• Food Science and Biotechnology
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• v.17 no.1
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• pp.8-14
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• 2008

The influence of salt concentration on the stability of sodium caseinate (CAS)-stabilized emulsions (20 wt% corn oil, 3.2 wt% CAS, 5 mM imidazole/acetate buffer, pH 7) was examined. In the absence of salt, laser diffraction measurements and optical microscopy measurements indicated there were some large oil droplets ($d>10\;{\mu}m$) in the emulsions stabilized by 0.8 to 3.2 wt% of CAS. The droplet aggregation (mostly droplet coalescence) observed in the emulsions containing ${\leq}2.8\;wt%$ CAS tended to decrease as the CAS concentration increased, however, after which concentration (at 3.2 wt% CAS) depletion flocculation occurred. The addition of $CaCl_2$ (5-20 mM) into the emulsions stabilized by 3.2 wt% CAS prevented the depletion flocculation although there was a small fraction of relatively large individual droplets in the emulsions, which was attributed to electrostatic screening effect and bridging effect of calcium ion. This study has shown that calcium ion that has been reputed to promote droplet aggregation could improve emulsion stability against droplet aggregation in CAS-stabilized emulsions.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.587-587
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• 2012

Supercapacitors, which can deliver significant energy with high power density, have attracted a lot of attention due to their potential application in energy storage. Among various oxide materials, sodium vanadate has been recognized as one of the most promising electrode materials because of high electrical conductivity. In addition, larger layer spacing of ${\beta}$-Na0.33V2O5 compared to V2O5 makes easier Li+ insertion. Moreover, ${\beta}$-Na0.33V2O5 has a tunnel like structure along b axis with 3 kinds of V site allowing it to enhance the ion intercalation by introducing three different intercalation sites along the tunnel. The tunnel can act as a fast diffusion path for ion diffusion, which can improve the overall charge storage kinetics. In this study, high quality single crystalline sodium vanadate (${\beta}$-Na0.33V2O5) nanowires were grown directly on Pt coated $SiO_2$ substrate by a facile chemical solution deposition method without employing catalyst, surfactant or carrier gas. The results show that great enhancement in capacitance was observed compared with previous reports.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.632-637
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• 1992

Standard transfer free energies of sodium and cupric perchlorates in water-acetylacetone solvent system have been determined by electromotive force measurements of galvanic cell and these energies of sodium and cupric ions in this solvent system have been evaluated by the tetrabutylammonium tetraphenylborate assumption as the extrathermodynamic procedure. Standard transfer free energy values of sodium and cupric ions from water to acetylacetone solvent were 5.09 and 4.16 kcal/mol at 25${\circ}C$, respectively. These values mean that acetylacetone is much weaker donor solvent to sodium and cupric ions than water. The standard transfer free energy value of cupric ion from water to mixture solvents which contain small amount of acetylacetone is changed by an unusual form. This is because of the chelate formation effect of acetylacetone to cupric ion.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1936-1938
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• 2011

Phosphonium montmorillonites (P-MMTs) were prepared by intercalating dodecyl tributyl phosphonium salt into sodium montmorillonite (Na-MMT) through an ion-exchange method. Microstructure and antibacterial activity of phosphonium montmorillonites were studied by FT-IR, TGA, XRD and Minimum Inhibitory Concentration (MIC), respectively. The results show that phosphonium montmorillonites exhibit higher thermal stability than conventional ammonium montmorillonites, the onset temperature of decomposition is higher than 300 $^{\circ}C$, and the basal spacing of phosphonium montmorillonites is enlarged compared to that of sodium montmorillonite. Phosphonium montmorillonites also show good antibacterial activity with the MIC against E. coli and S. aureus of 150 and 50 $mg{\cdot}L^{-1}$, respectively.

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.243-244
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• 2008

The Velocity Autocorrelation Function (VAF) of the sodium ions is calculated for a range of temperature from 250K to 1000K and converted into the linear ac-conductivity and ac-susceptibility response via Fourier transformation. A peak is found in the conductivity around $6{\times}10^{12}Hz$ that has some of the character of a Poley absorption. Here it is shown to be due to an harmonically coupled site vibrations of the sodium atoms, which extend only over a limited range. At frequencies below the peak the conductivity tends towards a constant i.e. dc value corresponding to a constant flow of ions through the simulation cell. At high temperatures the conductivity due to this ion transport process behaves like a metal with an insulator to metal transition occurring around a specific temperature.

• Korean Journal of Materials Research
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• v.11 no.12
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• pp.1047-1051
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• 2001

Purity tantalum powder has been produced by sodium reduction of potassium tantalum fluoride($K_2TaF_7$)in a stainless steel bomb. The influence of experimental variable, such as excess of reductant and temperature of reduction on the yield and quality of the Ta powder has been studied. The excesses of reductant were varied from -20%, -10%, 0%, 5%, 10%, 20%. When -20% excess of sodium was used, the un-reacted sodium remained in the reacted product. The yield of 81% of Ta powder has been achieved by reducing 50g of$K_TaF_7$with 5% sodium in excess of stoichiometric amount in presence of 16.8g of sodium chloride in the charge at a reduction temperature of$905{\circ}C$. The proportion of fine fraction(~325mesh) decreased appreciably with the increase of sodium excess, and the yield of tantalum powder improved from 65% to 94%. The average particle size of Ta Powder is improved from 3 microns to 4 microns in the 5% excess sodium.

• Analytical Science and Technology
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• v.14 no.4
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• pp.306-310
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• 2001

Ion chromatography was applied to determine iodide remained in sulfuric acid aqueous solution after adsorption procedure. Iodide was determined in 0.25 M, 0.5 M and 1 M sulfuric acid solution on time variation. Because sulfuric acid in solution plays as an oxidizer, the concentration of iodide decreased with increasing concentration or sulfuric acid. Thereafter, sulfuric acid was neutralized with sodium hydroxide. Good linearity(r=0.99999) was obtained at the range of 0-20 mg/L 1 in 0.5 M sodium sulfate matrix.

• Journal of Environmental Science International
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• v.13 no.1
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• pp.89-97
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• 2004

An author has been known that A-type zeolite supported with silver ions has excellent antibacterial activity. However, it is no research of concern in the antibacterial activity of eluted silver ions. This study tested the elution of silver ions from A-type zeolite silver ions in deionized distilled water and NaNO$_3$ aqueous solution. In NaNO$_3$ aqueous solution of 74mM to 588mM, it was found that the concentration of silver ions and electric conductivity increased with the increasing concentration of sodium ions, and equilibrated at 15 min, and the ion exchange equilibrium coefficient, k, is 1.3${\times}$10$\^$-3/. However, deionized distilled water is not equilibrated to pass 6 months. A-type zeolite sodium ions showed no antibacterial activity. It was found that antibacterial activity was exhibited even at the concentration of 10 nM of eluted silver ions, and E-coli died with the incorporation of 2.43${\times}$10$\^$8/ Ag ion/cell. antibacterial activity of A-type zeolite silver ions were mainly attributed to hydroxyl radical.

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.75-80
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• 2006

We studied feasibility of three-dimensional optical memory by utilizing femtosecond laser-induced changes of transmission in photopolymers and photoluminescence in Eu and Sm ion doped sodium borate glasses. We produced transmission change by two photon absorption and obtained sub-Um size spots in photopolymers using 780 nm modelocked Ti-sapphire laser pulses. We also changed valence state of Eu and Sm ions by multi-photon absorption and achieved $\~{\mu}m$ sized spot formation in Sm-doped glasses.

• Journal of Environmental Science International
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• v.9 no.1
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• pp.43-47
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• 2000

A study on the remediation of heavily for ion contaminated soils from abandoned iron mine was carried out, using ex-situ extraction process. Also, oxalic acid as a complex agent was evaluated as a function of concentration, reaction time and mixing ratio of washing agent in order to evaluate Fe removability of the soil contaminated from the abandoned iron mine. Oxalic acid showed a better extraction performance than 0.1N-HCl, i.e., the concentrations of Fe ion extracted from the abandoned mine for the former at uncontrolled pH and the latter were 1,750 ppm and 1,079 ppm, respectively. The optimum washing condition of oxalic acid was in the ratio of 1:5 and 1:10 between soil and acid solution during l hr reaction. The total concentrations of Fe ion by oxalic acid and EDTA at three repeated extraction, were 4,554 ppm and 864 ppm, respectively. The recovery of Fe ions from washing solution was achieved, forming hydroxide precipitation and metal sulfide under excess of calcium hydroxide and sodium sulfide. In addition, the amounted of sodium sulfide and calcium hydroxide for the optimal revovery of Fe were 15g/$\ell$ and 5g/$\ell$ from the oxalic acid complexes, respectively.