Takehiko Gonda

Growth rate and morphology of ice crystals growing in a solution of trehalose and water

In-situ observations have been made of ice crystals growing in solutions of trehalose and water in order to investigate how trehalose suppresses the growth of ice crystals and protects organisms from the freezing of their cellular water. In the range of trehalose concentration below 41.7 wt% the growth rate along the a-axis was found to increase proportionally to the second power of the supercooling and to be suppressed by 75% when the trehalose concentration was doubled. In this manner, trehalose proved to be approximately twice as effective as sucrose in suppressing the growth rate of ice crystals. It was also more effective than sucrose in suppressing the morphological instability of ice crystals. This effectiveness is believed to be related to the fact that trehalose binds more water molecules than does a sucrose molecule.

In situ observation of vapor-grown ice crystals by laser two-beam interferometry

Abstract In situ observation of vapor-grown ice crystals was carried out using laser two-beam interferometry, and the growth mechanism of vapor-grown ice crystals at the temperature range of -7 to -28.5°C and at low supersaturation was investigated.

Dendritic ice crystals with faceted tip growing from the vapor phase

Abstract Dendritic ice crystals with faceted tip are formed in air of 1.0 × 10 5 Pa at − 15°C and just below water saturation. When large concaves are formed on two prismatic facets at the tip of primary branches, dendritic ice crystals with side branches are formed.

Formation mechanism of side branches of dendritic ice crystals grown from vapor

Dendritic ice crystals were grown in air of 1.0 × 105 Pa at about −15°C and the formation mechanism of side branches was experimentally investigated. As a result, when bulk supersaturation is constant, side branches are not formed though the ruggedness is formed along the sides of primary branches. On the other hand, when bulk supersaturation varies with time, the side branches are formed.

Growth mechanism of a Ag crystal particle containing a twin plane grown on a Mo(110) surface

Abstract We have studied the growth of vapour deposited Ag particles on a Mo(110) surface heated at 400°C using a method of “in-situ” observation by scanning electron microscopy (SEM). The shape of almost all Ag particles showed a quasi-Wulff polyhedron of cubo-octahedron truncated by (100) planes, but for the small number of particles multiply twinned particles of a regular icosahedron were observed. Otherwise particular shapes of (111) trigonal bipyramid truncated by (100) planes were observed in rare cases. By successive observation of the growth of these particles, it was clarified that they grew as bicrystal containing a twin plane. The growth process of the particle is described in detail. Such singly twinned particles on the substrate were observed for the first time in the present study and are important as an origin of twins in continuous films.