Coalescence-induced jumping of nanodroplets on mixed-wettability superhydrophobic surfaces

Coalescence-induced droplet jumping on superhydrophobic surfaces has been observed at microscale and even nanoscale. The enhancement in jumping velocity of coalescing droplets is crucial for condensation heat transfer enhancement, anti-icing, self-cleaning, and so forth. However, the research on how to acquire a higher jumping velocity is really very limited. In this paper, we use molecular dynamics simulations to study the coalescence-induced jumping of two equally-sized nanodroplets on chemically heterogeneous surfaces composed of alternating stripes with different hydrophobicity. We show that the jumping velocity is closely related to the stripe width and wettability contrast, and it can even exceed that on an ideal superhydrophobic surface with 180° contact angle when the striped surfaces are properly designed. We also demonstrate that there is always an optimal stripe width yielding the maximum jumping velocity, whereas its value is independent of the wettability contrast. We reveal that the dominant factor to determine the jumping velocity is the apparent contact angle of equilibrated droplets over heterogeneous surfaces for small stripe widths, it changes to the time of liquid bridges impacting surfaces for moderate stripe widths and to the contact area between equilibrated droplets and relatively hydrophobic stripes for large stripe widths. We believe the present simulations can provide useful guidance to design self-jumping superhydrophobic surfaces.

Real-Time Stripe Width Computation Using Back Propagation Neural Network for Adaptive Control of Line Structured Light Sensors

A line structured light sensor (LSLS) is generally constituted of a laser line projector and a camera. With the advantages of simple construction, non-contact, and high measuring speed, it is of great perspective in 3D measurement. For traditional LSLSs, the camera exposure time is usually fixed while the surface properties can be varied for different measurement tasks. This would lead to under/over exposure of the stripe images or even failure of the measurement. To avoid these undesired situations, an adaptive control method was proposed to modulate the average stripe width (ASW) within a favorite range. The ASW is first computed based on the back propagation neural network (BPNN), which can reach a high accuracy result and reduce the runtime dramatically. Then, the approximate linear relationship between the ASW and the exposure time was demonstrated via a series of experiments. Thus, a linear iteration procedure was proposed to compute the optimal camera exposure time. When the optimized exposure time is real-time adjusted, stripe images with the favorite ASW can be obtained during the whole scanning process. The smoothness of the stripe center lines and the surface integrity can be improved. A small proportion of the invalid stripe images further proves the effectiveness of the control method.

Effect of Surface Structure on Peptide Adsorption on Soft Surfaces

Using molecular dynamics simulations the adsorption of peptides onto nanostructured surfaces, consisting of alternating hydrophilic-hydrophobic stripes, was investigated. The adsorption strength, calculated using metadynamics, was found to decrease as the stripe width gets smaller.

Effect of Surface Structure on Peptide Adsorption on Soft Surfaces

Using molecular dynamics simulations the adsorption of peptides onto nanostructured surfaces, consisting of alternating hydrophilic-hydrophobic stripes, was investigated. The adsorption strength, calculated using metadynamics, was found to decrease as the stripe width gets smaller.

Indium Incorporation into InGaN Quantum Wells Grown on GaN Narrow Stripes

InGaN quantum wells were grown using metalorganic chemical vapor phase epitaxy (vertical and horizontal types of reactors) on stripes made on GaN substrate. The stripe width was 5, 10, 20, 50, and 100 µm and their height was 4 and 1 µm. InGaN wells grown on stripes made in the direction perpendicular to the off-cut had a rough morphology and, therefore, this azimuth of stripes was not further explored. InGaN wells grown on the stripes made in the direction parallel to the GaN substrate off-cut had a step-flow-like morphology. For these samples (grown at low temperatures), we found out that the InGaN growth rate was higher for the narrower stripes. The higher growth rate induces a higher indium incorporation and a longer wavelength emission in photoluminescence measurements. This phenomenon is very clear for the 4 µm high stripes and less pronounced for the shallower 1 µm high stripes. The dependence of the emission wavelength on the stripe width paves a way to multicolor emitters.

Effect of Surface Structure on Peptide Adsorption on Soft Surfaces

Using molecular dynamics simulations the adsorption of peptides onto nanostructured surfaces, consisting of alternating hydrophilic-hydrophobic stripes, was investigated. The adsorption strength, calculated using metadynamics, was found to decrease as the stripe width gets smaller. The contribution of peptide conformation, entropy, and water structure on the adsorption strengths were investigated.

Sexual Dimorphism in Breast Stripe Width and Beak Eco-Morphology in Himalayan Green-Backed Tits (Parus Monticolus)

Quantitative field data on sexual dimorphism is scant for most bird species. In this first field study of a western Himalayan population of Green-backed Tits ( Parus monticolus), we demonstrate that breast stripe width is a dimorphic trait that is a reliable measure to sex this species in the wild. Based on our ability to sex the birds in hand, we describe the sexual dimorphism in eco-morphological variables in our study population. Sexual dimorphism in beak morphology changed from winter to summer due to males having shorter beaks (4.5%) in summer; however, there was little change in female beak measurements. Our study on this Himalayan congener of a widely studied European species can be used to inform studies of the evolutionary ecology of morphological traits in closely-related species inhabiting vastly different habitats.

Qualitative Inheritance of External Fruit Traits in Watermelon

Genes for watermelon [Citrullus lanatus (Thunb.) Matsumura & Nakai] fruit traits have been identified since the 1930s. We conducted a study of fruit traits including fruit stripe width, stripe color, rind color, fruit shape, and blossom end shape (concave vs. convex). Ten watermelon cultivars (inbred lines) were used as parents. Several new genes or alleles were discovered. A series of alleles at the g locus is proposed to explain the inheritance of fruit rind pattern: G (medium or dark solid green), gW (wide stripe), gM (medium stripe), gN (narrow stripe), and g (solid light green or gray). The dominance series is G > gW > gM > gN > g. Another series of alleles at the ob locus is proposed for the fruit shape: allele ObE for elongate fruit, which is the most dominant; allele ObR (not the same as the o gene for round) for the round fruit; and allele ob for oblong fruit, which is the most recessive. Gene csm is proposed for the clear stripe margin in the cultivar Red-N-Sweet and is recessive to the blurred stripe margin (Csm) in ‘Crimson Sweet’, ‘Allsweet’, and ‘Tendersweet Orange Flesh’.