• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.582-592
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• 1990

Retention behavior of lanthanide-$\alpha$HiBA complexes was studied on the cation exchanger (LC-18 coated with $C_{20}H_{41}SO_4^-$). An equation predicting retention of lanthanides in isocratic or gradient elution with sodium ion and $\alpha$-HiBA concentration was derived from ion exchange equilibria of metal-ligand complex system, respectively. The relations between log k' and log [Na$^+$] /log [$\alpha$-HiBA) showed non-linearity in isocratic elution. In gradient elution a good linearity between log k' vs log R was obtained. The values of slopes (log k / log R) gave good agreements between calculation and experiment. Individual capacity factors ($k'_{Ln}^{3+}, k'_{LnL}^{2+}, k'{LnL2+}) and stability constant (${\beta}_1$, ${\beta}_2$, ${\beta}_3$) of lanthanide-$\alpha$HiBA complexes were calculated by the non-linear least square fittings using the retention equation. The correlation coefficients of lanthanides were shown better than 0.9996 between experiment and calculation.

• The Korean Journal of Ecology
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• v.22 no.1
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• pp.13-19
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• 1999

To investigate and compare the effects of air pollution near Seoul on soil ion, plant nutrient contents and plant growth, 14 Quercus mongolica forests were studied from Mt. Namsan in Seoul to Mt. Maebongsan in Kangwon-Do along the line transect. Soil pH values decreased as approached to Seoul. Concentrations of basic cations such as exchangeable Ca/sup 2+/, Mg/sup 2+/ and Na/sup +/ and effective cation exchange capacity(ECEC) in forest soil decreased as approached to Seoul. Ca/sup 2+/ and Mg/sup 2+/ contents in l-year-old Q. mongolica twigs decreased, but their K/sup +/ and Na/sup +/ contents increased as approached to Seoul. Ca/sup 2+/ contents in l-year-old Q. mongolica leaves decreased, but their K/sup +/ and Mg/sup 2+/ contents increased as approached to Seoul. Length of l-year-old twigs generally decreased near Seoul. Tree-ring analyses of Q. mongolica trees in Mt. Namsan and Mt. Yebongsan showed that mean tree-ring width in Mt. Namsan was narrower than that of Mt. Yebongsan from early 1970's to late 1980's.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.338-338
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• 2011

The behavior of hydroxide ions on water-ice films was studied by using $Cs^+$ reactive ion scattering (RIS), low energy sputtering (LES) and temperature-programmed desorption (TPD). A $Cs^+$ beam of a low kinetic energy (<100 eV) from $Cs^+$ ion gun was scattered at the film surface, and then $Cs^+$ projectiles pick up the neutral molecules on the surface as $Cs^+$-molecule clusters form (RIS process). In LES process, the preexisting ions on the surface are desorbed by the $Cs^+$ beam impact. The water-ice films made of a thick (>50 BL) $H_2$O layer and a thin $D_2O$ overlayer were controlled in temperatures 90~140K. We prepared hydroxide ions by using Na atoms which proceeded hydrolysis reaction either on the ice film surface or at the interface of the $H_2O$ and $D_2O$ layers.[1] The migration of hydroxide ions from the $H_2O/D_2O$ interface to the top of the film was examined as afunction of time. From this experiment, we show that hydroxide ions tend to reside at the water-ice surface. We also investigated the H/D exchange reactions of $H_2O$ and $D_2O$ molecules mediated by hydroxide ions to reveal the mechanism of migration of hydroxide to the ice surface.

• Journal of the Mineralogical Society of Korea
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• v.15 no.4
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• pp.259-272
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• 2002

This study was tried to interpret the important major factors controlling some physicochemical properties by comparing mineralogical and physicochemical characteristics such as pH, cation exchange capacity, Methylene Blue adsorption amount, swelling, viscosity, strength (compressional and tensile), and surface area etc. Investigated bentonite samples are five Korean samples from Dusan, Naa, Oksan, Dongyang, and Yeonil deposits and two Japanese bentonites from Tsukinuno and Tomioka deposits which were formed under a similar geological environment of the Tertiary basin. Tsukinuno bentonite is only natural Na-type bentonite and the others are all Ca-type bentonites. Most of the properties are not explained by the montmorillonite content only though the most important factor controlling the physicochemical properties is the montmorillonite content. The layer charge of montmorillonite will strongly control cation exchange capacity and Methylene Blue adsorption. Zeolite bearing bentonites show the strong alkaline character and causes the increase of cation exchange capacity, however decrease swelling, viscosity and strengths. Pyrite bearing bentonites decrease green compressional strength and wet tensile strength. The exchangeable interlayer cations control some physicochemical properties. Na-type bentonite than Ca-type shows more strong alkaline character and much more advanced swelling and viscosity. Also the size and thickness of montmorillonite flakes seem to control some physicochemical properties. Bentonite mainly composed of montmorillonite of very thin and large flakes is characterized by the very high surface area, cation exchange capacity, viscosity, swelling, Methylene Blue adsorption, green compressional strength and wet tensile strength. Domestic Dusan bentonite shows the most excellent physicochemical properties, which is due to the high content(84%) and very well crystallinity of montmorillonite.

• Korean Journal of Veterinary Research
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• v.40 no.3
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• pp.479-487
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• 2000

Several recent studies demonstrate that receptor-mediated cAMP (adenosine 3',5'-monophosphate) production evokes marked change in magnesium ($Mg^{2+}$) homeostasis. The effects of dimaprit or/and phosphodiesterase (PDE) inhibitors on the $Mg^{2+}$ release from perfused guinea pig heart and collagenase-dispersed myocytes was studied to clarify an association of $H_2-histaminergic$ receptor-mediated $Mg^{2+}$ regulation with intracellular cAMP-degradation system. $Mg^{2+}$ efflux was stimulated in perfused hearts and myocytes by IBMX (3-isobutyl-1-methylxanthine), a calmodulin-sensitive PDE inhibitor, but not by RO 20-1724(4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone) or papaverine, cAMP-specific PDE inhibitors. $Mg^{2+}$ efflux was also be induced by dimaprit, a H-2-agonist. $Mg^{2+}$ effluxes induced by dimaprit were augmented by the presence of the PDE inhibitors. The augmentation of dimaprit-induced $Mg^{2+}$ effluxes by the PDE inhibitors were inhibited by ranitidine, a $H_2-antagonist$, and imipramine, a $Na^{+}-Mg^{2+}$ exchange inhibitor, in perfused hearts and myocytes and were also inhibited by amiloride in perfused hearts. These results suggest that the $H_2$-stimulated $Mg^{2+}$ effluxes from guinea pig heart can be regulated by the cytosolic nonspecific-dependent PDE systems and that it is induced by the $Na^{+}-Mg^{2+}$ exchanger stimulation.

• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.141-145
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• 2001

The Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ exchange bias layers (EBLs), which have a small amounts of Pt, exhibit a high value of H$\_$ex/. The Si/Ni-Fe/Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ EBL shows the largest H$\_$ex/ of 187 Oe, which is equivalent to a exchange energy (J$\_$ex/) of 0.146 erg/cm$^2$. Mn$\_$80/Ir$\_$18.1/Pt$\_$1.9/ EBLS are estimated to have blocking temperature of about 250 $\^{C}$, which is higher than those of Mn-Ir EBLs and Mn-Ir-Pt EBLs with higher Pt contents. This result implies that a little addition of Pt element promotes thermal stability in the Mn-Ir-Pt EBLs. The chemical stability of Mn-Ir-Pt EBLs was characterized by potentiodynamic test, which was performed in 0.001 M NaCl solution. The current density of Mn-Ir-Pt films was gradually reduced with increasing Pt content. The present results indicate that the Mn-Ir-Pt with a small amount of Pt is suitable for an antiferromagnetic material for a reliable spin valve giant magnetoresistance device.

• Fisheries and Aquatic Sciences
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• v.6 no.1
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• pp.7-12
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• 2003

Chitinase and chitobiase produced by Aeromonas sp. J-5003 were purified and characterized. The chitinase was purified to 19.4 folds by gel chromatography and ion-exchange chromatography with the overall yield of $2.2\%$ and the specific activity of 93.1 unit/mg. The purified enzyme showed a single band on SDS-PAGE with MW 54kDa. The optimum pH and temperature of the purified chitinase were 7.0 and $37^{\circ}C$, respectively, and this enzyme stable in the range of pH 6.0 to 10.0 below $37^{\circ}C$. $Mg^{2+},\;Ca^{2+}\;and\;Na^+$ slightly stimulated the chitinase activity. However, $Hg^{2+}\;and\;Fe^{3+}$ inhibited chitinase activity. The chitobiase was purified by Sephacryl HR-l00 gel chromatography and DEAE-Sephadex A-50 ion-exchange chromatography with 33.5 purification folds and $4.3\%$ yield. The purified enzyme showed a single band with MW 63 kDa. The optimum pH and temperature of the purified chitobiase were 7.0 and $37^{\circ}C$, respectively. And this enzyme was stable in the range of pH 6.0 to 9.0 and at the temperature below $37^{\circ}C$. The enzyme activity was increased by $Mn^{2+}$, but it was inhibited by $Ag^+$.

• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.312-317
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• 1995

The polygalacturonase (PG) production in rotten apples by Botryosphaeria dothidea was purified by using gel filtration and ion exchange column chromatography, and the biochemical characters of PG were investigated. The purified PG appeared as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) with approximate molecular weight of 49 kilodalton (kDa). The molecular weight was equal to the native molecular weight estimated by gel filtration. The Km and Vmax values of PG were 0.51 mg/ml and 90.9 $\mu$M/min/ml, respectively. Optimum pH was 4.0~5.0, and the PG activity was stable from pH 5.0~10.0. Optimum temperature of the enzyme activity was 4$0^{\circ}C$. The PG activity was relatively stable at 2$0^{\circ}C$, but it was reduced 45% at 4$0^{\circ}C$ and completely inactivated at 8$0^{\circ}C$. The PG activity was considerably inhibited by Cu2+, Zn2+, SDS and EDTA, whereas it was not effected by Ca2+, K+, Mg2+ or Na+ ions.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.500-504
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• 2005

Fusion ferritin (heavy chain ferritin, $F_H+$ light chain ferritin, $F_L$), an iron-binding protein, was primarily purified from recombinant Escherichia coli by two-step sonications with urea [1]. Unfolded ferritin was refolded by gel filtration chromatography (GFC) with refolding enhancer, where 50 mM Na-phosphate (pH 7.4) buffer containing additives such as Tween 20, PEG, and L-arginine was used. Ferritin is a multimeric protein that contains approximately 20 monomeric units for full activity. Fusion ferritin was expressed in the form of inclusion bodies (IBs). The IBs were initially solubilized in 4 M urea denaturant. The refolding process was then performed by decreasing the urea concentration on the GFC column to form protein multimers. The combination of the buffer-exchange effect of GFC and the refolding enhancers in refolding buffer resulted in an efficient route for producing properly folded fusion ferritin.

• Journal of Korea Soil Environment Society
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• v.2 no.1
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• pp.35-44
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• 1997

A column study using artificial acid rain was conducted to evaluate the buffering capacities in soil layer and host rock. In an effort to compare the effect of composition of host root two valleys of which compositions of host rock are different were chosen within the study area and the pHs of the water flowing in the valleys were measured from May, 1996 to October, 1996. The pHs of the artificial acid rain prepared by adding appropriate amounts of both sulfuric and nitric acids to distilled water were 3, 4, and 5, and the column effluents were analyzed for major cations and anions. The cation exchange capacities(CECs) of A Horizon and the B Horizon were 9.68 and 6.16 meq/100g, respectively, Compared to the B Horizon, the pH in the column effluent of A Horizon with larger CEC was higher. The sums of $Ca^{2+}$, $Mg^{2+}$, $Na^{+}$in the column effluents gradually decreased, indicating the loss of CEC by acid rain. The field study showed that pHs of the surface water in the valleys increased as the water flows downwards. The magnitude of this buffering capacity was greater for the valley in which smectite in addition to kaolinite and illite was a weathered product of host rocks. This also indicates that host rock as well as soil layer retains the buffering capacity.