Forward extrusion experiments of as-cast AZ31 magnesium alloy were conducted at different temperatures and different extrusion ratios using the as-cast billets with and without homogenizing treatment.The mechanical pr...Forward extrusion experiments of as-cast AZ31 magnesium alloy were conducted at different temperatures and different extrusion ratios using the as-cast billets with and without homogenizing treatment.The mechanical properties of pre-and post-extrusion of the two kinds of billets were investigated.Experimental results show that the mechanical properties of post-extrusion of the two kinds of billets all are obviously improved compared with those of pre-extrusion.The elongation of post-extrusion using the billet with homogenizing is higher than that without homogenizing,but the tensile strength is lower than that without homogenizing.When the extrusion ratio increases,the elongation and tensile strength of post-extrusion of two kinds of billets all will increase obviously.When the extrusion temperature of billet without homogenizing increases,the tensile strength of post-extrusion will decrease obviously and the elongation of post-extrusion will change to a small extent.For the billet with homogenizing,the tensile strength of post-extrusion will decrease in some sort when extrusion temperature increases.展开更多
The microstructure of as-cast Ti-46AI-0.5W-0.5Si alloy exhibits significant microinhomogenetity due to the non-equilibrium solidification and low atom diffusion rate. In order to reduce the adverse effect of this micr...The microstructure of as-cast Ti-46AI-0.5W-0.5Si alloy exhibits significant microinhomogenetity due to the non-equilibrium solidification and low atom diffusion rate. In order to reduce the adverse effect of this microsegregation on plasticity, the microstructure evolution of the Ti-46AI-0.5W-0.5Si alloy homogenized at different temperatures from 1,200 ℃ to 1,320 ℃was investigated, and the optimized process of homogenizing treatment, i.e., annealing treated at 1,280 ℃ and held for 8 h, was determined. Microstructures of both the as-cast and heat treated alloys were observed by means of optical microscope and scanning electron microscopes. Tensile tests at room temperature were conducted on the homogenizing treated fully lamellar Ti-46AI-0.5W-0.5Si alloy with loading axis parallel to the lamellar interface. Results show that, at higher heat treatment temperatures, the W element diffuses sufficiently, the microstructure tends to be more homogeneous, and the profile of the silicide clusters becomes smooth. Heat treating conducted in the a＋y two phase region can keep the columnar grains and the original lamellar orientation within them. The microstructure of the alloy after heat treated in a＋y two phase region exhibits the coexisting morphology of coarse lamellar and thin lamellar. The homogenization process at 1,280℃ for 8 h can significantly reduce the microsegregation, and the elongation at room temperature can increase from 0.48% （as-cast） to 1.34%.展开更多
Homogeneous, high concentrated ceramic suspensions wi th low viscosity are the key controlling factors for the production of ceramic c omponents through colloidal processing. A well-dispersed suspension can be obta in...Homogeneous, high concentrated ceramic suspensions wi th low viscosity are the key controlling factors for the production of ceramic c omponents through colloidal processing. A well-dispersed suspension can be obta ined by choosing suitable dispersant, solvent, particle size distribution etc. B esides these factors, the homogenizing procedure is also a key step. In this paper, reaction sialon suspensions were prepared using 3-wt% KD1 as dis persant in organic media composed of 60-vol% methyletheylketone and 40-vol% et hanol. Different homogenizing procedures have been used and compared, including planetary milling, low energy ball milling and ultrasonic disaggregation. The ef fects of different homogenizing routes and mixing times on the rheology and stab ility of suspensions, and on the microstructure of slip casting green bodies, ha ve been studied. The varying dispersion efficiencies observed could be attribute d to differences in deagglomeration degrees achieved and in adsorption amount of dispersant onto the surface of reaction sialon powders.展开更多
To improve the homogeneity and rolling formability of as-cast AZ91 magnesium,the effects of pre-homogenizing treatment on microstructure evolution,deformation mechanism,mechanical properties and tensile fracture morph...To improve the homogeneity and rolling formability of as-cast AZ91 magnesium,the effects of pre-homogenizing treatment on microstructure evolution,deformation mechanism,mechanical properties and tensile fracture morphology of hot-rolled AZ91 magnesium alloy were studied.The results showed that the amount of coarseβ-Mg17Al12 phase decreases dramatically,being distributed along the grain boundaries as small strips after homogenizing.Twining plays a dominant role in the deformation mechanism of AZ91 alloys in the experimental condition,while dynamic recrystallization(DRX)considerably occurred in homogenized-rolled alloys,contributed to microstructure uniformity andβ-Mg17Al12 phase precipitated refinement.The tensile strength of homogenized-rolled AZ91 alloys increases dramatically with elongation declining slightly in contrast to homogenized alloys.The fracture surface of homogenized-rolled specimen exhibits more ductile fracture with the manifestation of a large amount of dimples distributing higher density in matrix,while the micro cracks are prone to initiate around the Mg/Mg17Al12 phase interface and grain boundaries owing to the fragile interface bonding of two phases.展开更多
Objective To quantitatively evaluate the contamination area and risk of a live pathogen during tissue homogenization by either ultrasonic processor or tissue disperser.Methods A recombinant Herpes Simplex Virus（rHSV...Objective To quantitatively evaluate the contamination area and risk of a live pathogen during tissue homogenization by either ultrasonic processor or tissue disperser.Methods A recombinant Herpes Simplex Virus（rHSV） containing GFP gene was used as the index virus,and fresh liver tissue from healthy mice was used as simulated specimen.After 10% liver homogenate was mixed with rHSV（100 TCID50/0.1 mL） in a 5 mL tube,the stability of rHSV in liver homogenate and influences of an ultrasonic processor and a tissue disperser on viral infectivity were determined by GFP expressions in cell cultures.The contaminating areas of live viruses during homogenization were evaluated by a cell culture-based sedimentary.The contamination radii were counted by measurement of the distance between the operator and the farthest GFP positive well.Results The infectivity of rHSV in 10% liver homogenate maintained almost unchanged after it was incubated at room temperature for 30 min.Treatment with an ultrasonic processor clearly dropped down the virus infectivity,while a disperser not.Obvious spills and slashes of live viruses were observed in processes of homogenization with those two apparatuses.The contamination radii are positively related with sample volume,output energy of operator and handling time.Conclusion Homogenizing infectious samples with an ultrasonic processor and a tissue disperser at commonly used conditions caused obvious spills and splashes of live viruses,which possesses high risk to induce Laboratory acquired infections（LAIs）.展开更多
Objective To optimize the extraction technology of the active component, rosmarinic acid, an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid, in perilla oil meal for the first time by a new homogenizing techn...Objective To optimize the extraction technology of the active component, rosmarinic acid, an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid, in perilla oil meal for the first time by a new homogenizing technology called smashing tissue extraction (STE). Methods Orthogonal design was used to optimize the extraction condition. The content of rosmarinic acid was quantified from the methanol crude extract with the help of HPLC. Results The optimization of STE process to get rosmarinic acid from the perilla oil meal was the ratio of liquid to solid material at 10:1 and the power of extraction at 150 V, extracting twice (2 min for each time). Conclusion STE could be applied to extracting the active ingredients from the oil meals due to its high extraction efficiency. This new homogenizing technology has advantages on saving extraction time, raising extraction efficiency, and maintaining the temperature sensitive constituents.展开更多
In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order hom...In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.展开更多
As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal...As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions.Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces.However,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials.From the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear surfaces.The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized.Starting from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed.It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.展开更多
Porous organic cages(POCs)with permanent porosity and excellent host–vip property hold great potentials in regulating ion transport behavior,yet their feasibility as solid-state electrolytes has never been testifie...Porous organic cages(POCs)with permanent porosity and excellent host–vip property hold great potentials in regulating ion transport behavior,yet their feasibility as solid-state electrolytes has never been testified in a practical battery.Herein,we design and fabricate a quasi-solid-state electrolyte(QSSE)based on a POC to enable the stable operation of Li-metal batteries(LMBs).Benefiting from the ordered channels and cavity-induced anion-trapping effect of POC,the resulting POC-based QSSE exhibits a high Li+transference number of 0.67 and a high ionic conductivity of 1.25×10^(−4) S cm^(−1) with a low activation energy of 0.17 eV.These allow for homogeneous Li deposition and highly reversible Li plating/stripping for over 2000 h.As a proof of concept,the LMB assembled with POC-based QSSE demonstrates extremely stable cycling performance with 85%capacity retention after 1000 cycles.Therefore,our work demonstrates the practical applicability of POC as SSEs for LMBs and could be extended to other energy-storage systems,such as Na and K batteries.展开更多
Social interaction with peer pressure is widely studied in social network analysis.Game theory can be utilized to model dynamic social interaction,and one class of game network models assumes that people’s decision p...Social interaction with peer pressure is widely studied in social network analysis.Game theory can be utilized to model dynamic social interaction,and one class of game network models assumes that people’s decision payoff functions hinge on individual covariates and the choices of their friends.However,peer pressure would be misidentified and induce a non-negligible bias when incomplete covariates are involved in the game model.For this reason,we develop a generalized constant peer effects model based on homogeneity structure in dynamic social networks.The new model can effectively avoid bias through homogeneity pursuit and can be applied to a wider range of scenarios.To estimate peer pressure in the model,we first present two algorithms based on the initialize expand merge method and the polynomial-time twostage method to estimate homogeneity parameters.Then we apply the nested pseudo-likelihood method and obtain consistent estimators of peer pressure.Simulation evaluations show that our proposed methodology can achieve desirable and effective results in terms of the community misclassification rate and parameter estimation error.We also illustrate the advantages of our model in the empirical analysis when compared with a benchmark model.展开更多
Photoredox catalysis has made significant advances in stateof-the-art chemical synthesis,drawing energy from inexhaustible light and enabling various organic transformations to occur under mild reaction conditions.Ove...Photoredox catalysis has made significant advances in stateof-the-art chemical synthesis,drawing energy from inexhaustible light and enabling various organic transformations to occur under mild reaction conditions.Over the past few years,a variety of homogeneous and heterogeneous photocatalysts have been applied in the photoredox catalysis.Heterogeneous photoredox catalysis offers advantages such as easy separation and superior recyclability compared to homogeneous counterparts,although homogenous catalysts are usually associated with higher activities and selectivity.From a practical perspective,an optimal photoredox catalytic system would integrate the advantages of both homogeneous and heterogeneous cases.展开更多
The acoustic wave propagation in gas-saturated double-porosity materials composed of a microporous matrix and mesopores with arrays of plate-type resonators is investigated.A macroscopic description,established with t...The acoustic wave propagation in gas-saturated double-porosity materials composed of a microporous matrix and mesopores with arrays of plate-type resonators is investigated.A macroscopic description,established with the two-scale asymptotic homogenization method,evidences the combined effect of inner resonances on the acoustic properties of the respective effective visco-thermal fluid.One type of resonance originates from strong pore-scale fluid-structure interaction,while the other one arises from pressure diffusion.These phenomena respectively cause weakly and highly damped resonances,which are activated by internal momentum or mass sources,and can largely influence,depending on the material's morphology,either the effective fluid's dynamic density,compressibility,or both.We introduce semi-analytical models to illustrate the key effective properties of the studied multiscale metamaterials.The results provide insights for the bottom-up design of multiscale acoustic metamaterials with exotic behaviors,such as the negative,very slow,or supersonic phase velocity,as well as sub-wavelength bandgaps.展开更多
Based on microstructure analysis,diffusion theory,and hot deformation experiments,the solidification microstructure and element segregation of the Alloy 625 Plus ingot,the diffusion kinetics of Ti,Nb,and Mo during hom...Based on microstructure analysis,diffusion theory,and hot deformation experiments,the solidification microstructure and element segregation of the Alloy 625 Plus ingot,the diffusion kinetics of Ti,Nb,and Mo during homogenization and the hot deformation behavior of the homogenized ingot were investigated in this study.The results indicate that:(1)the solidified ingot exhibits a typical dendritic microstructure,and significant element segregation occurs,leading to the presence of Ti,Nb,and Mo-rich precipitates in the interdendritic region;(2)Following homogenization,the degree of element segregation in the ingot is significantly reduced.The diffusion coefficients(D)of Ti,Nb,and Mo under various homogenization conditions were calculated.Subsequently,the diffusion constants(D_(0))and activation energies(Q)of Ti,Nb,and Mo were obtained to be 0.01432,0.00397 and 0.00195 cm^(2)/s and 244.851,230.312,and 222.125 kJ/mol,respectively.Finally,the diffusion kinetics formulas for Ti,Nb,and Mo in Alloy 625 Plus were established.After homogenization at 1220℃for 8 h,the alloy exhibits low deformation resistance,a high degree of recrystallization,and optimal deformation coordination ability.Therefore,this represents a rational single-stage homogenization process.展开更多
The utilization of self-assembled monolayers(SAMs)has significantly elevated the power conversion efficiency(PCE)of inverted perovskite solar cells(PSCs).However,the inherent hydrophobicity of these SAMs poses challen...The utilization of self-assembled monolayers(SAMs)has significantly elevated the power conversion efficiency(PCE)of inverted perovskite solar cells(PSCs).However,the inherent hydrophobicity of these SAMs poses challenges in the subsequent printing of perovskite films in PSC upscaling.In this work,we incorporated a multifunctional additive,dimethyl suberimidate dihydrochloride(DMSCl_(2)),into the perovskite precursor to enhance the quality of the blade-coated perovskite film on the SAM interlayer.Characterizations revealed that the function groups of the imino(N-H)and methoxy(CH_(3)O-)DMSCl_(2) facilitate both bonding between perovskite precursor and SAM molecule(Me-4PACz),which facilitates the large-area printing of perovskite film.These interactions also provide effective passivation within the perovskite films and interface defects of PSCs.As a result,a significantly enhanced PCE from 16.62% to 20.37% was obtained for the printed perovskite solar module(93.10 cm^(2))and 25.27% for the small device(0.09 cm^(2)).Remarkable stability was achieved with 93.3% of their initial PCE after 1000 h of continuous maximum power point(MPP)tracking.This report suggests that multifunctional additive doping provides a convenient route for the upscaling of perovskite solar cells with SAM interlayers.展开更多
The multiscale computational method with asymptotic analysis and reduced-order homogenization(ROH)gives a practical numerical solution for engineering problems,especially composite materials.Under the ROH framework,a ...The multiscale computational method with asymptotic analysis and reduced-order homogenization(ROH)gives a practical numerical solution for engineering problems,especially composite materials.Under the ROH framework,a partition-based unitcell structure at the mesoscale is utilized to give a mechanical state at the macro-scale quadrature point with pre-evaluated influence functions.In the past,the“1-phase,1-partition”rule was usually adopted in numerical analysis,where one constituent phase at the mesoscale formed one partition.The numerical cost then is significantly reduced by introducing an assumption that the mechanical responses are the same all the time at the same constituent,while it also introduces numerical inaccuracy.This study proposes a new partitioning method for fibrous unitcells under a reduced-order homogenization methodology.In this method,the fiber phase remains 1 partition,but the matrix phase is divided into 2 partitions,which refers to the“12”partitioning scheme.Analytical elastic influence+functions are derived by introducing the elastic strain energy equivalence(Hill-Mandel condition).This research also obtains the analytical eigenstrain influence functions by alleviating the so-called“inclusion-locking”phenomenon.In addition,a numerical approach to minimize the error of strain energy density is introduced to determine the partitioning of the matrix phase.Several numerical examples are presented to compare the differences among direct numerical simulation(DNS),“11”,and“12”partitioning schemes.The numerical simulations show improved++numerical accuracy by the“12”partitioning scheme.展开更多
The photoinduced ligand-to-metal charge transfer(LMCT)process has been extensively investigated,however,the recovery of photocatalysts has remained a persistent challenge in the field.In light of this issue,a novel ap...The photoinduced ligand-to-metal charge transfer(LMCT)process has been extensively investigated,however,the recovery of photocatalysts has remained a persistent challenge in the field.In light of this issue,a novel approach involving the development of iron-based ionic liquids as photocatalysts has been pursued for the first time,with the goal of simultaneously facilitating the LMCT process and addressing the issue of photocatalyst recovery.Remarkably,the iron-based ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate(C_(4)mim-Fe Cl_(4))demonstrates exceptional recyclability and stability for the photocatalytic hydroacylation of olefins.This study will pave the way for new approaches to photocatalytic organic synthesis using ionic liquids as recyclable photocatalysts.展开更多
To investigate the instability mechanisms of heterogeneous geological structures in goaf area roofs,three-point bending tests(TPBT)and numerical simulations are performed on composite coal-rock(CCR).Acoustic emission(...To investigate the instability mechanisms of heterogeneous geological structures in goaf area roofs,three-point bending tests(TPBT)and numerical simulations are performed on composite coal-rock(CCR).Acoustic emission(AE)monitoring is employed to analyze key parameters,establishing a multiparameter quantitative system for CCR fracture processes.The impact of lithological homogeneity on fracture evolution and energy migration is examined.Results show that CCR exhibits a three-stage mechanical response:weak contact,strong contact,and post-peak stages,each with distinct crack evolution patterns.A positive correlation is found between lithological homogeneity and tensile crack proportion.No significant correlation is observed between AE average frequency(AF)and AE counts across different lithological CCR;however,peak frequency(PF)displays clear lithology-dependent characteristics.The regulatory effect of the rock homogeneity coefficient(φ)on crack deriva tion mechanisms is quantfied,yielding mathematical relationships between fracture strength(f),crack propagation path angle(β),crack fractal dimension(D),andφ.The study highlights how different fracture modes alter energy migration pathways,confirming the coupling effect of grain distribution on mechanical response and crack propagation,and the influence of parameterφon critical energy release zones.These findings offer new insights into CCR failure mechanisms for mining safety.展开更多
TC4 titanium alloy(Ti-6Al-4V),known for its excellent specific strength,corrosion resistance,and weldability,is extensively applied in aerospace,marine engineering,and advanced manufacturing.This study focuses on the ...TC4 titanium alloy(Ti-6Al-4V),known for its excellent specific strength,corrosion resistance,and weldability,is extensively applied in aerospace,marine engineering,and advanced manufacturing.This study focuses on the microstructural uniformity and mechanical properties of TC4 ingots fabricated via the electron-beam cold hearth melting(EBCHM)process.A comprehensive analysis was performed using optical microscopy,scanning electron microscopy,electron backscatter diffraction,and energy-dispersive spectroscopy to investigate the ingot’s morphology,α-phase lamellar structure,and elemental distribution.Mechanical characterization included tensile testing,and microhardness and impact toughness assessments.Results reveal that EBCHM produces a well-defined and homogeneous microstructure,with the averageαlamellae thickness varying between 1.53 and 1.71μm and minimal fluctuations across the ingot regions,indicating high process consistency.Major alloying elements(Al and V)and impurity elements(O,N,H,C,and Fe)are evenly distributed,with no observable macrosegregation.The mechanical properties are stable and reliable,with a yield strength of 694.6-701.2 MPa,a tensile strength of 711.1-716.6 MPa,an elongation of 3.35%-3.84%,and an average impact toughness of 94.7 J/cm^(2).These results provide valuable data and technical references for the application of EBCHM in manufacturing premium-quality Ti-6Al-4V ingots.展开更多
Enhancing homogenization efficiency and hot-workability is the key issue for wrought superalloys in the industry.A novel approach for simultaneous accelerating the homogenization kinetics and improving hot-workability...Enhancing homogenization efficiency and hot-workability is the key issue for wrought superalloys in the industry.A novel approach for simultaneous accelerating the homogenization kinetics and improving hot-workability via a simple way of prior hot-deformation was proposed,which was not widely accepted for wrought superalloys.The homogenization efficiency is increased by 40%-70%via performing 10%-20%prior hot-deformation.Both theoretical and experimental analyses revealed that the increment in homogenization efficiency is mainly attributed to the decrease in interdendritic-segregation spacing,and thus the necessary diffusion distance,rather than that of dislocations.In addition,dynamic and static recrystallizations occurred during the prior hot-deformation and diffusion-annealing processes,and the grains were significantly refined even after the homogenization.Furthermore,the size of the precipitates was refined as well.These enhanced the hot-workability of the homogenized ingot for the subsequent cogging process.展开更多
Higher-order modes of the neutron diffusion/transport equation can be used to study the temporal behavior of nuclear reactors and can be applied in modal analysis, transient analysis, and online monitoring of the reac...Higher-order modes of the neutron diffusion/transport equation can be used to study the temporal behavior of nuclear reactors and can be applied in modal analysis, transient analysis, and online monitoring of the reactor core. Both the deterministic method and the Monte Carlo(MC) method can be used to solve the higher-order modes. However, MC method, compared to the deterministic method, faces challenges in terms of computational efficiency and α mode calculation stability, whereas the deterministic method encounters issues arising from homogenization-related geometric and energy spectra adaptation.Based on the higher-order mode diffusion calculation code HARMONY, we developed a new higher-order mode calculation code, HARMONY2.0, which retains the functionality of computing λ and α higher-order modes from HARMONY1.0, but enhances the ability to treat complex geometries and arbitrary energy spectra using the MC-deterministic hybrid two-step strategy. In HARMONY2.0, the mesh homogenized multigroup constants were obtained using OpenMC in the first step,and higher-order modes were then calculated with the mesh homogenized core diffusion model using the implicitly restarted Arnoldi method(IRAM), which was also adopted in the HARMONY1.0 code. In addition, to improve the calculation efficiency, particularly in large higher-order modes, event-driven parallelization/domain decomposition methods are embedded in the HARMONY2.0 code to accelerate the inner iteration of λ∕α mode using OpenMP. Furthermore, the higher-order modes of complex geometric models, such as Hoogenboom and ATR reactors for λ mode and the MUSE-4 experiment facility for the prompt α mode, were computed using diffusion theory.展开更多
基金Projects(50605059,50735005)supported by the National Natural Science Foundation of ChinaProject(2009081012)supported by International Cooperation of Shanxi Province,ChinaProject(20090319ZX)supported by Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province,China
文摘Forward extrusion experiments of as-cast AZ31 magnesium alloy were conducted at different temperatures and different extrusion ratios using the as-cast billets with and without homogenizing treatment.The mechanical properties of pre-and post-extrusion of the two kinds of billets were investigated.Experimental results show that the mechanical properties of post-extrusion of the two kinds of billets all are obviously improved compared with those of pre-extrusion.The elongation of post-extrusion using the billet with homogenizing is higher than that without homogenizing,but the tensile strength is lower than that without homogenizing.When the extrusion ratio increases,the elongation and tensile strength of post-extrusion of two kinds of billets all will increase obviously.When the extrusion temperature of billet without homogenizing increases,the tensile strength of post-extrusion will decrease obviously and the elongation of post-extrusion will change to a small extent.For the billet with homogenizing,the tensile strength of post-extrusion will decrease in some sort when extrusion temperature increases.
基金supported by National Natural Science Foundation of China (Nos. 50975060, 50901025)the National Basic Research Program of China (2011CB610406)+2 种基金the China Postdoctoral Science Foundation (201104420, 20090450840)the Fundamental Research Funds for the Central Universities (HIT. BRET1. 2010008)Scientific and Technological Project in Heilongjiang Province (GZ09A206)
文摘The microstructure of as-cast Ti-46AI-0.5W-0.5Si alloy exhibits significant microinhomogenetity due to the non-equilibrium solidification and low atom diffusion rate. In order to reduce the adverse effect of this microsegregation on plasticity, the microstructure evolution of the Ti-46AI-0.5W-0.5Si alloy homogenized at different temperatures from 1,200 ℃ to 1,320 ℃was investigated, and the optimized process of homogenizing treatment, i.e., annealing treated at 1,280 ℃ and held for 8 h, was determined. Microstructures of both the as-cast and heat treated alloys were observed by means of optical microscope and scanning electron microscopes. Tensile tests at room temperature were conducted on the homogenizing treated fully lamellar Ti-46AI-0.5W-0.5Si alloy with loading axis parallel to the lamellar interface. Results show that, at higher heat treatment temperatures, the W element diffuses sufficiently, the microstructure tends to be more homogeneous, and the profile of the silicide clusters becomes smooth. Heat treating conducted in the a＋y two phase region can keep the columnar grains and the original lamellar orientation within them. The microstructure of the alloy after heat treated in a＋y two phase region exhibits the coexisting morphology of coarse lamellar and thin lamellar. The homogenization process at 1,280℃ for 8 h can significantly reduce the microsegregation, and the elongation at room temperature can increase from 0.48% （as-cast） to 1.34%.
文摘Homogeneous, high concentrated ceramic suspensions wi th low viscosity are the key controlling factors for the production of ceramic c omponents through colloidal processing. A well-dispersed suspension can be obta ined by choosing suitable dispersant, solvent, particle size distribution etc. B esides these factors, the homogenizing procedure is also a key step. In this paper, reaction sialon suspensions were prepared using 3-wt% KD1 as dis persant in organic media composed of 60-vol% methyletheylketone and 40-vol% et hanol. Different homogenizing procedures have been used and compared, including planetary milling, low energy ball milling and ultrasonic disaggregation. The ef fects of different homogenizing routes and mixing times on the rheology and stab ility of suspensions, and on the microstructure of slip casting green bodies, ha ve been studied. The varying dispersion efficiencies observed could be attribute d to differences in deagglomeration degrees achieved and in adsorption amount of dispersant onto the surface of reaction sialon powders.
基金the National Natural Science Foundation of China(Grant Nos.51175363 and 51474152)the Research Project Supported by the Shanxi Scholarship Council of China(Grant Nos.2014029)。
文摘To improve the homogeneity and rolling formability of as-cast AZ91 magnesium,the effects of pre-homogenizing treatment on microstructure evolution,deformation mechanism,mechanical properties and tensile fracture morphology of hot-rolled AZ91 magnesium alloy were studied.The results showed that the amount of coarseβ-Mg17Al12 phase decreases dramatically,being distributed along the grain boundaries as small strips after homogenizing.Twining plays a dominant role in the deformation mechanism of AZ91 alloys in the experimental condition,while dynamic recrystallization(DRX)considerably occurred in homogenized-rolled alloys,contributed to microstructure uniformity andβ-Mg17Al12 phase precipitated refinement.The tensile strength of homogenized-rolled AZ91 alloys increases dramatically with elongation declining slightly in contrast to homogenized alloys.The fracture surface of homogenized-rolled specimen exhibits more ductile fracture with the manifestation of a large amount of dimples distributing higher density in matrix,while the micro cracks are prone to initiate around the Mg/Mg17Al12 phase interface and grain boundaries owing to the fragile interface bonding of two phases.
基金supported by China Mega-Project for Infectious Disease (2009ZX10004-101,2009ZX10004-502)Health Sector Fund (200802021)SKLID Development Grant (2008SKLID102)
文摘Objective To quantitatively evaluate the contamination area and risk of a live pathogen during tissue homogenization by either ultrasonic processor or tissue disperser.Methods A recombinant Herpes Simplex Virus（rHSV） containing GFP gene was used as the index virus,and fresh liver tissue from healthy mice was used as simulated specimen.After 10% liver homogenate was mixed with rHSV（100 TCID50/0.1 mL） in a 5 mL tube,the stability of rHSV in liver homogenate and influences of an ultrasonic processor and a tissue disperser on viral infectivity were determined by GFP expressions in cell cultures.The contaminating areas of live viruses during homogenization were evaluated by a cell culture-based sedimentary.The contamination radii were counted by measurement of the distance between the operator and the farthest GFP positive well.Results The infectivity of rHSV in 10% liver homogenate maintained almost unchanged after it was incubated at room temperature for 30 min.Treatment with an ultrasonic processor clearly dropped down the virus infectivity,while a disperser not.Obvious spills and slashes of live viruses were observed in processes of homogenization with those two apparatuses.The contamination radii are positively related with sample volume,output energy of operator and handling time.Conclusion Homogenizing infectious samples with an ultrasonic processor and a tissue disperser at commonly used conditions caused obvious spills and splashes of live viruses,which possesses high risk to induce Laboratory acquired infections（LAIs）.
基金E&T Modern Center for Natural Products of Liaoning Province of China (2008402021)
文摘Objective To optimize the extraction technology of the active component, rosmarinic acid, an ester of caffeic acid and 3,4-dihydroxyphenyllactic acid, in perilla oil meal for the first time by a new homogenizing technology called smashing tissue extraction (STE). Methods Orthogonal design was used to optimize the extraction condition. The content of rosmarinic acid was quantified from the methanol crude extract with the help of HPLC. Results The optimization of STE process to get rosmarinic acid from the perilla oil meal was the ratio of liquid to solid material at 10:1 and the power of extraction at 150 V, extracting twice (2 min for each time). Conclusion STE could be applied to extracting the active ingredients from the oil meals due to its high extraction efficiency. This new homogenizing technology has advantages on saving extraction time, raising extraction efficiency, and maintaining the temperature sensitive constituents.
基金support by the National Key R&D Program of China(Grant No.2023YFA1008901)the National Natural Science Foundation of China(Grant Nos.11988102,12172009)is gratefully acknowledged.
文摘In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.
基金financially supported by the National Key R&D Program of China(No.2022YFE0121300)the National Natural Science Foundation of China(No.52374376)the Introduction Plan for High-end Foreign Experts(No.G2023105001L)。
文摘As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions.Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces.However,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials.From the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear surfaces.The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized.Starting from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed.It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.
基金supported by the National Natural Science Foundation of China(No.92372123)Guangdong Basic and Applied Basic Research Foundation(No.2022A1515012057,2022B1515020005,2023B1515130004)Guangzhou Basic and Applied Basic Research Foundation(No.202201011342).
文摘Porous organic cages(POCs)with permanent porosity and excellent host–vip property hold great potentials in regulating ion transport behavior,yet their feasibility as solid-state electrolytes has never been testified in a practical battery.Herein,we design and fabricate a quasi-solid-state electrolyte(QSSE)based on a POC to enable the stable operation of Li-metal batteries(LMBs).Benefiting from the ordered channels and cavity-induced anion-trapping effect of POC,the resulting POC-based QSSE exhibits a high Li+transference number of 0.67 and a high ionic conductivity of 1.25×10^(−4) S cm^(−1) with a low activation energy of 0.17 eV.These allow for homogeneous Li deposition and highly reversible Li plating/stripping for over 2000 h.As a proof of concept,the LMB assembled with POC-based QSSE demonstrates extremely stable cycling performance with 85%capacity retention after 1000 cycles.Therefore,our work demonstrates the practical applicability of POC as SSEs for LMBs and could be extended to other energy-storage systems,such as Na and K batteries.
基金supported by the National Nature Science Foundation of China(71771201,72531009,71973001)the USTC Research Funds of the Double First-Class Initiative(FSSF-A-240202).
文摘Social interaction with peer pressure is widely studied in social network analysis.Game theory can be utilized to model dynamic social interaction,and one class of game network models assumes that people’s decision payoff functions hinge on individual covariates and the choices of their friends.However,peer pressure would be misidentified and induce a non-negligible bias when incomplete covariates are involved in the game model.For this reason,we develop a generalized constant peer effects model based on homogeneity structure in dynamic social networks.The new model can effectively avoid bias through homogeneity pursuit and can be applied to a wider range of scenarios.To estimate peer pressure in the model,we first present two algorithms based on the initialize expand merge method and the polynomial-time twostage method to estimate homogeneity parameters.Then we apply the nested pseudo-likelihood method and obtain consistent estimators of peer pressure.Simulation evaluations show that our proposed methodology can achieve desirable and effective results in terms of the community misclassification rate and parameter estimation error.We also illustrate the advantages of our model in the empirical analysis when compared with a benchmark model.
基金the National Natural Science Foundation of China(No.22271060),The Department of Chemistry at Fudan University and College of Chemistry and Chemical Engineering at Ningxia University is gratefully acknowledged.
文摘Photoredox catalysis has made significant advances in stateof-the-art chemical synthesis,drawing energy from inexhaustible light and enabling various organic transformations to occur under mild reaction conditions.Over the past few years,a variety of homogeneous and heterogeneous photocatalysts have been applied in the photoredox catalysis.Heterogeneous photoredox catalysis offers advantages such as easy separation and superior recyclability compared to homogeneous counterparts,although homogenous catalysts are usually associated with higher activities and selectivity.From a practical perspective,an optimal photoredox catalytic system would integrate the advantages of both homogeneous and heterogeneous cases.
基金Project supported by the Chilean National Agency for Research and Development(ANID)through Grants ANID FONDECYT Regular(Nos.1211310 and 1250496)ANID Anillo de Tecnologia(No.ACT240015)the Polish National Science Centre(NCN)through Grant Agreement(No.2021/41/B/ST8/04492)。
文摘The acoustic wave propagation in gas-saturated double-porosity materials composed of a microporous matrix and mesopores with arrays of plate-type resonators is investigated.A macroscopic description,established with the two-scale asymptotic homogenization method,evidences the combined effect of inner resonances on the acoustic properties of the respective effective visco-thermal fluid.One type of resonance originates from strong pore-scale fluid-structure interaction,while the other one arises from pressure diffusion.These phenomena respectively cause weakly and highly damped resonances,which are activated by internal momentum or mass sources,and can largely influence,depending on the material's morphology,either the effective fluid's dynamic density,compressibility,or both.We introduce semi-analytical models to illustrate the key effective properties of the studied multiscale metamaterials.The results provide insights for the bottom-up design of multiscale acoustic metamaterials with exotic behaviors,such as the negative,very slow,or supersonic phase velocity,as well as sub-wavelength bandgaps.
基金Project(52174303)supported by the National Natural Science Foundation of ChinaProject(2023JH2/101700302)supported by the Joint Program of Science and Technology Plans in Liaoning Province,China。
文摘Based on microstructure analysis,diffusion theory,and hot deformation experiments,the solidification microstructure and element segregation of the Alloy 625 Plus ingot,the diffusion kinetics of Ti,Nb,and Mo during homogenization and the hot deformation behavior of the homogenized ingot were investigated in this study.The results indicate that:(1)the solidified ingot exhibits a typical dendritic microstructure,and significant element segregation occurs,leading to the presence of Ti,Nb,and Mo-rich precipitates in the interdendritic region;(2)Following homogenization,the degree of element segregation in the ingot is significantly reduced.The diffusion coefficients(D)of Ti,Nb,and Mo under various homogenization conditions were calculated.Subsequently,the diffusion constants(D_(0))and activation energies(Q)of Ti,Nb,and Mo were obtained to be 0.01432,0.00397 and 0.00195 cm^(2)/s and 244.851,230.312,and 222.125 kJ/mol,respectively.Finally,the diffusion kinetics formulas for Ti,Nb,and Mo in Alloy 625 Plus were established.After homogenization at 1220℃for 8 h,the alloy exhibits low deformation resistance,a high degree of recrystallization,and optimal deformation coordination ability.Therefore,this represents a rational single-stage homogenization process.
基金financially supported by the Guangdong Pearl River Talent Program(2021ZT09L400)the National Natural Science Foundation of China(52302195,52072284)+1 种基金the Joint Funds of Natural Science Foundation of Hubei Province(2022CFD087)the Scientific Research and Technology Development Project of China National Petroleum Corporation(Grant Nos.2024ZG50)。
文摘The utilization of self-assembled monolayers(SAMs)has significantly elevated the power conversion efficiency(PCE)of inverted perovskite solar cells(PSCs).However,the inherent hydrophobicity of these SAMs poses challenges in the subsequent printing of perovskite films in PSC upscaling.In this work,we incorporated a multifunctional additive,dimethyl suberimidate dihydrochloride(DMSCl_(2)),into the perovskite precursor to enhance the quality of the blade-coated perovskite film on the SAM interlayer.Characterizations revealed that the function groups of the imino(N-H)and methoxy(CH_(3)O-)DMSCl_(2) facilitate both bonding between perovskite precursor and SAM molecule(Me-4PACz),which facilitates the large-area printing of perovskite film.These interactions also provide effective passivation within the perovskite films and interface defects of PSCs.As a result,a significantly enhanced PCE from 16.62% to 20.37% was obtained for the printed perovskite solar module(93.10 cm^(2))and 25.27% for the small device(0.09 cm^(2)).Remarkable stability was achieved with 93.3% of their initial PCE after 1000 h of continuous maximum power point(MPP)tracking.This report suggests that multifunctional additive doping provides a convenient route for the upscaling of perovskite solar cells with SAM interlayers.
基金funded by the National Key R&D Program of China(Grant No.2023YFA1008901)the National Natural Science Foundation of China(Grant Nos.11988102,12172009)“The Fundamental Research Funds for the Central Universities,Peking University”.
文摘The multiscale computational method with asymptotic analysis and reduced-order homogenization(ROH)gives a practical numerical solution for engineering problems,especially composite materials.Under the ROH framework,a partition-based unitcell structure at the mesoscale is utilized to give a mechanical state at the macro-scale quadrature point with pre-evaluated influence functions.In the past,the“1-phase,1-partition”rule was usually adopted in numerical analysis,where one constituent phase at the mesoscale formed one partition.The numerical cost then is significantly reduced by introducing an assumption that the mechanical responses are the same all the time at the same constituent,while it also introduces numerical inaccuracy.This study proposes a new partitioning method for fibrous unitcells under a reduced-order homogenization methodology.In this method,the fiber phase remains 1 partition,but the matrix phase is divided into 2 partitions,which refers to the“12”partitioning scheme.Analytical elastic influence+functions are derived by introducing the elastic strain energy equivalence(Hill-Mandel condition).This research also obtains the analytical eigenstrain influence functions by alleviating the so-called“inclusion-locking”phenomenon.In addition,a numerical approach to minimize the error of strain energy density is introduced to determine the partitioning of the matrix phase.Several numerical examples are presented to compare the differences among direct numerical simulation(DNS),“11”,and“12”partitioning schemes.The numerical simulations show improved++numerical accuracy by the“12”partitioning scheme.
基金financial support from the National Natural Science Foundation of China(Nos.22071222,22171249)the Natural Science Foundation of Henan Province(Nos.232300421363,242300420526)+2 种基金Key Research Projects of Universities in Henan Province(No.23A180010)Science&Technology Innovation Talents in Universities of Henan Province(No.23HASTIT003)Science and Technology Research and Development Plan Joint Fund of Henan Province(No.242301420006)。
文摘The photoinduced ligand-to-metal charge transfer(LMCT)process has been extensively investigated,however,the recovery of photocatalysts has remained a persistent challenge in the field.In light of this issue,a novel approach involving the development of iron-based ionic liquids as photocatalysts has been pursued for the first time,with the goal of simultaneously facilitating the LMCT process and addressing the issue of photocatalyst recovery.Remarkably,the iron-based ionic liquid 1-butyl-3-methylimidazolium tetrachloroferrate(C_(4)mim-Fe Cl_(4))demonstrates exceptional recyclability and stability for the photocatalytic hydroacylation of olefins.This study will pave the way for new approaches to photocatalytic organic synthesis using ionic liquids as recyclable photocatalysts.
基金support from the National Key Research and Development Plan Project(No.2022YFC3004700)the National Natural Science Foundation of China(No.52374241)+1 种基金Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX24_2924)Graduate Innovation Program of China University of Mining and Technology(No.2024WLKXJ151).
文摘To investigate the instability mechanisms of heterogeneous geological structures in goaf area roofs,three-point bending tests(TPBT)and numerical simulations are performed on composite coal-rock(CCR).Acoustic emission(AE)monitoring is employed to analyze key parameters,establishing a multiparameter quantitative system for CCR fracture processes.The impact of lithological homogeneity on fracture evolution and energy migration is examined.Results show that CCR exhibits a three-stage mechanical response:weak contact,strong contact,and post-peak stages,each with distinct crack evolution patterns.A positive correlation is found between lithological homogeneity and tensile crack proportion.No significant correlation is observed between AE average frequency(AF)and AE counts across different lithological CCR;however,peak frequency(PF)displays clear lithology-dependent characteristics.The regulatory effect of the rock homogeneity coefficient(φ)on crack deriva tion mechanisms is quantfied,yielding mathematical relationships between fracture strength(f),crack propagation path angle(β),crack fractal dimension(D),andφ.The study highlights how different fracture modes alter energy migration pathways,confirming the coupling effect of grain distribution on mechanical response and crack propagation,and the influence of parameterφon critical energy release zones.These findings offer new insights into CCR failure mechanisms for mining safety.
基金funding recei-ved from the National Key R&D Program of China(No.2022YFB3705602)the Scientific Research Plan Project of Shanghai,P.R.China(No.22SQBS 00600).
文摘TC4 titanium alloy(Ti-6Al-4V),known for its excellent specific strength,corrosion resistance,and weldability,is extensively applied in aerospace,marine engineering,and advanced manufacturing.This study focuses on the microstructural uniformity and mechanical properties of TC4 ingots fabricated via the electron-beam cold hearth melting(EBCHM)process.A comprehensive analysis was performed using optical microscopy,scanning electron microscopy,electron backscatter diffraction,and energy-dispersive spectroscopy to investigate the ingot’s morphology,α-phase lamellar structure,and elemental distribution.Mechanical characterization included tensile testing,and microhardness and impact toughness assessments.Results reveal that EBCHM produces a well-defined and homogeneous microstructure,with the averageαlamellae thickness varying between 1.53 and 1.71μm and minimal fluctuations across the ingot regions,indicating high process consistency.Major alloying elements(Al and V)and impurity elements(O,N,H,C,and Fe)are evenly distributed,with no observable macrosegregation.The mechanical properties are stable and reliable,with a yield strength of 694.6-701.2 MPa,a tensile strength of 711.1-716.6 MPa,an elongation of 3.35%-3.84%,and an average impact toughness of 94.7 J/cm^(2).These results provide valuable data and technical references for the application of EBCHM in manufacturing premium-quality Ti-6Al-4V ingots.
基金supported by the National Natural Science Foundation of China(No.51804232)Beijing Municipal Natural Science Foundation(No.2212041)+1 种基金supported by the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(FRF-IDRY-20-020)GIMRT Program of the Institute for Materials Research,Tohoku University(202303-RDKGE-0518).
文摘Enhancing homogenization efficiency and hot-workability is the key issue for wrought superalloys in the industry.A novel approach for simultaneous accelerating the homogenization kinetics and improving hot-workability via a simple way of prior hot-deformation was proposed,which was not widely accepted for wrought superalloys.The homogenization efficiency is increased by 40%-70%via performing 10%-20%prior hot-deformation.Both theoretical and experimental analyses revealed that the increment in homogenization efficiency is mainly attributed to the decrease in interdendritic-segregation spacing,and thus the necessary diffusion distance,rather than that of dislocations.In addition,dynamic and static recrystallizations occurred during the prior hot-deformation and diffusion-annealing processes,and the grains were significantly refined even after the homogenization.Furthermore,the size of the precipitates was refined as well.These enhanced the hot-workability of the homogenized ingot for the subsequent cogging process.
基金supported by the National Natural Science Foundation of China(No.U2267207)Science and Technology on Reactor System Design Technology Laboratory(No.KFKT-05-FWHTWU-2023004).
文摘Higher-order modes of the neutron diffusion/transport equation can be used to study the temporal behavior of nuclear reactors and can be applied in modal analysis, transient analysis, and online monitoring of the reactor core. Both the deterministic method and the Monte Carlo(MC) method can be used to solve the higher-order modes. However, MC method, compared to the deterministic method, faces challenges in terms of computational efficiency and α mode calculation stability, whereas the deterministic method encounters issues arising from homogenization-related geometric and energy spectra adaptation.Based on the higher-order mode diffusion calculation code HARMONY, we developed a new higher-order mode calculation code, HARMONY2.0, which retains the functionality of computing λ and α higher-order modes from HARMONY1.0, but enhances the ability to treat complex geometries and arbitrary energy spectra using the MC-deterministic hybrid two-step strategy. In HARMONY2.0, the mesh homogenized multigroup constants were obtained using OpenMC in the first step,and higher-order modes were then calculated with the mesh homogenized core diffusion model using the implicitly restarted Arnoldi method(IRAM), which was also adopted in the HARMONY1.0 code. In addition, to improve the calculation efficiency, particularly in large higher-order modes, event-driven parallelization/domain decomposition methods are embedded in the HARMONY2.0 code to accelerate the inner iteration of λ∕α mode using OpenMP. Furthermore, the higher-order modes of complex geometric models, such as Hoogenboom and ATR reactors for λ mode and the MUSE-4 experiment facility for the prompt α mode, were computed using diffusion theory.
