Understanding the evolution and mechanisms of livestock industry agglomeration provides valuable policy insights for reconciling growing meat demand with constrained resource endowments.This study analyzes the spatial...Understanding the evolution and mechanisms of livestock industry agglomeration provides valuable policy insights for reconciling growing meat demand with constrained resource endowments.This study analyzes the spatial agglomeration of livestock industry at county level across China from 2000 to 2022 using the localization quotient and Moran’s I.An interpretable machine learning approach is employed to test hypotheses concerning the driving mechanisms underlying the spatial distribution of livestock industry.The results show that the agglomeration of China’s livestock industry is intensifying,with the agro-pastoral transitional zone(APTZ)emerging as a prominent agglomeration area and distinct agglomeration patterns observed within the zone as well as in its eastern and western regions.Proximity to markets has become an increasingly important determinant of livestock industry agglomeration in China.This market-driven shift has heightened the demand for agricultural feed,prompting the livestock industry to relax its dependence on local natural resource endowments and gradually relocate eastward.Regionally,the agglomeration within the APTZ is shaped by the joint effects of natural and social factors.Natural factors dominate agglomeration dynamics in the western regions of the zone,whereas social factors are more influential in its eastern regions.展开更多
By investigating the evolution of shale gas generation,storage,adjustment and accumulation under different structural settings in superimposed basins,this study elucidates the differential accumulation mechanisms of s...By investigating the evolution of shale gas generation,storage,adjustment and accumulation under different structural settings in superimposed basins,this study elucidates the differential accumulation mechanisms of shale gas.An improved evaluation method of shale gas content evolution in superimposed basins is proposed.This method incorporates the coupling effect of key geological factors such as temperature,pressure,organic matter abundance,maturity,and pore characteristics on the content and occurrence state of shale gas,as well as the configuration relationship between shale gas generation and storage throughout geological history.Using this approach,the gas evolution histories of the Longmaxi Formation shales in wells N201 and PY1 are reconstructed under varying geological conditions.The Longmaxi Formation shales in these wells are dominated by typeⅠkerogen,with original total organic carbon(TOC_(o))contents of 6.20 wt% and 4.92 wt%,respectively,indicating differences in the initial material basis for gas generation.At the maximum burial depth of approximately 5000 m,the Longmaxi Formation shale in well N201 exhibits a formation pressure coefficient of 2.05,an organic matter maturity of 2.2%,and organic pores accounting for 68%of the total porosity.The gas generation quantity(Q_(g))reaches 19.24 m^(3)/t,while the gas storage capacity(Q_(s))is 4.30 m^(3)/t.The actual total gas content(Q_(a)),constrained by Q_(s),is 4.30 m^(3)/t,with free gas comprising 94%.Following relatively moderate tectonic uplift,the Q_(a) in well N201 decreases to 4.03 m^(3)/t,with free gas accounting for 63%.In contrast,the Longmaxi Formation shale in well PY1 reached a maximum burial depth of 6300 m,associated with a formation pressure coefficient of 1.62,organic matter maturity of 2.5%,and organic pore proportion of 67%.Here,Q_(g) is 16.87 m^(3)/t,and both Q_(s) and Q_(a) are 3.65 m^(3)/t,with free gas accounting for 98%.After intense tectonic uplift,Q_(a) declines to 2.72 m^(3)/t,and the proportion of free gas drops to51%.Finally,a four-stage differential accumulation model of shale gas is established:Slow gas generation and only adsorbed gas occur in stageⅠ,which is primarily controlled by TOC content;both adsorbed gas and free gas present in stageⅡ,with free gas becoming dominant;rapid gas generation and free gas predominance are controlled by temperature and porosity in stageⅢ;and gas adjustment and accumulation are primarily controlled by temperature and pressure in stageⅣ.展开更多
The traditional"trial and error"microstructural control method,with high cost and low efficiency,has become a key issue restricting the development of ultra-high strength and toughness titanium alloys.This s...The traditional"trial and error"microstructural control method,with high cost and low efficiency,has become a key issue restricting the development of ultra-high strength and toughness titanium alloys.This study adopts the molybdenum equivalent(Mo_([eq]))method to rapidly design Ti-xMo-4Al-4Zr-3Nb-2Cr-1Fe alloys(x=5-9).The as-cast alloys with different Mo_([eq])exhibit a single peak of theβphase in XRD.Theβgrains of 5Mo alloy(the lowest Mo_([eq]))exhibit elongated columnar grain characteristics.As the Mo_([eq])increases,theβgrains transition towards a more equiaxed form,resulting in a decrease in aspect ratio and a reduction in grain size.As the Mo_([eq])increases,the a phase content gradually decreases and the a phase is almost unobservable in 9Mo alloy(the highest Mo_([eq])).The a phase in 5Mo alloy exhibits short rod-shaped shapes with an average length of about2.4μm,while the a phase in 6Mo alloy shows an equiaxed and short rod shapes with the smallest size.The strength,plasticity,and toughness are the lowest in 5Mo alloy,with values of 867 MPa,7.3%,and 56 MPa·m^(1/2),respectively.However,it reaches its maximum in 6Mo alloy,where the strength,plasticity,and toughness increase to 984 MPa,12.8%,and 74 MPa·m^(1/2),respectively.The mechanical properties of Ti-xMo-4Al-4Zr-3Nb-2Cr-1Fe alloys are affected mainly by solid-solution strengthening of Mo element,refinement ofβgrain,and changes inα/βphase content.This study lays a certain theoretical foundation for the theoretical research and composition development of new ultra-high strength and toughness titanium alloys.展开更多
The oxygen evolution reaction(OER)suffers from sluggish kinetics,necessitating efficient electrocatalysts to reduce overpotentials in water splitting.Currently recognized OER mechanisms primarily include the adsorbate...The oxygen evolution reaction(OER)suffers from sluggish kinetics,necessitating efficient electrocatalysts to reduce overpotentials in water splitting.Currently recognized OER mechanisms primarily include the adsorbate evolution mechanism(AEM),lattice oxygen mechanism(LOM),and oxide path mechanism(OPM).Compared to AEM,limited by scaling relationships,and LOM,constrained by stability issues,the OPM offers a promising alternative by enabling direct O-O bond formation via dual active sites,thus bypassing^(*)OOH intermediates and lattice O involvement and achieving a balance between activity and durability.However,activating the OPM process requires precise control over the spatial and electronic structure of active sites,making the design of OPM-based catalysts challenging.While previous reviews have focused on homo/heteronuclear diatomic perspectives of OPM-based catalysts,it is urgent to systematically summarize design strategies to provide a rational reference for their development.Herein,a review of design strategies for OPM-based OER catalysts across three scales is comprehensively presented,including in-situ engineering,doping-enabled sites reconstruction,and introducing new sites for nanoparticles,direct synthesis or post-treatments for molecular catalysts,and doping or template strategies for atom pairs or arrays.The unique advantage of atom arrays is also highlighted,and their future research directions and possible strategies are discussed.This review provides a systematic summary and forward-looking perspectives for rationally designing high-performance OPM-based OER catalysts.展开更多
Underground carbon sequestration(CS)by solid waste backfill(SWB)offers an effective pathway for collaborative disposal of coal-based solid waste and CO_(2),where the amount of carbon sequestration is an important eval...Underground carbon sequestration(CS)by solid waste backfill(SWB)offers an effective pathway for collaborative disposal of coal-based solid waste and CO_(2),where the amount of carbon sequestration is an important evaluation parameter.In this study,the concept of whole-process carbon sequestration using coal-based solid waste and CO_(2),including sequential stirring and curing stages,was proposed to evaluate the performance evolution of CS.The results showed that CO_(2) pressure and ambient temperature positively correlated with the CS amount from coal-based SWB.In particular,CO_(2) pressure prevailed in the stirring stage,while the ambient temperature effect was more significant in the curing stage.The CS amounts obtained during the stirring stage alone,the curing stage alone,and two sequential stages ranged from 0.66%–3.10%,3.53%–5.09%,and 5.12%–6.02%,respectively.The functional group and micromorphology analyses revealed that the prevailing mechanism at the CS stirring stage was the stirringdriven gas dissolution-leaching-mineralization reaction,while that at the curing stage was the hydration-driven gas permeation-dissociation-CS reaction.Both were essentially solid-liquid-gas multiphase chemical reactions.The results are instrumental in substantiating the coal-based SWB carbon sequestration evolution patterns and mechanisms and providing data support for waste disposal and carbon emission reduction in the coal industry.展开更多
The utilization of iron coke provides a green pathway for low-carbon ironmaking.To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the micro...The utilization of iron coke provides a green pathway for low-carbon ironmaking.To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was investigated.Furthermore,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method.The findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and interconnect.This provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron coke.Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke.The metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon atoms.The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure.Moreover,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.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
Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress,while hexaploid wild Camellia oleifera shows strong freezing tolerance.As a valuable genetic resource of woody oil crop C.oleifera,wil...Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress,while hexaploid wild Camellia oleifera shows strong freezing tolerance.As a valuable genetic resource of woody oil crop C.oleifera,wild C.oleifera can serve as a case for studying the molecular bases of adaptive evolution to freezing stress.Here,47 wild C.oleifera from 11 natural distribution sites in China and 4 relative species of C.oleifera were selected for genome sequencing.“Min Temperature of Coldest Month”(BIO6)had the highest comprehensive contribution to wild C.oleifera distribution.The population genetic structure of wild C.oleifera could be divided into two groups:in cold winter(BIO6≤0℃)and warm winter(BIO6>0℃)areas.Wild C.oleifera in cold winter areas might have experienced stronger selection pressures and population bottlenecks with lower N_(e) than those in warm winter areas.155 singlenucleotide polymorphisms(SNPs)were significantly correlated with the key bioclimatic variables(106 SNPs significantly correlated with BIO6).Twenty key SNPs and 15 key copy number variation regions(CNVRs)were found with genotype differentiation>50%between the two groups of wild C.oleifera.Key SNPs in cis-regulatory elements might affect the expression of key genes associated with freezing tolerance,and they were also found within a CNVR suggesting interactions between them.Some key CNVRs in the exon regions were closely related to the differentially expressed genes under freezing stress.The findings suggest that rich SNPs and CNVRs in polyploid trees may contribute to the adaptive evolution to freezing stress.展开更多
The effects of seemingly inert alkali metal(AM)cations on the electrocatalytic activity of electrode materials towards reactions essential for energy provision have become the emphasis of substantial research efforts ...The effects of seemingly inert alkali metal(AM)cations on the electrocatalytic activity of electrode materials towards reactions essential for energy provision have become the emphasis of substantial research efforts in recent years.The hydrogen and oxygen evolution reactions during alkaline water electrolysis and the oxygen electro-reduction taking place in fuel cells are of particular importance.There is no universal theory explaining all the details of the AM cation effect in electrocatalysis.For example,it remains unclear how“spectator”AM-cations can change the kinetics of electrocatalytic reactions often more significantly than the modifications of the elec-trode structure and composition.This situation originates partly from a lack of systematic experimental and theoretical studies of this phenomenon.The present work exploits impedance spectroscopy to investigate the influence of the AM cations on the mechanism of the hydrogen evolution reaction at Pt microelectrodes.The activity follows the trend:Li^(+)≥Na^(+)≥K^(+)≥Cs^(+),where the highest activity corresponds to 0.1 M LiOH electrolytes at low overpotentials.We demonstrate that the nature of the AM cations also changes the relative contribution of the Volmer–Heyrovsky and Volmer–Tafel mechanisms to the overall reaction,with the former being more important for LiOH electrolytes.Our density functional theory-based thermodynamics and molecular dynamics calculations support these findings.展开更多
High manganese steels(HMS),known for their exceptional strength-ductility balance,are increasingly utilized in dynamic loading applications.This review examines the effects of strain rate on their mechanical propertie...High manganese steels(HMS),known for their exceptional strength-ductility balance,are increasingly utilized in dynamic loading applications.This review examines the effects of strain rate on their mechanical properties and microstructural evolution,focusing on strain rate hardening,adiabatic heating softening,and dynamic strain aging(DSA).The influence of strain rate on yield strength,ultimate tensile strength,strain hardening,and ductility is discussed,highlighting both positive and negative sensitivities across different alloy compositions and strain rate regimes.The strain rate response of various deformation mechanisms,including deformation twinning,dislocation slip,and phase transformation,is examined alongside their influence on microstructural evolution,alloy design,and industrial applications.The intricate role of DSA is also analyzed,emphasizing its contribution to strain rate sensitivity.To optimize HMS for dynamic environments,future research should focus on advanced modeling and processing techniques,in-situ characterization methods,and a deeper understanding of thermally activated processes and stacking fault energy-controlled mechanisms.This review provides insights into strain rate effects,guiding alloy design,and technological advancements of the new HMS.展开更多
The microstructure evolution and deformation mechanism of a DZ125 superalloy during high-temperature creep were studied by means of microstructure observation and creep-property tests.The results show that at the init...The microstructure evolution and deformation mechanism of a DZ125 superalloy during high-temperature creep were studied by means of microstructure observation and creep-property tests.The results show that at the initial stage of high-temperature creep,two sets of dislocations with different Burgers vectors move and meet inγmatrix channels,and react to form a quadrilateral dislocation network.Andγ′phases with raft-like microstructure are generated after the formation of dislocation networks.As creep progresses,the quadrilateral dislocation network is gradually transformed into hexagonal and quadrilateral dislocation networks.During steady stage of creep,the superalloy undergoes deformation with the mechanism that a great number of dislocations slip and climb in the matrix across the raft-likeγ′phases.At the later stage of creep,the raft-likeγ′phases are sheared by dislocations at the breakage of dislocation networks,and then alternate slip occurs,which distorts and breaks the raft-likeγ′/γphases,resulting in the accumulation of micropores at the raft-likeγ′/γinterfaces and the formation of microcracks.As creep continues,the microcracks continue to expand until creep fracture occurs,which is the damage and fracture mechanism of the alloy at the later stage of creep at high temperature.展开更多
Acetolactate synthase(ALS)-targeting herbicides are among the most widely used weed-control chemicals globally.Mutations in the ALS gene can confer herbicide resistance in crops,thereby allowing selective elimination ...Acetolactate synthase(ALS)-targeting herbicides are among the most widely used weed-control chemicals globally.Mutations in the ALS gene can confer herbicide resistance in crops,thereby allowing selective elimination of weeds without harming crops.Herbicide-resistant ALS alleles were initially discovered in weeds and subsequently developed through artificial mutagenesis techniques.With the advancement of CRISPR/Cas technologies,various genome-editing tools are now available to introduce these resistant alleles,as well as novel variants,into diverse crop species.Moreover,emerging methodologies,such as directed evolution,enable the generation and screening of large populations of random ALS mutants.Consequently,ALS has become one of the most extensively targeted genes in plant gene evolution.This paper provides a comprehensive overview of both conventional and recently developed strategies for ALS evolution,with particular emphasis on CRISPR/Cas-based genome editing and directed evolution.Future perspectives on technological application are also discussed.By advancing our understanding of herbicide-resistant ALS allele development for crop improvement,these methodologies may also pave the way for their application to the evolution of other agronomically important genes.展开更多
The study of the oxygen evolution reaction(OER)mechanism is vital for advancing our understanding of this pivotal energy conversion process.This review synthesizes recent advancements in OER mechanism,emphasizing the ...The study of the oxygen evolution reaction(OER)mechanism is vital for advancing our understanding of this pivotal energy conversion process.This review synthesizes recent advancements in OER mechanism,emphasizing the intricate relationship between catalytic mechanisms and catalyst design.This review discusses the connotation and cutting-edge progress of traditional mechanisms such as adsorbate evolution mechanism(AEM)and lattice oxygen mechanism(LOM)as well as emerging pathways including oxide path mechanism(OPM),oxo-oxo coupling mechanism(OCM),and intramolecular oxygen coupling mechanism(IMOC)etc.Innovative research progress on the coexistence and transformation of multiple mechanisms is highlighted,and the intrinsic factors that influence these dynamic processes are summarized.Advanced characterization techniques and theoretical modeling are underscored as indispensable tools for revealing these complex interactions.This review provides guiding principles for mechanism-based catalyst design.Finally,in view of the multidimensional challenges currently faced by OER mechanisms,prospects for future research are given to bridge the gap between mechanism innovation and experimental verification and application.This comprehensive review provides valuable perspectives for advancing clean energy technologies and achieving sustainable development.展开更多
To accurately investigate the evolution characteristics and generation mechanism of retained oil,the study analyzed organic-rich lacustrine shale samples from the Paleogene Kongdian Formation in Cangdong Sag,Bohai Bay...To accurately investigate the evolution characteristics and generation mechanism of retained oil,the study analyzed organic-rich lacustrine shale samples from the Paleogene Kongdian Formation in Cangdong Sag,Bohai Bay Basin.This analysis involves Rock-Eval pyrolysis,pyrolysis simulation experiments,Gas Chromatograph Mass Spectrometer(GC-MS),and reactive molecular dynamics simulations(ReaxFF).The results revealed the retained oil primarily consisted of n-alkanes with carbon numbers ranging from C14 to C36.The generation of retained oil occurred through three stages.A slow growth stage of production rate was observed before reaching the peak of oil production in Stage Ⅰ.Stage Ⅱ involved a rapid increase in oil retention,with C12-C17 and C24-C32 serving as the primary components,increasing continuously during the pyrolysis process.The generation process involved the cleavage of weak bonds,including bridging bonds(hydroxyl,oxy,peroxy,imino,amino,and nitro),ether bonds,and acid amides in the first stage(Ro=0.50%-0.75%).The carbon chains in aromatic ring structures with heteroatomic functional groups breaks in the second stage(R_(o)=0.75%-1.20%).In the third stage(R_(o)=1.20%-2.50%),the ring structures underwent ring-opening reactions to synthesize iso-short-chain olefins and radicals,while further breakdown of aliphatic chains occurred.By coupling pyrolysis simu-lation experiments and molecular simulation technology,the evolution characteristics and bond breaking mechanism of retained oil in three stages were revealed,providing a reference for the for-mation and evolution mechanism of retained oil.展开更多
基金National Natural Science Foundation of China,No.42277488Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA26010301。
文摘Understanding the evolution and mechanisms of livestock industry agglomeration provides valuable policy insights for reconciling growing meat demand with constrained resource endowments.This study analyzes the spatial agglomeration of livestock industry at county level across China from 2000 to 2022 using the localization quotient and Moran’s I.An interpretable machine learning approach is employed to test hypotheses concerning the driving mechanisms underlying the spatial distribution of livestock industry.The results show that the agglomeration of China’s livestock industry is intensifying,with the agro-pastoral transitional zone(APTZ)emerging as a prominent agglomeration area and distinct agglomeration patterns observed within the zone as well as in its eastern and western regions.Proximity to markets has become an increasingly important determinant of livestock industry agglomeration in China.This market-driven shift has heightened the demand for agricultural feed,prompting the livestock industry to relax its dependence on local natural resource endowments and gradually relocate eastward.Regionally,the agglomeration within the APTZ is shaped by the joint effects of natural and social factors.Natural factors dominate agglomeration dynamics in the western regions of the zone,whereas social factors are more influential in its eastern regions.
基金funded by the Sinopec Science and Technology Project(No.P23132)the AAPG Foundation Grants-inAid Program(No.18644937)。
文摘By investigating the evolution of shale gas generation,storage,adjustment and accumulation under different structural settings in superimposed basins,this study elucidates the differential accumulation mechanisms of shale gas.An improved evaluation method of shale gas content evolution in superimposed basins is proposed.This method incorporates the coupling effect of key geological factors such as temperature,pressure,organic matter abundance,maturity,and pore characteristics on the content and occurrence state of shale gas,as well as the configuration relationship between shale gas generation and storage throughout geological history.Using this approach,the gas evolution histories of the Longmaxi Formation shales in wells N201 and PY1 are reconstructed under varying geological conditions.The Longmaxi Formation shales in these wells are dominated by typeⅠkerogen,with original total organic carbon(TOC_(o))contents of 6.20 wt% and 4.92 wt%,respectively,indicating differences in the initial material basis for gas generation.At the maximum burial depth of approximately 5000 m,the Longmaxi Formation shale in well N201 exhibits a formation pressure coefficient of 2.05,an organic matter maturity of 2.2%,and organic pores accounting for 68%of the total porosity.The gas generation quantity(Q_(g))reaches 19.24 m^(3)/t,while the gas storage capacity(Q_(s))is 4.30 m^(3)/t.The actual total gas content(Q_(a)),constrained by Q_(s),is 4.30 m^(3)/t,with free gas comprising 94%.Following relatively moderate tectonic uplift,the Q_(a) in well N201 decreases to 4.03 m^(3)/t,with free gas accounting for 63%.In contrast,the Longmaxi Formation shale in well PY1 reached a maximum burial depth of 6300 m,associated with a formation pressure coefficient of 1.62,organic matter maturity of 2.5%,and organic pore proportion of 67%.Here,Q_(g) is 16.87 m^(3)/t,and both Q_(s) and Q_(a) are 3.65 m^(3)/t,with free gas accounting for 98%.After intense tectonic uplift,Q_(a) declines to 2.72 m^(3)/t,and the proportion of free gas drops to51%.Finally,a four-stage differential accumulation model of shale gas is established:Slow gas generation and only adsorbed gas occur in stageⅠ,which is primarily controlled by TOC content;both adsorbed gas and free gas present in stageⅡ,with free gas becoming dominant;rapid gas generation and free gas predominance are controlled by temperature and porosity in stageⅢ;and gas adjustment and accumulation are primarily controlled by temperature and pressure in stageⅣ.
基金the financial support by the National Natural Science Foundation of China(Nos.U21A2042,52425401,U2441255,52474377)the Major Science and Technology Achievement Transformation Project in Heilongjiang Province(No.ZC2023SH0075)the Henan Provincial Key Research and Development&Promotion Special Program(No.251111231400)。
文摘The traditional"trial and error"microstructural control method,with high cost and low efficiency,has become a key issue restricting the development of ultra-high strength and toughness titanium alloys.This study adopts the molybdenum equivalent(Mo_([eq]))method to rapidly design Ti-xMo-4Al-4Zr-3Nb-2Cr-1Fe alloys(x=5-9).The as-cast alloys with different Mo_([eq])exhibit a single peak of theβphase in XRD.Theβgrains of 5Mo alloy(the lowest Mo_([eq]))exhibit elongated columnar grain characteristics.As the Mo_([eq])increases,theβgrains transition towards a more equiaxed form,resulting in a decrease in aspect ratio and a reduction in grain size.As the Mo_([eq])increases,the a phase content gradually decreases and the a phase is almost unobservable in 9Mo alloy(the highest Mo_([eq])).The a phase in 5Mo alloy exhibits short rod-shaped shapes with an average length of about2.4μm,while the a phase in 6Mo alloy shows an equiaxed and short rod shapes with the smallest size.The strength,plasticity,and toughness are the lowest in 5Mo alloy,with values of 867 MPa,7.3%,and 56 MPa·m^(1/2),respectively.However,it reaches its maximum in 6Mo alloy,where the strength,plasticity,and toughness increase to 984 MPa,12.8%,and 74 MPa·m^(1/2),respectively.The mechanical properties of Ti-xMo-4Al-4Zr-3Nb-2Cr-1Fe alloys are affected mainly by solid-solution strengthening of Mo element,refinement ofβgrain,and changes inα/βphase content.This study lays a certain theoretical foundation for the theoretical research and composition development of new ultra-high strength and toughness titanium alloys.
基金funding from the National Natural Science Foundation of China(22378289)the Key Central Government Guides Local Funds for Science and Technology Development(YDZJSX2022A021)the special fund for Science and Technology Innovation Teams of Shanxi Province(202304051001026)。
文摘The oxygen evolution reaction(OER)suffers from sluggish kinetics,necessitating efficient electrocatalysts to reduce overpotentials in water splitting.Currently recognized OER mechanisms primarily include the adsorbate evolution mechanism(AEM),lattice oxygen mechanism(LOM),and oxide path mechanism(OPM).Compared to AEM,limited by scaling relationships,and LOM,constrained by stability issues,the OPM offers a promising alternative by enabling direct O-O bond formation via dual active sites,thus bypassing^(*)OOH intermediates and lattice O involvement and achieving a balance between activity and durability.However,activating the OPM process requires precise control over the spatial and electronic structure of active sites,making the design of OPM-based catalysts challenging.While previous reviews have focused on homo/heteronuclear diatomic perspectives of OPM-based catalysts,it is urgent to systematically summarize design strategies to provide a rational reference for their development.Herein,a review of design strategies for OPM-based OER catalysts across three scales is comprehensively presented,including in-situ engineering,doping-enabled sites reconstruction,and introducing new sites for nanoparticles,direct synthesis or post-treatments for molecular catalysts,and doping or template strategies for atom pairs or arrays.The unique advantage of atom arrays is also highlighted,and their future research directions and possible strategies are discussed.This review provides a systematic summary and forward-looking perspectives for rationally designing high-performance OPM-based OER catalysts.
基金supported by the National Key R&D Program of China(No.2023YFC3904304)the National Natural Science Foundation of China(No.52304158)Jiangsu Key Laboratory for Clean Utilization of Carbon Resources Research Project(No.BM2024007)。
文摘Underground carbon sequestration(CS)by solid waste backfill(SWB)offers an effective pathway for collaborative disposal of coal-based solid waste and CO_(2),where the amount of carbon sequestration is an important evaluation parameter.In this study,the concept of whole-process carbon sequestration using coal-based solid waste and CO_(2),including sequential stirring and curing stages,was proposed to evaluate the performance evolution of CS.The results showed that CO_(2) pressure and ambient temperature positively correlated with the CS amount from coal-based SWB.In particular,CO_(2) pressure prevailed in the stirring stage,while the ambient temperature effect was more significant in the curing stage.The CS amounts obtained during the stirring stage alone,the curing stage alone,and two sequential stages ranged from 0.66%–3.10%,3.53%–5.09%,and 5.12%–6.02%,respectively.The functional group and micromorphology analyses revealed that the prevailing mechanism at the CS stirring stage was the stirringdriven gas dissolution-leaching-mineralization reaction,while that at the curing stage was the hydration-driven gas permeation-dissociation-CS reaction.Both were essentially solid-liquid-gas multiphase chemical reactions.The results are instrumental in substantiating the coal-based SWB carbon sequestration evolution patterns and mechanisms and providing data support for waste disposal and carbon emission reduction in the coal industry.
基金financially supported by the National Science Foundation of China(Nos.51974212 and 52274316)the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202116)+1 种基金the Science and Technology Major Project of Wuhan(No.2023020302020572)the Foundation of Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education(No.FMRUlab23-04)。
文摘The utilization of iron coke provides a green pathway for low-carbon ironmaking.To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification,the effect of iron ore on the microstructure of iron coke was investigated.Furthermore,a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method.The findings indicate that compared to coke,iron coke exhibits an augmentation in micropores and specific surface area,and the micropores further extend and interconnect.This provides more adsorption sites for CO_(2) molecules during the gasification process,resulting in a reduction in the initial gasification temperature of iron coke.Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke.The metallic iron reduced from iron ore is embedded in the carbon matrix,reducing the orderliness of the carbon structure,which is primarily responsible for the heightened reactivity of the carbon atoms.The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure.Moreover,as the proportion of iron ore increases,the activation energy for the carbon gasification gradually decreases,from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.
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.
基金funded by the National Natural Science Foundation of China(grant no.32270238 and 31870311).
文摘Subtropical evergreen broad-leaved trees are usually vulnerable to freezing stress,while hexaploid wild Camellia oleifera shows strong freezing tolerance.As a valuable genetic resource of woody oil crop C.oleifera,wild C.oleifera can serve as a case for studying the molecular bases of adaptive evolution to freezing stress.Here,47 wild C.oleifera from 11 natural distribution sites in China and 4 relative species of C.oleifera were selected for genome sequencing.“Min Temperature of Coldest Month”(BIO6)had the highest comprehensive contribution to wild C.oleifera distribution.The population genetic structure of wild C.oleifera could be divided into two groups:in cold winter(BIO6≤0℃)and warm winter(BIO6>0℃)areas.Wild C.oleifera in cold winter areas might have experienced stronger selection pressures and population bottlenecks with lower N_(e) than those in warm winter areas.155 singlenucleotide polymorphisms(SNPs)were significantly correlated with the key bioclimatic variables(106 SNPs significantly correlated with BIO6).Twenty key SNPs and 15 key copy number variation regions(CNVRs)were found with genotype differentiation>50%between the two groups of wild C.oleifera.Key SNPs in cis-regulatory elements might affect the expression of key genes associated with freezing tolerance,and they were also found within a CNVR suggesting interactions between them.Some key CNVRs in the exon regions were closely related to the differentially expressed genes under freezing stress.The findings suggest that rich SNPs and CNVRs in polyploid trees may contribute to the adaptive evolution to freezing stress.
基金the German Research Foundation (DFG) under Germany's excellence strategy–EXC 2089/1–390776260, Germany's excellence cluster “e-conversion”the DFG project BA 5795/6-1+2 种基金funding from the European Union's Horizon 2020 research and innovation program under grant agreement HERMES No 952184the National Science Foundation (NSF) support through the NSF CAREER award (Grant No. CBET1941204)financial support from TUM Innovation Network for Artificial Intelligence powered Multifunctional Material Design (ARTEMIS).
文摘The effects of seemingly inert alkali metal(AM)cations on the electrocatalytic activity of electrode materials towards reactions essential for energy provision have become the emphasis of substantial research efforts in recent years.The hydrogen and oxygen evolution reactions during alkaline water electrolysis and the oxygen electro-reduction taking place in fuel cells are of particular importance.There is no universal theory explaining all the details of the AM cation effect in electrocatalysis.For example,it remains unclear how“spectator”AM-cations can change the kinetics of electrocatalytic reactions often more significantly than the modifications of the elec-trode structure and composition.This situation originates partly from a lack of systematic experimental and theoretical studies of this phenomenon.The present work exploits impedance spectroscopy to investigate the influence of the AM cations on the mechanism of the hydrogen evolution reaction at Pt microelectrodes.The activity follows the trend:Li^(+)≥Na^(+)≥K^(+)≥Cs^(+),where the highest activity corresponds to 0.1 M LiOH electrolytes at low overpotentials.We demonstrate that the nature of the AM cations also changes the relative contribution of the Volmer–Heyrovsky and Volmer–Tafel mechanisms to the overall reaction,with the former being more important for LiOH electrolytes.Our density functional theory-based thermodynamics and molecular dynamics calculations support these findings.
基金supported by the National Natural Science Foundation(No.52101128)the Jiangsu Provincial Key Research and Development Program(No.BE023059)+1 种基金Postdoctoral Science Foundation(No.2022M710021)the Northeastern University Postdoctoral Research Fund(No.20220202)of China。
文摘High manganese steels(HMS),known for their exceptional strength-ductility balance,are increasingly utilized in dynamic loading applications.This review examines the effects of strain rate on their mechanical properties and microstructural evolution,focusing on strain rate hardening,adiabatic heating softening,and dynamic strain aging(DSA).The influence of strain rate on yield strength,ultimate tensile strength,strain hardening,and ductility is discussed,highlighting both positive and negative sensitivities across different alloy compositions and strain rate regimes.The strain rate response of various deformation mechanisms,including deformation twinning,dislocation slip,and phase transformation,is examined alongside their influence on microstructural evolution,alloy design,and industrial applications.The intricate role of DSA is also analyzed,emphasizing its contribution to strain rate sensitivity.To optimize HMS for dynamic environments,future research should focus on advanced modeling and processing techniques,in-situ characterization methods,and a deeper understanding of thermally activated processes and stacking fault energy-controlled mechanisms.This review provides insights into strain rate effects,guiding alloy design,and technological advancements of the new HMS.
基金Guizhou Province Science and Technology Plan Project(QKHJC-ZK[2024]yiban604)Guizhou Province Science and Technology Plan Project(CXTD[2021]008)+4 种基金Bijie City Science and Technology Project(BKLH[2023]9)Technology Project of Bijie City(BKLH[2023]36)Natural Science Research Project of Guizhou Higher Education Institutions of China(QJJ[2023]047)Science and Technology Project of Guizhou Department of Transportation(2022-121-011)Sanmenxia City Science and Technology Bureau Science and Technology Research Project(2022002005)。
文摘The microstructure evolution and deformation mechanism of a DZ125 superalloy during high-temperature creep were studied by means of microstructure observation and creep-property tests.The results show that at the initial stage of high-temperature creep,two sets of dislocations with different Burgers vectors move and meet inγmatrix channels,and react to form a quadrilateral dislocation network.Andγ′phases with raft-like microstructure are generated after the formation of dislocation networks.As creep progresses,the quadrilateral dislocation network is gradually transformed into hexagonal and quadrilateral dislocation networks.During steady stage of creep,the superalloy undergoes deformation with the mechanism that a great number of dislocations slip and climb in the matrix across the raft-likeγ′phases.At the later stage of creep,the raft-likeγ′phases are sheared by dislocations at the breakage of dislocation networks,and then alternate slip occurs,which distorts and breaks the raft-likeγ′/γphases,resulting in the accumulation of micropores at the raft-likeγ′/γinterfaces and the formation of microcracks.As creep continues,the microcracks continue to expand until creep fracture occurs,which is the damage and fracture mechanism of the alloy at the later stage of creep at high temperature.
基金Guangdong Basic and Applied Basic Research Foundation(2023B1515120050,2023A1515110529 and 2024A1515012454)Shenzhen Science and Technology Program(JCYJ20230807145759008 and KJZD20240903100206009).
文摘Acetolactate synthase(ALS)-targeting herbicides are among the most widely used weed-control chemicals globally.Mutations in the ALS gene can confer herbicide resistance in crops,thereby allowing selective elimination of weeds without harming crops.Herbicide-resistant ALS alleles were initially discovered in weeds and subsequently developed through artificial mutagenesis techniques.With the advancement of CRISPR/Cas technologies,various genome-editing tools are now available to introduce these resistant alleles,as well as novel variants,into diverse crop species.Moreover,emerging methodologies,such as directed evolution,enable the generation and screening of large populations of random ALS mutants.Consequently,ALS has become one of the most extensively targeted genes in plant gene evolution.This paper provides a comprehensive overview of both conventional and recently developed strategies for ALS evolution,with particular emphasis on CRISPR/Cas-based genome editing and directed evolution.Future perspectives on technological application are also discussed.By advancing our understanding of herbicide-resistant ALS allele development for crop improvement,these methodologies may also pave the way for their application to the evolution of other agronomically important genes.
文摘The study of the oxygen evolution reaction(OER)mechanism is vital for advancing our understanding of this pivotal energy conversion process.This review synthesizes recent advancements in OER mechanism,emphasizing the intricate relationship between catalytic mechanisms and catalyst design.This review discusses the connotation and cutting-edge progress of traditional mechanisms such as adsorbate evolution mechanism(AEM)and lattice oxygen mechanism(LOM)as well as emerging pathways including oxide path mechanism(OPM),oxo-oxo coupling mechanism(OCM),and intramolecular oxygen coupling mechanism(IMOC)etc.Innovative research progress on the coexistence and transformation of multiple mechanisms is highlighted,and the intrinsic factors that influence these dynamic processes are summarized.Advanced characterization techniques and theoretical modeling are underscored as indispensable tools for revealing these complex interactions.This review provides guiding principles for mechanism-based catalyst design.Finally,in view of the multidimensional challenges currently faced by OER mechanisms,prospects for future research are given to bridge the gap between mechanism innovation and experimental verification and application.This comprehensive review provides valuable perspectives for advancing clean energy technologies and achieving sustainable development.
基金financially supported by the National Natural Science Foundation of China (Grant No. 42072150)
文摘To accurately investigate the evolution characteristics and generation mechanism of retained oil,the study analyzed organic-rich lacustrine shale samples from the Paleogene Kongdian Formation in Cangdong Sag,Bohai Bay Basin.This analysis involves Rock-Eval pyrolysis,pyrolysis simulation experiments,Gas Chromatograph Mass Spectrometer(GC-MS),and reactive molecular dynamics simulations(ReaxFF).The results revealed the retained oil primarily consisted of n-alkanes with carbon numbers ranging from C14 to C36.The generation of retained oil occurred through three stages.A slow growth stage of production rate was observed before reaching the peak of oil production in Stage Ⅰ.Stage Ⅱ involved a rapid increase in oil retention,with C12-C17 and C24-C32 serving as the primary components,increasing continuously during the pyrolysis process.The generation process involved the cleavage of weak bonds,including bridging bonds(hydroxyl,oxy,peroxy,imino,amino,and nitro),ether bonds,and acid amides in the first stage(Ro=0.50%-0.75%).The carbon chains in aromatic ring structures with heteroatomic functional groups breaks in the second stage(R_(o)=0.75%-1.20%).In the third stage(R_(o)=1.20%-2.50%),the ring structures underwent ring-opening reactions to synthesize iso-short-chain olefins and radicals,while further breakdown of aliphatic chains occurred.By coupling pyrolysis simu-lation experiments and molecular simulation technology,the evolution characteristics and bond breaking mechanism of retained oil in three stages were revealed,providing a reference for the for-mation and evolution mechanism of retained oil.
