To investigate the effect of AlsMn4Gd phase on microstructural and mechanical properties of Mg-Al-Ca magnesium alloy,two Mg-2.5AbCa and Mg-2.5Al2Ca-0.1 Al8Mn4Gd alloys were designed and compared in this work.The resul...To investigate the effect of AlsMn4Gd phase on microstructural and mechanical properties of Mg-Al-Ca magnesium alloy,two Mg-2.5AbCa and Mg-2.5Al2Ca-0.1 Al8Mn4Gd alloys were designed and compared in this work.The results show that a small amount of Gd can significantly refine a-Mg grains and change the morphology of AUCa particles.Indeed,the formed Al8Mn4Gd phase could serve as a heterogeneous nucleation site for the a-Mg grains and AbCa particles.Furthermore,the introduction of Gd not only optimized the mechanical properties of Mg-Al-Ca alloy,but also facilitated the thermal deformation(such as hot rolling).展开更多
Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c...Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c. HEAs is generally low, significantly limiting their practical applications. Recently, the alloying of W has been evidenced to be able to remarkably improve the mechanical properties of f.c.c. HEAs and is becoming a hot topic in the community of HEAs. To date, when W is introduced, multiple strengthening mechanisms, including solid-solution strengthening, precipitation strengthening (μphase,σphase, and b.c.c. phase), and grain-refinement strengthening, have been discovered to be activated or enhanced. Apart from mechanical properties, the addition of W improves corrosion resistance as W helps to form a dense WO_(3) film on the alloy surface. Until now, despite the extensive studies in the literature, there is no available review paper focusing on the W doping of the f.c.c. HEAs. In that context, the effects of W doping on f.c.c. HEAs were reviewed in this work from three aspects, i.e., microstructure,mechanical property, and corrosion resistance. We expect this work can advance the application of the W alloying strategy in the f.c.c. HEAs.展开更多
The compressive yielding phenomenon of titanium alloys is not as focused and sufficiently ascertain as the tensile yielding phenomenon.In the present work,the peculiar compressive yielding behavior and the different d...The compressive yielding phenomenon of titanium alloys is not as focused and sufficiently ascertain as the tensile yielding phenomenon.In the present work,the peculiar compressive yielding behavior and the different dynamic responses of three different initial microstructures(singleβ,clavateβand lamellarβ)were investigated in an attractive metastableβtitanium alloy Ti-5553 using electron microscopes/crystallographic calculation/crystal plastic finite element simulation.Results reveal that the distinct compressive yielding behavior,steep peaks of sudden drop in the initial stage(very small true strain 0.03)of stress loading have appeared in the compression stress-strain curves except for the lamellarβinitial microstructure.Dislocation slip is the essential mechanism of the initial yielding behavior.Interlaced multiple-slip bands formed in the singleβinitial microstructure during the warm deformation process.A small quantity of single slip bands was observed in the deformed clavateβinitial microstructure.The abundant varied nano/ultrafineβsprecipitates were nucleated dynamically and dispersedly in all the three deformed initial microstructures.The multiple-slip bands formation and substantial nanoscaleβsresult in the highest peak of flow stress for singleβinitial microstructure.The compressive slip bands are formed early in the elastic–plastic deformation stage.As the increasing strain,the sample showed a significant compressive bulge,or eventually forming a strong adiabatic shear band or crack.These results are expected to provide a reference for the study of deformation behavior and mechanical properties of metastableβtitanium alloys.展开更多
Magnesium and its alloys are the most investigated materials for solid-state hydrogen storage in the form of metal hydrides,but there are still unresolved problems with the kinetics and thermodynamics of hydrogenation...Magnesium and its alloys are the most investigated materials for solid-state hydrogen storage in the form of metal hydrides,but there are still unresolved problems with the kinetics and thermodynamics of hydrogenation and dehydrogenation of this group of materials.Severe plastic deformation(SPD)methods,such as equal-channel angular pressing(ECAP),high-pressure torsion(HPT),intensive rolling,and fast forging,have been widely used to enhance the activation,air resistance,and hydrogenation/dehydrogenation kinetics of Mg-based hydrogen storage materials by introducing ultrafine/nanoscale grains and crystal lattice defects.These severely deformed materials,particularly in the presence of alloying additives or second-phase nanoparticles,can show not only fast hydrogen absorption/desorption kinetics but also good cycling stability.It was shown that some materials that are apparently inert to hydrogen can absorb hydrogen after SPD processing.Moreover,the SPD methods were effectively used for hydrogen binding-energy engineering and synthesizing new magnesium alloys with low thermodynamic stability for reversible low/room-temperature hydrogen storage,such as nanoglasses,high-entropy alloys,and metastable phases including the high-pressureγ-MgH2 polymorph.This work reviews recent advances in the development of Mg-based hydrogen storage materials by SPD processing and discusses their potential in future applications.展开更多
The dominant hydride precipitates have been well demonstrated to follow two types of orientation relationships(ORs)with Ti matrix:OR1 with{0001}//{001},<1210>//<110>and OR2 with{0001}//{111},<1210>//...The dominant hydride precipitates have been well demonstrated to follow two types of orientation relationships(ORs)with Ti matrix:OR1 with{0001}//{001},<1210>//<110>and OR2 with{0001}//{111},<1210>//<110>.Within the grains with special orientations,the complicated interactions of different hydride variants inside Ti-hydride diffusion layer are characterized in this work.For OR1 hydride layer,the orientations of{1010}plane parallel to the sample surface and a-axis parallel to the normal direction prefer multiple OR1 variants.The orientations favorable for OR2 hydride layer are:{1013}plane parallel to sample surface corresponding to the layer with one OR2 variant dominated and c-axis parallel to the surface normal with multiple OR2 variant layer preferred.Furthermore,{1012}extension twins and{1122}contraction twins are activated to accommodate the OR2 hydride-induced surface expansion and local misfit strain.The stimulation of these two twins is also orientation-dependent:{1012}and{1122}twins are observed in the grains with c-axis parallel to and deviated from the surface normal,respectively.The further variant selection for each twin mode is performed through shear accommodation of hydride-twin pairs.展开更多
Among resources of mesenchymal stem cells, human umbilical cord appears to be a rising source capable of differentiating into all germ layers, reaching and repairing lesion areas, and promoting wound repair, and it ha...Among resources of mesenchymal stem cells, human umbilical cord appears to be a rising source capable of differentiating into all germ layers, reaching and repairing lesion areas, and promoting wound repair, and it has also the capacity to influence the immune response. Human umbilical cord-derived mesenchymal stem cells are considered to be an optimal resource compared with other mesenchymal stem cells sources because they require a non-invasive recovery. All these characteristics allow their use in heterogeneous applications. Human umbilical cord-derived mesenchymal stem cells can regenerate tissues, stimulate angiogenesis, modulate inflammatory pathway signals and recruit endogenous stem cell. Human umbilical cord-derived mesenchymal stem cells suppress mitogen-induced signals and modulate the activation and proliferation of several immune cells, modifying lymphocyte phenotypes activity. In culture, human umbilical cord-derived mesenchymal stem cellss show the capacity to create several tissues such as bone, cartilage, and fat. Human umbilical cord-derived mesenchymal stem cells can be isolated from the different compartments of umbilical cord and processed by using different techniques. Clinical applications of human umbilical cord-derived mesenchymal stem cells include graft-versus-host disease, autoimmune diseases such as Sj?gren's syndrome and diabetes mellitus types 1 and 2, gynecological disorders like endometriosis. Recent studies have shown possible application on rheumatoid arthritis, osteoarthritis, and neuronal degenerative diseases. This review is focused on the resources, molecular profiles, propriety, in vitro characterizations, clinical applications and possible future usage of human umbilical cord-derived mesenchymal stem cells.展开更多
This paper reports on the latest advances in line-field confocal optical cohere nee tomography(LC-OCT),a recently invented imaging technology that now allows the generation of either horizontal(x×y)section images...This paper reports on the latest advances in line-field confocal optical cohere nee tomography(LC-OCT),a recently invented imaging technology that now allows the generation of either horizontal(x×y)section images at an adjustable depth or vertical(x×z)section images at an adjustable lateral position,as well as thre dimensional images.For both two-dimensional imaging modes,images are acquired in real-time,with real-time control of the depth and lateral positions.Three-dimensional(x×y×z)images are acquired from a stack of horizontal section images.The device is in the form of a portable probe.The handle of the probe has a button and a scroll wheel allowing the user to control the imaging modes.Using a supercontinuum laser as a broadband light source and a high numerical microscope objective,an isotropic spatial resolution of^1|im is achieved.The field of view of the three-dimensional images is 1.2 mm×0.5 mm×0.5 mm(x×y×z).Images of skin tissues are presented to demonstrate the potential of the technology in dermatology.展开更多
This article begins explaining the Aristotelian reduction of rhetoric to persuasion, which came to determine Western tradition until modern times. To understand Aristotle＇s methodology the author then wants to discus...This article begins explaining the Aristotelian reduction of rhetoric to persuasion, which came to determine Western tradition until modern times. To understand Aristotle＇s methodology the author then wants to discuss the concept of enthymeme, the ＂rhetorical syllogism,＂ in Aristotle＇s own words. In order to try a realistic critique on the Aristotelian rhetoric, more adequate to a rhetoric of modern law, the author will suggest three epistemological points of departure, three theses, and the three levels of rhetoric that support them.展开更多
基金National Natural Science Foundation of Jiangsu Province(BK20160291)the Natural Science Foundation of the Jiangsu Higher Education Institutions(17KJB430013)+1 种基金the fund of the State Key Laboratory of Solidification Processing in NWPU(SKLSP201822)the Fund of the Jiangsu Planned Projects for Postdoctoral Research Funds(1701006B)
基金the National Science Foundation of China(No.51701010)Beijing Government Funds for the Constructive Project of Central Universities(No.353139535)Thanks to Gaomi Xiangyu Company(Shandong province,China)for the gravity casting.
文摘To investigate the effect of AlsMn4Gd phase on microstructural and mechanical properties of Mg-Al-Ca magnesium alloy,two Mg-2.5AbCa and Mg-2.5Al2Ca-0.1 Al8Mn4Gd alloys were designed and compared in this work.The results show that a small amount of Gd can significantly refine a-Mg grains and change the morphology of AUCa particles.Indeed,the formed Al8Mn4Gd phase could serve as a heterogeneous nucleation site for the a-Mg grains and AbCa particles.Furthermore,the introduction of Gd not only optimized the mechanical properties of Mg-Al-Ca alloy,but also facilitated the thermal deformation(such as hot rolling).
基金financially supported by the National Key R&D Program of China (No.2021YFA1200203)the National Natural Science Foundation of China (Nos.51922026 and 51975111)+1 种基金the Fundamental Research Funds for the Central Universities (No.N2202015,N2002005,and N2105001)the 111 Project of China (No.BP0719037 and B20029)。
文摘Face-centered cubic (f.c.c.) high entropy alloys (HEAs) are attracting more and more attention owing to their excellent strength and ductility synergy, irradiation resistance, etc. However, the yield strength of f.c.c. HEAs is generally low, significantly limiting their practical applications. Recently, the alloying of W has been evidenced to be able to remarkably improve the mechanical properties of f.c.c. HEAs and is becoming a hot topic in the community of HEAs. To date, when W is introduced, multiple strengthening mechanisms, including solid-solution strengthening, precipitation strengthening (μphase,σphase, and b.c.c. phase), and grain-refinement strengthening, have been discovered to be activated or enhanced. Apart from mechanical properties, the addition of W improves corrosion resistance as W helps to form a dense WO_(3) film on the alloy surface. Until now, despite the extensive studies in the literature, there is no available review paper focusing on the W doping of the f.c.c. HEAs. In that context, the effects of W doping on f.c.c. HEAs were reviewed in this work from three aspects, i.e., microstructure,mechanical property, and corrosion resistance. We expect this work can advance the application of the W alloying strategy in the f.c.c. HEAs.
基金supported by National Natural Science Foundation of China(51801156)Major State Research Development Program of China(2016YFB0701305)+1 种基金Natural Science Basic Research Plan in Shaanxi Province of China(2018JQ5035)the Fundamental Research Funds for the Central Universities(G2017KY0310).
文摘The compressive yielding phenomenon of titanium alloys is not as focused and sufficiently ascertain as the tensile yielding phenomenon.In the present work,the peculiar compressive yielding behavior and the different dynamic responses of three different initial microstructures(singleβ,clavateβand lamellarβ)were investigated in an attractive metastableβtitanium alloy Ti-5553 using electron microscopes/crystallographic calculation/crystal plastic finite element simulation.Results reveal that the distinct compressive yielding behavior,steep peaks of sudden drop in the initial stage(very small true strain 0.03)of stress loading have appeared in the compression stress-strain curves except for the lamellarβinitial microstructure.Dislocation slip is the essential mechanism of the initial yielding behavior.Interlaced multiple-slip bands formed in the singleβinitial microstructure during the warm deformation process.A small quantity of single slip bands was observed in the deformed clavateβinitial microstructure.The abundant varied nano/ultrafineβsprecipitates were nucleated dynamically and dispersedly in all the three deformed initial microstructures.The multiple-slip bands formation and substantial nanoscaleβsresult in the highest peak of flow stress for singleβinitial microstructure.The compressive slip bands are formed early in the elastic–plastic deformation stage.As the increasing strain,the sample showed a significant compressive bulge,or eventually forming a strong adiabatic shear band or crack.These results are expected to provide a reference for the study of deformation behavior and mechanical properties of metastableβtitanium alloys.
基金supported in part by the Light Metals Educational Foundation of Japan,and in part by the MEXT,Japan through Grants-in-Aid for Scientific Research on Innovative Areas(Nos.JP19H05176&JP21H00150)the Challenging Research Exploratory(Grant No.JP22K18737)+6 种基金W.J.Botta is grateful to the Brazilian agencies FAPESP(Grant No.2013/05987-8)CNPq(Grant Nos.421181-2018-4 and 307397-2019-0)the financial support and to the Laboratory of Structural Characterization(LCE-DEMa-UFSCar)for general electron microscopy facilities.R.Floriano thanks for the financial support from FAPESP(Grant No.2022/01351-0)support from the French State through the ANR-21-CE08-0034-01 project as well as the program“Investment in the future”operated by the National Research Agency(ANR)referenced under No.ANR-11-LABX-0008-01(Labex DAMAS)support from the National Natural Science Foundation of China(Grant No.52171205)support from the National Natural Science Foundation of China(Grant No.52071157).
文摘Magnesium and its alloys are the most investigated materials for solid-state hydrogen storage in the form of metal hydrides,but there are still unresolved problems with the kinetics and thermodynamics of hydrogenation and dehydrogenation of this group of materials.Severe plastic deformation(SPD)methods,such as equal-channel angular pressing(ECAP),high-pressure torsion(HPT),intensive rolling,and fast forging,have been widely used to enhance the activation,air resistance,and hydrogenation/dehydrogenation kinetics of Mg-based hydrogen storage materials by introducing ultrafine/nanoscale grains and crystal lattice defects.These severely deformed materials,particularly in the presence of alloying additives or second-phase nanoparticles,can show not only fast hydrogen absorption/desorption kinetics but also good cycling stability.It was shown that some materials that are apparently inert to hydrogen can absorb hydrogen after SPD processing.Moreover,the SPD methods were effectively used for hydrogen binding-energy engineering and synthesizing new magnesium alloys with low thermodynamic stability for reversible low/room-temperature hydrogen storage,such as nanoglasses,high-entropy alloys,and metastable phases including the high-pressureγ-MgH2 polymorph.This work reviews recent advances in the development of Mg-based hydrogen storage materials by SPD processing and discusses their potential in future applications.
基金the China Scholarship Council for the financial support。
文摘The dominant hydride precipitates have been well demonstrated to follow two types of orientation relationships(ORs)with Ti matrix:OR1 with{0001}//{001},<1210>//<110>and OR2 with{0001}//{111},<1210>//<110>.Within the grains with special orientations,the complicated interactions of different hydride variants inside Ti-hydride diffusion layer are characterized in this work.For OR1 hydride layer,the orientations of{1010}plane parallel to the sample surface and a-axis parallel to the normal direction prefer multiple OR1 variants.The orientations favorable for OR2 hydride layer are:{1013}plane parallel to sample surface corresponding to the layer with one OR2 variant dominated and c-axis parallel to the surface normal with multiple OR2 variant layer preferred.Furthermore,{1012}extension twins and{1122}contraction twins are activated to accommodate the OR2 hydride-induced surface expansion and local misfit strain.The stimulation of these two twins is also orientation-dependent:{1012}and{1122}twins are observed in the grains with c-axis parallel to and deviated from the surface normal,respectively.The further variant selection for each twin mode is performed through shear accommodation of hydride-twin pairs.
文摘Among resources of mesenchymal stem cells, human umbilical cord appears to be a rising source capable of differentiating into all germ layers, reaching and repairing lesion areas, and promoting wound repair, and it has also the capacity to influence the immune response. Human umbilical cord-derived mesenchymal stem cells are considered to be an optimal resource compared with other mesenchymal stem cells sources because they require a non-invasive recovery. All these characteristics allow their use in heterogeneous applications. Human umbilical cord-derived mesenchymal stem cells can regenerate tissues, stimulate angiogenesis, modulate inflammatory pathway signals and recruit endogenous stem cell. Human umbilical cord-derived mesenchymal stem cells suppress mitogen-induced signals and modulate the activation and proliferation of several immune cells, modifying lymphocyte phenotypes activity. In culture, human umbilical cord-derived mesenchymal stem cellss show the capacity to create several tissues such as bone, cartilage, and fat. Human umbilical cord-derived mesenchymal stem cells can be isolated from the different compartments of umbilical cord and processed by using different techniques. Clinical applications of human umbilical cord-derived mesenchymal stem cells include graft-versus-host disease, autoimmune diseases such as Sj?gren's syndrome and diabetes mellitus types 1 and 2, gynecological disorders like endometriosis. Recent studies have shown possible application on rheumatoid arthritis, osteoarthritis, and neuronal degenerative diseases. This review is focused on the resources, molecular profiles, propriety, in vitro characterizations, clinical applications and possible future usage of human umbilical cord-derived mesenchymal stem cells.
文摘This paper reports on the latest advances in line-field confocal optical cohere nee tomography(LC-OCT),a recently invented imaging technology that now allows the generation of either horizontal(x×y)section images at an adjustable depth or vertical(x×z)section images at an adjustable lateral position,as well as thre dimensional images.For both two-dimensional imaging modes,images are acquired in real-time,with real-time control of the depth and lateral positions.Three-dimensional(x×y×z)images are acquired from a stack of horizontal section images.The device is in the form of a portable probe.The handle of the probe has a button and a scroll wheel allowing the user to control the imaging modes.Using a supercontinuum laser as a broadband light source and a high numerical microscope objective,an isotropic spatial resolution of^1|im is achieved.The field of view of the three-dimensional images is 1.2 mm×0.5 mm×0.5 mm(x×y×z).Images of skin tissues are presented to demonstrate the potential of the technology in dermatology.
文摘This article begins explaining the Aristotelian reduction of rhetoric to persuasion, which came to determine Western tradition until modern times. To understand Aristotle＇s methodology the author then wants to discuss the concept of enthymeme, the ＂rhetorical syllogism,＂ in Aristotle＇s own words. In order to try a realistic critique on the Aristotelian rhetoric, more adequate to a rhetoric of modern law, the author will suggest three epistemological points of departure, three theses, and the three levels of rhetoric that support them.
