Rapidly expanding studies investigate the effects of e-commerce on company operations in the retail market.However,the interaction between agri-food e-commerce(AEC)and the traditional agri-food wholesale industry(AWI)...Rapidly expanding studies investigate the effects of e-commerce on company operations in the retail market.However,the interaction between agri-food e-commerce(AEC)and the traditional agri-food wholesale industry(AWI)has not received enough attention in the existing literature.Based on the provincial panel data from 2013 to 2020 in China,this paper examines the effect of AEC on AWI,comprising three dimensions:digitalization(DIGITAL),agrifood e-commerce infrastructure and supporting services(AECI),and agri-food e-commerce economy(AECE).First,AWI and AEC are measured using an entropy-based combination of indicators.The results indicate that for China as a whole,AWI has remained practically unchanged,whereas AEC exhibits a significant rising trend.Second,the findings of the fixed-effect regression reveal that DIGITAL and AECE tend to raise AWI,whereas AECI negatively affects AWI.Third,threshold regression results indicate that AECI tends to diminish AWI with three-stage inhibitory intensity,which manifests as a first increase and then a drop in the inhibition degree.These results suggest that with the introduction of e-commerce for agricultural product circulation,digital development will have catfish effects that tend to stimulate the vitality of the conventional wholesale industry and promote technical progress.Furthermore,the traditional wholesale industry benefits financially from e-commerce even while it diverts part of the traditional wholesale circulation for agricultural products.展开更多
Jet quenching parameter q is essential for characterizing the interaction strength between jet partons and nuclear matter.Based on the quark-meson model,we develop a new framework for calculating q at finite chemical ...Jet quenching parameter q is essential for characterizing the interaction strength between jet partons and nuclear matter.Based on the quark-meson model,we develop a new framework for calculating q at finite chemical potentials,in which q is related to the spectral function of the chiral order parameter.展开更多
Air pollution has seriously endangered human health and the natural ecosystem during the last decades.Air quality monitoring stations(AQMS)have played a critical role in providing valuable data sets for recording regi...Air pollution has seriously endangered human health and the natural ecosystem during the last decades.Air quality monitoring stations(AQMS)have played a critical role in providing valuable data sets for recording regional air pollutants.The spatial representativeness of AQMS is a critical parameter when choosing the location of stations and assessing effects on the population to long-term exposure to air pollution.In this paper,we proposed a methodological framework for assessing the spatial representativeness of the regional air quality monitoring network and applied it to ground-based PM_(2.5)observation in the mainland of China.Weighted multidimensional Euclidean distance between each pixel and the stations was used to determine the representativeness of the existing monitoring network.In addition,the K-means clustering method was adopted to improve the spatial representativeness of the existing AQMS.The results showed that there were obvious differences among the representative area of 1820 stations in the mainland of China.The monitoring stations could well represent the PM_(2.5)spatial distribution of the entire region,and the effectively represented area(i.e.the area where the Euclidean distance between the pixels and the stations was lower than the average value)accounted for 67.32%of the total area and covered 93.12%of the population.Forty additional stations were identified in the Northwest,North China,and Northeast regions,which could improve the spatial representativeness by 14.31%.展开更多
In order to investigate and research the fatigue cracking of prestressed concrete fatigue properties and loading and stiffness degeneration process,cyclic loading tests were carried out on six prestressed concrete bea...In order to investigate and research the fatigue cracking of prestressed concrete fatigue properties and loading and stiffness degeneration process,cyclic loading tests were carried out on six prestressed concrete beams and the stiffness degradation under fatigue was investigated. A simulation model of stiffness degradation is proposed based on the stiffness analysis of the fatigue-damaged section. The elastic modulus of damaged concrete and the effective residual area of steel were introduced as well as an adjusted three-stage concrete fatigue damage evolution model. The strip method was used to analyze concrete damage due to changing stress along the depth of the beam section. The simulation and test results were compared and a method of predicting fatigue deflection was presented based on the simulation model. The predicted results were compared with that of the neural network method. It is in good agreement for the simulation results with the test results. It is only less than5% error for the simulation model which can reveal the two-stage degradation of prestressed concrete beams under cyclic loading. It is more precise for the simulation prediction method under proper conditions.展开更多
Heavy quark observables are applied to probe the initial energy density distribution with violation of longitudinal boost invariance produced in relativistic heavy-ion collisions.Using an improved Langevin model coupl...Heavy quark observables are applied to probe the initial energy density distribution with violation of longitudinal boost invariance produced in relativistic heavy-ion collisions.Using an improved Langevin model coupled to a(3+1)-dimensional viscous hydrodynamic model,we study the nuclear modification factor(R_(AA)) and directed flow(v_(1)) and elliptic flow(v_(2)) coefficients of heavy mesons and their decayed electrons at an RHIC energy.We find that the counter-clockwise tilt of nuclear matter in the reaction plane results in a positive(negative) heavy flavor vi in the backward(forward) rapidity region,whose magnitude increases with the heavy quark transverse momentum.The difference in the heavy flavor R_(AA) between different angular regions is also proposed as a complementary tool to characterize the asymmetry of the medium profile.Our model results are consistent with currently available data at the RHIC and provide predictions that can be tested by future measurements.展开更多
Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma(QGP).As a multi-particle system,jets require time to develop from a highly virtual parton to a group of partons close...Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma(QGP).As a multi-particle system,jets require time to develop from a highly virtual parton to a group of partons close to mass shells.In this study,we present a systematical analysis on the effects of this formation time on jet quenching in relativistic nuclear collisions.Jets from initial hard scatterings were simulated with Pythia,and their interactions with QGP were described using a Linear Boltzmann Transport(LBT) model that incorporates both elastic and inelastic scatterings between jet partons and the thermal medium.Three different estimations of the jet formation time were implemented and compared,including instantaneous formation,formation from single splitting,and formation from sequential splittings,before which no jet-medium interaction was assumed.We found that deferring the jet-medium interaction with a longer formation time not only affects the overall magnitude of the nuclear modification factor of jets but also its dependence on the jet transverse momentum.展开更多
A near-equiatomic NiTi shape memory alloy was fabricated by rapid solidification process through vacuum arc melting followed by vacuum suction casting in water-cooled thick copper mold.The rapidly solidified(or suctio...A near-equiatomic NiTi shape memory alloy was fabricated by rapid solidification process through vacuum arc melting followed by vacuum suction casting in water-cooled thick copper mold.The rapidly solidified(or suction cast) NiTi alloy shows much finer grains and homogenous microstructure,in particular a uniform distribution of various fine precipitates,compared to the conventional cast one.The resultant alloy also exhibits the homogenous Ni distribution in the matrix of the alloy,allowing the martensitic transformation to take place throughout the NiTi alloy matrix simultaneously and resulting in sharper transformation peaks compared to the conventional cast alloy.Moreover,the suction cast NiTi alloy shows a significant improvement over the conventional cast one,in terms of possessing higher deformation recovery rates and displaying the increased compressive strength and damping capacity by 4% and 20%,respectively.展开更多
The combination of optical fiber with graphene has greatly expanded the application regimes of fiber optics,from dynamic optical control and ultrafast pulse generation to high precision sensing.However,limited by fabr...The combination of optical fiber with graphene has greatly expanded the application regimes of fiber optics,from dynamic optical control and ultrafast pulse generation to high precision sensing.However,limited by fabrication,previous graphene-fiber samples are typically limited in the micrometer to centimeter scale,which cannot take the inherent advantage of optical fibers—longdistance optical transmission.Here,we demonstrate kilometers long graphene-coated optical fiber(GCF)based on industrial graphene nanosheets and coating technique.The GCF shows unusually high thermal diffusivity of 24.99 mm^(2) s^(-1) in the axial direction,measured by a thermal imager directly.This enables rapid thermooptical response both in optical fiber Bragg grating sensors at one point(18-fold faster than conventional fiber)and in long-distance distributed fiber sensing systems based on backward Rayleigh scattering in optical fiber(15-fold faster than conventional fiber).This work realizes the industrial-level graphene-fiber production and provides a novel platform for two-dimensional material-based optical fiber sensing applications.展开更多
Understanding the persistence of antibody in convalescent COVID-19 patients may help to answer the current major concerns such as the risk of reinfection,the protection period of vaccination and the possibility of bui...Understanding the persistence of antibody in convalescent COVID-19 patients may help to answer the current major concerns such as the risk of reinfection,the protection period of vaccination and the possibility of building an active herd immunity.This retrospective cohort study included 172 COVID-19 patients who were hospitalized in Wuhan.A total of404 serum samples were obtained over six months from hospitalization to convalescence.Antibodies in the specimens were quantitatively analyzed by the capture chemiluminescence immunoassays(CLIA).All patients were positive for the anti-SARS-Co V-2 Ig M/Ig G at the onset of COVID-19 symptoms,and the Ig G antibody persisted in all the patients during the convalescence.However,only approximately 25%of patients can detect the Ig M antibodies,Ig M against N protein(NIg M)and receptor binding domain of S protein(RBD-Ig M)at the 27 th week.The titers of Ig M,N-Ig M and RBD-Ig M reduced to 16.7%,17.6%and 15.2%of their peak values respectively.In contrast,the titers of Ig G,N-Ig G and RBD-Ig G peaked at 4–5 th week and reduced to 85.9%,62.6%and 87.2%of their peak values respectively at the end of observation.Dynamic behavior of antibodies and their correlation in age,gender and severity groups were investigated.In general,the COVID-19 antibody was sustained at high levels for over six months in most of the convalescent patients.Only a few patients with antibody reducing to an undetectable level which needs further attention.The humoral immune response against SARS-Co V-2 infection in COVID-19 patients exhibits a typical dynamic of acquired immunity.展开更多
Heavy-ion collisions at very high colliding energies are expected to produce a quark-gluon plasma(QGP) at the highest temperature obtainable in a laboratory setting. Experimental studies of these reactions can provide...Heavy-ion collisions at very high colliding energies are expected to produce a quark-gluon plasma(QGP) at the highest temperature obtainable in a laboratory setting. Experimental studies of these reactions can provide an unprecedented range of information on properties of the QGP at high temperatures. We report theoretical investigations of the physics perspectives of heavy-ion collisions at a future high-energy collider. These include initial parton production, collective expansion of the dense medium, jet quenching,heavy-quark transport, dissociation and regeneration of quarkonia, photon and dilepton production. We illustrate the potential of future experimental studies of the initial particle production and formation of QGP at the highest temperature to provide constraints on properties of strongly interaction matter.展开更多
Within an advanced Langevin-hydrodynamics framework coupled to a hybrid fragmentation-coalescence hadronization model,we study heavy flavor quenching and flow in relativistic heavy-ion collisions.We investigate how th...Within an advanced Langevin-hydrodynamics framework coupled to a hybrid fragmentation-coalescence hadronization model,we study heavy flavor quenching and flow in relativistic heavy-ion collisions.We investigate how the initial heavy quark spectrum,the in-medium energy loss and hadronization mechanisms of heavy quarks,the evolution profile of the pre-equilibrium stage,the medium flow,and the temperature dependence of heavy quark diffusion coefficients influence the suppression and elliptic flow of heavy mesons at the RHIC and the LHC.Our results show that the different modeling of initial conditions,pre-equilibrium evolution,and in-medium interactions can individually yield uncertainties of approximately 10-40% in D meson suppression and flow at a low transverse momentum.We also find that proper combinations of collisional versus radiative energy loss,coalescence versus fragmentation in hadronization,and the inclusion of medium flow are the most important factors for describing the suppression and elliptic flow of heavy mesons.展开更多
Gut microbiota composition is suggested to associate with coronavirus disease 2019(COVID-19)severity,but the impact of gut microbiota on health outcomes is largely unclear.We recruited 81 individuals from Wuhan,China,...Gut microbiota composition is suggested to associate with coronavirus disease 2019(COVID-19)severity,but the impact of gut microbiota on health outcomes is largely unclear.We recruited 81 individuals from Wuhan,China,including 13 asymptomatic infection cases(Group A),24 COVID-19 convalescents with adverse outcomes(Group C),31 severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)re-positive cases(Group D),and 13 non-COVID-19 healthy controls(Group H).The microbial features of Groups A and D were similar and exhibited higher gut microbial diversity and more abundant short-chain fatty acid(SCFA)-producing species than Group C.Group C was enriched with opportunistic pathogens and virulence factors related to adhesion and toxin production.The abundance of SCFA-producing species was negatively correlated,while Escherichia coli was positively correlated with adverse outcomes.All three groups(A,C,and D)were enriched with the mucusdegrading species Akkermansia muciniphila,but decreased with Bacteroides-encoded carbohydrate-active enzymes.The pathways of vitamin B6 metabolic and folate biosynthesis were decreased,while selenocompound metabolism was increased in the three groups.Specifically,the secondary bile acid(BA)metabolic pathway was enriched in Group A.Antibiotic resistance genes were common among the three groups.Conclusively,the gut microbiota was related to the health outcomes of COVID-19.Dietary supplementations(SCFAs,BA,selenium,folate,vitamin B6)may be beneficial to COVID-19 patients.展开更多
基金supported by the Leading Talent Support Program for Agricultural Talents of the Chinese Academy of Agricultural Sciences(TCS2022020)the General program of National Natural Science Foundation of China(1573263)。
文摘Rapidly expanding studies investigate the effects of e-commerce on company operations in the retail market.However,the interaction between agri-food e-commerce(AEC)and the traditional agri-food wholesale industry(AWI)has not received enough attention in the existing literature.Based on the provincial panel data from 2013 to 2020 in China,this paper examines the effect of AEC on AWI,comprising three dimensions:digitalization(DIGITAL),agrifood e-commerce infrastructure and supporting services(AECI),and agri-food e-commerce economy(AECE).First,AWI and AEC are measured using an entropy-based combination of indicators.The results indicate that for China as a whole,AWI has remained practically unchanged,whereas AEC exhibits a significant rising trend.Second,the findings of the fixed-effect regression reveal that DIGITAL and AECE tend to raise AWI,whereas AECI negatively affects AWI.Third,threshold regression results indicate that AECI tends to diminish AWI with three-stage inhibitory intensity,which manifests as a first increase and then a drop in the inhibition degree.These results suggest that with the introduction of e-commerce for agricultural product circulation,digital development will have catfish effects that tend to stimulate the vitality of the conventional wholesale industry and promote technical progress.Furthermore,the traditional wholesale industry benefits financially from e-commerce even while it diverts part of the traditional wholesale circulation for agricultural products.
基金supported by the National Natural Science Foundation of China(Grant Nos.12105129,12175122,2021867,and 12247101)。
文摘Jet quenching parameter q is essential for characterizing the interaction strength between jet partons and nuclear matter.Based on the quark-meson model,we develop a new framework for calculating q at finite chemical potentials,in which q is related to the spectral function of the chiral order parameter.
基金funded by the National Natural Science Foundation of China (41977399)the National Key Research and Development Program (2017YFC0505800)
文摘Air pollution has seriously endangered human health and the natural ecosystem during the last decades.Air quality monitoring stations(AQMS)have played a critical role in providing valuable data sets for recording regional air pollutants.The spatial representativeness of AQMS is a critical parameter when choosing the location of stations and assessing effects on the population to long-term exposure to air pollution.In this paper,we proposed a methodological framework for assessing the spatial representativeness of the regional air quality monitoring network and applied it to ground-based PM_(2.5)observation in the mainland of China.Weighted multidimensional Euclidean distance between each pixel and the stations was used to determine the representativeness of the existing monitoring network.In addition,the K-means clustering method was adopted to improve the spatial representativeness of the existing AQMS.The results showed that there were obvious differences among the representative area of 1820 stations in the mainland of China.The monitoring stations could well represent the PM_(2.5)spatial distribution of the entire region,and the effectively represented area(i.e.the area where the Euclidean distance between the pixels and the stations was lower than the average value)accounted for 67.32%of the total area and covered 93.12%of the population.Forty additional stations were identified in the Northwest,North China,and Northeast regions,which could improve the spatial representativeness by 14.31%.
基金Sponsored by the National Natural Science Foundation of China(Grant No.5117804251308159+4 种基金51578047)the National High Technology Research and Development Program Project(Grant No.2008AA11Z102)China Railway Corporation Research and Development of Science and Technology Plan Project(Grant No.2014G004-B)China Communications Construction Co.LTD Science and Technology Research and Development Projects(Grant No.2014-ZJKJ-03)
文摘In order to investigate and research the fatigue cracking of prestressed concrete fatigue properties and loading and stiffness degeneration process,cyclic loading tests were carried out on six prestressed concrete beams and the stiffness degradation under fatigue was investigated. A simulation model of stiffness degradation is proposed based on the stiffness analysis of the fatigue-damaged section. The elastic modulus of damaged concrete and the effective residual area of steel were introduced as well as an adjusted three-stage concrete fatigue damage evolution model. The strip method was used to analyze concrete damage due to changing stress along the depth of the beam section. The simulation and test results were compared and a method of predicting fatigue deflection was presented based on the simulation model. The predicted results were compared with that of the neural network method. It is in good agreement for the simulation results with the test results. It is only less than5% error for the simulation model which can reveal the two-stage degradation of prestressed concrete beams under cyclic loading. It is more precise for the simulation prediction method under proper conditions.
基金Supported by the National Natural Science Foundation of China (11935007, 12175122, 2021-867)Guangdong Major Project of Basic and Applied Basic Research (2020B0301030008)+3 种基金Natural Science Foundation of Hubei Province (2021CFB272)Education Department of Hubei Province of China with Young Talents Project (Q20212703)Open Foundation of Key Laboratory of Quark and Lepton Physics (MOE)(QLPL202104)Xiaogan Natural Science Foundation(XGKJ2021010016)。
文摘Heavy quark observables are applied to probe the initial energy density distribution with violation of longitudinal boost invariance produced in relativistic heavy-ion collisions.Using an improved Langevin model coupled to a(3+1)-dimensional viscous hydrodynamic model,we study the nuclear modification factor(R_(AA)) and directed flow(v_(1)) and elliptic flow(v_(2)) coefficients of heavy mesons and their decayed electrons at an RHIC energy.We find that the counter-clockwise tilt of nuclear matter in the reaction plane results in a positive(negative) heavy flavor vi in the backward(forward) rapidity region,whose magnitude increases with the heavy quark transverse momentum.The difference in the heavy flavor R_(AA) between different angular regions is also proposed as a complementary tool to characterize the asymmetry of the medium profile.Our model results are consistent with currently available data at the RHIC and provide predictions that can be tested by future measurements.
基金Supported by the National Natural Science Foundation of China (12175122, 2021-867, 11890710, 11890713, 14-547)。
文摘Jet quenching has successfully served as a hard probe to study the properties of Quark-Gluon Plasma(QGP).As a multi-particle system,jets require time to develop from a highly virtual parton to a group of partons close to mass shells.In this study,we present a systematical analysis on the effects of this formation time on jet quenching in relativistic nuclear collisions.Jets from initial hard scatterings were simulated with Pythia,and their interactions with QGP were described using a Linear Boltzmann Transport(LBT) model that incorporates both elastic and inelastic scatterings between jet partons and the thermal medium.Three different estimations of the jet formation time were implemented and compared,including instantaneous formation,formation from single splitting,and formation from sequential splittings,before which no jet-medium interaction was assumed.We found that deferring the jet-medium interaction with a longer formation time not only affects the overall magnitude of the nuclear modification factor of jets but also its dependence on the jet transverse momentum.
基金supported by the National Natural Science Foundation of China under grant Nos. 50871039 and 51205135Guangdong Provincial Natural Science Foundation under grant Nos. 10151064101000017 and S2011040001436the Fundamental Research Funds for Central Universities (SCUT2011ZM0001)
文摘A near-equiatomic NiTi shape memory alloy was fabricated by rapid solidification process through vacuum arc melting followed by vacuum suction casting in water-cooled thick copper mold.The rapidly solidified(or suction cast) NiTi alloy shows much finer grains and homogenous microstructure,in particular a uniform distribution of various fine precipitates,compared to the conventional cast one.The resultant alloy also exhibits the homogenous Ni distribution in the matrix of the alloy,allowing the martensitic transformation to take place throughout the NiTi alloy matrix simultaneously and resulting in sharper transformation peaks compared to the conventional cast alloy.Moreover,the suction cast NiTi alloy shows a significant improvement over the conventional cast one,in terms of possessing higher deformation recovery rates and displaying the increased compressive strength and damping capacity by 4% and 20%,respectively.
基金support from the National Science Foundation of China(61705032 and 61975025)the 111 project(B14039)the UESTC-ZTT joint laboratory project(H04W180463).
文摘The combination of optical fiber with graphene has greatly expanded the application regimes of fiber optics,from dynamic optical control and ultrafast pulse generation to high precision sensing.However,limited by fabrication,previous graphene-fiber samples are typically limited in the micrometer to centimeter scale,which cannot take the inherent advantage of optical fibers—longdistance optical transmission.Here,we demonstrate kilometers long graphene-coated optical fiber(GCF)based on industrial graphene nanosheets and coating technique.The GCF shows unusually high thermal diffusivity of 24.99 mm^(2) s^(-1) in the axial direction,measured by a thermal imager directly.This enables rapid thermooptical response both in optical fiber Bragg grating sensors at one point(18-fold faster than conventional fiber)and in long-distance distributed fiber sensing systems based on backward Rayleigh scattering in optical fiber(15-fold faster than conventional fiber).This work realizes the industrial-level graphene-fiber production and provides a novel platform for two-dimensional material-based optical fiber sensing applications.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFC0861100 and 2020YFC0000)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB29050100)+2 种基金the Key Technology Development Program of Shenzhen(Grant No.JSGG20200225153042494)the Youth Innovation Promotion Association of CAS(Grant No.2014308)the Interdisciplinary Innovation Team of CAS。
文摘Understanding the persistence of antibody in convalescent COVID-19 patients may help to answer the current major concerns such as the risk of reinfection,the protection period of vaccination and the possibility of building an active herd immunity.This retrospective cohort study included 172 COVID-19 patients who were hospitalized in Wuhan.A total of404 serum samples were obtained over six months from hospitalization to convalescence.Antibodies in the specimens were quantitatively analyzed by the capture chemiluminescence immunoassays(CLIA).All patients were positive for the anti-SARS-Co V-2 Ig M/Ig G at the onset of COVID-19 symptoms,and the Ig G antibody persisted in all the patients during the convalescence.However,only approximately 25%of patients can detect the Ig M antibodies,Ig M against N protein(NIg M)and receptor binding domain of S protein(RBD-Ig M)at the 27 th week.The titers of Ig M,N-Ig M and RBD-Ig M reduced to 16.7%,17.6%and 15.2%of their peak values respectively.In contrast,the titers of Ig G,N-Ig G and RBD-Ig G peaked at 4–5 th week and reduced to 85.9%,62.6%and 87.2%of their peak values respectively at the end of observation.Dynamic behavior of antibodies and their correlation in age,gender and severity groups were investigated.In general,the COVID-19 antibody was sustained at high levels for over six months in most of the convalescent patients.Only a few patients with antibody reducing to an undetectable level which needs further attention.The humoral immune response against SARS-Co V-2 infection in COVID-19 patients exhibits a typical dynamic of acquired immunity.
基金the National Natural Science Foundation of China(Grant Nos.11175071,11221504,11305089,11322546,11375072,11435001 and 11435004)China MOST(Grant Nos.2014DFG02050 and2015CB856900)+5 种基金the Major State Basic Research Development Program in China(Grant Nos.2014CB845404 and 2014CB845403)the Natural Sciences and Engineering Research Council of Canadathe US National Science Foundation(Grant No.PHY-1306359)the Director,Office of Energy Research,Office of High Energy and Nuclear Physics,Division of Nuclear Physics,of the U.S.Department of Energy under Contract Nos.DE-AC02-05CH11231,DE-SC0012704within the framework of the JET CollaborationBJS is also supported by a DOE Office of Science Early Career Award
文摘Heavy-ion collisions at very high colliding energies are expected to produce a quark-gluon plasma(QGP) at the highest temperature obtainable in a laboratory setting. Experimental studies of these reactions can provide an unprecedented range of information on properties of the QGP at high temperatures. We report theoretical investigations of the physics perspectives of heavy-ion collisions at a future high-energy collider. These include initial parton production, collective expansion of the dense medium, jet quenching,heavy-quark transport, dissociation and regeneration of quarkonia, photon and dilepton production. We illustrate the potential of future experimental studies of the initial particle production and formation of QGP at the highest temperature to provide constraints on properties of strongly interaction matter.
基金Supported by the Natural Science Foundation of China(NSFC)(11805082,11775095,11890711,11935007)a Project of Shandong Province Higher Educational Science and Technology Program(J17KB128)+2 种基金the China Scholarship Council(CSC)(201906775042)the U.S.Department of Energy(DOE)(DE-SC0013460)the National Science Foundation(NSF)(ACI-1550300)within the framework of the JETSCAPE Collaboration。
文摘Within an advanced Langevin-hydrodynamics framework coupled to a hybrid fragmentation-coalescence hadronization model,we study heavy flavor quenching and flow in relativistic heavy-ion collisions.We investigate how the initial heavy quark spectrum,the in-medium energy loss and hadronization mechanisms of heavy quarks,the evolution profile of the pre-equilibrium stage,the medium flow,and the temperature dependence of heavy quark diffusion coefficients influence the suppression and elliptic flow of heavy mesons at the RHIC and the LHC.Our results show that the different modeling of initial conditions,pre-equilibrium evolution,and in-medium interactions can individually yield uncertainties of approximately 10-40% in D meson suppression and flow at a low transverse momentum.We also find that proper combinations of collisional versus radiative energy loss,coalescence versus fragmentation in hadronization,and the inclusion of medium flow are the most important factors for describing the suppression and elliptic flow of heavy mesons.
基金supported by the National Key Research and Development Program(Grant Nos.2020YFC0861100 and 2020YFC0845000)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB29050100)+1 种基金the Scientific Research Fund of Traditional Chinese Medicine of Hubei Health Commission(Grant No.ZY2021M035)the Youth Innovation Promotion Association of CAS.
文摘Gut microbiota composition is suggested to associate with coronavirus disease 2019(COVID-19)severity,but the impact of gut microbiota on health outcomes is largely unclear.We recruited 81 individuals from Wuhan,China,including 13 asymptomatic infection cases(Group A),24 COVID-19 convalescents with adverse outcomes(Group C),31 severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)re-positive cases(Group D),and 13 non-COVID-19 healthy controls(Group H).The microbial features of Groups A and D were similar and exhibited higher gut microbial diversity and more abundant short-chain fatty acid(SCFA)-producing species than Group C.Group C was enriched with opportunistic pathogens and virulence factors related to adhesion and toxin production.The abundance of SCFA-producing species was negatively correlated,while Escherichia coli was positively correlated with adverse outcomes.All three groups(A,C,and D)were enriched with the mucusdegrading species Akkermansia muciniphila,but decreased with Bacteroides-encoded carbohydrate-active enzymes.The pathways of vitamin B6 metabolic and folate biosynthesis were decreased,while selenocompound metabolism was increased in the three groups.Specifically,the secondary bile acid(BA)metabolic pathway was enriched in Group A.Antibiotic resistance genes were common among the three groups.Conclusively,the gut microbiota was related to the health outcomes of COVID-19.Dietary supplementations(SCFAs,BA,selenium,folate,vitamin B6)may be beneficial to COVID-19 patients.
