The soil-bentonite(SB)cut-off wall has been widely considered a vertical barrier to effectively control the migration of pollutants in contaminated sites.Recently,active porous materials have been used as a promising ...The soil-bentonite(SB)cut-off wall has been widely considered a vertical barrier to effectively control the migration of pollutants in contaminated sites.Recently,active porous materials have been used as a promising candidate amendment for mitigating chemical degradation and improving the retardation capacity of the SB cut-off wall.In this study,the silty clay from a typical Cr(VI)contaminated site was selected as the body material of the SB cut-off wall,and zeolite and active carbon were used as the modifiers of the silty clay-bentonite backfills,respectively.The impact of the two modifiers on the engineering properties of the backfills was investigated through a series of slump tests,consolidation tests,hydraulic conductivity tests,and microstructure tests.The experimental results demonstrated that the slump curves closely exhibited a linear relationship between standard slump and moisture content.Meanwhile,bentonite could improve the optimum moisture content of the backfills,while the addition of the two modifiers yielded the opposite outcome.As the bentonite content increased,the compression index of the backfills significantly increased,while the hydraulic conductivity decreased.At a given bentonite content of 5%,the addition of zeolite or active carbon resulted in a reduction in the compression index and initial void ratio,while exhibiting minimal impact on the hydraulic conductivity.Scanning electron microscope(SEM)observations indicated that the silty clay-bentonite backfills became increasingly loose with increasing bentonite content,owing to the filling and expansion of dispersed bentonite layers.The amendment of zeolite or active carbon was able to decrease the backfill volume by promoting the agglomeration of layered bentonite.The findings of this study will be useful for the optimal selection of backfill materials and the performance evaluation of the cut-off wall.展开更多
Uneven lithium deposition leading to lithium dendrite growth severely hampers the application of lithium-metal batteries.Modifying the collector with lithiophilic materials helps improve lithium deposition.For lithoph...Uneven lithium deposition leading to lithium dendrite growth severely hampers the application of lithium-metal batteries.Modifying the collector with lithiophilic materials helps improve lithium deposition.For lithophilic materials to modify the collector,the choice of cut-off voltage is very important.While excessively high cut-off voltages may compromise the stability of the modified layer and consequently disrupt ordered lithium deposition,conventional approaches typically employ lower cut-off voltages(particularly 0.1 V)to maintain modification layer stability.However,the 0.1 V cut-off voltage results in incomplete lithium stripping from the lithiophilic material surface.This phenomenon significantly diminishes the lithiophilic properties of the modified layer and consequently leads to substantial nucleation overpotential.Here,we propose to use a moderate cut-voltage stimulation effect to slow down the interfacial shielding effect of residual lithium metal on lithiophilic materials.By optimizing the cut-off voltage for the Cu@Sb_(2)S_(3)collector,the stability of the modified layer can be preserved while enabling the complete stripping of lithium metal from the surface of the lithophilic material.The asymmetric cell received the highest Coulombic efficiency(CE)when the lithium stripping cut-off voltage was set at 0.5 V relative to 0.1 and 2.0 V.At a current density of 1 mA cm^(-2)and a deposition capacity of1 m A h cm^(-2),the CE remained 98.6% at a cut-off voltage of 0.5 V after 140 cycles in an ether electrolyte without lithium nitrate.展开更多
The variable salinity in stored reservoirs connected by a long channel attracts the attention of scientists worldwide,having applications in environmental and geophysical engineering.This study explores the impact of ...The variable salinity in stored reservoirs connected by a long channel attracts the attention of scientists worldwide,having applications in environmental and geophysical engineering.This study explores the impact of Navier slip conditions on exchange flows within a long channel connecting two large reservoirs of differing salinity.These horizontal density gradients drive the flow.We modify the recent one-dimensional theory,developed to avoid runaway stratification,to account for the presence of uniform slip walls.By adjusting the parameters of the horizontal density gradient based on the slip factor,we resolve analytically various flow regimes ranging from high diffusion to transitional high advection.These regimes are governed by physical parameters like channel aspect ratio,slip factor,Schmidt number,and gravitational Reynolds number.Our solutions align perfectly with ones in the no-slip limit.More importantly,under the conditions of no net flow across the channel and high Schmidt number(where stratification is concentrated near the channel’s mid-layer),we derive a closed-form solution for the slip parameter,aspect ratio,and gravitational Reynolds number that describes the interface’s behavior as a sharp interface separating two distinct zones.This interface,arising from hydrostatic wall gradients,ultimately detaches the low-and high-density regimes throughout the channel when the gravitational Reynolds number is inversely proportional to the aspect ratio for a fixed slip parameter.This phenomenon,observed previously in 2D numerical simulations with no-slip walls in the literature,is thus confirmed by our theoretical results.Our findings further demonstrate that wall slip leads to distinct and diverse flow regimes.展开更多
This study investigates the bifurcation dynamics underlying rhythmic transitions in a biophysical hippocampal–cortical neural network model.We specifically focus on the membrane potential dynamics of excitatory neuro...This study investigates the bifurcation dynamics underlying rhythmic transitions in a biophysical hippocampal–cortical neural network model.We specifically focus on the membrane potential dynamics of excitatory neurons in the hippocampal CA3 region and examine how strong coupling parameters modulate memory consolidation processes.Employing bifurcation analysis,we systematically characterize the model's complex dynamical behaviors.Subsequently,a characteristic waveform recognition algorithm enables precise feature extraction and automated detection of hippocampal sharp-wave ripples(SWRs).Our results demonstrate that neuronal rhythms exhibit a propensity for abrupt transitions near bifurcation points,facilitating the emergence of SWRs.Critically,temporal rhythmic analysis reveals that the occurrence of a bifurcation is not always sufficient for SWR formation.By integrating one-parameter bifurcation analysis with extremum analysis,we demonstrate that large-amplitude membrane potential oscillations near bifurcation points are highly conducive to SWR generation.This research elucidates the mechanistic link between changes in neuronal self-connection parameters and the evolution of rhythmic characteristics,providing deeper insights into the role of dynamical behavior in memory consolidation.展开更多
Sharp eyespot(Rhizoctonia cerealis)is a widespread soil-borne fungal disease that poses a severe threat to wheat health,and it is one of the main obstacles to achieving stable and high-quality wheat yields in China.Ou...Sharp eyespot(Rhizoctonia cerealis)is a widespread soil-borne fungal disease that poses a severe threat to wheat health,and it is one of the main obstacles to achieving stable and high-quality wheat yields in China.Our collaborative team has developed a novel,efficient,and low-toxicity fungicide named Y17991(N-(2-(2,4-bis-(trifluoromethyl)phenoxy)phenyl)-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxamide).Preliminary laboratory tests confirmed the significant inhibitory effect of this agent on R.cerealis.Large-area field trials also demonstrated its efficacy,with a disease prevention index of 83.52%,which is 1.97%greater than that of the widely used thifluzamide,and it significantly increased the wheat yield.Moreover,this study explored the impacts of Y17991 on the structure and function of the microbial community in wheat rhizosphere soil.Bacterial communities were more strongly affected than fungal communities.Y17991 significantly modulated key amino acid metabolic pathways and certain biosynthetic processes in diseased wheat rhizospheres,and it also enhanced certain biosynthetic pathways and metabolic activities in healthy wheat rhizospheres.Additionally,the application of Y17991 regulated rhizosphere metabolites,thus exerting significant control over the microbial community.We identified 15 microbial strains potentially involved in the prevention and treatment of R.cerealis,and Y17991 treatment promoted the growth of Pedobacter and Bacillus strains.These strains not only aid in plant growth but they also have the potential for disease prevention.In summary,Y17991 application at a reasonable dose does not cause significant disruption to nontarget rhizosphere microbial communities.In future studies,we will continue to investigate the impacts of Y17991 on nonmicrobial components in soil ecosystems,such as protozoa and nematodes.Our research provides a theoretical basis for the scientific application and promotion of new fungicides and offers a significant reference for establishing a comprehensive system for assessing the ecological impact of pesticides on the environment.展开更多
Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects...Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.展开更多
传统Sharpe比率将投资收益的标准差作为风险的度量,而实证研究中更关注基金的损失风险而非全部风险,这是收益标准差所无法准确刻画的。针对传统Sharpe比率的这一缺点,本文考虑了用于度量下方风险的指标风险价值VaR(Value at Risk)和预...传统Sharpe比率将投资收益的标准差作为风险的度量,而实证研究中更关注基金的损失风险而非全部风险,这是收益标准差所无法准确刻画的。针对传统Sharpe比率的这一缺点,本文考虑了用于度量下方风险的指标风险价值VaR(Value at Risk)和预期不足ES(Expected Shortfall)来替代投资收益的标准差,从而对传统Sharpe比率进行了调整。这里对VaR和ES进行计算时,运用了经验非参数估计和非参数平滑核估计两种方法。此外,本文还考虑了基金收益随时间波动的动态性,用广义自回归异方差GARCH模型对收益波动进行模拟,考察动态的VaR和ES,在实践中以动态的VaR和ES评价风险收益更加灵活。在实证研究中,本文用传统的Sharpe比率、基于VaR和ES的Sharpe比率以及基于条件VaR和条件ES的条件Sharpe比率对国内证券市场上所有26只封闭式基金在2005-2009年间的业绩进行了实证分析,分析了基金在不同指标下所体现的风险控制能力和收益水平的差别,并基于不同指标对所有基金进行了排名。此外,本文还运用协整检验考察基金收益率与市场基准指数是否存在联动关系,检验证明两者并不存在长期的均衡关系。展开更多
基金the National Natural Science Foundation of China (Grant Nos.42072318 and 42207227)Central South University Innovation-Driven Research Program (Grant No.2023CXQD044).
文摘The soil-bentonite(SB)cut-off wall has been widely considered a vertical barrier to effectively control the migration of pollutants in contaminated sites.Recently,active porous materials have been used as a promising candidate amendment for mitigating chemical degradation and improving the retardation capacity of the SB cut-off wall.In this study,the silty clay from a typical Cr(VI)contaminated site was selected as the body material of the SB cut-off wall,and zeolite and active carbon were used as the modifiers of the silty clay-bentonite backfills,respectively.The impact of the two modifiers on the engineering properties of the backfills was investigated through a series of slump tests,consolidation tests,hydraulic conductivity tests,and microstructure tests.The experimental results demonstrated that the slump curves closely exhibited a linear relationship between standard slump and moisture content.Meanwhile,bentonite could improve the optimum moisture content of the backfills,while the addition of the two modifiers yielded the opposite outcome.As the bentonite content increased,the compression index of the backfills significantly increased,while the hydraulic conductivity decreased.At a given bentonite content of 5%,the addition of zeolite or active carbon resulted in a reduction in the compression index and initial void ratio,while exhibiting minimal impact on the hydraulic conductivity.Scanning electron microscope(SEM)observations indicated that the silty clay-bentonite backfills became increasingly loose with increasing bentonite content,owing to the filling and expansion of dispersed bentonite layers.The amendment of zeolite or active carbon was able to decrease the backfill volume by promoting the agglomeration of layered bentonite.The findings of this study will be useful for the optimal selection of backfill materials and the performance evaluation of the cut-off wall.
基金support from the National Natural Science Foundation of China(22179006)the National Key Research and Development Program of China(2024YFF0505900)+1 种基金the Key Research and Development Program of Henan province,China(231111242500)the SINOPEC project(223128)。
文摘Uneven lithium deposition leading to lithium dendrite growth severely hampers the application of lithium-metal batteries.Modifying the collector with lithiophilic materials helps improve lithium deposition.For lithophilic materials to modify the collector,the choice of cut-off voltage is very important.While excessively high cut-off voltages may compromise the stability of the modified layer and consequently disrupt ordered lithium deposition,conventional approaches typically employ lower cut-off voltages(particularly 0.1 V)to maintain modification layer stability.However,the 0.1 V cut-off voltage results in incomplete lithium stripping from the lithiophilic material surface.This phenomenon significantly diminishes the lithiophilic properties of the modified layer and consequently leads to substantial nucleation overpotential.Here,we propose to use a moderate cut-voltage stimulation effect to slow down the interfacial shielding effect of residual lithium metal on lithiophilic materials.By optimizing the cut-off voltage for the Cu@Sb_(2)S_(3)collector,the stability of the modified layer can be preserved while enabling the complete stripping of lithium metal from the surface of the lithophilic material.The asymmetric cell received the highest Coulombic efficiency(CE)when the lithium stripping cut-off voltage was set at 0.5 V relative to 0.1 and 2.0 V.At a current density of 1 mA cm^(-2)and a deposition capacity of1 m A h cm^(-2),the CE remained 98.6% at a cut-off voltage of 0.5 V after 140 cycles in an ether electrolyte without lithium nitrate.
文摘The variable salinity in stored reservoirs connected by a long channel attracts the attention of scientists worldwide,having applications in environmental and geophysical engineering.This study explores the impact of Navier slip conditions on exchange flows within a long channel connecting two large reservoirs of differing salinity.These horizontal density gradients drive the flow.We modify the recent one-dimensional theory,developed to avoid runaway stratification,to account for the presence of uniform slip walls.By adjusting the parameters of the horizontal density gradient based on the slip factor,we resolve analytically various flow regimes ranging from high diffusion to transitional high advection.These regimes are governed by physical parameters like channel aspect ratio,slip factor,Schmidt number,and gravitational Reynolds number.Our solutions align perfectly with ones in the no-slip limit.More importantly,under the conditions of no net flow across the channel and high Schmidt number(where stratification is concentrated near the channel’s mid-layer),we derive a closed-form solution for the slip parameter,aspect ratio,and gravitational Reynolds number that describes the interface’s behavior as a sharp interface separating two distinct zones.This interface,arising from hydrostatic wall gradients,ultimately detaches the low-and high-density regimes throughout the channel when the gravitational Reynolds number is inversely proportional to the aspect ratio for a fixed slip parameter.This phenomenon,observed previously in 2D numerical simulations with no-slip walls in the literature,is thus confirmed by our theoretical results.Our findings further demonstrate that wall slip leads to distinct and diverse flow regimes.
基金supported by the National Natural Science Foundation of China(Grant Nos.12272002 and 12372061)the R&D Program of Beijing Municipal Education Commission(Grant No.KM202310009004)+1 种基金the North China University of Technology(Grant No.2023XN075-01)the Youth Research Special Project of the North China University of Technology(Grant No.2025NCUTYRSP051)。
文摘This study investigates the bifurcation dynamics underlying rhythmic transitions in a biophysical hippocampal–cortical neural network model.We specifically focus on the membrane potential dynamics of excitatory neurons in the hippocampal CA3 region and examine how strong coupling parameters modulate memory consolidation processes.Employing bifurcation analysis,we systematically characterize the model's complex dynamical behaviors.Subsequently,a characteristic waveform recognition algorithm enables precise feature extraction and automated detection of hippocampal sharp-wave ripples(SWRs).Our results demonstrate that neuronal rhythms exhibit a propensity for abrupt transitions near bifurcation points,facilitating the emergence of SWRs.Critically,temporal rhythmic analysis reveals that the occurrence of a bifurcation is not always sufficient for SWR formation.By integrating one-parameter bifurcation analysis with extremum analysis,we demonstrate that large-amplitude membrane potential oscillations near bifurcation points are highly conducive to SWR generation.This research elucidates the mechanistic link between changes in neuronal self-connection parameters and the evolution of rhythmic characteristics,providing deeper insights into the role of dynamical behavior in memory consolidation.
基金supported by the National Natural Science Foundation of China(32270296)the Shenzhen Postdoctoral Scientific Research,China(77000-42100004)+1 种基金the Key Basic Research and Development Program of Hubei Province,China(2020BBA052)the Natural Science Foundation of Guangdong Province,China(2024A1515010498)and the Fundamental Research Funds for the Central Universities,Sun Yat-sen University,China.
文摘Sharp eyespot(Rhizoctonia cerealis)is a widespread soil-borne fungal disease that poses a severe threat to wheat health,and it is one of the main obstacles to achieving stable and high-quality wheat yields in China.Our collaborative team has developed a novel,efficient,and low-toxicity fungicide named Y17991(N-(2-(2,4-bis-(trifluoromethyl)phenoxy)phenyl)-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxamide).Preliminary laboratory tests confirmed the significant inhibitory effect of this agent on R.cerealis.Large-area field trials also demonstrated its efficacy,with a disease prevention index of 83.52%,which is 1.97%greater than that of the widely used thifluzamide,and it significantly increased the wheat yield.Moreover,this study explored the impacts of Y17991 on the structure and function of the microbial community in wheat rhizosphere soil.Bacterial communities were more strongly affected than fungal communities.Y17991 significantly modulated key amino acid metabolic pathways and certain biosynthetic processes in diseased wheat rhizospheres,and it also enhanced certain biosynthetic pathways and metabolic activities in healthy wheat rhizospheres.Additionally,the application of Y17991 regulated rhizosphere metabolites,thus exerting significant control over the microbial community.We identified 15 microbial strains potentially involved in the prevention and treatment of R.cerealis,and Y17991 treatment promoted the growth of Pedobacter and Bacillus strains.These strains not only aid in plant growth but they also have the potential for disease prevention.In summary,Y17991 application at a reasonable dose does not cause significant disruption to nontarget rhizosphere microbial communities.In future studies,we will continue to investigate the impacts of Y17991 on nonmicrobial components in soil ecosystems,such as protozoa and nematodes.Our research provides a theoretical basis for the scientific application and promotion of new fungicides and offers a significant reference for establishing a comprehensive system for assessing the ecological impact of pesticides on the environment.
基金Projects(52278395,52208409) supported by the National Natural Science Foundation of ChinaProject(2022JJ40531) supported by the Natural Science Foundation of Hunan Province,China。
文摘Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.
文摘传统Sharpe比率将投资收益的标准差作为风险的度量,而实证研究中更关注基金的损失风险而非全部风险,这是收益标准差所无法准确刻画的。针对传统Sharpe比率的这一缺点,本文考虑了用于度量下方风险的指标风险价值VaR(Value at Risk)和预期不足ES(Expected Shortfall)来替代投资收益的标准差,从而对传统Sharpe比率进行了调整。这里对VaR和ES进行计算时,运用了经验非参数估计和非参数平滑核估计两种方法。此外,本文还考虑了基金收益随时间波动的动态性,用广义自回归异方差GARCH模型对收益波动进行模拟,考察动态的VaR和ES,在实践中以动态的VaR和ES评价风险收益更加灵活。在实证研究中,本文用传统的Sharpe比率、基于VaR和ES的Sharpe比率以及基于条件VaR和条件ES的条件Sharpe比率对国内证券市场上所有26只封闭式基金在2005-2009年间的业绩进行了实证分析,分析了基金在不同指标下所体现的风险控制能力和收益水平的差别,并基于不同指标对所有基金进行了排名。此外,本文还运用协整检验考察基金收益率与市场基准指数是否存在联动关系,检验证明两者并不存在长期的均衡关系。
