The magnetic properties and Kondo effect in Ce3TiBi5 with a quasi-one-dimensional structure were investigated using in situ high-pressure resistivity measurements up to 48 GPa.At ambient pressure,Ce_(3)TiBi_(5) underg...The magnetic properties and Kondo effect in Ce3TiBi5 with a quasi-one-dimensional structure were investigated using in situ high-pressure resistivity measurements up to 48 GPa.At ambient pressure,Ce_(3)TiBi_(5) undergoes an antiferromagnetic(AFM)transition at T_(N)∼5 K.Under high pressures within 8.9 GPa,we find that Kondo scattering contributes differently to the high-temperature resistance,R(T),depending on the applied current direction,demonstrating a significantly anisotropic Kondo effect.The complete P–T phase diagram has been constructed,in which the pressure dependence of T_(N) exhibits a dome-like shape.The AFM order remains robust under pressure,even when the coherence temperature T^(*) far exceeds 300 K.We attribute the observed anisotropic Kondo effect and the robust AFM to the underlying anisotropy in electronic hybridization under high pressure.展开更多
The development and deployment of aluminum conductor have been significantly hampered by the contradiction of yield strength,uniform elongation,and electrical conductivity.Herein,we successfully fabricated a pure alum...The development and deployment of aluminum conductor have been significantly hampered by the contradiction of yield strength,uniform elongation,and electrical conductivity.Herein,we successfully fabricated a pure aluminum(Al)clad aluminum alloy(AA)rod with hierarchical compositions and microstructures.The proposed pure Al clad AA rod showcases an optimized combination of yield strength,uniform elongation,and electrical conductivity,i.e.,easing the restriction on improving yield strength,uniform elongation,and electrical conductivity.Compared to existing experiments,uniform elongation improved fourfold,while yield strength increased by 13%and electrical conductivity improved by 2%in terms of the international annealed copper standard(IACS).Microstructural characterizations and theoretical analyses revealed that the optimal performance of the Al clad AA arose from low-density low-angle grain boundaries(LAGBs)in the outer Al and high-density LAGBs with nanoscale precipitations in the inner AA.Our findings offer a compelling strategy for fabricating high-performance aluminum conductors,thereby laying a solid technical foundation for their wide application in power delivery systems.展开更多
In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on ...In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on fine aluminum powder as a reinforcing phase,can serve as an integrated structural and functional NAM for dry storage applications.Welding is crucial in the fabrication of these casks.In this study,friction stir welding was performed on(B_(4)C+Al_(2)O_(3))/Al composite sheets at a welding speed of 50 mm/min and rotation rates ranging from 500 to 1000 r/min.The microstructure of the weld joints was analyzed,and the intrinsic relationship between fracture behavior and microstructure was elucidated.Results showed that defect-free joints were achieved at rotation rates of 500 and 750 r/min,while tunnel defects were observed at 1000 r/min.The ultimate tensile strength of the joint welded at 500 r/min was 205.7 MPa,with a strength efficiency of 82%.Microstructural analysis revealed that the grains within the nugget zones(NZs)coarsened and the Al_(2)O_(3)network was disrupted due to the welding thermo-mechanical effect,resulting in softening within the NZs.Fracture locations for all three joints were consistently observed at the NZ boundary on the advancing side(AS).Finite element simulations confirmed that cracks propagated along the NZ boundary on the AS,where stress concentration occurred during tensile testing.展开更多
Theoretical analysis and numerical simulation methods were used to study the in-plane crushing behavior of single-cell structures and regular and composite honeycombs.Square,hexagonal,and circular honeycombs were sele...Theoretical analysis and numerical simulation methods were used to study the in-plane crushing behavior of single-cell structures and regular and composite honeycombs.Square,hexagonal,and circular honeycombs were selected as honeycomb layers to establish composite honeycomb models in the form of composite structures and realize the complementary advantages of honeycombs with type Ⅰ and type Ⅱ structures.The effects of honeycomb layer arrangement,plastic collapse strength,relative density,and crushing velocity on the deformation mode,plateau stress,load uniformity,and energy absorption performance of the composite honeycombs were mainly considered.A semi-empirical formula for plateau stress and energy absorption rate per unit mass for the composite honeycombs was developed.The results showed that the arrangement mode of honeycomb layers is an important factor that affects their mechanical properties.Appropriately selecting the arrangement of honeycomb layers and the proportion of honeycomb layers with different structures in a composite honeycomb can effectively improve its load uniformity and control the magnitude of plateau stress and energy absorption capacity.展开更多
In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar ...In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar collision species alternated frequently between 9644 Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr.In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data,STAR developed a three-step blind analysis procedure.Analysts are initially provided a"reference sample"of data,comprised of a mix of events from the two species,the order of which respects time-dependent changes in run conditions.After tuning analysis codes and performing time-dependent quality assurance on the reference sample,analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual≈30-min data-taking runs.For this sample,species-specific information is disguised,but individual output files contain data from a single isobar species.Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage.Following these modifications,the"frozen"code is passed over the fully un-blind data,completing the blind analysis.As a check of the feasibility of the blind analysis procedure,analysts completed a"mock data challenge,"analyzing data from Au+Au collisions at√^(S)NN=27 Ge V,collected in 2018.The Au+Au data were prepared in the same manner intended for the isobar blind data.The details of the blind analysis procedure and results from the mock data challenge are presented.展开更多
With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others w...With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks,which greatly increases the risk of COVID-19 transmission.Therefore,the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated.In this study,a numerical simulation of coughing at dining tables under two conditions was performed,namely the presence and absence of protective partitions,and the evaporation and condensation of aerosol droplets in the air were examined.By using the numerical method,we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets.The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed.We demonstrated how respiratory droplets spread through coughing and how these droplets affect others.Finally,we proposed a design for a dining table partition that minimizes the transmission of COVID-19.展开更多
It has been a central task of solidification research to predict solute microsegregation. Apart from the Lever rule and the Scheil-Gulliver equation, which concern two extreme cases, a long list of microsegregation mo...It has been a central task of solidification research to predict solute microsegregation. Apart from the Lever rule and the Scheil-Gulliver equation, which concern two extreme cases, a long list of microsegregation models has been proposed. However, the use of these models often requires essential experimental input information, e.g., the secondary dendrite arm spacing(λ), cooling rate( ˙T) or actual solidification range(△T). This requirement disables these models for alloy solidification with no measured values for λ,˙T and △T. Furthermore, not all of these required experimental data are easily obtainable. It is therefore highly desirable to have an easy-to-apply predictive model that is independent of experimental input,akin to the Lever rule or Scheil-Gulliver model. Gong, Chen, and co-workers have recently proposed such a model, referred to as the Gong-Chen model, by averaging the solid fractions(f_(s)) of the Lever rule and Scheil-Gulliver model as the actual solid fraction. We provide a systematic assessment of this model versus established solidification microsegregation models and address a latent deficiency of the model, i.e.,it allows the Lever rule solid fraction fsto be greater than one(f_(s)> 1). It is shown that the Gong-Chen model can serve as a generic model for alloy solidification until fsreaches about 0.9, beyond which(f_(s)> 0.9) its applicability is dictated by both the equilibrium solute partition coefcient(k) and the solute diffusion coefcient in the solid(Ds), which has been tabulated in detail.展开更多
The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on20...The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.展开更多
The strain dependent characteristics of hard coatings make the vibration analysis of hard-coated composite structure become a challenging task. In this study, the modeling and the analysis method of a hard-coated comp...The strain dependent characteristics of hard coatings make the vibration analysis of hard-coated composite structure become a challenging task. In this study, the modeling and the analysis method of a hard-coated composite beam was developed considering the strain dependent characteristics of coating material. Firstly, based on analyzing the properties of hard-coating material, a high order polynomial was adopted to characterize the strain dependent characteristics of coating materials. Then, the analytical model of a hard-coated composite beam was created by the energy method. Next, using the numerical method to solve the vibration response and the resonance frequencies of the composite beam, a specific calculation flow was also proposed. Finally,a cantilever beam coated with Mg O ＋ Al2_O_3 hard coating was chosen as the study case; under different excitation levels, the resonance region responses and the resonance frequencies of the composite beam were calculated using the proposed method. The calculation results were compared with the experiment and the linear calculation, and the correctness of the created model was verified. The study shows that compared with the general linear calculation, the proposed method can still maintain an acceptable precision when the excitation level is larger.展开更多
Tendril-bearing climbing plants must recur to the tendril helices with chiral perversion or dual chirality for climbing and to obtain sun exposure. Despite researchers' prolonged fascination with climbing tendrils...Tendril-bearing climbing plants must recur to the tendril helices with chiral perversion or dual chirality for climbing and to obtain sun exposure. Despite researchers' prolonged fascination with climbing tendrils since Darwin's time and even earlier, why the soft and slender tendrils can bear heavy loads such as the self-weight of a plant or additional load caused by rain remains elusive. In this paper, we take towel gourd tendrils as an example and investigate the macroscopic and microscopic mechanical behaviors of tendrils through experiments and simulations. Our study indicates that the tendril filament exhibits rubber-like hyperelastic behaviors and can particularly endure large elongation, which is mainly attributed to the superelasticity of the cellulose fibril helix contained in the cell wall. Combination of the tendril helical structure with dual chirality or chiral perversion at a macroscale and a cellulose filament helix at a subcellular level creates superior elasticity for biological species relying on support and climbing. This study provides deep insight into the structure-property relationship of climbing tendrils, and the relationship is useful for the bioinspired design of composite systems with superior elasticity.展开更多
Composites featuring negative permittivity have garnered significant attention for their potential in novel capacitance designs,coil-less electrical inductors,and electromagnetic shielding applications.In this study,w...Composites featuring negative permittivity have garnered significant attention for their potential in novel capacitance designs,coil-less electrical inductors,and electromagnetic shielding applications.In this study,we prepared polyvinylidene fluoride(PVDF)matrix composites filled with ZrO_(2)/C nanoparticles de-rived from metal-organic frameworks(MOFs)via a hot-pressing method.With an increase in the ZrO_(2)/C content to 30 wt.%,electrical percolation was observed,accompanied by a transition mechanism from hopping conduction to metal-like conduction.This enabled the realization of ZrO_(2)/C/PVDF composites with tailorable negative permittivity properties,attributed to the plasmonic oscillation of free electrons in the composites beyond the percolation threshold(30 wt.%).Furthermore,the permittivity transition along to a shift in the electrical behavior of the percolative composites from capacitive to inductive.We explored the regulatory mechanism behind the negative permittivity in this random composite system,and our findings highlight the potential of these tunable negative permittivity media as promising candi-dates for diverse electromagnetic applications.展开更多
Tumor cells escape host immune surveillance bydown-regulation of MHC and/or co-stimulatorymolecules.Anti-tumor immune responses are mediated primarily by T cells.A deficiency in either MHC or co-stimulatory molecules ...Tumor cells escape host immune surveillance bydown-regulation of MHC and/or co-stimulatorymolecules.Anti-tumor immune responses are mediated primarily by T cells.A deficiency in either MHC or co-stimulatory molecules on tumor cells is associated with a failure to induce anti-tumor immunity.展开更多
B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,i...B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder surface.In this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al composites.It was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high temperature.As the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased significantly.The finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional B_(4)C/Al composites.展开更多
This study investigates the influence of varying rolling reduction on the evolution of microstructure and mechanical properties of Mg–10Gd(in wt%)alloys by caliber rolling(CR).By increasing the rolling reduction from...This study investigates the influence of varying rolling reduction on the evolution of microstructure and mechanical properties of Mg–10Gd(in wt%)alloys by caliber rolling(CR).By increasing the rolling reduction from 45%to 65%,a uniform bimodal structure is obtained in which coarse grains(CGs)larger than 10μm are surrounded by fine grains(FGs).The Mg–Gd alloy subjected to 65%reduction exhibits superior mechanical properties,i.e.yield strength(YS)of~424 MPa,ultimate tensile strength(UTS)of~500 MPa and elongation(El.)of~3.3%.The synergistic improvement in strength and ductility is primarily attributed to the combined effects of low-angle grain boundary(LAGB)strengthening,precipitation strengthening,and the coordinated deformation exhibited by the bimodal structure.In addition,caliber rolling also provides a novel approach for the design of Mg alloys with uniform bimodal structures that exhibit both high strength and ductility.展开更多
Small-angle X-ray scattering(SAXS)using synchrotron radiation as X-ray source has been employed to charactcizc the microscopic structrure of organo-modified mesoporous molecular sieves(organo-MSU-X)prepared by a one-p...Small-angle X-ray scattering(SAXS)using synchrotron radiation as X-ray source has been employed to charactcizc the microscopic structrure of organo-modified mesoporous molecular sieves(organo-MSU-X)prepared by a one-pot template-directed synthesis.It is shown that the SAXS profile is hardly constant with Porod’s law showing a negative slope,i.e.,negative deviation.This suggests that there is diffuse interfacial layer located between the pores and the matrix.This suggests that the organic groups remain covalently linked to the matrix,as indicated by ^29SiCP MAS NMR and FT-IR.The average thickness of the interfacial layer was found to be about 1nm for each of the three samples with different kinds and the same amounts(20? of organic groups.This kind of material has also been proved to possess both surface and mass fractal structure of the amophous porous silica materials.2001 Elsevier Science B.V.All rights reserved.展开更多
In this work,firstly,based on effectivemulti-scale numerical modeling and simulations,three possible mechanisms of piezoresistivity inpolymer nanocomposites with carbon nanofiller(CNF,e.g.,carbon nanotube and carbon n...In this work,firstly,based on effectivemulti-scale numerical modeling and simulations,three possible mechanisms of piezoresistivity inpolymer nanocomposites with carbon nanofiller(CNF,e.g.,carbon nanotube and carbon nanofi-ber),i.e.,1)variation of conductive networksformed by CNFs;2)tunneling resistance changein neighboring CNFs and 3)piezoresistivity展开更多
基金supported by the National Key Research and Development Program of Chinathe National Natural Science Foundation of China (Grant Nos.2024YFA1408000,12474097,and2023YFA1406001)+2 种基金the Guangdong Provincial Quantum Science Strategic Initiative (Grant No.GDZX2201001)the Center for Computational Science and Engineering at Southern University of Science and Technology,the Major Science and Technology Infrastructure Project of Material Genome Big-science Facilities Platform supported by Municipal Development and Reform Commission of Shenzhen(for J.L.Z.and Y.L.)the Chinese funding sources applied via HPSTAR。
文摘The magnetic properties and Kondo effect in Ce3TiBi5 with a quasi-one-dimensional structure were investigated using in situ high-pressure resistivity measurements up to 48 GPa.At ambient pressure,Ce_(3)TiBi_(5) undergoes an antiferromagnetic(AFM)transition at T_(N)∼5 K.Under high pressures within 8.9 GPa,we find that Kondo scattering contributes differently to the high-temperature resistance,R(T),depending on the applied current direction,demonstrating a significantly anisotropic Kondo effect.The complete P–T phase diagram has been constructed,in which the pressure dependence of T_(N) exhibits a dome-like shape.The AFM order remains robust under pressure,even when the coherence temperature T^(*) far exceeds 300 K.We attribute the observed anisotropic Kondo effect and the robust AFM to the underlying anisotropy in electronic hybridization under high pressure.
基金supported by the National Natural Science Foundation of China(Nos.12072327,12302497)the National Outstanding Youth Science Fund Project(No.12125206)+2 种基金Major International Joint Research Project(No.W2411003)Fund raised by China Electric Power Research Institute(No.GC80-21-002)CAS Project for Young Scientists in Basic Research(YSBR-096).
文摘The development and deployment of aluminum conductor have been significantly hampered by the contradiction of yield strength,uniform elongation,and electrical conductivity.Herein,we successfully fabricated a pure aluminum(Al)clad aluminum alloy(AA)rod with hierarchical compositions and microstructures.The proposed pure Al clad AA rod showcases an optimized combination of yield strength,uniform elongation,and electrical conductivity,i.e.,easing the restriction on improving yield strength,uniform elongation,and electrical conductivity.Compared to existing experiments,uniform elongation improved fourfold,while yield strength increased by 13%and electrical conductivity improved by 2%in terms of the international annealed copper standard(IACS).Microstructural characterizations and theoretical analyses revealed that the optimal performance of the Al clad AA arose from low-density low-angle grain boundaries(LAGBs)in the outer Al and high-density LAGBs with nanoscale precipitations in the inner AA.Our findings offer a compelling strategy for fabricating high-performance aluminum conductors,thereby laying a solid technical foundation for their wide application in power delivery systems.
基金support of the National Natural Science Foundation of China(Grant Nos.52171056 and 52203385)the Joint Funds of the National Natural Science Foundation of China(Grant Nos.U2341255 and U22A20114)+1 种基金the Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220225)the IMR Innovation Fund(Grant No.2021-ZD02).
文摘In dry storage,spent fuel is typically stored in casks constructed from neutron absorbing materials(NAMs).The(B_(4)C+Al_(2)O_(3))/Al composite,which incorporates in-situ amorphous Al_(2)O_(3)(am-Al_(2)O_(3))formed on fine aluminum powder as a reinforcing phase,can serve as an integrated structural and functional NAM for dry storage applications.Welding is crucial in the fabrication of these casks.In this study,friction stir welding was performed on(B_(4)C+Al_(2)O_(3))/Al composite sheets at a welding speed of 50 mm/min and rotation rates ranging from 500 to 1000 r/min.The microstructure of the weld joints was analyzed,and the intrinsic relationship between fracture behavior and microstructure was elucidated.Results showed that defect-free joints were achieved at rotation rates of 500 and 750 r/min,while tunnel defects were observed at 1000 r/min.The ultimate tensile strength of the joint welded at 500 r/min was 205.7 MPa,with a strength efficiency of 82%.Microstructural analysis revealed that the grains within the nugget zones(NZs)coarsened and the Al_(2)O_(3)network was disrupted due to the welding thermo-mechanical effect,resulting in softening within the NZs.Fracture locations for all three joints were consistently observed at the NZ boundary on the advancing side(AS).Finite element simulations confirmed that cracks propagated along the NZ boundary on the AS,where stress concentration occurred during tensile testing.
基金the National Natural Science Foundation of China(Grant 11402089)the Natural Science Foundation of Hebei Province of China(Grant A2017502015).The financial contributions are gratefully acknowledged.
文摘Theoretical analysis and numerical simulation methods were used to study the in-plane crushing behavior of single-cell structures and regular and composite honeycombs.Square,hexagonal,and circular honeycombs were selected as honeycomb layers to establish composite honeycomb models in the form of composite structures and realize the complementary advantages of honeycombs with type Ⅰ and type Ⅱ structures.The effects of honeycomb layer arrangement,plastic collapse strength,relative density,and crushing velocity on the deformation mode,plateau stress,load uniformity,and energy absorption performance of the composite honeycombs were mainly considered.A semi-empirical formula for plateau stress and energy absorption rate per unit mass for the composite honeycombs was developed.The results showed that the arrangement mode of honeycomb layers is an important factor that affects their mechanical properties.Appropriately selecting the arrangement of honeycomb layers and the proportion of honeycomb layers with different structures in a composite honeycomb can effectively improve its load uniformity and control the magnitude of plateau stress and energy absorption capacity.
文摘In 2018,the STAR collaboration collected data from^(96)_(44)Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr at√^(S)NN=200 Ge V to search for the presence of the chiral magnetic effect in collisions of nuclei.The isobar collision species alternated frequently between 9644 Ru+^(96)_(44)Ru and^(96)_(40)Zr+^(96)_(40)Zr.In order to conduct blind analyses of studies related to the chiral magnetic effect in these isobar data,STAR developed a three-step blind analysis procedure.Analysts are initially provided a"reference sample"of data,comprised of a mix of events from the two species,the order of which respects time-dependent changes in run conditions.After tuning analysis codes and performing time-dependent quality assurance on the reference sample,analysts are provided a species-blind sample suitable for calculating efficiencies and corrections for individual≈30-min data-taking runs.For this sample,species-specific information is disguised,but individual output files contain data from a single isobar species.Only run-by-run corrections and code alteration subsequent to these corrections are allowed at this stage.Following these modifications,the"frozen"code is passed over the fully un-blind data,completing the blind analysis.As a check of the feasibility of the blind analysis procedure,analysts completed a"mock data challenge,"analyzing data from Au+Au collisions at√^(S)NN=27 Ge V,collected in 2018.The Au+Au data were prepared in the same manner intended for the isobar blind data.The details of the blind analysis procedure and results from the mock data challenge are presented.
基金the National Natural Science Foundation of China(11872353,91852102)the Natural Science Foundation of Zhejiang Province(LZ22A020004)。
文摘With the prevalence of COVID-19,the phenomenon of viruses spreading through aerosols has become a focus of attention.Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks,which greatly increases the risk of COVID-19 transmission.Therefore,the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated.In this study,a numerical simulation of coughing at dining tables under two conditions was performed,namely the presence and absence of protective partitions,and the evaporation and condensation of aerosol droplets in the air were examined.By using the numerical method,we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets.The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed.We demonstrated how respiratory droplets spread through coughing and how these droplets affect others.Finally,we proposed a design for a dining table partition that minimizes the transmission of COVID-19.
基金funding from the Australian Research Council(ARC) via DP180103205。
文摘It has been a central task of solidification research to predict solute microsegregation. Apart from the Lever rule and the Scheil-Gulliver equation, which concern two extreme cases, a long list of microsegregation models has been proposed. However, the use of these models often requires essential experimental input information, e.g., the secondary dendrite arm spacing(λ), cooling rate( ˙T) or actual solidification range(△T). This requirement disables these models for alloy solidification with no measured values for λ,˙T and △T. Furthermore, not all of these required experimental data are easily obtainable. It is therefore highly desirable to have an easy-to-apply predictive model that is independent of experimental input,akin to the Lever rule or Scheil-Gulliver model. Gong, Chen, and co-workers have recently proposed such a model, referred to as the Gong-Chen model, by averaging the solid fractions(f_(s)) of the Lever rule and Scheil-Gulliver model as the actual solid fraction. We provide a systematic assessment of this model versus established solidification microsegregation models and address a latent deficiency of the model, i.e.,it allows the Lever rule solid fraction fsto be greater than one(f_(s)> 1). It is shown that the Gong-Chen model can serve as a generic model for alloy solidification until fsreaches about 0.9, beyond which(f_(s)> 0.9) its applicability is dictated by both the equilibrium solute partition coefcient(k) and the solute diffusion coefcient in the solid(Ds), which has been tabulated in detail.
基金supported by the Einstein Probe project,a mission in the Strategic Priority Program on Space Science of CAS(grant Nos.XDA15310000,XDA15052100)in part been supported by the European Union’s Horizon 2020 Program under the AHEAD2020 project(grant No.871158).
文摘The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.
基金supported by the National Natural Science Foundation of China(Grant 51375079)the Fundamental Research Funds for the Central Universities of China(Grant N140301001)
文摘The strain dependent characteristics of hard coatings make the vibration analysis of hard-coated composite structure become a challenging task. In this study, the modeling and the analysis method of a hard-coated composite beam was developed considering the strain dependent characteristics of coating material. Firstly, based on analyzing the properties of hard-coating material, a high order polynomial was adopted to characterize the strain dependent characteristics of coating materials. Then, the analytical model of a hard-coated composite beam was created by the energy method. Next, using the numerical method to solve the vibration response and the resonance frequencies of the composite beam, a specific calculation flow was also proposed. Finally,a cantilever beam coated with Mg O ＋ Al2_O_3 hard coating was chosen as the study case; under different excitation levels, the resonance region responses and the resonance frequencies of the composite beam were calculated using the proposed method. The calculation results were compared with the experiment and the linear calculation, and the correctness of the created model was verified. The study shows that compared with the general linear calculation, the proposed method can still maintain an acceptable precision when the excitation level is larger.
基金the National Natural Science Foundation of China (Grants 11872273, 11472191, 11602163, and 11672297)the Major Program of the National Science Foundation of China (Grant 11890683)+1 种基金the Opening Fund of State Key Laboratory of Nonlinear Mechanicsthe Australian Endeavour Research Fellowship.
文摘Tendril-bearing climbing plants must recur to the tendril helices with chiral perversion or dual chirality for climbing and to obtain sun exposure. Despite researchers' prolonged fascination with climbing tendrils since Darwin's time and even earlier, why the soft and slender tendrils can bear heavy loads such as the self-weight of a plant or additional load caused by rain remains elusive. In this paper, we take towel gourd tendrils as an example and investigate the macroscopic and microscopic mechanical behaviors of tendrils through experiments and simulations. Our study indicates that the tendril filament exhibits rubber-like hyperelastic behaviors and can particularly endure large elongation, which is mainly attributed to the superelasticity of the cellulose fibril helix contained in the cell wall. Combination of the tendril helical structure with dual chirality or chiral perversion at a macroscale and a cellulose filament helix at a subcellular level creates superior elasticity for biological species relying on support and climbing. This study provides deep insight into the structure-property relationship of climbing tendrils, and the relationship is useful for the bioinspired design of composite systems with superior elasticity.
基金National Natural Science Foundation of China(No.52272117)National Key Research and Development Program of China(Nos.2022YFB3505104,2022YFB3706604)National Youth Fund(No.52207239).
文摘Composites featuring negative permittivity have garnered significant attention for their potential in novel capacitance designs,coil-less electrical inductors,and electromagnetic shielding applications.In this study,we prepared polyvinylidene fluoride(PVDF)matrix composites filled with ZrO_(2)/C nanoparticles de-rived from metal-organic frameworks(MOFs)via a hot-pressing method.With an increase in the ZrO_(2)/C content to 30 wt.%,electrical percolation was observed,accompanied by a transition mechanism from hopping conduction to metal-like conduction.This enabled the realization of ZrO_(2)/C/PVDF composites with tailorable negative permittivity properties,attributed to the plasmonic oscillation of free electrons in the composites beyond the percolation threshold(30 wt.%).Furthermore,the permittivity transition along to a shift in the electrical behavior of the percolative composites from capacitive to inductive.We explored the regulatory mechanism behind the negative permittivity in this random composite system,and our findings highlight the potential of these tunable negative permittivity media as promising candi-dates for diverse electromagnetic applications.
文摘Tumor cells escape host immune surveillance bydown-regulation of MHC and/or co-stimulatorymolecules.Anti-tumor immune responses are mediated primarily by T cells.A deficiency in either MHC or co-stimulatory molecules on tumor cells is associated with a failure to induce anti-tumor immunity.
基金supported by the National Key R&D Program of China(Grant No.2023YFB3710601)the National Natural Science Foundation of China(Grant Nos.52203385 and 52171056)+2 种基金the CNNC Science Fund for Talented Young Scholars,the Institute of Metal Research(IMR)Innovation Fund(Grant No.2021-ZD02)the Natural Science Foundation of Liaoning Province(Grant No.2022-BS-009)Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220225).
文摘B_(4)C/Al composites are widely utilized as neutron absorbing materials for the storage and transportation of spent nuclear fuel.In order to improve the high-temperature mechanical properties of B_(4)C/Al composites,in-situ nano-Al_(2)O_(3)was introduced utilizing oxide on Al powder surface.In this study,the Al_(2)O_(3)content was adjusted by utilizing spheroid Al powder with varying diameters,thereby investigating the impact of Al_(2)O_(3)content on the tensile properties of(B_(4)C+Al_(2)O_(3))/Al composites.It was found that the pinning effect of Al_(2)O_(3)on the grain boundaries could hinder the recovery of dislocations and lead to dislocation accumulation at high temperature.As the result,with the increase in Al_(2)O_(3)content and the decrease in grain size,the high-temperature strength of the composites increased significantly.The finest Al powder used in this investigation had a diameter of 1.4μm,whereas the resultant composite exhibited a maximum strength of 251 MPa at room temperature and 133 MPa at 350℃,surpassing that of traditional B_(4)C/Al composites.
基金financial support from the National Natural Science Foundation of China(51701060,52001106)Hebei Province(E2022202158),the foundation of the Strengthening Program(2019-JCJQ-142-00)。
文摘This study investigates the influence of varying rolling reduction on the evolution of microstructure and mechanical properties of Mg–10Gd(in wt%)alloys by caliber rolling(CR).By increasing the rolling reduction from 45%to 65%,a uniform bimodal structure is obtained in which coarse grains(CGs)larger than 10μm are surrounded by fine grains(FGs).The Mg–Gd alloy subjected to 65%reduction exhibits superior mechanical properties,i.e.yield strength(YS)of~424 MPa,ultimate tensile strength(UTS)of~500 MPa and elongation(El.)of~3.3%.The synergistic improvement in strength and ductility is primarily attributed to the combined effects of low-angle grain boundary(LAGB)strengthening,precipitation strengthening,and the coordinated deformation exhibited by the bimodal structure.In addition,caliber rolling also provides a novel approach for the design of Mg alloys with uniform bimodal structures that exhibit both high strength and ductility.
文摘Small-angle X-ray scattering(SAXS)using synchrotron radiation as X-ray source has been employed to charactcizc the microscopic structrure of organo-modified mesoporous molecular sieves(organo-MSU-X)prepared by a one-pot template-directed synthesis.It is shown that the SAXS profile is hardly constant with Porod’s law showing a negative slope,i.e.,negative deviation.This suggests that there is diffuse interfacial layer located between the pores and the matrix.This suggests that the organic groups remain covalently linked to the matrix,as indicated by ^29SiCP MAS NMR and FT-IR.The average thickness of the interfacial layer was found to be about 1nm for each of the three samples with different kinds and the same amounts(20? of organic groups.This kind of material has also been proved to possess both surface and mass fractal structure of the amophous porous silica materials.2001 Elsevier Science B.V.All rights reserved.
文摘In this work,firstly,based on effectivemulti-scale numerical modeling and simulations,three possible mechanisms of piezoresistivity inpolymer nanocomposites with carbon nanofiller(CNF,e.g.,carbon nanotube and carbon nanofi-ber),i.e.,1)variation of conductive networksformed by CNFs;2)tunneling resistance changein neighboring CNFs and 3)piezoresistivity
