Repulsion, Acceleration, and Coalescence between Water Droplets on Superhydrophobic Glass by Triboelectrification.

Manipulating the motion of water droplets on surfaces, which is crucial for various applications, such as microfluidics and heat transfer, presents considerable challenges, primarily due to the significant influence of capillary forces. This effect becomes more pronounced when droplets are in close proximity, often resulting in undesired coalescence. Triboelectrification, which involves charging pure water droplets, is a promising approach to enhance the ability to manipulate water droplets. For effective triboelectrification, charges must accumulate within the droplets; this ensures efficient and sustained droplet manipulation while minimizing dissipation. Low-friction, superhydrophobic, insulating surfaces are ideal for this purpose. However, few studies have explored the application of insulating superhydrophobic surfaces to manipulate droplet motion. In this study, we investigated the behavior of water droplets on insulating superhydrophobic quartz surfaces after triboelectrification. The droplets acquired significant charge when dripped onto a superhydrophobic glass surface. Consequently, these charged droplets exhibited behaviors such as repulsion and acceleration from one another, uphill movement, and rapid long-distance transport to specific positions. These advancements in droplet manipulation techniques hold promise for diverse fields such as microfluidics and heat exchangers.

Single-Layer-Graphene-Coated and Gold-Film-Based Surface Plasmon Resonance Prism Coupler Sensor for Immunoglobulin G Detection.

A graphene-based surface plasmon resonance (SPR) prism coupler sensor is proposed for the rapid detection of immunoglobulin G (IgG) antibodies. The feasibility of the proposed sensor is demonstrated by measuring the IgG concentration in phantom mouse and human serum solutions over the range of 0-250 ng/mL. The results show that the circular dichroism and principal fast axis angle of linear birefringence increase in line with increases in IgG concentration over the considered range. Moreover, the proposed device has a resolution of 5-10 ng/mL and a response time of less than three minutes. In general, the sensor provides a promising approach for IgG detection and has significant potential for rapid infectious viral disease testing applications.

Harvesting water surface energy: self-jumping nanostructured hydrophobic metals.

Water in motion is a significant energy source worldwide, but the surface energy of water is rarely utilized as a power source. In this study, we made metals unsinkable and able to jump out of the water by harvesting the water surface energy. This effect is attributed to the enhanced floating ability of the nanostructures on copper and stainless steel foil surfaces. Sufficiently thin hydrophobic metals can slowly float underwater through air trapping at the surface and then rapidly leap out of the water on contact with the water-air interface. The mechanism is related to the surface energy of the water, which contributes to the 15 mg metals with a power of 0.49 µW experiencing rapid changes in velocity and acceleration at the interface. The conversion of surface energy to eject nanostructured hydrophobic materials from the liquid surface may lead to new solid-liquid separation techniques.

Attribute-Aware Recommender System Based on Collaborative Filtering: Survey and Classification.

Attribute-aware CF models aim at rating prediction given not only the historical rating given by users to items but also the information associated with users (e.g., age), items (e.g., price), and ratings (e.g., rating time). This paper surveys work in the past decade to develop attribute-aware CF systems and finds that they can be classified into four different categories mathematically. We provide readers not only with a high-level mathematical interpretation of the existing work in this area but also with mathematical insight into each category of models. Finally, we provide in-depth experiment results comparing the effectiveness of the major models in each category.

Pool boiling of nanoparticle-modified surface with interlaced wettability.

This study investigated the pool boiling heat transfer under heating surfaces with various interlaced wettability. Nano-silica particles were used as the coating element to vary the interlaced wettability of the surface. The experimental results revealed that when the wettability of a surface is uniform, the critical heat flux increases with the more wettable surface; however, when the wettability of a surface is modified interlacedly, regardless of whether the modified region becomes more hydrophilic or hydrophobic, the critical heat flux is consistently higher than that of the isotropic surface. In addition, this study observed that critical heat flux was higher when the contact angle difference between the plain surface and the modified region was smaller.