Confined thin film wrinkling on shape memory polymer with hybrid surface morphologies

With appropriate stimuli,such as heat,humidity,or magnetic field,shape memory polymers(SMPs)can recover to their original shapes from temporary,programmed states.Using thermal responsive SMPs as substrates,we demonstrate a simple method to realize hybrid surface morphologies through confined thin film wrinkling in localized areas.The bilayer system was fabricated by depositing a layer of aluminum thin?lm on top of a SMP substrate programmed with a tensile strain.After the system was heated by a heating wire,hybrid wrinkling patterns were formed in a confined circular area around the heat source,with an inner spoke pattern and an outer ring pattern.Wrinkling patterns showed good symmetry,and the size of the wrinkling area can be tuned by controlling the heat input.This study o?ers a simple but effective approach to fabricate hybrid morphological features in micro-scale.With appropriate stimuli,such as heat,humidity,or magnetic field,shape memory polymers(SMPs)can recover to their original shapes from temporary,programmed states.Using thermal responsive SMPs as substrates,we demonstrate a simple method to realize hybrid surface morphologies through confined thin film wrinkling in localized areas.The bilayer system was fabricated by depositing a layer of aluminum thin?lm on top of a SMP substrate programmed with a tensile strain.After the system was heated by a heating wire,hybrid wrinkling patterns were formed in a confined circular area around the heat source,with an inner spoke pattern and an outer ring pattern.Wrinkling patterns showed good symmetry,and the size of the wrinkling area can be tuned by controlling the heat input.This study offers a simple but effective approach to fabricate hybrid morphological features in micro-scale.

Heat Transfer Analysis for Dropwise-Filmwise Hybrid Surface of Steam on Vertical Plate

A model is proposed to predict and evaluate the heat transfer characteristics of dropwise-filmwise hybrid surface.This is approached by modifying the original drop-size distribution,which is defined for fully dropwise condensation(DWC)and making it applicable for dropwise-filmwise condensation(DFC).The modification is achieved by simulation work to determine two parameters:the area fraction occupied by large drops f and the ratio of the maximum radius of newly formed drops to that of larger drops γ.Simulation results show a good agreement with the literature for fully DWC and provide a correlation for each parameter with respect to DWC region width in the DFC hybrid surface.The present model evaluates the heat transfer performance of DFC by utilizing these correlations.A comparison is made between the proposed model with experimental work from the literature and results show a good agreement.While changing filmwise condensation(FWC)region width significantly affects the overall heat transfer performance,utilizing smaller width to that of DWC region has the advantage over fully DWC.Furthermore,surface renewal within the hydrophobic region is controlled by adjusting the DWC region width.When the ratio of drop maximum diameter to DWC region width is unity,surface renewal is achieved by drops merging to adjacent FWC regions only.When the ratio is less than unity,surface renewal is achieved by sweeping of departing drops within the hydrophobic region and by merging.For each case,an optimum DWC region width which corresponds to the maximum DFC heat flux is defined.

Photocatalytic activity enhanced via surface hybridization

Surface hybrid inorganic semiconductors photocatalysts withπconjugated structure have recently been widely used in the field of photocatalytic environmental remediation and energy conversion.Surface hybridization is considered to be an efficient way to significantly enhance the photocatalytic activity by several times,completely inhibit photocorrosion of inorganic photocatalysts and expand the spectral response range of photocatalysts.This review provides a comprehensive overview of the surface hybridization definition,the principle of enhancing photocatalytic performance and the control factors of surface hybridization to promote photoactivity.Summarize the preparation and structural identification method of the surface hybrid photocatalyst.Special emphasis is placed on the various photocatalytic system construction of surface hybridization.The development of surface hybrid photocatalysts for pollutant degradation and energy conversion are further presented.Finally,the challenges and future development prospects of surface hybridization in photocatalysis are discussed.We hope this critical review can provide a clear picture of the state-of-the-art achievements and facilitate the applications of surface hybrid photocatalysts in environmental remediation and energy conversion.

Construction of New Surface Wave Solutions of the Modified KdV Equation

The major concern of this work is to propose new prototypes of surface hybrid waves, in particular waves propagating without sprawl or deformation on the surface of a fluid. The model considered for this purpose is the modified KdV (Korteweg-de Vries) equation. A peculiarity of the obtained solutions is that they form packages constituted by combinations of waves belonging to the two main families of well-known bright and dark solitary waves. This putting together creates competitions between the different components of the considered packages which, following the values assigned to the parameters of the considered system and in relation to those of the wave parameters, generate hybrid or multi-form structures. The direct method of resolution which made possible the obtained results is that of Bogning-Djeumen Tchaho-Kofane extended to the new implicit Bogning functions. The existence conditions of some solutions are obtained. The numerical simulations carried out with a view to testing the observable and applicable characters of the obtained solutions revealed their stabilities over a relatively long time, and at the same time, confirmed the recommended theoretical forecasts. We are convinced that the solutions proposed as part of this work will make it possible to detect, understand and explain some physical phenomena linked to fluid molecular interactions, former or new, which constantly occur on the fluid surfaces, mainly at the shallow water surface.

Tunable coupling of a hybrid plasmonic waveguide consisting of two identical dielectric cylinders and a silver film

The propagation length of surface plasmon polaritons（SPPs） is intrinsically limited by the metallic ohmic loss that is enhanced by the strongly confined electromagnetic field. In this paper, we propose a new class of hybrid plasmonic waveguides（HPWs） that can support long-range SPP propagation while keeping subwavelength optical field confinement. It is shown that the coupling between the waveguides can be well tuned by simply varying the structural parameters. Compared with conventional HPWs, a larger propagation length as well as a better optical field confinement can be simultaneously realized. The proposed structure with better optical performance can be useful for future photonic device design and optical integration research.

Surface Doping vs.Bulk Doping of Cathode Materials for Lithium-Ion Batteries:A Review

To address the capacity degradation,voltage fading,structural instability and adverse interface reactions in cathode materi-als of lithium-ion batteries(LIBs),numerous modification strategies have been developed,mainly including coating and doping.In particular,the important strategy of doping(surface doping and bulk doping)has been considered an effective strategy to modulate the crystal lattice structure of cathode materials.However,special insights into the mechanisms and effectiveness of the doping strategy,especially comparisons between surface doping and bulk doping in cathode materials,are still lacking.In this review,recent significant progress in surface doping and bulk doping strategies is demonstrated in detail by focusing on their inherent differences as well as effects on the structural stability,lithium-ion(Li-ion)diffusion and electrochemical properties of cathode materials from the following mechanistic insights:preventing the exposure of reactive Ni on the surface,stabilizing the Li slabs,mitigating the migration of transition metal(TM)ions,alleviating unde-sired structural transformations and adverse interface issues,enlarging the Li interslab spacing,forming three-dimensional(3D)Li-ion diffusion channels,and providing more active sites for the charge-transfer process.Moreover,insights into the correlation between the mechanisms of hybrid surface engineering strategies(doping and coating)and their influences on the electrochemical performance of cathode materials are provided by emphasizing the stabilization of the Li slabs,the enhancement of the surface chemical stability,and the alleviation of TM ion migration.Furthermore,the existing challenges and future perspectives in this promising field are indicated.