A new technical prototype for producing Fe-6.5wt% Si electrical steel sheets by directional solidification, heat treatment before rolling, warm rolling, and cold rolling was proposed in the present study. The formabil...A new technical prototype for producing Fe-6.5wt% Si electrical steel sheets by directional solidification, heat treatment before rolling, warm rolling, and cold rolling was proposed in the present study. The formability of Fe-6.5wt% Si electrical steel before rolling and the reasonable process parameters of this technical prototype were obtained. Experimental results reveal that the formability of Fe-6.5wt% Si electrical steel is improved significantly under the combination of directional solidification and heat treatment before rolling. Fe-6.5wt% Si electrical steel sheets with the thickness of 0.15 ram, bright surface, few edge cracks, and high rolling yield can be successfully fabricated using this technology without any intermediate annealing during the whole rolling. The combination of directional solidification, heat treatment before rolling, warm rolling, and cold rolling can work as a new process for highly efficient and compact fabrication of Fe-6.5wt% Si electrical steel sheets.展开更多
A reconstruction technology of finite element meshes based on reversal engineering was applied to solve mesh penetration and separation in the finite element simulation for the divergent extrusion. The 3D numerical si...A reconstruction technology of finite element meshes based on reversal engineering was applied to solve mesh penetration and separation in the finite element simulation for the divergent extrusion. The 3D numerical simulation of the divergent extrusion process in- cluding the welding stage for complicated hollow sections was conducted. Based on the analysis of flowing behaviors, the flowing velocities of the alloy in portholes and near the welding planes were properly controlled through optimizing the expansion angle as well as porthole ar- eas and positions. After the die structure optimization, defects such as warp, wrist, and the wavelike are eliminated, which improves the sec- tion-forming quality. Meanwhile, the temperature distribution in the cross section is uniform. Especially, the temperature of the C-shape notch with a larger thickness is lower than that of other regions in the cross section, which is beneficial for balancing the alloy flowing velocity.展开更多
Taking extruded Al–Zn–Mg–Cu alloy(7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigat...Taking extruded Al–Zn–Mg–Cu alloy(7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigated. The results show that a pre-annealing treatment at 350°C for 15 h before a T6 treatment substantially reduced the sensitivity of the microstructure and mechanical properties of the extruded 7A04 aluminum alloy specimens toward the extrusion temperature. The average grain sizes of the specimens extruded at 390 and 430°C after T6 treatment were 3.4 and 8.1 μm, respectively, and their elongations to failure were 7.0% and 9.2%, respectively. However, after pre-annealing + T6 treatment, the differences in both the grain sizes and the elongations of the specimens became small, i.e., their average grain sizes were 3.2 and 3.8 μm and their elongations were 12.0% and 13.3%, respectively. For the specimens extruded at the same temperature, pre-annealing treatment obviously improved the plasticity of the alloy, which is attributed to an increase in soft texture or to grain refinement in the specimens as a result of the pre-annealing + T6 treatment.展开更多
As a classic noninvasive physiotherapy,photobiomodulation,also known as low-level laser therapy,is widely used for the treatment of many diseases and has anti-inflammatory and tissue repair effects.Photobiomodulation ...As a classic noninvasive physiotherapy,photobiomodulation,also known as low-level laser therapy,is widely used for the treatment of many diseases and has anti-inflammatory and tissue repair effects.Photobiomodulation has been shown to promote spinal cord injury repair.In our previous study,we found that 810 nm low-level laser therapy reduced the M1 polarization of macrophages and promoted motor function recovery.However,the mechanism underlying this inhibitory effect is not clear.In recent years,transcriptome sequencing analysis has played a critical role in elucidating the progression of diseases.Therefore,in this study,we performed M1 polarization on induced mouse bone marrow macrophages and applied low-level laser therapy.Our sequencing results showed the differential gene expression profile of photobiomodulation regulating macrophage polarization.We analyzed these genes using gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses.Networks of protein-protein interactions and competing RNA endogenous networks were constructed.We found that photobiomodulation inhibited STAT3 expression through increasing the expression of miR-330-5p,and that miR-330-5p binding to STAT3 inhibited STAT3 expression.Inducible nitric oxide synthase showed trends in changes similar to the changes in STAT3 expression.Finally,we treated a mouse model of spinal cord injury using photobiomodulation and confirmed that photobiomodulation reduced inducible nitric oxide synthase and STAT3 expression and promoted motor function recovery in spinal cord injury mice.These findings suggest that STAT3 may be a potential target of photobiomodulation,and the miR-330-5p/STAT3 pathway is a possible mechanism by which photobiomodulation has its biological effects.展开更多
Increasing evidence indicates that mitochonarial lission imbalance plays an important role in derayed neuronal cell death. Our previous study round that photo biomodulation improved the motor function of rats with spi...Increasing evidence indicates that mitochonarial lission imbalance plays an important role in derayed neuronal cell death. Our previous study round that photo biomodulation improved the motor function of rats with spinal cord injury.However,the precise mechanism remains unclear.To investigate the effect of photo biomodulation on mitochondrial fission imbalance after spinal cord injury,in this study,we treated rat models of spinal co rd injury with 60-minute photo biomodulation(810 nm,150 mW) every day for 14 consecutive days.Transmission electron microscopy results confirmed the swollen and fragmented alte rations of mitochondrial morphology in neurons in acute(1 day) and subacute(7 and 14 days) phases.Photo biomodulation alleviated mitochondrial fission imbalance in spinal cord tissue in the subacute phase,reduced neuronal cell death,and improved rat posterior limb motor function in a time-dependent manner.These findings suggest that photobiomodulation targets neuronal mitochondria,alleviates mitochondrial fission imbalance-induced neuronal apoptosis,and thereby promotes the motor function recovery of rats with spinal cord injury.展开更多
Background: Lower mean platelet volume(MPV) is an indicator of platelet activity in the setting of tumor development. This study was to assess the relationship between preoperative MPV and survival outcomes of patient...Background: Lower mean platelet volume(MPV) is an indicator of platelet activity in the setting of tumor development. This study was to assess the relationship between preoperative MPV and survival outcomes of patients with hepatocellular carcinoma(HCC) following liver transplantation(LT). Methods: The demographic and clinical characteristics of 304 HCC patients following LT were retrieved from an LT database. All the patients were divided into the normal and lower MPV groups according to the median MPV. The factors were first analyzed using a Kaplan–Meier survival analysis, then the factors with P < 0.10 were selected for multivariate Cox regression analysis and were used to define the independent risk factors for poor prognosis. Results: The 1-, 3-, and 5-year tumor free survival was 95.34%, 74.67% and 69.29% in the normal MPV group, respectively, and 95.40%, 59.97% and 42.94% in the lower MPV group, respectively( P < 0.01). No significant difference was observed in post-LT complications between the normal and lower MPV groups. Portal vein tumor thrombosis(PVTT)[hazard ratio(HR = 2.24;95% confidence interval: 1.46–3.43;P < 0.01) and lower MPV(HR = 1.58;95% confidence interval: 1.05–2.36;P = 0.03) were identified as independent prognostic risk factors for recipient survival. Conclusion: Preoperative lower MPV is a risk indicator of HCC patients survival outcomes after LT.展开更多
In order to develop high strength,high damping and low density Al matrix composites,the Al/Zn composite bar samples with Zn mass fraction of 10%-40%were prepared by powder extrusion.The tensile strength and damping pr...In order to develop high strength,high damping and low density Al matrix composites,the Al/Zn composite bar samples with Zn mass fraction of 10%-40%were prepared by powder extrusion.The tensile strength and damping properties of the samples are improved by controlling both the Zn/Al diffusion degree and the precipitation of the interfacial phases.The results show that the tensile strength of the samples with Zn mass fraction of 10%-30%increases with the increases of both the Zn content and annealing temperature.When the Zn mass fraction increases to 40%,the tensile strength of the sample remains basically unchanged or decreases slightly,and the plasticity decreases gradually.Alloying of Al matrix and the formation of Zn/Al interface layer are mainly responsible for improving the strength of the annealed samples.The damping properties increase with the increases of both the Zn content and annealing temperature.The Zn/Al eutectoid lamella eliminates the detrimental effects on damping properties due to both alloying of the Al matrix and reduction of pure Zn in the Al matrix.The Al-30%Zn sample annealed at 350°C for 0.5 h has good comprehensive properties,including the tensile strength of 330 MPa,the elongation to failure of 10%and the room-temperature damping properties(tanθ)of 0.025.展开更多
The effects of annealing temperature(with the annealing time being constant at 1 h) on the microstructure, ordering, residual stress, mechanical properties, and subsequent cold rolling workability of Fe-6.5wt%Si ele...The effects of annealing temperature(with the annealing time being constant at 1 h) on the microstructure, ordering, residual stress, mechanical properties, and subsequent cold rolling workability of Fe-6.5wt%Si electrical steel with columnar grains were investigated, where the steel was warm rolled at 500℃ with a reduction of 95%. The results show that recrystallization began to occur in the sample annealed at 575℃ and that full recrystallization occurred in the sample annealed at 625℃. When the annealing temperature was 500℃ or greater, the extent of reordering in the sample was high, which reduced the room-temperature plasticity. However, annealing at temperatures below 300℃ did not significantly reduce the residual tensile stress on the edge of the warm rolled samples. Considering the comprehensive effects of annealing temperature on the recrystallization, reordering, residual stress, and mechanical properties of the warm rolled Fe-6.5wt%Si electrical steel with columnar grains, the appropriate annealing temperature range is 300℃-400℃. Unlike the serious edge cracks that appeared in the sample after direct cold rolling, the annealed samples could be cold rolled to a total reduction of more than 71.4% without the formation of obvious edge cracks, and bright-surface Fe-6.5wt%Si electrical steel strips with a thickness less than 0.1 mm could be fabricated by cold rolling.展开更多
Based on the parent austenite orientation reconstruction method,it is aimed to reveal the origination of high angle grain boundaries(HAGBs)and its relationship with ductility of H13 steel.The orientation relationship ...Based on the parent austenite orientation reconstruction method,it is aimed to reveal the origination of high angle grain boundaries(HAGBs)and its relationship with ductility of H13 steel.The orientation relationship between martensite and parent austenite of quenched H13 samples was(123.5°,9.3°,192.5°),which agreed with the Kurdumov–Sachs relationship.The variant distribution of quenched samples was dominated by close-packed plane group,and its high length fraction of V1/V2 inter-variant boundaries of calculated 62.6%was mainly contributed to HAGBs(>45°).When the quenched H13 samples underwent the pre-tempering treatment,their density of HAGBs(>45°)notably increased from 1.33 to 2.39μm^(−1),which improved its total elongation from 8.3%to 11.5%.Compared with the quenched H13 samples,the length fraction of V1/V2 inter-variant boundaries of H13 samples with pre-tempering for 5,10 and 60 min was reduced by 6.7%,7.0%and 7.5%,respectively.During pre-tempering treatment,V1/V3&V5 variant pairs,etc.,merged V1/V2 variant pair by strain-induced grain boundary migration,which decreased the length fraction of V1/V2 inter-variant boundaries by 7.0%.The pre-tempering treatment significantly increased HAGBs(>45°)of H13 samples by sub-grains coarsening and strain-induced grain boundary migration mechanism.展开更多
Topological phases in non-Hermitian systems have become fascinating subjects recently.In this paper,we attempt to classify topological phases in 1D interacting non-Hermitian systems.We begin with the non-Hermitian gen...Topological phases in non-Hermitian systems have become fascinating subjects recently.In this paper,we attempt to classify topological phases in 1D interacting non-Hermitian systems.We begin with the non-Hermitian generalization of the Su-Schrieffer-Heeger(SSH)model and discuss its many-body topological Berry phase,which is well defined for all interacting quasi-Hermitian systems(non-Hermitian systems that have real energy spectrum).We then demonstrate that the classification of topological phases for quasi-Hermitian systems is exactly the same as their Hermitian counterparts.Finally,we construct the fixed point partition function for generic 1D interacting non-Hermitian local systems and find that the fixed point partition function still has a one-to-one correspondence to their Hermitian counterparts.Thus,we conclude that the classification of topological phases for generic 1D interacting non-Hermitian systems is still exactly the same as Hermitian systems.展开更多
Deformation behaviors and mechanisms under different temperatures for columnar-grained Fe 6.5Si (mass%) alloys fabricated by directional solidification and equiaxed grained Fe-6.5Si alloy fabricated by forging were ...Deformation behaviors and mechanisms under different temperatures for columnar-grained Fe 6.5Si (mass%) alloys fabricated by directional solidification and equiaxed grained Fe-6.5Si alloy fabricated by forging were comparatively investigated. The results showed that, with increasing the deformation temperature from 300℃ to 500℃, the elongation increased from 2.9% to 30.1% for the equiaxed-grained Fe-6.5Si alloy, while from 6.6% to about 51% for the columnar-grained Fe-6.5Si alloy. The deformation mode of equiaxed-grained Fe 6.5Si alloy trans ferred from nearly negligible plastic deformation to large plastic deformation dominated by dislocation slipping. Comparatively, the deformation mode of the columnar grained alloy transferred from nearly negligible plastic deformation to plastic deformation dominated by the twining, and finally to plastic deformation dominated by dislocation slipping. Meanwhile, compared with the alloy with equiaxed grains, it was found that ultimate tensile strength and elongation could be increased simultaneously, which was ascribed for the twinning deformation in columnar-grained Fe-6.5Si al loy. This work would assist us to further understand the plastic deformation mechanism of Fe-6.5Si alloy and pro vide more clues for high-efficiency production of the alloy.展开更多
Effect of titanium microalloying on the microstructure and mechanical properties of vanadium microalloyed steels for hot forging was studied.Titanium microalloying improves the mechanical properties mainly through ref...Effect of titanium microalloying on the microstructure and mechanical properties of vanadium microalloyed steels for hot forging was studied.Titanium microalloying improves the mechanical properties mainly through refining the austenite grains.When the heating temperature is in the range of 1050–1300℃,the austenite grain diameter is decreased from 77–133 to 26–68μm by titanium microalloying.With the decrease in austenite grain diameter,the final microstructure is refined significantly,and the high misorientation boundaries are increased.After the steel is heated at 1200℃(the common hot forging temperature)and cooled slowly,titanium microalloying decreases the yield strength from 548.4 to 519.4 MPa,and the tensile strength decreases from 842.7 to 808.7 MPa.However,the elongation increases from 19.0%to 21.4%,and the impact energy increases from 9.8 to 38.2 J.V–Ti steel has a better combination of strength,plasticity and toughness than V steel.In addition,the nucleation of intragranular ferrite idiomorphs is promoted by titanium microalloying,which may have a beneficial effect on the property of steels with coarse microstructure caused by the critical deformation in hot die forging.展开更多
Morphology and distribution of precipitates in the Fe-6.5Si-0.02B alloy were characterized, and these effects on room- temperature compression cracks were investigated. The results showed that the precipitate in the F...Morphology and distribution of precipitates in the Fe-6.5Si-0.02B alloy were characterized, and these effects on room- temperature compression cracks were investigated. The results showed that the precipitate in the Fe-6.5Si-0.02B alloy is FezB with body-centered tetragonal structure, and its nano-hardness is 15.0 GPa which is higher than that of the matrix (- 8.5 GPa). In the as-cast alloys, most of the intragranular precipitates are coarse lath-like with the length of 5-15 μm and width of 2-5 μm, and the precipitates formed at the grain boundaries are of about 2-3 μm in width. After oil quenching followed by heat treatment at 1100 ℃ for more than 30 min, the precipitates inside grains are refined with a size of several hundred nanometers and the precipitates at the grain boundaries are refined with a size of 〈 1 μm. After compression test, transgranular and intergranular cracks occur in the as-cast alloys with coarse precipitates. For the quenched alloys with fine precipitates, the number of cracks decreases significantly, and no transgranular cracks happen because some cracks are blocked or the propagation direction is changed by grain boundary.展开更多
Micro-deformation behavior and mechanical properties of columnar-grained Fe-6.5 mass%Si alloy before and after warm rolling were investigated by means of micro-indentation and three-point bending tests.The results sho...Micro-deformation behavior and mechanical properties of columnar-grained Fe-6.5 mass%Si alloy before and after warm rolling were investigated by means of micro-indentation and three-point bending tests.The results show that the columnar-grained Fe-6.5mass%Si alloy before warm rolling presents sink-in mode of micro-indentation,while pile-up mode with a number of arc-shaped deformation bands exists in the warm-rolled alloy.Compared with that of the alloy before warm rolling,the maximum bending fracture stress and maximum bending fracture deflection of the warm-rolled alloy are increased by 96% and 50%,respectively.The different micro-deformation behavior and mechanical properties of the columnar-grained Fe-6.5mass%Si alloy are ascribed to the changes of dislocation density,dislocation configuration and long-range order degree,which significantly improve the room temperature plasticity of the alloy after warm rolling.展开更多
The dynamic behaviors of a single vesicle bounded by the cylindrical wall in a Poiseuille flow were investigated by considering different confinements and dimensionless shear rates. By observing the evolution of two a...The dynamic behaviors of a single vesicle bounded by the cylindrical wall in a Poiseuille flow were investigated by considering different confinements and dimensionless shear rates. By observing the evolution of two adjacent particles attached to the internal and external surfaces of the spherical vesicles, we found they had the same frequency. The vorticity trajectories formed by the time-tracing of the particles on the membrane are parallel, which can be identified as the unsteady rolling motion of the membranes due to the unfixed axis. The dynamic behaviors of vesicles are associated with the confinement degree and the dimensionless shear rate. The smaller dimensionless shear rate will result in the slower frequency of the rolling by examining the velocity of the rolling. The weakened rolling motion under stronger confinements is observed by measuring the evolution of the orientation angles. The changes of revolution axes over time can be interpreted by the lateral excursion of the center of mass on the orthogonal plane of the flow.展开更多
基金supported by the Major States Basic Research Development Program of China(No.2011CB606300)China Postdoctoral Science Foundation(No.2012M520263)
文摘A new technical prototype for producing Fe-6.5wt% Si electrical steel sheets by directional solidification, heat treatment before rolling, warm rolling, and cold rolling was proposed in the present study. The formability of Fe-6.5wt% Si electrical steel before rolling and the reasonable process parameters of this technical prototype were obtained. Experimental results reveal that the formability of Fe-6.5wt% Si electrical steel is improved significantly under the combination of directional solidification and heat treatment before rolling. Fe-6.5wt% Si electrical steel sheets with the thickness of 0.15 ram, bright surface, few edge cracks, and high rolling yield can be successfully fabricated using this technology without any intermediate annealing during the whole rolling. The combination of directional solidification, heat treatment before rolling, warm rolling, and cold rolling can work as a new process for highly efficient and compact fabrication of Fe-6.5wt% Si electrical steel sheets.
文摘A reconstruction technology of finite element meshes based on reversal engineering was applied to solve mesh penetration and separation in the finite element simulation for the divergent extrusion. The 3D numerical simulation of the divergent extrusion process in- cluding the welding stage for complicated hollow sections was conducted. Based on the analysis of flowing behaviors, the flowing velocities of the alloy in portholes and near the welding planes were properly controlled through optimizing the expansion angle as well as porthole ar- eas and positions. After the die structure optimization, defects such as warp, wrist, and the wavelike are eliminated, which improves the sec- tion-forming quality. Meanwhile, the temperature distribution in the cross section is uniform. Especially, the temperature of the C-shape notch with a larger thickness is lower than that of other regions in the cross section, which is beneficial for balancing the alloy flowing velocity.
基金financially supported by the National Key Technologies R & D Program of China (No. 2016YFB0300901)
文摘Taking extruded Al–Zn–Mg–Cu alloy(7A04 alloy) bars as the research object, the effect and mechanism of pre-annealing treatments on the microstructure and mechanical properties of the aged alloy bars were investigated. The results show that a pre-annealing treatment at 350°C for 15 h before a T6 treatment substantially reduced the sensitivity of the microstructure and mechanical properties of the extruded 7A04 aluminum alloy specimens toward the extrusion temperature. The average grain sizes of the specimens extruded at 390 and 430°C after T6 treatment were 3.4 and 8.1 μm, respectively, and their elongations to failure were 7.0% and 9.2%, respectively. However, after pre-annealing + T6 treatment, the differences in both the grain sizes and the elongations of the specimens became small, i.e., their average grain sizes were 3.2 and 3.8 μm and their elongations were 12.0% and 13.3%, respectively. For the specimens extruded at the same temperature, pre-annealing treatment obviously improved the plasticity of the alloy, which is attributed to an increase in soft texture or to grain refinement in the specimens as a result of the pre-annealing + T6 treatment.
基金supported by the National Natural Science Foundation of China,Nos.81070996(to ZW),81572151(to XYH)Shaanxi Provincial Key R&D Program,China,Nos.2020ZDLSF02-05(to ZW),2021ZDLSF02-10(to XYH)。
文摘As a classic noninvasive physiotherapy,photobiomodulation,also known as low-level laser therapy,is widely used for the treatment of many diseases and has anti-inflammatory and tissue repair effects.Photobiomodulation has been shown to promote spinal cord injury repair.In our previous study,we found that 810 nm low-level laser therapy reduced the M1 polarization of macrophages and promoted motor function recovery.However,the mechanism underlying this inhibitory effect is not clear.In recent years,transcriptome sequencing analysis has played a critical role in elucidating the progression of diseases.Therefore,in this study,we performed M1 polarization on induced mouse bone marrow macrophages and applied low-level laser therapy.Our sequencing results showed the differential gene expression profile of photobiomodulation regulating macrophage polarization.We analyzed these genes using gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses.Networks of protein-protein interactions and competing RNA endogenous networks were constructed.We found that photobiomodulation inhibited STAT3 expression through increasing the expression of miR-330-5p,and that miR-330-5p binding to STAT3 inhibited STAT3 expression.Inducible nitric oxide synthase showed trends in changes similar to the changes in STAT3 expression.Finally,we treated a mouse model of spinal cord injury using photobiomodulation and confirmed that photobiomodulation reduced inducible nitric oxide synthase and STAT3 expression and promoted motor function recovery in spinal cord injury mice.These findings suggest that STAT3 may be a potential target of photobiomodulation,and the miR-330-5p/STAT3 pathway is a possible mechanism by which photobiomodulation has its biological effects.
基金supported by the National Natural Science Foundation of China,Nos.81070996 (to ZW) and 815 72151 (to XYH)Shaanxi Provincial Key R&D Program,Nos.2020ZDLSF02-05 (to ZW),2021ZDLSF02-10 (to XYH)。
文摘Increasing evidence indicates that mitochonarial lission imbalance plays an important role in derayed neuronal cell death. Our previous study round that photo biomodulation improved the motor function of rats with spinal cord injury.However,the precise mechanism remains unclear.To investigate the effect of photo biomodulation on mitochondrial fission imbalance after spinal cord injury,in this study,we treated rat models of spinal co rd injury with 60-minute photo biomodulation(810 nm,150 mW) every day for 14 consecutive days.Transmission electron microscopy results confirmed the swollen and fragmented alte rations of mitochondrial morphology in neurons in acute(1 day) and subacute(7 and 14 days) phases.Photo biomodulation alleviated mitochondrial fission imbalance in spinal cord tissue in the subacute phase,reduced neuronal cell death,and improved rat posterior limb motor function in a time-dependent manner.These findings suggest that photobiomodulation targets neuronal mitochondria,alleviates mitochondrial fission imbalance-induced neuronal apoptosis,and thereby promotes the motor function recovery of rats with spinal cord injury.
基金supported by grants from the Natural Science Foundation of Zhejiang Province(Y17H160118,LY18H030002 and LQ15H030003)the Fundamental Research Funds for the Cen-tral University(2018FZA7002)
文摘Background: Lower mean platelet volume(MPV) is an indicator of platelet activity in the setting of tumor development. This study was to assess the relationship between preoperative MPV and survival outcomes of patients with hepatocellular carcinoma(HCC) following liver transplantation(LT). Methods: The demographic and clinical characteristics of 304 HCC patients following LT were retrieved from an LT database. All the patients were divided into the normal and lower MPV groups according to the median MPV. The factors were first analyzed using a Kaplan–Meier survival analysis, then the factors with P < 0.10 were selected for multivariate Cox regression analysis and were used to define the independent risk factors for poor prognosis. Results: The 1-, 3-, and 5-year tumor free survival was 95.34%, 74.67% and 69.29% in the normal MPV group, respectively, and 95.40%, 59.97% and 42.94% in the lower MPV group, respectively( P < 0.01). No significant difference was observed in post-LT complications between the normal and lower MPV groups. Portal vein tumor thrombosis(PVTT)[hazard ratio(HR = 2.24;95% confidence interval: 1.46–3.43;P < 0.01) and lower MPV(HR = 1.58;95% confidence interval: 1.05–2.36;P = 0.03) were identified as independent prognostic risk factors for recipient survival. Conclusion: Preoperative lower MPV is a risk indicator of HCC patients survival outcomes after LT.
基金Project(2016YFB0300901)supported by the National Key Research and Development Program of China
文摘In order to develop high strength,high damping and low density Al matrix composites,the Al/Zn composite bar samples with Zn mass fraction of 10%-40%were prepared by powder extrusion.The tensile strength and damping properties of the samples are improved by controlling both the Zn/Al diffusion degree and the precipitation of the interfacial phases.The results show that the tensile strength of the samples with Zn mass fraction of 10%-30%increases with the increases of both the Zn content and annealing temperature.When the Zn mass fraction increases to 40%,the tensile strength of the sample remains basically unchanged or decreases slightly,and the plasticity decreases gradually.Alloying of Al matrix and the formation of Zn/Al interface layer are mainly responsible for improving the strength of the annealed samples.The damping properties increase with the increases of both the Zn content and annealing temperature.The Zn/Al eutectoid lamella eliminates the detrimental effects on damping properties due to both alloying of the Al matrix and reduction of pure Zn in the Al matrix.The Al-30%Zn sample annealed at 350°C for 0.5 h has good comprehensive properties,including the tensile strength of 330 MPa,the elongation to failure of 10%and the room-temperature damping properties(tanθ)of 0.025.
基金financially supported by the National Basic Research Program of China (No. 2011CB606300)the National High Technology Research and Development Program of China (No. 2012AA03A505)the China Postdoctoral Science Foundation (No. 2013T60110)
文摘The effects of annealing temperature(with the annealing time being constant at 1 h) on the microstructure, ordering, residual stress, mechanical properties, and subsequent cold rolling workability of Fe-6.5wt%Si electrical steel with columnar grains were investigated, where the steel was warm rolled at 500℃ with a reduction of 95%. The results show that recrystallization began to occur in the sample annealed at 575℃ and that full recrystallization occurred in the sample annealed at 625℃. When the annealing temperature was 500℃ or greater, the extent of reordering in the sample was high, which reduced the room-temperature plasticity. However, annealing at temperatures below 300℃ did not significantly reduce the residual tensile stress on the edge of the warm rolled samples. Considering the comprehensive effects of annealing temperature on the recrystallization, reordering, residual stress, and mechanical properties of the warm rolled Fe-6.5wt%Si electrical steel with columnar grains, the appropriate annealing temperature range is 300℃-400℃. Unlike the serious edge cracks that appeared in the sample after direct cold rolling, the annealed samples could be cold rolled to a total reduction of more than 71.4% without the formation of obvious edge cracks, and bright-surface Fe-6.5wt%Si electrical steel strips with a thickness less than 0.1 mm could be fabricated by cold rolling.
基金The research is financially supported by the National Key Research and Development Program of China(Nos.2016YFB0300900 and 2017YFB0306202).
文摘Based on the parent austenite orientation reconstruction method,it is aimed to reveal the origination of high angle grain boundaries(HAGBs)and its relationship with ductility of H13 steel.The orientation relationship between martensite and parent austenite of quenched H13 samples was(123.5°,9.3°,192.5°),which agreed with the Kurdumov–Sachs relationship.The variant distribution of quenched samples was dominated by close-packed plane group,and its high length fraction of V1/V2 inter-variant boundaries of calculated 62.6%was mainly contributed to HAGBs(>45°).When the quenched H13 samples underwent the pre-tempering treatment,their density of HAGBs(>45°)notably increased from 1.33 to 2.39μm^(−1),which improved its total elongation from 8.3%to 11.5%.Compared with the quenched H13 samples,the length fraction of V1/V2 inter-variant boundaries of H13 samples with pre-tempering for 5,10 and 60 min was reduced by 6.7%,7.0%and 7.5%,respectively.During pre-tempering treatment,V1/V3&V5 variant pairs,etc.,merged V1/V2 variant pair by strain-induced grain boundary migration,which decreased the length fraction of V1/V2 inter-variant boundaries by 7.0%.The pre-tempering treatment significantly increased HAGBs(>45°)of H13 samples by sub-grains coarsening and strain-induced grain boundary migration mechanism.
基金supported by the National Key Research and Development Program of China (2016YFA0300300)the National Natural Science Foundation of China (NSFC+4 种基金11861161001)NSFC/RGC Joint Research Scheme (N-CUHK427/18)the Science, Technology and Innovation Commission of Shenzhen Municipality (ZDSYS20190902092905285)Guangdong Basic and Applied Basic Research Foundation under Grant No. 2020B1515120100Center for Computational Science and Engineering of Southern University of Science and Technology。
文摘Topological phases in non-Hermitian systems have become fascinating subjects recently.In this paper,we attempt to classify topological phases in 1D interacting non-Hermitian systems.We begin with the non-Hermitian generalization of the Su-Schrieffer-Heeger(SSH)model and discuss its many-body topological Berry phase,which is well defined for all interacting quasi-Hermitian systems(non-Hermitian systems that have real energy spectrum).We then demonstrate that the classification of topological phases for quasi-Hermitian systems is exactly the same as their Hermitian counterparts.Finally,we construct the fixed point partition function for generic 1D interacting non-Hermitian local systems and find that the fixed point partition function still has a one-to-one correspondence to their Hermitian counterparts.Thus,we conclude that the classification of topological phases for generic 1D interacting non-Hermitian systems is still exactly the same as Hermitian systems.
基金Item Sponsored by Major States Basic Research Development Program of China(2011CB606300)National Natural Science Foundation of China(51504023)+1 种基金Fundamental Research Funds for the Central Universities of China(FRF-TP-15-051A2)State Key Laboratory of Advanced Metals and Materials Foundation of China(2014-Z06)
文摘Deformation behaviors and mechanisms under different temperatures for columnar-grained Fe 6.5Si (mass%) alloys fabricated by directional solidification and equiaxed grained Fe-6.5Si alloy fabricated by forging were comparatively investigated. The results showed that, with increasing the deformation temperature from 300℃ to 500℃, the elongation increased from 2.9% to 30.1% for the equiaxed-grained Fe-6.5Si alloy, while from 6.6% to about 51% for the columnar-grained Fe-6.5Si alloy. The deformation mode of equiaxed-grained Fe 6.5Si alloy trans ferred from nearly negligible plastic deformation to large plastic deformation dominated by dislocation slipping. Comparatively, the deformation mode of the columnar grained alloy transferred from nearly negligible plastic deformation to plastic deformation dominated by the twining, and finally to plastic deformation dominated by dislocation slipping. Meanwhile, compared with the alloy with equiaxed grains, it was found that ultimate tensile strength and elongation could be increased simultaneously, which was ascribed for the twinning deformation in columnar-grained Fe-6.5Si al loy. This work would assist us to further understand the plastic deformation mechanism of Fe-6.5Si alloy and pro vide more clues for high-efficiency production of the alloy.
基金The authors appreciate the financial support by the China Postdoctoral Science Foundation(2019TQ0031)the Fundamental Research Funds for the Central Universities(FRF-TP-20-030A1)the State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2021-002).
文摘Effect of titanium microalloying on the microstructure and mechanical properties of vanadium microalloyed steels for hot forging was studied.Titanium microalloying improves the mechanical properties mainly through refining the austenite grains.When the heating temperature is in the range of 1050–1300℃,the austenite grain diameter is decreased from 77–133 to 26–68μm by titanium microalloying.With the decrease in austenite grain diameter,the final microstructure is refined significantly,and the high misorientation boundaries are increased.After the steel is heated at 1200℃(the common hot forging temperature)and cooled slowly,titanium microalloying decreases the yield strength from 548.4 to 519.4 MPa,and the tensile strength decreases from 842.7 to 808.7 MPa.However,the elongation increases from 19.0%to 21.4%,and the impact energy increases from 9.8 to 38.2 J.V–Ti steel has a better combination of strength,plasticity and toughness than V steel.In addition,the nucleation of intragranular ferrite idiomorphs is promoted by titanium microalloying,which may have a beneficial effect on the property of steels with coarse microstructure caused by the critical deformation in hot die forging.
基金This research was funded by the Major States Basic Research Development Program of China (973 Program, No. 2011CB606300) and China Postdoctoral Science Foundation (Nos. 2012M520263 and 2013T60110).
文摘Morphology and distribution of precipitates in the Fe-6.5Si-0.02B alloy were characterized, and these effects on room- temperature compression cracks were investigated. The results showed that the precipitate in the Fe-6.5Si-0.02B alloy is FezB with body-centered tetragonal structure, and its nano-hardness is 15.0 GPa which is higher than that of the matrix (- 8.5 GPa). In the as-cast alloys, most of the intragranular precipitates are coarse lath-like with the length of 5-15 μm and width of 2-5 μm, and the precipitates formed at the grain boundaries are of about 2-3 μm in width. After oil quenching followed by heat treatment at 1100 ℃ for more than 30 min, the precipitates inside grains are refined with a size of several hundred nanometers and the precipitates at the grain boundaries are refined with a size of 〈 1 μm. After compression test, transgranular and intergranular cracks occur in the as-cast alloys with coarse precipitates. For the quenched alloys with fine precipitates, the number of cracks decreases significantly, and no transgranular cracks happen because some cracks are blocked or the propagation direction is changed by grain boundary.
基金Item Sponsored by Major State Basic Research Development Program of China(2011CB606300)National Natural Science Foundation of China(51504023)+1 种基金Fundamental Research Funds for the Central Universities of China(FRF-TP-15-051A2)State Key Laboratory of Advanced Metals and Materials Foundation of China(2014-Z06)
文摘Micro-deformation behavior and mechanical properties of columnar-grained Fe-6.5 mass%Si alloy before and after warm rolling were investigated by means of micro-indentation and three-point bending tests.The results show that the columnar-grained Fe-6.5mass%Si alloy before warm rolling presents sink-in mode of micro-indentation,while pile-up mode with a number of arc-shaped deformation bands exists in the warm-rolled alloy.Compared with that of the alloy before warm rolling,the maximum bending fracture stress and maximum bending fracture deflection of the warm-rolled alloy are increased by 96% and 50%,respectively.The different micro-deformation behavior and mechanical properties of the columnar-grained Fe-6.5mass%Si alloy are ascribed to the changes of dislocation density,dislocation configuration and long-range order degree,which significantly improve the room temperature plasticity of the alloy after warm rolling.
基金financially supported by the National Natural Science Foundation of China (Nos.21973041,22173045,21973040,21674047 and 21734005)the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT)the Fundamental Research Funds for the Central Universities。
文摘The dynamic behaviors of a single vesicle bounded by the cylindrical wall in a Poiseuille flow were investigated by considering different confinements and dimensionless shear rates. By observing the evolution of two adjacent particles attached to the internal and external surfaces of the spherical vesicles, we found they had the same frequency. The vorticity trajectories formed by the time-tracing of the particles on the membrane are parallel, which can be identified as the unsteady rolling motion of the membranes due to the unfixed axis. The dynamic behaviors of vesicles are associated with the confinement degree and the dimensionless shear rate. The smaller dimensionless shear rate will result in the slower frequency of the rolling by examining the velocity of the rolling. The weakened rolling motion under stronger confinements is observed by measuring the evolution of the orientation angles. The changes of revolution axes over time can be interpreted by the lateral excursion of the center of mass on the orthogonal plane of the flow.