The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,an...The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.展开更多
As a multidisciplinary phenomenon,panel aeroelasticity in shock-dominated flow is featured by two primary interactions:Fluid-Structure Interactions(FSIs)and Shock-Boundary Layer Interactions(SBLIs).The former raises s...As a multidisciplinary phenomenon,panel aeroelasticity in shock-dominated flow is featured by two primary interactions:Fluid-Structure Interactions(FSIs)and Shock-Boundary Layer Interactions(SBLIs).The former raises structural concerns,and the latter is of aerodynamic interest.Thus,panel aeroelasticity in shock-dominated flow represents a vital topic for the development and optimization of supersonic vehicles and propulsion systems.This review systematically summarizes recent advances in the methodologies applied to capture structural and fluid dynamics,including theoretical models,numerical simulations,and wind tunnel experiments.The application of data-driven modal decomposition,an advanced technique to extract physically crucial features,on the topic is introduced.From the perspective of FSIs,the distinctive aeroelastic behaviors in shock-dominated flow,including hysteresis phenomena and nonlinear responses,are highlighted.From the perspective of SBLIs,the modifications in their spatial and temporal characteristics imposed by the aeroelastic responses are emphasized.Motivated by the interaction between the shock waves and structural response,different strategies have been proposed to implement aeroelastic suppression and shock control,which have the potential to enhance structural safety and aerodynamic performance in the next generation of high-speed flight vehicles.展开更多
Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results ...Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results were obtained.Firstly,at pressures lower than 53GPa,the opaque minerals still keep the unmelted state,while at 78 GPa and higher,FeNi metal and troilite form eutectic intergrowths occurring as disorderly fine veinlets filling the shock-induced fractures in silicate minerals.Secondly,single kamacite grains still maintain their contour at 12 GPa,but a part of brittle troilite grains was fragmented and squeezed into the shock-induced fractures within kamacite grains.At53 and 133 GPa,many more troilite fragments are poured in the kamacite interior to form disordered hybrid aggregates or to form squiggly strips,respectively.Similar phenomena are observed within single troilite grains,but the mineral squeezed into troilite grains is kamacite.Thirdly,chromite is a hard and refractory oxide mineral.When the shock pressure rises step by step from 12 to 133 GPa,the shock effect of chromite is only fragmentation.Its grain size decreases from tens of um at 53 GPa to a few um at 133 GPa.And,fourthly,native copper exhibits distinct redistribution behavior at high temperature.In Jilin samples shock-loaded to 12 GPa,copper initially located at troilite-kamacite interfaces partially transferred into small troilite grains containing fine FeNi particles.At 53 and 133 GPa,native copper preferentially transferred into larger troilite grains containing more particles of eutectic FeNi metal.展开更多
The manipulation of intense shock waves to either attenuate or enhance damage has long been a key goal in the domain of impact dynamics.Effective methods for such manipulation,however,remain elusive owing to the wide ...The manipulation of intense shock waves to either attenuate or enhance damage has long been a key goal in the domain of impact dynamics.Effective methods for such manipulation,however,remain elusive owing to the wide spectrum and irreversible destructive nature of intense shock waves.This work proposes a novel approach for actively controlling intense shock waves in solids,inspired by the principles of optical and explosive lenses.Specifically,by designing a shock wave convex lens composed of a low-shock-impedance material embedded in a high-shock-impedance matrix,we prove the feasibility of transforming a planar shock into a spherically converging shock.This is based on oblique shock theory,according to which shock waves pass through an oblique interface and then undergo deflection.Both experimental and simulation results demonstrate that,as expected,the obtained local spherical shock wave has a wavefront that is nearly perfectly spherical and uniform in pressure.Thus,this work proves the possibility of generating spherical shock waves using plate-impact experiments and highlights the potential of further exploration of the manipulation of shock waves in solids.It also contributes an innovative perspective for both armor penetration technologies and shock wave mitigation strategies.展开更多
We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-or...We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-order low-dissipative finite difference operators with energy-preserving properties.No-slip,adiabatic boundary conditions are enforced at the surface of large particles(with diameters significantly larger than the local grid spacing)using a ghost-point immersed boundary method.Two-way coupling between the gas phase and small particles(with diameters proportional to the grid spacing)is accounted for through volumetric source terms for interphase momentum and energy exchange.A simple and efficient approach for collision detection between small and large particles is proposed.The framework is applied to simulations of planar shocks interacting with bidisperse distributions of particles with size ratios of approximately thirty.Particle dispersion and size segregation are reported and a simple analytical model for size segregation is proposed.展开更多
Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens un...Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.展开更多
For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehe...For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehensive review of flow characteristics at the crotch of VSLEs,with particular focus on the transition of shock interaction types and the variation of wall heat flux under different freestream Mach numbers and geometric configurations.The mechanisms governing shock transition,unsteady oscillations,hysteresis,and three-dimensional effects in VSLE flows are first examined.Subsequently,thermal protection strategies aimed at mitigating extreme heating loads are reviewed,emphasizing their relevance to practical engineering applications.Special attention is given to recent studies addressing thermochemical nonequilibrium effects on VSLE shock interactions,and the limitations of current research are critically assessed.Finally,perspectives for future investigations into hypersonic VSLE shock interactions are outlined,highlighting opportunities for advancing design and thermal management strategies.展开更多
Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study el...Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study elucidates the fundamental mechanisms of ultrafast laser shock imprinting(LSI)in two-dimensional tellurium(Te),establishing a direct relationship between strain field orientation,mold topology,and anisotropic structural evolution.This is the first demonstration of ultrafast LSI on chiral chain Te unveiling orientation-sensitive dislocation networks.By applying controlled strain fields parallel or transverse to Te’s helical chains,we uncover two distinct deformation regimes.Strain aligned parallel to the chain’s direction induces gliding and rotation governed by weak interchain interactions,preserving covalent intrachain bonds and vibrational modes.In contrast,transverse strain drives shear-mediated multimodal deformations—tensile stretching,compression,and bending—resulting in significant lattice distortions and electronic property modulation.We discovered the critical role of mold topology on deformation:sharp-edged gratings generate localized shear forces surpassing those from homogeneous strain fields via smooth CD molds,triggering dislocation tangle formation,lattice reorientation,and inhomogeneous plastic deformation.Asymmetrical strain configurations enable localized structural transformations while retaining single-crystal integrity in adjacent regions—a balance essential for functional device integration.These insights position LSI as a precision tool for nanoscale strain engineering,capable of sculpting 2D material morphologies without compromising crystallinity.By bridging ultrafast mechanics with chiral chain material science,this work advances the design of strain-tunable devices for next-generation electronics and optoelectronics,while establishing a universal framework for manipulating anisotropic 2D systems under extreme strain rates.This work discovered crystallographic orientation-dependent deformation mechanisms in 2D Te,linking parallel strain to chain gliding and transverse strain to shear-driven multimodal distortion.It demonstrates mold geometry as a critical lever for strain localization and dislocation dynamics,with sharp-edged gratings enabling unprecedented control over lattice reorientation.Crucially,the identification of strain field conditions that reconcile severe plastic deformation with single-crystal retention offers a pathway to functional nanostructure fabrication,redefining LSI’s potential in ultrafast strain engineering of chiral chain materials.展开更多
Stator vanes especially vane suction sides of transonic turbines are subjected to high frequency excitation forces under many circumstances,and thus are exposed to the risk of high cycle fatigue.Therefore,it is necess...Stator vanes especially vane suction sides of transonic turbines are subjected to high frequency excitation forces under many circumstances,and thus are exposed to the risk of high cycle fatigue.Therefore,it is necessary to reveal the flow mechanism of this kind of excitations for potential prevention measures.In this paper,the traveling shock phenomenon in the transonic turbine stator/rotor gap is observed and the concept of‘Inter-Row Traveling Shock(IRTS)'is proposed through the unsteady Reynolds-Averaged Navier-Stokes(RANS)simulation of a typical highlyloaded transonic turbine stage.The characteristics of an IRTS were described and summarized in aspects of unsteady shock wave system,aerodynamic characteristics and motion.The probable forming mechanism of an IRTS was explained through a theoretical model and it was validated through correct prediction of the flow state parameter change across the IRTS.Since IRTSs would strike onto vane suction sides,the pressure oscillation dynamic modes on vane suction side corresponding to the characteristic frequencies associated with IRTS were extracted through Dynamic Mode Decomposition(DMD),from which the way and extent of the IRTS influences on vane aerodynamic excitation were revealed and evaluated.Over 82%pressure oscillation energy on vane suction side could be brought by the IRTS sweeping along with blade rotation.展开更多
Hemorrhagic shock(HS)is a leading cause of death worldwide,particularly within the first 24 h post-injury.Current treatments are limited,especially in low-resource settings.Therapeutic hypothermia(TH)offers potential ...Hemorrhagic shock(HS)is a leading cause of death worldwide,particularly within the first 24 h post-injury.Current treatments are limited,especially in low-resource settings.Therapeutic hypothermia(TH)offers potential benefits by reducing metabolic demands and protecting organs,but its application in HS is challenged by cooling difficulties and side effects.This study introduces a novel nasal gel formulation of N6-cyclohexyladenosine(CHA),an adenosine A1 receptor agonist,designed to enhance brain delivery while minimizing peripheral side effects.In a mouse model of HS,administration of CHA nasal gel significantly improved survival rates,reduced metabolic rates,and protected major organs without worsening coagulopathy.Metabolomics analysis revealed a shift towards fatty acid oxidation and increased antioxidant capacity.These findings demonstrate that CHA nasal gel effectively induces TH,offering a safe and innovative treatment strategy for HS,particularly in resource-limited environments.展开更多
It is well known that aluminum and copper exhibit structural phase transformations in quasi-static and dynamic measurements,including shock wave loading.However,the dependence of phase transformations in a wide range ...It is well known that aluminum and copper exhibit structural phase transformations in quasi-static and dynamic measurements,including shock wave loading.However,the dependence of phase transformations in a wide range of crystallographic directions of shock loading has not been revealed.In this work,we calculated the shock Hugoniot for aluminum and copper in different crystallographic directions([100],[110],[111],[112],[102],[114],[123],[134],[221]and[401])of shock compression using molecular dynamics(MD)simulations.The results showed a high pressure(>160 GPa for Cu and>40 GPa for Al)of the FCC-to-BCC transition.In copper,different characteristics of the phase transition are observed depending on the loading direction with the[100]compression direction being the weakest.The FCC-to-BCC transition for copper is in the range of 150–220 GPa,which is consistent with the existing experimental data.Due to the high transition pressure,the BCC phase transition in copper competes with melting.In aluminum,the FCC-to-BCC transition is observed for all studied directions at pressures between 40 and 50 GPa far beyond the melting.In all considered cases we observe the coexistence of HCP and BCC phases during the FCC-to-BCC transition,which is consistent with the experimental data and atomistic calculations;this HCP phase forms in the course of accompanying plastic deformation with dislocation activity in the parent FCC phase.The plasticity incipience is also anisotropic in bothmetals,which is due to the difference in the projections of stress on the slip plane for different orientations of the FCC crystal.MD modeling results demonstrate a strong dependence of the FCC-to-BCC transition on the crystallographic direction,in which the material is loaded in the copper crystals.However,MD simulations data can only be obtained for specific points in the stereographic direction space;therefore,for more comprehensive understanding of the phase transition process,a feed-forward neural network was trained using MD modeling data.The trained machine learning model allowed us to construct continuous stereographic maps of phase transitions as a function of stress in the shock-compressed state of metal.Due to appearance and growth of multiple centers of new phase,the FCC-to-BCC transition leads to formation of a polycrystalline structure from the parent single crystal.展开更多
The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have bee...The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have been verified by static and shock compression experiments.Nevertheless,the dynamic formation processes underlying these phenomena remain insufficiently understood.In combination with a deep learning model,we demonstrate that diamonds form through a three-step process involving dissociation,species separation,and nucleation processes.Under shock conditions of 125 GPa and 4590 K,hydrocarbons decompose to give hydrogen and low-molecular-weight alkanes(CH_(4) and C_(2)H_(6)),which escape from the carbon chains,resulting in C/H species separation.The remaining carbon atoms without C-H bonds accumulate and nucleate to form diamond crystals.The process of diamond growth is associated with a critical nucleus size at which the dynamic energy barrier plays a key role.These dynamic processes of diamond formation provide insight into the establishment of a model for the evolution of ice giant planets.展开更多
Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads ...Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.展开更多
The thermochemical non-equilibrium phenomena encountered by hypersonic vehicles present significant challenges in their design.To investigate the thermochemical reaction flow behind shock waves,the non-equilibrium rad...The thermochemical non-equilibrium phenomena encountered by hypersonic vehicles present significant challenges in their design.To investigate the thermochemical reaction flow behind shock waves,the non-equilibrium radiation in the visible range using a shock tube was studied.Experiments were conducted with a shock velocity of 4.7 km/s,using nitrogen at a pressure of 20 Pa.To address measurement difficulties associated with weak radiation,a special square section shock tube with a side length of 380 mm was utilized.A high-speed camera characterized the shock wave’s morphology,and a spectrograph and a monochromator captured the radiation.The spectra were analyzed,and the numerical spectra were compared with experimental results,showing a close match.Temperature changes behind the shock wave were obtained and compared with numerical predictions.The findings indicate that the vibrational temperatures are overestimated,while the vibrational relaxation time is likely underestimated,due to the oversimplified portrayals of the non-equilibrium relaxation process in the models.Additionally,both experimental and simulated time-resolved profiles of radiation intensity at specific wavelengths were analyzed.The gathered data aims to enhance computational fluid dynamics codes and radiation models,improving their predictive accuracy.展开更多
The concept of local shock strength and a quantitative measure index str of local shock strength are proposed,derived from the oblique shock relation and the monotonic relationship between total pressure loss ratio an...The concept of local shock strength and a quantitative measure index str of local shock strength are proposed,derived from the oblique shock relation and the monotonic relationship between total pressure loss ratio and normal Mach number.Utilizing the high density gradient characteristic of shock waves and the oblique shock relation,a post-processing algorithm for two-dimensional flow field data is developed.The objective of the post-processing algorithm is to obtain specific shock wave location coordinates and calculate the corresponding str from flow filed data under the calibration of the oblique shock relation.Valida-tion of this post-processing algorithm is conducted using a standard model example that can be solved analytically.Combining the concept of local shock strength with the post-processing algorithm,a local shock strength quantitative mapping approach is established for the first time.This approach enables a quantitative measure and visualization of local shock strength at distinct locations,represented by color mapping on the shock structures.The approach can be applied to post-processing numerical sim-ulation data of two-dimensional flows.Applications to the intersection of two left-running oblique shock waves(straight shock waves),the bow shock in front of a cylinder(curved shock wave),and Mach reflection(mixed straight and curved shock waves)demonstrate the accuracy,and effectiveness of the mapping approach in investigating diverse shock wave phenomena.The quan-titative mapping approach of str may be a valuable tool in the design of supersonic/hypersonic vehicles and the exploration of shock wave evolution.展开更多
A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modifie...A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modified reaction acceleration method is adopted and validated in the three-dimensional model. Seven ground motions are selected and the peak ground acceleration is adjusted to 0.2 g, 0.4 g and 0.6 g. The impact of the void ratio and thickness of the porous shock absorption layer is studied, while the surrounding rock grade and tunnel depth are also investigated. The numerical results show that the porous shock absorption layer has good shock absorption performance and can effectively reduce the maximum internal force of the secondary lining, but it cannot reduce the maximum horizontal relative displacement of the secondary lining. The circumferential rubber strip in the porous shock absorption layer will reduce shock absorption performance. The results of parameter analysis indicate that the shock absorption performance of the porous shock absorption layer increases with the increase of the void ratio and thickness, and it has good shock absorption performance under different surrounding rock grades and tunnel depths.展开更多
Three-dimensional curved shock wave/boundary layer interaction with streamwise and spanwise curvatures widely exists in practical aerodynamic design.To explore the effects of composite shock curvatures on boundary lay...Three-dimensional curved shock wave/boundary layer interaction with streamwise and spanwise curvatures widely exists in practical aerodynamic design.To explore the effects of composite shock curvatures on boundary layer separation,a canonical model with a cone placed above plate was utilized as a reference.Configurations of straight,convex,and concave conical shock waves inducing the curved conical shock wave/boundary layer interactions were studied,using CFD based on Reynolds-averaged numerical simulation method.The flow structure and separation region of each case were discussed quantitively on the symmetry plane,flat plate,and plane perpendicular to flow direction,respectively.The focus of the analysis was on the characteristic patterns of separation scale variation in the streamwise and spanwise directions,which were observed to consistently change with respect to both directions with alterations in the incident shock wave shape.A simplified control volume model was established to qualitatively discuss the influence source of curved shock waves on separation scales,based on mass conservation equations.The results suggest that the curved shock wave has a holistic effect on separation,which is not solely dependent on the shock foot strength.展开更多
An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microst...An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.展开更多
Small heat shock proteins(sHSPs)act as molecular chaperones that can prevent the accumulation of damaged proteins during abiotic stress,especially heat shock,but the mechanism is not clear.To study the function of sHS...Small heat shock proteins(sHSPs)act as molecular chaperones that can prevent the accumulation of damaged proteins during abiotic stress,especially heat shock,but the mechanism is not clear.To study the function of sHSPs in Lenzites gibbosa,a common polypore in northern temperate forests that causes spongy white rot of broadleaf trees,under temperature stress,L.gibbosa mycelia were grown at 25℃ for 9 d,treated at 33℃ for 15,30,60,and 120 min before sequencing the transcriptomes.From among 32 heat shock protein(HSP)genes found in the screen of the transcriptome data,a highly expressed gene was cloned and named Lghsp17.4.RT-qPCR was used to analyze the expression of the gene Lghsp17.4 under heat shock and dye stress.Both treatments induced higher expression of Lghsp17.4 at the transcriptional level,indicating that Lghsp17.4 might function in the response to heat stress and dye degradation.We previously found that L.gibbosa generally had a heat shock reaction(HSR)during degradation of aromatic compounds,and HSPs were always produced with manganese peroxidases(MnPs)and other lignin-degrading enzymes.Therefore,we measured the activity of MnPs in L.gibbosa after 33℃ heat shock to analyze the relationship between MnPs expression and Lghsp17.4 expression.Heat shocks of 0–30 min increased MnPs activity,and the change in MnPs activity were closely positively correlated with the expression levels of Lghsp17.4 over time,indicating a potential connection and interaction between LgHSP17.4 and MnPs during the HSR in L.gibbosa.Thus,LgHSP17.4 might have a positive regulatory effect on the HSR in L.gibbosa and be a critical component of a stress resistance mechanism.展开更多
Aortic stenosis(AS)is one of the most common types of valvular heart disease in older adults,with age being significantly associated with the development of AS.The transcatheter aortic valve replacement(TAVR)procedure...Aortic stenosis(AS)is one of the most common types of valvular heart disease in older adults,with age being significantly associated with the development of AS.The transcatheter aortic valve replacement(TAVR)procedure,since it was first performed in 2002,has emerged as a preferred treatment option for patients who are at intermediate to high surgical risk due to advanced age or medical comorbidities.Older adults with severe AS may present with acute decompensated heart failure leading to cardiogenic shock(CS).Among patients 65 years and older with AS presenting for TAVR,4.1%were reportedly in acute CS.Regardless of etiology,mortality from CS itself is high(30%−50%)and increases with advancing age.TAVR for these patients could provide a definite treatment for both AS and CS.There is still limited evidence regarding the safety and efficacy of TAVR in this population,but recent studies are promising,with successful procedural results and a good recovery rate after the procedure.However,particularly for older adults,there are other factors that clinicians should consider during pre-and post-procedural status,such as patient’s goals,frailty,polypharmacy,dementia,or delirium.In this article,we reviewed current studies regarding TAVR for older adults with AS and CS,the reason for comprehensive geriatric assessment,and the introduction of appropriate geriatric assessment tools based on the Age-Friendly 4Ms framework that cardiologists can adopt in real-world practice.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12172063).
文摘The damage evolution of polycrystalline Al with helium(He)bubbles under strongly decaying shock waves is studied by molecular dynamics simulations.A new damage region is observed near the loading side of the sample,and the evolution characteristics and underlying mechanisms are elucidated.The development of damage in the new damage region begins after complete unloading of the incident shock wave and is further enhanced when the tensile stress arrives later.The damage evolution is completely controlled by the expansion-merging of He bubbles,without nucleation–growth of voids.This new damage region can be divided into two sections,each of which exhibits a unique dominant mechanism.The damage in the section closer to the loading side is due to the reverse velocity gradient formed after complete unloading of the incident shock wave,depending on the rate of decrease and the amplitude of the initial peak pressure.A high initial peak pressure that can lead to melting of material near the loading side is a necessary condition for the formation of the new damage region,since a significant reverse velocity gradient can only be established if melting occurs.The dominant mechanism in the section distant from the loading side is the action of tensile stress,associated with the profile of the incident shock wave upon reaching the free surface,which determines the material phase near the free surface.Moreover,the presence of He bubbles is another critical factor for formation of the new damage region,which does not occur in pure Al samples.
基金supported by the National Natural Science Foundation of China(No.12372233)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.25GH01020005)the“111 Project”of China(No.B17037)。
文摘As a multidisciplinary phenomenon,panel aeroelasticity in shock-dominated flow is featured by two primary interactions:Fluid-Structure Interactions(FSIs)and Shock-Boundary Layer Interactions(SBLIs).The former raises structural concerns,and the latter is of aerodynamic interest.Thus,panel aeroelasticity in shock-dominated flow represents a vital topic for the development and optimization of supersonic vehicles and propulsion systems.This review systematically summarizes recent advances in the methodologies applied to capture structural and fluid dynamics,including theoretical models,numerical simulations,and wind tunnel experiments.The application of data-driven modal decomposition,an advanced technique to extract physically crucial features,on the topic is introduced.From the perspective of FSIs,the distinctive aeroelastic behaviors in shock-dominated flow,including hysteresis phenomena and nonlinear responses,are highlighted.From the perspective of SBLIs,the modifications in their spatial and temporal characteristics imposed by the aeroelastic responses are emphasized.Motivated by the interaction between the shock waves and structural response,different strategies have been proposed to implement aeroelastic suppression and shock control,which have the potential to enhance structural safety and aerodynamic performance in the next generation of high-speed flight vehicles.
基金Science and Technology Planning Project of Guangdong Province,2023B1212060048,Xiande Xie。
文摘Recovered samples of Jilin H5 chondrite experimentally shocked to 12-133 GPa were studied to explore the behavior of opaque minerals under shock loading using SEM-EDS,Raman spectroscopy,and TIMA.The following results were obtained.Firstly,at pressures lower than 53GPa,the opaque minerals still keep the unmelted state,while at 78 GPa and higher,FeNi metal and troilite form eutectic intergrowths occurring as disorderly fine veinlets filling the shock-induced fractures in silicate minerals.Secondly,single kamacite grains still maintain their contour at 12 GPa,but a part of brittle troilite grains was fragmented and squeezed into the shock-induced fractures within kamacite grains.At53 and 133 GPa,many more troilite fragments are poured in the kamacite interior to form disordered hybrid aggregates or to form squiggly strips,respectively.Similar phenomena are observed within single troilite grains,but the mineral squeezed into troilite grains is kamacite.Thirdly,chromite is a hard and refractory oxide mineral.When the shock pressure rises step by step from 12 to 133 GPa,the shock effect of chromite is only fragmentation.Its grain size decreases from tens of um at 53 GPa to a few um at 133 GPa.And,fourthly,native copper exhibits distinct redistribution behavior at high temperature.In Jilin samples shock-loaded to 12 GPa,copper initially located at troilite-kamacite interfaces partially transferred into small troilite grains containing fine FeNi particles.At 53 and 133 GPa,native copper preferentially transferred into larger troilite grains containing more particles of eutectic FeNi metal.
基金supported by the National Key R&D Program of China(Grant No.2021YFB3802303)the National Natural Science Foundation of China(Grant Nos.12302493 and 12525211).
文摘The manipulation of intense shock waves to either attenuate or enhance damage has long been a key goal in the domain of impact dynamics.Effective methods for such manipulation,however,remain elusive owing to the wide spectrum and irreversible destructive nature of intense shock waves.This work proposes a novel approach for actively controlling intense shock waves in solids,inspired by the principles of optical and explosive lenses.Specifically,by designing a shock wave convex lens composed of a low-shock-impedance material embedded in a high-shock-impedance matrix,we prove the feasibility of transforming a planar shock into a spherically converging shock.This is based on oblique shock theory,according to which shock waves pass through an oblique interface and then undergo deflection.Both experimental and simulation results demonstrate that,as expected,the obtained local spherical shock wave has a wavefront that is nearly perfectly spherical and uniform in pressure.Thus,this work proves the possibility of generating spherical shock waves using plate-impact experiments and highlights the potential of further exploration of the manipulation of shock waves in solids.It also contributes an innovative perspective for both armor penetration technologies and shock wave mitigation strategies.
基金This work used Expanse systems at UCSD through an allocation[PHY240089]from the Advanced Cyberinfrastructure Coordination Ecosystem:Services&Support(ACCESS)programsupported by U.S.National Science Foundation(Grant Nos.2138259,2138286,2138307,2137603 and 2138296).
文摘We present a numerical framework for simulating viscous compressible flows in the presence of solid particles with large size ratios.The volume-filtered Navier-Stokes equations are discretized using a class of high-order low-dissipative finite difference operators with energy-preserving properties.No-slip,adiabatic boundary conditions are enforced at the surface of large particles(with diameters significantly larger than the local grid spacing)using a ghost-point immersed boundary method.Two-way coupling between the gas phase and small particles(with diameters proportional to the grid spacing)is accounted for through volumetric source terms for interphase momentum and energy exchange.A simple and efficient approach for collision detection between small and large particles is proposed.The framework is applied to simulations of planar shocks interacting with bidisperse distributions of particles with size ratios of approximately thirty.Particle dispersion and size segregation are reported and a simple analytical model for size segregation is proposed.
基金supported by National Natural Science Foundation of China (Nos.52264006,52364004,and 52464005)the Guizhou Provincial Science and Technology Foundation (No.GCC[2022]005-1)。
文摘Investigating the damage evolution of surrounding rock under thermal shock cycles is crucial for ensuring the stability of engineering rock masses.This study performed Brazilian splitting tests on granite specimens under varying temperature and cycle conditions,employing acoustic emission monitoring,digital image correlation,and three-dimensional scanning technology.A systematic analysis was conducted on the patterns of damage evolution,failure precursor,and response mechanisms under combined thermal and cyclic loading.Experimental results show that both P-wave velocity and tensile strength degrade significantly with increasing temperature and cycle count,with temperature having a more pronounced effect than cycle count.Notably,damage evolution exhibits a dual-threshold behavior in which degradation accelerates markedly above 400℃ and stabilizes after 5 thermal cycles.Fracture surfaces evolve from initially planar to rugged morphologies,with peak-valley height differences at 600℃ being approximately three times greater than those at 200℃.Furthermore,based on acoustic emission energy entropy analysis,we introduce a novel failure precursor indicator where the sustained increase and critical surge in average entropy serve as reliable early-warning signals for impending rock failure.These findings establish a solid theoretical basis and practical methodology for damage assessment and instability early-warning systems in high-temperature rock engineering.
基金funded by the Research Fund of National Key Laboratory of Aerospace Physics in Fluids,grant number 2024-APF-KFZD-01Guangdong Basic and Applied Basic Research Foundation,grant number 2025A1515012081+1 种基金National Natural Science Foundation of China,grant number 12002193Shandong Provincial Natural Science Foundation,China,grant number ZR2019QA018.
文摘For hypersonic air-breathing vehicles,the V-shaped leading edges(VSLEs)of supersonic combustion ramjet(scramjet)inlets experience complex shock interactions and intense aerodynamic loads.This paper provides a comprehensive review of flow characteristics at the crotch of VSLEs,with particular focus on the transition of shock interaction types and the variation of wall heat flux under different freestream Mach numbers and geometric configurations.The mechanisms governing shock transition,unsteady oscillations,hysteresis,and three-dimensional effects in VSLE flows are first examined.Subsequently,thermal protection strategies aimed at mitigating extreme heating loads are reviewed,emphasizing their relevance to practical engineering applications.Special attention is given to recent studies addressing thermochemical nonequilibrium effects on VSLE shock interactions,and the limitations of current research are critically assessed.Finally,perspectives for future investigations into hypersonic VSLE shock interactions are outlined,highlighting opportunities for advancing design and thermal management strategies.
基金financial support from NSF ExpandQISE program.The synthesis of tellurene was supported by NSF under grant no.CMMI-2046936supports from Purdue Research Foundation.
文摘Tellurene,a chiral chain semiconductor with a narrow bandgap and exceptional strain sensitivity,emerges as a pivotal material for tailoring electronic and optoelectronic properties via strain engineering.This study elucidates the fundamental mechanisms of ultrafast laser shock imprinting(LSI)in two-dimensional tellurium(Te),establishing a direct relationship between strain field orientation,mold topology,and anisotropic structural evolution.This is the first demonstration of ultrafast LSI on chiral chain Te unveiling orientation-sensitive dislocation networks.By applying controlled strain fields parallel or transverse to Te’s helical chains,we uncover two distinct deformation regimes.Strain aligned parallel to the chain’s direction induces gliding and rotation governed by weak interchain interactions,preserving covalent intrachain bonds and vibrational modes.In contrast,transverse strain drives shear-mediated multimodal deformations—tensile stretching,compression,and bending—resulting in significant lattice distortions and electronic property modulation.We discovered the critical role of mold topology on deformation:sharp-edged gratings generate localized shear forces surpassing those from homogeneous strain fields via smooth CD molds,triggering dislocation tangle formation,lattice reorientation,and inhomogeneous plastic deformation.Asymmetrical strain configurations enable localized structural transformations while retaining single-crystal integrity in adjacent regions—a balance essential for functional device integration.These insights position LSI as a precision tool for nanoscale strain engineering,capable of sculpting 2D material morphologies without compromising crystallinity.By bridging ultrafast mechanics with chiral chain material science,this work advances the design of strain-tunable devices for next-generation electronics and optoelectronics,while establishing a universal framework for manipulating anisotropic 2D systems under extreme strain rates.This work discovered crystallographic orientation-dependent deformation mechanisms in 2D Te,linking parallel strain to chain gliding and transverse strain to shear-driven multimodal distortion.It demonstrates mold geometry as a critical lever for strain localization and dislocation dynamics,with sharp-edged gratings enabling unprecedented control over lattice reorientation.Crucially,the identification of strain field conditions that reconcile severe plastic deformation with single-crystal retention offers a pathway to functional nanostructure fabrication,redefining LSI’s potential in ultrafast strain engineering of chiral chain materials.
文摘Stator vanes especially vane suction sides of transonic turbines are subjected to high frequency excitation forces under many circumstances,and thus are exposed to the risk of high cycle fatigue.Therefore,it is necessary to reveal the flow mechanism of this kind of excitations for potential prevention measures.In this paper,the traveling shock phenomenon in the transonic turbine stator/rotor gap is observed and the concept of‘Inter-Row Traveling Shock(IRTS)'is proposed through the unsteady Reynolds-Averaged Navier-Stokes(RANS)simulation of a typical highlyloaded transonic turbine stage.The characteristics of an IRTS were described and summarized in aspects of unsteady shock wave system,aerodynamic characteristics and motion.The probable forming mechanism of an IRTS was explained through a theoretical model and it was validated through correct prediction of the flow state parameter change across the IRTS.Since IRTSs would strike onto vane suction sides,the pressure oscillation dynamic modes on vane suction side corresponding to the characteristic frequencies associated with IRTS were extracted through Dynamic Mode Decomposition(DMD),from which the way and extent of the IRTS influences on vane aerodynamic excitation were revealed and evaluated.Over 82%pressure oscillation energy on vane suction side could be brought by the IRTS sweeping along with blade rotation.
基金supported by grants from the National Natural Science Foundation of China(No.81981340417 to LiSu)Natural Science Foundation of Jiangsu Province Outstanding Youth Fund(No.BK20240134 to Yuanqing Gao).
文摘Hemorrhagic shock(HS)is a leading cause of death worldwide,particularly within the first 24 h post-injury.Current treatments are limited,especially in low-resource settings.Therapeutic hypothermia(TH)offers potential benefits by reducing metabolic demands and protecting organs,but its application in HS is challenged by cooling difficulties and side effects.This study introduces a novel nasal gel formulation of N6-cyclohexyladenosine(CHA),an adenosine A1 receptor agonist,designed to enhance brain delivery while minimizing peripheral side effects.In a mouse model of HS,administration of CHA nasal gel significantly improved survival rates,reduced metabolic rates,and protected major organs without worsening coagulopathy.Metabolomics analysis revealed a shift towards fatty acid oxidation and increased antioxidant capacity.These findings demonstrate that CHA nasal gel effectively induces TH,offering a safe and innovative treatment strategy for HS,particularly in resource-limited environments.
基金founded by the Ministry of Science and Higher Education of the Russian Federation,State assignments for research,registration No.1024032600084-8-1.3.2Study of the grain growth and the formation of polycrystalline structure as a result of phase transition(Section 6)was founded by the Russian Science Foundation,Project No.24-71-00078+3 种基金https://rscf.ru/en/project/24-71-00078/(accessed on 01 December 2025).Study of the orientation dependence of the phase transition of aluminum in Section 3 was founded by the Russian Science Foundation,Project No.24-19-00684https://rscf.ru/en/project/24-19-00684/(accessed on 01 December 2025).
文摘It is well known that aluminum and copper exhibit structural phase transformations in quasi-static and dynamic measurements,including shock wave loading.However,the dependence of phase transformations in a wide range of crystallographic directions of shock loading has not been revealed.In this work,we calculated the shock Hugoniot for aluminum and copper in different crystallographic directions([100],[110],[111],[112],[102],[114],[123],[134],[221]and[401])of shock compression using molecular dynamics(MD)simulations.The results showed a high pressure(>160 GPa for Cu and>40 GPa for Al)of the FCC-to-BCC transition.In copper,different characteristics of the phase transition are observed depending on the loading direction with the[100]compression direction being the weakest.The FCC-to-BCC transition for copper is in the range of 150–220 GPa,which is consistent with the existing experimental data.Due to the high transition pressure,the BCC phase transition in copper competes with melting.In aluminum,the FCC-to-BCC transition is observed for all studied directions at pressures between 40 and 50 GPa far beyond the melting.In all considered cases we observe the coexistence of HCP and BCC phases during the FCC-to-BCC transition,which is consistent with the experimental data and atomistic calculations;this HCP phase forms in the course of accompanying plastic deformation with dislocation activity in the parent FCC phase.The plasticity incipience is also anisotropic in bothmetals,which is due to the difference in the projections of stress on the slip plane for different orientations of the FCC crystal.MD modeling results demonstrate a strong dependence of the FCC-to-BCC transition on the crystallographic direction,in which the material is loaded in the copper crystals.However,MD simulations data can only be obtained for specific points in the stereographic direction space;therefore,for more comprehensive understanding of the phase transition process,a feed-forward neural network was trained using MD modeling data.The trained machine learning model allowed us to construct continuous stereographic maps of phase transitions as a function of stress in the shock-compressed state of metal.Due to appearance and growth of multiple centers of new phase,the FCC-to-BCC transition leads to formation of a polycrystalline structure from the parent single crystal.
基金supported by the National Natural Science Foundation of China(Grant Nos.12534013,12047561,and 12104507)the Science and Technology Innovation Program of Hunan Province(Grant Nos.2025ZYJ001 and 2021RC4026)the National University of Defense Technology Research Fund Project.
文摘The accumulation and circulation of carbon and hydrogen contribute to the chemical evolution of ice giant planets.Species separation and diamond precipitation have been reported in carbon-hydrogen systems and have been verified by static and shock compression experiments.Nevertheless,the dynamic formation processes underlying these phenomena remain insufficiently understood.In combination with a deep learning model,we demonstrate that diamonds form through a three-step process involving dissociation,species separation,and nucleation processes.Under shock conditions of 125 GPa and 4590 K,hydrocarbons decompose to give hydrogen and low-molecular-weight alkanes(CH_(4) and C_(2)H_(6)),which escape from the carbon chains,resulting in C/H species separation.The remaining carbon atoms without C-H bonds accumulate and nucleate to form diamond crystals.The process of diamond growth is associated with a critical nucleus size at which the dynamic energy barrier plays a key role.These dynamic processes of diamond formation provide insight into the establishment of a model for the evolution of ice giant planets.
基金financially supported by National Natural Science Foundation of China(Grant Nos.52378401,52278504)the Fundamental Research Funds for the Central Universities(Grant No.30922010918)。
文摘Traffic engineering such as tunnels in various altitudinal gradient zone are at risk of accidental explosion,which can damage personnel and equipment.Accurate prediction of the distribution pattern of explosive loads and shock wave propagation process in semi-enclosed structures at various altitude environment is key research focus in the fields of explosion shock and fluid dynamics.The effect of altitude on the propagation of shock waves in tunnels was investigated by conducting explosion test and numerical simulation.Based on the experimental and numerical simulation results,a prediction model for the attenuation of the peak overpressure of tunnel shock waves at different altitudes was established.The results showed that the peak overpressure decreased at the same measurement points in the tunnel entrance under the high altitude condition.In contrast,an increase in altitude accelerated the propagation speed of the shock wave in the tunnel.The average error between the peak shock wave overpressure obtained using the overpressure prediction formula and the measured test data was less than15%,the average error between the propagation velocity of shock waves predicted values and the test data is less than 10%.The method can effectively predict the overpressure attenuation of blast wave in tunnel at various altitudes.
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grant No.2021B0909060004)the National Natural Science Foundation of China(Grant Nos.12072355 and 92271117)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620202).
文摘The thermochemical non-equilibrium phenomena encountered by hypersonic vehicles present significant challenges in their design.To investigate the thermochemical reaction flow behind shock waves,the non-equilibrium radiation in the visible range using a shock tube was studied.Experiments were conducted with a shock velocity of 4.7 km/s,using nitrogen at a pressure of 20 Pa.To address measurement difficulties associated with weak radiation,a special square section shock tube with a side length of 380 mm was utilized.A high-speed camera characterized the shock wave’s morphology,and a spectrograph and a monochromator captured the radiation.The spectra were analyzed,and the numerical spectra were compared with experimental results,showing a close match.Temperature changes behind the shock wave were obtained and compared with numerical predictions.The findings indicate that the vibrational temperatures are overestimated,while the vibrational relaxation time is likely underestimated,due to the oversimplified portrayals of the non-equilibrium relaxation process in the models.Additionally,both experimental and simulated time-resolved profiles of radiation intensity at specific wavelengths were analyzed.The gathered data aims to enhance computational fluid dynamics codes and radiation models,improving their predictive accuracy.
基金supported by the National Natural Science Foundation of China(Grant No.12372233)the Fund of NPU-Duke China Seed Program(Grant No.119003067)the“111 Project”of China(Grant No.B17037-106).
文摘The concept of local shock strength and a quantitative measure index str of local shock strength are proposed,derived from the oblique shock relation and the monotonic relationship between total pressure loss ratio and normal Mach number.Utilizing the high density gradient characteristic of shock waves and the oblique shock relation,a post-processing algorithm for two-dimensional flow field data is developed.The objective of the post-processing algorithm is to obtain specific shock wave location coordinates and calculate the corresponding str from flow filed data under the calibration of the oblique shock relation.Valida-tion of this post-processing algorithm is conducted using a standard model example that can be solved analytically.Combining the concept of local shock strength with the post-processing algorithm,a local shock strength quantitative mapping approach is established for the first time.This approach enables a quantitative measure and visualization of local shock strength at distinct locations,represented by color mapping on the shock structures.The approach can be applied to post-processing numerical sim-ulation data of two-dimensional flows.Applications to the intersection of two left-running oblique shock waves(straight shock waves),the bow shock in front of a cylinder(curved shock wave),and Mach reflection(mixed straight and curved shock waves)demonstrate the accuracy,and effectiveness of the mapping approach in investigating diverse shock wave phenomena.The quan-titative mapping approach of str may be a valuable tool in the design of supersonic/hypersonic vehicles and the exploration of shock wave evolution.
基金Science and Technology Plan Project of Xizang Autonomous Region,China under Grant No.XZ202501YD0007。
文摘A novel porous shock absorption layer is put forward in this study, and the shock absorption performance of the porous shock absorption layer is evaluated based on three-dimensional pseudo-static analysis. The modified reaction acceleration method is adopted and validated in the three-dimensional model. Seven ground motions are selected and the peak ground acceleration is adjusted to 0.2 g, 0.4 g and 0.6 g. The impact of the void ratio and thickness of the porous shock absorption layer is studied, while the surrounding rock grade and tunnel depth are also investigated. The numerical results show that the porous shock absorption layer has good shock absorption performance and can effectively reduce the maximum internal force of the secondary lining, but it cannot reduce the maximum horizontal relative displacement of the secondary lining. The circumferential rubber strip in the porous shock absorption layer will reduce shock absorption performance. The results of parameter analysis indicate that the shock absorption performance of the porous shock absorption layer increases with the increase of the void ratio and thickness, and it has good shock absorption performance under different surrounding rock grades and tunnel depths.
基金the support of the National Natural Science Foundation of China(Nos.12372295,U21B6003,U20A2069,12302389 and 123B2037)。
文摘Three-dimensional curved shock wave/boundary layer interaction with streamwise and spanwise curvatures widely exists in practical aerodynamic design.To explore the effects of composite shock curvatures on boundary layer separation,a canonical model with a cone placed above plate was utilized as a reference.Configurations of straight,convex,and concave conical shock waves inducing the curved conical shock wave/boundary layer interactions were studied,using CFD based on Reynolds-averaged numerical simulation method.The flow structure and separation region of each case were discussed quantitively on the symmetry plane,flat plate,and plane perpendicular to flow direction,respectively.The focus of the analysis was on the characteristic patterns of separation scale variation in the streamwise and spanwise directions,which were observed to consistently change with respect to both directions with alterations in the incident shock wave shape.A simplified control volume model was established to qualitatively discuss the influence source of curved shock waves on separation scales,based on mass conservation equations.The results suggest that the curved shock wave has a holistic effect on separation,which is not solely dependent on the shock foot strength.
基金supported by the Key Project of the National Natural Science Foundation of China(Grant No.U21A2058)the Hebei Guoliang New Materials Co.,Ltd.(Grant No.22150239J).
文摘An experiment was conducted to assess the impact of fused calcia-stabilized zirconia micro-powder on the thermal shock behavior of magnesia–spinel refractories.The effects of calcia-stabilized zirconia on the microstructure evolution and properties of magnesia–spinel refractories were characterized by the high-temperature elastic modulus,thermal shock damage resistance parameters,retainment of elastic modulus after thermal shock,and scanning electron microscopy.The results indicated that the incorporation of calcia-stabilized zirconia improved the thermomechanical properties and thermal shock behavior of magnesia–spinel specimens.The hot modulus of rupture of magnesia–spinel specimens increased by 2.5-fold due to the incorporation of calcia-stabilized zirconia micro-powder.The presence of a martensitic phase transformation in partially unstable ZrO2 and thermal mismatches among various phases contributed to a controlled formation of microcracks.And the pinning effect caused by the calcia-stabilized zirconia particles surrounding the grain boundaries played a crucial role in preventing the propagation of microcracks.This phenomenon significantly bolstered the thermal shock stability of magnesia–spinel refractories,consequently prolonging their service life.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.:2572016AA04)Northeast Asia Biodiversity Research Center Double First class Funds(Grant No.:411146030416 and No.:411147021003).
文摘Small heat shock proteins(sHSPs)act as molecular chaperones that can prevent the accumulation of damaged proteins during abiotic stress,especially heat shock,but the mechanism is not clear.To study the function of sHSPs in Lenzites gibbosa,a common polypore in northern temperate forests that causes spongy white rot of broadleaf trees,under temperature stress,L.gibbosa mycelia were grown at 25℃ for 9 d,treated at 33℃ for 15,30,60,and 120 min before sequencing the transcriptomes.From among 32 heat shock protein(HSP)genes found in the screen of the transcriptome data,a highly expressed gene was cloned and named Lghsp17.4.RT-qPCR was used to analyze the expression of the gene Lghsp17.4 under heat shock and dye stress.Both treatments induced higher expression of Lghsp17.4 at the transcriptional level,indicating that Lghsp17.4 might function in the response to heat stress and dye degradation.We previously found that L.gibbosa generally had a heat shock reaction(HSR)during degradation of aromatic compounds,and HSPs were always produced with manganese peroxidases(MnPs)and other lignin-degrading enzymes.Therefore,we measured the activity of MnPs in L.gibbosa after 33℃ heat shock to analyze the relationship between MnPs expression and Lghsp17.4 expression.Heat shocks of 0–30 min increased MnPs activity,and the change in MnPs activity were closely positively correlated with the expression levels of Lghsp17.4 over time,indicating a potential connection and interaction between LgHSP17.4 and MnPs during the HSR in L.gibbosa.Thus,LgHSP17.4 might have a positive regulatory effect on the HSR in L.gibbosa and be a critical component of a stress resistance mechanism.
文摘Aortic stenosis(AS)is one of the most common types of valvular heart disease in older adults,with age being significantly associated with the development of AS.The transcatheter aortic valve replacement(TAVR)procedure,since it was first performed in 2002,has emerged as a preferred treatment option for patients who are at intermediate to high surgical risk due to advanced age or medical comorbidities.Older adults with severe AS may present with acute decompensated heart failure leading to cardiogenic shock(CS).Among patients 65 years and older with AS presenting for TAVR,4.1%were reportedly in acute CS.Regardless of etiology,mortality from CS itself is high(30%−50%)and increases with advancing age.TAVR for these patients could provide a definite treatment for both AS and CS.There is still limited evidence regarding the safety and efficacy of TAVR in this population,but recent studies are promising,with successful procedural results and a good recovery rate after the procedure.However,particularly for older adults,there are other factors that clinicians should consider during pre-and post-procedural status,such as patient’s goals,frailty,polypharmacy,dementia,or delirium.In this article,we reviewed current studies regarding TAVR for older adults with AS and CS,the reason for comprehensive geriatric assessment,and the introduction of appropriate geriatric assessment tools based on the Age-Friendly 4Ms framework that cardiologists can adopt in real-world practice.
