Arteriovenous fistula(AVF)calcification is a common complication in hemodialysis patients that leads to AVF dysfunction and decreases the AVF survival,but the mechanisms of AVF calcification,especially the role of hem...Arteriovenous fistula(AVF)calcification is a common complication in hemodialysis patients that leads to AVF dysfunction and decreases the AVF survival,but the mechanisms of AVF calcification,especially the role of hemodynamic changes in AVF calcification have not been fully investigated.In this study,a computational fluid dynamics(CFD)model was carried out based on AVF,at the distal anastomosis of the cephalic vein and radial artery,generated from a patient-specific computed tomography(CT)angiography and Doppler ultrasound image.Hemodynamic factors were considered to explore the mechanisms responsible for the initiation and progression of AVF calcification.Five stages in one cardiac cycle were chosen to be studied for the velocity field,pressure,time-averaged wall shear stress(TAWSS),and oscillatory shear index(OSI).Blood pressure was higher in the arteriovenous anastomosis,and variations of great amplitude of pressure were examined during the cardiac cycle.Blood pressure,transient shear stress,TAWSS,and OSI were higher in the arteriovenous anastomosis and at the bottom of expanded outflow vein,and these sites were highly consistent with the calcified areas shown on CT angiography.On the contrary,no calcification was found in sites where streamline was stable,blood pressure did not change dramatically,as well as TAWSS and OSI were lower.It was shown that AVF calcification was correlated with hemodynamic changes,which may contribute to further understanding the mechanisms of AVF calcification and providing scientific evidence to inform the optimization of surgical strategies and the development of personalized interventional measures in clinical contexts.展开更多
Hydraulic stimulation technology is widely employed to enhance the permeability of geothermal reservoirs.Nevertheless,accurately predicting hydraulic fracture propagation in complex geological conditions remains chall...Hydraulic stimulation technology is widely employed to enhance the permeability of geothermal reservoirs.Nevertheless,accurately predicting hydraulic fracture propagation in complex geological conditions remains challenging,thereby hindering the effective utilization of existing natural fractures.In this study,a phase field model was developed utilizing the finite element method to examine the influence of fluid presence,stress conditions,and natural fractures on the initiation and propagation of hydraulic fractures.The model employs Biot's poroelasticity theory to establish the coupling between the displacement field and the fluid field,while the phase field theory is applied to simulate fracture behavior.The results show that whenσ_(x0)/σ_(y0)<3 or qf<20 kg/(m^(3)·s),the presence of natural fractures can alter the original propagation direction of hydraulic fractures.Conversely,in the absence of these conditions,the propagation path of natural fractures is predominantly influenced by the initial stress field.Furthermore,based on the analysis of breakdown pressure and damage area,the optimal intersection angle between natural fractures and hydraulic fractures is determined to range from 45°to 60°.Finally,once a dominant channel forms,initiating and propagating hydraulic fractures in other directions becomes increasingly difficult,even in highly fractured areas.This method tackles the challenges of initiating and propagating hydraulic fractures in complex geological conditions,providing a theoretical basis for optimizing Enhanced Geothermal System(EGS)projects.展开更多
The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)sof...The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)software Fidesys.It briefly highlights the issues of comparing limit equilibrium methods using the VNIMI(Research Institute of Geomechanics and Mine Surveying-Intersectoral Scientific Center"VNIMI")methodology and a specialized software product with numerical methods.The main focus of this study is to compare the results of the stability analysis in the volumetric model of the open pit-dump system using limit equilibrium and finite element methods in the CAE software Fidesys.It was found that,when modeling the combined operation of an open pit-dump system in complex terrain,both methods should be used,as each has its own advantages.The finite element method,for instance,has certain features that are not present in the calculations using the limit equilibrium approach.As a key scientific contribution,this paper introduces an automation program for calculating the stability of open-pit walls using the limit equilibrium method in CAE Fidesys,which was not previously integrated in the original software.The calculations performed with the use of this newly developed module were compared to those obtained from other widely used software solutions available on the market.The findings demonstrate a remarkable level of convergence in the calculation results for all relevant parameters,including the safety factor,localization,instability type,and deformation.The proposed approach i mproves the accuracy of calculati ons and ensures consistency between the higher stress design zones and the actual deformation and fracture patterns.It also enhances the ability to predict the behavior of rock mass when calculating stability parameters for facilities,both during operation and desi gn.展开更多
The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in ...The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.展开更多
Degradation of materials is one of the most critical aging mechanisms affecting the performance of lithium batteries.Among the various approaches to investigate battery aging,phase-field modelling(PFM)has emerged as a...Degradation of materials is one of the most critical aging mechanisms affecting the performance of lithium batteries.Among the various approaches to investigate battery aging,phase-field modelling(PFM)has emerged as a widely used numerical method for simulating the evolution of the phase interface as a function of space and time during material phase transition process.Moreover,PFM coupled with multi-physics analyses is particularly well-suited for investigating the mesoscale microstructural evolution of materials,providing quantitative understandings of aging and failure mechanisms in lithium batteries.In this paper,we comprehensively overview the state-of-art applications of PFM in the research of degradation and failure processes in lithium batteries,particularly focusing on the theoretical framework and development of the PFMs for lithium deposition/dissolution,phase separation,and crack propagation.Furthermore,we summarize the existing challenges and prospect some future developments in PFMs,aiming to offer new insights into the advancement of PFM and ultimately enhance the development of lithium batteries.展开更多
The properties of electrolytes are critical for fast-charging and stable-cycling applications in lithium metal batteries(LMBs).However,the slow kinetics of Li^(+)transport and desolvation in commercial carbonate elect...The properties of electrolytes are critical for fast-charging and stable-cycling applications in lithium metal batteries(LMBs).However,the slow kinetics of Li^(+)transport and desolvation in commercial carbonate electrolytes,cou pled with the formation of unstable solid electrolyte interphases(SEI),exacerbate the degradation of LMB performance at high current densities.Herein,we propose a versatile electrolyte design strategy that incorporates cyclohexyl methyl ether(CME)as a co-solvent to reshape the Li^(+)solvation environment by the steric-hindrance effect of bulky molecules and their competitive coordination with other solvent molecules.Simulation calculations and spectral analysis demonstrate that the addition of CME molecules reduces the involvement of other solvent molecules in the Li solvation sheath and promotes the formation of Li^(+)-PF_(6)^(-)coordination,thereby accelerating Li^(+)transport kinetics.Additionally,this electrolyte composition improves Li^(+)desolvation kinetics and fosters the formation of inorganic-rich SEI,ensuring cycle stability under fast charging.Consequently,the Li‖LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)battery with the modified electrolyte retains 82% of its initial capacity after 463 cycles at 1 C.Even under the extreme fast-charging condition of 5 C,the battery can maintain 80% capacity retention after 173 cycles.This work provides a promising approach for the development of highperformance LMBs by modulating solvation environment of electrolytes.展开更多
Lithium(Li)deposition and nucleation at solid electrolyte interphase(SEI)is the main origin for the capacity decay in Li metal batteries(LMBs).SEI conversion with enhanced electrochemical and mechanical properties is ...Lithium(Li)deposition and nucleation at solid electrolyte interphase(SEI)is the main origin for the capacity decay in Li metal batteries(LMBs).SEI conversion with enhanced electrochemical and mechanical properties is an effective approach to achieve uniform nucleation of Li^(+)and stabilize the lithium metal anode.However,complex interfacial reaction mechanisms and interface compatibility issues hinder the development of SEI conversion strategies for stabilizing lithium metal anodes.Herein,we presented the release of I_(3)^(-)in–NH_(2)-modified metal–organic frameworks for a Li metal surface SEI phase conversion strategy.The–NH_(2)group in MOF pores induced the formation of I_(3)^(-)from I_(2),which was further spontaneously reacted with inactive Li_(2)O transforming into high-performance LiI and LiIO_(3)interphase.Furthermore,theoretical calculation provided deeply insight into the unique reconstructed interfacial formation and electrochemical mechanism of rich LiI and LiIO_(3)SEI.As a result,the Li^(+)deposition and nucleation were improved,facilitating the transport kinetics of Li^(+)and inhibiting the growth of lithium dendrites.The assembled solid-state Li||LiFePO_(4)full cells exhibited superior long-term stability of 800 cycles and high Coulombic efficiency(>99%),Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)pouch cell also displayed superior practical performance over 200 cycles at 2 C,high loading of 5 mg cm^(-2)and safety performance.This innovative SEI design strategy promotes the development of high-performance solid-state Li metal batteries.展开更多
Tribocorrosion readily removes the protective corrosion product,creates new reactive corrosion sites and thus accelerates material loss in metallic materials.This is evidenced by a pronounced or gradual decline in ope...Tribocorrosion readily removes the protective corrosion product,creates new reactive corrosion sites and thus accelerates material loss in metallic materials.This is evidenced by a pronounced or gradual decline in open circuit potential(OCP)during tribocorrosion assessments.Here we report that grain refinement can not only enhance wear resistance in dry conditions,but also induce an anomalously stable OCP variation and fortify tribocorrosion resistance in ultrahigh-purity magnesium during tribocorrosion.The tribocorrosion tests revealed that the fine-grained Mg(FG-Mg)sample exhibited a wear rate(4.56×10^(−4) mm^(3)/(N m))approximately half that of the coarse-grained Mg(CG-Mg)sample(7.87×10^(−4) mm^(3)/(N m)).CG-Mg showed a gradual OCP decrease,associated with a thin,unprotective tribocorrosion layer,even thinner than that resulting from dry sliding.Conversely,FG-Mg exhibited stable OCP evolution and quasi-linear tribocorrosion kinetics over time,attributed to a thick,protective tribocorrosion layer.Transmission electron microscopy data suggest that high-diffusivity pathways for oxygen along grain boundaries at the early tribocorrosion stages facilitate the formation of a continuous,protective MgO layer and an adjacent oxidized layer with a depth-dependent oxygen content gradient,enhancing tribocorrosion resistance in FG-Mg.Our findings offer valuable insights for strategically tailoring tribocorrosion resistance by modulating the OCP variation of highly active metals and alloys.展开更多
Heterointerfaces have been pivotal in unveiling extraordinary interfacial properties and enabling multifunctional material platforms.Despite extensive research on all-oxide interfaces,heterointerfaces between differen...Heterointerfaces have been pivotal in unveiling extraordinary interfacial properties and enabling multifunctional material platforms.Despite extensive research on all-oxide interfaces,heterointerfaces between different material classes,such as oxides and nitrides,remain underexplored.Here we present the fabrication of atomically sharp heterointerfaces between antiperovskite Ni_(3)InN and perovskite SrVO_(3).Leveraging layer-resolved scanning transmission electron microscopy and electron energy loss spectroscopy,we identified pronounced charge transfer across the well-ordered interface.First-principles calculations confirmed our experimental observations and further predicted an emergent magnetic moment within the Ni_(3)InN layer due to the charge transfer.These findings pave the way for novel electronic and spintronic applications by enabling tunable interfacial properties in nitride/oxide systems.展开更多
The commercialization of polymer electrolyte membrane water splitting technology significantly depends on the oxygen/hydrogen evolution reaction(OER/HER)electrocatalysts;customarily catalyzed by platinum(Pt)and ruthen...The commercialization of polymer electrolyte membrane water splitting technology significantly depends on the oxygen/hydrogen evolution reaction(OER/HER)electrocatalysts;customarily catalyzed by platinum(Pt)and ruthenium/iridium oxides(RuO_(2)/IrO_(2)).In this work,we have devised a novel strategy to improve the catalytic activities towards OER and HER catalysis via the decoration of RuO_(2)with Pt.Pt dopants in ruthenium oxides(Pt-RuO_(2))create more oxygen vacancies inducing a weaker interaction between active site and oxygen reaction intermediates,evidenced by downshifted d band center and increment in e_(g)orbital filling of Ru atom;thereby,the acidic OER performance of Pt-RuO_(2)is enhanced by 3.5-fold than commercial RuO_(2)by mean of turnover frequency at 1.6 V vs.RHE.Moreover,Pt-RuO_(2)exhibits a similar HER performance to commercial Pt/C.The potential for overall water splitting is decreased by 0.18 V at100 mA/cm^(2);besides,an excellent stability is also recorded after the incorporation of Pt dopants.TheΔ_(ε_(d-p))value of Pt-RuO_(2)was 1.76 e V,which is lower than the counterpart of RuO_(2),suggesting easy electron transition between d and p orbitals,suppressing the over-oxidation of RuO_(2);thereby,a higher stability is achieved for Pt-RuO_(2).The invitation of Pt dopants to boost catalytic activity and stability has also been extended to IrO_(2).展开更多
High-energy continuous wave(CW)lasers are mostly used in laser damage applications,but efficient laser ablation of transparent materials is challenging due to low optical absorption.Considering the potential of femtos...High-energy continuous wave(CW)lasers are mostly used in laser damage applications,but efficient laser ablation of transparent materials is challenging due to low optical absorption.Considering the potential of femtosecond(fs)laser-induced air filament for high-peak laser transmission over long distances,femtosecond(fs)laser-induced air filaments are combined with a millisecond(ms)laser to form an fs-ms CPL,enhancing the efficiency of sapphire ablation through synchronized spatial-temporal focusing.Experimental results show that ablation efficiency increases with the ms peak power and duty ratio.Excessive thermal stress leads to fragmentation of the sapphire when the ms duty ratio is over 30%at the peak power of 800 W,or when the peak power is over 500 W at a duty ratio of 100%.Also,the mechanism of high-efficiency damage is revealed through in-situ high-speed imaging.According to it,the ablation process went through 4 stages within 1.5 ms:defect-creating,melting and ablation,spattering,and fragmentation.Finally,the equivalent ablation efficiency of the fs-ms CPL is as high as 1.73×10^(7)μm^(3)/J,about 28 times higher compared to the fs laser only.The CPL damage method explored in this paper can provide theoretical guidance for efficient laser damage of transparent materials.展开更多
Photothermal catalysis is a promising technology primarily utilized the solar energy to produce photogenerated e^(-)/h^(+) pairs together with the production of heat energy.However,the inefficient separation of charge...Photothermal catalysis is a promising technology primarily utilized the solar energy to produce photogenerated e^(-)/h^(+) pairs together with the production of heat energy.However,the inefficient separation of charge carriers and inadequate response to near-infrared(NIR)light usually leads to the unsatisfactory photocatalytic efficiency,hindering their application potentials.In this work,a significantly enhanced photothermal catalytic hydrogen evolution reaction over the lead-free perovskite Cs_(3)Bi_(2)Br_(9)/FeS_(2)(CBB/FS)heterostructure is simultaneously verified,where the CBB/FS Z-scheme heterojunctions display the strong stability and superb photothermal catalytic activity.Under the simulated solar irradiation(AM 1.5G),the optimized CBB/FS-5 achieves a photocatalytic hydrogen evolution rate of 31.5 mmol g^(-1)h^(-1),which is 112.6 and 77.1 times higher than that of FS and CBB,respectively,together with an apparent quantum yield of 29.5%at 420 nm.This significantly improved photocatalytic H_(2)evolution can be mainly attributed to the Z-scheme charge transfer and photothermal-assisted synergistically enhanced photocatalytic H_(2)production,and the potential mechanism of the enhanced photocatalytic H_(2)evolution is also proposed by photoelectrochemical characterizations,in situ XPS,EPR spectra,and the DFT calculations.This work provides new insights to the design of high-efficient photothermal catalysts,leading to the sustainable and efficient solutions towards the energy and environmental challenges.展开更多
Ice shelves are important passageways for ice sheets flowing into the ocean.Through iceberg calving and basal melting,ice shelves exert considerable influence on the mass balance of the Antarctic Ice Sheet and glacier...Ice shelves are important passageways for ice sheets flowing into the ocean.Through iceberg calving and basal melting,ice shelves exert considerable influence on the mass balance of the Antarctic Ice Sheet and glacier stability.The Ross Ice Shelf(RIS),the largest body of floating ice on Earth,plays an essential role in any changes in the mass balance of the Antarctic Ice Sheet.The long-term elevation change trend of RIS has been calculated with multiple satellite altimetry in previous studies.However,the seasonal variations were less revealed.Based on crossover analysis and indirect observation adjustments,this study proposed a new method for constructing seasonal records for surface elevation changes in the RIS using ICESat laser altimetry data from 2003 to 2009.The results showed that surface elevation changes exhibited seasonal variations with fluctuations over 20 cm,and the seasonal change characteristics were closely related to the temperature.Interannual variations in RIS surface elevation decreased from 2003 to2009 at a rate of 2 cm/yr.From March 2003 to April 2007,the surface elevation decreased at 3.7 cm/yr;however,after April 2007,the surface elevation increased at 5.5 cm/yr.The more recent stages of surface elevation growth have been influenced by reductions in the summer basal melt,which is related to the decreases in ocean heat content.展开更多
Developing novel building blocks with predictable side-chain orientations and minimal intramolecular interactions is essential for peptide-based self-assembling materials.Traditional structures likeα-helices andβ-sh...Developing novel building blocks with predictable side-chain orientations and minimal intramolecular interactions is essential for peptide-based self-assembling materials.Traditional structures likeα-helices andβ-sheets rely on such interactions for stability,limiting control over exposed interacting moieties.Here,we reported a novel,frame-like peptide scaffold that maintains exceptional stability without intramolecular interactions.This structure exposes its backbone and orients side chains for hierarchical self-assembly into micron-scale cubes.By introducing mutations at specific sites,we controlled packing orientations,offering new options for tunable self-assembly.Our scaffold provides a versatile platform for designing advanced peptide materials,with applications in nanotechnology and biomaterials.展开更多
A novel approach for fabricating multi-principal element alloys with adjustable phase configurations and mechanical properties was developed using laser-aided additive manufacturing(LAAM),combining FCC-structured(face...A novel approach for fabricating multi-principal element alloys with adjustable phase configurations and mechanical properties was developed using laser-aided additive manufacturing(LAAM),combining FCC-structured(face-centered cubic)CoCrNi and BCC-structured(body-centered cubic)CoCrNiAl0.6TiFe feedstocks.During fabrication,CoCrNi powders and CoCrNiAl0.6TiFe powders were simultaneously fed into the melt pool at individually adjustable rates,allowing for controlled phase transitions.The resulting phase evolution demonstrated a gradual transition from a single FCC structure CoCrNi(A10.6TiFe)x(x=0,0.1,0.2,0.3)to a dual FCCB2 structure CoCrNi(Al0.6TiFe)x(x=0.4,0.5)as the proportion of BCC-structured powders increased.The B2 phase,enriched in Ti and Al due to their larger atomic radii and negative segregation enthalpy,precipitated around the FCC matrix,with volume fractions of 0.5%and 5.7%for CoCrNi(A10.6TiFe)0.4 and CoCrNi(A10.6TiFe)0.5,respectively.This phase transition resulted in significant mechanical enhancements.Yield and ultimate tensile strengths increased from 486.0 and 781.2 MPa(CoCrNi)to 887.2 and 1165.2 MPa(CoCrNi(A10.6TiFe)0.5).Dislocation-mediated hardening prevailed in single-phase FCC alloys,exhibiting a characteristic dislocation density of 2.5×10^(15)m^(-2)for CoCrNi(A10.6TiFe)0.3 alloy.Once the B2 phase precipitated,precipitation strengthening became dominant,as observed in transmission electron microscopy(TEM),where dislocations accumulated around B2 precipitates.This study presents an innovative alloy fabrication strategy that enables precise tuning of FCC-BCC dualphase structures,facilitating the direct fabrication of components with spatially customized properties.These findings provide valuable insights for developing multiprincipal element alloys with heterogeneous microstructures for advanced engineering applications.展开更多
Initial firing temperatures play an important role on the combustion rate of propellant. In gun propellants, initial temperature is a key factor for both accuracy and safety. Ideally, the initial temperature of the pr...Initial firing temperatures play an important role on the combustion rate of propellant. In gun propellants, initial temperature is a key factor for both accuracy and safety. Ideally, the initial temperature of the propellant should not influence the ballistic properties of the round. Nevertheless, constant initial temperature coefficients can not be achieved easily. This work focuses on the influence of the firing temperature on the ballistic properties, the mechanical integrity and the sensitivity to impact of nitrocellulose based propellants. Combustion rates have been determined by closed vessel tests. Ballistic properties have been investigated by firing 5.56 cartridges. The propellants have been conditioned at temperatures ranging from -54 ℃ to ＋71 ℃ before firing. The largest temperature coefficient is observed at high temperatures. The temperature sensitivity of the peak pressure in the combustion chamber can not be fully explained by the results from the closed vessel test. The authors speculated that the mechanical behaviour of the propellant grains at low temperatures influences also the overall ballistic properties of the round. Impact tests with propellants conditioned at low and high temperatures permit to investigate their mechanical strength under extreme temperatures and to better understand the propellant performance during firing. Tests on aged propellants have been conducted as well.展开更多
The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerim...The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerimental results show that the symmetric TiO2 membranes display better sintering activity in the air than in argon, and the mean pore diameters and porosities of the membrane sintered in argon are higher than those of the membrane sintered in the air at the same temperature. The surface compositions of the symmetric TiO2 membrane sintered in the air and in argon at different temperatures, as studied by X-ray photoelectron spectroscopy, are discussed in terms of their chemical composition, with particular emphasis on the valence state of the titanium ions. The correlation between the valence state of the titanium ions at the surface and the surface charge properties is examined.It is found that the presence of Ti^3＋, introduced at the surface of the symmetric TiO2 membranes by sintering in a lower partial pressure of oxygen, is related to a significant decrease in the isoelectric point. TiO2 with Ti^4＋ at the interface has an isoelectric point of 5.1, but the non-stoichiometric TiO2-x with Ti^3＋ at the interface has a lower isoelectric point of 3.6.展开更多
Carbon-based composites, including carbon reinforced composites and carbon-matrix composites, in defence technologies have raised a lot of attention due to its significant physical capabilities, superior thermal and m...Carbon-based composites, including carbon reinforced composites and carbon-matrix composites, in defence technologies have raised a lot of attention due to its significant physical capabilities, superior thermal and mechanical stability, and its eco-friendly nature. Carbon-based composite which incorporating with various carbonaceous materials such as coke, char, black carbon, activated carbon, carbon fibre and other carbon nanomaterials (carbon nanotubes, carbon nanofibres, graphene and graphite) are the greatest viable option for the development of advanced defence technologies. In this review article the characteristics of carbon-based materials and its composites are discussed for their distinct application in defence sectors;aeronautics, maritime, automotive, electronics, energy storage, electromagnetic interference (EMI) shielding and structures. The origin of carbonaceous materials and its production techniques were discussed. Carbon-based composites have a promising future in defence technology, particularly in chemical sensors, drug delivery agents, radar technologies, and nanocomposites due to their low cost, easy availability, flexibility in design and processing.展开更多
Allelopathy is prevalent in agricultural ecosystems and mediated by plant-derived secondary metabolites(allelochemicals).Allelochemicals are released by donor plants and affect the root growth and development of recep...Allelopathy is prevalent in agricultural ecosystems and mediated by plant-derived secondary metabolites(allelochemicals).Allelochemicals are released by donor plants and affect the root growth and development of receptor plants.Allelopathy is responsible for the continuous cropping obstacles in cucumber(Cucumis sativus L.).p-Hydroxybenzoic acid(pHBA),an autotoxin from root exudates of cucumber,has been proposed to be an important allelopathic chemical.However,the molecular mechanism by which pHBA affect root growth and development in cucumber is unknown.Here,we found that pHBA treatment suppressed root growth of cucumber by reducing the meristem activity and cell length.This root growth defect is caused by reduced reactive oxygen species(ROS)accumulation in root tips.After pHBA treatment,the expression levels of several ROS-scavenging-related genes were increased,including peroxidase(POD),catalase(CAT)and metallothionein(MT).Moreover,exogenously application of salicylhydroxamate(SHAM),a peroxidase inhibitor,can partially restore the pHBA treatment induced root growth inhibition.Furthermore,we found that there is natural variation for the inhibitory effect of pHBA on root growth.We also showed that pHBA treatment could maintain higher level of ROS accumulated in the pHBA less sensitive cucumber than that in the pHBA-sensitive cucumber.These results suggest that pHBA inhibits root growth by reducing root tip ROS level in cucumber.展开更多
基金supported by the Scientific Program of Tianjin Municipal Education Commission(Natural Science,Grant No.2022KJ254)Science Foundation of the Second Hospital of Tianjin Medical University(Grant No.2021ydey05)Tianjin Municipal Health Commission Integrated Traditional Chinese and Western Medicine Project(Grant No.2021173).
文摘Arteriovenous fistula(AVF)calcification is a common complication in hemodialysis patients that leads to AVF dysfunction and decreases the AVF survival,but the mechanisms of AVF calcification,especially the role of hemodynamic changes in AVF calcification have not been fully investigated.In this study,a computational fluid dynamics(CFD)model was carried out based on AVF,at the distal anastomosis of the cephalic vein and radial artery,generated from a patient-specific computed tomography(CT)angiography and Doppler ultrasound image.Hemodynamic factors were considered to explore the mechanisms responsible for the initiation and progression of AVF calcification.Five stages in one cardiac cycle were chosen to be studied for the velocity field,pressure,time-averaged wall shear stress(TAWSS),and oscillatory shear index(OSI).Blood pressure was higher in the arteriovenous anastomosis,and variations of great amplitude of pressure were examined during the cardiac cycle.Blood pressure,transient shear stress,TAWSS,and OSI were higher in the arteriovenous anastomosis and at the bottom of expanded outflow vein,and these sites were highly consistent with the calcified areas shown on CT angiography.On the contrary,no calcification was found in sites where streamline was stable,blood pressure did not change dramatically,as well as TAWSS and OSI were lower.It was shown that AVF calcification was correlated with hemodynamic changes,which may contribute to further understanding the mechanisms of AVF calcification and providing scientific evidence to inform the optimization of surgical strategies and the development of personalized interventional measures in clinical contexts.
基金supported by the National Key Research and Development Program(2021YFB150740401)National Natural Science Foundation of China(42202336)the CAS Pioneer Hundred Talents Program in China(Y826031C01)。
文摘Hydraulic stimulation technology is widely employed to enhance the permeability of geothermal reservoirs.Nevertheless,accurately predicting hydraulic fracture propagation in complex geological conditions remains challenging,thereby hindering the effective utilization of existing natural fractures.In this study,a phase field model was developed utilizing the finite element method to examine the influence of fluid presence,stress conditions,and natural fractures on the initiation and propagation of hydraulic fractures.The model employs Biot's poroelasticity theory to establish the coupling between the displacement field and the fluid field,while the phase field theory is applied to simulate fracture behavior.The results show that whenσ_(x0)/σ_(y0)<3 or qf<20 kg/(m^(3)·s),the presence of natural fractures can alter the original propagation direction of hydraulic fractures.Conversely,in the absence of these conditions,the propagation path of natural fractures is predominantly influenced by the initial stress field.Furthermore,based on the analysis of breakdown pressure and damage area,the optimal intersection angle between natural fractures and hydraulic fractures is determined to range from 45°to 60°.Finally,once a dominant channel forms,initiating and propagating hydraulic fractures in other directions becomes increasingly difficult,even in highly fractured areas.This method tackles the challenges of initiating and propagating hydraulic fractures in complex geological conditions,providing a theoretical basis for optimizing Enhanced Geothermal System(EGS)projects.
文摘The paper considers the methodology for a comprehensive analysis of the stability of an open pit-dump system,using limit equilibrium(LEM)and finite element(FEM)methods in the Russian CAE(computer-aided engineering)software Fidesys.It briefly highlights the issues of comparing limit equilibrium methods using the VNIMI(Research Institute of Geomechanics and Mine Surveying-Intersectoral Scientific Center"VNIMI")methodology and a specialized software product with numerical methods.The main focus of this study is to compare the results of the stability analysis in the volumetric model of the open pit-dump system using limit equilibrium and finite element methods in the CAE software Fidesys.It was found that,when modeling the combined operation of an open pit-dump system in complex terrain,both methods should be used,as each has its own advantages.The finite element method,for instance,has certain features that are not present in the calculations using the limit equilibrium approach.As a key scientific contribution,this paper introduces an automation program for calculating the stability of open-pit walls using the limit equilibrium method in CAE Fidesys,which was not previously integrated in the original software.The calculations performed with the use of this newly developed module were compared to those obtained from other widely used software solutions available on the market.The findings demonstrate a remarkable level of convergence in the calculation results for all relevant parameters,including the safety factor,localization,instability type,and deformation.The proposed approach i mproves the accuracy of calculati ons and ensures consistency between the higher stress design zones and the actual deformation and fracture patterns.It also enhances the ability to predict the behavior of rock mass when calculating stability parameters for facilities,both during operation and desi gn.
基金support from the National Natural Science Foundation of China(22268025,52473083,and 22475176)Key Research and Development Program of Yunnan Province(202403AP140036)+2 种基金Natural Science Basic Research Program of Shaanxi(2024JC-TBZC-04)Applied Basic Research Program of Yunnan Province(202201AT070115 and 202201BE070001-031)supported by the Innovation Capability Support Program of Shaanxi(2024RS-CXTD-57).
文摘The microstructure design for thermal conduction pathways in polymeric electrical encapsulation materials is essential to meet the stringent requirements for efficient thermal management and thermal runaway safety in modern electronic devices.Hence,a composite with three-dimensional network(Ho/U-BNNS/WPU)is developed by simultaneously incorporating magnetically modified boron nitride nanosheets(M@BNNS)and non-magnetic organo-grafted BNNS(U-BNNS)into waterborne polyurethane(WPU)to synchronous molding under a horizontal magnetic field.The results indicate that the continuous in-plane pathways formed by M@BNNS aligned along the magnetic field direction,combined with the bridging structure established by U-BNNS,enable Ho/U-BNNS/WPU to exhibit exceptional in-plane(λ//)and through-plane thermal conductivities(λ_(⊥)).In particular,with the addition of 30 wt%M@BNNS and 5 wt%U-BNNS,theλ//andλ_(⊥)of composites reach 11.47 and 2.88 W m^(-1) K^(-1),respectively,which representing a 194.2%improvement inλ_(⊥)compared to the composites with a single orientation of M@BNNS.Meanwhile,Ho/U-BNNS/WPU exhibits distinguished thermal management capabilities as thermal interface materials for LED and chips.The composites also demonstrate excellent flame retardancy,with a peak heat release and total heat release reduced by 58.9%and 36.9%,respectively,compared to WPU.Thus,this work offers new insights into the thermally conductive structural design and efficient flame-retardant systems of polymer composites,presenting broad application potential in electronic packaging fields.
基金financially supported by the National Key R&D Program of China(2021YFB2401800)。
文摘Degradation of materials is one of the most critical aging mechanisms affecting the performance of lithium batteries.Among the various approaches to investigate battery aging,phase-field modelling(PFM)has emerged as a widely used numerical method for simulating the evolution of the phase interface as a function of space and time during material phase transition process.Moreover,PFM coupled with multi-physics analyses is particularly well-suited for investigating the mesoscale microstructural evolution of materials,providing quantitative understandings of aging and failure mechanisms in lithium batteries.In this paper,we comprehensively overview the state-of-art applications of PFM in the research of degradation and failure processes in lithium batteries,particularly focusing on the theoretical framework and development of the PFMs for lithium deposition/dissolution,phase separation,and crack propagation.Furthermore,we summarize the existing challenges and prospect some future developments in PFMs,aiming to offer new insights into the advancement of PFM and ultimately enhance the development of lithium batteries.
基金supported by the Lithium Resources and Lithium Materials Key Laboratory of Sichuan Province(LRMKF202405)the National Natural Science Foundation of China(52402226)+3 种基金the Natural Science Foundation of Sichuan Province(2024NSFSC1016)the Scientific Research Startup Foundation of Chengdu University of Technology(10912-KYQD2023-10240)the opening funding from Key Laboratory of Engineering Dielectrics and Its Application(Harbin University of Science and Technology)(KFM202507,Ministry of Education)the funding provided by the Alexander von Humboldt Foundation。
文摘The properties of electrolytes are critical for fast-charging and stable-cycling applications in lithium metal batteries(LMBs).However,the slow kinetics of Li^(+)transport and desolvation in commercial carbonate electrolytes,cou pled with the formation of unstable solid electrolyte interphases(SEI),exacerbate the degradation of LMB performance at high current densities.Herein,we propose a versatile electrolyte design strategy that incorporates cyclohexyl methyl ether(CME)as a co-solvent to reshape the Li^(+)solvation environment by the steric-hindrance effect of bulky molecules and their competitive coordination with other solvent molecules.Simulation calculations and spectral analysis demonstrate that the addition of CME molecules reduces the involvement of other solvent molecules in the Li solvation sheath and promotes the formation of Li^(+)-PF_(6)^(-)coordination,thereby accelerating Li^(+)transport kinetics.Additionally,this electrolyte composition improves Li^(+)desolvation kinetics and fosters the formation of inorganic-rich SEI,ensuring cycle stability under fast charging.Consequently,the Li‖LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)battery with the modified electrolyte retains 82% of its initial capacity after 463 cycles at 1 C.Even under the extreme fast-charging condition of 5 C,the battery can maintain 80% capacity retention after 173 cycles.This work provides a promising approach for the development of highperformance LMBs by modulating solvation environment of electrolytes.
基金financial support from National Natural Science Foundation of China(22271178,U2032131,21972103)International Cooperation Key Project of Science and Technology Department of Shaanxi,China(2022KWZ-06)+3 种基金the Youth Talent Promotion Project of Science and Technology Association of Universities of Shaanxi Province(20210602)Research Project of Xi’an Science and Technology Bureau(2022GXFW0011)Science and Technology New Star in Shaanxi Province(2023KJXX-045)Shaanxi Provincial Department of Education Service Local Special Project,Industrialization Cultivation Project(23JC007)。
文摘Lithium(Li)deposition and nucleation at solid electrolyte interphase(SEI)is the main origin for the capacity decay in Li metal batteries(LMBs).SEI conversion with enhanced electrochemical and mechanical properties is an effective approach to achieve uniform nucleation of Li^(+)and stabilize the lithium metal anode.However,complex interfacial reaction mechanisms and interface compatibility issues hinder the development of SEI conversion strategies for stabilizing lithium metal anodes.Herein,we presented the release of I_(3)^(-)in–NH_(2)-modified metal–organic frameworks for a Li metal surface SEI phase conversion strategy.The–NH_(2)group in MOF pores induced the formation of I_(3)^(-)from I_(2),which was further spontaneously reacted with inactive Li_(2)O transforming into high-performance LiI and LiIO_(3)interphase.Furthermore,theoretical calculation provided deeply insight into the unique reconstructed interfacial formation and electrochemical mechanism of rich LiI and LiIO_(3)SEI.As a result,the Li^(+)deposition and nucleation were improved,facilitating the transport kinetics of Li^(+)and inhibiting the growth of lithium dendrites.The assembled solid-state Li||LiFePO_(4)full cells exhibited superior long-term stability of 800 cycles and high Coulombic efficiency(>99%),Li||LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)pouch cell also displayed superior practical performance over 200 cycles at 2 C,high loading of 5 mg cm^(-2)and safety performance.This innovative SEI design strategy promotes the development of high-performance solid-state Li metal batteries.
基金financially supported by the National Natu-ral Science Foundation of China(Nos.92366201 and 52371068)Natural Science Foundation of Jiangsu Province(No.BK20220965)the Fundamental Research Funds for the Central Universities(No.30923010911).
文摘Tribocorrosion readily removes the protective corrosion product,creates new reactive corrosion sites and thus accelerates material loss in metallic materials.This is evidenced by a pronounced or gradual decline in open circuit potential(OCP)during tribocorrosion assessments.Here we report that grain refinement can not only enhance wear resistance in dry conditions,but also induce an anomalously stable OCP variation and fortify tribocorrosion resistance in ultrahigh-purity magnesium during tribocorrosion.The tribocorrosion tests revealed that the fine-grained Mg(FG-Mg)sample exhibited a wear rate(4.56×10^(−4) mm^(3)/(N m))approximately half that of the coarse-grained Mg(CG-Mg)sample(7.87×10^(−4) mm^(3)/(N m)).CG-Mg showed a gradual OCP decrease,associated with a thin,unprotective tribocorrosion layer,even thinner than that resulting from dry sliding.Conversely,FG-Mg exhibited stable OCP evolution and quasi-linear tribocorrosion kinetics over time,attributed to a thick,protective tribocorrosion layer.Transmission electron microscopy data suggest that high-diffusivity pathways for oxygen along grain boundaries at the early tribocorrosion stages facilitate the formation of a continuous,protective MgO layer and an adjacent oxidized layer with a depth-dependent oxygen content gradient,enhancing tribocorrosion resistance in FG-Mg.Our findings offer valuable insights for strategically tailoring tribocorrosion resistance by modulating the OCP variation of highly active metals and alloys.
基金supported by the Beijing Natural Science Foundation(Grant No.JQ24002)the National Key Basic Research Program of China(Grant No.2020YFA0309100)+3 种基金the National Natural Science Foundation of China(Grant Nos.U22A20263,52250308,12304158,12325401,12274069,12404102,and 12474096)the Chinese Academy of Sciences(CAS)Project for Young Scientists in Basic Research(Grant No.YSBR-084)the CAS Youth Interdisciplinary Team,the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022B1515120014)the Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology,and the International Young Scientist Fellowship of Institute of Physics,CAS.
文摘Heterointerfaces have been pivotal in unveiling extraordinary interfacial properties and enabling multifunctional material platforms.Despite extensive research on all-oxide interfaces,heterointerfaces between different material classes,such as oxides and nitrides,remain underexplored.Here we present the fabrication of atomically sharp heterointerfaces between antiperovskite Ni_(3)InN and perovskite SrVO_(3).Leveraging layer-resolved scanning transmission electron microscopy and electron energy loss spectroscopy,we identified pronounced charge transfer across the well-ordered interface.First-principles calculations confirmed our experimental observations and further predicted an emergent magnetic moment within the Ni_(3)InN layer due to the charge transfer.These findings pave the way for novel electronic and spintronic applications by enabling tunable interfacial properties in nitride/oxide systems.
基金supported by the National Natural Science Foundation of China(No.22209126)the Opening Project of Key Laboratory of Optoelectronic Chemical Materials and Devices,Ministry of Education,Jianghan University(No.JDGD-202314)。
文摘The commercialization of polymer electrolyte membrane water splitting technology significantly depends on the oxygen/hydrogen evolution reaction(OER/HER)electrocatalysts;customarily catalyzed by platinum(Pt)and ruthenium/iridium oxides(RuO_(2)/IrO_(2)).In this work,we have devised a novel strategy to improve the catalytic activities towards OER and HER catalysis via the decoration of RuO_(2)with Pt.Pt dopants in ruthenium oxides(Pt-RuO_(2))create more oxygen vacancies inducing a weaker interaction between active site and oxygen reaction intermediates,evidenced by downshifted d band center and increment in e_(g)orbital filling of Ru atom;thereby,the acidic OER performance of Pt-RuO_(2)is enhanced by 3.5-fold than commercial RuO_(2)by mean of turnover frequency at 1.6 V vs.RHE.Moreover,Pt-RuO_(2)exhibits a similar HER performance to commercial Pt/C.The potential for overall water splitting is decreased by 0.18 V at100 mA/cm^(2);besides,an excellent stability is also recorded after the incorporation of Pt dopants.TheΔ_(ε_(d-p))value of Pt-RuO_(2)was 1.76 e V,which is lower than the counterpart of RuO_(2),suggesting easy electron transition between d and p orbitals,suppressing the over-oxidation of RuO_(2);thereby,a higher stability is achieved for Pt-RuO_(2).The invitation of Pt dopants to boost catalytic activity and stability has also been extended to IrO_(2).
基金Project(52105498) supported by the National Natural Science Foundation of ChinaProject(2021RC3074) supported by the Science and Technology Innovation Program of Hunan Province,China+2 种基金Project(2023YFB4605500) supported by the National Key Research and Development Program of ChinaProject(AHL2022KF04) supported by the Advanced Laser Technology Laboratory of Anhui Province,ChinaProject(kq2402089) supported by the Changsha Natural Science Foundation,China。
文摘High-energy continuous wave(CW)lasers are mostly used in laser damage applications,but efficient laser ablation of transparent materials is challenging due to low optical absorption.Considering the potential of femtosecond(fs)laser-induced air filament for high-peak laser transmission over long distances,femtosecond(fs)laser-induced air filaments are combined with a millisecond(ms)laser to form an fs-ms CPL,enhancing the efficiency of sapphire ablation through synchronized spatial-temporal focusing.Experimental results show that ablation efficiency increases with the ms peak power and duty ratio.Excessive thermal stress leads to fragmentation of the sapphire when the ms duty ratio is over 30%at the peak power of 800 W,or when the peak power is over 500 W at a duty ratio of 100%.Also,the mechanism of high-efficiency damage is revealed through in-situ high-speed imaging.According to it,the ablation process went through 4 stages within 1.5 ms:defect-creating,melting and ablation,spattering,and fragmentation.Finally,the equivalent ablation efficiency of the fs-ms CPL is as high as 1.73×10^(7)μm^(3)/J,about 28 times higher compared to the fs laser only.The CPL damage method explored in this paper can provide theoretical guidance for efficient laser damage of transparent materials.
基金supported by the National Natural Science Foundation of China(No.52172206)the Project of Science&Technology Office of Jiangsu Province(No.KB20181043)the Talent Research Projects of Qilu University of Technology(Shandong Academy of Sciences)(No.2024RCKY018)。
文摘Photothermal catalysis is a promising technology primarily utilized the solar energy to produce photogenerated e^(-)/h^(+) pairs together with the production of heat energy.However,the inefficient separation of charge carriers and inadequate response to near-infrared(NIR)light usually leads to the unsatisfactory photocatalytic efficiency,hindering their application potentials.In this work,a significantly enhanced photothermal catalytic hydrogen evolution reaction over the lead-free perovskite Cs_(3)Bi_(2)Br_(9)/FeS_(2)(CBB/FS)heterostructure is simultaneously verified,where the CBB/FS Z-scheme heterojunctions display the strong stability and superb photothermal catalytic activity.Under the simulated solar irradiation(AM 1.5G),the optimized CBB/FS-5 achieves a photocatalytic hydrogen evolution rate of 31.5 mmol g^(-1)h^(-1),which is 112.6 and 77.1 times higher than that of FS and CBB,respectively,together with an apparent quantum yield of 29.5%at 420 nm.This significantly improved photocatalytic H_(2)evolution can be mainly attributed to the Z-scheme charge transfer and photothermal-assisted synergistically enhanced photocatalytic H_(2)production,and the potential mechanism of the enhanced photocatalytic H_(2)evolution is also proposed by photoelectrochemical characterizations,in situ XPS,EPR spectra,and the DFT calculations.This work provides new insights to the design of high-efficient photothermal catalysts,leading to the sustainable and efficient solutions towards the energy and environmental challenges.
基金supported by the National Key Research and Development Program of China under grant numbers 2023YFC2809103 and 2024YFC2813505the National Natural Science Foundation of China under the grant number 41706216+2 种基金the Fundamental Research Funds for the Central Universities under grant numbers 2042022kf1204,2042022kf1069,2042023gf0012,2042022dx0001the Hubei Provincial Natural Science Foundation of China under grant number 2022CFB081the State Key Laboratory of Geodesy and Earth's Dynamics,Innovation Academy for Precision Measurement Science and Technology under grant number SKLGED2023-2-6。
文摘Ice shelves are important passageways for ice sheets flowing into the ocean.Through iceberg calving and basal melting,ice shelves exert considerable influence on the mass balance of the Antarctic Ice Sheet and glacier stability.The Ross Ice Shelf(RIS),the largest body of floating ice on Earth,plays an essential role in any changes in the mass balance of the Antarctic Ice Sheet.The long-term elevation change trend of RIS has been calculated with multiple satellite altimetry in previous studies.However,the seasonal variations were less revealed.Based on crossover analysis and indirect observation adjustments,this study proposed a new method for constructing seasonal records for surface elevation changes in the RIS using ICESat laser altimetry data from 2003 to 2009.The results showed that surface elevation changes exhibited seasonal variations with fluctuations over 20 cm,and the seasonal change characteristics were closely related to the temperature.Interannual variations in RIS surface elevation decreased from 2003 to2009 at a rate of 2 cm/yr.From March 2003 to April 2007,the surface elevation decreased at 3.7 cm/yr;however,after April 2007,the surface elevation increased at 5.5 cm/yr.The more recent stages of surface elevation growth have been influenced by reductions in the summer basal melt,which is related to the decreases in ocean heat content.
基金supported by the National Basic Research Program of China 973 Program(Nos.2021YFA0910803,2021YFC2103900)the National Natural Science Foundation of China(No.21977011)+4 种基金the Natural Science Foundation of Guangdong Province(Nos.2022A1515010996 and 2020A1515011544)the Shenzhen Science and Technology Innovation Committee(Nos.RCJC20200714114433053,JCYJ20180507181527112 and JCYJ20200109140406047)the Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions(No.2019SHIBS0004)the Shenzhen Fundamental Research Program(No.GXWD20201231165807007–20200827170132001)Tian Fu Jin Cheng Laboratory(Advanced Medical Center)Group Racing Project(No.TFJC2023010008)。
文摘Developing novel building blocks with predictable side-chain orientations and minimal intramolecular interactions is essential for peptide-based self-assembling materials.Traditional structures likeα-helices andβ-sheets rely on such interactions for stability,limiting control over exposed interacting moieties.Here,we reported a novel,frame-like peptide scaffold that maintains exceptional stability without intramolecular interactions.This structure exposes its backbone and orients side chains for hierarchical self-assembly into micron-scale cubes.By introducing mutations at specific sites,we controlled packing orientations,offering new options for tunable self-assembly.Our scaffold provides a versatile platform for designing advanced peptide materials,with applications in nanotechnology and biomaterials.
基金financially supported by the following sources:Guangdong Basic and Applied Basic Research Foundation(No.2023B1515120045)Yangjiang City Key Industry Talent Revitalization Plan Project for Alloy Materials and Hardware Scissors(No.RCZX202302)+7 种基金GDAS'Project of Science and Technology Development(Nos.2022GDASZH-2022010108,2022GD ASZH-2022010107 and 2024GD ASZH-2024010102)GDAS'Young Talent Project(No.2024GDASQNRC-0314)Guangzhou Basic and Applied Basic Research Foundation(No.2023A04J1628)the National Key R&D Program of China(No.2022YFB4600700)National Natural Science Foundation of China(No.52371110)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011510)Shenzhen Science and Technology Program(Nos.JCYJ20220530115011026 and JCYJ20230807093410021)Shanxi Province Key R&D Project(No.202302050201011)
文摘A novel approach for fabricating multi-principal element alloys with adjustable phase configurations and mechanical properties was developed using laser-aided additive manufacturing(LAAM),combining FCC-structured(face-centered cubic)CoCrNi and BCC-structured(body-centered cubic)CoCrNiAl0.6TiFe feedstocks.During fabrication,CoCrNi powders and CoCrNiAl0.6TiFe powders were simultaneously fed into the melt pool at individually adjustable rates,allowing for controlled phase transitions.The resulting phase evolution demonstrated a gradual transition from a single FCC structure CoCrNi(A10.6TiFe)x(x=0,0.1,0.2,0.3)to a dual FCCB2 structure CoCrNi(Al0.6TiFe)x(x=0.4,0.5)as the proportion of BCC-structured powders increased.The B2 phase,enriched in Ti and Al due to their larger atomic radii and negative segregation enthalpy,precipitated around the FCC matrix,with volume fractions of 0.5%and 5.7%for CoCrNi(A10.6TiFe)0.4 and CoCrNi(A10.6TiFe)0.5,respectively.This phase transition resulted in significant mechanical enhancements.Yield and ultimate tensile strengths increased from 486.0 and 781.2 MPa(CoCrNi)to 887.2 and 1165.2 MPa(CoCrNi(A10.6TiFe)0.5).Dislocation-mediated hardening prevailed in single-phase FCC alloys,exhibiting a characteristic dislocation density of 2.5×10^(15)m^(-2)for CoCrNi(A10.6TiFe)0.3 alloy.Once the B2 phase precipitated,precipitation strengthening became dominant,as observed in transmission electron microscopy(TEM),where dislocations accumulated around B2 precipitates.This study presents an innovative alloy fabrication strategy that enables precise tuning of FCC-BCC dualphase structures,facilitating the direct fabrication of components with spatially customized properties.These findings provide valuable insights for developing multiprincipal element alloys with heterogeneous microstructures for advanced engineering applications.
文摘Initial firing temperatures play an important role on the combustion rate of propellant. In gun propellants, initial temperature is a key factor for both accuracy and safety. Ideally, the initial temperature of the propellant should not influence the ballistic properties of the round. Nevertheless, constant initial temperature coefficients can not be achieved easily. This work focuses on the influence of the firing temperature on the ballistic properties, the mechanical integrity and the sensitivity to impact of nitrocellulose based propellants. Combustion rates have been determined by closed vessel tests. Ballistic properties have been investigated by firing 5.56 cartridges. The propellants have been conditioned at temperatures ranging from -54 ℃ to ＋71 ℃ before firing. The largest temperature coefficient is observed at high temperatures. The temperature sensitivity of the peak pressure in the combustion chamber can not be fully explained by the results from the closed vessel test. The authors speculated that the mechanical behaviour of the propellant grains at low temperatures influences also the overall ballistic properties of the round. Impact tests with propellants conditioned at low and high temperatures permit to investigate their mechanical strength under extreme temperatures and to better understand the propellant performance during firing. Tests on aged propellants have been conducted as well.
基金Supported by the National-Basic Research Program of China （2003CB615707） and the National Natural Science Foundation of China （20636020）.
文摘The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerimental results show that the symmetric TiO2 membranes display better sintering activity in the air than in argon, and the mean pore diameters and porosities of the membrane sintered in argon are higher than those of the membrane sintered in the air at the same temperature. The surface compositions of the symmetric TiO2 membrane sintered in the air and in argon at different temperatures, as studied by X-ray photoelectron spectroscopy, are discussed in terms of their chemical composition, with particular emphasis on the valence state of the titanium ions. The correlation between the valence state of the titanium ions at the surface and the surface charge properties is examined.It is found that the presence of Ti^3＋, introduced at the surface of the symmetric TiO2 membranes by sintering in a lower partial pressure of oxygen, is related to a significant decrease in the isoelectric point. TiO2 with Ti^4＋ at the interface has an isoelectric point of 5.1, but the non-stoichiometric TiO2-x with Ti^3＋ at the interface has a lower isoelectric point of 3.6.
文摘Carbon-based composites, including carbon reinforced composites and carbon-matrix composites, in defence technologies have raised a lot of attention due to its significant physical capabilities, superior thermal and mechanical stability, and its eco-friendly nature. Carbon-based composite which incorporating with various carbonaceous materials such as coke, char, black carbon, activated carbon, carbon fibre and other carbon nanomaterials (carbon nanotubes, carbon nanofibres, graphene and graphite) are the greatest viable option for the development of advanced defence technologies. In this review article the characteristics of carbon-based materials and its composites are discussed for their distinct application in defence sectors;aeronautics, maritime, automotive, electronics, energy storage, electromagnetic interference (EMI) shielding and structures. The origin of carbonaceous materials and its production techniques were discussed. Carbon-based composites have a promising future in defence technology, particularly in chemical sensors, drug delivery agents, radar technologies, and nanocomposites due to their low cost, easy availability, flexibility in design and processing.
基金supported by the National Key Research and Development Program of China (2018YFD1000803)the National Natural Science Foundation of China (31800246)
文摘Allelopathy is prevalent in agricultural ecosystems and mediated by plant-derived secondary metabolites(allelochemicals).Allelochemicals are released by donor plants and affect the root growth and development of receptor plants.Allelopathy is responsible for the continuous cropping obstacles in cucumber(Cucumis sativus L.).p-Hydroxybenzoic acid(pHBA),an autotoxin from root exudates of cucumber,has been proposed to be an important allelopathic chemical.However,the molecular mechanism by which pHBA affect root growth and development in cucumber is unknown.Here,we found that pHBA treatment suppressed root growth of cucumber by reducing the meristem activity and cell length.This root growth defect is caused by reduced reactive oxygen species(ROS)accumulation in root tips.After pHBA treatment,the expression levels of several ROS-scavenging-related genes were increased,including peroxidase(POD),catalase(CAT)and metallothionein(MT).Moreover,exogenously application of salicylhydroxamate(SHAM),a peroxidase inhibitor,can partially restore the pHBA treatment induced root growth inhibition.Furthermore,we found that there is natural variation for the inhibitory effect of pHBA on root growth.We also showed that pHBA treatment could maintain higher level of ROS accumulated in the pHBA less sensitive cucumber than that in the pHBA-sensitive cucumber.These results suggest that pHBA inhibits root growth by reducing root tip ROS level in cucumber.
