Leakage Retardation of Static Seals via Surface Roughness and Wettability Modification.

In this paper, the effects of surface roughness and wettability on the leakage performance of static seals were highlighted. The results show that the leakage rate is negatively correlated with the contact pressure and positively correlated with surface roughness. Surface wettability affects leakage performance.

Creating lifting force in liquids via thermal gradients.

In this paper, we explore a concept and present the first experimental evidence to show that it is possible to form a stable liquid film and create lifting force at the interface via thermal gradient to minimize interfacial rubbing of surfaces and the associated wear. The approach is based on manipulating the flow behavior via thermocapillary, which describes how a liquid can be made to flow from warm to cold regions purely by inducing a thermal gradient. We show that liquid bridges between two parallel plates can be manipulated and stabilized under a combined effect of the thermocapillary flow and the Couette flow, which describes the motion of a viscous fluid between two parallel plates in a relative sliding motion.

Bioinspired Functional Structures for Lubricant Control at Surfaces and Interfaces: Wedged-Groove with Oriented Capillary Patterns.

In this work, a design concept of bioinspired functional surfaces is proposed for lubricant control at surfaces and interfaces subjected to external thermal gradients. Inspired by the conical structures of and the motion configuration of , a bioinspired surface of wedged-groove with an oriented capillary pattern is constructed. The effect of geometrical parameters on the directional lubricant manipulation capacity and sliding anisotropy is discussed.

Succession of soil bacterial communities and network patterns in response to conventional and biodegradable microplastics: A microcosmic study in Mollisol.

Significant soil contamination of microplastics (MPs) by the application of agricultural mulching films has aroused global concern, however, the effects of conventional and biodegradable MPs on the dynamics of soil microbial communities and network patterns have not been sufficiently reported. In this study, we conducted a soil microcosmic experiment by adding low-density polyethylene and biodegradable MPs (PE and BD) into a black soil at the dosages of 0 % (CK), 0.1 % (low-dose, w/w), 1 % (medium-dose, w/w) and 5 % (high-dose, w/w), and soils were sampled on the 15th, 30th, 60th and 90th day of soil incubation for high-throughput sequencing.

Efficient Bubble Transport on Bioinspired Topological Ultraslippery Surfaces.

Slippery liquid-infused porous surfaces (SLIPS) with micro-/nanostructures inspired by the pitcher plant exhibit excellent characteristics in terms of liquid repellency, self-healing, pressure tolerance, and so forth. In particular, stable bubble transport on SLIPS can be achieved when the surface is submerged in water. However, more precise and sophisticated bubble manipulations on SLIPS still remain challenging.

Migration of Liquid Bridges at the Interface of Spheres and Plates with an Imposed Thermal Gradient.

In this paper, we experimentally investigate the migration of liquid bridges at the interface of spheres and plates with an imposed thermal gradient. The key influencing factors of interface gap, sphere material and diameter, liquid viscosity, and thermal gradient on the migration behaviors are highlighted. Furthermore, the physical mechanism of this intriguing interfacial phenomenon is numerically unraveled.

Non-sticky and Free-forward Performances of Grubs against Soil.

The intriguing non-sticky and free-forward performances of grubs against soil deeply attract our interests. In this study, the life cycle and body morphology of a kind of grubs, larvae of Japanese rhinoceros beetles, are introduced. The uniformly oriented hierarchical micro structures pattern on the back epidermis is firstly reported.

Manipulating thermocapillary migration via superoleophobic surfaces with wedge shaped superoleophilic grooves.

Hypothesis: Thermocapillary migration is a phenomenon that liquid droplets can move from warm to cold regions on a nonuniformly heated surface. We expect to construct functional surfaces to manipulate the migration of liquid lubricants on rubbing surfaces.

Experiments: Superoleophobic surfaces with wedge shaped superoleophilic grooves of varying geometrical parameters are fabricated, and migration experiments of typical liquid lubricants are performed on the designed surfaces.

On the Thermocapillary Migration on Radially Microgrooved Surfaces.

Thermocapillary migration describes the phenomenon in which a droplet placed on a nonuniformly heated surface can migrate from warm to cold regions. Herein, we report an experimental investigation of the migration of silicone oil droplets on radially microgrooved surfaces subjected to a thermal gradient; the effects of the initial divergence angle and divergent direction on the migration behavior are highlighted. A theoretical model is established to predict the migration velocity considering the thermocapillary, viscous resistance, and radial structure-induced forces; furthermore, the proposed theoretical derivation is validated.

Magnetically stimulating capillary effect for reversible wet adhesions.

Despite fascinating natural examples of switchable adhesives to wet surfaces, strategies for an artificially switching capillary adhesion system in situ remains a challenge. Here, we develop a smart reversible magnetic fluid (MF) meniscus adhesion system whose capillary effect can be regulated by external magnetic stimuli. It is revealed that the MF filled joint between two solid surfaces undergoes alteration of its adhesive properties in response to the external stimulus of a varying magnetic field.

Pillar versus dimple patterned surfaces for wettability and adhesion with varying scales.

Inspired by biological topographical surfaces, micropatterned elastomeric surfaces with square pillars and dimples of different geometry scales were fabricated. Their wettability and adhesion properties with various liquids were systematically investigated and compared with flat surfaces. Interesting results were obtained in the case of silicone oil (the toe-pad-like wetting case) in that the scale-dependent wettability and adhesion performed inversely for pillars and dimples.

Ringlike Migration of a Droplet Propelled by an Omnidirectional Thermal Gradient.

The interfacial phenomenon associated with the ringlike motion of a liquid droplet subjected to an omnidirectional thermal gradient is investigated. An experimentally verified model is proposed for estimating the droplet migration velocity. It is shown that the unbalanced interfacial tension acting on the liquid in the radial direction provides the necessary propulsion for the migration, whereas the internal force acting on the adjoining liquid contributes to the equilibrium condition in the circumferential direction.

Contact angle hysteresis effect on the thermocapillary migration of liquid droplets.

Thermocapillary migration describes a phenomenon where a liquid droplet spreads from warm to cold regions due to the interfacial tension gradients. Since the contact angle hysteresis effect is involved during the migration process, we consider the hysteresis effect and rectify the theoretical model to predict the migration velocity on solid surfaces. By conducting migration experiments on surfaces with different magnitudes of the hysteresis effect, we verify the validity of the theoretical derivation.

Effect of wetting case and softness on adhesion of bioinspired micropatterned surfaces.

Inspired by the adhesive ability of amphibian toe-pads, polydimethylsiloxane (PDMS) hexagonal pillar arrayed surfaces with varying softness are fabricated, and their adhesion behaviors in the non-wetting, mostly wetting and totally wetting cases are throughly investigated. Experimental results demonstrate that under a totally wetting case, i.e.

On the migration of a droplet on an incline.

A liquid droplet placed on a nonuniformly heated solid surface will migrate from a high temperature region to a low temperature region. The present study reports the results of an experimental investigation on the migration behavior of mineral oil droplets subjected to a thermal gradient on an inclined plane. A particular attention is paid to the relationship between the critical inclination angle and thermal gradients.

Thermocapillary Migration of Liquid Droplets Induced by a Unidirectional Thermal Gradient.

A liquid droplet placed on a nonuniformly heated solid surface will migrate from a high-temperature region to a low-temperature region. This study reports the development of a theoretical model and experimental investigation on the migration behavior of paraffin oil droplets induced by the unidirectional thermal gradient. Thin-film lubrication theory is employed to determine the migration velocity of droplets, and temperature dependence of viscosity is taken into account.

A Surface Texture Design to Obstruct the Liquid Migration Induced by Omnidirectional Thermal Gradients.

Thermo-capillary migration is a phenomenon in which surface thermal gradients drive a liquid to flow from warm to cold regions without external forces. It is important to prevent the migration of liquid lubricants on rubbing surfaces. In this paper, a pattern of microdimples was proposed to obstruct the liquid migration induced by an omnidirectional thermal gradient.

Covalent attachment of phospholipid analogous polymers to modify a polymeric membrane surface: a novel approach.

A novel method for the surface modification of a microporous polypropylene membrane by tethering phospholipid analogous polymers (PAPs) is given, which includes the photoinduced graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and the ring-opening reaction of grafted poly-(DMAEMA) with 2-alkyloxy-2-oxo-1,3,2-dioxaphospholanes. Five 2-alkyloxy-2-oxo-1,3,2-dioxaphospholanes, containing octyloxy, dodecyloxy, tetradecyloxy, hexadecyloxy, and octadecyloxy groups in the molecular structure, were used to fabricate the PAP-modified polypropylene membranes. The attenuated total reflectance FT-IR spectra of the original, poly(DMAEMA)-grafted, and PAP-modified membranes confirmed the chemical changes on the membrane surface.