This work investigates the effects of the excluded volume and especially those of the chain stiffness on the structural and dynamical properties of a model polymer chain. The theoretical framework is the same as in th...This work investigates the effects of the excluded volume and especially those of the chain stiffness on the structural and dynamical properties of a model polymer chain. The theoretical framework is the same as in the recent works by Steinhauser et al., where a Rouse approach is adopted. Our model differs in that our chains have a finite average bending angle. As in the works by Steinhauser et al., Langevin dynamic simulations were performed without hydrodynamic interactions. Whereas this doesn＇t impact the static properties we obtain, it also allows us to compare our results on dynamic properties to those predicted by Rouse theory, where hydrodynamic interactions are also neglected. Our results show that the structural properties are very sensitive to the chain stiffness, whereas the dynamic scaling laws remain the same as those by Rouse theory, with the prefactor depending on the persistence length.展开更多
A theoretical model for the translocation process of biomacromolecule is developed based on the self-consistent field theory （SCFT）, where the biomacromolecule is regarded as a self-avoiding polymer chain actuated b...A theoretical model for the translocation process of biomacromolecule is developed based on the self-consistent field theory （SCFT）, where the biomacromolecule is regarded as a self-avoiding polymer chain actuated by the external potential. In this theoretical model, the external potential, the Coulomb electrostatic potential of the charged ions （the electrolyte effect）, and the attractive interaction between the polymer and the nanopore （the excluded volume effect） are all considered, which have effects on the free energy landscape and conformation entropy during the translocation stage. The result shows that the entropy barrier of the polymer in the solution with high valence electrolyte is much larger than that with low valence electrolyte under the same condition, leading to that the translocation time of the DNA molecules in the solution increases when the valence electrolyte increases. In addition, the attractive interaction between the polymer and the nanopore increases the free energy of the polymer, which means that the probability of the translocation through the nanopore increases. The average translocation time decreases when the excluded volume effect parameter increases. The electrolyte effect can prolong the average translocation time. The simulation results agree well with the available experimental results.展开更多
Beam-tracking simulations have been extensively utilized in the study of collective beam instabilities in circular accelerators.Traditionally,many simulation codes have relied on central processing unit(CPU)-based met...Beam-tracking simulations have been extensively utilized in the study of collective beam instabilities in circular accelerators.Traditionally,many simulation codes have relied on central processing unit(CPU)-based methods,tracking on a single CPU core,or parallelizing the computation across multiple cores via the message passing interface(MPI).Although these approaches work well for single-bunch tracking,scaling them to multiple bunches significantly increases the computational load,which often necessitates the use of a dedicated multi-CPU cluster.To address this challenge,alternative methods leveraging General-Purpose computing on Graphics Processing Units(GPGPU)have been proposed,enabling tracking studies on a standalone desktop personal computer(PC).However,frequent CPU-GPU interactions,including data transfers and synchronization operations during tracking,can introduce communication overheads,potentially reducing the overall effectiveness of GPU-based computations.In this study,we propose a novel approach that eliminates this overhead by performing the entire tracking simulation process exclusively on the GPU,thereby enabling the simultaneous processing of all bunches and their macro-particles.Specifically,we introduce MBTRACK2-CUDA,a Compute Unified Device Architecture(CUDA)ported version of MBTRACK2,which facilitates efficient tracking of single-and multi-bunch collective effects by leveraging the full GPU-resident computation.展开更多
[Objectives]To explore the control mode of farmland drainage pollutants and investigate the effects of ecological ditch and wetland on reducing farmland drainage pollutants in Hetao Irrigation District.[Methods]Based ...[Objectives]To explore the control mode of farmland drainage pollutants and investigate the effects of ecological ditch and wetland on reducing farmland drainage pollutants in Hetao Irrigation District.[Methods]Based on the demonstration construction project of the ecological ditch-constructed wetland system in the Hetao Irrigation District,an experimental study was conducted from July to September 2023 to investigate the interception and purification effects of ecological ditches,constructed wetlands,and the combined ecological ditch-constructed wetland system on farmland drainage pollutants.Key water quality parameters measured included total nitrogen(TN)concentration and total phosphorus(TP)concentration.[Results]Different treatment modes of ecological ditches and constructed wetlands have a certain removal effect on nitrogen and phosphorus pollutants in water bodies.The ecological ditches treated with Astragalus laxmannii,Melilotus officinalis,Medicago sativa,bio-ball substrate,and bio-sheet substrate showed reduction efficiencies for TN and TP of 21.09% and 23.84%,12.06% and 26.67%,20.08% and 34.15%,23.65% and 20.56%,and 19.92% and 25.83%,respectively.The emergent plant area showed reduction efficiencies of 24.28%for TN and 17.89%for TP,while the submerged plant area achieved a reduction efficiency of 10.21%for both TN and TP.Among the different treatment modes,the ecological ditch with M.sativa performed better in TP removal,whereas the bio-ball substrate treatment mode showed higher effectiveness in TN removal.In addition,the emergent plant area exhibited better TP removal performance,while the submerged plant area was more effective in TN removal.The combined system of ecological ditch and constructed wetland achieved removal rates of 37.55% for TN and 11.47% for TP.It effectively facilitates the step-by-step interception and adsorption purification of pollutants,thereby showing significant removal and purification effects on nitrogen and phosphorus contaminants.This contributes to mitigating agricultural non-point source pollution.[Conclusions]The combined ecological ditch-constructed wetland system serves dual functions of agricultural drainage and pollutant interception and purification.It reduces the pollution load of farmland drainage on receiving water bodies to some extent and mitigates agricultural non-point source pollution.Therefore,it is a relatively suitable technology for managing agricultural non-point source pollution in the Hetao Irrigation District.展开更多
Inflammatory bowel disease(IBD),which includes Crohn’s disease(CD)and ulcerative colitis(UC),is a chronic inflammatory condition affecting the gastrointestinal tract.The global incidence and prevalence of IBD continu...Inflammatory bowel disease(IBD),which includes Crohn’s disease(CD)and ulcerative colitis(UC),is a chronic inflammatory condition affecting the gastrointestinal tract.The global incidence and prevalence of IBD continue to increase.While multiple clinical treatments exist,conventional therapies frequently present limitations and adverse effects.Natural polysaccharides(PSs)have emerged as a significant focus of research interest due to their therapeutic potential and applications in functional foods and health products.This review synthesizes current understanding of IBD pathophysiology and the mechanisms by which natural PSs counter IBD,including their capacity to restore immune homeostasis and intestinal barrier function,modulate gut microbiota and metabolites,reduce oxidative stress,and address irregularities in autophagy and endoplasmic reticulum stress(ERS).The review examines the structure-activity relationships of PSs demonstrating anti-IBD effects and identifies promising therapeutic products.The discussion encompasses pharmacokinetics,safety evaluations,and clinical applications of these compounds.This comprehensive review establishes a theoretical foundation for developing natural PS-based therapeutic approaches for IBD management.展开更多
This article reviews the research advances in traditional Chinese medicine rhubarb and its compound formulations in the treatment of sepsis,with particular emphasis on elucidating their mechanisms of action and clinic...This article reviews the research advances in traditional Chinese medicine rhubarb and its compound formulations in the treatment of sepsis,with particular emphasis on elucidating their mechanisms of action and clinical application value.Research has demonstrated that rhubarb and its compound formulations exert therapeutic effects via multiple targets and mechanisms,including anti-inflammatory actions,protection of the intestinal barrier,modulation of immune balance,inhibition of oxidative stress,and regulation of associated signaling pathways.Clinically,rhubarb has shown distinct advantages in enhancing gastrointestinal function,mitigating systemic inflammatory responses,and reducing mortality rates among patients with sepsis.These findings provide a foundational reference for the integrated prevention and treatment of sepsis through the combined use of traditional Chinese and Western medicine.展开更多
In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural a...In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.展开更多
Transforming urban spatial structures to promote green and low-carbon development is an effective strategy.Although prior studies have examined the impact of urban polycentricity on carbon emissions and economic devel...Transforming urban spatial structures to promote green and low-carbon development is an effective strategy.Although prior studies have examined the impact of urban polycentricity on carbon emissions and economic development,research on its role in the synergistic relationship between these factors regarding carbon emission efficiency is limited.Furthermore,existing literature often overlooks nonlinear effects and interactions with other urban variables.This paper analyzed data from 295 Chinese cities in 2020,calculating urban population polycentricity,population dispersion indices,and carbon emission efficiency.Utilizing local spatial autocorrelation tools,we reveal interactions among urban population polycentricity,dispersion,carbon emissions,and carbon emission efficiency.We then employ a gradient boosting decision tree model(GBDT)to explore nonlinear and synergistic effects of polycentric urbanization.Key findings include:1)polycentric urbanization in Chinese cities exhibits significant spatial differentiation characteristics.The Polycentricity index is relatively high in economically developed eastern coastal regions with an overall low level,carbon emissions are concentrated in industrialized north-central cities and some Yangtze River Delta hubs,and carbon emission efficiency is the highest in the Yangtze River Delta while relatively low in Northeast China;there are significant spatially heterogeneous interaction characteristics among population polycentricity,population dispersion,carbon emissions,and carbon emission efficiency.2)Urban population polycentricity contributes 9.42%to total carbon emissions and 6.24%to carbon emission efficiency.3)The polycentricity index has a nonlinear impact on carbon emissions and carbon emission efficiency:no significant effect when below 0.50 or above 0.55,increased carbon emissions in 0.50-0.53,and reduced carbon emissions with improved efficiency in 0.53-0.55.4)The polycentricity index has an interaction effect with other variables;specifically,when the polycentricity index is between 0.53 and 0.55,its interaction with urban gross domestic product(GDP),urban population,urban built-up area,green coverage rate in built-up areas,urban technological expenditure,and the proportion of the output value of the secondary industry will reduce carbon emissions and improve carbon emission efficiency.These findings enhance the understanding of urban spatial structures and carbon emissions,providing valuable insights for policymakers in developing green and low-carbon strategies.展开更多
Lithium metal batteries(LMBs)have been regarded as one of the most promising alternatives in the post-lithium battery era due to their high energy density,which meets the needs of light-weight electronic devices and l...Lithium metal batteries(LMBs)have been regarded as one of the most promising alternatives in the post-lithium battery era due to their high energy density,which meets the needs of light-weight electronic devices and long-range electric vehicles.However,technical barriers such as dendrite growth and poor Li plating/stripping reversibility severely hinder the practical application of LMBs.However,lithium nitrate(LiNO_(3))is found to be able to stabilize the Li/electrolyte interface and has been used to address the above challenges.To date,considerable research efforts have been devoted toward understanding the roles of LiNO_(3) in regulating the surface properties of Li anodes and toward the development of many effective strategies.These research efforts are partially mentioned in some articles on LMBs and yet have not been reviewed systematically.To fill this gap,we discuss the recent advances in fundamental and technological research on LiNO_(3) and its derivatives for improving the performances of LMBs,particularly for Li-sulfur(S),Li-oxygen(O),and Li-Li-containing transition-metal oxide(LTMO)batteries,as well as LiNO_(3)-containing recipes for precursors in battery materials and interphase fabrication.This review pays attention to the effects of LiNO_(3) in lithium-based batteries,aiming to provide scientific guidance for the optimization of electrode/electrolyte interfaces and enrich the design of advanced LMBs.展开更多
Under the background of‘the Belt and Road’and‘China-Mongolia-Russia Economic Corridor’initiatives,this paper studied the urban accessibility level,regional accessibility pattern and regional spatial effects along ...Under the background of‘the Belt and Road’and‘China-Mongolia-Russia Economic Corridor’initiatives,this paper studied the urban accessibility level,regional accessibility pattern and regional spatial effects along the Primorsky No.1 and No.2 transportation corridors.First,the evaluation of urban accessibility level with and without Primorsky No.1 and No.2 high-speed rails(HSRs)opening was conducted with two indicators,i.e.,the weighted average travel time,and the economic potential.After the evaluation,the spatial differentiation pattern of the accessibility changes with and without Primorsky No.1 and No.2 HSRs opening was performed respectively using ArcGIS.On these bases,the regional spatial effects brought by Primorsky No.1 and No.2 HSRs opening were studied.The results are as following.First,the urban accessibility level will be greatly improved by the opening of Primorsky No.1 and No.2 HSRs.All adjacent cities will be integrated into‘1 h HSR communication circle’and the whole journey will be integrated into‘4 h HSR communication circle’along Primorsky No.1 and No.2 corridors,respectively.The HSR accessibility of Primorsky No.1 corridor is stronger than that of Primorsky No.2 corridor.But the HSR accessibility improvement degree of Primorsky No.1 corridor is weaker than that of Primorsky No.2 corridor.Second,spatially,along Primorsky No.1 and No.2 corridors,the HSR accessibility level of the cities which are located in China is stronger than those cities located in Russia,showing the‘High West,Low East’patterns.The HSR accessibility improvement degree of the cities which are located in Russia and Sino-Russian border is stronger than those cities located in China,showing the‘High East,Low West’patterns.Third,Primorsky No.1 and No.2 corridors could connect the China’s‘Heilongjiang Land Sea Silk Road Economic Belt’and‘Changchun-Jilin-Tumen Development Pilot Zone’respectively,gradually involving into the development of China’s Harbin-Changchun Megalopolis.Relying on Harbin(China)and Changchun(China),Primorsky No.1 and No.2 HSRs could connect Northeast China-Beijing HSR,accelerating the diffusion of population,economy and other flows from China’s Beijing-Tianjin-Hebei Urban Agglomeration to Northeast China,and then to Russia’s Far East Federal District.Relying on Suifenhe(China)and Hunchun(China),Primorsky No.1 and No.2 HSRs could be conducive to the development of the second largest sea channels for Northeast China,creating the Northeast Asian Urban Belt,and new sea-rail intermodal pattern among China,Russia,Democratic People’s Republic of Korea,Japan and Republic of Korea.Relying on Vladivostok(Russia)and Zarubino(Russia),Primorsky No.1 and No.2 corridors could connect the‘Ice Silk Road’,building the‘Sino-Russian Northern Maritime Corridor’and‘Sino-Russian Arctic Blue Economic Areas’.展开更多
Based on the observation data of rainfall,vegetation,runoff and sediment yield in the experimental plots located in Hetian Town,Changting County of Fujian Province during 2007-2010,the changing characteristics and int...Based on the observation data of rainfall,vegetation,runoff and sediment yield in the experimental plots located in Hetian Town,Changting County of Fujian Province during 2007-2010,the changing characteristics and interrelation of live vegetation volume of grass,rainfall parameters,and water(soil)conservation effect RE(SE)were analyzed at four time scales of rainfall event,month,season,and year.The results showed that with the increase of time scales,the rainfall and vegetation indicators increased or decreased more or less,and the variation range of RE was small,while SEslowly decreased.The mean REchanged by 10%-20% at different time scales,and the observed water conservation effect of the grassland was the best at season scale while the worst at year scale.The soil conservation effect of the grassland was the best at month scale and the worst at season scale.The water conservation effect of the grass was mainly controlled by rainfall factors,including rainfall duration and precipitation at rainfall event scale,and the maximum intensity of precipitation within 30 min at longer time scales.However,the soil conservation effect of the grass was mainly controlled by vegetation factors,including the contribution of the litter on soil surface at rainfall event scale,the interaction of rainfall and vegetation at month and season scales,and the live vegetation volume of the grass at year scale.Consequently,at different time scales,the factors influencing water and soil conservation changed and interacted,and the observed water and soil conservation effects were also different,indicating that the influence of time scales deserves attention in both research and management practices.展开更多
Understanding the excluded volume of anisotropic particle is of great importance in the evaluation of continuum percolation and random packing behaviors of soft/hard particle systems in heterogeneous disordered media....Understanding the excluded volume of anisotropic particle is of great importance in the evaluation of continuum percolation and random packing behaviors of soft/hard particle systems in heterogeneous disordered media.In this work,we obtain the excluded volumes of several anisotropic convex particles including prolate spheroids,oblate spheroids,spherocylinders,and Platonic particles,using theoretical and numerical approaches.According to the second virial coefficient,we first present a theoretical scheme for determining the excluded volumes of anisotropic particles.Also,the mean tangent diameters of anisotropic convex particles are formulated by the quantitative stereology.Subsequently,Monte Carlo simulations are demonstrated to numerically evaluate the excluded volumes.The theoretical results of the dimensionless excluded volume are thereafter compared with that of the numerical results to verify the validity of the theoretical scheme.We further investigate the dependence of the dimensionless excluded volume on the geometric characteristics of anisotropic particles based on the proposed theoretical and numerical schemes.Results show that the dimensionless excluded volume mainly relies on the shape and surface information of anisotropic particles.The developed theoretical and numerical schemes can provide theoretical insights into the percolation threshold and packing density of soft/hard anisotropic particle systems in heterogeneous materials,physics,and chemistry fields.展开更多
To investigate equilibrium mercury(Hg)and lead(Pb)isotope fractionation caused by the nuclear volume effect(NVE)in crystals,the electron densities at nuclei(i.e.,|Ψ(0)|2)for Hg-or Pb-bearing crystalline compounds wer...To investigate equilibrium mercury(Hg)and lead(Pb)isotope fractionation caused by the nuclear volume effect(NVE)in crystals,the electron densities at nuclei(i.e.,|Ψ(0)|2)for Hg-or Pb-bearing crystalline compounds were investigated by using the relativistic spin orbit zeroth-order regular approximation(ZORA)method with a three-dimensional periodic boundary condition based on the density functional theory(DFT).Many isotope fractionation factors of crystalline compounds are provided for the first time.Our results show,even at1000℃,NVE-driven Hg and Pb isotope fractionation are meaningfully large,i.e.,range from 0.12‰to 0.49‰(202Hg/^(198)Hg),from-0.20‰to 0.17‰(208Pb/^(206)Pb)and from-0.08‰to 0.06‰(207Pb/^(206) Pb)relative to Hg0 vapor and Pb0 vapor,respectively.Specifically,the fractionations range from-0.06‰to-0.20‰(208Pb/^(206)Pb)and from-0.02‰to-0.08‰(207Pb/^(206)Pb)for Pb2+-bearing species,from 0.10‰to 0.17‰(208Pb/^(206)Pb)and from 0.04‰to 0.06‰(207Pb/^(206)Pb)for Pb4+-bearing species in crystals.All calculated Hg-bearing species in crystals will enrich heavier isotope(202Hg)relative to Hg0 vapor.Meanwhile,Pb4+-bearing species enrich heavier Pb isotopes(208Pb and 207Pb)than Pb^(2+)-bearing species in crystals,which the enrichment can be up to 0.37‰(208-Pb/^(206)Pb)and 0.14‰(207Pb/^(206)Pb)at 1000℃,due to their NVEs are in opposite directions.The NVE-driven MIFs of Hg isotopes,which are compared to the Hg202-Hg198baseline,are up to-0.158‰(ΔNV199Hg),-0.024‰(ΔNV200Hg)and-0.094‰(ΔNV201Hg)relative to Hg0 vapor at5000 C.For all studied Hg-bearing species in crystals,the MIFs of two odd-mass isotopes(i.e.,ΔNV199Hg andΔNV201Hg)will be changed proportionally and their ratio(i.e.,ΔNV199Hg/ΔNV201Hg)will be a constant 1.67.The NVE can also cause mass-independent fractionations for 207Pb and 204 Pb compared to the baseline of 208Pb and 206Pb.The largest NVEdriven MIFs are 0.043‰(ΔNV207Pb)and-0.040‰(ΔNV204Pb)among all the studied species relative to Pb0 vapor at 5000 C.The magnitudes of odd-mass isotope MIF(ΔNV207Pb)and even-mass isotope MIF(ΔNV204Pb)are almost the same but with opposite signs,leading to the MIF ratio of them(i.e.,ΔNV207Pb/ΔNV204Pb)is-1.08.展开更多
We propose a pedestrian position update rule, which is added to a microscopic pedestrian model to avoid pedestrian overlap. In the rule, the step size of a pedestrian moving in a selected direction at each update is i...We propose a pedestrian position update rule, which is added to a microscopic pedestrian model to avoid pedestrian overlap. In the rule, the step size of a pedestrian moving in a selected direction at each update is in inverse proportion to the repulsive actions imposed by other pedestrians moving in a direction with an exponential rate. The positions of the pedestrians are then updated in each small time interval. In this way, a barrier between the pedestrians can be generated, and after updating their positions the pedestrians do not overlap with each other. The modified model is compared to the original model through a simulation of the evacuation process of pedestrians in a closed area. The simulation results indicate that the modified model is superior to the original model in several aspects.展开更多
To evaluate the fracturing effect and dynamic change process after volume fracturing with vertical wells in low permeability oil reservoirs, an oil-water two-phase flow model and a well model are built. On this basis,...To evaluate the fracturing effect and dynamic change process after volume fracturing with vertical wells in low permeability oil reservoirs, an oil-water two-phase flow model and a well model are built. On this basis, an evaluation method of fracturing effect based on production data and fracturing fluid backflow data is established, and the method is used to analyze some field cases. The vicinity area of main fracture after fracturing is divided into different stimulated regions. The permeability and area of different regions are used to characterize the stimulation strength and scale of the fracture network. The conductivity of stimulated region is defined as the product of the permeability and area of the stimulated region. Through parameter sensitivity analysis, it is found that half-length of the fracture and the permeability of the core area mainly affect the flow law near the well, that is, the early stage of production;while matrix permeability mainly affects the flow law at the far end of the fracture. Taking a typical old well in Changqing Oilfield as an example, the fracturing effect and its changes after two rounds of volume fracturing in this well are evaluated. It is found that with the increase of production time after the first volume fracturing, the permeability and conductivity of stimulated area gradually decreased, and the fracturing effect gradually decreased until disappeared;after the second volume fracturing, the permeability and conductivity of stimulated area increased significantly again.展开更多
A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_...A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.展开更多
The effects of Co and Fe co-doping Ni-Mn-In alloy on the phase stability,lattice parameters,mag-netic properties,and electronic structures are systematically investigated by using the first-principles calculations.Res...The effects of Co and Fe co-doping Ni-Mn-In alloy on the phase stability,lattice parameters,mag-netic properties,and electronic structures are systematically investigated by using the first-principles calculations.Results indicate that Fe atoms replace the excess Mn2 atoms by direct and indirect coex-istence(Fe→Mn 2 and Fe→In→Mn2);Co substitutes the Ni atoms by direct substitution(Co→Ni)for the Ni-Mn-In alloy.The austenites all exhibit the ferromagnetic(FM)state for the studied composi-tions.The NM martensites are in the ferrimagnetic(FIM-1)state for the Ni_(2)Mn_(1.5)In_(0.5),Ni_(2)Mn_(1.25)In_(0.5)Fe 0.25,Ni_(1.75)Mn_(1.5)In_(0.5)Co_(0.25),and Ni_(1.75)Mn_(1.25)In_(0.5)Co_(0.25)Fe 0.25 alloys,while the other compositions are in the FM state.The phase stability of austenite and martensite decreases with increasing Co and Fe co-doping.A magnetic-structural coupling transition occurs at x<0.25 and y<0.25.The Ni_(1.91)Mn_(1.5)In_(0.5)Co_(0.08)and Ni_(1.91)Mn_(1.42)In_(0.5)Co_(0.08)Fe_(0.08)alloys exhibit an A→6M→NM transformation,accompanied by a magnetic transition.When Co and Fe are co-doped,the hybridization strength between Co and Fe is greater than that between Co/Fe and Mn.The enhancement of magnetocaloric and elastocaloric effects is favored by larger magnetization difference(△M)and lattice volume change(△V/V_(0)).Based on the calculated phase stability,magneto-structure coupling,△V/V 0 and c/a ratio,one can predict that the Ni_(2)-x Mn_(1.5)-y In_(0.5)Co x Fe y alloy with Co content 0≤x≤0.25 and Fe content 0≤y≤0.05 is predicted to have good magneto-controlled functional behavior.展开更多
Hippocampal volume loss is an important biomarker in distinguishing subjects with Alzheimer＇s disease （AD） and its measurement in magnetic resonance images （MRI） is influenced by partial volume effects （PVE）. T...Hippocampal volume loss is an important biomarker in distinguishing subjects with Alzheimer＇s disease （AD） and its measurement in magnetic resonance images （MRI） is influenced by partial volume effects （PVE）. This paper describes a post-processing approach to quantify PVE for correction of the hippocampal volume by using a spatial fuzzyC-means （SFCM） method. The algorithm is evaluated on a dataset of 20 T1-weighted MRI scans sampled at two different resolutions. The corrected volumes for left and right hippocampus （HC） which are 23% and 18% for the low resolution and 6% and 5% for the high resolution datasets, respectively are lower than hippocampal volume results from manual segmentation. Results show the importance of applying this technique in AD detection with low resolution datasets.展开更多
It is well-known that the equilibrium isotope fractionation of mercury(Hg)includes classical massdependent fractionations(MDFs)and nuclear volume effect(NVE)induced mass-independent fractionations(MIFs).However,the ef...It is well-known that the equilibrium isotope fractionation of mercury(Hg)includes classical massdependent fractionations(MDFs)and nuclear volume effect(NVE)induced mass-independent fractionations(MIFs).However,the effect of the NVE on these kinetic processes is not known.The total fractionations(MDFs+NVEinduced MIFs)of several representative Hg-incorporated substances were selected and calculated with ab initio calculations in this work for both equilibrium and kinetic processes.NVE-induced MIFs were calculated with scaled contact electron densities at the nucleus through systematic evaluations of their accuracy and errors using the Gaussian09 and DIRAC19 packages(named the electron density scaling method).Additionally,the NVE-induced kinetic isotope effect(KIE)of Hg isotopes are also calculated with this method for several representative Hg oxidation reactions by chlorine species.Total KIEs for 202 Hg/^(198)Hg ranging from−2.27‰to 0.96‰are obtained.Three anomalous^(202)Hg-enriched KIEs(δ^(202)Hg/^(198)Hg=0.83‰,0.94‰,and 0.96‰,)caused by the NVE are observed,which are quite different from the classical view(i.e.,light isotopes react faster than the heavy ones).The electron density scaling method we developed in this study can provide an easier way to calculate the NVE-induced KIEs for heavy isotopes and serve to better understand the fractionation mechanisms of mercury isotope systems.展开更多
Current transient analysis predominantly relies on zero-dimensional/one-dimensional tools,proficient at capturing aerothermodynamic variations across critical engine stations but insufficient for analyzing the interna...Current transient analysis predominantly relies on zero-dimensional/one-dimensional tools,proficient at capturing aerothermodynamic variations across critical engine stations but insufficient for analyzing the internal flow field evolution during transients.Addressing this gap,the study presents an enhanced quasi-three dimensional(quasi-3D)transient simulation technique that integrates component volume effects,offering a significant leap from the preceding quasi-3D transient simulation method based on quasi-steady assumption.By embedding the component volume effects on density,momentum,and energy within the physical temporal dimension of the Navier-Stokes equations,the refined quasi-3D transient model achieves a closer representation of physical phenomena.Validation against a single-shaft turbofan engine’s experimental data confirms the model’s accuracy.Average errors for key performance indicators,including shaft speed,thrust,mass flow rate,and critical component exit temperature and pressure,remain below 0.41%,5.69%,2.55%,3.18%and 0.67%,respectively.Crucially,the model exposes a discernible temporal lag in the compressor outlet pressure and temperature response due to volume effects—previously unquantified in quasi-3D transient simulations.And further exploration of the meridional flow field emphasizes the consequential role of volumes in transient flow field evolution.Incorporating volume effects within quasi-3D transient simulations enhances engine modeling and is pivotal for precise transient analysis in engine design and optimization.展开更多
基金financially supported by the National Natural Science Foundation of China(No.10572056)
文摘This work investigates the effects of the excluded volume and especially those of the chain stiffness on the structural and dynamical properties of a model polymer chain. The theoretical framework is the same as in the recent works by Steinhauser et al., where a Rouse approach is adopted. Our model differs in that our chains have a finite average bending angle. As in the works by Steinhauser et al., Langevin dynamic simulations were performed without hydrodynamic interactions. Whereas this doesn＇t impact the static properties we obtain, it also allows us to compare our results on dynamic properties to those predicted by Rouse theory, where hydrodynamic interactions are also neglected. Our results show that the structural properties are very sensitive to the chain stiffness, whereas the dynamic scaling laws remain the same as those by Rouse theory, with the prefactor depending on the persistence length.
基金supported by the National Natural Science Foundation of China(No.51375090)
文摘A theoretical model for the translocation process of biomacromolecule is developed based on the self-consistent field theory （SCFT）, where the biomacromolecule is regarded as a self-avoiding polymer chain actuated by the external potential. In this theoretical model, the external potential, the Coulomb electrostatic potential of the charged ions （the electrolyte effect）, and the attractive interaction between the polymer and the nanopore （the excluded volume effect） are all considered, which have effects on the free energy landscape and conformation entropy during the translocation stage. The result shows that the entropy barrier of the polymer in the solution with high valence electrolyte is much larger than that with low valence electrolyte under the same condition, leading to that the translocation time of the DNA molecules in the solution increases when the valence electrolyte increases. In addition, the attractive interaction between the polymer and the nanopore increases the free energy of the polymer, which means that the probability of the translocation through the nanopore increases. The average translocation time decreases when the excluded volume effect parameter increases. The electrolyte effect can prolong the average translocation time. The simulation results agree well with the available experimental results.
基金supported by the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(MSIT)(No.RS-2022-00143178)the Ministry of Education(MOE)(Nos.2022R1A6A3A13053896 and 2022R1F1A1074616),Republic of Korea.
文摘Beam-tracking simulations have been extensively utilized in the study of collective beam instabilities in circular accelerators.Traditionally,many simulation codes have relied on central processing unit(CPU)-based methods,tracking on a single CPU core,or parallelizing the computation across multiple cores via the message passing interface(MPI).Although these approaches work well for single-bunch tracking,scaling them to multiple bunches significantly increases the computational load,which often necessitates the use of a dedicated multi-CPU cluster.To address this challenge,alternative methods leveraging General-Purpose computing on Graphics Processing Units(GPGPU)have been proposed,enabling tracking studies on a standalone desktop personal computer(PC).However,frequent CPU-GPU interactions,including data transfers and synchronization operations during tracking,can introduce communication overheads,potentially reducing the overall effectiveness of GPU-based computations.In this study,we propose a novel approach that eliminates this overhead by performing the entire tracking simulation process exclusively on the GPU,thereby enabling the simultaneous processing of all bunches and their macro-particles.Specifically,we introduce MBTRACK2-CUDA,a Compute Unified Device Architecture(CUDA)ported version of MBTRACK2,which facilitates efficient tracking of single-and multi-bunch collective effects by leveraging the full GPU-resident computation.
基金Supported by Special Fund Project for the Transformation of Scientific and Technological Achievements in Inner Mongolia Autonomous Region(2021CG0013)Bayannur City Science and Technology Plan Project(K202014)+1 种基金Inner Mongolia Autonomous Region Science and Technology Plan Project(2022YFHH0088)Research Special Project of the Education Department of Inner Mongolia Autonomous Region(STAQZX202320).
文摘[Objectives]To explore the control mode of farmland drainage pollutants and investigate the effects of ecological ditch and wetland on reducing farmland drainage pollutants in Hetao Irrigation District.[Methods]Based on the demonstration construction project of the ecological ditch-constructed wetland system in the Hetao Irrigation District,an experimental study was conducted from July to September 2023 to investigate the interception and purification effects of ecological ditches,constructed wetlands,and the combined ecological ditch-constructed wetland system on farmland drainage pollutants.Key water quality parameters measured included total nitrogen(TN)concentration and total phosphorus(TP)concentration.[Results]Different treatment modes of ecological ditches and constructed wetlands have a certain removal effect on nitrogen and phosphorus pollutants in water bodies.The ecological ditches treated with Astragalus laxmannii,Melilotus officinalis,Medicago sativa,bio-ball substrate,and bio-sheet substrate showed reduction efficiencies for TN and TP of 21.09% and 23.84%,12.06% and 26.67%,20.08% and 34.15%,23.65% and 20.56%,and 19.92% and 25.83%,respectively.The emergent plant area showed reduction efficiencies of 24.28%for TN and 17.89%for TP,while the submerged plant area achieved a reduction efficiency of 10.21%for both TN and TP.Among the different treatment modes,the ecological ditch with M.sativa performed better in TP removal,whereas the bio-ball substrate treatment mode showed higher effectiveness in TN removal.In addition,the emergent plant area exhibited better TP removal performance,while the submerged plant area was more effective in TN removal.The combined system of ecological ditch and constructed wetland achieved removal rates of 37.55% for TN and 11.47% for TP.It effectively facilitates the step-by-step interception and adsorption purification of pollutants,thereby showing significant removal and purification effects on nitrogen and phosphorus contaminants.This contributes to mitigating agricultural non-point source pollution.[Conclusions]The combined ecological ditch-constructed wetland system serves dual functions of agricultural drainage and pollutant interception and purification.It reduces the pollution load of farmland drainage on receiving water bodies to some extent and mitigates agricultural non-point source pollution.Therefore,it is a relatively suitable technology for managing agricultural non-point source pollution in the Hetao Irrigation District.
基金supported by the National Natural Science Foundation of China(Nos.82003977,82274134 and 82274139)the National Key Research and Development Plan(No.2017YFC1702200)+1 种基金the Key Research and Development Program of Zhejiang Province(No.2020C04020)the Science and Technology Program of Zhejiang Province(No.2025C02183).
文摘Inflammatory bowel disease(IBD),which includes Crohn’s disease(CD)and ulcerative colitis(UC),is a chronic inflammatory condition affecting the gastrointestinal tract.The global incidence and prevalence of IBD continue to increase.While multiple clinical treatments exist,conventional therapies frequently present limitations and adverse effects.Natural polysaccharides(PSs)have emerged as a significant focus of research interest due to their therapeutic potential and applications in functional foods and health products.This review synthesizes current understanding of IBD pathophysiology and the mechanisms by which natural PSs counter IBD,including their capacity to restore immune homeostasis and intestinal barrier function,modulate gut microbiota and metabolites,reduce oxidative stress,and address irregularities in autophagy and endoplasmic reticulum stress(ERS).The review examines the structure-activity relationships of PSs demonstrating anti-IBD effects and identifies promising therapeutic products.The discussion encompasses pharmacokinetics,safety evaluations,and clinical applications of these compounds.This comprehensive review establishes a theoretical foundation for developing natural PS-based therapeutic approaches for IBD management.
基金Supported by National Natural Science Foundation of China(82374346)Double Hundred Outstanding Young and Middle-aged Medical and Health Talents of Wuxi City(BJ2023071)Scientific Research Project of Wuxi Municipal Health Commission(Q202358).
文摘This article reviews the research advances in traditional Chinese medicine rhubarb and its compound formulations in the treatment of sepsis,with particular emphasis on elucidating their mechanisms of action and clinical application value.Research has demonstrated that rhubarb and its compound formulations exert therapeutic effects via multiple targets and mechanisms,including anti-inflammatory actions,protection of the intestinal barrier,modulation of immune balance,inhibition of oxidative stress,and regulation of associated signaling pathways.Clinically,rhubarb has shown distinct advantages in enhancing gastrointestinal function,mitigating systemic inflammatory responses,and reducing mortality rates among patients with sepsis.These findings provide a foundational reference for the integrated prevention and treatment of sepsis through the combined use of traditional Chinese and Western medicine.
基金supported by the CAS Strategic Priority Research Program(No.XDB0760102),the Ministry of Science and Technology of China(No.2022YFF0802501)the Major Science and Technology Infrastructure Maintenance and Transformation Project of the Chinese Academy of Sciences,Shanghai Science and Technology Innovation Action Plan-Phospherus Project(No.23YF1426200)the National Key Research and Development Program of China(No.2024YFE0212200).
文摘In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.
基金Under the auspices of National Natural Science Foundation of China(No.42571300)。
文摘Transforming urban spatial structures to promote green and low-carbon development is an effective strategy.Although prior studies have examined the impact of urban polycentricity on carbon emissions and economic development,research on its role in the synergistic relationship between these factors regarding carbon emission efficiency is limited.Furthermore,existing literature often overlooks nonlinear effects and interactions with other urban variables.This paper analyzed data from 295 Chinese cities in 2020,calculating urban population polycentricity,population dispersion indices,and carbon emission efficiency.Utilizing local spatial autocorrelation tools,we reveal interactions among urban population polycentricity,dispersion,carbon emissions,and carbon emission efficiency.We then employ a gradient boosting decision tree model(GBDT)to explore nonlinear and synergistic effects of polycentric urbanization.Key findings include:1)polycentric urbanization in Chinese cities exhibits significant spatial differentiation characteristics.The Polycentricity index is relatively high in economically developed eastern coastal regions with an overall low level,carbon emissions are concentrated in industrialized north-central cities and some Yangtze River Delta hubs,and carbon emission efficiency is the highest in the Yangtze River Delta while relatively low in Northeast China;there are significant spatially heterogeneous interaction characteristics among population polycentricity,population dispersion,carbon emissions,and carbon emission efficiency.2)Urban population polycentricity contributes 9.42%to total carbon emissions and 6.24%to carbon emission efficiency.3)The polycentricity index has a nonlinear impact on carbon emissions and carbon emission efficiency:no significant effect when below 0.50 or above 0.55,increased carbon emissions in 0.50-0.53,and reduced carbon emissions with improved efficiency in 0.53-0.55.4)The polycentricity index has an interaction effect with other variables;specifically,when the polycentricity index is between 0.53 and 0.55,its interaction with urban gross domestic product(GDP),urban population,urban built-up area,green coverage rate in built-up areas,urban technological expenditure,and the proportion of the output value of the secondary industry will reduce carbon emissions and improve carbon emission efficiency.These findings enhance the understanding of urban spatial structures and carbon emissions,providing valuable insights for policymakers in developing green and low-carbon strategies.
基金supported by the Yunnan Fundamental Research Projects(Grant Nos.202401AU070163 and 202501AT070298)the Yunnan Engineering Research Center Innovation Ability Construction and Enhancement Projects(Grant No.2023-XMDJ-00617107)+5 种基金the University Service Key Industry Project of Yunnan Province(Grant No.FWCY-ZD2024005)the Expert Workstation Support Project of Yunnan Province(Grant No.202405AF140069)the Scientific Research Foundation of Kunming University of Science and Technology(Grant No.20220122)the Analysis and Test Foundation of Kunming University of Science and Technology(Grant No.2023T20220122)the Natural Science Foundation of Inner Mongolia Autonomous Region of China(Grant No.2025QN02057)the Ordos City Strategic Pioneering Science and Technology Special Program for New Energy(Grant No.DC2400003365).
文摘Lithium metal batteries(LMBs)have been regarded as one of the most promising alternatives in the post-lithium battery era due to their high energy density,which meets the needs of light-weight electronic devices and long-range electric vehicles.However,technical barriers such as dendrite growth and poor Li plating/stripping reversibility severely hinder the practical application of LMBs.However,lithium nitrate(LiNO_(3))is found to be able to stabilize the Li/electrolyte interface and has been used to address the above challenges.To date,considerable research efforts have been devoted toward understanding the roles of LiNO_(3) in regulating the surface properties of Li anodes and toward the development of many effective strategies.These research efforts are partially mentioned in some articles on LMBs and yet have not been reviewed systematically.To fill this gap,we discuss the recent advances in fundamental and technological research on LiNO_(3) and its derivatives for improving the performances of LMBs,particularly for Li-sulfur(S),Li-oxygen(O),and Li-Li-containing transition-metal oxide(LTMO)batteries,as well as LiNO_(3)-containing recipes for precursors in battery materials and interphase fabrication.This review pays attention to the effects of LiNO_(3) in lithium-based batteries,aiming to provide scientific guidance for the optimization of electrode/electrolyte interfaces and enrich the design of advanced LMBs.
基金Under the auspices of Heilongjiang Provincial Natural Science Foundation of China(No.YQ2024D012),National Natural Science Foundation of China(No.42071162,42101165,42501220)。
文摘Under the background of‘the Belt and Road’and‘China-Mongolia-Russia Economic Corridor’initiatives,this paper studied the urban accessibility level,regional accessibility pattern and regional spatial effects along the Primorsky No.1 and No.2 transportation corridors.First,the evaluation of urban accessibility level with and without Primorsky No.1 and No.2 high-speed rails(HSRs)opening was conducted with two indicators,i.e.,the weighted average travel time,and the economic potential.After the evaluation,the spatial differentiation pattern of the accessibility changes with and without Primorsky No.1 and No.2 HSRs opening was performed respectively using ArcGIS.On these bases,the regional spatial effects brought by Primorsky No.1 and No.2 HSRs opening were studied.The results are as following.First,the urban accessibility level will be greatly improved by the opening of Primorsky No.1 and No.2 HSRs.All adjacent cities will be integrated into‘1 h HSR communication circle’and the whole journey will be integrated into‘4 h HSR communication circle’along Primorsky No.1 and No.2 corridors,respectively.The HSR accessibility of Primorsky No.1 corridor is stronger than that of Primorsky No.2 corridor.But the HSR accessibility improvement degree of Primorsky No.1 corridor is weaker than that of Primorsky No.2 corridor.Second,spatially,along Primorsky No.1 and No.2 corridors,the HSR accessibility level of the cities which are located in China is stronger than those cities located in Russia,showing the‘High West,Low East’patterns.The HSR accessibility improvement degree of the cities which are located in Russia and Sino-Russian border is stronger than those cities located in China,showing the‘High East,Low West’patterns.Third,Primorsky No.1 and No.2 corridors could connect the China’s‘Heilongjiang Land Sea Silk Road Economic Belt’and‘Changchun-Jilin-Tumen Development Pilot Zone’respectively,gradually involving into the development of China’s Harbin-Changchun Megalopolis.Relying on Harbin(China)and Changchun(China),Primorsky No.1 and No.2 HSRs could connect Northeast China-Beijing HSR,accelerating the diffusion of population,economy and other flows from China’s Beijing-Tianjin-Hebei Urban Agglomeration to Northeast China,and then to Russia’s Far East Federal District.Relying on Suifenhe(China)and Hunchun(China),Primorsky No.1 and No.2 HSRs could be conducive to the development of the second largest sea channels for Northeast China,creating the Northeast Asian Urban Belt,and new sea-rail intermodal pattern among China,Russia,Democratic People’s Republic of Korea,Japan and Republic of Korea.Relying on Vladivostok(Russia)and Zarubino(Russia),Primorsky No.1 and No.2 corridors could connect the‘Ice Silk Road’,building the‘Sino-Russian Northern Maritime Corridor’and‘Sino-Russian Arctic Blue Economic Areas’.
基金Supported by the National Natural Science Foundation of China(41571415,41071281)Natural Science Foundation of Jiangsu Province(BK20131078)Planning Project for Cultivation of Young Academic Leaders in"Qinglan Project"of Education Department of Jiangsu Province
文摘Based on the observation data of rainfall,vegetation,runoff and sediment yield in the experimental plots located in Hetian Town,Changting County of Fujian Province during 2007-2010,the changing characteristics and interrelation of live vegetation volume of grass,rainfall parameters,and water(soil)conservation effect RE(SE)were analyzed at four time scales of rainfall event,month,season,and year.The results showed that with the increase of time scales,the rainfall and vegetation indicators increased or decreased more or less,and the variation range of RE was small,while SEslowly decreased.The mean REchanged by 10%-20% at different time scales,and the observed water conservation effect of the grassland was the best at season scale while the worst at year scale.The soil conservation effect of the grassland was the best at month scale and the worst at season scale.The water conservation effect of the grass was mainly controlled by rainfall factors,including rainfall duration and precipitation at rainfall event scale,and the maximum intensity of precipitation within 30 min at longer time scales.However,the soil conservation effect of the grass was mainly controlled by vegetation factors,including the contribution of the litter on soil surface at rainfall event scale,the interaction of rainfall and vegetation at month and season scales,and the live vegetation volume of the grass at year scale.Consequently,at different time scales,the factors influencing water and soil conservation changed and interacted,and the observed water and soil conservation effects were also different,indicating that the influence of time scales deserves attention in both research and management practices.
基金The authors acknowledge financial supports from National Natural Science Foundation Project of China(Grant No.11402076)Natural Science Foundation Project for Jiangsu Province(Grant No.BK20130841)+5 种基金China Postdoctoral Science Foundation Funded Project(Grant Nos.2014M560385 and 2015T80493)the Open Research Fund of State Key Laboratory of Structural Analysis for Industrial Equipment(Grant No.GZ1405)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(Grant No.IWHR-SKL-201511)the Open Research Fund of Jiangsu Key Laboratory of Construction Materials(Grant No.CM2014-03)Jiangsu Postdoctoral Science Foundation Project(Grant No.1402053C)Research Special of the China Institute of Water Resources and Hydropower Research(Grant No.KY1640).
文摘Understanding the excluded volume of anisotropic particle is of great importance in the evaluation of continuum percolation and random packing behaviors of soft/hard particle systems in heterogeneous disordered media.In this work,we obtain the excluded volumes of several anisotropic convex particles including prolate spheroids,oblate spheroids,spherocylinders,and Platonic particles,using theoretical and numerical approaches.According to the second virial coefficient,we first present a theoretical scheme for determining the excluded volumes of anisotropic particles.Also,the mean tangent diameters of anisotropic convex particles are formulated by the quantitative stereology.Subsequently,Monte Carlo simulations are demonstrated to numerically evaluate the excluded volumes.The theoretical results of the dimensionless excluded volume are thereafter compared with that of the numerical results to verify the validity of the theoretical scheme.We further investigate the dependence of the dimensionless excluded volume on the geometric characteristics of anisotropic particles based on the proposed theoretical and numerical schemes.Results show that the dimensionless excluded volume mainly relies on the shape and surface information of anisotropic particles.The developed theoretical and numerical schemes can provide theoretical insights into the percolation threshold and packing density of soft/hard anisotropic particle systems in heterogeneous materials,physics,and chemistry fields.
基金supported by National Natural Science Foundation of China (NSFC) projects (41703012)Qinghai Science and Technology projects (2018-ZJ-956Q)+2 种基金the supports of the Strategic Priority Research Program (B) of CAS (XDB18010100, XDB41000000)pre-research Project on Civil Aerospace Technologies No. D020202 funded by the Chinese National Space AdministrationNSFC projects (41530210)。
文摘To investigate equilibrium mercury(Hg)and lead(Pb)isotope fractionation caused by the nuclear volume effect(NVE)in crystals,the electron densities at nuclei(i.e.,|Ψ(0)|2)for Hg-or Pb-bearing crystalline compounds were investigated by using the relativistic spin orbit zeroth-order regular approximation(ZORA)method with a three-dimensional periodic boundary condition based on the density functional theory(DFT).Many isotope fractionation factors of crystalline compounds are provided for the first time.Our results show,even at1000℃,NVE-driven Hg and Pb isotope fractionation are meaningfully large,i.e.,range from 0.12‰to 0.49‰(202Hg/^(198)Hg),from-0.20‰to 0.17‰(208Pb/^(206)Pb)and from-0.08‰to 0.06‰(207Pb/^(206) Pb)relative to Hg0 vapor and Pb0 vapor,respectively.Specifically,the fractionations range from-0.06‰to-0.20‰(208Pb/^(206)Pb)and from-0.02‰to-0.08‰(207Pb/^(206)Pb)for Pb2+-bearing species,from 0.10‰to 0.17‰(208Pb/^(206)Pb)and from 0.04‰to 0.06‰(207Pb/^(206)Pb)for Pb4+-bearing species in crystals.All calculated Hg-bearing species in crystals will enrich heavier isotope(202Hg)relative to Hg0 vapor.Meanwhile,Pb4+-bearing species enrich heavier Pb isotopes(208Pb and 207Pb)than Pb^(2+)-bearing species in crystals,which the enrichment can be up to 0.37‰(208-Pb/^(206)Pb)and 0.14‰(207Pb/^(206)Pb)at 1000℃,due to their NVEs are in opposite directions.The NVE-driven MIFs of Hg isotopes,which are compared to the Hg202-Hg198baseline,are up to-0.158‰(ΔNV199Hg),-0.024‰(ΔNV200Hg)and-0.094‰(ΔNV201Hg)relative to Hg0 vapor at5000 C.For all studied Hg-bearing species in crystals,the MIFs of two odd-mass isotopes(i.e.,ΔNV199Hg andΔNV201Hg)will be changed proportionally and their ratio(i.e.,ΔNV199Hg/ΔNV201Hg)will be a constant 1.67.The NVE can also cause mass-independent fractionations for 207Pb and 204 Pb compared to the baseline of 208Pb and 206Pb.The largest NVEdriven MIFs are 0.043‰(ΔNV207Pb)and-0.040‰(ΔNV204Pb)among all the studied species relative to Pb0 vapor at 5000 C.The magnitudes of odd-mass isotope MIF(ΔNV207Pb)and even-mass isotope MIF(ΔNV204Pb)are almost the same but with opposite signs,leading to the MIF ratio of them(i.e.,ΔNV207Pb/ΔNV204Pb)is-1.08.
基金Project supported by the National Natural Science Foundation of China(Grant No.71001047)the Natural Science Foundation of Inner Mongolia,China(Grant No.2010BS1001)the Program of Higher-Level Talents of Inner Mongolia University,China(Grant No.Z20090113)
文摘We propose a pedestrian position update rule, which is added to a microscopic pedestrian model to avoid pedestrian overlap. In the rule, the step size of a pedestrian moving in a selected direction at each update is in inverse proportion to the repulsive actions imposed by other pedestrians moving in a direction with an exponential rate. The positions of the pedestrians are then updated in each small time interval. In this way, a barrier between the pedestrians can be generated, and after updating their positions the pedestrians do not overlap with each other. The modified model is compared to the original model through a simulation of the evacuation process of pedestrians in a closed area. The simulation results indicate that the modified model is superior to the original model in several aspects.
基金Supported by the China National Science and Technology Major Project (2017ZX05013-001)CNPC Science and Technology Major Research Project (2018B-4907)
文摘To evaluate the fracturing effect and dynamic change process after volume fracturing with vertical wells in low permeability oil reservoirs, an oil-water two-phase flow model and a well model are built. On this basis, an evaluation method of fracturing effect based on production data and fracturing fluid backflow data is established, and the method is used to analyze some field cases. The vicinity area of main fracture after fracturing is divided into different stimulated regions. The permeability and area of different regions are used to characterize the stimulation strength and scale of the fracture network. The conductivity of stimulated region is defined as the product of the permeability and area of the stimulated region. Through parameter sensitivity analysis, it is found that half-length of the fracture and the permeability of the core area mainly affect the flow law near the well, that is, the early stage of production;while matrix permeability mainly affects the flow law at the far end of the fracture. Taking a typical old well in Changqing Oilfield as an example, the fracturing effect and its changes after two rounds of volume fracturing in this well are evaluated. It is found that with the increase of production time after the first volume fracturing, the permeability and conductivity of stimulated area gradually decreased, and the fracturing effect gradually decreased until disappeared;after the second volume fracturing, the permeability and conductivity of stimulated area increased significantly again.
基金Japanese Ministry of Education, Science, Sports and Culture!Grantin-Aid for Scientific Research (B)(2) 08455287
文摘A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.
基金supported by the National Natural Science Foundation of China(No.51771044)Natural Science Foun-dation of Hebei Province(No.E2019501061)+2 种基金the Fundamental Research Funds for the Central Universities(No.N2023027)Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)the LiaoNing Revitalization Talents Program(No.XLYC1802023).
文摘The effects of Co and Fe co-doping Ni-Mn-In alloy on the phase stability,lattice parameters,mag-netic properties,and electronic structures are systematically investigated by using the first-principles calculations.Results indicate that Fe atoms replace the excess Mn2 atoms by direct and indirect coex-istence(Fe→Mn 2 and Fe→In→Mn2);Co substitutes the Ni atoms by direct substitution(Co→Ni)for the Ni-Mn-In alloy.The austenites all exhibit the ferromagnetic(FM)state for the studied composi-tions.The NM martensites are in the ferrimagnetic(FIM-1)state for the Ni_(2)Mn_(1.5)In_(0.5),Ni_(2)Mn_(1.25)In_(0.5)Fe 0.25,Ni_(1.75)Mn_(1.5)In_(0.5)Co_(0.25),and Ni_(1.75)Mn_(1.25)In_(0.5)Co_(0.25)Fe 0.25 alloys,while the other compositions are in the FM state.The phase stability of austenite and martensite decreases with increasing Co and Fe co-doping.A magnetic-structural coupling transition occurs at x<0.25 and y<0.25.The Ni_(1.91)Mn_(1.5)In_(0.5)Co_(0.08)and Ni_(1.91)Mn_(1.42)In_(0.5)Co_(0.08)Fe_(0.08)alloys exhibit an A→6M→NM transformation,accompanied by a magnetic transition.When Co and Fe are co-doped,the hybridization strength between Co and Fe is greater than that between Co/Fe and Mn.The enhancement of magnetocaloric and elastocaloric effects is favored by larger magnetization difference(△M)and lattice volume change(△V/V_(0)).Based on the calculated phase stability,magneto-structure coupling,△V/V 0 and c/a ratio,one can predict that the Ni_(2)-x Mn_(1.5)-y In_(0.5)Co x Fe y alloy with Co content 0≤x≤0.25 and Fe content 0≤y≤0.05 is predicted to have good magneto-controlled functional behavior.
文摘Hippocampal volume loss is an important biomarker in distinguishing subjects with Alzheimer＇s disease （AD） and its measurement in magnetic resonance images （MRI） is influenced by partial volume effects （PVE）. This paper describes a post-processing approach to quantify PVE for correction of the hippocampal volume by using a spatial fuzzyC-means （SFCM） method. The algorithm is evaluated on a dataset of 20 T1-weighted MRI scans sampled at two different resolutions. The corrected volumes for left and right hippocampus （HC） which are 23% and 18% for the low resolution and 6% and 5% for the high resolution datasets, respectively are lower than hippocampal volume results from manual segmentation. Results show the importance of applying this technique in AD detection with low resolution datasets.
基金This paper is supported by Chinese NSF project(42130114)the strategic priority research program(B)of CAS(XDB41000000)the pre-research Project on Civil Aerospace Technologies No.D020202 funded by Chinese National Space Administration(CNSA)。
文摘It is well-known that the equilibrium isotope fractionation of mercury(Hg)includes classical massdependent fractionations(MDFs)and nuclear volume effect(NVE)induced mass-independent fractionations(MIFs).However,the effect of the NVE on these kinetic processes is not known.The total fractionations(MDFs+NVEinduced MIFs)of several representative Hg-incorporated substances were selected and calculated with ab initio calculations in this work for both equilibrium and kinetic processes.NVE-induced MIFs were calculated with scaled contact electron densities at the nucleus through systematic evaluations of their accuracy and errors using the Gaussian09 and DIRAC19 packages(named the electron density scaling method).Additionally,the NVE-induced kinetic isotope effect(KIE)of Hg isotopes are also calculated with this method for several representative Hg oxidation reactions by chlorine species.Total KIEs for 202 Hg/^(198)Hg ranging from−2.27‰to 0.96‰are obtained.Three anomalous^(202)Hg-enriched KIEs(δ^(202)Hg/^(198)Hg=0.83‰,0.94‰,and 0.96‰,)caused by the NVE are observed,which are quite different from the classical view(i.e.,light isotopes react faster than the heavy ones).The electron density scaling method we developed in this study can provide an easier way to calculate the NVE-induced KIEs for heavy isotopes and serve to better understand the fractionation mechanisms of mercury isotope systems.
基金supported by the National Natural Science Foundation of China(No.52376021).
文摘Current transient analysis predominantly relies on zero-dimensional/one-dimensional tools,proficient at capturing aerothermodynamic variations across critical engine stations but insufficient for analyzing the internal flow field evolution during transients.Addressing this gap,the study presents an enhanced quasi-three dimensional(quasi-3D)transient simulation technique that integrates component volume effects,offering a significant leap from the preceding quasi-3D transient simulation method based on quasi-steady assumption.By embedding the component volume effects on density,momentum,and energy within the physical temporal dimension of the Navier-Stokes equations,the refined quasi-3D transient model achieves a closer representation of physical phenomena.Validation against a single-shaft turbofan engine’s experimental data confirms the model’s accuracy.Average errors for key performance indicators,including shaft speed,thrust,mass flow rate,and critical component exit temperature and pressure,remain below 0.41%,5.69%,2.55%,3.18%and 0.67%,respectively.Crucially,the model exposes a discernible temporal lag in the compressor outlet pressure and temperature response due to volume effects—previously unquantified in quasi-3D transient simulations.And further exploration of the meridional flow field emphasizes the consequential role of volumes in transient flow field evolution.Incorporating volume effects within quasi-3D transient simulations enhances engine modeling and is pivotal for precise transient analysis in engine design and optimization.
