• Applied Chemistry for Engineering
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• v.8 no.5
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• pp.777-783
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• 1997

$TiO_2$ powders were synthesized via hydrolysis reaction of titanium n-propoxide in n-propanol solvent and the reaction rates were studied by use of UV-vis spectroscopic method. Concentration of water, reaction temperature, reaction time and acid-base effects of the solution were investigated to determine the optimum conditions for $TiO_2$ powder synthesis. The reaction were controlled to proceed to pseudo-first orders reaction in the presence of excess water in n-propanol solvent. The rate constants which varied with temperature and concentration of water were calculated by Guggenheim method. Reaction using $D_2O$ was also carried out to determine the catalytic character of water. $TiO_2$ powders were synthesized only in the neutral and basic solution and those were almost spheric forms having average particle size of $0.4-0.7{\mu}m$ diameter. Particle size decreased with increasing concentration of water and reaction temperature, however, increased with increasing reaction time. Associative $S_N2$ mechanism for the hydrolysis was proposed from the data of n-value in the transition state and thermodynamic parameter. $D_2O$ solvent isotope effect showed that $H_2O$ molecules reacted as nucleophilic catalysis.

• Journal of the Korean Chemical Society
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• v.13 no.2
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• pp.141-147
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• 1969

Organophosphorous compounds can be reduced by zinc metal in acidic solution after alkaline hydrolysis. Although phosphates and phosphonates did not evolve any gas, dithioates did evolve hydrogen sulfide and phosphine, thionates and thiolates did evolve only hydrogen sulfide. The evolved gases were qualitatively detected by means of lead acetate and silver nitrate or mercuric bromide papers and determined by spectrophotometrically. The reduction mechanism and analytical method of dithioates were proposed.

• Journal of the Korean Chemical Society
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• v.41 no.7
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• pp.362-365
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• 1997

• Bulletin of the Korean Chemical Society
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• v.11 no.2
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• pp.105-108
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• 1990

A spectroelectrochemical study on the redox chemistry of polyaniline (PANI) was carried out by using indium-tin oxide (ITO) transparent electrode in aqueous acidic solutions. Three different PANI-derived species were observed depending on the potential. The most highly oxidized species having alternating benzenoid-quinoid structures degraded through hydrolysis reaction. The degradation products were confirmed to be p-benzoquinone (BQ) and p-diaminobenzene (PDAB) by spectrophotometry anld potentiostatic experiments. Finally, a degradation mechanism is deduced from the observed behaviour.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.319.2-319.2
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• 2002

Chitin is a major component of the shells of crustacea such as crab. shrimp and crawfish. Renal dipeptidase (RDPase. EC 3.4.13.19), an ectoenzyme of renal proximal tubules. is covalently bound to outer leaflet of lipid bilayer via glycosylphosphatidylinositol (GPI)-anchor. The biological role of RDPase was suggested as the hydrolysis of dipeptide into free-amino acids before renal reabsorption. The underlying biochemical mechanism of decreased RDPase release was suggested as nitric oxide (NO) production. (omitted)

• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1098-1105
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• 2007

Quantum mechanical and molecular dynamics simulation analysis has been performed on the model system for CALB (Candida antarctica lipase B) with esters to study the reaction mechanism and conformational preference of catalytic hydrolysis and the esterification reaction. Using quantum mechanical analysis, the ping-pong bi-bi mechanism was applied and energies and 3-dimensional binding configurations of the whole reaction pathways were calculated. Further molecular dynamics simulation analysis was performed on the basis of the transition state obtained from quantum mechanical study to observe the effect of structures of the substrates. Calculation results using substrates of different chain length and chiral configurations were compared for conformational preference. The calculated results showed very small influence on chain length, whereas chiral conformation showed big differences. Calculated results from molecular modeling studies have been compared qualitatively with the experimental data using racemic mixtures of (${\pm}$)-cis-4-acetamido-cyclopent-2-ene-1-ethyl acetate as substrates.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2673-2678
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• 2014

The detailed mechanisms of the efficient $\small{L}$-proline and pyrrolidine catalyzed transamidation of acetamide with benzylamine have been investigated using density functional theory (DFT) calculations. Our calculated results show: (1) the mechanisms of two catalytic cycle reactions are similar. However, the rate-determining steps of their reactions are different for the whole catalytic process. One is the intramolecular nucleophilic addition reaction of 1-COM, the other is hydrolysis reaction of 2-C. (2) COOH group of $\small{L}$-proline is essential for efficient transamidation. The computational results are in good agreement with the experiment finding and mechanism resported by Rao et al. for $\small{L}$-proline-catalyzed synthesis of amidesin good to excellent yields.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.221-222
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• 2009

The results showed that the addition of VAE polymer strongly reduces the $Ca(OH)_2$ formation, being this result attributed to reduce degree of cement hydration caused by different ion elution amount of polymer modified cement pastes and interaction between acetate anion from the partial hydrolysis of co-polymer and Ca$^{2+}$ion from OPC hydration.

• YAKHAK HOEJI
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• v.31 no.5
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• pp.280-285
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• 1987

There are three plausible bioconversion pathways in biodegradation mechanism of capsaicinoids; first, side chain degradation through $\omega$-hydroxylation and $\beta$-oxidation, secondly, aromatic ring hydroxylation, and lastly, hydrolysis on the acidaraide linkage. In microbes, it was reported that capsaicin and its synthetic, analog, nonoylvanillylamide(NVA), could be metabolized to N-vanillylcarbamoylbutyric acid via $\omega$-hydroxylation and consecutive $\beta$-oxidations by Aspergillus niger. In order to broaden the scope of microbial degradation of capsaicinoids, over thirty strains of various fungi including Aspergillus, Penicillum, Mycotypha, Gliocladium, Paecilomyces, Byssoclamys, Conidiobolus, Thamnidium, and Entomophthora. It was observed that almost all the strains examined oxidized, the side chain of capsaicids as A. niger did. These observations strongly support the notion that side chain degradation is the most dominant pathway in the microbial degradation of capsaicinoids.

• Microbiology and Biotechnology Letters
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• v.18 no.1
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• pp.39-43
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• 1990

The inhibitor had the inhibitory activities against hydrolysis of PNPG, sucrose and ONPG by $\alpha$-Dglucosidase, $\alpha$ - and $\beta$ -galactosidase, but it did not inhibit amylases and other carbohydrases. Kinetic studies exhibited that the inhibitory substance non-competitively inhibited the enzyme reaction with a Ki value of 118 $\mu$g/m$\ell$, and enzyme-inhibitor complex was formed slowly.