Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail ...Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and deterioration.Few researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry irregularities.However,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric shape.In this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to Shanghai.The vertical dynamic forces in the time and frequency domains were compared under different running speeds.These forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed model.Finally,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is found.The results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the literature.The ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.展开更多
Aflatoxin B1(AFB1)is a highly toxic mycotoxin,and rapid and sensitive detection of AFB1 is in demand for food safety and environmental analysis.Here we described a simple aptamer molecular beacon assay for rapid detec...Aflatoxin B1(AFB1)is a highly toxic mycotoxin,and rapid and sensitive detection of AFB1 is in demand for food safety and environmental analysis.Here we described a simple aptamer molecular beacon assay for rapid detection of aflatoxin B1(AFB1)by using an aptamer with a fluorescein(FAM)label at the 50 end and a fluorescence quencher(black hole quencher 1,BHQ1)at the 30 end.In the presence of AFB1,the aptamer probe bound with AFB1 and induced a hairpin structure,drawing FAM and BHQ1 into close proximity and leading to fluorescence quenching.This assay allowed for a detection limit of 3.9 nmol/L and a dynamic range from 3.9 nmol/L to 4 mmol/L.Specificity test showed other mycotoxins including ochratoxin A,ochratoxin B,fumonisin B1,fumonisin B2,and zearalenone had negligible influence on detection of AFB1.AFB1 spiked in diluted liquor wine,methanol,or corn flour samples was successfully detected by using this aptamer probe,and the assay showed potential for real sample analysis.展开更多
Exfoliation of bulk graphitic carbon nitride(g‐C3N4)into two‐dimensional(2D)nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g‐C3N4 nanosheets(CN)have larger spe...Exfoliation of bulk graphitic carbon nitride(g‐C3N4)into two‐dimensional(2D)nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g‐C3N4 nanosheets(CN)have larger specific surface areas and more reaction sites.In addition,poly‐o‐phenylenediamine(PoPD)can improve the electrical conductivity and photocatalytic activity of semiconductor materials.Here,the novel efficient composite PoPD/AgCl/g‐C3N4 nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach.The obtained photocatalysts have larger specific surface areas and could achieve better visible‐light response.However,silver chloride(AgCl)is susceptible to agglomeration and photocorrosion.The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density,which is three times that of CN.Obviously enhanced photocatalytic activities of PoPD/AgCl/g‐C3N4 are revealed through the photodegradation of tetracycline.The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly.Furthermore,.O2^-and h+are the main active species,which are confirmed through a trapping experiment and ESR spin‐trap technique.Therefore,the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst,in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles.This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.展开更多
It is extremely important for photocatalysts to exhibit intelligent responsiveness to their environment. Herein, a poly N-isopropyl acrylamide(PNIPAM)-modified Ag/Ag3PO4-20/CN hybrid material with excellent convertibl...It is extremely important for photocatalysts to exhibit intelligent responsiveness to their environment. Herein, a poly N-isopropyl acrylamide(PNIPAM)-modified Ag/Ag3PO4-20/CN hybrid material with excellent convertible photocatalytic activity is prepared. PNIPAM has good hydrophilicity below the lower critical solution temperature(LCST);this increases the capacity of the photocatalyst for adsorbing tetracycline(TC) molecules. In addition, the PNIPAM-modified Ag/Ag3PO4-20/CN can prevent the loss of Ag3PO4. The dispersity is improved by loading g-C3N4 nanosheets(CN) for enhancing the efficiency of photocatalytic activity. Furthermore, a Z-scheme heterostructure is formed between CN and Ag3PO4, accelerating the separation efficiency of the holes and electrons. Ag nanoparticles can be used as electron-shuttle mediators, and electrons receiving more energy are transferred via the localized surface plasmon resonance(LSPR) effect. Furthermore, the PNIPAM@Ag/Ag3PO4-20/CN photocatalyst exhibits an excellent degradation rate for the degradation of TC when the temperature is lower than the LCST. The photoluminescence spectra and photocurrent curves prove that the carrier-separation efficiency of PNIPAM@Ag/Ag3PO4-20/CN is higher than those of Ag/Ag3PO4/CN and CN. The main active species of ·O2-and h+ are detected to reveal the plausible mechanism of the PNIPAM@Ag/Ag3PO4-20/CN hybrid material system. This work provides a way to develop intelligent materials for switchable photocatalytic applications.展开更多
To consider the anisotropic damage in fatigue, an improved boom-panel model is presented to simulate a representative volume element (RVE) in the framework of continuum damage mechanics. The anisotropic damage state o...To consider the anisotropic damage in fatigue, an improved boom-panel model is presented to simulate a representative volume element (RVE) in the framework of continuum damage mechanics. The anisotropic damage state of the RVE is described by the continuity extents of booms and panels, whose damage evolutions are assumed to be isotropic. The numerical implementation is proposed on the basis of damage mechanics and the finite element method. Finally, the approach is applied to the fatigue life prediction of 2A12-T4 aluminium alloy specimen under cyclic loading of tension-torsion. The results indicate a good agreement with the experimental data.展开更多
Medicinal plants are renowned for their abundant production of secondary metabolites,which exhibit notable pharmacological activities and great potential for drug development.The biosynthesis of secondary metabolites ...Medicinal plants are renowned for their abundant production of secondary metabolites,which exhibit notable pharmacological activities and great potential for drug development.The biosynthesis of secondary metabolites is highly intricate and influenced by various intrinsic and extrinsic factors,resulting in substantial species diversity and content variation.Consequently,precise regulation of secondary metabolite synthesis is of utmost importance.In recent years,genome sequencing has emerged as a valuable tool for investigating the synthesis and regulation of secondary metabolites in medicinal plants,facilitated by the widespread use of high-throughput sequencing technologies.This review highlights the latest advancements in genome sequencing within this field and presents several strategies for studying secondary metabolites.Specifically,the article elucidates how genome sequencing can unravel the pathways for secondary metabolite synthesis in medicinal plants,offering insights into the functions and regulatory mechanisms of participating enzymes.Comparative analyses of plant genomes allow identification of shared pathways of metabolite synthesis among species,thereby providing novel avenues for obtaining cost-effective biosynthetic intermediates.By examining individual genomic variations,genes or gene clusters associated with the synthesis of specific compounds can be discovered,indicating potential targets and directions for drug development and the exploration of alternative compound sources.Moreover,the advent of gene-editing technology has enabled the precise modifications of medicinal plant genomes.Optimization of specific secondary metabolite synthesis pathways becomes thus feasible,enabling the precise editing of target genes to regulate secondary metabolite production within cells.These findings serve as valuable references and lessons for future drug development endeavors,conservation of rare resources,and the exploration of new resources.展开更多
This study examines the effects of macroscopic bending and microscopic contact loading in inhomogeneous materials using a semi-analytical model based on Eshelby’s equivalent inclusion method.The model accounts for be...This study examines the effects of macroscopic bending and microscopic contact loading in inhomogeneous materials using a semi-analytical model based on Eshelby’s equivalent inclusion method.The model accounts for bending effects through the beam theory,with bending stress included in the Eshelby’s equivalent inclusion equations.The macroscopic displacement resulting from bending effects is incorporated into the microscopic contact solver,and the final displacement is determined using the conjugate gradient method in an iterative solution.Computational efficiency can be improved by incorporating the discrete convolution and fast Fourier transform.The core scheme is validated using the finite element method,yielding accurate and efficient results for bending-contact problems in inhomogeneous materials.Simulations reveal the interplay between bending,contact loading,and inhomogeneity,as stress around the inhomogeneity alters and the stress concentration area expands under increasing bending moments.Conversely,low-magnitude negative bending moments reduce both contact pressure and stress around the inhomogeneity.The position where inhomogeneities are least affected shifts from the neutral surface depending on the coupling effect.The model provides a valuable bridge for connecting the macroscopic bending effect and microscale contact-inhomogeneity problems by visualizing stress fields and assessing pressure distributions.展开更多
For a homotopy class[u]of maps between a closed Riemannian manifold M and a general manifold N,we want to find a Dirac-harmonic map with the map component in the given homotopy class.Most known results require the ind...For a homotopy class[u]of maps between a closed Riemannian manifold M and a general manifold N,we want to find a Dirac-harmonic map with the map component in the given homotopy class.Most known results require the index to be nontrivial.When the index is trivial,the few known results are all constructive and produce uncoupled solutions.In this paper,we define a new quantity.As a byproduct of proving the homotopy invariance of this new quantity,we find a new simple proof for the fact that all the Dirac-harmonic spheres in surfaces are uncoupled.More importantly,by using the homotopy invariance of this new quantity,we prove the existence of Dirac-harmonic maps from manifolds in the trivial index case.In particular,when the domain is a closed Riemann surface,we prove the short-time existence of theα-Dirac-harmonic map flow in the trivial index case.Together with the density of the minimal kernel,we get an existence result for Dirac-harmonic maps from closed Riemann surfaces to K?hler manifolds,which extends the previous result of the first and third authors.This establishes a general existence theory for Dirac-harmonic maps in the context of the trivial index.展开更多
Protein arginine methyltransferase 5(PRMT5)acts as an oncogene in liver cancer,yet its roles and in-depth molecular mechanisms within the liver cancer immune microenvironment remain mostly undefined.Here,we demonstrat...Protein arginine methyltransferase 5(PRMT5)acts as an oncogene in liver cancer,yet its roles and in-depth molecular mechanisms within the liver cancer immune microenvironment remain mostly undefined.Here,we demonstrated that disruption of tumor-intrinsic PRMT5 enhances CD8^(+)T-cell-mediated antitumor immunity both in vivo and in vitro.Further experiments verified that this effect is achieved through downregulation of the inhibitory immune checkpoint molecule,fibrinogen-like protein 1(FGL1).Mechanistically,PRMT5 catalyzed symmetric dimethylation of transcription factor 12(TCF12)at arginine 554(R554),prompting the binding of TCF12 to FGL1 promoter region,which transcriptionally activated FGL1 in tumor cells.Methylation deficiency at TCF12-R554 residue downregulated FGL1 expression,which promoted CD8^(+)T-cell-mediated antitumor immunity.Notably,combining the PRMT5 methyltransferase inhibitor GSK591 with PD-L1 blockade efficiently inhibited liver cancer growth and improved overall survival in mice.Collectively,our findings reveal the immunosuppressive role and mechanism of PRMT5 in liver cancer and highlight that targeting PRMT5 could boost checkpoint immunotherapy efficacy.展开更多
This work used high velocity oxygen fuel spraying technology to prepare three types of ceramic-based self-lubricating sealing coating on C/SiC substrates,with Yttria-stabilized zirconia as the matrix and different mas...This work used high velocity oxygen fuel spraying technology to prepare three types of ceramic-based self-lubricating sealing coating on C/SiC substrates,with Yttria-stabilized zirconia as the matrix and different mass fractions of Mo and Ag as lubricating phases.The compositions are S1(50%YSZ40%CaF_(2)10%Mo),S2(50%YSZ40%CaF_(2)10%Ag)and S3(40%YSZ30%CaF_(2)10%Mo10%Ag10%SiO_(2)).The friction coefficient and wear rate of the coating were examined at room temperature(RT),400℃and 800℃.The effects of different lubricating phases on the tribological properties of the coating were compared.The wear mechanism of the coating under different temperature environments will be revealed by clarifying the evolution law of the microstructure of the coating.The results show that the addition of Ag can improve the lubricating ability of the coating.Ag element forms a continuous and smooth tribo-layer on the sliding surface to reduce the friction coefficient of the coating.In addition,the lubricating effect of Ag element is more significant at medium and low temperatures.At 800℃,the S3 coating with both Ag and Mo exhibited excellent tribological properties.The wear mechanism of the coating is that it starts with adhesive wear and gradually transitions to abrasive wear as friction continues.This work provides theoretical support and experimental evidence for the construction of ceramic-based self-lubricating sealing coating with a wide temperature range.展开更多
Ni-based superalloys play a critical role in the aerospace industry due to their exceptional mechanical properties and oxidation resistance.However,the conventional development of new superalloys is often constrained ...Ni-based superalloys play a critical role in the aerospace industry due to their exceptional mechanical properties and oxidation resistance.However,the conventional development of new superalloys is often constrained by lengthy experimental cycles and high costs.To address these challenges,machine learning has emerged as an effective strategy for accelerating alloy design by efficiently exploring composition-property relationship,optimizing processing parameters,and enhancing predictive accuracy.This review summarizes recent progress in applying machine learning to composition optimization and mechanical property prediction of Ni-based superalloys,emphasizing the integration of theoretical modeling and experimental validation.The importance of feature engineering,including data collection,preprocessing,feature construction,and dimensionality reduction,was first highlighted.Subsequently,the machine learning approaches for novel alloy design and prediction of key properties including fatigue resistance,creep resistance,and oxidation resistance were discussed.Through data-driven approaches,machine learning not only enhances predictive capabilities but also uncovers complex composition-property relationship,which accelerates the development of next-generation Ni-based superalloys.We anticipate that the continued advancements in this field will drive more efficient and cost-effective alloy design,ultimately accelerating the transition from computational predictions to experimental realizations.展开更多
In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary condition.The SBM is a strong-for...In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary condition.The SBM is a strong-form boundary discretization collocation technique and is mathematically simple,easy-to-program,and free of mesh.The crucial step in the implementation of the SBM is to determine the OIFs which isolate the singularities of the fundamental solutions.Traditionally,the inverse interpolation technique(IIT)is adopted to calculate the OIFs on Dirichlet boundary,which is time consuming for large-scale simulation.In recent years,the new methodology has been developed to efficiently calculate the OIFs on Neumann boundary,but the Dirichlet problem remains an open issue.This study employs the subtracting and adding-back technique based on the integration of the fundamental solution over the whole boundary to develop a new formulation of the OIFs on 3D Dirichlet boundary.Several problems with varied domain shapes and boundary conditions are carried out to validate the effectiveness and feasibility of the proposed scheme in comparison with the SBM based on inverse interpolation technique,the method of fundamental solutions,and the boundary element method.展开更多
Erysipelothrix rhusiopathiae is a facultative anaerobic,nonmotile,nonspore-forming,gram-positive bacillus.It is a zoonotic pathogen that rarely infects humans but causes swine erysipelas.The disease caused by E.rhusio...Erysipelothrix rhusiopathiae is a facultative anaerobic,nonmotile,nonspore-forming,gram-positive bacillus.It is a zoonotic pathogen that rarely infects humans but causes swine erysipelas.The disease caused by E.rhusiopathiae canmanifest in the following threemain forms:erysipeloid,diffuse cutaneous infections,and bacteremia with or without endocarditis.In this article,we present the case study of a healthy Chinese man who developed erysipeloid and an E.rhusiopathiae bloodstream infection after being stabbed by a crab.Additionally,we conducted a thorough review of the available literature on E.rhusiopathiae bacteremia within the past two decades and provided a summary of the key findings.Early diagnosis and proper treatment are crucial in mitigating recurrence risk and avoiding sepsis.Understanding the risk factors for death from E.rhusiopathiae bacteremia is essential,and appropriate personal protective equipment should be used to prevent occupational exposure to this bacterium.展开更多
Let(Σ,g)be a compact Riemann surface with smooth boundary■Σ,Δ_(g) be the Laplace-Beltrami operator,and h be a positive smooth function.Using a min-max scheme introduced by Djadli and Malchiodi(2008)and Djadli(2008...Let(Σ,g)be a compact Riemann surface with smooth boundary■Σ,Δ_(g) be the Laplace-Beltrami operator,and h be a positive smooth function.Using a min-max scheme introduced by Djadli and Malchiodi(2008)and Djadli(2008),we prove that ifΣis non-contractible,then for anyρ∈(8kπ,8(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫∑he^(u)dv_(g)in∑,u=0 on■∑has a solution.This generalizes earlier existence results of Ding et al.(Ann Inst H PoincaréAnal Non Linéaire,1999)and Chen and Lin(2003)in the Euclidean domain.Also we consider the corresponding Neumann boundary value problem.If h is a positive smooth function,then for anyρ∈(4kπ,4(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫_(∑)he^(u)dv_(g)-1/|∑|in∑,■u/■v=0 on■∑has a solution,where v denotes the unit normal outward vector on ■Σ.Note that in this case we do not require the surface to be non-contractible.展开更多
基金supported by Natural Science Foundation of China(52178441)the Scientific Research Projects of the China Academy of Railway Sciences Co.,Ltd.(Grant No.2022YJ043).
文摘Rail weld irregularities are one of the primary excitation sources for vehicle-track interaction dynamics in modern high-speed railways.They can cause significant wheel-rail dynamic interactions,leading to wheel-rail noise,component damage,and deterioration.Few researchers have employed the vehicle-track interaction dynamic model to study the dynamic interactions between wheel and rail induced by rail weld geometry irregularities.However,the cosine wave model used to simulate rail weld irregularities mainly focuses on the maximum value and neglects the geometric shape.In this study,novel theoretical models were developed for three categories of rail weld irregularities,based on measurements of the high-speed railway from Beijing to Shanghai.The vertical dynamic forces in the time and frequency domains were compared under different running speeds.These forces generated by the rail weld irregularities that were measured and modeled,respectively,were compared to validate the accuracy of the proposed model.Finally,based on the numerical study,the impact force due to rail weld irrregularity is modeled using an Artificial Neural Network(ANN),and the optimum combination of parameters for this model is found.The results showed that the proposed model provided a more accurate wheel/rail dynamic evaluation caused by rail weld irregularities than that established in the literature.The ANN model used in this paper can effectively predict the impact force due to rail weld irrregularity while reducing the computation time.
基金financial support from the National Natural Science Foundation of China(Nos.21575153,21435008,21874146)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB14030200)the Key Research Program of the Chinese Academy of Sciences(No.KFZD-SW-203)
文摘Aflatoxin B1(AFB1)is a highly toxic mycotoxin,and rapid and sensitive detection of AFB1 is in demand for food safety and environmental analysis.Here we described a simple aptamer molecular beacon assay for rapid detection of aflatoxin B1(AFB1)by using an aptamer with a fluorescein(FAM)label at the 50 end and a fluorescence quencher(black hole quencher 1,BHQ1)at the 30 end.In the presence of AFB1,the aptamer probe bound with AFB1 and induced a hairpin structure,drawing FAM and BHQ1 into close proximity and leading to fluorescence quenching.This assay allowed for a detection limit of 3.9 nmol/L and a dynamic range from 3.9 nmol/L to 4 mmol/L.Specificity test showed other mycotoxins including ochratoxin A,ochratoxin B,fumonisin B1,fumonisin B2,and zearalenone had negligible influence on detection of AFB1.AFB1 spiked in diluted liquor wine,methanol,or corn flour samples was successfully detected by using this aptamer probe,and the assay showed potential for real sample analysis.
基金supported by the National Natural Science Foundation of China(21576125,21776117)the China Postdoctoral Science Foundation(2017M611716,2017M611734)+1 种基金the Six talent peaks project of Jiangsu Province(XCL-014)the Zhenjiang Science&Technology Program(SH2016012)~~
文摘Exfoliation of bulk graphitic carbon nitride(g‐C3N4)into two‐dimensional(2D)nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g‐C3N4 nanosheets(CN)have larger specific surface areas and more reaction sites.In addition,poly‐o‐phenylenediamine(PoPD)can improve the electrical conductivity and photocatalytic activity of semiconductor materials.Here,the novel efficient composite PoPD/AgCl/g‐C3N4 nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach.The obtained photocatalysts have larger specific surface areas and could achieve better visible‐light response.However,silver chloride(AgCl)is susceptible to agglomeration and photocorrosion.The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density,which is three times that of CN.Obviously enhanced photocatalytic activities of PoPD/AgCl/g‐C3N4 are revealed through the photodegradation of tetracycline.The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly.Furthermore,.O2^-and h+are the main active species,which are confirmed through a trapping experiment and ESR spin‐trap technique.Therefore,the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst,in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles.This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.
文摘It is extremely important for photocatalysts to exhibit intelligent responsiveness to their environment. Herein, a poly N-isopropyl acrylamide(PNIPAM)-modified Ag/Ag3PO4-20/CN hybrid material with excellent convertible photocatalytic activity is prepared. PNIPAM has good hydrophilicity below the lower critical solution temperature(LCST);this increases the capacity of the photocatalyst for adsorbing tetracycline(TC) molecules. In addition, the PNIPAM-modified Ag/Ag3PO4-20/CN can prevent the loss of Ag3PO4. The dispersity is improved by loading g-C3N4 nanosheets(CN) for enhancing the efficiency of photocatalytic activity. Furthermore, a Z-scheme heterostructure is formed between CN and Ag3PO4, accelerating the separation efficiency of the holes and electrons. Ag nanoparticles can be used as electron-shuttle mediators, and electrons receiving more energy are transferred via the localized surface plasmon resonance(LSPR) effect. Furthermore, the PNIPAM@Ag/Ag3PO4-20/CN photocatalyst exhibits an excellent degradation rate for the degradation of TC when the temperature is lower than the LCST. The photoluminescence spectra and photocurrent curves prove that the carrier-separation efficiency of PNIPAM@Ag/Ag3PO4-20/CN is higher than those of Ag/Ag3PO4/CN and CN. The main active species of ·O2-and h+ are detected to reveal the plausible mechanism of the PNIPAM@Ag/Ag3PO4-20/CN hybrid material system. This work provides a way to develop intelligent materials for switchable photocatalytic applications.
基金Project supported by the National Natural Science Foundation of China(No.11102008)
文摘To consider the anisotropic damage in fatigue, an improved boom-panel model is presented to simulate a representative volume element (RVE) in the framework of continuum damage mechanics. The anisotropic damage state of the RVE is described by the continuity extents of booms and panels, whose damage evolutions are assumed to be isotropic. The numerical implementation is proposed on the basis of damage mechanics and the finite element method. Finally, the approach is applied to the fatigue life prediction of 2A12-T4 aluminium alloy specimen under cyclic loading of tension-torsion. The results indicate a good agreement with the experimental data.
基金funded by the National Natural Science Foundation of China,grant number 81603221.
文摘Medicinal plants are renowned for their abundant production of secondary metabolites,which exhibit notable pharmacological activities and great potential for drug development.The biosynthesis of secondary metabolites is highly intricate and influenced by various intrinsic and extrinsic factors,resulting in substantial species diversity and content variation.Consequently,precise regulation of secondary metabolite synthesis is of utmost importance.In recent years,genome sequencing has emerged as a valuable tool for investigating the synthesis and regulation of secondary metabolites in medicinal plants,facilitated by the widespread use of high-throughput sequencing technologies.This review highlights the latest advancements in genome sequencing within this field and presents several strategies for studying secondary metabolites.Specifically,the article elucidates how genome sequencing can unravel the pathways for secondary metabolite synthesis in medicinal plants,offering insights into the functions and regulatory mechanisms of participating enzymes.Comparative analyses of plant genomes allow identification of shared pathways of metabolite synthesis among species,thereby providing novel avenues for obtaining cost-effective biosynthetic intermediates.By examining individual genomic variations,genes or gene clusters associated with the synthesis of specific compounds can be discovered,indicating potential targets and directions for drug development and the exploration of alternative compound sources.Moreover,the advent of gene-editing technology has enabled the precise modifications of medicinal plant genomes.Optimization of specific secondary metabolite synthesis pathways becomes thus feasible,enabling the precise editing of target genes to regulate secondary metabolite production within cells.These findings serve as valuable references and lessons for future drug development endeavors,conservation of rare resources,and the exploration of new resources.
基金support from the National Science and Technology Major Project(no.J2019-VII-0017-0159)the National Natural Science Foundation of China(no.52205048)+1 种基金support from the National Natural Science Foundation of China(no.52205192)Jinran Li would like to thank the China Scholarship Council(CSC)for its financial support(file no.201906290129)during his studies at Northwestern University as a visiting student.
文摘This study examines the effects of macroscopic bending and microscopic contact loading in inhomogeneous materials using a semi-analytical model based on Eshelby’s equivalent inclusion method.The model accounts for bending effects through the beam theory,with bending stress included in the Eshelby’s equivalent inclusion equations.The macroscopic displacement resulting from bending effects is incorporated into the microscopic contact solver,and the final displacement is determined using the conjugate gradient method in an iterative solution.Computational efficiency can be improved by incorporating the discrete convolution and fast Fourier transform.The core scheme is validated using the finite element method,yielding accurate and efficient results for bending-contact problems in inhomogeneous materials.Simulations reveal the interplay between bending,contact loading,and inhomogeneity,as stress around the inhomogeneity alters and the stress concentration area expands under increasing bending moments.Conversely,low-magnitude negative bending moments reduce both contact pressure and stress around the inhomogeneity.The position where inhomogeneities are least affected shifts from the neutral surface depending on the coupling effect.The model provides a valuable bridge for connecting the macroscopic bending effect and microscale contact-inhomogeneity problems by visualizing stress fields and assessing pressure distributions.
基金supported by National Natural Science Foundation of China(Grant No.12201440)the Fundamental Research Funds for the Central Universities。
文摘For a homotopy class[u]of maps between a closed Riemannian manifold M and a general manifold N,we want to find a Dirac-harmonic map with the map component in the given homotopy class.Most known results require the index to be nontrivial.When the index is trivial,the few known results are all constructive and produce uncoupled solutions.In this paper,we define a new quantity.As a byproduct of proving the homotopy invariance of this new quantity,we find a new simple proof for the fact that all the Dirac-harmonic spheres in surfaces are uncoupled.More importantly,by using the homotopy invariance of this new quantity,we prove the existence of Dirac-harmonic maps from manifolds in the trivial index case.In particular,when the domain is a closed Riemann surface,we prove the short-time existence of theα-Dirac-harmonic map flow in the trivial index case.Together with the density of the minimal kernel,we get an existence result for Dirac-harmonic maps from closed Riemann surfaces to K?hler manifolds,which extends the previous result of the first and third authors.This establishes a general existence theory for Dirac-harmonic maps in the context of the trivial index.
基金supported by the National Natural Science Foundation of China(Nos.82372818 to Xiaodong Zhang,82103066 to Guang Yang,82302887 to Hongfeng Yuan,82303210 to Yufei Wang)The China Postdoctoral Science Foundation(No.2022M712389 to Hongfeng Yuan,No.2023M732624 to Yufei Wang,No.2023M742621 to Lina Zhao)+1 种基金Tianjin Key Medical Discipline(Specialty)Construction Project(TJYXZDXK-009A to W.Lu,China)“14th Five-Year Plan”Tumor Prevention and Treatment Research Project of Tianjin Medical University Cancer Institute and Hospital(No.YZ-03,China).
文摘Protein arginine methyltransferase 5(PRMT5)acts as an oncogene in liver cancer,yet its roles and in-depth molecular mechanisms within the liver cancer immune microenvironment remain mostly undefined.Here,we demonstrated that disruption of tumor-intrinsic PRMT5 enhances CD8^(+)T-cell-mediated antitumor immunity both in vivo and in vitro.Further experiments verified that this effect is achieved through downregulation of the inhibitory immune checkpoint molecule,fibrinogen-like protein 1(FGL1).Mechanistically,PRMT5 catalyzed symmetric dimethylation of transcription factor 12(TCF12)at arginine 554(R554),prompting the binding of TCF12 to FGL1 promoter region,which transcriptionally activated FGL1 in tumor cells.Methylation deficiency at TCF12-R554 residue downregulated FGL1 expression,which promoted CD8^(+)T-cell-mediated antitumor immunity.Notably,combining the PRMT5 methyltransferase inhibitor GSK591 with PD-L1 blockade efficiently inhibited liver cancer growth and improved overall survival in mice.Collectively,our findings reveal the immunosuppressive role and mechanism of PRMT5 in liver cancer and highlight that targeting PRMT5 could boost checkpoint immunotherapy efficacy.
基金supported by the National Natural Science Foundation of China(No.52105211)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(Grant No.2023-TS-04)the Research Fund of Pre-research Projects(No.0730-2411080386).
文摘This work used high velocity oxygen fuel spraying technology to prepare three types of ceramic-based self-lubricating sealing coating on C/SiC substrates,with Yttria-stabilized zirconia as the matrix and different mass fractions of Mo and Ag as lubricating phases.The compositions are S1(50%YSZ40%CaF_(2)10%Mo),S2(50%YSZ40%CaF_(2)10%Ag)and S3(40%YSZ30%CaF_(2)10%Mo10%Ag10%SiO_(2)).The friction coefficient and wear rate of the coating were examined at room temperature(RT),400℃and 800℃.The effects of different lubricating phases on the tribological properties of the coating were compared.The wear mechanism of the coating under different temperature environments will be revealed by clarifying the evolution law of the microstructure of the coating.The results show that the addition of Ag can improve the lubricating ability of the coating.Ag element forms a continuous and smooth tribo-layer on the sliding surface to reduce the friction coefficient of the coating.In addition,the lubricating effect of Ag element is more significant at medium and low temperatures.At 800℃,the S3 coating with both Ag and Mo exhibited excellent tribological properties.The wear mechanism of the coating is that it starts with adhesive wear and gradually transitions to abrasive wear as friction continues.This work provides theoretical support and experimental evidence for the construction of ceramic-based self-lubricating sealing coating with a wide temperature range.
基金financially supported by the National Natural Science Foundation of China(Nos.52201203 and 52471004)the Fundamental Research Funds for the Central Universities(No.N2423030)the Science and Technology Project of Hebei Education Department(No.QN2023155).
文摘Ni-based superalloys play a critical role in the aerospace industry due to their exceptional mechanical properties and oxidation resistance.However,the conventional development of new superalloys is often constrained by lengthy experimental cycles and high costs.To address these challenges,machine learning has emerged as an effective strategy for accelerating alloy design by efficiently exploring composition-property relationship,optimizing processing parameters,and enhancing predictive accuracy.This review summarizes recent progress in applying machine learning to composition optimization and mechanical property prediction of Ni-based superalloys,emphasizing the integration of theoretical modeling and experimental validation.The importance of feature engineering,including data collection,preprocessing,feature construction,and dimensionality reduction,was first highlighted.Subsequently,the machine learning approaches for novel alloy design and prediction of key properties including fatigue resistance,creep resistance,and oxidation resistance were discussed.Through data-driven approaches,machine learning not only enhances predictive capabilities but also uncovers complex composition-property relationship,which accelerates the development of next-generation Ni-based superalloys.We anticipate that the continued advancements in this field will drive more efficient and cost-effective alloy design,ultimately accelerating the transition from computational predictions to experimental realizations.
基金The work described in this paper was supported by the National Science Funds for Distinguished Young Scholars of China(No.11125208)NSFC Funds(Nos.11302069,11372097,11602114 and 11662003)the 111 project under Grant No.B12032.
文摘In this paper,a new formulation is proposed to evaluate the origin intensity factors(OIFs)in the singular boundary method(SBM)for solving 3D potential problems with Dirichlet boundary condition.The SBM is a strong-form boundary discretization collocation technique and is mathematically simple,easy-to-program,and free of mesh.The crucial step in the implementation of the SBM is to determine the OIFs which isolate the singularities of the fundamental solutions.Traditionally,the inverse interpolation technique(IIT)is adopted to calculate the OIFs on Dirichlet boundary,which is time consuming for large-scale simulation.In recent years,the new methodology has been developed to efficiently calculate the OIFs on Neumann boundary,but the Dirichlet problem remains an open issue.This study employs the subtracting and adding-back technique based on the integration of the fundamental solution over the whole boundary to develop a new formulation of the OIFs on 3D Dirichlet boundary.Several problems with varied domain shapes and boundary conditions are carried out to validate the effectiveness and feasibility of the proposed scheme in comparison with the SBM based on inverse interpolation technique,the method of fundamental solutions,and the boundary element method.
基金supported by Sanming Project of Medicine in Shenzhen(SZSM201911014)and the High Level-Hospital Program,Health Commission of Guangdong Province,China.The funders had no role in study design,data collection or analysis,decision to publish or preparation of the manuscript.
文摘Erysipelothrix rhusiopathiae is a facultative anaerobic,nonmotile,nonspore-forming,gram-positive bacillus.It is a zoonotic pathogen that rarely infects humans but causes swine erysipelas.The disease caused by E.rhusiopathiae canmanifest in the following threemain forms:erysipeloid,diffuse cutaneous infections,and bacteremia with or without endocarditis.In this article,we present the case study of a healthy Chinese man who developed erysipeloid and an E.rhusiopathiae bloodstream infection after being stabbed by a crab.Additionally,we conducted a thorough review of the available literature on E.rhusiopathiae bacteremia within the past two decades and provided a summary of the key findings.Early diagnosis and proper treatment are crucial in mitigating recurrence risk and avoiding sepsis.Understanding the risk factors for death from E.rhusiopathiae bacteremia is essential,and appropriate personal protective equipment should be used to prevent occupational exposure to this bacterium.
基金supported by National Natural Science Foundation of China (Grant No.11721101)the National Key Research and Development Project (Grant No.SQ2020YFA070080)+1 种基金supported by Hubei Provincial Natural Science Foundation of China (Grant No.2021CFB400)National Natural Science Foundation of China (Grant No.11971358)。
文摘Let(Σ,g)be a compact Riemann surface with smooth boundary■Σ,Δ_(g) be the Laplace-Beltrami operator,and h be a positive smooth function.Using a min-max scheme introduced by Djadli and Malchiodi(2008)and Djadli(2008),we prove that ifΣis non-contractible,then for anyρ∈(8kπ,8(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫∑he^(u)dv_(g)in∑,u=0 on■∑has a solution.This generalizes earlier existence results of Ding et al.(Ann Inst H PoincaréAnal Non Linéaire,1999)and Chen and Lin(2003)in the Euclidean domain.Also we consider the corresponding Neumann boundary value problem.If h is a positive smooth function,then for anyρ∈(4kπ,4(k+1)π)with k∈N^(*),the mean field equation{Δgu=ρhe^(u)/∫_(∑)he^(u)dv_(g)-1/|∑|in∑,■u/■v=0 on■∑has a solution,where v denotes the unit normal outward vector on ■Σ.Note that in this case we do not require the surface to be non-contractible.
