Mitochondria and mitochondria-associated endoplasmic reticulum membrane in neurodegenerative diseases:Mitochondria generate most of the chemical energy needed to power the biochemical reactions of cells,and thus are o...Mitochondria and mitochondria-associated endoplasmic reticulum membrane in neurodegenerative diseases:Mitochondria generate most of the chemical energy needed to power the biochemical reactions of cells,and thus are often referred to as the"powerhouse"of the cell.Nevertheless,this organelle is also involved in a pleth,ora of different cellular functions such as calcium(Ca^(2+))homeostasis,apoptosis,oxidative stress,and several metabolic pathways including oxidative phosphorylation,tricarboxylic acid cycle,andβ-oxidation of fatty acids.展开更多
In order to find closed form solutions of nonintegrable nonlinear ordinary differential equations,numerous tricks have been proposed.The goal of this short review is to explain how a theorem of Eremenko on meromorphic...In order to find closed form solutions of nonintegrable nonlinear ordinary differential equations,numerous tricks have been proposed.The goal of this short review is to explain how a theorem of Eremenko on meromorphic solutions of some nonlinear ODEs together with some classical,19th-century results,can be turned into algorithms(thus avoiding ad hoc assumptions)which provide all(as opposed to some)solutions in a precise class.To illustrate these methods,we present some new such exact solutions,physically relevant.展开更多
A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructur...A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment.Transmission electron microscopyand Rietveld refinement methods were employed.The residual stress and microhardness variations with depth were also characterized.The results show:(1)At the initial stage of deformation,plastic deformation is primarily accommodated through twinning and dislocation slip.(2)As the strain increases,twinning disappears,and dislocations interact to form tangles.Some dislocations annihilate and rearrange into subgrain boundaries,subdividing the original grains into subgrains.(3)With continued dislocation activity,the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization.SSP introduced compressive residual stress(CRS)in the near-surface layer of the material,with the maximum CRS of approximately−1141 MPa observed in the subsurface layer.It also induced work hardening,increasing the surface hardness to approximately 479 HV.However,the surface roughness increases,leading to a slight deterioration in surface quality.展开更多
Estimating bird abundance is key to assess threats,and to prioritize conservation actions.However,few studies focus on this topic,particularly in developing countries,which may hamper conservation efficiency.We used d...Estimating bird abundance is key to assess threats,and to prioritize conservation actions.However,few studies focus on this topic,particularly in developing countries,which may hamper conservation efficiency.We used data collected from Guangdong Province,China,between 2000 and 2020 to estimate bird abundance using MaxEnt modelling.In total,258 bird species were included,with an average density of 1485.2±489.3 ind./km^(2)(range:242.9-4502.2 ind./km^(2)).The highest density occurred in the Pearl River Estuary and on the Leizhou Peninsula.For forest birds,203 species were included with an average density of 1236.2±424.5 ind./km^(2)(143.7-2373.1 ind./km^(2)),and highest densities were found in the Pearl River Estuary and North River regions.For the 55 species of waterbirds,the average density was 249.0±351.8 ind./km^(2)(0.3-2336.1 ind./km^(2)).The total number of birds in Guangdong was estimated to be 2.58×108 ind.(2.24-3.06×10^(8)),with a total number of forest birds estimated to be 2.15×10^(8)ind.(1.90-2.49×10^(8)).The most abundant forest species(>107 individuals)were:Huet's Fulvetta(Alcippe hueti)with 2.84×10^(7)ind.,(range:2.73-2.95×10~7),Light-vented Bulbul(Pycnonotus sinensis)with 1.13×10^(7)ind.(1.07-1.20×10^(7)),Swinhoe's White-eye(Zosterops simplex)with 1.13×10^(7)ind.(1.09-1.17×10^(7)),and Red-whiskered Bulbul(Pycnonotus jocosus)with 1.01×10^(7)ind.(9.66-10.47×10^(6)),The total number of waterbirds in Guangdong was estimated to be 4.37×10^(7)ind.(3.38-5.75×10^(7)).The most abundant waterbirds(>106 individuals)were Black-headed Gull(Chroicocephalus ridibundus)with 6.35×10^(6)ind.(5.48-7.36×10^(6)),Pied Avocet(Recurvirostra avosetta)with 5.56×10^(6)ind.(3.75-8.24×10^(6)),and Little Egret(Egretta garzetta)with 5.01×10^(6)ind.(4.19-6.00×10^(6)).The densities and abundances of the 41 species listed as threatened in IUCN(higher than NT)or Chinese National Protected lists(higher thanⅡ)were evaluated,of which the population sizes of nine species were estimated for the first time in Guangdong.Moreover,all 41 species'average densities significantly declined from 2012 to 2017 in Nanling National Natural Reserve,Guangdong.展开更多
We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The...We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The free-electron contribution is described by the Maynard–Deutsch–Zimmerman formula,and the bound-electron contribution relies on the Bethe formula with corrections,in particular taking into account density and shell effects.The results of the bound-state computation using three different parametric potentials are investigated within the Garbet formalism for the mean excitation energy.The first parametric potential is due to Green,Sellin,and Zachor,the second one was proposed by Yunta,and the third one was introduced by Klapisch in the framework of atomic-structure computations.The results are compared with those of self-consistent average-atom calculations.This approach correctly bridges the limits of neutral and fully ionized matter.展开更多
Recent progress in the design and fabrication of thermal metasurfaces allows a broad control of the properties of light emission,including its polarization state.Stokes polarimetry is a key approach to accurately char...Recent progress in the design and fabrication of thermal metasurfaces allows a broad control of the properties of light emission,including its polarization state.Stokes polarimetry is a key approach to accurately characterize partially polarized light.The quality of a Stokes polarimeter made of retarders and polarizers can be evaluated by use of metrics such as the equally weighted variance or the condition number of the matrix representing the polarimeter.Although specific instrument configurations are used to maximize polarimeter performance at a given wavelength,such optimal solutions are not spectrally robust because of the wave-length dependence of retardance.This becomes an issue in characterizing broadband thermal sources in the infrared.We report a Stokes polarimeter making use of five polarization analysis states and consisting of two simple and common optical elements—a crystalline waveplate and a linear polarizer.We combine this setup with a Fourier transform infrared spectrometer to measure accurately in a single set of acqui-sitions without requiring any spectral filtering,and to measure the polarization state with accuracy over a broad range of wavelengths.Such a Stokes polarimeter allows for close to optimal noise in the data reduc-tion process in the mid-wave infrared spectral range from 2.5 to 5μm.展开更多
In this paper, we study the stability of a class of conformable fractional-order systems using the Lyapunov function. We assume that the nonlinear part of the system satisfies the one-sided Lipschitz condition and the...In this paper, we study the stability of a class of conformable fractional-order systems using the Lyapunov function. We assume that the nonlinear part of the system satisfies the one-sided Lipschitz condition and the quadratic inner-bounded condition. We provide some sufficient conditions that ensure the asymptotic stability of the system. Furthermore, we present the construction of a feedback stabilizing controller for conformable fractional bilinear systems.展开更多
Electrocatalytic C–N coupling technology offers a promising route for green and sustainable urea synthesis.However,this route faces challenges of low urea yield and Faradaic efficiency due to the high dissociation en...Electrocatalytic C–N coupling technology offers a promising route for green and sustainable urea synthesis.However,this route faces challenges of low urea yield and Faradaic efficiency due to the high dissociation energy of atomic bonds in reactants,complex reaction intermediates,high reaction energy barriers,and competing side reactions.As C–N coupling involves the synergistic action of two or more active sites,it is crucial to develop efficient multi-active-site catalysts to address these challenges.This review analyzes the reaction mechanisms of electrocatalytic C–N coupling for urea synthesis and summarizes effective strategies to achieve multi-active-site catalysts,including heteroatom doping,defect engineering,heterojunctions,and diatomic catalysts.Furthermore,based on this analysis,we propose the universal design principles for high-efficiency multi-activesite catalysts.展开更多
Substantial advancements have been achieved in Tunnel Boring Machine(TBM)technology and monitoring systems,yet the presence of missing data impedes accurate analysis and interpretation of TBM monitoring results.This s...Substantial advancements have been achieved in Tunnel Boring Machine(TBM)technology and monitoring systems,yet the presence of missing data impedes accurate analysis and interpretation of TBM monitoring results.This study aims to investigate the issue of missing data in extensive TBM datasets.Through a comprehensive literature review,we analyze the mechanism of missing TBM data and compare different imputation methods,including statistical analysis and machine learning algorithms.We also examine the impact of various missing patterns and rates on the efficacy of these methods.Finally,we propose a dynamic interpolation strategy tailored for TBM engineering sites.The research results show that K-Nearest Neighbors(KNN)and Random Forest(RF)algorithms can achieve good interpolation results;As the missing rate increases,the interpolation effect of different methods will decrease;The interpolation effect of block missing is poor,followed by mixed missing,and the interpolation effect of sporadic missing is the best.On-site application results validate the proposed interpolation strategy's capability to achieve robust missing value interpolation effects,applicable in ML scenarios such as parameter optimization,attitude warning,and pressure prediction.These findings contribute to enhancing the efficiency of TBM missing data processing,offering more effective support for large-scale TBM monitoring datasets.展开更多
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 difference in the microstructure,texture in the stir zone(SZ)of the AZ31(Mg-3 Al-1 Zn,wt.%)alloy after friction stir welding(FSW)and subsequent annealing at 400℃for 1 h was characterized by scanning electron micr...The difference in the microstructure,texture in the stir zone(SZ)of the AZ31(Mg-3 Al-1 Zn,wt.%)alloy after friction stir welding(FSW)and subsequent annealing at 400℃for 1 h was characterized by scanning electron microscopy(SEM)with electron backscatter diffraction(EBSD)measurements at the surface and core regions.The findings indicate that FSW produced grain refinement where the mean grain size decreases from 19μm(base metal)to 5.1 and 3.5μm at the surface and core regions,respectively.The c-axis of the grains at the surface region was aligned with the normal direction(<0001>//ND)due to the additional strain of the tool shoulder.In contrast,the core region shows a typical shear texture,where the c-axis tends to be oriented parallel to the welding direction(<0001>//WD).The Vickers microhardness mapping across the SZ revealed that the core region was soften than the surface region due to the dynamic recrystallization and texture weakening.The microstructure of the SZ remains principally deformed after annealing treatment except for the development of massive Mg_(17)Al_(12)precipitates and the abnormal grain growth of a few grains with<11-20>//WD orientation at the upper side of the surface region.The c-axis of the grains at the surface region was tilted about 10°toward WD,while an inclined<0001>//WD orientation about 30°from WD was developed at the core region.Consequently,the distribution of microhardness values across the SZ was more heterogeneous than the FSW sample.The results were discussed in the light of grain boundary misorientation,dislocation density and the pinning effect of Mg_(17)Al_(12)precipitates.Additionally,Schmid factor analysis was used to examine the activation of the basal slip mode to characterize the associated mechanical response.展开更多
Analyzing filaments and cores in molecular clouds is key to understanding galactic star formation and its environmental dependence.This paper studies the properties and distribution of dense cores and filaments in the...Analyzing filaments and cores in molecular clouds is key to understanding galactic star formation and its environmental dependence.This paper studies the properties and distribution of dense cores and filaments in the Ophiuchus molecular cloud,with a focus on the L1688 hub-filament system(HFS)and its star formation potential.We extracted sources and filaments from Herschel images and a 13.5 resolution surface density map using the getsf method,identified dense cores among the extracted sources,evaluated core mass segregation,and constructed the core mass function(CMF).We derived properties of the filaments from their radial surface density profiles,constructed the filament linear density function(FLDF),and assessed the mass distribution in the L1688 HFS to estimate the core and filament formation efficiencies(CFEs,FFEs).We identified 64 protostellar,132 prestellar,and 686 unbound cores.The CMF of the prestellar cores has a power-law exponent of-0.86,and the FLDF of the densest filaments has a similar slope of-0.97,whereas the CMF of the unbound cores is found to be-1.36.Mass segregation is prominent among the most massive cores,with only slight differences between the bound and unbound cores.The low-mass unbound cores affect the overall spatial distribution.Among the 769 well-resolved filaments,we find a median half-maximum width of 0.12 pc and a median slope of-1.4 for the filament radial profiles.Mass distribution in the L1688 hub is dominated by the filaments,and outside the hub,it is dominated by the molecular cloud background.There exists a strong correlation between FFE and CFE,which reach their respective maxima of 71%and 5%within the hub and decrease to 21%and 0.9%outside it.The results suggest that the gravitational potential in the L1688 HFS influences core clustering in its high-density regions and that the filament-dominated core formation is a key mechanism in star formation within the system.展开更多
Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of supr...Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.展开更多
Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from...Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from 17 space-and ground-based telescopes/instruments,covering wavelengths from NIR/optical to X-ray and GeV,and spanning from the prompt emission to the afterglow phase triggered by Swift and Fermi.The early afterglow observations were carried out by SVOM/C-GFT,and spectroscopic observations of the afterglow by GTC,VLT,and TNG determined the redshift of the burst(z=0.659)later.A comprehensive analysis of the prompt emission spectrum observed by Swift-BAT and Fermi-GBM/LAT reveals a rare and significant high-energy cutoff at 76 MeV.Assuming this cutoff is due toγγabsorption allows us to place an upper limit on the initial Lorentz factor,Γ_(0)<245.The optical/NIR and GeV afterglow light curves can be described by the standard external shock model,with early-time emission dominated by a reverse shock(RS)and a subsequent transition to forward shock(FS)emission.Our afterglow modeling yields a consistent estimate of the initial Lorentz factor(Γ_(0)∼234).Furthermore,the RS-to-FS magnetic field ratio(R 302B)indicates that the RS region is significantly more magnetized than the FS region.An isotropic-equivalent kinetic energy of E_(k,iso)=5.25×10^(54) erg is derived,and the correspondingγ-ray radiation efficiency is estimated to beη_(γ)=3.1%.On the other hand,the standard afterglow model cannot reproduce the X-ray light curve of GRB 240825A,calling for improved models to characterize all multiwavelength data.展开更多
轻子散射实验是探索核子与原子核结构的理想工具。中国电子离子对撞机(Electron Ion Collider in China,EicC)建议书设想在已开建的强流重离子加速器装置(High Intensity heavy ion Accelerator Facility,HIAF)的基础上,升级质子束流为2...轻子散射实验是探索核子与原子核结构的理想工具。中国电子离子对撞机(Electron Ion Collider in China,EicC)建议书设想在已开建的强流重离子加速器装置(High Intensity heavy ion Accelerator Facility,HIAF)的基础上,升级质子束流为20 GeV的极化束流,并建造2.8~5 GeV极化电子束流,从而实现质心系能量为15~20 GeV的双极化电子-离子对撞。EicC设计的亮度为(2~4)×10^33cm^-2·s^-1,质子束流极化率达到70%,电子束流极化率达到80%。该装置除了能提供极化轻离子束流(例如:氦-3)外,也可产生非极化重离子束流(碳-12~铀-238)。EicC将聚焦核子海夸克部分子结构、原子核物质结构与性质、奇特强子态三个方面的物理研究。高亮度、高精度的对撞机有助于精确地测量核子结构函数并对核子进行三维成像,揭示强相互作用的动力学规律;原子核部分子分布包括核子短程关联以及原子核介质效应同样是该提案的重要科学目标;EicC能区接近重味夸克产生阈值,在研究重味强子谱方面拥有低背景的独特优势,有助于发现研究新的奇特强子态。质子质量起源问题也可以通过重味矢量介子的产生来研究。为了完成上述物理目标,我们将利用最先进的探测器技术建造接近全立体角覆盖的EicC对撞机谱仪。在准备EicC白皮书的过程中,我们得到世界各国专家的支持。EicC的物理与已有的实验和美国即将建设的EIC中的物理项目相互补充。EicC的建成及运行有望引领前沿的中高能核物理研究,使我国在加速器和探测器先进技术等领域实现跨越式发展,为我国核物理与强子物理以及相关科学领域提供大型综合实验平台与人才培养基地。展开更多
基金supported by LifeArc Philanthropic Fund(P2019-0004)LifeArc Pathfinder Award+7 种基金along with Wellcome Trust Seed Award(109626/Z/15/Z)FA PESP-UoB Strategic Collaboration FundBirmingham Fellowship(to SS)grants from Laboratoire d'Excellence Revive(Investissement d'AvenirANR-10-LABX-73)the Region lle-de-France via doctoral school Innovation Therapeutique,du Fondamentalàl'Appliqué(ED569)from Universite Paris-Saclay(to LA)Medical Research Council(MRC)Developmental Pathway Funding Scheme(DPFS)grant(MR/P007732/1)(to TB)supported by the Association Fran?aise contre les Myopathies(AFM-Téléthon)。
文摘Mitochondria and mitochondria-associated endoplasmic reticulum membrane in neurodegenerative diseases:Mitochondria generate most of the chemical energy needed to power the biochemical reactions of cells,and thus are often referred to as the"powerhouse"of the cell.Nevertheless,this organelle is also involved in a pleth,ora of different cellular functions such as calcium(Ca^(2+))homeostasis,apoptosis,oxidative stress,and several metabolic pathways including oxidative phosphorylation,tricarboxylic acid cycle,andβ-oxidation of fatty acids.
基金partially supported by RGC(No.17307420)supported by NSFC(No.12471077)。
文摘In order to find closed form solutions of nonintegrable nonlinear ordinary differential equations,numerous tricks have been proposed.The goal of this short review is to explain how a theorem of Eremenko on meromorphic solutions of some nonlinear ODEs together with some classical,19th-century results,can be turned into algorithms(thus avoiding ad hoc assumptions)which provide all(as opposed to some)solutions in a precise class.To illustrate these methods,we present some new such exact solutions,physically relevant.
基金financially supported by the National Natural Science Foundation of China(No.12262014).
文摘A gradient nanostructured layer was fabricated on the surface of TA15(Ti-6Al-2Zr-1Mo-1V)alloy(produced by selective laser melting)using severe shot peening(SSP).This study focuses on the evolution of the microstructure and the mechanism of grain refinement in TA15 titanium alloy during SSP treatment.Transmission electron microscopyand Rietveld refinement methods were employed.The residual stress and microhardness variations with depth were also characterized.The results show:(1)At the initial stage of deformation,plastic deformation is primarily accommodated through twinning and dislocation slip.(2)As the strain increases,twinning disappears,and dislocations interact to form tangles.Some dislocations annihilate and rearrange into subgrain boundaries,subdividing the original grains into subgrains.(3)With continued dislocation activity,the subgrain size decreases until nanocrystals are formed through the dynamic rotational recrystallization.SSP introduced compressive residual stress(CRS)in the near-surface layer of the material,with the maximum CRS of approximately−1141 MPa observed in the subsurface layer.It also induced work hardening,increasing the surface hardness to approximately 479 HV.However,the surface roughness increases,leading to a slight deterioration in surface quality.
基金supported by the National Natural Science Foundation of China(31961123003,32001098,31672265)the DFGP project of fauna of Guangdong(202115)the GDAS Special Project of Science and Technology Development(2022GDASZH-2022010106)。
文摘Estimating bird abundance is key to assess threats,and to prioritize conservation actions.However,few studies focus on this topic,particularly in developing countries,which may hamper conservation efficiency.We used data collected from Guangdong Province,China,between 2000 and 2020 to estimate bird abundance using MaxEnt modelling.In total,258 bird species were included,with an average density of 1485.2±489.3 ind./km^(2)(range:242.9-4502.2 ind./km^(2)).The highest density occurred in the Pearl River Estuary and on the Leizhou Peninsula.For forest birds,203 species were included with an average density of 1236.2±424.5 ind./km^(2)(143.7-2373.1 ind./km^(2)),and highest densities were found in the Pearl River Estuary and North River regions.For the 55 species of waterbirds,the average density was 249.0±351.8 ind./km^(2)(0.3-2336.1 ind./km^(2)).The total number of birds in Guangdong was estimated to be 2.58×108 ind.(2.24-3.06×10^(8)),with a total number of forest birds estimated to be 2.15×10^(8)ind.(1.90-2.49×10^(8)).The most abundant forest species(>107 individuals)were:Huet's Fulvetta(Alcippe hueti)with 2.84×10^(7)ind.,(range:2.73-2.95×10~7),Light-vented Bulbul(Pycnonotus sinensis)with 1.13×10^(7)ind.(1.07-1.20×10^(7)),Swinhoe's White-eye(Zosterops simplex)with 1.13×10^(7)ind.(1.09-1.17×10^(7)),and Red-whiskered Bulbul(Pycnonotus jocosus)with 1.01×10^(7)ind.(9.66-10.47×10^(6)),The total number of waterbirds in Guangdong was estimated to be 4.37×10^(7)ind.(3.38-5.75×10^(7)).The most abundant waterbirds(>106 individuals)were Black-headed Gull(Chroicocephalus ridibundus)with 6.35×10^(6)ind.(5.48-7.36×10^(6)),Pied Avocet(Recurvirostra avosetta)with 5.56×10^(6)ind.(3.75-8.24×10^(6)),and Little Egret(Egretta garzetta)with 5.01×10^(6)ind.(4.19-6.00×10^(6)).The densities and abundances of the 41 species listed as threatened in IUCN(higher than NT)or Chinese National Protected lists(higher thanⅡ)were evaluated,of which the population sizes of nine species were estimated for the first time in Guangdong.Moreover,all 41 species'average densities significantly declined from 2012 to 2017 in Nanling National Natural Reserve,Guangdong.
文摘We present a study of the ion stopping power due to free and bound electrons in a warm dense plasma.Our main goal is to propose a method of stopping-power calculation expected to be valid for any ionization degree.The free-electron contribution is described by the Maynard–Deutsch–Zimmerman formula,and the bound-electron contribution relies on the Bethe formula with corrections,in particular taking into account density and shell effects.The results of the bound-state computation using three different parametric potentials are investigated within the Garbet formalism for the mean excitation energy.The first parametric potential is due to Green,Sellin,and Zachor,the second one was proposed by Yunta,and the third one was introduced by Klapisch in the framework of atomic-structure computations.The results are compared with those of self-consistent average-atom calculations.This approach correctly bridges the limits of neutral and fully ionized matter.
文摘Recent progress in the design and fabrication of thermal metasurfaces allows a broad control of the properties of light emission,including its polarization state.Stokes polarimetry is a key approach to accurately characterize partially polarized light.The quality of a Stokes polarimeter made of retarders and polarizers can be evaluated by use of metrics such as the equally weighted variance or the condition number of the matrix representing the polarimeter.Although specific instrument configurations are used to maximize polarimeter performance at a given wavelength,such optimal solutions are not spectrally robust because of the wave-length dependence of retardance.This becomes an issue in characterizing broadband thermal sources in the infrared.We report a Stokes polarimeter making use of five polarization analysis states and consisting of two simple and common optical elements—a crystalline waveplate and a linear polarizer.We combine this setup with a Fourier transform infrared spectrometer to measure accurately in a single set of acqui-sitions without requiring any spectral filtering,and to measure the polarization state with accuracy over a broad range of wavelengths.Such a Stokes polarimeter allows for close to optimal noise in the data reduc-tion process in the mid-wave infrared spectral range from 2.5 to 5μm.
文摘In this paper, we study the stability of a class of conformable fractional-order systems using the Lyapunov function. We assume that the nonlinear part of the system satisfies the one-sided Lipschitz condition and the quadratic inner-bounded condition. We provide some sufficient conditions that ensure the asymptotic stability of the system. Furthermore, we present the construction of a feedback stabilizing controller for conformable fractional bilinear systems.
基金supported by Foshan Xianhu Laboratory Project(No.XHD2024–31000000–06)Guangdong Basic and Applied Basic Research Foundation(Nos.2024A1515140005,2024B1515120017)National Natural Science Foundation of China(No.22308070).
文摘Electrocatalytic C–N coupling technology offers a promising route for green and sustainable urea synthesis.However,this route faces challenges of low urea yield and Faradaic efficiency due to the high dissociation energy of atomic bonds in reactants,complex reaction intermediates,high reaction energy barriers,and competing side reactions.As C–N coupling involves the synergistic action of two or more active sites,it is crucial to develop efficient multi-active-site catalysts to address these challenges.This review analyzes the reaction mechanisms of electrocatalytic C–N coupling for urea synthesis and summarizes effective strategies to achieve multi-active-site catalysts,including heteroatom doping,defect engineering,heterojunctions,and diatomic catalysts.Furthermore,based on this analysis,we propose the universal design principles for high-efficiency multi-activesite catalysts.
基金supported by the National Natural Science Foundation of China(Grant No.52409151)the Programme of Shenzhen Key Laboratory of Green,Efficient and Intelligent Construction of Underground Metro Station(Programme No.ZDSYS20200923105200001)the Science and Technology Major Project of Xizang Autonomous Region of China(XZ202201ZD0003G).
文摘Substantial advancements have been achieved in Tunnel Boring Machine(TBM)technology and monitoring systems,yet the presence of missing data impedes accurate analysis and interpretation of TBM monitoring results.This study aims to investigate the issue of missing data in extensive TBM datasets.Through a comprehensive literature review,we analyze the mechanism of missing TBM data and compare different imputation methods,including statistical analysis and machine learning algorithms.We also examine the impact of various missing patterns and rates on the efficacy of these methods.Finally,we propose a dynamic interpolation strategy tailored for TBM engineering sites.The research results show that K-Nearest Neighbors(KNN)and Random Forest(RF)algorithms can achieve good interpolation results;As the missing rate increases,the interpolation effect of different methods will decrease;The interpolation effect of block missing is poor,followed by mixed missing,and the interpolation effect of sporadic missing is the best.On-site application results validate the proposed interpolation strategy's capability to achieve robust missing value interpolation effects,applicable in ML scenarios such as parameter optimization,attitude warning,and pressure prediction.These findings contribute to enhancing the efficiency of TBM missing data processing,offering more effective support for large-scale TBM monitoring datasets.
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.
基金supported by the PHC-Tassili program No.24MDU114。
文摘The difference in the microstructure,texture in the stir zone(SZ)of the AZ31(Mg-3 Al-1 Zn,wt.%)alloy after friction stir welding(FSW)and subsequent annealing at 400℃for 1 h was characterized by scanning electron microscopy(SEM)with electron backscatter diffraction(EBSD)measurements at the surface and core regions.The findings indicate that FSW produced grain refinement where the mean grain size decreases from 19μm(base metal)to 5.1 and 3.5μm at the surface and core regions,respectively.The c-axis of the grains at the surface region was aligned with the normal direction(<0001>//ND)due to the additional strain of the tool shoulder.In contrast,the core region shows a typical shear texture,where the c-axis tends to be oriented parallel to the welding direction(<0001>//WD).The Vickers microhardness mapping across the SZ revealed that the core region was soften than the surface region due to the dynamic recrystallization and texture weakening.The microstructure of the SZ remains principally deformed after annealing treatment except for the development of massive Mg_(17)Al_(12)precipitates and the abnormal grain growth of a few grains with<11-20>//WD orientation at the upper side of the surface region.The c-axis of the grains at the surface region was tilted about 10°toward WD,while an inclined<0001>//WD orientation about 30°from WD was developed at the core region.Consequently,the distribution of microhardness values across the SZ was more heterogeneous than the FSW sample.The results were discussed in the light of grain boundary misorientation,dislocation density and the pinning effect of Mg_(17)Al_(12)precipitates.Additionally,Schmid factor analysis was used to examine the activation of the basal slip mode to characterize the associated mechanical response.
文摘Analyzing filaments and cores in molecular clouds is key to understanding galactic star formation and its environmental dependence.This paper studies the properties and distribution of dense cores and filaments in the Ophiuchus molecular cloud,with a focus on the L1688 hub-filament system(HFS)and its star formation potential.We extracted sources and filaments from Herschel images and a 13.5 resolution surface density map using the getsf method,identified dense cores among the extracted sources,evaluated core mass segregation,and constructed the core mass function(CMF).We derived properties of the filaments from their radial surface density profiles,constructed the filament linear density function(FLDF),and assessed the mass distribution in the L1688 HFS to estimate the core and filament formation efficiencies(CFEs,FFEs).We identified 64 protostellar,132 prestellar,and 686 unbound cores.The CMF of the prestellar cores has a power-law exponent of-0.86,and the FLDF of the densest filaments has a similar slope of-0.97,whereas the CMF of the unbound cores is found to be-1.36.Mass segregation is prominent among the most massive cores,with only slight differences between the bound and unbound cores.The low-mass unbound cores affect the overall spatial distribution.Among the 769 well-resolved filaments,we find a median half-maximum width of 0.12 pc and a median slope of-1.4 for the filament radial profiles.Mass distribution in the L1688 hub is dominated by the filaments,and outside the hub,it is dominated by the molecular cloud background.There exists a strong correlation between FFE and CFE,which reach their respective maxima of 71%and 5%within the hub and decrease to 21%and 0.9%outside it.The results suggest that the gravitational potential in the L1688 HFS influences core clustering in its high-density regions and that the filament-dominated core formation is a key mechanism in star formation within the system.
基金financial support from the LASERLAB-EUROPE Access to Research Infrastructure Activity (Application No. 23068)carried out within the framework of EUROfusion Enabling Research Projects AWP21-ENR-01-CEA02 and AWP24-ENR-IFE-02-CEA-02+3 种基金received funding from Euratom Research and Training Programme 2021–2025 under Grant No. 633053supported by the Ministry of Youth and Sports of the Czech Republic [Project No. LM2023068 (PALS RI)]by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant Nos. XDA25030200 and XDA25010100)supported by COST (European Cooperation in Science and Technology) through Action CA21128 PROBONO (PROton BOron Nuclear Fusion: from energy production to medical applicatiOns)
文摘Recent experiments at the National Ignition Facility and theoretical modeling suggest that side stimulated Raman scattering(SSRS)instability could reduce laser–plasma coupling and generate considerable fluxes of suprathermal hot electrons under interaction conditions envisaged for direct-drive schemes for inertial confinement fusion.Nonetheless,SSRS remains to date one of the least understood parametric instabilities.Here,we report the first angularly and spectrally resolved measurements of scattered light at laser intensities relevant for the shock ignition scheme(I×10^(16)W/cm^(2)),showing significant SSRS growth in the direction perpendicular to the laser polarization.Modification of the focal spot shape and orientation,obtained by using two different random phase plates,and of the density gradient of the plasma,by utilizing exploding foil targets of different thicknesses,clearly reveals a different dependence of backward SRS(BSRS)and SSRS on experimental parameters.While convective BSRS scales with plasma density scale length,as expected by linear theory,the growth of SSRS depends on the spot extension in the direction perpendicular to laser polarization.Our analysis therefore demonstrates that under current experimental conditions,with density scale lengths L_(n)≈60–120μm and spot sizes FWHM≈40–100μm,SSRS is limited by laser beam size rather than by the density scale length of the plasma.
基金supported by the National Key R&D Program of China(grant No.2024YFA1611600)the SVOM project(a mission under the Strategic Priority Program on Space Science of the Chinese Academy of Sciences)+23 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0550401)the National Natural Science Foundation of China(NSFC,grant No.12494573)partly supported by Natural Science Foundation of Xinjiang Uygur Autonomous Region(grant No.2024D01D32)Tianshan Talent Training Program(grant No.2023TSYCLJ0053)Tianshan Innovation Team Program(grant No.2024D14015)supported by the Jiangsu Funding Program for Excellent Postdoctoral Talent(grant No.2024ZB110)the Postdoctoral Fellowship Program(grant No.GZC20241916)the General Fund(grant No.2024M763531)of the China Postdoctoral Science Foundationsupported by a Royal Society Dorothy Hodgkin Fellowship(grant Nos.DHF-R1-221175 and DHF-ERE-221005)support by a postdoctoral fellowship from the CNESsupported by the National Key R&D Program of China(grant No.2024YFA1611702)the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0550101)the support of the French Agence Nationale de la Recherche(ANR),under grant ANR-23-CE31-0011(project PEGaSUS)financial support from the GRAWITA Large Program Grant(PI P.D’Avanzo)financial support from the Italian Space Agency,contract ASI/INAF No.I/004/11/6support from the INAF project Premiale Supporto Arizona&Italiasupported by the National Natural Science Foundation of China(NSFC,grant No.12133003)supported by the National Natural Science Foundation of China(NSFC,grant No.12373042)the Bagui Scholars Program(No.GXR-6BG2424001)funded by the European Union(ERC,HEAVYMETAL,101071865,Views and opinions expressed are,however,those of the authors only and do not necessarily reflect those of the European Union or the European Research Council Neither the European Union nor the granting authority can be held responsible for them)the Cosmic Dawn Center(DAWN)is funded by the Danish National Research Foundation under grant No.DNRF140supported by the National Natural Science Foundation of China(NSFC,grant Nos.12225305 and 12321003)supported by the National Natural Science Foundation of China(NSFC,grant No.12473049)supported by the General Fund(grant No.2024M763530)of the China Postdoctoral Science Foundation。
文摘Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from 17 space-and ground-based telescopes/instruments,covering wavelengths from NIR/optical to X-ray and GeV,and spanning from the prompt emission to the afterglow phase triggered by Swift and Fermi.The early afterglow observations were carried out by SVOM/C-GFT,and spectroscopic observations of the afterglow by GTC,VLT,and TNG determined the redshift of the burst(z=0.659)later.A comprehensive analysis of the prompt emission spectrum observed by Swift-BAT and Fermi-GBM/LAT reveals a rare and significant high-energy cutoff at 76 MeV.Assuming this cutoff is due toγγabsorption allows us to place an upper limit on the initial Lorentz factor,Γ_(0)<245.The optical/NIR and GeV afterglow light curves can be described by the standard external shock model,with early-time emission dominated by a reverse shock(RS)and a subsequent transition to forward shock(FS)emission.Our afterglow modeling yields a consistent estimate of the initial Lorentz factor(Γ_(0)∼234).Furthermore,the RS-to-FS magnetic field ratio(R 302B)indicates that the RS region is significantly more magnetized than the FS region.An isotropic-equivalent kinetic energy of E_(k,iso)=5.25×10^(54) erg is derived,and the correspondingγ-ray radiation efficiency is estimated to beη_(γ)=3.1%.On the other hand,the standard afterglow model cannot reproduce the X-ray light curve of GRB 240825A,calling for improved models to characterize all multiwavelength data.
文摘轻子散射实验是探索核子与原子核结构的理想工具。中国电子离子对撞机(Electron Ion Collider in China,EicC)建议书设想在已开建的强流重离子加速器装置(High Intensity heavy ion Accelerator Facility,HIAF)的基础上,升级质子束流为20 GeV的极化束流,并建造2.8~5 GeV极化电子束流,从而实现质心系能量为15~20 GeV的双极化电子-离子对撞。EicC设计的亮度为(2~4)×10^33cm^-2·s^-1,质子束流极化率达到70%,电子束流极化率达到80%。该装置除了能提供极化轻离子束流(例如:氦-3)外,也可产生非极化重离子束流(碳-12~铀-238)。EicC将聚焦核子海夸克部分子结构、原子核物质结构与性质、奇特强子态三个方面的物理研究。高亮度、高精度的对撞机有助于精确地测量核子结构函数并对核子进行三维成像,揭示强相互作用的动力学规律;原子核部分子分布包括核子短程关联以及原子核介质效应同样是该提案的重要科学目标;EicC能区接近重味夸克产生阈值,在研究重味强子谱方面拥有低背景的独特优势,有助于发现研究新的奇特强子态。质子质量起源问题也可以通过重味矢量介子的产生来研究。为了完成上述物理目标,我们将利用最先进的探测器技术建造接近全立体角覆盖的EicC对撞机谱仪。在准备EicC白皮书的过程中,我们得到世界各国专家的支持。EicC的物理与已有的实验和美国即将建设的EIC中的物理项目相互补充。EicC的建成及运行有望引领前沿的中高能核物理研究,使我国在加速器和探测器先进技术等领域实现跨越式发展,为我国核物理与强子物理以及相关科学领域提供大型综合实验平台与人才培养基地。
