• Journal of the Korean Applied Science and Technology
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• v.11 no.2
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• pp.113-120
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• 1994

Amphoteric surfactants were synthesized by the cyclization of 1-(2-hydroxyethyl)-2-undecyl-2-imidazoline [I] with acrylic acid ethyl ester. Compound [I] was easily hydrolyzed with water, especially in the presence of a alkali, to afford amidoamines. After [I] was hydrolyzed, the reaction mixture was allowed to react with acrylic acid ethyl ester and then soapoinfied. Only sodium salts of N- -(2-carboxyethyl)-N'-(2-hydroxyethyl)aminoethyl]dodecanoyl amide[III] was obtained. However, when the reacton of [I] with acrylic acid ethyl ester was carried out in the presence of water, followed by soapnification, ring cleavage of [I] occurred at 2, 3 position, different from hydrolysis of [I] where the cleavage occurred at 1, 2 position, to give sodium salts of N-[N'-(2-carboxyethyl)aminoethyl]-N-(2-hydroxyethyl)dodecanoyl amide [IV] and N-[N', N'-bis(2-carboxyethyl)aminoethyl]-N(2-hydroxyethyl)dodecanoyl amide [V] as main products.

• Journal of the Korean Applied Science and Technology
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• v.29 no.1
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• pp.47-53
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• 2012

This study is concerned with coemulsifier which is better emulsifiable properties than emulsifier itselves' use only. It's compound was synthesized by esterification of propylene glycol and succinic acid. The structure of them was comfirmed with FT-IR and $^1H$-NMR. Surface active properties with surface tension, cmc, emulsing power were tested respectively at given conditions. Their surface tensions in the aqueous solution was decreased to 33-35 dyne/cm and their cmc was evaluated by surface tension method. And it's emulsifying power was excellent in jojoba oil. As results, the synthesized dipropylene glycol succinate is expected to apply as O/W coemulsifier.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.101-104
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• 1996

During the screening of inhibitor of DNA topoisomerase I from microbial secondary metabolites, Streptomyces melanosporofaciens 7489 which was capable of producing high level of inhibitor was selected from soil. The active compound (7489-1) was purified from the culture broth by solvent extraction, silica gel column chromatography and HPLC. The inhibitor was identified as dibutyl phthalate by spectroscopic methods of UV, $^{1}H$-NMR, $^{13}C$-NMR, DEPT and EI-MS. 7489-1 showed a strong inhibitory activity against topoisomerase I with 10 ${\mu}$M of $IC_{50}$ value.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.81-85
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• 2002

Oligotrophic bacteria isolated from forest soil showed a specific community consisting of various taxonomic groups compared with those in other soil or aquatic habitats. Based on the cell shape, the isolates were divided into four groups: regular rod, curved/spiral rod, irregular rod, and prosthecate bacteria. The cellular fatty acids 60 oligotrophic isolates were analyzed. At the dendrogram based on cellular fatty acid composition, four clusters(I-IV) were separated at a euclidian distance of about 50. Based on the 16S rDNA sequence analysis, the two representative strains(MH256 and MA828) of cluster 3 showed the close relation to genera, Xathomonas/Stenotrophomonas, but were not included in these genera. The isolates with Q-10 were also studied. They are corresponded to the two large groups in Proteobacteria alpha subdivision. One was incorporated in the genus Bradyrhizobium cluster, which also includes Agromonas, a genus for oligotrophic bacteria. The strains of the other group showed high similarity to the genus Agrobacterium. We attempted to screening of bioactive compounds from oligotrophs which was isolated from forest soil. The active compounds were analyzed by mass and NMR spectrum, one of them identified as crisamicin A. Another one designated as SAPH is a new compound. The results indicate that there were possibilities for finding new compounds from the rare microorganisms such as oligotrophs.

• Journal of Power Electronics
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• v.16 no.2
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• pp.610-620
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• 2016

The compound active clamp zero voltage soft switching (CACZVS) three-phase power factor correction (PFC) converter has many advantages, such as high efficiency, high power factor, bi-directional energy flow, and soft switching of all the switches. Triple closed-loop PI controllers are used for the three-phase power factor correction converter. The control objectives of the converter include a fast transient response, high accuracy, and unity power factor. There are six parameters of the controllers that need to be tuned in order to obtain multi-objective optimization. However, six of the parameters are mutually dependent for the objectives. This is beyond the scope of the traditional experience based PI parameters tuning method. In this paper, an improved chaotic particle swarm optimization (CPSO) method has been proposed to optimize the controller parameters. In the proposed method, multi-dimensional chaotic sequences generated by spatiotemporal chaos map are used as initial particles to get a better initial distribution and to avoid local minimums. Pareto optimal solutions are also used to avoid the weight selection difficulty of the multi-objectives. Simulation and experiment results show the effectiveness and superiority of the proposed method.

• Journal of Electrochemical Science and Technology
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• v.7 no.2
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• pp.153-160
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• 2016

The inhibition ability of N,N-bis(2,4-dihydroxyhydroxybenzaldehyde)-1,3-Propandiimine (DHBP) as a schiff base against the corrosion of API-5L-X65 steel in 1 M HCl solution was evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy. Electrochemical impedance studies indicated that DHBP inhibited corrosion by blocking the active corrosion sites. The inhibition efficiency increased with increasing inhibitor concentrations. EIS data was analysed to equivalent circuit model and showed that the charge transfer resistance of steel increased with increasing inhibitor concentration whilst the double layer capacitance decreased. The adsorption of this compound obeyed the Langmuir adsorption isotherm. Gibbs free energy of adsorption was calculated and indicated that adsorption occurred through physical and spontaneous process. The corrosion inhibition mechanism was studied by potential of zero charge. Polarization studies indicated that DHBP retards both the cathodic and anodic reactions through adsorption on steel surface. Scanning electron microscopy was used to study the steel surface with and without inhibitor.

• Journal of the Korean Society of Tobacco Science
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• v.25 no.2
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• pp.160-166
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• 2003

The majority of ι-menthol is still obtained by freezing the oil of Mentha arvensis to crystallize the menthol present. This 'natural' menthol is then physically seperated by centrifuging the supernatant liquid away from the menthol crystal. But the price of natural ι-menthol has fluctuated widely so effort has been devoted to the production of ι-menthol by synthetic more readily available raw materials. In the 1970's, many researcher synthesised a new compounds with the menthol cooling effect. During this period many molecular structure designed and synthesised on concepts of correlation between structure and biological activity and the various types of molecule which give rise to cooling effect more than ι-menthol. Specially, N-alkyl-carboxamide group is substituted for the hydroxyl group in ι-menthol. Recently, the most active compounds synthesised is 4-methyl-3-(1-pyrrolidinyl)-2-[5H]-furanone. This compound is 35 times more powerful in the mouth and 512 times more powerful on the skin than ι-menthol. The cooling effect also lasts twice as long. While not yet commercially available, it is expected that these types of materials will be subjected to toxicological studies and will soon be sell on the market.

• Natural Product Sciences
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• v.20 no.2
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• pp.126-129
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• 2014

Bioactivity-guided investigation on whole plant of Euphorbia supina, using LPS-induced Raw264.7 cells, led to the identificaiton of a tannin which was not reported from this plant along with four known constituents (quercetin, astragalin, juglanin and methyl gallate). The structure of the tannin was determined as corilagin by the interpretation of NMR (1D and 2D) and MS spectroscopic data. All the isolates were tested for the inhibitory activity against NO production in LPS-induced Raw264.7 cells. Among the tested isolates, corilagin was found to be the most active compound.

• Food Science and Biotechnology
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• v.14 no.6
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• pp.832-835
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• 2005

Inhibitory activity of active compound isolated from Ruta chalepensis leaf was examined against alcohol dehydrogenase and, upon comparison to those of four commercially available compounds (quinoline, quinoline-3-carboxaldehyde, quinoline-3-carboxylic acid, and quinoline-4-carboxylic acid) and 1,10-phenanthroline as alcohol dehydrogenase inhibitor, was characterized as quinoline-4-caboxaldehyde by spectral analyses. Inhibitory effects ($IC_{50}$) of quinoline-4-caboxaldehyde and quinoline derivatives varied depending on chemicals and concentrations used. The $IC_{50}$ values of quinoline-4-carboxaldehyde, quinoline-3-carboxaldehyde, quinoline, quinoline-3-carboxylic acid, and quinoline-4-carboxylic acid were 0.04, 0.3, 0.8, >1, and >1 mg/mL, respectively. These results suggest inhibitory action of quinoline-4-carboxaldehyde against alcohol dehydrogenase as prospective therapeutics for treatment of alcoholic liver diseases such as alcohol hepatitis and cirrhosis resulting from chronic alcohol abuse.

• Food Science and Biotechnology
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• v.14 no.5
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• pp.685-688
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• 2005

Antibacterial and antiplatelet activities of Acorus gramineus rhizome-derived asaronaldehyde and asaron were analyzed using platelet aggregometer and six human intestinal bacteria. Active constituent of A. gramineus rhizome was isolated and characterized as asaronaldehyde by spectral analyses. At 2 and 1 mg/disk, asaronaldehyde exhibited strong inhibition of Clostridium perfringens and C. difficile without adverse effects on growth of beneficial bacteria such as Bifidobacterium bifidum, Lactobacillus acidophilus, and L. casei. Asaron also revealed moderate growth inhibition against C. perfringens and C. difficile at 2 mg/disk, no growth-inhibiting activity was observed on B. bifidum, L. acidophilus, L. casei, and E. coli. At 50% inhibitory concentration ($IC_{50}$) value, asaronaldehyde was effective in inhibiting platelet aggregation induced by collagen ($IC_{50}$, $27.6\;{\mu}M$) and arachidonic acid ($IC_{50}$, $53.7\;{\mu}M$). These results suggest asaronaldehyde may be useful as lead compound for inhibiting platelet aggregation induced by collagen and arachidonic acid.