• Journal of the Korean Society of Clothing and Textiles
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• v.22 no.1
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• pp.100-107
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• 1998

Polyester filaments were dyed with disperse dye in dyebath containing water and water miscible organic solvents . acetone, 1,4-dioxane, DMF. In case of Acetone and 1,4-dioxane, the equilibrium dyeuptake was maximun at the volume fraction 0.05. The equilibrium dye uptakes were decreased as volun~e fraction of organic solvents were increased. When the volume fractions of water miscible organic solvents were varied, dye uptake was increased constantly with dyeing time. In dyebath containing water and water miscible organicsolvent, the dyeuptake was increased quickly during initial 40∼ 60 min. and slowly increased there after. The slope of Ct/Coo to t was greater in dyebath containing water and water miscible organic solvents than dyebath containing water. The differences of the slope with volulne fractions of water miscible organic solvent were not shown big.

• Korean Chemical Engineering Research
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• v.44 no.1
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• pp.92-96
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• 2006

Enzymes in organic media afford many advantages such as chiral synthesis and resolution, modification of fats and oils and production of biodegradable polymers. However, the nature of solvents influences the activity and stability of enzymes, and the presence of organic solvents always constitute a risk of enzyme inactivation. Heat-shock protein Hsp90, one of the molecular chaperone, was applied for understanding of enzyme inactivation and for increasing of enzyme stability in water-miscible organic solvent. Hsp90 showed stabilization effect on HRP in the 30％ of DMSO, in the 30％ and 50％ of dioxane. Hsp90 also showed reactivation effect on the inactivated HRP by water-miscible organic solvent such as dioxane and DMSO. In addition, structural analysis using fluorescence spectrophotometry and circular dichroism showed that exposure of HRP in water-miscible organic solvent caused appreciable conformational changes and enzyme inactivation, and the unfolded HRP by water-miscible organic solvent was refolded by Hsp90.

• KSBB Journal
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• v.9 no.3
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• pp.312-318
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• 1994

The esterification of Ac-Tyr-OH was carried out in one-phase system containing ethanol by ${\alpha}$-chymotrypsin. The results of the esterification reaction are as follows. Chitin-${\alpha}$-chymotrypsin complex was found to be an effective catalyst for the esterlfication of Ac-Tyr-OH in ethanol organic solvent. The optimal conditions for the esterification were chitn/${\alpha}$-chymotrypsin ratio, 20(w/w); reaction temp., $35^{\circ}C$; reaction pH, 8.0; reaction time, 24 hrs. Also, addition of chitin in water/water-miscible organic solvent was effective for the stability of the enzyme. The esterification yield, Km and Vmax under optimal conditions were 93%, 3.093mM and 1.088mM/mg/hr, respectively.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.197-200
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• 2009

A simple dye having phenol and indole moieties was synthesized and its chromogenic signaling behaviors for the determination of water content in organic solvents were investigated. The compound revealed a pronounced chromogenic behavior in response to the variation of water content in water miscible aprotic organic solvents of acetone, acetonitrile, THF, and dioxane. Significant red shifts and changes in absorption spectra allowed a ratiometric analysis of the signaling behavior. The chemosensing behaviors were particularly pronounced in water content in less than 10% that is suitable for the application of the compound as a probe for the determination of water content in binary aqueous organic solutions having lower water content.

• Advances in nano research
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• v.13 no.2
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• pp.187-197
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• 2022

The synthesis of organic and hybrid organic-inorganic perovskites directly from solution improves the cost- and energy-efficiency of processing. To date, numerous research efforts have been devoted to investigating the influence of the various solvent parameters for the synthesis of lead halide perovskites, focused on the effects of different single solvents on the efficiency of the resulting perovskites. In this work, we investigated the effect of solvent blends for the first time on the structure and phase of perovskites produced via the Lewis base vapor diffusion method to develop a new synthetic approach for water-stable CsPbBr₃ particles with nanometer-sized dimensions. Solvent blends prepared with DMF and water-miscible solvents with different Gutmann's donor numbers (D_N) affect the Pb ions differently, resulting in a variety of lead bromide species with various colors. The use of a DMF/isopropanol solvent mixture was found to induce the formation of the Ruddlesden-Popper perovskite based on lead bromide. This perovskite undergoes a blue color shift in the solvated state owing to the separation of nanoplatelets. In contrast, the replacement of isopropanol with DMSO, which has a high DN, induces the formation of spherical CsPbBr₃ perovskite nanoparticles that exhibit green emission. Finally, the integration of acetone in the solvent system leads to the formation of lead bromide complexes with a yellow-orange color and the perovskite CsPbBr₃.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.541-545
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• 2000

For the sustained release formulation of recombinant human growth hormone (rhGH), dissociable rhGH aggregates were microencapsulated within poly(D,L-lactic-co-glycolic acid) [PLGA] microparticles. rhGH aggregates with 2 - 3 m Particle diameter were first produced by adding a small volume of aqueous rhGH solution into a partially water miscible organic solvent phase(ethyl acetate) containing PLGA. These rhGH aggregates were then microencapsulated within PLGA polymer phase by extracting ethyl acetate into an aqueous phase pre-saturated with ethyl acetate. The resultant microparticles were 2 - 3 m in diameter similar to the size of rhGH aggregates, suggesting that PLGA polymer was coated around the protein aggregates. Release profiles of rhGH from these microparticles were greatly affected by changing the volume of the incubation medium. The release rhGH species consisted of mostly monomeric form with having a correct conformation. This study reveals that sustained rhGH release could be achieved by microencapsulating reversibly dissociable protein aggregates within biodegradable polymers.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.781-785
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• 2005

A fast and reliable method for the selective separation and preconcentration of $Cu^{2+}$ ions using homogeneous liquid-liquid extraction was developed. A new $\alpha$-dioxime derivative (2H-1,4-benzothioazine-2,3(4H)dionedioxime, Dioxime I) was synthesized and investigated as a suitable selective complexing ligand for $Cu^{2+}$ ions. Zonyl FSA (FSA) was applied as a phase-separator agent under the slightly acidic pH conditions. Under the optimal experimental conditions ([FSA] = 3.2% w/v, [THF] = 19.5% v/v, [Dioxime I] = 1.9 ${\times}\;10^{-3}$ M, and pH = 4.7), 10 ${\mu}g\;of\;Cu^{2+}$ in 5.2 mL aqueous phase could be extracted quantitatively into 80 $\mu$L of the sedimented phase. The maximum concentration factor was 65-fold. The limit of detection of the proposed method was 0.005 ng $mL^{-1}$. The reproducibility of the proposed method, on the 10 replicate measurements, was 1.3%. The influence of the pH, type and volume of the water-miscible organic solvent, concentration of FSA, concentration of the complexing ligand and the effect of different diverse ions on the extraction and determination of $Cu^{2+}$ ions were investigated. The proposed method was applied to the extraction and determination of $Cu^{2+}$ ion in different synthetic and natural water samples.

• Korean Journal of Food Science and Technology
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• v.24 no.5
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• pp.504-510
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• 1992

Several single or mixed water-miscible organic solvent systems were investigated to develop the most effective solvent system for enzymatic synthesis of N-benzoylaspartame(BzAPM). The BzAPM was prepared by immobilized thermolysin with using N-benzoyl-L-aspartic acid(Bz-Asp) and L-phenylalanine methyl ester(PheOMe). The solubilities of BzAPM and L-phenylalanine were highest in 4.5% methanol(1.89 and 1.79%, respectively) among the solvents system investigated while a mixed solvent system of 25% dimethyl sulfoxide(DMSO) and 20% polyethylene glycol(PEG) 200 showed relatively high values. The synthetic activity of BzAPM as well as initial reaction rate were found to be high in 45% methanol, 45% DMSO and a mixed solvent of 25% DMSO and 20% PEM 200. The imobilized thermolysin was most stable in 25% DMSO and 20% PEG 200 during storage at $40^{\circ}C$ for 42 days. PheOMe in the same solvent system was also found fairly stable against non-enzymatic decomposition at $40^{\circ}C$. Based on the synthetic efficiency and stability, the solvent system containing 25% DMSO and 20% PEG 200 was selected to be appropriate for the enzymatic synthesis of BzAPM.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.479-486
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• 2003

In this study, poly(DL-lactide-co-glycolide) nanoparticles loaded with water-insoluble vitamins such as vitamin A (Retinol) and vitamin E acetate were prepared by the emulsification diffusion method. Polymer solution was prepared by the two water-miscible organic solvent, such as ethanol and acetone. Because of its biocompatible property, polyethyleneglycol-polypropyleneglycol diblock copolymer was used as surfactant and stabilizer. The influence of some preparative variables on the nanoparticle formation and on the loading efficiency of active agents, such as the type and concentration of stabilizing agent, the stirring methods, the water/oil phase ratio and the polymer concentration were investigated in order to control and optimize the process. After preparation of nanoparticles loaded with active agent, particle size and distribution were evaluated by the light scattering particle analyzer. The loading efficiency of active agents was evaluated by the UV-visible spectroscopy. As the results, particle size were 50-200 nm and dispersibility was monodisperse. The optimum loading efficiency of active agents was observed 50-60%. It was found that the appropriate of selections of binary solvent mixtures and polymeric concentrations in both organic and aqueous phases could provide good yield and favorable physical properties of PLGA nanoparticles.

• Clean Technology
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• v.22 no.3
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• pp.175-180
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• 2016

Tyrosinases catalyze the hydroxylation of a monophenol (monophenolase activity) and the conversion of an o-diphenol to o-quinone (diphenolase activity), which are mainly involved in the modification of tyrosine residues into 3,4-dihydroxyphenyl-alanine (DOPA) and DOPA/DOPAquinone-derived intermolecular cross-linking. Previously, we obtained a slightly acidic and cold-active tyrosinase, tyrosinase-CNK, by our recombinant protein approach. The enzyme showed optimal activity at pH 6.0 and 20 ℃ with an abnormally high monophenolase/diphenolase activity ratio and still had approximately 50% activity compared with the highest activity even in ice water. Here, we investigated reaction stability of the recombinant tyrosinase-CNK as a psychrophilic enzyme. The enzyme showed remarkable thermal stability at 0 ℃ and the activity was well conserved in repeated freeze-thaw cycles. Although water-miscible organic solvent as reaction media caused the activity decrease of tyrosinase-CNK as expected, the enzyme activity was not additionally decreased with increased concentration in organic solvents such as ethanol and acetonitrile. Also, the enzyme showed high salt tolerance in chaotropic salts. It was remarkably considered that 2⁺ metal ions might inhibit the incorporation of Cu²⁺ into the active site. We expect that these results could be used to design tyrosinase-mediated enzymatic reaction at low temperature for the production of catechols through minimizing unwanted self-oxidation and enzyme inactivation.