Masato Hoshi

MICROWAVE DIELECTRIC ANALYSIS OF HUMAN STRATUM CORNEUM IN VIVO

The dielectric properties of the human skin stratum corneum (SC) in the frequency range higher than 107 Hz are not well understood because of the difficulty in selective scanning of the SC area in vivo. The present study was carried out to make clear factors responsible for the dielectric properties using a measuring system specially developed for the study of SC [S. Naito, M. Hoshi, S. Mashimo, Anal. Biochem. 251 (1997) 163-172]. We found that the dielectric properties of SC can be expressed by the linear combination of two relaxation processes and d.c. conduction. The faster relaxation is that of free water. The slower relaxation and d. c. conduction were analyzed using a model assuming interfacial polarization between dissimilar materials. We concluded that the polarization is the origin of the slower relaxation process because the experimental data could be well interpreted according to the above mechanism. We also concluded that the polarization of swelled SC locates at the interface between SC cells and the intercellular lipid layer, or at the interface between the lipophilic and the hydrophilic part of the lamellar structured intercellular lipid layer.

A method of measuring surface permittivity by microwave dielectric analysis

A method for controlling skin depth by microwave dielectric analysis using an open end cell is presented here. The correlation between the measured permittivity, the electric length of the cell, and the permittivity depth profile has been shown from time domain reflectometry measurements on a sample with known depth profile of permittivity. This skin depth controlling method is exceedingly useful for dielectric analysis of water in living organisms and related food products.

Elucidation of Softening Mechanism in Rinse-Cycle Fabric Softeners. Part 2: Uneven Adsorption-The Key Phenomenon to the Effect of Fabric Softeners.

We investigated the actual factor determining the softening effect of a fabric softener. The adsorption area of the softener on model cotton cloths and yarns was identified using bromophenol blue. There was almost no softener at the cross-points of the yarns in the cloth samples or in the inner part of the yarns. The softening performance was better when there was less softener at the cross-points of the yarns than when the yarns were evenly covered by the softener. Thus we conclude that the presence of softener at the cross-points of yarns is not a vital factor in the softening effect. In addition, more softener was found on the outer part of the yarn than the inner part, indicating gradation in the adsorption pattern of the softener. Thus, we propose that more softener is adsorbed on the exposed part of the yarn in a cloth, and the formation of a hydrogen-bonding network containing bound water is inhibited, thus softening the outer part of the yarn. However, the presence of a small amount of softener in the inner part of the yarn preserves the hydrogen-bonding network. Favorable elasticity, or bounce, of the yarns and cloth is realized when an appropriate amount of softener is used. Excess softener would reach the inner part of the yarn, reducing the diameter of the core part of the yarn, making the cloth appear wilted.

A new automated analysis system of polymers by pyrolysis GC.

各種家庭用製品中の多種多様の高分子を,熱分解キャピラリーガスクロマトグラフィーにより分析した後,自動的に高分子を検索することが可能な,全自動高分子同定支援システムの開発を試みた.検討の結果,熱分解された高分子の分離には,DB-17キャピラリーカラムが最適であることを見いだし,検出には水素フレームイオン化及び窒素,リン同時検出法を用いた.分離成分の同定には保持指標を用い,熱分解後に多数の同族体を与えるポリエチレンを保持指標計算のための基準物質とすることにより,良好な保持指標安定性を得ることができ,保持指標のデータベース化が可能となった.本分析法は,熱分解ガスクロマトグラフをパーソナルコンピュータとオンライン結合させることにより,完全に自動化することができた.