• Proceedings of the Korean Biophysical Society Conference
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• 1996.07a
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• pp.13-13
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• 1996

Aggregation of human $\alpha$$_1$-antitrypsin ($\alpha$$_1$-AT) during folding occurs both in vitro and in vivo. In vivo aggregates of mutant $\alpha$$_1$-AT such as $M_{malton}$ (Phe52 deleted) and Z (Glu342 longrightarrowLys) variants have pathological consequences. In order to analyze the process of $\alpha$$_1$-AT aggregation in detail, the folding-unfolding kinetics of $\alpha$$_1$-AT was examined by monitoring intrinsic Trp fluorescence and ANS binding. (omitted)

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.27-27
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• 2003

Conformations of the +5 to +13 charge state of ubiquitin ions have been studied in the gas phase by an Electron Capture Dissociation (ECD) mass spectrometry (MS) technique. This approach has showed that the conformations of the gaseous ions change from the compact to extended structures as the number of protons on the protein ions increases, consistent with previous collisional cross-section measurements by an ion-mobility MS. However, this observation is in contrast to that of the solution-phase where the unique native structure is usually found. The (un)folding stability and kinetics of these gaseous ions were further investigated experimentally using gradual blackbody-radiation or sudden laser-induced thermal heating, respectively. These studies have provided the evidence that the thermodynamics and kinetics of protein (un)folding in the gas phase are quite different from those of the native aqueous proteins.

• Archives of Pharmacal Research
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• v.8 no.1
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• pp.7-14
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• 1985

Membrane-coated tablet of isonicotinic acid hydrazide (INAH) which releases INAH at the zero-order kinetics was deveoped. It consisted of a soluble tablet core surrounded by a porous membrane which controls the diffusion rate. Tablet cores were prepared by compressing granules of INAH and polyvinyl chloride (PVC) dissolved in methyl ethyl ketone in which micronized sucrose were suspended. Diffusion rate of INAH from the tablet through the membrane was constant until the loaded INAH in the core was almost released. The rate was independent of pH of the dissolution medium. Water-soluble sucrose particles behaved as a poreproducing material in the water-insoluble PVC film coat. The pH independency of the rate was probably due to the high solubility of INAH in the water of wide pH range. The diffusion rate of INAH could be controlled by chnaging the composition of the membrane or the coat weight. This membrane-coated INAH tablet seemed to be a powerful candidate for the controlled release drug delivery system (DDS) of INAH or other highly watersoluble drugs.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.993-999
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• 2011

The photoreactive prepolymers with multifunctional cinnamate and bisphenol Atype cinnamate groups that could perform photodimerization without photoinitiators were synthesized by the reaction of t-cinnamic acids (CAs) and epoxy resins. Their photocure reaction rates and the extent of reaction conversion were measured with Fourier transform infrared spectroscopy, and these increased with the intensity of UVirradiation. The experimental data of these reaction rates showed the characteristics of nth-order kinetics reaction, and all kinetic constants of each photoreactive polymer with this equation were summarized. Although the GTR-1800-HCA and KWG1-EP-HCA with hydroxyl group substituted cinnamate showed lower reaction conversion rates and rate constant than GTR-1800-CA and KWG1-EP-CAwith an unsubstituted cinnamate group, GTR-1800-MCAand KWG1-EP-MCAwith methoxy group substituted cinnamate showed similar and higher reaction conversion rates than the former, respectively. These results were explained in terms of segmental mobility for photopolymerization by molecular interactions.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3691-3695
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• 2012

Photocatalytic reduction of hexavalent chromium (Cr(VI)) in ferric-tartrate system under irradiation of visible light was investigated. Effects of light resources, initial pH value and initial concentration of various reactants on Cr(VI) photocatalytic reduction were studied. Photoreaction kinetics was discussed and a possible photochemical pathway was proposed. The results indicate that Fe(III)-tartrate system is able to rapidly and effectively photocatalytically reduce Cr(VI) utilizing visible light. Initial pH variations resulte in the concentration changes of Fe(III)-tartrate complex in this system, and pH at 3.0 is optimal for Cr(VI) photocatalytic reduction. Efficiency of Cr(VI) photocatalytic reduction increases with increasing initial concentrations of Cr(VI), Fe(III) and tartrate. Kinetics analysis indicates that initial Fe(III) concentration affects Cr(VI) photoreduction most significantly.

• Journal of Environmental Science International
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• v.8 no.1
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• pp.125-133
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• 1999

Sorbents of calcined limestone and oyster particles having a diameter of about 0.63mm were exposed to simulated fuel gases containing 5000ppm $H_2S$ for temperatures ranging from 600 to 80$0^{\circ}C$ in a TGA (Thermalgravimetric analyzer). The reaction between CaO and $H_2S$ proceeds via an unreacted shrinking core mechanism. The sulfidation rate is likely to be controlled primarily by countercurrent diffusion through the product layer of calcium sulfide(CaS) formed. The kinetics of the sorption of $H_2S$ by CaO is sensitive to the reaction temperature and particle size, and the reaction rate of oyster was faster than the calcined limestone.

• Journal of Hydrogen and New Energy
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• v.16 no.4
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• pp.324-333
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• 2005

The kinetics of external hydrogen embrittlememt is considered. The equation of the crack growth rate (CGR) is derived from modification of the model developed by Wilkinson and Vitek. After calculation of hydrogen pressure build-up in the void, the effect of the internal hydrogen pressure on the void growth is added. The CGR is expressed by two terms. One is the term dependent on the critical stress, which is exactly same as Wilkinson and Vitek. The other is term dependent on the pressure of the hydrogen in void.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.1
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• pp.99-105
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• 1997

In the paper, aging of insulating oil in pole transformer has been studied by performing accelerated thermal aging test. Dissolved gases were extracted by air bubbling method. Concentration of dissolved gases were modified by extraction ratio of each gases in insulating oil. Aging of insulating materials were proceeded by thermal degradation and oxidation reaction. Both of the reactions followed zeroch order kinetics. Formation rate equations for hydrocarbons, carbon oxides, and hydrogen were derived. It was conformed by gas analysis and UV-Visible spectrophotometric method that iron core and copper coil in pole transformer act as catalyst during the aging process.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.210-215
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• 2013

Kinetics of oxidation of indole by peroxomonosulphate (PMS) in aqueous acetonitrile medium has been investigated. The reaction follows a total second order, first order each with respect to [Indole] and [PMS]. The rate of the reaction was not affected by added [$H^+$]. Variation of ionic strength (${\mu}$) had no influence on the rate. Increase of percentage of acetonitrile decreased the rate. Absen ce of any polymerization indicated a nonradical pathway. Activation and thermodynamic parameters have bee n computed. A suitable kinetic scheme based on these observations is proposed. The reactivity of PMS towards Indole was found to be higher than that with peroxodisulphate.

• Elastomers and Composites
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• v.50 no.4
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• pp.274-278
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• 2015

Nanosized gold particles were synthesized by microwave irradiation in a mixture composed of potassium tetrachloroaurate(III) n-hydrate, sodium citrate dihydrate and Tween 20. The synthesized gold particles were characterized by UV-vis spectrophotometer, scanning electron microscopy, and X-ray diffraction techniques. Using UV-vis spectroscopy, it was confirmed that gold nanoparticles act as a catalyst in the reduction of 4-nitroaniline with sodium borohydride to form 1,4-diaminobenzene. Additionally, we studied the kinetics of this reductive reaction in the presence of these gold nanoparticles under various conditions.