Foreign body reactions to the wear debris and corrosion products from the implants,and bacterial infections are the main factors leading to the implant failures.In order to resolve these problems,the antibacterial TiN...Foreign body reactions to the wear debris and corrosion products from the implants,and bacterial infections are the main factors leading to the implant failures.In order to resolve these problems,the antibacterial TiN/Cu nanocomposite coatings with various N_(2) partial pressures were deposited on 304 stainless steels(SS)using an arc ion plating(AIP)system,named TiN/Cu-x(x=0.5,1.0,1.5 Pa).The results of X-ray diffraction analysis,energy-dispersive X-ray spectroscopy,and scanning electron microscopy showed that the N_(2) partial pressures determined the Cu contents,surface defects,and crystallite sizes of TiN/Cu nanocomposite coatings,which further influenced the comprehensive abilities.And the hardness and wear resistances of TiN/Cu coatings were enhanced with increase of the crystallite sizes.Under the co-actions of surface defects,crystallite sizes,and Cu content,TiN/Cu-1.0 and TiN/Cu-1.5 coatings possessed excellent corrosion resistance.Besides,the biological tests proved that all the TiN/Cu coatings showed no cytotoxicity with strong antibacterial ability.Among them,TiN/Cu-1.5 coating significantly promoted the cell proliferation,which is expected to be a novel antibacterial,corrosion-resistant,and wear-resistant coating on the surfaces of medical implants.展开更多
Objective: To discuss the clinical significance and value of PRVC by monitoring, comparing and studying pressure control (PC), volume control (VC) and pressure-regulated volume control (PRVC) ventilation modes during ...Objective: To discuss the clinical significance and value of PRVC by monitoring, comparing and studying pressure control (PC), volume control (VC) and pressure-regulated volume control (PRVC) ventilation modes during pneumoperitoneum. Methods: Ninety patients with laparoscopic cholecystectomy were randomly and equally divided into 3 groups (PC group, VC group and PRVC group). Esophageal pressure (PES), mean airway pressure (PAWM), peak airway pressure (PAP), arterial blood carbon dioxide partial pressure (PaCO2), end-tidal carbon dioxide concentration in the expired air (ETCO2), tidal volume (TV), mean arterial pressure (MAP) and heart rate (HR) were not only detected before pneumoperitoneum, but also in 5, 10, 15 and 20 minutes after pneumoperitoneum. Results: PES after pneumoperitoneum in VC mode was obviously higher than that in PC and PRVC groups. In 10 minutes after pneumoperitoneum, levels of PaCO2 and ETCO2 became increased obviously in PC and VC groups (p < .05);levels of PaCO2 and ETCO2 were not only increased in PC group, but also the level of TV after pneumoperitoneum in PC group was significantly lower than that in the other two groups (p < .05). Levels of PaCO2 and ETCO2 were increased in PC and VC groups after pneumoperitoneum, along with the increase of MAP and HR (p < .05). After pneumoperitoneum, levels of MAP and HR in PRVC group were significantly lower than those in PC and VC groups (p < .05). Conclusions: PRVC mode can effectively reduce the pneumoperitoneum-induced increase of PAWM, PAP and PES without the unusual increase of PaCO2 and ETCO2 during surgery, so as to guarantee the stability of vital signs in perioperative patients.展开更多
The Ti6Al4V-Cu alloy was reported to show good antibacterial properties, which was promising to reduce the hazard of the bacterial infection problem. For the purpose of preparing Ti6Al4V-Cu alloy with satisfied compre...The Ti6Al4V-Cu alloy was reported to show good antibacterial properties, which was promising to reduce the hazard of the bacterial infection problem. For the purpose of preparing Ti6Al4V-Cu alloy with satisfied comprehensive properties, it’s important to study the heat treatment and the appropriate Cu content of the alloy. In this study, high Cu content Ti6Al4V-x Cu(x = 4.5, 6, 7.5 wt%) alloys were prepared, and firstly the annealing heat treatments were optimized in the α+β+Ti2Cu triple phase region to obtain satisfied tensile mechanical properties. Then the effect of Cu content on the tribological property, corrosion resistance, antibacterial activity and cytotoxicity of the Ti6Al4 V-x Cu alloys were systematically studied to obtain the appropriate Cu content. The results showed that the optimal annealing temperatures for Ti6Al4 V-x Cu(x = 4.5, 6, 7.5 wt%) alloys were 720, 740 and 760℃, respectively, which was resulted from the proper volume fractions of α,β and Ti2Cu phases in the microstructure. The additions of 4.5 wt% and 6 wt% Cu into the medical Ti6Al4 V alloy could enhance the wear resistance and corrosion resistance of the alloy, but the addition of 7.5 wt% Cu showed an opposite effect. With the increase of the Cu content, the antibacterial property was enhanced due to the increased volume fraction of Ti2Cu phase in the microstructure, but when the Cu content was increased to 7.5 wt%, cytotoxicity was presented. A medium Cu content of 6 wt%, with annealing temperature of 740℃ make the alloy possesses the best comprehensive properties of tensile properties, wear resistance, corrosion resistance, antibacterial property and biocompatibility, which is promising for future medical applications.展开更多
In order to reduce implant-related infections and improve early osseointegration,we performed HF+anodic oxidation on the surface of the new antibacterial Ti-Cu alloy to make the titanium-based implants have a micro/su...In order to reduce implant-related infections and improve early osseointegration,we performed HF+anodic oxidation on the surface of the new antibacterial Ti-Cu alloy to make the titanium-based implants have a micro/submicron structure.On this basis,a series of surface-modified Ti-x Cu alloys with different Cu contents(3,5 and 7 wt%)were fabricated and a comprehensive study was conducted on MC3 T3-E1 cell adhesion,proliferation,apoptosis and its antibacterial activity against Staphylococcus aureus.Results showed that the Ti-x Cu alloys by HF etching+anodized possessed multifunctional characteristics of antibiofilm and antibacterial abilities,excellent biocompatibility and osteogenesis promoting abilities.Increment of Cu content significantly contributed to the antibacterial and osteogenic properties of HF etching+anodized Ti-Cu alloys.Cell proliferation rates of HF etching+anodized Ti-7 Cu alloys were lower than those of Ti-3 Cu and Ti-5 Cu alloys,while the early cell apoptosis rates were higher than Ti-3 Cu and Ti-5 Cu groups.All the above results finally presented that the HF etching+anodized Ti-5 Cu alloy exhibited extremely strong antibacterial properties,good biological compatibility and osteogenic ability,as well as the most excellent ductility and corrosion resistance,providing a great potential application for the future dental implantation.展开更多
Frequent start-stops of automatic seedling transplanters would lengthen the seedling picking time due to alternating movement of the motor,and cause positioning errors and frequent motor vibrations when starting the m...Frequent start-stops of automatic seedling transplanters would lengthen the seedling picking time due to alternating movement of the motor,and cause positioning errors and frequent motor vibrations when starting the machine.To solve these problems and ensure the pick-up continuity of automatic transplanters,in this study the smooth circular arc interpolation algorithm and the least square method for multinomial curve fitting were used to conduct the trajectory planning of automatic transplanter based on the movement of the pick-up arm of the transplanter.Velocity and time curves were fitted in segments to acquire motion control parameters and further tracking control was conducted.The mathematical model of the control system was established using Simulink,and simulation analysis and system debugging test were performed.Experiments show that the trajectory curves obtained by MATLAB’s data processing can realize the continual and smooth motion trajectory of the pick-up arm;stepper motor velocity control can effectively track the planning curve and improve the seedling pick-up efficiency.The pick-up and pushing time of each motion of the planned plug seedling transplanter reduced by 1.0678 s and the start-stop times reduced from 6 to 1,which solved the frequent motor vibrations when starting the machine and improved the stability of the system.In addition,overstep and out-of-step of the motor at the start-stop moment were avoided and displacement error was reduced.展开更多
The insufficient low-cycle fatigue properties of titanium alloys under cyclic heavy loading are regarded as a challenge for their security in service. In recent years, a large number of studies have found that the tra...The insufficient low-cycle fatigue properties of titanium alloys under cyclic heavy loading are regarded as a challenge for their security in service. In recent years, a large number of studies have found that the transformation induced plasticity(TRIP) effect could hinder the propagation of fatigue cracks, which significantly improved the low-cycle fatigue properties of titanium alloys. However, the coarse β-phase grains and the soft phase transformation product α phase in TRIP titanium alloys impair their tensile strength, which restrict their applications in engineering. To this end, a Ti6Al4V5Cu alloy with TRIP effect was developed in this work. It was proposed to use the mutual restraint between the α and βphases in the material to refine the grains, and through composition optimization, the phase transformation product would be the α’ phase, which has a higher strength than the α phase. Thus, the strength of the Ti6Al4V5Cu alloy can be improved. The results showed that the tensile strength and elongation of the TRIP Ti6Al4V5Cu alloy was 1286 MPa and 22%, which was 23.7% and 46.7% higher than that of the traditional Ti6Al4V alloy, respectively. Besides, under the same strain amplitude, the fatigue life of the Ti6Al4V5Cu alloy was 2–5 times longer than that of the Ti6Al4V alloy. Furthermore, we clarified the mechanisms of improving the tensile strength and fatigue properties of the Ti6Al4V5Cu alloy, which would lay a research foundation for the development of high-performance titanium alloys.展开更多
Osteoporosis results in decreased bone mass and insufficient osteogenic function.Existing titanium alloy implants have insufficient osteoinductivity and delayed/incomplete fracture union can occur when used to treat o...Osteoporosis results in decreased bone mass and insufficient osteogenic function.Existing titanium alloy implants have insufficient osteoinductivity and delayed/incomplete fracture union can occur when used to treat osteoporotic fractures.Copper ions have good osteogenic activity,but their dose-dependent cytotoxicity limits their clinical use for bone implants.In this study,titanium alloy implants functionalized with a TiCu/TiCuN coating by arc ion plating achieved a controlled release of copper ions in vitro for 28 days.The coated alloy was co-cultured with bone marrow mesenchymal stem cells and showed excellent biocompatibility and osteoinductivity in vitro.A further exploration of the underlying mechanism by quantitative real-time polymerase chain reaction and western blotting revealed that the enhancement effects are related to the upregulation of genes and proteins(such as axin2,β-catenin,GSK-3β,p-GSK-3β,LEF1 and TCF1/TCF7)involved in the Wnt/β-catenin pathway.In vivo experiments showed that the TiCu/TiCuN coating significantly promoted osteoporotic fracture healing in a rat femur fracture model,and has good in vivo biocompatibility based on various staining results.Our study confirmed that TiCu/TiCuN-coated Ti promotes osteoporotic fracture healing associated with the Wnt pathway.Because the coating effectively accelerates the healing of osteoporotic fractures and improves bone quality,it has significant clinical application prospects.展开更多
Grain refinement has been found to be able to improve the strength of metals without reducing their plasticity or ductility.In this work,ultrafine-grained Ti6Al7Nb-xCu(x=0,3 wt%,6 wt%,9 wt%)alloys were fabricated base...Grain refinement has been found to be able to improve the strength of metals without reducing their plasticity or ductility.In this work,ultrafine-grained Ti6Al7Nb-xCu(x=0,3 wt%,6 wt%,9 wt%)alloys were fabricated based on the clinically used Ti6Al7Nb alloy via Cu alloying fabrication strategy combined with dynamic recrystallization(DRX)from martensite during hot work.Our results indicate that Cu alloying is not only effective in reducing the width of martensite laths after quenching in theβphase region but also increases the nucleation rate of DRX during the high-temperature deformation.Additionally,the Ti2Cu phase that precipitates from the matrix can pin the grain boundaries and inhibit their growth during the high-temperature deformation.The optimal Cu concentration of Ti6Al7Nb-xCu alloy is determined to be 6 wt%,and the optimal deformation temperature is determined to be 750°C.At this Cu content and deformation temperature,the grain size is only 270 nm,the tensile strength is up to 1266±10 MPa,and the elongation is 17%.Compared with the commercial Ti6Al7Nb alloy,the ultrafine-grained Ti6Al7Nb-6Cu alloy has better overall mechanical properties,good biocompatibility,and unique antibacterial properties.This work provides a theoretical basis for fabricating the new antibacterial titanium-based alloys with high strength.展开更多
Grain refinement is a well-recognized method to simultaneously increase the strength and ductility of metallic materials.Fabrication of ultrafine-grained metals in bulk using a simple low-cost approach is a long-term ...Grain refinement is a well-recognized method to simultaneously increase the strength and ductility of metallic materials.Fabrication of ultrafine-grained metals in bulk using a simple low-cost approach is a long-term goal for material scientists.In this work,based on the chemical composition of a biomedical Ti-15Zr alloy,a series of novel Ti-15Zr-xCu(x=0,3,5,7 wt.%)alloys were designed and fabricated.The alloys were quenched in the singleβphase region to obtain a martensitic microstructure and deformed in the temperature range of 710–750℃to obtain an ultrafine-grained microstructure through martensite decomposition under thermomechanical coupling conditions.Experimental results showed that Cu alloying could increase the dynamic recrystallization(DRX)nucleation rate due to its role in both refining martensitic lath width and increasing dislocation density.Cu alloying could also suppress grain growth due to the precipitated Ti_(2)Cu particles exerting pinning forces on the grain boundaries.The optimal Cu content in the Ti-15Zr-xCu alloy was determined to be 5 wt.%.After being subjected to a compression leading to a 70%height reduction at 730℃and 1 s^(–1),the grain size of the Ti-15Zr-5Cu alloy was only 180±70 nm.The tensile strength of the as-prepared alloy reached 975±10 MPa,which was 45%higher than that of the conventional Ti-15Zr alloy(673±16 MPa).This increase in strength was achieved without any reduction in ductility.The comprehensive mechanical properties of the ultrafinegrained Ti-15Zr-5Cu alloy are better than that of the Roxolid Ti–Zr alloy currently used for dental implants.展开更多
This study used an anodic etching(AE)method to construct a hierarchical rough surface on the surface of the Cu-bearing antibacterial titanium alloy,Ti-xCu(x=3,5,7 wt%),a three-dimensional structure with nested micro-/...This study used an anodic etching(AE)method to construct a hierarchical rough surface on the surface of the Cu-bearing antibacterial titanium alloy,Ti-xCu(x=3,5,7 wt%),a three-dimensional structure with nested micro-/submicro-pores and internal cavities,which is conducive to the adhesion and growth of bone cells.After AE treatment,with increase of the Cu content in the alloy,the surface of Ti-Cu alloy became sharper,with more fine micropores and internal cavities,thus increasing the surface area.The results indicated that the AE/Ti-Cu alloy exhibited good antibacterial properties and had the effect of inhibiting bacterial biofilm formation.AE treatment could increase the Cu ions release of Ti-Cu alloy in saline,and the higher the Cu content in the alloy,the more Cu ions release,resulting in stronger antibacterial performance of the alloy.AE/Ti-Cu alloy showed excellent biocompatibility,similar to the pure Ti.Therefore,anodic etching is a safe and effective surface treatment method for Ti-Cu alloy,with good clinical application prospects.展开更多
Ti-Cu alloys with different Cu contents(3, 5 and 7 wt%) were fabricated and studied as novel antibacterial biomaterials for dental application. The Ti-Cu alloys were annealing treated at different temperatures(740℃, ...Ti-Cu alloys with different Cu contents(3, 5 and 7 wt%) were fabricated and studied as novel antibacterial biomaterials for dental application. The Ti-Cu alloys were annealing treated at different temperatures(740℃, 830℃ and 910℃) in order to obtain three typical microstructures, β-Ti + Ti2Cu, β-Ti + transformed α-Ti, and transformed α-Ti. Mechanical, antibacterial and biocorrosion properties of Ti-Cu alloys with different microstructures were well analyzed by scanning electron microscopy(SEM),X-ray diffraction(XRD), transmission electron microscopy(TEM), tensile test, electrochemical test and antibacterial test. The results indicated that the Ti-Cu alloys with microstructure of β-Ti + Ti2 Cu showed the best ductility compared with other Ti-Cu alloys with microstructures of β-Ti + transformed α-Ti and complete transformed α-Ti, and meanwhile, increase of the Cu content significantly contributed to the decreased ductility due to the increasing amount of Ti2 Cu, which brought both solid solution strengthening and precipitation strengthening. Finally, the Ti-5 Cu alloy with microstructure of β-Ti + Ti2 Cu exhibited excellent ductility, antibacterial property and corrosion resistance, providing a great potential in clinical application for dental implants.展开更多
A new concept for development of metallic biomaterials is proposed in this article, i.e., a certain bio-function can be realized for a metal implant through continuous release of a designed bio-functional metal elemen...A new concept for development of metallic biomaterials is proposed in this article, i.e., a certain bio-function can be realized for a metal implant through continuous release of a designed bio-functional metal element from surface of the metal implant in the body environment. This creative idea has been verified to be possible by several different in vitro and in vivo experimental evidences on the Cu-bearing stainless steels and magnesium based metals. It was indicated that a trace amount of Cu release from the Cu-bearing steels could have obvious bio-functions of reduction of the in-stent restenosis （ISR）, anti-bacterial infection, inhibiting the inflammatory cells and even promoting the early osteogenesis. Furthermore, the degradation of magnesium based metals in bones could promote the new bone formation, enhance the bone mineral density for the osteoporosis modeled animal, and even have strong anti-bacterial ability and strong cytotoxicity to bone tumor cells due to the enhancement of pH. Special bio-function with satisfied load-bearing capacity for metallic biomaterials will bring higher application values for the implant made of this novel material. This is an attractive direction for research and development with many challenges, but the final success will be much beneficial to the majority of patients.展开更多
基金financially supported by National Key Research and Development Program of China (Nos. 2018YFC1106601 and 2016YFC1100601)Liaoning Revitalization Talents Program (No. XLYC1807069)+1 种基金National Natural Science Foundation of China (Nos. 51631009 and 31870954)Key Projects for Foreign Cooperation of Bureau of International Cooperation Chinese Academy of Sciences (No. 174321KYSB20180006)
文摘Foreign body reactions to the wear debris and corrosion products from the implants,and bacterial infections are the main factors leading to the implant failures.In order to resolve these problems,the antibacterial TiN/Cu nanocomposite coatings with various N_(2) partial pressures were deposited on 304 stainless steels(SS)using an arc ion plating(AIP)system,named TiN/Cu-x(x=0.5,1.0,1.5 Pa).The results of X-ray diffraction analysis,energy-dispersive X-ray spectroscopy,and scanning electron microscopy showed that the N_(2) partial pressures determined the Cu contents,surface defects,and crystallite sizes of TiN/Cu nanocomposite coatings,which further influenced the comprehensive abilities.And the hardness and wear resistances of TiN/Cu coatings were enhanced with increase of the crystallite sizes.Under the co-actions of surface defects,crystallite sizes,and Cu content,TiN/Cu-1.0 and TiN/Cu-1.5 coatings possessed excellent corrosion resistance.Besides,the biological tests proved that all the TiN/Cu coatings showed no cytotoxicity with strong antibacterial ability.Among them,TiN/Cu-1.5 coating significantly promoted the cell proliferation,which is expected to be a novel antibacterial,corrosion-resistant,and wear-resistant coating on the surfaces of medical implants.
文摘Objective: To discuss the clinical significance and value of PRVC by monitoring, comparing and studying pressure control (PC), volume control (VC) and pressure-regulated volume control (PRVC) ventilation modes during pneumoperitoneum. Methods: Ninety patients with laparoscopic cholecystectomy were randomly and equally divided into 3 groups (PC group, VC group and PRVC group). Esophageal pressure (PES), mean airway pressure (PAWM), peak airway pressure (PAP), arterial blood carbon dioxide partial pressure (PaCO2), end-tidal carbon dioxide concentration in the expired air (ETCO2), tidal volume (TV), mean arterial pressure (MAP) and heart rate (HR) were not only detected before pneumoperitoneum, but also in 5, 10, 15 and 20 minutes after pneumoperitoneum. Results: PES after pneumoperitoneum in VC mode was obviously higher than that in PC and PRVC groups. In 10 minutes after pneumoperitoneum, levels of PaCO2 and ETCO2 became increased obviously in PC and VC groups (p < .05);levels of PaCO2 and ETCO2 were not only increased in PC group, but also the level of TV after pneumoperitoneum in PC group was significantly lower than that in the other two groups (p < .05). Levels of PaCO2 and ETCO2 were increased in PC and VC groups after pneumoperitoneum, along with the increase of MAP and HR (p < .05). After pneumoperitoneum, levels of MAP and HR in PRVC group were significantly lower than those in PC and VC groups (p < .05). Conclusions: PRVC mode can effectively reduce the pneumoperitoneum-induced increase of PAWM, PAP and PES without the unusual increase of PaCO2 and ETCO2 during surgery, so as to guarantee the stability of vital signs in perioperative patients.
基金financially supported by the National Key Research and Development Program of China (Nos. 2018YFC1106600 and 2016YFC1100600)the Innovation Fund Project of Institute of Metal Research, Chinese Academy of Sciences (No. 2017-ZD01)+1 种基金the National Natural Science Foundation (Nos. 51631009 and 51811530320)Key Projects for Foreign Cooperation of Bureau of International Cooperation Chinese Academy of Sciences (No. 174321KYSB2018000)
文摘The Ti6Al4V-Cu alloy was reported to show good antibacterial properties, which was promising to reduce the hazard of the bacterial infection problem. For the purpose of preparing Ti6Al4V-Cu alloy with satisfied comprehensive properties, it’s important to study the heat treatment and the appropriate Cu content of the alloy. In this study, high Cu content Ti6Al4V-x Cu(x = 4.5, 6, 7.5 wt%) alloys were prepared, and firstly the annealing heat treatments were optimized in the α+β+Ti2Cu triple phase region to obtain satisfied tensile mechanical properties. Then the effect of Cu content on the tribological property, corrosion resistance, antibacterial activity and cytotoxicity of the Ti6Al4 V-x Cu alloys were systematically studied to obtain the appropriate Cu content. The results showed that the optimal annealing temperatures for Ti6Al4 V-x Cu(x = 4.5, 6, 7.5 wt%) alloys were 720, 740 and 760℃, respectively, which was resulted from the proper volume fractions of α,β and Ti2Cu phases in the microstructure. The additions of 4.5 wt% and 6 wt% Cu into the medical Ti6Al4 V alloy could enhance the wear resistance and corrosion resistance of the alloy, but the addition of 7.5 wt% Cu showed an opposite effect. With the increase of the Cu content, the antibacterial property was enhanced due to the increased volume fraction of Ti2Cu phase in the microstructure, but when the Cu content was increased to 7.5 wt%, cytotoxicity was presented. A medium Cu content of 6 wt%, with annealing temperature of 740℃ make the alloy possesses the best comprehensive properties of tensile properties, wear resistance, corrosion resistance, antibacterial property and biocompatibility, which is promising for future medical applications.
基金financially supported by the National Key Research and Development Program of China(Nos.2018YFC1106601 and 2016YFC1100601)the LiaoNing Revitalization Talents Program(No.XLYC1807069)+1 种基金the National Natural Science Foundation of China(Nos.51631009 and 31870954)the Key Projects for Foreign Cooperation of Bureau of International Cooperation Chinese Academy of Sciences(No.174321KYSB2018000)。
文摘In order to reduce implant-related infections and improve early osseointegration,we performed HF+anodic oxidation on the surface of the new antibacterial Ti-Cu alloy to make the titanium-based implants have a micro/submicron structure.On this basis,a series of surface-modified Ti-x Cu alloys with different Cu contents(3,5 and 7 wt%)were fabricated and a comprehensive study was conducted on MC3 T3-E1 cell adhesion,proliferation,apoptosis and its antibacterial activity against Staphylococcus aureus.Results showed that the Ti-x Cu alloys by HF etching+anodized possessed multifunctional characteristics of antibiofilm and antibacterial abilities,excellent biocompatibility and osteogenesis promoting abilities.Increment of Cu content significantly contributed to the antibacterial and osteogenic properties of HF etching+anodized Ti-Cu alloys.Cell proliferation rates of HF etching+anodized Ti-7 Cu alloys were lower than those of Ti-3 Cu and Ti-5 Cu alloys,while the early cell apoptosis rates were higher than Ti-3 Cu and Ti-5 Cu groups.All the above results finally presented that the HF etching+anodized Ti-5 Cu alloy exhibited extremely strong antibacterial properties,good biological compatibility and osteogenic ability,as well as the most excellent ductility and corrosion resistance,providing a great potential application for the future dental implantation.
基金The research work was supported by the Project of National Natural Science Foundation of China(No.51565048)Excellent young teacher training program of Xinjiang Corps(CZ027213)Graduate Research and Innovation Project of Xinjiang Uygur Autonomous Region(XJGRI2017056)。
文摘Frequent start-stops of automatic seedling transplanters would lengthen the seedling picking time due to alternating movement of the motor,and cause positioning errors and frequent motor vibrations when starting the machine.To solve these problems and ensure the pick-up continuity of automatic transplanters,in this study the smooth circular arc interpolation algorithm and the least square method for multinomial curve fitting were used to conduct the trajectory planning of automatic transplanter based on the movement of the pick-up arm of the transplanter.Velocity and time curves were fitted in segments to acquire motion control parameters and further tracking control was conducted.The mathematical model of the control system was established using Simulink,and simulation analysis and system debugging test were performed.Experiments show that the trajectory curves obtained by MATLAB’s data processing can realize the continual and smooth motion trajectory of the pick-up arm;stepper motor velocity control can effectively track the planning curve and improve the seedling pick-up efficiency.The pick-up and pushing time of each motion of the planned plug seedling transplanter reduced by 1.0678 s and the start-stop times reduced from 6 to 1,which solved the frequent motor vibrations when starting the machine and improved the stability of the system.In addition,overstep and out-of-step of the motor at the start-stop moment were avoided and displacement error was reduced.
基金financially supported by the National Key Research and Development Program of China(2018YFC1106600)Natural Science Foundation of China(51631009)+2 种基金Liaoning Revitalization Talents Program(XLYC1807069)Doctoral Scientific Research Foundation of Liaoning Province(2020BS002)Binzhou Weiqiao Guoke Institute of Advanced Technology。
文摘The insufficient low-cycle fatigue properties of titanium alloys under cyclic heavy loading are regarded as a challenge for their security in service. In recent years, a large number of studies have found that the transformation induced plasticity(TRIP) effect could hinder the propagation of fatigue cracks, which significantly improved the low-cycle fatigue properties of titanium alloys. However, the coarse β-phase grains and the soft phase transformation product α phase in TRIP titanium alloys impair their tensile strength, which restrict their applications in engineering. To this end, a Ti6Al4V5Cu alloy with TRIP effect was developed in this work. It was proposed to use the mutual restraint between the α and βphases in the material to refine the grains, and through composition optimization, the phase transformation product would be the α’ phase, which has a higher strength than the α phase. Thus, the strength of the Ti6Al4V5Cu alloy can be improved. The results showed that the tensile strength and elongation of the TRIP Ti6Al4V5Cu alloy was 1286 MPa and 22%, which was 23.7% and 46.7% higher than that of the traditional Ti6Al4V alloy, respectively. Besides, under the same strain amplitude, the fatigue life of the Ti6Al4V5Cu alloy was 2–5 times longer than that of the Ti6Al4V alloy. Furthermore, we clarified the mechanisms of improving the tensile strength and fatigue properties of the Ti6Al4V5Cu alloy, which would lay a research foundation for the development of high-performance titanium alloys.
基金supported by the National Natural Science Foundation of China[81972058 and 81902194]the Science and Technology Commission of Shanghai Municipality[22YF1422900 and 21002411200]+3 种基金the Shanghai Municipal Key Clinical Specialty,China[shslczdzk06701]Huangpu District Industrial Support Fund[XK2020009]the National Facility for Translational Medicine(Shanghai),China[TMSZ-2020-207]the Shanghai Engineering Research Center of Orthopedic Innovative Instruments and Personalized Medicine Instruments and Personalized Medicine[19DZ2250200].
文摘Osteoporosis results in decreased bone mass and insufficient osteogenic function.Existing titanium alloy implants have insufficient osteoinductivity and delayed/incomplete fracture union can occur when used to treat osteoporotic fractures.Copper ions have good osteogenic activity,but their dose-dependent cytotoxicity limits their clinical use for bone implants.In this study,titanium alloy implants functionalized with a TiCu/TiCuN coating by arc ion plating achieved a controlled release of copper ions in vitro for 28 days.The coated alloy was co-cultured with bone marrow mesenchymal stem cells and showed excellent biocompatibility and osteoinductivity in vitro.A further exploration of the underlying mechanism by quantitative real-time polymerase chain reaction and western blotting revealed that the enhancement effects are related to the upregulation of genes and proteins(such as axin2,β-catenin,GSK-3β,p-GSK-3β,LEF1 and TCF1/TCF7)involved in the Wnt/β-catenin pathway.In vivo experiments showed that the TiCu/TiCuN coating significantly promoted osteoporotic fracture healing in a rat femur fracture model,and has good in vivo biocompatibility based on various staining results.Our study confirmed that TiCu/TiCuN-coated Ti promotes osteoporotic fracture healing associated with the Wnt pathway.Because the coating effectively accelerates the healing of osteoporotic fractures and improves bone quality,it has significant clinical application prospects.
基金financially supported by the National Key Research and Development Program of China(No.2022YFC2406003)the Bintech-IMR R&D Program(No.GYY-JSBU-2022-008).
文摘Grain refinement has been found to be able to improve the strength of metals without reducing their plasticity or ductility.In this work,ultrafine-grained Ti6Al7Nb-xCu(x=0,3 wt%,6 wt%,9 wt%)alloys were fabricated based on the clinically used Ti6Al7Nb alloy via Cu alloying fabrication strategy combined with dynamic recrystallization(DRX)from martensite during hot work.Our results indicate that Cu alloying is not only effective in reducing the width of martensite laths after quenching in theβphase region but also increases the nucleation rate of DRX during the high-temperature deformation.Additionally,the Ti2Cu phase that precipitates from the matrix can pin the grain boundaries and inhibit their growth during the high-temperature deformation.The optimal Cu concentration of Ti6Al7Nb-xCu alloy is determined to be 6 wt%,and the optimal deformation temperature is determined to be 750°C.At this Cu content and deformation temperature,the grain size is only 270 nm,the tensile strength is up to 1266±10 MPa,and the elongation is 17%.Compared with the commercial Ti6Al7Nb alloy,the ultrafine-grained Ti6Al7Nb-6Cu alloy has better overall mechanical properties,good biocompatibility,and unique antibacterial properties.This work provides a theoretical basis for fabricating the new antibacterial titanium-based alloys with high strength.
基金the National Key Research and Development Program of China(No.2018YFC1106601)the Doctoral Scientific Research Foundation of Liaoning Province(No.2020BS002)。
文摘Grain refinement is a well-recognized method to simultaneously increase the strength and ductility of metallic materials.Fabrication of ultrafine-grained metals in bulk using a simple low-cost approach is a long-term goal for material scientists.In this work,based on the chemical composition of a biomedical Ti-15Zr alloy,a series of novel Ti-15Zr-xCu(x=0,3,5,7 wt.%)alloys were designed and fabricated.The alloys were quenched in the singleβphase region to obtain a martensitic microstructure and deformed in the temperature range of 710–750℃to obtain an ultrafine-grained microstructure through martensite decomposition under thermomechanical coupling conditions.Experimental results showed that Cu alloying could increase the dynamic recrystallization(DRX)nucleation rate due to its role in both refining martensitic lath width and increasing dislocation density.Cu alloying could also suppress grain growth due to the precipitated Ti_(2)Cu particles exerting pinning forces on the grain boundaries.The optimal Cu content in the Ti-15Zr-xCu alloy was determined to be 5 wt.%.After being subjected to a compression leading to a 70%height reduction at 730℃and 1 s^(–1),the grain size of the Ti-15Zr-5Cu alloy was only 180±70 nm.The tensile strength of the as-prepared alloy reached 975±10 MPa,which was 45%higher than that of the conventional Ti-15Zr alloy(673±16 MPa).This increase in strength was achieved without any reduction in ductility.The comprehensive mechanical properties of the ultrafinegrained Ti-15Zr-5Cu alloy are better than that of the Roxolid Ti–Zr alloy currently used for dental implants.
基金financially supported by the Natural Science Foundation of Liaoning Province(No.2022-MS-079).
文摘This study used an anodic etching(AE)method to construct a hierarchical rough surface on the surface of the Cu-bearing antibacterial titanium alloy,Ti-xCu(x=3,5,7 wt%),a three-dimensional structure with nested micro-/submicro-pores and internal cavities,which is conducive to the adhesion and growth of bone cells.After AE treatment,with increase of the Cu content in the alloy,the surface of Ti-Cu alloy became sharper,with more fine micropores and internal cavities,thus increasing the surface area.The results indicated that the AE/Ti-Cu alloy exhibited good antibacterial properties and had the effect of inhibiting bacterial biofilm formation.AE treatment could increase the Cu ions release of Ti-Cu alloy in saline,and the higher the Cu content in the alloy,the more Cu ions release,resulting in stronger antibacterial performance of the alloy.AE/Ti-Cu alloy showed excellent biocompatibility,similar to the pure Ti.Therefore,anodic etching is a safe and effective surface treatment method for Ti-Cu alloy,with good clinical application prospects.
基金financially supported by the National Natural Science Foundation of China (Nos. 51631009 and 51811530320)the National Key Research and Development Program of China (Nos. 2018YFC1106600 and 2016YFC1100600)+1 种基金the Innovation Fund Project of Institute of Metal Research, Chinese Academy of Sciences (No. 2017-ZD01)the Key Projects for Foreign Cooperation of Bureau of International Cooperation Chinese Academy of Sciences (No. 174321KYSB2018000)
文摘Ti-Cu alloys with different Cu contents(3, 5 and 7 wt%) were fabricated and studied as novel antibacterial biomaterials for dental application. The Ti-Cu alloys were annealing treated at different temperatures(740℃, 830℃ and 910℃) in order to obtain three typical microstructures, β-Ti + Ti2Cu, β-Ti + transformed α-Ti, and transformed α-Ti. Mechanical, antibacterial and biocorrosion properties of Ti-Cu alloys with different microstructures were well analyzed by scanning electron microscopy(SEM),X-ray diffraction(XRD), transmission electron microscopy(TEM), tensile test, electrochemical test and antibacterial test. The results indicated that the Ti-Cu alloys with microstructure of β-Ti + Ti2 Cu showed the best ductility compared with other Ti-Cu alloys with microstructures of β-Ti + transformed α-Ti and complete transformed α-Ti, and meanwhile, increase of the Cu content significantly contributed to the decreased ductility due to the increasing amount of Ti2 Cu, which brought both solid solution strengthening and precipitation strengthening. Finally, the Ti-5 Cu alloy with microstructure of β-Ti + Ti2 Cu exhibited excellent ductility, antibacterial property and corrosion resistance, providing a great potential in clinical application for dental implants.
基金supported by the National Basic Research Program of China(No.2012CB619101)the National Natural Science Foundation of China(Nos.51171186 and 30970715)Shenyang National Labfor Materials Science,and Military Medicine Research Fund(CWS11C268)
文摘A new concept for development of metallic biomaterials is proposed in this article, i.e., a certain bio-function can be realized for a metal implant through continuous release of a designed bio-functional metal element from surface of the metal implant in the body environment. This creative idea has been verified to be possible by several different in vitro and in vivo experimental evidences on the Cu-bearing stainless steels and magnesium based metals. It was indicated that a trace amount of Cu release from the Cu-bearing steels could have obvious bio-functions of reduction of the in-stent restenosis （ISR）, anti-bacterial infection, inhibiting the inflammatory cells and even promoting the early osteogenesis. Furthermore, the degradation of magnesium based metals in bones could promote the new bone formation, enhance the bone mineral density for the osteoporosis modeled animal, and even have strong anti-bacterial ability and strong cytotoxicity to bone tumor cells due to the enhancement of pH. Special bio-function with satisfied load-bearing capacity for metallic biomaterials will bring higher application values for the implant made of this novel material. This is an attractive direction for research and development with many challenges, but the final success will be much beneficial to the majority of patients.
