Heterogeneous structures(HS)materials have the potential to exhibit simultaneous improvement in strength and plasticity due to hetero-deformation-induced hardening(HDI)between multiple grain struc-tures.However,achiev...Heterogeneous structures(HS)materials have the potential to exhibit simultaneous improvement in strength and plasticity due to hetero-deformation-induced hardening(HDI)between multiple grain struc-tures.However,achieving HS in aluminum alloy can be quite challenging.In this study,7000 series alu-minum alloys are investigated by incorporating rare earth element Y to develop a dual-phase structure containing Al_(8)Cu_(4)Y and Al_(3)(Y,Zr)phases.And a heterogeneous lamella structure(HLS)is formed through the synergistic effect of Al_(8)Cu_(4)Y which includes dynamic recrystallization nucleation during deformation,and Al_(3)(Y,Zr)which hinders the growth of recrystallized grain by means of pinning dislocations and sub-grain boundaries.Substructures such as precipitates and nanocrystals are incorporated during the fabri-cation of HS,allowing for precise control over the volume fraction of fine grains by adjusting the ratio of two-scale second phases.When Y content reaches 0.3%,the 7Y55-2/heterogeneous lamella structure(HLS)samples exhibit a fine grain volume fraction of 76.5 vol.%,a tensile strength of 695 MPa,and an elon-gation of 16.6%.The alloy contains a large number of dislocations that preferentially induce the growth ofη’phases along specific directions,thereby promoting their development.The multi-coupling effect and composite strengthening mechanisms in the“heterostructure-dislocation-precipitate”microstructure contribute to the intrinsic excellent strength and plasticity of the alloy.This study tackles the challenge of inverted strength and plasticity observed in Al-Zn-Mg-Cu-Zr alloys,offering novel insights that pave the way for further applications of heterogeneous materials.展开更多
During solidifications of immiscible alloys,the motion of droplets at the solid/liquid(S/L)interface is gen-erally driven by dragging force,gravity force,repulsion force of interface,and thermal-solutal Marangoni forc...During solidifications of immiscible alloys,the motion of droplets at the solid/liquid(S/L)interface is gen-erally driven by dragging force,gravity force,repulsion force of interface,and thermal-solutal Marangoni force,However,there is few in situ study investigating kinetics behavior to analyze the forces on droplets.The mechanism of droplet motion remains unclear due to the unavailability or uncertainty of the effect of convection and solutal Marangoni force on droplet behavior.In this study,directional solidification of im-miscible Al-Bi alloy was observed via synchrotron radiography,and the horizontal oscillation of droplets at S/L interface was detected for the first time.Forces,especially solutal Marangoni force,were calcu-lated based on the in situ measured radius of droplets and thermal-solutal gradients.The experimental results cannot be reasonably explained by the previous analysis model which neglects melt convection.The non-negligible effect of flow on droplet motion was demonstrated,and the force balance of droplet both vertically and horizontally can be obtained considering a lift force of 6.39 × 10^(-9) N and a modified solute-related parameter dσ/dc of 0.45-0.65 J m^(-2),respectively.展开更多
The effect of undercooling DT and the interface energy anisotropy parameter e4 on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary al...The effect of undercooling DT and the interface energy anisotropy parameter e4 on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary alloys.It was found that the tip radius r increases and the tip shape amplitude coefficient A4 decreases with the increase of the fitting range for all cases.The dendrite tip shape selection parameter sdecreases and then stabilizes with the increase of the fitting range,and sincreases with the increase of e4.The relationship between sand e4 follows a power-law function sµea 4,and a is independent of DT but dependent on the fitting range.Numerical results demonstrate that the predicted sis consistent with the curve of microscopic solvability theory(MST)for e4<0.02,and sobtained from our phase-field simulations is sensitive to the undercooling when e4 is fixed.展开更多
Introduction:The genetic diversity of human immunodeficiency virus-1(HIV-1)in China is characterized by multiple subtypes,circulating recombinant forms(CRFs)and unique recombinant forms(URFs)across the country.Through...Introduction:The genetic diversity of human immunodeficiency virus-1(HIV-1)in China is characterized by multiple subtypes,circulating recombinant forms(CRFs)and unique recombinant forms(URFs)across the country.Through timely molecular surveillance,over 65 distinct CRFs have been identified in China to date.In this study,we identified five novel URFs among newly reported HIV-1 infected individuals in Anhui Province,China.Methods:Near-full length HIV genome sequences were obtained using two-half molecule amplification methods from five samples containing potential URFs.The sequences were subsequently subjected to phylogenetic and recombination analyses.Results:Phylogenetic and recombination analyses of the five near-full length genome sequences confirmed their classification as novel URFs.Among these,three sequences were recombinants of CRF01_AE and CRF07_BC,one sequence was a recombinant of CRF01_AE,CRF07_BC and B,and one sequence resulted from CRF07_BC and CRF08_BC recombination.Conclusions:The identification of URFs in newly infected individuals indicates ongoing transmission of multiple HIV-1 clades in Anhui Province,with superinfection occurring at notable frequencies.These findings emphasize the importance of enhancing longterm surveillance of circulating HIV-1 clades using near-full length sequence analysis in Anhui,China.展开更多
<div style="text-align:justify;"> The large aperture mirror surface test is the basis of optical processing and alignment, and is also the key to the development of remote sensing device. The simulatio...<div style="text-align:justify;"> The large aperture mirror surface test is the basis of optical processing and alignment, and is also the key to the development of remote sensing device. The simulation results show that the RMS values of 1.07 m primary mirror with multi-point support and sling support are 1.86 nm and 3.28 nm respectively. Using 36 point unloading device, sponge 36 point free support and sling support to test the mirror surface, the results are basically consistent, RMS is better than 0.02λ (λ = 632.8 nm). </div>展开更多
To understand the prevalence and evolution of drug resistant HIV strains in Henan China after the implementation of free antiretroviral therapy for AIDS patients. 45 drug naive AIDS patients, 118 AIDS patients who rec...To understand the prevalence and evolution of drug resistant HIV strains in Henan China after the implementation of free antiretroviral therapy for AIDS patients. 45 drug naive AIDS patients, 118 AIDS patients who received three months antiretroviral therapy and 124 AIDS patients who received six months antiretroviral treatment were recruited in the southern part of Henan province. Information on general condition, antiretroviral medicines, adherence and clinical syndromes were collected by face to face interview. Meanwhile, 14ml EDTA anticoagulant blood was drawn. CD4/CD8 T cell count, viral load and genotypic drug resistance were tested. The rates of clinical improvement were 55.1% and 50.8% respectively three months and six months after antiretroviral therapy. The mean CD4 cell count after antiretroviral therapy was significantly higher than in drug naive patients. The prevalence rate of drug resistant HIV strains were 13.9%, 45.4% and 62.7% in drug naive patients, three month treatment patients and six month treatment patients, respectively. The number of resistance mutation codons and the frequency of mutations increased significantly with continued antiretroviral therapy. The mutation sites were primarily at the 103, 106 and 215 codons in the three-month treatment group and they increased to 15 codon mutations in the six-month treatment group. From this result, the evolution of drug resistant strains was inferred to begin with the high level NNRTI resistant strain, and then develop low level resistant strains to NRTIs. The HIV strains with high level resistance to NVP and low level resistance to AZT and DDI were highly prevalent because of the AZT＋DDI＋NVP combination therapy. These HIV strains were also cross resistant to DLV, EFV, DDC and D4T. Poor adherence to therapy was believed to be the main reason for the emergence and prevalence of drug resistant HIV strains. The prevalence of drug resistant HIV strains was increased with the continuation of antiretroviral therapy in the southern part of Henan province. Measures, that could promote high level adherence, provide new drugs and change ART regimens in failing patients, should be implemented as soon as possible.展开更多
The AM50,AM50-0.1 Ca,AM50-0.3 Ca and AM50-0.5 Ca(wt.%) alloys were hot-rolled and their mechanical properties were determined for the purpose of investigating the effect of trace Ca addition on the texture and stretch...The AM50,AM50-0.1 Ca,AM50-0.3 Ca and AM50-0.5 Ca(wt.%) alloys were hot-rolled and their mechanical properties were determined for the purpose of investigating the effect of trace Ca addition on the texture and stretch formability of AM50 alloy.The results show that the addition of trace Ca can effectively modify the basal texture,which is characterized by the split of basal poles deviated from the normal direction(ND) after the hot rolling,while a broad spread of the basal planes toward the transverse direction(TD) after the annealing.Such change of the basal texture is related to the prior formation of massive compression twins and the decrease of the c/a ratio.Erichsen value increases from 2.25 to 4.21 mm with the increase of Ca content.The enhancement of stretch formability is ascribed to the weakened basal texture,which results in the increase of n-value and the decrease of r-value.展开更多
SHIV-CN97001 played an important role in assessing the immune effect and strategy of the AIDS vaccine which included genes of the predominant prevalent HIV-1 strain in China. In this study, SHIV-CN97001 was in vivo pa...SHIV-CN97001 played an important role in assessing the immune effect and strategy of the AIDS vaccine which included genes of the predominant prevalent HIV-1 strain in China. In this study, SHIV-CN97001 was in vivo passaged serially to construct pathogenic SHIV-CN97001/rhesus macaques model. To identify variation in the gp120 region of SHIV-CN97001 during passage, the fragments of gp120 gene were amplified by RT-PCR from the plasma of SHIV-CN97001 infected animals at the peak viral load time point and the gene distances (divergence, diversity) were calculated using DISTANCE. The analysis revealed that the genetic distances of SHIV-CN97001 in the third passage animals were the highest during in vivo passage. It had a relationship between viral divergence from the founder strain and viral replication ability. The nucleic acid sequence of the V3 region was highly conservative. All of the SHIV-CN97001 strains had V3 loop central motif (GPGQ) and were predicted to be using CCR5 co-receptor on the basis of the critical amino acids within V3 loop. These results show that there was no significant increase in the genetic distance during serial passage, and SHIV-CN97001 gp120 gene evolved toward ancestral states upon transmission to a new host. This could partly explain why there was no pathogenic viral strain obtained during in vivo passage.展开更多
Phase-field method,as a powerful and popular approach to predict the mesoscale microstructure evolution in various materials science,provides a bridge from atomic-scale methods to the macroscale and has been widely us...Phase-field method,as a powerful and popular approach to predict the mesoscale microstructure evolution in various materials science,provides a bridge from atomic-scale methods to the macroscale and has been widely used at an ever-increasing rate.This paper aims to briefly review the origin,basic idea,and development of phase-field models in a historical manner.The focus is placed on the classical and state-of-the-art applications in China,including liquid–solid,solid–solid,gas–solid,ferroelectrics/ferromagnetics phase transformation,and crack propagation-fracture.After introducing the academic activities in the phase-field community in China,some suggestions for the future development directions of phase-field method are finally mentioned.展开更多
Objective To develop a model of SHIV-KB9/Chinese origin rhesus （Ch Rh） macaques for vaccine research and to compare the pathogenesis of SHIV-KB9 in Ch Rh macaques with that reported in Indian rhesus （Ind Rh） macaq...Objective To develop a model of SHIV-KB9/Chinese origin rhesus （Ch Rh） macaques for vaccine research and to compare the pathogenesis of SHIV-KB9 in Ch Rh macaques with that reported in Indian rhesus （Ind Rh） macaques. Methods Seven mamu-A＊01 negative Ch Rh macaques were inoculated intravenously with 1-10000 MID50 of SHIV-KB9. The monkeys were monitored for viral load, CD4, CDS, SHIV-specific antibody and virus genetic variation. The results were compared with those previously observed in Ind Rh macaques. Results As compared to that observed in Ind Rh macaques, SHIV-KB9 in Ch Rh macaques displayed three identical disease progression patterns. However, the primary pattern was not identical between the two subspecies. The level of plasma viremia differed in SHIV-KB9-infected Ch Rh macaques which exhibited different outcomes from those in Ind Rh macaques. Generally, the values of viral load and the maintenance of CD4^＋ T cells were associated with humoral responses. Otherwise, the viral genetic distances （divergence, diversity） were larger in animals （M419, M425） with their CD4^＋ T cells profoundly depleted. Conclusion The model of SHIV-KB9/Ch Rh macaques displays a relatively slow progression to AIDS compared with Ind Rh macaques, which may more accurately reflect the potential of candidate vaccines in humans.展开更多
Density change is ubiquitous in phase transformation, and it can induce melt convection which strongly influences the crystal growth. Here, an anisotropic lattice Boltzmann-phase-field method was extended to predict t...Density change is ubiquitous in phase transformation, and it can induce melt convection which strongly influences the crystal growth. Here, an anisotropic lattice Boltzmann-phase-field method was extended to predict the dendritic growth under the shrinkage or expansion melt convection by density change induced. A novel LB equation with an anisotropic coefficient was constructed to model the advancement of ordering parameter, coupling with the passive scalar LB equation for convective and diffusive heat transfer during phase transition. We studied dendritic growth and shape selection with melt convection induced by density change in crystal growth. Results show that the melt convection induced by density change affects strongly the dendritic growth. The shrinkage flow results in a higher tip velocity while the expansion flow leads to a slower one. Predicted Péclet number with respect to the relative density change was compared with an analytical solution. Moreover, the modified selection parameter has been verified by numerical simulations.展开更多
Degenerate pattern is a seemingly disordered morphology but it exhibits the inherently ordered crystal connected with tip-splitting and limited stability which makes it difficult to observe in the metallic system. Her...Degenerate pattern is a seemingly disordered morphology but it exhibits the inherently ordered crystal connected with tip-splitting and limited stability which makes it difficult to observe in the metallic system. Here we employ(100)[011] orientated planar-front seeds using directional solidification and reveal the fundamental origins of the degenerate pattern growth in an Al-4.5 wt% Cu alloy. We find that the spacing of the tip-splitting(λ) in the degenerate of the alloys followed a power law,λ∝V^-0.5, and the frequency(f) of the splitting was related to the growth velocity(V) by f ∝V^1.5. The dimensionless growth direction(θ/θ0) increased monotonously and approached 0.6 with faster velocity, attributed to its anisotropy in the interface kinetics. Once growth velocity exceeded a threshold, two types of pattern transitions from degenerate to regular dendrites were proposed. One of them exhibited a random and chaotic mode and the other underwent a rotation in growth direction.展开更多
Pattern selection during crystal growth is studied by using the anisotropic lattice Boltzmann-phase field model.In the model,the phase transition,melt flows,and heat transfer are coupled and mathematically described b...Pattern selection during crystal growth is studied by using the anisotropic lattice Boltzmann-phase field model.In the model,the phase transition,melt flows,and heat transfer are coupled and mathematically described by using the lattice Boltzmann(LB)scheme.The anisotropic streaming-relaxation operation fitting into the LB framework is implemented to model interface advancing with various preferred orientations.Crystal pattern evolutions are then numerically investigated in the conditions of with and without melt flows.It is found that melt flows can significantly influence heat transfer,crystal growth behavior,and phase distributions.The crystal morphological transition from dendrite,seaweed to cauliflower-like patterns occurs with the increase of undercoolings.The interface normal angles and curvature distributions are proposed to quantitatively characterize crystal patterns.The results demonstrate that the distributions are corresponding to crystal morphological features,and they can be therefore used to describe the evolution of crystal patterns in a quantitative way.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFB3406800)the National Natural Science Foundation of China(Nos.52271036 and 51971237).
文摘Heterogeneous structures(HS)materials have the potential to exhibit simultaneous improvement in strength and plasticity due to hetero-deformation-induced hardening(HDI)between multiple grain struc-tures.However,achieving HS in aluminum alloy can be quite challenging.In this study,7000 series alu-minum alloys are investigated by incorporating rare earth element Y to develop a dual-phase structure containing Al_(8)Cu_(4)Y and Al_(3)(Y,Zr)phases.And a heterogeneous lamella structure(HLS)is formed through the synergistic effect of Al_(8)Cu_(4)Y which includes dynamic recrystallization nucleation during deformation,and Al_(3)(Y,Zr)which hinders the growth of recrystallized grain by means of pinning dislocations and sub-grain boundaries.Substructures such as precipitates and nanocrystals are incorporated during the fabri-cation of HS,allowing for precise control over the volume fraction of fine grains by adjusting the ratio of two-scale second phases.When Y content reaches 0.3%,the 7Y55-2/heterogeneous lamella structure(HLS)samples exhibit a fine grain volume fraction of 76.5 vol.%,a tensile strength of 695 MPa,and an elon-gation of 16.6%.The alloy contains a large number of dislocations that preferentially induce the growth ofη’phases along specific directions,thereby promoting their development.The multi-coupling effect and composite strengthening mechanisms in the“heterostructure-dislocation-precipitate”microstructure contribute to the intrinsic excellent strength and plasticity of the alloy.This study tackles the challenge of inverted strength and plasticity observed in Al-Zn-Mg-Cu-Zr alloys,offering novel insights that pave the way for further applications of heterogeneous materials.
基金National Natural Science Foundation of China(Nos.52271036 and 51971237)Shanghai Pujiang Program(No.21PJD030)。
文摘During solidifications of immiscible alloys,the motion of droplets at the solid/liquid(S/L)interface is gen-erally driven by dragging force,gravity force,repulsion force of interface,and thermal-solutal Marangoni force,However,there is few in situ study investigating kinetics behavior to analyze the forces on droplets.The mechanism of droplet motion remains unclear due to the unavailability or uncertainty of the effect of convection and solutal Marangoni force on droplet behavior.In this study,directional solidification of im-miscible Al-Bi alloy was observed via synchrotron radiography,and the horizontal oscillation of droplets at S/L interface was detected for the first time.Forces,especially solutal Marangoni force,were calcu-lated based on the in situ measured radius of droplets and thermal-solutal gradients.The experimental results cannot be reasonably explained by the previous analysis model which neglects melt convection.The non-negligible effect of flow on droplet motion was demonstrated,and the force balance of droplet both vertically and horizontally can be obtained considering a lift force of 6.39 × 10^(-9) N and a modified solute-related parameter dσ/dc of 0.45-0.65 J m^(-2),respectively.
基金the National Key Research and De-velopment Program of China(Grant No.2021YFB3502600)Shenzhen Science and Technology Program(Grant No.JCYJ20220530161813029).
文摘The effect of undercooling DT and the interface energy anisotropy parameter e4 on the shape of the equiaxed dendritic tip has been investigated by using a quantitative phase-field model for solidification of binary alloys.It was found that the tip radius r increases and the tip shape amplitude coefficient A4 decreases with the increase of the fitting range for all cases.The dendrite tip shape selection parameter sdecreases and then stabilizes with the increase of the fitting range,and sincreases with the increase of e4.The relationship between sand e4 follows a power-law function sµea 4,and a is independent of DT but dependent on the fitting range.Numerical results demonstrate that the predicted sis consistent with the curve of microscopic solvability theory(MST)for e4<0.02,and sobtained from our phase-field simulations is sensitive to the undercooling when e4 is fixed.
基金Supported by the Ministry of Science and Technology of China(grant number 2022YFC2305201).
文摘Introduction:The genetic diversity of human immunodeficiency virus-1(HIV-1)in China is characterized by multiple subtypes,circulating recombinant forms(CRFs)and unique recombinant forms(URFs)across the country.Through timely molecular surveillance,over 65 distinct CRFs have been identified in China to date.In this study,we identified five novel URFs among newly reported HIV-1 infected individuals in Anhui Province,China.Methods:Near-full length HIV genome sequences were obtained using two-half molecule amplification methods from five samples containing potential URFs.The sequences were subsequently subjected to phylogenetic and recombination analyses.Results:Phylogenetic and recombination analyses of the five near-full length genome sequences confirmed their classification as novel URFs.Among these,three sequences were recombinants of CRF01_AE and CRF07_BC,one sequence was a recombinant of CRF01_AE,CRF07_BC and B,and one sequence resulted from CRF07_BC and CRF08_BC recombination.Conclusions:The identification of URFs in newly infected individuals indicates ongoing transmission of multiple HIV-1 clades in Anhui Province,with superinfection occurring at notable frequencies.These findings emphasize the importance of enhancing longterm surveillance of circulating HIV-1 clades using near-full length sequence analysis in Anhui,China.
文摘<div style="text-align:justify;"> The large aperture mirror surface test is the basis of optical processing and alignment, and is also the key to the development of remote sensing device. The simulation results show that the RMS values of 1.07 m primary mirror with multi-point support and sling support are 1.86 nm and 3.28 nm respectively. Using 36 point unloading device, sponge 36 point free support and sling support to test the mirror surface, the results are basically consistent, RMS is better than 0.02λ (λ = 632.8 nm). </div>
文摘To understand the prevalence and evolution of drug resistant HIV strains in Henan China after the implementation of free antiretroviral therapy for AIDS patients. 45 drug naive AIDS patients, 118 AIDS patients who received three months antiretroviral therapy and 124 AIDS patients who received six months antiretroviral treatment were recruited in the southern part of Henan province. Information on general condition, antiretroviral medicines, adherence and clinical syndromes were collected by face to face interview. Meanwhile, 14ml EDTA anticoagulant blood was drawn. CD4/CD8 T cell count, viral load and genotypic drug resistance were tested. The rates of clinical improvement were 55.1% and 50.8% respectively three months and six months after antiretroviral therapy. The mean CD4 cell count after antiretroviral therapy was significantly higher than in drug naive patients. The prevalence rate of drug resistant HIV strains were 13.9%, 45.4% and 62.7% in drug naive patients, three month treatment patients and six month treatment patients, respectively. The number of resistance mutation codons and the frequency of mutations increased significantly with continued antiretroviral therapy. The mutation sites were primarily at the 103, 106 and 215 codons in the three-month treatment group and they increased to 15 codon mutations in the six-month treatment group. From this result, the evolution of drug resistant strains was inferred to begin with the high level NNRTI resistant strain, and then develop low level resistant strains to NRTIs. The HIV strains with high level resistance to NVP and low level resistance to AZT and DDI were highly prevalent because of the AZT＋DDI＋NVP combination therapy. These HIV strains were also cross resistant to DLV, EFV, DDC and D4T. Poor adherence to therapy was believed to be the main reason for the emergence and prevalence of drug resistant HIV strains. The prevalence of drug resistant HIV strains was increased with the continuation of antiretroviral therapy in the southern part of Henan province. Measures, that could promote high level adherence, provide new drugs and change ART regimens in failing patients, should be implemented as soon as possible.
基金Projects(51801186,51974281)supported by the National Natural Science Foundation of ChinaProject(SKLSP201814)supported by the Fund of the State Key Laboratory of Solidification Processing in Northwestern Polytechnical University,China
文摘The AM50,AM50-0.1 Ca,AM50-0.3 Ca and AM50-0.5 Ca(wt.%) alloys were hot-rolled and their mechanical properties were determined for the purpose of investigating the effect of trace Ca addition on the texture and stretch formability of AM50 alloy.The results show that the addition of trace Ca can effectively modify the basal texture,which is characterized by the split of basal poles deviated from the normal direction(ND) after the hot rolling,while a broad spread of the basal planes toward the transverse direction(TD) after the annealing.Such change of the basal texture is related to the prior formation of massive compression twins and the decrease of the c/a ratio.Erichsen value increases from 2.25 to 4.21 mm with the increase of Ca content.The enhancement of stretch formability is ascribed to the weakened basal texture,which results in the increase of n-value and the decrease of r-value.
文摘SHIV-CN97001 played an important role in assessing the immune effect and strategy of the AIDS vaccine which included genes of the predominant prevalent HIV-1 strain in China. In this study, SHIV-CN97001 was in vivo passaged serially to construct pathogenic SHIV-CN97001/rhesus macaques model. To identify variation in the gp120 region of SHIV-CN97001 during passage, the fragments of gp120 gene were amplified by RT-PCR from the plasma of SHIV-CN97001 infected animals at the peak viral load time point and the gene distances (divergence, diversity) were calculated using DISTANCE. The analysis revealed that the genetic distances of SHIV-CN97001 in the third passage animals were the highest during in vivo passage. It had a relationship between viral divergence from the founder strain and viral replication ability. The nucleic acid sequence of the V3 region was highly conservative. All of the SHIV-CN97001 strains had V3 loop central motif (GPGQ) and were predicted to be using CCR5 co-receptor on the basis of the critical amino acids within V3 loop. These results show that there was no significant increase in the genetic distance during serial passage, and SHIV-CN97001 gp120 gene evolved toward ancestral states upon transmission to a new host. This could partly explain why there was no pathogenic viral strain obtained during in vivo passage.
基金the National Natural Science Foundation of China(Nos.52074246,52201146,52205429,52275390,U1904214)the National Defense Basic Scientific Research Program of China(No.JCKY2020408B002)+1 种基金the Key Research and Development Program of Shanxi Province(No.202102050201011)L.Z.acknowledges the Natural Science Foundation of Hunan Province for Distinguished Young Scholars(No.2021JJ10062).
文摘Phase-field method,as a powerful and popular approach to predict the mesoscale microstructure evolution in various materials science,provides a bridge from atomic-scale methods to the macroscale and has been widely used at an ever-increasing rate.This paper aims to briefly review the origin,basic idea,and development of phase-field models in a historical manner.The focus is placed on the classical and state-of-the-art applications in China,including liquid–solid,solid–solid,gas–solid,ferroelectrics/ferromagnetics phase transformation,and crack propagation-fracture.After introducing the academic activities in the phase-field community in China,some suggestions for the future development directions of phase-field method are finally mentioned.
文摘Objective To develop a model of SHIV-KB9/Chinese origin rhesus （Ch Rh） macaques for vaccine research and to compare the pathogenesis of SHIV-KB9 in Ch Rh macaques with that reported in Indian rhesus （Ind Rh） macaques. Methods Seven mamu-A＊01 negative Ch Rh macaques were inoculated intravenously with 1-10000 MID50 of SHIV-KB9. The monkeys were monitored for viral load, CD4, CDS, SHIV-specific antibody and virus genetic variation. The results were compared with those previously observed in Ind Rh macaques. Results As compared to that observed in Ind Rh macaques, SHIV-KB9 in Ch Rh macaques displayed three identical disease progression patterns. However, the primary pattern was not identical between the two subspecies. The level of plasma viremia differed in SHIV-KB9-infected Ch Rh macaques which exhibited different outcomes from those in Ind Rh macaques. Generally, the values of viral load and the maintenance of CD4^＋ T cells were associated with humoral responses. Otherwise, the viral genetic distances （divergence, diversity） were larger in animals （M419, M425） with their CD4^＋ T cells profoundly depleted. Conclusion The model of SHIV-KB9/Ch Rh macaques displays a relatively slow progression to AIDS compared with Ind Rh macaques, which may more accurately reflect the potential of candidate vaccines in humans.
基金supported by the National Natural Science Foundation of China (Nos. 51701160, 51801186, and U1862117)Fundamental Research Funds for the Central Universities (No. 3102018zy046, and No. 2242019k1G003)the State Key Laboratory of Advanced Special Steel, Shanghai University, China (SKLASS2019-16)。
文摘Density change is ubiquitous in phase transformation, and it can induce melt convection which strongly influences the crystal growth. Here, an anisotropic lattice Boltzmann-phase-field method was extended to predict the dendritic growth under the shrinkage or expansion melt convection by density change induced. A novel LB equation with an anisotropic coefficient was constructed to model the advancement of ordering parameter, coupling with the passive scalar LB equation for convective and diffusive heat transfer during phase transition. We studied dendritic growth and shape selection with melt convection induced by density change in crystal growth. Results show that the melt convection induced by density change affects strongly the dendritic growth. The shrinkage flow results in a higher tip velocity while the expansion flow leads to a slower one. Predicted Péclet number with respect to the relative density change was compared with an analytical solution. Moreover, the modified selection parameter has been verified by numerical simulations.
基金financially supported by the National Natural Science Foundation of China (No. 51474174)Research Funds of the State Key Laboratory of Solidification Processing in NWPU (No. SKLSP201714)
文摘Degenerate pattern is a seemingly disordered morphology but it exhibits the inherently ordered crystal connected with tip-splitting and limited stability which makes it difficult to observe in the metallic system. Here we employ(100)[011] orientated planar-front seeds using directional solidification and reveal the fundamental origins of the degenerate pattern growth in an Al-4.5 wt% Cu alloy. We find that the spacing of the tip-splitting(λ) in the degenerate of the alloys followed a power law,λ∝V^-0.5, and the frequency(f) of the splitting was related to the growth velocity(V) by f ∝V^1.5. The dimensionless growth direction(θ/θ0) increased monotonously and approached 0.6 with faster velocity, attributed to its anisotropy in the interface kinetics. Once growth velocity exceeded a threshold, two types of pattern transitions from degenerate to regular dendrites were proposed. One of them exhibited a random and chaotic mode and the other underwent a rotation in growth direction.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51728601 and 51771118)the Fund of the State Key Laboratory of Solidification Processing in NPU(Grant No.SKLSP201901)the Fundamental Research Funds for the Central Universities,China(Grant No.2242019K1G003).
文摘Pattern selection during crystal growth is studied by using the anisotropic lattice Boltzmann-phase field model.In the model,the phase transition,melt flows,and heat transfer are coupled and mathematically described by using the lattice Boltzmann(LB)scheme.The anisotropic streaming-relaxation operation fitting into the LB framework is implemented to model interface advancing with various preferred orientations.Crystal pattern evolutions are then numerically investigated in the conditions of with and without melt flows.It is found that melt flows can significantly influence heat transfer,crystal growth behavior,and phase distributions.The crystal morphological transition from dendrite,seaweed to cauliflower-like patterns occurs with the increase of undercoolings.The interface normal angles and curvature distributions are proposed to quantitatively characterize crystal patterns.The results demonstrate that the distributions are corresponding to crystal morphological features,and they can be therefore used to describe the evolution of crystal patterns in a quantitative way.
