Kid, Hurry and Grab Mom's hand. It's too dark around here——the road To the heaven. I'm afraid Something mav hurt your head. Hurry and Grab my hand. Let's move on Side by side.
Die Walküre is the most frequently staged and most popular title of the Ring cycle among classical music enthusiasts.It tells a complex story that involves intertwined relationships between father and daughter,hu...Die Walküre is the most frequently staged and most popular title of the Ring cycle among classical music enthusiasts.It tells a complex story that involves intertwined relationships between father and daughter,husband and wife,brother and sister,and lovers in the epic context of the Nordic mythology.展开更多
This study investigates the formation feasibility of the integrated bottom car body components with dual die casting injection molding technology.During the production of a die-cast super-large one-piece body part wei...This study investigates the formation feasibility of the integrated bottom car body components with dual die casting injection molding technology.During the production of a die-cast super-large one-piece body part weighing over 10,000 t,a thorough comparison and investigation were conducted on the arising issues,using both single and double injection systems.Particular attention was given to meticulously discussing the die casting filling problems and microstructural defects that originated from the filling process.The research findings indicate that the implementation of a double injection system can significantly minimize cold shuts and reduce the solidification time.The effectiveness of this die casting technique was further confirmed by the production of high-quality castings using a scaled model that replicated real casting conditions at a 1:3 ratio,thereby maintaining a one-to-one correspondence in essential aspects.This successful study offers both theoretical insights and practical applications for the production of integrated bottom car bodies utilizing die casting in conjunction with a dual injection system.展开更多
Dynamic recrystallization(DRX)in inhomogeneous deformation zones,such as grain boundaries,shear bands,and deformation bands,is critical for texture modification in magnesium alloys during deformation at elevated temper...Dynamic recrystallization(DRX)in inhomogeneous deformation zones,such as grain boundaries,shear bands,and deformation bands,is critical for texture modification in magnesium alloys during deformation at elevated temperatures.This study investigates the DRX mechanisms in AZWX3100 magnesium alloy under plane strain compression at 200℃.Microstructural analysis revealed necklace-type DRX accompanied by evidence of local grain boundary bulging.Additionally,ribbons of recrystallized grains were observed withinfine deformation bands,aligned with theoretical pyramidal I and II slip traces derived from the matrix.The distribution of local misorientation within the deformed microstructure demonstrated a clear association between deformation bands and localized strain.Dislocation analysis of lamellar specimens extracted from two pyramidal slip bands revealed<c+a>dislocations,indicating a connection between<c+a>slip activation and the formation of deformation bands.Crystal plasticity simulations suggest that the orientation of deformation bands is responsible for the unique recrystallization texture of the DRX grains within these bands.The texture characteristics imply a progressive,glide-induced DRX mechanism.A fundamental understanding of the role of deformation bands in texture modification can facilitate future alloy and process design.展开更多
A novel oxide-dispersion-strengthened(ODS)die steel was fabricated by mechanical alloying and hot consolidation.Annealing and quench-tempering treatments both obtained an ultra-fine grain structure(mean size:310-330 n...A novel oxide-dispersion-strengthened(ODS)die steel was fabricated by mechanical alloying and hot consolidation.Annealing and quench-tempering treatments both obtained an ultra-fine grain structure(mean size:310-330 nm)with an ultra-high density of ultra-fine Y-Al-O nano-oxides(number density:~(1-1.5)×10^(23)m^(−3),mean size:5.1-7.2 nm).Prolonged thermal exposure further induced the new,highly dense precipitation of ultra-fine Y-Zr-O nano-oxides.Both nano-oxides tended to be wrapped up with a B2-NiAl nano-shells.Although the quench-tempered sample showed much higher room-temperature strength(yield strength=1393±40 MPa and ultimate tensile strength=1774±11 MPa)and slightly lower elongation(elongation=13.6%±0.6%)than the annealed sample(YS=988±7 MPa,UTS=1490±12 MPa,and EL=15.2%±1.1%),both samples exhibited better strength-ductility synergy at room temperature and much higher thermal stabilities at high temperatures(600-700℃)than all those conventional hot-work die steels,which makes the new ODS steel highly promising for advanced hot-work mold and die applications at high temperatures above 600℃.展开更多
Achieving optimal mechanical performance in high-pressure die-cast(HPDC)Mg-based alloys through experimental methods is both costly and time-intensive due to significant variations in composition.This study leverages ...Achieving optimal mechanical performance in high-pressure die-cast(HPDC)Mg-based alloys through experimental methods is both costly and time-intensive due to significant variations in composition.This study leverages machine learning(ML)techniques to accelerate the development of high-performance Mg-based alloys.Data on alloy composition and mechanical properties were collected from literature sources,focusing on HPDC Mg-based alloys.Six ML models—extra trees,CatBoost,k-nearest neighbors,random forest,gradient boosting,and decision tree—were trained to predict mechanical behavior.Cat Boost yielded the highest prediction accuracy with R^(2) scores of 0.95 for ultimate tensile strength(UTS)and 0.92 for yield strength(YS).Further validation using published datasets reaffirmed its reliability,demonstrating R^(2) values of 0.956(UTS)and 0.936(YS),MAE of 1%and 2.8%,and RMSE of 1%and 3.5%,respectively.Among these,the CatBoost model demonstrated the highest predictive accuracy,outperforming other ML techniques across multiple optimization metrics.展开更多
Unwarranted death of neurons is a major cause of neurodegenerative diseases.Since mature neurons are postmitotic and do not replicate,their death usually constitutes an irreversible step in pathology.A logical strateg...Unwarranted death of neurons is a major cause of neurodegenerative diseases.Since mature neurons are postmitotic and do not replicate,their death usually constitutes an irreversible step in pathology.A logical strategy to prevent neurodegeneration would then be to save all neurons that are still alive,i.e.protecting the ones that are still healthy as well as trying to rescue the ones that are damaged and in the process of dying.Regarding the latter,recent experiments have indicated that the possibility of reversing the cell death process and rescuing dying cells is more significant than previously anticipated.In many situations,the elimination of the cell death trigger alone enables dying cells to spontaneously repair their damage,recover,and survive.In this review,we explore the factors,which determine the fate of neurons engaged in the cell death process.A deeper insight into cell death mechanisms and the intrinsic capacity of cells to recover could pave the way for novel therapeutic approaches to neurodegenerative diseases.展开更多
High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicle...High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.展开更多
This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on t...This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.展开更多
“遥远的共鸣”,是卡普马吉他全国巡演的主题,同时作为新的指弹专辑名称。主人公亦有两位——Casper Esmann、Eddie van der Meer。二人平日里相距甚远,Casper生活在丹麦,Eddie定居于墨西哥。可即便如此,他们还是走向了同一方舞台,并将...“遥远的共鸣”,是卡普马吉他全国巡演的主题,同时作为新的指弹专辑名称。主人公亦有两位——Casper Esmann、Eddie van der Meer。二人平日里相距甚远,Casper生活在丹麦,Eddie定居于墨西哥。可即便如此,他们还是走向了同一方舞台,并将各自的音乐融合成了一副声音,在纵横交错的情绪流转间交织为彼此的同类。展开更多
国家大剧院制作歌剧《指环》之《女武神》即将登场NCPA’s Die Walküre to grace the stage继2024年8月国家大剧院制作《指环》系列的首部作品《莱茵的黄金》震撼亮相后,该系列第二部《女武神》将于4月29日、5月1日、5月3日登台国...国家大剧院制作歌剧《指环》之《女武神》即将登场NCPA’s Die Walküre to grace the stage继2024年8月国家大剧院制作《指环》系列的首部作品《莱茵的黄金》震撼亮相后,该系列第二部《女武神》将于4月29日、5月1日、5月3日登台国家大剧院歌剧节·2025。本轮演出将由对瓦格纳作品有着丰富诠释经验的国际知名指挥家皮塔里·因基宁执棒。瓦格纳的音乐是因基宁艺术生涯的重心,他曾在拜罗伊特音乐节上呈献瓦格纳的《指环》全剧,此次执棒《女武神》也将是因基宁继2008年之后再度登台国家大剧院,他将携手国家大剧院管弦乐团与一众国内外实力派歌唱家共同谱写这部情感澎湃的壮丽乐章。曾因执导德利布歌剧《拉克美》在国家大剧院舞台上大放异彩的重量级导演达维德·利维摩尔再度操刀,此次他将担任《女武神》的导演,并深度参与歌剧的舞美设计工作,率领主创团队运用更具创新性的多媒体舞台语汇,为观众呈献一个更加绚丽、充满奇幻色彩的“指环宇宙”。展开更多
修辞学结构论是一种专门研究语篇描写的理论,以篇章结构为研究重点,致力于通过分析语篇结构阐述作者的交际意图在语篇中是如何实现的。通过观察修辞结构关系的类别与分布状况,能够了解语篇的核心思想、连贯特性以及写作特色等基础信息...修辞学结构论是一种专门研究语篇描写的理论,以篇章结构为研究重点,致力于通过分析语篇结构阐述作者的交际意图在语篇中是如何实现的。通过观察修辞结构关系的类别与分布状况,能够了解语篇的核心思想、连贯特性以及写作特色等基础信息。本文将采用修辞结构理论的描述框架对Peter Bichsel的短篇小说Die Tochter的语篇结构进行描述和解释,思考修辞结构理论对于该小说的语篇结构分析能力。根据分析,修辞结构理论可以分析出结构段的中心思想,但是无法把握整篇小说的主旨;修辞结构较多且连接十分紧密,连贯性较强;作者多用背景关系和解释关系进行叙述,先交代背景,再塑造人物,风格细腻。Rhetorical Structure Theory (RST) is a comprehensive set of theories dedicated to describing natural discourse. It emphasizes the structure of texts and aims to elucidate how authors’ communicative intentions are realized through textual analysis. By examining the types and distribution of rhetorical structural relationships, one can gain insights into the central idea, coherence features, writing characteristics, and other fundamental aspects of a text. This paper employs the descriptive framework of Rhetorical Structure Theory to describe and explain the text structure of Peter Bichsel’s short story Die Tochter and reflects on the efficacy of RST in analyzing the textual structure of novels. The analysis reveals that RST can effectively dissect the central idea of individual structural paragraphs but struggles to encapsulate the overarching theme of the entire novel. Furthermore, the rhetorical structures are numerous and tightly interconnected, contributing to a strong sense of coherence. The author frequently utilizes background and explanation relationships in the narration, first establishing the context and then developing the characters, resulting in a nuanced and refined style.展开更多
The microstructure and mechanical properties of the Ti-5Al-5Mo-5V-1Cr-1Fe(Ti-55511)alloy under different strains were investigated through the design of step-shaped die forging.The results indicate that continuous dyn...The microstructure and mechanical properties of the Ti-5Al-5Mo-5V-1Cr-1Fe(Ti-55511)alloy under different strains were investigated through the design of step-shaped die forging.The results indicate that continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX)occur in the high strain region.The orientation of the grains produced by CDRX is random and does not weaken the fiber texture.<100>-oriented grains expand gradually with increasing strain,thereby enhancing the strength of{100}texture.Significant anisotropic mechanical properties are observed in the large strain region and analyzed through in-situ tensile experiments.When the loading direction is parallel to the longitudinal(L)direction,strain concentration is observed near the dynamically recrystallized(DRXed)grains and inside grains oriented along<100>,leading to crack initiation.Furthermore,the small angle between the loading direction and the c-axis hinders the activation of prismatic and basal slip,thereby enhancing the strength.When the loading direction is parallel to the short transverse(ST)direction,cracks are initiated not only within grains oriented along<100>,but also at the grain boundaries.Regarding impact toughness,the elongatedβgrains in the L direction enhance the resistance to crack propagation.展开更多
The development and application of large Die⁃Casting Al Alloy(DCAA)parts and Thermo⁃Formed Steel Sheets(TFSS)in Body⁃in⁃White(BIW)have created higher demands for the joining technology of high⁃strength steel/Al dissim...The development and application of large Die⁃Casting Al Alloy(DCAA)parts and Thermo⁃Formed Steel Sheets(TFSS)in Body⁃in⁃White(BIW)have created higher demands for the joining technology of high⁃strength steel/Al dissimilar materials.As an emerging technology,Flush Self⁃Piercing Riveting(FSPR)is still in the experimental phase and undergoing small batch equipment verification.This paper focuses on the joining methods for DCAA and TFSS in BIW,investigating the joining mechanisms,technical features,and forming principles of FSPR for steel/Al dissimilar materials with two⁃layer or three⁃layer plate combinations.Considering the TL4225/C611/CR5 sheet combination as a subject,the forming mechanism of high⁃quality joints was studied,and a physical and mathematical model was established to depict the relationship between the filling amount of the arc⁃gap and die dimensions,as well as the extrusion amount.This model effectively illustrates the relationship between the filling amount of the flowing metal in the arc⁃gap and critical parameters,such as die dimensions and feeding amounts.By simplifying the process of selecting joining parameters,it significantly reduces both the time and experimental workload associated with parameter selection.This provides a technical foundation for the application of DAAA and TFSS parts in BIW,enabling the rapid choice of appropriate joining parameters to meet the requirements for obtaining high⁃quality joints.The model can be effectively utilized to investigate the relationships between key parameters,including arc⁃gap radius,plate thickness,rivet arc radius,nail head radius,groove width,and feeding amount,while keeping other parameters constant.This approach provides a theoretical foundation for the design of Friction Stir Processing(FSP)joints and aids in the selection of optimal parameters.展开更多
Larger-sized primary carbides lead to stress concentration during the application of H13 hot-work die steel,resulting in microcracks and fatigue failure.Rare earth was usually added to modify the carbides and inclusio...Larger-sized primary carbides lead to stress concentration during the application of H13 hot-work die steel,resulting in microcracks and fatigue failure.Rare earth was usually added to modify the carbides and inclusions.The existing literature is reviewed on the effect of rare earth on primary carbides in H13 steel.A comprehensive review on the effect of rare earth on the characteristics of primary carbides,i.e.,number,size,morphology,and thermal stability in H13 steel,was done.The precipitation mechanism and nucleation of primary carbides with rare earth were summarized.The position and form of rare earth in steel and their effects on alloying elements segregation were reviewed.The addition techniques of rare earth in H13 steel were compared,and the prospects for other uncommon rare earth and emerging technology were present.Based on the current references,it can be known that adding rare earth facilitated refined and dispersed primary carbides.The size of primary carbides would be reduced,and their morphology would be improved because the rare earth inclusions formed in H13 steel can act as nucleation cores forγ-Fe orδ-Fe,refining the dendritic structure.Besides,the number of primary carbides at grain boundaries would be significantly reduced.However,rare earth had little impact on thermal stability.The nucleation of primary carbides tended to be inhibited due to the modification of inclusions by rare earth which were likely to be nucleation cores for primary carbides.Rare earth had been reported to affect the mechanism and process of primary carbide precipitation.Additionally,the addition of rare earth can inhibit the segregation of alloying elements and carbon diffusion by calculation.Thus,laboratory experiments and theoretical calcu-lations need to be conducted to study the states and evolution of rare earth steels.展开更多
The effect of slow shot speed on externally solidified crystal(ESC),porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy(OM),scanning electron mi...The effect of slow shot speed on externally solidified crystal(ESC),porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy(OM),scanning electron microscopy(SEM)and laboratory computed tomography(CT).Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg alloy.The AlSi9MnMoV alloy,which was designed with trace multicomponent additions,displays a notable grain refining effect in comparison to the AlSi10MnMg alloy.Refining elements Ti,Zr,V,Nb,B promote heterogeneous nucleation and reduce the grain size of primaryα-Al.At a lower slow shot speed,the large ESCs are easier to form and gather,developing into the dendrite net and net-shrinkage.With an increase in slow shot speed,the size and number of ESCs and porosities significantly reduce.In addition,the distribution of ESCs is more dispersed and the net-shrinkage disappears.The tensile property is greatly improved by adopting a higher slow shot speed.The ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa(increased by 11.52%),and the elongation is enhanced from 3.72%to 6.34%(increased by 70.52%).展开更多
文摘Kid, Hurry and Grab Mom's hand. It's too dark around here——the road To the heaven. I'm afraid Something mav hurt your head. Hurry and Grab my hand. Let's move on Side by side.
文摘Die Walküre is the most frequently staged and most popular title of the Ring cycle among classical music enthusiasts.It tells a complex story that involves intertwined relationships between father and daughter,husband and wife,brother and sister,and lovers in the epic context of the Nordic mythology.
基金supported by the National Natural Science Foundation of China(No.52175284)the National Key Research and Development Program of China(Grant No.2022YFB3404201).
文摘This study investigates the formation feasibility of the integrated bottom car body components with dual die casting injection molding technology.During the production of a die-cast super-large one-piece body part weighing over 10,000 t,a thorough comparison and investigation were conducted on the arising issues,using both single and double injection systems.Particular attention was given to meticulously discussing the die casting filling problems and microstructural defects that originated from the filling process.The research findings indicate that the implementation of a double injection system can significantly minimize cold shuts and reduce the solidification time.The effectiveness of this die casting technique was further confirmed by the production of high-quality castings using a scaled model that replicated real casting conditions at a 1:3 ratio,thereby maintaining a one-to-one correspondence in essential aspects.This successful study offers both theoretical insights and practical applications for the production of integrated bottom car bodies utilizing die casting in conjunction with a dual injection system.
基金by the Deutsche Forschungsgemeinschaft(DFG)through projects 420149269,394480829as part of the CRC1394“Structural and Chemical Atomic Complexity-From Defect Phase Diagrams to Material Properties”(project 409476157).
文摘Dynamic recrystallization(DRX)in inhomogeneous deformation zones,such as grain boundaries,shear bands,and deformation bands,is critical for texture modification in magnesium alloys during deformation at elevated temperatures.This study investigates the DRX mechanisms in AZWX3100 magnesium alloy under plane strain compression at 200℃.Microstructural analysis revealed necklace-type DRX accompanied by evidence of local grain boundary bulging.Additionally,ribbons of recrystallized grains were observed withinfine deformation bands,aligned with theoretical pyramidal I and II slip traces derived from the matrix.The distribution of local misorientation within the deformed microstructure demonstrated a clear association between deformation bands and localized strain.Dislocation analysis of lamellar specimens extracted from two pyramidal slip bands revealed<c+a>dislocations,indicating a connection between<c+a>slip activation and the formation of deformation bands.Crystal plasticity simulations suggest that the orientation of deformation bands is responsible for the unique recrystallization texture of the DRX grains within these bands.The texture characteristics imply a progressive,glide-induced DRX mechanism.A fundamental understanding of the role of deformation bands in texture modification can facilitate future alloy and process design.
基金support from the National MCF Energy R&D Program of China(No.2018YFE0306100).
文摘A novel oxide-dispersion-strengthened(ODS)die steel was fabricated by mechanical alloying and hot consolidation.Annealing and quench-tempering treatments both obtained an ultra-fine grain structure(mean size:310-330 nm)with an ultra-high density of ultra-fine Y-Al-O nano-oxides(number density:~(1-1.5)×10^(23)m^(−3),mean size:5.1-7.2 nm).Prolonged thermal exposure further induced the new,highly dense precipitation of ultra-fine Y-Zr-O nano-oxides.Both nano-oxides tended to be wrapped up with a B2-NiAl nano-shells.Although the quench-tempered sample showed much higher room-temperature strength(yield strength=1393±40 MPa and ultimate tensile strength=1774±11 MPa)and slightly lower elongation(elongation=13.6%±0.6%)than the annealed sample(YS=988±7 MPa,UTS=1490±12 MPa,and EL=15.2%±1.1%),both samples exhibited better strength-ductility synergy at room temperature and much higher thermal stabilities at high temperatures(600-700℃)than all those conventional hot-work die steels,which makes the new ODS steel highly promising for advanced hot-work mold and die applications at high temperatures above 600℃.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2021R1A6A1A10044950)。
文摘Achieving optimal mechanical performance in high-pressure die-cast(HPDC)Mg-based alloys through experimental methods is both costly and time-intensive due to significant variations in composition.This study leverages machine learning(ML)techniques to accelerate the development of high-performance Mg-based alloys.Data on alloy composition and mechanical properties were collected from literature sources,focusing on HPDC Mg-based alloys.Six ML models—extra trees,CatBoost,k-nearest neighbors,random forest,gradient boosting,and decision tree—were trained to predict mechanical behavior.Cat Boost yielded the highest prediction accuracy with R^(2) scores of 0.95 for ultimate tensile strength(UTS)and 0.92 for yield strength(YS).Further validation using published datasets reaffirmed its reliability,demonstrating R^(2) values of 0.956(UTS)and 0.936(YS),MAE of 1%and 2.8%,and RMSE of 1%and 3.5%,respectively.Among these,the CatBoost model demonstrated the highest predictive accuracy,outperforming other ML techniques across multiple optimization metrics.
基金supported by the following foundations:“Stichting Oogfonds Nederland(No.2023-26)”the“Landelijke Stichting voor Blinden en Slechtzienden(No.2023-24)”that contributed through UitZicht,ZonMw grant(No.435005020)a grant of the Chinese Scholarship Council(No.201809110169)(to TGMFG,CPMR,and WY).
文摘Unwarranted death of neurons is a major cause of neurodegenerative diseases.Since mature neurons are postmitotic and do not replicate,their death usually constitutes an irreversible step in pathology.A logical strategy to prevent neurodegeneration would then be to save all neurons that are still alive,i.e.protecting the ones that are still healthy as well as trying to rescue the ones that are damaged and in the process of dying.Regarding the latter,recent experiments have indicated that the possibility of reversing the cell death process and rescuing dying cells is more significant than previously anticipated.In many situations,the elimination of the cell death trigger alone enables dying cells to spontaneously repair their damage,recover,and survive.In this review,we explore the factors,which determine the fate of neurons engaged in the cell death process.A deeper insight into cell death mechanisms and the intrinsic capacity of cells to recover could pave the way for novel therapeutic approaches to neurodegenerative diseases.
基金funded by the Department of Energy Office of Vehicle Technologies under the Automotive Lightweighting Materials Program。
文摘High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.
基金supported by National Natural Science Foundation of China(Grant No.52205344,51925401)Postdoctoral Research Foundation of China(Grant No.2023M732398)+1 种基金National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2023-1)Key Research and Development Program of Shandong Province(Grant No.2023CXPT066).
文摘This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.
文摘“遥远的共鸣”,是卡普马吉他全国巡演的主题,同时作为新的指弹专辑名称。主人公亦有两位——Casper Esmann、Eddie van der Meer。二人平日里相距甚远,Casper生活在丹麦,Eddie定居于墨西哥。可即便如此,他们还是走向了同一方舞台,并将各自的音乐融合成了一副声音,在纵横交错的情绪流转间交织为彼此的同类。
文摘国家大剧院制作歌剧《指环》之《女武神》即将登场NCPA’s Die Walküre to grace the stage继2024年8月国家大剧院制作《指环》系列的首部作品《莱茵的黄金》震撼亮相后,该系列第二部《女武神》将于4月29日、5月1日、5月3日登台国家大剧院歌剧节·2025。本轮演出将由对瓦格纳作品有着丰富诠释经验的国际知名指挥家皮塔里·因基宁执棒。瓦格纳的音乐是因基宁艺术生涯的重心,他曾在拜罗伊特音乐节上呈献瓦格纳的《指环》全剧,此次执棒《女武神》也将是因基宁继2008年之后再度登台国家大剧院,他将携手国家大剧院管弦乐团与一众国内外实力派歌唱家共同谱写这部情感澎湃的壮丽乐章。曾因执导德利布歌剧《拉克美》在国家大剧院舞台上大放异彩的重量级导演达维德·利维摩尔再度操刀,此次他将担任《女武神》的导演,并深度参与歌剧的舞美设计工作,率领主创团队运用更具创新性的多媒体舞台语汇,为观众呈献一个更加绚丽、充满奇幻色彩的“指环宇宙”。
文摘修辞学结构论是一种专门研究语篇描写的理论,以篇章结构为研究重点,致力于通过分析语篇结构阐述作者的交际意图在语篇中是如何实现的。通过观察修辞结构关系的类别与分布状况,能够了解语篇的核心思想、连贯特性以及写作特色等基础信息。本文将采用修辞结构理论的描述框架对Peter Bichsel的短篇小说Die Tochter的语篇结构进行描述和解释,思考修辞结构理论对于该小说的语篇结构分析能力。根据分析,修辞结构理论可以分析出结构段的中心思想,但是无法把握整篇小说的主旨;修辞结构较多且连接十分紧密,连贯性较强;作者多用背景关系和解释关系进行叙述,先交代背景,再塑造人物,风格细腻。Rhetorical Structure Theory (RST) is a comprehensive set of theories dedicated to describing natural discourse. It emphasizes the structure of texts and aims to elucidate how authors’ communicative intentions are realized through textual analysis. By examining the types and distribution of rhetorical structural relationships, one can gain insights into the central idea, coherence features, writing characteristics, and other fundamental aspects of a text. This paper employs the descriptive framework of Rhetorical Structure Theory to describe and explain the text structure of Peter Bichsel’s short story Die Tochter and reflects on the efficacy of RST in analyzing the textual structure of novels. The analysis reveals that RST can effectively dissect the central idea of individual structural paragraphs but struggles to encapsulate the overarching theme of the entire novel. Furthermore, the rhetorical structures are numerous and tightly interconnected, contributing to a strong sense of coherence. The author frequently utilizes background and explanation relationships in the narration, first establishing the context and then developing the characters, resulting in a nuanced and refined style.
基金funded by Department of Science and Technology of Sichuan Province,China(No.2022YFG0102)the China Postdoctoral Science Foundation(No.2023M733314).
文摘The microstructure and mechanical properties of the Ti-5Al-5Mo-5V-1Cr-1Fe(Ti-55511)alloy under different strains were investigated through the design of step-shaped die forging.The results indicate that continuous dynamic recrystallization(CDRX)and discontinuous dynamic recrystallization(DDRX)occur in the high strain region.The orientation of the grains produced by CDRX is random and does not weaken the fiber texture.<100>-oriented grains expand gradually with increasing strain,thereby enhancing the strength of{100}texture.Significant anisotropic mechanical properties are observed in the large strain region and analyzed through in-situ tensile experiments.When the loading direction is parallel to the longitudinal(L)direction,strain concentration is observed near the dynamically recrystallized(DRXed)grains and inside grains oriented along<100>,leading to crack initiation.Furthermore,the small angle between the loading direction and the c-axis hinders the activation of prismatic and basal slip,thereby enhancing the strength.When the loading direction is parallel to the short transverse(ST)direction,cracks are initiated not only within grains oriented along<100>,but also at the grain boundaries.Regarding impact toughness,the elongatedβgrains in the L direction enhance the resistance to crack propagation.
文摘The development and application of large Die⁃Casting Al Alloy(DCAA)parts and Thermo⁃Formed Steel Sheets(TFSS)in Body⁃in⁃White(BIW)have created higher demands for the joining technology of high⁃strength steel/Al dissimilar materials.As an emerging technology,Flush Self⁃Piercing Riveting(FSPR)is still in the experimental phase and undergoing small batch equipment verification.This paper focuses on the joining methods for DCAA and TFSS in BIW,investigating the joining mechanisms,technical features,and forming principles of FSPR for steel/Al dissimilar materials with two⁃layer or three⁃layer plate combinations.Considering the TL4225/C611/CR5 sheet combination as a subject,the forming mechanism of high⁃quality joints was studied,and a physical and mathematical model was established to depict the relationship between the filling amount of the arc⁃gap and die dimensions,as well as the extrusion amount.This model effectively illustrates the relationship between the filling amount of the flowing metal in the arc⁃gap and critical parameters,such as die dimensions and feeding amounts.By simplifying the process of selecting joining parameters,it significantly reduces both the time and experimental workload associated with parameter selection.This provides a technical foundation for the application of DAAA and TFSS parts in BIW,enabling the rapid choice of appropriate joining parameters to meet the requirements for obtaining high⁃quality joints.The model can be effectively utilized to investigate the relationships between key parameters,including arc⁃gap radius,plate thickness,rivet arc radius,nail head radius,groove width,and feeding amount,while keeping other parameters constant.This approach provides a theoretical foundation for the design of Friction Stir Processing(FSP)joints and aids in the selection of optimal parameters.
基金supported by the National Natural Science Foundation of China(Grant Nos.52064011 and 52274331)Guizhou Provincial Basic Research Program(Natural Science)(Nos.ZK[2021]258 and ZK[2022]Zhongdian 023)+1 种基金Guizhou Provincial Program on Commercialization of Scientific and Technological Achievements(No.[2022]089)Natural Science Research Project of Guizhou Provincial Department of Education(No.[2022]041).
文摘Larger-sized primary carbides lead to stress concentration during the application of H13 hot-work die steel,resulting in microcracks and fatigue failure.Rare earth was usually added to modify the carbides and inclusions.The existing literature is reviewed on the effect of rare earth on primary carbides in H13 steel.A comprehensive review on the effect of rare earth on the characteristics of primary carbides,i.e.,number,size,morphology,and thermal stability in H13 steel,was done.The precipitation mechanism and nucleation of primary carbides with rare earth were summarized.The position and form of rare earth in steel and their effects on alloying elements segregation were reviewed.The addition techniques of rare earth in H13 steel were compared,and the prospects for other uncommon rare earth and emerging technology were present.Based on the current references,it can be known that adding rare earth facilitated refined and dispersed primary carbides.The size of primary carbides would be reduced,and their morphology would be improved because the rare earth inclusions formed in H13 steel can act as nucleation cores forγ-Fe orδ-Fe,refining the dendritic structure.Besides,the number of primary carbides at grain boundaries would be significantly reduced.However,rare earth had little impact on thermal stability.The nucleation of primary carbides tended to be inhibited due to the modification of inclusions by rare earth which were likely to be nucleation cores for primary carbides.Rare earth had been reported to affect the mechanism and process of primary carbide precipitation.Additionally,the addition of rare earth can inhibit the segregation of alloying elements and carbon diffusion by calculation.Thus,laboratory experiments and theoretical calcu-lations need to be conducted to study the states and evolution of rare earth steels.
基金financially supported by the National Key Research and Development Program of China(2022YFB3404201)the Major Science and Technology Project of Changchun City,Jilin Province(Grant No.20210301024GX)。
文摘The effect of slow shot speed on externally solidified crystal(ESC),porosity and tensile property in a newly developed high-pressure die-cast Al-Si alloy was investigated by optical microscopy(OM),scanning electron microscopy(SEM)and laboratory computed tomography(CT).Results showed that the newly developed AlSi9MnMoV alloy exhibited improved mechanical properties when compared to the AlSi10MnMg alloy.The AlSi9MnMoV alloy,which was designed with trace multicomponent additions,displays a notable grain refining effect in comparison to the AlSi10MnMg alloy.Refining elements Ti,Zr,V,Nb,B promote heterogeneous nucleation and reduce the grain size of primaryα-Al.At a lower slow shot speed,the large ESCs are easier to form and gather,developing into the dendrite net and net-shrinkage.With an increase in slow shot speed,the size and number of ESCs and porosities significantly reduce.In addition,the distribution of ESCs is more dispersed and the net-shrinkage disappears.The tensile property is greatly improved by adopting a higher slow shot speed.The ultimate tensile strength is enhanced from 260.31 MPa to 290.31 MPa(increased by 11.52%),and the elongation is enhanced from 3.72%to 6.34%(increased by 70.52%).
