This paper presents a novel method for optimizing the contact force of a hexapod robot to enhance its dynamic motion stability when one of its legs fails.The proposed approach aims to improve the Force Angle Stability...This paper presents a novel method for optimizing the contact force of a hexapod robot to enhance its dynamic motion stability when one of its legs fails.The proposed approach aims to improve the Force Angle Stability Margin(FASM)and adapt the foot trajectory through contact force optimization to achieve safe and stable motion on various terrains.The foot force optimization approach is designed to optimize the FASM,a factor rarely considered in existing contact force optimization methods.By formulating the problem of enhancing the motion stability of the hexapod robot as a Quadratic Programming(QP)optimization problem,this approach can effectively address this issue.Simulations of a hexapod robot using a fault-tolerant gait,along with real field experiments,were conducted to validate the effectiveness and feasibility of the contact force optimization approach.The results demonstrate that this approach can be used to design a motion controller for a hexapod robot with a significantly improved motion stability.In summary,the proposed contact force optimization method offers a promising solution for enhancing the motion stability of hexapod robots with single leg failures and has the potential to significantly advance the development of fault-tolerant hexapod robots for various applications.展开更多
This paper designs a soft robot with a multi-chamber,multi-airbag mimicking soft biological structure,where the airbags of the same chamber are interconnected with each other.The upper and lower chambers are separated...This paper designs a soft robot with a multi-chamber,multi-airbag mimicking soft biological structure,where the airbags of the same chamber are interconnected with each other.The upper and lower chambers are separated by an intermediate layer(thin plate),which is extended and widened to achieve robot movement and balance.By applying pressure to the different chambers of the soft robot,it is possible to produce a variety of bionic movements of the inchworm and caterpillar.Due to the strong nonlinearity and infinite number of degrees of freedom properties of the material,it is impossible to obtain the analytical solution of the bending morphology and pressure of the soft robot directly.Therefore,a method to establish a mathematical model of soft robot deformation based on the classical stacked plate theory is proposed,and a chain composite model of soft robot bending motion is established based on the large-deflection modeling method.This paper proposes a method to generate a multi-mode soft robot motion control based on the Central Pattern Generator(CPG)using a single controller,which achieves the switching of sine wave-like patterns,half-wave-like patterns,and dragging patterns by adjust-ing frequency,amplitude and period of parameters.Finally,a pneumatic control platform is built for the validation of the theoretical model and different experimental models of the motion of the robot.And comparation of the different motion modes of the soft robot under similar non-load and load conditions.展开更多
The application of grooved surface structure is an emerging and effective means in turbulence flow control.However,for a realistic configuration,the global flow field described directly by simple application of massiv...The application of grooved surface structure is an emerging and effective means in turbulence flow control.However,for a realistic configuration,the global flow field described directly by simple application of massive grids makes it unfeasible to simulate.In this paper,a boundary surrogate model reproducing the effect of microscopic near-wall region is proposed to improve computational efficiency.The surrogate model trained with Lattice Boltzmann Method(LBM)considering the rarefied effect based on real micro/nanoflow field is new among literature,which accurately shows flow characteristics of the micro/nano structure.With this approach,numerical simulations via Reynolds-averaged Navier Stokes equations with modified wall boundary condition are performed in subsonic and transonic flow.The results show that micro/nano grooved surface structure has the effect of delaying transition from laminar to turbulence,thus reducing the skin friction significantly.Analysis of turbulence intensity and turbulence kinetic energy shows that the near-wall flow field of grooved airfoil is more stable compared with that of the smooth airfoil.The reducing rate of maximum turbulent intensity reaches 13.39%.The paper shows a perspective for further application of micro/nano groove structure to turbulence flow control in aircraft design by providing an accurate and efficient simulation method.展开更多
Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,...Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.展开更多
Fuel cells have attracted extensive attention due to their high conversion efficiency and environmental friendliness.However,their wider application is limited by the poor activity and high cost of platinum(Pt),which ...Fuel cells have attracted extensive attention due to their high conversion efficiency and environmental friendliness.However,their wider application is limited by the poor activity and high cost of platinum(Pt),which is widely used as the cathode catalyst to overcome the slow kinetics associated with oxygen reduction reaction(ORR).Pt‐based composites with one‐dimensional(1D)nanoarchitectures demonstrate great advantages towards efficient ORR catalysis.This review focuses on the recent advancements in the design and synthesis of 1D Pt‐based ORR catalysts.After introducing the fundamental ORR mechanism and the advanced 1D architectures,their synthesis strategies(template‐based and template‐free methods)are discoursed.Subsequently,their morphology and structure optimization are highlighted,followed by the superstructure assembly using 1D Pt‐based blocks.Finally,the challenges and perspectives on the synthesis innovation,structure design,physical characterization,and theoretical investigations are proposed for 1D Pt‐based ORR nanocatalysts.We anticipate this study will inspire more research endeavors on efficient ORR nanocatalysts in fuel cell application.展开更多
The electrocatalytic water splitting technology can generate highpurity hydrogen without emitting carbon dioxide,which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality...The electrocatalytic water splitting technology can generate highpurity hydrogen without emitting carbon dioxide,which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality.Electrocatalysts can effectively reduce the reaction energy barrier and increase the reaction efficiency.Facet engineering is considered as a promising strategy in controlling the ratio of desired crystal planes on the surface.Owing to the anisotropy,crystal planes with different orientations usually feature facet-dependent physical and chemical properties,leading to differences in the adsorption energies of oxygen or hydrogen intermediates,and thus exhibit varied electrocatalytic activity toward hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this review,a brief introduction of the basic concepts,fundamental understanding of the reaction mechanisms as well as key evaluating parameters for both HER and OER are provided.The formation mechanisms of the crystal facets are comprehensively overviewed aiming to give scientific theory guides to realize dominant crystal planes.Subsequently,three strategies of selective capping agent,selective etching agent,and coordination modulation to tune crystal planes are comprehensively summarized.Then,we present an overview of significant contributions of facet-engineered catalysts toward HER,OER,and overall water splitting.In particular,we highlight that density functional theory calculations play an indispensable role in unveiling the structure–activity correlation between the crystal plane and catalytic activity.Finally,the remaining challenges in facet-engineered catalysts for HER and OER are provided and future prospects for designing advanced facet-engineered electrocatalysts are discussed.展开更多
Laminar flow design is one of the most effective ways to reduce the drag of a commercial aircraft by expanding the laminar flow region on the surface of the aircraft. As material science develops, the emergence of new...Laminar flow design is one of the most effective ways to reduce the drag of a commercial aircraft by expanding the laminar flow region on the surface of the aircraft. As material science develops, the emergence of new materials such as low surface energy materials has offered new choices for laminar flow design of commercial aircraft. Different types of low surface energy micro-nano coatings are prepared to verify the effects on the boundary layer transition position and the drag of the airfoil through wind tunnel tests. The infrared thermal imaging technology is adopted for measuring the boundary layer transition, while the momentum integral approach is employed to measure the drag coefficient through a wake rake. Infrared thermal imaging results indicate that the coatings are capable of moving backward the boundary layer transition position at both a low velocity of Mach number 0.15 and a high velocity of Mach number 0.785. Results of the momentum integral approach demonstrate that the drag coefficients are reduced obviously within the cruising angle of attack range from 1° and 5° by introducing the low surface energy micro-nano coating technology.展开更多
The frontal pole cortex(FPC)plays key roles in various higher-order functions and is highly developed in non-human primates.An essential missing piece of information is the detailed anatomical connections for finer pa...The frontal pole cortex(FPC)plays key roles in various higher-order functions and is highly developed in non-human primates.An essential missing piece of information is the detailed anatomical connections for finer parcellation of the macaque FPC than provided by the previous tracer results.This is important for understanding the functional architecture of the cerebral cortex.Here,combining cross-validation and principal component analysis,we formed a tractography-based parcellation scheme that applied a machine learning algorithm to divide the macaque FPC(2 males and 6 females)into eight subareas using high-resolution diffusion magnetic resonance imaging with the 9.4 T Bruker system,and then revealed their subregional connections.Furthermore,we applied improved hierarchical clustering to the obtained parcels to probe the modular structure of the subregions,and found that the dorsolateral FPC,which contains an extension to the medial FPC,was mainly connected to regions of the default-mode network.The ventral FPC was mainly involved in the social-interaction network and the dorsal FPC in the metacognitive network.These results enhance our understanding of the anatomy and circuitry of the macaque brain,and contribute to FPC-related clinical research.展开更多
Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surfa...Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.展开更多
Methylglyoxal(CH3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxy...Methylglyoxal(CH3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3)K,atmospheric pressure,(18±2)%relative humidity,and under different NOx and SO2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS)and the results showed that the addition of SO2 can promote SOA formation,while different NOx concentrations have different influences on SOA production.High NOx suppressed the SOA formation,whereas the particle mass concentration,particle number concentration and particle geometric mean diameter increased with the increasing NOx concentration at low NOx concentration in the presence of SO2.In addition,the products of the OH-initiated oxidation of MG and the functional groups of the particle phase in the MG/OH/SO2 and MG/OH/NOx/SO2 reaction systems were detected by gas chromatography mass spectrometry(GC-MS)and attenuated total reflection fourier transformed infrared spectroscopy(ATR-FTIR)analysis.Two products,glyoxylic acid and oxalic acid,were detected by GC-MS.The mechanism of the reaction of MG and OH radicals that follows two main pathways,H atom abstraction and hydration,is proposed.Evidence is provided for the formation of organic nitrates and organic sulfate in particle phase from IR spectra.Incorporation of NOx and SO2 influence suggested that SOA formation from anthropogenic hydrocarbons may be more efficient in polluted environment.展开更多
Renewable energy-driven hydrogen generation from water electrolysis has been widely recognized as a promising approach to utilize sustainable energy resources,reduce our dependence on legacy fossil fuels and alleviate...Renewable energy-driven hydrogen generation from water electrolysis has been widely recognized as a promising approach to utilize sustainable energy resources,reduce our dependence on legacy fossil fuels and alleviate net carbon dioxide emissions.However,conventional water electrolyzers suffer from the high overpotentials,mainly due to the sluggish kinetics of anodic oxygen evolution reaction(OER).This reaction also generates reactive oxygen species that could degrade the proton exchange membrane and oxygen that may mix with the cathodic hydrogen to form explosive gaseous mixtures.To address these issues,an innovative hybrid water electrolysis strategy which involves a certain alternative oxidation reaction to replace OER has been developed,and has led to a burgeoning area that sparks much research interest in finding available alternative reactions and their corresponding electrocatalysts.Herein,we summarize the alternative reactions into three groups:(1)the reagentsacrificing type that can generate H2 with an ultra-low potential while the substrates are oxidized to valueless products;(2)the pollutant-degrading type at which environmental pollutants are used as substrates;(3)the valueadded type that produces valuable products at the anode.Catalyst and electrolyzer designs for hybrid electrolysis are also briefly discussed,with an emphasis on the catalyst reconstruction phenomenon.Finally,the present challenges and perspectives are put forward.展开更多
Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative,5-aryl-1,3-dioxan-5-ol,as versatile 1,3-biselectrophile.In the reactions,5-aryl-1,3-dioxan-5-ol works like atrop...Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative,5-aryl-1,3-dioxan-5-ol,as versatile 1,3-biselectrophile.In the reactions,5-aryl-1,3-dioxan-5-ol works like atropaldehydes or 2-aryl malondialdehydes,and can react with 2-naphthols andβ-keto amides,allowing the synthesis of 4H-chromenes and 5-aryl-2-pyridinones.High yields,good functional group tolerance,broad substrate scope and simple reaction operation make this protocol attractive.展开更多
Developing efficient platinum(Pt)-based electrocatalysts is enormously significant for fuel cells.Herein,we report an integrated electrocatalyst of ultralow-Pt alloy encapsulated into nitrogen-doped nanocarbon archite...Developing efficient platinum(Pt)-based electrocatalysts is enormously significant for fuel cells.Herein,we report an integrated electrocatalyst of ultralow-Pt alloy encapsulated into nitrogen-doped nanocarbon architecture for efficient oxygen reduction reaction.This hybrid Pt-based catalyst achieves a mass activity of 3.46 A mg^(-1)_(pt)the potential of 0.9 V vs.RHE with a negligible stability decay after 10,000 cycles.More importantly,this half-cell activity can be expressed at full cell level with a high Pt utilization of 10.22 W mg^(-1)_(Pt cathode)and remarkable durability after 30,000 cycles in single-cell.Experimental and theoretical investigations reveal that a highly strained Pt structure with an optimal Pt-0 binding energy is induced by the incorporation of Co/Ni into Pt lattice,which would account for the improved reaction kinetics.The synergistic catalysis due to nitrogen-doped nanocarbon architecture and active Pt component is responsible for the enhanced catalytic activity.Meanwhile,the strong metal-support interaction and optimized hydrophilic properties of nanocarbon matrix facilitate efficient mass transport and water management.This work may provide significant insights in designing the low-Pt integrated electrocatalysts for fuel cells and beyond.展开更多
Designing earth-abundant electrocatalysts with high performance towards water oxidation is highly decisive for the sustainable energy technologies. This study develops a facile natural corrosion approach to fabricate ...Designing earth-abundant electrocatalysts with high performance towards water oxidation is highly decisive for the sustainable energy technologies. This study develops a facile natural corrosion approach to fabricate nickel-iron hydroxides for water oxidation. The resulted electrode demonstrates an outstanding activity and stability with an overpotential of 275 mV to deliver 10 mA·cm^(−2). Experimental and theoretical results suggest the corrosion-induced formation of hydroxides and their transformation to oxyhydroxides would account for this excellent performance. This work not only provides an interesting corrosion approach for the fabrication of excellent water oxidation electrode, but also bridges traditional corrosion engineering and novel materials fabrication, which would offer some insights in the innovative principles for nanomaterials and energy technologies.展开更多
Background:Gut ischemia and hypoxia post severe burn leads to breakdown of intestinal epithelial barrier and enteric bacterial translocation(EBT),resulting in serious complications,such as systemic inflammatory respon...Background:Gut ischemia and hypoxia post severe burn leads to breakdown of intestinal epithelial barrier and enteric bacterial translocation(EBT),resulting in serious complications,such as systemic inflammatory response syndrome,sepsis and multiple organ failure.Cystic fibrosis transmembrane conductance regulator(CFTR)is known to be downregulated by hypoxia and modulate junctional complexes,which are crucial structures maintaining the intestinal barrier.This study aimed to investigate whether CFTR plays a role in both regulating the intestinal barrier and mediating EBT post severe burn,as well as the signaling pathways involved in these processes.Methods:An in vitro Caco-2 cell model subjected to hypoxic injury and an in vivo mouse model with a 30%total body surface area full-thickness dermal burn were established.DF 508 mice(mice with F508del CFTR gene mutation)were used as an in vivo model to further demonstrate the role of CFTR in maintaining normal intestinal barrier function.QRT-PCR,western blot,ELISA,TER assay and immunofluorescence staining were used to detect the expression and localization of CFTR and tight junction proteins,as well as the function of tight junctions.Results:Our data indicated that,in Caco-2 cells,the hypoxia condition significantly reduced CFTR expression;activated extracellular signal-regulated kinase and nuclear factor-κB signaling;elevated secretion of inflammatory factors(tumor necrosis factor-α,interleukin-1βand interleukin-8);downregulated zonula occludens-1,occludin and E-cadherin expression;decreased transepithelial electrical resistance values;and led to a cellular mislocation of ZO-1.More importantly,knockdown of CFTR caused similar alterations.The upregulation of inflammatory factors and downregulation of tight junction proteins(ZO-1 and occludin)induced by knockdown of CFTR could be reversed by specific extracellular signal-regulated kinase or nuclear factor-κB inhibition.In support of the in vitro data,exuberant secretion of pro-inflammatory mediators and EBT was observed in the intestine of severely burnt mice in vivo.EBT occurred in DF508 mice(mice with the F508del CFTR gene mutation),accompanied by augmented tumor necrosis factor-α,interleukin-1βand interleukin-8 levels in the ileum compared to wildtype mice.In addition,vitamin D3 was shown to protect the intestinal epithelial barrier from hypoxic injury.Conclusions:Collectively,the present study illustrated that CFTR and downstream signaling were critical in modulating the intestinal epithelial junction and EBT post severe burn.展开更多
Cu-based electrocatalysts with favorable facets and Cu^(+)can boost CO_(2) reduction to valuable multicarbon products.However,the inevitable Cu^(+)reduction and the phase evolution usually result in poor performance.H...Cu-based electrocatalysts with favorable facets and Cu^(+)can boost CO_(2) reduction to valuable multicarbon products.However,the inevitable Cu^(+)reduction and the phase evolution usually result in poor performance.Herein,we fabricate CuI nanodots with favorable(220)facets and a stable Cu^(+)state,accomplished by operando reconstruction of Cu(OH)_(2) under CO_(2)-and I--containing electrolytes for enhanced CO_(2)-to-C_(2)H_(4) conversion.Synchrotron X-ray absorption spectroscopy(XAS),in-situ Raman spectroscopy and thermodynamic potential analysis reveal the preferred formation of CuI.Vacuum gas electroresponse and density functional theory(DFT)calculations reveal that CO_(2)-related species induce the exposure of the(220)plane of Cu I.Moreover,the small size of nanodots enables the adequate contact with I^(-),which guarantees the rapid formation of Cu I instead of the electroreduction to Cu^(0).As a result,the resulting catalysts exhibit a high C2H4 Faradaic efficiency of 72.4%at a large current density of 800 m A cm^(-2) and robust stability for 12 h in a flow cell.Combined in-situ ATR-SEIRS spectroscopic characterizations and DFT calculations indicate that the(220)facets and stable Cu^(+) in CuI nanodots synergistically facilitate CO_(2)/*CO adsorption and*CO dimerization.展开更多
The radiation decay of a two-level atom could be inhibited within structured environments even under longtime evolution.We investigate the stabilized quantum coherence of composite systems undergoing local dissipation...The radiation decay of a two-level atom could be inhibited within structured environments even under longtime evolution.We investigate the stabilized quantum coherence of composite systems undergoing local dissipation and exploit it further as a resource for remote state preparation.We focus on outputs of quantum states with solely quantum discord(i.e.,without entanglement)and demonstrate that they could be resulted from various initial states providing specific spectral structure of the reservoir.In detail,we elaborate the behavior of stabilized quantum discord and the corresponding fidelity for remote state preparation in connection with structural spectra of Ohmic class reservoir and of photonic band gap mediums.展开更多
基金The funding has been received from National Natural Science Foundation of China with Grant nos.52205013,52175012Fundamental Research Foundation for Universities of Heilongjiang Province with Grant no.2022-KYYWF-0122+1 种基金Natural Science Foundation of Heilongjiang Province with Grant no.LH2020E088Foundation of State Key Laboratory of Robotics and Systems with Grant no.SKLRS-2022-KF-18.
文摘This paper presents a novel method for optimizing the contact force of a hexapod robot to enhance its dynamic motion stability when one of its legs fails.The proposed approach aims to improve the Force Angle Stability Margin(FASM)and adapt the foot trajectory through contact force optimization to achieve safe and stable motion on various terrains.The foot force optimization approach is designed to optimize the FASM,a factor rarely considered in existing contact force optimization methods.By formulating the problem of enhancing the motion stability of the hexapod robot as a Quadratic Programming(QP)optimization problem,this approach can effectively address this issue.Simulations of a hexapod robot using a fault-tolerant gait,along with real field experiments,were conducted to validate the effectiveness and feasibility of the contact force optimization approach.The results demonstrate that this approach can be used to design a motion controller for a hexapod robot with a significantly improved motion stability.In summary,the proposed contact force optimization method offers a promising solution for enhancing the motion stability of hexapod robots with single leg failures and has the potential to significantly advance the development of fault-tolerant hexapod robots for various applications.
基金funded and supported by National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(Grant no.52025054)State Key Laboratory of Robotics and Systems(HIT)(SKLRS-2021-KF-13).
文摘This paper designs a soft robot with a multi-chamber,multi-airbag mimicking soft biological structure,where the airbags of the same chamber are interconnected with each other.The upper and lower chambers are separated by an intermediate layer(thin plate),which is extended and widened to achieve robot movement and balance.By applying pressure to the different chambers of the soft robot,it is possible to produce a variety of bionic movements of the inchworm and caterpillar.Due to the strong nonlinearity and infinite number of degrees of freedom properties of the material,it is impossible to obtain the analytical solution of the bending morphology and pressure of the soft robot directly.Therefore,a method to establish a mathematical model of soft robot deformation based on the classical stacked plate theory is proposed,and a chain composite model of soft robot bending motion is established based on the large-deflection modeling method.This paper proposes a method to generate a multi-mode soft robot motion control based on the Central Pattern Generator(CPG)using a single controller,which achieves the switching of sine wave-like patterns,half-wave-like patterns,and dragging patterns by adjust-ing frequency,amplitude and period of parameters.Finally,a pneumatic control platform is built for the validation of the theoretical model and different experimental models of the motion of the robot.And comparation of the different motion modes of the soft robot under similar non-load and load conditions.
基金funded by AECC Commercial Aircraft Engine in the project of Laminar Flow Design and Turbulent Drag Reduction of Compressor Blade Profile and Experimental Verification。
文摘The application of grooved surface structure is an emerging and effective means in turbulence flow control.However,for a realistic configuration,the global flow field described directly by simple application of massive grids makes it unfeasible to simulate.In this paper,a boundary surrogate model reproducing the effect of microscopic near-wall region is proposed to improve computational efficiency.The surrogate model trained with Lattice Boltzmann Method(LBM)considering the rarefied effect based on real micro/nanoflow field is new among literature,which accurately shows flow characteristics of the micro/nano structure.With this approach,numerical simulations via Reynolds-averaged Navier Stokes equations with modified wall boundary condition are performed in subsonic and transonic flow.The results show that micro/nano grooved surface structure has the effect of delaying transition from laminar to turbulence,thus reducing the skin friction significantly.Analysis of turbulence intensity and turbulence kinetic energy shows that the near-wall flow field of grooved airfoil is more stable compared with that of the smooth airfoil.The reducing rate of maximum turbulent intensity reaches 13.39%.The paper shows a perspective for further application of micro/nano groove structure to turbulence flow control in aircraft design by providing an accurate and efficient simulation method.
基金Project supported by the National Natural Science Foundation of China (Grant No.12104291)。
文摘Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.
文摘Fuel cells have attracted extensive attention due to their high conversion efficiency and environmental friendliness.However,their wider application is limited by the poor activity and high cost of platinum(Pt),which is widely used as the cathode catalyst to overcome the slow kinetics associated with oxygen reduction reaction(ORR).Pt‐based composites with one‐dimensional(1D)nanoarchitectures demonstrate great advantages towards efficient ORR catalysis.This review focuses on the recent advancements in the design and synthesis of 1D Pt‐based ORR catalysts.After introducing the fundamental ORR mechanism and the advanced 1D architectures,their synthesis strategies(template‐based and template‐free methods)are discoursed.Subsequently,their morphology and structure optimization are highlighted,followed by the superstructure assembly using 1D Pt‐based blocks.Finally,the challenges and perspectives on the synthesis innovation,structure design,physical characterization,and theoretical investigations are proposed for 1D Pt‐based ORR nanocatalysts.We anticipate this study will inspire more research endeavors on efficient ORR nanocatalysts in fuel cell application.
基金support from the National Natural Science Foundation of China(No.22005147)Dr.You acknowledges the financial support from the National Key Research and Development Program of China(2021YFA1600800)+1 种基金the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)the Open Research Fund of Key Laboratory of Material Chemistry for Energy Conversion and Storage(HUST),Ministry of Education(2021JYBKF03).
文摘The electrocatalytic water splitting technology can generate highpurity hydrogen without emitting carbon dioxide,which is in favor of relieving environmental pollution and energy crisis and achieving carbon neutrality.Electrocatalysts can effectively reduce the reaction energy barrier and increase the reaction efficiency.Facet engineering is considered as a promising strategy in controlling the ratio of desired crystal planes on the surface.Owing to the anisotropy,crystal planes with different orientations usually feature facet-dependent physical and chemical properties,leading to differences in the adsorption energies of oxygen or hydrogen intermediates,and thus exhibit varied electrocatalytic activity toward hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).In this review,a brief introduction of the basic concepts,fundamental understanding of the reaction mechanisms as well as key evaluating parameters for both HER and OER are provided.The formation mechanisms of the crystal facets are comprehensively overviewed aiming to give scientific theory guides to realize dominant crystal planes.Subsequently,three strategies of selective capping agent,selective etching agent,and coordination modulation to tune crystal planes are comprehensively summarized.Then,we present an overview of significant contributions of facet-engineered catalysts toward HER,OER,and overall water splitting.In particular,we highlight that density functional theory calculations play an indispensable role in unveiling the structure–activity correlation between the crystal plane and catalytic activity.Finally,the remaining challenges in facet-engineered catalysts for HER and OER are provided and future prospects for designing advanced facet-engineered electrocatalysts are discussed.
基金support by the United Innovation Program of Shanghai Commercial Aircraft Engine, which was founded by Shanghai Municipal Commission of Economy and Informatization, Shanghai Municipal Education Commission, and AECC Commercial Aircraft Engine Co., Ltd. (No. AR909)the Aeronautical Science Foundation of China (No. 2015ZBP9002)the China Scholarship Council
文摘Laminar flow design is one of the most effective ways to reduce the drag of a commercial aircraft by expanding the laminar flow region on the surface of the aircraft. As material science develops, the emergence of new materials such as low surface energy materials has offered new choices for laminar flow design of commercial aircraft. Different types of low surface energy micro-nano coatings are prepared to verify the effects on the boundary layer transition position and the drag of the airfoil through wind tunnel tests. The infrared thermal imaging technology is adopted for measuring the boundary layer transition, while the momentum integral approach is employed to measure the drag coefficient through a wake rake. Infrared thermal imaging results indicate that the coatings are capable of moving backward the boundary layer transition position at both a low velocity of Mach number 0.15 and a high velocity of Mach number 0.785. Results of the momentum integral approach demonstrate that the drag coefficients are reduced obviously within the cruising angle of attack range from 1° and 5° by introducing the low surface energy micro-nano coating technology.
基金the National Natural Science Foundation of China(91432302 and 31620103905)the Science Frontier Program of the Chinese Academy of Sciences(QYZDJ-SSW-SMC019)+3 种基金the National Key R&D Program of China(2017YFA0105203)Beijing Municipal Science and Technology Commission(Z161100000216152,Z161100000216139,Z181100001518004and Z171100000117002)the Beijing Brain Initiative of Beijing Municipal Science and Technology Commission(Z181100001518004)the Guangdong Pearl River Talents Plan(2016ZT06S220)。
文摘The frontal pole cortex(FPC)plays key roles in various higher-order functions and is highly developed in non-human primates.An essential missing piece of information is the detailed anatomical connections for finer parcellation of the macaque FPC than provided by the previous tracer results.This is important for understanding the functional architecture of the cerebral cortex.Here,combining cross-validation and principal component analysis,we formed a tractography-based parcellation scheme that applied a machine learning algorithm to divide the macaque FPC(2 males and 6 females)into eight subareas using high-resolution diffusion magnetic resonance imaging with the 9.4 T Bruker system,and then revealed their subregional connections.Furthermore,we applied improved hierarchical clustering to the obtained parcels to probe the modular structure of the subregions,and found that the dorsolateral FPC,which contains an extension to the medial FPC,was mainly connected to regions of the default-mode network.The ventral FPC was mainly involved in the social-interaction network and the dorsal FPC in the metacognitive network.These results enhance our understanding of the anatomy and circuitry of the macaque brain,and contribute to FPC-related clinical research.
基金This research was financially supported by the Key Project of China Educational Ministry (No. 103064)the Doctoral Foundation of University (No. 20020246031)
文摘Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.
基金supported by the National Natural Science Foundation of China(No.91644214)the Shandong Natural Science Fund for Distinguished Young Scholars(No.JQ201705)。
文摘Methylglyoxal(CH3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3)K,atmospheric pressure,(18±2)%relative humidity,and under different NOx and SO2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS)and the results showed that the addition of SO2 can promote SOA formation,while different NOx concentrations have different influences on SOA production.High NOx suppressed the SOA formation,whereas the particle mass concentration,particle number concentration and particle geometric mean diameter increased with the increasing NOx concentration at low NOx concentration in the presence of SO2.In addition,the products of the OH-initiated oxidation of MG and the functional groups of the particle phase in the MG/OH/SO2 and MG/OH/NOx/SO2 reaction systems were detected by gas chromatography mass spectrometry(GC-MS)and attenuated total reflection fourier transformed infrared spectroscopy(ATR-FTIR)analysis.Two products,glyoxylic acid and oxalic acid,were detected by GC-MS.The mechanism of the reaction of MG and OH radicals that follows two main pathways,H atom abstraction and hydration,is proposed.Evidence is provided for the formation of organic nitrates and organic sulfate in particle phase from IR spectra.Incorporation of NOx and SO2 influence suggested that SOA formation from anthropogenic hydrocarbons may be more efficient in polluted environment.
基金We acknowledge the financial support from the Start-up Funding of the Huazhong University of Science and Technology(HUST)and the Program for HUST Academic Frontier Youth Team(2018QYTD15).
文摘Renewable energy-driven hydrogen generation from water electrolysis has been widely recognized as a promising approach to utilize sustainable energy resources,reduce our dependence on legacy fossil fuels and alleviate net carbon dioxide emissions.However,conventional water electrolyzers suffer from the high overpotentials,mainly due to the sluggish kinetics of anodic oxygen evolution reaction(OER).This reaction also generates reactive oxygen species that could degrade the proton exchange membrane and oxygen that may mix with the cathodic hydrogen to form explosive gaseous mixtures.To address these issues,an innovative hybrid water electrolysis strategy which involves a certain alternative oxidation reaction to replace OER has been developed,and has led to a burgeoning area that sparks much research interest in finding available alternative reactions and their corresponding electrocatalysts.Herein,we summarize the alternative reactions into three groups:(1)the reagentsacrificing type that can generate H2 with an ultra-low potential while the substrates are oxidized to valueless products;(2)the pollutant-degrading type at which environmental pollutants are used as substrates;(3)the valueadded type that produces valuable products at the anode.Catalyst and electrolyzer designs for hybrid electrolysis are also briefly discussed,with an emphasis on the catalyst reconstruction phenomenon.Finally,the present challenges and perspectives are put forward.
基金The National Key Research and Development Project(No.2022YFE0124100)Ordos Key Research and Development Project(No.2022EEDSKJZDZX003)+3 种基金National Natural Science Foundation of China(Nos.21872060,21902054,21761132014,and 22072049)the Open Research Fund(No.2022JYBKF01)of Key Laboratory of Material Chemistry for Energy Conversion and Storage(HUST),Ministry of Education,are acknowledged for the financial supportProgram for HUST Academic Frontier Youth Team(No.2019QYTD06)is also acknowledgedsupported by The Innovation and Talent Recruitment Base of New Energy Chemistry and Device。
文摘Acid-catalyzed tandem reactions were established by employing a novel class of 2-arylglycerol derivative,5-aryl-1,3-dioxan-5-ol,as versatile 1,3-biselectrophile.In the reactions,5-aryl-1,3-dioxan-5-ol works like atropaldehydes or 2-aryl malondialdehydes,and can react with 2-naphthols andβ-keto amides,allowing the synthesis of 4H-chromenes and 5-aryl-2-pyridinones.High yields,good functional group tolerance,broad substrate scope and simple reaction operation make this protocol attractive.
基金the National Natural Science Foundation of China(22075092 and 21805104)the Program for Huazhong University of Science and Technology(HUST)Academic Frontier Youth Team(2018QYTD15)The Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)。
文摘Developing efficient platinum(Pt)-based electrocatalysts is enormously significant for fuel cells.Herein,we report an integrated electrocatalyst of ultralow-Pt alloy encapsulated into nitrogen-doped nanocarbon architecture for efficient oxygen reduction reaction.This hybrid Pt-based catalyst achieves a mass activity of 3.46 A mg^(-1)_(pt)the potential of 0.9 V vs.RHE with a negligible stability decay after 10,000 cycles.More importantly,this half-cell activity can be expressed at full cell level with a high Pt utilization of 10.22 W mg^(-1)_(Pt cathode)and remarkable durability after 30,000 cycles in single-cell.Experimental and theoretical investigations reveal that a highly strained Pt structure with an optimal Pt-0 binding energy is induced by the incorporation of Co/Ni into Pt lattice,which would account for the improved reaction kinetics.The synergistic catalysis due to nitrogen-doped nanocarbon architecture and active Pt component is responsible for the enhanced catalytic activity.Meanwhile,the strong metal-support interaction and optimized hydrophilic properties of nanocarbon matrix facilitate efficient mass transport and water management.This work may provide significant insights in designing the low-Pt integrated electrocatalysts for fuel cells and beyond.
基金This work is financially supported by the National Natural Science Foundation of China(No.22075092)China Postdoctoral Science Foundation(No.2018M642810)the Program for HUST Academic Frontier Youth Team(No.2018QYTD15)。
文摘Designing earth-abundant electrocatalysts with high performance towards water oxidation is highly decisive for the sustainable energy technologies. This study develops a facile natural corrosion approach to fabricate nickel-iron hydroxides for water oxidation. The resulted electrode demonstrates an outstanding activity and stability with an overpotential of 275 mV to deliver 10 mA·cm^(−2). Experimental and theoretical results suggest the corrosion-induced formation of hydroxides and their transformation to oxyhydroxides would account for this excellent performance. This work not only provides an interesting corrosion approach for the fabrication of excellent water oxidation electrode, but also bridges traditional corrosion engineering and novel materials fabrication, which would offer some insights in the innovative principles for nanomaterials and energy technologies.
文摘Background:Gut ischemia and hypoxia post severe burn leads to breakdown of intestinal epithelial barrier and enteric bacterial translocation(EBT),resulting in serious complications,such as systemic inflammatory response syndrome,sepsis and multiple organ failure.Cystic fibrosis transmembrane conductance regulator(CFTR)is known to be downregulated by hypoxia and modulate junctional complexes,which are crucial structures maintaining the intestinal barrier.This study aimed to investigate whether CFTR plays a role in both regulating the intestinal barrier and mediating EBT post severe burn,as well as the signaling pathways involved in these processes.Methods:An in vitro Caco-2 cell model subjected to hypoxic injury and an in vivo mouse model with a 30%total body surface area full-thickness dermal burn were established.DF 508 mice(mice with F508del CFTR gene mutation)were used as an in vivo model to further demonstrate the role of CFTR in maintaining normal intestinal barrier function.QRT-PCR,western blot,ELISA,TER assay and immunofluorescence staining were used to detect the expression and localization of CFTR and tight junction proteins,as well as the function of tight junctions.Results:Our data indicated that,in Caco-2 cells,the hypoxia condition significantly reduced CFTR expression;activated extracellular signal-regulated kinase and nuclear factor-κB signaling;elevated secretion of inflammatory factors(tumor necrosis factor-α,interleukin-1βand interleukin-8);downregulated zonula occludens-1,occludin and E-cadherin expression;decreased transepithelial electrical resistance values;and led to a cellular mislocation of ZO-1.More importantly,knockdown of CFTR caused similar alterations.The upregulation of inflammatory factors and downregulation of tight junction proteins(ZO-1 and occludin)induced by knockdown of CFTR could be reversed by specific extracellular signal-regulated kinase or nuclear factor-κB inhibition.In support of the in vitro data,exuberant secretion of pro-inflammatory mediators and EBT was observed in the intestine of severely burnt mice in vivo.EBT occurred in DF508 mice(mice with the F508del CFTR gene mutation),accompanied by augmented tumor necrosis factor-α,interleukin-1βand interleukin-8 levels in the ileum compared to wildtype mice.In addition,vitamin D3 was shown to protect the intestinal epithelial barrier from hypoxic injury.Conclusions:Collectively,the present study illustrated that CFTR and downstream signaling were critical in modulating the intestinal epithelial junction and EBT post severe burn.
基金financially supported by The National Key Research and Development Program of China(2021YFA1600800)the Start-up Funding of the Huazhong University of Science and Technology(HUST)+2 种基金the Program for HUST Academic Frontier Youth Teamthe National Natural Science Foundation of China(22075092)the National 1000 Young Talents Program of China and The Innovation and Talent Recruitment Base of New Energy Chemistry and Device(B21003)。
文摘Cu-based electrocatalysts with favorable facets and Cu^(+)can boost CO_(2) reduction to valuable multicarbon products.However,the inevitable Cu^(+)reduction and the phase evolution usually result in poor performance.Herein,we fabricate CuI nanodots with favorable(220)facets and a stable Cu^(+)state,accomplished by operando reconstruction of Cu(OH)_(2) under CO_(2)-and I--containing electrolytes for enhanced CO_(2)-to-C_(2)H_(4) conversion.Synchrotron X-ray absorption spectroscopy(XAS),in-situ Raman spectroscopy and thermodynamic potential analysis reveal the preferred formation of CuI.Vacuum gas electroresponse and density functional theory(DFT)calculations reveal that CO_(2)-related species induce the exposure of the(220)plane of Cu I.Moreover,the small size of nanodots enables the adequate contact with I^(-),which guarantees the rapid formation of Cu I instead of the electroreduction to Cu^(0).As a result,the resulting catalysts exhibit a high C2H4 Faradaic efficiency of 72.4%at a large current density of 800 m A cm^(-2) and robust stability for 12 h in a flow cell.Combined in-situ ATR-SEIRS spectroscopic characterizations and DFT calculations indicate that the(220)facets and stable Cu^(+) in CuI nanodots synergistically facilitate CO_(2)/*CO adsorption and*CO dimerization.
基金supported by the National Natural Science Foundation of China (10874254)
文摘The radiation decay of a two-level atom could be inhibited within structured environments even under longtime evolution.We investigate the stabilized quantum coherence of composite systems undergoing local dissipation and exploit it further as a resource for remote state preparation.We focus on outputs of quantum states with solely quantum discord(i.e.,without entanglement)and demonstrate that they could be resulted from various initial states providing specific spectral structure of the reservoir.In detail,we elaborate the behavior of stabilized quantum discord and the corresponding fidelity for remote state preparation in connection with structural spectra of Ohmic class reservoir and of photonic band gap mediums.
