With the upgrade of armor protection materials,higher requirements are put forward for the penetration performance of tungsten alloy kinetic energy armor-piercing projectiles,and the penetration performance is closely...With the upgrade of armor protection materials,higher requirements are put forward for the penetration performance of tungsten alloy kinetic energy armor-piercing projectiles,and the penetration performance is closely related to the adiabatic shear band under extreme stress conditions.Here,the detailed analysis of the adiabatic shear band microstructure evolution of a dual-phase 90W-Ni-Fe alloy under a high strain rate was conducted by combining advanced electron microscopic characterization,while discussing shear fracture from a mechanical perspective under thermoplastic instability.The high temperature and high stress environment inside the adiabatic shear band led to the refinement of the W phase andγ-(Ni,Fe)phase grains to the submicron level,and induced the elements redistribution of W,Ni,and Fe to precipitate W nanocrystalline with hardness as high as 11.7 GPa along the recrystallization grain boundaries of theγ-(Ni,Fe)phase.Mechanical incompatibility caused by the hardness difference between W nanocrystalline andγ-(Ni,Fe)phases led to a strain gradient at the interface.The microvoids preferentially nucleated at the W nanocrystalline/γ-(Ni,Fe)phase interface,then merged to form microcracks and grew further,leading to shear failure.展开更多
The accurate establishment of a ferrite transformation start temperature model is crucial to design a reasonable controlled rolling process and ensure uniform microstructure in aluminum bearing dual-phase steel.The me...The accurate establishment of a ferrite transformation start temperature model is crucial to design a reasonable controlled rolling process and ensure uniform microstructure in aluminum bearing dual-phase steel.The measurements of the expansion-temperature curves of aluminum bearing dual-phase steel under continuous cooling and isothermal conditions are presented,utilizing a dynamic transformation dilatometer experiment.Based on these expansion-temperature curves,the start temperature and incubation time of ferrite transformation were determined,elucidating the influence of process parameters on both the incubation time and the start temperature of ferrite transformation.By integrating metallurgical principles with measured incubation time of ferrite transformation,and considering the effects of temperature and strain,a fitting model for the variation in volume free energy during ferrite nucleation was derived.Building upon this foundation,a high-precision incubation time of ferrite transformation mathematical model for the experimental steel was established.To more accurately calculate the start temperature of ferrite transformation under continuous cooling conditions,the Scheil’s additivity rule was modified to account for the effects of deformation and cooling rate.The results indicate that the modification coefficient decreases with increasing the cooling rate and strain,thereby significantly improving the accuracy of calculating the starting temperature of ferrite transformation using the modified additivity rule.展开更多
Litter decomposition is an essential ecosystem process influenced by multiple factors,including substrate quality,climate,edaphic environment,and decomposer communities.However,the role of canopy species identity and ...Litter decomposition is an essential ecosystem process influenced by multiple factors,including substrate quality,climate,edaphic environment,and decomposer communities.However,the role of canopy species identity and diversity on leaf litter decomposition in forests remains understudied.By controlling for macroclimate,soil properties,and litter substrate in a mature common garden,we investigated whether a three-month tea bag incubation of standardized green and rooibos tea substrate is driven by canopy tree species characteristics and diversity.Our study hypothesized two primary pathways:a chemical engineering effect,where trees alter soil properties and decomposer communities through litter input,and a physical engineering effect,where tree canopy structure modulates the local microclimate.The results showed that even under uniform macroclimatic and initial soil conditions,mass loss rates varied widely for green tea(27.4%–73.2%)and rooibos tea(6.1%–34.7%),comparable as found in other research between distinct biomes.While substrate quality was the dominant factor,both engineering pathways and,to a minor extent,tree diversity modulated mass losses.For green tea,tree chemical and physical characteristics seemed equally important,while the physical environment showed an increased importance for rooibos.Incubation depth played a key role,where forest floor decomposition rates are more susceptible to temporal climate variations,and soil-layer decomposition rates are less susceptible to climate variations and more determined by tree species identity.Our findings suggest that tea bag experiments focusing solely on topsoil burial may underestimate processes in the forest floor and the mineralorganic boundary layer.This study underscores the critical role of litter substrate quality in decomposition while demonstrating that tree community composition and the associated herbaceous layer,through both chemical and physical engineering pathways,strongly modulate decomposition rates.展开更多
Objective:Hypertension is a serious public health concern that is influenced by a variety of body composition parameters.This study examines the associations between body composition metrics and blood pressure(BP)in a...Objective:Hypertension is a serious public health concern that is influenced by a variety of body composition parameters.This study examines the associations between body composition metrics and blood pressure(BP)in a rural population,specifically how variations in body fat distribution and other metrics affect systolic blood pressure(SBP)and diastolic blood pressure(DBP).Methods:A cross-sectional study of 226 participants examined the relationships between body composition metrics—such as total body fat,visceral fat,and body mass index(BMI)—and BP.Correlation and regression analyses were used to assess these relationships.Results:The study found substantial positive correlations between visceral fat and total body fat with both SBP and DBP.Visceral fat was strongly connected with both SBP(r=0.145,P=0.030)and DBP(r=0.331,P<0.01),while total body fat was significantly correlated with DBP(r=0.268,P<0.01)but not SBP.Body composition variables explained 12.8% of the variance in SBP(R^(2)=0.128,P=0.001)and 15.0% in DBP(R^(2)=0.150,P<0.001).Conclusions:The study found substantial connections between body composition,particularly visceral and subcutaneous fat and systolic and DBP.Higher levels of visceral fat were linked to elevate BP.Body composition accounted for a significant amount of BP fluctuation.展开更多
Understory plants are an integral part of forests,serving a variety of functions that help maintain healthy ecosystems.The structure and composition of the understory are influenced by numerous biotic and abiotic fact...Understory plants are an integral part of forests,serving a variety of functions that help maintain healthy ecosystems.The structure and composition of the understory are influenced by numerous biotic and abiotic factors,with light being critical.The introduction of the pathogen Cronartium ribicola,which causes white pine blister rust,into North America in the early 20 th century led to the near total loss of western white pine(Pinus monticola)from moist forests of the Northern Rockies.Management is reintroducing blister rust-resistant western white pine across the landscape,but the effects on the understory are unknown.We examined the effects of stand structure and proportion of western white pine in the overstory on understory diversity of vascular plants in closed canopy stands dominated by blister rust-resistant western white pine across northern Idaho.Habitat series explained the greatest amount of variation(34%)in species presence-absence,while canopy cover accounted for 25%,basal area of all trees for 18%,and the proportion of western white pine composition by 14%.Our analysis revealed positive relationships between the proportion of western white pine in the overstory and both the presence of understory plants and the cover of several understory species.For both the presence and cover,separate sets of thirteen species were found to have a positive relationship with the proportion of western white pine in the overstory,with eight species in common.This research fills a knowledge gap by using data from a range of stands across northern Idaho with varying abundance of western white pine in the overstory to evaluate the relationship between the understory and overstory composition.As land managers plant more western white pine trees,we are likely to see the concomitant increase in understory plant diversity across the landscape,in addition to numerous other benefits,including disturbance resistance and resilience.展开更多
This study proposes a multi-scale simplified residual convolutional neural network(MS-SRCNN)for the precise prediction of Mg-Nd binary alloy compositions from scanning electron microscope(SEM)images.A multi-scale data...This study proposes a multi-scale simplified residual convolutional neural network(MS-SRCNN)for the precise prediction of Mg-Nd binary alloy compositions from scanning electron microscope(SEM)images.A multi-scale data structure is established by spatially aligning and stacking SEM images at different magnifications.The MS-SRCNN significantly reduces computational runtime by over 90%compared to traditional architectures like ResNet50,VGG16,and VGG19,without compromising prediction accuracy.The model demonstrates more excellent predictive performance,achieving a>5%increase in R^(2) compared to single-scale models.Furthermore,the MS-SRCNN exhibits robust composition prediction capability across other Mg-based binary alloys,including Mg-La,Mg-Sn,Mg-Ce,Mg-Sm,Mg-Ag,and Mg-Y,thereby emphasizing its generalization and extrapolation potential.This research establishes a non-destructive,microstructure-informed composition analysis framework,reduces characterization time compared to traditional experiment methods and provides insights into the composition-microstructure relationship in diverse material systems.展开更多
Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual st...Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual stress according to Hookers Law. The present work focuses on the lattice strain determination of individual grains in a dual-phase stainless steel （DPSS） by means of differential-aperture X-ray micro-diffraction （DAXM）. The results show that the residual stress only takes part of the responsibility of the total measured lattice strain. In fact, the compositional variation inside the material was found to cause greater strain gradient in both ferrite （c~） and austenite （~） phases in DPSS. Therefore, quantification of compositional and residual stress effects on lattice strain was conducted in order to evaluate the true residual stress inside engineering materials.展开更多
Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships w...Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships with antioxidant activity and oxidative stability,gas chromatography-mass spectrometry was performed to characterize the associated fatty acid profiles.The antioxidant activity of vegetable oils,based on their DPPH-scavenging capacity(expressed as IC_(50) values),was used to assess their impact on human health,and their oxidative stability was characterized by performing lipid oxidation analysis to determine the oxidative induction time of fats and oils.In addition,correlation analyses were performed to examine associations between the fatty acid composition of the oils and DPPH-scavenging capacity and oxidative stability.The results revealed that among the assessed oils,coffee seed oil has the highest saturated fatty acid content(355.10 mg/g),whereas Garddenia jaminoides oil has the highest unsaturated fatty acid content(844.84 mg/g).Coffee seed oil was also found have the lowest DPPH IC_(50) value(2.30 mg/mL)and the longest oxidation induction time(17.09 h).Correlation analysis revealed a significant linear relationship(P<0.05)between oxidative stability and unsaturated fatty acid content,with lower contents tending to be associated with better oxidative stability.The findings of this study provide reference data for the screening of functional edible vegetable oils.展开更多
Brazing filler metals are widely applied,which serve as an industrial adhesive in the joining of dissimilar structures.With the continuous emergence of new structures and materials,the demand for novel brazing filler ...Brazing filler metals are widely applied,which serve as an industrial adhesive in the joining of dissimilar structures.With the continuous emergence of new structures and materials,the demand for novel brazing filler metals is ever-increasing.It is of great significance to investigate the optimized composition design methods and to establish systematic design guidelines for brazing filler metals.This study elucidated the fundamental rules for the composition design of brazing filler metals from a three-dimensional perspective encompassing the basic properties of applied brazing filler metals,formability and processability,and overall cost.The basic properties of brazing filler metals refer to their mechanical properties,physicochemical properties,electromagnetic properties,corrosion resistance,and the wettability and fluidity during brazing.The formability and processability of brazing filler metals include the processes of smelting and casting,extrusion,rolling,drawing and ring-making,as well as the processes of granulation,powder production,and the molding of amorphous and microcrystalline structures.The cost of brazing filler metals corresponds to the sum of materials value and manufacturing cost.Improving the comprehensive properties of brazing filler metals requires a comprehensive and systematic consideration of design indicators.Highlighting the unique characteristics of brazing filler metals should focus on relevant technical indicators.Binary or ternary eutectic structures can effectively enhance the flow spreading ability of brazing filler metals,and solid solution structures contribute to the formability.By employing the proposed design guidelines,typical Ag based,Cu based,Zn based brazing filler metals,and Sn based solders were designed and successfully applied in major scientific and engineering projects.展开更多
An energetic binder based on hydroxyl-terminated polybutadiene(HTPB),doped with different ratios of nitrocellulose(NC)(10%,20%,30%,and 50%),was developed to study the effect of NC doping on the thermal decomposition b...An energetic binder based on hydroxyl-terminated polybutadiene(HTPB),doped with different ratios of nitrocellulose(NC)(10%,20%,30%,and 50%),was developed to study the effect of NC doping on the thermal decomposition behavior of a composite propellant(CP)comprising ammonium nitrate(AN)as an oxidizer and magnesium(Mg)as a fuel.Optimization of the propellant formulation was conducted using Chemical Equilibrium with Applications-National Aeronautics and Space Administration(CEA-NASA)software,which demonstrated an increase in specific impulse by 12.09 s when the binder contained 50%NC.Fourier-transform infrared spectroscopy(FTIR)analysis confirmed the excellent compatibility between the components,and density measurements revealed an increase of 6.4%with a higher NC content.Morphological analysis using optical microscopy showed that NC doping improved the uniformity and compactness of the surface,reduced cavities,and achieved a more homogeneous particle distribution.Differential scanning calorimetry(DSC)analysis indicated a decrease in the decomposition temperature of the propellant as the NC content increased,while kinetic studies revealed a 48.68%reduction in the activation energy when 50%NC was incorporated into the binder.These findings suggest that the addition of NC enhances combustion efficiency and improves overall propellant performance.This study highlights the potential of the new HTPB-NC energetic binder as a promising approach for advancing solid propellant technology.展开更多
Fracture strain becomes critical for the local formability and crash performance of carbody components when the tensile strength exceeds 1000 MPa.Regrettably,high-strength quenching and partitioning(Q&P)steels and...Fracture strain becomes critical for the local formability and crash performance of carbody components when the tensile strength exceeds 1000 MPa.Regrettably,high-strength quenching and partitioning(Q&P)steels and dual-phase(DP)steels always focus on improving the tensile ductility for stretch formability,while ignoring their limited fracture strain.In this work,we explored a novel strategy,i.e.,developing a high fracture strain ferrite-martensite dual-phase steel(HFS-DP)maintaining good strength–ductility balance by suppressing intense strain localization during deformation and enhancing martensite deformability via microstructure design including grain refinement,nano-precipitate hardening in soft ferrite phase,low-carbon and high fraction martensite.HFS-DP demonstrates a remarkable 26%and 47%improvement in tensile ductility and fracture strain,respectively,compared to commercial DP1180 steel with similar ultimate tensile strength.Furthermore,HFS-DP also exhibits a substantial 39%improvement in fracture strain compared to retained austenite-involved commercial QP1180 steel.The detailed processes of strain partitioning,strain localization,and damage formation during deformation were revealed through in-situ scanning electron microscopy(SEM)observation combined with digital image correlation(DIC).The results indicate that the excellent coordinated deformation between ferrite and martensite,coupled with microstructure refinement,effectively suppresses intense strain localization.Moreover,the excellent martensite deformability resulting from the low carbon content also aids in retarding crack formation.This combination effectively suppresses damage initiation and development during deformation,therefore the fracture strain is significantly improved.This study not only contributes to a deeper understanding of the strain localization and damage process during tensile deformation of DP steels,but also provides a new perspective on designing ultrahigh strength steels with high ductility and fracture strain.展开更多
Dual-phase membranes of 60 wt% Ce0.8Gd0.2O2-δ-40 wt% Pr Ba Co2exFexO3 d（0 x 2） were prepared by a combined citrate and ethylene diamine tetraacetic acid（EDTA） complexing method. X-ray diffraction（XRD）results re...Dual-phase membranes of 60 wt% Ce0.8Gd0.2O2-δ-40 wt% Pr Ba Co2exFexO3 d（0 x 2） were prepared by a combined citrate and ethylene diamine tetraacetic acid（EDTA） complexing method. X-ray diffraction（XRD）results revealed the good chemical compatibility between ion-conducting phase CGO and electron-conducting phases PBC2 xFxO after sintering in air. The Fe ionic dopant had a significant effect on the phase structure stability and oxygen permeability under CO2 atmosphere, which was confirmed by XRD, thermogravimetrye differential scanning calorimetry（TGeD SC）, scanning electron microscopy（SEM） and oxygen permeation experiments. CGOeP BC0.5F1.5O dual-phase membrane demonstrated a stable oxygen permeation flux of2.71x10-7mol cm 2s 1with 50 mol% He/CO2 as the sweep gas at 925 C, and this value was much higher than that of perovskite-type membranes. The rate-limiting step in the oxygen permeation process changed from the bulk diffusion to the surface oxygen exchange when the CGOeP BC0.5F1.5O membrane thickness decreased to 0.8 mm or less. Due to the high oxygen permeation fluxes and the excellent structural stability under CO2 atmosphere, the CGOeP BC0.5F1.5O membrane is a great potential candidate material for separating oxygen from air in the oxy-fuel combustion techniques.展开更多
With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electro...With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electronic instruments.Therefore,the design and preparation of electromagnetic absorbing composites represent an efficient approach to mitigate the current hazards of electromagnetic radiation.However,traditional electromagnetic absorbers are difficult to satisfy the demands of actual utilization in the face of new challenges,and emerging absorbents have garnered increasing attention due to their structure and performance-based advantages.In this review,several emerging composites of Mxene-based,biochar-based,chiral,and heat-resisting are discussed in detail,including their synthetic strategy,structural superiority and regulation method,and final optimization of electromagnetic absorption ca-pacity.These insights provide a comprehensive reference for the future development of new-generation electromagnetic-wave absorption composites.Moreover,the potential development directions of these emerging absorbers have been proposed as well.展开更多
Angelica sinensis(A.sinensis),as a kind of Chinese medicine,has the effects of tonifying blood,promoting blood circulation,regulating menstrual flow,relieving pain,moistening bowel and so on.By consulting Sciencedirec...Angelica sinensis(A.sinensis),as a kind of Chinese medicine,has the effects of tonifying blood,promoting blood circulation,regulating menstrual flow,relieving pain,moistening bowel and so on.By consulting Sciencedirect database and Web of Science database,163 related articles were found,of which 36 were related to chemical composition and pharmacological activities of A.sinensis.In this paper,the chemical structures and different derivatives were systematically summarized by reviewing relevant literatures,and the pharmacological effects were also summarized.展开更多
Objective This study aimed to study the effects of different crystalline states of Sheng Shigao(raw gypsum,RG)and its inorganic elements on the antipyretic efficacy of Baihu Decoction(BHT).Methods RG samples calcined ...Objective This study aimed to study the effects of different crystalline states of Sheng Shigao(raw gypsum,RG)and its inorganic elements on the antipyretic efficacy of Baihu Decoction(BHT).Methods RG samples calcined at different temperatures were prepared.The phase composition of RG and Duan Shigao(calcination of gypsum,CG)as well as the changes in phase composition before and after adding water to RG calcined at specific temperatures,were determined using X-ray diffraction(XRD).A fever model was established by subcutaneously injecting 20%yeast suspension(10 mL·kg~(-1))into the backs of rats.The effects of BHT containing RG in different crystalline states on rat body temperature were measured.Serum levels of IL-1β,IL-6,and hypothalamic prostaglandin E2(PGE_2)were detected using ELISA.Serum Ca~(2+)levels were measured using a microplate method.The content of trace elements in RG and CG and the corresponding freeze-dried BHT powder was determined using inductively coupled plasma mass spectrometry(ICP-MS).The complexation of representative inorganic elements with mangiferin,a major active component in BHT,was investigated using UV-Vis spectroscopy and fluorescence spectroscopy.A validation model was established using RAW264.7 mouse macrophages.Drug-containing serum of BHT with different inorganic elements was prepared,and the nitric oxide(NO)levels in the cell supernatant of different treatment groups were measured using the Griess method.The mRNA levels of IL-6,TNF-α,and PGE2in each group were detected using qPCR(real-time fluorescent quantitative PCR).Results After calcination,the phase composition of RG changed,and the content of inorganic elements in RG,CG170(RG calcined at 170°C),and CG350(RG calcined at 350°C)showed similar trends.Compared with RG,the content of Ca,Sr,Al,and Na in CG changed significantly.Compared with BHT,the content of Ca,Sr,Si,and Na in CG changed significantly when incorporated into the formula.Intermolecular interactions confirmed strong binding between mangiferin and Cu~(2+)and Al~(3+).Cu~(2+)and Fe~(3+)exhibited fluorescence quenching effects on mangiferin solution,while Al~(3+)and Zn~(2+)showed strong fluorescence enhancement,with fluorescence intensity increasing by 120-fold and 30-fold,respectively.In vitro evaluation of synergistic anti-inflammatory effects confirmed that Ca,Fe,Cr,Al,and Si exhibited synergistic anti-inflammatory effects.Conclusion The crystalline state of RG has little effect on its antipyretic properties,while Ca,Sr,Na,Fe,and Al are likely the key material bases influencing its efficacy.展开更多
The dual-phase Re_(0.5)MoNbW(TaC)_(0.5) composite,consisting of refractory body-centered cubic(BCC)highentropy alloy and carbide with many fine eutectic structures,was successfully synthesized by arc melting.The phase...The dual-phase Re_(0.5)MoNbW(TaC)_(0.5) composite,consisting of refractory body-centered cubic(BCC)highentropy alloy and carbide with many fine eutectic structures,was successfully synthesized by arc melting.The phase stability,high-temperature mechanical properties and strengthening mechanism of the ascast composite were studied.The microstructure of the composite remained stable after annealing at 1300℃for 168 h.It exhibited remarkably high-temperature strength,yield strength~901 MPa,and true ultimate compressive strength~1186 MPa at 1200℃.The BCC phase and carbide exhibited a semi-coherent interface with good bonding after severe deformation at 1200℃.The dipolar dislocation walls in BCC phase,restricted dynamic interaction between defects in carbide,and the pinning effect of semi-coherent interface offered effective strengthening effects.展开更多
Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions ...Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions affect EMF remain largely unknown.Here,we investigated variation in three measures of diversity(alpha diversity,community composition and network complexity)among rare,intermediate,and abundant taxa across a latitudinal gradient spanning five forest plots in Yunnan Province,China and examined their contributions on EMF.We aimed to characterize the diversity distributions of bacterial groups across latitudes and to assess the differences in the mechanisms underlying their contributions to EMF.We found that multifaceted diversity(i.e.,diversity assessed by the three different metrics)of rare,intermediate,and abundant bacteria generally decreased with increasing latitude.More importantly,we found that rare bacterial taxa tended to be more diverse,but they contributed less to EMF than intermediate or abundant bacteria.Among the three dimensions of diversity we assessed,only community composition significantly affected EMF across all locations,while alpha diversity had a negative effect,and network complexity showed no significant impact.Our study further emphasizes the importance of intermediate and abundant bacterial taxa as well as community composition to EMF and provides a theoretical basis for investigating the mechanisms by which belowground microorganisms drive EMF along a latitudinal gradient.展开更多
Scientific knowledge on the chemical compositions of fine particulate matter(PM_(2.5)) is essential for properly assessing its health and climate effects,and for decisionmakers to develop efficient mitigation strategi...Scientific knowledge on the chemical compositions of fine particulate matter(PM_(2.5)) is essential for properly assessing its health and climate effects,and for decisionmakers to develop efficient mitigation strategies.A high-resolution PM_(2.5) chemical composition dataset(CAQRA-aerosol)is developed in this study,which provides hourly maps of organic carbon,black carbon,ammonium,nitrate,and sulfate in China from 2013 to 2020 with a horizontal resolution of 15 km.This paper describes the method,access,and validation results of this dataset.It shows that CAQRA-aerosol has good consistency with observations and achieves higher or comparable accuracy with previous PM_(2.5) composition datasets.Based on CAQRA-aerosol,spatiotemporal changes of different PM_(2.5) compositions were investigated from a national viewpoint,which emphasizes different changes of nitrate from other compositions.The estimated annual rate of population-weighted concentrations of nitrate is 0.23μg m^(−3)yr^(−1) from 2015 to 2020,compared with−0.19 to−1.1μg m^(−3)yr^(−1) for other compositions.The whole dataset is freely available from the China Air Pollution Data Center(https://doi.org/10.12423/capdb_PKU.2023.DA).展开更多
Nano-AlN and submicron-Al_(2)O_(3) particles were simultaneously utilized in a 6061 Al matrix composite to improve the high-temperature strength.According to the SEM and TEM characterization,nano-AlN and submicron-Al_...Nano-AlN and submicron-Al_(2)O_(3) particles were simultaneously utilized in a 6061 Al matrix composite to improve the high-temperature strength.According to the SEM and TEM characterization,nano-AlN and submicron-Al_(2)O_(3) particles are uniformly distributed in the Al matrix.Brinell hardness results indicate that different from the traditional 6061 Al matrix alloy,the aging kinetics of the composite is obviously accelerated by the reinforcement particles.The T6-treated composite exhibits excellent tensile properties at both room temperature and elevated temperature.Especially at 350℃,the T6-treated composite not only has a high yield strength of 121 MPa and ultimate tensile strength of 128 MPa,but also exhibits a large elongation of 11.6%.Different strengthening mechanisms of nano-AlN and submicron-Al_(2)O_(3) particles were also discussed in detail.展开更多
Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-...Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.展开更多
基金supported by the National Natural Science Foundation of China(No.51931012)the Science and Technology Innovation Program of Hunan Province(No.2023RC3068).
文摘With the upgrade of armor protection materials,higher requirements are put forward for the penetration performance of tungsten alloy kinetic energy armor-piercing projectiles,and the penetration performance is closely related to the adiabatic shear band under extreme stress conditions.Here,the detailed analysis of the adiabatic shear band microstructure evolution of a dual-phase 90W-Ni-Fe alloy under a high strain rate was conducted by combining advanced electron microscopic characterization,while discussing shear fracture from a mechanical perspective under thermoplastic instability.The high temperature and high stress environment inside the adiabatic shear band led to the refinement of the W phase andγ-(Ni,Fe)phase grains to the submicron level,and induced the elements redistribution of W,Ni,and Fe to precipitate W nanocrystalline with hardness as high as 11.7 GPa along the recrystallization grain boundaries of theγ-(Ni,Fe)phase.Mechanical incompatibility caused by the hardness difference between W nanocrystalline andγ-(Ni,Fe)phases led to a strain gradient at the interface.The microvoids preferentially nucleated at the W nanocrystalline/γ-(Ni,Fe)phase interface,then merged to form microcracks and grew further,leading to shear failure.
基金supported by the National Science and Technology Major Project-Intelligent Manufacturing Systems And Robots(2025ZD1602200)the National Key Research and Development Program of China(Grant No.2022YFB3304800).
文摘The accurate establishment of a ferrite transformation start temperature model is crucial to design a reasonable controlled rolling process and ensure uniform microstructure in aluminum bearing dual-phase steel.The measurements of the expansion-temperature curves of aluminum bearing dual-phase steel under continuous cooling and isothermal conditions are presented,utilizing a dynamic transformation dilatometer experiment.Based on these expansion-temperature curves,the start temperature and incubation time of ferrite transformation were determined,elucidating the influence of process parameters on both the incubation time and the start temperature of ferrite transformation.By integrating metallurgical principles with measured incubation time of ferrite transformation,and considering the effects of temperature and strain,a fitting model for the variation in volume free energy during ferrite nucleation was derived.Building upon this foundation,a high-precision incubation time of ferrite transformation mathematical model for the experimental steel was established.To more accurately calculate the start temperature of ferrite transformation under continuous cooling conditions,the Scheil’s additivity rule was modified to account for the effects of deformation and cooling rate.The results indicate that the modification coefficient decreases with increasing the cooling rate and strain,thereby significantly improving the accuracy of calculating the starting temperature of ferrite transformation using the modified additivity rule.
基金funded by the Global PhD Scholarship between KU Leuven and UCLouvain。
文摘Litter decomposition is an essential ecosystem process influenced by multiple factors,including substrate quality,climate,edaphic environment,and decomposer communities.However,the role of canopy species identity and diversity on leaf litter decomposition in forests remains understudied.By controlling for macroclimate,soil properties,and litter substrate in a mature common garden,we investigated whether a three-month tea bag incubation of standardized green and rooibos tea substrate is driven by canopy tree species characteristics and diversity.Our study hypothesized two primary pathways:a chemical engineering effect,where trees alter soil properties and decomposer communities through litter input,and a physical engineering effect,where tree canopy structure modulates the local microclimate.The results showed that even under uniform macroclimatic and initial soil conditions,mass loss rates varied widely for green tea(27.4%–73.2%)and rooibos tea(6.1%–34.7%),comparable as found in other research between distinct biomes.While substrate quality was the dominant factor,both engineering pathways and,to a minor extent,tree diversity modulated mass losses.For green tea,tree chemical and physical characteristics seemed equally important,while the physical environment showed an increased importance for rooibos.Incubation depth played a key role,where forest floor decomposition rates are more susceptible to temporal climate variations,and soil-layer decomposition rates are less susceptible to climate variations and more determined by tree species identity.Our findings suggest that tea bag experiments focusing solely on topsoil burial may underestimate processes in the forest floor and the mineralorganic boundary layer.This study underscores the critical role of litter substrate quality in decomposition while demonstrating that tree community composition and the associated herbaceous layer,through both chemical and physical engineering pathways,strongly modulate decomposition rates.
基金supported by Universitas Advent Indonesia(No.067/EKS-SU/V/24 and 389/KEPK-FIK.UNAI/EC/V/24)。
文摘Objective:Hypertension is a serious public health concern that is influenced by a variety of body composition parameters.This study examines the associations between body composition metrics and blood pressure(BP)in a rural population,specifically how variations in body fat distribution and other metrics affect systolic blood pressure(SBP)and diastolic blood pressure(DBP).Methods:A cross-sectional study of 226 participants examined the relationships between body composition metrics—such as total body fat,visceral fat,and body mass index(BMI)—and BP.Correlation and regression analyses were used to assess these relationships.Results:The study found substantial positive correlations between visceral fat and total body fat with both SBP and DBP.Visceral fat was strongly connected with both SBP(r=0.145,P=0.030)and DBP(r=0.331,P<0.01),while total body fat was significantly correlated with DBP(r=0.268,P<0.01)but not SBP.Body composition variables explained 12.8% of the variance in SBP(R^(2)=0.128,P=0.001)and 15.0% in DBP(R^(2)=0.150,P<0.001).Conclusions:The study found substantial connections between body composition,particularly visceral and subcutaneous fat and systolic and DBP.Higher levels of visceral fat were linked to elevate BP.Body composition accounted for a significant amount of BP fluctuation.
基金supported by the United States Department of Agriculture,Forest Service,Rocky Mountain Research Station through Research Joint Venture Agreement 17–098Funding was provided by the USDA Forest Service Northern Region。
文摘Understory plants are an integral part of forests,serving a variety of functions that help maintain healthy ecosystems.The structure and composition of the understory are influenced by numerous biotic and abiotic factors,with light being critical.The introduction of the pathogen Cronartium ribicola,which causes white pine blister rust,into North America in the early 20 th century led to the near total loss of western white pine(Pinus monticola)from moist forests of the Northern Rockies.Management is reintroducing blister rust-resistant western white pine across the landscape,but the effects on the understory are unknown.We examined the effects of stand structure and proportion of western white pine in the overstory on understory diversity of vascular plants in closed canopy stands dominated by blister rust-resistant western white pine across northern Idaho.Habitat series explained the greatest amount of variation(34%)in species presence-absence,while canopy cover accounted for 25%,basal area of all trees for 18%,and the proportion of western white pine composition by 14%.Our analysis revealed positive relationships between the proportion of western white pine in the overstory and both the presence of understory plants and the cover of several understory species.For both the presence and cover,separate sets of thirteen species were found to have a positive relationship with the proportion of western white pine in the overstory,with eight species in common.This research fills a knowledge gap by using data from a range of stands across northern Idaho with varying abundance of western white pine in the overstory to evaluate the relationship between the understory and overstory composition.As land managers plant more western white pine trees,we are likely to see the concomitant increase in understory plant diversity across the landscape,in addition to numerous other benefits,including disturbance resistance and resilience.
基金funded by the National Natural Science Foundation of China(No.52204407)the Natural Science Foundation of Jiangsu Province(No.BK20220595)the China Postdoctoral Science Foundation(No.2022M723689).
文摘This study proposes a multi-scale simplified residual convolutional neural network(MS-SRCNN)for the precise prediction of Mg-Nd binary alloy compositions from scanning electron microscope(SEM)images.A multi-scale data structure is established by spatially aligning and stacking SEM images at different magnifications.The MS-SRCNN significantly reduces computational runtime by over 90%compared to traditional architectures like ResNet50,VGG16,and VGG19,without compromising prediction accuracy.The model demonstrates more excellent predictive performance,achieving a>5%increase in R^(2) compared to single-scale models.Furthermore,the MS-SRCNN exhibits robust composition prediction capability across other Mg-based binary alloys,including Mg-La,Mg-Sn,Mg-Ce,Mg-Sm,Mg-Ag,and Mg-Y,thereby emphasizing its generalization and extrapolation potential.This research establishes a non-destructive,microstructure-informed composition analysis framework,reduces characterization time compared to traditional experiment methods and provides insights into the composition-microstructure relationship in diverse material systems.
基金financial supported by the National Science Foundation of China(No.51231002)supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,under Contract No.DE-AC02-06CH11357
文摘Residual stress is an important factor for evaluating the deformation and failure of engineering materials. Diffraction-based measurement assumes that the full measured lattice strain tensor contributes to residual stress according to Hookers Law. The present work focuses on the lattice strain determination of individual grains in a dual-phase stainless steel （DPSS） by means of differential-aperture X-ray micro-diffraction （DAXM）. The results show that the residual stress only takes part of the responsibility of the total measured lattice strain. In fact, the compositional variation inside the material was found to cause greater strain gradient in both ferrite （c~） and austenite （~） phases in DPSS. Therefore, quantification of compositional and residual stress effects on lattice strain was conducted in order to evaluate the true residual stress inside engineering materials.
文摘Fatty acids are the main constituents of vegetable oils.To determine the fatty acid compositions of small trade vegetable oils and some less well studied beneficial vegetable oils,and investigate their relationships with antioxidant activity and oxidative stability,gas chromatography-mass spectrometry was performed to characterize the associated fatty acid profiles.The antioxidant activity of vegetable oils,based on their DPPH-scavenging capacity(expressed as IC_(50) values),was used to assess their impact on human health,and their oxidative stability was characterized by performing lipid oxidation analysis to determine the oxidative induction time of fats and oils.In addition,correlation analyses were performed to examine associations between the fatty acid composition of the oils and DPPH-scavenging capacity and oxidative stability.The results revealed that among the assessed oils,coffee seed oil has the highest saturated fatty acid content(355.10 mg/g),whereas Garddenia jaminoides oil has the highest unsaturated fatty acid content(844.84 mg/g).Coffee seed oil was also found have the lowest DPPH IC_(50) value(2.30 mg/mL)and the longest oxidation induction time(17.09 h).Correlation analysis revealed a significant linear relationship(P<0.05)between oxidative stability and unsaturated fatty acid content,with lower contents tending to be associated with better oxidative stability.The findings of this study provide reference data for the screening of functional edible vegetable oils.
基金National Natural Science Foundation of China(U22A20191)。
文摘Brazing filler metals are widely applied,which serve as an industrial adhesive in the joining of dissimilar structures.With the continuous emergence of new structures and materials,the demand for novel brazing filler metals is ever-increasing.It is of great significance to investigate the optimized composition design methods and to establish systematic design guidelines for brazing filler metals.This study elucidated the fundamental rules for the composition design of brazing filler metals from a three-dimensional perspective encompassing the basic properties of applied brazing filler metals,formability and processability,and overall cost.The basic properties of brazing filler metals refer to their mechanical properties,physicochemical properties,electromagnetic properties,corrosion resistance,and the wettability and fluidity during brazing.The formability and processability of brazing filler metals include the processes of smelting and casting,extrusion,rolling,drawing and ring-making,as well as the processes of granulation,powder production,and the molding of amorphous and microcrystalline structures.The cost of brazing filler metals corresponds to the sum of materials value and manufacturing cost.Improving the comprehensive properties of brazing filler metals requires a comprehensive and systematic consideration of design indicators.Highlighting the unique characteristics of brazing filler metals should focus on relevant technical indicators.Binary or ternary eutectic structures can effectively enhance the flow spreading ability of brazing filler metals,and solid solution structures contribute to the formability.By employing the proposed design guidelines,typical Ag based,Cu based,Zn based brazing filler metals,and Sn based solders were designed and successfully applied in major scientific and engineering projects.
文摘An energetic binder based on hydroxyl-terminated polybutadiene(HTPB),doped with different ratios of nitrocellulose(NC)(10%,20%,30%,and 50%),was developed to study the effect of NC doping on the thermal decomposition behavior of a composite propellant(CP)comprising ammonium nitrate(AN)as an oxidizer and magnesium(Mg)as a fuel.Optimization of the propellant formulation was conducted using Chemical Equilibrium with Applications-National Aeronautics and Space Administration(CEA-NASA)software,which demonstrated an increase in specific impulse by 12.09 s when the binder contained 50%NC.Fourier-transform infrared spectroscopy(FTIR)analysis confirmed the excellent compatibility between the components,and density measurements revealed an increase of 6.4%with a higher NC content.Morphological analysis using optical microscopy showed that NC doping improved the uniformity and compactness of the surface,reduced cavities,and achieved a more homogeneous particle distribution.Differential scanning calorimetry(DSC)analysis indicated a decrease in the decomposition temperature of the propellant as the NC content increased,while kinetic studies revealed a 48.68%reduction in the activation energy when 50%NC was incorporated into the binder.These findings suggest that the addition of NC enhances combustion efficiency and improves overall propellant performance.This study highlights the potential of the new HTPB-NC energetic binder as a promising approach for advancing solid propellant technology.
基金supported by the National Natural Science Foundation of China(No.52101128)the Jiangsu Provincial Key Research and Development Program(No.BE023059)+1 种基金the Post-doctoral Science Foundation of China(No.2022M710021)the Northeastern University Postdoctoral Research Fund of China(No.20220202).
文摘Fracture strain becomes critical for the local formability and crash performance of carbody components when the tensile strength exceeds 1000 MPa.Regrettably,high-strength quenching and partitioning(Q&P)steels and dual-phase(DP)steels always focus on improving the tensile ductility for stretch formability,while ignoring their limited fracture strain.In this work,we explored a novel strategy,i.e.,developing a high fracture strain ferrite-martensite dual-phase steel(HFS-DP)maintaining good strength–ductility balance by suppressing intense strain localization during deformation and enhancing martensite deformability via microstructure design including grain refinement,nano-precipitate hardening in soft ferrite phase,low-carbon and high fraction martensite.HFS-DP demonstrates a remarkable 26%and 47%improvement in tensile ductility and fracture strain,respectively,compared to commercial DP1180 steel with similar ultimate tensile strength.Furthermore,HFS-DP also exhibits a substantial 39%improvement in fracture strain compared to retained austenite-involved commercial QP1180 steel.The detailed processes of strain partitioning,strain localization,and damage formation during deformation were revealed through in-situ scanning electron microscopy(SEM)observation combined with digital image correlation(DIC).The results indicate that the excellent coordinated deformation between ferrite and martensite,coupled with microstructure refinement,effectively suppresses intense strain localization.Moreover,the excellent martensite deformability resulting from the low carbon content also aids in retarding crack formation.This combination effectively suppresses damage initiation and development during deformation,therefore the fracture strain is significantly improved.This study not only contributes to a deeper understanding of the strain localization and damage process during tensile deformation of DP steels,but also provides a new perspective on designing ultrahigh strength steels with high ductility and fracture strain.
基金supported by the National Natural Science Foundation of China (Nos. 51004069 and 51474145)the National Science Fund for Distinguished Young Scholars (No. 51225401)the Innovation Program of Shanghai Municipal Education Commission and Shanghai University (Nos. 14YZ013 and SDCX2012002)
文摘Dual-phase membranes of 60 wt% Ce0.8Gd0.2O2-δ-40 wt% Pr Ba Co2exFexO3 d（0 x 2） were prepared by a combined citrate and ethylene diamine tetraacetic acid（EDTA） complexing method. X-ray diffraction（XRD）results revealed the good chemical compatibility between ion-conducting phase CGO and electron-conducting phases PBC2 xFxO after sintering in air. The Fe ionic dopant had a significant effect on the phase structure stability and oxygen permeability under CO2 atmosphere, which was confirmed by XRD, thermogravimetrye differential scanning calorimetry（TGeD SC）, scanning electron microscopy（SEM） and oxygen permeation experiments. CGOeP BC0.5F1.5O dual-phase membrane demonstrated a stable oxygen permeation flux of2.71x10-7mol cm 2s 1with 50 mol% He/CO2 as the sweep gas at 925 C, and this value was much higher than that of perovskite-type membranes. The rate-limiting step in the oxygen permeation process changed from the bulk diffusion to the surface oxygen exchange when the CGOeP BC0.5F1.5O membrane thickness decreased to 0.8 mm or less. Due to the high oxygen permeation fluxes and the excellent structural stability under CO2 atmosphere, the CGOeP BC0.5F1.5O membrane is a great potential candidate material for separating oxygen from air in the oxy-fuel combustion techniques.
基金supported by the Surface Project of Local De-velopment in Science and Technology Guided by Central Govern-ment(No.2021ZYD0041)the National Natural Science Founda-tion of China(Nos.52377026 and 52301192)+3 种基金the Natural Science Foundation of Shandong Province(No.ZR2019YQ24)the Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)the Special Financial of Shandong Province(Struc-tural Design of High-efficiency Electromagnetic Wave-absorbing Composite Materials and Construction of Shandong Provincial Tal-ent Teams)the“Sanqin Scholars”Innovation Teams Project of Shaanxi Province(Clean Energy Materials and High-Performance Devices Innovation Team of Shaanxi Dongling Smelting Co.,Ltd.).
文摘With the increasing complexity of the current electromagnetic environment,excessive microwave radi-ation not only does harm to human health but also forms various electromagnetic interference to so-phisticated electronic instruments.Therefore,the design and preparation of electromagnetic absorbing composites represent an efficient approach to mitigate the current hazards of electromagnetic radiation.However,traditional electromagnetic absorbers are difficult to satisfy the demands of actual utilization in the face of new challenges,and emerging absorbents have garnered increasing attention due to their structure and performance-based advantages.In this review,several emerging composites of Mxene-based,biochar-based,chiral,and heat-resisting are discussed in detail,including their synthetic strategy,structural superiority and regulation method,and final optimization of electromagnetic absorption ca-pacity.These insights provide a comprehensive reference for the future development of new-generation electromagnetic-wave absorption composites.Moreover,the potential development directions of these emerging absorbers have been proposed as well.
基金financially supported by National Nature Science Foundation of China(81973284)Scientific Research Foundation of the Education Department of Liaoning Province(LJKZ0944).
文摘Angelica sinensis(A.sinensis),as a kind of Chinese medicine,has the effects of tonifying blood,promoting blood circulation,regulating menstrual flow,relieving pain,moistening bowel and so on.By consulting Sciencedirect database and Web of Science database,163 related articles were found,of which 36 were related to chemical composition and pharmacological activities of A.sinensis.In this paper,the chemical structures and different derivatives were systematically summarized by reviewing relevant literatures,and the pharmacological effects were also summarized.
基金Joint Fund Project of the Henan Provincial Science and Technology Research and Development Plan(222301420060)。
文摘Objective This study aimed to study the effects of different crystalline states of Sheng Shigao(raw gypsum,RG)and its inorganic elements on the antipyretic efficacy of Baihu Decoction(BHT).Methods RG samples calcined at different temperatures were prepared.The phase composition of RG and Duan Shigao(calcination of gypsum,CG)as well as the changes in phase composition before and after adding water to RG calcined at specific temperatures,were determined using X-ray diffraction(XRD).A fever model was established by subcutaneously injecting 20%yeast suspension(10 mL·kg~(-1))into the backs of rats.The effects of BHT containing RG in different crystalline states on rat body temperature were measured.Serum levels of IL-1β,IL-6,and hypothalamic prostaglandin E2(PGE_2)were detected using ELISA.Serum Ca~(2+)levels were measured using a microplate method.The content of trace elements in RG and CG and the corresponding freeze-dried BHT powder was determined using inductively coupled plasma mass spectrometry(ICP-MS).The complexation of representative inorganic elements with mangiferin,a major active component in BHT,was investigated using UV-Vis spectroscopy and fluorescence spectroscopy.A validation model was established using RAW264.7 mouse macrophages.Drug-containing serum of BHT with different inorganic elements was prepared,and the nitric oxide(NO)levels in the cell supernatant of different treatment groups were measured using the Griess method.The mRNA levels of IL-6,TNF-α,and PGE2in each group were detected using qPCR(real-time fluorescent quantitative PCR).Results After calcination,the phase composition of RG changed,and the content of inorganic elements in RG,CG170(RG calcined at 170°C),and CG350(RG calcined at 350°C)showed similar trends.Compared with RG,the content of Ca,Sr,Al,and Na in CG changed significantly.Compared with BHT,the content of Ca,Sr,Si,and Na in CG changed significantly when incorporated into the formula.Intermolecular interactions confirmed strong binding between mangiferin and Cu~(2+)and Al~(3+).Cu~(2+)and Fe~(3+)exhibited fluorescence quenching effects on mangiferin solution,while Al~(3+)and Zn~(2+)showed strong fluorescence enhancement,with fluorescence intensity increasing by 120-fold and 30-fold,respectively.In vitro evaluation of synergistic anti-inflammatory effects confirmed that Ca,Fe,Cr,Al,and Si exhibited synergistic anti-inflammatory effects.Conclusion The crystalline state of RG has little effect on its antipyretic properties,while Ca,Sr,Na,Fe,and Al are likely the key material bases influencing its efficacy.
基金supported by the State Key Program of National Natural Science Foundation of China[Grant No.51932006]National Natural Science Foundation of China[Grant No.51521001]+3 种基金the“111”Project[Grant No.B13035]the Joint Fund[Grant No.6141A02022255]the major program of specialized technological innovation of Hubei Province,China[Grant No.2019AFA176]support from China Scholarship Council(No.201906950060)。
文摘The dual-phase Re_(0.5)MoNbW(TaC)_(0.5) composite,consisting of refractory body-centered cubic(BCC)highentropy alloy and carbide with many fine eutectic structures,was successfully synthesized by arc melting.The phase stability,high-temperature mechanical properties and strengthening mechanism of the ascast composite were studied.The microstructure of the composite remained stable after annealing at 1300℃for 168 h.It exhibited remarkably high-temperature strength,yield strength~901 MPa,and true ultimate compressive strength~1186 MPa at 1200℃.The BCC phase and carbide exhibited a semi-coherent interface with good bonding after severe deformation at 1200℃.The dipolar dislocation walls in BCC phase,restricted dynamic interaction between defects in carbide,and the pinning effect of semi-coherent interface offered effective strengthening effects.
基金supported by the Fundamental Research Funds of Chinese Academy of Forestry(Nos.CAFYBB2022SY037,CAFYBB2021ZA002 and CAFYBB2022QC002)the Basic Research Foundation of Yunnan Province(Grant No.202201AT070264).
文摘Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions affect EMF remain largely unknown.Here,we investigated variation in three measures of diversity(alpha diversity,community composition and network complexity)among rare,intermediate,and abundant taxa across a latitudinal gradient spanning five forest plots in Yunnan Province,China and examined their contributions on EMF.We aimed to characterize the diversity distributions of bacterial groups across latitudes and to assess the differences in the mechanisms underlying their contributions to EMF.We found that multifaceted diversity(i.e.,diversity assessed by the three different metrics)of rare,intermediate,and abundant bacteria generally decreased with increasing latitude.More importantly,we found that rare bacterial taxa tended to be more diverse,but they contributed less to EMF than intermediate or abundant bacteria.Among the three dimensions of diversity we assessed,only community composition significantly affected EMF across all locations,while alpha diversity had a negative effect,and network complexity showed no significant impact.Our study further emphasizes the importance of intermediate and abundant bacterial taxa as well as community composition to EMF and provides a theoretical basis for investigating the mechanisms by which belowground microorganisms drive EMF along a latitudinal gradient.
基金support from the National Key Scientific and Technological Infrastructure project “Earth System Science Numerical Simulator Facility” (Earth Lab)sponsored by the National Natural Science Foundation of China (Grant Nos. 42175132, 92044303, and 42205119)+2 种基金the National Key R&D Program (Grant Nos. 2020YFA0607802 and 2022YFC3703003)the CAS Information Technology Program (Grant No. CAS-WX2021SF-0107-02)the fellowship of China Postdoctoral Science Foundation (Grant No. 2022M723093)
文摘Scientific knowledge on the chemical compositions of fine particulate matter(PM_(2.5)) is essential for properly assessing its health and climate effects,and for decisionmakers to develop efficient mitigation strategies.A high-resolution PM_(2.5) chemical composition dataset(CAQRA-aerosol)is developed in this study,which provides hourly maps of organic carbon,black carbon,ammonium,nitrate,and sulfate in China from 2013 to 2020 with a horizontal resolution of 15 km.This paper describes the method,access,and validation results of this dataset.It shows that CAQRA-aerosol has good consistency with observations and achieves higher or comparable accuracy with previous PM_(2.5) composition datasets.Based on CAQRA-aerosol,spatiotemporal changes of different PM_(2.5) compositions were investigated from a national viewpoint,which emphasizes different changes of nitrate from other compositions.The estimated annual rate of population-weighted concentrations of nitrate is 0.23μg m^(−3)yr^(−1) from 2015 to 2020,compared with−0.19 to−1.1μg m^(−3)yr^(−1) for other compositions.The whole dataset is freely available from the China Air Pollution Data Center(https://doi.org/10.12423/capdb_PKU.2023.DA).
基金supported by the Key Program of National Natural Science Foundation of China(No.51731007)the National Natural Science Foundation of China(No.52071179)the Fundamental Research Funds for the Central Universities(No.30920021160).
文摘Nano-AlN and submicron-Al_(2)O_(3) particles were simultaneously utilized in a 6061 Al matrix composite to improve the high-temperature strength.According to the SEM and TEM characterization,nano-AlN and submicron-Al_(2)O_(3) particles are uniformly distributed in the Al matrix.Brinell hardness results indicate that different from the traditional 6061 Al matrix alloy,the aging kinetics of the composite is obviously accelerated by the reinforcement particles.The T6-treated composite exhibits excellent tensile properties at both room temperature and elevated temperature.Especially at 350℃,the T6-treated composite not only has a high yield strength of 121 MPa and ultimate tensile strength of 128 MPa,but also exhibits a large elongation of 11.6%.Different strengthening mechanisms of nano-AlN and submicron-Al_(2)O_(3) particles were also discussed in detail.
基金supported by the Gas Hydrate R&D Organization and the Korea Institute of Geoscience and Mineral Resources(KIGAM)(GP2021-010)supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2021R1C1C1004460)Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korean government(MOTIE)(20214000000500,Training Program of CCUS for Green Growth).
文摘Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.
