In order to solve the problem of poor formability caused by different materials and properties in the process of tailor-welded sheets forming,a forming method was proposed to change the stress state of tailor-welded s...In order to solve the problem of poor formability caused by different materials and properties in the process of tailor-welded sheets forming,a forming method was proposed to change the stress state of tailor-welded sheets by covering the tailor-welded sheets with better plastic properties overlapping sheets.At the same time,the interface friction effect between the overlapping and tailor-welded sheets was utilized to control the stress magnitude and further improve the formability and quality of the tailor-welded sheets.In this work,the bulging process of the tailor-welded overlapping sheets was taken as the research object.Aluminum alloy tailor-welded overlapping sheets bulging specimens were studied by a combination of finite element analysis and experimental verification.The results show that the appropriate use of interface friction between tailor-welded and overlapping sheets can improve the formability of tailor-welded sheets and control the flow of weld seam to improve the forming quality.When increasing the interface friction coefficient on the side of tailor-welded sheets with higher strength and decreasing that on the side of tailor-welded sheets with lower strength,the deformation of the tailor-welded sheets are more uniform,the offset of the weld seam is minimal,the limit bulging height is maximal,and the forming quality is optimal.展开更多
The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sh...The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.展开更多
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
This study focuses on the risks associated with the on-balance sheet recognition of data resources.At the legal level,disputes over ownership often arise due to unclear data property rights,while privacy protection,cy...This study focuses on the risks associated with the on-balance sheet recognition of data resources.At the legal level,disputes over ownership often arise due to unclear data property rights,while privacy protection,cybersecurity,and cross-border data flows create additional compliance challenges.In terms of recognition,the subjectivity of traditional valuation methods,the lack of active markets,and the rapid depreciation of data value caused by technological iteration hinder reliable measurement.With respect to disclosure,organizations face a dilemma between transparency and confidentiality.Collectively,these issues exacerbate audit risks.It is therefore imperative to establish an appropriate legal,accounting,and auditing framework to mitigate such risks and remove barriers to the proper recognition of data assets on balance sheets.展开更多
Edge cracking is one of the most serious problems in the rolling process of magnesium alloy sheets,which limits its application.In this work,the edge cracking behavior of different initial AZ31 alloy sheets,including ...Edge cracking is one of the most serious problems in the rolling process of magnesium alloy sheets,which limits its application.In this work,the edge cracking behavior of different initial AZ31 alloy sheets,including as-cast(AC),as-rolled(AR)and as-extruded(AE),was systematically investigated and compared under the online heating rolling(O-LHR)process with a single-pass reduction of 50% at 250℃.The results show that both AC and AR sheets exhibit severe edge cracking behavior after the O-LHR.Among them,the AR sheet exhibits the severest edge cracking behavior on the rolling plane(RD-TD)and longitudinal section(RD-ND),which is attributed to the strong basal texture and extremely uneven microstructure with shear bands.While no visible edge crack appears in the AE rolled sheet,which is mainly related to the tilted texture and the more dynamic recrystallization during rolling process.Moreover,it is also found that the micro-cracks of the AC rolled sheet are mainly generated in the local fine-grained area and the twins where recrystallization occurs.In the AR rolled sheet,micro-cracks mainly develop inside the shear bands.Meanwhile,the micro-crack initiation mechanism of AC and AR rolled sheets was also discussed.展开更多
Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and qu...Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and quantification inaccuracy.Here,we report a light-sheet dynamic light-scattering imaging(LSHDSI)system to overcome these shortcomings.LSH-DSI utilizes selected plane illumination for an optical sectioning,while a time-frequency analysis method retrieves blood flow velocity estimates from dynamic changes in the detected light intensity.We have performed imaging experiments with zebrafish embryos to obtain angiographs from the trunk and head regions.The results show that LSH-DSI can capture label-free tomographic images of microvasculature and three-dimensional quantitative maps of local blood flow velocities.展开更多
The deformation behavior of hot-rolled AZ31 magnesium(Mg)alloy sheet was analyzed when subjected to uniaxial tension along its normal direction at temperatures ranging from 100 to 400℃and strain rates ranging from 0....The deformation behavior of hot-rolled AZ31 magnesium(Mg)alloy sheet was analyzed when subjected to uniaxial tension along its normal direction at temperatures ranging from 100 to 400℃and strain rates ranging from 0.5 to 100 mm/min.Based on the stress−strain curves and the dynamic material model,the hot processing map was established,which demonstrates that the power dissipation factor(η)is the most sensitive to strain rate at 400℃via absorption of dislocations.At 400℃,sample at 0.5 mm/min possessesηof 0.89 because of its lower kernel average misorientation(KAM)value of 0.51,while sample at 100 mm/min possessesηof 0.46 with a higher KAM value of 1.147.In addition,the flow stress presents a slight decrease of 25.94 MPa at 10 mm/min compared to that at 100 mm/min and 100℃.The reasons are twofold:a special~34°texture component during 100℃-100 mm/min favoring the activation of basal slip,and dynamic recrystallization(DRX)also providing softening effect to some extent by absorbing dislocations.Difference in activation of basal slip among twin laminas during 100℃-100 mm/min results in deformation inhomogeneity within the grains,which generates stress that helps matrix grains tilt to a direction favorable to basal slip,forming the special~34°texture component.展开更多
During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile str...During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.展开更多
Fe–Ga sheets with large magnetostriction are required for improving the conversion efficiency under the ultra-high frequencymagnetic field. Trace Tb element doping can simultaneously improve the magnetostriction and ...Fe–Ga sheets with large magnetostriction are required for improving the conversion efficiency under the ultra-high frequencymagnetic field. Trace Tb element doping can simultaneously improve the magnetostriction and ductility of Fe–Ga alloy. However, the im-pact of trace Tb doping on the microstructure and magnetostriction of Fe–Ga thin sheets is an open question. In this paper, the effects oftrace Tb addition on the secondary recrystallization and magnetostriction of Fe–Ga thin sheets are systematically studied by comparing thecharacteristics evolution of precipitation, texture, and nanoinclusions. The results indicate that trace Tb addition accelerates the secondaryrecrystallization of Goss texture due to the combined action of the bimodal size distributed precipitates, smaller grains, and more HEGBsin primary recrystallization. After quenching at 900℃, the magnetostriction value in 0.07 at %Tb-doped Fe_(81)Ga_(19) thin sheets increases by 30% to that of Fe_(81)Ga_(19) thin sheets. The increase in magnetostriction is attributed to the decrease in the number of Tb-rich precipitates andthe higher density of the nanometer-sized modified-D0_(3) inclusions induced by the dissolving of trace Tb elements after quenching. Theseresults demonstrate a simple and efficient approach for preparing Fe–Ga thin sheets with a large magnetostrictive coefficient by a combin-ation of trace RE element addition and conventional rolling method.展开更多
Laser-induced graphene(LIG)technology enables the direct writing of functional films for flexible devices.However,the intrinsic amorphous structure,triggered by laser-induced ultrafast kinetics,leads to high sheet res...Laser-induced graphene(LIG)technology enables the direct writing of functional films for flexible devices.However,the intrinsic amorphous structure,triggered by laser-induced ultrafast kinetics,leads to high sheet resistance.Herein,we report a designed laser-stepwise induced graphene(LSIG)method,which sequentially applies focused and defocused laser pulses to polyimide precursors to reduce sheet resistance.In this method,the focused laser pulse induces longitudinal heat penetration and diffusion through the substrate,enabling conversion of polyimide molecules into graphene,while the subsequent defocused pulse facilitates defect healing and crystalline domain growth,achieving a remarkably low sheet resistance of 15Ω·sq^(−1) for LSIG.The LSIG exhibits a decreased defect density and increased crystalline domain from Raman analysis.Compared with existing approaches involving chemical reduction or high-temperature treatment for LIG optimization,the LSIG methodology accomplishes single-step synthesis while maintaining experimental simplicity.Utilizing LSIG technology,we design and fabricate a flexible frequency-selective surface to demonstrate its potential in electromagnetic devices and systems.展开更多
The objective of this work is to investigate the dynamics of a self-propelled undulating sheet in a non-Newtonian electrolyte solution inside a wavy channel under the electroosmotic effect.The electrolyte solution,whi...The objective of this work is to investigate the dynamics of a self-propelled undulating sheet in a non-Newtonian electrolyte solution inside a wavy channel under the electroosmotic effect.The electrolyte solution,which is non-Newtonian,is modeled as a Carreau-Yasuda fluid.The flow generated by a combination of an undulating sheet and electroosmotic effect is obtained by solving the continuity and momentum equations.The electroosmotic body force term is derived using the Poisson-Boltzmann equation for the electric potential.A fourth-order ordinary differential equation for the stream function is solved under the Stokes flow regime.The dynamics of the undulating sheet’s speed and the energy dissipation it,are investigated.The combined effects of electroosmosis and the viscoelastic properties of the ambient fluid on the undulating sheet are discussed.展开更多
The automotive industry increasingly relies on numerical simulations to predict the geometry and forming processes of complex curved parts.Accurate yield stress functions that cover a wide range of stress states,such ...The automotive industry increasingly relies on numerical simulations to predict the geometry and forming processes of complex curved parts.Accurate yield stress functions that cover a wide range of stress states,such as uniaxial tension,equi-biaxial tension,near-plane strain tension,and simple shear,are essential for implementing virtual manufacturing technologies.In this work,a new additive-coupled analytical yield stress function,CPN2025,is proposed to accurately describe plastic anisotropy under various loading conditions.CPN2025 integrates the Poly4 anisotropic yield criterion with the Hosford isotropic yield criterion under a non-associated flow rule.A non-fixed-exponent calibration strategy is introduced,overcoming the limitations of existing yield criteria that typically offer curvature adjustment with only positive or negative correlations.CPN2025 is compared with other non-associated yield functions,including SY2009,CQN2017,and NAFR-Poly4,to evaluate its performance in predicting the plastic anisotropy of DP490,QP1180,AA5754-O,and AA6016-T4.Results show that,while meeting convexity requirements,the additive-coupled approach not only provides greater flexibility than the multiplicative-coupled but also simplifies the acquisition of partial derivative information.CPN2025 delivers the highest accuracy in characterizing anisotropic yield behavior,particularly for near-plane strain tension and simple shear loadings.Additionally,incorporating more uniaxial tensile yield stress-calibrated material parameters significantly improves the prediction capacity of in-plane anisotropic behavior.The use of anisotropic hardening concepts enhances the model's capability to capture the subsequent yield behavior across the entire plastic strain range.展开更多
In this work,AZ31B extruded sheets with mixed-grain microstructures were prepared through extrusion.Samples of mixed-grain microstructure with different morphologies were selected from the AZ31B extruded sheets(referr...In this work,AZ31B extruded sheets with mixed-grain microstructures were prepared through extrusion.Samples of mixed-grain microstructure with different morphologies were selected from the AZ31B extruded sheets(referred to as M1 and M2 samples,respectively).The creep tests were performed on these samples at the temperature range of 150-200℃,and the stress level range of 50-100 MPa.The creep properties and fracture behavior of AZ31 extruded sheets with mixed-grain microstructures were studied.Results showed that the creep properties of the M2 sample always outperformed that of the M1 sample and M1 and M2 samples’creep was dominated by dislocation movement.The creep rate of M2 samples(1.5×10^(-7)±1.1×10^(-10) s^(-1))is an order of magnitude lower than that of M1 samples(4.8×10^(-6)±8.1×10^(-10) s^(-1))at 200℃under 50 MPa The high activity of basal slip and softening mechanism in the M1 sample significantly accelerated creep,resulting in a relatively high creep rate.Moreover,the stress concentration within the M1 sample caused by deformation incompatibility,increased the initiation and propagation of voids,ultimately leading to fracture and poorer creep performance.However,the numerous<10µm fine grains surrounding deformed coarse grains in the M2 sample facilitated better coordination of deformation through dislocation slip,effectively slowing down the initiation of voids during the creep process.Meanwhile,the strain was uniformly distributed within each grain,mitigating stress concentration,inhibiting voids propagation,and contributing to the superior creep resistance of the M2 sample.展开更多
Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady ...Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.展开更多
Bending is a crucial deformation process in metal sheet forming.In this study,the microstructural evolution of a highly ductile Mg–Er–Zr alloy sheet was examined in various bending regions under different bending st...Bending is a crucial deformation process in metal sheet forming.In this study,the microstructural evolution of a highly ductile Mg–Er–Zr alloy sheet was examined in various bending regions under different bending strains using electron backscatter diffraction and optical microscopy.The results show that the Mg–Er–Zr extruded sheet has excellent bending properties,with a failure bending strain of 39.3%,bending yield strength,and ultimate bending strength of 75.1 MPa and 250.5 MPa,respectively.The exceptional bending properties of the Mg–Er–Zr extruded sheets are primarily due to their fine grain size and the formation of rare-earth(RE)textures resulting from Er addition.Specifically,the in-grain misorientation axes(IGMA)and the twinning behaviors in various regions of the specimen during bending were thoroughly analyzed.Due to the polarity of the tensile twins and their low activation stress,a significant number of tensile twins are activated in the compression zone to regulate plastic deformation.The addition of Er weakens the basal texture of the sheet and reduces the critical resolved shear stress difference between non-basal slip and basal slip.Consequently,in the tensile zone,the basal and non-basal slips co-operate to coordinate the plastic deformation,effectively impeding crack initiation and propagation,and thereby enhancing the bending toughness of the Mg–Er–Zr sheet.展开更多
The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic s...The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic strain,contact pressure,and area.The interface promotes lubrication and support when wall angles were≤40°,a 0.5 mm-thin sheet was used,and a 10 mm-large tool radius was employed.This mainly results in micro-plowing and plastic extrusion flow,leading to lower friction coefficient.However,when wall angles exceed 40°,significant plastic strain roughening occurs,leading to inadequate lubrication on the newly formed surface.Increased sheet thickness and decreased tool radius elevate contact pressure.These actions trigger micro-cutting and adhesion,potentially leading to localized scuffing and dimple tears,and higher friction coefficient.The friction mechanisms remain unaffected by the part’s plane curve features.As the forming process progresses,abrasive wear intensifies,and surface morphology evolves unfavorably for lubrication and friction reduction.展开更多
EuB_(6),a magnetic topological semimetal,has attracted considerable attention in recent years due to its rich intriguing physical properties,including a colossal negative magnetoresistance(CNMR)ratio exceeding-80%,a t...EuB_(6),a magnetic topological semimetal,has attracted considerable attention in recent years due to its rich intriguing physical properties,including a colossal negative magnetoresistance(CNMR)ratio exceeding-80%,a topological phase transition and a predicted quantum anomalous Hall effect(QAHE)approaching the two-dimensional(2D)limit.Yet,studies of the influence of the dimensionality approaching 2D on the electronic transport properties of EuB_(6) are still scarce.In this work,EuB_(6) thin sheets with thicknesses ranging from 35μm to 180μm were successfully fabricated through careful mechanical polishing of high-quality EuB_(6) single crystals.The reduced thickness,temperature and magnetic field have a strong influence on the electronic transport properties,including the CNMR and carrier concentration of EuB_(6) thin sheets.As the thickness of EuB_(6) thin sheets decreases from 180μm to 35μm,the magnetization transition temperature and the corresponding suppressing temperature of the Kondo effect decrease from 15.2 K to 10.9 K,while the CNMR ratio increases from-87.2%to-90.8%.Furthermore,the weak antilocalization effect transits to a weak localization effect and the carrier concentration increases by 9.4%at 30 K in a 35μm EuB_(6) thin sheet compared to the value reported for a 180μm thin sheet.Our findings demonstrate an obvious tunable effect of the reduced dimensionality on the transport properties of EuB_(6) along with the temperature and magnetic field,which could provide a route to exploring the QAHE near the 2D limit in EuB_(6) and other topological semimetals.展开更多
The plastic flow behaviors of AA6061-T4 sheets at different temperatures(21-300°C)and strain rates(0.002-4 s^(-1))were studied.Significant nonlinear effects of temperature and strain rate on flow behaviors were r...The plastic flow behaviors of AA6061-T4 sheets at different temperatures(21-300°C)and strain rates(0.002-4 s^(-1))were studied.Significant nonlinear effects of temperature and strain rate on flow behaviors were revealed,as well as underlying micromechanical factors.Phenomenology and machine learning-based constitutive models were developed.Both models were formulated in the framework of a temperature-dependent linear combination regulated by a transition function to capture the evolution of strain-hardening behavior with increasing temperature.Novel mathematical functions for describing temperature and strain rate sensitivities were formulated for the phenomenological constitutive model.The threshold temperature related to microstructure evolution was considered in the modeling.A data-enrichment strategy based on extrapolating experimental data via classical strain hardening laws was adopted to improve neural network training.An efficient inverse identification strategy,focusing solely on the transition function,was proposed to enhance the prediction accuracy of post-necking deformation by both constitutive models.展开更多
The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microsco...The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,transmission electron microscopy,and mechanical property tests.The results indicate that the plane stress fracture toughness of AA7075-T6 cladding sheet can be greatly improved.The plane stress fracture toughness for the longitudinal-transverse(L-T)and transverse-longitudinal(T-L)directions were 117.7 and 94.8 MPa·m^(1/2),respectively,after intermediate annealing at 380°C.This represents an increase of 23.9 MPa·m^(1/2)in the L-T direction and 22.6 MPa·m^(1/2) in the T-L direction compared with the AA7075-T6 cladding sheet without intermediate annealing.Moreover,the tensile strength remains similar under different conditions.Microstructure analysis indicates that intermediate annealing before heat treatment can result in long sub-grains,few recrystallized grain boundaries,and small size precipitates in AA7075-T6 cladding sheets.展开更多
BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive...BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive discussion on the most efficient and cost-effective approaches at the good manufacturing practice(GMP)level.AIM To investigate the culture condition of GMP-compliant DFSC sheets and to compare the properties of DFSC sheets and cell suspensions.METHODS This study explored the optimal conditions for culturing GMP-compliant DFSC sheets,focusing on four key factors:Cell passage,cell concentration,L-ascorbic acid content,and culture duration.We evaluated the characteristics of the cell sheets under varying culture conditions,including cell viability,cell count,appearance,osteogenesis,chondrogenesis,odontogenesis,aging,relative telomere length,and extracellular matrix secretion.A comparison was also made between the periodontal regeneration,osteogenesis,and paracrine capacity of cell sheets cultured under optimal conditions and those of the cell suspensions.RESULTS The GMP-compliant DFSC sheets cultured from passage 4 cells exhibited the highest viability(≥99%,P<0.05)and optimal osteogenic differentiation capacity(optical density≥0.126,P<0.05).When cultured for 10 days,DFSC sheets demonstrated maximal expression of osteogenic,chondrogenic and periostin genes[alkaline phosphatase,Runt-related transcription factor 2,collagen type I,osteopontin,cartilage associated protein,and PERIOSTN(P<0.001);osteocalcin(P<0.01)].Concurrently,they showed the lowest senescent cell count(P<0.01)with no progression to late-stage senescence.At a seeding density of 2500 cells/cm^(2),GMP-compliant DFSC sheets achieved better osteogenic differentiation(P<0.01)and maximal osteogenic,chondrogenic and periostin gene expression(P<0.001),coupled with the highest hydroxyproline secretion(P<0.001)and moderate sulfated glycosaminoglycan production.No statistically significant difference in senescent cell count was observed compared to DFSC sheets at a seeding density of 5000 cells/cm^(2).Supplementation with 25μg/mL L-ascorbic acid significantly enhanced osteogenic gene expression(P<0.001)and elevated hydroxyproline(P<0.01)and sulfated glycosaminoglycan secretion to high ranges.Compared with the cell suspension,the cell sheet demonstrated improved osteogenic,paracrine,and periodontal regenerative capacities in Sprague-Dawley rats.The optimized DFSC sheets demonstrated significantly higher levels of vascular endothelial growth factor and angiopoietin-1(P<0.001)compared to DFSC suspensions,along with enhanced osteogenic induction outcomes(optical density=0.1333±0.01270 vs 0.1007±0.0005774 in suspensions,P<0.05).Following implantation into the rat periodontal defect model,micro-computed tomography analysis revealed superior bone regeneration metrics in the cell sheet group compared to both the cell suspension group and control group(percent bone volume,trabecular thickness,trabecular number),while trabecular spacing exhibited an inverse pattern.CONCLUSION Optimized DFSC sheets cultured under the identified conditions outperform DFSC suspensions.This study contributes to the industrial-scale production of DFSC sheets and establishes a foundation for cell therapy applications.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.52075347,51575364)and the Natural Science Foundation of Liaoning Provincial(No.2022-MS-295)。
文摘In order to solve the problem of poor formability caused by different materials and properties in the process of tailor-welded sheets forming,a forming method was proposed to change the stress state of tailor-welded sheets by covering the tailor-welded sheets with better plastic properties overlapping sheets.At the same time,the interface friction effect between the overlapping and tailor-welded sheets was utilized to control the stress magnitude and further improve the formability and quality of the tailor-welded sheets.In this work,the bulging process of the tailor-welded overlapping sheets was taken as the research object.Aluminum alloy tailor-welded overlapping sheets bulging specimens were studied by a combination of finite element analysis and experimental verification.The results show that the appropriate use of interface friction between tailor-welded and overlapping sheets can improve the formability of tailor-welded sheets and control the flow of weld seam to improve the forming quality.When increasing the interface friction coefficient on the side of tailor-welded sheets with higher strength and decreasing that on the side of tailor-welded sheets with lower strength,the deformation of the tailor-welded sheets are more uniform,the offset of the weld seam is minimal,the limit bulging height is maximal,and the forming quality is optimal.
基金the National Natural Science Founda-tion of China(NSFC,Grant No.42174181)and the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDJ-SSW-DQC010).
文摘The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.
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.
文摘This study focuses on the risks associated with the on-balance sheet recognition of data resources.At the legal level,disputes over ownership often arise due to unclear data property rights,while privacy protection,cybersecurity,and cross-border data flows create additional compliance challenges.In terms of recognition,the subjectivity of traditional valuation methods,the lack of active markets,and the rapid depreciation of data value caused by technological iteration hinder reliable measurement.With respect to disclosure,organizations face a dilemma between transparency and confidentiality.Collectively,these issues exacerbate audit risks.It is therefore imperative to establish an appropriate legal,accounting,and auditing framework to mitigate such risks and remove barriers to the proper recognition of data assets on balance sheets.
基金financially supported by the National Natural Science Foundation of China(Nos.52071036,U2037601)the Guangdong Major Project of Basic and Applied Basic Research,China(No.2020B0301030006)+1 种基金the Independent Research Project of State Key Laboratory of Mechanical Transmissions,China(Nos.SKLMT-ZZKT-2022Z01,SKLMT-ZZKT-2022M12)the Chongqing Science and Technology Commission,China(No.CSTB2022TIAD-KPX0021)。
文摘Edge cracking is one of the most serious problems in the rolling process of magnesium alloy sheets,which limits its application.In this work,the edge cracking behavior of different initial AZ31 alloy sheets,including as-cast(AC),as-rolled(AR)and as-extruded(AE),was systematically investigated and compared under the online heating rolling(O-LHR)process with a single-pass reduction of 50% at 250℃.The results show that both AC and AR sheets exhibit severe edge cracking behavior after the O-LHR.Among them,the AR sheet exhibits the severest edge cracking behavior on the rolling plane(RD-TD)and longitudinal section(RD-ND),which is attributed to the strong basal texture and extremely uneven microstructure with shear bands.While no visible edge crack appears in the AE rolled sheet,which is mainly related to the tilted texture and the more dynamic recrystallization during rolling process.Moreover,it is also found that the micro-cracks of the AC rolled sheet are mainly generated in the local fine-grained area and the twins where recrystallization occurs.In the AR rolled sheet,micro-cracks mainly develop inside the shear bands.Meanwhile,the micro-crack initiation mechanism of AC and AR rolled sheets was also discussed.
基金supported by the following funding sources:Ministry of Education-Singapore MOE2019-T2-2-094 Ministry of Education-Singapore Tier I R-397-000-327-114 ScienceTechnology Project of Jiangsu Province(Grant No.BZ2022056)Biomedical and Health Technology Platform,National University of Singapore(Suzhou)Research Institute.
文摘Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and quantification inaccuracy.Here,we report a light-sheet dynamic light-scattering imaging(LSHDSI)system to overcome these shortcomings.LSH-DSI utilizes selected plane illumination for an optical sectioning,while a time-frequency analysis method retrieves blood flow velocity estimates from dynamic changes in the detected light intensity.We have performed imaging experiments with zebrafish embryos to obtain angiographs from the trunk and head regions.The results show that LSH-DSI can capture label-free tomographic images of microvasculature and three-dimensional quantitative maps of local blood flow velocities.
基金Project(52005362) supported by the National Natural Science Foundation of ChinaProjects(202303021221005,202303021211045) supported by the Natural Science Foundation of Shanxi Province,China+1 种基金Project(202402003) supported by the Patent Commercialization Program of Shanxi Province,ChinaProject supported by the Key Research and Development Plan of Xinzhou City,China。
文摘The deformation behavior of hot-rolled AZ31 magnesium(Mg)alloy sheet was analyzed when subjected to uniaxial tension along its normal direction at temperatures ranging from 100 to 400℃and strain rates ranging from 0.5 to 100 mm/min.Based on the stress−strain curves and the dynamic material model,the hot processing map was established,which demonstrates that the power dissipation factor(η)is the most sensitive to strain rate at 400℃via absorption of dislocations.At 400℃,sample at 0.5 mm/min possessesηof 0.89 because of its lower kernel average misorientation(KAM)value of 0.51,while sample at 100 mm/min possessesηof 0.46 with a higher KAM value of 1.147.In addition,the flow stress presents a slight decrease of 25.94 MPa at 10 mm/min compared to that at 100 mm/min and 100℃.The reasons are twofold:a special~34°texture component during 100℃-100 mm/min favoring the activation of basal slip,and dynamic recrystallization(DRX)also providing softening effect to some extent by absorbing dislocations.Difference in activation of basal slip among twin laminas during 100℃-100 mm/min results in deformation inhomogeneity within the grains,which generates stress that helps matrix grains tilt to a direction favorable to basal slip,forming the special~34°texture component.
基金sponsored by Natural Science Research Project of Anhui Educational Committee(GrantNo.2022AH050810),NationalNatural Science Foundation of China(GrantNos.42402276,41972286,42072309,42102329)State Key Laboratory of Precision Blasting and Hubei Key Laboratory of Blasting Engineering,Jianghan University(No.PBSKL2023A1)the Open Fund of National Center for International Research on Deep Earth Drilling and Resource Development(No.DEDRD-2023-02).
文摘During the construction of bank slopes involving pile driving,ensuring slope stability is crucial.This requires the design of appropriate support systems and a thorough evaluation of the failure mechanisms of pile structures under dynamic loading conditions.Based on the Huarong Coal Wharf project,various support schemes are analyzed using numerical simulation methods to calculate and compare slope stability coefficients.The optimal scheme is then identified.Under the selected support scheme,a numerical model of double-row suspended steel sheet piles is developed to investigate the dynamic response of the pile structures under pile driving loads.A time-history analysis is performed to assess the slope’s dynamic stability.The results show that the maximum displacements of the upper and lower steel sheet pile rows are 2.51 and 3.14 cm,respectively.The maximum principal stresses remain below 20 MPa in both rows,while the maximum von Mises stresses are 20.85 MPa for the upper row and 25.40 MPa for the lower row.The dominant frequencies of the steel sheet pile structures fall between 30 and 35 Hz,with a frequency bandwidth ranging from 0 to 500 Hz.The stability coefficient of the pile structures varies over time during the pile driving process,ultimately reaching a value of 1.26—exceeding the required safety threshold.This research provides practical guidance for designing support systems in wharf piling projects and offers a reliable basis for evaluating the safety performance of steel sheet piles in bank slopes.
基金financially supported by the National Natural Science Foundation of China (No. 52004164)the Funding Program of Science and Technology Department of Liaoning Province, China (No. 2023-MSLH-249)the Funding Program of Education Department of Liaoning P rovince, China (No. LMGD2023018)。
文摘Fe–Ga sheets with large magnetostriction are required for improving the conversion efficiency under the ultra-high frequencymagnetic field. Trace Tb element doping can simultaneously improve the magnetostriction and ductility of Fe–Ga alloy. However, the im-pact of trace Tb doping on the microstructure and magnetostriction of Fe–Ga thin sheets is an open question. In this paper, the effects oftrace Tb addition on the secondary recrystallization and magnetostriction of Fe–Ga thin sheets are systematically studied by comparing thecharacteristics evolution of precipitation, texture, and nanoinclusions. The results indicate that trace Tb addition accelerates the secondaryrecrystallization of Goss texture due to the combined action of the bimodal size distributed precipitates, smaller grains, and more HEGBsin primary recrystallization. After quenching at 900℃, the magnetostriction value in 0.07 at %Tb-doped Fe_(81)Ga_(19) thin sheets increases by 30% to that of Fe_(81)Ga_(19) thin sheets. The increase in magnetostriction is attributed to the decrease in the number of Tb-rich precipitates andthe higher density of the nanometer-sized modified-D0_(3) inclusions induced by the dissolving of trace Tb elements after quenching. Theseresults demonstrate a simple and efficient approach for preparing Fe–Ga thin sheets with a large magnetostrictive coefficient by a combin-ation of trace RE element addition and conventional rolling method.
基金supported by the National Natural Science Foundation of China(Nos.22279097,62401413,and 92163208)the Key R&D Program of Hubei Province(No.2023BAB103)+1 种基金the Foundation of National Key Laboratory of Microwave Imaging Technology,Natural Science Foundation of Hubei Province(Nos.2025AFB038 and 2025AFD120)the Fundamental Research Funds for the Central Universities(WUT:2024IVA031).
文摘Laser-induced graphene(LIG)technology enables the direct writing of functional films for flexible devices.However,the intrinsic amorphous structure,triggered by laser-induced ultrafast kinetics,leads to high sheet resistance.Herein,we report a designed laser-stepwise induced graphene(LSIG)method,which sequentially applies focused and defocused laser pulses to polyimide precursors to reduce sheet resistance.In this method,the focused laser pulse induces longitudinal heat penetration and diffusion through the substrate,enabling conversion of polyimide molecules into graphene,while the subsequent defocused pulse facilitates defect healing and crystalline domain growth,achieving a remarkably low sheet resistance of 15Ω·sq^(−1) for LSIG.The LSIG exhibits a decreased defect density and increased crystalline domain from Raman analysis.Compared with existing approaches involving chemical reduction or high-temperature treatment for LIG optimization,the LSIG methodology accomplishes single-step synthesis while maintaining experimental simplicity.Utilizing LSIG technology,we design and fabricate a flexible frequency-selective surface to demonstrate its potential in electromagnetic devices and systems.
文摘The objective of this work is to investigate the dynamics of a self-propelled undulating sheet in a non-Newtonian electrolyte solution inside a wavy channel under the electroosmotic effect.The electrolyte solution,which is non-Newtonian,is modeled as a Carreau-Yasuda fluid.The flow generated by a combination of an undulating sheet and electroosmotic effect is obtained by solving the continuity and momentum equations.The electroosmotic body force term is derived using the Poisson-Boltzmann equation for the electric potential.A fourth-order ordinary differential equation for the stream function is solved under the Stokes flow regime.The dynamics of the undulating sheet’s speed and the energy dissipation it,are investigated.The combined effects of electroosmosis and the viscoelastic properties of the ambient fluid on the undulating sheet are discussed.
基金financial support from the National Natural Science Foundation of China(Grant Nos.52305396,52371116,and 52375310)support of the research fellowship from the Alexander von Humboldt Foundation.
文摘The automotive industry increasingly relies on numerical simulations to predict the geometry and forming processes of complex curved parts.Accurate yield stress functions that cover a wide range of stress states,such as uniaxial tension,equi-biaxial tension,near-plane strain tension,and simple shear,are essential for implementing virtual manufacturing technologies.In this work,a new additive-coupled analytical yield stress function,CPN2025,is proposed to accurately describe plastic anisotropy under various loading conditions.CPN2025 integrates the Poly4 anisotropic yield criterion with the Hosford isotropic yield criterion under a non-associated flow rule.A non-fixed-exponent calibration strategy is introduced,overcoming the limitations of existing yield criteria that typically offer curvature adjustment with only positive or negative correlations.CPN2025 is compared with other non-associated yield functions,including SY2009,CQN2017,and NAFR-Poly4,to evaluate its performance in predicting the plastic anisotropy of DP490,QP1180,AA5754-O,and AA6016-T4.Results show that,while meeting convexity requirements,the additive-coupled approach not only provides greater flexibility than the multiplicative-coupled but also simplifies the acquisition of partial derivative information.CPN2025 delivers the highest accuracy in characterizing anisotropic yield behavior,particularly for near-plane strain tension and simple shear loadings.Additionally,incorporating more uniaxial tensile yield stress-calibrated material parameters significantly improves the prediction capacity of in-plane anisotropic behavior.The use of anisotropic hardening concepts enhances the model's capability to capture the subsequent yield behavior across the entire plastic strain range.
基金supported by the National Natural Science Foundation of China(52474419,52374395)Natural Science Foundation of Shanxi Province(20210302123135,202303021221143)+3 种基金Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi Province(202104021301022,202204021301009)Central Government Guided Local Science and Technology development projects(YDZJSX20231B003,YDZJSX2021A010)The Ministry of Science and Higher Education of the Russian Federation for financial support under the Megagrant(No.075-15-2022-1133)the National Research Foundation(NRF)grant funded by the Ministry of Science and ICT(2015R1A2A1A01006795)of Korea through the Research Institute of Advanced.
文摘In this work,AZ31B extruded sheets with mixed-grain microstructures were prepared through extrusion.Samples of mixed-grain microstructure with different morphologies were selected from the AZ31B extruded sheets(referred to as M1 and M2 samples,respectively).The creep tests were performed on these samples at the temperature range of 150-200℃,and the stress level range of 50-100 MPa.The creep properties and fracture behavior of AZ31 extruded sheets with mixed-grain microstructures were studied.Results showed that the creep properties of the M2 sample always outperformed that of the M1 sample and M1 and M2 samples’creep was dominated by dislocation movement.The creep rate of M2 samples(1.5×10^(-7)±1.1×10^(-10) s^(-1))is an order of magnitude lower than that of M1 samples(4.8×10^(-6)±8.1×10^(-10) s^(-1))at 200℃under 50 MPa The high activity of basal slip and softening mechanism in the M1 sample significantly accelerated creep,resulting in a relatively high creep rate.Moreover,the stress concentration within the M1 sample caused by deformation incompatibility,increased the initiation and propagation of voids,ultimately leading to fracture and poorer creep performance.However,the numerous<10µm fine grains surrounding deformed coarse grains in the M2 sample facilitated better coordination of deformation through dislocation slip,effectively slowing down the initiation of voids during the creep process.Meanwhile,the strain was uniformly distributed within each grain,mitigating stress concentration,inhibiting voids propagation,and contributing to the superior creep resistance of the M2 sample.
文摘Magnetohydrodynamic(MHD)radiative chemically reactive mixed convection flow of a hybrid nanofluid(Al_(2)O_(3)–Cu/H_(2)O)across an inclined,porous,and stretched sheet is examined in this study,along with its unsteady heat and mass transport properties.The hybrid nanofluid’s enhanced heat transfer efficiency is a major benefit in high-performance engineering applications.It is composed of two separate nanoparticles suspended in a base fluid and is chosen for its improved thermal properties.Thermal radiation,chemical reactions,a transverse magnetic field,surface stretching with time,injection or suction through the porous medium,and the effect of inclination,which introduces gravity-induced buoyancy forces,are all important physical phenomena that are taken into account in the analysis.A system of nonlinear ordinary differential equations(ODEs)is derived from the governing partial differential equations for mass,momentum,and energy by applying suitable similarity transformations.This simplifies the modeling procedure.The bvp4c solver in MATLAB is then used to numerically solve these equations.Different governing parameters modify temperature,concentration,and velocity profiles in graphs and tables.These factors include radiation intensity,chemical reaction rate,magnetic field strength,unsteadiness,suction/injection velocity,inclination angle,and nanoparticle concentration.A complex relationship between buoyancy and magnetic factors makes hybrid nanofluids better at heat transmission than regular ones.Thermal systems including cooling technologies,thermal coatings,and electronic heat management benefit from these findings.
基金supported by the National Natural Science Foundation of China(No.52071037).
文摘Bending is a crucial deformation process in metal sheet forming.In this study,the microstructural evolution of a highly ductile Mg–Er–Zr alloy sheet was examined in various bending regions under different bending strains using electron backscatter diffraction and optical microscopy.The results show that the Mg–Er–Zr extruded sheet has excellent bending properties,with a failure bending strain of 39.3%,bending yield strength,and ultimate bending strength of 75.1 MPa and 250.5 MPa,respectively.The exceptional bending properties of the Mg–Er–Zr extruded sheets are primarily due to their fine grain size and the formation of rare-earth(RE)textures resulting from Er addition.Specifically,the in-grain misorientation axes(IGMA)and the twinning behaviors in various regions of the specimen during bending were thoroughly analyzed.Due to the polarity of the tensile twins and their low activation stress,a significant number of tensile twins are activated in the compression zone to regulate plastic deformation.The addition of Er weakens the basal texture of the sheet and reduces the critical resolved shear stress difference between non-basal slip and basal slip.Consequently,in the tensile zone,the basal and non-basal slips co-operate to coordinate the plastic deformation,effectively impeding crack initiation and propagation,and thereby enhancing the bending toughness of the Mg–Er–Zr sheet.
基金the support of the Key Research and Development Program of Shaanxi Province,China(No.2021GXLH-Z-049)。
文摘The influence of geometric configuration on the friction characteristics during incremental sheet forming of AA5052 was analyzed by integrating surface morphology and its characteristic parameters,along with plastic strain,contact pressure,and area.The interface promotes lubrication and support when wall angles were≤40°,a 0.5 mm-thin sheet was used,and a 10 mm-large tool radius was employed.This mainly results in micro-plowing and plastic extrusion flow,leading to lower friction coefficient.However,when wall angles exceed 40°,significant plastic strain roughening occurs,leading to inadequate lubrication on the newly formed surface.Increased sheet thickness and decreased tool radius elevate contact pressure.These actions trigger micro-cutting and adhesion,potentially leading to localized scuffing and dimple tears,and higher friction coefficient.The friction mechanisms remain unaffected by the part’s plane curve features.As the forming process progresses,abrasive wear intensifies,and surface morphology evolves unfavorably for lubrication and friction reduction.
基金Project supported by the National Key R&D Program of China(Grant No.2022YFA1204100)the National Natural Science Foundation of China(Grant No.62488201)+1 种基金the Chinese Academy of Sciences(Grant Nos.XDB33030000 and YSBR-053)Innovation Program of Quantum Science and Technology(Grant No.2021ZD0302700)。
文摘EuB_(6),a magnetic topological semimetal,has attracted considerable attention in recent years due to its rich intriguing physical properties,including a colossal negative magnetoresistance(CNMR)ratio exceeding-80%,a topological phase transition and a predicted quantum anomalous Hall effect(QAHE)approaching the two-dimensional(2D)limit.Yet,studies of the influence of the dimensionality approaching 2D on the electronic transport properties of EuB_(6) are still scarce.In this work,EuB_(6) thin sheets with thicknesses ranging from 35μm to 180μm were successfully fabricated through careful mechanical polishing of high-quality EuB_(6) single crystals.The reduced thickness,temperature and magnetic field have a strong influence on the electronic transport properties,including the CNMR and carrier concentration of EuB_(6) thin sheets.As the thickness of EuB_(6) thin sheets decreases from 180μm to 35μm,the magnetization transition temperature and the corresponding suppressing temperature of the Kondo effect decrease from 15.2 K to 10.9 K,while the CNMR ratio increases from-87.2%to-90.8%.Furthermore,the weak antilocalization effect transits to a weak localization effect and the carrier concentration increases by 9.4%at 30 K in a 35μm EuB_(6) thin sheet compared to the value reported for a 180μm thin sheet.Our findings demonstrate an obvious tunable effect of the reduced dimensionality on the transport properties of EuB_(6) along with the temperature and magnetic field,which could provide a route to exploring the QAHE near the 2D limit in EuB_(6) and other topological semimetals.
文摘The plastic flow behaviors of AA6061-T4 sheets at different temperatures(21-300°C)and strain rates(0.002-4 s^(-1))were studied.Significant nonlinear effects of temperature and strain rate on flow behaviors were revealed,as well as underlying micromechanical factors.Phenomenology and machine learning-based constitutive models were developed.Both models were formulated in the framework of a temperature-dependent linear combination regulated by a transition function to capture the evolution of strain-hardening behavior with increasing temperature.Novel mathematical functions for describing temperature and strain rate sensitivities were formulated for the phenomenological constitutive model.The threshold temperature related to microstructure evolution was considered in the modeling.A data-enrichment strategy based on extrapolating experimental data via classical strain hardening laws was adopted to improve neural network training.An efficient inverse identification strategy,focusing solely on the transition function,was proposed to enhance the prediction accuracy of post-necking deformation by both constitutive models.
基金the National Key R&D Program of China(Nos.2023YFB3710401,2022YFB3504401)the National Natural Science Foundation of China(Nos.52271094,U1708251)+1 种基金the Key Research and Development Program of Liaoning,China(No.2020JH2/10700003)Qingyuan City Science and Technology Plan Project(No.2023YFJH003),China.
文摘The effects of the inter-annealing process on the microstructure,plane stress fracture toughness,and tensile properties of an AA7075 cladding sheet were investigated using optical microscopy,scanning electron microscopy,electron backscattered diffraction,transmission electron microscopy,and mechanical property tests.The results indicate that the plane stress fracture toughness of AA7075-T6 cladding sheet can be greatly improved.The plane stress fracture toughness for the longitudinal-transverse(L-T)and transverse-longitudinal(T-L)directions were 117.7 and 94.8 MPa·m^(1/2),respectively,after intermediate annealing at 380°C.This represents an increase of 23.9 MPa·m^(1/2)in the L-T direction and 22.6 MPa·m^(1/2) in the T-L direction compared with the AA7075-T6 cladding sheet without intermediate annealing.Moreover,the tensile strength remains similar under different conditions.Microstructure analysis indicates that intermediate annealing before heat treatment can result in long sub-grains,few recrystallized grain boundaries,and small size precipitates in AA7075-T6 cladding sheets.
基金Supported by National Key Research and Development Program of China,No.2021YFA1100600 and No.2022YFA1104400.
文摘BACKGROUND Dental follicle stem cell(DFSC)sheets demonstrate strong extracellular secretion capabilities and efficacy in periodontal regeneration.However,existing methods for producing DFSC sheets lack a comprehensive discussion on the most efficient and cost-effective approaches at the good manufacturing practice(GMP)level.AIM To investigate the culture condition of GMP-compliant DFSC sheets and to compare the properties of DFSC sheets and cell suspensions.METHODS This study explored the optimal conditions for culturing GMP-compliant DFSC sheets,focusing on four key factors:Cell passage,cell concentration,L-ascorbic acid content,and culture duration.We evaluated the characteristics of the cell sheets under varying culture conditions,including cell viability,cell count,appearance,osteogenesis,chondrogenesis,odontogenesis,aging,relative telomere length,and extracellular matrix secretion.A comparison was also made between the periodontal regeneration,osteogenesis,and paracrine capacity of cell sheets cultured under optimal conditions and those of the cell suspensions.RESULTS The GMP-compliant DFSC sheets cultured from passage 4 cells exhibited the highest viability(≥99%,P<0.05)and optimal osteogenic differentiation capacity(optical density≥0.126,P<0.05).When cultured for 10 days,DFSC sheets demonstrated maximal expression of osteogenic,chondrogenic and periostin genes[alkaline phosphatase,Runt-related transcription factor 2,collagen type I,osteopontin,cartilage associated protein,and PERIOSTN(P<0.001);osteocalcin(P<0.01)].Concurrently,they showed the lowest senescent cell count(P<0.01)with no progression to late-stage senescence.At a seeding density of 2500 cells/cm^(2),GMP-compliant DFSC sheets achieved better osteogenic differentiation(P<0.01)and maximal osteogenic,chondrogenic and periostin gene expression(P<0.001),coupled with the highest hydroxyproline secretion(P<0.001)and moderate sulfated glycosaminoglycan production.No statistically significant difference in senescent cell count was observed compared to DFSC sheets at a seeding density of 5000 cells/cm^(2).Supplementation with 25μg/mL L-ascorbic acid significantly enhanced osteogenic gene expression(P<0.001)and elevated hydroxyproline(P<0.01)and sulfated glycosaminoglycan secretion to high ranges.Compared with the cell suspension,the cell sheet demonstrated improved osteogenic,paracrine,and periodontal regenerative capacities in Sprague-Dawley rats.The optimized DFSC sheets demonstrated significantly higher levels of vascular endothelial growth factor and angiopoietin-1(P<0.001)compared to DFSC suspensions,along with enhanced osteogenic induction outcomes(optical density=0.1333±0.01270 vs 0.1007±0.0005774 in suspensions,P<0.05).Following implantation into the rat periodontal defect model,micro-computed tomography analysis revealed superior bone regeneration metrics in the cell sheet group compared to both the cell suspension group and control group(percent bone volume,trabecular thickness,trabecular number),while trabecular spacing exhibited an inverse pattern.CONCLUSION Optimized DFSC sheets cultured under the identified conditions outperform DFSC suspensions.This study contributes to the industrial-scale production of DFSC sheets and establishes a foundation for cell therapy applications.
