A modified multi-component solute diffusion equation described with diffusion flux was derived in detail based on the classical MaxwellStefan diffusion theory. The friction between the solute species and the soil skel...A modified multi-component solute diffusion equation described with diffusion flux was derived in detail based on the classical MaxwellStefan diffusion theory. The friction between the solute species and the soil skeleton wall, which is proportional to the relative velocity between the solute species and the soil skeleton, is introduced. The chemical potential gradient is considered the driving force. A one-dimensional model for transport of multi-component solute in saturated soil was developed based on the modified diffusion equation and the modified competitive Langmuir adsorption equation. Numerical calculation of a case of two heavy metal ion species, which was chosen as an example, was carried out using the finite element software COMSOL Multiphysics. A comparative analysis was performed between the multi-component solute transport model developed in this study and the convection-diffusion transport model of single-component solute based on Fick's law. Simulation results show that the transport behavior of each species in a multi-component solute system is different from that in a single-component system, and the friction characteristics considered in the developed model contribute to obstructing the movement of each solute component. At the same time,the influence of modified competitive Langmuir adsorption on solute transport was investigated. These research results can provide strong theoretical support for the design of antifouling barriers in landfills and the maintenance of operation stability.展开更多
Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable ...Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable strategy for constructing new carbon-oxygen bonds.In comparison with traditional thermal or metal-mediated carbene transfer reactions,visible-light-promoted multi-component reaction strategy provides a mild and eco-friendly approach to access densely functionalized molecules.Recently,visible-light-induced multi-component carbene transfer reactions of diazo compounds have been rapidly developed and attracted a great deal of research interest of chemists owing to their advantages of simple operation,mild condition,high atom economy and rich structural diversity.This paper summarizes the recent research progress on the visible-light-promoted multi-component carbene transfer reactions of diazo compounds via ring-opening of cyclic ethers with various nucleophiles.The reaction patterns of different nucleophiles and their corresponding mechanism are described in this review.The future research direction and challenges in this area are also discussed.展开更多
Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer （salt deposit） in Qarhan Salt Lake was studied by using the Pitzer theory. Th...Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer （salt deposit） in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system （salt deposits） was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarhan Salt Lake.展开更多
The Cahn, Lücke and Stüwe theory remains the backbone of more complex analysis dealing with solute drag, however, the mathematical treatment is rather involved. A new approach based on solute pinning the bou...The Cahn, Lücke and Stüwe theory remains the backbone of more complex analysis dealing with solute drag, however, the mathematical treatment is rather involved. A new approach based on solute pinning the boundary has therefore recently been suggested, which has the main advantage of a simpler mathematical treatment. In the present paper this approach has been generalized to take into account the influence of different types of solute atoms in the high solute content/low driving force regime.展开更多
An empiric equation, G ex H 2O /(1- x (H 2O)) 2= α+β·x (H 2O)/ln( x (H 2O)), representing the relation between the excess free energy G ex H 2O and mole fraction of water x (H 2O) in binary electrolyte solution...An empiric equation, G ex H 2O /(1- x (H 2O)) 2= α+β·x (H 2O)/ln( x (H 2O)), representing the relation between the excess free energy G ex H 2O and mole fraction of water x (H 2O) in binary electrolyte solution, was developed and the parameters α and β in the equation were determined by fitting the experimental data for some binary aqueous systems of electrolytes such as CuCl 2, NiCl 2, HCl, NaCl, KCl, CaCl 2 and BaCl 2. The activities of water in such ternary and multi component systems composed of 7 binaries as HClH 2OCuCl 2, HClH 2ONiCl 2, HClH 2ONaCl, NaClH 2OKCl, NaCl H 2OCaCl 2, KClH 2OCaCl 2, NaClH 2OBaCl 2, KClH 2OCaCl 2 and NaClH 2OKClBaCl 2 were predicted by a simplified sub regular solution model developed by authors from the corresponding binary systems. The predicted results are in good agreement with the measured ones. [展开更多
To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migong...To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.展开更多
In this paper, new Jacobi elliptic function solutions of multi-component mKdV equation are obtained directly in a unified way. When the modulus m → 1, those periodic solutions degenerate as the corresponding hyperbol...In this paper, new Jacobi elliptic function solutions of multi-component mKdV equation are obtained directly in a unified way. When the modulus m → 1, those periodic solutions degenerate as the corresponding hyperbolic function solutions. Then, to the three-component mKdV equation, five types of effective solution are presented in detail.展开更多
In the realm of nonlinear integrable systems,the presence of decompositions facilitates the establishment of linear superposition solutions and the derivation of novel coupled systems exhibiting nonlinear integrabilit...In the realm of nonlinear integrable systems,the presence of decompositions facilitates the establishment of linear superposition solutions and the derivation of novel coupled systems exhibiting nonlinear integrability.By focusing on single-component decompositions within the potential BKP hierarchy,it has been observed that specific linear superpositions of decomposition solutions remain consistent with the underlying equations.Moreover,through the implementation of multi-component decompositions within the potential BKP hierarchy,successful endeavors have been undertaken to formulate linear superposition solutions and novel coupled Kd V-type systems that resist decoupling via alterations in dependent variables.展开更多
Multi-component transition group metal borides(MMB_(2))have become a research hotspot due to their new composition design concepts and superior properties compared with conventional ceramics.Most of the current method...Multi-component transition group metal borides(MMB_(2))have become a research hotspot due to their new composition design concepts and superior properties compared with conventional ceramics.Most of the current methods,however,are complicated and time-consuming,the mass production remains a chal-lenge.Herein,we proposed a new high-efficiency strategy for synthesis of MMB_(2)using molten aluminum as the medium for the first time.The prepared Al-containing multi-component borides(TiZrHfNbTa)B_(2)microcrystals had a homogeneous composition with a hexagonal AlB_(2)structure and ultra-high hardness value of∼35.3 GPa,which was much higher than data reported in the literature and the rule of mix-ture estimations.Furthermore,combined with the First-principles calculation results,we found that the Poisson’s ratio(v)values exhibit a clearly ascending trend from 0.17 at VEC=3.5 to 0.18 at VEC=3.4,then to 0.201 at VEC=3.2 with the increasing of Al content.This indicates that the intrinsic toughness of multi-component boride microcrystals is obviously enhanced by the trace-doped Al elements.Besides,the fabricated Al-containing multi-component boride microcrystals have superior oxidation activation en-ergy and structural stability.The enhanced oxidation resistance is mainly attributed to the formation of a protective Al2 O3 oxide layer and the lattice distortion,both of which lead to sluggish diffusion of O_(2).These findings propose a new unexplored avenue for the fabrication of MMB_(2)materials with supe-rior comprehensive performance including ultra-hardness and intrinsically improved thermo-mechanical properties.展开更多
The present work extends the search of Jacobi elliptic function solutions for the multi-component modified Korteweg-de Vries equations. When the modulum m →1, those periodic solutions degenerate as the corresponding ...The present work extends the search of Jacobi elliptic function solutions for the multi-component modified Korteweg-de Vries equations. When the modulum m →1, those periodic solutions degenerate as the corresponding solitary wave and shock wave ones. Especially, exact solutions for the three-component system are presented in detail and graphically.展开更多
The hardening mechanism of multi-component carbide ceramic has been investigated in detail through a combination of experiments,first-principles calculations,and ab initio molecular dynamics(AIMD).Eight dense carbide ...The hardening mechanism of multi-component carbide ceramic has been investigated in detail through a combination of experiments,first-principles calculations,and ab initio molecular dynamics(AIMD).Eight dense carbide ceramics were prepared by spark plasma sintering.Compulsorily,all the multi-component carbide samples have similar carbon content,grain size,and uniform compositional distribution by optimizing the sintering process and adjusting the initial raw materials.Hence the interference of other factors on the hardness of multi-component carbide ceramics is minimized.The effects of changes in the elemental species on the lattice distortion,bond strength,bonding properties,and electronic structure of multi-component carbide ceramics were thoroughly analyzed.These results show that the hardening of multi-component carbide ceramic can be attributed to the coupling of solid solution strengthening caused by lattice distortion and covalent bond strengthening.Besides,the“host lattice”of multi-component carbide ceramics is defined based on the concept of supporting lattice.The present work is of great significance for a deeper understanding of the hardening mechanism of multi-component carbide ceramics and the design of superhard multi-component carbides.展开更多
A convenient photocatalytic multi-component reaction of alkenes,quinoxalin-2(1H)-ones,and diazo compounds has been developed in the presence of water.A number of ester-containing quinoxalin-2(1H)-ones could be efficie...A convenient photocatalytic multi-component reaction of alkenes,quinoxalin-2(1H)-ones,and diazo compounds has been developed in the presence of water.A number of ester-containing quinoxalin-2(1H)-ones could be efficiently obtained in moderate to good yields at room temperature.This metal-free visiblelight-driven tandem reaction was conducted through proton-coupled electron transfer(PCET)process using water as the hydrogen donor and 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene(4CzIPN)as the photocatalyst.展开更多
With the evolution of nickel-based single crystal superalloys,there is an increase in heavy elements such as Re and Ru.This has made solutal convection more pronounced during the directional solidification process,lea...With the evolution of nickel-based single crystal superalloys,there is an increase in heavy elements such as Re and Ru.This has made solutal convection more pronounced during the directional solidification process,leading to solute redistribution and increasing the risk of casting defects such as low-angle grain boundaries.To avoid casting defects,downward directional solidification(DWS)method is adopted to eliminate solutal convection and change solute redistribution.However,there is currently no in-situ characterization or quantitative simulation studying the solute redistribution during DWS and upward directional solidification(UWS)processes.A multicomponent phase field simulation coupled with lattice Boltzmann method was employed to quantitatively investigate changes in dendrite morphology,solutal convection and deviation of dendrite tips from the perspective of solute redistribution during UWS and DWS processes.The simulation of microstructure agrees well with the experimental results.The mechanism that explains how solutal convection affects side branching behavior is depicted.A novel approach is introduced to characterize dendrite deviation,elucidating the reasons why defects are prone to occur under the influence of natural convection and solute redistribution.展开更多
The construction of a borehole correction library for the multi-component array induction tool in deviated boreholes involves extensive 3D forward modeling and typically requires significant computational resources.To...The construction of a borehole correction library for the multi-component array induction tool in deviated boreholes involves extensive 3D forward modeling and typically requires significant computational resources.To address this challenge,this paper proposes an efficient algorithm for the library construction based on the 3D finite volume method(FVM)and contraction high-order Born approximation(CHBA).First,the electromagnetic(EM)field solution region is divided into two symmetric subregions based on the symmetry of the correction library model and the EM field.Numerical solution on a single subregion,combined with the symmetry boundary extension technique,enhances the efficiency of the 3D numerical simulation.Second,three reference mud conductivities are selected based on the mud conductivity range,and the CHBA is applied to calculate the EM responses at all mud conductivity nodes rapidly.Third,the number of forward simulation operations is further reduced by exploiting the principle that models with different frequencies and different formation conductivities have equivalent EM responses.Numerical experiments demonstrate the correctness and feasibility of the proposed algorithm.Compared to conventional 3D modeling,the proposed algorithm achieves approximately a 20-fold speedup in library construction,effectively reducing computational resources and time consumption.展开更多
Interface segregation of solute atoms has a profound effect on properties of engineering alloys.In this study,we report a novel strategy for breaking the strength-ductility dilemma of Mg alloy via solute segregation.T...Interface segregation of solute atoms has a profound effect on properties of engineering alloys.In this study,we report a novel strategy for breaking the strength-ductility dilemma of Mg alloy via solute segregation.The hot extruded Mg-1.8Gd-0.3Zr(wt.%)alloy sheet was subjected to three different passes of rolling,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Gd atoms along high and low-angel grain boundaries(GBs).Under almost precipitation-free conditions,the strength and ductility of rolled alloy sheets are simultaneously improved after annealing.Especially for the annealed 3-passes-rolled specimen,the yield strength,ultimate tensile strength,and elongation are simultaneously increased by 11.2%,7.3%,and 18%,respectively.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects,including dislocation annihilation and grain coarsening during the heating.Meanwhile,the directional migration of Gd atoms and the annihilation of dislocations provide a“clear”space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.展开更多
In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then hea...In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Zn atoms along both high and lowangle grain boundaries(GBs).As compared with as-rolled plate,the yield strength,ultimate tensile strength,and the elongation of annealed sample is increased by 15.6%,14%,and 8.4%,respectively,acquiring an obvious strength-ductility synergy effect.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects including dislocation annihilation and grain coarsening.Meanwhile,the directional migration of Zn atoms and the annihilation of dislocations provide a"clear"space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.展开更多
In order to investigate the segregation process and clarify its effect on the formation of TiN during the solidification of a micro-alloy steel containing titanium(Ti),a new mathematical model concerning solute transp...In order to investigate the segregation process and clarify its effect on the formation of TiN during the solidification of a micro-alloy steel containing titanium(Ti),a new mathematical model concerning solute transportation,solidification,as well as TiN precipitation was successfully established and verified.The transportation of solute elements was described using the Brody-Fleming microsegregation model,while the thermodynamic principles governing the precipitation of TiN were derived within the framework of the model.Additionally,the model accounts for variations in the diffusion coefficient due to phase transition and the influence of non-equilibrium solidification on solute distribution.High-temperature tests were conducted to validate the mathematical model.Results show that during solidification,due to selective crystallization,there is positive segregation of Ti and N in the solidifying front.What’s more,due to the high cooling rate near the surface of this steel,negative segregation is easier to be formed in the surface area.The highest concentration of TiN precipitation is found in the 1/4 width of this steel.High-temperature experiment shows that when the solidifying front reaches the 1/4 width of the specimen,the concentration product of Ti and N elements biased at the solidifying front reaches the thermodynamic conditions of TiN precipitation,and exists a higher concentration of TiN distributed in this region.To address this phenomenon,a comparative analysis of the effects of cooling rate and initial solute element content on TiN precipitation behavior was conducted.An increase in the surface cooling rate accelerates the progression of the solidification front and diminishes solute segregation near the front,thereby reducing TiN precipitation.However,with the increase of the initial solute element content,the concentration product of Ti and N elements rises,then the content of TiN precipitation increases.The results of this model provide important insight into the micro segregation and TiN precipitation mechanism of the micro-alloy steels bearing titanium.展开更多
The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation ener...The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation energies.Here we propose novel electronic descriptors for grain-boundary segregation based on the valence,electronegativity and size of solutes.By integrating the non-local coordination number of surfaces,we build a predictive analytic framework for evaluating the segregation energies across various solutes,grain-boundary structures,and segregation sites.This framework uncovers not only the coupling rule of solutes and matrices,but also the origin of solute-segregation determinants,which stems from the d-and sp-states hybridization in alloying.Our scheme establishes a novel picture for grain-boundary segregation and provides a useful tool for the design of advanced alloys.展开更多
Solute segregation at grain boundaries(GBs)can significantly influence GB cohesion.In this work,the segregation energies of solutes(Zn,Al,Ag,Ca,and Gd)were first investigated at six symmetrical tilt GBs rotating aroun...Solute segregation at grain boundaries(GBs)can significantly influence GB cohesion.In this work,the segregation energies of solutes(Zn,Al,Ag,Ca,and Gd)were first investigated at six symmetrical tilt GBs rotating around[0001]axis of Mg,to uncover the impact of GB characteristics on solute segregation behavior.The results reveal that solute segregation propensity is closely related to the local geometric environment of GB sites,but has little correlation with intrinsic GB properties(such as GB misorientation and GB energy).Furthermore,relationships between GB site characteristics and solute segregation tendencies were established.Ca-like solutes tend to occupy GB sites with larger Voronoi volumes(V),while Zn-like solutes prefer GB sites with smaller V as well as smaller shortest bond lengths(SBL).Based on this finding,we further evaluated the segregation capacities of 26 solutes at their most energetically stable segregation sites and their impact on GB cohesion.A descriptor that can effectively capture the strengthening/embrittling potency of segregated solutes on GBs was proposed by performing the crystal orbital Hamilton population(COHP)analyses.It was found that the discrepancies in bond strength between GBs and free surface dominate the solute-strengthening behavior.Finally,a first-principles“design map”regarding the segregation energies and strengthening energies was provided,which offers a database for designing Mg alloys with high fracture toughness.展开更多
基金supported by the National Basic Research Program of China(Grant No.2014CB744702)the Beijing Natural Science Foundation Key Projects(Grant No.8171001)the National Natural Science Foundation of China(Grant No.51678012)
文摘A modified multi-component solute diffusion equation described with diffusion flux was derived in detail based on the classical MaxwellStefan diffusion theory. The friction between the solute species and the soil skeleton wall, which is proportional to the relative velocity between the solute species and the soil skeleton, is introduced. The chemical potential gradient is considered the driving force. A one-dimensional model for transport of multi-component solute in saturated soil was developed based on the modified diffusion equation and the modified competitive Langmuir adsorption equation. Numerical calculation of a case of two heavy metal ion species, which was chosen as an example, was carried out using the finite element software COMSOL Multiphysics. A comparative analysis was performed between the multi-component solute transport model developed in this study and the convection-diffusion transport model of single-component solute based on Fick's law. Simulation results show that the transport behavior of each species in a multi-component solute system is different from that in a single-component system, and the friction characteristics considered in the developed model contribute to obstructing the movement of each solute component. At the same time,the influence of modified competitive Langmuir adsorption on solute transport was investigated. These research results can provide strong theoretical support for the design of antifouling barriers in landfills and the maintenance of operation stability.
基金Science and Technology Foundation of Guizhou Province(No.QKHJC-ZK[2024]654)Guizhou Provincial University Key Laboratory of Advanced Functional Electronic Materials(No.QJ[2023]021).
文摘Carbenes as one of the most important class of intermediates have been widely utilized in various organic synthetic transformations.Carbene insertion-initiated ring-opening reactions of cyclic ethers offer a valuable strategy for constructing new carbon-oxygen bonds.In comparison with traditional thermal or metal-mediated carbene transfer reactions,visible-light-promoted multi-component reaction strategy provides a mild and eco-friendly approach to access densely functionalized molecules.Recently,visible-light-induced multi-component carbene transfer reactions of diazo compounds have been rapidly developed and attracted a great deal of research interest of chemists owing to their advantages of simple operation,mild condition,high atom economy and rich structural diversity.This paper summarizes the recent research progress on the visible-light-promoted multi-component carbene transfer reactions of diazo compounds via ring-opening of cyclic ethers with various nucleophiles.The reaction patterns of different nucleophiles and their corresponding mechanism are described in this review.The future research direction and challenges in this area are also discussed.
基金the National Natural Science Foundation of China
文摘Firstly, the macroscopic chemical equilibrium state of a series of chemical reactions between intercrystal brine and its media salt layer （salt deposit） in Qarhan Salt Lake was studied by using the Pitzer theory. The concept of macroscopic solubility product and its relation with accumulated ore dissolving ratio were presented, which are used in the numerical model of dissolving and driving exploitation of potassium salt in Qarhan Salt Lake. And secondly, with a model forming idea of transport model for reacting solutes in the multi-component fresh groundwater system in porous media being a reference, a two-dimensional transport model coupled with a series of chemical reactions in a multi-component brine porous system （salt deposits） was developed by using the Pitzer theory. Meanwhile, the model was applied to model potassium/magnesium transport in Qarhan Salt Lake in order to study the transfer law of solid and liquid phases in the dissolving and driving process and to design the optimal injection/abstraction strategy for dissolving and capturing maximum Potassium/ Magnesium in the mining of salt deposits in Qarhan Salt Lake.
基金supported by a KMB project(project number:193179/I40),in Norwayfinancial support by the Research Council of Norway and the industrial partners,Hydro Aluminium and Sapa Technology is gratefully acknowledged.
文摘The Cahn, Lücke and Stüwe theory remains the backbone of more complex analysis dealing with solute drag, however, the mathematical treatment is rather involved. A new approach based on solute pinning the boundary has therefore recently been suggested, which has the main advantage of a simpler mathematical treatment. In the present paper this approach has been generalized to take into account the influence of different types of solute atoms in the high solute content/low driving force regime.
文摘An empiric equation, G ex H 2O /(1- x (H 2O)) 2= α+β·x (H 2O)/ln( x (H 2O)), representing the relation between the excess free energy G ex H 2O and mole fraction of water x (H 2O) in binary electrolyte solution, was developed and the parameters α and β in the equation were determined by fitting the experimental data for some binary aqueous systems of electrolytes such as CuCl 2, NiCl 2, HCl, NaCl, KCl, CaCl 2 and BaCl 2. The activities of water in such ternary and multi component systems composed of 7 binaries as HClH 2OCuCl 2, HClH 2ONiCl 2, HClH 2ONaCl, NaClH 2OKCl, NaCl H 2OCaCl 2, KClH 2OCaCl 2, NaClH 2OBaCl 2, KClH 2OCaCl 2 and NaClH 2OKClBaCl 2 were predicted by a simplified sub regular solution model developed by authors from the corresponding binary systems. The predicted results are in good agreement with the measured ones. [
基金supported by the National Natural Science Foundation of China(Nos.42007178 and 41907327)the Natural Science Foundation of Hubei(Nos.2020CFB463 and 2019CFB372)+4 种基金China Geological Survey(Nos.DD20160304 and DD20190824)Fundamental Research Funds for the Central Universities(Nos.CUG 190644 and CUGL180817)National Key Research and Development Program(No.2019YFC1805502)Key Laboratory of Karst Dynamics,MNR and GZAR(Institute of Karst Geology,CAGS)Guilin(No.KDL201703)Key Laboratory of Karst Ecosystem and Treatment of Rocky Desertification,MNR and IRCK by UNESCO(No.KDL201903)。
文摘To investigate groundwater flow and solute transport characteristics of the karst trough zone in China,tracer experiments were conducted at two adjacent typical karst groundwater flow systems(Yuquandong(YQD)and Migongquan(MGQ))in Sixi valley,western Hubei,China.Highresolution continuous monitoring was utilized to obtain breakthrough curves(BTCs),which were then analyzed using the multi-dispersion model(MDM)and the two-region nonequilibrium model(2RNE)with basic parameters calculated by CXTFIT and QTRACER2.Results showed that:(1)YQD flow system had a complex infiltration matrix with overland flow,conduit flow and fracture flow,while the MGQ flow system was dominated by conduit flow with fast flow transport velocity,but also small amount of fracture flow there;(2)They were well fitted based on the MDM(R^2=0.928)and 2RNE(R^2=0.947)models,indicating that they had strong adaptability in the karst trough zone;(3)conceptual models for YQD and MGQ groundwater systems were generalized.In YQD system,the solute was transported via overland flow during intense rainfall,while some infiltrated down into fissures and conduits.In MGQ system,most were directly transported to spring outlet in the fissureconduit network.
基金The project supported by the Education Foundation of Zhejiang Province of China under Grant No. 20030557 and the Science Foundation of Zhejiang Forestry College
文摘In this paper, new Jacobi elliptic function solutions of multi-component mKdV equation are obtained directly in a unified way. When the modulus m → 1, those periodic solutions degenerate as the corresponding hyperbolic function solutions. Then, to the three-component mKdV equation, five types of effective solution are presented in detail.
基金sponsored by the National Natural Science Foundations of China under Grant Nos.12301315,12235007,11975131the Zhejiang Provincial Natural Science Foundation of China under Grant No.LQ20A010009。
文摘In the realm of nonlinear integrable systems,the presence of decompositions facilitates the establishment of linear superposition solutions and the derivation of novel coupled systems exhibiting nonlinear integrability.By focusing on single-component decompositions within the potential BKP hierarchy,it has been observed that specific linear superpositions of decomposition solutions remain consistent with the underlying equations.Moreover,through the implementation of multi-component decompositions within the potential BKP hierarchy,successful endeavors have been undertaken to formulate linear superposition solutions and novel coupled Kd V-type systems that resist decoupling via alterations in dependent variables.
基金financially supported by the National Natural Science Foundation of China(Nos.52271033 and 52071179)the Key program of National Natural Science Foundation of China(No.51931003)+2 种基金Natural Science Foundation of Jiangsu Province,China(No.BK20221493)Jiangsu Province Leading Edge Technology Basic Research Major Project(No.BK20222014)Foundation of“Qinglan Project”for Colleges and Universities in Jiangsu Province.
文摘Multi-component transition group metal borides(MMB_(2))have become a research hotspot due to their new composition design concepts and superior properties compared with conventional ceramics.Most of the current methods,however,are complicated and time-consuming,the mass production remains a chal-lenge.Herein,we proposed a new high-efficiency strategy for synthesis of MMB_(2)using molten aluminum as the medium for the first time.The prepared Al-containing multi-component borides(TiZrHfNbTa)B_(2)microcrystals had a homogeneous composition with a hexagonal AlB_(2)structure and ultra-high hardness value of∼35.3 GPa,which was much higher than data reported in the literature and the rule of mix-ture estimations.Furthermore,combined with the First-principles calculation results,we found that the Poisson’s ratio(v)values exhibit a clearly ascending trend from 0.17 at VEC=3.5 to 0.18 at VEC=3.4,then to 0.201 at VEC=3.2 with the increasing of Al content.This indicates that the intrinsic toughness of multi-component boride microcrystals is obviously enhanced by the trace-doped Al elements.Besides,the fabricated Al-containing multi-component boride microcrystals have superior oxidation activation en-ergy and structural stability.The enhanced oxidation resistance is mainly attributed to the formation of a protective Al2 O3 oxide layer and the lattice distortion,both of which lead to sluggish diffusion of O_(2).These findings propose a new unexplored avenue for the fabrication of MMB_(2)materials with supe-rior comprehensive performance including ultra-hardness and intrinsically improved thermo-mechanical properties.
基金supported by National Natural Science Foundation of China under Grant Nos. 60772023 and 60372095the Key Project of the Ministry of Education under Grant No. 106033+3 种基金the Open Fund of the State Key Laboratory of Software Development Environment under Grant No. SKLSDE-07-001Beijing University of Aeronautics and Astronautics,the National Basic Research Program of China (973 Program) under Grant No. 2005CB321901the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No. 20060006024the Ministry of Education
文摘The present work extends the search of Jacobi elliptic function solutions for the multi-component modified Korteweg-de Vries equations. When the modulum m →1, those periodic solutions degenerate as the corresponding solitary wave and shock wave ones. Especially, exact solutions for the three-component system are presented in detail and graphically.
基金financially supported by the National Natural Science Foundation of China(Nos.52032002,52372060,51972081,and U22A20128)the National Safety Academic Foundation(No.U2130103)+1 种基金the National Key Laboratory of Precision Hot Processing of Metals(No.61429092300305)Heilongjiang Touyan Team Program are gratefully acknowledged.
文摘The hardening mechanism of multi-component carbide ceramic has been investigated in detail through a combination of experiments,first-principles calculations,and ab initio molecular dynamics(AIMD).Eight dense carbide ceramics were prepared by spark plasma sintering.Compulsorily,all the multi-component carbide samples have similar carbon content,grain size,and uniform compositional distribution by optimizing the sintering process and adjusting the initial raw materials.Hence the interference of other factors on the hardness of multi-component carbide ceramics is minimized.The effects of changes in the elemental species on the lattice distortion,bond strength,bonding properties,and electronic structure of multi-component carbide ceramics were thoroughly analyzed.These results show that the hardening of multi-component carbide ceramic can be attributed to the coupling of solid solution strengthening caused by lattice distortion and covalent bond strengthening.Besides,the“host lattice”of multi-component carbide ceramics is defined based on the concept of supporting lattice.The present work is of great significance for a deeper understanding of the hardening mechanism of multi-component carbide ceramics and the design of superhard multi-component carbides.
基金supported by Sichuan Science and Technology Program(No.2023NSFSC0101)the 2024 Provincial platform project of Chengdu Normal University(No.GNFZ202404)+1 种基金Natural Science Foundation of Shandong Province(No.ZR2021MB065)National Natural Science Foundation of China(No.22101237)。
文摘A convenient photocatalytic multi-component reaction of alkenes,quinoxalin-2(1H)-ones,and diazo compounds has been developed in the presence of water.A number of ester-containing quinoxalin-2(1H)-ones could be efficiently obtained in moderate to good yields at room temperature.This metal-free visiblelight-driven tandem reaction was conducted through proton-coupled electron transfer(PCET)process using water as the hydrogen donor and 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene(4CzIPN)as the photocatalyst.
基金supported by the stable support project and the Major National Science and Technology Project(2017-VII-0008-0101).
文摘With the evolution of nickel-based single crystal superalloys,there is an increase in heavy elements such as Re and Ru.This has made solutal convection more pronounced during the directional solidification process,leading to solute redistribution and increasing the risk of casting defects such as low-angle grain boundaries.To avoid casting defects,downward directional solidification(DWS)method is adopted to eliminate solutal convection and change solute redistribution.However,there is currently no in-situ characterization or quantitative simulation studying the solute redistribution during DWS and upward directional solidification(UWS)processes.A multicomponent phase field simulation coupled with lattice Boltzmann method was employed to quantitatively investigate changes in dendrite morphology,solutal convection and deviation of dendrite tips from the perspective of solute redistribution during UWS and DWS processes.The simulation of microstructure agrees well with the experimental results.The mechanism that explains how solutal convection affects side branching behavior is depicted.A novel approach is introduced to characterize dendrite deviation,elucidating the reasons why defects are prone to occur under the influence of natural convection and solute redistribution.
基金funded by the Forward-looking Basic Science and Technology Research Project of PetroChina Company Limited(2025DJ104)the National Natural Science Foundation of China(42174150)the National Science and Technology Major Project for Deep Earth Probe and Mineral Resources Exploration(2024ZD1003005).
文摘The construction of a borehole correction library for the multi-component array induction tool in deviated boreholes involves extensive 3D forward modeling and typically requires significant computational resources.To address this challenge,this paper proposes an efficient algorithm for the library construction based on the 3D finite volume method(FVM)and contraction high-order Born approximation(CHBA).First,the electromagnetic(EM)field solution region is divided into two symmetric subregions based on the symmetry of the correction library model and the EM field.Numerical solution on a single subregion,combined with the symmetry boundary extension technique,enhances the efficiency of the 3D numerical simulation.Second,three reference mud conductivities are selected based on the mud conductivity range,and the CHBA is applied to calculate the EM responses at all mud conductivity nodes rapidly.Third,the number of forward simulation operations is further reduced by exploiting the principle that models with different frequencies and different formation conductivities have equivalent EM responses.Numerical experiments demonstrate the correctness and feasibility of the proposed algorithm.Compared to conventional 3D modeling,the proposed algorithm achieves approximately a 20-fold speedup in library construction,effectively reducing computational resources and time consumption.
基金supported by the National Natural Science Foundation of China(No.52225101)the Fundamental Research Funds for the Central Universities(2023CDJYXTD-002)+1 种基金supported by the Special Fund for Special Posts of Guizhou University(No.202353)Guizhou Provincial Basic Research Program(Natural Science)(Qingnian Yindao No.2024-123).
文摘Interface segregation of solute atoms has a profound effect on properties of engineering alloys.In this study,we report a novel strategy for breaking the strength-ductility dilemma of Mg alloy via solute segregation.The hot extruded Mg-1.8Gd-0.3Zr(wt.%)alloy sheet was subjected to three different passes of rolling,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Gd atoms along high and low-angel grain boundaries(GBs).Under almost precipitation-free conditions,the strength and ductility of rolled alloy sheets are simultaneously improved after annealing.Especially for the annealed 3-passes-rolled specimen,the yield strength,ultimate tensile strength,and elongation are simultaneously increased by 11.2%,7.3%,and 18%,respectively.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects,including dislocation annihilation and grain coarsening during the heating.Meanwhile,the directional migration of Gd atoms and the annihilation of dislocations provide a“clear”space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.
基金Project supported by the National Natural Science Foundation of China(52301041)Guizhou Provincial Science and Technology Projects(Qingnian No.2024-123)the Special Fund for Special Posts of Guizhou University(2023-26,2023-53)。
文摘In this study,a novel strategy for breaking the strength-ductility dilemma of Mg-1.5Zn-0.6Gd(wt%)alloy via solute segregation was reported.The hot extruded alloy sheet was subjected to rolling deformation,and then heat-treated at 200℃.The high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM)reveals a remarkable segregation of solute Zn atoms along both high and lowangle grain boundaries(GBs).As compared with as-rolled plate,the yield strength,ultimate tensile strength,and the elongation of annealed sample is increased by 15.6%,14%,and 8.4%,respectively,acquiring an obvious strength-ductility synergy effect.The solute segregation endows the rolled plate with excellent grain size stability and provides a prominent extra solute cluster strengthening,which completely resists the other softening effects including dislocation annihilation and grain coarsening.Meanwhile,the directional migration of Zn atoms and the annihilation of dislocations provide a"clear"space within the grain,which is beneficial for the moving and accumulating of subsequent dislocations.This work sheds light on the solute partitioning behavior and realizes a good application of GB segregation in improving the comprehensive mechanical properties of Mg alloys.
基金supported by the National Natural Science Foundation of China(Grant Nos.52174321,52274339,52204348)the Jiangsu Achievement Transformation Fund Project(Grant No.SBA2023030047)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_3310).
文摘In order to investigate the segregation process and clarify its effect on the formation of TiN during the solidification of a micro-alloy steel containing titanium(Ti),a new mathematical model concerning solute transportation,solidification,as well as TiN precipitation was successfully established and verified.The transportation of solute elements was described using the Brody-Fleming microsegregation model,while the thermodynamic principles governing the precipitation of TiN were derived within the framework of the model.Additionally,the model accounts for variations in the diffusion coefficient due to phase transition and the influence of non-equilibrium solidification on solute distribution.High-temperature tests were conducted to validate the mathematical model.Results show that during solidification,due to selective crystallization,there is positive segregation of Ti and N in the solidifying front.What’s more,due to the high cooling rate near the surface of this steel,negative segregation is easier to be formed in the surface area.The highest concentration of TiN precipitation is found in the 1/4 width of this steel.High-temperature experiment shows that when the solidifying front reaches the 1/4 width of the specimen,the concentration product of Ti and N elements biased at the solidifying front reaches the thermodynamic conditions of TiN precipitation,and exists a higher concentration of TiN distributed in this region.To address this phenomenon,a comparative analysis of the effects of cooling rate and initial solute element content on TiN precipitation behavior was conducted.An increase in the surface cooling rate accelerates the progression of the solidification front and diminishes solute segregation near the front,thereby reducing TiN precipitation.However,with the increase of the initial solute element content,the concentration product of Ti and N elements rises,then the content of TiN precipitation increases.The results of this model provide important insight into the micro segregation and TiN precipitation mechanism of the micro-alloy steels bearing titanium.
基金support from the National Natural Science Foundation of China(Nos.22173034,11974128,52130101)the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure(No.SKL202206SIC)+2 种基金the Program of Innovative Research Team(in Science and Technology)in University of Jilin Province,the Program for JLU(Jilin University)Science and Technology Innovative Research Team(No.2017TD-09)the Fundamental Research Funds for the Central Universitiesthe computing resources of the High Performance Computing Center of Jilin University,China.
文摘The control of solute segregation at grain boundaries is of significance in engineering alloy properties.However,there is currently a lack of a physics-informed predictive model for estimating solute segre-gation energies.Here we propose novel electronic descriptors for grain-boundary segregation based on the valence,electronegativity and size of solutes.By integrating the non-local coordination number of surfaces,we build a predictive analytic framework for evaluating the segregation energies across various solutes,grain-boundary structures,and segregation sites.This framework uncovers not only the coupling rule of solutes and matrices,but also the origin of solute-segregation determinants,which stems from the d-and sp-states hybridization in alloying.Our scheme establishes a novel picture for grain-boundary segregation and provides a useful tool for the design of advanced alloys.
基金supported by the National Natural Science Foundation of China(Nos.52222409 and U24A20104)the National Key Research and Development Program(No.2024YFB3408900)+1 种基金Partial financial support came from the Fundamental Research Funds for the Central Universities,JLUsupported by the High Performance Computing Center of Jilin University,China.
文摘Solute segregation at grain boundaries(GBs)can significantly influence GB cohesion.In this work,the segregation energies of solutes(Zn,Al,Ag,Ca,and Gd)were first investigated at six symmetrical tilt GBs rotating around[0001]axis of Mg,to uncover the impact of GB characteristics on solute segregation behavior.The results reveal that solute segregation propensity is closely related to the local geometric environment of GB sites,but has little correlation with intrinsic GB properties(such as GB misorientation and GB energy).Furthermore,relationships between GB site characteristics and solute segregation tendencies were established.Ca-like solutes tend to occupy GB sites with larger Voronoi volumes(V),while Zn-like solutes prefer GB sites with smaller V as well as smaller shortest bond lengths(SBL).Based on this finding,we further evaluated the segregation capacities of 26 solutes at their most energetically stable segregation sites and their impact on GB cohesion.A descriptor that can effectively capture the strengthening/embrittling potency of segregated solutes on GBs was proposed by performing the crystal orbital Hamilton population(COHP)analyses.It was found that the discrepancies in bond strength between GBs and free surface dominate the solute-strengthening behavior.Finally,a first-principles“design map”regarding the segregation energies and strengthening energies was provided,which offers a database for designing Mg alloys with high fracture toughness.
