Impact of a Ball Regulation Change on Game Performance and Shooting Play in Japanese U-15 Girls' Handball.

We aimed to investigate how a ball regulation change, implemented in U15 girls' handball games, now affects game performance and shooting plays. Over 14 matches (28 observations), we included all the attacks ( = 813) and shooting plays ( = 589) with the conventional ball and all the attacks ( = 821) and shooting plays ( = 618) with the new ball performed by both teams. We used notational analysis to compare the game performance and shooting plays in these two conditions.

Gas Bubbles Stabilized by Janus Particles with Varying Hydrophilic-Hydrophobic Surface Characteristics.

Micrometer-sized polymer-grafted gold-silica (Au-SiO) Janus particles were fabricated by vacuum evaporation followed by polymer grafting. The Janus particle diameter, diameter distribution, morphology, surface chemistry, and water wettability were characterized by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The optical microscopy results showed that the polystyrene (PS)-grafted Au-SiO Janus particles exhibited monolayer adsorption at the air-water interface and could stabilize bubbles, preventing their coalescence for more than 1 month.

pH-Sensitive Adsorption Behavior of Polymer Particles at the Air-Water Interface.

pH-Sensitive adsorption of polymer particles bearing poly[2-(dimethylamino)ethyl methacrylate] hairs at the air-water interface was investigated using a surface tensiometer, a Langmuir-Blodgett trough, and an X-ray reflectometer. We clarified that the particles are adsorbed at the interface at basic pH; by contrast, at acidic pH, only a small number of particles are adsorbed, whereas the majority are dispersed in the water phase. X-ray reflectometry analysis revealed that a particle monolayer was formed at the air-water interface, which was packed densely under increasing surface pressure, as determined by the electron density profile change.

Liquid marble and water droplet interactions and stability.

The interactions between two individual water droplets were investigated in air using a combination of coalescence rig and high speed video camera. This combination allows the visualization of droplet coalescence dynamics with millisecond resolution which provides information on droplet stability. Bare water droplets coalesced rapidly upon contact, while droplet stability was achieved by coating the droplets with polystyrene particles carrying pH-responsive poly[2-(diethylamino)ethyl methacrylate] hairs (PDEA-PS particles) to form liquid marbles.

pH- and temperature-responsive aqueous foams stabilized by hairy latex particles.

Polystyrene (PS) particles carrying pH- and temperature-responsive poly[2-(dimethylamino)ethyl methacrylate] (PDMA) hairs (PDMA-PS particles) were synthesized by dispersion polymerization. The diameter, diameter distribution, morphology, chemical composition and surface chemistry of the particles were characterized using scanning electron microscopy (SEM), elemental microanalysis, dynamic light scattering and zeta potential measurements. The hydrophilicity-hydrophobicity balance of the PDMA could be tuned by varying both pH and temperature and therefore these sterically stabilized particles acted as doubly stimuli-responsive stabilizers for aqueous foams by adsorption and desorption to/from the air-water interface.