Commercial carbonate electrolytes suffer from ion transport difficulty in bulk electrolytes and interphase at low temperatures,bringing challenges to the application of lithium-ion batteries(LIBs)at low temperatures.H...Commercial carbonate electrolytes suffer from ion transport difficulty in bulk electrolytes and interphase at low temperatures,bringing challenges to the application of lithium-ion batteries(LIBs)at low temperatures.Herein,the ester solvent of methyl propionate(MP)with low melting point and low viscosity was used to tackle ion transport difficulty in electrolytes.Fluorinated ester was further added to accelerate interfacial transport through intermolecular interactions.The influence of fluorinated esters with different fluorination degrees on the solvation structure of electrolytes and the performance of batteries was further studied.As a result,methyl pentafluoropropionate(M5F)with five fluorine atoms was selected for its optimal interactions with both Li+and MP solvent in the primary solvation structure,contributing to desired solvation structure for fast interfacial transport.The LiFePO4(LFP)||graphite cell with LiFSI-MP-M5F electrolyte exhibited a high cyclability of 85.8%after 120 cycles and retained 81.2%of room-temperature capacity when charged and discharged at−30℃.1 Ah LFP||graphite pouch cell with high cathode loading(20 mg/cm^(2))in LiFSI-MP-M5F electrolyte exhibited 0.85 Ah capacity when charged and discharged at−20℃.This work provides a guidance for electrolyte design by synergistic fluorinated and non-fluorinated solvents for LIBs at low-temperature application.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
With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at ...With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at different temperatures in combination with real-time acoustic emission(AE)monitoring.The results show that the cumulative AE count increases stepwise with increasing cyclic stress.The peak frequency is concentrated primarily in the medium-frequency range,exhibiting a band distribution across low-,medium-,and high-frequency ranges.As the temperature increases,the proportion of low-frequency signals decreases from 14.32%to 5.76%,whereas the proportion of medium-frequency signals increases from 85.48%to 94.1%.The proportion of high-frequency signals remains relatively constant between 0.1%and 0.2%.The amplitude-count relationship of the AE signals demonstrates a strong negative power-law correlation.Furthermore,with increasing temperature,the negative power-law exponent of the amplitude gradually decreases,with the b value decreasing from 1.096 to 0.837 and the a value decreasing from 7.4871 to 6.6982.Under all four temperature conditions,the dominant failure mode in rock salt is tensile cracking.However,as the temperature increases,the proportion of tensile cracks decreases from 88.59%to 75.12%,whereas the proportion of shear cracks at 80℃is nearly double that at 20℃.This finding indicates that as the temperature increases,the ductility of the material increases,and the crack propagation mode shifts from tensile to shear.This research provides valuable insights for the design and stability assessment of salt cavern reservoirs for deep underground energy storage systems.展开更多
Raw water temperature can fluctuate significantly throughout the year,with peaks above 30℃in summer and below 15℃in winter.Traditional desalination systems(e.g.,reverse osmosis,RO)face challenges under these varying...Raw water temperature can fluctuate significantly throughout the year,with peaks above 30℃in summer and below 15℃in winter.Traditional desalination systems(e.g.,reverse osmosis,RO)face challenges under these varying temperature conditions.Specifically,while the RO system performs well under high temperatures,its efficiency decreases sharply at lower temperatures.Membrane capacitive deionization(MCDI)is considered as an emergent and promising technology for brackish water desalination.While plenty of studies have been devoted to investigating the impacts of raw water properties(e.g.,salinity,coexisting ions,and natural organic matter)on MCDI performance,the role of water temperatures during the desalination remains under-explored.In this study,we first tested and determined the optimized MCDI operation parameters,such as the cell voltage and feedwater flow rate.Key findings showed that MCDI’s salt removal efficiency remains unaffected by feedwater temperature fluctuations.However,as feedwater temperature increases from 15℃to 40℃,the specific energy consumption for desalination slightly rises by 16.3%,and current efficiency drops by 14.1%.Compared to RO systems,the resilience of MCDI to temperature fluctuations makes it a preferable choice for brackish water treatment in areas with a large temperature difference.展开更多
Two anaerobic ammonia oxidation(anammox)systems,one with adding nano-scale zerovalent iron modified biochar(nZVI@BC)and the other with adding biochar,were constructed to explore the feasibility of nZVI@BC for enhancin...Two anaerobic ammonia oxidation(anammox)systems,one with adding nano-scale zerovalent iron modified biochar(nZVI@BC)and the other with adding biochar,were constructed to explore the feasibility of nZVI@BC for enhancing the resistance of low-nitrogen anammox processes to low temperatures.The results showed that the average nitrogen removal efficiency with nZVI@BC addition at lowtemperatureswas maintained at about 80%,while that with biochar addition gradually decreased to 69.49%.The heme-c content of biomass with nZVI@BC was significantly higher by 36.60%-91.45%.Additional,nZVI@BC addition resulted in more extracellular polymeric substances,better biomass granulation,and a higher abundance of anammox bacteria.In particularly,anammox genes hzsA/B/C,hzo and hdh played a pivotal role in maintaining nitrogen removal performance at 15℃.These findings suggest that nZVI@BC has the potential to enhance the resistance of low-nitrogen anammox processes to low temperatures,making it a valuable approach for practical applications in low-nitrogen and low-temperature wastewater treatment.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
Negative Poisson ratio(NPR)steel is a new material with high strength and toughness.This study conducted tensile tests at elevated temperatures to investigate the mechanical properties of NPR steel at high temperature...Negative Poisson ratio(NPR)steel is a new material with high strength and toughness.This study conducted tensile tests at elevated temperatures to investigate the mechanical properties of NPR steel at high temperatures.The stress−strain curve,ultimate strength,yield strength,modulus of elasticity,elongation after fracture,and percentage reduction of area of NPR steel bars were measured at 9 different temperatures ranging from 20 to 800℃.The experimental results indicate that high-temperature environments significantly affect the mechanical properties of NPR steel.However,compared to other types of steel,NPR steel exhibits better resistance to deformation.When the test temperature is below 700℃,NPR steel exhibits a ductile fracture characteristic,while at 800℃,it exhibits a brittle fracture characteristic.Finally,based on the experimental findings,a constitutive model suitable for NPR steel at high temperatures is proposed.展开更多
Cobalt-free nickel-manganese binary materials are one of the most promising cathode candidates for lithium-ion batteries due to the low reserves, high price,political and ecological unfriendliness of cobalt. The prepa...Cobalt-free nickel-manganese binary materials are one of the most promising cathode candidates for lithium-ion batteries due to the low reserves, high price,political and ecological unfriendliness of cobalt. The preparation of high-performance Ni-Mn bimetallic materials through controlled synthesis conditions holds significant importance for industrial applications. In this work,through systematic modulation of calcination temperatures and nickel ratios, we have effectively addressed critical challenges in binary layered cathodes, including cationic disordering, detrimental H2-H3 phase transitions, and severe interfacial side reactions. The electrochemical performance and thermal stability tests demonstrate that the medium-nickel cathode calcined at 850℃(NM64) exhibit superior comprehensive performance, including moderate discharge capacity(181.34 mAh g^(-1)at 1C), enhanced thermal stability and cycling stability(90% capacity retention after 100 cycles), excellent rate performance(125 mAh g^(-1)at high rate of 10C). Moreover, a 10 kg sample was prepared further verified its commercial application prospects. The soft-pack battery with commercial graphite anode and NM64-850 cathode achieve a discharge capacity of 171.0 mAh g^(-1)and retains 86.5% capacity after 180 cycles. The optimized integration of nickel content and calcination temperature endows binary cathodes with balanced electrochemical performance,enabling commercial viability.展开更多
Urban vegetation plays a crucial role in regulating temperatures and heat waves in urban areas.However,the influence of vegetation coverage and its configuration on surface temperatures in different climate zones at a...Urban vegetation plays a crucial role in regulating temperatures and heat waves in urban areas.However,the influence of vegetation coverage and its configuration on surface temperatures in different climate zones at a national scale is unclear.To address this,we utilized high-resolution data to detect spatial patterns for 31 provincial capital cities in China.We integrated day and night surface temperatures to determine the influence of vegetative coverage and configuration on urban temperatures across different climate zones and city sizes.Our study revealed that a subtropical monsoon climate and medium-sized cities had the highest vegetative coverage and shape complexity.The best connectivity and agglomeration of vegetation were found in a temperate monsoon climate and large cities.In contrast,small cities,especially those under a temperate continental climate,had low vegetation coverage,high fragmentation,and weak agglomeration and connectivity.In addition,vegetative coverage had a negative impact on daytime surface temperatures,especially in large cities in a subtropical monsoon climate.However,an increase in vegetation coverage could result in warming at night in small cities in temperate continental climates.Although urban vegetation configuration also contributed to moderating surface temperatures,especially at night,they did not surpass the influence of vegetation coverage.The effect on nighttime temperatures of the configuration of vegetation increased by 3–6%relative to that of daytime temperatures,especially in large cities in a temperate monsoon climate.The contribution vegetation coverage and configuration interaction to cooling efficiency decreased at night,especially in medium-sized cities in a temperate continental climate by 3–5%.In addition,this study identified several moderating effects of natural and social factors on the relationship between urban vegetation coverage and surface temperatures.High duration of sunshine,low humidity and high wind speed significantly enhanced the negative impact of vegetation coverage on surface temperatures.In addition,the moderating effect of vegetation coverage was more pronounced in low population density cities and high gross domestic product.This study enhances understanding of the ecological functions of urban vegetation and provides a valuable scientific basis and strategic recommendations for optimizing urban vegetation and improving urban environmental quality.展开更多
BACKGROUND:Fever in patients can provide an important clue to the etiology of a patient's symptoms.Non-invasive temperature sites(oral,axillary,temporal) may be insensitive due to a variety of factors.This has not...BACKGROUND:Fever in patients can provide an important clue to the etiology of a patient's symptoms.Non-invasive temperature sites(oral,axillary,temporal) may be insensitive due to a variety of factors.This has not been well studied in adult emergency department patients.To determine whether emergency department triage temperatures detected fever adequately when compared to a rectal temperature.METHODS:A retrospective chart review was made of 27 130 adult patients in a high volume,urban emergency department over an eight-year period who received first a non-rectal triage temperature and then a subsequent rectal temperature.RESULTS:The mean difference in temperatures between the initial temperature and the rectal temperature was 1.3 °F(P<0.001),with 25.9%of the patients having higher rectal temperatures >2°F,and 5.0%having higher rectal temperatures >4 °F.The mean difference among the patients who received oral,axillary,and temporal temperatures was 1.2 °F(PO.001),1.8 °F(PO.001),and 1.2 °F(P<0.001) respectively.About 18.1%of the patients were initially afebrile and found to be febrile by rectal temperature,with an average difference of 2.5 °F(P<0.001).These patients had a higher rate of admission(61.4%,P<0.005),and were more likely to be admitted to the hospital for a higher level of care,such as an intensive care unit,when compared with the full cohort(12.5%vs.5.8%,P<0.005).CONCLUSIONS:There are significant differences between rectal temperatures and noninvasive triage temperatures in this emergency department cohort.In almost one in five patients,fever was missed by triage temperature.展开更多
An equation of state(EOS)was obtained that accurately describes the thermodynamics of the system H_(2)O–CO_(2) at temperatures of 50–350°C and pressures of 0.2–3.5 kbar.The equation is based on experimental da...An equation of state(EOS)was obtained that accurately describes the thermodynamics of the system H_(2)O–CO_(2) at temperatures of 50–350°C and pressures of 0.2–3.5 kbar.The equation is based on experimental data on the compositions of the coexisting liquid and gas phases and the Van Laar model,within which the values of the Van Laar parameters A12 and A21 were found for each experimental P-T point.For the resulting sets A12(P,T),A21(P,T),approximation formulas describing the dependences of these quantities on temperature and pressure were found and the parameters contained in the formulas were fitted.This two-stage approach made it possible to obtain an adequate thermodynamic description of the system,which allows,in addition to determining the phase state of the system(homogeneous or heterogeneous),to calculate the excess free energy of mixing of H_(2)O and CO_(2),the activities of H_(2)O and CO_(2),and other thermodynamic characteristics of the system.The possibility of such calculations creates the basis for using the obtained EOS in thermodynamic models of more complicated fluid systems in P-T conditions of the middle and upper crust.These fluids play an important role in many geological processes including the transport of ore matter and forming hydrothermal ore deposits,in particular,the most of the world’s gold deposits.The knowledge of thermodynamics of these fluids is important in the technology of drilling oil and gas wells.In particular,this concerns the prevention of precipitation of solid salts in the well.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
Gifford-McMahon-type pulse-tube cryocoolers(GM-PTCs)working at liquid helium temperatures are promising in quantum technology and cryogenic physics for their high reliability and minimal vibration.These features stem ...Gifford-McMahon-type pulse-tube cryocoolers(GM-PTCs)working at liquid helium temperatures are promising in quantum technology and cryogenic physics for their high reliability and minimal vibration.These features stem from the fact that there are no extra moving parts introduced into the system.The rotary valve is a key component in GM-PTCs that transfers the output exergy from the compressor to the cold head.Because a low Carnot efficiency of 1.58%is achieved at liquid helium temperatures,optimizing the rotary valve is crucial for improving the efficiency of GM-PTCs.In this regard,an exergy-loss analysis method is proposed in this paper to quantitatively obtain the leakage loss and viscosity loss of a rotary valve by experimental measurements.The results show that viscosity loss accounts for more than 97.5%of the total exergy loss in the rotary valve,and that it is possible to improve the structure of the rotary valve by expanding the flow area by 1.5 times.To verify the method,the cooling temperature and power of a remote two-stage GM-PTC were monitored,with original or optimized rotary valves installed.The experimental results show that compared to the original rotary valve,the optimized rotary valve can improve the cooling efficiency of a GM-PTC by 16.4%,with a cooling power of 0.78 W at 4.2 K.展开更多
Sodium-ion batteries have emerged as competitive substitutes for low-temperature applications due to severe capacity loss and safety concerns of lithium-ion batteries at−20°C or lower.However,the key capability o...Sodium-ion batteries have emerged as competitive substitutes for low-temperature applications due to severe capacity loss and safety concerns of lithium-ion batteries at−20°C or lower.However,the key capability of ultrafast charging at ultralow temperature for SIBs is rarely reported.Herein,a hybrid of Bi nanoparticles embedded in carbon nanorods is demonstrated as an ideal material to address this issue,which is synthesized via a high temperature shock method.Such a hybrid shows an unprecedented rate performance(237.9 mAh g^(−1) at 2 A g^(−1))at−60℃,outperforming all reported SIB anode materials.Coupled with a Na_(3)V_(2)(PO_(4))_(3)cathode,the energy density of the full cell can reach to 181.9 Wh kg^(−1) at−40°C.Based on this work,a novel strategy of high-rate activation is proposed to enhance performances of Bi-based materials in cryogenic conditions by creating new active sites for interfacial reaction under large current.展开更多
Heating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere,despite the transition from an El Ni?o to neutral conditions. In 2024, both global sea surface temper...Heating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere,despite the transition from an El Ni?o to neutral conditions. In 2024, both global sea surface temperature(SST) and upper2000 m ocean heat content(OHC) reached unprecedented highs in the historical record. The 0–2000 m OHC in 2024exceeded that of 2023 by 16 ± 8 ZJ(1 Zetta Joules = 1021 Joules, with a 95% confidence interval)(IAP/CAS data), which is confirmed by two other data products: 18 ± 7 ZJ(CIGAR-RT reanalysis data) and 40 ± 31 ZJ(Copernicus Marine data,updated to November 2024). The Indian Ocean, tropical Atlantic, Mediterranean Sea, North Atlantic, North Pacific, and Southern Ocean also experienced record-high OHC values in 2024. The global SST continued its record-high values from2023 into the first half of 2024, and declined slightly in the second half of 2024, resulting in an annual mean of 0.61°C ±0.02°C(IAP/CAS data) above the 1981–2010 baseline, slightly higher than the 2023 annual-mean value(by 0.07°C ±0.02°C for IAP/CAS, 0.05°C ± 0.02°C for NOAA/NCEI, and 0.06°C ± 0.11°C for Copernicus Marine). The record-high values of 2024 SST and OHC continue to indicate unabated trends of global heating.展开更多
The influence of pouring temperature and mold temperature on the fluidity and hot tearing behavior of Al-2Li-2Cu-0.5Mg-0.15Sc-0.1Zr-0.1Ti alloys was investigated by experimental investigation and simulation assessment...The influence of pouring temperature and mold temperature on the fluidity and hot tearing behavior of Al-2Li-2Cu-0.5Mg-0.15Sc-0.1Zr-0.1Ti alloys was investigated by experimental investigation and simulation assessment.The results showed that the length of the spiral fluidity sample increases from 302 to 756 mm as the pouring temperature increases from 680 to 740℃,and from 293 to 736 mm as the mold temperature increases from 200 to 400℃.The hot tearing susceptibility(HTS)firstly decreases and then increases with increasing pouring and mold temperatures,which is mainly caused by the oxide inclusion originating from the high activity of Li at excessive pouring temperature.Excessive pouring and mold temperatures easily produce oxide inclusions and holes,leading to a reduction in fluidity and an increase in HTS of the alloy.Combining the experimental and simulation results,the optimized pouring and mold temperatures are~720℃ and~300℃ for the cast Al-Li alloy,respectively.展开更多
Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow.The behavior of grout,often highly temperature dependent...Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow.The behavior of grout,often highly temperature dependent,is likely to be affected by the elevated ground temperature in deep rock masses.This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting.The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8.When the temperature is up to 35°C,there can be significant improvements in rheological parameters,acceleration of grout setting,and increase in the rheological time dependence of thick cement grout;however,there may also be a slight impact on the initial grout flowability and the nature of shear thinning.The high temperature may still improve the stability of fresh cement grout and also improve the porosity and creep deformation of hardened cement grout considerably.The proposed constitutive model that couples the Burgers model with a fractional derivativebased Abel dashpot in the series can be used to characterize the creep behavior of hardened cement grout appropriately.The paper provides a valuable reference for optimization of mixture design of cement grouts,thus enhancing deep rock grouting quality and improving safety.展开更多
High-temperature performance of energy storage dielectric polymers is desired for many electronics and electrical applications,but the trade-off between energy density and temperature stability remains fundamentally c...High-temperature performance of energy storage dielectric polymers is desired for many electronics and electrical applications,but the trade-off between energy density and temperature stability remains fundamentally challenging.Here,we report a general material design strategy to enhance energy storage performance at high temperatures by crosslinking a polar polymer and a high glass-transition temperature polymer as a crosslinked binary blend.Such crosslinked binary polymers display a temperature-insensitive and high energy density behavior of about6.2~8.5 J cm^(-3) up to 110℃,showing a significant enhancement in thermal resistant properties and consequently outperforming most of the other ferroelectric polymers.Further microstructural investigations reveal that the improved thermal stability stems from the confinement effect on conformational motion of the crosslinking network,which is evidenced by the increased rigid amorphous fraction and steady intermolecular distance of amorphous regions from temperature-dependent X-ray diffraction results.Our findings provide a general and straightforward strategy to attain temperature-stable,high-energy-density polymer-based dielectrics for energy storage capacitors.展开更多
The performance of welded Ni-based superalloys at high temperatures is essential to be evaluated due to their particular service environment for aero-engines and high-speed aircrafts.The tensile properties and related...The performance of welded Ni-based superalloys at high temperatures is essential to be evaluated due to their particular service environment for aero-engines and high-speed aircrafts.The tensile properties and related microstructural evolutions such as the carbide precipitate and grain of a laser-welded Ni-based alloy were experimentally and numerically investigated at different temperatures(20,300,500,800℃).The results show that at room temperature,the strength of the Base Material(BM)was slightly smaller,with a difference of less than 1%,than the Welded Material(WM),which can be attributed to the more uniformly distributed needle-shaped carbide precipitates in the WM than those nonuniformly coarser spherical ones in the BM.While at 300℃ and 500℃,the strength of WM decreased more obviously compared with that of BM due to the more apparent growth of grain:13.52%loss in yield strength in WM alloys as compared with BM alloys at 300℃,and 16.57% at 500℃.At 800℃,the strength of BM and WM both decreased to a similar level due to Dynamic Recrystallization(DRX).However,a much higher elongation was observed for the BM than WM(less than 50%of BM),which can be attributed to the enhanced dislocation accumulation capability of the large spherical carbides along grain boundaries on the fracture surface in BM.Furthermore,a unified model considering the welding effects on both microstructures(dislocation,carbides,and grain)and mechanical properties evolutions at different temperatures was developed and validated.Based on this model,the key temperature ranges(20–600℃)where apparent weakening of strength and uniform plasticity occurs for welded structures were identified,providing a direct guidance for potential structure and process design.展开更多
Bismuth-doped antimony tungstate(Bi-doped Sb_(2)WO_(6))microspheres were synthesized via a novel hydrothermal synthesis approach.These microspheres were then used as active layers in gas sensors for the detection of c...Bismuth-doped antimony tungstate(Bi-doped Sb_(2)WO_(6))microspheres were synthesized via a novel hydrothermal synthesis approach.These microspheres were then used as active layers in gas sensors for the detection of carbon dioxide(CO_(2)),a significant greenhouse gas and a critical parameter for evaluating air quality.The incorporation of bismuth significantly enhances the gas-sensing performance of the Sb_(2)WO_(6)microspheres,with the 4%Bidoped sensing active layer achieving a remarkable response value of 15 when exposed to 200 ppm of CO_(2),outperforming the undoped Sb_(2)WO_(6).Furthermore,the selectivity of the 4%Bi-Sb_(2)WO_(6)sensor toward CO_(2)gas was enhanced relative to the Sb_(2)WO_(6)sensor.The fundamental mechanisms of gas sensing and the factors contributing to the improved CO_(2)response of 4%Bi-Sb_(2)WO_(6)micro spheres were investigated using density functional theory.Bi-doped Sb_(2)WO_(6)materials exhibit significant advantages in gas-sensing applications,including improved conductivity,enhanced gas adsorption capacity,increased reaction rates,good chemical stability,excellent selectivity,and the ability to adjust electron density.These characteristics enable Bi-doped Sb_(2)WO_(6)to demonstrate higher sensitivity and rapid response capabilities in gas sensors,making it suitable for practical applications.展开更多
基金supported by the National Key R&D Program of China(No.2022YFB3803400)National Natural Science Foundation of China(Nos.52102054,52020105010,51927803,52188101 and 52072378)+1 种基金Liaoning Province Science and Technology Planning Project(No.2022-BS-007)Fujian Science and Technology Program(No.2023T3025).
文摘Commercial carbonate electrolytes suffer from ion transport difficulty in bulk electrolytes and interphase at low temperatures,bringing challenges to the application of lithium-ion batteries(LIBs)at low temperatures.Herein,the ester solvent of methyl propionate(MP)with low melting point and low viscosity was used to tackle ion transport difficulty in electrolytes.Fluorinated ester was further added to accelerate interfacial transport through intermolecular interactions.The influence of fluorinated esters with different fluorination degrees on the solvation structure of electrolytes and the performance of batteries was further studied.As a result,methyl pentafluoropropionate(M5F)with five fluorine atoms was selected for its optimal interactions with both Li+and MP solvent in the primary solvation structure,contributing to desired solvation structure for fast interfacial transport.The LiFePO4(LFP)||graphite cell with LiFSI-MP-M5F electrolyte exhibited a high cyclability of 85.8%after 120 cycles and retained 81.2%of room-temperature capacity when charged and discharged at−30℃.1 Ah LFP||graphite pouch cell with high cathode loading(20 mg/cm^(2))in LiFSI-MP-M5F electrolyte exhibited 0.85 Ah capacity when charged and discharged at−20℃.This work provides a guidance for electrolyte design by synergistic fluorinated and non-fluorinated solvents for LIBs at low-temperature application.
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 the Major Research Development Program of Hubei Province,China(Grant Nos.2022BAA093 and 2022BAD163)the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.SKLGME023008).
文摘With the growing global demand for energy,deep underground salt caverns are emerging as a potential solution for large-scale energy storage.In this study,multistage cyclic loading tests were conducted on rock salt at different temperatures in combination with real-time acoustic emission(AE)monitoring.The results show that the cumulative AE count increases stepwise with increasing cyclic stress.The peak frequency is concentrated primarily in the medium-frequency range,exhibiting a band distribution across low-,medium-,and high-frequency ranges.As the temperature increases,the proportion of low-frequency signals decreases from 14.32%to 5.76%,whereas the proportion of medium-frequency signals increases from 85.48%to 94.1%.The proportion of high-frequency signals remains relatively constant between 0.1%and 0.2%.The amplitude-count relationship of the AE signals demonstrates a strong negative power-law correlation.Furthermore,with increasing temperature,the negative power-law exponent of the amplitude gradually decreases,with the b value decreasing from 1.096 to 0.837 and the a value decreasing from 7.4871 to 6.6982.Under all four temperature conditions,the dominant failure mode in rock salt is tensile cracking.However,as the temperature increases,the proportion of tensile cracks decreases from 88.59%to 75.12%,whereas the proportion of shear cracks at 80℃is nearly double that at 20℃.This finding indicates that as the temperature increases,the ductility of the material increases,and the crack propagation mode shifts from tensile to shear.This research provides valuable insights for the design and stability assessment of salt cavern reservoirs for deep underground energy storage systems.
基金supported by the National Natural Science Foundation of China(Nos.52370090,52300016)China Postdoctoral Science Foundation(Nos.2023M733379,2024M753122).
文摘Raw water temperature can fluctuate significantly throughout the year,with peaks above 30℃in summer and below 15℃in winter.Traditional desalination systems(e.g.,reverse osmosis,RO)face challenges under these varying temperature conditions.Specifically,while the RO system performs well under high temperatures,its efficiency decreases sharply at lower temperatures.Membrane capacitive deionization(MCDI)is considered as an emergent and promising technology for brackish water desalination.While plenty of studies have been devoted to investigating the impacts of raw water properties(e.g.,salinity,coexisting ions,and natural organic matter)on MCDI performance,the role of water temperatures during the desalination remains under-explored.In this study,we first tested and determined the optimized MCDI operation parameters,such as the cell voltage and feedwater flow rate.Key findings showed that MCDI’s salt removal efficiency remains unaffected by feedwater temperature fluctuations.However,as feedwater temperature increases from 15℃to 40℃,the specific energy consumption for desalination slightly rises by 16.3%,and current efficiency drops by 14.1%.Compared to RO systems,the resilience of MCDI to temperature fluctuations makes it a preferable choice for brackish water treatment in areas with a large temperature difference.
基金supported by the China Postdoctoral Science Foundation(No.2020M671624)the State Key Laboratory of Pollution Control and Resource Reuse(No.PCRRF20011).
文摘Two anaerobic ammonia oxidation(anammox)systems,one with adding nano-scale zerovalent iron modified biochar(nZVI@BC)and the other with adding biochar,were constructed to explore the feasibility of nZVI@BC for enhancing the resistance of low-nitrogen anammox processes to low temperatures.The results showed that the average nitrogen removal efficiency with nZVI@BC addition at lowtemperatureswas maintained at about 80%,while that with biochar addition gradually decreased to 69.49%.The heme-c content of biomass with nZVI@BC was significantly higher by 36.60%-91.45%.Additional,nZVI@BC addition resulted in more extracellular polymeric substances,better biomass granulation,and a higher abundance of anammox bacteria.In particularly,anammox genes hzsA/B/C,hzo and hdh played a pivotal role in maintaining nitrogen removal performance at 15℃.These findings suggest that nZVI@BC has the potential to enhance the resistance of low-nitrogen anammox processes to low temperatures,making it a valuable approach for practical applications in low-nitrogen and low-temperature wastewater treatment.
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Projects(41702320,52104125)supported by the National Natural Science Foundation of ChinaProject(ZR2021MD005)+2 种基金supported by the Natural Science Foundation of Shandong Province,ChinaProject(TMduracon2022002)supported by the Engineering Research Center of Marine Environmental Concrete Technology,Ministry of Education,China。
文摘Negative Poisson ratio(NPR)steel is a new material with high strength and toughness.This study conducted tensile tests at elevated temperatures to investigate the mechanical properties of NPR steel at high temperatures.The stress−strain curve,ultimate strength,yield strength,modulus of elasticity,elongation after fracture,and percentage reduction of area of NPR steel bars were measured at 9 different temperatures ranging from 20 to 800℃.The experimental results indicate that high-temperature environments significantly affect the mechanical properties of NPR steel.However,compared to other types of steel,NPR steel exhibits better resistance to deformation.When the test temperature is below 700℃,NPR steel exhibits a ductile fracture characteristic,while at 800℃,it exhibits a brittle fracture characteristic.Finally,based on the experimental findings,a constitutive model suitable for NPR steel at high temperatures is proposed.
基金supported by the National Natural Science Foundation of China(Nos.52074113,22005091 and 22005092)Shanxi Province Transformation Program of Scientific and Technological Achievements(No.202304021301032)+8 种基金the Fundamental Research Program of Shanxi Province(No.202403021211075)Hunan University Outstanding Youth Science Foundation(No.531118040319)The science and technology innovation Program of Hunan Province(No.2021RC3055)Changsha Municipal Natural Science Foundation(No.43184)the CITIC Metals Ningbo Energy Co.Ltd.(No.H202191380246)Chongqing Talents:Exceptional Young Talents Project(No.CQYC202105015)Shenzhen Virtual University Park Basic Research Project of Free exploration(No.2021Szvup036)the National Key Research and Development Program of China(No.2022YFB2402400)Shenzhen Virtual University Park Basic Research Project of Free exploration(No.2021Szvup036)
文摘Cobalt-free nickel-manganese binary materials are one of the most promising cathode candidates for lithium-ion batteries due to the low reserves, high price,political and ecological unfriendliness of cobalt. The preparation of high-performance Ni-Mn bimetallic materials through controlled synthesis conditions holds significant importance for industrial applications. In this work,through systematic modulation of calcination temperatures and nickel ratios, we have effectively addressed critical challenges in binary layered cathodes, including cationic disordering, detrimental H2-H3 phase transitions, and severe interfacial side reactions. The electrochemical performance and thermal stability tests demonstrate that the medium-nickel cathode calcined at 850℃(NM64) exhibit superior comprehensive performance, including moderate discharge capacity(181.34 mAh g^(-1)at 1C), enhanced thermal stability and cycling stability(90% capacity retention after 100 cycles), excellent rate performance(125 mAh g^(-1)at high rate of 10C). Moreover, a 10 kg sample was prepared further verified its commercial application prospects. The soft-pack battery with commercial graphite anode and NM64-850 cathode achieve a discharge capacity of 171.0 mAh g^(-1)and retains 86.5% capacity after 180 cycles. The optimized integration of nickel content and calcination temperature endows binary cathodes with balanced electrochemical performance,enabling commercial viability.
基金supported by the National Natural Science Foundation of China(42171109,32130068)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2020237)National Key R&D Program of China(2023YFF1304604).
文摘Urban vegetation plays a crucial role in regulating temperatures and heat waves in urban areas.However,the influence of vegetation coverage and its configuration on surface temperatures in different climate zones at a national scale is unclear.To address this,we utilized high-resolution data to detect spatial patterns for 31 provincial capital cities in China.We integrated day and night surface temperatures to determine the influence of vegetative coverage and configuration on urban temperatures across different climate zones and city sizes.Our study revealed that a subtropical monsoon climate and medium-sized cities had the highest vegetative coverage and shape complexity.The best connectivity and agglomeration of vegetation were found in a temperate monsoon climate and large cities.In contrast,small cities,especially those under a temperate continental climate,had low vegetation coverage,high fragmentation,and weak agglomeration and connectivity.In addition,vegetative coverage had a negative impact on daytime surface temperatures,especially in large cities in a subtropical monsoon climate.However,an increase in vegetation coverage could result in warming at night in small cities in temperate continental climates.Although urban vegetation configuration also contributed to moderating surface temperatures,especially at night,they did not surpass the influence of vegetation coverage.The effect on nighttime temperatures of the configuration of vegetation increased by 3–6%relative to that of daytime temperatures,especially in large cities in a temperate monsoon climate.The contribution vegetation coverage and configuration interaction to cooling efficiency decreased at night,especially in medium-sized cities in a temperate continental climate by 3–5%.In addition,this study identified several moderating effects of natural and social factors on the relationship between urban vegetation coverage and surface temperatures.High duration of sunshine,low humidity and high wind speed significantly enhanced the negative impact of vegetation coverage on surface temperatures.In addition,the moderating effect of vegetation coverage was more pronounced in low population density cities and high gross domestic product.This study enhances understanding of the ecological functions of urban vegetation and provides a valuable scientific basis and strategic recommendations for optimizing urban vegetation and improving urban environmental quality.
文摘BACKGROUND:Fever in patients can provide an important clue to the etiology of a patient's symptoms.Non-invasive temperature sites(oral,axillary,temporal) may be insensitive due to a variety of factors.This has not been well studied in adult emergency department patients.To determine whether emergency department triage temperatures detected fever adequately when compared to a rectal temperature.METHODS:A retrospective chart review was made of 27 130 adult patients in a high volume,urban emergency department over an eight-year period who received first a non-rectal triage temperature and then a subsequent rectal temperature.RESULTS:The mean difference in temperatures between the initial temperature and the rectal temperature was 1.3 °F(P<0.001),with 25.9%of the patients having higher rectal temperatures >2°F,and 5.0%having higher rectal temperatures >4 °F.The mean difference among the patients who received oral,axillary,and temporal temperatures was 1.2 °F(PO.001),1.8 °F(PO.001),and 1.2 °F(P<0.001) respectively.About 18.1%of the patients were initially afebrile and found to be febrile by rectal temperature,with an average difference of 2.5 °F(P<0.001).These patients had a higher rate of admission(61.4%,P<0.005),and were more likely to be admitted to the hospital for a higher level of care,such as an intensive care unit,when compared with the full cohort(12.5%vs.5.8%,P<0.005).CONCLUSIONS:There are significant differences between rectal temperatures and noninvasive triage temperatures in this emergency department cohort.In almost one in five patients,fever was missed by triage temperature.
基金funded by the Research program FMUW-2021-0002 of the IPGG RAS.
文摘An equation of state(EOS)was obtained that accurately describes the thermodynamics of the system H_(2)O–CO_(2) at temperatures of 50–350°C and pressures of 0.2–3.5 kbar.The equation is based on experimental data on the compositions of the coexisting liquid and gas phases and the Van Laar model,within which the values of the Van Laar parameters A12 and A21 were found for each experimental P-T point.For the resulting sets A12(P,T),A21(P,T),approximation formulas describing the dependences of these quantities on temperature and pressure were found and the parameters contained in the formulas were fitted.This two-stage approach made it possible to obtain an adequate thermodynamic description of the system,which allows,in addition to determining the phase state of the system(homogeneous or heterogeneous),to calculate the excess free energy of mixing of H_(2)O and CO_(2),the activities of H_(2)O and CO_(2),and other thermodynamic characteristics of the system.The possibility of such calculations creates the basis for using the obtained EOS in thermodynamic models of more complicated fluid systems in P-T conditions of the middle and upper crust.These fluids play an important role in many geological processes including the transport of ore matter and forming hydrothermal ore deposits,in particular,the most of the world’s gold deposits.The knowledge of thermodynamics of these fluids is important in the technology of drilling oil and gas wells.In particular,this concerns the prevention of precipitation of solid salts in the well.
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supported by the National Key Research&Development Program of China(No.2023YFF0721304)the Key Research&Development Program of Jiangsu Province(No.2021015-4),China。
文摘Gifford-McMahon-type pulse-tube cryocoolers(GM-PTCs)working at liquid helium temperatures are promising in quantum technology and cryogenic physics for their high reliability and minimal vibration.These features stem from the fact that there are no extra moving parts introduced into the system.The rotary valve is a key component in GM-PTCs that transfers the output exergy from the compressor to the cold head.Because a low Carnot efficiency of 1.58%is achieved at liquid helium temperatures,optimizing the rotary valve is crucial for improving the efficiency of GM-PTCs.In this regard,an exergy-loss analysis method is proposed in this paper to quantitatively obtain the leakage loss and viscosity loss of a rotary valve by experimental measurements.The results show that viscosity loss accounts for more than 97.5%of the total exergy loss in the rotary valve,and that it is possible to improve the structure of the rotary valve by expanding the flow area by 1.5 times.To verify the method,the cooling temperature and power of a remote two-stage GM-PTC were monitored,with original or optimized rotary valves installed.The experimental results show that compared to the original rotary valve,the optimized rotary valve can improve the cooling efficiency of a GM-PTC by 16.4%,with a cooling power of 0.78 W at 4.2 K.
基金supported from Science and Technology Development Program of Jilin Province(Nos.20240101128JC,20230402058GH)National Natural Science Foundation of China(No.52130101).
文摘Sodium-ion batteries have emerged as competitive substitutes for low-temperature applications due to severe capacity loss and safety concerns of lithium-ion batteries at−20°C or lower.However,the key capability of ultrafast charging at ultralow temperature for SIBs is rarely reported.Herein,a hybrid of Bi nanoparticles embedded in carbon nanorods is demonstrated as an ideal material to address this issue,which is synthesized via a high temperature shock method.Such a hybrid shows an unprecedented rate performance(237.9 mAh g^(−1) at 2 A g^(−1))at−60℃,outperforming all reported SIB anode materials.Coupled with a Na_(3)V_(2)(PO_(4))_(3)cathode,the energy density of the full cell can reach to 181.9 Wh kg^(−1) at−40°C.Based on this work,a novel strategy of high-rate activation is proposed to enhance performances of Bi-based materials in cryogenic conditions by creating new active sites for interfacial reaction under large current.
基金supported by the National Key R&D Program of China (Grant No.2023YFF0806500)the International Partnership Program of the Chinese Academy of Sciences (Grant No.060GJHZ2024064MI)+10 种基金the Chinese Academy of Sciences and the National Research Council of Italy Scientific Cooperative Programmethe new Cornerstone Science Foundation through the XPLORER PRIZEthe National Key Scientific and Technological Infrastructure project “Earth System Science Numerical Simulator Facility” (Earth Lab), and Ocean Negative Carbon Emissions (ONCE)sponsored by the US National Science Foundationsupported by the Young Talent Support Project of Guangzhou Association for Science and Technologythe Open Research Cruise NORC2022-10+NORC2022-303 supported by NSFC shiptime Sharing Projects 42149910supported by NASA Awards 80NSSC17K0565, 80NSSC21K1191, and 80NSSC22K0046by the Regional and Global Model Analysis (RGMA) component of the Earth and Environmental System Modeling Program of the U.S.Department of Energy’s Office of Biological & Environmental Research (BER) via National Science Foundation IA 1947282supported by NOAA (Grant No.NA19NES4320002 to CISESS-MD at the University of Maryland)supported by the Austrian Science Fund (P33177)ESA (contract ref.4000145298/24/I-LR)。
文摘Heating in the ocean has continued in 2024 in response to increased greenhouse gas concentrations in the atmosphere,despite the transition from an El Ni?o to neutral conditions. In 2024, both global sea surface temperature(SST) and upper2000 m ocean heat content(OHC) reached unprecedented highs in the historical record. The 0–2000 m OHC in 2024exceeded that of 2023 by 16 ± 8 ZJ(1 Zetta Joules = 1021 Joules, with a 95% confidence interval)(IAP/CAS data), which is confirmed by two other data products: 18 ± 7 ZJ(CIGAR-RT reanalysis data) and 40 ± 31 ZJ(Copernicus Marine data,updated to November 2024). The Indian Ocean, tropical Atlantic, Mediterranean Sea, North Atlantic, North Pacific, and Southern Ocean also experienced record-high OHC values in 2024. The global SST continued its record-high values from2023 into the first half of 2024, and declined slightly in the second half of 2024, resulting in an annual mean of 0.61°C ±0.02°C(IAP/CAS data) above the 1981–2010 baseline, slightly higher than the 2023 annual-mean value(by 0.07°C ±0.02°C for IAP/CAS, 0.05°C ± 0.02°C for NOAA/NCEI, and 0.06°C ± 0.11°C for Copernicus Marine). The record-high values of 2024 SST and OHC continue to indicate unabated trends of global heating.
基金financially supported by the National Natural Science Foundation of China(Nos.51871148,51821001)。
文摘The influence of pouring temperature and mold temperature on the fluidity and hot tearing behavior of Al-2Li-2Cu-0.5Mg-0.15Sc-0.1Zr-0.1Ti alloys was investigated by experimental investigation and simulation assessment.The results showed that the length of the spiral fluidity sample increases from 302 to 756 mm as the pouring temperature increases from 680 to 740℃,and from 293 to 736 mm as the mold temperature increases from 200 to 400℃.The hot tearing susceptibility(HTS)firstly decreases and then increases with increasing pouring and mold temperatures,which is mainly caused by the oxide inclusion originating from the high activity of Li at excessive pouring temperature.Excessive pouring and mold temperatures easily produce oxide inclusions and holes,leading to a reduction in fluidity and an increase in HTS of the alloy.Combining the experimental and simulation results,the optimized pouring and mold temperatures are~720℃ and~300℃ for the cast Al-Li alloy,respectively.
基金The Fundamental Research Funds for the Central Universities,Grant/Award Number:YJ2021148National Natural Science Foundation of China,Grant/Award Number:52374132。
文摘Appropriate determination of the mix ratios of cement grouts is of vital importance to the quality of rock grouting and the risk reduction of groundwater inflow.The behavior of grout,often highly temperature dependent,is likely to be affected by the elevated ground temperature in deep rock masses.This paper aims to experimentally gain insights into the effects of elevated ground temperatures on the properties of cement grout in fresh and hardened states in deep rock grouting.The results revealed that a temperature of 35°C is crucial for changes in the properties of thick cement grout with a water–cement ratio of less than 0.8.When the temperature is up to 35°C,there can be significant improvements in rheological parameters,acceleration of grout setting,and increase in the rheological time dependence of thick cement grout;however,there may also be a slight impact on the initial grout flowability and the nature of shear thinning.The high temperature may still improve the stability of fresh cement grout and also improve the porosity and creep deformation of hardened cement grout considerably.The proposed constitutive model that couples the Burgers model with a fractional derivativebased Abel dashpot in the series can be used to characterize the creep behavior of hardened cement grout appropriately.The paper provides a valuable reference for optimization of mixture design of cement grouts,thus enhancing deep rock grouting quality and improving safety.
基金supported by the National Natural Science Foundation of China(Grant No.52207031)the National Key R&D Program of China(Grant No.2020YFA0710500)。
文摘High-temperature performance of energy storage dielectric polymers is desired for many electronics and electrical applications,but the trade-off between energy density and temperature stability remains fundamentally challenging.Here,we report a general material design strategy to enhance energy storage performance at high temperatures by crosslinking a polar polymer and a high glass-transition temperature polymer as a crosslinked binary blend.Such crosslinked binary polymers display a temperature-insensitive and high energy density behavior of about6.2~8.5 J cm^(-3) up to 110℃,showing a significant enhancement in thermal resistant properties and consequently outperforming most of the other ferroelectric polymers.Further microstructural investigations reveal that the improved thermal stability stems from the confinement effect on conformational motion of the crosslinking network,which is evidenced by the increased rigid amorphous fraction and steady intermolecular distance of amorphous regions from temperature-dependent X-ray diffraction results.Our findings provide a general and straightforward strategy to attain temperature-stable,high-energy-density polymer-based dielectrics for energy storage capacitors.
基金co-supported by the financial support from the Fundamental Research Funds for the Central Universities,China(Nos.YWF-23-L-1012,YWF-22-L-1017)the National Natural Science Foundation of China(No.52005020)。
文摘The performance of welded Ni-based superalloys at high temperatures is essential to be evaluated due to their particular service environment for aero-engines and high-speed aircrafts.The tensile properties and related microstructural evolutions such as the carbide precipitate and grain of a laser-welded Ni-based alloy were experimentally and numerically investigated at different temperatures(20,300,500,800℃).The results show that at room temperature,the strength of the Base Material(BM)was slightly smaller,with a difference of less than 1%,than the Welded Material(WM),which can be attributed to the more uniformly distributed needle-shaped carbide precipitates in the WM than those nonuniformly coarser spherical ones in the BM.While at 300℃ and 500℃,the strength of WM decreased more obviously compared with that of BM due to the more apparent growth of grain:13.52%loss in yield strength in WM alloys as compared with BM alloys at 300℃,and 16.57% at 500℃.At 800℃,the strength of BM and WM both decreased to a similar level due to Dynamic Recrystallization(DRX).However,a much higher elongation was observed for the BM than WM(less than 50%of BM),which can be attributed to the enhanced dislocation accumulation capability of the large spherical carbides along grain boundaries on the fracture surface in BM.Furthermore,a unified model considering the welding effects on both microstructures(dislocation,carbides,and grain)and mechanical properties evolutions at different temperatures was developed and validated.Based on this model,the key temperature ranges(20–600℃)where apparent weakening of strength and uniform plasticity occurs for welded structures were identified,providing a direct guidance for potential structure and process design.
基金financially supported by the Outstanding Youth Foundation of Jiangsu Province of China(No.BK20211548)Yangzhou Science and Technology Plan Project(No.YZ2023246)+1 种基金China Scholarship Council(No.202308320445)the Postgraduate Research and Practice Innovation Program of Jiangsu Province of China(No.KYCX23_3551)
文摘Bismuth-doped antimony tungstate(Bi-doped Sb_(2)WO_(6))microspheres were synthesized via a novel hydrothermal synthesis approach.These microspheres were then used as active layers in gas sensors for the detection of carbon dioxide(CO_(2)),a significant greenhouse gas and a critical parameter for evaluating air quality.The incorporation of bismuth significantly enhances the gas-sensing performance of the Sb_(2)WO_(6)microspheres,with the 4%Bidoped sensing active layer achieving a remarkable response value of 15 when exposed to 200 ppm of CO_(2),outperforming the undoped Sb_(2)WO_(6).Furthermore,the selectivity of the 4%Bi-Sb_(2)WO_(6)sensor toward CO_(2)gas was enhanced relative to the Sb_(2)WO_(6)sensor.The fundamental mechanisms of gas sensing and the factors contributing to the improved CO_(2)response of 4%Bi-Sb_(2)WO_(6)micro spheres were investigated using density functional theory.Bi-doped Sb_(2)WO_(6)materials exhibit significant advantages in gas-sensing applications,including improved conductivity,enhanced gas adsorption capacity,increased reaction rates,good chemical stability,excellent selectivity,and the ability to adjust electron density.These characteristics enable Bi-doped Sb_(2)WO_(6)to demonstrate higher sensitivity and rapid response capabilities in gas sensors,making it suitable for practical applications.
