Conducting thin rods with a length of half the wavelength of microwaves produced by the kitchen microwave oven, such as dress pins or mechanical pencil leads, absorb microwaves efficiently. Electrons in rods accelerated by microwaves are emitted from both ends of the rods, collide with surrounding gas molecules, and create plasma. Spectra with a single bright emission line at a wavelength of about 587 nm in the visual light range were observed, regardless of the material the rod was made from.
In order to clarify the relationship between the structural color and the nanolevel structure of bird feathers, the cortical thin-film structure, the shape of melanin granules, and their arrangement were observed using transmission electron microscopy. The reflection spectra were calculated based on the electron microscopic image data using Fresnel's equation to simulate a thin-film interference and Bragg's law to simulate a photonic crystal, then were compared with the actual reflection spectra. The simulation spectra calculated using Fresnel's equation were very similar to the reflection spectra from dove and mallard feathers. The reflection spectra from each part of the eye-spot pattern of peacock feathers were very similar to both simulation spectra using Fresnel's and Bragg's equations. In the peacock feathers, the structural color from the cortex and the three-dimensional photonic crystal consisting of the lattice structure of rod-shaped melanin granules were fused to further enhance the selectivity.
In a previous study of Dettmann and Georgiou, it was considered such a situation that point-wise particles repeatedly and elastically collided with the wall of a container without any particle-particle collision and eventually escaped through a small window from the container, which can be modeled by an open billiard. In the present study, point-wise particles were replaced with finite-size disks and disk-disk collisions were also considered, and inverse power laws of distributions of dwell time in the container were obtained from numerical simulations.