Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materi...Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.展开更多
In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperat...In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperature(T_(c))of 1D superconductors is low.In this work,we theoretically investigate the possible high T_(c) superconductivity of(5,5)carbon nanotube(CNT).The pristine(5,5)CNT is a Dirac semimetal and can be modulated into a semiconductor by full hydrogenation.Interestingly,by further hole doping,it can be regulated into a metallic state with the sp^(3)-hybridized σ electrons metalized,and a giant Kohn anomaly appears in the optical phonons.The two factors together enhance the electron–phonon coupling,and lead to high-T_(c) superconductivity.When the hole doping concentration of hydrogenated-(5,5)CNT is 2.5 hole/cell,the calculated T_(c) is 82.3 K,exceeding the boiling point of liquid nitrogen.Therefore,the predicted hole-doped hydrogenated-(5,5)CNT provides a new platform for 1D high-T_(c) superconductivity and may have potential applications in 1D nanodevices.展开更多
Spikelet filling characteristics in early-season rice in southern China may be distinctive due to its exposure to high temperatures during the ripening period.However,limited information is currently available on thes...Spikelet filling characteristics in early-season rice in southern China may be distinctive due to its exposure to high temperatures during the ripening period.However,limited information is currently available on these characteristics.This study aimed to characterize spikelet filling in early-season rice and identify the key factors contributing to its improvement.Field experiments were conducted over two years(2021 and 2022)to mainly investigate the proportions of fully-filled,partially-filled,and empty spikelets,along with the biomass-fertilized spikelet ratio and harvest index,in 11 early-season rice varieties.The results revealed significant varietal variation in spikelet filling,with the proportion of fully-filled spikelets ranging from 60.6%to 81.1%in 2021 and from 66.3%to 79.2%in 2022.Among the 11 varieties,Liangyou 42,Lingliangyou 942,and Liangyou 287 exhibited relatively superior performance in spikelet filling.Linear regression revealed that,although a significant negative relationship existed between the proportion of fully-filled spikelets and both partially-filled and empty spikelets,the relationship with partially-filled spikelets was stronger.Additionally,the proportion of fully-filled spikelets showed a significant positive relationship with the harvest index but not with the biomass-fertilized spikelet ratio.These findings indicate that increasing the harvest index and reducing the occurrence of partially-filled grains are essential strategies for improving spikelet filling in early-season rice.展开更多
The demand for sensors capable of operating in extreme environment of the fields,such as aerospace vehicles,aeroengines and fire protection,is rapidly increasing.However,developing flexible ceramic fibrous pressure se...The demand for sensors capable of operating in extreme environment of the fields,such as aerospace vehicles,aeroengines and fire protection,is rapidly increasing.However,developing flexible ceramic fibrous pressure sensors that combine high temperature stability with robust mechanical properties remains a significant challenge.Herein,through precise multi-scale process control,high-strength(2.1 MPa)TiC-SiC flexible fibrous membrane is successfully fabricated.The membrane exhibits exceptional thermal resistance(2000℃)and long–term thermal stability(1800℃ for 5 h)in the inert atmosphere.Meanwhile,the TiC-SiC fibrous membrane shows excellent oxidation resistance and still achieves strength of 1.8 MPa after being oxidized at 1200℃ for 1 h in air.Remarkably,TiC-SiC fibrous membrane withstands a load of approximately 1400 times its own weight and the ablation of butane flame(~1300℃)for at least 1 h without breaking.Notably,after heat treatment at 1800℃ for 5 h in an argon atmosphere,the TiC-SiC fibrous membrane even sustains pressure–sensing performance for up to 300 cycles.The membrane exhibits stable resistivity up to 900℃ and shows sensing stability under butane flame.The results of this work provide an effective and feasible solution to fill the research gap of flexible fibrous sensors for extreme environments.展开更多
Thermal-mechanical damage and deformation at the interface between shotcrete linings and the surrounding rock of tunnels under high-temperature and variable-temperature conditions are critical to the safe construction...Thermal-mechanical damage and deformation at the interface between shotcrete linings and the surrounding rock of tunnels under high-temperature and variable-temperature conditions are critical to the safe construction and operation of tunnel engineering.This study investigated the thermo-mechanical damage behavior of the composite interface between alkali-resistant glass fiber-reinforced concrete(ARGFRC)and granite,focusing on a plateau railway tunnel.Laboratory triaxial tests,laser scanning,XRD analysis,numerical simulations,and theoretical analyses were employed to investigate how different initial curing temperatures and joint roughness coefficient(JRC)influence interfacial damage behavior.The results indicate that an increase in interface roughness exacerbates the structural damage at the interface.At a JRC of 19.9 and a temperature of 70℃,crack initiation in granite was notably restrained when the confining pressure rose from 7 MPa to 10 MPa.Roughness-induced stress distribution at the interface was notably altered,although this effect became less pronounced under high confining pressure conditions.Additionally,during high-temperature curing,thermal stress concentration at the tips of micro-convex protrusions on the granite surface induced microcracks in the adjacent ARGFRC matrix,followed by deformation.These findings provide practical guidelines for designing concrete support systems to ensure tunnel structural safety in high-altitude regions with harsh thermal environments.展开更多
During geothermal resource exploitation,the potential deterioration of mechanical properties in high-temperature granite subjected to cooling poses a significant safety concern.To address this,the present study invest...During geothermal resource exploitation,the potential deterioration of mechanical properties in high-temperature granite subjected to cooling poses a significant safety concern.To address this,the present study investigates the coupled thermo-mechanical behavior of granite during heating and cooling through a combination of laboratory tests and finite difference method analysis.Initial investigations involve X-ray diffraction,thermal expansion test,thermogravimetric analysis,and uniaxial compression test.Results show the significant variations of granite properties under different thermal conditions,attributed to temperature gradients,water evaporation,and mineral phase transitions.Subsequently,a model considering temperature-dependent parameters and real-time cooling rates was employed to simulate linear heating and nonlinear cooling processes.Simulation results indicate that the thermal cracking predominantly occurs during the heating stage,with tensile failure as the primary mode.Additionally,a faster real-time cooling rate at higher temperatures intensifies the thermal cracking behavior in granite.This study effectively elucidates the thermomechanical coupling behavior of granite during heating and cooling processes,providing insights into the mechanisms of mechanical property changes with rising or decreasing temperatures.展开更多
The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical sim...The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.展开更多
High temperature stress (HT) significantly reduces maize yield by impairing starch accumulation in kernels.However,the mechanism by which HT affects starch synthesis remains controversial-whether through reduced assim...High temperature stress (HT) significantly reduces maize yield by impairing starch accumulation in kernels.However,the mechanism by which HT affects starch synthesis remains controversial-whether through reduced assimilate supply or direct inhibition on kernel metabolism.To clarify these mechanisms,a heat-sensitive maize hybrid,Xianyu 335 (XY),was exposed to 30℃/20℃ (maximum/minimum temperature,control) and 40℃/30℃ for seven consecutive days during the seed setting stage.Synchronous pollination (SP),apical pollination (AP),and shading treatments were applied to manipulate the inherent source–sink ratio in maize plants.Results showed that apical kernel weight decreased by 11.9%under 40℃ in the SP treatment.The ^(13)C content,starch accumulation,and cell-wall invertase (CWIN) activity also declined by 15.9,36.7,and 16.4%,respectively,under HT.In the shading treatment,40℃/30℃ caused even greater reductions in^(13)C content,starch accumulation,and CWIN activity due to diminished assimilate supply.Conversely,in the AP treatment,starch content and CWIN activity increased by 22.0 and 18.5%,respectively,under 40℃/30℃,resulting in kernel weight and ^(13)C content similar to those in SP and shading treatments regardless of temperature.Consistent with apical kernels under AP,HT did not negatively affect middle kernels in either SP or shading treatments,as kernel weight and starch content remained unchanged under HT.Although all kernels were exposed to the same HT or control environment,their responses varied a lot.The impaired starch synthesis in apical kernels under HT was rescued by increasing carbon supply via AP treatment.The contrasting performance among middle kernels,apical kernels under AP,and apical kernels under SP or shading indicates that reduced carbon supply is a critical factor underlying inhibited starch accumulation.Our findings provide a theoretical basis for further understanding kernel abortion under HT.展开更多
Rechargeable Zn/Sn-air batteries have received considerable attention as promising energy storage devices.However,the electrochemical performance of these batteries is significantly constrained by the sluggish electro...Rechargeable Zn/Sn-air batteries have received considerable attention as promising energy storage devices.However,the electrochemical performance of these batteries is significantly constrained by the sluggish electrocatalytic reaction kinetics at the cathode.The integration of light energy into Zn/Sn-air batteries is a promising strategy for enhancing their performance.However,the photothermal and photoelectric effects generate heat in the battery under prolonged solar irradiation,leading to air cathode instability.This paper presents the first design and synthesis of Ni_(2)-1,5-diamino-4,8-dihydroxyanthraquinone(Ni_(2)DDA),an electronically conductiveπ-d conjugated metal-organic framework(MOF).Ni_(2)DDA exhibits both photoelectric and photothermal effects,with an optical band gap of~1.14 eV.Under illumination,Ni_(2)DDA achieves excellent oxygen evolution reaction performance(with an overpotential of 245 mV vs.reversible hydrogen electrode at 10 mA cm^(−2))and photothermal stability.These properties result from the synergy between the photoelectric and photothermal effects of Ni_(2)DDA.Upon integration into Zn/Sn-air batteries,Ni_(2)DDA ensures excellent cycling stability under light and exhibits remarkable performance in high-temperature environments up to 80℃.This study experimentally confirms the stable operation of photo-assisted Zn/Sn-air batteries under high-temperature conditions for the first time and provides novel insights into the application of electronically conductive MOFs in photoelectrocatalysis and photothermal catalysis.展开更多
Spaceborne optomechanical systems face the dual challenges of extreme thermal disturbances and millikelvin-level temperature control precision during orbital operations,demanding robust control strategies.To address t...Spaceborne optomechanical systems face the dual challenges of extreme thermal disturbances and millikelvin-level temperature control precision during orbital operations,demanding robust control strategies.To address the performance limitations of conventional fixed-parameter active disturbance rejection control(ADRC)under complex operating conditions,this work proposes a Qlearning-enhanced adaptive ADRC framework.A thermal-transfer model incorporating multisource disturbances(solar radiation,structural conduction,and contact thermal resistance)is established,coupled with a reinforcement learning-driven parameter optimization mechanism.The ε-greedy policy dynamically adjusts observer bandwidth(ω_(o)∈[0.01,0.2])and controller bandwidth(ω_(c)∈[0.01,0.1])to enable real-time estimation and compensation of total disturbances.Simulation results demonstrate significant improvements over fixed-parameter ADRC and a self-tuning internal model control proportional-integral(SIMC-PI)controller:31.3% and 15.4% reduction in settling time during setpoint responses,respectively;21.8% lower integral absolute error(IAE)than the fixed-parameter ADRC during setpoint step responses;12.7% and 52.5% enhancement in control precision over conventional fixed-parameter and SIMC-PI controllers,respectively,under±10 K periodic and step thermal disturbances.Monte Carlo robustness tests reveal smaller fluctuation ranges of IAE,settling time,and overshoot under±5% parameter perturbations.This methodology establishes a new paradigm for millikelvin-level thermal control in space optical payloads.展开更多
The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The micr...The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The microstructure analysis revealed that the tungsten phase in 95W-HEAs exhibited a nearly spherical morphology in the HEA binder matrix and the formation of a Cr−Mn oxide mixed phase was observed.The sintering temperature exerted a significant influence on the relative density,grain size,W−W contiguity,and mechanical properties of the alloys.The optimal performance was achieved when sintering at 1450℃,yielding a relative density of 96.61%,a W−W contiguity of 0.528,an average grain size of 18.97μm,a compressive strength of 2234.82 MPa,and a hardness of HV 400.6.The activation energy for the diffusion of tungsten in the liquid phase formed by HEA binder was calculated to be 354.514 kJ/mol,highlighting its role in controlling grain growth.展开更多
This study investigates the thermo–mechanical behavior of C40 concrete and reinforced concrete subjected to elevated temperatures up to 700℃by integrating experimental testing and advanced numerical modeling.A tempe...This study investigates the thermo–mechanical behavior of C40 concrete and reinforced concrete subjected to elevated temperatures up to 700℃by integrating experimental testing and advanced numerical modeling.A temperature-indexed Concrete Damage Plasticity(CDP)framework incorporating bond–slip effects was developed in Abaqus to capture both global stress–strain responses and localized damage evolution.Uniaxial compression tests on thermally exposed cylinders provided residual strength data and failure observations for model calibration and validation.Results demonstrated a distinct two-stage degradation regime:moderate stiffness and strength reduction up to~400℃,followed by sharp deterioration beyond 500℃–600℃,with residual capacity at 700℃reduced to~20%–25%of the ambient value.Strain–damage analyses revealed the formation of a peripheral tensile strain band,which thickened and propagated inward with increasing temperature,governing crack initiation and cover spalling.Supplemental analyses highlighted that transverse reinforcement improved ductility and damage distribution at moderate temperatures(~300℃),but bond deterioration and steel softening beyond~600℃substantially diminished confinement effectiveness.The proposed CDP model accurately reproduced experimental stress–strain curves(R^(2)≈0.94–0.98 up to 600℃;≈0.90 at 700℃),with peak stress errors within 7%–10%and energy absorption captured within~12%.These findings confirm the robustness of the temperature-indexed CDP framework for simulating fire-damaged reinforced concrete and provide practical guidelines for post-fire assessment,spalling detection,and fire-resilient design of structural members.展开更多
The high efficiency particulate air filter(HEPA)in exhaust system of high-level biosafety laboratory must be disinfected to kill harmful microorganisms before being replaced or tested.In-situ fumigation by vaporized h...The high efficiency particulate air filter(HEPA)in exhaust system of high-level biosafety laboratory must be disinfected to kill harmful microorganisms before being replaced or tested.In-situ fumigation by vaporized hydrogen peroxide(VHP)is the most commonly used disinfection method for HEPA unit.The disinfection effect of HEPA unit is affected by the internal environment,but the influence of initial internal environment on VHP penetration during the fumigation process is still rarely studied.In this paper,a numerical model was established based on a physical HEPA box unit and field measurement.According to the simulated VHP flow field during in-situ fumigation process,the influence of initial internal temperature and relative humidity on the VHP penetration effect in HEPA was discussed with the indicators of penetration rate and velocity distribution.The results showed that the VHP concentration in the upstream section of HEPA was relatively uniform,while the maximum and minimum concentrations in the downstream section showed great difference and located at the top and bottom,respectively.The distributions of VHP penetration and upstream velocity were both vertically uneven.The VHP penetration rates in the middle of HEPA remained around 73%.The initial temperature of 32℃or 36℃,or the initial relative humidity of 18%were the suitable initial internal environment for HEPA in-situ fumigation,which could keep the VHP penetration rates of the upper and lower parts of HEPA at about 76%and 61%,respectively.In the suitable initial environment,the penetration and disinfection effect could be promoted by appropriately extending the rapid injection duration.This study provides a reference for optimizing the initial environment setting of HEPA in-situ fumigation.展开更多
High-temperature stealth is vital for enhancing the concealment,survivability,and longevity of critical assets.However,achieving stealth across multiple infrared bands—particularly in the short-wave infrared(SWIR)ban...High-temperature stealth is vital for enhancing the concealment,survivability,and longevity of critical assets.However,achieving stealth across multiple infrared bands—particularly in the short-wave infrared(SWIR)band—along with microwave stealth and efficient thermal management at high temperatures,remains a significant challenge.Here,we propose a strategy that integrates an IR-selective emitter(Mo/Si multilayer films)and a microwave metasurface(TiB2–Al2O3–TiB2)to enable multi-infrared band stealth,encompassing mid-wave infrared(MWIR),long-wave infrared(LWIR),and SWIR bands,and microwave(X-band)stealth at 700℃,with simultaneous radiative cooling in non-atmospheric window(5–8μm).At 700℃,the device exhibits low emissivity of 0.38/0.44/0.60 in the MWIR/LWIR/SWIR bands,reflection loss below−3 dB in the X-band(9.6–12 GHz),and high emissivity of 0.82 in 5–8μm range—corresponding to a cooling power of 9.57 kW m^(−2).Moreover,under an input power of 17.3 kW m^(−2)—equivalent to the aerodynamic heating at Mach 2.2—the device demonstrates a temperature reduction of 72.4℃ compared to a conventional low-emissivity molybdenum surface at high temperatures.This work provides comprehensive guidance on high-temperature stealth design,with far-reaching implications for multispectral information processing and thermal management in extreme high-temperature environments.展开更多
Traditional metals often exhibit a trade-offbetween strength and plasticity,limiting their wide application of metals in aerospace,transportation,energy industry and other fields[1-3].In order to overcome this dilemma...Traditional metals often exhibit a trade-offbetween strength and plasticity,limiting their wide application of metals in aerospace,transportation,energy industry and other fields[1-3].In order to overcome this dilemma,high-entropy alloys(HEAs),proposed by Yeh et al.and Cantor et al.,are currently of great interest in the materials community due to their excellent mechanical properties[4-7].To further promote the wide application of HEAs in industrial production,Lu et al.developed a new eutectic high-entropy alloy(EHEAs)by combining the potential advantages of traditional eutectic alloys and HEAs[8-11].展开更多
CO_(2)flooding enhanced oil recovery(CO_(2)-EOR)represents a significant technology in the low permeability reservoir.With the fractures and heterogeneity in low permeability reservoirs,CO_(2)-EOR is susceptible to pe...CO_(2)flooding enhanced oil recovery(CO_(2)-EOR)represents a significant technology in the low permeability reservoir.With the fractures and heterogeneity in low permeability reservoirs,CO_(2)-EOR is susceptible to pessimistic gas channeling.Consequently,there is a need to develop conformance control materials that can be used in CO_(2)-EOR.Herein,to address the challenges of low strength and poor stability of polymer gel in high temperature and low permeability reservoirs,a new organic/metal ion composite crosslinking polymer gel(AR-Gel)is reported,which is formed by low hydrolysis and medium to high molecular weight polymer(CX-305),organic crosslinking agent(phenolic resin),and aluminium citrate(AI(Ⅲ)).The crosslinking of AI(Ⅲ)with carboxyl group and organic/metal ion double crosslinking can construct a more complex and stable polymer gel structure on the basis of traditional chemical crosslinking,to cope with the harsh conditions such as high temperature.The structure-activity relationship of AR-Gel was revealed by rheology behavior and micro-morphology.The applicability of AR-Gel in reservoir was investigated,as was its strength and stability in supercritical CO_(2).The anti-gas channeling and enhanced oil recovery of AR-Gel were investigated using low permeability fractured cores,and the field process parameters were provided.The gel can be used to meet supercritical CO_(2)reservoirs at 110℃and 20,000 mg/L salinity,with long-term stability over 60 days.The plugging rate of AR-Gel for fractured co re was 97%,with subsequent CO_(2)flooding re sulting in an enhanced oil recovery by 34.5%.ARGel can effectively control CO_(2)gas channeling and enhanced oil recovery.It offers a new material with high strength and temperature resistance,which is particularly beneficial in the CO_(2)flooding for the conformance control of oil field.展开更多
Polymer dielectrics possessing excellent electrical insulation and high thermal conductivity are pivotal for dielectric capacitors at elevated temperatures.However,the integration of electrical insulation and thermal ...Polymer dielectrics possessing excellent electrical insulation and high thermal conductivity are pivotal for dielectric capacitors at elevated temperatures.However,the integration of electrical insulation and thermal conductivity in polymers remains a challenge.In this work,we present a feasible strategy to integrate high electrical insulation and high thermal conductivity by bonding carbon quantum dots(CQDs)with the diamine monomer of polyetherimide(PEI).The CQDs with Coulomb blockade effect serve as traps for the migrating of electrons in the dielectrics,while the bonding networks formed by CQDs and PEI further deepen the traps and augment trap density.As a result,the hybrid dielectrics(PEI-NH_(2)-CQDs)exhibit nearly an order of magnitude higher electrical resistivity than that of pure PEI,leading to an 80%increase in discharge energy density with an energy efficiency of 90%at 200℃ compared to pure counterpart.Additionally,this all-organic dielectric achieves a significantly increased thermal conductivity of 0.65 W m^(-1) K^(-1) compared to 0.26 W m^(-1) K^(-1) of PEI,which supports its cyclic stability at elevated temperatures.We also demonstrate the kilogram-scale production of CQDs,synthesizing over 8 kg in a single batch,paving the way for large-scale production of reliable PEI-NH_(2)-CQDs dielectrics.展开更多
The roughness of the fracture surface directly affects the strength,deformation,and permeability of the surrounding rock in deep underground engineering.Understanding the effect of high temperature and thermal cycle o...The roughness of the fracture surface directly affects the strength,deformation,and permeability of the surrounding rock in deep underground engineering.Understanding the effect of high temperature and thermal cycle on the fracture surface roughness plays an important role in estimating the damage degree and stability of deep rock mass.In this paper,the variations of fracture surface roughness of granite after different heating and thermal cycles were investigated using the joint roughness coefficient method(JRC),three-dimensional(3D)roughness parameters,and fractal dimension(D),and the mechanism of damage and deterioration of granite were revealed.The experimental results show an increase in the roughness of the granite fracture surface as temperature and cycle number were incremented.The variations of JRC,height parameter,inclination parameter and area parameter with the temperature conformed to the Boltzmann's functional distribution,while the D decreased linearly as the temperature increased.Besides,the anisotropy index(Ip)of the granite fracture surface increased as the temperature increased,and the larger parameter values of roughness characterization at different temperatures were attained mainly in directions of 20°–40°,60°–100°and 140°–160°.The fracture aperture of granite after fracture followed the Gauss distribution and the average aperture increased with increasing temperature,which increased from 0.665 mm at 25℃to 1.058 mm at 800℃.High temperature caused an uneven thermal expansion,water evaporation,and oxidation of minerals within the granite,which promoted the growth and expansion of microfractures,and reduced interparticle bonding strength.In particular,the damage was exacerbated by the expansion and cracking of the quartz phase transition after T>500℃.Thermal cycles contributed to the accumulation of this damage and further weakened the interparticle bonding forces,resulting in a significant increase in the roughness,anisotropy,and aperture of the fracture surface after five cycles.展开更多
The deterioration of aqueous zinc-ion batteries(AZIBs)is confronted with challenges such as unregulated Zn^(2+)diffusion,dendrite growth and severe decay in battery performance under harsh environments.Here,a design c...The deterioration of aqueous zinc-ion batteries(AZIBs)is confronted with challenges such as unregulated Zn^(2+)diffusion,dendrite growth and severe decay in battery performance under harsh environments.Here,a design concept of eutectic electrolyte is presented by mixing long chain polymer molecules,polyethylene glycol dimethyl ether(PEGDME),with H_(2)O based on zinc trifluoromethyl sulfonate(Zn(OTf)2),to reconstruct the Zn^(2+)solvated structure and in situ modified the adsorption layer on Zn electrode surface.Molecular dynamics simulations(MD),density functional theory(DFT)calculations were combined with experiment to prove that the long-chain polymer-PEGDME could effectively reduce side reactions,change the solvation structure of the electrolyte and priority absorbed on Zn(002),achieving a stable dendrite-free Zn anode.Due to the comprehensive regulation of solvation structure and zinc deposition by PEGDME,it can stably cycle for over 3200 h at room temperature at 0.5 mA/cm^(2)and 0.5 mAh/cm^(2).Even at high-temperature environments of 60℃,it can steadily work for more than 800 cycles(1600 h).Improved cyclic stability and rate performance of aqueous Zn‖VO_(2)batteries in modified electrolyte were also achieved at both room and high temperatures.Beyond that,the demonstration of stable and high-capacity Zn‖VO_(2)pouch cells also implies its practical application.展开更多
Low-to medium-maturity oil shale resources display substantial reserves, offering promising prospects for in-situ conversion inChina. Investigating the evolution of the mechanical properties of the reservoir and capro...Low-to medium-maturity oil shale resources display substantial reserves, offering promising prospects for in-situ conversion inChina. Investigating the evolution of the mechanical properties of the reservoir and caprock under in-situ high-temperature and confine-ment conditions is of considerable importance. Compared to conventional mechanical experiments on rock samples after high-temperat-ure treatment, in-situ high-temperature experiments can more accurately characterize the behavior of rocks in practical engineering,thereby providing a more realistic reflection of their mechanical properties. In this study, an in-situ high-temperature triaxial compressiontesting machine is developed to conduct in-situ compression tests on sandstone at different temperatures(25, 200, 400, 500, and 650℃)and confining pressures(0, 10, and 20 MPa). Based on the experimental results, the temperature-dependent changes in compressivestrength, peak strain, elastic modulus, Poisson's ratio, cohesion, and internal friction angle are thoroughly analyzed and discussed. Resultsindicate that the mass of sandstone gradually decreases as the temperature increases. The thermal conductivity and thermal diffusivity ofsandstone exhibit a linear relationship with temperature. Peak stress decreases as the temperature rises, while it increases with higher con-fining pressures. Notably, the influence of confining pressure on peak stress diminishes at higher temperatures. Additionally, as the tem-perature rises, the Poisson's ratio of sandstone decreases. The internal friction angle also decreases with increasing temperature, with 400℃ acting as the threshold temperature. Interestingly, under uniaxial conditions, the damage stress of sandstone is less affected by tem-perature. However, when the confining pressure is 10 or 20 MPa, the damage stress decreases as the temperature increases. This study en-hances our understanding of the influence of in-situ high-temperature and confinement conditions on the mechanical properties of sand-stone strata. The study also provides valuable references and experimental data that support the development of low-to medium-maturityoil shale resources.展开更多
文摘Platinum group metals have high melting points,strong corrosion resistance,stable chemical properties,and low oxygen permeability in high-temperature oxygen-containing environments.As thermal protective coating materials,they have gained essential applications in the aerospace field and have excellent prospects for application in frontier military fields,such as protecting hot-end components of hypersonic aircraft.This research reviewed the latest research progress of platinum group metal coatings with hightemperature oxidation resistance,including coating preparation techniques,oxidation failure,and alloying modification.The leading preparation techniques of current platinum group metal coatings were discussed,as well as the advantages and disadvantages of various existing preparation techniques.Besides,the intrinsic properties,failure forms,and failure mechanisms of coatings of single platinum group metal in high-temperature oxygen-containing environments were analyzed.On this basis,the necessity,main methods,and main achievements of alloying modification of platinum group metals were summarized.Finally,the future development of platinum group coatings with high-temperature oxidation resistance was discussed and prospected.
基金supported by the National Natural Science Foundation of China (Grant Nos.12074213 and 11574108)the Major Basic Program of Natural Science Foundation of Shandong Province (Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Province (Grant No.ZR2023MA082)。
文摘In recent years,the research on superconductivity in one-dimensional(1D)materials has been attracting increasing attention due to its potential applications in low-dimensional nanodevices.However,the critical temperature(T_(c))of 1D superconductors is low.In this work,we theoretically investigate the possible high T_(c) superconductivity of(5,5)carbon nanotube(CNT).The pristine(5,5)CNT is a Dirac semimetal and can be modulated into a semiconductor by full hydrogenation.Interestingly,by further hole doping,it can be regulated into a metallic state with the sp^(3)-hybridized σ electrons metalized,and a giant Kohn anomaly appears in the optical phonons.The two factors together enhance the electron–phonon coupling,and lead to high-T_(c) superconductivity.When the hole doping concentration of hydrogenated-(5,5)CNT is 2.5 hole/cell,the calculated T_(c) is 82.3 K,exceeding the boiling point of liquid nitrogen.Therefore,the predicted hole-doped hydrogenated-(5,5)CNT provides a new platform for 1D high-T_(c) superconductivity and may have potential applications in 1D nanodevices.
基金funded by the Earmarked Fund for China Agriculture Research System,grant number CARS-01-33.
文摘Spikelet filling characteristics in early-season rice in southern China may be distinctive due to its exposure to high temperatures during the ripening period.However,limited information is currently available on these characteristics.This study aimed to characterize spikelet filling in early-season rice and identify the key factors contributing to its improvement.Field experiments were conducted over two years(2021 and 2022)to mainly investigate the proportions of fully-filled,partially-filled,and empty spikelets,along with the biomass-fertilized spikelet ratio and harvest index,in 11 early-season rice varieties.The results revealed significant varietal variation in spikelet filling,with the proportion of fully-filled spikelets ranging from 60.6%to 81.1%in 2021 and from 66.3%to 79.2%in 2022.Among the 11 varieties,Liangyou 42,Lingliangyou 942,and Liangyou 287 exhibited relatively superior performance in spikelet filling.Linear regression revealed that,although a significant negative relationship existed between the proportion of fully-filled spikelets and both partially-filled and empty spikelets,the relationship with partially-filled spikelets was stronger.Additionally,the proportion of fully-filled spikelets showed a significant positive relationship with the harvest index but not with the biomass-fertilized spikelet ratio.These findings indicate that increasing the harvest index and reducing the occurrence of partially-filled grains are essential strategies for improving spikelet filling in early-season rice.
基金supported by National Natural Science Foundation of China(Grant No.52272100)the Fund of Science and Technology on Advanced Ceramic Fibers and Composites Laboratory(Grant No.WDZC20215250507)the Fund of National Key Laboratory of Nuclear Reactor Technology of Nuclear Power Institute of China(KGSW-0324-0301-08)。
文摘The demand for sensors capable of operating in extreme environment of the fields,such as aerospace vehicles,aeroengines and fire protection,is rapidly increasing.However,developing flexible ceramic fibrous pressure sensors that combine high temperature stability with robust mechanical properties remains a significant challenge.Herein,through precise multi-scale process control,high-strength(2.1 MPa)TiC-SiC flexible fibrous membrane is successfully fabricated.The membrane exhibits exceptional thermal resistance(2000℃)and long–term thermal stability(1800℃ for 5 h)in the inert atmosphere.Meanwhile,the TiC-SiC fibrous membrane shows excellent oxidation resistance and still achieves strength of 1.8 MPa after being oxidized at 1200℃ for 1 h in air.Remarkably,TiC-SiC fibrous membrane withstands a load of approximately 1400 times its own weight and the ablation of butane flame(~1300℃)for at least 1 h without breaking.Notably,after heat treatment at 1800℃ for 5 h in an argon atmosphere,the TiC-SiC fibrous membrane even sustains pressure–sensing performance for up to 300 cycles.The membrane exhibits stable resistivity up to 900℃ and shows sensing stability under butane flame.The results of this work provide an effective and feasible solution to fill the research gap of flexible fibrous sensors for extreme environments.
基金funded by the National Natural Science Foundation of China(Nos.52209130 and 52379100)Shandong Provincial Natural Science Foundation(No.ZR2024ME112).
文摘Thermal-mechanical damage and deformation at the interface between shotcrete linings and the surrounding rock of tunnels under high-temperature and variable-temperature conditions are critical to the safe construction and operation of tunnel engineering.This study investigated the thermo-mechanical damage behavior of the composite interface between alkali-resistant glass fiber-reinforced concrete(ARGFRC)and granite,focusing on a plateau railway tunnel.Laboratory triaxial tests,laser scanning,XRD analysis,numerical simulations,and theoretical analyses were employed to investigate how different initial curing temperatures and joint roughness coefficient(JRC)influence interfacial damage behavior.The results indicate that an increase in interface roughness exacerbates the structural damage at the interface.At a JRC of 19.9 and a temperature of 70℃,crack initiation in granite was notably restrained when the confining pressure rose from 7 MPa to 10 MPa.Roughness-induced stress distribution at the interface was notably altered,although this effect became less pronounced under high confining pressure conditions.Additionally,during high-temperature curing,thermal stress concentration at the tips of micro-convex protrusions on the granite surface induced microcracks in the adjacent ARGFRC matrix,followed by deformation.These findings provide practical guidelines for designing concrete support systems to ensure tunnel structural safety in high-altitude regions with harsh thermal environments.
基金National Natural Science Foundation of China,Grant/Award Number:52104120Hunan Provincial Key Laboratory of Key Technology on Hydropower Development,Grant/Award Number:PKLHD202303。
文摘During geothermal resource exploitation,the potential deterioration of mechanical properties in high-temperature granite subjected to cooling poses a significant safety concern.To address this,the present study investigates the coupled thermo-mechanical behavior of granite during heating and cooling through a combination of laboratory tests and finite difference method analysis.Initial investigations involve X-ray diffraction,thermal expansion test,thermogravimetric analysis,and uniaxial compression test.Results show the significant variations of granite properties under different thermal conditions,attributed to temperature gradients,water evaporation,and mineral phase transitions.Subsequently,a model considering temperature-dependent parameters and real-time cooling rates was employed to simulate linear heating and nonlinear cooling processes.Simulation results indicate that the thermal cracking predominantly occurs during the heating stage,with tensile failure as the primary mode.Additionally,a faster real-time cooling rate at higher temperatures intensifies the thermal cracking behavior in granite.This study effectively elucidates the thermomechanical coupling behavior of granite during heating and cooling processes,providing insights into the mechanisms of mechanical property changes with rising or decreasing temperatures.
基金Project(51879135)supported by the Taishan Scholars Program,ChinaProject(52309130)supported by the National Natural Science Foundation of China+1 种基金Project(SKLGME023003)supported by the Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,ChinaProject(2022AH051754)supported by the Natural Science Research Project of Anhui Universities,China。
文摘The effect of real-time high temperature and thermal treatment on the mechanical characteristics and crack evolution of granite with different grain sizes(i.e.,0.5 mm,0.7 mm and 1.0 mm)is investigated by numerical simulation employing a grain-based model,and the impact of initial cracks on thermal-induced strengthening is also examined by integrating random cracks within the model before tests.The results revealed that thermal stress,induced by the mismatch in thermal expansion coefficient between various minerals,is the primary distinction between rock specimens in real-time high temperature and thermal treatment.With increasing temperature,the thermal stress gradually accumulates in quartz minerals under real-time high temperature but releases after thermal treatment.The high local contact force significantly affects the peak stress and crack evolution.Uniaxial compression simulation results demonstrate that progressive accumulation of thermal stress induces degradation in macroscopic peak strength and increase of microcrack density.The grain size controls the ratio of intergranular contacts to intragranular contacts,and leads to an increase in strong contact number in the intragrain and a decrease in strong contact number in the intergrain.The strengthening of uniaxial compression strength in the experiment can be well simulated by controlling the number of pre-existing initial cracks in the numerical model.Our conclusions are beneficial to a better understanding of the underlying mechanisms of thermal damage and thermal strengthening of granite for deep geological engineering.
基金financially supported by the National Natural Science Foundation of China (32071978)the National Key Research and Development Program of China (2022YFD2300901 and 2022YFD2300905)。
文摘High temperature stress (HT) significantly reduces maize yield by impairing starch accumulation in kernels.However,the mechanism by which HT affects starch synthesis remains controversial-whether through reduced assimilate supply or direct inhibition on kernel metabolism.To clarify these mechanisms,a heat-sensitive maize hybrid,Xianyu 335 (XY),was exposed to 30℃/20℃ (maximum/minimum temperature,control) and 40℃/30℃ for seven consecutive days during the seed setting stage.Synchronous pollination (SP),apical pollination (AP),and shading treatments were applied to manipulate the inherent source–sink ratio in maize plants.Results showed that apical kernel weight decreased by 11.9%under 40℃ in the SP treatment.The ^(13)C content,starch accumulation,and cell-wall invertase (CWIN) activity also declined by 15.9,36.7,and 16.4%,respectively,under HT.In the shading treatment,40℃/30℃ caused even greater reductions in^(13)C content,starch accumulation,and CWIN activity due to diminished assimilate supply.Conversely,in the AP treatment,starch content and CWIN activity increased by 22.0 and 18.5%,respectively,under 40℃/30℃,resulting in kernel weight and ^(13)C content similar to those in SP and shading treatments regardless of temperature.Consistent with apical kernels under AP,HT did not negatively affect middle kernels in either SP or shading treatments,as kernel weight and starch content remained unchanged under HT.Although all kernels were exposed to the same HT or control environment,their responses varied a lot.The impaired starch synthesis in apical kernels under HT was rescued by increasing carbon supply via AP treatment.The contrasting performance among middle kernels,apical kernels under AP,and apical kernels under SP or shading indicates that reduced carbon supply is a critical factor underlying inhibited starch accumulation.Our findings provide a theoretical basis for further understanding kernel abortion under HT.
基金supported by the National Natural Science Foundation of China(No.62464010)Spring City Plan-Special Program for Young Talents(K202005007)+2 种基金Yunnan Talents Support Plan for Young Talents(XDYC-QNRC-2022-0482)Yunnan Local Colleges Applied Basic Research Projects(202101BA070001-138)Frontier Research Team of Kunming University 2023.
文摘Rechargeable Zn/Sn-air batteries have received considerable attention as promising energy storage devices.However,the electrochemical performance of these batteries is significantly constrained by the sluggish electrocatalytic reaction kinetics at the cathode.The integration of light energy into Zn/Sn-air batteries is a promising strategy for enhancing their performance.However,the photothermal and photoelectric effects generate heat in the battery under prolonged solar irradiation,leading to air cathode instability.This paper presents the first design and synthesis of Ni_(2)-1,5-diamino-4,8-dihydroxyanthraquinone(Ni_(2)DDA),an electronically conductiveπ-d conjugated metal-organic framework(MOF).Ni_(2)DDA exhibits both photoelectric and photothermal effects,with an optical band gap of~1.14 eV.Under illumination,Ni_(2)DDA achieves excellent oxygen evolution reaction performance(with an overpotential of 245 mV vs.reversible hydrogen electrode at 10 mA cm^(−2))and photothermal stability.These properties result from the synergy between the photoelectric and photothermal effects of Ni_(2)DDA.Upon integration into Zn/Sn-air batteries,Ni_(2)DDA ensures excellent cycling stability under light and exhibits remarkable performance in high-temperature environments up to 80℃.This study experimentally confirms the stable operation of photo-assisted Zn/Sn-air batteries under high-temperature conditions for the first time and provides novel insights into the application of electronically conductive MOFs in photoelectrocatalysis and photothermal catalysis.
基金The National Key R&D Program of China(No.2022YFB3902902)the National Natural Science Foundation of China(No.52276003).
文摘Spaceborne optomechanical systems face the dual challenges of extreme thermal disturbances and millikelvin-level temperature control precision during orbital operations,demanding robust control strategies.To address the performance limitations of conventional fixed-parameter active disturbance rejection control(ADRC)under complex operating conditions,this work proposes a Qlearning-enhanced adaptive ADRC framework.A thermal-transfer model incorporating multisource disturbances(solar radiation,structural conduction,and contact thermal resistance)is established,coupled with a reinforcement learning-driven parameter optimization mechanism.The ε-greedy policy dynamically adjusts observer bandwidth(ω_(o)∈[0.01,0.2])and controller bandwidth(ω_(c)∈[0.01,0.1])to enable real-time estimation and compensation of total disturbances.Simulation results demonstrate significant improvements over fixed-parameter ADRC and a self-tuning internal model control proportional-integral(SIMC-PI)controller:31.3% and 15.4% reduction in settling time during setpoint responses,respectively;21.8% lower integral absolute error(IAE)than the fixed-parameter ADRC during setpoint step responses;12.7% and 52.5% enhancement in control precision over conventional fixed-parameter and SIMC-PI controllers,respectively,under±10 K periodic and step thermal disturbances.Monte Carlo robustness tests reveal smaller fluctuation ranges of IAE,settling time,and overshoot under±5% parameter perturbations.This methodology establishes a new paradigm for millikelvin-level thermal control in space optical payloads.
基金supported by the National Natural Science Foundation of China(No.51874368)。
文摘The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The microstructure analysis revealed that the tungsten phase in 95W-HEAs exhibited a nearly spherical morphology in the HEA binder matrix and the formation of a Cr−Mn oxide mixed phase was observed.The sintering temperature exerted a significant influence on the relative density,grain size,W−W contiguity,and mechanical properties of the alloys.The optimal performance was achieved when sintering at 1450℃,yielding a relative density of 96.61%,a W−W contiguity of 0.528,an average grain size of 18.97μm,a compressive strength of 2234.82 MPa,and a hardness of HV 400.6.The activation energy for the diffusion of tungsten in the liquid phase formed by HEA binder was calculated to be 354.514 kJ/mol,highlighting its role in controlling grain growth.
文摘This study investigates the thermo–mechanical behavior of C40 concrete and reinforced concrete subjected to elevated temperatures up to 700℃by integrating experimental testing and advanced numerical modeling.A temperature-indexed Concrete Damage Plasticity(CDP)framework incorporating bond–slip effects was developed in Abaqus to capture both global stress–strain responses and localized damage evolution.Uniaxial compression tests on thermally exposed cylinders provided residual strength data and failure observations for model calibration and validation.Results demonstrated a distinct two-stage degradation regime:moderate stiffness and strength reduction up to~400℃,followed by sharp deterioration beyond 500℃–600℃,with residual capacity at 700℃reduced to~20%–25%of the ambient value.Strain–damage analyses revealed the formation of a peripheral tensile strain band,which thickened and propagated inward with increasing temperature,governing crack initiation and cover spalling.Supplemental analyses highlighted that transverse reinforcement improved ductility and damage distribution at moderate temperatures(~300℃),but bond deterioration and steel softening beyond~600℃substantially diminished confinement effectiveness.The proposed CDP model accurately reproduced experimental stress–strain curves(R^(2)≈0.94–0.98 up to 600℃;≈0.90 at 700℃),with peak stress errors within 7%–10%and energy absorption captured within~12%.These findings confirm the robustness of the temperature-indexed CDP framework for simulating fire-damaged reinforced concrete and provide practical guidelines for post-fire assessment,spalling detection,and fire-resilient design of structural members.
基金supported by the Natural Science Foundation of Hebei Province(Project no.E2023202232)Science and Technology Research Project for Colleges and Universities in Hebei Province(Project no.CXY2024026).
文摘The high efficiency particulate air filter(HEPA)in exhaust system of high-level biosafety laboratory must be disinfected to kill harmful microorganisms before being replaced or tested.In-situ fumigation by vaporized hydrogen peroxide(VHP)is the most commonly used disinfection method for HEPA unit.The disinfection effect of HEPA unit is affected by the internal environment,but the influence of initial internal environment on VHP penetration during the fumigation process is still rarely studied.In this paper,a numerical model was established based on a physical HEPA box unit and field measurement.According to the simulated VHP flow field during in-situ fumigation process,the influence of initial internal temperature and relative humidity on the VHP penetration effect in HEPA was discussed with the indicators of penetration rate and velocity distribution.The results showed that the VHP concentration in the upstream section of HEPA was relatively uniform,while the maximum and minimum concentrations in the downstream section showed great difference and located at the top and bottom,respectively.The distributions of VHP penetration and upstream velocity were both vertically uneven.The VHP penetration rates in the middle of HEPA remained around 73%.The initial temperature of 32℃or 36℃,or the initial relative humidity of 18%were the suitable initial internal environment for HEPA in-situ fumigation,which could keep the VHP penetration rates of the upper and lower parts of HEPA at about 76%and 61%,respectively.In the suitable initial environment,the penetration and disinfection effect could be promoted by appropriately extending the rapid injection duration.This study provides a reference for optimizing the initial environment setting of HEPA in-situ fumigation.
基金supported by National Key Research and Development Program of China(Grant No.2024YFA1210500)National Natural Science Foundation of China(Grant Nos.U2341225 and 62375242)+1 种基金Sichuan Science and Technology Program(2025YFHZ0297)Postdoctoral Fellowship Program of CPSF(Grant No.GZB20240647).
文摘High-temperature stealth is vital for enhancing the concealment,survivability,and longevity of critical assets.However,achieving stealth across multiple infrared bands—particularly in the short-wave infrared(SWIR)band—along with microwave stealth and efficient thermal management at high temperatures,remains a significant challenge.Here,we propose a strategy that integrates an IR-selective emitter(Mo/Si multilayer films)and a microwave metasurface(TiB2–Al2O3–TiB2)to enable multi-infrared band stealth,encompassing mid-wave infrared(MWIR),long-wave infrared(LWIR),and SWIR bands,and microwave(X-band)stealth at 700℃,with simultaneous radiative cooling in non-atmospheric window(5–8μm).At 700℃,the device exhibits low emissivity of 0.38/0.44/0.60 in the MWIR/LWIR/SWIR bands,reflection loss below−3 dB in the X-band(9.6–12 GHz),and high emissivity of 0.82 in 5–8μm range—corresponding to a cooling power of 9.57 kW m^(−2).Moreover,under an input power of 17.3 kW m^(−2)—equivalent to the aerodynamic heating at Mach 2.2—the device demonstrates a temperature reduction of 72.4℃ compared to a conventional low-emissivity molybdenum surface at high temperatures.This work provides comprehensive guidance on high-temperature stealth design,with far-reaching implications for multispectral information processing and thermal management in extreme high-temperature environments.
基金financial supported by the Natural Science Foundation of Jiangsu Provincial Education Department(No.24KJB430003)the Natural Science Foundation for Young Scholars of Jiangsu Province(No.BK20240979)+3 种基金support of Natural Science Foundation for Young Scholars of Jiangsu Province(No.BK20220628)the National Natural Science Foundation for Young Scholars of China(52301130)the Changzhou Sci&Tech program(No.GJ20220153)support of the Natural Science Foundation of Jiangsu Provincial Education Department(No.21KJB430001).
文摘Traditional metals often exhibit a trade-offbetween strength and plasticity,limiting their wide application of metals in aerospace,transportation,energy industry and other fields[1-3].In order to overcome this dilemma,high-entropy alloys(HEAs),proposed by Yeh et al.and Cantor et al.,are currently of great interest in the materials community due to their excellent mechanical properties[4-7].To further promote the wide application of HEAs in industrial production,Lu et al.developed a new eutectic high-entropy alloy(EHEAs)by combining the potential advantages of traditional eutectic alloys and HEAs[8-11].
基金project was supported by the Fund of State Key Laboratory of Deep Oil and Gas,China University of Petroleum(East China)(No.SKLDOG2024-ZYRC-06)Key Program of National Natural Science Foundation of China(52130401)+1 种基金National Natural Science Foundation of China(52104055,52374058)Shandong Provincial Natural Science Foundation,China(ZR2021ME171,ZR2024YQ043)。
文摘CO_(2)flooding enhanced oil recovery(CO_(2)-EOR)represents a significant technology in the low permeability reservoir.With the fractures and heterogeneity in low permeability reservoirs,CO_(2)-EOR is susceptible to pessimistic gas channeling.Consequently,there is a need to develop conformance control materials that can be used in CO_(2)-EOR.Herein,to address the challenges of low strength and poor stability of polymer gel in high temperature and low permeability reservoirs,a new organic/metal ion composite crosslinking polymer gel(AR-Gel)is reported,which is formed by low hydrolysis and medium to high molecular weight polymer(CX-305),organic crosslinking agent(phenolic resin),and aluminium citrate(AI(Ⅲ)).The crosslinking of AI(Ⅲ)with carboxyl group and organic/metal ion double crosslinking can construct a more complex and stable polymer gel structure on the basis of traditional chemical crosslinking,to cope with the harsh conditions such as high temperature.The structure-activity relationship of AR-Gel was revealed by rheology behavior and micro-morphology.The applicability of AR-Gel in reservoir was investigated,as was its strength and stability in supercritical CO_(2).The anti-gas channeling and enhanced oil recovery of AR-Gel were investigated using low permeability fractured cores,and the field process parameters were provided.The gel can be used to meet supercritical CO_(2)reservoirs at 110℃and 20,000 mg/L salinity,with long-term stability over 60 days.The plugging rate of AR-Gel for fractured co re was 97%,with subsequent CO_(2)flooding re sulting in an enhanced oil recovery by 34.5%.ARGel can effectively control CO_(2)gas channeling and enhanced oil recovery.It offers a new material with high strength and temperature resistance,which is particularly beneficial in the CO_(2)flooding for the conformance control of oil field.
基金supported by the National Natural Science Foundation of China(52172265)Excellent Youth Science Foundation of Hunan Province(2022JJ20067)+1 种基金The Science and Technology Innovation Program of Hunan Province(2022RC1074)Central South University Innovation-Driven Research Program(2023CXQD010).
文摘Polymer dielectrics possessing excellent electrical insulation and high thermal conductivity are pivotal for dielectric capacitors at elevated temperatures.However,the integration of electrical insulation and thermal conductivity in polymers remains a challenge.In this work,we present a feasible strategy to integrate high electrical insulation and high thermal conductivity by bonding carbon quantum dots(CQDs)with the diamine monomer of polyetherimide(PEI).The CQDs with Coulomb blockade effect serve as traps for the migrating of electrons in the dielectrics,while the bonding networks formed by CQDs and PEI further deepen the traps and augment trap density.As a result,the hybrid dielectrics(PEI-NH_(2)-CQDs)exhibit nearly an order of magnitude higher electrical resistivity than that of pure PEI,leading to an 80%increase in discharge energy density with an energy efficiency of 90%at 200℃ compared to pure counterpart.Additionally,this all-organic dielectric achieves a significantly increased thermal conductivity of 0.65 W m^(-1) K^(-1) compared to 0.26 W m^(-1) K^(-1) of PEI,which supports its cyclic stability at elevated temperatures.We also demonstrate the kilogram-scale production of CQDs,synthesizing over 8 kg in a single batch,paving the way for large-scale production of reliable PEI-NH_(2)-CQDs dielectrics.
基金funding support from the National Natural Science Foundation of China(Grant No.52274082)the Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology(Grant No.JXUSTQJBJ2020003)the Innovation Fund Designated for Graduate Students of Jiangxi Province(Grant No.YC2023-B215).
文摘The roughness of the fracture surface directly affects the strength,deformation,and permeability of the surrounding rock in deep underground engineering.Understanding the effect of high temperature and thermal cycle on the fracture surface roughness plays an important role in estimating the damage degree and stability of deep rock mass.In this paper,the variations of fracture surface roughness of granite after different heating and thermal cycles were investigated using the joint roughness coefficient method(JRC),three-dimensional(3D)roughness parameters,and fractal dimension(D),and the mechanism of damage and deterioration of granite were revealed.The experimental results show an increase in the roughness of the granite fracture surface as temperature and cycle number were incremented.The variations of JRC,height parameter,inclination parameter and area parameter with the temperature conformed to the Boltzmann's functional distribution,while the D decreased linearly as the temperature increased.Besides,the anisotropy index(Ip)of the granite fracture surface increased as the temperature increased,and the larger parameter values of roughness characterization at different temperatures were attained mainly in directions of 20°–40°,60°–100°and 140°–160°.The fracture aperture of granite after fracture followed the Gauss distribution and the average aperture increased with increasing temperature,which increased from 0.665 mm at 25℃to 1.058 mm at 800℃.High temperature caused an uneven thermal expansion,water evaporation,and oxidation of minerals within the granite,which promoted the growth and expansion of microfractures,and reduced interparticle bonding strength.In particular,the damage was exacerbated by the expansion and cracking of the quartz phase transition after T>500℃.Thermal cycles contributed to the accumulation of this damage and further weakened the interparticle bonding forces,resulting in a significant increase in the roughness,anisotropy,and aperture of the fracture surface after five cycles.
基金supported by the National Natural Science Foundation of China(Nos.22208221,22178221)the Natural Science Foundation of Guangdong Province(Nos.2024A1515011078,2024A1515011507)+1 种基金the Shenzhen Science and Technology Program(Nos.JCYJ20220818095805012,JCYJ20230808105109019)the Start-up Research Funding of Shenzhen University(No.868-000001032522).
文摘The deterioration of aqueous zinc-ion batteries(AZIBs)is confronted with challenges such as unregulated Zn^(2+)diffusion,dendrite growth and severe decay in battery performance under harsh environments.Here,a design concept of eutectic electrolyte is presented by mixing long chain polymer molecules,polyethylene glycol dimethyl ether(PEGDME),with H_(2)O based on zinc trifluoromethyl sulfonate(Zn(OTf)2),to reconstruct the Zn^(2+)solvated structure and in situ modified the adsorption layer on Zn electrode surface.Molecular dynamics simulations(MD),density functional theory(DFT)calculations were combined with experiment to prove that the long-chain polymer-PEGDME could effectively reduce side reactions,change the solvation structure of the electrolyte and priority absorbed on Zn(002),achieving a stable dendrite-free Zn anode.Due to the comprehensive regulation of solvation structure and zinc deposition by PEGDME,it can stably cycle for over 3200 h at room temperature at 0.5 mA/cm^(2)and 0.5 mAh/cm^(2).Even at high-temperature environments of 60℃,it can steadily work for more than 800 cycles(1600 h).Improved cyclic stability and rate performance of aqueous Zn‖VO_(2)batteries in modified electrolyte were also achieved at both room and high temperatures.Beyond that,the demonstration of stable and high-capacity Zn‖VO_(2)pouch cells also implies its practical application.
基金financially supported by the Beijing Natural Science Foundation,China (No.JQ21028)the National Natural Science Foundation of China (Nos.52311530070,52278326,and 52004015)+2 种基金the Major National Science and Technology Project for Deep Earth,China (No.2024ZD1003805)the Project from PetroChina RIPED:the Study on the evolution law of Mineral Structure and Rock Mechanical Properties Under Ultra-High Temperature Conditions (No.2022-KFKT-02)the Fundamental Research Funds for the Central Universities of China (No.FRF-IDRY-20-003,Interdisciplinary Research Project for Young Teachers of USTB)。
文摘Low-to medium-maturity oil shale resources display substantial reserves, offering promising prospects for in-situ conversion inChina. Investigating the evolution of the mechanical properties of the reservoir and caprock under in-situ high-temperature and confine-ment conditions is of considerable importance. Compared to conventional mechanical experiments on rock samples after high-temperat-ure treatment, in-situ high-temperature experiments can more accurately characterize the behavior of rocks in practical engineering,thereby providing a more realistic reflection of their mechanical properties. In this study, an in-situ high-temperature triaxial compressiontesting machine is developed to conduct in-situ compression tests on sandstone at different temperatures(25, 200, 400, 500, and 650℃)and confining pressures(0, 10, and 20 MPa). Based on the experimental results, the temperature-dependent changes in compressivestrength, peak strain, elastic modulus, Poisson's ratio, cohesion, and internal friction angle are thoroughly analyzed and discussed. Resultsindicate that the mass of sandstone gradually decreases as the temperature increases. The thermal conductivity and thermal diffusivity ofsandstone exhibit a linear relationship with temperature. Peak stress decreases as the temperature rises, while it increases with higher con-fining pressures. Notably, the influence of confining pressure on peak stress diminishes at higher temperatures. Additionally, as the tem-perature rises, the Poisson's ratio of sandstone decreases. The internal friction angle also decreases with increasing temperature, with 400℃ acting as the threshold temperature. Interestingly, under uniaxial conditions, the damage stress of sandstone is less affected by tem-perature. However, when the confining pressure is 10 or 20 MPa, the damage stress decreases as the temperature increases. This study en-hances our understanding of the influence of in-situ high-temperature and confinement conditions on the mechanical properties of sand-stone strata. The study also provides valuable references and experimental data that support the development of low-to medium-maturityoil shale resources.
