Directed transport of coupled Brownian motors in a two-dimensional traveling-wave potential

Considering an elastically coupled Brownian motors system in a two-dimensional traveling-wave potential, we investigate the effects of the angular frequency of the traveling wave, wavelength, coupling strength, free length of the spring, and the noise intensity on the current of the system. It is found that the traveling wave is the essential condition of the directed transport. The current is dominated by the traveling wave and varies nonmonotonically with both the angular frequency and the wavelength. At an optimal angular frequency or wavelength, the current can be optimized. The coupling strength and the free length of the spring can locally modulate the current, especially at small angular frequencies. Moreover, the current decreases rapidly with the increase of the noise intensity, indicating the interference effect of noise on the directed transport.

Direct Observation of Carrier Transportation Process in InGaAs/GaAs Multiple Quantum Wells Used for Solar Cells and Photodetectors

The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and without a p-n junction. It is observed directly in experiment that most of the photo-excited carriers in quantum wells with a p-n junction escape from quantum wells and form photoeurrent rather than relax to the ground state of the quantum wells. The photo absorption coei^cient of multiple quantum wells is also enhanced by a p-n junction. The results pave a novel way for solar cells and photodetectors making use of low-dimensional structure.

Bioinspired Stable Single‑Layer Janus Fabric with Directional Water/Moisture Transport Property for Integrated Personal Cooling Management

Extensive progress has been achieved regarding Janus fabric for directional water transport due to its excellent and feasible personal cooling management ability,which has great significance for energy conservation,pollution reduction,and human health.However,existing Janus asymmetric multilayer fabrics for directional water transport are still limited by their com-plicated syntheses and poor stabilities.Inspired by the compositionally graded architecture of leaf cuticles,we propose a single-layer Janus personal cooling management fabric(JPCMF)via a one-step electrospinning method.The JPCMF shows not only great directional bulk water transport ability but also asymmetry moisture(water vapor)transport ability with a high asymmetry factor(1.49),water vapor transmission value(18.5 kg^(-1) m-2 D-1),and water evaporation rate(0.735 g h^(-1)).Importantly,the JPCMF exhibits outstanding durability and stability thanks to a novel electrostatic adsorption-assisted self-adhesion strategy for resisting abrasion,peeling and pulling.With these characteristics,the JPCMF can achieve a 4.0°C personal cooling management effect,better than taht of cotton fabric,on wet skin.The good biocompatibility and nontoxic-ity also endow the JPCMF with the potential to be a self-pumping dressing.Our strategy should facilitate a new method for developing next-generation intelligent multifunctional fabrics.

Drop impact dynamic and directional transport on dragonfly wing surface

The ability of dragonflies to fly in the rain without being wetted by raindrops has motivated researchers to investigate the impact behavior of a drop on the superhydrophobic wings of dragonflies.This superhydrophobic surface is used as a reference for the design of directional surfaces and has attracted extensive attention owing to its wide applicability in microfluidics,self-cleaning,and other fields.In this study,the static contact angle and rebound process of a drop impacting a dragonfly wing surface are investigated experimentally,whereas the wetting pressure,Gibbs free energy,and Stokes number vs.coefficient of restitution are theoretically calculated to examine the dynamic and unidirectional transport behaviors of the drop.Results show that the initial inclination angle of the dragonfly wing is similar to the sliding angles along with the drop sliding.The water drop bounces from the bottom of the dragonfly wing to the distal position,demonstrating directional migration.The drop impacts the dragonfly wing surface,and the drop exhibits compression,recovery,and separation phases;in these three phases,the drop morphology evolves.As the Gibbs free energy and cross-sectional area evolve,the coefficient of restitution decreases as the drop continues to bounce,and the Stokes number increases.

An active bacterial anti-adhesion strategy based on directional transportation of bacterial droplets driven by triboelectric nanogenerators

An active bacterial anti-adhesion strategy based on directional transportation of bacterial droplets driven by a triboelectric nanogenerator(TENG)has not been reported to date,although passive defense approaches can prevent bacterial adhesion by regulating superwetting surfaces combined with incorporated antibacterial substances.Here a triboelectric nanogenerator driving droplet system(TNDDS)was built to drive directional transportation of bacterial droplets to be eliminated,which comprises TENG with periodical frictional Kapton film and aluminum foils and a superhydrophobic driving platform(SDP)with paralleled driving electrodes.The current generated by the TENG triboelectricity is transmitted to the paralleled driving electrodes to form an electric field driving the directional transportation of charged droplets.The critical value of the driven droplet volume on SDP is closely related to the distributed electrodes’distance and width,and the driving distance of droplets is related to the number of electrodes.More crucially,TNDDS can actively drive the charged droplets of prepared triangular silver nanoprisms(Ag NPs)forward and back to mix with and remove a tiny bacterial droplet on an open SDP or in a tiny semi-enclosed channel.Bacteria could be killed by releasing Ag+and effectively removed by TNDDS by regulating the motion direction.Generally,this approach offers a promising application for removing bacteria from material surfaces driven by TENG and opens a new avenue for bacterial anti-adhesion.

Bioinspired directional liquid transport induced by the corner effect

Many natural creatures have demonstrated unique abilities in directional liquid transport(DLT)for better adapting to the local environment,which,for a long time,have inspired the material fabrication for applications in microfluidics,self-cleaning,water collection,etc.Recently,DLTs aroused by the corner effect have been witnessed in various natural organisms,where liquid transports/spreads spontaneously along the corner structures in microgrooves,wedges or conical structures driven by micro-/nano-scaled capillary forces without external energy input.Particularly,these DLTs show advantages of ultrahigh speed,continuous proceeding,and/or external controllability.Here,we reviewed recent research advances on the bioinspired DLTs induced by the corner effect,as well as the involved mechanisms and the artificial counterpart materials with various applications.We also introduced some bioinspired materials that are capable of stimulus-responsive DLT under external fields.Finally,we suggested perspectives of the bioinspired DLTs in liquid manipulations.

Biomimetic directional transport for sustainable liquid usage

Through hundreds of millions of evolution,animals and plants have possessed their unique structures to adapt to natural variations.As a familiar process,liquid transportation plays an important part in both production and life,and researchers focus on how to achieve this process in a convenient and efficient way without energy input.Inspired by nature,various bioinspired structures are reported and have won multiple achievements.This review starts from basic theory about surface wettability,and then summarises the creatures with special liquid transport functions as well as crucial structures that cause this phenomenon.Next,the recent articles about transporting liquid by bioinspired materials are introduced.Finally,we proposed a brief conclusion and the prospect of bionic materials in the future.

THE SIMPLE BLOCK ITERATIVE ALGORITHM OF AN EXTENDED ENTROPY MODEL AND ITS CONVERGENCE

The paper discusses an extended entropy model for the prediction of trip amount and provides a method to solve it, called the simple block iterative algorithm, from the point of view of the system of nonlinear equations. Because the algorithm gives consideration to the characteristic of the model, it has better effect in our practice. The paper also studies the existence and uniqueness of the solution and convergence of the algorithm.