• Journal of the Korean Chemical Society
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• v.29 no.2
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• pp.129-136
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• 1985

In the atomic absorption spectrometry using an air-acetylene flame, the interferences of Zr, Sn, Al, Sb, $SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$, on the calcium absorption and the repression of this interference by the addition of cerium have been studied. The interference by Zr, Sn, Al, Sb, $SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$ existed as the same concentration as calciurn ($3.0 {\times} 10^{-4}$M) in the sample solution are completely released by the addition of cerium twice as much as interfering cation. The interferences by the mixed interfering cations (Zr, Sn, Al and Sb) and by the mixed interfering anions ($SO_4^{2-},\;VO_3^-,\;and\;SiO_3^{2-}$) are larger than by each interfering cation and anion, and the releasing effect by cerium ($1.5 {\times} 10^{-2}$M) is effective up to some degree of the concentration of mixed interfering cations and of mixed interfering anions. The releasing effect by cerium to the mixed solution of interfering cations and anions is applicable to quite wide range of concentration.

• Progress in Medical Physics
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• v.17 no.2
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• pp.96-104
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• 2006

Experiments from several groups Including ours have demonstrated that $Ca^{2+}$ can enhance the inactivation of N-type calcium channels. However, it is not clear if this effect can be ascribed to a 'classic' $Ca^{2+}$-dependent inactivation (CDI) mechanism. One method that has been used to demonstrate CDI of L-type calcium channels is to alter the intracellular and extracellular concentration of $Ca^{2+}$. In this paper we replaced the external divalent cation to monovalent ion ($MA^+$) to test CDI. In the previous paper, we could separate fast (${\tau}{\sim}150ms$) and slow (${\tau}{\sim}2,500ms$) components of inactivation in both $Ba^{2+}$ and $Ca^{2+}$ using 5-sec voltage step. Lowering the external divalent cation concentration to zero abolished fast inactivation with relatively little effect on slow inactivation. Slow inactivation ${\tau}$ correspond very well with provided the $MA^+$ data is shifted 10 mV hyperpolarized and slow inactivation ${\tau}$ decreases with depolarization voltage in both $MA^+\;and\;Ba^{2+}$, which consistent with a classical voltage dependent inactivation (VDI) mechanism. These results combined with those of our previous paper lead us to hypothesize that external divalent cations are required to produce fast N-channel inactivation and this divalent cation-dependent inactivation is a different mechanism from classic CDI or VDI.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.531-535
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• 1997

An efficient process for recovery of calcium from the eggshell was developed and some organic acids were used in an attempt to enhance the degree of calcium ionization. Eggshell membrane was readily separated from crushed eggshell based on the differences in specific gravities. The conditions which allowed most efficient membrane removal were found to be 30 rpm of speed, 30 min of residence time and 0.08 of volume fraction. It took 3 hours for the eggshell powder prepared at $1000^{\circ}C$ to reach L value of 90 with the Hausner ratio being 1.43. The calcium ion concentrations were 990, 3500, 3900 and 4200 ppm in pure water, acetic acid, citric acid and lactic acid$(0.05{\sim}3%)$ aqueous solution, respectively. The degrees of ionization of calcium-citrate-malate complex(CCM), calcium-citric acid complex(CC) and calcium malic acid complex(CM) increased by 4 to 5 times compared to eggshell calcium powder.

• Journal of Veterinary Clinics
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• v.27 no.3
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• pp.216-219
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• 2010

The purpose of this study is to establish experimental canine skin barrier disruption model, the study was designed to observe calcium ion in skin frozen tissue of canine skin and also the modulation of calcium ion distribution of normal skin with disrupted skin such as clipping, acetone, tape stripping damages according to time. To compare the changes of calcium ion gradient after damages, the distribution of calcium ion in the canine epidermis was visualized by blotting to gel containing chemical indicator (Calcium Green-1) with fluorescent microscope and the effects of skin barrier damages were examined according to time. Three mins and 1hr after acetone damage, the gradations of epidermis and hair follicle showed more radiant and disappeared after 48 hrs. On the contrary, 3mins and 1hr after tape stripping damage, the gradations showed more radiant than those of acetone damage, and these gradations were stabilized after 48 hrs. The method we presented here could show the visual image of the calcium ions in frozen tissue without further preparation, and it might be useful to investigate the role of calcium ion in the canine epidermal barrier recovery, however, it might be need further methodological improvement to get accurate quantitative information.

• Korean Journal of Plant Tissue Culture
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• v.22 no.5
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• pp.277-281
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• 1995

The present study was performed to investigate the effect of calcium ion on the mesophyll protoplast culture of Arabidopsis thaliana. The mesophyll protoplase were isolated and cultured on an IMH medium supplemented with CaCl$_2$of various concentrations. When the protoplasts were cultured on the medium containing 0 to 12.5 mM CaCl$_2$, extreme vacuolization occurred without cell division. When the protoplasts were cultured with higher levels of CaCl$_2$ up to 50 mM, vacuolization decreased dose-dependent): and the number of plasma-rich cells increased. Cell division was induced when the protoplast were cultured on the medium with CaCl$_2$ higher than 25 mM. The highest plating efficiency (5-6%) was obtained with 50 mM CaCl$_2$. However the plating efficiency was markedly inhibited by 100mM CaCl$_2$ or above. These resole suggest that the relatively high concentration (50 mM) of calcium ion may be required for the culture of protoplasts.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.206-213
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• 2024

The present study concerns the inhibition of Calcium Nitrite Inhibitor(Ca(NO₂)₂) in mortar contaminated by chloride ions. Thus, the corrosion resistance and chloride transport were measured for the mortar containing calcium nitrite inhibitor. As a result, an increase in the dosage of calcium nitrite inhibitor resulted in an increase in the chloride threshold concentration for reinforcement corrosion, while the rate of chloride transport was accelerated. However, the calcium nitrite inhibitor could not guarantee the time to corrosion, due to the increased mobility of chlorides. To ensure the passivity of steel, the dosage of calcium nitrite inhibitor must exceed a certain dosage, ranging from 2.0~3.0 % by cement weight.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 1998.07a
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• pp.48-49
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• 1998

생쥐 수정난 및 초기 2세포배를 체외배양시 0.428mM 이상의 칼슘 농도를 필요로 하는 것을 알았다. 칼슘 chelator인 EDTA를 저농도로 배양액에 처리 할 경우 2-cell block이 유의하게 극복되었으며, 저농도의 칼슘이 존재하는 배양액에서 보인 2-cell block은 니켈 50 $\mu$ M을 처리함으로서 극복 효과를 보였다. EDTA와 니켈에 의한 2-cell block 극복 현상이 어떠한 기작에 의해 이루어지는가에 대한 자세한 연구가 필요하다고 생각된다.

• Applied Chemistry for Engineering
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• v.5 no.3
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• pp.406-412
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• 1994

The ion-exchange properties of $Ca^{2+}$ and $Mg^{2+}$ ions have been studied in ${\delta}-Na_2Si_2O_5$ synthesized from water glass. Results show that optimum temperature for synthesis of ${\delta}-Na_2Si_2O_5$ was $725^{\circ}C$. Ion-exchange isotherms for $Ca^{2+}$ and $Mg^{2+}$ exchange for $Na^+$ in the synthetic ${\delta}-Na_2Si_2O_5$ show that the ion-exchange capacity of magnesium is better than that of calcium, and the ion-exchange of magnesium is less sensitive for temperature than that of calcium. When initial pH of solution is increased between 2 and 6, the ion-exchange capacities of magnesium and calcium decrease a little. However, they are almost constant above pH 6 because of alkali buffer effect of ${\delta}-Na_2Si_2O_5$. In the thermodynamic studies, it was found that Gibbs free energies of reaction of calcium ion-exchange are larger than those of magnesium ion-exchange with inverse order of selectivity. The standard enthalpy and entropy of reaction of calcium ion-exchange are larger than those of magnesium ion-exchange.

• Journal of the Korean Geotechnical Society
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• v.37 no.4
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• pp.39-47
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• 2021

Recently, the enzyme-induced carbonate precipitation (EICP) technique has been considered as one of the alternatives to the cement-based soil reinforcing method. However, the problem with the emission of ammonium ion has not been solved. In this study, an experimental study on the EICP without releasing an environmental contaminant (Ze-EICP) is performed using calcium-exchanged zeolite. The results show that the Ze-EICP using calcium-exchanged zeolite reduced the amount of ammonium ions by 96.96% and precipitated almost the same amount of calcium carbonate, compared to the EICP using calcium chloride. In addition, the Ze-EICP shows higher strength improvement rate than the EICP due to densification of zeolite and cementation of calcium carbonate.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.111-120
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• 2023

The nucleation mechanism was studied using a calcium ion selective electrode (Ca ISE) to observe the formation of CaCO₃, a representative mineral in the CO2 cycle, and to analyze the effect of the Mg/Ca-ratio and temperature on the formation of pre-nucleation cluster (PNC) and CaCO₃. As a result of the experiment, a small amount of crystal was formed. Energy dispersive X-ray spectroscopy (EDS) was used for surface element analysis, and a field emission scanning-electron microscope (FE-SEM) was used for the morphology analysis of synthesized carbonates. These results showed that various shapes of crystalline CaCO₃ (calcite, aragonite, etc.) were observed for each Mg/Ca ratio and temperature. In addition, the calibration plot obtained from Ca ISE showed information on the formation process of CaCO₃. Our results showed that as magnesium ions interfered with the binding of calcium and carbonate ions and delayed the aggregation between PNCs, the nucleation and formation of CaCO₃ were delayed. On the other hand, the temperature showed an opposite trend as compared to the effect of magnesium under our experimental conditions, indicating that temperature accelerated the formation of CaCO₃. Furthermore, the morphology of CaCO₃ clearly changed according to the Mg/Ca ratio and temperature, and it was confirmed that the two factors are very important for CaCO₃ formation in that they could affect the overall process.