Hydrogen peroxide(H_(2)O_(2))oxidation and reduction reactions(HPOR/HPRR)are pivotal in various innovative electrochemical energy conversion devices.A comprehensive understanding of these mechanisms is critical for ca...Hydrogen peroxide(H_(2)O_(2))oxidation and reduction reactions(HPOR/HPRR)are pivotal in various innovative electrochemical energy conversion devices.A comprehensive understanding of these mechanisms is critical for catalyst design and performance improvement in these applications.In this work,we systematically investigate the HPOR/HPRR mechanisms on low-index Pt surfaces,specifically Pt(111),Pt(100)and Pt(110),through density functional theory(DFT)calculations combined with the computational hydrogen electrode(CHE)model.For HPOR,all the low-index Pt surfaces exhibit a unified potential-determining step(PDS)involving the electrochemical oxidation of hydroperoxyl intermediates(HOO*).The binding free energy of HOO*(Δ_(GHOO*))emerges as an activity descriptor,with Pt(110)exhibiting the highest HPOR activity.The HPRR mechanism follows a chem-electrochemical(C-EC)pathway.The rate-determining step(RDS)of HPRR is either the cleavage of the HO-OH bond(chemical)or the reduction of HO(electrochemical),depending on their respective activation energies.These activation energies are functions of the HO*binding free energy,Δ_(GHO*),establishingΔ_(GHO*)as the descriptor for HPRR activity prediction.Pt(111)and Pt(100)are identified as the most active HPRR catalysts among the studied metal surfaces,although they still experience a significant overpotential.The scaling relationship betweenΔ_(GHOO*)andΔ_(GHO*)reveals a thermodynamic coupling of HPOR and HPRR,explaining their occurrence on Pt surfaces.These findings provide important insights and activity descriptors for both HPOR and HPRR,providing valuable guidance for the design of electrocatalysts in H_(2)O_(2)-related energy applications and fuel cells.展开更多
This study experimentally investigates the influence of surfacewettability on the frosting characteristics of three types of corrugated structures(Types A,B,and C)under controlled low-temperature conditions.The experi...This study experimentally investigates the influence of surfacewettability on the frosting characteristics of three types of corrugated structures(Types A,B,and C)under controlled low-temperature conditions.The experiments were conducted in a constant-temperature bath at a cold surface temperature of–5℃,relative humidity of 90%,and ambient air temperature of 10℃.The results reveal that the variation trends of frost morphology,frost mass,and frost layer thickness are generally consistent across surfaces with different wettability.Among the tested surfaces,frost crystal formation and complete surface coverage occurred latest on the superhydrophobic surface(CA=153.9–165.8℃),next on the bare aluminumsurface(75.3–83.2℃),and earliest on the hydrophilic surface(5.3–7.5℃).At the same frosting duration,the superhydrophobic surface exhibited a sparse and fluffy frost layer,the bare aluminum surface formed a rough and dense frost,while the hydrophilic surface developed a fine and compact frost layer.The amount of frost formation decreased in the order of hydrophilic>bare aluminum>superhydrophobic,indicating that the superhydrophobic surface provides the most significant anti-frosting effect during the initial stages of frost formation.For instance,on the Type A corrugated structure,after 15 min of frosting,the frost mass on the superhydrophobic surface was 38.78%and 68.45%lower than those on the bare aluminum and hydrophilic surfaces,respectively.After 30 min,these differences were 4.99%and 25.26%,respectively.Overall,the superhydrophobic surface exhibited the smallest frost mass and frost layer thickness,demonstrating superior anti-frosting performance compared with the other surface types.展开更多
Used extensively in the aerospace industry,the superalloy Inconel 718 is deemed hard to cut because of its rapid work hardening,low thermal conductivity,and excessive shear strength.Proposed here is patterning Inconel...Used extensively in the aerospace industry,the superalloy Inconel 718 is deemed hard to cut because of its rapid work hardening,low thermal conductivity,and excessive shear strength.Proposed here is patterning Inconel 718 with micro-dimples using electrochemical machining and electrical discharge machining prior to conventional cutting.How this micro-dimple patterning influences the machinability of Inconel 718 is analyzed via orthogonal cutting experiments,and with the optimal parameters,the cutting temperature is lowered by 45.5%and the cutting forces are reduced significantly,i.e.,the tangential cutting force and the thrust force are reduced by 61.1% and 47.1%,respectively.The predictions of finite-element simulations agree with experimental observations,and it is concluded that dimpled Inconel 718 offers significantly improved tool wear and surface integrity.展开更多
Surface texturing has been applied to improving the tribological performance of mechanical components for many years. Currently, the researches simulate the film pressure distribution of textured rough surfaces on the...Surface texturing has been applied to improving the tribological performance of mechanical components for many years. Currently, the researches simulate the film pressure distribution of textured rough surfaces on the basis of the average flow model, and however the influence of roughness on the film pressure distribution could not be precisely expressed. Therefore, in order to study the hydrodynamic lubrication of the rough textured surfaces, sinusoidal waves are employed to characterize untextured surfaces. A deterministic model for hydrodynamic lubrication of microdimple textured rough surfaces is developed to predict the distribution of hydrodynamic pressure. By supplementing with the JFO cavitation boundary, the load carrying capacity of the film produced by micro-dimples and roughness is obtained. And the geometric parameters of textured rough surface are optimized to obtain the maximum hydrodynamic lubrication by specifying an optimization goal of the load carrying capacity. The effect of roughness on the hydrodynamic pressure of surface texture is significant and the load carrying capacity decreases with the increase of the roughness ratio because the roughness greatly suppresses the hydrodynamic effect of dimples. It shows that the roughness ratio of surface may be as small as possible to suppress the effect of hydrodynamic lubrication. Additionally,there are the optimum values of the micro-dimple depth and area density to maximize the load carrying capacity for any given value of the roughness ratio. The proposed approach is capable of accurately reflects the influence of roughness on the hydrodynamic pressure, and developed a deterministic model to investigate the hydrodynamic lubrication of textured surfaces.展开更多
The application of surface textures has been employed to improve the tribological performance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-d...The application of surface textures has been employed to improve the tribological performance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-dimple arrays, but the fabrication of such arrays on cylindrical inner surfaces remains a challenge. In this study, a dry-film photoresist is used as a mask during through-mask electrochemical micromachining to successfully prepare micro-dimple arrays with dimples 94 lm in diameter and 22.7 lm deep on cylindrical inner surfaces, with a machining time of 9 s and an applied voltage of 8 V. The versatility of this method is demonstrated, as are its potential low cost and high efficiency. It is also shown that for a fixed dimple depth, a smaller dimple diameter can be obtained using a combination of lower current density and longer machining time in a passivating sodium nitrate electrolyte.展开更多
As one of the lightest engineering materials,magnesium(Mg)alloy possesses excellent mechanical performance,meeting the needs of versatile engineering fields and holding the potential to address cutting-edge issues in ...As one of the lightest engineering materials,magnesium(Mg)alloy possesses excellent mechanical performance,meeting the needs of versatile engineering fields and holding the potential to address cutting-edge issues in aerospace,electronics,biomedicine.The design of superhydrophobic(SHB)surfaces with micro and nanostructures can endow Mg alloys with multiple functionalities,such as self-cleaning,self-healing,antibacterial,and corrosion resistance.Over the past decade,researchers have drawn inspiration from nature to implement biomimetic design principles,resulting in the rapid development of micro/nanostructured SHB surfaces on Mg alloys,which hold great promise for biomedical applications.This review comprehensively introduces the biomimetic design principles of micro/nanostructured SHB surfaces on Mg alloys,discusses the challenges along with advantages and disadvantages of current preparation methods,and explores the future perspectives for preparing these SHB surfaces,providing strategies to enhance their performance in biomedical applications.展开更多
In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance ...In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.展开更多
As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal...As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions.Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces.However,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials.From the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear surfaces.The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized.Starting from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed.It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.展开更多
The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the in...The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.展开更多
The multidimensional dynamic manipulation of spoof surface waves(SSWs)is crucial for terahertz(THz)on-chip integrated systems.However,existing metasurfaces are limited to passive,single-function wavefront shaping of S...The multidimensional dynamic manipulation of spoof surface waves(SSWs)is crucial for terahertz(THz)on-chip integrated systems.However,existing metasurfaces are limited to passive,single-function wavefront shaping of SSWs,which precludes on-chip multidimensional dynamic control and hinders their practical applications.To address these limitations,we propose a polarization multiplexing THz graphene metasurface.展开更多
We deal with the properties of incompressible and pairwise incompressible surfaces in knot complements through the application of relevant properties of almost simple topological graphs.We analyze the topological grap...We deal with the properties of incompressible and pairwise incompressible surfaces in knot complements through the application of relevant properties of almost simple topological graphs.We analyze the topological graph invariants associated with surfaces embedded in the complements of alternating and almost alternating knots.Specifically,we prove that the characteristic numbers of these graphs remain invariant under two fundamental transformations(R-move and S^(2)-move).Leveraging the interplay between characteristic numbers and Euler characteristics,and further connecting Euler characteristics to surface genus,we derive novel results regarding the genus of incompressible pairwise incompressible surfaces.Additionally,we establish a discriminant criterion to determine when such surfaces in knot complements admit genus zero.展开更多
In this paper,we construct an efficient decoupling-type strategy for solving the Allen-Cahn equation on curved surfaces.It is based on an FEM-EIEQ(Finite Element Method and explicit-Invariant Energy Quadratization)ful...In this paper,we construct an efficient decoupling-type strategy for solving the Allen-Cahn equation on curved surfaces.It is based on an FEM-EIEQ(Finite Element Method and explicit-Invariant Energy Quadratization)fully discrete scheme with unconditional energy stability.Spatially the FEM is adopted,using a triangular mesh discretization strategy that can be adapted to complex regions.Temporally,the EIEQ approach is considered,which not only linearizes the nonlinear potential but also gives a new variable that we combine with the nonlocal splitting method to achieve the fully decoupled computation.The strategy can successfully transform the Allen-Cahn system into some completely independent algebraic equations and linear elliptic equations with constant coefficients,we only need to solve these simple equations at each time step.Moreover,we conducted some numerical experiments to demonstrate the effectiveness of the strategy.展开更多
In recent years,the study of chalcopyrite and pyrite flotation surfaces using computational chemistry methods has made significant progress.However,current computational methods are limited by the small size of their ...In recent years,the study of chalcopyrite and pyrite flotation surfaces using computational chemistry methods has made significant progress.However,current computational methods are limited by the small size of their systems and insufficient consideration of hydration and temperature effects,making it difficult to fully replicate the real flotation environment of chalcopyrite and pyrite.In this study,we employed the self-consistent charge density functional tight-binding(SCC-DFTB)parameterization method to develop a parameter set,CuFeOrg,which includes the interactions between Cu-Fe-C-H-O-N-S-P-Zn elements,to investigate the surface interactions in large-scale flotation systems of chalcopyrite and pyrite.The results of bulk modulus,atomic displacement,band structure,surface relaxation,surface Mulliken charge distribution,and adsorption tests of typical flotation reagents on mineral surfaces demonstrate that CuFeOrg achieves DFT-level accuracy while significantly outperforming DFT in computational efficiency.By constructing large-scale hydration systems of mineral surfaces,as well as large-scale systems incorporating the combined interactions of mineral surfaces,flotation reagents,and hydration,we more realistically reproduce the actual flotation environment.Furthermore,the dynamic analysis results are consistent with mineral surface contact angle experiments.Additionally,CuFeOrg lays the foundation for future studies of more complex and diverse chalcopyrite and pyrite flotation surface systems.展开更多
Dear Editor,As the Internet of things(IoT)and autonomous driving continue to evolve,positioning technology faces increasing demands for higher accuracy and reliability.Traditional positioning methods often struggle in...Dear Editor,As the Internet of things(IoT)and autonomous driving continue to evolve,positioning technology faces increasing demands for higher accuracy and reliability.Traditional positioning methods often struggle in complex signal environments with multipath interference and non-line-of-sight(NLOS)conditions.Reconfigurable intelligent surfaces(RIS),an innovative technology that can flexibly control signal propagation,offer new possibilities for positioning systems.展开更多
Functional materials synthesized from bio-based building blocks are fascinating and challenging in the fields of chemistry and materials science.Herein,we present a versatile strategy for synthesizing bio-based stimul...Functional materials synthesized from bio-based building blocks are fascinating and challenging in the fields of chemistry and materials science.Herein,we present a versatile strategy for synthesizing bio-based stimulus-responsive polymers derived from itaconic acid(IA).Bearing an azobenzene-containing side chain,the IA-based epoxy polymer exhibited both photoresponsiveness and acid/base-stimulus responsiveness.With controllable manipulation of the stress field of the wrinkling IA-polymer film via the stress relaxation effect resulting from the reversible cis-trans isomerization of the azobenzene moieties or solvent-induced swelling of the film,various tailor-made patterned wrinkling surfaces were conveniently fabricated.More importantly,the azobenzene protonation/deprotonation yields a reversible visual color transformation between pale yellow and purple in the film,which allows these IA-based polymer-coated surfaces to be utilized as rewritable information storage media.Various elegant pattern information can be acid-printed and base-erased(within 10 s)for multiple cycles and legible for over one day under laboratory conditions.Notably,the aforementioned dual-stimulus responsiveness of the IA-based polymer film enables its surface to be applied in information encryption.This study not only paves a new avenue for the convenient fabrication of stimulus-responsive surfaces but also sheds light on the development of functional polymers through green engineering.展开更多
The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable ad...The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable adsorption configuration of MgP on the NaCl/Au(111)heterosurfaces was found to be at the Cl-top site with a 20°angle between the[110]lattice direction of NaCl and the Mg–N bond of the molecule.Compared with MgP molecule adsorbed on bare Au(111),the inclusion of NaCl lay-ers can lead to a significant decrease in the adsorption energy of the MgP molecule.The exis-tence of NaCl layers also reduced the charge transfer between the molecule and the surface.For heterosurfaces with two or three monolayers of NaCl,the charge transfer was almost com-pletely suppressed.The obtained partial density of states(PDOS)showed that hybridization between the electronic structures of the adsorbed MgP molecule and the metal surface can be significantly suppressed when NaCl layers were added.For the heterosurface with three lay-ers of NaCl,the PDOS around the Fermi level was almost identical with that of the free molecule,suggesting the electronic structure of the MgP molecule was nicely preserved.Influ-ence of the NaCl layers on the electronic structure of the MgP molecule was mainly found for molecular orbitals(MOs)away from the Fermi level as a result of the large band gap of the NaCl layers.展开更多
On-demand droplet manipulation plays a critical role in microfluidics,bio/chemical detection and microreactions.Acoustic droplet manipulation has emerged as a promising technique due to its non-contact nature,biocompa...On-demand droplet manipulation plays a critical role in microfluidics,bio/chemical detection and microreactions.Acoustic droplet manipulation has emerged as a promising technique due to its non-contact nature,biocompatibility and precision,circumventing the complexities associated with other methods requiring surface or droplet pretreatment.Despite their promise,existing methods for acoustic droplet manipulation often involve complex hardware setups and difficulty for controlling individual droplet amidst multiple ones.Here we fabricate simple yet effective acoustic tweezers for in-surface and out-of-surface droplet manipulation.It is found that droplets can be transported on the superhydrophobic surfaces when the acoustic radiation force surpasses the friction force.Using a two-axis acoustic tweezer,droplets can be maneuvered along arbitrarily programmed paths on the surfaces.By introducing multiple labyrinthine structures on the superhydrophobic surface,individual droplet manipulation is realized by constraining the unselected droplets in the labyrinthine structures.In addition,a three-axis acoustic tweezer is developed for manipulating droplets in three-dimensional space.Potential applications of the acoustic tweezers for micro-reaction,bio-assay and chemical analysis are also demonstrated.展开更多
Biomass-derived carbon materials are favored for their abundance and sustainability,and ease of preparation and modification.By surface activation and modification they can have a good electrical conductivity,excellen...Biomass-derived carbon materials are favored for their abundance and sustainability,and ease of preparation and modification.By surface activation and modification they can have a good electrical conductivity,excellent catalytic activity,a remarkable adsorption capacity,and different interfacial physicochemical functionalities.Surface-modified biochars have found wide applications in energy storage,environmental remediation,and catalysis.However,achieving precise and controllable modification of their active sites remains a challenge.Recent advances and future prospects for controlling their surface morphology,defect engineering,and surface coating strategies,with particular attention to their means of fabrication,are reviewed.展开更多
This review systematically summarizes recent advancements in the design of antibacterial hydrogels and the surface-related factors influencing microbial adhesion to polymeric materials.Hydrogels,characterized by their...This review systematically summarizes recent advancements in the design of antibacterial hydrogels and the surface-related factors influencing microbial adhesion to polymeric materials.Hydrogels,characterized by their three-dimensional porous architecture and ultra-high water content,serve as ideal platforms for incorporating antibacterial agents(e.g.,metal ions,natural polymers)through physical/chemical interactions,enabling sustained release and enhanced antibacterial efficacy.For traditional polymers,surface properties(e.g.,roughness,charge,superhydrophobicity,free energy,nanoforce gradients)play critical roles in microbial adhesion.Modifying the surface properties of polymers through surface treatment can regulate antibacterial performance.In particular,by referencing the micro/nanostructures found on natural surfaces such as lotus leaves and cicada wings,antibacterial surfaces with multiple superior functions can be fabricated.Collectively,these findings provide a theoretical basis for the rational design of multifunctional antibacterial materials,offering material-based solutions to address complex infection scenarios and advance infection management strategies.展开更多
As a popular approach to producing atmospheric pressure non-thermal plasma,dielectric barrier discharge(DBD)has been extensively used in various application fields.In this paper,DBD with wavy dielectric layers is nume...As a popular approach to producing atmospheric pressure non-thermal plasma,dielectric barrier discharge(DBD)has been extensively used in various application fields.In this paper,DBD with wavy dielectric layers is numerically simulated in atmospheric pressure helium mixed with trace nitrogen based on a fluid model.With varying relative position(phase difference(Δφ))of the wavy surfaces,there is a positive discharge and a negative discharge per voltage cycle,each of which consists of a pulse stage and a hump stage.For the pulse stage,maximal current increases with increasingΔφ.Results show that DBD with the wavy surfaces appears as discrete micro-discharges(MDs),which are self-organized to different patterns with varyingΔφ.The MDs are vertical and uniformly-spaced withΔφ=0,which are self-organized in pairs withΔφ=π/4.These MD pairs are merged into some bright wide MDs withΔφ=π/2.In addition,narrow MDs appear between tilted wide MDs withΔφ=3π/4.WithΔφ=π,the pattern is composed of wide and narrow MDs,which are vertical and appear alternately.To elucidate the formation mechanism of the patterns with differentΔφ,temporal evolutions of electron density and electric field are investigated for the positive discharge.Moreover,surface charge on the wavy dielectric layers has also been compared with differentΔφ.展开更多
基金Supported by the Shanxi Province Grant(202203021212007,2023SHB003).
文摘Hydrogen peroxide(H_(2)O_(2))oxidation and reduction reactions(HPOR/HPRR)are pivotal in various innovative electrochemical energy conversion devices.A comprehensive understanding of these mechanisms is critical for catalyst design and performance improvement in these applications.In this work,we systematically investigate the HPOR/HPRR mechanisms on low-index Pt surfaces,specifically Pt(111),Pt(100)and Pt(110),through density functional theory(DFT)calculations combined with the computational hydrogen electrode(CHE)model.For HPOR,all the low-index Pt surfaces exhibit a unified potential-determining step(PDS)involving the electrochemical oxidation of hydroperoxyl intermediates(HOO*).The binding free energy of HOO*(Δ_(GHOO*))emerges as an activity descriptor,with Pt(110)exhibiting the highest HPOR activity.The HPRR mechanism follows a chem-electrochemical(C-EC)pathway.The rate-determining step(RDS)of HPRR is either the cleavage of the HO-OH bond(chemical)or the reduction of HO(electrochemical),depending on their respective activation energies.These activation energies are functions of the HO*binding free energy,Δ_(GHO*),establishingΔ_(GHO*)as the descriptor for HPRR activity prediction.Pt(111)and Pt(100)are identified as the most active HPRR catalysts among the studied metal surfaces,although they still experience a significant overpotential.The scaling relationship betweenΔ_(GHOO*)andΔ_(GHO*)reveals a thermodynamic coupling of HPOR and HPRR,explaining their occurrence on Pt surfaces.These findings provide important insights and activity descriptors for both HPOR and HPRR,providing valuable guidance for the design of electrocatalysts in H_(2)O_(2)-related energy applications and fuel cells.
基金supported by the Science and Technology Research Project of Henan Province(No.232102241014)the Key scientific research project of Henan Province Colleges and Universities(No.22A470002)Doctoral Fund Project of Henan Polytechnic University(No.B2021-37).
文摘This study experimentally investigates the influence of surfacewettability on the frosting characteristics of three types of corrugated structures(Types A,B,and C)under controlled low-temperature conditions.The experiments were conducted in a constant-temperature bath at a cold surface temperature of–5℃,relative humidity of 90%,and ambient air temperature of 10℃.The results reveal that the variation trends of frost morphology,frost mass,and frost layer thickness are generally consistent across surfaces with different wettability.Among the tested surfaces,frost crystal formation and complete surface coverage occurred latest on the superhydrophobic surface(CA=153.9–165.8℃),next on the bare aluminumsurface(75.3–83.2℃),and earliest on the hydrophilic surface(5.3–7.5℃).At the same frosting duration,the superhydrophobic surface exhibited a sparse and fluffy frost layer,the bare aluminum surface formed a rough and dense frost,while the hydrophilic surface developed a fine and compact frost layer.The amount of frost formation decreased in the order of hydrophilic>bare aluminum>superhydrophobic,indicating that the superhydrophobic surface provides the most significant anti-frosting effect during the initial stages of frost formation.For instance,on the Type A corrugated structure,after 15 min of frosting,the frost mass on the superhydrophobic surface was 38.78%and 68.45%lower than those on the bare aluminum and hydrophilic surfaces,respectively.After 30 min,these differences were 4.99%and 25.26%,respectively.Overall,the superhydrophobic surface exhibited the smallest frost mass and frost layer thickness,demonstrating superior anti-frosting performance compared with the other surface types.
基金This work was supported financially by Portescap India Pvt.Ltd. via its CSR fund.
文摘Used extensively in the aerospace industry,the superalloy Inconel 718 is deemed hard to cut because of its rapid work hardening,low thermal conductivity,and excessive shear strength.Proposed here is patterning Inconel 718 with micro-dimples using electrochemical machining and electrical discharge machining prior to conventional cutting.How this micro-dimple patterning influences the machinability of Inconel 718 is analyzed via orthogonal cutting experiments,and with the optimal parameters,the cutting temperature is lowered by 45.5%and the cutting forces are reduced significantly,i.e.,the tangential cutting force and the thrust force are reduced by 61.1% and 47.1%,respectively.The predictions of finite-element simulations agree with experimental observations,and it is concluded that dimpled Inconel 718 offers significantly improved tool wear and surface integrity.
基金Supported by National Natural Science Foundation of China(Grant Nos.51305168,51375211,51375213)Jiangsu Provincial Natural Science Foundation of China(Grant No.BK20130524)Research Foundation for Advanced Talents of Jiangsu University,China(Grant No.13JDG090)
文摘Surface texturing has been applied to improving the tribological performance of mechanical components for many years. Currently, the researches simulate the film pressure distribution of textured rough surfaces on the basis of the average flow model, and however the influence of roughness on the film pressure distribution could not be precisely expressed. Therefore, in order to study the hydrodynamic lubrication of the rough textured surfaces, sinusoidal waves are employed to characterize untextured surfaces. A deterministic model for hydrodynamic lubrication of microdimple textured rough surfaces is developed to predict the distribution of hydrodynamic pressure. By supplementing with the JFO cavitation boundary, the load carrying capacity of the film produced by micro-dimples and roughness is obtained. And the geometric parameters of textured rough surface are optimized to obtain the maximum hydrodynamic lubrication by specifying an optimization goal of the load carrying capacity. The effect of roughness on the hydrodynamic pressure of surface texture is significant and the load carrying capacity decreases with the increase of the roughness ratio because the roughness greatly suppresses the hydrodynamic effect of dimples. It shows that the roughness ratio of surface may be as small as possible to suppress the effect of hydrodynamic lubrication. Additionally,there are the optimum values of the micro-dimple depth and area density to maximize the load carrying capacity for any given value of the roughness ratio. The proposed approach is capable of accurately reflects the influence of roughness on the hydrodynamic pressure, and developed a deterministic model to investigate the hydrodynamic lubrication of textured surfaces.
基金supported by the Joint Funds of the National Natural Science Foundation of China and Guangdong Province(No.U1134003)
文摘The application of surface textures has been employed to improve the tribological performance of various mechanical components. Various techniques have been used for the application of surface textures such as micro-dimple arrays, but the fabrication of such arrays on cylindrical inner surfaces remains a challenge. In this study, a dry-film photoresist is used as a mask during through-mask electrochemical micromachining to successfully prepare micro-dimple arrays with dimples 94 lm in diameter and 22.7 lm deep on cylindrical inner surfaces, with a machining time of 9 s and an applied voltage of 8 V. The versatility of this method is demonstrated, as are its potential low cost and high efficiency. It is also shown that for a fixed dimple depth, a smaller dimple diameter can be obtained using a combination of lower current density and longer machining time in a passivating sodium nitrate electrolyte.
基金supported by the National Natural Science Found for Distinguished Young Scholars(52225101)the Fundamental Research Funds for the Central Universities(WUT:104972024RSCbs0018 and 2023CDJYXTD-002)+1 种基金the Natural Science Foundation of Chongqing(CSTB2023NSCQ-MSX0527)the Chongqing Academician Special Fund(2022YSZXJCX0014CSTB).
文摘As one of the lightest engineering materials,magnesium(Mg)alloy possesses excellent mechanical performance,meeting the needs of versatile engineering fields and holding the potential to address cutting-edge issues in aerospace,electronics,biomedicine.The design of superhydrophobic(SHB)surfaces with micro and nanostructures can endow Mg alloys with multiple functionalities,such as self-cleaning,self-healing,antibacterial,and corrosion resistance.Over the past decade,researchers have drawn inspiration from nature to implement biomimetic design principles,resulting in the rapid development of micro/nanostructured SHB surfaces on Mg alloys,which hold great promise for biomedical applications.This review comprehensively introduces the biomimetic design principles of micro/nanostructured SHB surfaces on Mg alloys,discusses the challenges along with advantages and disadvantages of current preparation methods,and explores the future perspectives for preparing these SHB surfaces,providing strategies to enhance their performance in biomedical applications.
基金supported by the National Natural Science Foundation of China(Grant No.12272369)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0620101).
文摘In recent decades,capacitive pressure sensors(CPSs)with high sensitivity have demonstrated significant potential in applications such as medical monitoring,artificial intelligence,and soft robotics.Efforts to enhance this sensitivity have predominantly focused on material design and structural optimization,with surface microstructures such as wrinkles,pyramids,and micro-pillars proving effective.Although finite element modeling(FEM)has guided enhancements in CPS sensitivity across various surface designs,a theoretical understanding of sensitivity improvements remains underexplored.This paper employs sinusoidal wavy surfaces as a representative model to analytically elucidate the underlying mechanisms of sensitivity enhancement through contact mechanics.These theoretical insights are corroborated by FEM and experimental validations.Our findings underscore that optimizing material properties,such as Young’s modulus and relative permittivity,alongside adjustments in surface roughness and substrate thickness,can significantly elevate the sensitivity.The optimal performance is achieved when the amplitude-to-wavelength ratio(H/)is about 0.2.These results offer critical insights for designing ultrasensitive CPS devices,paving the way for advancements in sensor technology.
基金financially supported by the National Key R&D Program of China(No.2022YFE0121300)the National Natural Science Foundation of China(No.52374376)the Introduction Plan for High-end Foreign Experts(No.G2023105001L)。
文摘As a mathematical analysis method,fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties.Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions.Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces.However,fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials.From the perspective of two-dimensional planes and three-dimensional curved surfaces,this paper reviews the current research status of the fractal analysis of metal precipitate interfaces,metal grain boundary interfaces,metal-deposited film surfaces,metal fracture surfaces,metal machined surfaces,and metal wear surfaces.The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized.Starting from three perspectives of fractal analysis,namely,research scope,image acquisition methods,and calculation methods,this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed.It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.
基金This work are supported by the Natural Science Foundation of China General Program(Grant No.12272157)the Natural Science Foundation of China Major Program(Grant No.12327901)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2023-ey05)the 111 Project(Grant No.B14044).
文摘The contact problem of deformed rough surfaces exists widely in complex engineering structures.How to reveal the influence mechanism of surface deformation on the contact properties is a key issue in evaluating the interface performances of the engineering structures.In this paper,a contact model is established,which is suitable for tensile and bending deformed contact surfaces.Four contact forms of asperities are proposed,and their distribution characteristics are analyzed.This model reveals the mechanism of friction generation from the perspective of the force balance of asperity.The results show the contact behaviors of the deformed contact surface are significantly different from that of the plane contact,which is mainly reflected in the change in the number of contact asperities and the real contact area.This study suggests that the real contact area of the interface can be altered by applying tensile and bending strains,thereby regulating its contact mechanics and conductive behavior.
基金National Key Research and Development Program of China(2024YFE0108300,2023YFB3210400)Science and Technology Major Projects of Guangxi(Gui Ke AA24263032,Gui Ke AA21077015)+3 种基金Open Fund Project of Key Laboratory of Integrated Circuits and Microsystems in Guangxi Universities(ICM-25-02)National Natural Science Foundation of China(62075052,6227419)Science Foundation of the National Key Laboratory of Science and Technology on Advanced Composites in Special Environments(JCKYS2020603C009,6142905212711)Project of Innovative and Entrepreneurship Training Program for College Students in Heilongjiang Province(201810214105)。
文摘The multidimensional dynamic manipulation of spoof surface waves(SSWs)is crucial for terahertz(THz)on-chip integrated systems.However,existing metasurfaces are limited to passive,single-function wavefront shaping of SSWs,which precludes on-chip multidimensional dynamic control and hinders their practical applications.To address these limitations,we propose a polarization multiplexing THz graphene metasurface.
基金Supported by the National Natural Science Foundation of China(Grant No.12026411)。
文摘We deal with the properties of incompressible and pairwise incompressible surfaces in knot complements through the application of relevant properties of almost simple topological graphs.We analyze the topological graph invariants associated with surfaces embedded in the complements of alternating and almost alternating knots.Specifically,we prove that the characteristic numbers of these graphs remain invariant under two fundamental transformations(R-move and S^(2)-move).Leveraging the interplay between characteristic numbers and Euler characteristics,and further connecting Euler characteristics to surface genus,we derive novel results regarding the genus of incompressible pairwise incompressible surfaces.Additionally,we establish a discriminant criterion to determine when such surfaces in knot complements admit genus zero.
基金Supported by the National Natural Science Foundation of China(Grant No.12171147).
文摘In this paper,we construct an efficient decoupling-type strategy for solving the Allen-Cahn equation on curved surfaces.It is based on an FEM-EIEQ(Finite Element Method and explicit-Invariant Energy Quadratization)fully discrete scheme with unconditional energy stability.Spatially the FEM is adopted,using a triangular mesh discretization strategy that can be adapted to complex regions.Temporally,the EIEQ approach is considered,which not only linearizes the nonlinear potential but also gives a new variable that we combine with the nonlocal splitting method to achieve the fully decoupled computation.The strategy can successfully transform the Allen-Cahn system into some completely independent algebraic equations and linear elliptic equations with constant coefficients,we only need to solve these simple equations at each time step.Moreover,we conducted some numerical experiments to demonstrate the effectiveness of the strategy.
基金supported by the National Natural Science Foundation of China(No.52374264)the National Key Technologies Research and Development Program of China(No.2024YFC2909600)the Major Science and Technology Projects in Yunnan Province(No.202402AB080010).
文摘In recent years,the study of chalcopyrite and pyrite flotation surfaces using computational chemistry methods has made significant progress.However,current computational methods are limited by the small size of their systems and insufficient consideration of hydration and temperature effects,making it difficult to fully replicate the real flotation environment of chalcopyrite and pyrite.In this study,we employed the self-consistent charge density functional tight-binding(SCC-DFTB)parameterization method to develop a parameter set,CuFeOrg,which includes the interactions between Cu-Fe-C-H-O-N-S-P-Zn elements,to investigate the surface interactions in large-scale flotation systems of chalcopyrite and pyrite.The results of bulk modulus,atomic displacement,band structure,surface relaxation,surface Mulliken charge distribution,and adsorption tests of typical flotation reagents on mineral surfaces demonstrate that CuFeOrg achieves DFT-level accuracy while significantly outperforming DFT in computational efficiency.By constructing large-scale hydration systems of mineral surfaces,as well as large-scale systems incorporating the combined interactions of mineral surfaces,flotation reagents,and hydration,we more realistically reproduce the actual flotation environment.Furthermore,the dynamic analysis results are consistent with mineral surface contact angle experiments.Additionally,CuFeOrg lays the foundation for future studies of more complex and diverse chalcopyrite and pyrite flotation surface systems.
基金supported by the Open Fund Project of Key Laboratory of Ocean Observation Technology,MNR(2023klootA01).
文摘Dear Editor,As the Internet of things(IoT)and autonomous driving continue to evolve,positioning technology faces increasing demands for higher accuracy and reliability.Traditional positioning methods often struggle in complex signal environments with multipath interference and non-line-of-sight(NLOS)conditions.Reconfigurable intelligent surfaces(RIS),an innovative technology that can flexibly control signal propagation,offer new possibilities for positioning systems.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2022MB034)。
文摘Functional materials synthesized from bio-based building blocks are fascinating and challenging in the fields of chemistry and materials science.Herein,we present a versatile strategy for synthesizing bio-based stimulus-responsive polymers derived from itaconic acid(IA).Bearing an azobenzene-containing side chain,the IA-based epoxy polymer exhibited both photoresponsiveness and acid/base-stimulus responsiveness.With controllable manipulation of the stress field of the wrinkling IA-polymer film via the stress relaxation effect resulting from the reversible cis-trans isomerization of the azobenzene moieties or solvent-induced swelling of the film,various tailor-made patterned wrinkling surfaces were conveniently fabricated.More importantly,the azobenzene protonation/deprotonation yields a reversible visual color transformation between pale yellow and purple in the film,which allows these IA-based polymer-coated surfaces to be utilized as rewritable information storage media.Various elegant pattern information can be acid-printed and base-erased(within 10 s)for multiple cycles and legible for over one day under laboratory conditions.Notably,the aforementioned dual-stimulus responsiveness of the IA-based polymer film enables its surface to be applied in information encryption.This study not only paves a new avenue for the convenient fabrication of stimulus-responsive surfaces but also sheds light on the development of functional polymers through green engineering.
基金supported by the National Natural Science Foundation of China(No.22373084,No.62201494)Hebei Natural Science Foundation(B2022203007)the Cultivation Project for Basic Research and Innovation of Yanshan University(2024LGZD002).
文摘The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable adsorption configuration of MgP on the NaCl/Au(111)heterosurfaces was found to be at the Cl-top site with a 20°angle between the[110]lattice direction of NaCl and the Mg–N bond of the molecule.Compared with MgP molecule adsorbed on bare Au(111),the inclusion of NaCl lay-ers can lead to a significant decrease in the adsorption energy of the MgP molecule.The exis-tence of NaCl layers also reduced the charge transfer between the molecule and the surface.For heterosurfaces with two or three monolayers of NaCl,the charge transfer was almost com-pletely suppressed.The obtained partial density of states(PDOS)showed that hybridization between the electronic structures of the adsorbed MgP molecule and the metal surface can be significantly suppressed when NaCl layers were added.For the heterosurface with three lay-ers of NaCl,the PDOS around the Fermi level was almost identical with that of the free molecule,suggesting the electronic structure of the MgP molecule was nicely preserved.Influ-ence of the NaCl layers on the electronic structure of the MgP molecule was mainly found for molecular orbitals(MOs)away from the Fermi level as a result of the large band gap of the NaCl layers.
基金supported by National Natural Science Foundation of China(Nos.12072381,22072185,21805315)Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011812)Science and Technology Innovation Project of Guangzhou(No.202102020263).
文摘On-demand droplet manipulation plays a critical role in microfluidics,bio/chemical detection and microreactions.Acoustic droplet manipulation has emerged as a promising technique due to its non-contact nature,biocompatibility and precision,circumventing the complexities associated with other methods requiring surface or droplet pretreatment.Despite their promise,existing methods for acoustic droplet manipulation often involve complex hardware setups and difficulty for controlling individual droplet amidst multiple ones.Here we fabricate simple yet effective acoustic tweezers for in-surface and out-of-surface droplet manipulation.It is found that droplets can be transported on the superhydrophobic surfaces when the acoustic radiation force surpasses the friction force.Using a two-axis acoustic tweezer,droplets can be maneuvered along arbitrarily programmed paths on the surfaces.By introducing multiple labyrinthine structures on the superhydrophobic surface,individual droplet manipulation is realized by constraining the unselected droplets in the labyrinthine structures.In addition,a three-axis acoustic tweezer is developed for manipulating droplets in three-dimensional space.Potential applications of the acoustic tweezers for micro-reaction,bio-assay and chemical analysis are also demonstrated.
文摘Biomass-derived carbon materials are favored for their abundance and sustainability,and ease of preparation and modification.By surface activation and modification they can have a good electrical conductivity,excellent catalytic activity,a remarkable adsorption capacity,and different interfacial physicochemical functionalities.Surface-modified biochars have found wide applications in energy storage,environmental remediation,and catalysis.However,achieving precise and controllable modification of their active sites remains a challenge.Recent advances and future prospects for controlling their surface morphology,defect engineering,and surface coating strategies,with particular attention to their means of fabrication,are reviewed.
基金supported by Science and Technology Plan of Luzhou under Grant No.2024JYJ039.
文摘This review systematically summarizes recent advancements in the design of antibacterial hydrogels and the surface-related factors influencing microbial adhesion to polymeric materials.Hydrogels,characterized by their three-dimensional porous architecture and ultra-high water content,serve as ideal platforms for incorporating antibacterial agents(e.g.,metal ions,natural polymers)through physical/chemical interactions,enabling sustained release and enhanced antibacterial efficacy.For traditional polymers,surface properties(e.g.,roughness,charge,superhydrophobicity,free energy,nanoforce gradients)play critical roles in microbial adhesion.Modifying the surface properties of polymers through surface treatment can regulate antibacterial performance.In particular,by referencing the micro/nanostructures found on natural surfaces such as lotus leaves and cicada wings,antibacterial surfaces with multiple superior functions can be fabricated.Collectively,these findings provide a theoretical basis for the rational design of multifunctional antibacterial materials,offering material-based solutions to address complex infection scenarios and advance infection management strategies.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12375250,11875121,51977057,11805013)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2020201025 and A2022201036)+3 种基金the Hebei Province Optoelectronic Information Materials Laboratory Performance Subsidy Fund Project(Grant No.22567634H)the Funds for Distinguished Young Scientists of Hebei Province,China(Grant No.A2012201045)the Natural Science Interdisciplinary Research Program of Hebei University(Grant Nos.DXK201908 and DXK202011)the Post-graduate’s Innovation Fund Project of Hebei University(Grant No.HBU2022bs004)。
文摘As a popular approach to producing atmospheric pressure non-thermal plasma,dielectric barrier discharge(DBD)has been extensively used in various application fields.In this paper,DBD with wavy dielectric layers is numerically simulated in atmospheric pressure helium mixed with trace nitrogen based on a fluid model.With varying relative position(phase difference(Δφ))of the wavy surfaces,there is a positive discharge and a negative discharge per voltage cycle,each of which consists of a pulse stage and a hump stage.For the pulse stage,maximal current increases with increasingΔφ.Results show that DBD with the wavy surfaces appears as discrete micro-discharges(MDs),which are self-organized to different patterns with varyingΔφ.The MDs are vertical and uniformly-spaced withΔφ=0,which are self-organized in pairs withΔφ=π/4.These MD pairs are merged into some bright wide MDs withΔφ=π/2.In addition,narrow MDs appear between tilted wide MDs withΔφ=3π/4.WithΔφ=π,the pattern is composed of wide and narrow MDs,which are vertical and appear alternately.To elucidate the formation mechanism of the patterns with differentΔφ,temporal evolutions of electron density and electric field are investigated for the positive discharge.Moreover,surface charge on the wavy dielectric layers has also been compared with differentΔφ.
