Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied usin...Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied using high-pressure mercury injection(HPMI),low-pressure nitrogen adsorption(LPGA-N2),and scanning electron microscopy(SEM)test methods.Based on the Frankel,Halsey and Hill(FHH)fractal theory,the Menger sponge model,Pores and Cracks Analysis System(PCAS),pore volume complexity(D_(v)),coal surface irregularity(Ds)and pore distribution heterogeneity(D_(p))were studied and evaluated,respectively.The effect of three fractal dimensions on the gas adsorption ability was also analyzed with high-pressure isothermal gas adsorption experiments.Results show that pore structures within these coal samples have obvious fractal characteristics.A noticeable segmentation effect appears in the Dv1and Dv2fitting process,with the boundary size ranging from 36.00 to 182.95 nm,which helps differentiate diffusion pores and seepage fractures.The D values show an asymmetric U-shaped trend as the coal metamorphism increases,demonstrating that coalification greatly affects the pore fractal dimensions.The three fractal dimensions can characterize the difference in coal microstructure and reflect their influence on gas adsorption ability.Langmuir volume(V_(L))has an evident and positive correlation with Dsvalues,whereas Langmuir pressure(P_(L))is mainly affected by the combined action of Dvand Dp.This study will provide valuable knowledge for the appraisal of coal seam gas reservoirs of differently ranked coals.展开更多
The purpose of this paper is to revisit theoretical positions on gender and the implications for gender in management by building upon current research on doing gender well and re-doing or undoing gender and argue tha...The purpose of this paper is to revisit theoretical positions on gender and the implications for gender in management by building upon current research on doing gender well and re-doing or undoing gender and argue that gender can be done well and differently through simultaneous,multiple enactments of femininity and masculinity.展开更多
Tungsten(W)is an important material in tokamak walls and divertors.The W ion charge state distribution and the dynamic behavior of ions play important roles in the investigation of plasma–wall interactions using lase...Tungsten(W)is an important material in tokamak walls and divertors.The W ion charge state distribution and the dynamic behavior of ions play important roles in the investigation of plasma–wall interactions using laser-ablation-based diagnostics such as laser-induced breakdown spectroscopy and laser-induced ablation spectroscopy.In this work,we investigate the temporal and spatial evolutions of differently charged ions in a nanosecond-laser-produced W plasma in vacuum using time-of-flight mass spectroscopy.Ions with different charge states from 1 to 7(W+to W7+)are all observed.The temporal evolutions of the differently charged ions show that ions with higher charge states have higher velocities,indicating that space separation occurs between the differently charged ion groups.Spatially-resolved mass spectroscopy measurements further demonstrate the separation phenomenon.The temporal profile can be accurately fitted by a shifted Maxwell–Boltzmann distribution,and the velocities of the differently charged ions are also obtained from the fittings.It is found that the ion velocities increase continuously from the measured position of 0.75 cm to 2.25 cm away from the target surface,which indicates that the acceleration process lasts through the period of plasma expansion.The acceleration and space separation of the differently charged ions confirm that there is a dynamic plasma sheath in the laser-produced plasma,which provides essential information for the theoretical laser-ablation model with plasma formation and expansion.展开更多
The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb1.8Mo2Si13B9.5 alloy was investigated by using Mssbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed...The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb1.8Mo2Si13B9.5 alloy was investigated by using Mssbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed at temperatures between 480℃ and 600℃ for 0.5 h. The experimental results show that the microstructure mainly consists of the nanoscale bcc α-Fe(Si) grains and the residual amorphous matrix phase. A trace paramagnetic phase was found for annealing about above 500℃. The volume fraction of cr-Fe(Si) grain increases with increasing annealing temperature, whereas the average size of grain is almost unchanged above 480℃ up to 580℃. The calculated thickness of the intergranular layer of the residual amorphous matrix clearly decreases with increasing annealing temperature.展开更多
2-Acryloxyacetophenone （AAP） was prepared and subjected to suspension polymerization with methyl methacrylate （MMA） using azobisisobutyronitrile （AIBN） as free radical initiator. The differently sulfonated AAP-M...2-Acryloxyacetophenone （AAP） was prepared and subjected to suspension polymerization with methyl methacrylate （MMA） using azobisisobutyronitrile （AIBN） as free radical initiator. The differently sulfonated AAP-MMA cross-linked copolymer cationic exchange resins were prepared by sulfonation with concentrated sulphuric acid at 70 ~C. Several characteristics of the prepared resins were evaluated, i.e. FTIR, the ion-exchange capacity （IEC）, thermo gravimetric analysis （TGA）, particle size distribution and microscopic morphology. The resin characteristics were altered with degree of sulfonation, providing that differently sulfonated resins could be prepared. The behavior of atenolol （ATL） loading and in vitro release in the USP stimulated gastric and intestinal fluids of the obtained resins were evaluated. The drug loaded in the resin increased with increasing degree of sulfonation and hence the drug binding site in resin employed. The drug release was lower from the resins with higher content of sulfonic group due to the increase in the diffusive path depth. The drug release was a little lower in stimulated gastric fluid （SGF） than in stimulated intestinal fluids （SIF）. The basic groups, ionized to a little greater extent in SGF and preferred binding with the resin rather than releasing. Hence, the differently sulfonated resins could be utilized as novel carriers for drug delivery.展开更多
The single-event susceptibility of three silicon carbide(SiC)metal-oxide-semiconductor field-effect transistor(MOSFET)power devices structures(planar,trench and double trench)is researched by the technology computer-a...The single-event susceptibility of three silicon carbide(SiC)metal-oxide-semiconductor field-effect transistor(MOSFET)power devices structures(planar,trench and double trench)is researched by the technology computer-aided design(TCAD)simulation.Comparative analysis of the heavy-ion irradiation effects on three device structures reveals distinct susceptibility characteristics.The gate oxide region is identified as the most sensitive position in planar devices,while trench and doubletrench structures exhibit no localized sensitive regions.Furthermore,the single-event susceptibility demonstrates strong depth dependence across all three structures,with enhanced vulnerability observed at greater ion penetration depths.展开更多
In this paper,the growth characteristic of meromorphic solutions for the following difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=0 with no dominating coefficient is studied.By imposing certain restriction o...In this paper,the growth characteristic of meromorphic solutions for the following difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=0 with no dominating coefficient is studied.By imposing certain restriction on the entire coefficients associated with Petrenko's deviation of the above equation,we obtain some results and partially address a question posed byⅠ.Laine and C.C.Yang.Furthermore,for the entire solutions f(z)of the difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=F(z),where Aj(z)(j=0,…,n),F(z)are entire functions,we discover a close relationship between the measure of common transcendental directions associated with classical difference operators of f(z)and Petrenko's deviations of the coefficients.展开更多
Migratory divides,where individuals from distinct breeding populations within a species exhibit divergent migratory routes and strategies,play a critical role in shaping avian ecology and evolution.These divides can d...Migratory divides,where individuals from distinct breeding populations within a species exhibit divergent migratory routes and strategies,play a critical role in shaping avian ecology and evolution.These divides can drive intraspecific genetic divergence and promote reproductive isolation,potentially leading to population differentiation and speciation.Understanding the migration strategies of populations utilizing distinct flyways is essential not only for elucidating the mechanisms underlying migration patterns but also for informing effective species conservation efforts.From 2014 to 2023,we used satellite tracking to monitor the migration patterns of 87 White-naped Cranes(Antigone vipio)from the species'two breeding populations—western(Mongolia)and eastern(Songnen Plain,China).We delineated their migratory routes,quantified key migration parameters,and identified their population-and season-specific differences in migratory strategies.Our results indicate that the Greater Khingan Mountains and the Bohai-Yellow Sea formed a distinct migratory barrier separating the eastern and western populations.Significant differences in migration strategies were observed between populations and seasons.The western population adopts a"longer-distance,slower-speed,more-stopover"strategy,while the eastern population employs a"shorter-distance,higher-speed,fewer-stopover"strategy.Our study identifies the migratory divides between the two populations of White-naped Cranes and highlights the importance of migratory divides in shaping distinct migration strategies.These findings enhance our understanding of the factors driving population-specific migration strategies and provide a foundation for tailored conservation efforts for these populations.展开更多
Background:Depression is a growing public health concern among Chinese children and adolescents,with substantial healthcare costs.Physical activity(PA)and organized sport are modifiable behaviours protective against d...Background:Depression is a growing public health concern among Chinese children and adolescents,with substantial healthcare costs.Physical activity(PA)and organized sport are modifiable behaviours protective against depression.This study,therefore,estimated the healthcare costs of depression attributable to insufficient PA and organized sport participation.Methods:A cost-of-illness approach with population attributable fraction(PAF)was applied.Relative risks were derived from longitudinal evidence,prevalence estimates from national Chinese surveys,and depression case numbers from the Global Burden of Disease 2021.Direct healthcare costs were extrapolated from European Union estimates,adjusted to 2024 US dollars(USD),and Chinese expenditure.Sex-stratified analyses were conducted.Results:Estimated depression-related healthcare costs attributable to insufficient PA were approximately 81 million USD,compared with around 84 million USD attributable to insufficient organized sport participation.At the population level,the economic burden attributable to insufficient PA and organized sport was of a similar order of magnitude.Among boys,costs attributable to insufficient organized sport participation(approximately 57 million USD)exceeded those attributable to insufficient PA(around 39 million USD),whereas among girls,costs attributable to insufficient PA(approximately 42 million USD)were higher than those related to organized sport(around 27 million USD).These sex-specific patterns were consistent across sensitivity analyses examining uncertainty in key model parameters.Conclusions:Both insufficient PA and organized sport contribute substantially to depression-related healthcare costs,with sex-specific differences.Policies should prioritise promoting overall PA in girls and organized sport in boys to reduce depression burden and associated expenditures.The magnitude of these attributable costs indicates an economically meaningful burden that is potentially modifiable through behavioural interventions.展开更多
Background:Exposure to environmental vulnerability poses significant threats to adolescent suicidal ideation,while individual resilience can mitigate these adverse effects with notable gender commonalities and differe...Background:Exposure to environmental vulnerability poses significant threats to adolescent suicidal ideation,while individual resilience can mitigate these adverse effects with notable gender commonalities and differences.However,research examining how these factors co-configure at the individual level remains limited,particularly from a gender-specific perspective.Thus,the present study aims to adopt a person-centered analytic approach to identify gender-specific configurations of environmental vulnerability and individual resilience associated with suicidal ideation among Chinese adolescents.Methods:Data were collected from 2616 Chinese primary and secondary school students(aged 10–17;1223 girls).Participants completed validated scales measuring environmental vulnerability,individual resilience,and suicidal ideation.Latent profile analysis(LPA)was conducted separately by gender.Results:Gender differences were prominent:males exhibited higher resilience and lower suicidal ideation,while females reported higher environmental vulnerability and elevated levels of suicidal ideation.LPA identified three distinct profiles for males:Low Vulnerable–High Protective–Low Risk(LHL),Medium Vulnerable–Low Protective–Low Risk(MLL),and High Vulnerable–Low Protective–High Risk(HLH).Four profiles emerged for females:LHL,MLL,Medium Vulnerable–Low Protective–Medium Risk(MLM),and HLH.Crucially,within the HLH profile,males exhibited particularly deficient humor(η^(2)=0.19)and confidence(η^(2)=0.16),while females formed a distinct subgroup characterized by severe academic and family stressors(η^(2)=0.30–0.36).Conclusion:The study underscores developing gender-specific mental health interventions using a nuanced,person-centered approach that considers both environmental risk and individual resilience factors,which allows for targeted suicide prevention strategies addressing the unique needs of male and female adolescents.展开更多
Urban populations are increasingly exposed to extreme heat due to climate change and rapid urbanization,heightening health risks in cities worldwide.Accurate heat exposure assessment is essential for public health pla...Urban populations are increasingly exposed to extreme heat due to climate change and rapid urbanization,heightening health risks in cities worldwide.Accurate heat exposure assessment is essential for public health planning and risk reduction.Most existing approaches rely on a single threshold temperature(e.g.,35℃of daily max temperature),applied uniformly to the entire population.However,this one-size-fits-all assumption overlooks substantial differences in heat sensitivity across population subgroups.In this study,we address this limitation by quantifying subgroup-specific temperature-mortality relationships and using corresponding minimum mortality temperatures(MMTs)to assess heat exposure.Results show that the population-wide MMT was 27.5℃,but it varied greatly across population subgroups.The elderly population(≥65)had an MMT of 24.6℃,much lower than the 28.6℃observed in younger individuals(<65).Females also exhibited a lower MMT that males(25℃versus 28.2℃).However,educational attainment did not significantly affect MMT.Using a uniform MMT resulted in substantial underestimation of heat exposure,ranging from 25.3%in 1990 to 13.9%in 2020,reflecting demographic shifts over time.Spatially,nearly half of the city experienced underestimated heat risk,especially in central and northeastern regions where heat-vulnerable populations are concentrated.These findings underscore the need for more nuanced heat exposure assessments that account for demographic and spatial variability,paving the way for targeted public health interventions to protect the most vulnerable urban populations.展开更多
In the study of thin-walled wedge shells subjected to lateral water entry impact loads,similarity theory is employed to predict the behavior of the prototype by analyzing the dynamic response of the model.However,the ...In the study of thin-walled wedge shells subjected to lateral water entry impact loads,similarity theory is employed to predict the behavior of the prototype by analyzing the dynamic response of the model.However,the traditional similarity law for structural impact fails to accurately describe the relationship between the dynamic responses of the model and the prototype,mainly due to the ignoring of the fluid-structure coupling effect and geometric distortion in the thickness direction.To address this limitation,this study employs dimensional analysis to derive the scaling factors for achieving structural similarity during water entry while considering the effects of fluid-structure coupling.Based on the analysis of the governing equations for thin-walled wedge shells under water entry impact loads,the scaling factor accounting for geometric distortion for water entry of wedge shells is determined.Numerical models are established to verify the applicability of the geometric distortion similarity model with different materials.The results demonstrate the effectiveness of the proposed similarity model,which significantly reduces the disparities in displacement peaks and energy between the scaled model and the prototype.In addition,experimental platforms are constructed to further verify the proposed similarity model by performing vertical water entry tests on thickness-distorted and material-distorted specimens.展开更多
To examine the impact of anthropogenic land reconstruction,particularly the consolidation of small terraces into larger fields,on soil organic carbon(SOC),total nitrogen(TN)dynamics,rice yield,and its components,soil ...To examine the impact of anthropogenic land reconstruction,particularly the consolidation of small terraces into larger fields,on soil organic carbon(SOC),total nitrogen(TN)dynamics,rice yield,and its components,soil and plant samples were collected from seven newly reconstructed fields in Japanese Andosols in Tochigi,Japan.Samples were obtained from both the former low-and high-elevation sides within each field plot.During harvest season,nine rice plants were randomly selected from each plot(0.675 m^(2),comprising 3 rows and 3 hills per row),collected from a 3-m stretch along both the east(former low side)and west(former high side)ridges.Soil cores were collected from identical plots at two depths(0–15 and 15–30 cm)and combined into one composite sample per layer.Rice plant samples were air-dried for two weeks until reaching constant moisture content,after which stems and ears were separated and weighed to determine biomass,yield,yield components,and nitrogen uptake.This indicated that land reconstruction significantly affected rice yield and its components between the two sides of all field plots.SOC,TN,and their decomposition following land reconstruction showed notable changes,especially in the 15–30 cm subsurface soil layer.Additionally,grain weight demonstrated significant correlation with SOC,TN,and carbon decomposition in both the 0–15 and 15–30 cm layers,indicating that soil fertility to a depth of 30 cm was crucial for rice productivity after land reconstruction.展开更多
In our study,we tackle a linear advection-diffusion equation that varies with time and is constrained to one dimension,under the framework of homogeneous Dirichlet boundary conditions.We employ two distinct approaches...In our study,we tackle a linear advection-diffusion equation that varies with time and is constrained to one dimension,under the framework of homogeneous Dirichlet boundary conditions.We employ two distinct approaches for solving this equation:an analytical solution through the method of separation of variables,and a numerical solution utilizing the finite difference method.The computational output includes three dimensional(3D)plots for solutions,focusing on pollutants such as Ammonia,Carbon monoxide,Carbon dioxide,and Sulphur dioxide.Concentrations,along with their respective diffusivities,are analyzed through 3D plots and actual calculations.To comprehend the diffusivity-concentration relationship for predicting pollutant movement in the air,the domain is divided into two halves.The study explores the behavior of pollutants with higher diffusivity entering regions with lower diffusivity,and vice versa,using 2D and 3D plots.This task is crucial for effective pollution control strategies,and safeguarding the environment and public health.展开更多
In this study, the ground potential rise(GPR) phenomenon caused by a lightning current injected into a field-shaped artificial grounding grid, as well as the potential difference between two different nodes at the edg...In this study, the ground potential rise(GPR) phenomenon caused by a lightning current injected into a field-shaped artificial grounding grid, as well as the potential difference between two different nodes at the edge of the grounding grid, was observed and analyzed under artificially triggered lightning conditions. Based on circuit theory and measured current data, a π-equivalent circuit was established to simulate the transient response of the grounding grid.Nineteen return strokes from three artificially triggered lightning events were analyzed. The peak currents of the 19 return strokes range from -6.7 to -25.1 kA, and the mean value was -14.3 kA. The GPR decreased rapidly and formed a subpeak after reaching the initial peak, with the mean value of the initial peak being -148.65 kV and the mean value of the subpeak being -92.87 kV. The GPR induced by the triggered lightning currents exhibited a subpeak phenomenon. Simulation results indicate that the subpeak phenomenon is related to localized corrosion of the vertical grounding electrode. The potential difference at the grounding grid edge exhibited a multi-pulse waveform with alternating polarity, dominated by positive pulses. The peak values of both the positive and negative polarity pulses gradually decreased, with the first positive pulse displaying a significantly higher intensity than that of subsequent pulses.展开更多
Imidazole(IM)particles in the atmosphere affect climate,atmospheric chemical reactions,and human health.However,research on IM particles in the Sichuan Basin(SCB),one of the areas of China affected most heavily by haz...Imidazole(IM)particles in the atmosphere affect climate,atmospheric chemical reactions,and human health.However,research on IM particles in the Sichuan Basin(SCB),one of the areas of China affected most heavily by haze,remains very scarce.This study used single-particle aerosol mass spectrometry to investigate IM-containing particles in Chengdu,one of the megacities in the SCB,during summer and winter before and after implemen-tation of the Three-year Action Plan to Win the Blue-Sky Defense War(BSDW).We found that IM-containing particles accounted for 1.2%–12.0%of all detected particles,and they highly mixed with carbonaceous com-ponents,secondary inorganic species,and organic nitrogen.From before to after the BSDW,the proportion of IM-containing particles decreased by 1.8%in summer,but increased by 9.6%in winter.Ammonium/amines and carbonyl compounds were closely related to IM-containing particles;the highest proportion of IM-containing particles occurred in particles mixed with amines and carbonyls.The number fraction of IM-containing particles in all seasons was higher at night than during daytime.The potential source areas of IM-containing particles showed notable narrowing after the BSDW,and the high-value areas were found distributed closer to Chengdu and its surrounding areas.In the winter before the BSDW,most IM-containing particles(>70%)were mixed with organic carbon(OC)particles,and the contributions of OC and mixed organic–elemental carbon(OC-EC)particles increased with aggravation of pollution,whereas OC-EC and Metal particles played a more crucial role in the winter after the BSDW.展开更多
Rechargeable alkali metal-sulfur(M-S)batteries,including Li/Na/K-S chemistries,have the potential to utilize abundant and low-cost sulfur cathodes yet offer high theoretical energy densities.However,their practical el...Rechargeable alkali metal-sulfur(M-S)batteries,including Li/Na/K-S chemistries,have the potential to utilize abundant and low-cost sulfur cathodes yet offer high theoretical energy densities.However,their practical electrochemical performance is fundamentally limited by the polysulfide shuttle effect.This challenge is particularly exacerbated in Na-S and K-S systems owing to larger metal-ion radii,weaker solvation energies,slower redox kinetics,and greater electrolyte-electrode incompatibilities compared to Li-S batteries.This review presents a comparative analysis of interface engineering strategies designed to suppress the shuttle effect across these three systems.Following a summary of sulfur cathode properties and reaction mechanisms,we systematically examine the origins of polysulfide shuttling.Our analysis progresses from functional separator design and interlayer enhancements to the implementation of solid-state electrolytes for root-cause inhibition.By evaluating interface engineering research specific to Na-S and K-S batteries,we elucidate both shared principles and unique challenges inherent to alkali M-S systems.Finally,we propose multifaceted solutions to achieve shuttlefree operation and enhance overall battery performance,thereby establishing a foundation for future advancements.展开更多
Quasi-periodic solutions with multiple base frequencies exhibit the feature of 2π-periodicity with respect to each of the hyper-time variables.However,it remains a challenge work,due to the lack of effective solution...Quasi-periodic solutions with multiple base frequencies exhibit the feature of 2π-periodicity with respect to each of the hyper-time variables.However,it remains a challenge work,due to the lack of effective solution methods,to solve and track the quasi-periodic solutions with multiple base frequencies until now.In this work,a multi-steps variable-coefficient formulation is proposed,which provides a unified framework to enable either harmonic balance method or collocation method or finite difference method to solve quasi-periodic solutions with multiple base frequencies.For this purpose,a method of alternating U and S domain is also developed to efficiently evaluate the nonlinear force terms.Furthermore,a new robust phase condition is presented for all of the three methods to make them track the quasi-periodic solutions with prior unknown multiple base frequencies,while the stability of the quasi-periodic solutions is assessed by mean of Lyapunov exponents.The feasibility of the constructed methods under the above framework is verified by application to three nonlinear systems.展开更多
To improve the penetration of thick plates,a laser-enhanced plasma arc welding process was developed.However,the current understanding of laser absorption and energy transfer mechanisms is still unclear,limiting its o...To improve the penetration of thick plates,a laser-enhanced plasma arc welding process was developed.However,the current understanding of laser absorption and energy transfer mechanisms is still unclear,limiting its optimization and application.This work establishes mathematical model of this novel heat source including electron density based on the gas state equation,Saha equation,and charge conservation equation.This model reveals the laser transmission characteristics in the plasma controlled by temperature and electron density,as well as the electrical and thermal transfer from the composite arc to the base material.The simulated temperature fields,arc pressure distributions,and arc voltages showed good agreement with experimental measurements,with peak pressure errors within 50 Pa and voltage differences within 0.3 V,validating the accuracy of the model.The results showed that the laser increased the arc temperature inside the keyhole,extending the high-temperature zone downwards.The laser has altered the current density distribution at the keyhole edge,decreasing the upper part but increasing the lower part.The trend of heat flux density change is consistent with the current density.There is a high laser absorption zone in the arc between the tungsten electrode and base metal,whose position changes with laser power,thereby improving the position and axial energy distribution of the plasma arc.展开更多
基金The first author would like to express sincere appreciation for the scholarship provided by China Scholarship Council(No.202006430006)and University of Wollongongfinancially supported by the ACARP Project C28006+1 种基金the National Key Research and Development Program of China(No.2018YFC0808301)the Natural Science Foundation of Beijing Municipality,China(No.8192036)。
文摘Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied using high-pressure mercury injection(HPMI),low-pressure nitrogen adsorption(LPGA-N2),and scanning electron microscopy(SEM)test methods.Based on the Frankel,Halsey and Hill(FHH)fractal theory,the Menger sponge model,Pores and Cracks Analysis System(PCAS),pore volume complexity(D_(v)),coal surface irregularity(Ds)and pore distribution heterogeneity(D_(p))were studied and evaluated,respectively.The effect of three fractal dimensions on the gas adsorption ability was also analyzed with high-pressure isothermal gas adsorption experiments.Results show that pore structures within these coal samples have obvious fractal characteristics.A noticeable segmentation effect appears in the Dv1and Dv2fitting process,with the boundary size ranging from 36.00 to 182.95 nm,which helps differentiate diffusion pores and seepage fractures.The D values show an asymmetric U-shaped trend as the coal metamorphism increases,demonstrating that coalification greatly affects the pore fractal dimensions.The three fractal dimensions can characterize the difference in coal microstructure and reflect their influence on gas adsorption ability.Langmuir volume(V_(L))has an evident and positive correlation with Dsvalues,whereas Langmuir pressure(P_(L))is mainly affected by the combined action of Dvand Dp.This study will provide valuable knowledge for the appraisal of coal seam gas reservoirs of differently ranked coals.
文摘The purpose of this paper is to revisit theoretical positions on gender and the implications for gender in management by building upon current research on doing gender well and re-doing or undoing gender and argue that gender can be done well and differently through simultaneous,multiple enactments of femininity and masculinity.
基金supported by the National Key R&D Program of China(No.2017YFE0301304)National Natural Science Foundation of China(No.12005034)the China Postdoctoral Science Foundation(No.2019M661087)supported by the US Department of Energy,Office of Defense Nuclear Nonproliferation Research and Development,under contract number DE-AC02-05CH11231 at the Lawrence Berkeley National Laboratory。
文摘Tungsten(W)is an important material in tokamak walls and divertors.The W ion charge state distribution and the dynamic behavior of ions play important roles in the investigation of plasma–wall interactions using laser-ablation-based diagnostics such as laser-induced breakdown spectroscopy and laser-induced ablation spectroscopy.In this work,we investigate the temporal and spatial evolutions of differently charged ions in a nanosecond-laser-produced W plasma in vacuum using time-of-flight mass spectroscopy.Ions with different charge states from 1 to 7(W+to W7+)are all observed.The temporal evolutions of the differently charged ions show that ions with higher charge states have higher velocities,indicating that space separation occurs between the differently charged ion groups.Spatially-resolved mass spectroscopy measurements further demonstrate the separation phenomenon.The temporal profile can be accurately fitted by a shifted Maxwell–Boltzmann distribution,and the velocities of the differently charged ions are also obtained from the fittings.It is found that the ion velocities increase continuously from the measured position of 0.75 cm to 2.25 cm away from the target surface,which indicates that the acceleration process lasts through the period of plasma expansion.The acceleration and space separation of the differently charged ions confirm that there is a dynamic plasma sheath in the laser-produced plasma,which provides essential information for the theoretical laser-ablation model with plasma formation and expansion.
文摘The microstructure of differently annealed nanocrystalline Fe72.7Cu1Nb1.8Mo2Si13B9.5 alloy was investigated by using Mssbauer spectroscopy and transmission electron microscope. The specimens were isochronally annealed at temperatures between 480℃ and 600℃ for 0.5 h. The experimental results show that the microstructure mainly consists of the nanoscale bcc α-Fe(Si) grains and the residual amorphous matrix phase. A trace paramagnetic phase was found for annealing about above 500℃. The volume fraction of cr-Fe(Si) grain increases with increasing annealing temperature, whereas the average size of grain is almost unchanged above 480℃ up to 580℃. The calculated thickness of the intergranular layer of the residual amorphous matrix clearly decreases with increasing annealing temperature.
基金The University Grants Commission,New Delhi for its funding of this workIndian Institute of Science,Bangalore for its instrumental support+2 种基金Department of Physics,Sri Venkateswara University,Tirupathi,for its assistance in the SEM studyUGC,New Delhi for its support under SAPDST,New Delhi for its support under FIST
文摘2-Acryloxyacetophenone （AAP） was prepared and subjected to suspension polymerization with methyl methacrylate （MMA） using azobisisobutyronitrile （AIBN） as free radical initiator. The differently sulfonated AAP-MMA cross-linked copolymer cationic exchange resins were prepared by sulfonation with concentrated sulphuric acid at 70 ~C. Several characteristics of the prepared resins were evaluated, i.e. FTIR, the ion-exchange capacity （IEC）, thermo gravimetric analysis （TGA）, particle size distribution and microscopic morphology. The resin characteristics were altered with degree of sulfonation, providing that differently sulfonated resins could be prepared. The behavior of atenolol （ATL） loading and in vitro release in the USP stimulated gastric and intestinal fluids of the obtained resins were evaluated. The drug loaded in the resin increased with increasing degree of sulfonation and hence the drug binding site in resin employed. The drug release was lower from the resins with higher content of sulfonic group due to the increase in the diffusive path depth. The drug release was a little lower in stimulated gastric fluid （SGF） than in stimulated intestinal fluids （SIF）. The basic groups, ionized to a little greater extent in SGF and preferred binding with the resin rather than releasing. Hence, the differently sulfonated resins could be utilized as novel carriers for drug delivery.
基金National Key Research and Development Program of China(2023YFA1609000)National Natural Science Foundation of China(62474190,U22B2043,U2267210)。
文摘The single-event susceptibility of three silicon carbide(SiC)metal-oxide-semiconductor field-effect transistor(MOSFET)power devices structures(planar,trench and double trench)is researched by the technology computer-aided design(TCAD)simulation.Comparative analysis of the heavy-ion irradiation effects on three device structures reveals distinct susceptibility characteristics.The gate oxide region is identified as the most sensitive position in planar devices,while trench and doubletrench structures exhibit no localized sensitive regions.Furthermore,the single-event susceptibility demonstrates strong depth dependence across all three structures,with enhanced vulnerability observed at greater ion penetration depths.
基金Supported by the National Natural Science Foundation of China(Grant No.11661043)and the ScienceTechnology Research Project of Jiangxi Provincial Department of Education(Grant No.GJJ2200320).
文摘In this paper,the growth characteristic of meromorphic solutions for the following difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=0 with no dominating coefficient is studied.By imposing certain restriction on the entire coefficients associated with Petrenko's deviation of the above equation,we obtain some results and partially address a question posed byⅠ.Laine and C.C.Yang.Furthermore,for the entire solutions f(z)of the difference equation An(z)f(z+n)+…+A1(z)f(z+1)+A0(z)f(z)=F(z),where Aj(z)(j=0,…,n),F(z)are entire functions,we discover a close relationship between the measure of common transcendental directions associated with classical difference operators of f(z)and Petrenko's deviations of the coefficients.
基金supported by the National Natural Science Foundation of China(No.31770573)。
文摘Migratory divides,where individuals from distinct breeding populations within a species exhibit divergent migratory routes and strategies,play a critical role in shaping avian ecology and evolution.These divides can drive intraspecific genetic divergence and promote reproductive isolation,potentially leading to population differentiation and speciation.Understanding the migration strategies of populations utilizing distinct flyways is essential not only for elucidating the mechanisms underlying migration patterns but also for informing effective species conservation efforts.From 2014 to 2023,we used satellite tracking to monitor the migration patterns of 87 White-naped Cranes(Antigone vipio)from the species'two breeding populations—western(Mongolia)and eastern(Songnen Plain,China).We delineated their migratory routes,quantified key migration parameters,and identified their population-and season-specific differences in migratory strategies.Our results indicate that the Greater Khingan Mountains and the Bohai-Yellow Sea formed a distinct migratory barrier separating the eastern and western populations.Significant differences in migration strategies were observed between populations and seasons.The western population adopts a"longer-distance,slower-speed,more-stopover"strategy,while the eastern population employs a"shorter-distance,higher-speed,fewer-stopover"strategy.Our study identifies the migratory divides between the two populations of White-naped Cranes and highlights the importance of migratory divides in shaping distinct migration strategies.These findings enhance our understanding of the factors driving population-specific migration strategies and provide a foundation for tailored conservation efforts for these populations.
文摘Background:Depression is a growing public health concern among Chinese children and adolescents,with substantial healthcare costs.Physical activity(PA)and organized sport are modifiable behaviours protective against depression.This study,therefore,estimated the healthcare costs of depression attributable to insufficient PA and organized sport participation.Methods:A cost-of-illness approach with population attributable fraction(PAF)was applied.Relative risks were derived from longitudinal evidence,prevalence estimates from national Chinese surveys,and depression case numbers from the Global Burden of Disease 2021.Direct healthcare costs were extrapolated from European Union estimates,adjusted to 2024 US dollars(USD),and Chinese expenditure.Sex-stratified analyses were conducted.Results:Estimated depression-related healthcare costs attributable to insufficient PA were approximately 81 million USD,compared with around 84 million USD attributable to insufficient organized sport participation.At the population level,the economic burden attributable to insufficient PA and organized sport was of a similar order of magnitude.Among boys,costs attributable to insufficient organized sport participation(approximately 57 million USD)exceeded those attributable to insufficient PA(around 39 million USD),whereas among girls,costs attributable to insufficient PA(approximately 42 million USD)were higher than those related to organized sport(around 27 million USD).These sex-specific patterns were consistent across sensitivity analyses examining uncertainty in key model parameters.Conclusions:Both insufficient PA and organized sport contribute substantially to depression-related healthcare costs,with sex-specific differences.Policies should prioritise promoting overall PA in girls and organized sport in boys to reduce depression burden and associated expenditures.The magnitude of these attributable costs indicates an economically meaningful burden that is potentially modifiable through behavioural interventions.
基金supported by the Major Planning Project of Philosophy and Social Science of Guangdong Province(GD23ZD17)the Humanities and Social Sciences Program of the Ministry of Education(23YJA190006)+3 种基金the Ministry of Education(MOE)Major Project of Philosophy and Social Sciences Research(2025JZDZ024)the MOE Project of the Key Research Institute of Humanities and Social Sciences in Universities(22JJD190008)a grant from the Research Center for Brain Cognition and Human Development of Guangdong(2024B0303390003)the Psychological Services and Counseling Base for the Happy Guangzhou Project.
文摘Background:Exposure to environmental vulnerability poses significant threats to adolescent suicidal ideation,while individual resilience can mitigate these adverse effects with notable gender commonalities and differences.However,research examining how these factors co-configure at the individual level remains limited,particularly from a gender-specific perspective.Thus,the present study aims to adopt a person-centered analytic approach to identify gender-specific configurations of environmental vulnerability and individual resilience associated with suicidal ideation among Chinese adolescents.Methods:Data were collected from 2616 Chinese primary and secondary school students(aged 10–17;1223 girls).Participants completed validated scales measuring environmental vulnerability,individual resilience,and suicidal ideation.Latent profile analysis(LPA)was conducted separately by gender.Results:Gender differences were prominent:males exhibited higher resilience and lower suicidal ideation,while females reported higher environmental vulnerability and elevated levels of suicidal ideation.LPA identified three distinct profiles for males:Low Vulnerable–High Protective–Low Risk(LHL),Medium Vulnerable–Low Protective–Low Risk(MLL),and High Vulnerable–Low Protective–High Risk(HLH).Four profiles emerged for females:LHL,MLL,Medium Vulnerable–Low Protective–Medium Risk(MLM),and HLH.Crucially,within the HLH profile,males exhibited particularly deficient humor(η^(2)=0.19)and confidence(η^(2)=0.16),while females formed a distinct subgroup characterized by severe academic and family stressors(η^(2)=0.30–0.36).Conclusion:The study underscores developing gender-specific mental health interventions using a nuanced,person-centered approach that considers both environmental risk and individual resilience factors,which allows for targeted suicide prevention strategies addressing the unique needs of male and female adolescents.
基金supported by the National Natural Science Foundation of China(Grant No.42225104)CAS Project for Young Scientists in Basic Research(Grant No.YSBR-086).
文摘Urban populations are increasingly exposed to extreme heat due to climate change and rapid urbanization,heightening health risks in cities worldwide.Accurate heat exposure assessment is essential for public health planning and risk reduction.Most existing approaches rely on a single threshold temperature(e.g.,35℃of daily max temperature),applied uniformly to the entire population.However,this one-size-fits-all assumption overlooks substantial differences in heat sensitivity across population subgroups.In this study,we address this limitation by quantifying subgroup-specific temperature-mortality relationships and using corresponding minimum mortality temperatures(MMTs)to assess heat exposure.Results show that the population-wide MMT was 27.5℃,but it varied greatly across population subgroups.The elderly population(≥65)had an MMT of 24.6℃,much lower than the 28.6℃observed in younger individuals(<65).Females also exhibited a lower MMT that males(25℃versus 28.2℃).However,educational attainment did not significantly affect MMT.Using a uniform MMT resulted in substantial underestimation of heat exposure,ranging from 25.3%in 1990 to 13.9%in 2020,reflecting demographic shifts over time.Spatially,nearly half of the city experienced underestimated heat risk,especially in central and northeastern regions where heat-vulnerable populations are concentrated.These findings underscore the need for more nuanced heat exposure assessments that account for demographic and spatial variability,paving the way for targeted public health interventions to protect the most vulnerable urban populations.
基金supported by the National Natural Science Foundation of China(Grant Nos.11972309,12272320 and 12272309)the Overseas Expertise Introduction Project for Discipline Innovation(the 111 Project)(Grant No.BP0719007).
文摘In the study of thin-walled wedge shells subjected to lateral water entry impact loads,similarity theory is employed to predict the behavior of the prototype by analyzing the dynamic response of the model.However,the traditional similarity law for structural impact fails to accurately describe the relationship between the dynamic responses of the model and the prototype,mainly due to the ignoring of the fluid-structure coupling effect and geometric distortion in the thickness direction.To address this limitation,this study employs dimensional analysis to derive the scaling factors for achieving structural similarity during water entry while considering the effects of fluid-structure coupling.Based on the analysis of the governing equations for thin-walled wedge shells under water entry impact loads,the scaling factor accounting for geometric distortion for water entry of wedge shells is determined.Numerical models are established to verify the applicability of the geometric distortion similarity model with different materials.The results demonstrate the effectiveness of the proposed similarity model,which significantly reduces the disparities in displacement peaks and energy between the scaled model and the prototype.In addition,experimental platforms are constructed to further verify the proposed similarity model by performing vertical water entry tests on thickness-distorted and material-distorted specimens.
基金support of the Japanese Government(Monbukagakusho)Scholarship for his studies in Japansupported by the Yamagata University YU-COE(S)program and by the Advanced Agri-food System Research Center of Yamagata University,Japan+2 种基金financially supported by a Japan Society for the Promotion of Science(JSPS)Grant-in-Aid for Scientific Research(26310304)Yamagata University YU-COE(S)programby the Advanced Agri-food System Research Center of Yamagata University,Japan。
文摘To examine the impact of anthropogenic land reconstruction,particularly the consolidation of small terraces into larger fields,on soil organic carbon(SOC),total nitrogen(TN)dynamics,rice yield,and its components,soil and plant samples were collected from seven newly reconstructed fields in Japanese Andosols in Tochigi,Japan.Samples were obtained from both the former low-and high-elevation sides within each field plot.During harvest season,nine rice plants were randomly selected from each plot(0.675 m^(2),comprising 3 rows and 3 hills per row),collected from a 3-m stretch along both the east(former low side)and west(former high side)ridges.Soil cores were collected from identical plots at two depths(0–15 and 15–30 cm)and combined into one composite sample per layer.Rice plant samples were air-dried for two weeks until reaching constant moisture content,after which stems and ears were separated and weighed to determine biomass,yield,yield components,and nitrogen uptake.This indicated that land reconstruction significantly affected rice yield and its components between the two sides of all field plots.SOC,TN,and their decomposition following land reconstruction showed notable changes,especially in the 15–30 cm subsurface soil layer.Additionally,grain weight demonstrated significant correlation with SOC,TN,and carbon decomposition in both the 0–15 and 15–30 cm layers,indicating that soil fertility to a depth of 30 cm was crucial for rice productivity after land reconstruction.
文摘In our study,we tackle a linear advection-diffusion equation that varies with time and is constrained to one dimension,under the framework of homogeneous Dirichlet boundary conditions.We employ two distinct approaches for solving this equation:an analytical solution through the method of separation of variables,and a numerical solution utilizing the finite difference method.The computational output includes three dimensional(3D)plots for solutions,focusing on pollutants such as Ammonia,Carbon monoxide,Carbon dioxide,and Sulphur dioxide.Concentrations,along with their respective diffusivities,are analyzed through 3D plots and actual calculations.To comprehend the diffusivity-concentration relationship for predicting pollutant movement in the air,the domain is divided into two halves.The study explores the behavior of pollutants with higher diffusivity entering regions with lower diffusivity,and vice versa,using 2D and 3D plots.This task is crucial for effective pollution control strategies,and safeguarding the environment and public health.
基金National Natural Science Foundation of China(42575091)Marine Meteorological Science and Data Center Program (2024B1212070014)。
文摘In this study, the ground potential rise(GPR) phenomenon caused by a lightning current injected into a field-shaped artificial grounding grid, as well as the potential difference between two different nodes at the edge of the grounding grid, was observed and analyzed under artificially triggered lightning conditions. Based on circuit theory and measured current data, a π-equivalent circuit was established to simulate the transient response of the grounding grid.Nineteen return strokes from three artificially triggered lightning events were analyzed. The peak currents of the 19 return strokes range from -6.7 to -25.1 kA, and the mean value was -14.3 kA. The GPR decreased rapidly and formed a subpeak after reaching the initial peak, with the mean value of the initial peak being -148.65 kV and the mean value of the subpeak being -92.87 kV. The GPR induced by the triggered lightning currents exhibited a subpeak phenomenon. Simulation results indicate that the subpeak phenomenon is related to localized corrosion of the vertical grounding electrode. The potential difference at the grounding grid edge exhibited a multi-pulse waveform with alternating polarity, dominated by positive pulses. The peak values of both the positive and negative polarity pulses gradually decreased, with the first positive pulse displaying a significantly higher intensity than that of subsequent pulses.
基金supported by Sichuan Science and Technology Program(No.2024NSFSC0060)the National Natural Science Foundation of China(No.U23A2030)the Basic Research Cultivation Support Plan of Southwest Jiaotong University(No.2682023ZTPY016).
文摘Imidazole(IM)particles in the atmosphere affect climate,atmospheric chemical reactions,and human health.However,research on IM particles in the Sichuan Basin(SCB),one of the areas of China affected most heavily by haze,remains very scarce.This study used single-particle aerosol mass spectrometry to investigate IM-containing particles in Chengdu,one of the megacities in the SCB,during summer and winter before and after implemen-tation of the Three-year Action Plan to Win the Blue-Sky Defense War(BSDW).We found that IM-containing particles accounted for 1.2%–12.0%of all detected particles,and they highly mixed with carbonaceous com-ponents,secondary inorganic species,and organic nitrogen.From before to after the BSDW,the proportion of IM-containing particles decreased by 1.8%in summer,but increased by 9.6%in winter.Ammonium/amines and carbonyl compounds were closely related to IM-containing particles;the highest proportion of IM-containing particles occurred in particles mixed with amines and carbonyls.The number fraction of IM-containing particles in all seasons was higher at night than during daytime.The potential source areas of IM-containing particles showed notable narrowing after the BSDW,and the high-value areas were found distributed closer to Chengdu and its surrounding areas.In the winter before the BSDW,most IM-containing particles(>70%)were mixed with organic carbon(OC)particles,and the contributions of OC and mixed organic–elemental carbon(OC-EC)particles increased with aggravation of pollution,whereas OC-EC and Metal particles played a more crucial role in the winter after the BSDW.
基金supported by the National Natural Science Foundation of China(52371131)the 10th Youth Talent Lifting Project of the China Association for Science and Technology.
文摘Rechargeable alkali metal-sulfur(M-S)batteries,including Li/Na/K-S chemistries,have the potential to utilize abundant and low-cost sulfur cathodes yet offer high theoretical energy densities.However,their practical electrochemical performance is fundamentally limited by the polysulfide shuttle effect.This challenge is particularly exacerbated in Na-S and K-S systems owing to larger metal-ion radii,weaker solvation energies,slower redox kinetics,and greater electrolyte-electrode incompatibilities compared to Li-S batteries.This review presents a comparative analysis of interface engineering strategies designed to suppress the shuttle effect across these three systems.Following a summary of sulfur cathode properties and reaction mechanisms,we systematically examine the origins of polysulfide shuttling.Our analysis progresses from functional separator design and interlayer enhancements to the implementation of solid-state electrolytes for root-cause inhibition.By evaluating interface engineering research specific to Na-S and K-S batteries,we elucidate both shared principles and unique challenges inherent to alkali M-S systems.Finally,we propose multifaceted solutions to achieve shuttlefree operation and enhance overall battery performance,thereby establishing a foundation for future advancements.
基金supported by the National Natural Science Foundation of China(Grant Nos.12172267 and 12302014).
文摘Quasi-periodic solutions with multiple base frequencies exhibit the feature of 2π-periodicity with respect to each of the hyper-time variables.However,it remains a challenge work,due to the lack of effective solution methods,to solve and track the quasi-periodic solutions with multiple base frequencies until now.In this work,a multi-steps variable-coefficient formulation is proposed,which provides a unified framework to enable either harmonic balance method or collocation method or finite difference method to solve quasi-periodic solutions with multiple base frequencies.For this purpose,a method of alternating U and S domain is also developed to efficiently evaluate the nonlinear force terms.Furthermore,a new robust phase condition is presented for all of the three methods to make them track the quasi-periodic solutions with prior unknown multiple base frequencies,while the stability of the quasi-periodic solutions is assessed by mean of Lyapunov exponents.The feasibility of the constructed methods under the above framework is verified by application to three nonlinear systems.
基金funded by the National Natural Science Foundation of China(Grant Nos.52275302,52375301 and 52322508)the National Key Research and Development Program of China(Grant No.2023YFB3407701)+1 种基金the HaiYou Industrial Experts Programme(Grant No.CYLJ20241901412)the Open Project of the Key Laboratory of Multiscale Laser Manufacturing Technology,Ministry of Education.
文摘To improve the penetration of thick plates,a laser-enhanced plasma arc welding process was developed.However,the current understanding of laser absorption and energy transfer mechanisms is still unclear,limiting its optimization and application.This work establishes mathematical model of this novel heat source including electron density based on the gas state equation,Saha equation,and charge conservation equation.This model reveals the laser transmission characteristics in the plasma controlled by temperature and electron density,as well as the electrical and thermal transfer from the composite arc to the base material.The simulated temperature fields,arc pressure distributions,and arc voltages showed good agreement with experimental measurements,with peak pressure errors within 50 Pa and voltage differences within 0.3 V,validating the accuracy of the model.The results showed that the laser increased the arc temperature inside the keyhole,extending the high-temperature zone downwards.The laser has altered the current density distribution at the keyhole edge,decreasing the upper part but increasing the lower part.The trend of heat flux density change is consistent with the current density.There is a high laser absorption zone in the arc between the tungsten electrode and base metal,whose position changes with laser power,thereby improving the position and axial energy distribution of the plasma arc.
