In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,d...In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,due to their voltage source behavior and emulated swing dynamics,GFM converters may encounter low-frequency oscillations(LFOs)when connected to strong grids,which belongs to the self-stability problem of GFM converters.Moreover,GFM converters will also interact with grid-following(GFL)converters and thus impact the mid-frequency oscillations(MFOs)induced by phase-locked loops(PLLs).It has been preliminarily shown in the literature that GFM converters can help stabilize the PLL-induced MFOs,but currently,there is a lack of systematic design methods to coordinate the self-stability and stabilizing ability of GFM converters.This paper addresses this gap by revisiting the impedance model of a typical GFM converter and briefly analyze the oscillations caused by converters.Based on our analysis,we propose a frequency-partitioned synthesis design framework to enable dynamic virtual impedance(DVI)in GFM converters,aiming to enhance their self-stability and stabilizing ability simultaneously.Particularly,a self-stabilizing module is designed to ensure robust device-level damping,with control parameters auto-tuned using H∞methods.In parallel,a stabilizing module is introduced to stabilize GFL converters and enhance the system-level stability,which utilizes a perceive-and-optimize tuning strategy.Simulation results validate the effectiveness of the proposed synthesis DVI framework.展开更多
Rapid industrialization in China has caused significant environmental challenges,particularly heavy metal pollution from mine tailings.Toxic heavy metals such as lead(Pb),cadmium(Cd),and mercury(Hg)are released during...Rapid industrialization in China has caused significant environmental challenges,particularly heavy metal pollution from mine tailings.Toxic heavy metals such as lead(Pb),cadmium(Cd),and mercury(Hg)are released during the processing of mining wastewater and leaching of mine tailings.Owing to their excellent physicochemical properties,cementitious materials are widely used for the solidification/stabilization of heavy metals,immobilizing heavy metals via two distinct mechanisms.Physically,their favorable characteristics,including high mechanical strength,low porosity,and durable matrix,create effective barriers.Chemically,the alkaline environment facilitates the precipitation of metal hydroxides/carbonates.Conversely,hydration products(calcium silicate hydrate gels and ettringite)contribute to immobilization through adsorption and physical encapsulation.This study systematically investigated the migration mechanisms of heavy metal contaminants in mine tailings;further,it elucidated the multifaceted immobilization pathways of cementitious materials,which involve synergistic adsorption,precipitation,and encapsulation by hydration products combined with homocrystalline substitution.A comprehensive analysis indicated that cementitious materials significantly reduced the mobility and bioavailability of heavy metals.Nonetheless,their long-term stability and potential environmental impact require further investigation.This study aims to provide theoretical support for environmental management and sustainable resource utilization,and to explore the broader application potential of cementitious technology for heavy metal stabilization,thereby establishing a theoretical foundation for future research on heavy metals in low-cement solidified/stabilized tailings.展开更多
Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration...Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration and freeze–thaw(FT) cycles is a significant factor causing slope failure. This study aims to investigate the transmedia seepage characteristics at slope–concrete stabilizing pile interface systems by using silty clay and concrete with varying microstructure characteristics under FT cycles. To this end, a self-developed indoor test device for transmedia water migration, combined with a macro-meso-micro multiscale testing approach, was used to analyze the laws and mechanisms of transmedia seepage at the interface systems. The effect of the medium's microstructure characteristics on the transmedia seepage behavior at the interface systems under FT cycles was also assessed. Results indicated that the transmedia water migration exhibited particularity due to the migration of soil particles and the low permeability characteristics of concrete. The water content in the media increased significantly within the range of 1/3–2/3 of the height from the interface for soil and within 5 mm from the interface for concrete.FT cycles promoted the increase and penetration of cracks within the medium, enhancing the permeability of the slope-concrete stabilizing pile interface systems.With the increase in FT cycles, the porosity inside the medium first decreased and then increased, and the porosity reached the minimum after 25 FT cycles and the maximum after 75 FT cycles, and the water content of the medium after water migration was positively correlated with the porosity. FT cycles also significantly influenced the temporal variation characteristics of soil moisture and the migration path of water in concrete. The study results could serve as a reference for related research on slope stability assessment.展开更多
The remediation of lead-contaminated dredged sediments(LDS)presents significant environmental challenges.This study investigates the solidification/stabilization(S/S)mechanisms of ordinary Portland cement(OPC)modified...The remediation of lead-contaminated dredged sediments(LDS)presents significant environmental challenges.This study investigates the solidification/stabilization(S/S)mechanisms of ordinary Portland cement(OPC)modified with nano-silica(NS)across a continuum from nanoscale interactions to macroscopic performance.For this,a series of macroscopic experiments was conducted to evaluate the mechanical performance and lead-encapsulation efficiency,including unconfined compressive strength(UCS)and toxicity characteristic leaching procedure(TCLP).Microstructural and phase transformations were characterized using X-ray diffraction,thermogravimetric analysis,and scanning electron microscope.Molecular dynamics simulations revealed the interactions between NS-modified cement,calcium silicate hydrates(C-S-H)gel,and Illite,focusing on interaction energies,atomic density distributions and structural changes.Macroscopic analyses demonstrated that increasing NS content from 0%to 8%improved Pb-immobilization rate from 88.7%to 97.6%and enhanced UCS from 764 kPa to 1358 kPa.These improvements were attributed to NS enhancing the microstructural integrity of C-S-H gel and filling pores in samples.Nanoscale simulations elucidated that Pb-stabilization occurs through coordination bonds with oxygen atoms in the C-S-H silicon chains and on Illite surfaces,complemented by the formation of stable Pb_(3)(CO)_(3)(OH)_(2)precipitates.Additionally,the simulations revealed that Ca^(2+)migration from hydration products to mineral surfaces generated substantial repulsive interaction energies,reducing Illite layer dispersion.However,the presence of Pb impeded further Ca^(2+)migration,leading to expansion of the C-S-H gel,which collectively degraded the mechanical properties of the material.Furthermore,wet-dry and freeze-thaw cycles showed that after 10 cycles,UCS and TCLP results still met the United States Environmental Protection Agency standards,confirming long-term durability.This study provides a theoretical foundation for resource utilization of the contaminated sediments and offers a perspective for design of the cement-based curing agents,particularly in addressing variations in pollutant concentrations and environmental conditions,advancing the application of responsive and controlled release curing agents.展开更多
Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM)to approach its theoretical capacity.However,NCM suffers from structural degra...Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM)to approach its theoretical capacity.However,NCM suffers from structural degradation in deep delithiation state,which is often accompanied by severe surface lattice oxygen loss and transition metal dissolution,leading to restricted cycle life.Herein,a facile and effective surfacestrengthening strategy is proposed,in which Mn(OH)_(2)nanoshells are uniformly grown on the NCM surface as a Li~+capturer and then converted to thin spinel Li_(4)Mn_(5)O_(12)layers during subsequent hightemperature sintering.The resultant Li_(4)Mn_(5)O_(12)layers can enhance cathode-electrolyte interface electrochemical stability with inhibited electrolyte corrosion and accelerated Li~+kinetics.The theoretical calculations confirms that the Mn-O bonds formed at the interfaces can effectively decrease the oxygen activity,thereby further inhibiting the lattice oxygen release and structural degradation caused by the irreversible phase transition.Consequently,the Li_(4)Mn_(5)O_(12)-coated NCM displays high capacity retention of 80.3%and 94.9%at 1 C and 5 C compared to the pristine NCM(52.5%and 10.1%)after 200 cycles and can operate stably at 2.7-4.6 V and 60℃.The spinel Li_(4)Mn_(5)O_(12)-coating demonstrates an effective route to enhance the structural/electrochemical stability of NCM for next-generation advanced lithium-ion batteries.展开更多
Aqueous sodium-ion batteries(ASIBs) offer significant advantages for energy storage on a large scale,attributed to their economical cost,secure operatio n,and eco-friend ly natu re.Among the leading cathode materials ...Aqueous sodium-ion batteries(ASIBs) offer significant advantages for energy storage on a large scale,attributed to their economical cost,secure operatio n,and eco-friend ly natu re.Among the leading cathode materials for ASIBs,Na_(3)V_(2)(PO_(4))_(3)(NVP) exhibits excellent structural stability and a high Na+diffusion coefficient,making it a promising option.However,the high solubility of vanadium-based materials in aqueous electrolytes engenders suboptimal cycling stability for Na_(3)V_(2)(PO_(4))_(3),constraining its application in ASIBs.Herein,the Cr-substituted Na_(3)V_(1.3)Cr_(0.7)(PO_(4))3@C(NV_(1.3)Cr_(0.7)P) cathode material was synthesized via a simple sol-gel method.It is found that Cr substitution reduces the cell parameters of NV_(1.3)Cr_(0.7)P,effectively reinforcing the crystal structure.Furthermore,NV_(1.3)Cr_(0.7)P alters the Na^(+)insertion/extraction mechanism,transforming the typical two-phase reaction between Na_(1)V_(2)(PO_(4))_(3)and Na_(3)V_(2)(PO_(4))3into continuous solid-solution reactions with stable intermediates.The Cr substitution diminishes the sodium-ion diffusion energy barrier in NV_(1.3)Cr_(0.7)P,leading to smoother Na+insertion and extraction processes.Consequently,NV_(1.3)Cr_(0.7)P exhibits impressive cycling stability,retaining 74.8% of its capacity after 5,000 cycles at a current density of 5 A g^(-1),along with an outstanding rate performance of 79,2% at 10 A g^(-1).This work elucidates the stable Na^(+)insertion/extraction processes in Cr-substituted NV_(1.3)Cr_(0.7)P,offering insights into the application of vanadium-based materials in aqueous sodium-ion batteries.展开更多
P2-type layered oxides are highly promising cathode candidates for sodium-ion batteries(SIBs)owing to their substantial theoretical capacity.Nevertheless,structural degradation caused by transition metal dissolution a...P2-type layered oxides are highly promising cathode candidates for sodium-ion batteries(SIBs)owing to their substantial theoretical capacity.Nevertheless,structural degradation caused by transition metal dissolution and irreversible phase transitions at high voltage severely compromises cycling stability.To address this limitation,we propose a Li/Ti co-doping strategy to design a Na_(0.67)Li_(0.06)Ni_(0.27)Mn_(0.5)7Ti_(0.1)O_(2)(NLMT) cathode for SIBs.In-situ X-ray diffraction(XRD) confirms that this deliberate strategy eliminates the adverse phase transition at high voltage and sustains the unitary P2phase throughout cycling.In addition,strengthened transition metal-oxygen(TM-O) bonding via electronic modulation suppresses transition metal dissolution and reinforces the layered oxide framework,contributing to exceptional electrochemical performance.Consequently,the NLMT cathode exhibits an outstanding capacity of 92.8 mA h g^(-1) within 2.5-4.3 V at 5 C(865 mA g^(-1)),with 87 % capacity retention over 200 cycles.Configured into a full cell,which achieves a competitive capacity of 107.7 mA h g^(-1) at0.1 C and retains 86.4 % capacity over 100 cycles at 0.5 C.This study validates co-doping as a potent strategy for significantly improving the long-term cyclability of layered oxide cathodes in SIBs.展开更多
We investigate a class of non-integrable two-particle Calogero-Moser systems modulated by a power-law external potential.The local well-posedness of the Cauchy problem is established under the strict initial separatio...We investigate a class of non-integrable two-particle Calogero-Moser systems modulated by a power-law external potential.The local well-posedness of the Cauchy problem is established under the strict initial separation condition for the particles.For suitably prepared initial configurations,local solutions can be extended globally via energy conservation;conversely,negative energy conditions induce(in)finite-time blowup.The linear(in)stability of stationary solutions is analyzed,with their energy serving as a threshold.Numerical investigations employ a fourth-order Runge-Kutta scheme with adaptive step-size control.Simulations demonstrate that the trajectories either converge to steady states or exhibit blowup,depending on the power exponent α and initial conditions.Increasingαaccelerates the convergence rate and dampens oscillatory dynamics,promoting a transition from periodic behavior to static equilibrium.展开更多
Selective electrocatalytic semi-hydrogenation(ECSH)of alkynes in water using Cu catalysts is highly relevant for the production of value-added chemicals.However,achieving high olefin selectivity still poses extreme ch...Selective electrocatalytic semi-hydrogenation(ECSH)of alkynes in water using Cu catalysts is highly relevant for the production of value-added chemicals.However,achieving high olefin selectivity still poses extreme challenges due to the susceptibility of the copper cathode in a reduction environment.Herein,a small molecule modulation electrodeposition strategy is introduced that regulates the structure of Cubased materials through modification with citric acid(CA)ligands,aiming for highly active and selective ECSH.The as-prepared EDCu-CA electrode achieves more than 97%alkyne conversion and 99%olefin selectivity.In-situ Raman and Auger electron spectroscopy(AES)data provide evidence that active Cu^(+)sites can stably exist in the EDCu-CA during the catalytic process.Density functional theory(DFT)calculations indicate that the modulation by CA contributes to maintaining Cu in a positive valence state,and Cu^(+)can inhibit the over-hydrogenation of olefins.Moreover,by utilizing a large-area electrode for longterm electrolysis,g-level conversion and a 92%separation yield of olefin can be achieved,demonstrating a viable application prospect.This study offers a promising route for designing Cu-based catalysts for the highly selective electrocata lytic conversion of organic substrates to value-added chemicals in water.展开更多
In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes ...In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes in population density.In this paper,we consider a reaction-diffusion-advection model with nonlocal delay and Dirichlet boundary conditions.First of all,we investigate the well-posedness of solution of model.Then,the existence of positive steady state is proofed by implicit function theorem.Based on a priori estimate for the eigenvalue,we prove the stability of the positive steady state and conclude the associated distribution of Hopf bifurcation.Our research indicates that the combined effects of nonlocal and time delays have a certain impact on the dynamics of the model.展开更多
Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-dope...Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.展开更多
Quantitative real-time PCR(qPCR)is widely used for gene expression analysis,but its accuracy critically depends on stable internal reference genes for normalization.In marine invertebrates,especially non-model taxa su...Quantitative real-time PCR(qPCR)is widely used for gene expression analysis,but its accuracy critically depends on stable internal reference genes for normalization.In marine invertebrates,especially non-model taxa such as cephalopods,systematic evaluation of reference genes is limited,leading to potential bias.The cuttlefish Sepiella japonica is ecologically and economically important in China,yet previous molecular studies have often relied on single unvalidated reference genes,which may compromise data reliability.This study aimed to systematically evaluate the stability of five commonly used reference genes(18S,ef-1α,ef-1γ,gapdh,andβ-actin)across multiple tissues and sexes of S.japonica,and to identify the most suitable reference genes and optimal number for qPCR normalization.Fifteen to sixteen tissue types were collected from ten healthy adults(five males and five females).Total RNA was extracted,reverse-transcribed,and analyzed by qPCR.Gene stability was assessed using four algorithms(geNorm,NormFinder,BestKeeper,andΔCt)integrated with RefFinder,and the optimal gene number was determined using geNorm pairwise variation(V_(n/n+1)<0.15).Four transcriptome-derived genes(creld2,cd109,acy1,and miox)were used for validation.The C_(t)values of the five genes ranged from 15.47 to 20.83.β-actin and gapdh showed pronounced variability in expression stability among tissues and sexes,indicating their limited suitability for normalization.18S exhibited the highest expression(mean C_(t):15.47-16.29)and lowest variability but displayed sex-biased expression,whereas ef-1αand ef-1γremained consistently stable across most tissues in both sexes,with ef-1αbeing the most robust and showing no sex-related bias.Although specific rankings varied among tissues and sexes,the comprehensive results indicated that ef-1αand ef-1γpossessed the highest overall stability,followed by 18S,whileβ-actin and gapdh were the least stable.The final comprehensive rankings were ef-1γ>ef-1α>18S>gapdh>β-actin(male)and ef-1α>ef-1γ>18S>gapdh>β-actin(female).geNorm analysis(V2/3<0.15)indicated that two genes,mainly ef-1αand ef-1γ,were generally sufficient for reliable normalization in most tissues.Validation confirmed that normalization using the stable ef-1αand ef-1γaccurately reflected the expression differences among tissues,whereasβ-actin and gapdh can bias or confound statistical analyses.ef-1αand ef-1γare identified as the most reliable reference gene combination for qPCR analysis in S.japonica,while 18S can serve as an auxiliary gene for within-sex comparisons.The use ofβ-actin or gapdh alone is not recommended.This study establishes a systematic framework for selecting reliable reference genes in S.japonica,thereby facilitating robust qPCR normalization and providing a foundation for future gene expression research in S.japonica and other cephalopods.展开更多
Vitamin C,a potent antioxidant with broad therapeutic applications,is limited by rapid degradation under environmental stressors,which compromises its stability and bioactivity.This study addresses these limitations b...Vitamin C,a potent antioxidant with broad therapeutic applications,is limited by rapid degradation under environmental stressors,which compromises its stability and bioactivity.This study addresses these limitations by formulating a double nano-emulsion(W/O/W)system incorporating macadamia oil and tea tree oil,using homogenization and phase inversion temperature(PIT)techniques.Comprehensive physicochemical charac-terization,including droplet size,polydispersity index(PDI),zeta potential,turbidity,Fourier transform infrared spectroscopy(FTIR),and SEM,was conducted alongside stability assessments under varying pH,temperature,and storage conditions.The optimized nano-emulsions exhibited nanoscale droplet sizes(10-40 nm),low PDI values(indicating high uniformity),and robust stability.Interestingly,the formulation with 2%W/O loading,with a particle size of 11.57 nm and a PDI of 0.04,demonstrated an antioxidant capacity of 4622.62μg ascorbic acid equivalents(AA)/g,which was significantly higher(p<0.05)compared to both natural oils(macadamia oil:20.91μg AA/g,tea tree oil:16.86μg AA/g)and a 10%Vitamin C aqueous solution(592.94μg AA/g).FTIR analysis confirmed the molecular integrity of Vitamin C and its successful encapsulation with macadamia and tea tree oils,while SEM images revealed uniformly spherical and well-dispersed droplets.Moreover,the formulation retained its structural integrity and antioxidant functionality under diverse pH and thermal conditions.These findings underscore the potential of double nano-emulsion systems to overcome the stability challenges of Vitamin C,offering a promising approach to enhance its bioavailability and therapeutic performance in phar-maceutical and cosmetic applications.展开更多
The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as...The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as-cast alloys maintain their original single body-centered cubic(bcc)structure.As for the mechanical properties,compared with those without Ti addition,the strength and ductility of NbTaMoWTi,alloys increase by 93%and 215%,respectively.Furthermore,the NbTaMoWTi alloys exhibit outstanding thermal stability.After annealing at 1400 C,they still maintain the single bcc structure,and their mechanical properties are even slightly improved.However,annealing leads to a significant deterioration in the mechanical properties of high-Ti-content alloys(NbTaMoWTil and NbTaMoWTi2),owing to the formation of Ti-rich acicular phases.展开更多
The uncontrollable dendrite growth of lithium anode and active material dissolution of transition metal oxides cathodes severely hinder the development of lithium metal batteries.An effective strategy to address these...The uncontrollable dendrite growth of lithium anode and active material dissolution of transition metal oxides cathodes severely hinder the development of lithium metal batteries.An effective strategy to address these issues is optimizing the separator to regulate ion transport and trap the lost active component.Herein,a crosslinked gelatin nonwoven(CGN)separator is elaborately fabricated through electrospinning and in-situ vapor phase crosslinking process to manipulate the dual electrode interface.Benefitting from the characteristic composition of gelatin,and porous structure of electrospun nonwoven,the CGN separator exhibits excellent interface wettability and low interface resistance,featuring a high Li^(+)transference number of 0.70 and high ionic conductivity of 3.75 m S/cm.As expected,the symmetrical Li/Li cells present stable cycling behavior for 1900 h at 0.5 mA/cm^(2)with low overpotential of 20 mV.The optimized LiMn_(2)O_(4)/Li cells deliver high reversible capacity of 103 m Ah/g as well as high capacityretention ratio of 83.7%after 100 cycles at 0.3 C,which can be effectively attributed to the strong interaction between CGN separator and Mn ions to prevent the loss of active Mn component.This study indicates the application potential of protein-based electrospun membrane for high-performance lithium metal batteries.展开更多
Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in te...Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in temperature and their subgrade condition within the active zone due to the structures'technogenic impact.Design solutions for the fifty-year-old structures fail to ensure in all cases their reliable operation at the present time.The greatest danger to the reliable operation of railway lines in cold regions is uneven deformations of bridges,which are barrier places.Therefore,the solution to this problem is urgent especially due to the necessity of increase carrying capacity.The purpose of this study is to increase reliability of bridge operation in cold regions through strengthening the subgrade by reinforcement with injection of solidifying solutions.The problem of uneven deformations due to permafrost degradation is considered using the example of a railway bridge located in the northern line of the Krasnoyarsk railway.Deformations of the bridge abutments began immediately after the construction was completed and the bridge was open for traffic-since 1977.Permafrost degradation was developing more actively straight under the abutments due to higher thermal conductivity of the piles concrete.Notably,thawing intensity of frozen soils under the bridge abutments is uneven due to its orientation to the cardinal points.The analysis of archive materials and results of the geodetic survey made it possible to systematize the features of augmenting deformations of each abutment over time.The engineering-geological survey with drilling wells near the abutments ensured determination of soil characteristics,both in the frozen and thawed states.Thermometric wells were arranged to measure temperatures.The analysis and systematization of the data obtained allowed us to develop geotechnical models for each abutment of the bridge.The peculiarity of these models is allowance for changes in the strength and deformation characteristics of the soil calculated layers depending on changes in temperature and the soil condition.Thus,different calculated geological elements with the corresponding strength and deformation characteristics were identified in the soil layers of the same origin.The analysis of the systematized geodetic data allowed us to confirm adequacy of the developed geotechnical models.Studies carried out using geotechnical models made it possible to predict improvement of physical and mechanical characteristics of the subgrade to prevent further growth deformations of the bridge abutments.The method of reinforcement by injection is proposed.Injecting a solution under pressure leads to strengthening of weakened thawed soils and improving their physical and mechanical properties.This research theoretically substantiates and develops the geotechnical models of the reinforced pier footing of bridge abutments by injection of solidifying solutions.The models take into account the reinforcement parameters and elements for the case in question.The influence of reinforcement on the change in physical and mechanical properties of the soil mass is determined.展开更多
When the converter bus voltage of a voltage source converter-based high voltage direct current(VSC-HVDC)system drops below a certain predetermined threshold,the system enters low-voltage ride-through(LVRT)mode to avoi...When the converter bus voltage of a voltage source converter-based high voltage direct current(VSC-HVDC)system drops below a certain predetermined threshold,the system enters low-voltage ride-through(LVRT)mode to avoid overcurrent and potential equipment failure,during which it operates as a controlled current source.The influence mechanism of LVRT control strategies on short-circuit current and overall system stability remains not yet fully and systematically investigated.First,this paper provides an overview of several LVRT strategies for VSC-HVDC systems and examines their effects on short-circuit current contribution.Next,it analyzes in detail the mechanisms through which active and reactive currents injected during LVRT impact system frequency stability,voltage stability,and synchronization stability.To address these interrelated issues,an optimized and comprehensive LVRT strategy incorporating short-circuit current constraints is proposed.The approach determines the active current ratio based on system frequency stability requirements and dynamically adjusts the active current recovery rate via phase control of the VSC-HVDC bus.The remaining capacity is allocated to reactive current support,thereby enhancing voltage and synchronization stability while maintaining sufficient short-circuit current margin and system frequency stability.Finally,simulations conducted on the PSS/E platform,using actual grid data from a selected cross-section system,validate convincingly the effectiveness of the proposed parameter optimization strategy for VSC-HVDC low-voltage ride-through.展开更多
SiC/Al-based composite foams were prepared by a two-step foaming method.The influence of the SiC content and its distribution uniformity on the foaming stability,cell structure,and mechanical properties of the aluminu...SiC/Al-based composite foams were prepared by a two-step foaming method.The influence of the SiC content and its distribution uniformity on the foaming stability,cell structure,and mechanical properties of the aluminum foams was investigated.The macro/micro-features of the aluminum foams were characterized and analyzed.Results demonstrate that an appropriate increase in SiC content and the uniform distribution of SiC can improve the foaming stability,optimize the cell diameter and cell wall thickness,ameliorate the cell distribution,and enhance the hardness and compressive strength of the aluminum foams.However,either insufficient or excessive SiC leads to uneven distribution of SiC particles,which is unfavorable to foaming stability and good cell structure formation.With 6wt%SiC,both the foaming stability and cell structure of the aluminum foam reach the optimal state,resulting in the highest compressive strength and optimal energy absorption capacity.展开更多
The effects of the high pressure die casting(HPDC)processes on porosity,microstructure,and mechanical properties of heat-treatment-free aluminum silicon(Al-Si)alloys have long been a focal point in automotive die-cast...The effects of the high pressure die casting(HPDC)processes on porosity,microstructure,and mechanical properties of heat-treatment-free aluminum silicon(Al-Si)alloys have long been a focal point in automotive die-casting research.In this work,the combined effect of shot sleeve materials and slow shot speeds on porosity,microstructure and mechanical properties of a newly designed HPDC Al-Si alloy was investigated.Results show that employing a ceramic shot sleeve or increasing the slow shot speed significantly reduces both the average size and area fraction of externally solidified crystals(ESCs),as well as the average pore size and volume fraction.When the slow shot speed is increased from 0.05 m·s^(-1)to 0.1 m·s^(-1),the pore volume fraction decreases by 10.2%in steel-shot-sleeve samples,compared to a substantial 67.1%reduction in ceramic-shot-sleeve samples.At a slow shot speed of 0.1 m·s^(-1),castings produced with a ceramic shot sleeve exhibit superior mechanical properties:8.3%higher yield strength,17.4%greater tensile strength,and an 81.4%improvement in elongation,relative to those from a steel shot sleeve.These findings provide valuable insights for minimizing porosity and coarse ESCs in die castings,offering promising potential for broader industrial applications.展开更多
ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects....ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects.Cur-rently,with increasing uncertainties in the external environment,China facesmultple difficulties and challenges in attracting foreign investment.展开更多
基金supported by National Natural Science Foundation of China(U24B6008,U22B6008)State Grid Zhejiang Electric Power Co.,Ltd.Science,and Technology Project(B311DS240015).
文摘In the future power-electronics-dominated power systems,grid-forming(GFM)converters have been regarded as important devices to actively establish frequency and voltage,so as to provide essential grid support.However,due to their voltage source behavior and emulated swing dynamics,GFM converters may encounter low-frequency oscillations(LFOs)when connected to strong grids,which belongs to the self-stability problem of GFM converters.Moreover,GFM converters will also interact with grid-following(GFL)converters and thus impact the mid-frequency oscillations(MFOs)induced by phase-locked loops(PLLs).It has been preliminarily shown in the literature that GFM converters can help stabilize the PLL-induced MFOs,but currently,there is a lack of systematic design methods to coordinate the self-stability and stabilizing ability of GFM converters.This paper addresses this gap by revisiting the impedance model of a typical GFM converter and briefly analyze the oscillations caused by converters.Based on our analysis,we propose a frequency-partitioned synthesis design framework to enable dynamic virtual impedance(DVI)in GFM converters,aiming to enhance their self-stability and stabilizing ability simultaneously.Particularly,a self-stabilizing module is designed to ensure robust device-level damping,with control parameters auto-tuned using H∞methods.In parallel,a stabilizing module is introduced to stabilize GFL converters and enhance the system-level stability,which utilizes a perceive-and-optimize tuning strategy.Simulation results validate the effectiveness of the proposed synthesis DVI framework.
基金supported by the National Natural Science Foundation of China(No.52374121)the Henan Province Science and Technology Research and Development Joint Fund,China(No.235200810016)the National Key Research and Development Program,China(No.2023YFC2907203).
文摘Rapid industrialization in China has caused significant environmental challenges,particularly heavy metal pollution from mine tailings.Toxic heavy metals such as lead(Pb),cadmium(Cd),and mercury(Hg)are released during the processing of mining wastewater and leaching of mine tailings.Owing to their excellent physicochemical properties,cementitious materials are widely used for the solidification/stabilization of heavy metals,immobilizing heavy metals via two distinct mechanisms.Physically,their favorable characteristics,including high mechanical strength,low porosity,and durable matrix,create effective barriers.Chemically,the alkaline environment facilitates the precipitation of metal hydroxides/carbonates.Conversely,hydration products(calcium silicate hydrate gels and ettringite)contribute to immobilization through adsorption and physical encapsulation.This study systematically investigated the migration mechanisms of heavy metal contaminants in mine tailings;further,it elucidated the multifaceted immobilization pathways of cementitious materials,which involve synergistic adsorption,precipitation,and encapsulation by hydration products combined with homocrystalline substitution.A comprehensive analysis indicated that cementitious materials significantly reduced the mobility and bioavailability of heavy metals.Nonetheless,their long-term stability and potential environmental impact require further investigation.This study aims to provide theoretical support for environmental management and sustainable resource utilization,and to explore the broader application potential of cementitious technology for heavy metal stabilization,thereby establishing a theoretical foundation for future research on heavy metals in low-cement solidified/stabilized tailings.
基金financially supported by Jilin Provincial Natural Science Foundation (No.20220101164JC)。
文摘Understanding the factors triggering slope failure is essential to ensure the safety of buildings and transportation infrastructure on slopes. Specifically,the failure of stabilizing piles due to groundwater migration and freeze–thaw(FT) cycles is a significant factor causing slope failure. This study aims to investigate the transmedia seepage characteristics at slope–concrete stabilizing pile interface systems by using silty clay and concrete with varying microstructure characteristics under FT cycles. To this end, a self-developed indoor test device for transmedia water migration, combined with a macro-meso-micro multiscale testing approach, was used to analyze the laws and mechanisms of transmedia seepage at the interface systems. The effect of the medium's microstructure characteristics on the transmedia seepage behavior at the interface systems under FT cycles was also assessed. Results indicated that the transmedia water migration exhibited particularity due to the migration of soil particles and the low permeability characteristics of concrete. The water content in the media increased significantly within the range of 1/3–2/3 of the height from the interface for soil and within 5 mm from the interface for concrete.FT cycles promoted the increase and penetration of cracks within the medium, enhancing the permeability of the slope-concrete stabilizing pile interface systems.With the increase in FT cycles, the porosity inside the medium first decreased and then increased, and the porosity reached the minimum after 25 FT cycles and the maximum after 75 FT cycles, and the water content of the medium after water migration was positively correlated with the porosity. FT cycles also significantly influenced the temporal variation characteristics of soil moisture and the migration path of water in concrete. The study results could serve as a reference for related research on slope stability assessment.
基金the supports from the National Natural Science Foundation of China(Grant Nos.42177163 and 42307232)the China Postdoctoral Science Foundation of China(Grant No.2022M723347).
文摘The remediation of lead-contaminated dredged sediments(LDS)presents significant environmental challenges.This study investigates the solidification/stabilization(S/S)mechanisms of ordinary Portland cement(OPC)modified with nano-silica(NS)across a continuum from nanoscale interactions to macroscopic performance.For this,a series of macroscopic experiments was conducted to evaluate the mechanical performance and lead-encapsulation efficiency,including unconfined compressive strength(UCS)and toxicity characteristic leaching procedure(TCLP).Microstructural and phase transformations were characterized using X-ray diffraction,thermogravimetric analysis,and scanning electron microscope.Molecular dynamics simulations revealed the interactions between NS-modified cement,calcium silicate hydrates(C-S-H)gel,and Illite,focusing on interaction energies,atomic density distributions and structural changes.Macroscopic analyses demonstrated that increasing NS content from 0%to 8%improved Pb-immobilization rate from 88.7%to 97.6%and enhanced UCS from 764 kPa to 1358 kPa.These improvements were attributed to NS enhancing the microstructural integrity of C-S-H gel and filling pores in samples.Nanoscale simulations elucidated that Pb-stabilization occurs through coordination bonds with oxygen atoms in the C-S-H silicon chains and on Illite surfaces,complemented by the formation of stable Pb_(3)(CO)_(3)(OH)_(2)precipitates.Additionally,the simulations revealed that Ca^(2+)migration from hydration products to mineral surfaces generated substantial repulsive interaction energies,reducing Illite layer dispersion.However,the presence of Pb impeded further Ca^(2+)migration,leading to expansion of the C-S-H gel,which collectively degraded the mechanical properties of the material.Furthermore,wet-dry and freeze-thaw cycles showed that after 10 cycles,UCS and TCLP results still met the United States Environmental Protection Agency standards,confirming long-term durability.This study provides a theoretical foundation for resource utilization of the contaminated sediments and offers a perspective for design of the cement-based curing agents,particularly in addressing variations in pollutant concentrations and environmental conditions,advancing the application of responsive and controlled release curing agents.
基金financial support from the Key Research and Development Project in Shaanxi Province(2023-YBGY-446)the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(No.2022SX-TD003)+1 种基金the Natural Science Basic Research Program of Shaanxi(No.2024JC-YBQN-0108)the Key Laboratory of Interface Science and Engineering in Advanced Materials,Ministry of Education(KLISEAM202202)。
文摘Augmenting the working voltage is an effective way to maximize the energy density of Ni-rich layered Li[Ni_(0.8)Co_(0.1)Mn_(0.1)]O_(2)(NCM)to approach its theoretical capacity.However,NCM suffers from structural degradation in deep delithiation state,which is often accompanied by severe surface lattice oxygen loss and transition metal dissolution,leading to restricted cycle life.Herein,a facile and effective surfacestrengthening strategy is proposed,in which Mn(OH)_(2)nanoshells are uniformly grown on the NCM surface as a Li~+capturer and then converted to thin spinel Li_(4)Mn_(5)O_(12)layers during subsequent hightemperature sintering.The resultant Li_(4)Mn_(5)O_(12)layers can enhance cathode-electrolyte interface electrochemical stability with inhibited electrolyte corrosion and accelerated Li~+kinetics.The theoretical calculations confirms that the Mn-O bonds formed at the interfaces can effectively decrease the oxygen activity,thereby further inhibiting the lattice oxygen release and structural degradation caused by the irreversible phase transition.Consequently,the Li_(4)Mn_(5)O_(12)-coated NCM displays high capacity retention of 80.3%and 94.9%at 1 C and 5 C compared to the pristine NCM(52.5%and 10.1%)after 200 cycles and can operate stably at 2.7-4.6 V and 60℃.The spinel Li_(4)Mn_(5)O_(12)-coating demonstrates an effective route to enhance the structural/electrochemical stability of NCM for next-generation advanced lithium-ion batteries.
基金financially supported by the Scientific and Technological Plan Project of Guizhou Province ([2024]054)Additional support came from the Industry and Education Combination Innovation Platform of Intelligent Manufacturing and Graduate Joint Training Base at Guizhou University (2020-520000-83-01324061)the Guizhou Engineering Research Center for Smart Services (2203-520102-04-04-298868)。
文摘Aqueous sodium-ion batteries(ASIBs) offer significant advantages for energy storage on a large scale,attributed to their economical cost,secure operatio n,and eco-friend ly natu re.Among the leading cathode materials for ASIBs,Na_(3)V_(2)(PO_(4))_(3)(NVP) exhibits excellent structural stability and a high Na+diffusion coefficient,making it a promising option.However,the high solubility of vanadium-based materials in aqueous electrolytes engenders suboptimal cycling stability for Na_(3)V_(2)(PO_(4))_(3),constraining its application in ASIBs.Herein,the Cr-substituted Na_(3)V_(1.3)Cr_(0.7)(PO_(4))3@C(NV_(1.3)Cr_(0.7)P) cathode material was synthesized via a simple sol-gel method.It is found that Cr substitution reduces the cell parameters of NV_(1.3)Cr_(0.7)P,effectively reinforcing the crystal structure.Furthermore,NV_(1.3)Cr_(0.7)P alters the Na^(+)insertion/extraction mechanism,transforming the typical two-phase reaction between Na_(1)V_(2)(PO_(4))_(3)and Na_(3)V_(2)(PO_(4))3into continuous solid-solution reactions with stable intermediates.The Cr substitution diminishes the sodium-ion diffusion energy barrier in NV_(1.3)Cr_(0.7)P,leading to smoother Na+insertion and extraction processes.Consequently,NV_(1.3)Cr_(0.7)P exhibits impressive cycling stability,retaining 74.8% of its capacity after 5,000 cycles at a current density of 5 A g^(-1),along with an outstanding rate performance of 79,2% at 10 A g^(-1).This work elucidates the stable Na^(+)insertion/extraction processes in Cr-substituted NV_(1.3)Cr_(0.7)P,offering insights into the application of vanadium-based materials in aqueous sodium-ion batteries.
基金supported by the National Science Foundation of China (Grant No.22179094)the Science and Technology Program of Cangzhou (Grant No.222103001)the research funding of Cangzhou Institute of Tiangong University (Grant No.TGCYY-Z0202)。
文摘P2-type layered oxides are highly promising cathode candidates for sodium-ion batteries(SIBs)owing to their substantial theoretical capacity.Nevertheless,structural degradation caused by transition metal dissolution and irreversible phase transitions at high voltage severely compromises cycling stability.To address this limitation,we propose a Li/Ti co-doping strategy to design a Na_(0.67)Li_(0.06)Ni_(0.27)Mn_(0.5)7Ti_(0.1)O_(2)(NLMT) cathode for SIBs.In-situ X-ray diffraction(XRD) confirms that this deliberate strategy eliminates the adverse phase transition at high voltage and sustains the unitary P2phase throughout cycling.In addition,strengthened transition metal-oxygen(TM-O) bonding via electronic modulation suppresses transition metal dissolution and reinforces the layered oxide framework,contributing to exceptional electrochemical performance.Consequently,the NLMT cathode exhibits an outstanding capacity of 92.8 mA h g^(-1) within 2.5-4.3 V at 5 C(865 mA g^(-1)),with 87 % capacity retention over 200 cycles.Configured into a full cell,which achieves a competitive capacity of 107.7 mA h g^(-1) at0.1 C and retains 86.4 % capacity over 100 cycles at 0.5 C.This study validates co-doping as a potent strategy for significantly improving the long-term cyclability of layered oxide cathodes in SIBs.
基金Supported by National Natural Science Foundation of China(12201118)Guangdong Basic and Applied Basic Research Foundation(2023A1515010706)。
文摘We investigate a class of non-integrable two-particle Calogero-Moser systems modulated by a power-law external potential.The local well-posedness of the Cauchy problem is established under the strict initial separation condition for the particles.For suitably prepared initial configurations,local solutions can be extended globally via energy conservation;conversely,negative energy conditions induce(in)finite-time blowup.The linear(in)stability of stationary solutions is analyzed,with their energy serving as a threshold.Numerical investigations employ a fourth-order Runge-Kutta scheme with adaptive step-size control.Simulations demonstrate that the trajectories either converge to steady states or exhibit blowup,depending on the power exponent α and initial conditions.Increasingαaccelerates the convergence rate and dampens oscillatory dynamics,promoting a transition from periodic behavior to static equilibrium.
基金financially supported by the National Natural Science Foundation of China(NSFC)(22179056,22172018)the Liaoning Revitalization Talents Program(XLYC2002097,1807210)+2 种基金the Key Projects of Liaoning Provincial Education Department(JYTZD2023001)the Fundamental Research Funds for the Central Universities(DUT23LAB611)Yingkou Talents Program。
文摘Selective electrocatalytic semi-hydrogenation(ECSH)of alkynes in water using Cu catalysts is highly relevant for the production of value-added chemicals.However,achieving high olefin selectivity still poses extreme challenges due to the susceptibility of the copper cathode in a reduction environment.Herein,a small molecule modulation electrodeposition strategy is introduced that regulates the structure of Cubased materials through modification with citric acid(CA)ligands,aiming for highly active and selective ECSH.The as-prepared EDCu-CA electrode achieves more than 97%alkyne conversion and 99%olefin selectivity.In-situ Raman and Auger electron spectroscopy(AES)data provide evidence that active Cu^(+)sites can stably exist in the EDCu-CA during the catalytic process.Density functional theory(DFT)calculations indicate that the modulation by CA contributes to maintaining Cu in a positive valence state,and Cu^(+)can inhibit the over-hydrogenation of olefins.Moreover,by utilizing a large-area electrode for longterm electrolysis,g-level conversion and a 92%separation yield of olefin can be achieved,demonstrating a viable application prospect.This study offers a promising route for designing Cu-based catalysts for the highly selective electrocata lytic conversion of organic substrates to value-added chemicals in water.
基金Supported by the Natural Science Foundation of Shanghai(23ZR1401700)National Natural Science Foundation of China(12471157)。
文摘In ecological environments,the survival environment of species is often inhomogeneous,and the reproductive process is affected by time delay.System with nonlocal effects and delay can more accurately simulate changes in population density.In this paper,we consider a reaction-diffusion-advection model with nonlocal delay and Dirichlet boundary conditions.First of all,we investigate the well-posedness of solution of model.Then,the existence of positive steady state is proofed by implicit function theorem.Based on a priori estimate for the eigenvalue,we prove the stability of the positive steady state and conclude the associated distribution of Hopf bifurcation.Our research indicates that the combined effects of nonlocal and time delays have a certain impact on the dynamics of the model.
文摘Neutral oxygen evolution reaction(OER)is a crucial half-reaction for electrocatalytic chemical production under mild condition,but with limited development due to low activity and poor stability.Herein,a tungsten-doped cobalt molybdate(WDCMO)catalyst was synthesized for efficient and durable OER under neutral electrolyte.It is demonstrated that catalyst reconstruction is suppressed by W doping,which stabilizes the Co-O-Mo point-to-point connection in CoMoO_(4) architecture and stimulates to a lower valence state of active sites over the surface phase.Thereby,the surface structure maintains to avoid compound dissolution caused by over-oxidation during OER.Meanwhile,the WDCMO catalyst promotes charge transfer and optimizes*OH intermediate adsorption,which improves reaction kinetics and intrinsic activity.Consequently,the WDCMO electrode exhibits an overpotential of 302 mV at 10 mA cm^(-2) in neutral electrolyte with an improvement of 182 mV compared with CoMoO4 electrode.Furthermore,W doping significantly improves the electrode stability from 50 h to more than 320 h,with a suppressive potential attenuation from 2.82 to 0.29 mV h^(-1).This work will shed new light on designing rational electrocatalysts for neutral OER.
文摘Quantitative real-time PCR(qPCR)is widely used for gene expression analysis,but its accuracy critically depends on stable internal reference genes for normalization.In marine invertebrates,especially non-model taxa such as cephalopods,systematic evaluation of reference genes is limited,leading to potential bias.The cuttlefish Sepiella japonica is ecologically and economically important in China,yet previous molecular studies have often relied on single unvalidated reference genes,which may compromise data reliability.This study aimed to systematically evaluate the stability of five commonly used reference genes(18S,ef-1α,ef-1γ,gapdh,andβ-actin)across multiple tissues and sexes of S.japonica,and to identify the most suitable reference genes and optimal number for qPCR normalization.Fifteen to sixteen tissue types were collected from ten healthy adults(five males and five females).Total RNA was extracted,reverse-transcribed,and analyzed by qPCR.Gene stability was assessed using four algorithms(geNorm,NormFinder,BestKeeper,andΔCt)integrated with RefFinder,and the optimal gene number was determined using geNorm pairwise variation(V_(n/n+1)<0.15).Four transcriptome-derived genes(creld2,cd109,acy1,and miox)were used for validation.The C_(t)values of the five genes ranged from 15.47 to 20.83.β-actin and gapdh showed pronounced variability in expression stability among tissues and sexes,indicating their limited suitability for normalization.18S exhibited the highest expression(mean C_(t):15.47-16.29)and lowest variability but displayed sex-biased expression,whereas ef-1αand ef-1γremained consistently stable across most tissues in both sexes,with ef-1αbeing the most robust and showing no sex-related bias.Although specific rankings varied among tissues and sexes,the comprehensive results indicated that ef-1αand ef-1γpossessed the highest overall stability,followed by 18S,whileβ-actin and gapdh were the least stable.The final comprehensive rankings were ef-1γ>ef-1α>18S>gapdh>β-actin(male)and ef-1α>ef-1γ>18S>gapdh>β-actin(female).geNorm analysis(V2/3<0.15)indicated that two genes,mainly ef-1αand ef-1γ,were generally sufficient for reliable normalization in most tissues.Validation confirmed that normalization using the stable ef-1αand ef-1γaccurately reflected the expression differences among tissues,whereasβ-actin and gapdh can bias or confound statistical analyses.ef-1αand ef-1γare identified as the most reliable reference gene combination for qPCR analysis in S.japonica,while 18S can serve as an auxiliary gene for within-sex comparisons.The use ofβ-actin or gapdh alone is not recommended.This study establishes a systematic framework for selecting reliable reference genes in S.japonica,thereby facilitating robust qPCR normalization and providing a foundation for future gene expression research in S.japonica and other cephalopods.
基金Ho Chi Minh City University of Technology(HCMUT),VNU-HCM for supporting this study.
文摘Vitamin C,a potent antioxidant with broad therapeutic applications,is limited by rapid degradation under environmental stressors,which compromises its stability and bioactivity.This study addresses these limitations by formulating a double nano-emulsion(W/O/W)system incorporating macadamia oil and tea tree oil,using homogenization and phase inversion temperature(PIT)techniques.Comprehensive physicochemical charac-terization,including droplet size,polydispersity index(PDI),zeta potential,turbidity,Fourier transform infrared spectroscopy(FTIR),and SEM,was conducted alongside stability assessments under varying pH,temperature,and storage conditions.The optimized nano-emulsions exhibited nanoscale droplet sizes(10-40 nm),low PDI values(indicating high uniformity),and robust stability.Interestingly,the formulation with 2%W/O loading,with a particle size of 11.57 nm and a PDI of 0.04,demonstrated an antioxidant capacity of 4622.62μg ascorbic acid equivalents(AA)/g,which was significantly higher(p<0.05)compared to both natural oils(macadamia oil:20.91μg AA/g,tea tree oil:16.86μg AA/g)and a 10%Vitamin C aqueous solution(592.94μg AA/g).FTIR analysis confirmed the molecular integrity of Vitamin C and its successful encapsulation with macadamia and tea tree oils,while SEM images revealed uniformly spherical and well-dispersed droplets.Moreover,the formulation retained its structural integrity and antioxidant functionality under diverse pH and thermal conditions.These findings underscore the potential of double nano-emulsion systems to overcome the stability challenges of Vitamin C,offering a promising approach to enhance its bioavailability and therapeutic performance in phar-maceutical and cosmetic applications.
基金National Natural Science Foundation of China(51774179)Natural Science Foundation of Liaoning Province(20180550546)+2 种基金Joint Fund of State Key Laboratory of Metal Material for Marine Equipment and Application(HGSKL-USTLN(2021)03)High-Level Talent Fund of USTL(6003000377,6003000294)supported by Liaoning Provincial Department of Education(LJ212410146037)。
文摘The effect of element Ti on the microstructures and mechanical properties of as-cast and annealed NbTaMoWTi,(x=0,1,1.5,2)refractory high-entropy alloys(RHEAs)was investigated.Results show that after Ti addition,the as-cast alloys maintain their original single body-centered cubic(bcc)structure.As for the mechanical properties,compared with those without Ti addition,the strength and ductility of NbTaMoWTi,alloys increase by 93%and 215%,respectively.Furthermore,the NbTaMoWTi alloys exhibit outstanding thermal stability.After annealing at 1400 C,they still maintain the single bcc structure,and their mechanical properties are even slightly improved.However,annealing leads to a significant deterioration in the mechanical properties of high-Ti-content alloys(NbTaMoWTil and NbTaMoWTi2),owing to the formation of Ti-rich acicular phases.
基金supported by National Natural Science Foundation of China(No.22309029)Guangdong Basic and Applied Basic Research Foundation(No.2024A1515140011)+1 种基金Dongguan Social Development Technology Foundation(No.20231800907933)Collaborative Innovation Center of Marine Science and Technology of Hainan University(No.XTCX2022HYC14)。
文摘The uncontrollable dendrite growth of lithium anode and active material dissolution of transition metal oxides cathodes severely hinder the development of lithium metal batteries.An effective strategy to address these issues is optimizing the separator to regulate ion transport and trap the lost active component.Herein,a crosslinked gelatin nonwoven(CGN)separator is elaborately fabricated through electrospinning and in-situ vapor phase crosslinking process to manipulate the dual electrode interface.Benefitting from the characteristic composition of gelatin,and porous structure of electrospun nonwoven,the CGN separator exhibits excellent interface wettability and low interface resistance,featuring a high Li^(+)transference number of 0.70 and high ionic conductivity of 3.75 m S/cm.As expected,the symmetrical Li/Li cells present stable cycling behavior for 1900 h at 0.5 mA/cm^(2)with low overpotential of 20 mV.The optimized LiMn_(2)O_(4)/Li cells deliver high reversible capacity of 103 m Ah/g as well as high capacityretention ratio of 83.7%after 100 cycles at 0.3 C,which can be effectively attributed to the strong interaction between CGN separator and Mn ions to prevent the loss of active Mn component.This study indicates the application potential of protein-based electrospun membrane for high-performance lithium metal batteries.
文摘Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in temperature and their subgrade condition within the active zone due to the structures'technogenic impact.Design solutions for the fifty-year-old structures fail to ensure in all cases their reliable operation at the present time.The greatest danger to the reliable operation of railway lines in cold regions is uneven deformations of bridges,which are barrier places.Therefore,the solution to this problem is urgent especially due to the necessity of increase carrying capacity.The purpose of this study is to increase reliability of bridge operation in cold regions through strengthening the subgrade by reinforcement with injection of solidifying solutions.The problem of uneven deformations due to permafrost degradation is considered using the example of a railway bridge located in the northern line of the Krasnoyarsk railway.Deformations of the bridge abutments began immediately after the construction was completed and the bridge was open for traffic-since 1977.Permafrost degradation was developing more actively straight under the abutments due to higher thermal conductivity of the piles concrete.Notably,thawing intensity of frozen soils under the bridge abutments is uneven due to its orientation to the cardinal points.The analysis of archive materials and results of the geodetic survey made it possible to systematize the features of augmenting deformations of each abutment over time.The engineering-geological survey with drilling wells near the abutments ensured determination of soil characteristics,both in the frozen and thawed states.Thermometric wells were arranged to measure temperatures.The analysis and systematization of the data obtained allowed us to develop geotechnical models for each abutment of the bridge.The peculiarity of these models is allowance for changes in the strength and deformation characteristics of the soil calculated layers depending on changes in temperature and the soil condition.Thus,different calculated geological elements with the corresponding strength and deformation characteristics were identified in the soil layers of the same origin.The analysis of the systematized geodetic data allowed us to confirm adequacy of the developed geotechnical models.Studies carried out using geotechnical models made it possible to predict improvement of physical and mechanical characteristics of the subgrade to prevent further growth deformations of the bridge abutments.The method of reinforcement by injection is proposed.Injecting a solution under pressure leads to strengthening of weakened thawed soils and improving their physical and mechanical properties.This research theoretically substantiates and develops the geotechnical models of the reinforced pier footing of bridge abutments by injection of solidifying solutions.The models take into account the reinforcement parameters and elements for the case in question.The influence of reinforcement on the change in physical and mechanical properties of the soil mass is determined.
基金funded by State Grid Corporation of China,grant number DQ30DK24001L。
文摘When the converter bus voltage of a voltage source converter-based high voltage direct current(VSC-HVDC)system drops below a certain predetermined threshold,the system enters low-voltage ride-through(LVRT)mode to avoid overcurrent and potential equipment failure,during which it operates as a controlled current source.The influence mechanism of LVRT control strategies on short-circuit current and overall system stability remains not yet fully and systematically investigated.First,this paper provides an overview of several LVRT strategies for VSC-HVDC systems and examines their effects on short-circuit current contribution.Next,it analyzes in detail the mechanisms through which active and reactive currents injected during LVRT impact system frequency stability,voltage stability,and synchronization stability.To address these interrelated issues,an optimized and comprehensive LVRT strategy incorporating short-circuit current constraints is proposed.The approach determines the active current ratio based on system frequency stability requirements and dynamically adjusts the active current recovery rate via phase control of the VSC-HVDC bus.The remaining capacity is allocated to reactive current support,thereby enhancing voltage and synchronization stability while maintaining sufficient short-circuit current margin and system frequency stability.Finally,simulations conducted on the PSS/E platform,using actual grid data from a selected cross-section system,validate convincingly the effectiveness of the proposed parameter optimization strategy for VSC-HVDC low-voltage ride-through.
基金Doctoral Startup Fund(20192066,20212028)Laijin Excellent Doctoral Fund(20202021)+1 种基金Scientific and Technological Innovation of Colleges and Universities in Shanxi Province(2020L0342)Fundamental Research Program of Shanxi Province(202303021222178)。
文摘SiC/Al-based composite foams were prepared by a two-step foaming method.The influence of the SiC content and its distribution uniformity on the foaming stability,cell structure,and mechanical properties of the aluminum foams was investigated.The macro/micro-features of the aluminum foams were characterized and analyzed.Results demonstrate that an appropriate increase in SiC content and the uniform distribution of SiC can improve the foaming stability,optimize the cell diameter and cell wall thickness,ameliorate the cell distribution,and enhance the hardness and compressive strength of the aluminum foams.However,either insufficient or excessive SiC leads to uneven distribution of SiC particles,which is unfavorable to foaming stability and good cell structure formation.With 6wt%SiC,both the foaming stability and cell structure of the aluminum foam reach the optimal state,resulting in the highest compressive strength and optimal energy absorption capacity.
基金the National Key Research and Development Program of China(Grant No.2022YFB3404201)the National Natural Science Foundation of China(Grant Nos.52175335,52405342)+1 种基金the Natural Science Foundation Joint Foundation of Liaoning province(Grant No.2023-B SB A-108)the Fundamental Research Funds for the Central Universities(Grant No.N2402005)。
文摘The effects of the high pressure die casting(HPDC)processes on porosity,microstructure,and mechanical properties of heat-treatment-free aluminum silicon(Al-Si)alloys have long been a focal point in automotive die-casting research.In this work,the combined effect of shot sleeve materials and slow shot speeds on porosity,microstructure and mechanical properties of a newly designed HPDC Al-Si alloy was investigated.Results show that employing a ceramic shot sleeve or increasing the slow shot speed significantly reduces both the average size and area fraction of externally solidified crystals(ESCs),as well as the average pore size and volume fraction.When the slow shot speed is increased from 0.05 m·s^(-1)to 0.1 m·s^(-1),the pore volume fraction decreases by 10.2%in steel-shot-sleeve samples,compared to a substantial 67.1%reduction in ceramic-shot-sleeve samples.At a slow shot speed of 0.1 m·s^(-1),castings produced with a ceramic shot sleeve exhibit superior mechanical properties:8.3%higher yield strength,17.4%greater tensile strength,and an 81.4%improvement in elongation,relative to those from a steel shot sleeve.These findings provide valuable insights for minimizing porosity and coarse ESCs in die castings,offering promising potential for broader industrial applications.
文摘ln order to improve the level of investment promotion and redouble effortsto enhance services,on February l9th,the 2025 Action Plan for StabilizingForeign lnvestment was released,proposing 20 measures in four aspects.Cur-rently,with increasing uncertainties in the external environment,China facesmultple difficulties and challenges in attracting foreign investment.
