The pantograph-catenary arc has persistently posed a challenge,impeding the advancement of high-speed rail systems.As the velocity of high-speed trains continues to escalate and environmental conditions become increas...The pantograph-catenary arc has persistently posed a challenge,impeding the advancement of high-speed rail systems.As the velocity of high-speed trains continues to escalate and environmental conditions become increasingly complex,the phenomenon of pantograph-catenary arc drifting has intensified,thereby jeopardizing the safe operation of trains.To enhance the stability of the pantograph-catenary arc,this paper proposes a method to regulate arc using an AC transverse magnetic field(ATMF)and investigates the regulation law of ATMF on an arc in airflow environment.The results indicate that ATMF can effectively maintain arc stability,with the stability enhancing as the magnetic field frequency increases up to a threshold value.In an airflow environment,the stabilization effect is maximized at a frequency of 50 Hz,with arc voltage fluctuation at 4.65 V,accounting for only 5.47%of total arc voltage.It is also found that the arc temperature increases with the frequency of the magnetic field,reaching 4743 K at 10 Hz and 4976 K at 1000 Hz.In addition,the effects of sinusoidal,triangular and rectangular magnetic field excitation currents on the arc are investigated,and it is found that the arc shows the greatest stability in the triangular field,with a voltage fluctuation of 3.04 V.This study provides theoretical support for the application of ATMF regulation to enhance the stability of the pantograph-catenary arc.展开更多
Stiffened plates or shells are widely used in engineering structures as primary or secondary load-bearing components.How to design the layout and sizes of the stiffeners is of great significance for structural lightwe...Stiffened plates or shells are widely used in engineering structures as primary or secondary load-bearing components.How to design the layout and sizes of the stiffeners is of great significance for structural lightweight.In this work,a new topology optimization method for simultaneously optimizing the layout and cross-section topology of the stiffeners is developed to solve this issue.The stilfeners and base plates are modeled by the beam and shell elements,respectively,significantly reducing the computational cost.The Giavotto beam theory,instead of the widely employed Euler or Timoshenko beam theory,is applied to model the stiffeners for considering the warping deformation in evaluating the section stiffness of the beam.A multi-scale topology optimization model is established by simultaneously optimizing the layout of the beam and the topology of the cross-section.The design space is significantly expanded by optimizing these two types of design variables.Several numerical examples are applied to illustrate the validity and effectiveness of the proposed method.The results show that the proposed two-scale optimization approach can generate better designs than the single-scale method.展开更多
Triple-negative breast cancer(TNBC)is characterized by fast growth,high metastasis,high invasion,and a lack of therapeutic targets.Mitosis and metastasis of TNBC cells are two important biological behaviors in TNBC ma...Triple-negative breast cancer(TNBC)is characterized by fast growth,high metastasis,high invasion,and a lack of therapeutic targets.Mitosis and metastasis of TNBC cells are two important biological behaviors in TNBC malignant progression.It is well known that the long noncoding RNA AFAP1-AS1 plays a crucial role in various tumors,but whether AFAP1-AS1 is involved in the mitosis of TNBC cells remains unknown.In this study,we investigated the functional mechanism of AFAP1-AS1 in targeting Polo-like Kinase 1(PLK1)activation and participating in mitosis of TNBC cells.We detected the expression of AFAP1-AS1 in the TNBC patient cohort and primary cells by in situ hybridization(ISH),northern blot,fluorescent in situ hybridization(FISH)and cell nucleus/cytoplasm RNA fraction isolation.High AFAP1-AS1 expression was negatively correlated with overall survival(OS),disease-free survival(DFS),metastasis-free survival(MFS)and recurrence-free survival(RFS)in TNBC patients.We explored the function of AFAP1-AS1 by transwell,apoptosis,immunofluorescence(IF)and patient-derived xenograft(PDX)models in vitro and in vivo.We found that AFAP1-AS1 promoted TNBC primary cell survival by inhibiting mitotic catastrophe and increased TNBC primary cell growth,migration and invasion.Mechanistically,AFAP1-AS1 activated phosphorylation of the mitosis-associated kinase PLK1 protein.Elevated levels of AFAP1-AS1 in TNBC primary cells increased PLK1 pathway downstream gene expression,such as CDC25C,CDK1,BUB1 and TTK.More importantly,AFAP1-AS1 increased lung metastases in a mouse metastasis model.Taken together,AFAP1-AS1 functions as an oncogene that activates the PLK1 signaling pathway.AFAP1-AS1 could be used as a potential prognostic marker and therapeutic target for TNBC.展开更多
Additive manufacturing(AM)has made significant progress in recent years and has been successfully applied in various fields owing to its ability to manufacture complex geometries.This method efficiently expands the de...Additive manufacturing(AM)has made significant progress in recent years and has been successfully applied in various fields owing to its ability to manufacture complex geometries.This method efficiently expands the design space,allowing for the creation of products with better performance than ever before.With the emergence of new manufacturing technologies,new design methods are required to efficiently utilize the expanded design space.Therefore,topology optimization methods have attracted the attention of researchers because of their ability to generate new and optimized designs without requiring prior experience.The combination of AM and topology optimization has proven to be a powerful tool for structural innovation in design and manufacturing.However,it is important to note that AM does not eliminate all manufacturing restrictions but instead replaces them with a different set of design considerations that designers must consider for the successful implementation of these technologies.This has motivated research on topology optimization methods that incorporate manufacturable constraints for AM structures.In this paper,we present a survey of the latest studies in this research area,with a particular focus on developments in China.Additionally,we discuss the existing research gaps and future development trends.展开更多
Panax ginseng,a perennial herbaceous plant and a representative of the Panax genus,is renowned for its exceptional medicinal value and economic benefits,often referred to as the“King of Herbs.”With the increasingmar...Panax ginseng,a perennial herbaceous plant and a representative of the Panax genus,is renowned for its exceptional medicinal value and economic benefits,often referred to as the“King of Herbs.”With the increasingmarket demand and the limited availability of suitable cultivation land,the issue of continuous cropping obstacles for P.ginseng has become increasingly prominent,directly hindering the sustainable development of the ginseng industry.This article summarizes the concept and hazards of continuous cropping obstacles and,drawing on the latest research,provides an in-depth analysis of the causes and responsemechanisms.This work aims to establish a solid foundation for future research into the mechanisms of continuous cropping obstacles in P.ginseng.展开更多
Tripterygium wilfordii is a valuable medicinal plant rich in biologically active diterpenoids,but there are few studies on the origins of these diterpenoids in its secondary metabolism.Here,we identified three regions...Tripterygium wilfordii is a valuable medicinal plant rich in biologically active diterpenoids,but there are few studies on the origins of these diterpenoids in its secondary metabolism.Here,we identified three regions containing tandemly duplicated diterpene synthase genes on chromosomes(Chr) 17 and 21 of T. wilfordii and obtained 11 diterpene synthases with different functions.We farther revealed that these diterpene synthases underwent duplication and rearrangement at approximately 2.3-23.7 million years ago(MYA) by whole-genome triplication(WGT),transposon mediation,and tandem duplication,followed by functional divergence.We first demonstrated that four key amino acids in the sequences of TwCPS3,TwCPS5,and TwCPSS were altered during evolution,leading to their functional divergence and the formation of diterpene secondary metabolites.Then,we demonstrated that the functional divergence of three TwKSLs was driven by mutations in two key amino acids.Finally,we discovered the mechanisms of evolution and pseudogenization of miltiradiene synthases in T.wilfordii and elucidated that the new function in TwMS1/2 from the terpene synthase(TPS)-b subfamily was caused by progressive changes in multiple amino acids after the WGT event.Our results provide key evidence for the formation of diverse diterpenoids during the evolution of secondary metabolites in T.wilfordii.展开更多
基金supported by National Natural Science Foundation of China (Nos.52322704 and 52077182)。
文摘The pantograph-catenary arc has persistently posed a challenge,impeding the advancement of high-speed rail systems.As the velocity of high-speed trains continues to escalate and environmental conditions become increasingly complex,the phenomenon of pantograph-catenary arc drifting has intensified,thereby jeopardizing the safe operation of trains.To enhance the stability of the pantograph-catenary arc,this paper proposes a method to regulate arc using an AC transverse magnetic field(ATMF)and investigates the regulation law of ATMF on an arc in airflow environment.The results indicate that ATMF can effectively maintain arc stability,with the stability enhancing as the magnetic field frequency increases up to a threshold value.In an airflow environment,the stabilization effect is maximized at a frequency of 50 Hz,with arc voltage fluctuation at 4.65 V,accounting for only 5.47%of total arc voltage.It is also found that the arc temperature increases with the frequency of the magnetic field,reaching 4743 K at 10 Hz and 4976 K at 1000 Hz.In addition,the effects of sinusoidal,triangular and rectangular magnetic field excitation currents on the arc are investigated,and it is found that the arc shows the greatest stability in the triangular field,with a voltage fluctuation of 3.04 V.This study provides theoretical support for the application of ATMF regulation to enhance the stability of the pantograph-catenary arc.
基金The authors gratefully acknowledge the financial support to this work from the National Natural Science Foundation of China(Grants 11802164 and U1808215)Shandong Provincial Natural Science Foundation(Grant ZR2019BEE005)the project funded by China Postdoctoral Science Foundation.
文摘Stiffened plates or shells are widely used in engineering structures as primary or secondary load-bearing components.How to design the layout and sizes of the stiffeners is of great significance for structural lightweight.In this work,a new topology optimization method for simultaneously optimizing the layout and cross-section topology of the stiffeners is developed to solve this issue.The stilfeners and base plates are modeled by the beam and shell elements,respectively,significantly reducing the computational cost.The Giavotto beam theory,instead of the widely employed Euler or Timoshenko beam theory,is applied to model the stiffeners for considering the warping deformation in evaluating the section stiffness of the beam.A multi-scale topology optimization model is established by simultaneously optimizing the layout of the beam and the topology of the cross-section.The design space is significantly expanded by optimizing these two types of design variables.Several numerical examples are applied to illustrate the validity and effectiveness of the proposed method.The results show that the proposed two-scale optimization approach can generate better designs than the single-scale method.
基金supported by the Natural Science Foundation of China(Nos.82002782,82202657)the Guangdong Basic and Applied Basic Research Foundation(2022A1515012021,2020A1515110930).
文摘Triple-negative breast cancer(TNBC)is characterized by fast growth,high metastasis,high invasion,and a lack of therapeutic targets.Mitosis and metastasis of TNBC cells are two important biological behaviors in TNBC malignant progression.It is well known that the long noncoding RNA AFAP1-AS1 plays a crucial role in various tumors,but whether AFAP1-AS1 is involved in the mitosis of TNBC cells remains unknown.In this study,we investigated the functional mechanism of AFAP1-AS1 in targeting Polo-like Kinase 1(PLK1)activation and participating in mitosis of TNBC cells.We detected the expression of AFAP1-AS1 in the TNBC patient cohort and primary cells by in situ hybridization(ISH),northern blot,fluorescent in situ hybridization(FISH)and cell nucleus/cytoplasm RNA fraction isolation.High AFAP1-AS1 expression was negatively correlated with overall survival(OS),disease-free survival(DFS),metastasis-free survival(MFS)and recurrence-free survival(RFS)in TNBC patients.We explored the function of AFAP1-AS1 by transwell,apoptosis,immunofluorescence(IF)and patient-derived xenograft(PDX)models in vitro and in vivo.We found that AFAP1-AS1 promoted TNBC primary cell survival by inhibiting mitotic catastrophe and increased TNBC primary cell growth,migration and invasion.Mechanistically,AFAP1-AS1 activated phosphorylation of the mitosis-associated kinase PLK1 protein.Elevated levels of AFAP1-AS1 in TNBC primary cells increased PLK1 pathway downstream gene expression,such as CDC25C,CDK1,BUB1 and TTK.More importantly,AFAP1-AS1 increased lung metastases in a mouse metastasis model.Taken together,AFAP1-AS1 functions as an oncogene that activates the PLK1 signaling pathway.AFAP1-AS1 could be used as a potential prognostic marker and therapeutic target for TNBC.
基金supported by National Natural Science Foundation of China(Grant Nos.12272076,U2341232,11332004,and U1808215)the 111 Project of China(Grant No.B14013).
文摘Additive manufacturing(AM)has made significant progress in recent years and has been successfully applied in various fields owing to its ability to manufacture complex geometries.This method efficiently expands the design space,allowing for the creation of products with better performance than ever before.With the emergence of new manufacturing technologies,new design methods are required to efficiently utilize the expanded design space.Therefore,topology optimization methods have attracted the attention of researchers because of their ability to generate new and optimized designs without requiring prior experience.The combination of AM and topology optimization has proven to be a powerful tool for structural innovation in design and manufacturing.However,it is important to note that AM does not eliminate all manufacturing restrictions but instead replaces them with a different set of design considerations that designers must consider for the successful implementation of these technologies.This has motivated research on topology optimization methods that incorporate manufacturable constraints for AM structures.In this paper,we present a survey of the latest studies in this research area,with a particular focus on developments in China.Additionally,we discuss the existing research gaps and future development trends.
基金supported by the National Natural Science Foundation of China(Grant Nos.12202154,12272076,and 52188102)the China Postdoctoral Science Foundation(Grant No.2022M711249)the Natural Science Foundation of Hubei Province(Grant No.2020CFA028).
基金funded byNational Natural Science Foundation of China(82003902),Scientific and Technological Innovation Project of China Academy of Chinese Medical Sciences(CI2021B014)Fundamental Research Funds for Central Public Welfare Research Institutes(ZZXT202008/ZZ14-YQ-046)the National Key R&D Program of China(2023YFC3400585,2020YFA0908000).
文摘Panax ginseng,a perennial herbaceous plant and a representative of the Panax genus,is renowned for its exceptional medicinal value and economic benefits,often referred to as the“King of Herbs.”With the increasingmarket demand and the limited availability of suitable cultivation land,the issue of continuous cropping obstacles for P.ginseng has become increasingly prominent,directly hindering the sustainable development of the ginseng industry.This article summarizes the concept and hazards of continuous cropping obstacles and,drawing on the latest research,provides an in-depth analysis of the causes and responsemechanisms.This work aims to establish a solid foundation for future research into the mechanisms of continuous cropping obstacles in P.ginseng.
基金supported by the National Key R&D Program of China (No.2020YFA0908000)the Key Project at central government level: The ability establishment of sustainable use for valuable Chinese medicine resources (No.2060302-1806-03)Innovation Team and Talents Cultivation Program of National Administration of Traditional Chinese Medicine (ZYYCXTD-D202005)。
文摘Tripterygium wilfordii is a valuable medicinal plant rich in biologically active diterpenoids,but there are few studies on the origins of these diterpenoids in its secondary metabolism.Here,we identified three regions containing tandemly duplicated diterpene synthase genes on chromosomes(Chr) 17 and 21 of T. wilfordii and obtained 11 diterpene synthases with different functions.We farther revealed that these diterpene synthases underwent duplication and rearrangement at approximately 2.3-23.7 million years ago(MYA) by whole-genome triplication(WGT),transposon mediation,and tandem duplication,followed by functional divergence.We first demonstrated that four key amino acids in the sequences of TwCPS3,TwCPS5,and TwCPSS were altered during evolution,leading to their functional divergence and the formation of diterpene secondary metabolites.Then,we demonstrated that the functional divergence of three TwKSLs was driven by mutations in two key amino acids.Finally,we discovered the mechanisms of evolution and pseudogenization of miltiradiene synthases in T.wilfordii and elucidated that the new function in TwMS1/2 from the terpene synthase(TPS)-b subfamily was caused by progressive changes in multiple amino acids after the WGT event.Our results provide key evidence for the formation of diverse diterpenoids during the evolution of secondary metabolites in T.wilfordii.
