A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced cataly...A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced catalytic activity in aerobic oxidative desulfurization process.The experimental results indicated that the as-prepared materials possessed excellent 3 DOM structure,which is beneficial for the catalytic activity.The sample 3 DOM W-TiO_(2)-20 exhibited the highest activity in ODS process,and the sulfur removal can reach 98%in 6 h.Furthermore,the oxidative product was also analyzed in the reaction process.展开更多
Transparent solar-blind ultraviolet photodetectors(SBUV PDs)have extensive applications in versatile scenarios,such as optical communication.However,it is still challenging to simultaneously achieve high responsivity,...Transparent solar-blind ultraviolet photodetectors(SBUV PDs)have extensive applications in versatile scenarios,such as optical communication.However,it is still challenging to simultaneously achieve high responsivity,high transparency,and satisfying self-powered capability.Here,we demonstrated high-performance,transparent,and self-powered photoelectrochemical-type(PEC)SBUV PDs based on vertically grown ultrathin In_(2)O_(3) nanosheet arrays(NAs)with a three-dimensional(3D)porous structure.The 3D porous structure simultaneously improves the transmittance in the visible light region,accelerates interfacial reaction kinetics,and promotes photogenerated carrier transport.The performance of In_(2)O_(3) NAs photoanodes exceeds most reported self-powered PEC SBUV PDs,exhibiting a high transmittance of approximately 80%in the visible light region,a high responsivity of 86.15 mA/W for 254 nm light irradiation,a fast response speed of 15/18 ms,and good multicycle stability.The In_(2)O_(3) NAs also show excellent spectral selectivity with an ultrahigh solar-blind rejection ratio of 1319.30,attributed to the quantum confinement effect induced by the ultrathin feature(2-3 nm).Furthermore,In_(2)O_(3) NAs photoanodes show good capability in underwater optical communication.Our work demonstrated that a 3D porous structure is a powerful strategy to synchronously achieve high responsivity and transparency and provides a new perspective for designing high-performance,transparent,and self-powered PEC SBUV PDs.展开更多
Porous Ti compacts with large size and complex shape for biomedical applications were fabricated in the porosity range from 40.5% to 53.8% by controlling gelcasting parameters and sintering conditions. The experimenta...Porous Ti compacts with large size and complex shape for biomedical applications were fabricated in the porosity range from 40.5% to 53.8% by controlling gelcasting parameters and sintering conditions. The experimental results show that the total porosity and open porosity of porous titanium compacts gelcast from the Ti slurry with 34 vol.% solid loading and sintered at 1100℃ for 1.5 h are 46.5% and 40.7%, respectively, and the mechanical properties are as follows: compressive strength 158.6 MPa and Young's modulus 8.5 GPa, which are similar to those of human cortical bone and appropriate for implanting purpose.展开更多
Titanium-based porous materials can be used in structural applications and medical implants because of their excellent mechanical properties at elevated temperatures, good corrosion resistance and wonderful biocompati...Titanium-based porous materials can be used in structural applications and medical implants because of their excellent mechanical properties at elevated temperatures, good corrosion resistance and wonderful biocompatibility. However, most of the methods used to produce the porous metal can only give limited porosity and uncontrollable pore morphologies. In the present study, a newly developed method of powder metallurgy using the space-holder technique was used to fabricate porous titanium with controllable porosity. The morphological features and mechanical properties of the products were fully investigated. The results show that the porosity is in the range of 55%-75%, and the mean pore size, with an average sphericity of -0.72, is 600 μm. The plateau stresses vary between 10 MPa and 35 MPa. As predicted by the Gibson-Ashby model, the plateau stress decreases with increasing porosity.展开更多
The powder space holder (PSH) and powder injection molding (PIM) methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts. In this study, mi...The powder space holder (PSH) and powder injection molding (PIM) methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts. In this study, micro-porous Ti6Al4V alloy (Ti64) parts were produced by the PSH-PIM process. Ti64 alloy powder and spherical polymethylrnethacrylate (PMMA) particles were used as a space holder material. After molding, binder debinding was performed by thermal method under inert gas. Debinded samples were sintered at 1250℃ for 60min in a vacuum (10-4 Pa). Metallographic studies were conducted to determine densification and the corresponding microstructural changes. The surface of sintered samples was examined by SEM. The compressive stress and elastic modulus of the rificro-porous Ti64 samples were determined. The effects of fraction of PMMA on the properties of sintered micro-porous Ti64 alloy samples were investigated. It was shown that the fraction of PMMA could be controlled to affect the properties of the Ti alloy.展开更多
In order to meet the clinical requirements of spine surgery,this paper proposed the exploratory research of computer-aided design and selective laser melting(SLM)fabrication of a bionic porous titanium spine implant.T...In order to meet the clinical requirements of spine surgery,this paper proposed the exploratory research of computer-aided design and selective laser melting(SLM)fabrication of a bionic porous titanium spine implant.The structural design of the spinal implant is based on CT scanning data to ensure correct matching,and the mechanical properties of the implant are verified by simulation analysis and laser selective melting experiment.The surface roughness of the spinal implant manufactured by SLM without post-processing is Ra 15μm,and the implant is precisely jointed with the photosensitive resin model of the upper and lower spine.The surface micro-hardness of the implant is HV 373,tensile strengthσ_(b)=1238.7 MPa,yield strengthσ_(0.2)=1043.9 MPa,the elongation is 6.43%,and the compressive strength of porous structure under 84.60%porosity is 184.09 MPa,which can meet the requirements of the reconstruction of stable spines.Compared with the traditional implant and intervertebral fusion cage,the bionic porous spinal implant has the advantages of accurate fit,porous bionic structure and recovery of patients,and the ion release experiment proved that implants manufactured by SLM are more suitable for clinical application after certain treatments.The elastic modulus of the sample is improved after heat treatment,mainly because the microstructure of the sample changes fromα’phase toα+βdual-phase after heat treatment.In addition,the design of high-quality bionic porous spinal implants still needs to be optimized for the actual needs of doctors.展开更多
Abstract An analytical solution to the three-dimen-sional scattering and diffraction of plane SV-waves by a saturated hemispherical alluvial valley in elastic half-space is obtained by using Fourier-Bessel series expa...Abstract An analytical solution to the three-dimen-sional scattering and diffraction of plane SV-waves by a saturated hemispherical alluvial valley in elastic half-space is obtained by using Fourier-Bessel series expan-sion technique. The hemispherical alluvial valley with saturated soil deposits is simulated with Biot's dynamic theory for saturated porous media. The following conclusions based on numerical results can be drawn: (1) there are a significant differences in the seismic response simulation between the previous single-phase models and the present two-phase model; (2) the nor-malized displacements on the free surface of the alluvial valley depend mainly on the incident wave angles, the dimensionless frequency of the incident SV waves and the porosity of sediments; (3) with the increase of the incident angle, the displacement distributions become more complicated; and the displacements on the free surface of the alluvial valley increase as the porosity of sediments increases.展开更多
The feature of porous titanium is that new bone trabecular tissue could ingrow intoits pores and produce interlocking attachment.The spherical TC<sub>4</sub> powder and titanium fiberwere seperately implan...The feature of porous titanium is that new bone trabecular tissue could ingrow intoits pores and produce interlocking attachment.The spherical TC<sub>4</sub> powder and titanium fiberwere seperately implanted into the femurs of 24 dogs.The pore size of the samples was0.24mm and their rates of porosity were 40%~50%.After 3 months,the interface shearstrength examined by straight pulling test,was over 4.60±0.36MPa.Scanning electronmicroscopy showed that there were new bone components in the porous layer.Lightmicroscopy also revealed that there were new bone lacunae and their pathways in it.Thedepth of the reforming bone was 3 mm.Interface shear strength of the new bone in the po-rous layer might meet the need of load bearing.Porous materials would prevent the artificialjoint from loosening and thus help to develop a new service clinically.展开更多
Porous calcium phosphate ceramics were produced by compression molding using a special mold followed by sintering. The porous calcium phosphate ceramics have three-dimensional and penetrated open pores 380-400μm in...Porous calcium phosphate ceramics were produced by compression molding using a special mold followed by sintering. The porous calcium phosphate ceramics have three-dimensional and penetrated open pores 380-400μm in diacneter spaced at intervals of 200μm. The layers of the linear penetration pores alternately lay perpendicular to pore direction. The porosity was 59%-65% . The Ca/ P molar ratios of the porous calcium phos phate ceramics range from 1.5 to 1.85. A binder cantaining methyl cellulose was most effective for preparing the powder compact among vinyl acetate, polyvinyl alcohol, starch, stearic acid, methyl cellulose and their mixtures . Stainless steel, polystyrene, nylon and bamboo were used as the long columnar dies for the penetrated open pores. When polystyrene, nylon and bamboo were used as the long columnar male dies, the dies were burned oat during the sintering process. Using stainless steel as the male dies with the removal of the dies before heat treatment resulted in a higher level of densification of the calcium phosphate ceramic.展开更多
As a novel structural and functional material,porous titanium and its alloys have been widely used in the aerospace,marine engineering and biomedical fields due to their high corrosion resistance,low density,good bioc...As a novel structural and functional material,porous titanium and its alloys have been widely used in the aerospace,marine engineering and biomedical fields due to their high corrosion resistance,low density,good biocompatibility and excellent mechanical properties.Therefore,in this paper,a comprehensive review of powder metallurgy(PM)(including additive manufacturing(AM)processes)for fabricating porous titanium is firstly covered in terms of their working principles,capabilities,shortcomings and strengths.Simultaneously,the influencing factors of various methods on final pore structure of porous Ti are involved.Secondly,a summary of the chemical methods(CM)to obtain the porous Ti is also provided,such as dealloying method and reduction method.Finally,the tendency and direction of preparation technology as well as application of porous titanium were prospected.展开更多
Porous titanium alloy is currently widely used in clinical treatment of orthopaedic diseases for its lower elastic modulus and ability to integrate with bone tissue.At the micro-level,cells can respond to different ge...Porous titanium alloy is currently widely used in clinical treatment of orthopaedic diseases for its lower elastic modulus and ability to integrate with bone tissue.At the micro-level,cells can respond to different geometries,and at the macro-level,the geometric design of implants will also affect the biological function of cells.In this study,three kinds of porous scaffolds with square,triangular and circle rod shapes were designed and 3D printed.This study observed the proliferation and differentiation of MC3T3-E1 cells during surface culture of the three types of scaffolds.It also evaluated the characteristics of the three scaffolds by means of compression tests and scanning electron microscopy to provide a reference for the design of porous titanium alloy implants for clinical applications.The trends of cell proliferation and gene expression between the three types of scaffolds were observed after treatment with two inhibitors.The results show that the square rod porous scaffolds have the best proliferative and osteogenic activities,and these findings may be due to differences in piezo-type mechanosensitive ion channel component 1(Piezo1)and Yes-associated protein(YAP)expression caused by the macro-geometric topography.展开更多
Although metal–organic frameworks have been heavily tested as the anode materials for lithium-ion batteries(LIBs),the poorer conductivity,easy collapse of frameworks,and serious volume expansion limit their further a...Although metal–organic frameworks have been heavily tested as the anode materials for lithium-ion batteries(LIBs),the poorer conductivity,easy collapse of frameworks,and serious volume expansion limit their further application in LIBs.Herein,we report a facile approach to obtain MXene-encapsulated porous Ni-naphthalene dicarboxylic acid(Ni-NDC)nanosheets by hybridizing ultrathin Ti_(3)C_(2)MXene and three-dimensional(3D)Ni-NDC nanosheet aggregates.In the structure of Ni-NDC/MXene hybrids,the interlayer hydrogen-bond interaction between Ni-NDC and MXene can effectively increase the interlayer spacing and further inhibit the oxidation of pure MXene.Hence,the introduction of MXene(a conductive matrix)could further improve the conductivity of Ni-NDC,avoid self-agglomeration,and buffer the volume expansion of Ni-NDC nanosheets.Benefiting from the synergistic effects between Ni-NDC and MXene,Ni-NDC/MXene hybrid electrode exhibits a reversible discharge capacity(579.8 mA∙h∙g^(−1)at 100 mA∙g^(−1)after 100 cycles)and good long-term cycling performance(310 mA∙h∙g^(−1)at 1 A∙g^(−1)after 500 cycles).展开更多
Radical-containing porous organic polymers(POPs)have drawn great interest in various applications.However,the synthesis of radical POPs remains challenging due to the unstable nature of organic radicals.Here,a persist...Radical-containing porous organic polymers(POPs)have drawn great interest in various applications.However,the synthesis of radical POPs remains challenging due to the unstable nature of organic radicals.Here,a persistent and stable three-dimensional silicon-diacetylene porous organic radical polymer was synthesized via a classic Eglinton homocoupling reaction of tetraethynylsilane.The presence of carbon radicals in this material was confirmed by electron paramagnetic resonance,and its paramagnetic behavior was analyzed by a superconducting quantum interference device.This unique material has a low-lying lowest unoccupied molecular orbital(LUMO)energy level(−5.47 eV)and a small energy gap(ca.1.46 eV),which shows long-term cycling stability and excellent rate capability as an anode material for lithium-ion batteries,demonstrating potential application in energy fields.展开更多
Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differ...Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650~C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic (PC) activity of the composites was investigated un- der UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were k = 0.576 mg'm3·min^-1 and K = 0.048 m3/mg.展开更多
Medical stone-based porous ceramics as a carrier were prepared by ultra-fine grinding and low-temperature sintering method. Nano-TiO~ thin films were loaded on the carrier by chemical liquid deposition method using ti...Medical stone-based porous ceramics as a carrier were prepared by ultra-fine grinding and low-temperature sintering method. Nano-TiO~ thin films were loaded on the carrier by chemical liquid deposition method using titanium tetrachloride as a precursor. The micro-morphology and microstructure of the synthesized samples were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, and mercury injection method. The photo-catalytic activity of the TiO2 thin films was investigated by degrading formaldehyde. The main crystalline phase in the TiO2 thin films calcined at 550~C is anatase with the average particle size about 10 nm. The specific surface area of the carrier-coated nano-TiO2 increases from 3.68 to 5.32 m2/g. The formaldehyde removal rate of the TiO2/medical stone-based porous ceramics irradiated under an ultraviolet lamp for 120 min reaches 85.6%.展开更多
In order to simulate the behavior of gas hydrate formation and decomposition,a 3-Dimension experimental device was built,consisting of a high-pressure reactor with an inner diameter of 300 mm,effective height of 100 m...In order to simulate the behavior of gas hydrate formation and decomposition,a 3-Dimension experimental device was built,consisting of a high-pressure reactor with an inner diameter of 300 mm,effective height of 100 mm,and operation pressure of 16 MPa.Eight thermal resistances were mounted in the porous media at different depthes and radiuses to detect the temperature distribution during the hydrate formation/decomposition.To collect the pressure,temperature,and flux of gas production data,the Monitor and Control Generated System(MCGS) was used.Using this device,the formation and decomposition behavior of methane hydrate in the 20 ~ 40 mesh natural sand with salinity of 3.35 wt% was examined.It was found that the front of formation or decomposition of hydrate can be judged by the temperature distribution.The amount of hydrate formation can also be evaluated by the temperature change.During the hydrate decomposition process,the temperature curves indicated that the hydrate in the top and bottom of reactor dissociated earlier than in the inner.The hydrate decomposition front gradually moved from porous media surface to inner and kept a shape of column form,with different moving speed at different surface position.The proper decomposition pressure was also determined.展开更多
Catalyst recovery is one of the most important aspects that restrict the application of Ti O_2 photocatalyst. In order to reduce restrictions and improve the photocatalytic efficiency, a hierarchical porous Ti O_2 mon...Catalyst recovery is one of the most important aspects that restrict the application of Ti O_2 photocatalyst. In order to reduce restrictions and improve the photocatalytic efficiency, a hierarchical porous Ti O_2 monolith(PTM) with well-defined macroporous and homogeneous mesoporous structure was prepared by using a sol-gel phase separation method. P123 was used as the mesoporous template and graphene oxide was applied to increase the activity and integrity of the monolithic Ti O_2. According to scanning electron microscopy and the Barrett-Joyner-Halenda measurements, PTM_3 is mainly composed of 10 nm anatase crystallines with3.6 nm mesopores and 2-8 μm macropores. Further characterization suggests carbon and nitrogen have been maintained in the PTM during calcinations so as to induce the visible light activity. The PTM with 0.07 wt%graphene oxide dosage shows high efficiency for methyl orange(MO) decolorization under both full spectrum and visible light irradiation(λ >400 nm). Besides, the monolith remains intact and has good photocatalytic stability after four cyclic experiments.展开更多
Selective laser melting(SLM)technology plays an important role in the preparation of porous titanium(Ti)implants with complex structures and precise sizes.Unfortunately,the processing characteristics of this technolog...Selective laser melting(SLM)technology plays an important role in the preparation of porous titanium(Ti)implants with complex structures and precise sizes.Unfortunately,the processing characteristics of this technology,which include rapid melting and solidification,lead to products with high residual stress.Herein,an in situ method was developed to restrain the residual stress and improve the mechanical strength of porous Ti alloys during laser additive manufacturing.In brief,porous Ti6Al4V was prepared by an SLM three-dimensional(3D)printer equipped with a double laser system that could rescan each layer immediately after solidification of the molten powder,thus reducing the temperature gradient and avoiding rapid melting and cooling.Results indicated that double scanning can provide stronger bonding conditions for the honeycomb structure and improve the yield strength and elastic modulus of the alloy.Rescanning with an energy density of 75%resulted in 33.5%–38.0%reductions in residual stress.The porosities of double-scanned specimens were 2%–4%lower than those of singlescanned specimens,and the differences noted increased with increasing sheet thickness.The rescanning laser power should be reduced during the preparation of porous Ti with thick cell walls to ensure dimensional accuracy.展开更多
基金the financial support from the National Natural Science Foundation of China(Nos.21722604 and 21776116)China Postdoctoral Science Foundation(2020M671365)+2 种基金Jiangsu Postdoctoral Research Funding Program(No.2021K343C)Natural Science Foundation of Jiangsu Province(No.BK20190243)the Society Development Fund of Zhenjiang City(SH2020020)。
文摘A series of three-dimensional ordered macroporous(3 DOM)W-TiO_(2)catalysts have been prepared through a facile colloidal crystal template method.The prepared materials characterized in detail exhibited enhanced catalytic activity in aerobic oxidative desulfurization process.The experimental results indicated that the as-prepared materials possessed excellent 3 DOM structure,which is beneficial for the catalytic activity.The sample 3 DOM W-TiO_(2)-20 exhibited the highest activity in ODS process,and the sulfur removal can reach 98%in 6 h.Furthermore,the oxidative product was also analyzed in the reaction process.
基金support from Fundamental Research Funds for the Central Universities(No.2572023AW26)the Innovation Foundation for the Doctoral Program of Forestry Engineering of Northeast Forestry University(No.LYGC202227).
文摘Transparent solar-blind ultraviolet photodetectors(SBUV PDs)have extensive applications in versatile scenarios,such as optical communication.However,it is still challenging to simultaneously achieve high responsivity,high transparency,and satisfying self-powered capability.Here,we demonstrated high-performance,transparent,and self-powered photoelectrochemical-type(PEC)SBUV PDs based on vertically grown ultrathin In_(2)O_(3) nanosheet arrays(NAs)with a three-dimensional(3D)porous structure.The 3D porous structure simultaneously improves the transmittance in the visible light region,accelerates interfacial reaction kinetics,and promotes photogenerated carrier transport.The performance of In_(2)O_(3) NAs photoanodes exceeds most reported self-powered PEC SBUV PDs,exhibiting a high transmittance of approximately 80%in the visible light region,a high responsivity of 86.15 mA/W for 254 nm light irradiation,a fast response speed of 15/18 ms,and good multicycle stability.The In_(2)O_(3) NAs also show excellent spectral selectivity with an ultrahigh solar-blind rejection ratio of 1319.30,attributed to the quantum confinement effect induced by the ultrathin feature(2-3 nm).Furthermore,In_(2)O_(3) NAs photoanodes show good capability in underwater optical communication.Our work demonstrated that a 3D porous structure is a powerful strategy to synchronously achieve high responsivity and transparency and provides a new perspective for designing high-performance,transparent,and self-powered PEC SBUV PDs.
基金This study was financially supported by the National Natural Science Foundation of China (No. 50774010).
文摘Porous Ti compacts with large size and complex shape for biomedical applications were fabricated in the porosity range from 40.5% to 53.8% by controlling gelcasting parameters and sintering conditions. The experimental results show that the total porosity and open porosity of porous titanium compacts gelcast from the Ti slurry with 34 vol.% solid loading and sintered at 1100℃ for 1.5 h are 46.5% and 40.7%, respectively, and the mechanical properties are as follows: compressive strength 158.6 MPa and Young's modulus 8.5 GPa, which are similar to those of human cortical bone and appropriate for implanting purpose.
基金supported by the National Natural Science Foundation of China (No. 50504020)the Chongqing Natural Science Foundation, China (No. 2008BB4051)
文摘Titanium-based porous materials can be used in structural applications and medical implants because of their excellent mechanical properties at elevated temperatures, good corrosion resistance and wonderful biocompatibility. However, most of the methods used to produce the porous metal can only give limited porosity and uncontrollable pore morphologies. In the present study, a newly developed method of powder metallurgy using the space-holder technique was used to fabricate porous titanium with controllable porosity. The morphological features and mechanical properties of the products were fully investigated. The results show that the porosity is in the range of 55%-75%, and the mean pore size, with an average sphericity of -0.72, is 600 μm. The plateau stresses vary between 10 MPa and 35 MPa. As predicted by the Gibson-Ashby model, the plateau stress decreases with increasing porosity.
基金supported by the Scientific Research Project Program of Marmara University (No.FEN-C-YLP-280110-0004)Marmara University for their financial support and the provision of laboratory facilities
文摘The powder space holder (PSH) and powder injection molding (PIM) methods have an industrial competitive advantage because they are capable of the net-shape production of micro-sized porous parts. In this study, micro-porous Ti6Al4V alloy (Ti64) parts were produced by the PSH-PIM process. Ti64 alloy powder and spherical polymethylrnethacrylate (PMMA) particles were used as a space holder material. After molding, binder debinding was performed by thermal method under inert gas. Debinded samples were sintered at 1250℃ for 60min in a vacuum (10-4 Pa). Metallographic studies were conducted to determine densification and the corresponding microstructural changes. The surface of sintered samples was examined by SEM. The compressive stress and elastic modulus of the rificro-porous Ti64 samples were determined. The effects of fraction of PMMA on the properties of sintered micro-porous Ti64 alloy samples were investigated. It was shown that the fraction of PMMA could be controlled to affect the properties of the Ti alloy.
基金The work presented in this paper was fully supported by the following projects:National Natural Science Foundation of China(51775196)Guangdong Province Science and Technology Project(2017B090912003)+3 种基金High-level Personnel Special Support Plan of Guangdong Province(2016TQ03X289)The Fundamental Research Funds for the Central Universities(Project No.2018ZD30)Guangdong Province Science and Technology Project(2017B090911014)Guangzhou Science and Technology Project(201704030097)。
文摘In order to meet the clinical requirements of spine surgery,this paper proposed the exploratory research of computer-aided design and selective laser melting(SLM)fabrication of a bionic porous titanium spine implant.The structural design of the spinal implant is based on CT scanning data to ensure correct matching,and the mechanical properties of the implant are verified by simulation analysis and laser selective melting experiment.The surface roughness of the spinal implant manufactured by SLM without post-processing is Ra 15μm,and the implant is precisely jointed with the photosensitive resin model of the upper and lower spine.The surface micro-hardness of the implant is HV 373,tensile strengthσ_(b)=1238.7 MPa,yield strengthσ_(0.2)=1043.9 MPa,the elongation is 6.43%,and the compressive strength of porous structure under 84.60%porosity is 184.09 MPa,which can meet the requirements of the reconstruction of stable spines.Compared with the traditional implant and intervertebral fusion cage,the bionic porous spinal implant has the advantages of accurate fit,porous bionic structure and recovery of patients,and the ion release experiment proved that implants manufactured by SLM are more suitable for clinical application after certain treatments.The elastic modulus of the sample is improved after heat treatment,mainly because the microstructure of the sample changes fromα’phase toα+βdual-phase after heat treatment.In addition,the design of high-quality bionic porous spinal implants still needs to be optimized for the actual needs of doctors.
基金The project was supported by the National Natural Science Foundation of China (50478062 and 10532070)Open Fund at the Key Laboratory of Urban Security and Disaster Engineering (Beijing University of Technology)Chinese Ministry of Education.
文摘Abstract An analytical solution to the three-dimen-sional scattering and diffraction of plane SV-waves by a saturated hemispherical alluvial valley in elastic half-space is obtained by using Fourier-Bessel series expan-sion technique. The hemispherical alluvial valley with saturated soil deposits is simulated with Biot's dynamic theory for saturated porous media. The following conclusions based on numerical results can be drawn: (1) there are a significant differences in the seismic response simulation between the previous single-phase models and the present two-phase model; (2) the nor-malized displacements on the free surface of the alluvial valley depend mainly on the incident wave angles, the dimensionless frequency of the incident SV waves and the porosity of sediments; (3) with the increase of the incident angle, the displacement distributions become more complicated; and the displacements on the free surface of the alluvial valley increase as the porosity of sediments increases.
文摘The feature of porous titanium is that new bone trabecular tissue could ingrow intoits pores and produce interlocking attachment.The spherical TC<sub>4</sub> powder and titanium fiberwere seperately implanted into the femurs of 24 dogs.The pore size of the samples was0.24mm and their rates of porosity were 40%~50%.After 3 months,the interface shearstrength examined by straight pulling test,was over 4.60±0.36MPa.Scanning electronmicroscopy showed that there were new bone components in the porous layer.Lightmicroscopy also revealed that there were new bone lacunae and their pathways in it.Thedepth of the reforming bone was 3 mm.Interface shear strength of the new bone in the po-rous layer might meet the need of load bearing.Porous materials would prevent the artificialjoint from loosening and thus help to develop a new service clinically.
文摘Porous calcium phosphate ceramics were produced by compression molding using a special mold followed by sintering. The porous calcium phosphate ceramics have three-dimensional and penetrated open pores 380-400μm in diacneter spaced at intervals of 200μm. The layers of the linear penetration pores alternately lay perpendicular to pore direction. The porosity was 59%-65% . The Ca/ P molar ratios of the porous calcium phos phate ceramics range from 1.5 to 1.85. A binder cantaining methyl cellulose was most effective for preparing the powder compact among vinyl acetate, polyvinyl alcohol, starch, stearic acid, methyl cellulose and their mixtures . Stainless steel, polystyrene, nylon and bamboo were used as the long columnar dies for the penetrated open pores. When polystyrene, nylon and bamboo were used as the long columnar male dies, the dies were burned oat during the sintering process. Using stainless steel as the male dies with the removal of the dies before heat treatment resulted in a higher level of densification of the calcium phosphate ceramic.
基金financially supported by the National Natural Science Foundation of China(Nos.51777152 and52202296)the Natural Science Foundation of Shaanxi Province(Nos.2022JZ-01 and 2022JQ-048)。
文摘As a novel structural and functional material,porous titanium and its alloys have been widely used in the aerospace,marine engineering and biomedical fields due to their high corrosion resistance,low density,good biocompatibility and excellent mechanical properties.Therefore,in this paper,a comprehensive review of powder metallurgy(PM)(including additive manufacturing(AM)processes)for fabricating porous titanium is firstly covered in terms of their working principles,capabilities,shortcomings and strengths.Simultaneously,the influencing factors of various methods on final pore structure of porous Ti are involved.Secondly,a summary of the chemical methods(CM)to obtain the porous Ti is also provided,such as dealloying method and reduction method.Finally,the tendency and direction of preparation technology as well as application of porous titanium were prospected.
基金This study was carried out at the 3D Printing Innovation Research Centre of the Ninth People's Hospital Affiliated to the School of Medicine of Shanghai Jiao Tong University,and the authors thank the founding support from the Shanghai Municipal Key Clinical Specialty-Biomedical Materials(shslczdzk06701)the 3-year Action Plan of Shen kang Development Centre(SHDC2020CR2019B)+2 种基金the Huangpu District Industrial Support Fund(XK2020009)the Shanghai Engineering Research Centre of Innovative Orthopedic Instruments and Personalized Medicine(19DZ2250200)the Industry Standard Study on 3D Printing Personalized Titanium Alloy Pelvic Reconstruction Prosthesis(21DZ2201500).
文摘Porous titanium alloy is currently widely used in clinical treatment of orthopaedic diseases for its lower elastic modulus and ability to integrate with bone tissue.At the micro-level,cells can respond to different geometries,and at the macro-level,the geometric design of implants will also affect the biological function of cells.In this study,three kinds of porous scaffolds with square,triangular and circle rod shapes were designed and 3D printed.This study observed the proliferation and differentiation of MC3T3-E1 cells during surface culture of the three types of scaffolds.It also evaluated the characteristics of the three scaffolds by means of compression tests and scanning electron microscopy to provide a reference for the design of porous titanium alloy implants for clinical applications.The trends of cell proliferation and gene expression between the three types of scaffolds were observed after treatment with two inhibitors.The results show that the square rod porous scaffolds have the best proliferative and osteogenic activities,and these findings may be due to differences in piezo-type mechanosensitive ion channel component 1(Piezo1)and Yes-associated protein(YAP)expression caused by the macro-geometric topography.
基金supported by the National Natural Science Foundation of China(Nos.62174085 and 21805136)the Program for Young Changjiang Scholars of the Ministry of Education,the Jiangsu Specially-Appointed Professors Program,the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions(TAPP),the Natural Science Foundation of Jiangsu Province(No.BK20200044)the Startup Foundation for Introducing Talent of NUIST(No.2021r091).
文摘Although metal–organic frameworks have been heavily tested as the anode materials for lithium-ion batteries(LIBs),the poorer conductivity,easy collapse of frameworks,and serious volume expansion limit their further application in LIBs.Herein,we report a facile approach to obtain MXene-encapsulated porous Ni-naphthalene dicarboxylic acid(Ni-NDC)nanosheets by hybridizing ultrathin Ti_(3)C_(2)MXene and three-dimensional(3D)Ni-NDC nanosheet aggregates.In the structure of Ni-NDC/MXene hybrids,the interlayer hydrogen-bond interaction between Ni-NDC and MXene can effectively increase the interlayer spacing and further inhibit the oxidation of pure MXene.Hence,the introduction of MXene(a conductive matrix)could further improve the conductivity of Ni-NDC,avoid self-agglomeration,and buffer the volume expansion of Ni-NDC nanosheets.Benefiting from the synergistic effects between Ni-NDC and MXene,Ni-NDC/MXene hybrid electrode exhibits a reversible discharge capacity(579.8 mA∙h∙g^(−1)at 100 mA∙g^(−1)after 100 cycles)and good long-term cycling performance(310 mA∙h∙g^(−1)at 1 A∙g^(−1)after 500 cycles).
基金Financial support from the National Natural Science Foundation of China(grant nos.22131004,U21A20330,and 52173195)the“111”project(grant no.B18012)+1 种基金Jilin Provincial Department of Science and Technology(grant no.20210508048RQ)the Fundamental Research Funds for the Central Universities are gratefully acknowledged.
文摘Radical-containing porous organic polymers(POPs)have drawn great interest in various applications.However,the synthesis of radical POPs remains challenging due to the unstable nature of organic radicals.Here,a persistent and stable three-dimensional silicon-diacetylene porous organic radical polymer was synthesized via a classic Eglinton homocoupling reaction of tetraethynylsilane.The presence of carbon radicals in this material was confirmed by electron paramagnetic resonance,and its paramagnetic behavior was analyzed by a superconducting quantum interference device.This unique material has a low-lying lowest unoccupied molecular orbital(LUMO)energy level(−5.47 eV)and a small energy gap(ca.1.46 eV),which shows long-term cycling stability and excellent rate capability as an anode material for lithium-ion batteries,demonstrating potential application in energy fields.
基金This work was financially supported by the Natural Science Foundation of Jiangsu Province (No. BK2004129) the Aviation Science Foundation of China (No. 04H52059).
基金financially supported by the National Natural Science Foundation of China (No. 50708037)the National Science Fund for Excellent Young Scholars of China (No. 51522402)+1 种基金the Science and Technology Research Projects in Zhengzhou (No. 141PPTGG388)the National Innovation and Entrepreneurship Training Program of the Undergraduate (No. 201610078034)
文摘Diatomite-based porous ceramics were adopted as carriers to immobilize nano-TiO2 via a hydrolysis-deposition technique. The thermal degradation of as-prepared composites was investigated using thermogravimetric-differential thermal analysis, and the phase and microstructure were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The results indicated that the carriers were encapsulated by nano-TiO2 with a thickness of 300-450 nm. The main crystalline phase of TiO2 calcined at 650~C was anatase, and the average grain size was 8.3 nm. The FT-IR absorption bands at 955.38 cm1 suggested that new chemical bonds among Ti, O, and Si had formed in the composites. The photocatalytic (PC) activity of the composites was investigated un- der UV irradiation. Furthermore, the photodegradation kinetics of formaldehyde was investigated using the composites as the cores of an air cleaner. A kinetics study showed that the reaction rate constants of the gas-phase PC reaction of formaldehyde were k = 0.576 mg'm3·min^-1 and K = 0.048 m3/mg.
基金supported by the Natural Science Research Projects of the Education Department of Henan Province,China(No.2011B610005)
文摘Medical stone-based porous ceramics as a carrier were prepared by ultra-fine grinding and low-temperature sintering method. Nano-TiO~ thin films were loaded on the carrier by chemical liquid deposition method using titanium tetrachloride as a precursor. The micro-morphology and microstructure of the synthesized samples were characterized using X-ray diffraction, scanning electron microscopy with energy dispersive spectrometry, and mercury injection method. The photo-catalytic activity of the TiO2 thin films was investigated by degrading formaldehyde. The main crystalline phase in the TiO2 thin films calcined at 550~C is anatase with the average particle size about 10 nm. The specific surface area of the carrier-coated nano-TiO2 increases from 3.68 to 5.32 m2/g. The formaldehyde removal rate of the TiO2/medical stone-based porous ceramics irradiated under an ultraviolet lamp for 120 min reaches 85.6%.
基金supported by the National Natural Science Foundation of China (Grant numbers: 20676145, U0633003)973 program (No. 2009CB219504)NCET-07-0842
文摘In order to simulate the behavior of gas hydrate formation and decomposition,a 3-Dimension experimental device was built,consisting of a high-pressure reactor with an inner diameter of 300 mm,effective height of 100 mm,and operation pressure of 16 MPa.Eight thermal resistances were mounted in the porous media at different depthes and radiuses to detect the temperature distribution during the hydrate formation/decomposition.To collect the pressure,temperature,and flux of gas production data,the Monitor and Control Generated System(MCGS) was used.Using this device,the formation and decomposition behavior of methane hydrate in the 20 ~ 40 mesh natural sand with salinity of 3.35 wt% was examined.It was found that the front of formation or decomposition of hydrate can be judged by the temperature distribution.The amount of hydrate formation can also be evaluated by the temperature change.During the hydrate decomposition process,the temperature curves indicated that the hydrate in the top and bottom of reactor dissociated earlier than in the inner.The hydrate decomposition front gradually moved from porous media surface to inner and kept a shape of column form,with different moving speed at different surface position.The proper decomposition pressure was also determined.
基金financially supported by the National Natural Science Foundation of China (No. 20907031)
文摘Catalyst recovery is one of the most important aspects that restrict the application of Ti O_2 photocatalyst. In order to reduce restrictions and improve the photocatalytic efficiency, a hierarchical porous Ti O_2 monolith(PTM) with well-defined macroporous and homogeneous mesoporous structure was prepared by using a sol-gel phase separation method. P123 was used as the mesoporous template and graphene oxide was applied to increase the activity and integrity of the monolithic Ti O_2. According to scanning electron microscopy and the Barrett-Joyner-Halenda measurements, PTM_3 is mainly composed of 10 nm anatase crystallines with3.6 nm mesopores and 2-8 μm macropores. Further characterization suggests carbon and nitrogen have been maintained in the PTM during calcinations so as to induce the visible light activity. The PTM with 0.07 wt%graphene oxide dosage shows high efficiency for methyl orange(MO) decolorization under both full spectrum and visible light irradiation(λ >400 nm). Besides, the monolith remains intact and has good photocatalytic stability after four cyclic experiments.
基金financially supported by the National Natural Science Foundation of China(Nos.52004026 and 51725401)the Fundamental Research Funds for the Central Universities,China(No.FRF-TP-18-003C2)。
文摘Selective laser melting(SLM)technology plays an important role in the preparation of porous titanium(Ti)implants with complex structures and precise sizes.Unfortunately,the processing characteristics of this technology,which include rapid melting and solidification,lead to products with high residual stress.Herein,an in situ method was developed to restrain the residual stress and improve the mechanical strength of porous Ti alloys during laser additive manufacturing.In brief,porous Ti6Al4V was prepared by an SLM three-dimensional(3D)printer equipped with a double laser system that could rescan each layer immediately after solidification of the molten powder,thus reducing the temperature gradient and avoiding rapid melting and cooling.Results indicated that double scanning can provide stronger bonding conditions for the honeycomb structure and improve the yield strength and elastic modulus of the alloy.Rescanning with an energy density of 75%resulted in 33.5%–38.0%reductions in residual stress.The porosities of double-scanned specimens were 2%–4%lower than those of singlescanned specimens,and the differences noted increased with increasing sheet thickness.The rescanning laser power should be reduced during the preparation of porous Ti with thick cell walls to ensure dimensional accuracy.