This article examines the influence of annealing temperature on fracture toughness and forming limit curves of dissimilar aluminum/silver sheets.In the cold roll bonding process,after brushing and acid washing,the pre...This article examines the influence of annealing temperature on fracture toughness and forming limit curves of dissimilar aluminum/silver sheets.In the cold roll bonding process,after brushing and acid washing,the prepared surfaces are placed on top of each other and by rolling with reduction more than 50%,the bonding between layers is established.In this research,the roll bonding process was done at room temperature,without the use of lubricants and with a 70%thickness reduction.Then,the final thickness of the Ag/Al bilayer sheet reached 350μm by several stages of cold rolling.Before cold rolling,it should be noted that to decrease the hardness created due to plastic deformation,the roll-bonded samples were subjected to annealing heat treatment at 400℃for 90 min.Thus,the final samples were annealed at 200,300 and 400℃for 90 min and cooled in a furnace to examine the annealing temperature effects.The uniaxial tensile and microhardness tests measured mechanical properties.Also,to investigate the fracture mechanism,the fractography of the cross-section was examined by scanning electron microscope(SEM).To evaluate the formability of Ag/Al bilayer sheets,forming limit curves were obtained experimentally through the Nakazima test.The resistance of composites to failure due to cracking was also investigated by fracture toughness.The results showed that annealing increases the elongation and formability of the Ag/Al bilayer sheet while reduces the ultimate tensile strength and fracture toughness.However,the changing trend is not the same at different temperatures,and according to the results,the most significant effect is obtained at 300℃and aluminum layers.It was also determined that by increasing annealing temperature,the fracture mechanism from shear ductile with small and shallow dimples becomes ductile with deep cavities.展开更多
【Objective】Through analyzing the bioaccumulation capacity,subcellular distribution and chemical forms of cadmium(Cd)in Aster subulatus Michx.,this study was to provide reference for revealing the Cd tolerance mechan...【Objective】Through analyzing the bioaccumulation capacity,subcellular distribution and chemical forms of cadmium(Cd)in Aster subulatus Michx.,this study was to provide reference for revealing the Cd tolerance mechanism of A.subulatus Michx.【Method】After cultured for 24 d under the action of Hoagland nutrient solution and gradient Cd concentrations(0,30,60 and 90 mg/L),A.subulatus Michx.were harvested,and its leaf,stem and root were treated by differential centrifugation,chemical reagent extraction,and digested with graphite digester,respectively,then the Cd content in the root,stem and leaf were determined by atomic absorption spectroscopy.【Result】The experimental results indicated that the bioaccumulation capacity of Cd in A.subulatus Michx.was root>stem>leaf,and the maximum Cd concentration in the root,stem and leaf of A.subulatus Michx.were 130.74,78.69 and 56.62 mg/kg(fresh matter),respectively.Most of Cd stored in the cell wall and the soluble fractions of the root and leaf of A.subulatus Michx.,with only a smaller portion Cd in organelle fraction.Analysis result of subcellular Cd content showed that 52.27%-58.61%of Cd for root was mainly stored in the soluble fraction,but 42.10%-63.28%of Cd for leaf was mainly stored in the cell wall fraction.The concentration of pectates and protein integrated-Cd was higher in the root and leaf compared to other chemical forms Cd.Pectates and protein integrated-Cd was the main chemical forms Cd in the root and leaf of A.subulatus Michx.,and their percentages were 68.91%-74.80%and 57.38%-83.80%,respectively.Cd treatment could significantly increase the proportion of water-soluble organic acid Cd from 13.64%to 22.72%in root and undissolved phosphate Cd from 10.02%to 32.78%in leaf with increasing Cd concentration in the culture medium.【Conclusion】The root,stem and leaf of A.subulatus Michx.has strong bioaccumulation capacity to Cd,Cd is primarily stored in the soluble fractions of the root and cell wall fractions of the leaf,and less toxic pectates and protein integrated-Cd is the main chemical forms Cd in the root and leaf of A.subulatus Michx.,this might be the main mechanism of Cd tolerance in A.subulatus Michx.展开更多
To further investigate the forming mechanism and springback characteristics of strips under multi-square punch forming (MSPF) considering partial-unloading effects, a series of concave form ing tests of strips are con...To further investigate the forming mechanism and springback characteristics of strips under multi-square punch forming (MSPF) considering partial-unloading effects, a series of concave form ing tests of strips are conducted on the MSPF machine. This paper aims to reveal the physical mecha nism of the elastic-plastic deformation in the MSPF process considering the effect of the forming ap proaches, and derive appropriate mathematical interpretations. The theoretical model is firstly estab lished to analyse the concave forming mechanism and springback characteristics of the strip, and its accuracy is then validated by experimental data. The forming history and load evolutions are depicted to explore the required forming capacity through the proposed analytical method. Besides, the paramet ric studies are carried out to discuss their effects on the springback of the strip. The results suggest that the deformation paths of the strip are influenced by the forming approach, and the springback of the strip in convex forming is larger than that in concave forming.展开更多
AIM:Regulatory T cells(Tregs)are a specialized subset of CD4^(+)T cells primarily involved in im⁃munosuppressive functions.AMP-activated protein kinase(AMPK)serves as a metabolic sensor that governs the differen⁃tiati...AIM:Regulatory T cells(Tregs)are a specialized subset of CD4^(+)T cells primarily involved in im⁃munosuppressive functions.AMP-activated protein kinase(AMPK)serves as a metabolic sensor that governs the differen⁃tiation,maturation,and immune functions of Tregs through metabolic reprogramming.However,the impact of AMPKα1(the catalytic subunit of AMPK)knockout specifically in Tregs on the host's immune microenvironment remains largely un⁃explored.METHODS:Histological changes in immune organs were assessed using HE staining.The types of immune cells and their relative population percentages in immune organs and blood were quantified through flow cytometry in both AMPKα1flox/flox(AMPKα1^(fl/fl))mice and Treg-specific AMPKα1 knockout mice(AMPKα1^(fl/fl)Foxp3^(cre)mice).RESULTS:Compared to AMPKα1^(fl/fl)mice,the percentage of eosinophils in the bone marrow of AMPKα1^(fl/fl)Foxp3^(cre)mice was significant⁃ly reduced.Additionally,while the thymus of AMPKα1^(fl/fl)Foxp3^(cre)mice exhibited normal structure,both its size and the ratio of thymus weight to body weight were significantly decreased.The knockout of AMPKα1 in Tregs led to a notable reduction in the total percentage of immature double-negative(DN)cells.Consequently,the percentage of CD4^(+)T cells derived from these DN cells also decreased,even though the percentages of DN1 and DN4 cells were higher in the thymus of AMPKα1^(fl/fl)Foxp3^(cre)mice compared to AMPKα1^(fl/fl)mice.Importantly,the proportion of Siglec-F+CD11b^(+)eosinophils in the thymus was significantly lower in AMPKα1^(fl/fl)Foxp3^(cre)mice.Knockout of AMPKα1 in Tregs resulted in a marked increase in the percentage of CD4^(+)T cells in peripheral blood,alongside a decrease in the proportion of mature CD8^(+)T cells.Similarly,the proportion of CD4^(+)T cells in the spleen of AMPKα1^(fl/fl)Foxp3^(cre)mice was elevated compared to AMPKα1^(fl/fl)mice.In contrast,the proportion of neutrophils significantly decreased,while mononuclear cell proportions increased in the spleen of AMPKα1^(fl/fl)Foxp3^(cre)mice.In lymph nodes,the medullary boundaries in AMPKα1^(fl/fl)Foxp3^(cre)mice were blurred,and the lymphoid follicles were missing,a feature not observed in AMPKα1^(fl/fl)mice.Furthermore,the knockout of AMPKα1 in Tregs reduced the CD3^(+)T cell population,particularly the CD8^(+)T cell population,in lymph nodes.Although the mature Treg cell population was significantly lower in AMPKα1^(fl/fl)Foxp3^(cre)mice,the percentage of CD4^(+)T cells was markedly in⁃creased.In contrast,there was no statistically significant difference in granulocyte populations between AMPKα1^(fl/fl)Foxp3^(cre)and AMPKα1^(fl/fl)mice.CONCLUSION:The populations of mature Tregs,CD8^(+)T cells and eosinophils in various im⁃mune organs were significantly altered in mice with Treg-specific AMPKα1 knockout,suggesting a potential remodeling of the host immune microenvironment in response to inflammatory stimuli.展开更多
The aim of this paper is to simulate and study the early moments of the reactive ballistics of a large caliber projectile fired from a gun,combining 0D and 2D axisymmetric Computational Fluid Dynamics(CFD)approaches.F...The aim of this paper is to simulate and study the early moments of the reactive ballistics of a large caliber projectile fired from a gun,combining 0D and 2D axisymmetric Computational Fluid Dynamics(CFD)approaches.First,the methodology is introduced with the development of an interior ballistics(IB)lumped parameter code(LPC),integrating an original image processing method for calculating the specific regression of propellant grains that compose the gun propellant.The ONERA CFD code CEDRE,equipped with a Dynamic Mesh Technique(DMT),is then used in conjunction with the developed LPC to build a dedicated methodology to calculate IB.First results obtained on the AGARD gun and 40 mm gun test cases are in a good agreement with the existing literature.CEDRE is also used to calculate inter-mediate ballistics(first milliseconds of free flight of the projectile)with a multispecies and reactive approach either starting from the gun muzzle plane or directly following IB.In the latter case,an inverse problem involving a Latin hypercube sampling method is used to find a gun propellant configuration that allows the projectile to reach a given exit velocity and base pressure when IB ends.The methodology developed in this work makes it possible to study the flame front of the intermediate flash and depressurization that occurs in a base bleed(BB)channel at the gun muzzle.Average pressure variations in the BB channel during depressurization are in good agreement with literature.展开更多
基金Project(4013311)supported by the National Science Foundation of Iran(INSF)。
文摘This article examines the influence of annealing temperature on fracture toughness and forming limit curves of dissimilar aluminum/silver sheets.In the cold roll bonding process,after brushing and acid washing,the prepared surfaces are placed on top of each other and by rolling with reduction more than 50%,the bonding between layers is established.In this research,the roll bonding process was done at room temperature,without the use of lubricants and with a 70%thickness reduction.Then,the final thickness of the Ag/Al bilayer sheet reached 350μm by several stages of cold rolling.Before cold rolling,it should be noted that to decrease the hardness created due to plastic deformation,the roll-bonded samples were subjected to annealing heat treatment at 400℃for 90 min.Thus,the final samples were annealed at 200,300 and 400℃for 90 min and cooled in a furnace to examine the annealing temperature effects.The uniaxial tensile and microhardness tests measured mechanical properties.Also,to investigate the fracture mechanism,the fractography of the cross-section was examined by scanning electron microscope(SEM).To evaluate the formability of Ag/Al bilayer sheets,forming limit curves were obtained experimentally through the Nakazima test.The resistance of composites to failure due to cracking was also investigated by fracture toughness.The results showed that annealing increases the elongation and formability of the Ag/Al bilayer sheet while reduces the ultimate tensile strength and fracture toughness.However,the changing trend is not the same at different temperatures,and according to the results,the most significant effect is obtained at 300℃and aluminum layers.It was also determined that by increasing annealing temperature,the fracture mechanism from shear ductile with small and shallow dimples becomes ductile with deep cavities.
基金the National Natural Science Foundation of China(62304252)the Youth Innovation Promotion Association of Chinese Academy Sciences(CAS)and IMECAS-HKUST-Joint Laboratory of Microelectronics。
基金Guangxi Natural Science Foundation(2024GXNSFAA010469,2021GXNSFBA196028)Science and Technology Development Project of Guangxi Academy of Agricultural Sciences(Guinongke 2021YT137,Guinongke 2022JM86)。
文摘【Objective】Through analyzing the bioaccumulation capacity,subcellular distribution and chemical forms of cadmium(Cd)in Aster subulatus Michx.,this study was to provide reference for revealing the Cd tolerance mechanism of A.subulatus Michx.【Method】After cultured for 24 d under the action of Hoagland nutrient solution and gradient Cd concentrations(0,30,60 and 90 mg/L),A.subulatus Michx.were harvested,and its leaf,stem and root were treated by differential centrifugation,chemical reagent extraction,and digested with graphite digester,respectively,then the Cd content in the root,stem and leaf were determined by atomic absorption spectroscopy.【Result】The experimental results indicated that the bioaccumulation capacity of Cd in A.subulatus Michx.was root>stem>leaf,and the maximum Cd concentration in the root,stem and leaf of A.subulatus Michx.were 130.74,78.69 and 56.62 mg/kg(fresh matter),respectively.Most of Cd stored in the cell wall and the soluble fractions of the root and leaf of A.subulatus Michx.,with only a smaller portion Cd in organelle fraction.Analysis result of subcellular Cd content showed that 52.27%-58.61%of Cd for root was mainly stored in the soluble fraction,but 42.10%-63.28%of Cd for leaf was mainly stored in the cell wall fraction.The concentration of pectates and protein integrated-Cd was higher in the root and leaf compared to other chemical forms Cd.Pectates and protein integrated-Cd was the main chemical forms Cd in the root and leaf of A.subulatus Michx.,and their percentages were 68.91%-74.80%and 57.38%-83.80%,respectively.Cd treatment could significantly increase the proportion of water-soluble organic acid Cd from 13.64%to 22.72%in root and undissolved phosphate Cd from 10.02%to 32.78%in leaf with increasing Cd concentration in the culture medium.【Conclusion】The root,stem and leaf of A.subulatus Michx.has strong bioaccumulation capacity to Cd,Cd is primarily stored in the soluble fractions of the root and cell wall fractions of the leaf,and less toxic pectates and protein integrated-Cd is the main chemical forms Cd in the root and leaf of A.subulatus Michx.,this might be the main mechanism of Cd tolerance in A.subulatus Michx.
文摘To further investigate the forming mechanism and springback characteristics of strips under multi-square punch forming (MSPF) considering partial-unloading effects, a series of concave form ing tests of strips are conducted on the MSPF machine. This paper aims to reveal the physical mecha nism of the elastic-plastic deformation in the MSPF process considering the effect of the forming ap proaches, and derive appropriate mathematical interpretations. The theoretical model is firstly estab lished to analyse the concave forming mechanism and springback characteristics of the strip, and its accuracy is then validated by experimental data. The forming history and load evolutions are depicted to explore the required forming capacity through the proposed analytical method. Besides, the paramet ric studies are carried out to discuss their effects on the springback of the strip. The results suggest that the deformation paths of the strip are influenced by the forming approach, and the springback of the strip in convex forming is larger than that in concave forming.
基金Supported by the National Natural Science Foundation of China(No.81800423)the Guangdong Medical Science and Technology Research project(No.B2022102)。
文摘AIM:Regulatory T cells(Tregs)are a specialized subset of CD4^(+)T cells primarily involved in im⁃munosuppressive functions.AMP-activated protein kinase(AMPK)serves as a metabolic sensor that governs the differen⁃tiation,maturation,and immune functions of Tregs through metabolic reprogramming.However,the impact of AMPKα1(the catalytic subunit of AMPK)knockout specifically in Tregs on the host's immune microenvironment remains largely un⁃explored.METHODS:Histological changes in immune organs were assessed using HE staining.The types of immune cells and their relative population percentages in immune organs and blood were quantified through flow cytometry in both AMPKα1flox/flox(AMPKα1^(fl/fl))mice and Treg-specific AMPKα1 knockout mice(AMPKα1^(fl/fl)Foxp3^(cre)mice).RESULTS:Compared to AMPKα1^(fl/fl)mice,the percentage of eosinophils in the bone marrow of AMPKα1^(fl/fl)Foxp3^(cre)mice was significant⁃ly reduced.Additionally,while the thymus of AMPKα1^(fl/fl)Foxp3^(cre)mice exhibited normal structure,both its size and the ratio of thymus weight to body weight were significantly decreased.The knockout of AMPKα1 in Tregs led to a notable reduction in the total percentage of immature double-negative(DN)cells.Consequently,the percentage of CD4^(+)T cells derived from these DN cells also decreased,even though the percentages of DN1 and DN4 cells were higher in the thymus of AMPKα1^(fl/fl)Foxp3^(cre)mice compared to AMPKα1^(fl/fl)mice.Importantly,the proportion of Siglec-F+CD11b^(+)eosinophils in the thymus was significantly lower in AMPKα1^(fl/fl)Foxp3^(cre)mice.Knockout of AMPKα1 in Tregs resulted in a marked increase in the percentage of CD4^(+)T cells in peripheral blood,alongside a decrease in the proportion of mature CD8^(+)T cells.Similarly,the proportion of CD4^(+)T cells in the spleen of AMPKα1^(fl/fl)Foxp3^(cre)mice was elevated compared to AMPKα1^(fl/fl)mice.In contrast,the proportion of neutrophils significantly decreased,while mononuclear cell proportions increased in the spleen of AMPKα1^(fl/fl)Foxp3^(cre)mice.In lymph nodes,the medullary boundaries in AMPKα1^(fl/fl)Foxp3^(cre)mice were blurred,and the lymphoid follicles were missing,a feature not observed in AMPKα1^(fl/fl)mice.Furthermore,the knockout of AMPKα1 in Tregs reduced the CD3^(+)T cell population,particularly the CD8^(+)T cell population,in lymph nodes.Although the mature Treg cell population was significantly lower in AMPKα1^(fl/fl)Foxp3^(cre)mice,the percentage of CD4^(+)T cells was markedly in⁃creased.In contrast,there was no statistically significant difference in granulocyte populations between AMPKα1^(fl/fl)Foxp3^(cre)and AMPKα1^(fl/fl)mice.CONCLUSION:The populations of mature Tregs,CD8^(+)T cells and eosinophils in various im⁃mune organs were significantly altered in mice with Treg-specific AMPKα1 knockout,suggesting a potential remodeling of the host immune microenvironment in response to inflammatory stimuli.
基金the French Defense Innovation Agency (AID)the French Procurement Agency for Armament (DGA)ONERA's scientific direction for funding and supporting the present work
文摘The aim of this paper is to simulate and study the early moments of the reactive ballistics of a large caliber projectile fired from a gun,combining 0D and 2D axisymmetric Computational Fluid Dynamics(CFD)approaches.First,the methodology is introduced with the development of an interior ballistics(IB)lumped parameter code(LPC),integrating an original image processing method for calculating the specific regression of propellant grains that compose the gun propellant.The ONERA CFD code CEDRE,equipped with a Dynamic Mesh Technique(DMT),is then used in conjunction with the developed LPC to build a dedicated methodology to calculate IB.First results obtained on the AGARD gun and 40 mm gun test cases are in a good agreement with the existing literature.CEDRE is also used to calculate inter-mediate ballistics(first milliseconds of free flight of the projectile)with a multispecies and reactive approach either starting from the gun muzzle plane or directly following IB.In the latter case,an inverse problem involving a Latin hypercube sampling method is used to find a gun propellant configuration that allows the projectile to reach a given exit velocity and base pressure when IB ends.The methodology developed in this work makes it possible to study the flame front of the intermediate flash and depressurization that occurs in a base bleed(BB)channel at the gun muzzle.Average pressure variations in the BB channel during depressurization are in good agreement with literature.
