Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption applications.In this study,a novel modified re-entrant hybrid auxetic me...Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption applications.In this study,a novel modified re-entrant hybrid auxetic metamaterial inspired by Islamic motif art is designed by integrating four-pointed double re-entrant motifs with symmetric semi-hexagonal unit cells to achieve a high energy absorption capacity(EAC).Theoretical analyses and numerical simulations are performed to examine the dynamic crushing behavior of the four-pointed double re-entrant combined structure(FDRCS).The developed finite element models(FEMs)are validated by the experiments under quasi-static compression.The deformation mode and stress-strain curves are further studied under low,medium,and high crushing velocities.The theoretically predicted plateau stress of the FDRCS under different crushing velocities is consistent with the numerical simulation results.The crushing stress and the EAC of the FDRCS are influenced by the geometric parameters and crushing velocities.The FDRCS exhibits a negative Poisson's ratio(NPR),owing to the four-point re-entrant structure(RES).Moreover,the specific energy absorption(SEA)of these structures is higher than that of nonauxetic hexagonal and auxetic re-entrant structures,owing to the generation of more plastic hinges that dissipate more energy during dynamic crushing.展开更多
Peach aphid is a common pest and hard to detect.This study employs hyperspectral imaging technology to identify early damage in green cabbage caused by peach aphid.Through principal component transformation and multip...Peach aphid is a common pest and hard to detect.This study employs hyperspectral imaging technology to identify early damage in green cabbage caused by peach aphid.Through principal component transformation and multiple linear regression analysis,the correlation relation between spectral characteristics and infestation stage is analyzed.Then,four characteristic wavelength selection methods are compared and optimal characteristic wavelengths subset is determined to be input for modelling.One linear algorithm and two nonlinear modelling algorithms are compared.Finally,support vector machine(SVM)model based on the characteristic wavelengths selected by multi-cluster feature selection(MCFS)acquires the highest identification accuracy,which is 98.97%.These results indicate that hyperspectral imaging technology have the ability to identify early peach aphid infestation stages on green cabbages.展开更多
The freeze-thaw cycling process considerably changes the composition,structure,and properties of soils.Since the grain size is the most important factor in determining soil characteristics,our current research primari...The freeze-thaw cycling process considerably changes the composition,structure,and properties of soils.Since the grain size is the most important factor in determining soil characteristics,our current research primarily aims to investigate dynamic changes of the soil fraction when exposed to freeze-thaw conditions.We observed two series of Moscow morainic clayey specimens(g QmII):(I) the original series,and(II) the remolded series.We subjected each series of soil specimens to different frequencies of freeze-thaw cycles(3,6,20,and 40 cycles),and we used granulometric tests to analyze both series before and after exposure to freeze-thaw conditions.As a result of our experiments,the granulometric compositions tended to be distributed evenly after 40 freeze-thaw processes(i.e.,content of fraction for 0.1–0.05 mm was increased after 40 freeze-thaw cycles) because the division of coarse grains and the aggregation of fine grains were synchronized during the freeze-thaw process.The soil grains in both series changed bi-directionally.In the original series,changes of the sand grains were conjugated with the clay grains,and in the remolded series,changes of the sand grains were conjugated with the silt grains,because potential energy difference caused the division and aggregation processes to relate to the counteraction process.The even distribution of soil grain size indicated the state of equilibrium or balance.The granulometric compositions were altered the most during the sixth freeze-thaw cycle,because the coefficient of the intensity variation of the grain fineness(Kvar) had its maximum value at that time.展开更多
In order to determine the changing rule of long-term frozen soil strength and elucidate the connection between long-term strength and soil physical properties,frozen loess was subjected to 4,6,8,10,and 50 freeze-thaw ...In order to determine the changing rule of long-term frozen soil strength and elucidate the connection between long-term strength and soil physical properties,frozen loess was subjected to 4,6,8,10,and 50 freeze-thaw cycles,under closed-state conditions in a constant-temperature box.The frozen samples were tested on a spherical template indenter,and the results show that under the effect of repeated freeze-thaw cycles,the long-term strength of frozen loess decreased; changes in the mechanical property indices were highly unstable during the first 10 cycles; the soil strength and density were the greatest at the eighth cycle while the void ratio was the smallest; and after eight cycles all of the indices had less fluctuation and certain rising or falling tendencies.By converting the number of freeze-thaw cycles into elapsed time in the tests,three different forecasting methods of long-term soil strength could be assessed and the soil equivalent cohesive force after 10 years,20 years,or 30 years could be estimated.展开更多
With globe warming,road safety will change dramatically,especially within the Qinghai-Tibet Plateau permafrost regions.Because of higher elevation and better atmospheric transparency,the Qinghai-Tibet Plateau has stro...With globe warming,road safety will change dramatically,especially within the Qinghai-Tibet Plateau permafrost regions.Because of higher elevation and better atmospheric transparency,the Qinghai-Tibet Plateau has stronger radiation than other regions,which can change the daily variation of ground surface temperature on the Plateau.The awning measure(shading board) is one of the actively protected permafrost measures,which was adopted along the Qinghai-Tibet railway and highway and the Qing-Kang Highway in China.Field test results show that embankment surface month mean net radiation is 60-130 W/m2,but the value is below 20 W/m2 under the shading board,and the reducing level of natural net radiation is 80%-90%.The shading board reduced the heat flow entering into the embankment by 80%-90% or more,with heat entering into the soil on the common embankment,but emitting from the embankment under the shading board.At the same time,ground surface temperature under the shading board is 6-8 ℃ lower than the exposed embankment.Test results show that the shading board measure can rapidly and effectively reduce net radiation and heat flow into the embankment,decrease embankment surface and interior temperature,effectively delay increase rate of soil temperature under globe warming,ensure stability and safety of the embankment,and guarantee unblocked road projects in cold and permafrost regions.展开更多
Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak e...Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak elastic foundation are first derived by the variational principle.The polynomial particular solutions corresponding to the established model are then obtained and further employed as basis functions with the method of particular solutions(MPS)to solve the governing equations numerically.It is confirmed that for the present bending model,the new solution strategy possesses more general applicability and superior flexibility in the selection of collocation points.The effects of different boundary conditions,applied loads,and geometrical shapes on the bending properties of MEE nanoplates are evaluated by using the developed method.Some important conclusions are drawn,which should be helpful for the design and applications of electromagnetic nanoplate structures.展开更多
Based on ground temperatures and deformations monitored at the Xieshuihe site along the Qinghai-Tibet Highway(QTH)in permafrost regions from 2004 to 2015,variation of artificial permafrost table(APT),maximum frozen de...Based on ground temperatures and deformations monitored at the Xieshuihe site along the Qinghai-Tibet Highway(QTH)in permafrost regions from 2004 to 2015,variation of artificial permafrost table(APT),maximum frozen depth(MFD),thawed interlayer thickness(TIT)and ground temperature beneath embankment is analyzed,respectively.The results indicate that under the embankment,the change of APT occurred from October to December of that year and presented a deepening trend.The change of MFD occurred from April to June of that year with no obvious change trend,and TIT had an increasing trend year by year,which mainly resulted from the deepening artificial permafrost table.Mean annual ground temperature at 0.5 m depth was 3.91°C higher beneath the embankment center than that under the natural field.The rising ground temperature at shallow layer of embankment resulted in the development of thawed interlayer beneath the embankment and warming of underlying permafrost.Embankment settlement is closely associated with TIT.Greater settlement easily occurs when permafrost with higher ice content exists under the thawed interlayer,and in turn the settlement is smaller when permafrost with lower ice content exists under the thawed interlayer.展开更多
Sarcopenia is an age-related disease that mainly involves decreases in muscle mass,muscle strength and muscle function.At the same time,the body fat content increases with aging,especially the visceral fat content.Adi...Sarcopenia is an age-related disease that mainly involves decreases in muscle mass,muscle strength and muscle function.At the same time,the body fat content increases with aging,especially the visceral fat content.Adipose tissue is an endocrine organ that secretes biologically active factors called adipokines,which act on local and distant tissues.Studies have revealed that some adipokines exert regulatory effects on muscle,such as higher serum leptin levels causing a decrease in muscle function and adiponectin inhibits the transcriptional activity of Forkhead box O3(FoxO3)by activating peroxisome proliferators-activated receptor-γcoactivator-1α(PGC-1α)and sensitizing cells to insulin,thereby repressing atrophy-related genes(atrogin-1 and muscle RING finger 1[MuRF1])to prevent the loss of muscle mass.Here,we describe the effects on muscle of adipokines produced by adipose tissue,such as leptin,adiponectin,resistin,mucin and lipocalin-2,and discuss the importance of these adipokines for understanding the development of sarcopenia.展开更多
Understanding controls on river planform changes can help to build predictive models for distributive fluvial systems,and then guide the oil and gas exploration.To do this we have undertaken a detailed investigation o...Understanding controls on river planform changes can help to build predictive models for distributive fluvial systems,and then guide the oil and gas exploration.To do this we have undertaken a detailed investigation of the modern Great Halten River distributive fluvial system from the Sugan Lake Basin,Qinghai,China.Unmanned aerial vehicle(UAV) photography,satellite remote sensing data and elemental analysis were used to determine differences in the sedimentary characteristics of the distributive fluvial system.From the apex to the toe,the changes in the slope,river morphology,sedimentary characteristics and element content in different regions were determined and three facies belts:“proximal”,“medial” and “distal” were identified.We found that the sedimentary structure and elemental content characteristics of each facies differ greatly.We compare the large-scale evolution of rivers from braided to meandering rivers,and the fine description of sedimentary characteristics in combination with each observation,we strengthen our overall understanding of the modern DFS from macro to micro scale.At the same time,we summarize the sedimentation model of the Great Halten River DFS,and our study provides a reference for establishing the sedimentary model in continental petroliferous basins.展开更多
Atherosclerosis is characterized by the accumulation of lipids and deposition of fibrous elements in the vascular wall, which is the primary cause of cardiovascular diseases. Adenosine monophosphate-activated protein ...Atherosclerosis is characterized by the accumulation of lipids and deposition of fibrous elements in the vascular wall, which is the primary cause of cardiovascular diseases. Adenosine monophosphate-activated protein kinase(AMPK) is a metabolic sensor of energy metabolism that regulates multiple physiological processes, including lipid and glucose metabolism and the normalization of energy imbalances. Overwhelming evidence indicates that AMPK activation markedly attenuates atherosclerosis development. Autophagy inhibits cell apoptosis and inflammation and promotes cholesterol efflux and efferocytosis. Physiological autophagy is essential for maintaining normal cardiovascular function. Increasing evidence demonstrates that autophagy occurs in developing atherosclerotic plaques. Emerging evidence indicates that AMPK regulates autophagy via a downstream signaling pathway. The complex relationship between AMPK and autophagy has attracted the attention of many researchers because of this close relationship to atherosclerosis development. This review demonstrates the role of AMPK and autophagy in atherosclerosis. An improved understanding of this interrelationship will create novel preventive and therapeutic strategies for atherosclerosis.展开更多
Xanthomonas oryzae pv.oryzicola(Xoc),which causes rice bacterial leaf streak,invades leaves mainly through stomata,which are often closed as a plant immune response against pathogen invasion.How Xoc overcomes stomatal...Xanthomonas oryzae pv.oryzicola(Xoc),which causes rice bacterial leaf streak,invades leaves mainly through stomata,which are often closed as a plant immune response against pathogen invasion.How Xoc overcomes stomatal immunity is unclear.Here,we show that the effector protein AvrRxo1,an ATPdependent protease,enhances Xoc virulence and inhibits stomatal immunity by targeting and degrading rice OsPDX1(pyridoxal phosphate synthase),thereby reducing vitamin B6(VB6)levels in rice.VB6 is required for the activity of aldehyde oxidase,which catalyzes the last step of abscisic acid(ABA)biosynthesis,and ABA positively regulates rice stomatal immunity against Xoc.Thus,we provide evidence supporting a model in which a major bacterial pathogen inhibits plant stomatal immunity by directly targeting VB6 biosynthesis and consequently inhibiting the biosynthesis of ABA in guard cells to open stomata.Moreover,AvrRxo1-mediated VB6 targeting also explains the poor nutritional quality,including low VB6 levels,of Xoc-infected rice grains.展开更多
The linear dynamic theory of microstretch thermomagnetoelectroelasticity is studied in this paper.First,a reciprocity relation which involves two processes at different instants is established to form the basis of a u...The linear dynamic theory of microstretch thermomagnetoelectroelasticity is studied in this paper.First,a reciprocity relation which involves two processes at different instants is established to form the basis of a uniqueness result and a reciprocal theorem.The proof of the reciprocal theorem avoids both using the Laplace transform and incorporating the initial conditions into the equations of motion.The uniqueness theorem is derived with no definiteness assumption on the elastic constitutive coefficients.Then the continuous dependence theorem is discussed upon two external data systems.Finally,the variational principle of Hamilton type which fully characterizes the solution of the mixed boundary-initial-value problem(mixed problem) is obtained.These theorems lay a solid foundation for further theoretical and numerical studies on microstretch thermomagnetoelectroelastic materials.展开更多
The mechanical properties of a superconducting composite cylinder with transport current are investigated. By adopting the exponent model, the nonlinear differential equations for flux distributions are derived. The e...The mechanical properties of a superconducting composite cylinder with transport current are investigated. By adopting the exponent model, the nonlinear differential equations for flux distributions are derived. The elastic solutions to stress, displacement and magnetostriction are analytically given. Some typical numerical results are displayed. Numerical results show that in the process of transport current reduction, tensile stress generally occurs in the outer region of the composite, and that displacement is always negative in the composite. In addition, as the applied maximal transport current exceeds the outer-cylinder critical current, a hysteresis loop of the magnetostriction exists for the full cycle of the transport current.展开更多
A magnetoelectrically permeable interface crack between two semi-infinite magnetoelectroelastic planes under the action of a heat flow and remote magnetoelectromechanical loadings is considered, where the assumption o...A magnetoelectrically permeable interface crack between two semi-infinite magnetoelectroelastic planes under the action of a heat flow and remote magnetoelectromechanical loadings is considered, where the assumption of frictionless contact between two dissimilar halfplanes is adopted. Not only the solutions of the interface crack problem are presented in an explicit form, but also the general condition for the transition from a perfect thermal contact of two magnetoelectroelastic bodies to their separation is given.展开更多
The aim of this paper is to present the backward substitution method for solving a class of fractional dual-phase-lag models of heat transfer.The proposed method is based on the Fourier series expansion along the spat...The aim of this paper is to present the backward substitution method for solving a class of fractional dual-phase-lag models of heat transfer.The proposed method is based on the Fourier series expansion along the spatial coordinate over the orthonormal basis formed by the eigenfunctions of the corresponding Sturm-Liouville problem.This Fourier expansion of the solution transforms the original fractional par-tial differential equation into a sequence of multi-term fractional ordinary differential equations.These fractional equations are solved by the use of the backward substi-tution method.The numerical examples with temperature-jump boundary condition and parameters of the tissue confirm the high accuracy and efficiency of the proposed numerical scheme.展开更多
基金the National Natural Science Foundation of China(Nos.12102274,1207220311872253)+1 种基金the Natural Science Foundation of Hebei Province of China(No.A2022210005)the Central Guidance on Local Science and Technology Development Fund of Hebei Province of China(No.226Z4901G)。
文摘Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption applications.In this study,a novel modified re-entrant hybrid auxetic metamaterial inspired by Islamic motif art is designed by integrating four-pointed double re-entrant motifs with symmetric semi-hexagonal unit cells to achieve a high energy absorption capacity(EAC).Theoretical analyses and numerical simulations are performed to examine the dynamic crushing behavior of the four-pointed double re-entrant combined structure(FDRCS).The developed finite element models(FEMs)are validated by the experiments under quasi-static compression.The deformation mode and stress-strain curves are further studied under low,medium,and high crushing velocities.The theoretically predicted plateau stress of the FDRCS under different crushing velocities is consistent with the numerical simulation results.The crushing stress and the EAC of the FDRCS are influenced by the geometric parameters and crushing velocities.The FDRCS exhibits a negative Poisson's ratio(NPR),owing to the four-point re-entrant structure(RES).Moreover,the specific energy absorption(SEA)of these structures is higher than that of nonauxetic hexagonal and auxetic re-entrant structures,owing to the generation of more plastic hinges that dissipate more energy during dynamic crushing.
基金supported by China National Key Research and Development Program(No.2016YFD0700304)Shandong Natural Science Foundation Youth Program(No.ZR2021QC216)Agricultural Scientific and Technological Innovation Project of Shandong Academy of Agricultural Science(No.CXGC2023A34)。
文摘Peach aphid is a common pest and hard to detect.This study employs hyperspectral imaging technology to identify early damage in green cabbage caused by peach aphid.Through principal component transformation and multiple linear regression analysis,the correlation relation between spectral characteristics and infestation stage is analyzed.Then,four characteristic wavelength selection methods are compared and optimal characteristic wavelengths subset is determined to be input for modelling.One linear algorithm and two nonlinear modelling algorithms are compared.Finally,support vector machine(SVM)model based on the characteristic wavelengths selected by multi-cluster feature selection(MCFS)acquires the highest identification accuracy,which is 98.97%.These results indicate that hyperspectral imaging technology have the ability to identify early peach aphid infestation stages on green cabbages.
基金supported in part by the National Natural Science Foundation of China(No.41301070)the West Light Program for Talent Cultivation of Chinese Academy of Sciencesthe project sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,which granted to Dr.Ze Zhang
文摘The freeze-thaw cycling process considerably changes the composition,structure,and properties of soils.Since the grain size is the most important factor in determining soil characteristics,our current research primarily aims to investigate dynamic changes of the soil fraction when exposed to freeze-thaw conditions.We observed two series of Moscow morainic clayey specimens(g QmII):(I) the original series,and(II) the remolded series.We subjected each series of soil specimens to different frequencies of freeze-thaw cycles(3,6,20,and 40 cycles),and we used granulometric tests to analyze both series before and after exposure to freeze-thaw conditions.As a result of our experiments,the granulometric compositions tended to be distributed evenly after 40 freeze-thaw processes(i.e.,content of fraction for 0.1–0.05 mm was increased after 40 freeze-thaw cycles) because the division of coarse grains and the aggregation of fine grains were synchronized during the freeze-thaw process.The soil grains in both series changed bi-directionally.In the original series,changes of the sand grains were conjugated with the clay grains,and in the remolded series,changes of the sand grains were conjugated with the silt grains,because potential energy difference caused the division and aggregation processes to relate to the counteraction process.The even distribution of soil grain size indicated the state of equilibrium or balance.The granulometric compositions were altered the most during the sixth freeze-thaw cycle,because the coefficient of the intensity variation of the grain fineness(Kvar) had its maximum value at that time.
基金This project is supported in part by the Natural Science Foundation of China (Nos.41301070,41301071)the West Light Program for Talent Cultivation of the Chinese Academy of Sciences (2013-03)the project sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars of State Education Ministry,granted to Dr.Ze Zhang
文摘In order to determine the changing rule of long-term frozen soil strength and elucidate the connection between long-term strength and soil physical properties,frozen loess was subjected to 4,6,8,10,and 50 freeze-thaw cycles,under closed-state conditions in a constant-temperature box.The frozen samples were tested on a spherical template indenter,and the results show that under the effect of repeated freeze-thaw cycles,the long-term strength of frozen loess decreased; changes in the mechanical property indices were highly unstable during the first 10 cycles; the soil strength and density were the greatest at the eighth cycle while the void ratio was the smallest; and after eight cycles all of the indices had less fluctuation and certain rising or falling tendencies.By converting the number of freeze-thaw cycles into elapsed time in the tests,three different forecasting methods of long-term soil strength could be assessed and the soil equivalent cohesive force after 10 years,20 years,or 30 years could be estimated.
基金supported by the Funds of the State Key Laboratory of Frozen Soils Engineering,CAS(Grant No. SKLFSE-ZY-03)the National Key Natural Science Foundation of China(Grant No.50534040)+1 种基金the National Natural Science Foundation of China(Grant Nos. 40821001, 40801022,40801024,40801026,50976120,41001041)the Western Project Program of the Chinese Academy of Sciences(Grant No.KZCX2-XB2-10)
文摘With globe warming,road safety will change dramatically,especially within the Qinghai-Tibet Plateau permafrost regions.Because of higher elevation and better atmospheric transparency,the Qinghai-Tibet Plateau has stronger radiation than other regions,which can change the daily variation of ground surface temperature on the Plateau.The awning measure(shading board) is one of the actively protected permafrost measures,which was adopted along the Qinghai-Tibet railway and highway and the Qing-Kang Highway in China.Field test results show that embankment surface month mean net radiation is 60-130 W/m2,but the value is below 20 W/m2 under the shading board,and the reducing level of natural net radiation is 80%-90%.The shading board reduced the heat flow entering into the embankment by 80%-90% or more,with heat entering into the soil on the common embankment,but emitting from the embankment under the shading board.At the same time,ground surface temperature under the shading board is 6-8 ℃ lower than the exposed embankment.Test results show that the shading board measure can rapidly and effectively reduce net radiation and heat flow into the embankment,decrease embankment surface and interior temperature,effectively delay increase rate of soil temperature under globe warming,ensure stability and safety of the embankment,and guarantee unblocked road projects in cold and permafrost regions.
基金Project supported by the National Natural Science Foundation of China(Nos.11872257 and 11572358)the German Research Foundation(No.ZH 15/14-1)。
文摘Based on the nonlocal theory and Mindlin plate theory,the governing equations(i.e.,a system of partial differential equations(PDEs)for bending problem)of magnetoelectroelastic(MEE)nanoplates resting on the Pasternak elastic foundation are first derived by the variational principle.The polynomial particular solutions corresponding to the established model are then obtained and further employed as basis functions with the method of particular solutions(MPS)to solve the governing equations numerically.It is confirmed that for the present bending model,the new solution strategy possesses more general applicability and superior flexibility in the selection of collocation points.The effects of different boundary conditions,applied loads,and geometrical shapes on the bending properties of MEE nanoplates are evaluated by using the developed method.Some important conclusions are drawn,which should be helpful for the design and applications of electromagnetic nanoplate structures.
基金supported by the National Natural Science Foundation of China (No. 41571064)the Key Program of National Natural Science Foundation of China (No. 41630636)the Independent Research of the State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZT-09)
文摘Based on ground temperatures and deformations monitored at the Xieshuihe site along the Qinghai-Tibet Highway(QTH)in permafrost regions from 2004 to 2015,variation of artificial permafrost table(APT),maximum frozen depth(MFD),thawed interlayer thickness(TIT)and ground temperature beneath embankment is analyzed,respectively.The results indicate that under the embankment,the change of APT occurred from October to December of that year and presented a deepening trend.The change of MFD occurred from April to June of that year with no obvious change trend,and TIT had an increasing trend year by year,which mainly resulted from the deepening artificial permafrost table.Mean annual ground temperature at 0.5 m depth was 3.91°C higher beneath the embankment center than that under the natural field.The rising ground temperature at shallow layer of embankment resulted in the development of thawed interlayer beneath the embankment and warming of underlying permafrost.Embankment settlement is closely associated with TIT.Greater settlement easily occurs when permafrost with higher ice content exists under the thawed interlayer,and in turn the settlement is smaller when permafrost with lower ice content exists under the thawed interlayer.
基金National Natural Science Foundation of China(Nos.82272611,82072506)National Clinical Research Center for Geriatric Disorders(Nos.2021KFJJ02 and 2021LNJJ05)+4 种基金National Clinical Research Center for Orthopedics,Sports Medicine and Rehabilitation(No.2021-NCRC-CXJJ-PY-40)Science and Technology Innovation Program of Hunan Province(No.2021RC3025)Innovation-Driven Project of Central South university(No.2020CX045)Program of Health Commission of Hunan Province(202204074879)Independent Exploration and Innovation Project for Post-graduate Students of Central South University(No.2022ZZTS0906)
文摘Sarcopenia is an age-related disease that mainly involves decreases in muscle mass,muscle strength and muscle function.At the same time,the body fat content increases with aging,especially the visceral fat content.Adipose tissue is an endocrine organ that secretes biologically active factors called adipokines,which act on local and distant tissues.Studies have revealed that some adipokines exert regulatory effects on muscle,such as higher serum leptin levels causing a decrease in muscle function and adiponectin inhibits the transcriptional activity of Forkhead box O3(FoxO3)by activating peroxisome proliferators-activated receptor-γcoactivator-1α(PGC-1α)and sensitizing cells to insulin,thereby repressing atrophy-related genes(atrogin-1 and muscle RING finger 1[MuRF1])to prevent the loss of muscle mass.Here,we describe the effects on muscle of adipokines produced by adipose tissue,such as leptin,adiponectin,resistin,mucin and lipocalin-2,and discuss the importance of these adipokines for understanding the development of sarcopenia.
基金supported by the National Natural Science Foundation of China (Nos.41772094 and 42130813)。
文摘Understanding controls on river planform changes can help to build predictive models for distributive fluvial systems,and then guide the oil and gas exploration.To do this we have undertaken a detailed investigation of the modern Great Halten River distributive fluvial system from the Sugan Lake Basin,Qinghai,China.Unmanned aerial vehicle(UAV) photography,satellite remote sensing data and elemental analysis were used to determine differences in the sedimentary characteristics of the distributive fluvial system.From the apex to the toe,the changes in the slope,river morphology,sedimentary characteristics and element content in different regions were determined and three facies belts:“proximal”,“medial” and “distal” were identified.We found that the sedimentary structure and elemental content characteristics of each facies differ greatly.We compare the large-scale evolution of rivers from braided to meandering rivers,and the fine description of sedimentary characteristics in combination with each observation,we strengthen our overall understanding of the modern DFS from macro to micro scale.At the same time,we summarize the sedimentation model of the Great Halten River DFS,and our study provides a reference for establishing the sedimentary model in continental petroliferous basins.
基金supported by the National Natural Science Foundation of China (81670401)the Natural Sciences Foundation of Hunan Province (2016JJ6133)+2 种基金the Scientific Research Innovation Program of Post-graduate in Hunan Province (CX2017B554)Zhengxiang Scholar (Xiangyang Tang) Program of the University of South ChinaThe Construct Program of the Key Discipline in Hunan Province (Basic Medicine Sciences in University of South China)
文摘Atherosclerosis is characterized by the accumulation of lipids and deposition of fibrous elements in the vascular wall, which is the primary cause of cardiovascular diseases. Adenosine monophosphate-activated protein kinase(AMPK) is a metabolic sensor of energy metabolism that regulates multiple physiological processes, including lipid and glucose metabolism and the normalization of energy imbalances. Overwhelming evidence indicates that AMPK activation markedly attenuates atherosclerosis development. Autophagy inhibits cell apoptosis and inflammation and promotes cholesterol efflux and efferocytosis. Physiological autophagy is essential for maintaining normal cardiovascular function. Increasing evidence demonstrates that autophagy occurs in developing atherosclerotic plaques. Emerging evidence indicates that AMPK regulates autophagy via a downstream signaling pathway. The complex relationship between AMPK and autophagy has attracted the attention of many researchers because of this close relationship to atherosclerosis development. This review demonstrates the role of AMPK and autophagy in atherosclerosis. An improved understanding of this interrelationship will create novel preventive and therapeutic strategies for atherosclerosis.
基金This study was supported by the National Natural Science Foundation(31872925 and 32072500)Natural Science Outstanding Youth Fund of Shandong Province(JQ201807)+3 种基金Shandong Province Key Research and Development Plan(2019JZZY020608,2020CXGC010803,and 2019GN C106152)Science and Technology Support Plan for Youth Innovation of Colleges and Universities of Shandong Province(2019KJF023)the National Key Research and Development Program of China(2016YFD0100903)X.D.thanks S.H.for hosting his research visit at Mich-igan State University,supported by the United States National Institute of General Medical Sciences(GM109928).
文摘Xanthomonas oryzae pv.oryzicola(Xoc),which causes rice bacterial leaf streak,invades leaves mainly through stomata,which are often closed as a plant immune response against pathogen invasion.How Xoc overcomes stomatal immunity is unclear.Here,we show that the effector protein AvrRxo1,an ATPdependent protease,enhances Xoc virulence and inhibits stomatal immunity by targeting and degrading rice OsPDX1(pyridoxal phosphate synthase),thereby reducing vitamin B6(VB6)levels in rice.VB6 is required for the activity of aldehyde oxidase,which catalyzes the last step of abscisic acid(ABA)biosynthesis,and ABA positively regulates rice stomatal immunity against Xoc.Thus,we provide evidence supporting a model in which a major bacterial pathogen inhibits plant stomatal immunity by directly targeting VB6 biosynthesis and consequently inhibiting the biosynthesis of ABA in guard cells to open stomata.Moreover,AvrRxo1-mediated VB6 targeting also explains the poor nutritional quality,including low VB6 levels,of Xoc-infected rice grains.
基金Project supported by the National Natural Science Fundation of China(Nos.11572358 and 11272223)the Training Program for Leading Talent in University Innovative Research Team in Hebei Province(No.LJRC006)
文摘The linear dynamic theory of microstretch thermomagnetoelectroelasticity is studied in this paper.First,a reciprocity relation which involves two processes at different instants is established to form the basis of a uniqueness result and a reciprocal theorem.The proof of the reciprocal theorem avoids both using the Laplace transform and incorporating the initial conditions into the equations of motion.The uniqueness theorem is derived with no definiteness assumption on the elastic constitutive coefficients.Then the continuous dependence theorem is discussed upon two external data systems.Finally,the variational principle of Hamilton type which fully characterizes the solution of the mixed boundary-initial-value problem(mixed problem) is obtained.These theorems lay a solid foundation for further theoretical and numerical studies on microstretch thermomagnetoelectroelastic materials.
基金Support from the National Natural Science Foundation of China(Grant Nos.11272223 and 11072160)the Program for Changjiang Scholars and Innovative Research Team in University(IRT0971)
文摘The mechanical properties of a superconducting composite cylinder with transport current are investigated. By adopting the exponent model, the nonlinear differential equations for flux distributions are derived. The elastic solutions to stress, displacement and magnetostriction are analytically given. Some typical numerical results are displayed. Numerical results show that in the process of transport current reduction, tensile stress generally occurs in the outer region of the composite, and that displacement is always negative in the composite. In addition, as the applied maximal transport current exceeds the outer-cylinder critical current, a hysteresis loop of the magnetostriction exists for the full cycle of the transport current.
基金supported by the National Natural Science Foundation of China (Nos. 10772123 and 11072160)the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0971)the Natural Science Fund for Outstanding Younger of Hebei Province (A2009001624), China
文摘A magnetoelectrically permeable interface crack between two semi-infinite magnetoelectroelastic planes under the action of a heat flow and remote magnetoelectromechanical loadings is considered, where the assumption of frictionless contact between two dissimilar halfplanes is adopted. Not only the solutions of the interface crack problem are presented in an explicit form, but also the general condition for the transition from a perfect thermal contact of two magnetoelectroelastic bodies to their separation is given.
基金The work was supported by the Natural Science Foundation of China(No.12072103)the Fundamental Research Funds for the Central Universities(No.B200202126)+4 种基金the Natural Science Foundation of Jiangsu Province(No.BK20190073)the State Key Laboratory of Acoustics,Chinese Academy of Sciences(No.SKLA202001)the State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University(No.KF2020-22)the Key Laboratory of Intelligent Materials and Structural Mechanics of Hebei Province(No.KF2021-01)the China Postdoctoral Science Foundation(Nos.2017M611669 and 2018T110430).
文摘The aim of this paper is to present the backward substitution method for solving a class of fractional dual-phase-lag models of heat transfer.The proposed method is based on the Fourier series expansion along the spatial coordinate over the orthonormal basis formed by the eigenfunctions of the corresponding Sturm-Liouville problem.This Fourier expansion of the solution transforms the original fractional par-tial differential equation into a sequence of multi-term fractional ordinary differential equations.These fractional equations are solved by the use of the backward substi-tution method.The numerical examples with temperature-jump boundary condition and parameters of the tissue confirm the high accuracy and efficiency of the proposed numerical scheme.
