Recent research is summarised with an emphasis on the use of Mg alloys for biodegradable medical applications.Mg melt purification using Zr has been shown to provide the opportunity to produce ultra-high-purity Mg all...Recent research is summarised with an emphasis on the use of Mg alloys for biodegradable medical applications.Mg melt purification using Zr has been shown to provide the opportunity to produce ultra-high-purity Mg alloys,which could lead to stainless Mg.Nor's solution may be a good starting model for the study of Mg for biodegradable medical implant applications.A systematic laboratory investigation is needed to elucidate the details of how the corrosion behaviour is controlled by the various constituents of the body fluids.In the evaluation of the Mg corrosion mechanism there is a critical lack of understanding of(i)the amount of hydrogen dissolved in the Mg metal during corrosion,and during anodic polarisation,and(ii)the size film-free area where corrosion occurs,and how to measure this area.In the evaluation of the apparent valence of Mg using an applied anodic current density,for reliable values,it is important to apply a sufficiently large applied current density.The available data are consistent with the slightly modified uni-positive Mg^(+)ion mechanism,which maintains that(i)the surface of Mg is covered by a partially protective film,and the film-free area increases as the potential becomes more positive(i.e.a catalytic activation process),(ii)corrosion occurs preferentially at breaks in the partial protective film,(iii)corrosion at the breaks in the partially protective film involves the uni-positive Mg ion,(iv)undermining of particles occurs when Mg is severely dissolved,and(v)there may be some self-corrosion not covered by these four processes,which may be associated with crevice-like features on a severely corroded surface or hydride dissolution at relatively negative potentials.Self-corrosion might also be possible under condition of essentially uniform corrosion.Mg^(+)has not been experimentally observed.Its existence is postulated as an extremely-short lifetime intermediate in the reaction sequence between metallic Mg and the equilibrium ion Mg^(++).There has been no direct experimental examination展开更多
A review of the literature confirmed that the intrinsic corrosion rate of high-purity Mg as measured by weight-loss is 0.3mm/y in a concentrated chloride solution.Atmospheric corrosion of Mg alloys has produced corros...A review of the literature confirmed that the intrinsic corrosion rate of high-purity Mg as measured by weight-loss is 0.3mm/y in a concentrated chloride solution.Atmospheric corrosion of Mg alloys has produced corrosion rates of Mg-Al alloys an order of magnitude lower than the intrinsic corrosion rate of Mg in a concentrated chloride solution of 0.3 mm/y.The only successful strategy to produce a Mg alloy with a corrosion rate in a concentrated chloride solution substantially less than the intrinsic corrosion rate as measured by weight loss of Mg of 0.3 mm/y has been to improve the protectiveness of the corrosion product film.展开更多
We report that a solo single-guide RNA （sgRNA） seed is capable of guiding Clustered Regularly Interspaced Short Palindromic Repeats （CRISPR）/CRISPR -associated 9 （CRISRP/Casg） to simultaneously edit multiple gen...We report that a solo single-guide RNA （sgRNA） seed is capable of guiding Clustered Regularly Interspaced Short Palindromic Repeats （CRISPR）/CRISPR -associated 9 （CRISRP/Casg） to simultaneously edit multiple genes AtRPL10A, AtRPL10B and AtRPL10C in Arabidopsis. Our results also demonstrate that it is possible to use CRISPR/Cas9 technology to create AtRPLlo triple mutants which otherwise cannot be generated by conventional genetic crossing. Compared to other conventional multiplex CRISPR/Cas systems, a single sgRNA seed has the advantage of reducing off-target gene-editing. Such a gene editing system might be also applicable to modify other homologous genes, or even less-homologous sequences for multiple gene-editing in plants and other organisms.展开更多
Ultra-wide band-gap nitrides have huge potential in micro-and optoelectronics due to their tunable wide band-gap,high breakdown field and energy density,excellent chemical and thermal stability.However,their applicati...Ultra-wide band-gap nitrides have huge potential in micro-and optoelectronics due to their tunable wide band-gap,high breakdown field and energy density,excellent chemical and thermal stability.However,their application has been severely hindered by the low p-doping efficiency,which is ascribed to the ultrahigh acceptor activation energy originated from the low valance band maximum.Here,a valance band modulation mode is proposed and a quantum engineering doping method is conducted to achieve high-efficient p-type ultra-wide band-gap nitrides,in which GaN quantum-dots are buried in nitride matrix to produce a new band edge and thus to tune the dopant activation energy.By non-equilibrium doping techniques,quantum engineering doped AIGaN:Mg with Al content of 60%is successfully fabricated.The Mg activation energy has been reduced to about 21 meV,and the hole concentration reaches higher than 10^(18)cm^(-3)at room temperature.Also,similar activation energies are obtained in AIGaN with other Al contents such as 50%and 70%;indicating the universality of the quantum engineering doping method.Moreover,deep-ultraviolet light-emission diodes are fabricated and the improved performance further demonstrates the validity and merit of the method.With the quantum material growth techniques developing,this method would be prevalently available and tremendously stimulate the promotion of ultra-wide band-gap semiconductor-based devices.展开更多
The effects of Sr additions on the microstructure and corrosion performance of a Mg-Al-RE alloy in 3.5 wt.%Na Cl saturated with Mg(OH)_(2) have been investigated.Microstructure examination reveals that the Sr addition...The effects of Sr additions on the microstructure and corrosion performance of a Mg-Al-RE alloy in 3.5 wt.%Na Cl saturated with Mg(OH)_(2) have been investigated.Microstructure examination reveals that the Sr addition introduces additional intermetallic phases,refines intermetallic networks and dendritic grains,and improves the network continuity.More Al and rare earth elements can be identified in the intermetallics and grain boundaries or inter-dendrite regions under a transmission electron microscope and secondary electron microscope,respectively.On the Sr-containing intermetallic phases and the refined microstructure,the oxide films become more protective,resulting in more corrosion resistant boundary areas and thus dendrite grain grooves.Hence,the presence of large amounts of intermetallics and boundaries can enhance the corrosion performance of the Mg-Al-RE alloy containing Sr.展开更多
Mg atmospheric corrosion is induced by a thin surface aqueous layer. Controlling factors are microgalvanic acceleration between different phases, protection by a continuous second phase distribution, protection by cor...Mg atmospheric corrosion is induced by a thin surface aqueous layer. Controlling factors are microgalvanic acceleration between different phases, protection by a continuous second phase distribution, protection by corrosion products, and degradation of protective layers by aggressive species such as chloride ions. The Mg atmospheric corrosion rate increases with relative humidity (RH) and concentrations of aggressive species. Temperature increases the corrosion rate unless a protective film causes a decrease.O2, SO2 and NO2 accelerate the atmospheric corrosion rate, whereas the corrosion rate is decreased by CO2. The traditional gravimetric method can evaluate effectively the corrosion behavior of Mg alloys.展开更多
UHP Mg-Ge alloys was recently found to provide excellent corrosion resistance.This paper provides new insights on the mechanism of improved corrosion resistance of UHP Mg-Ge alloys in Hanks’solution.The studied UHP M...UHP Mg-Ge alloys was recently found to provide excellent corrosion resistance.This paper provides new insights on the mechanism of improved corrosion resistance of UHP Mg-Ge alloys in Hanks’solution.The studied UHP Mg-0.5Ge and UHP Mg-1Ge alloys showed superior corrosion resistance compared to UHP Mg and WE43,with the Mg-1Ge exhibiting the best corrosion performance.The exceptional corrosion resistance of the UHP alloy is attributed to(i)Mg_(2)Ge’s ability to suppress cathodic kinetics,(ii)Ge’s capability to accelerate the formation of a highly passive layer,and the(iii)low amounts of corrosion-accelerating impurities.展开更多
Federated learning is a promising learning paradigm that allows collaborative training of models across multiple data owners without sharing their raw datasets.To enhance privacy in federated learning,multi-party comp...Federated learning is a promising learning paradigm that allows collaborative training of models across multiple data owners without sharing their raw datasets.To enhance privacy in federated learning,multi-party computation can be leveraged for secure communication and computation during model training.This survey provides a comprehensive review on how to integrate mainstream multi-party computation techniques into diverse federated learning setups for guaranteed privacy,as well as the corresponding optimization techniques to improve model accuracy and training efficiency.We also pinpoint future directions to deploy federated learning to a wider range of applications.展开更多
Shot peening is a surface modification technology with the metal surface nano machine(SNC),which can modify the surface microstructure and extend the fatigue life of Cu-19Ni alloy.The hardness,damage evolution and mec...Shot peening is a surface modification technology with the metal surface nano machine(SNC),which can modify the surface microstructure and extend the fatigue life of Cu-19Ni alloy.The hardness,damage evolution and mechanical properties were investigated and characterized by scanning electron microscope(SEM),laser confocal microscope(LSM)and material surface performance tester(CFT).The results showed that the surface roughness and friction coefficient of Cu-19Ni alloy decreased with the increase of shot peening duration and diameter,while the microhardness and strength increased.Moreover,with the increase in shot peening duration and diameter,SEM observation showed that the fracture dimples became smaller,meanwhile,with the increase of small cleavage planes,shear tearing ridges and the thickness of the surface nano layer,the fracture mode gradually evolved from plastic to brittle fracture.The uniaxial tensile test of shot peened Cu-19Ni alloy was carried out by MTS testing machine combined with digital image correlation technology(DIC).The evolution of Cu-19Ni surface damage was analyzed,and the evolution equations describing the damage of large deformation zone and small deformation zone were established.The effect of shot peening on the damage evolution behavior of Cu-19Ni alloy was revealed.展开更多
基金This research was supported by the Australian Research Council Centre of Excellence Design of Light Alloys.Thanks to the China Scholarship Council to provide a scholarship under the State Scholarship Fund to Fuyong Cao.
文摘Recent research is summarised with an emphasis on the use of Mg alloys for biodegradable medical applications.Mg melt purification using Zr has been shown to provide the opportunity to produce ultra-high-purity Mg alloys,which could lead to stainless Mg.Nor's solution may be a good starting model for the study of Mg for biodegradable medical implant applications.A systematic laboratory investigation is needed to elucidate the details of how the corrosion behaviour is controlled by the various constituents of the body fluids.In the evaluation of the Mg corrosion mechanism there is a critical lack of understanding of(i)the amount of hydrogen dissolved in the Mg metal during corrosion,and during anodic polarisation,and(ii)the size film-free area where corrosion occurs,and how to measure this area.In the evaluation of the apparent valence of Mg using an applied anodic current density,for reliable values,it is important to apply a sufficiently large applied current density.The available data are consistent with the slightly modified uni-positive Mg^(+)ion mechanism,which maintains that(i)the surface of Mg is covered by a partially protective film,and the film-free area increases as the potential becomes more positive(i.e.a catalytic activation process),(ii)corrosion occurs preferentially at breaks in the partial protective film,(iii)corrosion at the breaks in the partially protective film involves the uni-positive Mg ion,(iv)undermining of particles occurs when Mg is severely dissolved,and(v)there may be some self-corrosion not covered by these four processes,which may be associated with crevice-like features on a severely corroded surface or hydride dissolution at relatively negative potentials.Self-corrosion might also be possible under condition of essentially uniform corrosion.Mg^(+)has not been experimentally observed.Its existence is postulated as an extremely-short lifetime intermediate in the reaction sequence between metallic Mg and the equilibrium ion Mg^(++).There has been no direct experimental examination
基金This work was supported by the Australian Research Council Discovery Project DP 170102557。
文摘A review of the literature confirmed that the intrinsic corrosion rate of high-purity Mg as measured by weight-loss is 0.3mm/y in a concentrated chloride solution.Atmospheric corrosion of Mg alloys has produced corrosion rates of Mg-Al alloys an order of magnitude lower than the intrinsic corrosion rate of Mg in a concentrated chloride solution of 0.3 mm/y.The only successful strategy to produce a Mg alloy with a corrosion rate in a concentrated chloride solution substantially less than the intrinsic corrosion rate as measured by weight loss of Mg of 0.3 mm/y has been to improve the protectiveness of the corrosion product film.
基金supported by grants from the National Science Foundation of China(NSFC,31200913)the Ministry of Agriculture of the People’s Republic of China National Transgenic Program(2016ZX08009001-004)+2 种基金the China Scholarship Council(201709645003)NSFC(31370180,31601765)the Zhejiang Provincial Natural Science Foundation(LY15C140006,LY14C010005)
文摘We report that a solo single-guide RNA （sgRNA） seed is capable of guiding Clustered Regularly Interspaced Short Palindromic Repeats （CRISPR）/CRISPR -associated 9 （CRISRP/Casg） to simultaneously edit multiple genes AtRPL10A, AtRPL10B and AtRPL10C in Arabidopsis. Our results also demonstrate that it is possible to use CRISPR/Cas9 technology to create AtRPLlo triple mutants which otherwise cannot be generated by conventional genetic crossing. Compared to other conventional multiplex CRISPR/Cas systems, a single sgRNA seed has the advantage of reducing off-target gene-editing. Such a gene editing system might be also applicable to modify other homologous genes, or even less-homologous sequences for multiple gene-editing in plants and other organisms.
基金the National Natural Science Foundation for Distinguished Young Scholars of China[61725403]National Natural Science Foundation of China[62004196,61922078,61827813,61834008,61922077]+1 种基金Youth Innovation Promotion Association of CAS[Y201945,2017154]Open Project of Suzhou Institute of Nano-Tech and Nano-Bionics,CAS[20YZ10].
文摘Ultra-wide band-gap nitrides have huge potential in micro-and optoelectronics due to their tunable wide band-gap,high breakdown field and energy density,excellent chemical and thermal stability.However,their application has been severely hindered by the low p-doping efficiency,which is ascribed to the ultrahigh acceptor activation energy originated from the low valance band maximum.Here,a valance band modulation mode is proposed and a quantum engineering doping method is conducted to achieve high-efficient p-type ultra-wide band-gap nitrides,in which GaN quantum-dots are buried in nitride matrix to produce a new band edge and thus to tune the dopant activation energy.By non-equilibrium doping techniques,quantum engineering doped AIGaN:Mg with Al content of 60%is successfully fabricated.The Mg activation energy has been reduced to about 21 meV,and the hole concentration reaches higher than 10^(18)cm^(-3)at room temperature.Also,similar activation energies are obtained in AIGaN with other Al contents such as 50%and 70%;indicating the universality of the quantum engineering doping method.Moreover,deep-ultraviolet light-emission diodes are fabricated and the improved performance further demonstrates the validity and merit of the method.With the quantum material growth techniques developing,this method would be prevalently available and tremendously stimulate the promotion of ultra-wide band-gap semiconductor-based devices.
文摘The effects of Sr additions on the microstructure and corrosion performance of a Mg-Al-RE alloy in 3.5 wt.%Na Cl saturated with Mg(OH)_(2) have been investigated.Microstructure examination reveals that the Sr addition introduces additional intermetallic phases,refines intermetallic networks and dendritic grains,and improves the network continuity.More Al and rare earth elements can be identified in the intermetallics and grain boundaries or inter-dendrite regions under a transmission electron microscope and secondary electron microscope,respectively.On the Sr-containing intermetallic phases and the refined microstructure,the oxide films become more protective,resulting in more corrosion resistant boundary areas and thus dendrite grain grooves.Hence,the presence of large amounts of intermetallics and boundaries can enhance the corrosion performance of the Mg-Al-RE alloy containing Sr.
基金supported by the National Natural Science Foundation of China (No. 51731008)the National Environmental Corrosion Platform of China
文摘Mg atmospheric corrosion is induced by a thin surface aqueous layer. Controlling factors are microgalvanic acceleration between different phases, protection by a continuous second phase distribution, protection by corrosion products, and degradation of protective layers by aggressive species such as chloride ions. The Mg atmospheric corrosion rate increases with relative humidity (RH) and concentrations of aggressive species. Temperature increases the corrosion rate unless a protective film causes a decrease.O2, SO2 and NO2 accelerate the atmospheric corrosion rate, whereas the corrosion rate is decreased by CO2. The traditional gravimetric method can evaluate effectively the corrosion behavior of Mg alloys.
基金support of the Australian Research Council through the ARC Research Hub for Advanced Manufacturing of Medical Devices(IH150100024).J.Venezuela is also supported by the Advance Queensland Industry Research Fellowship(AQIRF114-2019RD2).
文摘UHP Mg-Ge alloys was recently found to provide excellent corrosion resistance.This paper provides new insights on the mechanism of improved corrosion resistance of UHP Mg-Ge alloys in Hanks’solution.The studied UHP Mg-0.5Ge and UHP Mg-1Ge alloys showed superior corrosion resistance compared to UHP Mg and WE43,with the Mg-1Ge exhibiting the best corrosion performance.The exceptional corrosion resistance of the UHP alloy is attributed to(i)Mg_(2)Ge’s ability to suppress cathodic kinetics,(ii)Ge’s capability to accelerate the formation of a highly passive layer,and the(iii)low amounts of corrosion-accelerating impurities.
基金partially supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.U21A20516,62076017,and 62141605)the Funding of Advanced Innovation Center for Future Blockchain and Privacy Computing(No.ZF226G2201)+1 种基金the Beihang University Basic Research Funding(No.YWF-22-L-531)the Funding(No.22-TQ23-14-ZD-01-001)and WeBank Scholars Program.
文摘Federated learning is a promising learning paradigm that allows collaborative training of models across multiple data owners without sharing their raw datasets.To enhance privacy in federated learning,multi-party computation can be leveraged for secure communication and computation during model training.This survey provides a comprehensive review on how to integrate mainstream multi-party computation techniques into diverse federated learning setups for guaranteed privacy,as well as the corresponding optimization techniques to improve model accuracy and training efficiency.We also pinpoint future directions to deploy federated learning to a wider range of applications.
基金Funded by Natural Science Foundation of the Inner Mongolia(Nos.2019MS01015,2019MS01017)National Natural Science Foundation of China(No.11002065)。
文摘Shot peening is a surface modification technology with the metal surface nano machine(SNC),which can modify the surface microstructure and extend the fatigue life of Cu-19Ni alloy.The hardness,damage evolution and mechanical properties were investigated and characterized by scanning electron microscope(SEM),laser confocal microscope(LSM)and material surface performance tester(CFT).The results showed that the surface roughness and friction coefficient of Cu-19Ni alloy decreased with the increase of shot peening duration and diameter,while the microhardness and strength increased.Moreover,with the increase in shot peening duration and diameter,SEM observation showed that the fracture dimples became smaller,meanwhile,with the increase of small cleavage planes,shear tearing ridges and the thickness of the surface nano layer,the fracture mode gradually evolved from plastic to brittle fracture.The uniaxial tensile test of shot peened Cu-19Ni alloy was carried out by MTS testing machine combined with digital image correlation technology(DIC).The evolution of Cu-19Ni surface damage was analyzed,and the evolution equations describing the damage of large deformation zone and small deformation zone were established.The effect of shot peening on the damage evolution behavior of Cu-19Ni alloy was revealed.
