Katsuo Ehara

Hydration of ions in aqueous electrolyte solutions studied by differential thermal analysis at low temperatures

Abstract In order to study the hydration of ions in aqueous electrolyte solution, the freezing and successive heating behavior was examined by means of differential thermal analysis. Li+ and Na+ ions as structure-forming ions, and K+ and Cs+ ions as structure-breaking ions, were chosen with NH4+ as an intermediate case. The anion was Cl−. On successive cooling and heating of the solutions, two freezing and melting peaks appeared respectively, except for LiCl solutions. The lower temperature peak (peak I) is considered to be the freezing and melting of the free water, while the higher temperature peak (peak II) corresponds to freezing and melting of the primary and secondary hydration regions. It could be proved that the single peak which appears for LiCl is attributable to the freezing and melting of the free water, since the hydrated region remained unfrozen due to supercooling. From the relative areas of the peaks I and II, the primary plus secondary solvation numbers could be estimated. The dependence of the total solvation number on the salt concentration is considered as due to the change in the secondary solvation number.

Pattern Analysis of Odors by Multiple Metal Oxide Semiconductors: Odor Analyzer with Human Sense of Smell

To carry out a pattern analysis of odors, we used an odor analyzer with a human sense of smell; this analyzer indicates not only the odor quality, i.e., pleasantness and unpleasantness in the pattern, but also the odor intensity. Conventional systems indicate only the intensity level of an odor, irrespective of its quality. This newly developed system can discriminate offensive from inoffensive odors by the shapes of graphic patterns. From a hexagonal radar pattern made by six unique semiconductor sensors, odor quality and intensity are obtained, the sharpness of radar pattern indicating the odor quality, while the area indicates odor intensity. An odor map can then be made from the odor quality and intensity obtained. Thus, various odors can be visually identified, and this procedure, rather than the human sense of smell, can be applied to classify various types of odors.