Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)...Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.展开更多
Urea is extensively used in agriculture and chemical industry,and it is produced on an industrial scale from CO_(2)and Haber-Bosch NH_(3)under relatively high temperature and high pressure conditions,which demands hig...Urea is extensively used in agriculture and chemical industry,and it is produced on an industrial scale from CO_(2)and Haber-Bosch NH_(3)under relatively high temperature and high pressure conditions,which demands high energy input and generates masses of carbon footprint.The conversion of CO_(2)and N sources(such as NO_(2)^(−),NO_(3)^(−),and N_(2))through electrocatalytic reactions under ambient conditions is a promising alternative to realize efficient urea synthesis.Of note,the design of electrocatalyst is one of the key factors that can improve the efficiency and selectivity of C-N coupling reactions.Defect engineer-ing is an intriguing strategy for regulating the electronic structure and charge density of electrocatalysts,which endows electrocatalysts with excellent physicochemical properties and optimized adsorption en-ergy of the reaction intermediates to reduce the kinetic barriers.In this minireview,recent advances of defect engineered electrocatalysts in urea electrosynthesis from CO_(2)and various N reactants are firstly introduced.Mechanistic discussions of C-N coupling in these advances are presented,with the aim of directing future investigations on improving the urea yield.Finally,the prospects and challenges of de-fect engineered electrocatalysts for urea synthesis are discussed.This overview is expected to provide in-depth understanding of structure-reactivity relationship and shed light on future electrocatalytic C-N coupling reactions.展开更多
Electrochemical C-C and C-N coupling reactions with the conversion of abundant and inexpensive small molecules,such as CO_(2) and nitrogencontaining species,are considered a promising route for increasing the value of...Electrochemical C-C and C-N coupling reactions with the conversion of abundant and inexpensive small molecules,such as CO_(2) and nitrogencontaining species,are considered a promising route for increasing the value of CO_(2) reduction products.The development of high-performance catalysts is the key to the both electrocatalytic reactions.In this review,we present a systematic summary of the reaction systems for electrocatalytic CO_(2) reduction,along with the coupling mechanisms of C-C and C-N bonds over outstanding electrocatalytic materials recently developed.The key intermediate species and reaction pathways related to the coupling as well as the catalyst-structure relationship will be also discussed,aiming to provide insights and guidance for designing efficient CO_(2) reduction systems.展开更多
The electrocatalytic CO_(2) reduction in aqueous solution mainly involves bond cleavage and formation between C,H and O,and it is highly desirable to expand the bond formation reaction of C with other atoms to obtain ...The electrocatalytic CO_(2) reduction in aqueous solution mainly involves bond cleavage and formation between C,H and O,and it is highly desirable to expand the bond formation reaction of C with other atoms to obtain novel and valuable chemicals.The electrochemical synthesis of N-containing organic chemicals in electrocatalytic CO_(2) reduction via introducing N sources is an effective strategy to expand the product scope,since chemicals con-taining C–N bonds(e.g.amides and amines)are important reactants/products for medicine,agriculture and in-dustry.This article focuses on the research progress of C–N coupling from CO_(2) and inorganic nitrogenous species in aqueous solution.Firstly,the reaction pathways related to the reaction intermediates for urea,formamide,acetamide,methylamine and ethylamine are highlighted.Then,the electrocatalytic performance of different catalysts for these several N-containing products are summarized and classified.Finally,the challenges and op-portunities are analyzed,aiming to provide general insights into future research directions for electrocatalytic C–N coupling.展开更多
Poly(4-butyltriarylamine)s with t-butyldimethylsilyl terminal protecting group (PBTPA-TBS) with various molecular weights were prepared by C-N coupling polymerization. The resulting precursors were postfunctionalized ...Poly(4-butyltriarylamine)s with t-butyldimethylsilyl terminal protecting group (PBTPA-TBS) with various molecular weights were prepared by C-N coupling polymerization. The resulting precursors were postfunctionalized and subse- quently used as macroinitiators for atom transfer radial polymerization (ATRP) of n-butyl acrylate (n-BA) and ethyl acrylate (EA). Both the polymerization processes were controlled and the polymers were characterized by 1H NMR, gel permeation chromatography (GPC) and thermal properties, which confirmed the successful synthesis of all the poly-mers. The microphase separated behaviors of the poly (4-butyltriarylamine)-block-poly (butyl acrylate) (PBTPA-b-PBA) were examined by AFM in the film showing phase separation structures for all the polymers. The photorefractive property of the composite based on PBTPA-b-PBA block copolymer was evaluated by two-beam coupling experiment. A relative high gain coefficient of 42.7 cm?1 was obtained at the electric field of 31 V/?m.展开更多
Urea is widely used as fertilizer and is a key substance supporting global food production. However, the traditional industrial synthesis of urea faces the challenges with high energy consumption and serious environme...Urea is widely used as fertilizer and is a key substance supporting global food production. However, the traditional industrial synthesis of urea faces the challenges with high energy consumption and serious environmental problems. With the increasing global demand for environmental protection and sustainable development, it is much necessary to develop novel and clean methods for the synthesis of urea.Electrocatalysis provides an efficient and renewable synthesis route that can directly produce urea at room temperature and atmospheric pressure by the coupling of CO_(2) and nitrogenous molecules. In this review, we summarized the most recent advances in electrochemical synthesis of urea via CAN coupling systematically, focusing on the coupling of CO_(2) and different nitrogen sources. And the associated coupling mechanism, catalysts optimization, and electrolyzer design are well discussed. Moreover, the challenges and future directions for electrocatalytic CAN coupling are prospected. This review will provide timely and valuable guidance for others and attract more interests to promote the development of electrochemical synthesis of urea or other valuable chemicals containing CAN bond.展开更多
Urea,a critical nitrogen-based feedstock predominantly employed in fertilizer production,can be synthesized via electrocatalytic C-N coupling,which provides an efficient route for efficient nitrogen and carbon fixatio...Urea,a critical nitrogen-based feedstock predominantly employed in fertilizer production,can be synthesized via electrocatalytic C-N coupling,which provides an efficient route for efficient nitrogen and carbon fixation under mild conditions.Nonetheless,electrocatalytic urea synthesis is hindered by intricate intermediate pathways and competing side reactions,leading to low urea selectivity and yield.Therefore,improving the efficiency of electrocatalytic urea synthesis requires efficient catalysts.This review presents an overview of urea detection methodologies,elucidates the C-N coupling mechanisms,and explores catalyst design strategies.Accurate detection of urea detection is particularly vital in low-yield systems;thus,we analyze the advantages and limitations of several detection techniques.Additionally,we investigate the fundamental reaction mechanisms that allow reduction of CO_(2)and various nitrogen species to be reduced simultaneously.A detailed examination of catalyst design strategies aimed at improving electrocatalytic urea production,including heterostructure,atomically dispersed structures,and vacancy engineering,is provided.Finally,we address the emerging challenges that must be tackled as the technology progresses.展开更多
The conversion and utilization of carbon dioxide(CO_(2))is one of the central topics in the energy and environmental research community.The development of electrocatalytic CO_(2) reduction technology is expected to br...The conversion and utilization of carbon dioxide(CO_(2))is one of the central topics in the energy and environmental research community.The development of electrocatalytic CO_(2) reduction technology is expected to bring more economic and environmental benefits to the carbon-neutral policy.Although researchers have conducted extensive and in-depth studies on the electrocatalytic CO_(2) reduction to derive diverse carbonaceous products such as C_(1) and C_(2+),the introduction of inorganic nitrogenous molecules in the electrocatalytic CO_(2) reduction can further expand the production of more valuable C-N bondcontaining chemicals,such as amides,amines,and urea.This review focuses on the research progress in the electrochemical C-N coupling of CO_(2) with diverse nitrogenous small molecules(NH_(3),N_(2),NO,NO_(2)^(-),and NO_(3)^(-))in aqueous solution.The C-N coupling mechanisms and electrocatalytic performance of catalysts towards different products have been discussed in depth from both computational and experimental aspects.On this basis,the research directions and prospects in this field are proposed,aiming to provide valuable insights into future research on electrocatalytic C-N coupling.展开更多
Photocatalytic urea production from nitrogen(N_(2))and carbon dioxide(CO_(2))is a sustainable and ecofriendly alternative to the Bosch-Meiser route.However,it remains a significant challenge in developing highly effic...Photocatalytic urea production from nitrogen(N_(2))and carbon dioxide(CO_(2))is a sustainable and ecofriendly alternative to the Bosch-Meiser route.However,it remains a significant challenge in developing highly efficient photocatalysts for enhancing C-N coupling to high-yield urea synthesis.Herein,we propose a multi-site photocatalyst concept to address the concern of low yield by simultaneously improving photogenerated carrier separation and reactant activation.As a proof of concept,a well-defined multisite photocatalyst,Ru nanoparticles and Cu single atoms decorated CeO_(2)nanorods(Ru-Cu/CeO_(2)),is developed for efficient urea production.The incorporation of Ru and Cu sites is crucial not only to generate high-density photogenerated electrons,but also to facilitate N_(2)and CO_(2)adsorption and conversion.The in situ formed local nitrogen-rich area at Ru sites increases the encounter possibility with the carbon-containing species generated from Cu sites,substantially promoting C-N coupling.The Ru-Cu/CeO_(2)photocatalyst exhibits an impressive urea yield rate of 16.7μmol g^(-1)h^(-1),which ranks among the best performance reported to date.This work emphasizes the importance of multi-site catalyst design concept in guaranteeing rapid C-N coupling in photocatalytic urea synthesis and beyond.展开更多
The electrocatalytic synthesis of C-N coupling compounds from CO_(2) and nitrogenous species not only offers an effective avenue to achieve carbon neutral-ity and reduce environmental pollution,but also establishes a ...The electrocatalytic synthesis of C-N coupling compounds from CO_(2) and nitrogenous species not only offers an effective avenue to achieve carbon neutral-ity and reduce environmental pollution,but also establishes a route to synthesize valuable chemicals,such as urea,amide,and amine.This innovative approach expands the application range and product categories beyond simple carbona-ceous species in electrocatalytic CO_(2) reduction,which is becoming a rapidly advancing field.This review summarizes the research progress in electrocatalytic urea synthesis,using N_(2),NO_(2)^(-),and NO_(3)^(-)as nitrogenous species,and explores emerging trends in the electrosynthesis of amide and amine from CO_(2) and nitro-gen species.Additionally,the future opportunities in this field are highlighted,including electrosynthesis of amino acids and other compounds containing C-N bonds,anodic C-N coupling reactions beyond water oxidation,and the catalytic mechanism of corresponding reactions.This critical review also captures the insights aimed at accelerating the development of electrochemical C-N coupling reactions,confirming the superiority of this electrochemical method over the traditional techniques.展开更多
Dual atomic catalysts(DAC),particularly copper(Cu_(2))-based nitrogen(N)doped graphene,show great potential to effectively convert CO_(2)and nitrate(NO_(3)-)into important industrial chemicals such as ethylene,glycol,...Dual atomic catalysts(DAC),particularly copper(Cu_(2))-based nitrogen(N)doped graphene,show great potential to effectively convert CO_(2)and nitrate(NO_(3)-)into important industrial chemicals such as ethylene,glycol,acetamide,and urea through an efficient catalytical process that involves C–C and C–N coupling.However,the origin of the coupling activity remained unclear,which substantially hinders the rational design of Cu-based catalysts for the N-integrated CO_(2)reduction reaction(CO_(2)RR).To address this challenge,this work performed advanced density functional theory calculations incorporating explicit solvation based on a Cu_(2)-based N-doped carbon(Cu_(2)N_(6)C_(10))catalyst for CO_(2)RR.These calculations are aimed to gain insight into the reaction mechanisms for the synthesis of ethylene,acetamide,and urea via coupling in the interfacial reaction micro-environment.Due to the sluggishness of CO_(2),the formation of a solvation electric layer by anions(F^(-),Cl^(-),Br^(-),and I^(-))and cations(Na+,Mg^(2+),K+,and Ca^(2+))leads to electron transfer towards the Cu surface.This process significantly accelerates the reduction of CO_(2).These results reveal that*CO intermediates play a pivotal role in N-integrated CO_(2)RR.Remarkably,the Cu_(2)-based N-doped carbon catalyst examined in this study has demonstrated the most potential for C–N coupling to date.Our findings reveal that through the process of a condensation reaction between*CO and NH_(2)OH for urea synthesis,*NO_(3)-is reduced to*NH_(3),and*CO_(2)to*CCO at dual Cu atom sites.This dual-site reduction facilitates the synthesis of acetamide through a nucleophilic reaction between NH_(3)and the ketene intermediate.Furthermore,we found that the I-and Mg^(2+)ions,influenced by pH,were highly effective for acetamide and ammonia synthesis,except when F-and Ca^(2+)were present.Furthermore,the mechanisms of C–N bond formation were investigated via ab-initio molecular dynamics simulations,and we found that adjusting the micro-environment can change the dominant side reaction,shifting from hydrogen production in acidic conditions to water reduction in alkaline ones.This study introduces a novel approach using ion-H_(2)O cages to significantly enhance the efficiency of C–N coupling reactions.展开更多
Electrocatalytic C—N coupling is an environmentally friendly pathway for reducing CO_(2)emissions,nitrate wastewater treatment,and urea production.CeO_(2)is a commonly used electrocatalyst for urea synthesis,but its ...Electrocatalytic C—N coupling is an environmentally friendly pathway for reducing CO_(2)emissions,nitrate wastewater treatment,and urea production.CeO_(2)is a commonly used electrocatalyst for urea synthesis,but its yield was restricted by the deficiency of active sites and the high barrier for C—N coupling.Herein,we employed transient heating to introduce oxygen vacancies as sites for the deposition of single metal atoms,thereby maximizing the atomic utilization as active sites for urea synthesis.The as-prepared CuFe-V-CeO_(2)electrocatalyst exhibits the outstanding urea yield rate(3553 mg h^(-1)g_(ca)^(t-1).)at-1.5 V versus reversible hydrogen electrode(RHE),surpassing the performance of previously reported electrochemical urea electrocatalysts.Theoretical calculation further revealed the roles of Ce,Cu,and Fe sites in active hydrogen(*H)generation,nitrate treatment,and CO_(2)stabilization,respectively.This work offers a novel and effective pathway for the design of electrocatalysts and developing an efficient C—N coupling system for urea production.展开更多
Pyridin-2-ol-N-oxide was designed as an efficient ligand for the coupling reaction of aryl iodides,aryl bromides and aryl chlorides,respectively,with primary amines,cyclic secondary amines or N-containing heterocycles...Pyridin-2-ol-N-oxide was designed as an efficient ligand for the coupling reaction of aryl iodides,aryl bromides and aryl chlorides,respectively,with primary amines,cyclic secondary amines or N-containing heterocycles at room or moderate temperature.The catalytic system showed great functional groups tolerance and excellent selective reactivity.展开更多
A porous polymeric ligand(PPL)has been synthesized and complexed with copper to generate a heterogeneous catalyst(Cu@PPL)that has facilitated the efficient C-N coupling with various(hetero)aryl chlorides under mild co...A porous polymeric ligand(PPL)has been synthesized and complexed with copper to generate a heterogeneous catalyst(Cu@PPL)that has facilitated the efficient C-N coupling with various(hetero)aryl chlorides under mild conditions of visiblelight irradiation at 80°C(58 examples,up to 99%yields).This method could be applied to both aqueous ammonia and substituted amines,and is compatible to a variety of functional groups and heterocycles,as well as allows tandem C-N couplings with conjunctive dihalides.Furthermore,the heterogeneous characteristic of Cu@PPL has enabled a straightforward catalyst separation in multiple times of recycling with negligible catalytic efficiency loss by simple filtration,affording reaction mixtures containing less than 1 ppm of Cu residue.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
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
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
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
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
基金supported by the Research Grants Council(26206115,16304821 and 16309418)the Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(SMSEGL20SC01)+2 种基金the Innovation and Technology Commission(grant no.ITC-CNERC14EG03)of the Hong Kong Special Administrative Regionthe Hong Kong Postdoctoral Fellowship Scheme(HKUST PDFS2021-4S12 and HKUST PDFS2021-6S08)the support from the Shenzhen fundamental research funding(JCYJ20210324115809026,20200925154115001,JCYJ20200109141216566)。
文摘Urea generation through electrochemical CO_(2) and NO_(3)~-co-reduction reaction(CO_(2)NO_(3)RR)is still limited by either the low selectivity or yield rate of urea.Herein,we report copper carbonate hydroxide(Cu_2(OH)_2CO_(3))as an efficient CO_(2)NO_(3)RR electrocatalyst with an impressive urea Faradaic efficiency of45.2%±2.1%and a high yield rate of 1564.5±145.2μg h~(-1)mg_(cat)~(-1).More importantly,H_(2) evolution is fully inhibited on this electrocatalyst over a wide potential range between-0.3 and-0.8 V versus reversible hydrogen electrode.Our thermodynamic simulation reveals that the first C-N coupling follows a unique pathway on Cu_2(OH)_2CO_(3) by combining the two intermediates,~*COOH and~*NHO.This work demonstrates that high selectivity and yield rate of urea can be simultaneously achieved on simple Cu-based electrocatalysts in CO_(2)NO_(3)RR,and provide guidance for rational design of more advanced catalysts.
基金supported by the National Natural Science Foundation of China(Nos.22278094,22209029)Outstanding Youth Project of Guangdong Natural Science Foundation(No.2020B1515020028)+2 种基金Guangdong Natural Science Foundation(No.2022A1515011775)University Innovation Team Scientific Research Project of Guangzhou Education Bureau(No.202235246)China Postdoctoral Science Foundation(No.2023M730760).
文摘Urea is extensively used in agriculture and chemical industry,and it is produced on an industrial scale from CO_(2)and Haber-Bosch NH_(3)under relatively high temperature and high pressure conditions,which demands high energy input and generates masses of carbon footprint.The conversion of CO_(2)and N sources(such as NO_(2)^(−),NO_(3)^(−),and N_(2))through electrocatalytic reactions under ambient conditions is a promising alternative to realize efficient urea synthesis.Of note,the design of electrocatalyst is one of the key factors that can improve the efficiency and selectivity of C-N coupling reactions.Defect engineer-ing is an intriguing strategy for regulating the electronic structure and charge density of electrocatalysts,which endows electrocatalysts with excellent physicochemical properties and optimized adsorption en-ergy of the reaction intermediates to reduce the kinetic barriers.In this minireview,recent advances of defect engineered electrocatalysts in urea electrosynthesis from CO_(2)and various N reactants are firstly introduced.Mechanistic discussions of C-N coupling in these advances are presented,with the aim of directing future investigations on improving the urea yield.Finally,the prospects and challenges of de-fect engineered electrocatalysts for urea synthesis are discussed.This overview is expected to provide in-depth understanding of structure-reactivity relationship and shed light on future electrocatalytic C-N coupling reactions.
基金support from the Tangshan Talent Funding Project(Grant No.A202202007)National Natural Science Foundation of China(Grant Nos.22102136 and 21703065)+2 种基金Natural Science Foundation of Hebei Province(Grant Nos.B2018209267 and E2022209039)Natural Science Foundation of Hubei Province(Grant No.2022CFB1001)Department of Education of Hubei Province(Grant No.Q20221701).
文摘Electrochemical C-C and C-N coupling reactions with the conversion of abundant and inexpensive small molecules,such as CO_(2) and nitrogencontaining species,are considered a promising route for increasing the value of CO_(2) reduction products.The development of high-performance catalysts is the key to the both electrocatalytic reactions.In this review,we present a systematic summary of the reaction systems for electrocatalytic CO_(2) reduction,along with the coupling mechanisms of C-C and C-N bonds over outstanding electrocatalytic materials recently developed.The key intermediate species and reaction pathways related to the coupling as well as the catalyst-structure relationship will be also discussed,aiming to provide insights and guidance for designing efficient CO_(2) reduction systems.
基金financially supported by National Natural Science Foundation of China(22072051,22122202,21972051).
文摘The electrocatalytic CO_(2) reduction in aqueous solution mainly involves bond cleavage and formation between C,H and O,and it is highly desirable to expand the bond formation reaction of C with other atoms to obtain novel and valuable chemicals.The electrochemical synthesis of N-containing organic chemicals in electrocatalytic CO_(2) reduction via introducing N sources is an effective strategy to expand the product scope,since chemicals con-taining C–N bonds(e.g.amides and amines)are important reactants/products for medicine,agriculture and in-dustry.This article focuses on the research progress of C–N coupling from CO_(2) and inorganic nitrogenous species in aqueous solution.Firstly,the reaction pathways related to the reaction intermediates for urea,formamide,acetamide,methylamine and ethylamine are highlighted.Then,the electrocatalytic performance of different catalysts for these several N-containing products are summarized and classified.Finally,the challenges and op-portunities are analyzed,aiming to provide general insights into future research directions for electrocatalytic C–N coupling.
文摘Poly(4-butyltriarylamine)s with t-butyldimethylsilyl terminal protecting group (PBTPA-TBS) with various molecular weights were prepared by C-N coupling polymerization. The resulting precursors were postfunctionalized and subse- quently used as macroinitiators for atom transfer radial polymerization (ATRP) of n-butyl acrylate (n-BA) and ethyl acrylate (EA). Both the polymerization processes were controlled and the polymers were characterized by 1H NMR, gel permeation chromatography (GPC) and thermal properties, which confirmed the successful synthesis of all the poly-mers. The microphase separated behaviors of the poly (4-butyltriarylamine)-block-poly (butyl acrylate) (PBTPA-b-PBA) were examined by AFM in the film showing phase separation structures for all the polymers. The photorefractive property of the composite based on PBTPA-b-PBA block copolymer was evaluated by two-beam coupling experiment. A relative high gain coefficient of 42.7 cm?1 was obtained at the electric field of 31 V/?m.
基金National Natural Science Foundation of China (No. 22202065, 22075092 and U21A20500)。
文摘Urea is widely used as fertilizer and is a key substance supporting global food production. However, the traditional industrial synthesis of urea faces the challenges with high energy consumption and serious environmental problems. With the increasing global demand for environmental protection and sustainable development, it is much necessary to develop novel and clean methods for the synthesis of urea.Electrocatalysis provides an efficient and renewable synthesis route that can directly produce urea at room temperature and atmospheric pressure by the coupling of CO_(2) and nitrogenous molecules. In this review, we summarized the most recent advances in electrochemical synthesis of urea via CAN coupling systematically, focusing on the coupling of CO_(2) and different nitrogen sources. And the associated coupling mechanism, catalysts optimization, and electrolyzer design are well discussed. Moreover, the challenges and future directions for electrocatalytic CAN coupling are prospected. This review will provide timely and valuable guidance for others and attract more interests to promote the development of electrochemical synthesis of urea or other valuable chemicals containing CAN bond.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.52273058 and 52073124)the Natural Science Foundation of Jiangsu Province(No.BK2022030167)the Fundamental Research Funds for the Central Universities.
文摘Urea,a critical nitrogen-based feedstock predominantly employed in fertilizer production,can be synthesized via electrocatalytic C-N coupling,which provides an efficient route for efficient nitrogen and carbon fixation under mild conditions.Nonetheless,electrocatalytic urea synthesis is hindered by intricate intermediate pathways and competing side reactions,leading to low urea selectivity and yield.Therefore,improving the efficiency of electrocatalytic urea synthesis requires efficient catalysts.This review presents an overview of urea detection methodologies,elucidates the C-N coupling mechanisms,and explores catalyst design strategies.Accurate detection of urea detection is particularly vital in low-yield systems;thus,we analyze the advantages and limitations of several detection techniques.Additionally,we investigate the fundamental reaction mechanisms that allow reduction of CO_(2)and various nitrogen species to be reduced simultaneously.A detailed examination of catalyst design strategies aimed at improving electrocatalytic urea production,including heterostructure,atomically dispersed structures,and vacancy engineering,is provided.Finally,we address the emerging challenges that must be tackled as the technology progresses.
基金supported by the National Key Research and Development Program of China(2021YFA1500702,2022YFE0108000,2023YFA1509103)the National Natural Science Foundation of China(22425207,22321002)+1 种基金the DICP(DICP I202314,DICP I202425)support from the China Postdoctoral Science Foundation(2024M753159).
文摘The conversion and utilization of carbon dioxide(CO_(2))is one of the central topics in the energy and environmental research community.The development of electrocatalytic CO_(2) reduction technology is expected to bring more economic and environmental benefits to the carbon-neutral policy.Although researchers have conducted extensive and in-depth studies on the electrocatalytic CO_(2) reduction to derive diverse carbonaceous products such as C_(1) and C_(2+),the introduction of inorganic nitrogenous molecules in the electrocatalytic CO_(2) reduction can further expand the production of more valuable C-N bondcontaining chemicals,such as amides,amines,and urea.This review focuses on the research progress in the electrochemical C-N coupling of CO_(2) with diverse nitrogenous small molecules(NH_(3),N_(2),NO,NO_(2)^(-),and NO_(3)^(-))in aqueous solution.The C-N coupling mechanisms and electrocatalytic performance of catalysts towards different products have been discussed in depth from both computational and experimental aspects.On this basis,the research directions and prospects in this field are proposed,aiming to provide valuable insights into future research on electrocatalytic C-N coupling.
基金support by the National Natural Science Foundation of China(12222508,12475325,and 22209061)the Youth Innovation Promotion Association CAS(2020454)+2 种基金the National Key R&D Program of China(2019YFA0405601 and2023YFA1506304)the Fundamental Research Funds for the Universities of Inner Mongolia Autonomous Region(JY20250030)the Start-up Fund for Senior Talents in Jiangsu University(21JDG060)。
文摘Photocatalytic urea production from nitrogen(N_(2))and carbon dioxide(CO_(2))is a sustainable and ecofriendly alternative to the Bosch-Meiser route.However,it remains a significant challenge in developing highly efficient photocatalysts for enhancing C-N coupling to high-yield urea synthesis.Herein,we propose a multi-site photocatalyst concept to address the concern of low yield by simultaneously improving photogenerated carrier separation and reactant activation.As a proof of concept,a well-defined multisite photocatalyst,Ru nanoparticles and Cu single atoms decorated CeO_(2)nanorods(Ru-Cu/CeO_(2)),is developed for efficient urea production.The incorporation of Ru and Cu sites is crucial not only to generate high-density photogenerated electrons,but also to facilitate N_(2)and CO_(2)adsorption and conversion.The in situ formed local nitrogen-rich area at Ru sites increases the encounter possibility with the carbon-containing species generated from Cu sites,substantially promoting C-N coupling.The Ru-Cu/CeO_(2)photocatalyst exhibits an impressive urea yield rate of 16.7μmol g^(-1)h^(-1),which ranks among the best performance reported to date.This work emphasizes the importance of multi-site catalyst design concept in guaranteeing rapid C-N coupling in photocatalytic urea synthesis and beyond.
基金National Natural Science Foundation of China,Grant/Award Numbers:42277485,21976141,22272197,22102184,22102136,U22A20392Natural Science Foundation of Hubei Province,Grant/Award Numbers:2022CFB1001,2021CFA034+1 种基金Department of Education of Hubei Province,Grant/Award Numbers:Q20221701,Q20221704Joint Fund of Yulin University and Dalian National Laboratory for Clean Energy,Grant/Award Number:YLU-DNL Fund 2022008。
文摘The electrocatalytic synthesis of C-N coupling compounds from CO_(2) and nitrogenous species not only offers an effective avenue to achieve carbon neutral-ity and reduce environmental pollution,but also establishes a route to synthesize valuable chemicals,such as urea,amide,and amine.This innovative approach expands the application range and product categories beyond simple carbona-ceous species in electrocatalytic CO_(2) reduction,which is becoming a rapidly advancing field.This review summarizes the research progress in electrocatalytic urea synthesis,using N_(2),NO_(2)^(-),and NO_(3)^(-)as nitrogenous species,and explores emerging trends in the electrosynthesis of amide and amine from CO_(2) and nitro-gen species.Additionally,the future opportunities in this field are highlighted,including electrosynthesis of amino acids and other compounds containing C-N bonds,anodic C-N coupling reactions beyond water oxidation,and the catalytic mechanism of corresponding reactions.This critical review also captures the insights aimed at accelerating the development of electrochemical C-N coupling reactions,confirming the superiority of this electrochemical method over the traditional techniques.
基金National Natural Science Foundation of China(U22B20149,22308376)Outstanding Young Scholars Foundation of China University of Petroleum(Beijing)(2462023BJRC015)Foundation of United Institute for Carbon Neutrality(CNIF20230209)。
文摘Dual atomic catalysts(DAC),particularly copper(Cu_(2))-based nitrogen(N)doped graphene,show great potential to effectively convert CO_(2)and nitrate(NO_(3)-)into important industrial chemicals such as ethylene,glycol,acetamide,and urea through an efficient catalytical process that involves C–C and C–N coupling.However,the origin of the coupling activity remained unclear,which substantially hinders the rational design of Cu-based catalysts for the N-integrated CO_(2)reduction reaction(CO_(2)RR).To address this challenge,this work performed advanced density functional theory calculations incorporating explicit solvation based on a Cu_(2)-based N-doped carbon(Cu_(2)N_(6)C_(10))catalyst for CO_(2)RR.These calculations are aimed to gain insight into the reaction mechanisms for the synthesis of ethylene,acetamide,and urea via coupling in the interfacial reaction micro-environment.Due to the sluggishness of CO_(2),the formation of a solvation electric layer by anions(F^(-),Cl^(-),Br^(-),and I^(-))and cations(Na+,Mg^(2+),K+,and Ca^(2+))leads to electron transfer towards the Cu surface.This process significantly accelerates the reduction of CO_(2).These results reveal that*CO intermediates play a pivotal role in N-integrated CO_(2)RR.Remarkably,the Cu_(2)-based N-doped carbon catalyst examined in this study has demonstrated the most potential for C–N coupling to date.Our findings reveal that through the process of a condensation reaction between*CO and NH_(2)OH for urea synthesis,*NO_(3)-is reduced to*NH_(3),and*CO_(2)to*CCO at dual Cu atom sites.This dual-site reduction facilitates the synthesis of acetamide through a nucleophilic reaction between NH_(3)and the ketene intermediate.Furthermore,we found that the I-and Mg^(2+)ions,influenced by pH,were highly effective for acetamide and ammonia synthesis,except when F-and Ca^(2+)were present.Furthermore,the mechanisms of C–N bond formation were investigated via ab-initio molecular dynamics simulations,and we found that adjusting the micro-environment can change the dominant side reaction,shifting from hydrogen production in acidic conditions to water reduction in alkaline ones.This study introduces a novel approach using ion-H_(2)O cages to significantly enhance the efficiency of C–N coupling reactions.
基金supported by the Hebei Natural Science Foundation(B2024205035)supported by the Fundamental Research Funds for the Central Universities+5 种基金the World-Class Universities(Disciplines)the Characteristic Development Guidance Funds for the Central Universities(1061-B23017010264)supported by the Fundamental Research Funds for the Natural Science Foundation of China(92047201,52102237)the Natural Science Foundation of Jiangsu Province(BK20220006)the National Major Projects of Water Pollution Control and Management Technology(2017ZX07204003)the Postdoctoral Science Foundations of China and Jiangsu Province(2021M690861,2022T150183,2021K065A)。
文摘Electrocatalytic C—N coupling is an environmentally friendly pathway for reducing CO_(2)emissions,nitrate wastewater treatment,and urea production.CeO_(2)is a commonly used electrocatalyst for urea synthesis,but its yield was restricted by the deficiency of active sites and the high barrier for C—N coupling.Herein,we employed transient heating to introduce oxygen vacancies as sites for the deposition of single metal atoms,thereby maximizing the atomic utilization as active sites for urea synthesis.The as-prepared CuFe-V-CeO_(2)electrocatalyst exhibits the outstanding urea yield rate(3553 mg h^(-1)g_(ca)^(t-1).)at-1.5 V versus reversible hydrogen electrode(RHE),surpassing the performance of previously reported electrochemical urea electrocatalysts.Theoretical calculation further revealed the roles of Ce,Cu,and Fe sites in active hydrogen(*H)generation,nitrate treatment,and CO_(2)stabilization,respectively.This work offers a novel and effective pathway for the design of electrocatalysts and developing an efficient C—N coupling system for urea production.
基金We gratefully acknowledge the National Natural Science Foundation(Nos.81172934,30973607,20972160 and 21172220)the National Basic Research Program of China(No.2009CB940900)the Special Foundation of President,and the Strategic Leading Science&Technology Programme of the Chinese Academy of Sciences for their financial support.
文摘Pyridin-2-ol-N-oxide was designed as an efficient ligand for the coupling reaction of aryl iodides,aryl bromides and aryl chlorides,respectively,with primary amines,cyclic secondary amines or N-containing heterocycles at room or moderate temperature.The catalytic system showed great functional groups tolerance and excellent selective reactivity.
基金the National Natural Science Foundation of China(21704016,21971044)。
文摘A porous polymeric ligand(PPL)has been synthesized and complexed with copper to generate a heterogeneous catalyst(Cu@PPL)that has facilitated the efficient C-N coupling with various(hetero)aryl chlorides under mild conditions of visiblelight irradiation at 80°C(58 examples,up to 99%yields).This method could be applied to both aqueous ammonia and substituted amines,and is compatible to a variety of functional groups and heterocycles,as well as allows tandem C-N couplings with conjunctive dihalides.Furthermore,the heterogeneous characteristic of Cu@PPL has enabled a straightforward catalyst separation in multiple times of recycling with negligible catalytic efficiency loss by simple filtration,affording reaction mixtures containing less than 1 ppm of Cu residue.
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 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.
