• Textile Coloration and Finishing
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• v.23 no.1
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• pp.51-59
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• 2011

Calcium alginate fiber were prepared by wet spinning of various conditions, including different concentrations of sodium alginate solution and $CaCl_2$ concentrations for coagulating the fiber through an absorption of calcium ion. The absorption of calcium ion during the coagulating step lead to solidify the fibers by the replacement of sodium ion with calcium ion to produce some crosslinking. The concentration of calcium ion in the calcium alginate fiber seems to be well related to the mechanical and physical property of the fiber, such as fiber strength moisture regain, and degree of swelling. The tensile strength of calcium alginate fiber was increased along with the increasing amount of sodium alginate solution. According to EDS analysis, 7 wt% $CaCl_2$ coagulation bath resulted in more calcium ion in the fiber compared to 3 wt% $CaCl_2$ coagulation bath. The decomposition temperature of calcium alginate fiber was $199^{\circ}C$, which $14^{\circ}C$ higher than that of sodium alginate.

• The Korean Journal of Pharmacology
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• v.31 no.3
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• pp.355-363
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• 1995

It has been well known that the intracellular calcium concentration $([Ca^{2+}]_i)$ in living cell is very sensitive to live or to survive, but the transmembrane system of calcium ion, especially mechanism of calcium ion movement in unexcitable state has been little elucidated. Though many proposed theories for calcium ion transport have been reported, it is still unclear that how could the sustained maintenance in cytosolic calcium level be done in cell. Since one of possible mechanisms of calcium transport may be related to the acetylcholine receptor-linked calcium channel, author performed experiment to elucidate this mechanism of calcium influx related to cholinergic receptor in ml muscarinic receptor-transfected RBL-2H3 cell-line. 1) The effects of carbachol both on calcium ion influx and on the secretion of hexosaminidase were respectively observed in the manner of time-related or concentration-dependent pattern in this model. 2) The effects of several metal cations on calcium transport were shown in carbachol-induced cell-line. 3) Atropine was administered to examine the relationship between cholinergic receptor and calcium ion influx in this model. 4) PMA (Phorbol 12-myristate 13-acetate) or PTx (Pertussis toxin) was respectively administered to examine the secondary mediator which involved pathway of calcium ion movement in carbachol-induced cell-line. The results of this experiments were as follows; 1) Carbachol significantly stimulated both the calcium influx and the secretion of hexosaminidase in the manner of the concentration-dependent pattern. 2) Atropine potently blocked the effects of carbachol in concentration-response manner. 3) Administered metal cations inhibited the calcium influx in carbachol-stimulated this model to the concentration-related pattern. 4) PMA did not inhibit carbachol-induced secretion of hexosaminidase, but blocked the calcium influx in this cell-line. 5) The suppression of carbachol-induced hexosaminidase secretion was shown in PTx-treated cell -line.

• BMB Reports
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• v.44 no.10
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• pp.635-646
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• 2011

Due to its high external and low internal concentration the $Ca^{2+}$ ion is used ubiquitously as an intracellular signaling molecule, and a great many $Ca^{2+}$-sensing proteins have evolved to receive and propagate $Ca^{2+}$ signals. Among them are ion channel proteins, whose $Ca^{2+}$ sensitivity allows internal $Ca^{2+}$ to influence the electrical activity of cell membranes and to feedback-inhibit further $Ca^{2+}$ entry into the cytoplasm. In this review I will describe what is understood about the $Ca^{2+}$ sensing mechanisms of the three best studied classes of $Ca^{2+}$-sensitive ion channels: Large-conductance $Ca^{2+}$-activated $K^+$ channels, small-conductance $Ca^{2+}$-activated $K^+$ channels, and voltage-gated $Ca^{2+}$ channels. Great strides in mechanistic understanding have be made for each of these channel types in just the past few years.

• BMB Reports
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• v.55 no.11
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• pp.528-534
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• 2022

Mitochondria are cellular organelles that perform various functions within cells. They are responsible for ATP production, cell-signal regulation, autophagy, and cell apoptosis. Because the mitochondrial proteins that perform these functions need Ca²⁺ ions for their activity, mitochondria have ion channels to selectively uptake Ca²⁺ ions from the cytoplasm. The ion channel known to play the most important role in the Ca²⁺ uptake in mitochondria is the mitochondrial calcium uniporter (MCU) holo-complex located in the inner mitochondrial membrane (IMM). This ion channel complex exists in the form of a complex consisting of the pore-forming protein through which the Ca²⁺ ions are transported into the mitochondrial matrix, and the auxiliary protein involved in regulating the activity of the Ca²⁺ uptake by the MCU holo-complex. Studies of this MCU holo-complex have long been conducted, but we didn't know in detail how mitochondria uptake Ca²⁺ ions through this ion channel complex or how the activity of this ion channel complex is regulated. Recently, the protein structure of the MCU holo-complex was identified, enabling the mechanism of Ca²⁺ uptake and its regulation by the MCU holo-complex to be confirmed. In this review, I will introduce the mechanism of action of the MCU holo-complex at the molecular level based on the Cryo-EM structure of the MCU holo-complex to help understand how mitochondria uptake the necessary Ca²⁺ ions through the MCU holo-complex and how these Ca²⁺ uptake mechanisms are regulated.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.219-224
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• 2021

Ion flotation is an efficient method to remove metal ions from aqueous solution. In this work, ion flotation was applied to calcium removal from aqueous solution. The parameters used included sodium stearate (SS) and sodium dodecyl sulfate (SDS) as collectors, 1-butanol and 1-propanol as frothers, pH, and air-flow rate. An L16 orthogonal array was chosen according to the mentioned factors and levels, and experimental tests were conducted according to the Taguchi orthogonal array. The results showed that all of the factors except one had significant effect on the flotation performance. The percentage contribution of parameters showed that type of frother and type of collector made the greatest (43.14%) and the lowest (9.86%) contribution, respectively. In optimal conditions, the recovery of Ca (II) ion was 45.67%. Also, the results illustrated that the Taguchi method could predict calcium removal from aqueous solution by ion flotation with 2.63%. This study showed that the use of ion flotation was an effective method for Ca (II) ion removal from aqueous solution.

• Analytical Science and Technology
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• v.18 no.6
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• pp.491-494
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• 2005

The main component governing selectivity in ion-selective electrodes and optodes is the ionophore. For this reason, a member of natural products that possess selective ion-binding properties have long been sought after. By applying this principle, the performance of cyclosporin used as neutral carriers for calcium selective polymeric membrane electrode was investigated. The calcium ion-selective electrode based on cyclosporin gave a good Nernstian response of 26.6 mV per decade for calcium ion in the activity range $1{\times}10^{-6}M$ to $1{\times}10^{-2}M$. The optimized calcium ion-selective electrode displayed very comparable selectivity for $Ca^{2+}$ ion against alkali and alkaline earth metal ions, $Na^{2+}$, and $Mg^{2+}$ in particular.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.291-298
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• 1988

The effect of Vanadate on the isometric contraction, membrane potential and intracellular calcium ion activities of rabbit myocardial cells were investigated, using calcium selective microelectrode, filled with neutral calcium ion carrier, ETH-1001. The resting tension, the membrane potential and the intracellular calcium ion activities were recorded in normal Tyrode solution and compared with those in the contracture induced by 10 mM Vanadate. The following results were obtained: 1. The dose-response relationship between the contraction of Vanadate and twitch tension showed near-maximum response in 5mM with no corresponding changes in action potential. 2. The resting tension increased up to the amplitude of a control twitch in 10mM Vanadate with resting membrane potential, hyperpolarized. 3. Increase in intracellular calcium ion activities proceeded the contracture by 10mM Vanadate which were restored to the control level in accordance with a decrease of intracellular calcium ion activities. 4. The amplitude of contractures by 10mM Vanadate were 90-120% of the control twitch tension in which the intracellular calcium ion activities were increased about 70 times from p Ca, 7.1 in the control to p Ca, 5.8 in contractures.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.43-48
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• 2018

In this study, we performed various extraction condition experiments such as types and concentrations of extractants, amounts of extraction sources, pretreatment processes, to optimize the calcium ion extraction for precipitated calcium carbonate (PCC) production. CaO was used as a calcium extraction source, The extraction amount of calcium ions and the particle size of CaO were determined by ICP and SEM results. As a result, 100% calcium ion was extracted when 2 M hydrochloric acid was used as an extractant, and the optimum amount of the extraction source was 6 g. On the other hand, it was confirmed that the reaction time, reaction temperature, particle milling and heat treatment process had no significant effect on the calcium ion extraction amount.

• Korean Journal of Veterinary Research
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• v.31 no.1
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• pp.123-130
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• 1991

The present study was performed to investigate the effect of Ca ion concentration on sperm viability and acrosome reaction rate and to evaluate the effect of treatments using caffeine and Ca-ionophore A23187 on acrosome reaction rate in frozen-thawed bull spermatozoa. Viabilities of in vitro capacitated bull spermatozoa at 0, 2.25 and 4.5 mM Ca ion concenrations were 21.00, 26.00 and 22.59%, respectively and significantly higher in Ca ion 2.25mM added group than Ca ion free group (p<0.05) and acrosome reaction rates of in vitro capacitated bull spermatozoa were 17.09, 52.15 and 47.92%, respectively and significantly high in Ca ion added groups(p<0.05). Viabilities in vitro capacitation by caffeine and Ca-ionophore A23187 in control, caffeine treated group, Ca-ionophore A23187 treated group and caffeine+Ca-ionophore A23187 treated group were 37.91, 27.67, 22.33 and 25.59%, respectively and significantly higher in control than treated groups(p<0.05), there were no significant differences among the treated groups, and acrosome reaction rates were 10.33, 37.92, 48.09 and 57.17%, respectively and there were significant differences among the groups(p<0.05), especially higher in caffeine+Ca-ionophore A23187 treated group than others.

• Analytical Science and Technology
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• v.5 no.4
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• pp.401-408
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• 1992

The ion-selectrodes based on calcium ferrite were prepared by mixing calcium oxide with ferric oxide on molar ratio of 0.6:1.4, 0.8:1.2, 1.0:1.0, respectively. The specimens were sintered at $1400^{\circ}C$ for 2hrs in $O_2$ and for 20min in $H_2$ atmosphere. The selectrode sintered in hydrogen atmosphere showed better responded potential and wider range of responded concentration than selectrode sintered in oxygen atmosphere. The ion-selectrodes base on calcium ferrite(0.6:1.4 molar ratio.) showed the highest potential to bivalent cations such as $Ca^{2+}$, $Ba^{2+}$, $Mg^{2+}$, $Zn^{2+}$ and halogen anions such as $I^-$, $Br^-$ in the range of $10^{-1}{\sim}10^{-7}M$. It showed good agreement with theoretical nernstian values.