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
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
Magnetron sputtering deposition with regulated Cu target power was used for depositing Cu-containing high-entropy alloy nitride(Cu-(HEA)N)films on TC4 titanium alloy substrates.The microscopic morphologies,surface com...Magnetron sputtering deposition with regulated Cu target power was used for depositing Cu-containing high-entropy alloy nitride(Cu-(HEA)N)films on TC4 titanium alloy substrates.The microscopic morphologies,surface compositions,and thicknesses of the films were characterized using SEM+EDS;the anti-corrosion,wear resistance and antibacterial properties of the films in simulated seawater were investigated.The experimental results show that all four Cu-(HEA)N films are uniformly dense and contained nanoparticles.The film with Cu doping come into contact with oxygen in the air to form cuprous oxide.The corrosion resistance of the(HEA)N film without Cu doping on titanium alloy is better than the films with Cu doping.The Cu-(HEA)N film with Cu target power of 16 W shows the best wear resistance and antibacterial performance,which is attributed to the fact that Cu can reduce the coefficient of friction and exacerbate corrosion,and the formation of cuprous oxide has antibacterial properties.The findings of this study provide insights for engineering applications of TC4 in the marine field.展开更多
Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect ...Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect in vivo. A bioactive chemical conversion Mg-phenolic networks complex coating(e EGCG) was stepwise incorporated by epigallocatechin-3-gallate(EGCG) and exogenous Mg^(2+)on Mg-2Zn magnesium alloy. Simplex EGCG induced chemical conversion coating(c EGCG) was set as compare group. The in vitro corrosion behavior of Mg-2Zn alloy, c EGCG and e EGCG was evaluated in SBF using electrochemical(PDP, EIS) and immersion test. The cytocompatibility was investigated with rat bone marrow mesenchymal stem cells(r BMSCs). Furthermore, the in vivo tests using a rabbit model involved micro computed tomography(Micro-CT) analysis, histological observation, and interface analysis. The results showed that the e EGCG is Mgphenolic multilayer coating incorporated Mg-phenolic networks, which is rougher, more compact and much thicker than c EGCG. The e EGCG highly improved the corrosion resistance of Mg-2Zn alloy, combined with its lower average hemolytic ratios, continuous high scavenging effect ability and relatively moderate contact angle features, resulting in a stable and suitable biological environment, obviously promoted r BMSCs adhesion and proliferation. More importantly, Micro-CT, histological and interface elements distribution evaluations all revealed that the e EGCG effectively inhibited degradation and enhanced bone tissue formation of Mg alloy implants. This study puts forward a promising bioactive chemical conversion coating with Mg-phenolic networks for the application of biodegradable orthopedic implants.展开更多
The role of α precipitates formed during aging in the fracture toughness and fracture behavior of β-type bio-titanium alloy Ti–29Nb–13Ta–4.6Zr(TNTZ) was studied. Results showed that the fracture toughness of the ...The role of α precipitates formed during aging in the fracture toughness and fracture behavior of β-type bio-titanium alloy Ti–29Nb–13Ta–4.6Zr(TNTZ) was studied. Results showed that the fracture toughness of the TNTZ alloy aged at 723 K decreases to the minimum of 72.07–73.19 kJ·m^(-2)when the aging time is extended to 4–8 h and then gradually increases and reaches 144.89 kJ·m^(-2)after 72 h. The decrease in fracture toughness within the aging time of 4–8 h is caused by the large stress concentration at the tip of acicular α precipitates with a high aspect ratio and the preferential crack propagation along the inhomogeneous acicular α precipitates distributed in “V-shape” and “nearly perpendicular shape”. When the aging time is extended to 8–72 h, the precrack tip is uniformly blunted, and the crack is effectively deflected by α precipitates with multi long axis directions, more high homogeneity, low aspect ratio, and large number density. Analysis of the effect of αprecipitates on the fracture behavior suggested that the number of long axis directions of α precipitates is the key controlling factor for the fracture behavior and fracture toughness of the TNTZ alloy aged for different times.展开更多
To study the relationship between the microstructure and tensile properties of the novel metastable β titanium alloy Ti-5.5Cr-5Al-4Mo-3Nb-2Zr,a heat treatment process of ABFCA(solid solution in α+βregion with subse...To study the relationship between the microstructure and tensile properties of the novel metastable β titanium alloy Ti-5.5Cr-5Al-4Mo-3Nb-2Zr,a heat treatment process of ABFCA(solid solution in α+βregion with subsequent furnace cooling followed by aging treatment finally)was designed,by which α phases of different sizes can be precipitated in the β matrix.The results show that the microstructure obtained by this heat treatment process is composed of primary α(α_(p))phase,submicro rod-like α(α_(r))phase and secondary α(α_(s))phase.The alloy with multi-scale α phase has an excellent balance between strength and ductility.The elongation is about 18.3% at the ultimate tensile strength of 1125.4 MPa.The relationship between the strength of the alloy and the α phase was established.The strength of the alloy is proportional to the power of‒1/2 of the average spacing and width of α phase.The α_(s) phase with a smaller size and phase spacing can greatly improve the strength of the alloy by hindering dislocation slip.The transmission electron microscope analysis shows that there is a large amount of dislocation accumulation at the α/β interfaces,and many deformation twins are found in the α_(p) phase after tensile deformation.When the dislocation slip is hindered,twins occur at the stress concentration location,and twins can initiate some dislocations that are difficult to slip.Meanwhile,the plastic strain is distributed uniformly among the α_(p),α_(r),α_(s) phases and β matrix,thereby enhancing the ductility of the alloy.展开更多
Binary titanium–niobium(Ti–Nb)alloys have recently been attracted due to low Young’s moduli and non-toxic properties.This study explores the influence of low Nb content(0–25 wt%)on the comprehensive parameters of ...Binary titanium–niobium(Ti–Nb)alloys have recently been attracted due to low Young’s moduli and non-toxic properties.This study explores the influence of low Nb content(0–25 wt%)on the comprehensive parameters of tensile stress–strain relationships(ultimate strength(rUTS),yield strength(r0.2)and elastic modulus(E)),surfaces properties(Vickers microhardness,surface roughness(Ra),water contact angle(WCA),X-ray diffraction(XRD)and scanning electron microscopy(SEM)),corrosion resistance(in artificial saliva and lactic acid)and biological properties(cytotoxicity and alkaline phosphatase activity of MC3T3-E1 pre-osteoblasts)of Ti–xNb alloys(x紏5,10,15,20 and 25 wt%),with using commercially pure grade 2 titanium(cp-Ti)as control.XRD results shown that all the Ti–xNb alloys comprised atb Ti alloy phases,such that the b phase increased correspondingly with the increased amount of Nb in the alloy,as well as the reduction of E(69–87 GPa).Except Ti–5Nb,all other Ti–xNb alloys showed a significantly higher hardness,increased rUTS and r0.2,and decreased WCA compared with cp-Ti.No corrosion was detected on Ti–xNb alloys and cp-Ti in artificial saliva and lactic acid solutions.The cytotoxicity of Ti–xNb alloys was comparable to that of cp-Ti in MC3T3-E1 pre-osteoblasts without interference from differentiation behaviour,but the proliferation rate of the Ti–5Nb alloy was lower than other groups.In overall,binary Ti–(10–25 wt%)Nb alloys are promising candidate for orthopaedic and dental implants due to their improved mechanical properties and comparable biological performance,while Ti–5Nb should be used with caution.展开更多
Attaining a highly efficient and inexpensive electrocatalyst is significant for the hydrogen evolution reaction(HER)but still challenging nowadays.The transition-metal phosphides(TMPs)catalysts with platinum-like elec...Attaining a highly efficient and inexpensive electrocatalyst is significant for the hydrogen evolution reaction(HER)but still challenging nowadays.The transition-metal phosphides(TMPs)catalysts with platinum-like electronic structures are a potential candidate for the HER,but those are prone to be strongly bound with hydrogen intermediates(H∗),resulting in sluggish HER kinetics.Herein we report a unique hybrid structure of CoP anchored on graphene nanoscrolls@carbon nano tubes(CNTs)scaffold(Ni M@C-CoP)encapsulating various Ni M(M=Zn,Mo,Ni,Co)bimetal nanoalloy via chemical vapor deposi-tion(CVD)growth of CNT on graphene nanoscrolls followed by the impregnation of cobalt precursors and phosphorization for efficiently electrocatalytic hydrogen evolution.CoP nanoparticles mainly scattered at the tip of CNT branches which exhibited the analogical“Three-layer core-shell”structures.Experiments and density functional theory(DFT)calculations consistently disclose that the encapsulated various NiMs can offer different numbers of electrons to weaken the interactions of outmost CoP with H∗and push the downshift of the d-band center to different degrees as well as stabilize the outmost CoP nanopar-ticles to gain catalytic stability via the electron traversing effect.The electrocatalytic HER activity can be maximumly enhanced with low overpotentials of 78 mV(alkaline)and 89 mV(acidic)at a current density of 10 mA/cm^(2) and sustained at least 24 h especially for NiZn@C-CoP catalyst.This novel system is distinct from conventional three-layer heterostructure,providing a specially thought of d-band center control engineering strategy for the design of heterogeneous catalysts and expanding to other electrocat-alysts,energy storage,sensing,and other applications.展开更多
Owing to its designability and intrinsic fluorescence,non-conjugated hyperbranched polysiloxane(HBPSi)has attracted widespread attention in biological filed,while it is still severely restricted by low fluorescence ef...Owing to its designability and intrinsic fluorescence,non-conjugated hyperbranched polysiloxane(HBPSi)has attracted widespread attention in biological filed,while it is still severely restricted by low fluorescence efficiency.So,in this paper,we introduced disulfide into HBPSi improving their luminescence properties and synthesized different molecular weight HBPSi(P1,P2,and P3).Surprisingly,P1 exhibited ultrahigh quantum yield up to 47.81%.Meanwhile,experiments applied with theoretical calculations were employed to explore the fluorescence mechanism,which is attributed to efficient restricting of non-radiative decay by clusteroluminogens formed with the cooperation of hyperbranched structure and double hydrogen bonding.In addition,the biocompatibility of P1 was verified by co-culture with MC3T3-E1 and P1 lighted up mouse fibroblast cells without fluorescent dyes.This work designed a novel fluorescent polymer with ultrahigh fluorescence quantum yield and cell imaging ability,which is promising in visualization diagnosis and treatment of tumor.展开更多
Infected bone defect is a formidable clinical challenge.Conventional approaches to prevention and treatment for infected bone defects are unsatisfactory.The key elements of the treatment are bone defect reconstruction...Infected bone defect is a formidable clinical challenge.Conventional approaches to prevention and treatment for infected bone defects are unsatisfactory.The key elements of the treatment are bone defect reconstruction,antiinfection,and osteogenesis.Conventional treatment methods remain unsatisfactory owing to the absence of composite integrating materials with anti-infective,and osteogenic activities as well as proper mechanical strength at the same time.In this study,we fabricated a vancomycin-encapsulated hydrogel with bacteriaresponsive release properties combined with a shaved porous(submicron-micron)three-dimensional-printed Ti6Al4V implant.The implant surface,modified with submicron-sized pores through microarc oxidation(MAO),showed enhanced osteogenic activity and integrated well with the hydrogel drug release system,enabling sustained vancomycin release.In vitro experiments underscored the commendable antibacterial ability,biosafety,and osteoinductive potential.Effective antibacterial and osteogenic abilities of the implant were further demonstrated in vivo in infected rabbit bone defects.These results showed that the vancomycinencapsulated hydrogel-loaded microarc-oxidized 3D-printed porous Ti6Al4V can repair the infected bone defects with satisfactory anti-infection and osseointegration effects.展开更多
The gradient porous Ti3Zr2Sn3Mo25Nb(TLM)alloy rods were fabricated through sintering the alloyed powder to a solid core.The porous sample was then modified by a Micro Arc Oxidation(MAO)treatment in an electrolyte cont...The gradient porous Ti3Zr2Sn3Mo25Nb(TLM)alloy rods were fabricated through sintering the alloyed powder to a solid core.The porous sample was then modified by a Micro Arc Oxidation(MAO)treatment in an electrolyte containing calcium and phosphate,a hydrothermal treatment enabled secondary microporous hydroxyapatite(HA)coating,and a further bone morphogenetic protein-2(BMP-2)loading treatment through immersion and freeze-drying.The treatment led to an orderly secondary microporous coating containing HA nano-particles and evenly distributed BMP-2 in the porous coatings.As a result,osteoblasts could adhere and grow well on the coatings with a high cell adhesion rate and cell functional activity.The in-situ shear testing indicated that the interfacial strength had been enhanced significantly.Improvement of the bond formation and osseointegration with the titanium implant is attributed to increased surface area for the cell to attach,creating voids for the cell to grow in,and activating titanium surface by introducing bioactive ingredients such as HA and BMP-2.展开更多
Hydroxyapatite(HA)synthesized by a wet chemical route was subjected to heavy ion irradiation,using4 Me V Krypton ion(Kr17+)with ion fluence ranging from 1×1013 to 1×1015 ions/cm2.Glancing incidence X-ray dif...Hydroxyapatite(HA)synthesized by a wet chemical route was subjected to heavy ion irradiation,using4 Me V Krypton ion(Kr17+)with ion fluence ranging from 1×1013 to 1×1015 ions/cm2.Glancing incidence X-ray diffraction(GIXRD)results confirmed the phase purity of irradiated HA with a moderate contraction in lattice parameters,and further indicated the irradiation-induced structural disorder,evidenced by broadening of the diffraction peaks.High-resolution transmission electron microscopy(HRTEM)observations indicated that the applied Kr irradiation induced significant damage in the hydroxyapatite lattice.Specifically,cavities were observed with their diameter and density varying with the irradiation fluences,while a radiation-induced crystalline-to-amorphous transition with increasing ion dose was identified.Raman and X-ray photoelectron spectroscopy(XPS)analysis further indicated the presence of irradiationinduced defects.Ion release from pristine and irradiated materials following immersion in Tris(p H 7.4,37?)buffer showed that dissolution in vitro was enhanced by irradiation,reaching a peak at 0.1 dpa.We examined the effects of irradiation on the early stages of the mouse osteoblast-like cells(MC3 T3-E)response.A cell counting kit-8 assay(CCK-8 test)was carried out to investigate the cytotoxicity of samples,and viable cells can be observed on the irradiated materials.展开更多
Endowing implant surfaces with combined antibacterial and osteogenic properties by drug-loaded coatings has made great strides,but how to achieve the combined excellence of infection-triggered bactericidal and in vivo...Endowing implant surfaces with combined antibacterial and osteogenic properties by drug-loaded coatings has made great strides,but how to achieve the combined excellence of infection-triggered bactericidal and in vivo-proven osteogenic activities without causing bacterial resistance still remains a formidable challenge.Herein,antimicrobial peptides(AMPs)with osteogenic fragments were designed and complexed on the surface of silver nanoparticle(AgNP)through hydrogen bonding,and the collagen structure-bionic silk fibroin(SF)was applied to carry AgNPs@AMPs to achieve infection-triggered antibacterial and osteointegration.As verified by TEM,AMPs contributed to the dispersion and size-regulation of AgNPs,with a particle size of about 20 nm,and a clear protein corona structure was observed on the particle surface.The release curve of silver ion displayed that the SF-based coating owned sensitive pH-responsive properties.In the antibacterial test against S.aureus for up to 21 days,the antibacterial rate had always remained above 99%.Meanwhile,the underlying mechanism was revealed,originating from the destruction of the bacterial cell membranes and ROS generation.The SF-based coating was conducive to the adhesion,diffusion,and proliferation of bone marrow stem cells(BMSCs)on the surface,and promoted the expression of osteogenic genes and collagen secretion.The in vivo implantation results showed that compared with the untreated Ti implants,SF-based coating enhanced osseointegration at week 4 and 8.Overall,the AgNPs@AMPs-loaded SF-based coating presented the ability to synergistically inhibit bacteria and promote osseointegration,possessing tremendous potential application prospects in bone defects and related-infection treatments.展开更多
Selective endovascular hypothermia has been used to provide cooling-induced cerebral neuroprotection,but current catheters do not support thermally-insulated transfer of cold infusate,which results in an increased exi...Selective endovascular hypothermia has been used to provide cooling-induced cerebral neuroprotection,but current catheters do not support thermally-insulated transfer of cold infusate,which results in an increased exit temperature,causes hemodilution,and limits its cooling efficiency.Herein,air-sprayed fibroin/silica-based coatings combined with chemical vapor deposited parylene-C capping film was prepared on catheter.This coating features in dual-sized-hollow-microparticle incorporated structures with low thermal conductivity.The infusate exit temperature is tunable by adjusting the coating thickness and infusion rate.No peeling or cracking was observed on the coatings under bending and rotational scenarios in the vascular models.Its efficiency was verified in a swine model,and the outlet temperature of coated catheter(75μm thickness)was 1.8-2.0◦C lower than that of the uncoated one.This pioneering work on catheter thermal insulation coatings may facilitate the clinical translation of selective endovascular hypothermia for neuroprotection in patients with acute ischemic stroke.展开更多
1.Introduction In structural metallic materials,the occurrence of particular deformation mechanisms such as dislocation slip,deformation twins(DTs)[1,2]deformation kink bands(KBs)[3,4]or stressinduced phase transforma...1.Introduction In structural metallic materials,the occurrence of particular deformation mechanisms such as dislocation slip,deformation twins(DTs)[1,2]deformation kink bands(KBs)[3,4]or stressinduced phase transformations(SIM)[5],are closely related to both their crystal structures[6–8](e.g.FCC,BCC and HCP)and loading conditions(e.g.temperature and/or strain rate).展开更多
The deformation mode of{332}<113>twinning(hereafter called 332T)has often been observed under the plastic flow in metastableβtitanium alloys with body-centered cubic(BCC)structure,which contributes to improving...The deformation mode of{332}<113>twinning(hereafter called 332T)has often been observed under the plastic flow in metastableβtitanium alloys with body-centered cubic(BCC)structure,which contributes to improving the mechanical performance.Herein,we report a structure of compressive deformation-induced primary 332T with hierarchical and/or heterogeneous composite sub-structure in a Twin-Induced Plasticity(TWIP)βTi-alloy under uniaxial compression.The detailed structural characterization after compressive deformation revealed that the sub-structure,including secondary 332T and secondary{112}<111>twinning,formed inside the 332T structure,which constitutes a hierarchical and/or heterogeneous structure at micro-and nano-scale and consequently contributes to the high strength,large ductility and enhanced strain-hardening behavior.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Funded by the National Natural Science Foundation of China(No.52071252)the Key Research and Development Plan of Shaanxi Province Industrial Project(Nos.2021GY-208,2022GY-407,and 2021ZDLSF03-11)the China Postdoctoral Science Foundation(No.2020M683670XB)。
文摘Magnetron sputtering deposition with regulated Cu target power was used for depositing Cu-containing high-entropy alloy nitride(Cu-(HEA)N)films on TC4 titanium alloy substrates.The microscopic morphologies,surface compositions,and thicknesses of the films were characterized using SEM+EDS;the anti-corrosion,wear resistance and antibacterial properties of the films in simulated seawater were investigated.The experimental results show that all four Cu-(HEA)N films are uniformly dense and contained nanoparticles.The film with Cu doping come into contact with oxygen in the air to form cuprous oxide.The corrosion resistance of the(HEA)N film without Cu doping on titanium alloy is better than the films with Cu doping.The Cu-(HEA)N film with Cu target power of 16 W shows the best wear resistance and antibacterial performance,which is attributed to the fact that Cu can reduce the coefficient of friction and exacerbate corrosion,and the formation of cuprous oxide has antibacterial properties.The findings of this study provide insights for engineering applications of TC4 in the marine field.
基金supported by the Key Research and Development Program of Shaanxi Province (2019ZDLSF03-06) and (2020ZDLGY13-05)the National Key Research and Development Program of China (2020YFC1107202)。
文摘Magnesium(Mg) and its alloys have been intensively studied to develop the next generation of bone implants recently, but their clinical application is restricted by rapid degradation and unsatisfied osteogenic effect in vivo. A bioactive chemical conversion Mg-phenolic networks complex coating(e EGCG) was stepwise incorporated by epigallocatechin-3-gallate(EGCG) and exogenous Mg^(2+)on Mg-2Zn magnesium alloy. Simplex EGCG induced chemical conversion coating(c EGCG) was set as compare group. The in vitro corrosion behavior of Mg-2Zn alloy, c EGCG and e EGCG was evaluated in SBF using electrochemical(PDP, EIS) and immersion test. The cytocompatibility was investigated with rat bone marrow mesenchymal stem cells(r BMSCs). Furthermore, the in vivo tests using a rabbit model involved micro computed tomography(Micro-CT) analysis, histological observation, and interface analysis. The results showed that the e EGCG is Mgphenolic multilayer coating incorporated Mg-phenolic networks, which is rougher, more compact and much thicker than c EGCG. The e EGCG highly improved the corrosion resistance of Mg-2Zn alloy, combined with its lower average hemolytic ratios, continuous high scavenging effect ability and relatively moderate contact angle features, resulting in a stable and suitable biological environment, obviously promoted r BMSCs adhesion and proliferation. More importantly, Micro-CT, histological and interface elements distribution evaluations all revealed that the e EGCG effectively inhibited degradation and enhanced bone tissue formation of Mg alloy implants. This study puts forward a promising bioactive chemical conversion coating with Mg-phenolic networks for the application of biodegradable orthopedic implants.
基金financially supported by the Natural Science Foundation of Liaoning Province,China (No.2022-MS-113)the Major technology projects of Liaoning Province,China (No.2019JH1/10100004)+1 种基金the National Natural Science Foundation of China (No.52271249)the Key Research and Development Program of Shaanxi,China(No.2023-YBGY-488)。
文摘The role of α precipitates formed during aging in the fracture toughness and fracture behavior of β-type bio-titanium alloy Ti–29Nb–13Ta–4.6Zr(TNTZ) was studied. Results showed that the fracture toughness of the TNTZ alloy aged at 723 K decreases to the minimum of 72.07–73.19 kJ·m^(-2)when the aging time is extended to 4–8 h and then gradually increases and reaches 144.89 kJ·m^(-2)after 72 h. The decrease in fracture toughness within the aging time of 4–8 h is caused by the large stress concentration at the tip of acicular α precipitates with a high aspect ratio and the preferential crack propagation along the inhomogeneous acicular α precipitates distributed in “V-shape” and “nearly perpendicular shape”. When the aging time is extended to 8–72 h, the precrack tip is uniformly blunted, and the crack is effectively deflected by α precipitates with multi long axis directions, more high homogeneity, low aspect ratio, and large number density. Analysis of the effect of αprecipitates on the fracture behavior suggested that the number of long axis directions of α precipitates is the key controlling factor for the fracture behavior and fracture toughness of the TNTZ alloy aged for different times.
基金National Natural Science Foundation of China(52104379,U21A20117,52071219,52271249)。
文摘To study the relationship between the microstructure and tensile properties of the novel metastable β titanium alloy Ti-5.5Cr-5Al-4Mo-3Nb-2Zr,a heat treatment process of ABFCA(solid solution in α+βregion with subsequent furnace cooling followed by aging treatment finally)was designed,by which α phases of different sizes can be precipitated in the β matrix.The results show that the microstructure obtained by this heat treatment process is composed of primary α(α_(p))phase,submicro rod-like α(α_(r))phase and secondary α(α_(s))phase.The alloy with multi-scale α phase has an excellent balance between strength and ductility.The elongation is about 18.3% at the ultimate tensile strength of 1125.4 MPa.The relationship between the strength of the alloy and the α phase was established.The strength of the alloy is proportional to the power of‒1/2 of the average spacing and width of α phase.The α_(s) phase with a smaller size and phase spacing can greatly improve the strength of the alloy by hindering dislocation slip.The transmission electron microscope analysis shows that there is a large amount of dislocation accumulation at the α/β interfaces,and many deformation twins are found in the α_(p) phase after tensile deformation.When the dislocation slip is hindered,twins occur at the stress concentration location,and twins can initiate some dislocations that are difficult to slip.Meanwhile,the plastic strain is distributed uniformly among the α_(p),α_(r),α_(s) phases and β matrix,thereby enhancing the ductility of the alloy.
基金The study was partially supported by the National Natural Science Foundation of China(NSFC)(grant number 81771126).
文摘Binary titanium–niobium(Ti–Nb)alloys have recently been attracted due to low Young’s moduli and non-toxic properties.This study explores the influence of low Nb content(0–25 wt%)on the comprehensive parameters of tensile stress–strain relationships(ultimate strength(rUTS),yield strength(r0.2)and elastic modulus(E)),surfaces properties(Vickers microhardness,surface roughness(Ra),water contact angle(WCA),X-ray diffraction(XRD)and scanning electron microscopy(SEM)),corrosion resistance(in artificial saliva and lactic acid)and biological properties(cytotoxicity and alkaline phosphatase activity of MC3T3-E1 pre-osteoblasts)of Ti–xNb alloys(x紏5,10,15,20 and 25 wt%),with using commercially pure grade 2 titanium(cp-Ti)as control.XRD results shown that all the Ti–xNb alloys comprised atb Ti alloy phases,such that the b phase increased correspondingly with the increased amount of Nb in the alloy,as well as the reduction of E(69–87 GPa).Except Ti–5Nb,all other Ti–xNb alloys showed a significantly higher hardness,increased rUTS and r0.2,and decreased WCA compared with cp-Ti.No corrosion was detected on Ti–xNb alloys and cp-Ti in artificial saliva and lactic acid solutions.The cytotoxicity of Ti–xNb alloys was comparable to that of cp-Ti in MC3T3-E1 pre-osteoblasts without interference from differentiation behaviour,but the proliferation rate of the Ti–5Nb alloy was lower than other groups.In overall,binary Ti–(10–25 wt%)Nb alloys are promising candidate for orthopaedic and dental implants due to their improved mechanical properties and comparable biological performance,while Ti–5Nb should be used with caution.
基金This work was supported by the Science and Technology Pro-gram of Shaanxi Province(No.2019GY-200).Shengwu Guo and Wei Wang contributed to the material TEM and SEM characterizations in this work.
文摘Attaining a highly efficient and inexpensive electrocatalyst is significant for the hydrogen evolution reaction(HER)but still challenging nowadays.The transition-metal phosphides(TMPs)catalysts with platinum-like electronic structures are a potential candidate for the HER,but those are prone to be strongly bound with hydrogen intermediates(H∗),resulting in sluggish HER kinetics.Herein we report a unique hybrid structure of CoP anchored on graphene nanoscrolls@carbon nano tubes(CNTs)scaffold(Ni M@C-CoP)encapsulating various Ni M(M=Zn,Mo,Ni,Co)bimetal nanoalloy via chemical vapor deposi-tion(CVD)growth of CNT on graphene nanoscrolls followed by the impregnation of cobalt precursors and phosphorization for efficiently electrocatalytic hydrogen evolution.CoP nanoparticles mainly scattered at the tip of CNT branches which exhibited the analogical“Three-layer core-shell”structures.Experiments and density functional theory(DFT)calculations consistently disclose that the encapsulated various NiMs can offer different numbers of electrons to weaken the interactions of outmost CoP with H∗and push the downshift of the d-band center to different degrees as well as stabilize the outmost CoP nanopar-ticles to gain catalytic stability via the electron traversing effect.The electrocatalytic HER activity can be maximumly enhanced with low overpotentials of 78 mV(alkaline)and 89 mV(acidic)at a current density of 10 mA/cm^(2) and sustained at least 24 h especially for NiZn@C-CoP catalyst.This novel system is distinct from conventional three-layer heterostructure,providing a specially thought of d-band center control engineering strategy for the design of heterogeneous catalysts and expanding to other electrocat-alysts,energy storage,sensing,and other applications.
基金National Natural Science Foundation of China,Grant/Award Numbers:21875188,22175143,32101087Key Research and Development Program of Shaanxi,Grant/Award Number:2021SF-297Natural Science Foundation of Shaanxi Province,Grant/Award Numbers:2022JQ-312,CLGC202218。
文摘Owing to its designability and intrinsic fluorescence,non-conjugated hyperbranched polysiloxane(HBPSi)has attracted widespread attention in biological filed,while it is still severely restricted by low fluorescence efficiency.So,in this paper,we introduced disulfide into HBPSi improving their luminescence properties and synthesized different molecular weight HBPSi(P1,P2,and P3).Surprisingly,P1 exhibited ultrahigh quantum yield up to 47.81%.Meanwhile,experiments applied with theoretical calculations were employed to explore the fluorescence mechanism,which is attributed to efficient restricting of non-radiative decay by clusteroluminogens formed with the cooperation of hyperbranched structure and double hydrogen bonding.In addition,the biocompatibility of P1 was verified by co-culture with MC3T3-E1 and P1 lighted up mouse fibroblast cells without fluorescent dyes.This work designed a novel fluorescent polymer with ultrahigh fluorescence quantum yield and cell imaging ability,which is promising in visualization diagnosis and treatment of tumor.
基金supported by the National Natural Science Foundation of China[grant number 82202729]the Natural Science Foundation of Shandong Province[grant number ZR2022QH261]+2 种基金the Taishan Scholar Project of Shandong Province[grant number tsqn202306355]the National Natural Science Foundation of China[grant number 32101087]the Tianjin Municipal Science and Technology Program(21JCZDJC01100).
文摘Infected bone defect is a formidable clinical challenge.Conventional approaches to prevention and treatment for infected bone defects are unsatisfactory.The key elements of the treatment are bone defect reconstruction,antiinfection,and osteogenesis.Conventional treatment methods remain unsatisfactory owing to the absence of composite integrating materials with anti-infective,and osteogenic activities as well as proper mechanical strength at the same time.In this study,we fabricated a vancomycin-encapsulated hydrogel with bacteriaresponsive release properties combined with a shaved porous(submicron-micron)three-dimensional-printed Ti6Al4V implant.The implant surface,modified with submicron-sized pores through microarc oxidation(MAO),showed enhanced osteogenic activity and integrated well with the hydrogel drug release system,enabling sustained vancomycin release.In vitro experiments underscored the commendable antibacterial ability,biosafety,and osteoinductive potential.Effective antibacterial and osteogenic abilities of the implant were further demonstrated in vivo in infected rabbit bone defects.These results showed that the vancomycinencapsulated hydrogel-loaded microarc-oxidized 3D-printed porous Ti6Al4V can repair the infected bone defects with satisfactory anti-infection and osseointegration effects.
基金financial support of the National Natural Science Foundation of China(32071327)National Key Research and Development Program of China(2016YFC1102003)+2 种基金International Science and Technology Cooperation Base of Shaanxi Province(2017GHJD-014)Science and Technology Program of Shaanxi Province(2019GY-200)Key Research and Development Program of Shaanxi Province(2019ZDLSF03-06)。
文摘The gradient porous Ti3Zr2Sn3Mo25Nb(TLM)alloy rods were fabricated through sintering the alloyed powder to a solid core.The porous sample was then modified by a Micro Arc Oxidation(MAO)treatment in an electrolyte containing calcium and phosphate,a hydrothermal treatment enabled secondary microporous hydroxyapatite(HA)coating,and a further bone morphogenetic protein-2(BMP-2)loading treatment through immersion and freeze-drying.The treatment led to an orderly secondary microporous coating containing HA nano-particles and evenly distributed BMP-2 in the porous coatings.As a result,osteoblasts could adhere and grow well on the coatings with a high cell adhesion rate and cell functional activity.The in-situ shear testing indicated that the interfacial strength had been enhanced significantly.Improvement of the bond formation and osseointegration with the titanium implant is attributed to increased surface area for the cell to attach,creating voids for the cell to grow in,and activating titanium surface by introducing bioactive ingredients such as HA and BMP-2.
基金supported by the Science Challenge Project[No:TZ2018004]National Natural Science Foundation of China[Nos.51072159,51273159]+1 种基金Science and technology program of Shaanxi Province[No:2014K10-07]Technology Foundation for Selected Overseas Chinese Scholar,Department of Human Resources and Social Security of Shaanxi Province[No:2014-27].
文摘Hydroxyapatite(HA)synthesized by a wet chemical route was subjected to heavy ion irradiation,using4 Me V Krypton ion(Kr17+)with ion fluence ranging from 1×1013 to 1×1015 ions/cm2.Glancing incidence X-ray diffraction(GIXRD)results confirmed the phase purity of irradiated HA with a moderate contraction in lattice parameters,and further indicated the irradiation-induced structural disorder,evidenced by broadening of the diffraction peaks.High-resolution transmission electron microscopy(HRTEM)observations indicated that the applied Kr irradiation induced significant damage in the hydroxyapatite lattice.Specifically,cavities were observed with their diameter and density varying with the irradiation fluences,while a radiation-induced crystalline-to-amorphous transition with increasing ion dose was identified.Raman and X-ray photoelectron spectroscopy(XPS)analysis further indicated the presence of irradiationinduced defects.Ion release from pristine and irradiated materials following immersion in Tris(p H 7.4,37?)buffer showed that dissolution in vitro was enhanced by irradiation,reaching a peak at 0.1 dpa.We examined the effects of irradiation on the early stages of the mouse osteoblast-like cells(MC3 T3-E)response.A cell counting kit-8 assay(CCK-8 test)was carried out to investigate the cytotoxicity of samples,and viable cells can be observed on the irradiated materials.
基金supported by the National Natural Science Foundation of China(Grant numbers 32071327,32101087)Shaanxi Science and Technology Association(2022JQ-312).
文摘Endowing implant surfaces with combined antibacterial and osteogenic properties by drug-loaded coatings has made great strides,but how to achieve the combined excellence of infection-triggered bactericidal and in vivo-proven osteogenic activities without causing bacterial resistance still remains a formidable challenge.Herein,antimicrobial peptides(AMPs)with osteogenic fragments were designed and complexed on the surface of silver nanoparticle(AgNP)through hydrogen bonding,and the collagen structure-bionic silk fibroin(SF)was applied to carry AgNPs@AMPs to achieve infection-triggered antibacterial and osteointegration.As verified by TEM,AMPs contributed to the dispersion and size-regulation of AgNPs,with a particle size of about 20 nm,and a clear protein corona structure was observed on the particle surface.The release curve of silver ion displayed that the SF-based coating owned sensitive pH-responsive properties.In the antibacterial test against S.aureus for up to 21 days,the antibacterial rate had always remained above 99%.Meanwhile,the underlying mechanism was revealed,originating from the destruction of the bacterial cell membranes and ROS generation.The SF-based coating was conducive to the adhesion,diffusion,and proliferation of bone marrow stem cells(BMSCs)on the surface,and promoted the expression of osteogenic genes and collagen secretion.The in vivo implantation results showed that compared with the untreated Ti implants,SF-based coating enhanced osseointegration at week 4 and 8.Overall,the AgNPs@AMPs-loaded SF-based coating presented the ability to synergistically inhibit bacteria and promote osseointegration,possessing tremendous potential application prospects in bone defects and related-infection treatments.
基金supported by National Natural Science Foundation of China(82102220,82027802,61975017,82071468)Beijing Municipal Science and Technology Commission(Z221100007422023)+1 种基金General Projects of Scientific and Technological Plan of Beijing Municipal Education Commission(KM202010025023)Talents Gathering Project of Xuanwu Hospital Capital Medical University.
文摘Selective endovascular hypothermia has been used to provide cooling-induced cerebral neuroprotection,but current catheters do not support thermally-insulated transfer of cold infusate,which results in an increased exit temperature,causes hemodilution,and limits its cooling efficiency.Herein,air-sprayed fibroin/silica-based coatings combined with chemical vapor deposited parylene-C capping film was prepared on catheter.This coating features in dual-sized-hollow-microparticle incorporated structures with low thermal conductivity.The infusate exit temperature is tunable by adjusting the coating thickness and infusion rate.No peeling or cracking was observed on the coatings under bending and rotational scenarios in the vascular models.Its efficiency was verified in a swine model,and the outlet temperature of coated catheter(75μm thickness)was 1.8-2.0◦C lower than that of the uncoated one.This pioneering work on catheter thermal insulation coatings may facilitate the clinical translation of selective endovascular hypothermia for neuroprotection in patients with acute ischemic stroke.
基金the State Key Laboratory of Solidification Processing in NWPU(No.SKLSP201818)the National Natural Science Foundation of China(No.51601216)the Fundamental Research Funds for the Central Universities(No.2018GF13)。
文摘1.Introduction In structural metallic materials,the occurrence of particular deformation mechanisms such as dislocation slip,deformation twins(DTs)[1,2]deformation kink bands(KBs)[3,4]or stressinduced phase transformations(SIM)[5],are closely related to both their crystal structures[6–8](e.g.FCC,BCC and HCP)and loading conditions(e.g.temperature and/or strain rate).
基金supported by the Fund of State Key Lab of Advanced Metals and Materials,University of Science and Technology Beijing(No.2019-ZD03)the Fund of the State Key Laboratory of Solidification Processing,Northwestern Polytechnical University(No.SKLSP201501)+2 种基金the National Natural Science Foundation of China(Nos.51601216 and 51901193)the Fundamental Research Funds for the Central Universities(Nos.2017XKQY009 and 2018GF13)sponsored by China Scholarship Council。
文摘The deformation mode of{332}<113>twinning(hereafter called 332T)has often been observed under the plastic flow in metastableβtitanium alloys with body-centered cubic(BCC)structure,which contributes to improving the mechanical performance.Herein,we report a structure of compressive deformation-induced primary 332T with hierarchical and/or heterogeneous composite sub-structure in a Twin-Induced Plasticity(TWIP)βTi-alloy under uniaxial compression.The detailed structural characterization after compressive deformation revealed that the sub-structure,including secondary 332T and secondary{112}<111>twinning,formed inside the 332T structure,which constitutes a hierarchical and/or heterogeneous structure at micro-and nano-scale and consequently contributes to the high strength,large ductility and enhanced strain-hardening behavior.
