• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.309-314
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• 2003

In order to find out the microscopic environmental information on the nonionic reverse micelle of Triton X-100/n-hexanol/water in cyclohexane, an absorption and fluorescence spectroscopic study has been conducted using a methylene blue(MB). The information on the microscopic states of water in the polar core of the reverse micelle has been found by investigating complex formation and solvatochromic behavior between MB and Triton X-100. As a result, it was found that there exist three states in the polar core of the reverse micelle. The measured values of $W(=[H_2O]/[Surf])$ for the three states of water are 0.71, 4.98, and 7.26, and the corresponding lifetimes of MB are $15.45 ns{\pm}0.56$, $12.27 ns{\pm}0.79$, and $8.28 ns{\pm}0.82$, respectively.

• Applied Biological Chemistry
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• v.36 no.5
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• pp.326-331
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• 1993

Three antioxidants were isolated: (-)-epigallocatechin and (-)-epigallo catechin gallate from Theae Folium generally called green tea, and gallic acid from Moutan Cortex. They inhibited $Fe^{3+}-ADP/ascorbate-induced$ lipid peroxidation in rat liver microsomal fraction, showing $IC_{50}$, the concentration of antioxidants which is required to inhibit 50% of the peroxidation for microsomal membranes at 1 mg protein/ml, to be $0.2\;{\mu}g/ml$, $0.4\;{\mu}g/ml$ and $2.5\;{\mu}g/ml$, respectively.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.466-471
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• 1994

The polymeric titania sol was prepared via partial hydrolysis of titanium isopropoxide and its characteristics were investigated. The effect of solvent, catalyst and water content on the sol stability was investigated. The shear viscosities of sol solution at different temperatures were measured to determine the gel time. Employing the spin coating technique, optically clear and transparent titanium oxide thin film was fabricated. Even after doped with second-order nonlinear optical(NL0) active monomers, the film quality was maintained very homogeneous. The film was corona-poled under 3~ 5kV at 50~$100^{\circ}C$ range. The electro-optic coefficient, $r_{33}$ was measured to be 1.5~5pm/V using the wavelength, 632.8nm from He-Ne laser.

• Polymer(Korea)
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• v.26 no.3
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• pp.400-409
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• 2002

Polyurethane microcapsules containing functional oil (citronella oil) were successfully prepared by conventional interfacial polymerization of tolulene 2,4-diisocyanate (TDI) and ethylene glycol (EG) and characterized by Fourier transform (FT-IR) spectroscopy, Ultraviolet spectroscopy, particle size analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Tile effects of polymerization variables, such as surfactant concentration and agitation speed, on the particle size and particle size distribution were investigated. FT-IR spectroscopic data showed that citronella oil was successfully encapsulated in the microcapsule. Thermogravimetric analysis data showed that the microcapsule was thermally stable up to $220^{\circ}C$. The controlled release of the citronella oil present in the microcapsule core in a methanol medium was demonstrated by ultraviolet spectroscopy showing that the amount of released citronella oil was increased with increasing time. It was observed that the amount of released citronella oil was increased with increasing stirring speed and emulsifier concentration in the rnicrocapsule preparation step. Polyurethane microcapsules containing citronella oil showed excellent anti-moth property.

• Applied Biological Chemistry
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• v.36 no.4
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• pp.310-314
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• 1993

High performance liquid chromatographic method using a TSK-gel amide 80 column and isocratic elution with acetonitrile-water (63 :35 ;v/v) mixture was used for the separation and the quantitation of fructo (GF2-GF7)- and inulo-oligosaccharides (F2-F4). Retention time of each standard carbohydrate was highly reproducible. Standardization curves obtained by plotting the peak areas against the amounts of each carbohydrate showed very high coefficient of determination$({\ge}0.9884)$ and similar slopes, and a wide range of y-intercepts. Our results suggest the use of each Pure oligosaccharide for its own standardization curve instead of using a certain carbohydrate as an internal standard.

• Applied Biological Chemistry
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• v.23 no.3
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• pp.173-177
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• 1980

The anti-oxidant components in Panax ginseng, which were known to have antiaging effect, were fractionated by various solvents and then isolated by the preparative thin layer chromatography. A developing system with silicagel G using toluene-chloroform-actene (20 : 13 : 13) as mobile phase was applied. The components were investigated the anti-oxidant activity by ${\alpha}$, ${\alpha}'-diphenyl-{\beta}-picrylhydrazyl$ (DPPH) at 517nm. Two effective components were obtained from red ginseng and were indophenol reducing substances.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.73-79
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• 1968

The resolving capacities of xanthophyll pigments on thin-layers of Silica Gel, Hyflo super-Cel, and Micro-Cel C with varying concentrations of acetone in petroleum ether as the developing solvent were compared. The results showed that the resolving capacity of Micro-Cel C thin-layer was superior to others and satisfactory for the separation of leaf carotenoids in clearly separated six bands; carotenes, lutein-zeaxanthin, antheraxanthin, violaxanthin, an unidentified band, and neoxanthin, when it was developed with $13\%$ acetone-petroleum ether solution for 15 to 20minutes in an unsaturated chamber. Adhension of Micro-Cel C to glass was adequate without binder. Calcium sulfate used as a binder appeared to inactivate the resolving capacity of Micro-Cel C. Removing an about 0.2cm-wide layer on bo side of thin-layer slide helped to prevent 'edge effect' which gave tailing and faster solvent ascending along the side than the center. An adequate thickness of thin-layer was obtained when a 3 ml aliquot of the suspension in which l0g powdered Micro-Cel C was suspended in 75 ml distilled water was coated on a $2\times20cm$ glass slide.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.510-516
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• 1997

O/W emulsions were prepared by adding water to the solution containing amphiphilic resin and the mixed emulsifier of cetyl alcohol polyoxyethylene(20) sorbitan monooleate. Phase behavoir of these emulsions was studied at various HLB(Hydrophilic Lipophilic Balance) values and temperatures. The polar oil emulsion containing the amphiphilic resin showed improved phase stability at various temperatures. Model compounds which contain one of the functional groups in the amphiphilic resin were used in the polar oil phase in order to study the effect of interaction between the functional group and the emulsifier on the phase stability of emulsion. These model compound emulsions showed the phase stability order of poly(acrylic acid)

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.216-223
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• 1986

Separation of optical isomers of DNS derivatized amino acids by a reversed-phase high-performance liquid chromatography has been studied by adding a complex of an optically active amino acid (L-arginine) with the metal ion (Cu(II), Zn(II), Cd(II), Ni(II)) to the mobile phase. The separations are affected by the concentrations of acetonitrile, chelate and buffer. They are also affected by the pH and the kinds of metal and buffer. A separation mechanism, which is based on steric effect of the ligand exchange reaction for the formation of ternary complexes by the D,L-DNS-amino acids and the chiral additive associated with the stationary phase, is proposed to interpret the elution behaviors of D, L-dansyl-amino acids.

• Elastomers and Composites
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• v.34 no.4
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• pp.350-359
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• 1999

Conversion and oil-yield of a used automotive tire sample in supercritical decomposition and extraction for three solvents such as water, 28% ammoina solution and ammonia, were compared. Supercritical extraction with ammonia gave the highest conversion and oil-yield at the same temperature and pressure. In this paper, supercritical ammonia was used as major solvent and tetralin acting as hydrogen-donor, was used as cosolvent. As the amount of tetralin increased, oil-yield was Increased. When a tire sample was extracted by supercritical ammonia, oil-yield was 48.8% at $280^{\circ}C$, 22.3MPa. But when the weight ratio of tetralin to tire sample (weight of tetralin/weight of tire sample) was 5, oil-yield was 61.2% at $280^{\circ}C$ and 22.3 MPa. These phenomena indicate that as radicals produced in supercritical decomposition become stable, the polymerization and the second decomposition of products may be inhibited. Supercritical extraction of a tire sample swollen by tetralin gave high oil-yield although the amount of tetralin was a little.