• The Korean Journal of Pharmacology
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• v.24 no.2
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• pp.179-187
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• 1988

Verapamil, tetrodotoxin and tetraethylammonium chloride in the stated amount did not affect the $Na^{++}$ induced $Ca^{++}$ release. $Cd^{++}$ and $Zn^{++}$ significantly inhibited the $Na^{++}$ induced $Ca^{++}$ release. $Mn^{++}$ also inhibited $Na^+-Ca^{++}$ exchange. $Cd^{++}$ inhibited $Na^+-Ca^{++}$ exchange noncompetitively with an apparent inhibition constant (Ki) of $100\;{\mu}M$. $Cd^{++}$ caused loss of sulfhydryl group, whereas $Zn^{++}$ did not show any significant effect. $Cd^{++}$ and $Zn^{++}$ effectively inhibited $Na^+-Ca^{++}$ ATPase and slightly inhibited $Ca^{++}-Mg^{++}$ ATPase. Carbonyl cyanide chlorophenylhydrazone, 2,4-dinitrophenol and sodium arsenate stimulated the $Na^{++}$ induced $Ca^{++}$ release. Dibucaine and oligomycin slightly inhibited it. The results suggest that the $Na^+-Ca^{++}$ exchange on the synaptosomal plasma membrane may be not accomplished by ion channels. The $Na^+-Ca^{++}$ exchange is sensitively inhibited by $Cd^{++}$ and this transport process appears to be partially regulated by sulfhydryl groups of the synaptosomal plasma membrane. It is also postulated that $Na^+-Ca^{++}$ exchange is suppressed during the phosphorylation reaction of protein component on the neuronal membrane.

• Journal of the Korean Electrochemical Society
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• v.18 no.4
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• pp.161-171
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• 2015

High-yield zinc germanium oxide ($Zn_2GeO_4$) and zinc tin oxide ($Zn_2SnO_4$) nanowires were synthesized using a hydrothermal method. We investigated the electrochemical properties of these $Zn_2GeO_4$ and $Zn_2SnO_4$ nanowires as anode materials of lithium ion battery and sodium ion battery. The $Zn_2GeO_4$ and $Zn_2SnO_4$ nanowires showed excellent cycling performance of the lithium ion battery, with a maximum capacity of 1021 mAh/g and 692 mAh/g after 50 cycles, respectively, with a high Coulomb efficiency of 98 %. For the first time, we examined the cycling performance of $Zn_2GeO_4$ and $Zn_2SnO_4$ nanowires for sodium ion batteries. The maximum capacity is 168 mAh/g and 200 mAh/g after 50 cycles, respectively, with a high Coulomb efficiency of 97%. These nanowires are expected as promising electrode materials for the development of high-performance lithium ion batteries as well as sodium ion batteries.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.57.2-57.2
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• 2009

퍼클로레이트 이온($ClO_4^-$)는 자연적으로 혹은 인공적으로 만들어지며 퍼클로릭산이나 암모늄 퍼클로레이트나, 포타슘 퍼클로레이트 혹은 소듐퍼클로레이트 염의 형태로 존재하며, 물에 아주 잘 녹고, 끓여도 제거되지 않으며, 활성 탄소와 같은 광물에도 흡착 되지 않는 성질로 인해, 기존 물리적인 정수 방법으로는 제거하기 어렵다. 또한 우리 몸에 흡수되면, 요오드가 갑상선에 흡수되는 작용을 방해하여 갑상선 기능장애를 초래한다. 이러한 퍼클로레이트 이온의 제거방법으로는 이온교환법이나 생물학적 방법 등이 개발되어져 있으나, 제거 시스템에 이동 및 안전한 농도까지 제거 등의 문제점으로 인한 퍼클로레이트 이온을 환원시키는 촉매 환원 반응에 의한 퍼클로레이트 이온 제거 기술 개발이 필요하다. 이런 촉매 환원에 필요한 수소 환원제를 발생시키기 위해서, 본 연구에서는 Carbon felt 위에 DC magnetron sputtering에 의한 thin film $TiO_2$과 regine을 이용한 powder $TiO_2$ 시편을 제작하였다. 이렇게 제작 된 $TiO_2$/Carbon felt의 미세구조 및 특성은 XRD, SEM, UV-vis-NIR 등을 통하여 분석하였다. UV 조사에 의해 $TiO_2$/Carbon felt 시편의 산소와 수소 발생과 DC bias의 걸어주었을 때 산소와 수소 발생 차이 등을 비교하였고, 이에 따른 퍼클로 레이트 이온의 분해 영향을 알아보았다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.137-137
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• 2018

이 연구에서는 리튬이온전지용 음극 활물질의 리튬이온 저장 용량을 최적화시키기 위한 새로운 방법이 제안되었다. 그 방법은 솔루션 플라즈마 프로세스를 사용하여 원자 단위의 리튬을 탄소 기반 물질의 내부에 도핑 시키고, 열처리를 통해 그 내부를 재설계하는 것이다. 리튬이온전지용 음극 활물질로 리튬금속 자체를 사용하려는 시도는 있었으나, 이는 충전 및 방전 사이클이 반복됨에 따라 리튬이 수지상으로 석출되어 내부를 단락시키거나, 리튬금속 자체의 폭발성에 의한 취급상의 제약이 있었다. 한편, 원자 단위로 탄소 내부에 도핑 된 리튬은 열처리 과정 동안 탄소 내부에서 확산함으로써 더 많은 리튬이 저장될 수 있는 공간을 만들었고, 사이클이 반복됨에 따라 서서히 충전 및 방전 반응에 참여함으로써 전지의 성능을 개선시켰다. 리튬이 도핑 된 탄소의 전기화학적 테스트 결과를 Fig. 1에 나타내었다. 실험 결과에서 보여진 초기 고용량 및 장기 사이클 특성은 탄소 내부에 도핑 된 리튬이 전지 성능의 향상에 중요한 역할을 한다는 것을 시사한다. 또한, 사이클이 반복됨에 따라 점차 증가하는 용량은 첫 사이클에서 형성된 solid electrolyte interphase의 비가역 용량을 보상할 수 있을 것으로 생각된다. 이상의 결과를 통해, 탄소 내부에 원자단위의 리튬을 도핑시키는 새로운 접근은 리튬이온전지의 성능 개선을 위한 효과적인 방법이 될 수 있을 것으로 보이며, 향후 리튬 이외의 다른 원소들, 즉 소듐과 같은 물질에 대하여 도핑을 시도한다면 새로운 분야에서 이와 같은 접근법이 유용하게 적용될 수 있을 것으로 사료된다.

• Journal of the Korean Chemical Society
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• v.41 no.9
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• pp.488-494
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• 1997

Lithium and sodium ions have been intercalated into two dimensional structure of $FeMoO_4Cl$. The electronic localization and the large difference in unit cell parameter between the pristine material and the intercalates lead to the existence of large biphased domains. In the case of the lithium system, a narrow range of $Li_xFeMoO_4Cl$ ($0.95{\leq}x{\leq}1.06$) solid solution has been found around the $LiFeMoO_4Cl$ composition. The OCV curve fitting has been performed using Armand's model. The occurrence of several parts in the charge-discharge curve is related to the electronic and structural modifications of the material during the intercalation process.

• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.141-146
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• 2007

The present paper describes a procedure for separation, preconcentration and determination of trace amount of copper in natural water samples by using 2-mercaptobenzimidazol as the complexing agent. The proposed method is based on the surfactant aggregation formed on γ-alumina by mixing sodium dodecyl sulfate and γ-alumina in water; 2-mercaptobenzimidazol was incorporated into inner hydrophobic part of produced ad-micelles in acidic media to produce an assemble suitable for preconcentration and determination of copper ion. Optimum experimental conditions for adsorption of μg/ml levels of copper ions from aqueous solution by the adsorbent have been reported. The copper ions were quantitively adsorbed by the sorbent over the pH range of 7.1-8.0 and were quantitatively desorbed afterward by using sulfosalycilic acid as the eluent. The determination of copper was not interfered in the presence of common metal ions. The procedure was applied for analysis of river water sample. Relative standard deviation was found to be 4.91%.

• Resources Recycling
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• v.30 no.6
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• pp.3-11
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• 2021

In this study, the effect of the solubility of ammonium metavanadate and the decomposition ratio of ammonium ions on a precipitation reaction-the precipitation of ammonium metavanadate by adding ammonium chloride to a sodium vanadate solution-was investigated. As the precipitation temperature and pH increased, the decomposition ratio of ammonium ions increased, and the decomposition ratio was greater than 81% at 45 ℃ and pH 9.3. This was approximately four times higher than that at pH 8. The result of the precipitation reaction, in view of these two factors that significantly influence the precipitation reaction, was that the precipitation yield increased as the temperature increased. However, the effect of temperature was not significant above 35 ℃. A kinetic study of the precipitation reaction revealed that the activation energy of the reaction was 42.3 kJ/mol. Therefore, considering the solubility of ammonium metavanadate, the lower the temperature, the better the vanadium recovery yield. Additionally, considering the decomposition of ammonium ions, the lower the pH of the aqueous solution, the more advantageous. However, at pH 8 or less, sodium polyvanadate is precipitated and the purity of vanadium oxide may reduce.

• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.300-309
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• 2010

The ability of sodium-exchanged clay particles as an adsorbent for the removal of commercial dyes, Methylene blue (MB) and Malachite green oxalate (MG) from aqueous solutions has been investigated under various experimental conditions. The effect of the experimental parameters, such as pH solution, agitation time, adsorbate concentration and adsorbent dose were examined. Maximum adsorption of dyes, i.e. >90% has been achieved in aqueous solutions using 0.03 g of clay at a pH of 7 and 298 K for both dyes. The adsorption process was a fast and the equilibrium was obtained within the first 5 min. For the adsorption of both MB and MG dyes, the pseudo-second-order reaction kinetics provides the best correlation of the experimental data. The adsorption equilibrium results follow Langmuir and Dubini-Radushkevich (D-R) isotherms with high regression coefficients $R^2$ > 0.98. The mean free energies $E_a$ of adsorption from D-R model were 3.779 and 2.564 kj/mol for MB and MG respectively, which corresponds to a physisorption process.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.1
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• pp.1-5
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• 2003

Quarternary $Na_2O-B_2O_3-Al_2O_3-SiO_2$ glasses were fabricated by the function of $R({\equiv}Na_2O\;mole%/B_2O_3\;mole%)$ and $K({\equiv}(Al_2O_3\;mole%+SiO_2\;mole%)/B_2O_3mole%)$. The structures of these glasses were investigated through refractive index and vicker's hardness. The refractive index increased as the increase of the polarizability in the glass network. In the region of low $Na_2O$ content, the refractive index increased due to the increase of the polarizability in the glass network, but in the region of high $Na_2O$ content, the rate of increase of the refractive index decreased due to the increase of the molar volume caused by the formation of $BO_3{^-}$ units with relatively high molar volume. And, the refractive index decreased as the increase of $Al_2O_3+SiO_2$ content with the molar volume in the glass network. The increase and decrease of vicker's hardness values for those glasses depended on the fraction of tetrahedral $BO_4$ units and it of triangle $BO_3{^-}$ units with non-bridging oxygen, respectively.

• Journal of the Korean Electrochemical Society
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• v.23 no.1
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• pp.11-17
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• 2020

The Prussian blue analogues of Fe₂(CN)₆ and Na_xFe₂(CN)₆ are prepared by precipitation method and evaluated the electrochemical characteristics as positive electrode materials for lithium-ion batteries (LIBs) because of their low cost. Fe₂(CN)₆ shows a low reversible capacity of 34.6 mAh g^-1, whereas sodium-containing Na_xFe₂(CN)₆ exhibits a reversible capacity of 107.5 mAh g^-1 when the discharge process proceeds first. When charging is first carried out to remove sodium in the structure, the reversible capacity of 114.1 mAh g^-1 is achieved and the cycle performance is further improved. In addition, Na_x-Fe₂(CN)₆ is synthesized at 0℃, room temperature (RT), and 60℃, respectively. Regardless of the synthesis temperature, Na_xFe₂(CN)₆ shows similar initial reversible capacity, but the crystallite size is formed smaller and improved cycle performance when synthetic temperature is lower. The sample synthesized at 0℃ shows a reversible capacity of 86.4 mAh g^-1 at the 120^th cycle and maintains 76.8% of the initial capacity.