鄭廣洙

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鄭敎民

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Increasing the oil volume in the oil: water mixtures using isopropyl myristate, oleic acid as oils, the solubilities of methyl, propyl and butyl parabens and the MICs (minimum inhibitory concentrations) to E. coli were increased. But in liquid paraffin, the solubility was reversed. The relation between MIC and solubility of parabens had constant factor of 0.7 as saturation fraction percent. The solubility of methyl paraben was crossed over in those of propyl and butyl parabens, when the oil volume was increased. When the oil was used over the cross-over point, methyl paraben was useful to preserve the systems, and below the cross-over point the more lipophilic propyl and/or butyl parabens were effective.

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Ji-sun Kim , Chang-kew Kim , Pill-soon Song

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李玉燮 , 金點植

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Tallow fatty acid consists of mixtures of fatty acids differing in chain length and saturation. In separation of tallow fatty acid, the effects of the type and concentration of detergents and electrolytes were studied. And the changes of acid composition of particular fractions were determined by gas-chromatography. Sodium lauryl sulfate (SLS), sodium lauryl ether sulfate (SLES) and sodium lauryl benzene sulfonate (SLBS) were used as detergents and NaCl, Na₂SO₄ and MgSO₄ were used as electrolytes. At low concentration of detergent, the tallow fatty acid was not fully wetted, and at high concentration, the emulsion was so stable that the tallow fatty acid was not well separated. The addition of proper amount of electrolyte increased the separation efficiency by the decrease of interfacial tension and by the increase of the amount of adsorbed detergent on the surface of solid fatty acid crystals. The optimum range of detergent was 0.4-0.6% (wt.) in SLS, 0.2-0.4% in SLES and 2.0-3.0% in SLBS. And the optimum range of electrolyte was 2.0-2.5% in NaCl, 3.04.0% in Na₂SO₄ and 0.5-1.0% in MgSO₄ respectively.

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Young Chul Hur , Byung Yul Moon , Young Kook Kim

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The comparative detergency of sodium dodecyl sulfate (SOS) solution near the first critical micelle concentration (CMC) was measured by means of a ¹³¹I-labelled castor oil as a soil. More than 95% radiochemical purity of ¹³¹I-labelled castor oil was obtained using potassium Iidide as a carrier. Polyester test fabric was soiled with ¹³¹I-labelled castor oil, and washed in a conventional washing apparatus mounted on appropriate devices. Fabric radioactivities were measured before and after washing by a scintillation counter. Near the first CMC, the detergency of SOS was increased with decreasing of surface tension of SOS. It was also shown that ¹³¹I-labelled castor oil was useful for studying the detergency of SDS.

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金昌奎

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Rheology of gels prepared with stearyl dimethyl benzyl ammonium hectorite (SDBAH) and various polar additives in n-butyl acetate was investigated by measuring the viscosity and rheogram. Including generally recognized polar additives, additional studies on the rheogram and viscosity were made with ether-type methyl cellosolve and carbitol, with dimethyl sulfoxide (DMSO) having sulfonyl group, and furthermore with above-mentioned polar additives containing small quantity of water. It was observed that molecular size, dipole moments and dielectric constants of polar additives had a great influence on viscosity increase and rheology of SDBAH gel, and the increase of SDBAH interlayer spacing was important factor in gel formation and viscosity change. It was also shown that thixotropy effect was increased with the increase of polar additive concentration, finally changed to rheopexy from thixotropy as the concentration of polar additives was increased more than about 40% of SDBAH weight. In addition thixotropy changed to rheopexy as the increase of shear rate. It was further found that the aqueous solutions of polar additives (water content, 5-25%) had more effects on rheology than additives without water, and particularly 95% DMSO solution was the most effective. And the optimum concentration of polar additives showing maximum viscosity in the same SDBAH concentration system was examined.

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朴秀男 , 李泰寧

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¹O₂ quenching abilities of several carotenoids which contain hydroxy, carbonyl and ester groups were compared quantitatively with /3-carotene, and the capacity of the quenching was interpreted in the light of electronic effects. The rate constans of ¹O₂ quenching of lutein diester and astaxanthin diester in MeOH solution were shown to be 1.9 x 10¹⁰ M^-1 Sec^-1, 2.3 x 10¹⁰ M^-1 Sec^-1 respectively. Under the experimental conditions, and within the carotenoid tested results, the larger the resonance energy is, the larger becomes the rate constant and consequently the lower the transition energy is, the better becomes the quencher.

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