Hokkaido University · Physics and Astronomy
Professor Yuki Kimura's research lab specializes in the in-situ observation and fundamental understanding of nucleation, crystallization, and defect formation processes across diverse systems, ranging from biological macromolecules and ionic liquids to semiconductors and astrophysical materials. The lab employs advanced electron microscopy techniques—particularly time-resolved liquid-cell TEM and in situ TEM—to visualize dynamic processes such as cluster formation, heterogeneous nucleation, and defect evolution at the nanoscale. A central theme is unraveling the mechanisms behind phase transitions, polymorph selection, and solidification under extreme or biologically relevant conditions.
Figures are computed from collected data and may differ slightly.
Nucleation, the primary step in crystallization, dictates the number of crystals, the distribution of their sizes, the polymorph selection, and other crucial properties of the crystal population. We used time-resolved liquid-cell transmission electron microscopy (TEM) to perform an in situ examination of the nucleation of lysozyme crystals. Our TEM images revealed that mesoscopic clusters, which are similar to those previously assumed to consist of a dense liquid and serve as nucleation precurso
The formation of crystals from solution requires the initial self-assembly of units of matter into stable periodic structures reaching a critical size. The early stages of this process , called nucleation, are very difficult to visualize. Here we describe a novel method that allows real time observation of the dynamics of nucleation and dissolution of sodium chlorate clusters in an ionic liquid solution using in situ transmission electron microscopy. Using ionic liquids as solvent circumvents th
Defects in the supercritical thickness strained-Si layer grown on a fully relaxed SiGe buffer layer were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The AFM observation of chemically etched surfaces showed that etch pits having a crosshatch pattern due to misfit dislocations decrease and segments and deep valley profiles increase with an increase in the strain energy of the Si. We found that the segment corresponds to an extended dislocation, of whic
The abundant forms in which the major elements in the universe exist have been determined from numerous astronomical observations and meteoritic analyses. Iron (Fe) is an exception, in that only depletion of gaseous Fe has been detected in the interstellar medium, suggesting that Fe is condensed into a solid, possibly the astronomically invisible metal. To determine the primary form of Fe, we replicated the formation of Fe grains in gaseous ejecta of evolved stars by means of microgravity experi
Root hairs often contribute to nutrient uptake from environments, but the contribution varies among nutrients. In <i>Arabidopsis</i>, two high-affinity sulfate transporters, SULTR1;1 and SULTR1;2, are responsible for sulfate uptake by roots. Their increased expression under sulfur deficiency (-S) stimulates sulfate uptake. Inspired by the higher and lower expression, respectively, of <i>SULTR1;1</i> in mutants with more (<i>werwolf</i> [<i>wer</i>]) and fewer (<i>caprice</i> [<i>cpc</i>]) root h
This study showed decreased FMD with aging even in the healthy elderly, with a further decline in hypertensive elderly compared with healthy elderly subjects. This impairment of FMD in the hypertensive elderly group was related to age and mean blood pressure, indicating that aging and hypertension may impair endothelial function in the brachial artery of elderly patients with hypertension.
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