the effects of biodegradation/hydrolysis conditions of the two types of starch substrates(native starch and enzymatically(α-amylase)hydrolyzed starch),which were treated via microorganism degradation within the simulated white water from OCC pulping system and their biodegradation products on the key properties were characterized via X-ray diffraction(XRD),Fourier-transform infrared spectroscopy(FT-IR),and gel permeation chromatography(GPC)technologies.The effects of system temperature,pH value,starch concentration,and biodegradation time on starch biodegradation ratio and the characteristics of obtained biodegradated products from the two types of starches were studied.In addition,the effect ofα-amylase dosage on the biodegradation ratio of enzymatically hydrolyzed starch and its properties was investigated.It was found that the native starch presented a maximal degradation ratio at a system temperature of 55℃and pH value range of 5-7,respectively,the corresponding starch concentration within simulated white water system was 200 mg/L.Whereas the enzymatically hydrolyzed starch exhibited a highest degradation ratio at a system temperature of 50℃and pH value of 5.5,respectively,and the corresponding starch concentration within simulated white water system was 100 mg/L.It was verified that native starch is more readily bio-hydrolyzed and biodegradation-susceptive by microorganisms in simulated white water system of OCC pulping process,while the enzymatically hydrolyzed starch exhibits better biodegradation/hydrolysis resistance to the microbial degradation than that of native starch.This study provides a practical and interesting approach to inves
