The microstructure evolution and mechanical properties of biodegradable Mg-3Sn-1Zn-0.5Mn alloys were investigated by the optical microscopy, X-ray diffractometer and a universal material testing machine. The corrosion...The microstructure evolution and mechanical properties of biodegradable Mg-3Sn-1Zn-0.5Mn alloys were investigated by the optical microscopy, X-ray diffractometer and a universal material testing machine. The corrosion and degradation behaviors were studied by potentiodynamic polarization method and immersion test in a simulated body fluid （SBF）. It was found that the as-extruded Mg-3Sn-1Zn-0.5Mn alloy has the fine equiaxed grains which underwent complete dynamic recrystallization during the hot extrusion process, with the second phase particles of Mg2Sn precipitated on the grain boundaries and inside the grains. The tensile strength and elongation of as-extruded Mg-3Sn-1Zn-0.5Mn alloys were 244 ± 3.7 MPa and 19.3% ± 1.7%, respectively. The potentiodynamic polarization curves in SBF solution indicated the better corrosion resistance of the as-extruded Mg-3Sn-1Zn-0.5Mn alloy in the SBF solution. Immersion test in the SBF solution for 720 h revealed that the corrosion rate of as-extruded Mg-3Sn-1Zn-0.5Mn alloy was nearly 4±0.33 ram/year. The hemolysis rate of as-extruded Mg-3Sn-1Zn-0.5Mn alloy was lower than the safe value of 5% according to ISO 10993-4. As-extruded Mg-3Sn- 1Zn-0.5Mn alloy showed good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the rabbit, and no abnormalities were found after short-term implantation. It was revealed that the as-extruded Mg-3Sn-1Zn-0.5Mn alloy is a promising material for biodegradable implants, which possesses an interesting combination of preferred mechanical properties, better corrosion resistance and biocompatibility.展开更多
The Ti-45Nb (mass%) alloy’s corrosive and biocompatible response in simulated physiological conditions was investigated before and after its additional high-pressure torsion (HPT) and laser irradiation processing. Th...The Ti-45Nb (mass%) alloy’s corrosive and biocompatible response in simulated physiological conditions was investigated before and after its additional high-pressure torsion (HPT) and laser irradiation processing. The grain size reduction from 2.76 µm to ~ 200 nm and the appearance of laser-induced morphologically altered and highly oxidized surface led to the significant improvement of alloy corrosion resistance and cell–implant interaction. Moreover, an additional increase of the laser pulse energy from 5 to 15 mJ during the alloy irradiation in the air led to an increase in the surface oxygen content from 13.64 to 23.89% accompanied by an increase of excellent cell viability from 127.18 to 134.42%. As a result of the controlled alloy microstructural and surface modifications, the formation of protective bi-modal mixed Ti- and Nb-oxide external scale was enabled. The presence of this surface oxide scale enhanced the alloy’s resistance to corrosion deterioration and simultaneously boosted cell viability and proliferation.展开更多
Piezoresistive sensors,as an indispensable part of electronic and intelligent wearable devices,are often hindered by nonrenewable resources(graphene,conventional metal,or silicon).Biomass-derived carbonaceous material...Piezoresistive sensors,as an indispensable part of electronic and intelligent wearable devices,are often hindered by nonrenewable resources(graphene,conventional metal,or silicon).Biomass-derived carbonaceous materials boast many advantages such as their light weight,renewability,and excellent chemical stabilization.However,a major challenge is that the strength and resilience of carbon-based piezoresistive materials still falls short of requirements due to their random microarchitectures which cannot provide sufficiently good stress distribution.Encouraged by the excellent compressible properties and extraordinary strength of the Thalia dealbata stem,we propose a wood biomassderived carbon piezoresistive sensor with an artificial interconnected lamellar structure like the stem itself.By introducing a freezing-induced assembly process,a wood-based,completely delignified,nano-lignocellulose material can be built into a“bridges supported lamellar”type architecture,where subsequent freeze-drying and pyrolysis results in carbon aerogel monoliths.The resultant bioinspired carbon sponge has high compressibility and strength,of the order of two to five times higher than that of conventional metal,carbon,and organic materials.Combined with excellent biocompatible properties and chemical durability,these are useful properties for intelligent wearable devices and human-motion detection.展开更多
Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide(KOH, Na OH and Li OH)/urea solutions. All of the α-c...Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide(KOH, Na OH and Li OH)/urea solutions. All of the α-chitin solutions exhibited temperature-induced rapid gelation behavior. 13 C nuclear magnetic resonance(NMR) spectra revealed that the aqueous alkali hydroxide/urea solutions are non-derivatizing solvents for α-chitin. Fourier transform infrared(FT-IR), X-ray diffraction(XRD) and cross-polarization magic angle spinning(CP/MAS) 13 C NMR confirmed that α-chitin has a stable aggregate structure after undergoing dissolution and regeneration. Subsequently, nanostructured α-chitin aerogels were fabricated by regeneration from the chitin solutions in ethanol and then freeze-drying from t-Bu OH. These α-chitin aerogels exhibited high porosity(87% to 94%), low density(0.09 to 0.19 g/cm^3), high specific surface area(419 to 535 m^2/g) and large pore volume(2.7 to 3.8 cm^3/g). Moreover, the α-chitin aerogels exhibited good mechanical properties under compression and tension models. In vitro studies showed that m BMSCs cultured on chitin hydrogels have good biocompatibility. These nanostructured α-chitin aerogels may be useful for various applications, such as catalyst supports, carbon aerogel precursors and biomedical materials.展开更多
基金supported by the National Natural Science Fund for Young Scientists of China(Grant No.51301049)the Fundamental Research Funds for the Central Universities(Grant No.HEUCF201310024)+1 种基金the National Natural Science Foundation of China(Grant No.81271676)the National High Technology Research and Development Program of China(“863 Program”,Grant No.2009AA03Z423)
文摘The microstructure evolution and mechanical properties of biodegradable Mg-3Sn-1Zn-0.5Mn alloys were investigated by the optical microscopy, X-ray diffractometer and a universal material testing machine. The corrosion and degradation behaviors were studied by potentiodynamic polarization method and immersion test in a simulated body fluid （SBF）. It was found that the as-extruded Mg-3Sn-1Zn-0.5Mn alloy has the fine equiaxed grains which underwent complete dynamic recrystallization during the hot extrusion process, with the second phase particles of Mg2Sn precipitated on the grain boundaries and inside the grains. The tensile strength and elongation of as-extruded Mg-3Sn-1Zn-0.5Mn alloys were 244 ± 3.7 MPa and 19.3% ± 1.7%, respectively. The potentiodynamic polarization curves in SBF solution indicated the better corrosion resistance of the as-extruded Mg-3Sn-1Zn-0.5Mn alloy in the SBF solution. Immersion test in the SBF solution for 720 h revealed that the corrosion rate of as-extruded Mg-3Sn-1Zn-0.5Mn alloy was nearly 4±0.33 ram/year. The hemolysis rate of as-extruded Mg-3Sn-1Zn-0.5Mn alloy was lower than the safe value of 5% according to ISO 10993-4. As-extruded Mg-3Sn- 1Zn-0.5Mn alloy showed good biocompatibility after being implanted into the dorsal muscle and the femoral shaft of the rabbit, and no abnormalities were found after short-term implantation. It was revealed that the as-extruded Mg-3Sn-1Zn-0.5Mn alloy is a promising material for biodegradable implants, which possesses an interesting combination of preferred mechanical properties, better corrosion resistance and biocompatibility.
基金supported by the Ministry of Science,Technological Development and Innovation of the Republic of Serbia through Contract Nos.451-03-47/2023-01/200017 and 451-03-66/2024-03/200017 and the Ph.D.fellowship of Slađana Laketić.
文摘The Ti-45Nb (mass%) alloy’s corrosive and biocompatible response in simulated physiological conditions was investigated before and after its additional high-pressure torsion (HPT) and laser irradiation processing. The grain size reduction from 2.76 µm to ~ 200 nm and the appearance of laser-induced morphologically altered and highly oxidized surface led to the significant improvement of alloy corrosion resistance and cell–implant interaction. Moreover, an additional increase of the laser pulse energy from 5 to 15 mJ during the alloy irradiation in the air led to an increase in the surface oxygen content from 13.64 to 23.89% accompanied by an increase of excellent cell viability from 127.18 to 134.42%. As a result of the controlled alloy microstructural and surface modifications, the formation of protective bi-modal mixed Ti- and Nb-oxide external scale was enabled. The presence of this surface oxide scale enhanced the alloy’s resistance to corrosion deterioration and simultaneously boosted cell viability and proliferation.
基金Hubei Provincial Natural Science Foundation of China,Grant/Award Number:2019CFA002National Basic Research Program of China,Grant/Award Number:2015CB932600+1 种基金the Fundamental Research Funds for the Central University,Grant/Award Number:2019kfyXMBZ018Zhejiang Provincial Natural Science Foundation for Distinguished Young Scholars of China,Grant/Award Number:LR19C160001。
文摘Piezoresistive sensors,as an indispensable part of electronic and intelligent wearable devices,are often hindered by nonrenewable resources(graphene,conventional metal,or silicon).Biomass-derived carbonaceous materials boast many advantages such as their light weight,renewability,and excellent chemical stabilization.However,a major challenge is that the strength and resilience of carbon-based piezoresistive materials still falls short of requirements due to their random microarchitectures which cannot provide sufficiently good stress distribution.Encouraged by the excellent compressible properties and extraordinary strength of the Thalia dealbata stem,we propose a wood biomassderived carbon piezoresistive sensor with an artificial interconnected lamellar structure like the stem itself.By introducing a freezing-induced assembly process,a wood-based,completely delignified,nano-lignocellulose material can be built into a“bridges supported lamellar”type architecture,where subsequent freeze-drying and pyrolysis results in carbon aerogel monoliths.The resultant bioinspired carbon sponge has high compressibility and strength,of the order of two to five times higher than that of conventional metal,carbon,and organic materials.Combined with excellent biocompatible properties and chemical durability,these are useful properties for intelligent wearable devices and human-motion detection.
基金supported by the National Natural Science Foundation of China (21422405, 51373125)the Major Program of National Natural Science Foundation of China (21334005)+1 种基金the facility support of the Natural Science Foundation of Hubei Provincethe Fundamental Research Funds for the Central Universities
文摘Light weight and mechanically strong α-chitin aerogels were fabricated using the sol-gel/self-assembly method from α-chitin in different aqueous alkali hydroxide(KOH, Na OH and Li OH)/urea solutions. All of the α-chitin solutions exhibited temperature-induced rapid gelation behavior. 13 C nuclear magnetic resonance(NMR) spectra revealed that the aqueous alkali hydroxide/urea solutions are non-derivatizing solvents for α-chitin. Fourier transform infrared(FT-IR), X-ray diffraction(XRD) and cross-polarization magic angle spinning(CP/MAS) 13 C NMR confirmed that α-chitin has a stable aggregate structure after undergoing dissolution and regeneration. Subsequently, nanostructured α-chitin aerogels were fabricated by regeneration from the chitin solutions in ethanol and then freeze-drying from t-Bu OH. These α-chitin aerogels exhibited high porosity(87% to 94%), low density(0.09 to 0.19 g/cm^3), high specific surface area(419 to 535 m^2/g) and large pore volume(2.7 to 3.8 cm^3/g). Moreover, the α-chitin aerogels exhibited good mechanical properties under compression and tension models. In vitro studies showed that m BMSCs cultured on chitin hydrogels have good biocompatibility. These nanostructured α-chitin aerogels may be useful for various applications, such as catalyst supports, carbon aerogel precursors and biomedical materials.
