Understanding the structure-property relationship and the mechanisms by which catalysts promote polysulfide conversion is crucial for the rational design of room-temperature sodium-sulfur(RT Na-S)battery catalysts.Her...Understanding the structure-property relationship and the mechanisms by which catalysts promote polysulfide conversion is crucial for the rational design of room-temperature sodium-sulfur(RT Na-S)battery catalysts.Herein,we systematically investigate Fe-,Co-,and Ni-incorporated Mo_(2)C as catalysts for RT Na-S battery to elucidate the intrinsic correlation between the d band center of Mo in Mo_(2)C and its catalytic activity.Combining experimental and theoretical analysis revealed that Ni-substituted Mo_(2)C elevates the d band center while significantly reducing antibonding orbitals(π^(*))occupancy compared to Fe-substituted Mo_(2)C and Co-substituted Mo_(2)C counterparts.This electronic restruction enhances d-p hybridization at the Mo-S interface,which strengthens sodium polysulfides adsorption energy and enhances charge transfer,thereby steering sulfur redox pathways toward thermodynamically favorable configurations.Our findings elucidate the intricate interplay between the electronic structure and catalytic activity of Mo_(2)C,advancing a novel perspective for the rational design of RT Na-S battery catalysts through tailored modulation of antibonding orbital occupancy.展开更多
The elastic wave propagation phenomena in two-dimensional periodic beam lattices are studied by using the Bloch wave transform. The numerical modeling is applied to the hexagonal and the rectangular beam lattices, in ...The elastic wave propagation phenomena in two-dimensional periodic beam lattices are studied by using the Bloch wave transform. The numerical modeling is applied to the hexagonal and the rectangular beam lattices, in which, both the in-plane （with respect to the lattice plane） and out-of-plane waves are considered. The dispersion relations are obtained by calculating the Bloch eigenfrequencies and eigenmodes. The frequency bandgaps are observed and the influence of the elastic and geometric properties of the primitive cell on the bandgaps is studied. By analyzing the phase and the group velocities of the Bloch wave modes, the anisotropic behaviors and the dispersive characteristics of the hexagonal beam lattice with respect to the wave prop- agation are highlighted in high frequency domains. One im- portant result presented herein is the comparison between the first Bloch wave modes to the membrane and bend- ing/transverse shear wave modes of the classical equivalent homogenized orthotropic plate model of the hexagonal beam lattice. It is shown that, in low frequency ranges, the homog- enized plate model can correctly represent both the in-plane and out-of-plane dynamic behaviors of the beam lattice, its frequency validity domain can be precisely evaluated thanks to the Bloch modal analysis. As another important and original result, we have highlighted the existence of the retro- propagating Bloch wave modes with a negative group veloc- ity, and of the corresponding ＂retro-propagating＂ frequency bands.展开更多
We present a micro-gravity experimental study of intermediate number density vibro-fluidized inelastic spheres in a rectangular container.Local velocity distributions are investigated,and are found to deviate measurab...We present a micro-gravity experimental study of intermediate number density vibro-fluidized inelastic spheres in a rectangular container.Local velocity distributions are investigated,and are found to deviate measurably from a symmetric distribution for the velocity component of the vibrating direction when dividing particles along the vibration direction into several bins.This feature does not exist in the molecular gas.We further study the hydrodynamic profiles of pressures p and temperatures T in positive and negative components,such as p+y and p-y and T+y and T-y,in accordance with the sign of velocity components of the vibrating direction.Along vibration direction,granular media are found to be not only inhomogeneous and anisotropic,but also different greatly in positive and negative components.Energy equipartition breaks down in this case.展开更多
Sclareol,an antifungal specialized metabolite produced by clary sage,Salvia sclarea,is the starting plant natural molecule used for the hemisynthesis of the perfume ingredient ambroxide.Sclareol is mainly produced in ...Sclareol,an antifungal specialized metabolite produced by clary sage,Salvia sclarea,is the starting plant natural molecule used for the hemisynthesis of the perfume ingredient ambroxide.Sclareol is mainly produced in clary sage flower calyces;however,the cellular localization of the sclareol biosynthesis remains unknown.To elucidate the site of sclareol biosynthesis,we analyzed its spatial distribution in the clary sage calyx epidermis using laser desorption/ionization mass spectrometry imaging(LDI–FTICR-MSI)and investigated the expression profile of sclareol biosynthesis genes in isolated glandular trichomes(GTs).We showed that sclareol specifically accumulates in GTs’gland cells in which sclareol biosynthesis genes are strongly expressed.We next isolated a glabrous beardless mutant and demonstrate that more than 90%of the sclareol is produced by the large capitate GTs.Feeding experiments,using 1-13 C-glucose,and specific enzyme inhibitors further revealed that the methylerythritol-phosphate(MEP)biosynthetic pathway is the main source of isopentenyl diphosphate(IPP)precursor used for the biosynthesis of sclareol.Our findings demonstrate that sclareol is an MEP-derived diterpene produced by large capitate GTs in clary sage emphasing the role of GTs as biofactories dedicated to the production of specialized metabolites.展开更多
A 3-D molecular dynamics simulation of a bi-disperse vibro-fluidized granular gas in a cyclic three-compartment cell is performed.A cluster of particles is randomly found in one of the compartments.Lohse's flux mo...A 3-D molecular dynamics simulation of a bi-disperse vibro-fluidized granular gas in a cyclic three-compartment cell is performed.A cluster of particles is randomly found in one of the compartments.Lohse's flux model is modified to incorporate inelastic particle-boundary colBsions.This model predicts that periodically there is clustering in each compartment.It is then found that if the model is further modified to incorporate Gaussian white noise,it correctly predicts the non-sequential clustering behavior confirming that there is no chaotic behavior.展开更多
The clustering behavior of a mono-disperse granular gas is experimentally studied in an asymmetric two-compartment setup. Unlike the random clustering in either compartment in the case of symmetric configuration when ...The clustering behavior of a mono-disperse granular gas is experimentally studied in an asymmetric two-compartment setup. Unlike the random clustering in either compartment in the case of symmetric configuration when lowering the shaking strength to below a critical value, the directed clustering is observed, which corresponds to an imperfect pitchfork bifurcation. Numerical solutions of the flux equation using a modified simple flux function show qualitative agreements with the experimental results. The potential application of this asymmetric structure is discussed.展开更多
The dielectric property and percolated behaviour of polymer matrix composites largely depend on the morphology of conductive fillers and external stimulations especially when the composites are processed by melting bl...The dielectric property and percolated behaviour of polymer matrix composites largely depend on the morphology of conductive fillers and external stimulations especially when the composites are processed by melting blending and extrusion-injection way.In this study,the poly(methyl methacrylate)(PMMA)matrix composites incorporated by two kinds of graphene nanoplatelets(GNP),G5 and G150 with different aspect ratios(the ratio of diameter and thickness)are prepared to study the influence of GNP morphology on the dielectric performances close to percolation threshold(f_(c)).After annealing at glass transition temperature(T_(g))for 1 h,the dielectric permittivities of PMMA/G5 and PMMA/G150 near fc increase 43 and 38%,respectively,while the dielectric loss change little.This improvement on the dielectric property is possibly attributed to the slight change of the distance between adjacent GNPs after annealing at T_(g)which enables to arouse stronger polarisation by tunnelling effect.展开更多
Selective oxidation of Fe-Mn alloys was characterizied through X-ray photoelectron spectroscopy and scanning/transmission electron microscopy during industrial continuous annealing(in an atmosphere of N_(2)-5 vol.%H_(...Selective oxidation of Fe-Mn alloys was characterizied through X-ray photoelectron spectroscopy and scanning/transmission electron microscopy during industrial continuous annealing(in an atmosphere of N_(2)-5 vol.%H_(2) with traces of water at 800℃).After annealing,only MnO oxides are formed on and below the surface and few iron oxides appear on the top surface due to oxidation of ambient air or the formation of FeO-MnO solid solutions.Mn concentration profiles exhibit typical selective oxidation and show similar features.Mn concentration first increases to a peak value at a depth of 5-10 nm from surface,and then decreases to the minimum at the oxidation front,following with a floating up and down to bulk composition.According to XPS spectra and Mn concentration profiles as a function of depth,the annealed alloy surfaces can be divided into four zones:ambient air contaminated zone,MnO enrichment zone(external and internal oxidation coexisting here),Mn depletion zone and bulk composition zone.Mn concentration reaches a minimum value at the oxidation front,whose position is deeper with annealing temperature and time increasing.The value of Mn diffusion coefficient in ferrite estimated using diffusion flux at the oxidation front is 2.9×10^(-15)m^(2)s^(-1) at 800℃,which is slightly greater than that in literature.展开更多
基金supported by the National Natural Science Foundation of China(No.52372224 and 52072299)the Major Project of Shaanxi Coal Joint Fund of Shaanxi.Provincial Science and Technology Department(No.2019JLZ-07)。
文摘Understanding the structure-property relationship and the mechanisms by which catalysts promote polysulfide conversion is crucial for the rational design of room-temperature sodium-sulfur(RT Na-S)battery catalysts.Herein,we systematically investigate Fe-,Co-,and Ni-incorporated Mo_(2)C as catalysts for RT Na-S battery to elucidate the intrinsic correlation between the d band center of Mo in Mo_(2)C and its catalytic activity.Combining experimental and theoretical analysis revealed that Ni-substituted Mo_(2)C elevates the d band center while significantly reducing antibonding orbitals(π^(*))occupancy compared to Fe-substituted Mo_(2)C and Co-substituted Mo_(2)C counterparts.This electronic restruction enhances d-p hybridization at the Mo-S interface,which strengthens sodium polysulfides adsorption energy and enhances charge transfer,thereby steering sulfur redox pathways toward thermodynamically favorable configurations.Our findings elucidate the intricate interplay between the electronic structure and catalytic activity of Mo_(2)C,advancing a novel perspective for the rational design of RT Na-S battery catalysts through tailored modulation of antibonding orbital occupancy.
文摘The elastic wave propagation phenomena in two-dimensional periodic beam lattices are studied by using the Bloch wave transform. The numerical modeling is applied to the hexagonal and the rectangular beam lattices, in which, both the in-plane （with respect to the lattice plane） and out-of-plane waves are considered. The dispersion relations are obtained by calculating the Bloch eigenfrequencies and eigenmodes. The frequency bandgaps are observed and the influence of the elastic and geometric properties of the primitive cell on the bandgaps is studied. By analyzing the phase and the group velocities of the Bloch wave modes, the anisotropic behaviors and the dispersive characteristics of the hexagonal beam lattice with respect to the wave prop- agation are highlighted in high frequency domains. One im- portant result presented herein is the comparison between the first Bloch wave modes to the membrane and bend- ing/transverse shear wave modes of the classical equivalent homogenized orthotropic plate model of the hexagonal beam lattice. It is shown that, in low frequency ranges, the homog- enized plate model can correctly represent both the in-plane and out-of-plane dynamic behaviors of the beam lattice, its frequency validity domain can be precisely evaluated thanks to the Bloch modal analysis. As another important and original result, we have highlighted the existence of the retro- propagating Bloch wave modes with a negative group veloc- ity, and of the corresponding ＂retro-propagating＂ frequency bands.
基金Supported by the Knowledge Innovation Project of the Chinese Academy of Sciences under Grant No KJCX2-YW-L08the National Natural Science Foundation of China under Grant No 10720101074 and 11034010the Special Fund for Earthquake Research of China under Grant No 201208011,and CNRS,CNES Special Funds.
文摘We present a micro-gravity experimental study of intermediate number density vibro-fluidized inelastic spheres in a rectangular container.Local velocity distributions are investigated,and are found to deviate measurably from a symmetric distribution for the velocity component of the vibrating direction when dividing particles along the vibration direction into several bins.This feature does not exist in the molecular gas.We further study the hydrodynamic profiles of pressures p and temperatures T in positive and negative components,such as p+y and p-y and T+y and T-y,in accordance with the sign of velocity components of the vibrating direction.Along vibration direction,granular media are found to be not only inhomogeneous and anisotropic,but also different greatly in positive and negative components.Energy equipartition breaks down in this case.
基金This work was supported by the Plant Biology and Breeding department in INRA,the grants Program LabEx Saclay Plant Sciences-SPS(ANR-10-LABX-40-SPS)Financial support from the National FT-ICR network(FR 3624 CNRS)is gratefully acknowledged.
文摘Sclareol,an antifungal specialized metabolite produced by clary sage,Salvia sclarea,is the starting plant natural molecule used for the hemisynthesis of the perfume ingredient ambroxide.Sclareol is mainly produced in clary sage flower calyces;however,the cellular localization of the sclareol biosynthesis remains unknown.To elucidate the site of sclareol biosynthesis,we analyzed its spatial distribution in the clary sage calyx epidermis using laser desorption/ionization mass spectrometry imaging(LDI–FTICR-MSI)and investigated the expression profile of sclareol biosynthesis genes in isolated glandular trichomes(GTs).We showed that sclareol specifically accumulates in GTs’gland cells in which sclareol biosynthesis genes are strongly expressed.We next isolated a glabrous beardless mutant and demonstrate that more than 90%of the sclareol is produced by the large capitate GTs.Feeding experiments,using 1-13 C-glucose,and specific enzyme inhibitors further revealed that the methylerythritol-phosphate(MEP)biosynthetic pathway is the main source of isopentenyl diphosphate(IPP)precursor used for the biosynthesis of sclareol.Our findings demonstrate that sclareol is an MEP-derived diterpene produced by large capitate GTs in clary sage emphasing the role of GTs as biofactories dedicated to the production of specialized metabolites.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10720101074 and 10874209the Knowledge Innovation Program of Chinese Academy of Sciences under Grant No KJCX2-YW-L08,CSSAR and CNES.
文摘A 3-D molecular dynamics simulation of a bi-disperse vibro-fluidized granular gas in a cyclic three-compartment cell is performed.A cluster of particles is randomly found in one of the compartments.Lohse's flux model is modified to incorporate inelastic particle-boundary colBsions.This model predicts that periodically there is clustering in each compartment.It is then found that if the model is further modified to incorporate Gaussian white noise,it correctly predicts the non-sequential clustering behavior confirming that there is no chaotic behavior.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11034010 and 11274354)the Chinese Academy of Sciences "Strategic Priority Research Program - SJ-10" (Grant No. XDA04020200)the Special Fund for Earthquake Research of China (Grant No. 201208011)
文摘The clustering behavior of a mono-disperse granular gas is experimentally studied in an asymmetric two-compartment setup. Unlike the random clustering in either compartment in the case of symmetric configuration when lowering the shaking strength to below a critical value, the directed clustering is observed, which corresponds to an imperfect pitchfork bifurcation. Numerical solutions of the flux equation using a modified simple flux function show qualitative agreements with the experimental results. The potential application of this asymmetric structure is discussed.
文摘The dielectric property and percolated behaviour of polymer matrix composites largely depend on the morphology of conductive fillers and external stimulations especially when the composites are processed by melting blending and extrusion-injection way.In this study,the poly(methyl methacrylate)(PMMA)matrix composites incorporated by two kinds of graphene nanoplatelets(GNP),G5 and G150 with different aspect ratios(the ratio of diameter and thickness)are prepared to study the influence of GNP morphology on the dielectric performances close to percolation threshold(f_(c)).After annealing at glass transition temperature(T_(g))for 1 h,the dielectric permittivities of PMMA/G5 and PMMA/G150 near fc increase 43 and 38%,respectively,while the dielectric loss change little.This improvement on the dielectric property is possibly attributed to the slight change of the distance between adjacent GNPs after annealing at T_(g)which enables to arouse stronger polarisation by tunnelling effect.
基金financially supported by the French"Agence Nationale de la Recherche"through the"Investissements d'avenir"Program(No.ANR-10-EQPX-37 MATMECA)the Chinese"International Exchange Program"(No.YJ20210129)the Shuimu Tsinghua Scholar Program(No.2020SM100)
文摘Selective oxidation of Fe-Mn alloys was characterizied through X-ray photoelectron spectroscopy and scanning/transmission electron microscopy during industrial continuous annealing(in an atmosphere of N_(2)-5 vol.%H_(2) with traces of water at 800℃).After annealing,only MnO oxides are formed on and below the surface and few iron oxides appear on the top surface due to oxidation of ambient air or the formation of FeO-MnO solid solutions.Mn concentration profiles exhibit typical selective oxidation and show similar features.Mn concentration first increases to a peak value at a depth of 5-10 nm from surface,and then decreases to the minimum at the oxidation front,following with a floating up and down to bulk composition.According to XPS spectra and Mn concentration profiles as a function of depth,the annealed alloy surfaces can be divided into four zones:ambient air contaminated zone,MnO enrichment zone(external and internal oxidation coexisting here),Mn depletion zone and bulk composition zone.Mn concentration reaches a minimum value at the oxidation front,whose position is deeper with annealing temperature and time increasing.The value of Mn diffusion coefficient in ferrite estimated using diffusion flux at the oxidation front is 2.9×10^(-15)m^(2)s^(-1) at 800℃,which is slightly greater than that in literature.
