• Journal of the Korean Ceramic Society
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• v.45 no.7
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• pp.375-379
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• 2008

Redox behavior was observed in alkali alkaline earth silicate PDP (Plasma Display Panel) glass melts doped with sulfate and sulfide by square wave voltammetry (SWV). According to voltammograms produced at a temperature range of 1100 to $1400^{\circ}C$ and frequency range of 5 to 1000 Hz, both melts showed the same behavior in which there is one reduction peak at low frequency but another peak at an increase of frequency. Based on the frequency dependence of the peak current, self diffusivity of $S^{4+}$ was determined. Based on the temperature dependence of the peak potential, standard enthalpy (${\Delta}H^0$) and standard entropy (${\Delta}S^0$) for the reduction of $S^{4+}$ to $S^0$ were calculated.

• BMB Reports
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• v.35 no.3
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• pp.302-305
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• 2002

Kinetic and thermodynamic studies have been made on the effect of the inosine product on the activity of adenosine deaminase in a 50 mM sodium phosphate buffer, pH 7.5, at $27^{\circ}C$ using UV spectrophotometry and isothermal titration calorimetry (ITC). A competitive inhibition was observed for inosine as a product of the enzymatic reaction. A graphical-fitting method was used for determination of the binding constant and enthalpy of inhibitor binding by using isothermal titration microcalorimetry data. The dissociation-binding constant is equal to $140\;{\mu}M$ by the microcalorimetry method, which agrees well with the value of $143\;{\mu}M$ for the inhibition constant that was obtained from the spectroscopy method.

• Textile Coloration and Finishing
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• v.14 no.2
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• pp.85-85
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• 2002

The interaction between berberine and tannin in aqueous solution was investigated spectrophotometerically. The dyeing mechanism of silk fabrics (control and tannin treated silk fabrics) with berberine was based on thermodynamic parameters obtained from equilibrium adsorption experiments. In adsorption spectra of aqueous solution of berberine and tannin mixture two isosbestic points (328nm, 357nm) were found and the mole fraction of reaction of components was 1:1. Initial dyeing rates were increased and the diffusion of dye was more effective by tannin treatment. Without regard to tannin treatment the adsorption isotherm of berberine was the langmuir type except high temperature, 80℃. By tannin treatment the saturation dye uptake was increased, the increase of dye uptake appeared to be a result of entropy change rather than enthalpy change. All these results can be interpreted by the hydrophobic interaction between berberine and silk treated with tannin and it is reasonable to conclude that not only the ionic force, but also the hydrophobic interaction contributes to the binding of berberine and tannin treated silk treated with tannin.

• Textile Coloration and Finishing
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• v.14 no.2
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• pp.9-17
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• 2002

The interaction between berberine and tannin in aqueous solution was investigated spectrophotometerically. The dyeing mechanism of silk fabrics (control and tannin treated silk fabrics) with berberine was based on thermodynamic parameters obtained from equilibrium adsorption experiments. In adsorption spectra of aqueous solution of berberine and tannin mixture two isosbestic points (328nm, 357nm) were found and the mole fraction of reaction of components was 1:1. Initial dyeing rates were increased and the diffusion of dye was more effective by tannin treatment. Without regard to tannin treatment the adsorption isotherm of berberine was the langmuir type except high temperature, $80^\circ{C}$. By tannin treatment the saturation dye uptake was increased, the increase of dye uptake appeared to be a result of entropy change rather than enthalpy change. All these results can be interpreted by the hydrophobic interaction between berberine and silk treated with tannin and it is reasonable to conclude that not only the ionic force, but also the hydrophobic interaction contributes to the binding of berberine and tannin treated silk treated with tannin.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.492-501
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• 1994

This study is an analysis of the turbulent diffusion flame with swirl flow and the calculated results are compared with experimental data in case of various swirl numbers and air-fuel rations. The mathematical model is restricted to single-phase, diffusion controlled combustion with swirl flow. Values of local flow properties were obtained by solving appropriate differential equation for continuity, momentum, stagnation enthalpy, concentration, turbulence energy, dissipation rate of turbulence energy, and the mean square of concentration fluctuation. The method is proposed for calculating the local probability of chemical reaction based on the use of the probability density function for the mixture fraction.

• Bulletin of the Korean Chemical Society
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• v.21 no.4
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• pp.379-382
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• 2000

The temperature dependence of the kinetic parameters of the aspartase-catalyzed reaction has been examined in the direction of deamination. The pK1values at 37$^{\circ}C$, 25$^{\circ}C$, 16$^{\circ}C$ and 7$^{\circ}C$ were 6.2 $\pm$ 0.1, 6.3 $\pm$ 0.1, $6.7{\pm}0.3$ and 6.9 $\pm$ 0.3, respectively. On the other hand, the pK2 values at 37$^{\circ}C$,25$^{\circ}C$, 16$^{\circ}C$ and 7$^{\circ}C$ were 8.1 $\pm0.2$, 8.3 $\pm$ 0.2, 8.2 $\pm$ 0.3 and 8.0 $\pm$ 0.2,respectively. The enthalpy of ionization, DHion, calculated from the slope of pK1, are 6.0 $\pm$ 0.3 kcal/mol. These results validate the prediction that aspartase requires a histidine residue for a general base, and a cysteine (or having a carboxyl functional group) for a general acid.

• Bulletin of the Korean Chemical Society
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• v.16 no.6
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• pp.498-503
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• 1995

The adsorption behaviors of two major components purified, endo Ⅱ and exo Ⅱ, from Trichoderma viride were investigated using microcrystalline cellulose with different specific surface area as substrates. Adsorption was found to apparently obey the Langmuir isotherm and the thermodynamic parameters, ΔH, ΔS, and ΔG, were calculated from adsorption equilibrium constant,K. The adsorption process was found to be endothermic and an adsorption entropy-controlled reaction. The amount of adsorption of cellulase components increased with specific surface area and decreased with temperature and varied with a change in composition of the cellulase components. The maximum synergistic degradation occurred at the specific weight ratio of the cellulase components at which the maximum affinity of cellulase components obtains. The adsorption entropy and enthalpy for respective enzyme system increased with specific surface area increase. The adsorption entropy was shown to have a larger value with enzyme mixture.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.407-416
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• 2019

The criticical micelle concentration (CMC) was measured by using the UV-Vis method for the micellization of the ammonium type cationic surfactants (DTAB, TTAB, and CTAB) in the aqueous aniline solution. The enthalpy change (${\Delta}H^0$) and entropy change (${\Delta}S^0$) were calculated from the dependence of Gibbs free energy change (${\Delta}G^0$) on the temperature for micellization of the cationic surfactants between 290K and 314K. The effects of n-butanol and sodium chloride on the micellization of cationic surfactants were measured and compared with the other thermodynamic functions. All the free energy changes (${\Delta}G^0$) of the micellization were negative, all the enthalpy change (${\Delta}H^0$) were negative, and all the entropy change (${\Delta}S^0$) were positive values, respectively. The micelle formation of cationic surfactant in aniline solution is a spontaneous exothermic reaction, and the iso-structural temperature calculated from the thermodynamic values show that enthalpy and entropy contribution to the micellization are almost the same for the micellization of cationic surfactants

• Journal of the Korean Chemical Society
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• v.17 no.2
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• pp.73-79
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• 1973

The ultrasonic absorption of Dodecyl pyridinium bromide (D.P.B.) in aqueous solution has been measured at $20^{\circ}C$ over a range of frequencies between 0.1 mc and 90 mc and a range of concentrations from 5 to 100 mM. The excess absorption was observed only in the solutions the concentration of which was higher than the critical micellar concentration (c.m.c.) both in the presence and absence of salt. The excess absorption of sound and the relaxation frequencies obtained from the absorption curves show a discontinuity with the variation of the concentration of D.P.B. in the neighborhood of 60 mM. Other properties such as viscosity, conductivity and velocity of sound also exhibit such a change near the same concentration. It is concluded that a change in the properties of the micelles of D.P.B. occurs in the neighborhood of this concentration. The mechanism of the observed ultrasonic excess absorption in attributed to the reaction $M_2{\rightleftarrow}M_1+2Br^-$where$M_2$ and$M_1$are two types of micelles. The rate constants of forward and backward reactions are found to be $6.9 {\times} 10^5 sec^{-1)$and $6.7{\times}10^{10}sec^{-1}mole{-2}$ respectively. Some kinetic characteristics including free energy, enthalpy, entropy and activation energy were calculated.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1988-1992
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• 2010

4-Amino-1,2,4-triazole copper complex (4-ATzCu) was synthesized, and its thermal behaviors, nonisothermal decomposition reaction kinetics were studied by DSC and TG-DTG techniques. The thermal decomposition reaction kinetic equation was obtained as: $d\alpha$ / dt =$10^{22.01}$ (1-$\alpha$)[-ln(1-$\alpha$)]$^{1/3}$ exp($-2.75\times10^4$ /T). The standard mole specific heat capacity of the complex was determined and the standard molar heat capacity is 305.66 $J{\cdot}mol^{-1}{\cdot}K^{-1}$ at 298.15 K. The entropy of activation $({\Delta}S^{\neq})$, enthalpy of activation $({\Delta}H^{\neq})$, and Gibbs free energy of activation $({\Delta}G^{\neq})$ are calculated as 171.88 $J{\cdot}mol^{-1}{\cdot}K^{-1}$ 225.81 $kJ{\cdot}mol^{-1}$ and 141.18 $kJ{\cdot}mol^{-1}$, and the adiabatic time-to-explosion of the complex was obtained as 389.20 s.