• Journal of Adhesion and Interface
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• v.25 no.1
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• pp.157-161
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• 2024

Amphiphilic gold nanoparticles, synthesized by the simultaneous binding of hydrophilic and hydrophobic ligands on their surfaces, find diverse applications in energy, bio, optical, electronic technologies, and various other fields. Particularly, these amphiphilic gold nanoparticles possess both hydrophilic and hydrophobic characteristics, enabling them to activate interface at the interface of immiscible fluids and form organized structures. The surface properties of gold nanoparticles play a crucial role in influencing the behaviors of amphiphilic gold nanoparticles at the interface of two fluids. Therefore, this study investigated the adsorption behaviors of gold nanoparticles at the organic solvent-water interface based on the surface characteristics of amphiphilic gold nanoparticles and the type of organic solvents. It was observed that the amount of adsorbed gold nanoparticles at the interface increased with the length of hydrocarbon chains in hydrophobic ligands and increased with shorter hydrocarbon chains in the organic solvent. Furthermore, using the Langmuir isotherm model, the study confirmed the formation of a monolayer by amphiphilic gold nanoparticles and obtained significant thermodynamic parameters simultaneously.

• Journal of the Korean Applied Science and Technology
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• v.33 no.3
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• pp.498-506
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• 2016

1, 2-Hexanediol galactoside (HD-gal) has been previously synthesized from 1, 2-hexanediol (HD), in which recombinant ${\beta}$-galactosidase (${\beta}$-gal) of Escherichia coli (E. coli) was used for transgalactosylation reaction. In this study, a method for HD-gal purification from the reaction mixture was particularly investigated. Using ${\beta}$-gal-containing E. coli, HD-gal was synthesized from 75 mM HD for 48 hr under 300 g/l lactose concentration. Then, HD-gal synthesis from HD was confirmed by TLC analysis, and the existence of E. coli ${\beta}$-gal during 48 hr-reaction was also confirmed by Western blotting, in which the conversion yield of HD to HD-gal reached about 94% during 48 hr. To establish an efficient method for HD-gal purification, we carried out the solvent extraction of the reaction mixture, followed by silica gel chromatography, particularly in order to remove the residual HD. Two water-immiscible solvents, such as methylene chloride and ethyl acetate, were investigated comparatively to find out appropriate solvent. Then, it was found that residual HD was almost removed when ethyl acetate extraction of water phase of reaction mixture was carried out four times. Subsequently, silica gel chromatography was carried out, and purified HD-gal could be finally obtained. The production yield for HD-gal from 75 mM HD was $8.9{\pm}0.6%$ (n=3) (mole basis) or $21.1{\pm}1.4%$ (n=3) (weight basis). For further study, using purified HD-gal, we will investigate the minimum inhibitory concentrations (MICs) of HD-gal against bacteria. In addition, cytotoxicity to human skin cells of HD-gal will be examined.

• Journal of the Korean earth science society
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• v.22 no.4
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• pp.278-291
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• 2001

Mesothermal gold vein minerals of the Seolhwa mine were deposited in a single stage of massive quartz veins which filled the mainly NE-trending fault shear zones exclusively in the granitoid of the Gyeonggi Massif. The Seolhwa mesothermal gold mineralization is spatially associated with the Jurassic granitoid of 161 Ma. The vein quartz contains three main types of fluid inclusions at 25$^{\circ}$C: 1) low-salinity (< 5 wt.% NaCl), liquid CO$_{2}$-bearing, type IV inclusion; 2) gas-rich (> 70 vol.%), aqueous type II inclusions; 3) aqueous type I inclusions (0${\sim}$15 wt.% NaCl) containing small amounts of CO$_{2}$. The H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl inclusions represent immiscible fluids trapped earlier along the solvurs curve at temperatures from 430$^{\circ}$ to 250$^{\circ}$C and pressures of 1 kbars. Detailed fluid inclusion chronologies may suggest a progressive decrease in pressure during the auriferous mineralization. The aqueous inclusion fluids represent either later fluids evelved through extensive fluid unmixing (CO$_{2}-CH$_{4}$ effervescence) from a homogeneous H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl fluid due to decreases in temperature and pressure, or the influence of deep circulated meteoric waters possibly related to uplift and unloading of the mineralizing suites. The initial fluids were homogeneous containing H$_{2}$O-CO$_{2}-CH$_{4}$-N$_{2}$-NaCl components and the following properties: the initital temperature of >250$^{\circ}$ to 430$^{\circ}$C, X$_{CO}\;_{2}$ of 0.16 to 0.62, 5 to 14 mole% CH$_{4}$, 0.06 to 0.3 mole% N$_{2}$ and salinities of 0.4 to 4.9 wt.% NaCl. The T-X data for the Seolhwa gold mine may suggest that the Seolhwa auriferous hydrothermal system has been probably originated from adjacent granitic melt which facilitated the CH$_{4}$ formation and resulted in a reduced fluid state evidenced by the predominance of pyrrhotite. The dominance of negative ${\delta}\;^{34}$S values of sulfides (-0.6 to 1.4$%_o$o) are consistent with their deep igneous source.