Herein,3‑aminopropyltriethoxysilane(APTES)was used to modify F‑containing silica slag(SS)by simple grafting and served as a multifunctional barrier layer.The amino group(—NH2)in the amino‑modified SS(NH2‑SS)forms lig...Herein,3‑aminopropyltriethoxysilane(APTES)was used to modify F‑containing silica slag(SS)by simple grafting and served as a multifunctional barrier layer.The amino group(—NH2)in the amino‑modified SS(NH2‑SS)forms ligand bonds or hydrogen bonds with sulfur ions in lithium polysulfides(LiPSs),thus inhibiting the shuttle effect.Electrochemical analyses demonstrated that lithium‑sulfur(Li‑S)batteries employing the NH2‑SS interlayer exhibited discharge specific capacities of 1048 and 789 mAh·g^(-1) at 0.2C and 2C,respectively,and even at 4C,the initial discharge specific capacity remained at 590 mAh·g^(-1),outperforming the Li‑S battery with unmodified SS as the interlayer.展开更多
Objective:Severe diastasis recti abdominis(DRA)in the postpartum period may lead to long‑term functional impairment in women.However,the independent effects and interactions of perinatal risk factors during the early ...Objective:Severe diastasis recti abdominis(DRA)in the postpartum period may lead to long‑term functional impairment in women.However,the independent effects and interactions of perinatal risk factors during the early postpartum recovery window have not been fully elucidated.This study aims to analyze the risk factors and interaction effects associated with severe postpartum DRA and to identify characteristics of high‑risk populations.Methods:This retrospective cohort study included postpartum women who underwent postpartum rehabilitation treatment at Hengyang Maternal and Child Health Hospital between January 2019 and August 2022,with a postpartum interval of 42 to 180 d.The inter-rectus distance was measured using palpation combined with caliper assessment.According to the inter-rectus distance,participants were divided into 4 groups:A severe DRA group(separation distance≥4 cm),a moderate DRA group(3.0 to 3.9 cm),a mild DRA group(2.0 to 2.9 cm),and a normal group(<2 cm).The moderate DRA,mild DRA,and normal groups were combined as the control group.Receiver operating characteristic(ROC)curve analysis was used to evaluate continuous variables and determine optimal cutoff values for stratification.The chi-square test was used to compare differences in influencing factors between the severe DRA group and the control group.Binary Logistic regression analysis was further performed to investigate the effects of various factors on severe DRA,and interaction analysis within the binary Logistic regression model was used to identify high-risk populations.Results:A total of 525 postpartum women were ultimately included,including 112 in the severe DRA group,257 in the moderate DRA group,98 in the mild DRA group,and 58 in the normal group.The overall incidence of DRA was 89.0%,while the incidence of severe DRA was 21.3%.The diagnostic cutoff values for body mass index(BMI),neonatal birth weight,and gestational weight gain were 22.55 kg/m^(2),3350 g,and 12.25 kg,respectively.Participants with BMI≥22.55 kg/m^(2),neonatal birth weight≥3350 g,gestational weight gain≥12.25 kg,multiparity,cesarean delivery,or number of fetuses≥2 had significantly higher incidences of severe DRA(all P<0.05).Binary Logistic regression analysis showed that neonatal birth weight≥3350 g,gestational weight gain≥12.25 kg,cesarean delivery,and multiparity were independent risk factors for severe DRA(all P<0.05).The interaction among neonatal birth weight≥3350 g,multiparity,and cesarean delivery showed the strongest association with severe DRA(OR=7.10,95%CI 3.43 to 14.71).When all 3 risk factors were present simultaneously,the incidence of severe DRA reached 61.76%.Conclusion:Neonatal birth weight≥3350 g,gestational weight gain≥12.25 kg,cesarean delivery,and multiparity are important independent risk factors for severe postpartum DRA,and significant synergistic amplification effects exist among these factors.This study clarified the characteristics of high-risk populations and may provide a basis for targeted early screening and intervention.展开更多
Nonlinear Rossby waves are used to describe typical wave phenomena in large-scale atmosphere andocean.Owing to the nonlinearity of the involved problems,the weakly nonlinear method,ie the derivative ex-pansion method,...Nonlinear Rossby waves are used to describe typical wave phenomena in large-scale atmosphere andocean.Owing to the nonlinearity of the involved problems,the weakly nonlinear method,ie the derivative ex-pansion method,was mainly used to investigate Rossby waves under the combined effects of the generalizedβ-effect and the basic flow effect.The derivative expansion method has the advantage of capturing the multi-scalecharacteristics of wave processes simultaneously.In the case where the perturbation expansion is independentof secular terms,the nonlinear equations describing the amplitude evolution of nonlinear waves were derived,such as the Korteweg-de Vries equation,the Boussinesq equation and Zakharov-Kuznetsov equation.Both quali-tative and quantitative analyses indicate that the generalizedβ-effect is the key factor inducing the evolution ofRossby solitary waves.展开更多
Electrochemiluminescence(ECL)of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions(As(III)).Cyclic voltammetry(CV)was applied as the proposed technique to ...Electrochemiluminescence(ECL)of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions(As(III)).Cyclic voltammetry(CV)was applied as the proposed technique to study luminol's electrochemical behavior and to evaluate the arsenic's effect in the ECL system,while hydrogen peroxide(H_(2)O_(2))served as a co-reactant to enhance luminol's light emission under alkaline conditions.To achieve optimal electrode performance,key parameters including pH,scan rate,and the concentrations of H_(2)O_(2)and luminol were carefully optimized.The presence of As(III)induced a quenching effect on the luminol/H_(2)O_(2)ECL system,leading to a linear decrease in ECL signal across the wide concentration range of 1 nmol·L^(-1)to 150μmol·L^(-1).The system demonstrated a low detection limit of 1.21 nmol·L^(-1)and exhibited excellent repeatability with a relative standard deviation of 2.27%,highlighting its sensitivity and reliability for As(III)detection.A key advantage of this study was the successful use of commercial bare electrodes,which were readily available and required no modifications,proving their effectiveness for ECL-based arsenic sensing.The optimized buffer solution pH of 10 played a critical role in enhancing arsenic detection selectivity,as it facilitated the optimal deprotonation of luminol and ensured arsenic remained in its dissolved state,whereas other potential metal ion interferences were more likely to form solid metal(hydro)oxides.Furthermore,the developed sensor was successfully applied for As(III)detection in a seawater matrix,demonstrating its potential as a robust and effective ECL-based arsenic sensor for environmental applications.展开更多
Despite their high theoretical capacity and energy density,lithiumsulfur(Li–S)batteries still face challenges such as soluble lithium polysulfides(LiPSs)shuttling and sluggish redox kinetics.In this work,we used a no...Despite their high theoretical capacity and energy density,lithiumsulfur(Li–S)batteries still face challenges such as soluble lithium polysulfides(LiPSs)shuttling and sluggish redox kinetics.In this work,we used a novel MoS_(2)-Mo_(2)C heterostructure anchored on a carbon sponge(CS)as a Li_(2)S host to solve these problems.A simple hydrothermal process following carbothermal reduction was used to construct the MoS_(2)-Mo_(2)C heterostructure,enabling control of the phases and integration of MoS_(2) and Mo_(2)C.Structural characterization confirmed the coherent interface of the heterostructure with a precise orientation relationship between the two phases and their uniform distribution.An evaluation of the adsorption and catalytic performance of the material showed that it has an exceptional LiPSs adsorption capacity with faster conversion from Li_(2)S_(4) to Li_(2)S_(2).Density functional theory calculations further confirmed these results.As a result,the cathode had a high initial discharge capacity of 693 mAh g^(−1) at 0.2 C and achieved stable cycling at 2 C for 500 cycles with a low decay rate of 0.107%per cycle.The heterostructure design,coupled with the macroporous CS framework,effectively prevented the shuttling and increased sulfur utilization,offering a promising way to produce practical high-energydensity Li–S batteries.展开更多
Layered transition-metal compounds(LTMCs)feature stacked architectures,strong magnetic anisotropy,and tunable magnetic order,making them promising material platforms for low-power spintronic technologies and for enabl...Layered transition-metal compounds(LTMCs)feature stacked architectures,strong magnetic anisotropy,and tunable magnetic order,making them promising material platforms for low-power spintronic technologies and for enabling topological functionalities in the post-Moore era.Here we review recent progress on two-dimensional(2D)magnetism in LTMCs,emphasizing material taxonomy,intrinsic magnetic properties,and external-field controls.This review first presents a classification of LTMCs by crystal structure and chemistry—binary halides,chalcogenides,and ternary families(e.g.,MPX_(3),M_(m)X_(n)Te_(k),MnBi_(2)Te_(4))—followed by a summary of their coupling mechanisms,ordering temperatures,and dimensional effects.It then analyzes the modulation of exchange interactions,magnetic anisotropy,and topological states by electric-field gating,strain engineering,and ion intercalation,with representative experimental demonstrations.Notable advances include room-temperature ferromagnetic metals and semiconductors,observation of the quantum anomalous Hall effect(QAHE)in MnBi2Te4,and synergistic control of magnetic-topological states under multiple external stimuli.Persistent challenges involve the limited availability of intrinsic 2D magnetic semiconductors with high Curie temperatures(Tc),incomplete understanding of the microscopic couplings at interfaces and under quantum confinement,and device-level stability.We conclude by outlining opportunities that lie in the integration of multiscale characterization,first-principles theory,and cross-scale fabrication to precisely co-engineer magnetism,topology,and electronic structure,thereby advancing LTMCs toward spintronic and topological-quantum applications.展开更多
Chitosan(CTS)was grafted onto the surface of amino‑functionalized silver chloride silicon dioxide(AgCl@SiO_(2)‑NH_(2))cores to obtain AgCl@SiO_(2)/CTS hybrid nanoparticles.The as‑obtained AgCl@SiO_(2)/CTS nanoparticle...Chitosan(CTS)was grafted onto the surface of amino‑functionalized silver chloride silicon dioxide(AgCl@SiO_(2)‑NH_(2))cores to obtain AgCl@SiO_(2)/CTS hybrid nanoparticles.The as‑obtained AgCl@SiO_(2)/CTS nanoparticles were chlorinated by NaClO solution to get AgCl@SiO_(2)/CTS‑based chloramine nano‑hybrid materials,denoted as AgCl@SiO_(2)/CTS‑Cl.A transmission electron microscope was used to observe the morphology of the as‑prepared samples AgCl@SiO_(2)/CTS and AgCl@SiO_(2)/CTS‑Cl.At the same time,an X‑ray diffractometer and an infrared spectroscope were utilized to characterize their crystal and chemical structures.Besides,ζpotentials were measured to elucidate the surface modification of AgCl nanoparticles by—NH_(2),the antibacterial mechanism of AgCl@SiO_(2)/CTS‑Cl was investigated by scanning electron microscopy,and Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)were used as the to‑be‑tested strains to evaluate the antimicrobial activity of samples AgCl@SiO_(2)/CTS and AgCl@SiO_(2)/CTS‑Cl.Findings demonstrate that sample AgCl@SiO_(2)/CTS exhibits a chain‑like structure ascribed to the interaction between—NH_(2),and each AgCl@SiO_(2)/CTS hybrid nanoparticle contains several AgCl cores.In the meantime,sample AgCl@SiO_(2)/CTS‑Cl exhibits excellent antibacterial activity against E.coli and S.aureus,which is attributed to the synergistic antibacterial effect of Ag^(+)and Cl^(-).Sample AgCl@SiO_(2)/CTS‑Cl with a dosage of 640.00μg·mL^(-1) could completely kill the two kinds of tested bacteria in 12 h of incubation;it retains a high antibacterial efficiency even after 10 cycles of antibacterial tests.展开更多
A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescenc...A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescence(TADF)properties.All calculations were performed using density functional theory(DFT)and time‑dependent density functional theory(TDDFT).Calculations for electronic structures,frontier molecular orbital characteristics(which determine the efficiency roll‑off effect of the complexes),and photophysical properties were conducted using the Gaussian 09 software package.The calculation of spin‑orbit coupling matrix elements<T|HSOC|S>,which determine the TADF properties of the complexes,was performed using the ORCA software package.The calculation results show that the auxiliary ligand tetraphenylimidodiphosphinate(tpip),a strong electron‑withdrawing group,can mitigate the efficiency roll‑off effect of the complex.Furthermore,TADF is observed in one of the designed complexes,(F_(3)Phppy)_(2)Ir(tpip),where F_(3)Phppy=2‑[4‑(2,4,6‑trifluorophenyl)phenyl]pyridine.展开更多
To study the influence of support timing and support strength on the mechanical properties and deformation damage characteristics of a single-sided unloaded rock mass,a true triaxial perturbation unloaded rock testing...To study the influence of support timing and support strength on the mechanical properties and deformation damage characteristics of a single-sided unloaded rock mass,a true triaxial perturbation unloaded rock testing system was used to conduct rock damage tests on sandstone with different support timing and strength paths.Based on the acoustic emission monitoring system,the spatial and temporal evolution characteristics of the whole process of rock body loaded instability under two stress paths were studied,and the mechanism of the reinforcing effect of stress support on the unloaded rock mass was analyzed.The results show that,within the scope of this study,both earlier applications of shoring and an increase in shoring strength can effectively improve the ultimate bearing capacity of the unloaded rock,which increases the ultimate bearing capacity of the unloaded rock mass by 60.31% and 54.96%,respectively;There is a phenomenon of rebound deformation of the rock mass during sudden changes in stress(single-sided unloading,stress support),which shows opposite expansion and compression platforms on the stress−strain curve;The crack evolution of unloaded rock under different stress support conditions shows the state law of"initial crack activation→middle steady state expansion→late main crack penetration",and the lagging support significantly accelerates the crack evolution from local activation to main penetration;The single-sided unloading and stress-supporting stages have less influence on the unloading deformationsσ_(1u),σ_(2u) and support deformationsσ_(1) t,σ_(2t) in theσ_(1) andσ_(2)directions,while they show significant response characteristics toσ_(3u),σ_(vu) and σ_(3) t,σ_(vt),and with the increase of the support strength,the stress-supporting stagesσ_(3) t,σ_(vt) gradually increase and exceed the deformations generated by the unloading stagesσ_(3u),σ_(vu);The increase of support strength can effectively compensate for the rock stress loss caused by unloading,which makes the maximum,minimum,and volumetric strain support coefficients during the loading and unloading of the rock body increase gradually while the effect on the intermediate principal strain support coefficient is small;During loading,the support strength of rock masses seeks a new bearing area by regulating stress equilibrium states.This process primarily manifests as a shift in the locations of the crushing zone and the main bearing area,accompanied by a corresponding transformation in failure patterns.Consequently,the rock mass transitions from asymmetric three-zone damage under no or weak support to approximate symmetric three-zone damage under strong support.Simultaneously,the main load-bearing area of the rock mass shifts from deep bearing in the unsupported to middle bearing under strong support as the support strength increases.展开更多
This study investigates the thermoviscoelastic behavior of Kirchhoff circular microplates by integrating the nonlocal Moore-Gibson-Thompson(MGT)thermoelastic model with the modified couple stress theory(MCST)and a non...This study investigates the thermoviscoelastic behavior of Kirchhoff circular microplates by integrating the nonlocal Moore-Gibson-Thompson(MGT)thermoelastic model with the modified couple stress theory(MCST)and a nonlocal thermal length-scale parameter.It emphasizes the significance of size-dependent effects in microscale structures,which are often overlooked in classical continuum me-chanics.To enhance the model's accuracy in capturing mechanical and thermal responses,a Kelvin-Voigt viscoelastic framework is employed,addressing the interplay between elastic and viscous ef-fects.Using Hamilton's principle,the governing equations incorporate thermal relaxation time and temperature-dependent thermal conductivity.The study focuses on a clamped circular microplate subjected to thermal shock heating at its outer boundary.Numerical simulations explore the influence of key factors,such as viscosity,thermal length-scale parameters,and scale-dependent effects,on displacement,temperature fields,and thermal stresses.The results reveal that nonlocal elasticity significantly modifies deformation and stress distributions,enhancing stiffness and reducing energy dissipation.Viscosity effectively dampens vibrations and influences thermal diffusion,while size-dependent effects become increasingly pronounced as the microplate size decreases.These findings offer valuable insights for the design of advanced micro-electromechanical systems(MEMS),nano-resonators,and thermal devices,highlighting the necessity of incorporating nonlocality and viscoelastic properties to improve performance and reliability.展开更多
This paper prepared a novel as-cast W-Zr-Ti metallic ESM using high-frequency vacuum induction melting technique.The above ESM performs a typical elastic-brittle material feature and strain rate strengthening behavior...This paper prepared a novel as-cast W-Zr-Ti metallic ESM using high-frequency vacuum induction melting technique.The above ESM performs a typical elastic-brittle material feature and strain rate strengthening behavior.The specimens exhibit violent chemical reaction during the fracture process under the impact loading,and the size distribution of their residual debris follows Rosin-Rammler model.The dynamic fracture toughness is obtained by the fitting of debris length scale,approximately 1.87 MPa·m~(1/2).Microstructure observation on residual debris indicates that the failure process is determined by primary crack propagation under quasi-static compression,while it is affected by multiple cracks propagation in both particle and matrix in the case of dynamic impact.Impact test demonstrates that the novel energetic fragment performs brilliant penetration and combustion effect behind the front target,leading to the effective ignition of fuel tank.For the brittleness of as-cast W-ZrTi ESM,further study conducted bond-based peridynamic(BB-PD)C++computational code to simulate its fracture behavior during penetration.The BB-PD method successfully captured the fracture process and debris cloud formation of the energetic fragment.This paper explores a novel as-cast metallic ESM,and provides an available numerical avenue to the simulation of brittle energetic fragment.展开更多
The evaluation of air combat decision-making has garnered significant attention due to its potential to effectively mitigate losses resulting from erroneous decisions.However,existing research primarily focuses on sta...The evaluation of air combat decision-making has garnered significant attention due to its potential to effectively mitigate losses resulting from erroneous decisions.However,existing research primarily focuses on static evaluation methods.Therefore,this paper proposes a dynamic multi-round decision evaluation method based on the characteristics of multi-round unmanned aerial vehicle air combat under opponent’s optimal strategy.In order to determine objective weights,an improved multi-attribute decision making method is proposed,which incorporates the proximity as a correction coefficient for evaluation indicators,utilizing the cosine similarity instead of Euclidean distance,and incorporating both actual and theoretical objective weights to prevent data mutations.Subsequently,the game theory is employed to reasonably adjust subjective and objective weights to obtain comprehensive weights.To address the issues related to the ambiguity and randomness during the evaluation process,a reverse cloud generator is utilized to determine the center of gravity of the cloud model using comprehensive weights while employing the weighted deviation degree for evaluating air combat decision-making effectiveness.By activating the cloud generator through the cloud model,the optimal strategies for each round of air combat are determined,thereby completing the dynamic evaluations for multi-round sequential decision-making processes.Finally,the feasibility and effectiveness of the proposed method are verified through simulations.展开更多
Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these defo...Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these deformation patterns.This study utilized geophysical surveys and the continuum-based discrete element method(CDEM)to investigate how fault activity influences rock deformation and failure.The results demonstrate that:1)Acting in mechanically weak zones,faults exerted a pronounced barrier effect on deformation propagation and stress redistribution within the surrounding rock,leading to markedly divergent displacement patterns on either side of the fault plane.Comparative analyses between single-fault and double-fault models revealed an 18%−22%expansion of the damage zone under the latter,together with significantly intensified deformation and failure;2)The double-fault model exhibited a larger maximum cumulative vertical displacement and a spatial shift in the location of peak deformation,thereby posing a heightened threat to mine safety;3)Acting in an orebody substitute,backfill effectively constrained surrounding rock deformation,enhanced its load-bearing capacity,and delayed the overburden subsidence.Nevertheless,backfill only reduced the amplitude of deformation;it could not entirely prevent settlement.These findings provide essential theoretical insights and foundational knowledge for safer submarine mining practices.展开更多
Bay-site carboxyl functionalized perylene diimide derivative 1,7-COOH-PDI-C_(12)(PDI-COOH)was synthesized and distinct enhanced fluorescence was observed through combining with calcium ion(Ca^(2+))in THF/H_(2)O soluti...Bay-site carboxyl functionalized perylene diimide derivative 1,7-COOH-PDI-C_(12)(PDI-COOH)was synthesized and distinct enhanced fluorescence was observed through combining with calcium ion(Ca^(2+))in THF/H_(2)O solution.The assembly and fluorescence behavior of PDI-COOH/Ca^(2+)were studied in detail by changing hydration state with different concentrations.Based on the differences in assembly morphology and stoichiometric ratios of PDICOOH/Ca^(2+),we proposed the fluorescence emission mechanism of PDI-COOH/Ca^(2+)in THF/H_(2)O and THF,respectively.This work reveals a novel strategy of aggregated state fluorescence enhancement and reminds us of the important role of water in molecular fluorescence emission and assembly.展开更多
A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface...A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface area of 427 m^(2)·g^(-1)and rich surface active sites,which help restrain polysulfides(LiPSs)through good physi-cal and chemical adsorption,while simultaneously accelerating the nucleation and dissolution kinetics of Li_(2)S,effec-tively suppressing the shuttle effect.The assembled lithium-sulfur batteries(LSBs)employing the PVS-based inter-layer delivered a high initial discharge capacity of 1386 mAh·g^(-1)at 0.1C(167.5 mAh·g^(-1)),long-term cycling stabil-ity,and good rate property.展开更多
The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alka...The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alkaline water.Precise control of the electronic structure by heteroatom doping has proven to be efficient for increasing catalytic activity.Nevertheless,both the structural characteristics and the underlying mechanism are not well understood,especially for doping with two different atoms,thus limiting the use of these catalysts.We report the production of phosphorus and nitrogen co-doped hollow carbon nanospheres(HCNs)by the copolymerization of pyrrole and aniline at a Triton X-100 micelle-interface,followed by doping with phytic acid and carbonization.The unique pore structure and defect-rich framework of the HCNs expose numerous active sites.Crucially,the combined effect of graphitic nitrogen and phosphorus-carbon bonds modulate the local electronic structure of adjacent C atoms and facilitates electron transfer.As a res-ult,the HCN carbonized at 1100°C exhibited superior HER activity and an outstanding stability(70 h at a current density of 10 mA cm^(−2))in alkaline water,because of the large number of graphitic nitrogen and phosphorus-carbon bonds.展开更多
Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads ...Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.展开更多
In existing studies, most slope stability analyses concentrate on conditions with constant temperature, assuming the slope is intact, and employ the Mohr-Coulomb (M-C) failure criterion for saturated soil to character...In existing studies, most slope stability analyses concentrate on conditions with constant temperature, assuming the slope is intact, and employ the Mohr-Coulomb (M-C) failure criterion for saturated soil to characterize the strength of the backfill. However, the actual working temperature of slopes varies, and natural phenomena such as rainfall and groundwater infiltration commonly result in unsaturated soil conditions, with cracks typically present in cohesive slopes. This study introduces a novel approach for assessing the stability of unsaturated soil stepped slopes under varying temperatures, incorporating the effects of open and vertical cracks. Utilizing the kinematic approach and gravity increase method, we developed a three-dimensional (3D) rotational wedge failure mechanism to simulate slope collapse, enhancing the traditional two-dimensional analyses. We integrated temperature-dependent functions and nonlinear shear strength equations to evaluate the impact of temperature on four typical unsaturated soil types. A particle swarm optimization algorithm was employed to calculate the safety factor, ensuring our method’s accuracy by comparing it with existing studies. The results indicate that considering 3D effects yields a higher safety factor, while cracks reduce slope stability. Each unsaturated soil exhibits a distinctive temperature response curve, highlighting the importance of understanding soil types in the design phase.展开更多
The penetration-deflagration coupling damage performance of rod-like reactive shaped charge pene-trator(RRSCP)impacting thick steel plates is investigated by theoretical analysis and experiments.A penetration-deflagra...The penetration-deflagration coupling damage performance of rod-like reactive shaped charge pene-trator(RRSCP)impacting thick steel plates is investigated by theoretical analysis and experiments.A penetration-deflagration coupling damage model is developed to predict the penetration depth and cratering diameter.Four type of aluminum-polytetrafluoroethylene-copper(Al-PTFE-Cu)reactive liners with densities of 2.3,2.7,3.5,and 4.5 g·cm^(-3) are selected to conduct the penetration experiments.The comparison results show that model predictions are in good agreement with the experimental data.By comparing the penetration depth and cratering diameter in the inert penetration mode and the penetration-deflagration coupling mode,the influence mechanism that the penetration-induced chemical response is unfavorable to penetration but has an enhanced cratering effect is revealed.From the formation characteristics,penetration effect and penetration-induced chemical reaction be-haviors,the influence of reactive liner density on the penetration-deflagration performance is further analyzed.The results show that increasing the density of reactive liner significantly increases both the kinetic energy and length of the reactive penetrator,meanwhile effectively reduces the weakened effect of penetration-induced chemical response,resulting in an enhanced penetration capability.However,due to the decreased diameter and potential energy content of reactive penetrator,the cratering capa-bility is weakened significantly.展开更多
Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsatur...Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsaturated seepage multi-field coupling,resulting in inaccurate estimates.To address these deficiencies,this paper proposed a calculation method for seismic passive earth pressure in unsaturated narrow backfill,based on inclined thin-layer units.It considers the interlayer shear stress,arching effect,and the multi-field coupling of seismic-unsaturated seepage.Additionally,this paper includes a parametric sensitivity analysis.The outcomes indicate that the earthquake passive ground pressure of unsaturated narrow backfill can be reduced by increasing the aspect ratio,seismic acceleration coefficient,and unsaturation parameterα.It can also be reduced by decreasing the effective interior friction angle,soil cohesion,wallearth friction angle,and vertical discharge.Furthermore,for any width soil,lowering the elevation of the action point of passive thrust can be attained by raising the effective interior friction angle,wall-earth friction angle,and unsaturation parameterα.Reducing soil cohesion,seismic acceleration coefficient,and vertical discharge can also lower the height of the application point of passive thrust.展开更多
文摘Herein,3‑aminopropyltriethoxysilane(APTES)was used to modify F‑containing silica slag(SS)by simple grafting and served as a multifunctional barrier layer.The amino group(—NH2)in the amino‑modified SS(NH2‑SS)forms ligand bonds or hydrogen bonds with sulfur ions in lithium polysulfides(LiPSs),thus inhibiting the shuttle effect.Electrochemical analyses demonstrated that lithium‑sulfur(Li‑S)batteries employing the NH2‑SS interlayer exhibited discharge specific capacities of 1048 and 789 mAh·g^(-1) at 0.2C and 2C,respectively,and even at 4C,the initial discharge specific capacity remained at 590 mAh·g^(-1),outperforming the Li‑S battery with unmodified SS as the interlayer.
基金supported by the Natural Science Foundation of Hunan Province,China(2024JJ7069)。
文摘Objective:Severe diastasis recti abdominis(DRA)in the postpartum period may lead to long‑term functional impairment in women.However,the independent effects and interactions of perinatal risk factors during the early postpartum recovery window have not been fully elucidated.This study aims to analyze the risk factors and interaction effects associated with severe postpartum DRA and to identify characteristics of high‑risk populations.Methods:This retrospective cohort study included postpartum women who underwent postpartum rehabilitation treatment at Hengyang Maternal and Child Health Hospital between January 2019 and August 2022,with a postpartum interval of 42 to 180 d.The inter-rectus distance was measured using palpation combined with caliper assessment.According to the inter-rectus distance,participants were divided into 4 groups:A severe DRA group(separation distance≥4 cm),a moderate DRA group(3.0 to 3.9 cm),a mild DRA group(2.0 to 2.9 cm),and a normal group(<2 cm).The moderate DRA,mild DRA,and normal groups were combined as the control group.Receiver operating characteristic(ROC)curve analysis was used to evaluate continuous variables and determine optimal cutoff values for stratification.The chi-square test was used to compare differences in influencing factors between the severe DRA group and the control group.Binary Logistic regression analysis was further performed to investigate the effects of various factors on severe DRA,and interaction analysis within the binary Logistic regression model was used to identify high-risk populations.Results:A total of 525 postpartum women were ultimately included,including 112 in the severe DRA group,257 in the moderate DRA group,98 in the mild DRA group,and 58 in the normal group.The overall incidence of DRA was 89.0%,while the incidence of severe DRA was 21.3%.The diagnostic cutoff values for body mass index(BMI),neonatal birth weight,and gestational weight gain were 22.55 kg/m^(2),3350 g,and 12.25 kg,respectively.Participants with BMI≥22.55 kg/m^(2),neonatal birth weight≥3350 g,gestational weight gain≥12.25 kg,multiparity,cesarean delivery,or number of fetuses≥2 had significantly higher incidences of severe DRA(all P<0.05).Binary Logistic regression analysis showed that neonatal birth weight≥3350 g,gestational weight gain≥12.25 kg,cesarean delivery,and multiparity were independent risk factors for severe DRA(all P<0.05).The interaction among neonatal birth weight≥3350 g,multiparity,and cesarean delivery showed the strongest association with severe DRA(OR=7.10,95%CI 3.43 to 14.71).When all 3 risk factors were present simultaneously,the incidence of severe DRA reached 61.76%.Conclusion:Neonatal birth weight≥3350 g,gestational weight gain≥12.25 kg,cesarean delivery,and multiparity are important independent risk factors for severe postpartum DRA,and significant synergistic amplification effects exist among these factors.This study clarified the characteristics of high-risk populations and may provide a basis for targeted early screening and intervention.
文摘Nonlinear Rossby waves are used to describe typical wave phenomena in large-scale atmosphere andocean.Owing to the nonlinearity of the involved problems,the weakly nonlinear method,ie the derivative ex-pansion method,was mainly used to investigate Rossby waves under the combined effects of the generalizedβ-effect and the basic flow effect.The derivative expansion method has the advantage of capturing the multi-scalecharacteristics of wave processes simultaneously.In the case where the perturbation expansion is independentof secular terms,the nonlinear equations describing the amplitude evolution of nonlinear waves were derived,such as the Korteweg-de Vries equation,the Boussinesq equation and Zakharov-Kuznetsov equation.Both quali-tative and quantitative analyses indicate that the generalizedβ-effect is the key factor inducing the evolution ofRossby solitary waves.
基金Directorate of Research and Development,Universitas Indonesia under Bilateral Strategic Alliance(UI-UTM BISA)Research Collaboration Agreement(Matching Fund)2023(Grant No.NKB-1181/UN2.RST/HKP.05.00/2023)。
文摘Electrochemiluminescence(ECL)of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions(As(III)).Cyclic voltammetry(CV)was applied as the proposed technique to study luminol's electrochemical behavior and to evaluate the arsenic's effect in the ECL system,while hydrogen peroxide(H_(2)O_(2))served as a co-reactant to enhance luminol's light emission under alkaline conditions.To achieve optimal electrode performance,key parameters including pH,scan rate,and the concentrations of H_(2)O_(2)and luminol were carefully optimized.The presence of As(III)induced a quenching effect on the luminol/H_(2)O_(2)ECL system,leading to a linear decrease in ECL signal across the wide concentration range of 1 nmol·L^(-1)to 150μmol·L^(-1).The system demonstrated a low detection limit of 1.21 nmol·L^(-1)and exhibited excellent repeatability with a relative standard deviation of 2.27%,highlighting its sensitivity and reliability for As(III)detection.A key advantage of this study was the successful use of commercial bare electrodes,which were readily available and required no modifications,proving their effectiveness for ECL-based arsenic sensing.The optimized buffer solution pH of 10 played a critical role in enhancing arsenic detection selectivity,as it facilitated the optimal deprotonation of luminol and ensured arsenic remained in its dissolved state,whereas other potential metal ion interferences were more likely to form solid metal(hydro)oxides.Furthermore,the developed sensor was successfully applied for As(III)detection in a seawater matrix,demonstrating its potential as a robust and effective ECL-based arsenic sensor for environmental applications.
文摘Despite their high theoretical capacity and energy density,lithiumsulfur(Li–S)batteries still face challenges such as soluble lithium polysulfides(LiPSs)shuttling and sluggish redox kinetics.In this work,we used a novel MoS_(2)-Mo_(2)C heterostructure anchored on a carbon sponge(CS)as a Li_(2)S host to solve these problems.A simple hydrothermal process following carbothermal reduction was used to construct the MoS_(2)-Mo_(2)C heterostructure,enabling control of the phases and integration of MoS_(2) and Mo_(2)C.Structural characterization confirmed the coherent interface of the heterostructure with a precise orientation relationship between the two phases and their uniform distribution.An evaluation of the adsorption and catalytic performance of the material showed that it has an exceptional LiPSs adsorption capacity with faster conversion from Li_(2)S_(4) to Li_(2)S_(2).Density functional theory calculations further confirmed these results.As a result,the cathode had a high initial discharge capacity of 693 mAh g^(−1) at 0.2 C and achieved stable cycling at 2 C for 500 cycles with a low decay rate of 0.107%per cycle.The heterostructure design,coupled with the macroporous CS framework,effectively prevented the shuttling and increased sulfur utilization,offering a promising way to produce practical high-energydensity Li–S batteries.
基金supported by the National KeyR&D Program of China(Grant No.2024YFB3817400)the National Natural Science Foundation of China(Grants No.12274276 and No.U24A6002)+1 种基金the Natural Science Foundation of Shanxi Province(China)(Grant No.202403021223008)Supported by Scientific and Technology Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2024Q017 and No.2025L043).
文摘Layered transition-metal compounds(LTMCs)feature stacked architectures,strong magnetic anisotropy,and tunable magnetic order,making them promising material platforms for low-power spintronic technologies and for enabling topological functionalities in the post-Moore era.Here we review recent progress on two-dimensional(2D)magnetism in LTMCs,emphasizing material taxonomy,intrinsic magnetic properties,and external-field controls.This review first presents a classification of LTMCs by crystal structure and chemistry—binary halides,chalcogenides,and ternary families(e.g.,MPX_(3),M_(m)X_(n)Te_(k),MnBi_(2)Te_(4))—followed by a summary of their coupling mechanisms,ordering temperatures,and dimensional effects.It then analyzes the modulation of exchange interactions,magnetic anisotropy,and topological states by electric-field gating,strain engineering,and ion intercalation,with representative experimental demonstrations.Notable advances include room-temperature ferromagnetic metals and semiconductors,observation of the quantum anomalous Hall effect(QAHE)in MnBi2Te4,and synergistic control of magnetic-topological states under multiple external stimuli.Persistent challenges involve the limited availability of intrinsic 2D magnetic semiconductors with high Curie temperatures(Tc),incomplete understanding of the microscopic couplings at interfaces and under quantum confinement,and device-level stability.We conclude by outlining opportunities that lie in the integration of multiscale characterization,first-principles theory,and cross-scale fabrication to precisely co-engineer magnetism,topology,and electronic structure,thereby advancing LTMCs toward spintronic and topological-quantum applications.
文摘Chitosan(CTS)was grafted onto the surface of amino‑functionalized silver chloride silicon dioxide(AgCl@SiO_(2)‑NH_(2))cores to obtain AgCl@SiO_(2)/CTS hybrid nanoparticles.The as‑obtained AgCl@SiO_(2)/CTS nanoparticles were chlorinated by NaClO solution to get AgCl@SiO_(2)/CTS‑based chloramine nano‑hybrid materials,denoted as AgCl@SiO_(2)/CTS‑Cl.A transmission electron microscope was used to observe the morphology of the as‑prepared samples AgCl@SiO_(2)/CTS and AgCl@SiO_(2)/CTS‑Cl.At the same time,an X‑ray diffractometer and an infrared spectroscope were utilized to characterize their crystal and chemical structures.Besides,ζpotentials were measured to elucidate the surface modification of AgCl nanoparticles by—NH_(2),the antibacterial mechanism of AgCl@SiO_(2)/CTS‑Cl was investigated by scanning electron microscopy,and Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)were used as the to‑be‑tested strains to evaluate the antimicrobial activity of samples AgCl@SiO_(2)/CTS and AgCl@SiO_(2)/CTS‑Cl.Findings demonstrate that sample AgCl@SiO_(2)/CTS exhibits a chain‑like structure ascribed to the interaction between—NH_(2),and each AgCl@SiO_(2)/CTS hybrid nanoparticle contains several AgCl cores.In the meantime,sample AgCl@SiO_(2)/CTS‑Cl exhibits excellent antibacterial activity against E.coli and S.aureus,which is attributed to the synergistic antibacterial effect of Ag^(+)and Cl^(-).Sample AgCl@SiO_(2)/CTS‑Cl with a dosage of 640.00μg·mL^(-1) could completely kill the two kinds of tested bacteria in 12 h of incubation;it retains a high antibacterial efficiency even after 10 cycles of antibacterial tests.
文摘A series of blue and blue‑green Ir(Ⅲ)complexes has been investigated theoretically to explore their electronic structures,photophysical properties,efficiency roll‑off effect,and thermal activation delayed fluorescence(TADF)properties.All calculations were performed using density functional theory(DFT)and time‑dependent density functional theory(TDDFT).Calculations for electronic structures,frontier molecular orbital characteristics(which determine the efficiency roll‑off effect of the complexes),and photophysical properties were conducted using the Gaussian 09 software package.The calculation of spin‑orbit coupling matrix elements<T|HSOC|S>,which determine the TADF properties of the complexes,was performed using the ORCA software package.The calculation results show that the auxiliary ligand tetraphenylimidodiphosphinate(tpip),a strong electron‑withdrawing group,can mitigate the efficiency roll‑off effect of the complex.Furthermore,TADF is observed in one of the designed complexes,(F_(3)Phppy)_(2)Ir(tpip),where F_(3)Phppy=2‑[4‑(2,4,6‑trifluorophenyl)phenyl]pyridine.
基金Projects(2023 YFC 2907602,2022 YFF 1303302)supported by the National Key Research and Development Project of ChinaProject(52342404)supported by the National Natural Science Foundation of China+2 种基金Project(GXXT-2021-075)supported by the University Synergy Innovation Program of Anhui Province,ChinaProject(2022AH010053)supported by Excellent Scientific Research and Innovation Team of Universities in Anhui Province,ChinaProject(2022xscx080)supported by Anhui Provincial Department of Education Graduate Student Academic Innovation Fund,China。
文摘To study the influence of support timing and support strength on the mechanical properties and deformation damage characteristics of a single-sided unloaded rock mass,a true triaxial perturbation unloaded rock testing system was used to conduct rock damage tests on sandstone with different support timing and strength paths.Based on the acoustic emission monitoring system,the spatial and temporal evolution characteristics of the whole process of rock body loaded instability under two stress paths were studied,and the mechanism of the reinforcing effect of stress support on the unloaded rock mass was analyzed.The results show that,within the scope of this study,both earlier applications of shoring and an increase in shoring strength can effectively improve the ultimate bearing capacity of the unloaded rock,which increases the ultimate bearing capacity of the unloaded rock mass by 60.31% and 54.96%,respectively;There is a phenomenon of rebound deformation of the rock mass during sudden changes in stress(single-sided unloading,stress support),which shows opposite expansion and compression platforms on the stress−strain curve;The crack evolution of unloaded rock under different stress support conditions shows the state law of"initial crack activation→middle steady state expansion→late main crack penetration",and the lagging support significantly accelerates the crack evolution from local activation to main penetration;The single-sided unloading and stress-supporting stages have less influence on the unloading deformationsσ_(1u),σ_(2u) and support deformationsσ_(1) t,σ_(2t) in theσ_(1) andσ_(2)directions,while they show significant response characteristics toσ_(3u),σ_(vu) and σ_(3) t,σ_(vt),and with the increase of the support strength,the stress-supporting stagesσ_(3) t,σ_(vt) gradually increase and exceed the deformations generated by the unloading stagesσ_(3u),σ_(vu);The increase of support strength can effectively compensate for the rock stress loss caused by unloading,which makes the maximum,minimum,and volumetric strain support coefficients during the loading and unloading of the rock body increase gradually while the effect on the intermediate principal strain support coefficient is small;During loading,the support strength of rock masses seeks a new bearing area by regulating stress equilibrium states.This process primarily manifests as a shift in the locations of the crushing zone and the main bearing area,accompanied by a corresponding transformation in failure patterns.Consequently,the rock mass transitions from asymmetric three-zone damage under no or weak support to approximate symmetric three-zone damage under strong support.Simultaneously,the main load-bearing area of the rock mass shifts from deep bearing in the unsupported to middle bearing under strong support as the support strength increases.
基金funded by the Deanship of Graduate Studies and Scientific Research at Jouf University(Grant No.DGSSR-2025-NF-02-028).
文摘This study investigates the thermoviscoelastic behavior of Kirchhoff circular microplates by integrating the nonlocal Moore-Gibson-Thompson(MGT)thermoelastic model with the modified couple stress theory(MCST)and a nonlocal thermal length-scale parameter.It emphasizes the significance of size-dependent effects in microscale structures,which are often overlooked in classical continuum me-chanics.To enhance the model's accuracy in capturing mechanical and thermal responses,a Kelvin-Voigt viscoelastic framework is employed,addressing the interplay between elastic and viscous ef-fects.Using Hamilton's principle,the governing equations incorporate thermal relaxation time and temperature-dependent thermal conductivity.The study focuses on a clamped circular microplate subjected to thermal shock heating at its outer boundary.Numerical simulations explore the influence of key factors,such as viscosity,thermal length-scale parameters,and scale-dependent effects,on displacement,temperature fields,and thermal stresses.The results reveal that nonlocal elasticity significantly modifies deformation and stress distributions,enhancing stiffness and reducing energy dissipation.Viscosity effectively dampens vibrations and influences thermal diffusion,while size-dependent effects become increasingly pronounced as the microplate size decreases.These findings offer valuable insights for the design of advanced micro-electromechanical systems(MEMS),nano-resonators,and thermal devices,highlighting the necessity of incorporating nonlocality and viscoelastic properties to improve performance and reliability.
文摘This paper prepared a novel as-cast W-Zr-Ti metallic ESM using high-frequency vacuum induction melting technique.The above ESM performs a typical elastic-brittle material feature and strain rate strengthening behavior.The specimens exhibit violent chemical reaction during the fracture process under the impact loading,and the size distribution of their residual debris follows Rosin-Rammler model.The dynamic fracture toughness is obtained by the fitting of debris length scale,approximately 1.87 MPa·m~(1/2).Microstructure observation on residual debris indicates that the failure process is determined by primary crack propagation under quasi-static compression,while it is affected by multiple cracks propagation in both particle and matrix in the case of dynamic impact.Impact test demonstrates that the novel energetic fragment performs brilliant penetration and combustion effect behind the front target,leading to the effective ignition of fuel tank.For the brittleness of as-cast W-ZrTi ESM,further study conducted bond-based peridynamic(BB-PD)C++computational code to simulate its fracture behavior during penetration.The BB-PD method successfully captured the fracture process and debris cloud formation of the energetic fragment.This paper explores a novel as-cast metallic ESM,and provides an available numerical avenue to the simulation of brittle energetic fragment.
基金supported by the Major Projects for Science and Technology Innovation 2030(2018AAA0100805)National Natural Science Foundation of China(62373187).
文摘The evaluation of air combat decision-making has garnered significant attention due to its potential to effectively mitigate losses resulting from erroneous decisions.However,existing research primarily focuses on static evaluation methods.Therefore,this paper proposes a dynamic multi-round decision evaluation method based on the characteristics of multi-round unmanned aerial vehicle air combat under opponent’s optimal strategy.In order to determine objective weights,an improved multi-attribute decision making method is proposed,which incorporates the proximity as a correction coefficient for evaluation indicators,utilizing the cosine similarity instead of Euclidean distance,and incorporating both actual and theoretical objective weights to prevent data mutations.Subsequently,the game theory is employed to reasonably adjust subjective and objective weights to obtain comprehensive weights.To address the issues related to the ambiguity and randomness during the evaluation process,a reverse cloud generator is utilized to determine the center of gravity of the cloud model using comprehensive weights while employing the weighted deviation degree for evaluating air combat decision-making effectiveness.By activating the cloud generator through the cloud model,the optimal strategies for each round of air combat are determined,thereby completing the dynamic evaluations for multi-round sequential decision-making processes.Finally,the feasibility and effectiveness of the proposed method are verified through simulations.
基金Project(42072305)supported by the National Natural Science Foundation of China。
文摘Seabed mining operations have been found to induce significant movement and deformation in overlying rock strata,posing serious threats to mining safety.The presence of geological faults further complicates these deformation patterns.This study utilized geophysical surveys and the continuum-based discrete element method(CDEM)to investigate how fault activity influences rock deformation and failure.The results demonstrate that:1)Acting in mechanically weak zones,faults exerted a pronounced barrier effect on deformation propagation and stress redistribution within the surrounding rock,leading to markedly divergent displacement patterns on either side of the fault plane.Comparative analyses between single-fault and double-fault models revealed an 18%−22%expansion of the damage zone under the latter,together with significantly intensified deformation and failure;2)The double-fault model exhibited a larger maximum cumulative vertical displacement and a spatial shift in the location of peak deformation,thereby posing a heightened threat to mine safety;3)Acting in an orebody substitute,backfill effectively constrained surrounding rock deformation,enhanced its load-bearing capacity,and delayed the overburden subsidence.Nevertheless,backfill only reduced the amplitude of deformation;it could not entirely prevent settlement.These findings provide essential theoretical insights and foundational knowledge for safer submarine mining practices.
文摘Bay-site carboxyl functionalized perylene diimide derivative 1,7-COOH-PDI-C_(12)(PDI-COOH)was synthesized and distinct enhanced fluorescence was observed through combining with calcium ion(Ca^(2+))in THF/H_(2)O solution.The assembly and fluorescence behavior of PDI-COOH/Ca^(2+)were studied in detail by changing hydration state with different concentrations.Based on the differences in assembly morphology and stoichiometric ratios of PDICOOH/Ca^(2+),we proposed the fluorescence emission mechanism of PDI-COOH/Ca^(2+)in THF/H_(2)O and THF,respectively.This work reveals a novel strategy of aggregated state fluorescence enhancement and reminds us of the important role of water in molecular fluorescence emission and assembly.
文摘A functional interlayer based on two-dimensional(2D)porous modified vermiculite nanosheets(PVS)was obtained by acid-etching vermiculite nanosheets.The as-obtained 2D porous nanosheets exhibited a high specific surface area of 427 m^(2)·g^(-1)and rich surface active sites,which help restrain polysulfides(LiPSs)through good physi-cal and chemical adsorption,while simultaneously accelerating the nucleation and dissolution kinetics of Li_(2)S,effec-tively suppressing the shuttle effect.The assembled lithium-sulfur batteries(LSBs)employing the PVS-based inter-layer delivered a high initial discharge capacity of 1386 mAh·g^(-1)at 0.1C(167.5 mAh·g^(-1)),long-term cycling stabil-ity,and good rate property.
基金financially supported by the project of the National Natural Science Foundation of China(52322203)the Key Research and Development Program of Shaanxi Province(2024GHZDXM-21)。
文摘The design of cost-effective and efficient metal-free carbon-based catalysts for the hydrogen evolution reaction(HER)is of great significance for increasing the production of clean hydrogen by the electrolysis of alkaline water.Precise control of the electronic structure by heteroatom doping has proven to be efficient for increasing catalytic activity.Nevertheless,both the structural characteristics and the underlying mechanism are not well understood,especially for doping with two different atoms,thus limiting the use of these catalysts.We report the production of phosphorus and nitrogen co-doped hollow carbon nanospheres(HCNs)by the copolymerization of pyrrole and aniline at a Triton X-100 micelle-interface,followed by doping with phytic acid and carbonization.The unique pore structure and defect-rich framework of the HCNs expose numerous active sites.Crucially,the combined effect of graphitic nitrogen and phosphorus-carbon bonds modulate the local electronic structure of adjacent C atoms and facilitates electron transfer.As a res-ult,the HCN carbonized at 1100°C exhibited superior HER activity and an outstanding stability(70 h at a current density of 10 mA cm^(−2))in alkaline water,because of the large number of graphitic nitrogen and phosphorus-carbon bonds.
基金financially supported by National Natural Science Foundation of China(Grant Nos.52378401,52278504)the Fundamental Research Funds for the Central Universities(Grant No.30922010918)。
文摘Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.
基金Project(51378510) supported by the National Natural Science Foundation of China。
文摘In existing studies, most slope stability analyses concentrate on conditions with constant temperature, assuming the slope is intact, and employ the Mohr-Coulomb (M-C) failure criterion for saturated soil to characterize the strength of the backfill. However, the actual working temperature of slopes varies, and natural phenomena such as rainfall and groundwater infiltration commonly result in unsaturated soil conditions, with cracks typically present in cohesive slopes. This study introduces a novel approach for assessing the stability of unsaturated soil stepped slopes under varying temperatures, incorporating the effects of open and vertical cracks. Utilizing the kinematic approach and gravity increase method, we developed a three-dimensional (3D) rotational wedge failure mechanism to simulate slope collapse, enhancing the traditional two-dimensional analyses. We integrated temperature-dependent functions and nonlinear shear strength equations to evaluate the impact of temperature on four typical unsaturated soil types. A particle swarm optimization algorithm was employed to calculate the safety factor, ensuring our method’s accuracy by comparing it with existing studies. The results indicate that considering 3D effects yields a higher safety factor, while cracks reduce slope stability. Each unsaturated soil exhibits a distinctive temperature response curve, highlighting the importance of understanding soil types in the design phase.
基金supported by the National Natural Science Foundation of China(Grant No.12172052)the Foundation of State Key Laboratory of Explosion Science and Safety Protection(Grant No.QKKT24-02).
文摘The penetration-deflagration coupling damage performance of rod-like reactive shaped charge pene-trator(RRSCP)impacting thick steel plates is investigated by theoretical analysis and experiments.A penetration-deflagration coupling damage model is developed to predict the penetration depth and cratering diameter.Four type of aluminum-polytetrafluoroethylene-copper(Al-PTFE-Cu)reactive liners with densities of 2.3,2.7,3.5,and 4.5 g·cm^(-3) are selected to conduct the penetration experiments.The comparison results show that model predictions are in good agreement with the experimental data.By comparing the penetration depth and cratering diameter in the inert penetration mode and the penetration-deflagration coupling mode,the influence mechanism that the penetration-induced chemical response is unfavorable to penetration but has an enhanced cratering effect is revealed.From the formation characteristics,penetration effect and penetration-induced chemical reaction be-haviors,the influence of reactive liner density on the penetration-deflagration performance is further analyzed.The results show that increasing the density of reactive liner significantly increases both the kinetic energy and length of the reactive penetrator,meanwhile effectively reduces the weakened effect of penetration-induced chemical response,resulting in an enhanced penetration capability.However,due to the decreased diameter and potential energy content of reactive penetrator,the cratering capa-bility is weakened significantly.
基金Project(42277175)supported by the National Natural Science Foundation of ChinaProject(NRMSSHR-2022-Z08)supported by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources,China。
文摘Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsaturated seepage multi-field coupling,resulting in inaccurate estimates.To address these deficiencies,this paper proposed a calculation method for seismic passive earth pressure in unsaturated narrow backfill,based on inclined thin-layer units.It considers the interlayer shear stress,arching effect,and the multi-field coupling of seismic-unsaturated seepage.Additionally,this paper includes a parametric sensitivity analysis.The outcomes indicate that the earthquake passive ground pressure of unsaturated narrow backfill can be reduced by increasing the aspect ratio,seismic acceleration coefficient,and unsaturation parameterα.It can also be reduced by decreasing the effective interior friction angle,soil cohesion,wallearth friction angle,and vertical discharge.Furthermore,for any width soil,lowering the elevation of the action point of passive thrust can be attained by raising the effective interior friction angle,wall-earth friction angle,and unsaturation parameterα.Reducing soil cohesion,seismic acceleration coefficient,and vertical discharge can also lower the height of the application point of passive thrust.
