Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main ...Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved.ZrO_(2)-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability.In this work,the degradation,cytotoxicity,and antibacterial performance of ZrO_(2)thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated.Short-term degradation of ZrO_(2)-coated and uncoated samples was assessed considering electrochemical techniques and H_(2)evolution(gas chromatography).Additionally,long term degradation was assessed by mass-loss measurements.The results showed that a 380 nm ZrO_(2)coating reduces the degradation rate and H_(2)evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term.The ZrO_(2)coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface,in comparison to the bare alloy.Finally,the ZrO_(2)coating prevents the adhesion and biofilm formation of S.aureus.展开更多
In this study,the peroxidase-like activity of zirconium(Ⅳ)oxide nanoparticles(nZr)is reported.Peroxidases catalyze the oxidation of their substrate in the presence of peroxide species.3,3′,5,5′-tetramethylbenzidine...In this study,the peroxidase-like activity of zirconium(Ⅳ)oxide nanoparticles(nZr)is reported.Peroxidases catalyze the oxidation of their substrate in the presence of peroxide species.3,3′,5,5′-tetramethylbenzidine(TMB)is a peroxidase substrate,and we have demonstrated that nZr oxidizes the TMB in the presence of hydrogen peroxide resulting in a colored(TMBox)product.The reaction was tested in various buffers,and sodium acetate with pH 4 was observed to be an ideal buffer for the enzymatic reaction and the dispersity of the nZr in the solution.The nanozyme behavior was studied systematically at three different temperatures(25,35 and 45℃)and a wide range of H_(2)O_(2) concentrations.The dependence of the enzymatic reaction on temperature,nZr content and H_(2)O_(2) concentration was observed.The enzymatic reaction was tested in different protein solutions and no noticeable interference was observed with these proteins.Overall,we demonstrate that nZr,which is often used for industrial applications,mimics peroxidase enzyme and catalyzes oxidation of its substrate in the presence of peroxide species.展开更多
ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase c...ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.展开更多
Energy consumption is increasing yearly all over the world due to the increase in population and demand of energy. The world largely depends on a hydroelectric energy supply, thermal electric energy supply which is al...Energy consumption is increasing yearly all over the world due to the increase in population and demand of energy. The world largely depends on a hydroelectric energy supply, thermal electric energy supply which is all non-renewable energy resources. Nevertheless, non-renewable energy resources are rapidly decreasing per year due to increasing rate of energy consumption. The quest for the discovery of another abundant resource of energy has attracted many scientists into development of renewable energy technologies like photovoltaic energy which are the technology that convert solar radiation into electricity. For the past several years, different photovoltaic devices like inorganic, organic, and hybrid solar cells have been invented using different methods for different application purposes. Moreover, high conversion efficiency of silicon solar cells, the high cost of module and complicated production processes involved in the production restricted commercialization of photovoltaic solar cells as a means of electricity supply. Among all organic solar cells, Dye-Sensitized Solar Cells (DSSCs) are the most efficient, low cost and easily implemented technology. This review paper focuses on clarifying the technological meaning of the structure of DSSCs, Various types of DSSCs materials, working electrode and working mechanism of DSSC, transparent and conductive substrate, nanocrystalline semiconductor film electrode, photosensisitizer (dye), electrolyte, carbon layer electrode, zinc oxide (ZnO) layer, zirconium dioxide (ZrO2) layer, benefits of DSSCs and application, the efficiency and challenges for research and development of DSSCs to upgrade the current efficiency.展开更多
基金supported by CONACYT-Frontera-1740,CONACy T-CB-288101,CONACy T-299703,and DGAPAPAPIIT-IN101419 projectssupport from the CONACYT Ph.D.-scholarship(CVU 606030)+2 种基金the program Doctorado en Ciencia e Ingeniería de Materials at the Universidad Nacional Autónoma de Méxicothe support from the program Maestría y Doctorado en Ciencias Médicas,Odontológicas y de la Salud at the Universidad Nacional Autónoma de México and the Ph.D.scholarship from CONACy T(CVU 856985)the support from the program Posgrado de Doctorado en Ciencias en Biomedicina y Biotecnología Molecular,Escuela Nacional de Ciencias Biológicas at the Instituto Politécnico Nacional and the Ph.D.scholarship from CONACy T(CVU 739515)
文摘Biodegradable magnesium alloys are promising candidates for temporary fracture fixation devices in orthopedics;nevertheless,its fast degradation rate at the initial stage after implantation remains as one of the main challenges to be resolved.ZrO_(2)-based coatings to reduce the degradation rate of the Mg-implants are an attractive solution since they show high biocompatibility and stability.In this work,the degradation,cytotoxicity,and antibacterial performance of ZrO_(2)thin films deposited by magnetron sputtering on a Mg-Zn-Ca alloy was evaluated.Short-term degradation of ZrO_(2)-coated and uncoated samples was assessed considering electrochemical techniques and H_(2)evolution(gas chromatography).Additionally,long term degradation was assessed by mass-loss measurements.The results showed that a 380 nm ZrO_(2)coating reduces the degradation rate and H_(2)evolution of the alloy during the initial 3 days after immersion but allows the degradation of the bare alloy for the long-term.The ZrO_(2)coating does not compromise the biocompatibility of the alloy and permits better cell adhesion and proliferation of mesenchymal stem cells directly on its surface,in comparison to the bare alloy.Finally,the ZrO_(2)coating prevents the adhesion and biofilm formation of S.aureus.
基金This work was supported by the USDA National Institute of Food and Agriculture(NIFA),AFRI project(2018-67021-27973,2017-07822).
文摘In this study,the peroxidase-like activity of zirconium(Ⅳ)oxide nanoparticles(nZr)is reported.Peroxidases catalyze the oxidation of their substrate in the presence of peroxide species.3,3′,5,5′-tetramethylbenzidine(TMB)is a peroxidase substrate,and we have demonstrated that nZr oxidizes the TMB in the presence of hydrogen peroxide resulting in a colored(TMBox)product.The reaction was tested in various buffers,and sodium acetate with pH 4 was observed to be an ideal buffer for the enzymatic reaction and the dispersity of the nZr in the solution.The nanozyme behavior was studied systematically at three different temperatures(25,35 and 45℃)and a wide range of H_(2)O_(2) concentrations.The dependence of the enzymatic reaction on temperature,nZr content and H_(2)O_(2) concentration was observed.The enzymatic reaction was tested in different protein solutions and no noticeable interference was observed with these proteins.Overall,we demonstrate that nZr,which is often used for industrial applications,mimics peroxidase enzyme and catalyzes oxidation of its substrate in the presence of peroxide species.
基金financially supported by the National Natural Science Foundation (Nos. 51164023 and 513640236)the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (No. NJYT-13B10)the Program for New Century Excellent Talents in University (No. NCET-13-0847)。
文摘ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.
文摘Energy consumption is increasing yearly all over the world due to the increase in population and demand of energy. The world largely depends on a hydroelectric energy supply, thermal electric energy supply which is all non-renewable energy resources. Nevertheless, non-renewable energy resources are rapidly decreasing per year due to increasing rate of energy consumption. The quest for the discovery of another abundant resource of energy has attracted many scientists into development of renewable energy technologies like photovoltaic energy which are the technology that convert solar radiation into electricity. For the past several years, different photovoltaic devices like inorganic, organic, and hybrid solar cells have been invented using different methods for different application purposes. Moreover, high conversion efficiency of silicon solar cells, the high cost of module and complicated production processes involved in the production restricted commercialization of photovoltaic solar cells as a means of electricity supply. Among all organic solar cells, Dye-Sensitized Solar Cells (DSSCs) are the most efficient, low cost and easily implemented technology. This review paper focuses on clarifying the technological meaning of the structure of DSSCs, Various types of DSSCs materials, working electrode and working mechanism of DSSC, transparent and conductive substrate, nanocrystalline semiconductor film electrode, photosensisitizer (dye), electrolyte, carbon layer electrode, zinc oxide (ZnO) layer, zirconium dioxide (ZrO2) layer, benefits of DSSCs and application, the efficiency and challenges for research and development of DSSCs to upgrade the current efficiency.
