Anammox was successfully transited from heterotrophic denitrification and autotrophic denitrification in two upflow biofilm reactors, respectively. The results showed that the volumetric loading rate and nitrogen remo...Anammox was successfully transited from heterotrophic denitrification and autotrophic denitrification in two upflow biofilm reactors, respectively. The results showed that the volumetric loading rate and nitrogen removal efficiency in the reactor transited from heterotrophic denitrification were higher than that in its counterpart. When the hydraulic retention time was 12 h or so, the total nitrogen loading rate was about 0.609 kg N/(m3·d), and the effluent ammonia and nitrite concentrations were less than 8.5 mg/L and 2.5 mg/L, respectively. The upflow anammox biofilm reactor was capable of keeping and accumulating the slow-growing bacteria efficiently. During operation of the reactor, the biomass color was gradually turned from brownish to red, and the ratio of ammonia consumption, nitrite consumption and nitrate production approached the theoretical one. These changes could be used as an indicator for working state of the reactor.展开更多
Temperature-programmed desorption(TPD)is a fundamental technique in surface science and heterogeneous catalysis for characterizing adsorption behavior,and for extracting key parameters such as adsorption energy.Howeve...Temperature-programmed desorption(TPD)is a fundamental technique in surface science and heterogeneous catalysis for characterizing adsorption behavior,and for extracting key parameters such as adsorption energy.However,the majority of existing TPD data is accessible in the form of published images,which lacks structured and quantitative datasets.This constrains its utility for rigorous quantitative analysis and computational modelling.Using carbon monoxide(CO)which is a widely adopted probe molecule,a curated and standardized dataset of CO-TPD is constructed,encompassing 14 transition-metal single-crystal surfaces,including copper(Cu)and ruthenium(Ru).By systematically extracting numerical data points from published spectra and applying normalization,essential spectral features such as peak shape are fully preserved.The dataset also documents relevant experimental parameters,including heating rates,and was developed using a standardized protocol for data collection and quality control.This resource serves as both a reference library to support the deconvolution of TPD spectra from complex catalysts and an experimental benchmark for calibrating parameters in theoretical models.By providing a reliable and accessible data function,this work advances the microscopic understanding and the rational design of catalyst active centers.展开更多
Electrochemical water splitting represents a sustainable technology for hydrogen(H_(2))production.However,its large-scale implementation is hindered by the high overpotentials required for both the cathodic hydrogen e...Electrochemical water splitting represents a sustainable technology for hydrogen(H_(2))production.However,its large-scale implementation is hindered by the high overpotentials required for both the cathodic hydrogen evolution reaction(HER)and the anodic oxygen evolution reaction(OER).Transition metal-based catalysts have garnered significant research interest as promising alternatives to noble-metal catalysts,owing to their low cost,tunable composition,and noble-metal-like catalytic activity.Nevertheless,systematic reviews on their application as bifunctional catalysts for overall water splitting(OWS)are still limited.This review comprehensively outlines the principal categories of bifunctional transition metal electrocatalysts derived from electrospun nanofibers(NFs),including metals,oxides,phosphides,sulfides,and carbides.Key strategies for enhancing their catalytic performance are systematically summarized,such as heterointerface engineering,heteroatom doping,metal-nonmetal-metal bridging architectures,and single-atom site design.Finally,current challenges and future research directions are discussed,aiming to provide insightful perspectives for the rational design of high-performance electrocatalysts for OWS.展开更多
Let T_(n) and S_(n) be the full transformation semigroup and the symmetric group on X_(n)={1,2,...,n},respectively.Let G be a transitiveimprimitive subgroupof S_(n) with nontrivial blocksΔand letαbe a transformation...Let T_(n) and S_(n) be the full transformation semigroup and the symmetric group on X_(n)={1,2,...,n},respectively.Let G be a transitiveimprimitive subgroupof S_(n) with nontrivial blocksΔand letαbe a transformation in T_(n)\S_(n).The kernel ofαis the partition of X_(n) induced by the equivalence relation{(x,y)|xα=yα};the kernel type ofαis the partition of n given by the sizes of the parts of the kernel.A transformation semigroup is called synchronizing if it contains a constant map.Then a group G synchronizes a transformationαif the semigroup(G,α)contains a constant map.In this paper,we study a transitive imprimitive permutation group G together with a non-invertible transformationαthat generate a synchronizing semigroup.We mainly discuss 7 cases where G synchronizes a special transformationαwith each kernel class A_(i)(A_(1)j)satisfying|A_(i)∩Δ|=1(|A_(1)j∩Δ|=1)for all blocksΔofG,that is,the kernel type ofαis(|A_(1)|,1,...,1),(|A_(1)1|,...,|A_(1m)|,|A_(2)|,...,|Ar|),or(|A_(1)|,...,|A_(t)|,1,...,1),or the rank is 2,3,4,or n-2.展开更多
Herein,manganese(Mn)‑doped poly(1,5‑diaminonaphthalene)(PN)electrode material(Mn@PN)was synthesized via chemical oxidative polymerization.The material′s distinctive vesicular architecture enables rapid ion transport ...Herein,manganese(Mn)‑doped poly(1,5‑diaminonaphthalene)(PN)electrode material(Mn@PN)was synthesized via chemical oxidative polymerization.The material′s distinctive vesicular architecture enables rapid ion transport while maintaining the structural stability of the electrode under continuous charge‑discharge cycles.Electrochemical characterization under a three‑electrode system revealed exceptional rate capability:Mn@PN delivered an ultrahigh specific capacitance of 10318 F·g^(-1) at a low current density of 3 A·g^(-1) and retained 9415 F·g^(-1)(91.2%retention compared to the value at 3 A·g^(-1))even at an ultrahigh current density of 50 A·g^(-1).Moreover,the material exhibited 97.4%capacitance retention after 9000 cycles at 30 A·g^(-1),corresponding with a low capacitance decay rate of 0.003‰per cycle,significantly outperforming conventional conductive polymers like polyaniline(PANI).An asymmetric supercapacitor assembled with Mn@PN as the positive electrode(Mn@PN||AC)achieved an energy density of 328 Wh·kg^(-1) at 15 A·g^(-1) and retained 80.7%of its initial specific capacitance after 4000 cycles at 20 A·g^(-1).展开更多
Transition metal-catalyzed C—C coupling reactions are a core strategy for the construction of carbon-carbon bonds in organic synthesis.Their development has not only promoted the synthesis of drugs,materials,and natu...Transition metal-catalyzed C—C coupling reactions are a core strategy for the construction of carbon-carbon bonds in organic synthesis.Their development has not only promoted the synthesis of drugs,materials,and natural products,but also promoted the development of new synthetic methods,and has also made breakthroughs in mechanism innovation and catalyst design.On this basis,a copper-catalyzed radical reaction between ketones is reported,enabling the synthesis of 2-carbonyl-1,4-diones.The method exhibits excellent applicability to multiple structural types of ketones,including aliphatic ketones with diverse substituents,aromatic ketones,and various simple ketones not limited to acetone,with wide applications,easy implementation,low catalyst toxicity,and low cost,cost-effective,and the product is easy to separate and purify.展开更多
This study systematically investigates the cyclization reaction mechanisms between n-C_(4)H_(3)(1-buten-3-yn-1-yl)and i-C_(4)H_(3)(2-buten-3-yn-1-yl)radicals with acetylene(C_(2)H_(2))using density functional theory(D...This study systematically investigates the cyclization reaction mechanisms between n-C_(4)H_(3)(1-buten-3-yn-1-yl)and i-C_(4)H_(3)(2-buten-3-yn-1-yl)radicals with acetylene(C_(2)H_(2))using density functional theory(DFT)and transition state theory(TST).The results reveal that the reaction of n-C_(4)H_(3)with acetylene proceeds via a radical chain mechanism through an additioncyclization pathway,yielding phenyl(sixmembered ring),fulvenyl(five-membered ring),and four-membered ring intermediates.The product formation rates follow the order:fulvenyl(five-membered ring)>phenyl(six-membered ring)>four-membered ring.For i-C_(4)H_(3),the intermediate structures depend on the carbon position of i-C_(4)H_(3)where acetylene addition occurs:addition at the C2 position predominantly generates fulvenyl(five-membered ring)as the primary product,whereas addition at the C4 position may lead to phenyl(six-membered ring),fulvenyl(five-membered ring),or four-membered ring intermediates,with the four-membered ring forming most rapidly and the six-membered ring the slowest.Theoretical analyses demonstrate that the selectivity of reaction pathways is primarily governed by structural differences between the isomers.This work provides atomic-scale insights into the cyclization processes between acetylene and C_(4)H_(3)species,establishing a foundation for refining models of soot precursor formation.展开更多
The post-embryonic development of shoot apices in higher plants progresses through three distinct phases:the juvenile phase,adult vegetative phase,and reproductive phase.The transition from vegetative to reproductive ...The post-embryonic development of shoot apices in higher plants progresses through three distinct phases:the juvenile phase,adult vegetative phase,and reproductive phase.The transition from vegetative to reproductive growth represents a critical developmental transition that affects plant adaptability(Poethig 2003;Baurle and Dean 2006).展开更多
Polyamorphous transition refers to the transformation between two distinct amorphous states with identical composition.This phenomenon is intriguing in the field of physics and offers avenues for glass material design...Polyamorphous transition refers to the transformation between two distinct amorphous states with identical composition.This phenomenon is intriguing in the field of physics and offers avenues for glass material design.Recently,polyamorphous transitions have been frequently observed in glassy materials.However,the transition pathway has yet to be established,which is essential for understanding its structural origins.Here,we present evidence from 12 different types of metallic glasses spanning 7 orders of magnitude in timescales,demonstrating that polyamorphous transitions consistently occur after the devitrification process,between two supercooled liquid phases(Ⅰ and Ⅱ).Notably,we observe a decrease in liquid fragility and heat capacity following the transition,suggesting that the polyamorphous transition is associated with the fragile-to-strong transition(FST)in liquids.These findings elucidate the detailed structural pathway of the polyamorphous transition,via glass I→devitrification→liquid I→fragile-strong transition→liquid II,and incorporate the FST into a cohesive framework for its understanding.展开更多
Separation bubbles forming on airfoils significantly influence aerodynamic behavior,particularly at low Reynolds numbers,making their accurate prediction a critical challenge in transition modelling.This study investi...Separation bubbles forming on airfoils significantly influence aerodynamic behavior,particularly at low Reynolds numbers,making their accurate prediction a critical challenge in transition modelling.This study investigates numerical modeling of a separation bubble and the effects of airfoil thickness and camber variation on the formation of the bubble dynamics at low Reynolds numbers.The numerical results were compared with the experimental results obtained from surface pressure distribution measurements,oil flow visualisation,and surface shear measurements to analyse the detailed flow behavior.The combination of pressure and flow visualisation techniques provided complementary insights,enabling a detailed characterisation of bubble formation.The results reveal that both the thickness and camber of the airfoil significantly influence the location,length,and stability of the bubble.At low Reynolds number flows(Re=0.5×10^(5)),particularly for highly cambered profiles,closer to the leading edge,separation and long bubbles were observed.As the Reynolds number increased,the separation point shifted to the leading edge,and reattachment became more likely.In numerical studies,transition models can accurately model the bubble initiation point;however,they often fail to model the bubble reattachment points accurately.This is due to the inadequacy of models that use empirical expressions for turbulence modelling,particularly in low Reynolds number flows,in their viscous modelling.In this study,it was concluded that transition onset terms,which specifically affect bubble formation,should be modified for more accurate modeling.展开更多
Based on datasets from the International Best-Track Archive for Climate Stewardship(IBTrACS)and the fifth major global reanalysis produced by ECMWF(ERA5),the authors found that 29%of tropical cyclones(TCs)in the weste...Based on datasets from the International Best-Track Archive for Climate Stewardship(IBTrACS)and the fifth major global reanalysis produced by ECMWF(ERA5),the authors found that 29%of tropical cyclones(TCs)in the western North Pacific underwent extratropical transition(ET)from 1979 to 2022,with the frequency of ET events showing a slow decreasing trend.The extratropical transition tropical cyclones(ETCs)are classified into four clusters using the k-means clustering method based on their track patterns:recurving ETCs,westward ETCs,northwestward ETCs,and abnormal track ETCs.The transition process of recurving ETCs mostly occurs after the recurvature is completed,while 63.7%of the westward ETCs complete their transition after landfall.Abnormal track ETCs undergo transition over high-latitude oceans.Northwestward ETCs have the longest duration and slowest transition speed during the ET period,resulting in a prolonged impact.The ET process occurs at the edges of the western Pacific subtropical high(WPSH),with higher frequency during westward extension and lower during eastward retreat.While westward ETCs transition through surface friction effects,others complete ET in the northwest baroclinic zone of the WPSH.展开更多
Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties.However,controlling pha...Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties.However,controlling phase transitions to form diverse heterostructures inside a single crystal remains challenging.In this study,we realize vertical/lateral polytype heterostructures in a hole-doped Mott insulator via thermal annealing-induced structural transitions.Raman spectroscopy,atomic force microscopy and scanning Kelvin probe force microscopy confirm the coexistence of T-H polytype heterostructures.Atomic-scale scanning tunneling microscopy/spectroscopy measurements reveal the transparent effect in 1H/1T vertical heterostructures,where positive bias voltage induces in a pronounced superposition of the√13×√13 CDW of the 1T-layer on the 1H-layer.By systematically comparing the 1T/1H and 1T/1T interfaces,we demonstrate that the metallic 1H-layer induces a Coulomb screening effect on the 1T-layer,suppressing the formation of CDW domain walls and forming more ordered electronic states.These results clarify the interfacial coupling between distinct quantum many-body phases and establish a controllable pathway for constructing two-dimensional polytype heterostructures with tunable electronic properties.展开更多
The complex aerodynamic interaction between tandem tilt-wing and multi-rotor directly affects the wing surface flow and rotor thrust,making it a critical factor during the tilt transition process of this configuration...The complex aerodynamic interaction between tandem tilt-wing and multi-rotor directly affects the wing surface flow and rotor thrust,making it a critical factor during the tilt transition process of this configuration of rotorcraft.The aerodynamic interaction of tandem tilt-wing and multi-rotor is investigated based on the CFD method.The aerodynamic effect of multi tilt-rotor is simulated as virtual disk modeling by adding source terms to the Navier-Stokes equations,effectively reducing the calculation time while maintaining the accuracy of aerodynamic interaction calculations.Aerodynamic forces and flow field characteristics of the tandem tilt-wing and multi-rotor under different tilt angles are compared between cases with and without aerodynamic interaction.Furthermore,the differences in aerodynamic forces between dynamic tilt transition and fixed-angle conditions were compared.The results show that the aerodynamic interaction of multi-rotor obviously increases the lift of front tilt-wing at different tilt angles,the wing lift under interaction is increased by more than 40%compared with isolated wing at tilt angle of 15°for the computation in this paper,which is related to the increase of wing flow velocity and the suppression of flow separation caused by multi-rotor;the wing blocking effect will increase rotor thrust,especially near the tilt angles of 30°and 45°;the increases of rear wing lift and rear rotor thrust under aerodynamic interaction are not significant because of suppression by the front wing’s downwash;the unsteady effects during dynamic tilting have a relatively minor impact on aerodynamic interaction,with the aerodynamic forces on the rotors and wings during the dynamic tilting process showing little difference from those under corresponding fixed tilt angles.展开更多
Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face wit...Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed C–H activation has been employed for the functionalization of amino acids and peptides.Through domino C–H activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed C–H activation/annulation.展开更多
A novel method for the synthesis of 2,4-disubstituted thiophenes via the reactions of N,N-disubstituted enaminones and elemental sulfur is developed.By simply heating the substrates in pure water in the presence of Na...A novel method for the synthesis of 2,4-disubstituted thiophenes via the reactions of N,N-disubstituted enaminones and elemental sulfur is developed.By simply heating the substrates in pure water in the presence of NaOH,the thiophene annulation practically takes place via the generation of one C-C and two C-S bonds via cascade dual C-H functionalization and C-N bond thiolation without using any transition metal reagent.展开更多
Discussions about the future of energy sources and environmental sustainability are becoming critical on a global scale.The energy sector plays a central role in the economy,as the availability and cost of energy infl...Discussions about the future of energy sources and environmental sustainability are becoming critical on a global scale.The energy sector plays a central role in the economy,as the availability and cost of energy influence the competitiveness of economies,while the level of energy consumption impacts the standard of living for individuals.This paper aims to examine environmental challenges and steps for a sustainable transition towards a hydrogen economy,focusing on its potential as an alternative to fossil fuels and the importance of developing the hydrogen paradigm.The research methodology is based on a combination of qualitative and quantitative methods,including an analysis of global and regional trends in the energy transition,the impact of various forms of hydrogen production(green,blue,gray hydrogen)on greenhouse gas emissions,and a comparison of existing policies and strategies in different countries transitioning to a sustainable hydrogen economy.Research results show that green hydrogen,produced via electrolysis using renewable energy sources,holds the greatest potential for reducing greenhouse gas emissions,while gray and blue hydrogen can serve as transitional options.The development of the hydrogen paradigm,rooted in innovative technologies,renewable energy sources,and international cooperation,is crucial for decarbonization and the creation of a sustainable global economy,despite challenges such as high costs and the need for global coordination.The hydrogen paradigm is becoming a cornerstone of these efforts,laying the foundation for a long-term,sustainable global economy.Currently,over 180 hydrogen transport projects,60 distribution projects,80 storage projects,30 terminal and port projects,and more than 220 hydrogen production projects are under development worldwide.The global momentum of the hydrogen transition helps mitigate climate change and build a sustainable future.展开更多
To realize the practical application of anion exchange membrane water electrolysis(AEMWE),it is essential to develop highly active,durable,and cost-effective electrocatalyst for oxygen evolution reaction(OER).Herein,w...To realize the practical application of anion exchange membrane water electrolysis(AEMWE),it is essential to develop highly active,durable,and cost-effective electrocatalyst for oxygen evolution reaction(OER).Herein,we report a hollow-structured Ni_(x)Co_(1−x)O/Ni_(3)S_(2)/Co_(9)S_(8)heterostructure synthesized via sequential template-assisted growth,thermal oxidation,and controlled sulfidation process.The abundant bimetallic heterointerfaces not only provide additional active sites but also promote electronic modulation via charge redistribution.Additionally,the porous and hollow architecture enhances active surface area and mass transfer ability,thereby increasing the number of accessible active sites for alkaline OER.As a result,the prepared electrocatalyst achieves low overpotential of 310 mV at 10 mA cm^(−2)and small Tafel slope of 55.94 mV dec^(−1),demonstrating the exceptional electrocatalytic performance for alkaline OER.When integrated as the anode in an AEMWE cell,it delivers outstanding performance with only 1.657 V at 1.0 A cm^(−2)and reaches high current density of 5.0 A cm^(−2)at 1.989 V,surpassing those of commercial RuO_(2).The cell also shows excellent long-term durability over 100 h with minimal degradation.This study highlights the strong potential of rationally engineered oxide/sulfide heterostructures for next-generation alkaline water electrolysis.展开更多
The Smiles rearrangement is an exceptionally versatile method in organic synthesis,providing a broad canvas for designing cascade reactions that construct new Csp^(2)-Y(Y=C,O,N,S,CO,etc.)bonds.Among the various types ...The Smiles rearrangement is an exceptionally versatile method in organic synthesis,providing a broad canvas for designing cascade reactions that construct new Csp^(2)-Y(Y=C,O,N,S,CO,etc.)bonds.Among the various types of Smiles rearrangement,the radical-type variant has emerged as a more powerful,mild,efficient,and modern synthetic technique compared to its traditional ionic counterpart.This approach excels in generating new(hetero)aromatic migration products,enabling significant advancements in recent years.This tutorial review focuses on the recent progress,since 2016,in the development and application of radical Smiles rearrangement in organic chemistry.Special attention is paid to novel transformations achieved through photochemical,electrochemical,and transition metal catalysis methods.展开更多
We synthesized Ru_(1)Cu_(25)P_(7.5)/TiO_(2)catalyst using sodium borohydride(NaBH_(4))as reductant in a facile strategy.The highly dispersed RuCuP nanoclusters are anchored on the TiO_(2)surface with an average partic...We synthesized Ru_(1)Cu_(25)P_(7.5)/TiO_(2)catalyst using sodium borohydride(NaBH_(4))as reductant in a facile strategy.The highly dispersed RuCuP nanoclusters are anchored on the TiO_(2)surface with an average particle size of 2.62 nm.The catalyst shows excellent catalytic activity when applied to the hydrolysis of AB,which owns a high turnover frequency value of 531.56 mol_(H2)mol_(Ru)^(-1)min^(-1)and a low activation energy of 46.38 kJ·mol^(-1),it also exhibits good durability which maintains 61.13%initial activity after five cycles.The high catalytic performance of Ru_(1)Cu_(25)P_(7.5)/TiO_(2)may be attributed to the synergistic effects between Ru,Cu,and P elements,fine particle size,good dispersion,and the tight adhesion between nanoclusters and carrier.展开更多
基金TheNationalNaturalScienceFoundationofChina (No . 30 0 70 0 1 7) theScienceandTechnologyFoundationforKeyProjectofZhejiang
文摘Anammox was successfully transited from heterotrophic denitrification and autotrophic denitrification in two upflow biofilm reactors, respectively. The results showed that the volumetric loading rate and nitrogen removal efficiency in the reactor transited from heterotrophic denitrification were higher than that in its counterpart. When the hydraulic retention time was 12 h or so, the total nitrogen loading rate was about 0.609 kg N/(m3·d), and the effluent ammonia and nitrite concentrations were less than 8.5 mg/L and 2.5 mg/L, respectively. The upflow anammox biofilm reactor was capable of keeping and accumulating the slow-growing bacteria efficiently. During operation of the reactor, the biomass color was gradually turned from brownish to red, and the ratio of ammonia consumption, nitrite consumption and nitrate production approached the theoretical one. These changes could be used as an indicator for working state of the reactor.
基金Supported by the Robotic AI-Scientist Platform of Chinese Academy of SciencesNational Natural Science Foundation of China(22372185)+2 种基金Youth Talent Development Program of SKLCC(2025BWZ009)Natural Science Foundation of Shanxi Province(202203021221219)Research on the Construction of Scientific and Technological Innovation Think Tank of Shanxi Association for Science and Technology(KXKT202542)。
文摘Temperature-programmed desorption(TPD)is a fundamental technique in surface science and heterogeneous catalysis for characterizing adsorption behavior,and for extracting key parameters such as adsorption energy.However,the majority of existing TPD data is accessible in the form of published images,which lacks structured and quantitative datasets.This constrains its utility for rigorous quantitative analysis and computational modelling.Using carbon monoxide(CO)which is a widely adopted probe molecule,a curated and standardized dataset of CO-TPD is constructed,encompassing 14 transition-metal single-crystal surfaces,including copper(Cu)and ruthenium(Ru).By systematically extracting numerical data points from published spectra and applying normalization,essential spectral features such as peak shape are fully preserved.The dataset also documents relevant experimental parameters,including heating rates,and was developed using a standardized protocol for data collection and quality control.This resource serves as both a reference library to support the deconvolution of TPD spectra from complex catalysts and an experimental benchmark for calibrating parameters in theoretical models.By providing a reliable and accessible data function,this work advances the microscopic understanding and the rational design of catalyst active centers.
基金Supported by the National Natural Science Foundation of China(No.52273056)the Science and Technology Development Program of Jilin Province,China(No.YDZJ202501ZYTS305)。
文摘Electrochemical water splitting represents a sustainable technology for hydrogen(H_(2))production.However,its large-scale implementation is hindered by the high overpotentials required for both the cathodic hydrogen evolution reaction(HER)and the anodic oxygen evolution reaction(OER).Transition metal-based catalysts have garnered significant research interest as promising alternatives to noble-metal catalysts,owing to their low cost,tunable composition,and noble-metal-like catalytic activity.Nevertheless,systematic reviews on their application as bifunctional catalysts for overall water splitting(OWS)are still limited.This review comprehensively outlines the principal categories of bifunctional transition metal electrocatalysts derived from electrospun nanofibers(NFs),including metals,oxides,phosphides,sulfides,and carbides.Key strategies for enhancing their catalytic performance are systematically summarized,such as heterointerface engineering,heteroatom doping,metal-nonmetal-metal bridging architectures,and single-atom site design.Finally,current challenges and future research directions are discussed,aiming to provide insightful perspectives for the rational design of high-performance electrocatalysts for OWS.
基金Supported by NSFC (No.12401024)the Scientific Research Innovation Project of Lingnan Normal University (Nos.LT2401,LT2410)。
文摘Let T_(n) and S_(n) be the full transformation semigroup and the symmetric group on X_(n)={1,2,...,n},respectively.Let G be a transitiveimprimitive subgroupof S_(n) with nontrivial blocksΔand letαbe a transformation in T_(n)\S_(n).The kernel ofαis the partition of X_(n) induced by the equivalence relation{(x,y)|xα=yα};the kernel type ofαis the partition of n given by the sizes of the parts of the kernel.A transformation semigroup is called synchronizing if it contains a constant map.Then a group G synchronizes a transformationαif the semigroup(G,α)contains a constant map.In this paper,we study a transitive imprimitive permutation group G together with a non-invertible transformationαthat generate a synchronizing semigroup.We mainly discuss 7 cases where G synchronizes a special transformationαwith each kernel class A_(i)(A_(1)j)satisfying|A_(i)∩Δ|=1(|A_(1)j∩Δ|=1)for all blocksΔofG,that is,the kernel type ofαis(|A_(1)|,1,...,1),(|A_(1)1|,...,|A_(1m)|,|A_(2)|,...,|Ar|),or(|A_(1)|,...,|A_(t)|,1,...,1),or the rank is 2,3,4,or n-2.
文摘Herein,manganese(Mn)‑doped poly(1,5‑diaminonaphthalene)(PN)electrode material(Mn@PN)was synthesized via chemical oxidative polymerization.The material′s distinctive vesicular architecture enables rapid ion transport while maintaining the structural stability of the electrode under continuous charge‑discharge cycles.Electrochemical characterization under a three‑electrode system revealed exceptional rate capability:Mn@PN delivered an ultrahigh specific capacitance of 10318 F·g^(-1) at a low current density of 3 A·g^(-1) and retained 9415 F·g^(-1)(91.2%retention compared to the value at 3 A·g^(-1))even at an ultrahigh current density of 50 A·g^(-1).Moreover,the material exhibited 97.4%capacitance retention after 9000 cycles at 30 A·g^(-1),corresponding with a low capacitance decay rate of 0.003‰per cycle,significantly outperforming conventional conductive polymers like polyaniline(PANI).An asymmetric supercapacitor assembled with Mn@PN as the positive electrode(Mn@PN||AC)achieved an energy density of 328 Wh·kg^(-1) at 15 A·g^(-1) and retained 80.7%of its initial specific capacitance after 4000 cycles at 20 A·g^(-1).
基金Project supported by the Basic Research Support Program for Outstanding Young Teachers in Provincial Undergraduate Colleges and Universities in Heilongjiang Province(No.YQJH2024096)the Heilongjiang Province Natural Joint Guidance Cultivation Project(No.PL2024H198)。
文摘Transition metal-catalyzed C—C coupling reactions are a core strategy for the construction of carbon-carbon bonds in organic synthesis.Their development has not only promoted the synthesis of drugs,materials,and natural products,but also promoted the development of new synthetic methods,and has also made breakthroughs in mechanism innovation and catalyst design.On this basis,a copper-catalyzed radical reaction between ketones is reported,enabling the synthesis of 2-carbonyl-1,4-diones.The method exhibits excellent applicability to multiple structural types of ketones,including aliphatic ketones with diverse substituents,aromatic ketones,and various simple ketones not limited to acetone,with wide applications,easy implementation,low catalyst toxicity,and low cost,cost-effective,and the product is easy to separate and purify.
基金Supported by the National Key Research and Development Program of China(2022YFB4301400)the Basic Science(Natural Science)Research Project for Higher Education Institutions in Jiangsu Province(24KJD580001)。
文摘This study systematically investigates the cyclization reaction mechanisms between n-C_(4)H_(3)(1-buten-3-yn-1-yl)and i-C_(4)H_(3)(2-buten-3-yn-1-yl)radicals with acetylene(C_(2)H_(2))using density functional theory(DFT)and transition state theory(TST).The results reveal that the reaction of n-C_(4)H_(3)with acetylene proceeds via a radical chain mechanism through an additioncyclization pathway,yielding phenyl(sixmembered ring),fulvenyl(five-membered ring),and four-membered ring intermediates.The product formation rates follow the order:fulvenyl(five-membered ring)>phenyl(six-membered ring)>four-membered ring.For i-C_(4)H_(3),the intermediate structures depend on the carbon position of i-C_(4)H_(3)where acetylene addition occurs:addition at the C2 position predominantly generates fulvenyl(five-membered ring)as the primary product,whereas addition at the C4 position may lead to phenyl(six-membered ring),fulvenyl(five-membered ring),or four-membered ring intermediates,with the four-membered ring forming most rapidly and the six-membered ring the slowest.Theoretical analyses demonstrate that the selectivity of reaction pathways is primarily governed by structural differences between the isomers.This work provides atomic-scale insights into the cyclization processes between acetylene and C_(4)H_(3)species,establishing a foundation for refining models of soot precursor formation.
基金supported by grants from Biological Breeding-National Science and Technology Major Project(2023ZD04076)the National Key Research and Development Program of Hubei Province(2022BBA154)the Foundation of Hubei Hongshan Laboratory(2021hszd010).
文摘The post-embryonic development of shoot apices in higher plants progresses through three distinct phases:the juvenile phase,adult vegetative phase,and reproductive phase.The transition from vegetative to reproductive growth represents a critical developmental transition that affects plant adaptability(Poethig 2003;Baurle and Dean 2006).
基金supported by the National Science Foundation of China(NSFC 52571185,52201180 and 52371148)the China Postdoctoral Science Foundation(2023T160241 and 2023M731176)+2 种基金the Natural Science Foundation of Chongqing(CSTB2025NSCQ-GPX1026)the Science and Technology Research Program of Chongqing Municipal Education Commission of China(KJQN202500526)the Foundation of Chongqing Normal University(No.24XLB019).
文摘Polyamorphous transition refers to the transformation between two distinct amorphous states with identical composition.This phenomenon is intriguing in the field of physics and offers avenues for glass material design.Recently,polyamorphous transitions have been frequently observed in glassy materials.However,the transition pathway has yet to be established,which is essential for understanding its structural origins.Here,we present evidence from 12 different types of metallic glasses spanning 7 orders of magnitude in timescales,demonstrating that polyamorphous transitions consistently occur after the devitrification process,between two supercooled liquid phases(Ⅰ and Ⅱ).Notably,we observe a decrease in liquid fragility and heat capacity following the transition,suggesting that the polyamorphous transition is associated with the fragile-to-strong transition(FST)in liquids.These findings elucidate the detailed structural pathway of the polyamorphous transition,via glass I→devitrification→liquid I→fragile-strong transition→liquid II,and incorporate the FST into a cohesive framework for its understanding.
基金the Scientific and Technological Research Council of Turkey(TÜB˙ITAK)for support under project number:122M826to the Scientific Research Projects Unit of Erciyes University under contract No.:FYL-2023-13162 and FYL-2024-13701.
文摘Separation bubbles forming on airfoils significantly influence aerodynamic behavior,particularly at low Reynolds numbers,making their accurate prediction a critical challenge in transition modelling.This study investigates numerical modeling of a separation bubble and the effects of airfoil thickness and camber variation on the formation of the bubble dynamics at low Reynolds numbers.The numerical results were compared with the experimental results obtained from surface pressure distribution measurements,oil flow visualisation,and surface shear measurements to analyse the detailed flow behavior.The combination of pressure and flow visualisation techniques provided complementary insights,enabling a detailed characterisation of bubble formation.The results reveal that both the thickness and camber of the airfoil significantly influence the location,length,and stability of the bubble.At low Reynolds number flows(Re=0.5×10^(5)),particularly for highly cambered profiles,closer to the leading edge,separation and long bubbles were observed.As the Reynolds number increased,the separation point shifted to the leading edge,and reattachment became more likely.In numerical studies,transition models can accurately model the bubble initiation point;however,they often fail to model the bubble reattachment points accurately.This is due to the inadequacy of models that use empirical expressions for turbulence modelling,particularly in low Reynolds number flows,in their viscous modelling.In this study,it was concluded that transition onset terms,which specifically affect bubble formation,should be modified for more accurate modeling.
基金supported by the National Key Research and Development Program of China [grant number 2023YFF0807000]。
文摘Based on datasets from the International Best-Track Archive for Climate Stewardship(IBTrACS)and the fifth major global reanalysis produced by ECMWF(ERA5),the authors found that 29%of tropical cyclones(TCs)in the western North Pacific underwent extratropical transition(ET)from 1979 to 2022,with the frequency of ET events showing a slow decreasing trend.The extratropical transition tropical cyclones(ETCs)are classified into four clusters using the k-means clustering method based on their track patterns:recurving ETCs,westward ETCs,northwestward ETCs,and abnormal track ETCs.The transition process of recurving ETCs mostly occurs after the recurvature is completed,while 63.7%of the westward ETCs complete their transition after landfall.Abnormal track ETCs undergo transition over high-latitude oceans.Northwestward ETCs have the longest duration and slowest transition speed during the ET period,resulting in a prolonged impact.The ET process occurs at the edges of the western Pacific subtropical high(WPSH),with higher frequency during westward extension and lower during eastward retreat.While westward ETCs transition through surface friction effects,others complete ET in the northwest baroclinic zone of the WPSH.
基金supported by the National Natural Science Foundation of China (Grant Nos.92477128,92580137,92477205,12374200,11604063,11974422,and 12104504)the National Key R&D Program of China (MOST) (Grant No.2023YFA1406500)+3 种基金the Strategic Priority Research Program (Chinese Academy of Sciences,CAS) (Grant No.XDB30000000)the Fundamental Research Funds for the Central Universities and Research Funds of Renmin University of China (Grant No.21XNLG27)supported by the Outstanding Innovative Talents Cultivation Funded Programs 2023 of the Renmin University of Chinaan outcome of “Two-dimensional anisotropic series of materials FePd2+xTe2:a structural modulation study from the atomic scale to the mesoscopic scale” (RUC25QSDL128),funded by the “Qiushi Academic-Dongliang” Talent Cultivation Project at Renmin University of China in 2025。
文摘Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties.However,controlling phase transitions to form diverse heterostructures inside a single crystal remains challenging.In this study,we realize vertical/lateral polytype heterostructures in a hole-doped Mott insulator via thermal annealing-induced structural transitions.Raman spectroscopy,atomic force microscopy and scanning Kelvin probe force microscopy confirm the coexistence of T-H polytype heterostructures.Atomic-scale scanning tunneling microscopy/spectroscopy measurements reveal the transparent effect in 1H/1T vertical heterostructures,where positive bias voltage induces in a pronounced superposition of the√13×√13 CDW of the 1T-layer on the 1H-layer.By systematically comparing the 1T/1H and 1T/1T interfaces,we demonstrate that the metallic 1H-layer induces a Coulomb screening effect on the 1T-layer,suppressing the formation of CDW domain walls and forming more ordered electronic states.These results clarify the interfacial coupling between distinct quantum many-body phases and establish a controllable pathway for constructing two-dimensional polytype heterostructures with tunable electronic properties.
基金supported by the National Key Laboratory of Helicopter Aeromechanics Fund(No.2024-CXPT-GF-JJ-093-05).
文摘The complex aerodynamic interaction between tandem tilt-wing and multi-rotor directly affects the wing surface flow and rotor thrust,making it a critical factor during the tilt transition process of this configuration of rotorcraft.The aerodynamic interaction of tandem tilt-wing and multi-rotor is investigated based on the CFD method.The aerodynamic effect of multi tilt-rotor is simulated as virtual disk modeling by adding source terms to the Navier-Stokes equations,effectively reducing the calculation time while maintaining the accuracy of aerodynamic interaction calculations.Aerodynamic forces and flow field characteristics of the tandem tilt-wing and multi-rotor under different tilt angles are compared between cases with and without aerodynamic interaction.Furthermore,the differences in aerodynamic forces between dynamic tilt transition and fixed-angle conditions were compared.The results show that the aerodynamic interaction of multi-rotor obviously increases the lift of front tilt-wing at different tilt angles,the wing lift under interaction is increased by more than 40%compared with isolated wing at tilt angle of 15°for the computation in this paper,which is related to the increase of wing flow velocity and the suppression of flow separation caused by multi-rotor;the wing blocking effect will increase rotor thrust,especially near the tilt angles of 30°and 45°;the increases of rear wing lift and rear rotor thrust under aerodynamic interaction are not significant because of suppression by the front wing’s downwash;the unsteady effects during dynamic tilting have a relatively minor impact on aerodynamic interaction,with the aerodynamic forces on the rotors and wings during the dynamic tilting process showing little difference from those under corresponding fixed tilt angles.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20220409)the National Natural Science Foundation of China(No.22401153)+2 种基金the FWO[Fund for Scientific Research-Flanders(Belgium)]for financial support(recipient Erik V.Van der Eycken)the Research Council of the KU Leuven(recipient Erik V.Van der Eycken)the support of the"RUDN University Strategic Academic Leadership Program"(recipient Erik V.Van der Eycken).
文摘Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed C–H activation has been employed for the functionalization of amino acids and peptides.Through domino C–H activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed C–H activation/annulation.
基金supported by the National Natural Science Foundation of China(No.22261026).
文摘A novel method for the synthesis of 2,4-disubstituted thiophenes via the reactions of N,N-disubstituted enaminones and elemental sulfur is developed.By simply heating the substrates in pure water in the presence of NaOH,the thiophene annulation practically takes place via the generation of one C-C and two C-S bonds via cascade dual C-H functionalization and C-N bond thiolation without using any transition metal reagent.
文摘Discussions about the future of energy sources and environmental sustainability are becoming critical on a global scale.The energy sector plays a central role in the economy,as the availability and cost of energy influence the competitiveness of economies,while the level of energy consumption impacts the standard of living for individuals.This paper aims to examine environmental challenges and steps for a sustainable transition towards a hydrogen economy,focusing on its potential as an alternative to fossil fuels and the importance of developing the hydrogen paradigm.The research methodology is based on a combination of qualitative and quantitative methods,including an analysis of global and regional trends in the energy transition,the impact of various forms of hydrogen production(green,blue,gray hydrogen)on greenhouse gas emissions,and a comparison of existing policies and strategies in different countries transitioning to a sustainable hydrogen economy.Research results show that green hydrogen,produced via electrolysis using renewable energy sources,holds the greatest potential for reducing greenhouse gas emissions,while gray and blue hydrogen can serve as transitional options.The development of the hydrogen paradigm,rooted in innovative technologies,renewable energy sources,and international cooperation,is crucial for decarbonization and the creation of a sustainable global economy,despite challenges such as high costs and the need for global coordination.The hydrogen paradigm is becoming a cornerstone of these efforts,laying the foundation for a long-term,sustainable global economy.Currently,over 180 hydrogen transport projects,60 distribution projects,80 storage projects,30 terminal and port projects,and more than 220 hydrogen production projects are under development worldwide.The global momentum of the hydrogen transition helps mitigate climate change and build a sustainable future.
基金supported by the Korea Institute for Advancement of Technology (KIAT)the Ministry of Trade,Industry&Energy (MOTIE) of the Republic of Korea (No. P0022130)by the Institute of Information&Communications Technology Planning&Evaluation(IITP)-Innovative Human Resource Development for Local Intellectualization program grant funded by the Korea government (MSIT)(IITP-2025-RS-2023-00259678)
文摘To realize the practical application of anion exchange membrane water electrolysis(AEMWE),it is essential to develop highly active,durable,and cost-effective electrocatalyst for oxygen evolution reaction(OER).Herein,we report a hollow-structured Ni_(x)Co_(1−x)O/Ni_(3)S_(2)/Co_(9)S_(8)heterostructure synthesized via sequential template-assisted growth,thermal oxidation,and controlled sulfidation process.The abundant bimetallic heterointerfaces not only provide additional active sites but also promote electronic modulation via charge redistribution.Additionally,the porous and hollow architecture enhances active surface area and mass transfer ability,thereby increasing the number of accessible active sites for alkaline OER.As a result,the prepared electrocatalyst achieves low overpotential of 310 mV at 10 mA cm^(−2)and small Tafel slope of 55.94 mV dec^(−1),demonstrating the exceptional electrocatalytic performance for alkaline OER.When integrated as the anode in an AEMWE cell,it delivers outstanding performance with only 1.657 V at 1.0 A cm^(−2)and reaches high current density of 5.0 A cm^(−2)at 1.989 V,surpassing those of commercial RuO_(2).The cell also shows excellent long-term durability over 100 h with minimal degradation.This study highlights the strong potential of rationally engineered oxide/sulfide heterostructures for next-generation alkaline water electrolysis.
基金Financial support from the Fundamental Research Funds for Gannan Medical University(No.QD202429)National Natural Science Foundation of China(No.22171206)+2 种基金Natural Science Foundation of Zhejiang Province(No.LZ23B020001)Zhejiang Provincial Ten Thousand Talent Program(No.2023R5244)Open Research Fund of School of Chemistry and Chemical Engineering,Henan Normal University(No.2020ZD04).
文摘The Smiles rearrangement is an exceptionally versatile method in organic synthesis,providing a broad canvas for designing cascade reactions that construct new Csp^(2)-Y(Y=C,O,N,S,CO,etc.)bonds.Among the various types of Smiles rearrangement,the radical-type variant has emerged as a more powerful,mild,efficient,and modern synthetic technique compared to its traditional ionic counterpart.This approach excels in generating new(hetero)aromatic migration products,enabling significant advancements in recent years.This tutorial review focuses on the recent progress,since 2016,in the development and application of radical Smiles rearrangement in organic chemistry.Special attention is paid to novel transformations achieved through photochemical,electrochemical,and transition metal catalysis methods.
基金Funded by the National Natural Science Foundation of China(No.21805217)the Fundamental Research Funds for the Central Universities(WUT:2019IVB014 and 2021IVA014)。
文摘We synthesized Ru_(1)Cu_(25)P_(7.5)/TiO_(2)catalyst using sodium borohydride(NaBH_(4))as reductant in a facile strategy.The highly dispersed RuCuP nanoclusters are anchored on the TiO_(2)surface with an average particle size of 2.62 nm.The catalyst shows excellent catalytic activity when applied to the hydrolysis of AB,which owns a high turnover frequency value of 531.56 mol_(H2)mol_(Ru)^(-1)min^(-1)and a low activation energy of 46.38 kJ·mol^(-1),it also exhibits good durability which maintains 61.13%initial activity after five cycles.The high catalytic performance of Ru_(1)Cu_(25)P_(7.5)/TiO_(2)may be attributed to the synergistic effects between Ru,Cu,and P elements,fine particle size,good dispersion,and the tight adhesion between nanoclusters and carrier.
