A solid solution 6063 aluminium alloy features an exceptional combination of strength and ductility at 77 K.Here,the deformation mechanisms responsible for superior strength-ductility synergy and excellent strain hard...A solid solution 6063 aluminium alloy features an exceptional combination of strength and ductility at 77 K.Here,the deformation mechanisms responsible for superior strength-ductility synergy and excellent strain hardening capacity at a cryogenic temperature of the alloy were comparatively investigated by insitu electron backscatter diffraction(EBSD)observations coupled with transmission electron microscopy(TEM)characterization and fracture morphologies at both 298 and 77 K.It is found that kernel average misorientation(KAM)mappings and quantified KAM in degree suggest a higher proportion of geometrically necessary dislocations(GNDs)at 77 K.The existence of orientation scatter partitions at 77 K implies the activation of multiple slip systems,which is consistent with the results of potential slip systems calculated by Taylor axes.Furthermore,dislocation tangles characterized by brief and curved dislocation cells and abundant small dimples have been observed at 77 K.This temperature-mediated activation of dislocations facilitates the increased dislocations,thus enhancing the strain hardening capacity and ductility of the alloy.This research enriches cryogenic deformation theory and provides valuable insights into the design of high-performance aluminium alloys that are suitable for cryogenic applications.展开更多
This work aims to reveal the actual effect of Zn and Ca additions on tensile properties and bendability of a recently designed Mg-3Al-0.2Mn(mass%,AM30)sheet with high formability.We fabricated AM30 and Mg-3Al-0.8Zn-0....This work aims to reveal the actual effect of Zn and Ca additions on tensile properties and bendability of a recently designed Mg-3Al-0.2Mn(mass%,AM30)sheet with high formability.We fabricated AM30 and Mg-3Al-0.8Zn-0.5Ca-0.2Mn(mass%,AZXM3100)sheets with weakly aligned(0001)poles.Their deformation behaviors were thoroughly investigated using electron backscattered diffraction and crystal plasticity simulation.We found that the Zn and Ca additions were not effective in improving the ductility and formability.Both the sheets showed large elongation to failure of~30% in tension,and their maximum bending angles during three-point bending were~90°.In-depth characterization of the deformation behaviors revealed that the Zn and Ca additions slightly facilitated tensile twinning,and the activity of the non-basal prismatic slip did not increase in the AZXM3100.Moreover,the Al_(2)Ca phase,which was formed in the AZXM3100,promoted the formation and propagation of cracks by concentrating plastic deformation.Therefore,ductility and formability could not be improved even after the Zn and Ca additions.展开更多
In this work,we investigated the mechanical properties and corresponding deformation mechanisms of an Al1Mg0.4Si alloy,which exhibited significantly higher strength and outstanding strain hardening capacity at 77 K co...In this work,we investigated the mechanical properties and corresponding deformation mechanisms of an Al1Mg0.4Si alloy,which exhibited significantly higher strength and outstanding strain hardening capacity at 77 K compared to its counterparts at 298 K.The deformation mechanisms responsible for the excellent strength-ductility synergy and extraordinary strain hardening capacity at cryogenic temperature were elucidated through a combined experimental and simulation study.The results reveal the presence of numerous slip traces and microbands throughout grain surfaces during deformation at 298 K,whereas at 77 K,vague grain surfaces dominate,indicating the simultaneous operation of multiple slip systems.Transmission electron microscopy(TEM)analysis using the two-beam diffraction technique demonstrates the presence of dislocations with several different Burgers vectors inside a grain at cryogenic temperature,confirming the activation of multiple slip systems.The accumulation of dislocations facilitated by these multiple slip systems,combined with the high dislocation density,contributes to strain hardening and remarkable uniform elongation at 77 K.A modified dislocation density-based crystal plasticity model,incorporating the effect of grain boundary hardening(GBH)and temperature,was developed to gain a better understanding of the underlying mechanisms governing alloy’s strength and plasticity.The GBH effect significantly enhances statistically stored dislocation(SSD)density and screw dislocation proportion,which promote homogeneous deformation and enhance strain hardening capacity at cryogenic temperature.These findings deepen the understanding of plastic deformation at cryogenic temperatures and pave the way for the development of ultrahigh-performance metallic materials for cryogenic applications.展开更多
1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7]...1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7],that indicate their potential for use in actu-ators,sensors,micropumps,energy harvesters,and solid-state re-frigeration[8-10].Among the alloys,Ni-Mn-Sn-based alloys are environment-friendly and cost-effective[6,7,11],and hence,they have received widespread attention.展开更多
为了解决传统抑郁症预测模型因过于依赖单一模型而难以有效应对数据复杂性的问题,提出了一种基于ABS-Stacking算法的抑郁症预测模型。在传统Stacking模型基础上采用最佳优先搜索算法构建基分类器筛选层,以自适应选择最优的基分类器组合...为了解决传统抑郁症预测模型因过于依赖单一模型而难以有效应对数据复杂性的问题,提出了一种基于ABS-Stacking算法的抑郁症预测模型。在传统Stacking模型基础上采用最佳优先搜索算法构建基分类器筛选层,以自适应选择最优的基分类器组合。通过5折交叉验证,根据各基模型在验证集上的AUC(area under curve)值对预测结果进行加权平均,使得表现较好的基模型在最终预测中贡献更大,从而提升模型的整体预测性能。在中老年结构化数据上的实验结果表明,ABS-Stacking模型在泛化能力和抑郁症预测效果上均优于单一模型和传统集成方法。该方法不仅有效解决了基分类器组合选择和性能加权的问题,还显著提高了模型的自适应性和泛化能力,为抑郁症预测提供了新的方法参考。展开更多
High thermal conductivity and high strength Mg-1.5Mn-2.5Ce alloy with a tensile yield strength of 387.0 MPa,ultimate tensile strength of 395.8 MPa,and thermal conductivity of 142.1 W/(m·K)was successfully fabrica...High thermal conductivity and high strength Mg-1.5Mn-2.5Ce alloy with a tensile yield strength of 387.0 MPa,ultimate tensile strength of 395.8 MPa,and thermal conductivity of 142.1 W/(m·K)was successfully fabricated via hot extrusion.The effects of La and Ce additions on the microstructure,thermal conductivity,and mechanical properties of the Mg-1.5Mn alloy were investigated.The results indicated that both the as-extruded Mg-1.5Mn-2.5La and Mg-1.5Mn-2.5Ce alloys exhibited a bimodal grain structure,with dynamically precipitated nano-scaleα-Mn phases.In comparison with La,the addition of Ce enhanced the dynamic precipitation more effectively during hot extrusion,while its influence on promoting the dynamic recrystallization was relatively weaker.The high tensile strength obtained in the as-extruded Mg-1.5Mn-2.5RE alloys can be attributed to the combined influence of the bimodal grain structure(with fine dynamic recrystallized(DRXed)grain size and high proportion of un-dynamic recrystallized(unDRXed)grains),dense nano-scale precipitates,and broken Mg12RE phases,while the remarkable thermal conductivity was due to the precipitation of Mn-rich phases from the Mg matrix.展开更多
The superelasticity and elastocaloric effect(eCE)in N-free Ti-Nb-Zr-Ta alloy and 0.6N(at.%)-doped Ti-Nb-Zr-Ta alloy were comparatively studied.It was found that nitrogen doping played roles in elevating β→α transit...The superelasticity and elastocaloric effect(eCE)in N-free Ti-Nb-Zr-Ta alloy and 0.6N(at.%)-doped Ti-Nb-Zr-Ta alloy were comparatively studied.It was found that nitrogen doping played roles in elevating β→α transition temperature,refining grain sizes,homogenizing microstructure and altering dominant texture index.The N-free Ti-Nb-Zr-Ta alloy exhibited a temperature change of +6.7/−6.5 K during load-ing/unloading processes in the first superelastic cycle,but gradually decreased to+5.7/−5.2 K in 200th cycle owing to the accumulation of newly codirectional dislocation lines and the following single-system dislocation slip during cyclic tests.By contrast,the N-doped alloy showed a lower initial temperature change of+3.7/−3.1 K but increased to+4.6/−4.1 K in 200th cycle due to the extra caloric effect generated from nanoscale O′phase to α″phase which experienced reorientation to favorable variants in early cycles.Residual α″phase laths derived from stress-induced martensitic transformation(SIMT)appeared in both alloys after tensile cycles.The phase interface between β and α″phase was determined to behave a terraced shape,a type of interface compromising the reversible martensitic transformation(MT)and stabilization of martensite phase.The amount of nanodomains(O′phase)in regions situated at a distance from martensite significantly increased after cycles in both alloys,which accounted for the quickly reached stable superelastic deformation and much narrower hysteresis after the first cycle.Therefore,in light of the reproducibility and reversibility of elastocaloric performance in practical application,N-doped β-Ti shape memory alloys(SMAs)are promising candidate materials.展开更多
In order to achieve the strength-ductility synergy and improve the work-hardening capacity,Ti64 based composites with dispersive nanoscaled TiB whiskers inside grains were fabricated by plasma rotating electrode proce...In order to achieve the strength-ductility synergy and improve the work-hardening capacity,Ti64 based composites with dispersive nanoscaled TiB whiskers inside grains were fabricated by plasma rotating electrode process coupled with spark plasma sintering.Based on the rapid eutectic reaction,the nanoscaled TiB whiskers exhibited ultra-fine network distribution in composite powders.During the spark plasma sintering process,the network dissolved,and TiB followed the Ostwald ripening mechanism and merged along the(100)plane.The intragranular TiB whiskers could significantly refine the primaryβgrain andαlath.The ultimate tensile strength of the composite with only 2 vol.%TiB whiskers was enhanced to(1123±17)MPa while the elongation was similar to that of the as-sintered Ti64 alloy with approximately 8%.The strength-ductility synergy effect was mainly attributed to the significant grain refinement and the work-hardening ability improvement contributed by intragranular nanoscaled TiB.展开更多
To assess the high-temperature creep properties of titanium matrix composites for aircraft skin,the TA15 alloy,TiB/TA15 and TiB/(TA15−Si)composites with network structure were fabricated using low-energy milling and v...To assess the high-temperature creep properties of titanium matrix composites for aircraft skin,the TA15 alloy,TiB/TA15 and TiB/(TA15−Si)composites with network structure were fabricated using low-energy milling and vacuum hot pressing sintering techniques.The results show that introducing TiB and Si can reduce the steady-state creep rate by an order of magnitude at 600℃ compared to the alloy.However,the beneficial effect of Si can be maintained at 700℃ while the positive effect of TiB gradually diminishes due to the pores near TiB and interface debonding.The creep deformation mechanism of the as-sintered TiB/(TA15−Si)composite is primarily governed by dislocation climbing.The high creep resistance at 600℃ can be mainly attributed to the absence of grain boundaryαphases,load transfer by TiB whisker,and the hindrance of dislocation movement by silicides.The low steady-state creep rate at 700℃ is mainly resulted from the elimination of grain boundaryαphases as well as increased dynamic precipitation of silicides andα_(2).展开更多
The long-lasting expectation“the hotter the engine,the better”calls for the development of high-temperature metallic alloys.Although the high specific strengths of titanium alloys are compelling for such application...The long-lasting expectation“the hotter the engine,the better”calls for the development of high-temperature metallic alloys.Although the high specific strengths of titanium alloys are compelling for such applications,their deleterious softening beyond 600℃ imposes serious limitations.Much has been known for decades regarding the phase metallurgy for precipitation strengthening design in titanium alloys,however,the other facile strength promotion mechanism,dispersion strengthening,remains comparatively less-explored and unutilized.The present research concerns the multi-scale dispersion strengthening in titanium alloys,with mechanistic emphases on the critical plasticity micro-events that affect strength preservation.Due to the simultaneous introduction of intragranular dispersoids and intergranular reinforcers,the current titanium alloys present superior engineering tensile strength of 519 MPa at 700℃.Throughout the examined 25-800℃ temperature range,noticeable softening induced by the thermal activation occurs above 600℃,accompanied by evident strength loss.The temperature-dependence transition of dominated softening mechanisms from dynamic recovery to dynamic recrystallization has been clarified by theoretical calculations.Furthermore,the strengthening effect of multi-scale architectures is underpinned as the enhanced dislocation strengthening owing to the introduction of thermally-stable heterointerfaces,which could generically guide the design of similar heat-resistant titanium alloys.展开更多
Magnesium(Mg)alloys typically suffer from cold brittleness at cryogenic temperatures(CT),where strength significantly increases and ductility decreases with decreasing temperature.This study investigates the improveme...Magnesium(Mg)alloys typically suffer from cold brittleness at cryogenic temperatures(CT),where strength significantly increases and ductility decreases with decreasing temperature.This study investigates the improvement of the strength-ductility balance at CT in Mg-3.6Y(wt.%)alloys with a bimodal grain structure,consisting of fine dynamically recrystallized(DRXed)grains and elongated unDRXed grains.The results demonstrate that the sample with∼50%DRXed region fraction achieves a remarkable strength-ductility synergy at CT.Dislocation strengthening in the unDRXed regions and grain boundary strengthening in the DRXed regions increase the tensile yield strength(TYS)by 1.6 times at CT compared to room temperature(RT).Concurrently,activation of{10¯12}tensile twinning and non-basal slip systems in DRXed regions,including prismatic a and pyramidal I c+a slips,along with abnormal pyramidal slip within unDRXed grains,reduces fracture elongation by only 1%relative to RT.Furthermore,the bimodal grain structure effectively alleviates strain localization through strain partitioning between DRXed and unDRXed grains,leading to the formation of interface-affected zones(IAZs)that promote the accumulation of geometrically necessary dislocations(GNDs)and enhance hetero-deformation-induced(HDI)hardening.At CT,the IAZs become wider and more pronounced,indicating enhanced GND accumulation that promotes stronger strain partitioning and more effective HDI strengthening.This work demonstrates that the bimodal grain structure is an effective approach to overcoming the low-temperature brittleness of Mg alloys,providing valuable insights for the design of high-performance materials for cryogenic applications.展开更多
BACKGROUND Type 2 diabetes mellitus(T2DM)is a metabolic disorder linked to high blood glucose and gut dysbiosis.Probiotics like Lactobacillus rhamnosus LRa05 may im-prove glycemic control and gut microbiota.AIM To exp...BACKGROUND Type 2 diabetes mellitus(T2DM)is a metabolic disorder linked to high blood glucose and gut dysbiosis.Probiotics like Lactobacillus rhamnosus LRa05 may im-prove glycemic control and gut microbiota.AIM To explore the impact of LRa05 with hypoglycemic medications on glycemic control and intestinal flora in T2DM patients with gut dysbiosis.METHODS Seventy-six participants were randomly assigned to receive either LRa05(0.1 g 2×10^(10) CFU)(n=38)or a placebo(n=38)for 12 weeks.Baseline characteristics were recorded,and changes in glycated hemoglobin,fasting blood glucose,and other biochemical indices were assessed using repeated measures one-way analysis of variance.Additionally,gut microbiota diversity was analyzed through species accumulation and alpha and beta diversity metrics.RESULTS The intervention group showed statistically significant improvements in lipid profiles,particularly in high-density lipoprotein cholesterol levels,which in-creased significantly over time(P<0.001).Additionally,fasting blood glucose was significantly reduced in the LRa05 group compared with the placebo group(P<0.001).No significant changes were observed in glycated hemoglobin,insulin sensitivity,or systemic inflammatory markers such as C-reactive protein.Fur-thermore,gut microbiota analysis revealed significant shifts in composition following the intervention,particularly an increase in Bifidobacterium and a de-crease in Bacillota,indicating beneficial effects on gut health.CONCLUSION This study demonstrated that the combination of Lactobacillus rhamnosus LRa05 and hypoglycemic medications positively impacted glycemic control,specifically reflected in improved levels of high-density lipoprotein and fasting blood glucose.Additionally,significant alterations in gut microbiota composition were observed in patients with T2DM,indicating a potential synergistic effect between gut health and blood glucose regulation.展开更多
Ni-Mn-Ga-Cu microwires,with diameter of 20-80 μm,length of 30-150 mm and fined columnar grains,were produced by melt-extraction technique.The damping capacity of the extracted micro wires was investigated by stretchi...Ni-Mn-Ga-Cu microwires,with diameter of 20-80 μm,length of 30-150 mm and fined columnar grains,were produced by melt-extraction technique.The damping capacity of the extracted micro wires was investigated by stretching a micro wire under a tensile stress using dynamic mechanical analyzer.The damping capacity of the martensite and austenite phases shows a weak frequency dependence but a strong strain amplitude dependence.The damping capacity(Tanδ) of the martensite and austenite phases reaches 0.08 and 0.04,respectively,under strain amplitude of 0.5% and frequency of 1 Hz.The high damping capacity of the martensite phase is related to the high mobility of martensite twin boudaries,while that of austenite phase to the motion of dislocations.The ferromagnetic Ni-Mn-Ga-Cu micro wires,with high ductility and damping capacity,may act as promising materials for microscale devices,systems and composite fillers for passive dissipation of undesired vibrations and noises.展开更多
Rivers are crucial in the spread of invasive plants.Invasive plants alter their seed traits to adapt to environmental changes and promote invasion.Studying the trait changes in invasive plant seeds may improve the und...Rivers are crucial in the spread of invasive plants.Invasive plants alter their seed traits to adapt to environmental changes and promote invasion.Studying the trait changes in invasive plant seeds may improve the understanding of their propagation mechanisms along the river and provide appropriate control measures.In this study,seven Ambrosia trifida populations along the Liaohe River were used as study subjects.The results showed that the seven A.trifida populations were closely related and exhibited a certain gene exchange,but the absence of evidence of directed gene flow among populations did not confirm that rivers were the medium of seed dispersal of A.trifida.Along the Liaohe River,from top to bottom,the positive view area,length,width,perimeter,and thousand seed weight of A.trifida seeds showed an increasing trend.The total nitrogen and phosphorus contents in the river water of the A.trifida population in the lower reaches of the Liaohe River were higher than those at the other sites.Furthermore,along the river,from top to bottom,the available nitrogen,total nitrogen,total potassium,available potassium,and organic matter contents in the soil in which A.trifida populations grew showed significant increasing trends.River structure,water quality,and soil nutrients had direct and indirect effects on seed morphology.Soil total nitrogen,available potassium,and organic matter had significant positive effects on seed positive view area and perimeter,suggesting that the maternal effect played a critical role in shaping seed morphology.Our analysis showed that soil nutrients along the river may be the primary driver that governs changes in A.trifida seed traits.展开更多
This is an erratum to the published paper titled “Lactobacillus rhamnosus LRa05 onglycemic control and gut microbiota in patients with type 2 diabetes”. We havenoticed that the names of the fourth author, Ms. Qin, a...This is an erratum to the published paper titled “Lactobacillus rhamnosus LRa05 onglycemic control and gut microbiota in patients with type 2 diabetes”. We havenoticed that the names of the fourth author, Ms. Qin, and the correspondingauthor, Dr. Qu, were spelled incorrectly. The correct names should be Ying Qinand Guang-Jin Qu, respectively.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.92263201,51927801,and 52001160)the National Key Research and Development Program of China(Grant No.2020YFA0405900).
文摘A solid solution 6063 aluminium alloy features an exceptional combination of strength and ductility at 77 K.Here,the deformation mechanisms responsible for superior strength-ductility synergy and excellent strain hardening capacity at a cryogenic temperature of the alloy were comparatively investigated by insitu electron backscatter diffraction(EBSD)observations coupled with transmission electron microscopy(TEM)characterization and fracture morphologies at both 298 and 77 K.It is found that kernel average misorientation(KAM)mappings and quantified KAM in degree suggest a higher proportion of geometrically necessary dislocations(GNDs)at 77 K.The existence of orientation scatter partitions at 77 K implies the activation of multiple slip systems,which is consistent with the results of potential slip systems calculated by Taylor axes.Furthermore,dislocation tangles characterized by brief and curved dislocation cells and abundant small dimples have been observed at 77 K.This temperature-mediated activation of dislocations facilitates the increased dislocations,thus enhancing the strain hardening capacity and ductility of the alloy.This research enriches cryogenic deformation theory and provides valuable insights into the design of high-performance aluminium alloys that are suitable for cryogenic applications.
基金supported by JSPS KAKENHI Grant Numbers JP22H00259,JP21H01669Osawa Scientific Studies Grants Foundation,Japan+3 种基金The Light Metal Educational Foundation,Inc.Japan,Natural Science Foundation of Heilongjiang Province-Outstanding Youth Fund(Grant No YQ2020E006)National Natural Science Foundation of China(52220105003,51971075)National Key Research&Development Program of China(2021YFB3703300,2022YFE0110600).
文摘This work aims to reveal the actual effect of Zn and Ca additions on tensile properties and bendability of a recently designed Mg-3Al-0.2Mn(mass%,AM30)sheet with high formability.We fabricated AM30 and Mg-3Al-0.8Zn-0.5Ca-0.2Mn(mass%,AZXM3100)sheets with weakly aligned(0001)poles.Their deformation behaviors were thoroughly investigated using electron backscattered diffraction and crystal plasticity simulation.We found that the Zn and Ca additions were not effective in improving the ductility and formability.Both the sheets showed large elongation to failure of~30% in tension,and their maximum bending angles during three-point bending were~90°.In-depth characterization of the deformation behaviors revealed that the Zn and Ca additions slightly facilitated tensile twinning,and the activity of the non-basal prismatic slip did not increase in the AZXM3100.Moreover,the Al_(2)Ca phase,which was formed in the AZXM3100,promoted the formation and propagation of cracks by concentrating plastic deformation.Therefore,ductility and formability could not be improved even after the Zn and Ca additions.
基金supported by the National Natural Science Foundation of China(Nos.92263201,51927801,52001160,and 52205378)the National Key Research&Development Plan(Nos.2020YFA0405900 and 2019YFA0708801)Natural Science Foundation of Jiangsu Province(No.BK20202010).
文摘In this work,we investigated the mechanical properties and corresponding deformation mechanisms of an Al1Mg0.4Si alloy,which exhibited significantly higher strength and outstanding strain hardening capacity at 77 K compared to its counterparts at 298 K.The deformation mechanisms responsible for the excellent strength-ductility synergy and extraordinary strain hardening capacity at cryogenic temperature were elucidated through a combined experimental and simulation study.The results reveal the presence of numerous slip traces and microbands throughout grain surfaces during deformation at 298 K,whereas at 77 K,vague grain surfaces dominate,indicating the simultaneous operation of multiple slip systems.Transmission electron microscopy(TEM)analysis using the two-beam diffraction technique demonstrates the presence of dislocations with several different Burgers vectors inside a grain at cryogenic temperature,confirming the activation of multiple slip systems.The accumulation of dislocations facilitated by these multiple slip systems,combined with the high dislocation density,contributes to strain hardening and remarkable uniform elongation at 77 K.A modified dislocation density-based crystal plasticity model,incorporating the effect of grain boundary hardening(GBH)and temperature,was developed to gain a better understanding of the underlying mechanisms governing alloy’s strength and plasticity.The GBH effect significantly enhances statistically stored dislocation(SSD)density and screw dislocation proportion,which promote homogeneous deformation and enhance strain hardening capacity at cryogenic temperature.These findings deepen the understanding of plastic deformation at cryogenic temperatures and pave the way for the development of ultrahigh-performance metallic materials for cryogenic applications.
基金supported by the National Key R&D Pro-gram of China(No.2022YFB3805701)National Natural Science Foundation of China(NSFC)(No.52371182,51701052,52192592,52192593)+1 种基金Young Elite Scientists Sponsorship Program by CAST(No.2019QNRC001)the Heilongjiang Touyan Innovation Team Program.
文摘1.Introduction.Ni-Mn-X(X=Ga,In,Sn,or Sb)Heusler alloys have versatile properties[1-4],such as shape memory effect[1],superelastic-ity[5],magnetocaloric effect[3],elastocaloric effect[6],and even multicaloric effect[7],that indicate their potential for use in actu-ators,sensors,micropumps,energy harvesters,and solid-state re-frigeration[8-10].Among the alloys,Ni-Mn-Sn-based alloys are environment-friendly and cost-effective[6,7,11],and hence,they have received widespread attention.
文摘为了解决传统抑郁症预测模型因过于依赖单一模型而难以有效应对数据复杂性的问题,提出了一种基于ABS-Stacking算法的抑郁症预测模型。在传统Stacking模型基础上采用最佳优先搜索算法构建基分类器筛选层,以自适应选择最优的基分类器组合。通过5折交叉验证,根据各基模型在验证集上的AUC(area under curve)值对预测结果进行加权平均,使得表现较好的基模型在最终预测中贡献更大,从而提升模型的整体预测性能。在中老年结构化数据上的实验结果表明,ABS-Stacking模型在泛化能力和抑郁症预测效果上均优于单一模型和传统集成方法。该方法不仅有效解决了基分类器组合选择和性能加权的问题,还显著提高了模型的自适应性和泛化能力,为抑郁症预测提供了新的方法参考。
基金supported by National Key Research&Development Program of China(Grant Nos.2021YFB3703300,2021YFE010016 and 2020YFA0405900)National Natural Science Foundation(Grant Nos.52220105003 and 51971075)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.FRFCU5710000918)Natural Science Foundation of Heilongjiang Province-Outstanding Youth Fund(Grant No.YQ2020E006)JSPS KAKENHI(Grant No.JP21H01669).
文摘High thermal conductivity and high strength Mg-1.5Mn-2.5Ce alloy with a tensile yield strength of 387.0 MPa,ultimate tensile strength of 395.8 MPa,and thermal conductivity of 142.1 W/(m·K)was successfully fabricated via hot extrusion.The effects of La and Ce additions on the microstructure,thermal conductivity,and mechanical properties of the Mg-1.5Mn alloy were investigated.The results indicated that both the as-extruded Mg-1.5Mn-2.5La and Mg-1.5Mn-2.5Ce alloys exhibited a bimodal grain structure,with dynamically precipitated nano-scaleα-Mn phases.In comparison with La,the addition of Ce enhanced the dynamic precipitation more effectively during hot extrusion,while its influence on promoting the dynamic recrystallization was relatively weaker.The high tensile strength obtained in the as-extruded Mg-1.5Mn-2.5RE alloys can be attributed to the combined influence of the bimodal grain structure(with fine dynamic recrystallized(DRXed)grain size and high proportion of un-dynamic recrystallized(unDRXed)grains),dense nano-scale precipitates,and broken Mg12RE phases,while the remarkable thermal conductivity was due to the precipitation of Mn-rich phases from the Mg matrix.
基金financially supported by the National Key R&D Program of China(No.2022YFB3805701)the National Natural Sci-ence Foundation of China(NSFC)(No.52371182)the Provincial Natural Science Foundation of China(Grant Number YQ2024E014).
文摘The superelasticity and elastocaloric effect(eCE)in N-free Ti-Nb-Zr-Ta alloy and 0.6N(at.%)-doped Ti-Nb-Zr-Ta alloy were comparatively studied.It was found that nitrogen doping played roles in elevating β→α transition temperature,refining grain sizes,homogenizing microstructure and altering dominant texture index.The N-free Ti-Nb-Zr-Ta alloy exhibited a temperature change of +6.7/−6.5 K during load-ing/unloading processes in the first superelastic cycle,but gradually decreased to+5.7/−5.2 K in 200th cycle owing to the accumulation of newly codirectional dislocation lines and the following single-system dislocation slip during cyclic tests.By contrast,the N-doped alloy showed a lower initial temperature change of+3.7/−3.1 K but increased to+4.6/−4.1 K in 200th cycle due to the extra caloric effect generated from nanoscale O′phase to α″phase which experienced reorientation to favorable variants in early cycles.Residual α″phase laths derived from stress-induced martensitic transformation(SIMT)appeared in both alloys after tensile cycles.The phase interface between β and α″phase was determined to behave a terraced shape,a type of interface compromising the reversible martensitic transformation(MT)and stabilization of martensite phase.The amount of nanodomains(O′phase)in regions situated at a distance from martensite significantly increased after cycles in both alloys,which accounted for the quickly reached stable superelastic deformation and much narrower hysteresis after the first cycle.Therefore,in light of the reproducibility and reversibility of elastocaloric performance in practical application,N-doped β-Ti shape memory alloys(SMAs)are promising candidate materials.
基金supported by the National Key R&D Program of China(No.2022YFB3707402)the National Natural Science Foundation of China(Nos.52301189,U22A20113)the Natural Science Foundation of Heilongjiang Province,China(No.LH2023E031).
文摘In order to achieve the strength-ductility synergy and improve the work-hardening capacity,Ti64 based composites with dispersive nanoscaled TiB whiskers inside grains were fabricated by plasma rotating electrode process coupled with spark plasma sintering.Based on the rapid eutectic reaction,the nanoscaled TiB whiskers exhibited ultra-fine network distribution in composite powders.During the spark plasma sintering process,the network dissolved,and TiB followed the Ostwald ripening mechanism and merged along the(100)plane.The intragranular TiB whiskers could significantly refine the primaryβgrain andαlath.The ultimate tensile strength of the composite with only 2 vol.%TiB whiskers was enhanced to(1123±17)MPa while the elongation was similar to that of the as-sintered Ti64 alloy with approximately 8%.The strength-ductility synergy effect was mainly attributed to the significant grain refinement and the work-hardening ability improvement contributed by intragranular nanoscaled TiB.
基金financially supported by the National Key R&D Program of China(No.2022YFB3707405)the National Natural Science Foundation of China(Nos.U22A20113,52171137,52071116)+1 种基金Heilongjiang Provincial Natural Science Foundation,China(No.TD2020E001)Heilongjiang Touyan Team Program,China.
文摘To assess the high-temperature creep properties of titanium matrix composites for aircraft skin,the TA15 alloy,TiB/TA15 and TiB/(TA15−Si)composites with network structure were fabricated using low-energy milling and vacuum hot pressing sintering techniques.The results show that introducing TiB and Si can reduce the steady-state creep rate by an order of magnitude at 600℃ compared to the alloy.However,the beneficial effect of Si can be maintained at 700℃ while the positive effect of TiB gradually diminishes due to the pores near TiB and interface debonding.The creep deformation mechanism of the as-sintered TiB/(TA15−Si)composite is primarily governed by dislocation climbing.The high creep resistance at 600℃ can be mainly attributed to the absence of grain boundaryαphases,load transfer by TiB whisker,and the hindrance of dislocation movement by silicides.The low steady-state creep rate at 700℃ is mainly resulted from the elimination of grain boundaryαphases as well as increased dynamic precipitation of silicides andα_(2).
基金financially supported by the National Key R&D Program of China(No.2021YFB3701203)the National Natural Science Foundation of China(Nos.U22A20113,52261135543,52171137 and 52071116)the Heilongjiang Touyan Team Program,Heilongjiang Provincial Natural Science Foundation of China(No.TD2020E001).
文摘The long-lasting expectation“the hotter the engine,the better”calls for the development of high-temperature metallic alloys.Although the high specific strengths of titanium alloys are compelling for such applications,their deleterious softening beyond 600℃ imposes serious limitations.Much has been known for decades regarding the phase metallurgy for precipitation strengthening design in titanium alloys,however,the other facile strength promotion mechanism,dispersion strengthening,remains comparatively less-explored and unutilized.The present research concerns the multi-scale dispersion strengthening in titanium alloys,with mechanistic emphases on the critical plasticity micro-events that affect strength preservation.Due to the simultaneous introduction of intragranular dispersoids and intergranular reinforcers,the current titanium alloys present superior engineering tensile strength of 519 MPa at 700℃.Throughout the examined 25-800℃ temperature range,noticeable softening induced by the thermal activation occurs above 600℃,accompanied by evident strength loss.The temperature-dependence transition of dominated softening mechanisms from dynamic recovery to dynamic recrystallization has been clarified by theoretical calculations.Furthermore,the strengthening effect of multi-scale architectures is underpinned as the enhanced dislocation strengthening owing to the introduction of thermally-stable heterointerfaces,which could generically guide the design of similar heat-resistant titanium alloys.
基金supported by National Key Research&Development Program of China[grant number 2022YFE0110600]National Natural Science Foundation[grant number 52220105003]the State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology[grant number XNDCQQ2910201124].
文摘Magnesium(Mg)alloys typically suffer from cold brittleness at cryogenic temperatures(CT),where strength significantly increases and ductility decreases with decreasing temperature.This study investigates the improvement of the strength-ductility balance at CT in Mg-3.6Y(wt.%)alloys with a bimodal grain structure,consisting of fine dynamically recrystallized(DRXed)grains and elongated unDRXed grains.The results demonstrate that the sample with∼50%DRXed region fraction achieves a remarkable strength-ductility synergy at CT.Dislocation strengthening in the unDRXed regions and grain boundary strengthening in the DRXed regions increase the tensile yield strength(TYS)by 1.6 times at CT compared to room temperature(RT).Concurrently,activation of{10¯12}tensile twinning and non-basal slip systems in DRXed regions,including prismatic a and pyramidal I c+a slips,along with abnormal pyramidal slip within unDRXed grains,reduces fracture elongation by only 1%relative to RT.Furthermore,the bimodal grain structure effectively alleviates strain localization through strain partitioning between DRXed and unDRXed grains,leading to the formation of interface-affected zones(IAZs)that promote the accumulation of geometrically necessary dislocations(GNDs)and enhance hetero-deformation-induced(HDI)hardening.At CT,the IAZs become wider and more pronounced,indicating enhanced GND accumulation that promotes stronger strain partitioning and more effective HDI strengthening.This work demonstrates that the bimodal grain structure is an effective approach to overcoming the low-temperature brittleness of Mg alloys,providing valuable insights for the design of high-performance materials for cryogenic applications.
文摘BACKGROUND Type 2 diabetes mellitus(T2DM)is a metabolic disorder linked to high blood glucose and gut dysbiosis.Probiotics like Lactobacillus rhamnosus LRa05 may im-prove glycemic control and gut microbiota.AIM To explore the impact of LRa05 with hypoglycemic medications on glycemic control and intestinal flora in T2DM patients with gut dysbiosis.METHODS Seventy-six participants were randomly assigned to receive either LRa05(0.1 g 2×10^(10) CFU)(n=38)or a placebo(n=38)for 12 weeks.Baseline characteristics were recorded,and changes in glycated hemoglobin,fasting blood glucose,and other biochemical indices were assessed using repeated measures one-way analysis of variance.Additionally,gut microbiota diversity was analyzed through species accumulation and alpha and beta diversity metrics.RESULTS The intervention group showed statistically significant improvements in lipid profiles,particularly in high-density lipoprotein cholesterol levels,which in-creased significantly over time(P<0.001).Additionally,fasting blood glucose was significantly reduced in the LRa05 group compared with the placebo group(P<0.001).No significant changes were observed in glycated hemoglobin,insulin sensitivity,or systemic inflammatory markers such as C-reactive protein.Fur-thermore,gut microbiota analysis revealed significant shifts in composition following the intervention,particularly an increase in Bifidobacterium and a de-crease in Bacillota,indicating beneficial effects on gut health.CONCLUSION This study demonstrated that the combination of Lactobacillus rhamnosus LRa05 and hypoglycemic medications positively impacted glycemic control,specifically reflected in improved levels of high-density lipoprotein and fasting blood glucose.Additionally,significant alterations in gut microbiota composition were observed in patients with T2DM,indicating a potential synergistic effect between gut health and blood glucose regulation.
基金financially supported by the Ministry of Science and Technology Bureau of Harbin(No.2011RFQXG001)
文摘Ni-Mn-Ga-Cu microwires,with diameter of 20-80 μm,length of 30-150 mm and fined columnar grains,were produced by melt-extraction technique.The damping capacity of the extracted micro wires was investigated by stretching a micro wire under a tensile stress using dynamic mechanical analyzer.The damping capacity of the martensite and austenite phases shows a weak frequency dependence but a strong strain amplitude dependence.The damping capacity(Tanδ) of the martensite and austenite phases reaches 0.08 and 0.04,respectively,under strain amplitude of 0.5% and frequency of 1 Hz.The high damping capacity of the martensite phase is related to the high mobility of martensite twin boudaries,while that of austenite phase to the motion of dislocations.The ferromagnetic Ni-Mn-Ga-Cu micro wires,with high ductility and damping capacity,may act as promising materials for microscale devices,systems and composite fillers for passive dissipation of undesired vibrations and noises.
基金funded by the National Key Research and Development Program of China(2022YFF1301004)the National Key R&D Program(2023YFC2604500).
文摘Rivers are crucial in the spread of invasive plants.Invasive plants alter their seed traits to adapt to environmental changes and promote invasion.Studying the trait changes in invasive plant seeds may improve the understanding of their propagation mechanisms along the river and provide appropriate control measures.In this study,seven Ambrosia trifida populations along the Liaohe River were used as study subjects.The results showed that the seven A.trifida populations were closely related and exhibited a certain gene exchange,but the absence of evidence of directed gene flow among populations did not confirm that rivers were the medium of seed dispersal of A.trifida.Along the Liaohe River,from top to bottom,the positive view area,length,width,perimeter,and thousand seed weight of A.trifida seeds showed an increasing trend.The total nitrogen and phosphorus contents in the river water of the A.trifida population in the lower reaches of the Liaohe River were higher than those at the other sites.Furthermore,along the river,from top to bottom,the available nitrogen,total nitrogen,total potassium,available potassium,and organic matter contents in the soil in which A.trifida populations grew showed significant increasing trends.River structure,water quality,and soil nutrients had direct and indirect effects on seed morphology.Soil total nitrogen,available potassium,and organic matter had significant positive effects on seed positive view area and perimeter,suggesting that the maternal effect played a critical role in shaping seed morphology.Our analysis showed that soil nutrients along the river may be the primary driver that governs changes in A.trifida seed traits.
文摘This is an erratum to the published paper titled “Lactobacillus rhamnosus LRa05 onglycemic control and gut microbiota in patients with type 2 diabetes”. We havenoticed that the names of the fourth author, Ms. Qin, and the correspondingauthor, Dr. Qu, were spelled incorrectly. The correct names should be Ying Qinand Guang-Jin Qu, respectively.
