The three-component coupling reaction of ethyl propiolate (1), phthalimide (2), and aldehyde (3) catalyzed by tripheny- lphosphine, was developed. A solution of an equivalent amount of 1 and 2 in benzaldehyde (3a) in ...The three-component coupling reaction of ethyl propiolate (1), phthalimide (2), and aldehyde (3) catalyzed by tripheny- lphosphine, was developed. A solution of an equivalent amount of 1 and 2 in benzaldehyde (3a) in the presence of 30 mol% of PPh3 was heated at 100?C for 48 h to give N-(1-ethoxycarbonyl-3-oxo-3-phenylpropyl)phthalimide (4a) in 83% yield. This reaction was thought to proceed via vinylphosphonium salt formed from the reaction of ethyl propiolate (1) with triphenylphosphine in situ.展开更多
Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing addit...Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.展开更多
In order to more accurately and effectively consider the propagation process of solitons in electromagnetic pulse waves and make full use of wavelength division multiplexing,we study a class of high-order three-compon...In order to more accurately and effectively consider the propagation process of solitons in electromagnetic pulse waves and make full use of wavelength division multiplexing,we study a class of high-order three-component Hirota equations by the Riemann-Hilbert method.Under zero boundary conditions and given initial conditions q_(j)(x,0),the N-soliton solutions of the equations are obtained by constructing and solving Riemann-Hilbert problems based on matrix spectral problem.Specifically,we discuss the cases of N=1,2,analyze the dynamical properties of 1-soliton and 2-soliton solutions through numerical simulations,and summarize the effect of integrable perturbations and spectral parameters on soliton motion.展开更多
Summary of main observation and conclusion An efficient Pd-catalyzed three-component coupling reaction of allyl carboxylates, norbornenes and diboronates is described, which allows efficient assembly of C(sp3)-C(sp3) ...Summary of main observation and conclusion An efficient Pd-catalyzed three-component coupling reaction of allyl carboxylates, norbornenes and diboronates is described, which allows efficient assembly of C(sp3)-C(sp3) and C(sp3)-B bonds in a single process. Moreover, this approach shows advantages of good chemo- and regioselectivity, as well as good substrates suitability.展开更多
Ureas are widely used in drugs,materials and catalysts because of their diamide structure,which can form strong hydrogen bonds.Therefore,it is of great scientific significance to develop efficient and green methods fo...Ureas are widely used in drugs,materials and catalysts because of their diamide structure,which can form strong hydrogen bonds.Therefore,it is of great scientific significance to develop efficient and green methods for the synthesis of urea compounds,especially unsymmetrical ureas.Here,we have disclosed novel and highly efficient three-component coupling reactions of organic halides,sodium cyanate and amines enabled by nickel/photoredox dual catalysis for the preparation of unsymmetrical ureas.The reaction features simple and safe operations,broad substrate scopes,and product diversities.It allows the facile synthesis of N-aryl/vinyl ureas from readily available,user-friendly feedstocks under mild conditions(27 examples,36%—98%yields).In addition,this method is further derived to alcohols as nucleophiles to synthesize a series of carbamates(15 examples,40%—95%yields).The mechanism experiment shows that the isocyanate produced by the coupling of halide and sodium cyanate may be the key intermediate in this reaction.展开更多
A copper-catalyzed three-component reaction involving cyclic carbonates,elemental sulfur,and H-phosphonates is presented.It proceeds with excellent yields and provides an attractive approach for the construction of va...A copper-catalyzed three-component reaction involving cyclic carbonates,elemental sulfur,and H-phosphonates is presented.It proceeds with excellent yields and provides an attractive approach for the construction of valuable trisubstituted allenyl phosphorothioates using a one-step strategy.Moreover,this method can be easily adapted to large-scale preparation.展开更多
Multicomponent alkene 1,2-dicarbofunctionalizations(DCFs)have emerged as a powerful strategy to rapidly incorporate both two carbon subunits across one C-C double bond in one step for enhancing molecular complexity an...Multicomponent alkene 1,2-dicarbofunctionalizations(DCFs)have emerged as a powerful strategy to rapidly incorporate both two carbon subunits across one C-C double bond in one step for enhancing molecular complexity and diversity.To the best of our knowledge,there is only one report on photoredox-catalyzed three-component DCFs with malonates through the radical−radical cross-coupling,while photoredox-catalyzed radical-polar crossover(RPC)-type DCFs with malonates were still rare.Herein,we describe a redox-neutral RPC-type 1,2-dialkylation of styrenes with malonates and aldehydes through the synergistic Brønsted base/photoredox catalysis system.This transition-metal-free strategy provides an efficient and clean approach to a broad variety ofδ-hydroxy esters and also features exceptionally mild conditions,wide compatibility of substrate scope and functional groups,and high atomic economy.Moreover,three-component 1,2-alkylacylation from the same starting materials was achieved in one-pot manner through such RPC-type coupling and subsequent two-electron oxidation process,providing a set ofδ-keto esters of interest in pharmaceutical research.展开更多
Controlled integration of ultrafine metal nanoparticles （MNPs） and metal- organic frameworks （MOFs） has drawn much attention due to their unique physical and chemical properties. However, the development of a one-...Controlled integration of ultrafine metal nanoparticles （MNPs） and metal- organic frameworks （MOFs） has drawn much attention due to their unique physical and chemical properties. However, the development of a one-step strategy for preparing ultrafine MNPs within MOFs still remains a great challenge. Herein, a facile synthetic approach toward the abovementioned composites was developed. In contrast to the conventional approach, these hybrids were prepared by the direct mixing of metal and MOF precursors in the reaction solution assisted by microwave irradiation. Impressively, the Au/MOF-199 composite with uniformly distributed ultrafine Au nanoparticles could be fabricated in only two minutes, and the Au loading could be increased up to a level of 5.13%. The multifunctional Au/MOF-199 catalysts exhibited high turnover numbers （TONs） and turnover frequencies （TOFs） in the three-component coupling reaction of formaldehyde, phenylacetylene, and piperidine （AB-coupling）. Owing to the confinement effect of MOF-199, the 5.13%Au/MOF-199 catalyst could be recycled for five runs without serious loss of activity, with no obvious aggregation of Au NPs detected.展开更多
Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,how...Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,however,constrain their delicate constructions.Herein,an innovative alternative is proposed:carrageenan-assistant cations-regulated(CACR)strategy,which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix.This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction,benefiting the delicate construction of defects-rich heterostructures in M_(x)S_(y)/carbon composites(M-CAs).Impressively,these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and,simultaneously,induct local asymmetry of electronic structure to evoke large dipole moment,ultimately leading to polarization coupling,i.e.,defect-type interfacial polarization.Such“Janus effect”(Janus effect means versatility,as in the Greek two-headed Janus)of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time.Consequently,the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm,compared to sulfur vacancies-free CAs without any dielectric response.Harnessing defects-rich heterostructures,this one-pot CACR strategy may steer the design and development of advanced nanomaterials,boosting functionality across diverse application domains beyond electromagnetic response.展开更多
We study the generalized Darboux transformation to the three-component coupled nonlinear Schr ¨odinger equation.First-and second-order localized waves are obtained by this technique.In first-order localized wave,...We study the generalized Darboux transformation to the three-component coupled nonlinear Schr ¨odinger equation.First-and second-order localized waves are obtained by this technique.In first-order localized wave,we get the interactional solutions between first-order rogue wave and one-dark,one-bright soliton respectively.Meanwhile,the interactional solutions between one-breather and first-order rogue wave are also given.In second-order localized wave,one-dark-one-bright soliton together with second-order rogue wave is presented in the first component,and two-bright soliton together with second-order rogue wave are gained respectively in the other two components.Besides,we observe second-order rogue wave together with one-breather in three components.Moreover,by increasing the absolute values of two free parameters,the nonlinear waves merge with each other distinctly.These results further reveal the interesting dynamic structures of localized waves in the three-component coupled system.展开更多
Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression an...Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.展开更多
The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and di...The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and discrete element method(DEM)was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack.The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road.Finally,an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress,vertical shear stress,and vertical compressive stress.The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface,while the longitudinal development of TD crack has minimal impact.This phenomenon may result in more severe fatigue failure on the middle surface.With the vertical and longitudinal development of TD crack,the vertical shear stress and compressive stress show obvious"two-stage"characteristics.When the crack's vertical length reaches 40 mm,there is a sharp increase in stress on the upper surface.As the crack continues to propagate vertically,the growth of stress on the upper surface becomes negligible,while the stress in the middle and lower layers increased significantly.Conversely,for longitudinal development of TD crack,any changes in stress are insignificant when their length is less than 180 mm;however,as they continue to develop longitudinally beyond this threshold,there is a sharp increase in stress levels.These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.展开更多
Electrochemical conversion of lignin for the production of high-value heterocyclic aromatic compounds has great potential.We demonstrate the targeted synthesis and cation modulation of NiCo_(2)O_(4)spinel nanoboxes,sy...Electrochemical conversion of lignin for the production of high-value heterocyclic aromatic compounds has great potential.We demonstrate the targeted synthesis and cation modulation of NiCo_(2)O_(4)spinel nanoboxes,synthesized via cation exchange and calcination oxidation.These catalysts exhibit excellent efficacy in the electrocatalytic conversion of lignin model compounds,specifically 2-phenoxy-1-phenylethanol,into nitrogen-containing aromatics,achieving high conversion rates and selectivities.These catalysts were synthesized via a cation exchange and calcination oxidation process,using Prussian blue nanocubes as precursors.The porous architecture and polymetallic composition of the NiCo_(2)O_(4)spinel demonstrated superior performance in electrocatalytic oxidative coupling,achieving a 99.2 wt%conversion rate of the 2-phenoxy-1-phenylethanol with selectivities of 37.5 wt%for quinoline derivatives and 31.5 wt%for phenol.Key innovations include the development of a sustainable one-pot synthesis method for quinoline derivatives,the elucidation of a multistage reaction pathway involving CAO bond cleavage,hydroxyaldol condensation,and CAN bond formation,and a deeper mechanistic understanding derived from DFT simulations.This work establishes a new strategy for lignin valorization,offering a sustainable route to produce high-value nitrogen-containing aromatics from renewable biomass under mild conditions,without the need for additional reagents.展开更多
Studying the coupling coordination development of new energy vehicles(NEVs)and the ecological environment in China is helpful in promoting the development of NEVs in the country and is of great significance in promoti...Studying the coupling coordination development of new energy vehicles(NEVs)and the ecological environment in China is helpful in promoting the development of NEVs in the country and is of great significance in promoting high-quality development of new energy in China.This paper constructs an evaluation index system for the development of NEVs and the ecological environment.It uses game theory combining weighting model,particle swarm optimized projection tracking evaluation model,coupling coordination degree model,and machine learning algorithms to calculate and analyze the level of coupling coordination development of NEVs and the ecological environment in China from 2010 to 2021,and identifies the driving factors.The research results show that:(i)From 2010 to 2021,the development index of NEVs in China has steadily increased from 0.085 to 0.634,while the ecological environment level index significantly rose from 0.170 to 0.884,reflecting the continuous development of China in both NEVs and the ecological environment.(ii)From 2010 to 2012,the two systems—new energy vehicle(NEV)development and the ecological environment—were in a period of imbalance and decline.From 2013 to 2016,they underwent a transition period,and from 2017 to 2021,they entered a period of coordinated development showing a trend of benign and continuous improvement.By 2021,they reached a good level of coordination.(iii)Indicators such as the number of patents granted for NEVs,water consumption per unit of GDP,and energy consumption per unit of GDP are the main driving factors affecting the coupling coordination development of NEVs and the ecological environment in China.展开更多
This study investigates the coordination between regional economic growth and ecological sustainability within the context of high-quality town economy development.To address the challenges of balancing economic expan...This study investigates the coordination between regional economic growth and ecological sustainability within the context of high-quality town economy development.To address the challenges of balancing economic expansion with environmental protection,a comprehensive evaluation index system is constructed,encompassing two key dimensions:regional economy and ecological environment.Using panel data from 2013 to 2022,the coupling coordination degree model is employed to quantify the interactions and synergy between these dimensions.Additionally,spatial econometric methods are applied to calculate both global and local Moran’s Index,revealing spatial clustering patterns,regional disparities,and heterogeneity.The relative development model further identifies critical factors influencing regional coordination,with a focus on the lagging development of basic infrastructure and public services.The findings demonstrate a positive temporal trend toward improved regional coordination and reduced development gaps,with a spatial pattern characterized by higher coupling degrees in eastern and central regions compared to western areas.Based on these results,this study proposes actionable strategies to enhance coordinated development,emphasizing ecological conservation,the establishment of green production and consumption systems,ecological restoration,and strengthened municipal collaboration.This revised abstract emphasizes the study’s purpose,methods,and key findings more clearly while maintaining a professional and concise tone.Finally,based on the above analysis results,the corresponding coordinated development suggestions of regional economy and ecological environment are given from the aspects of ecological environment protection measures,green production and consumption system construction,ecological environment restoration and municipal coordination.展开更多
As the main geomaterials for coral reefs oil or gas extraction and underground infrastructure construction,coral reef limestone demonstrates significantly distinct mechanical responses compared to terrigenous rocks.To...As the main geomaterials for coral reefs oil or gas extraction and underground infrastructure construction,coral reef limestone demonstrates significantly distinct mechanical responses compared to terrigenous rocks.To investigate the mechanical behaviour of coral reef limestone under the coupling impact of size and strain rate,the uniaxial compression tests were conducted on reef limestone samples with length-to-diameter(L/D)ratio ranging from 0.5 to 2.0 at strain rate ranging from 10^(−5)·s^(−1)to 10^(−2)·s^(−1).It is revealed that the uniaxial compressive strength(UCS)and residual compressive strength(RCS)of coral reef limestone exhibits a decreasing trend with L/D ratio increasing.The dynamic increase factor(DIF)of UCS is linearly correlated with the logarithm of strain rate,while increasing the L/D ratio further enhances the DIF.The elastic modulus increases with strain rate or L/D ratio increasing,whereas the Poisson’s ratio approximates to a constant value of 0.24.The failure strain increases with strain rate increasing or L/D ratio decreasing,while the increase in L/D ratio will inhibit the enhancing effect of the strain rate.The high porosity and low mineral strength are the primary factors contributing to a high RCS of 16.7%–64.9%of UCS,a lower brittleness index and multiple irregular fracture planes.The failure pattern of coral reef limestone transits from the shear-dominated to the splitting-dominated failure with strain rate increasing or L/D ratio decreasing,which is mainly governed by the constrained zones induced by end friction and the strain rate-dependent crack propagation.Moreover,a predictive formula incorporating coupling effect of size and strain rate for the UCS of reef limestone was established and verified to effectively capture the trend of UCS.展开更多
The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and run...The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.展开更多
Ultra-precision components have been widely used to produce advanced optoelectronic equipment.The so-called Electric field enhanced UltraViolet-Induced Jet Machining(EUV-INCJM)is an ultra-precision method that can ach...Ultra-precision components have been widely used to produce advanced optoelectronic equipment.The so-called Electric field enhanced UltraViolet-Induced Jet Machining(EUV-INCJM)is an ultra-precision method that can achieve sub-nanometer level surface quality polishing.This study focuses on the application of the EUV-INCJM with different nozzle structures to a single-crystal of silicon.Two kinds of electro-optic-liquid coupling nozzles with single-jet and multi-jet focusing structures are proposed accordingly.Simulations and experiments have been conducted to verify the material removal performance of these nozzles.The simulation results show that,under the same condition,the flow velocity of the single-jet nozzle is 1.05 times higher than that achieved with the multi-jet configuration,while the current density of the latter is 1.63 times higher than that of the single-jet nozzle.For the single-crystal silicon,the material removal efficiency of the multi-jet focusing nozzle exceeds by about 1.4 times that of the single-jet.These results confirm that the material removal ability of the multi-jet configuration is more suitable for ultra-smooth surface polishing.The surface roughness of Si workpiece was reduced from Rq 1.55 to Rq 0.816 nm with valleys and peaks on its surface being almost completely removed.展开更多
Dislocations and disclinations are fundamental topological defects within crystals,which determine the mechanical properties of metals and alloys.Despite their important roles in multiple physical mechanisms,e.g.,dyna...Dislocations and disclinations are fundamental topological defects within crystals,which determine the mechanical properties of metals and alloys.Despite their important roles in multiple physical mechanisms,e.g.,dynamic recovery and grain boundary mediated plasticity,the intrinsic coupling and correlation between disclinations and dislocations,and their impacts on the deformation behavior of metallic materials still remain obscure,partially due to the lack of a theoretical tool to capture the rotational nature of disclinations.By using a Lie-algebra-based theoretical framework,we obtain a general equation to quantify the intrinsic coupling of disclinations and dislocations.Through quasi in-situ electron backscatter diffraction characterizations and disclination/dislocation density analyses in Mg alloys,the generation,coevolution and reactions of disclinations and dislocations during dynamic recovery and superplastic deformation have been quantitatively analyzed.It has been demonstrated that the obtained governing equation can capture multiple physical processes associated with mechanical deformation of metals,e.g.,grain rotation and grain boundary migration,at both room temperature and high temperature.By establishing the disclination-dislocation coupling equation within a Lie algebra description,our work provides new insights for exploring the coevolution and reaction of disclinations/dislocations,with profound implications for elucidating the microstructure-property relationship and underlying deformation mechanisms in metallic materials.展开更多
Self-trapping excitons(STEs) emission in metal halides has been a matter of interest, correlating with the strength of electron-phonon coupling in the lattice, which are usually caused by ions with ns~2 electronic str...Self-trapping excitons(STEs) emission in metal halides has been a matter of interest, correlating with the strength of electron-phonon coupling in the lattice, which are usually caused by ions with ns~2 electronic structure. In this work, Sb^(3+)/Te^(4+)ions doped Zn-based halide single crystals(SCs) with two STEs emissions have been synthesized and the possibility of its anti-counterfeiting application was explored.Further, the relationship between the strength of electron-phonon coupling and photoluminescence quantum yields(PLQYs) for STEs in a series of metal halides has been studied. And the semi-empirical range of the Huang-Rhys factors(S) for metal halides with excellent photoluminescence(PL) property has been summarized. This work provides ideas for further research into the relationship between luminescence performance and electron-phonon coupling of metal halides, and also provides a reference for designing the metal halides with high PLQYs.展开更多
文摘The three-component coupling reaction of ethyl propiolate (1), phthalimide (2), and aldehyde (3) catalyzed by tripheny- lphosphine, was developed. A solution of an equivalent amount of 1 and 2 in benzaldehyde (3a) in the presence of 30 mol% of PPh3 was heated at 100?C for 48 h to give N-(1-ethoxycarbonyl-3-oxo-3-phenylpropyl)phthalimide (4a) in 83% yield. This reaction was thought to proceed via vinylphosphonium salt formed from the reaction of ethyl propiolate (1) with triphenylphosphine in situ.
基金National Key Research and Development Program of China(2022YFB4600902)Shandong Provincial Science Foundation for Outstanding Young Scholars(ZR2024YQ020)。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising approach for fabricating large-scale components.However,conventional WAAM still faces challenges in optimizing microstructural evolution,minimizing additive-induced defects,and alleviating residual stress and deformation,all of which are critical for enhancing the mechanical performance of the manufactured parts.Integrating interlayer friction stir processing(FSP)into WAAM significantly enhances the quality of deposited materials.However,numerical simulation research focusing on elucidating the associated thermomechanical coupling mechanisms remains insufficient.A comprehensive numerical model was developed to simulate the thermomechanical coupling behavior in friction stir-assisted WAAM.The influence of post-deposition FSP on the coupled thermomechanical response of the WAAM process was analyzed quantitatively.Moreover,the residual stress distribution and deformation behavior under both single-layer and multilayer deposition conditions were investigated.Thermal analysis of different deposition layers in WAAM and friction stir-assisted WAAM was conducted.Results show that subsequent layer deposition induces partial remelting of the previously solidified layer,whereas FSP does not cause such remelting.Furthermore,thermal stress and deformation analysis confirm that interlayer FSP effectively mitigates residual stresses and distortion in WAAM components,thereby improving their structural integrity and mechanical properties.
基金Project supported by Shaanxi Scholarship Council of China(Grant No.2021-030)the Youth Scientific Research Project of Shaanxi Province,China(Grant No.202103021223060)。
文摘In order to more accurately and effectively consider the propagation process of solitons in electromagnetic pulse waves and make full use of wavelength division multiplexing,we study a class of high-order three-component Hirota equations by the Riemann-Hilbert method.Under zero boundary conditions and given initial conditions q_(j)(x,0),the N-soliton solutions of the equations are obtained by constructing and solving Riemann-Hilbert problems based on matrix spectral problem.Specifically,we discuss the cases of N=1,2,analyze the dynamical properties of 1-soliton and 2-soliton solutions through numerical simulations,and summarize the effect of integrable perturbations and spectral parameters on soliton motion.
基金the National Program on Key Research Project (No. 2016YFA0602900)the National Natural Science Foundation of China (No. 21420102003)the Guangdong Province Science Foundation (No. 2017B090903003) for financial support.
文摘Summary of main observation and conclusion An efficient Pd-catalyzed three-component coupling reaction of allyl carboxylates, norbornenes and diboronates is described, which allows efficient assembly of C(sp3)-C(sp3) and C(sp3)-B bonds in a single process. Moreover, this approach shows advantages of good chemo- and regioselectivity, as well as good substrates suitability.
基金the National Natural Science Foundation of Chinaa(Nos.22271113,92256301,21822103,91956201,21820102003 and 21602052)the Natural Science Foundation of Hubei Province(No.2022CFB413)the fund from Central China Normal University for support of this research.
文摘Ureas are widely used in drugs,materials and catalysts because of their diamide structure,which can form strong hydrogen bonds.Therefore,it is of great scientific significance to develop efficient and green methods for the synthesis of urea compounds,especially unsymmetrical ureas.Here,we have disclosed novel and highly efficient three-component coupling reactions of organic halides,sodium cyanate and amines enabled by nickel/photoredox dual catalysis for the preparation of unsymmetrical ureas.The reaction features simple and safe operations,broad substrate scopes,and product diversities.It allows the facile synthesis of N-aryl/vinyl ureas from readily available,user-friendly feedstocks under mild conditions(27 examples,36%—98%yields).In addition,this method is further derived to alcohols as nucleophiles to synthesize a series of carbamates(15 examples,40%—95%yields).The mechanism experiment shows that the isocyanate produced by the coupling of halide and sodium cyanate may be the key intermediate in this reaction.
基金supported by the Educational Foundation of Zhejiang University of Technology(No.KYY-HX-20220471)。
文摘A copper-catalyzed three-component reaction involving cyclic carbonates,elemental sulfur,and H-phosphonates is presented.It proceeds with excellent yields and provides an attractive approach for the construction of valuable trisubstituted allenyl phosphorothioates using a one-step strategy.Moreover,this method can be easily adapted to large-scale preparation.
基金supported by the National Natural Science Foundation of China(Nos.22101237,22171233)the Science and Technology Program of Sichuan Province(No.2022NSFSC1219)+1 种基金the Science and Technology Program of Luzhou City(Nos.2021-SYF-34,2023LZXNYDJ019)and the Open Project Program of Nuclear Medicine and Molecular Imaging Key Laboratory of Sichuan Province(No.HYX21003).
文摘Multicomponent alkene 1,2-dicarbofunctionalizations(DCFs)have emerged as a powerful strategy to rapidly incorporate both two carbon subunits across one C-C double bond in one step for enhancing molecular complexity and diversity.To the best of our knowledge,there is only one report on photoredox-catalyzed three-component DCFs with malonates through the radical−radical cross-coupling,while photoredox-catalyzed radical-polar crossover(RPC)-type DCFs with malonates were still rare.Herein,we describe a redox-neutral RPC-type 1,2-dialkylation of styrenes with malonates and aldehydes through the synergistic Brønsted base/photoredox catalysis system.This transition-metal-free strategy provides an efficient and clean approach to a broad variety ofδ-hydroxy esters and also features exceptionally mild conditions,wide compatibility of substrate scope and functional groups,and high atomic economy.Moreover,three-component 1,2-alkylacylation from the same starting materials was achieved in one-pot manner through such RPC-type coupling and subsequent two-electron oxidation process,providing a set ofδ-keto esters of interest in pharmaceutical research.
基金The authors acknowledge the financial support from the National Natural Science Foundation of China （Nos. 21573286, 21173269, and 21572688）, Ministry ofScience and Technology of China （Nos. 2011BAK15B05 and 2015AA034603）, Specialized Research Fund for the Doctoral Program of Higher Education （No. 20130007110003）, and Science Foundation of China University of Petroleum, Beijing （No. 2462015YQ0304）.
文摘Controlled integration of ultrafine metal nanoparticles （MNPs） and metal- organic frameworks （MOFs） has drawn much attention due to their unique physical and chemical properties. However, the development of a one-step strategy for preparing ultrafine MNPs within MOFs still remains a great challenge. Herein, a facile synthetic approach toward the abovementioned composites was developed. In contrast to the conventional approach, these hybrids were prepared by the direct mixing of metal and MOF precursors in the reaction solution assisted by microwave irradiation. Impressively, the Au/MOF-199 composite with uniformly distributed ultrafine Au nanoparticles could be fabricated in only two minutes, and the Au loading could be increased up to a level of 5.13%. The multifunctional Au/MOF-199 catalysts exhibited high turnover numbers （TONs） and turnover frequencies （TOFs） in the three-component coupling reaction of formaldehyde, phenylacetylene, and piperidine （AB-coupling）. Owing to the confinement effect of MOF-199, the 5.13%Au/MOF-199 catalyst could be recycled for five runs without serious loss of activity, with no obvious aggregation of Au NPs detected.
基金financially supported by the National Natural Science Foundation of China(Grants nos.62201411,62371378,22205168,52302150 and 62304171)the China Postdoctoral Science Foundation(2022M722500)+1 种基金the Fundamental Research Funds for the Central Universities(Grants nos.ZYTS2308 and 20103237929)Startup Foundation of Xidian University(10251220001).
文摘Defects-rich heterointerfaces integrated with adjustable crystalline phases and atom vacancies,as well as veiled dielectric-responsive character,are instrumental in electromagnetic dissipation.Conventional methods,however,constrain their delicate constructions.Herein,an innovative alternative is proposed:carrageenan-assistant cations-regulated(CACR)strategy,which induces a series of sulfides nanoparticles rooted in situ on the surface of carbon matrix.This unique configuration originates from strategic vacancy formation energy of sulfides and strong sulfides-carbon support interaction,benefiting the delicate construction of defects-rich heterostructures in M_(x)S_(y)/carbon composites(M-CAs).Impressively,these generated sulfur vacancies are firstly found to strengthen electron accumulation/consumption ability at heterointerfaces and,simultaneously,induct local asymmetry of electronic structure to evoke large dipole moment,ultimately leading to polarization coupling,i.e.,defect-type interfacial polarization.Such“Janus effect”(Janus effect means versatility,as in the Greek two-headed Janus)of interfacial sulfur vacancies is intuitively confirmed by both theoretical and experimental investigations for the first time.Consequently,the sulfur vacancies-rich heterostructured Co/Ni-CAs displays broad absorption bandwidth of 6.76 GHz at only 1.8 mm,compared to sulfur vacancies-free CAs without any dielectric response.Harnessing defects-rich heterostructures,this one-pot CACR strategy may steer the design and development of advanced nanomaterials,boosting functionality across diverse application domains beyond electromagnetic response.
基金Project supported by the Global Change Research Program of China(Grant No.2015CB953904)the National Natural Science Foundation of China(Grant Nos.11275072 and 11435005)+2 种基金the Doctoral Program of Higher Education of China(Grant No.20120076110024)the Network Information Physics Calculation of Basic Research Innovation Research Group of China(Grant No.61321064)Shanghai Collaborative Innovation Center of Trustworthy Software for Internet of Things,China(Grant No.ZF1213)
文摘We study the generalized Darboux transformation to the three-component coupled nonlinear Schr ¨odinger equation.First-and second-order localized waves are obtained by this technique.In first-order localized wave,we get the interactional solutions between first-order rogue wave and one-dark,one-bright soliton respectively.Meanwhile,the interactional solutions between one-breather and first-order rogue wave are also given.In second-order localized wave,one-dark-one-bright soliton together with second-order rogue wave is presented in the first component,and two-bright soliton together with second-order rogue wave are gained respectively in the other two components.Besides,we observe second-order rogue wave together with one-breather in three components.Moreover,by increasing the absolute values of two free parameters,the nonlinear waves merge with each other distinctly.These results further reveal the interesting dynamic structures of localized waves in the three-component coupled system.
基金financially supported by the National Natural Science Foundation of China(Nos.42272153 and 42472195)the Research Fund of PetroChina Tarim Oilfield Company(No.671023060003)the Research Fund of China National Petroleum Corporation Limited(No.2023ZZ16YJ04).
文摘Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.
基金supported by National Key R&D Program of China(Grant No.2021YFB2601200)Open Fund of National Engineering Research Center of Highway Maintenance Technology(Changsha University of Science&Technology)(No.kfj230207).
文摘The occurrence of top-down(TD)cracking has gradually become a prevalent issue in semi-rigid base asphalt pavements after prolonged service.A coupled simulation model integrating the finite difference method(FDM)and discrete element method(DEM)was employed to investigate the mechanical behavior of asphalt pavement containing a pre-existing TD crack.The mesoscopic parameters of the model were calibrated based on the mixture modulus and the static mechanical response on the MLS66 test road.Finally,an analysis was performed to assess how variations in TD crack depth and longitudinal length affect the distribution patterns of transverse tensile stress,vertical shear stress,and vertical compressive stress.The results indicate that the vertical propagation of TD crack significantly increases both the tensile stress value and range on the middle surface,while the longitudinal development of TD crack has minimal impact.This phenomenon may result in more severe fatigue failure on the middle surface.With the vertical and longitudinal development of TD crack,the vertical shear stress and compressive stress show obvious"two-stage"characteristics.When the crack's vertical length reaches 40 mm,there is a sharp increase in stress on the upper surface.As the crack continues to propagate vertically,the growth of stress on the upper surface becomes negligible,while the stress in the middle and lower layers increased significantly.Conversely,for longitudinal development of TD crack,any changes in stress are insignificant when their length is less than 180 mm;however,as they continue to develop longitudinally beyond this threshold,there is a sharp increase in stress levels.These findings hold great significance for understanding pavement structure deterioration and maintenance behavior associated with TD crack.
基金National Natural Science Foundation of China (U23A6005 and 22078069)Project funded by China Postdoctoral Science Foundation (GZB20230172 and 2023M740748)。
文摘Electrochemical conversion of lignin for the production of high-value heterocyclic aromatic compounds has great potential.We demonstrate the targeted synthesis and cation modulation of NiCo_(2)O_(4)spinel nanoboxes,synthesized via cation exchange and calcination oxidation.These catalysts exhibit excellent efficacy in the electrocatalytic conversion of lignin model compounds,specifically 2-phenoxy-1-phenylethanol,into nitrogen-containing aromatics,achieving high conversion rates and selectivities.These catalysts were synthesized via a cation exchange and calcination oxidation process,using Prussian blue nanocubes as precursors.The porous architecture and polymetallic composition of the NiCo_(2)O_(4)spinel demonstrated superior performance in electrocatalytic oxidative coupling,achieving a 99.2 wt%conversion rate of the 2-phenoxy-1-phenylethanol with selectivities of 37.5 wt%for quinoline derivatives and 31.5 wt%for phenol.Key innovations include the development of a sustainable one-pot synthesis method for quinoline derivatives,the elucidation of a multistage reaction pathway involving CAO bond cleavage,hydroxyaldol condensation,and CAN bond formation,and a deeper mechanistic understanding derived from DFT simulations.This work establishes a new strategy for lignin valorization,offering a sustainable route to produce high-value nitrogen-containing aromatics from renewable biomass under mild conditions,without the need for additional reagents.
基金Supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX24_0102)the China Scholarship Council Program(202406190114)。
文摘Studying the coupling coordination development of new energy vehicles(NEVs)and the ecological environment in China is helpful in promoting the development of NEVs in the country and is of great significance in promoting high-quality development of new energy in China.This paper constructs an evaluation index system for the development of NEVs and the ecological environment.It uses game theory combining weighting model,particle swarm optimized projection tracking evaluation model,coupling coordination degree model,and machine learning algorithms to calculate and analyze the level of coupling coordination development of NEVs and the ecological environment in China from 2010 to 2021,and identifies the driving factors.The research results show that:(i)From 2010 to 2021,the development index of NEVs in China has steadily increased from 0.085 to 0.634,while the ecological environment level index significantly rose from 0.170 to 0.884,reflecting the continuous development of China in both NEVs and the ecological environment.(ii)From 2010 to 2012,the two systems—new energy vehicle(NEV)development and the ecological environment—were in a period of imbalance and decline.From 2013 to 2016,they underwent a transition period,and from 2017 to 2021,they entered a period of coordinated development showing a trend of benign and continuous improvement.By 2021,they reached a good level of coordination.(iii)Indicators such as the number of patents granted for NEVs,water consumption per unit of GDP,and energy consumption per unit of GDP are the main driving factors affecting the coupling coordination development of NEVs and the ecological environment in China.
基金support from Guangdong Science and Technology(20230505)Guangdong Provincial Philosophy and Social Science Planning Project(GD20SQ25)Guangdong Provincial Special Fund for Science and Technology Innovation Strategy in 2024(Cultivation of College Students’Science and Technology Innovation)(pdjh2024a391)during preparation of this manuscript.
文摘This study investigates the coordination between regional economic growth and ecological sustainability within the context of high-quality town economy development.To address the challenges of balancing economic expansion with environmental protection,a comprehensive evaluation index system is constructed,encompassing two key dimensions:regional economy and ecological environment.Using panel data from 2013 to 2022,the coupling coordination degree model is employed to quantify the interactions and synergy between these dimensions.Additionally,spatial econometric methods are applied to calculate both global and local Moran’s Index,revealing spatial clustering patterns,regional disparities,and heterogeneity.The relative development model further identifies critical factors influencing regional coordination,with a focus on the lagging development of basic infrastructure and public services.The findings demonstrate a positive temporal trend toward improved regional coordination and reduced development gaps,with a spatial pattern characterized by higher coupling degrees in eastern and central regions compared to western areas.Based on these results,this study proposes actionable strategies to enhance coordinated development,emphasizing ecological conservation,the establishment of green production and consumption systems,ecological restoration,and strengthened municipal collaboration.This revised abstract emphasizes the study’s purpose,methods,and key findings more clearly while maintaining a professional and concise tone.Finally,based on the above analysis results,the corresponding coordinated development suggestions of regional economy and ecological environment are given from the aspects of ecological environment protection measures,green production and consumption system construction,ecological environment restoration and municipal coordination.
基金supported by the National Natural Science Foundation of China(Nos.52222110,52401354,and 52301353).
文摘As the main geomaterials for coral reefs oil or gas extraction and underground infrastructure construction,coral reef limestone demonstrates significantly distinct mechanical responses compared to terrigenous rocks.To investigate the mechanical behaviour of coral reef limestone under the coupling impact of size and strain rate,the uniaxial compression tests were conducted on reef limestone samples with length-to-diameter(L/D)ratio ranging from 0.5 to 2.0 at strain rate ranging from 10^(−5)·s^(−1)to 10^(−2)·s^(−1).It is revealed that the uniaxial compressive strength(UCS)and residual compressive strength(RCS)of coral reef limestone exhibits a decreasing trend with L/D ratio increasing.The dynamic increase factor(DIF)of UCS is linearly correlated with the logarithm of strain rate,while increasing the L/D ratio further enhances the DIF.The elastic modulus increases with strain rate or L/D ratio increasing,whereas the Poisson’s ratio approximates to a constant value of 0.24.The failure strain increases with strain rate increasing or L/D ratio decreasing,while the increase in L/D ratio will inhibit the enhancing effect of the strain rate.The high porosity and low mineral strength are the primary factors contributing to a high RCS of 16.7%–64.9%of UCS,a lower brittleness index and multiple irregular fracture planes.The failure pattern of coral reef limestone transits from the shear-dominated to the splitting-dominated failure with strain rate increasing or L/D ratio decreasing,which is mainly governed by the constrained zones induced by end friction and the strain rate-dependent crack propagation.Moreover,a predictive formula incorporating coupling effect of size and strain rate for the UCS of reef limestone was established and verified to effectively capture the trend of UCS.
基金supported by Sichuan Science and Technology Program(Grant No.2020YFH0080)the National Natural Science Foundation of China(Grant No.51475386)the National Basic Research Project of China(973 Program,Grant No.2015CB654801).
文摘The gear transmission system directly affects the operational performance of high-speed trains(HST).However,current research on gear transmission systems of HST often overlooks the effects of gear eccentricity and running resistance,and the dynamic models of gear transmission system are not sufficiently comprehensive.This paper aims to establish an electromechanical coupling dynamic model of HST traction transmission system and study its electromechanical coupling vibration characteristics,in which the internal excitation factors such as gear eccentricity,time-varying meshing stiffness,backlash,meshing error,and external excitation factors such as electromagnetic torque and running resistance are stressed.The research results indicate that gear eccentricity and running resistance have a significant impact on the stability of the system,and gear eccentricity leads to intensified system vibration and decreased anti-interference ability.In addition,the characteristic frequency of gear eccentricity can be extracted from mechanical signals and current signals as a preliminary basis for eccentricity detection,and electrical signals can also be used to monitor changes in train running resistance in real time.The results of this study provide some useful insights into designing dynamic performance parameters for HST transmission systems and monitoring train operational states.
基金supported by the National Natural Science Foundation of China(52365056).
文摘Ultra-precision components have been widely used to produce advanced optoelectronic equipment.The so-called Electric field enhanced UltraViolet-Induced Jet Machining(EUV-INCJM)is an ultra-precision method that can achieve sub-nanometer level surface quality polishing.This study focuses on the application of the EUV-INCJM with different nozzle structures to a single-crystal of silicon.Two kinds of electro-optic-liquid coupling nozzles with single-jet and multi-jet focusing structures are proposed accordingly.Simulations and experiments have been conducted to verify the material removal performance of these nozzles.The simulation results show that,under the same condition,the flow velocity of the single-jet nozzle is 1.05 times higher than that achieved with the multi-jet configuration,while the current density of the latter is 1.63 times higher than that of the single-jet nozzle.For the single-crystal silicon,the material removal efficiency of the multi-jet focusing nozzle exceeds by about 1.4 times that of the single-jet.These results confirm that the material removal ability of the multi-jet configuration is more suitable for ultra-smooth surface polishing.The surface roughness of Si workpiece was reduced from Rq 1.55 to Rq 0.816 nm with valleys and peaks on its surface being almost completely removed.
基金Financial supports from the National Natural Science Foundation of China(Nos.52171116,U22A20109,52334010 and T2325013)are greatly acknowledgedPartial financial support came from The Program for the Central University Youth Innovation Team,and the Fundamental Research Funds for the Central Universities,JLU.
文摘Dislocations and disclinations are fundamental topological defects within crystals,which determine the mechanical properties of metals and alloys.Despite their important roles in multiple physical mechanisms,e.g.,dynamic recovery and grain boundary mediated plasticity,the intrinsic coupling and correlation between disclinations and dislocations,and their impacts on the deformation behavior of metallic materials still remain obscure,partially due to the lack of a theoretical tool to capture the rotational nature of disclinations.By using a Lie-algebra-based theoretical framework,we obtain a general equation to quantify the intrinsic coupling of disclinations and dislocations.Through quasi in-situ electron backscatter diffraction characterizations and disclination/dislocation density analyses in Mg alloys,the generation,coevolution and reactions of disclinations and dislocations during dynamic recovery and superplastic deformation have been quantitatively analyzed.It has been demonstrated that the obtained governing equation can capture multiple physical processes associated with mechanical deformation of metals,e.g.,grain rotation and grain boundary migration,at both room temperature and high temperature.By establishing the disclination-dislocation coupling equation within a Lie algebra description,our work provides new insights for exploring the coevolution and reaction of disclinations/dislocations,with profound implications for elucidating the microstructure-property relationship and underlying deformation mechanisms in metallic materials.
基金supported by the financial aid from the National Natural Science Foundation of China (No. 22271273)International Partnership Program of Chinese Academy of Sciences (No. 121522KYSB20190022)。
文摘Self-trapping excitons(STEs) emission in metal halides has been a matter of interest, correlating with the strength of electron-phonon coupling in the lattice, which are usually caused by ions with ns~2 electronic structure. In this work, Sb^(3+)/Te^(4+)ions doped Zn-based halide single crystals(SCs) with two STEs emissions have been synthesized and the possibility of its anti-counterfeiting application was explored.Further, the relationship between the strength of electron-phonon coupling and photoluminescence quantum yields(PLQYs) for STEs in a series of metal halides has been studied. And the semi-empirical range of the Huang-Rhys factors(S) for metal halides with excellent photoluminescence(PL) property has been summarized. This work provides ideas for further research into the relationship between luminescence performance and electron-phonon coupling of metal halides, and also provides a reference for designing the metal halides with high PLQYs.
