• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.958-963
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• 1995

The hydrolysis of pen shell by-product by the APL $440^{TM}$, selected as the suitable alkaline protease on the basis of cost per unit enzyme activity, was optimized using response surface methodology(RSM). A model equation obtained from the results of RSM could be used for the prediction of degree of hydrolysis(DH) as follows: $%DH=51.126+2.419\;pH+2.415T-2.426S-2.846pH^2-4.211T^2-3.014t^2+2.419S^2$. From the ridge analysis, the conditions favoring the highest degree of hydrolysis were pH 10.2, $61.4^{\circ}C$, 2.58 hrs reaction time, 30.9% substrate concentration, and 0.32% enzyme/substrate ratio. The effect of autolysis affecting degree of hydrolysis in pen shell by-product was negligible. Hydrolysate produced under the optimal condition increased 3.5 times and 7.7 times in amino nitrogen and salinity, respectively, comparing with raw pen shell by-product.

• 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.22 no.3
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• pp.164-172
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• 1978

Carboxypeptidase A-catalyzed hydrolysis of ester substrates was carried out at room temperature in the presence of a number of external reagents. If the acyl-enzyme intermediate, an anhydride, is attacked by the external reagents, products formed by trapping at the acyl portion or at the enzyme portion of the anhydride group can be obtained. Examination of the uv/vis spectral properties of the reaction products and of changes in enzyme activity indicated that such trapping reactions did not occur. Also performed was evaluation of enzymatic rate parameters for the the hydrolysis of O-(o-hydroxyphenylacetyl)-L-${\beta}$-phenyllactate. Detection of 2-coumaranone possibly formed by attack of the o-hydroxy group as an intramolecular trapping group at the acyl-enzyme intermediate was tried, but no evidences for the intramolecular trapping reaction were obtained. Failure to trap the intermediate was discussed in terms of steric hindrance imposed on the approach of the trapping reagents to the anhydride group of the acyl-enzyme intermediate and of the fast enzymatic breakdown of the intermediate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3261-3266
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• 2012

Sodium borohydride($NaBH_4$) known as the material of hydrogen generation and storage can produce the hydrogen via catalytic hydrolysis. This protide chemical could be used in the hydrogen supply system for residential and mobile fuel cells, and thus many researches and developments regarding to these chemicals and decomposition reactions have been implemented. We experimented the hydrolysis of $NaBH_4$ alkaline solution by metal oxide-supported PGM(platinum group metal) catalysts and measured the generation rate of hydrogen which is product of decomposition reaction. We compared oxides as catalyst supports, and the precious metals, Pt and Ru for the catalysts and studied the effects of amounts of catalyst added and $NaBH_4$ concentrations on the hydrogen generation rates and patterns.

• Polymer(Korea)
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• v.29 no.3
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• pp.304-307
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• 2005

The acid-catalyzed hydrolysis reaction of poly(vinyl acetate) (PVAc) in water/acetic acid solution at $35^{circ}C$ was studied at two different solvent compositions. The mole fractions of vinyl acetate (Vac) and vinyl alcohol (VA) during the course of the reaction were determined by NMR, and the equilibrium constant $K_{eq}$ of the reaction was determined using the molar ratio of VAc to VA at the chemical equilibrium. $K_{eq}$ was 0.75 (${\pm}0.01$) when the VAc mole faction at the equilibrium was 0.78 (${\pm}0.01$) and it was 0.69 (${\pm}0.01$) when the VAc mole fraction was 0.57 (${\pm}$0.02). The reaction was found to be a pseudo 1-st order reaction with the rate coefficient at $3.4{\times}10^{-6}/sec$.

• KSBB Journal
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• v.6 no.4
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• pp.327-336
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• 1991

A study on the optimum hydrolysis conditions of fish skin through the aid of enzymes and the development of a natural seasoning using the hydrolysate has been carried out for the effective utilization of fish skin. Using the "pH-drop" techniques the collagenase and pronase were identified as most suitable for this purpose. The $K_m$ and $V_{max}$ values of pronase were 1.82 mgN/ml and 0.06 mgN/mL/min, respectively. The hydrolysis conditions of the cod skin for the pronase were as follows: reaction temperature, $50^{\circ}C$; reaction time, 3hrs; pH 6; enzyme concentration, 0.03%. The degree of hydrolysis at these conditions was 76.8%. But after hydrolyzing cod skin with collagenase for 1hr, when the pronase was treated, the degree of hydrolysis was 83.13%. The molecular weight of the hydrolysate was 8,000 daltons. Among the amino acids in the hydrolysate, glycine(27.95%), glutamic acid(10.94%), proline(7.39%), aspartic acid(9.47%) and serine(7.39%) were responsible for 64.23% of the total amino acids. But valine, methionine, isoleucine, leucine, phenylalanine and histidine having a bitter taste were only 13.05%. From the results of the sensory evaluation, the imitation sauce which was made of 20% fermented soy sauce prepared from the hydrolysate was at least similar to the traditional soybean sauce in product quality. The complex seasoning containing 31.7% of the hydrolysate was nearly equal to complex seasonings on the market, too.

• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1295-1303
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• 1997

This study determined the effects of addtition of chicory extract on the rate of starch hydrolysis in vitro and blood glucose response in healthy subjects. The rate of corn starch hydrolysis in the presence or absence of chicory extract was determined in an in vitro enzyme/dialysis system for 2hr. Additions of dried or roasted chicory extract (5%, w/w) to corn starch solution reduced the starch hydrolysis and significantly (p<0.05) decreased the area under hydrolysis curve by 16% and 18%, respectively. Groups of five to nine volunteers underwent 60 g glucose tolerance tests (GTT) with 2.5, 5, 10, 20% (w/w) dried or roasted chicory extracts. The addition of chicory extracts significantly (p<0.05) reduced blood glucose concentration during the GTT and reduced the mean peak rise and area under blood glucose curve. The glycemic indices of all dried chicory extract, $5{\sim}20%$ roasted chicory extract groups were significantly decreased compared with glucose control. Chicory extract is therefore likely to be useful in modifying postprandial hyperglycemia.

• Journal of the Korean Chemical Society
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• v.43 no.1
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• pp.85-91
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• 1999

The second order rate constants for the hydrolysis of substituted phenyl N,N-diethyl-P-benzylphosphonamidates (2,4-$(NO_2)_2$, 4-$NO_2$, 4-CN, 4-Cl, 4-H)in 20% dioxane-water (v/v) have been determined by UV/Vis spectrophotometric method at various temperatures. The activation parameters (Ea, ${\Delta}H^{\neq}$,${\Delta}S^{\neq}$) were calculated from the rate constants and the reaction constant ($\rho$) was also estimated by Hammett equation. The activation entropies of the title reactions show considerably negative values, this result is not consistent with a dissociative mechanism (EA) in which a positive or a slightly negative value of the entropy of activation should be expected. Further, kinetic evidence for an associative mechanism (AE) was obtained from the linear free energy relationship. By the results of kinetic study for the alkaline hydrolysis of substituted phenyl N,N-diethyl-P-benzylphosphonamidates, it may be concluded that these reactions proceed through an associative mechanism.

• KSBB Journal
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• v.13 no.1
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• pp.90-95
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• 1998

Experiments on the process development for the concentration of polyunsaturated fatty acid (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil by using acyl chain specificity of Candida cylindracea lipase were performed. Five kinds of oils were hydrolyzed with Candida cylindracea lipase. Among then, Candida cylindracea lipase just had low activity on the PUFAs-rich fish oil. After the hydrolysis of fish oil, free fatty acid was removed and fatty acid components of glyceride mixtures were analyzed. When the hydrolysis was about 70%, the DHA content in the glyceride mixture was about three times more than that in the original fish oil. The EPA and stearidonic acid contents in the glyceride mixtures, however, were similar to that of the original fish oil. In this work, these results showed that the concentration process of PUFAs by using the acyl chain specificity of Candida cylindreacea lipase was effective in producing glycerides that contained a high concentration of PUFAs in good yield.

• Polymer(Korea)
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• v.35 no.4
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• pp.302-307
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• 2011

The parameters of silanol formation reaction of organosilane including solvent type, solution concentration, pH and hydrolysis time influence the adhesion property of 2 layer flexible copper clad laminate (FCCL). Especially, the hydrolysis reaction time of silane coupling agent affects the formation of the silanol groups and their self-condensation to generate oilgomeric structure to enhance the surface treatment as an adhesive promoter. In our study, we prepared the binary silane coupling agents to control hydrolysis reaction rate and surface energy after treatment of silane coupling agents for increasing the adhesive property between a copper layer and a polyimide layer. The surface morphology of rolled copper foil, as a function of the contents of the coated binary silane coupling agent, was fully characterized. As fabricated 2-layer FCCL, we observed that adhesive properties were changed by hydrolysis rate and surface energy.