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Traditional strategies, such as morphological or chemical gradients, struggle to realize the high-velocity and long-distance transport for droplets on a solid surface because of the pinning hydrodynamic equilibrium. Thus, there is a continuing challenge for practical technology to drive droplet transport over the last decades. The surface charge density (SCD) gradient printing method overcame the theoretical limit of traditional strategies and tackled this challenge [Nat. Mater. 2019, 18: 936], which utilized the asymmetric electric force to realize the high-velocity and long-distance droplet transport along a preprinted SCD gradient pathway. In the present work, by coupling the electrostatics and the hydrodynamics, we developed an unexplored numerical model for the water droplet transporting along the charged superhydrophobic surface. Subsequently, the effects of SCD gradients on the droplet transport were systematically discussed, and an optimized method for SCD gradient printing was proposed according to the numerical results. The present approach can provide early guidance for the SCD gradient printing to drive droplet transport on a solid surface.

Superhydrophobic surfaces have been widely studied due to their potential applications in aerospace fields. However, superhydrophobic surfaces with excellent water-repellent, anti-icing, and icephobic performances at low temperatures have rarely been reported. Herein, superhydrophobic surfaces with heating capability were prepared by etching square micropillar arrays on the surface of multiwalled carbon nanotube (MWCNT)/poly(dimethylsiloxane) (PDMS) films. The fabricated superhydrophobic surface has triple icephobicity, which can be activated even at low temperatures. The triple icephobicity is triggered by an applied voltage to achieve excellent water-repellent and icephobic capabilities, even at −40 °C. Additionally, theoretical calculations reveal that a droplet on a superhydrophobic surface loses heat at a rate of 8.91 × 10–5J/s, which is 2 orders of magnitude slower than a flat surface (2.15 × 10–3J/s). Also, at −40 °C, the mechanical interlocking force formed between the superhydrophobic surface and ice can be released by the heating property of the superhydrophobic surface. This low-energy, multifunctional superhydrophobic surface opens up new possibilities for bionic smart multifunctional materials in icephobic applications.

ABSTRACTPrevious studies have indicated that teacher well-being (TWB) should have substantial benefits for both individuals and organisations. This study explored the relationship between the professional learning community (PLC) and TWB from the perspective of the job demands-resources (JD-R) model. Informed by self-efficacy theory, the present study further investigated whether the PLC-TWB relationship was mediated by teaching self-efficacy (TSE). Survey data were gathered from 844 teachers from 28 schools in one province of southeastern China. The results showed that each of the six PLC components was positively related to teachers’ hedonic and eudaimonic well-being. The association between the PLC and TWB was confirmed to be mediated by TSE. Our study not only highlighted the importance of the PLC on TWB in China, but also provided insights into the mechanism of the PLC-TWB relationship through the lens of TSE. Implications for research and practice were discussed.

Surface 2019, surface charge density (SCD) gradient printing-driven droplet transport, has attracted considerable attention as a novel and effective approach, which adopts the water droplet impacting a nonwetting surface to create a reprintable SCD gradient pathway conveniently and realizes the high-velocity and long-distance transport of droplets. In the present work, we further investigated the effects of electrothermal behavior on SCD gradient printing on hydrophobic surfaces by considering the droplet impact dynamics. After the electrothermal function was activated, the wettability of the hydrophobic surface improved in terms of the spreading factor history and the infiltration depth, which increased the probability of solid/liquid contact electrification to generate a more favorable SCD gradient. Since the hydrophobic surface was negatively charged by droplet impact, polarized droplets rolled forward along the preprinted SCD gradient pathway due to opposite charge attraction. Based on these results, we designed a SCD gradient printer with an electrothermal function for hydrophobic surfaces. Subsequently, the kinematic parameters of rolling droplets on hydrophobic surfaces were observed and quantified to evaluate the improvements resulting from the electrothermal function.

In this study, bamboo and glass fibers were successfully added into bisphenol A–aniline-based benzoxazine resin by hot pressing method. The effect of water absorption on the mechanical properties of the neat benzoxazine and its composites was studied. The composites prepared in this study has been proved to exhibit better water resistance than some conventional natural fiber/polymer composites due to good hydrophobicity of the benzoxazine matrix. From the mechanical tests, the tensile performance of both neat benzoxazine and the composites degraded seriously after prolonged immersion in water. However, neat benzoxazine and the composites maintained relatively higher residual flexural properties (residual mechanical properties refer to the ratio of strength and modulus of the saturated samples to that of the nonaged samples) after 20 days of water immersion. The effect of water molecules on the fracture surface morphologies of the composites was studied using a scanning electron microscope (SEM). The SEM images showed that the interfacial bonding between fibers and the matrix degraded seriously due to the attack of water.

The icephobicity property of multifunctional surfaces has been widely studied due to their potential application in the aerospace field. Herein, a controllable CNW/PDMS biomimetic nanocomposite film with a superhydrophobic surface is fabricated. The microcolumns are etched on the surface of the biomimetic nanocomposite to provide superhydrophobicity. Two defense strategies of biomimetic nanocomposites are proposed while passive anti-icing and active electrothermal deicing behaviors of the biomimetic nanocomposite are experimentally studied. It is found that the initial nucleation time of a single water droplet is delayed by 353.3 s on the superhydrophobic surface relative to the hydrophilic surface. The adhesion strength increases with the increase of surface roughness. The heating uniformity on the biomimetic nanocomposite surface was validated by infrared thermography technology. The ice layer is completely melted within 150 s under 40 V voltage captured by a noncontact infrared camera. The proposed strategy was validated by the characterization of the passive anti-icing and active electrothermal deicing property from biomimetic nanocomposites with superhydrophobic microstructure surfaces. Research results show that the two lines of defense collaborative work for an icephobicity system were able to keep biomimetic nanocomposite surfaces ice-free under test conditions.

Based on the three-dimensional thermodynamic model, the wettability of a superhydrophobic solid surface with a circular truncated cone microstructure has been investigated. The relationship between the microstructure of the circular truncated cone surface and superhydrophobic property is established by introducing the tension of the three-phase contact line in the composite state. The results show that the base angle and base spacing of the circular truncated cone have great influence on the wetting transition of composite and non-composite states. The theoretical expressions of the critical transition criteria are also given. The accuracy of the theoretical results is verified by comparing the theoretical prediction with the existing experimental data in the literature. The model established in this paper provides a theoretical basis and a reference for the optimal geometric parameters for studying the wettability of advanced superhydrophobic materials by using engineering microstructures.

Amorphous alloys, with unique atomic structures and metastable nature, are treated as superior candidates for environmental wastewater remediation due to their superior catalytic capabilities. Given the strong demand for environmental protection, the field of amorphous alloys in wastewater treatment has great development prospects, and numerous research results have been published in recent years. As a promising catalyst, it was demonstrated that amorphous alloys could exhibit many excellent properties in wastewater treatment, such as high catalytic efficiency, easily adjustable parameters and reliable sustainability. This paper aims to summarize recent research trends regarding amorphous alloys in the field of catalysis, focusing on the preparation methods, physical performance, catalytic mechanisms and environmental application. Meanwhile, this review also investigates the challenges encountered and future perspectives of amorphous alloys, offering new research opportunities to enlarge their applicability spectra.

The sliding behavior of anisotropic surfaces is a crucial property to their applications from fundamental research to practical fields. Herein, we propose a theoretical model for analyzing the sliding behavior based on the concept of adhesion energy. Surface Evolver simulation is conducted to determine the adhesion energy per unit area. The microgrooved surfaces are fabricated and characterized to validate the proposed theory. It is found that the apparent contact angle measured along the direction parallel to the strips increases with the increase of microgroove width, while the corresponding sliding angles exhibit an opposite trend. The adhesion energy per unit area has a constant value regardless of the droplet volume. The different sliding behaviors of anisotropic surfaces along the perpendicular and parallel directions are attributed to the difference in the corresponding adhesion energies per unit area. The proposed model is expected to be used for predicting the sliding behavior of anisotropic surfaces.

Superhydrophobic surfaces have attracted great interest due to their self-cleaning, dust-proofing and friction-reducing properties. Related papers have proposed methods and theoretical bases for preparing these surfaces in order to achieve excellent superhydrophobicity. However, the influence of the roughness of the solid surface structure on its superhydrophobicity requires further in-depth thermodynamic analysis. In this paper, three-dimensional (3D) cylinder microtextured surface models are selected based on thermodynamic analysis. On this basis, a simulation diagram of the three-phase contact line of a circular cylinder section in a 3D model is presented. The effects of the intrinsic contact angle and geometrical parameters of the cylinder microtexture on free energy and the free energy barrier, as well as contact angle hysteresis, are theoretically investigated. The obtained results reveal the necessity of the transition between the non-composite state and composite state. The transition criteria between the non-composite and composite wetting states are obtained from the perspective of thermodynamic analysis and theoretical equations. The calculated results are basically consistent with the theoretical calculations and experimental results. This method provides theoretical guidance for the design of superhydrophobic surfaces.

The model of SMA reinforced composite is separated into three parts: reinforce, interphase and matrix. Taking effect of strain rate into consideration, the visco-hyperelastic model is employed in the constitutive law of interphase part. A damage model based on Hashin criterion is developed to simulate the SMA reinforced composite plate subject to low or high velocity impact. Effect of the impact velocity on the shape memory alloy reinforced composite plate under fixed boundary condition is investigated by finite element method, also as the damage state. Low velocity is applied to the model firstly to illustrate the accuracy of parameters and procedures by comparing with the experimental data. In next step, several impact velocities are applied during the simulation process to invest the impact resistance and failure mechanism. Simulation results indicate that damage model of composite is sensitive to loading speed and it is easier for the creak to grow under high velocity.

Application of algicidal bacteria is a potential bio-technique to inhibit harmful algal growth and remove algal blooms. At present, algicidal bacteria are mainly used in the form of freely suspended cells. In this study, the bacterium Brevundimonas sp. AA06 against Microcystis aeruginosa was isolated from soil and the algicidal effects of immobilized strain AA06 were investigated. The spherically immobilized beads (φ = 3.0~4.0 mm) were prepared by polyvinyl alcohol (PVA) and sodium alginate (SA). Scanning electron microscopy (SEM) images of polyvinyl alcohol-sodium alginate (PVA-SA) beads showed that there were a large number of pores inside and that the bacterial cells adhered to the skeleton. Cyanobacterial dose-relationship tests showed that the PVA-SA beads exhibited weaker algicidal effects than freely suspended cells. At an initial M. aeruginosa cell density of 2.0 × 109cells/L, PVA-SA beads inhibited the growth of M. aeruginosa for up to 60 days, which was much longer than freely suspended cells (34 days). When M. aeruginosa was exposed to PVA-SA beads at EC70 96h(concentrations for 70% of maximal algicidal effect after 96 h), the total microcystin-LR (MC-LR,) concentrations (intra and extra cellular) remained stable at 40.0±5 μg/L, with intracellular MC-LR concentrations declining.

Four types of granular activated carbon (GAC), i.e., two coal-based activated carbon (φ = 4 mm, CBAC-4; φ = 1.5 mm, CBAC-1.5), coconut shell activated carbon (CSAC), and nut shell activated carbon (NSAC), were selected to investigate the effects of their adsorption properties on the degradation of acid red 14 (AR-14) by using three-dimensional electrode system. The results of Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy indicated that obvious differences in the surface morphologies, textural properties, and surface functional groups among them were not observed. Based on the pseudo-second-order and Freundlich model, the adsorption velocity and capacity followed the order: NSAC > CSAC ≈ CBAC-4 > CBAC-1.5. According to the variation of AR-14, chemical oxygen demand, and total organic carbon concentrations in the electro-oxidation processes, the order of the four GACs on AR-14 degradation and removal was approximately NSAC > CSAC > CBAC-4 ≈ CBAC-1.5. The increase in hydraulic retention time was more beneficial to GACs with higher adsorption property. The GACs with lower adsorption property required higher current and energy consumption to obtain the similar efficiency for AR-14 removal. Thus, the particle electrodes should be the material with good adsorption capacity toward the target pollutants.

The toxicity of soil irrigated with treated domestic wastewater (site A) and untreated gray wastewater (site B) were investigated. Soil extracts were prepared using distilled water, acid solvent (0.1 mol·L−1HCl), and organic solvent (acetone:petroleum ether: cyclohexane = 1:1:1) to understand the type of pollutants responsible for the ecotoxicity associated with wastewater irrigation. The soil toxicity was assessed using a luminescence inhibition assay with Vibrio fischerifor acute toxicity, a micronucleus assay with Vicia fabaroot tips and a single cell gel electrophoresis assay of mice lymphocytes for genotoxicity. The physicochemical properties and the heavy metal (HM) contents of the irrigated soil were also analyzed. The results indicated that the wastewater irrigation at site A had no effects on the soil properties. With the exception of Pb, Zn, Fe, and Mn, the accumulation of HMs (Cu, Ni, and Cr) occurred. However, the irrigation at site A did not result in obvious acute toxicity or genotoxicity in the soil. The soil properties changed greatly, and HMs (Cu, Ni, and Cr) accumulated in site B. There were significant increases in the acute toxic and genotoxic effects in the soils from site B. The ecotoxicity in site B came primarily from organic-extractable pollutants.

Description on dynamic behaviours of crack-tips is one of the important foundations to develop a reasonable dynamic fracture criterion. In order to describe the dynamic behaviours of the crack-tip in a material with low viscosity-number, the displacement potential function is assumed as a mathematical expression with exponential singularity. The asymptotic linear differential equations determining plane crack-tip field are established based on the mechanical constitutive model for elastic-viscoplastic materials. According to the conditions of determining solutions for dynamic cracks of mode II, the crack-tip stress fields are numerically simulated based on the asymptotic linear differential equations. Results show the asymptotic linear equations can well describe the crack-tip fields of plane dynamic cracks in the elastic-viscoplastic material with low viscosity-number.

Description on dynamic behaviours of crack-tips is one of the important foundations to develop a reasonable dynamic fracture criterion. In order to describe the dynamic behaviours of the crack-tip in a material with low viscosity-number, the displacement potential function is assumed as a mathematical expression with exponential singularity. The asymptotic linear differential equations determining plane crack-tip field are established based on the mechanical constitutive model for elastic-viscoplastic materials. According to the conditions of determining solutions for dynamic cracks of mode II, the crack-tip stress fields are numerically simulated based on the asymptotic linear differential equations. Results show the asymptotic linear equations can well describe the crack-tip fields of plane dynamic cracks in the elastic-viscoplastic material with low viscosity-number.

In order to improve dispersibility, chemical stability and magnetic flocculation performance, Fe3O4was functionalized through SiO2coating. The characterization of Fe3O4/SiO2particles was analyzed, such as morphology, size, structure, chemical composition, zeta potential, magnetic and thermal properties. Magnetic flocculation of kaolin particles was investigated under different pH conditions, Fe3O4/SiO2dosages and Ca2+concentrations. Flocculation factors were further analyzed using response surface methodology. A modified Derjaguin-Landau-Verwey-Overbeek (MDLVO) model was applied, and the size and fractal dimension of magnetic flocs were analyzed to establish the mechanism of flocculation. Results showed that Fe3O4/SiO2is a core-shell nanocomposite with a specific surface area of 65.14 m2/g and saturation magnetization of 46.54 emu/g. Coating with SiO2greatly reduced the median equivalent-volume diameter (D50) of Fe3O4from 10.48 to 2.88 µm. A kaolin removal efficiency of 93.8% was achieved under conditions of an initial turbidity of 200 NTU, pH 7.0, 1.0 g/L Fe3O4/SiO2, and 4.5 mmol/L Ca2+. Response surface analysis indicated that interactions occur between Fe3O4/SiO2and Ca2+, as well as Ca2+and pH. Fe3O4/SiO2can be effectively detached from the aggregates and reused, maintaining a removal efficiency of more than 87.7% after ten cycles of use. The energy barrier between kaolin and Fe3O4/SiO2was significantly reduced due to the electrostatic interaction of Ca2+. Furthermore, the MDLVO theory predicted that magnetic forces induce collision and movement between Fe3O4/SiO2and kaolin-Ca2+. The floc structures formed in the magnetophoresis process significantly affect the flocculation of kaolin particles.

The interlaminar bonding property between the facesheet and foam core plays an important role in enhancing the impact damage resistance ability of sandwich panels. In this paper, we filled short glass fiber (SGF) mat between the facesheet and foam core to enhance their bonding strength. The newly designed sandwich panels were manufactured by vacuum-assisted resin injection processing. A series of SGF mat filled sandwich panels with glass and/or carbon fiber facesheets were manufactured. The low-velocity impact as well as the compression-after-impact (CAI) performence were investigated. Failure modes of the sandwich panels were analyzed. Low-velocity impact results show that SGF mat filled sandwich panels with pure glass fiber facesheet displayed the maximum contact force. In the CAI test, wrinkling of the facesheet, buckling of the foam, and debonding between them are the major failure modes. Compared with contrast samples, SGF toughened sandwich panels show the highest strength increase rate.

Fiber-reinforced thermosetting composites have been increasingly used in various fields due to their outstanding mechanical properties. However, nonreversible spring-in deformation is an obstacle to the rapid development of composite parts. In the present paper, the spring-in of ribs were investigated by experimental measurements and numerical simulations with an emphasis on industrial manufacturing. The results indicate that for the area with both ends involved with the castellations removal, the spring-in of ribs can be reduced by removing the castellations on flanges before curing. The mechanism behind is that relatively larger nonmechanical strains along length direction can be produced between gelation and vitrification for the processing method where castellations were removed before curing, which further causes an increase in the nonmechanical strains along radial direction, and the resultant spring-in will be reduced. The obtained findings are also expected to be extendable to curved composite parts with structural holes.