Shinsuke Yamazaki

Surface active properties of biosoap from spiculisporic acid

Abstract Penicillium spiculisporum produces 4,5-dicarboxy-4-pentadecanolide (spiculisporic acid, S-acid) efficiently from glucose. Three kinds of sodium salts of S-acid were prepared. As a result of potentiometric titration, IR, and 13C NMR, it was concluded that the monosodium salt of S-acid (S-1Na) consisted mainly of the neutralizing product of the carboxylic group attached to the 4-positioned carbon of S-acid, the disodium salt of S-acid (S-2Na) corresponded to the neutralizing product of the carboxylic group attached to the 4- and 5-positioned carbons, and the trisodium salt of S-acid (S-3Na) was the saponified product of the lactone group of S-2Na. The micelle formation of these three kinds of S-acid salts was ascertained in water by means of both surface tension and electrical conductance measurements. And, the CMC values were S-1Na, 3.9 × 10−3; S-2Na, 6.1 × 10−2; and S-3Na, 1.7 × 10−1 mole/liter, respectively. These three salts showed low foaming properties, with S-2Na having the highest foaming property of the three. Further, these showed a dispersing action for hydrophilic pigments, as well as showing both calcium ion sequestration and buffering actions. It will be a future theme to study the connection with the biological function of S-acid from the viewpoint of biosurfactant.

Electrical control of reversible microgel flocculation and its estimated performance as a display device

Abstract Reversible flocculation of pH-responsive microgels with poly-L-lysine was electrically controlled by a pH modulator. The pH modulator was composed of a polypyrrole-coated Pt electrode coupled with an Ag/AgCl counter-electrode. The applicability of the flocculation system for display devices was examined to determine whether its performance was comparable with that of conventional display devices. A display performance of contrast 50 in 50 ms with operating potentials of ±0.4 V will be attained in a proposed cell where vertical microelectrode arrays are built in.