• Resources Recycling
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• v.27 no.6
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• pp.53-58
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• 2018

Solvent extraction of Li(I) from weak HCl solution was investigated by the mixture of TBP/MIBK with other neutral extractants such as Cyanex 923, TOPO and TOP. The TBP/MIBK organic phase was loaded with 0.1 M $FeCl_3$ at different HCl concentrations (1-9 M). Extraction of Li(I) from weak HCl solution is related to the stability of $FeCl_3$ in the organic mixture. As HCl concentration increased in preparing the loaded TBP phase, the stripping percentage of Fe(III) during the extraction of Li(I) became reduced and thus Li(I) could be extracted by ion exchange reaction with hydrogen ion in the organic. The concentration of TBP in the extractant mixture affected the stability of $FeCl_3$. Compared to TBP, Fe(III) was easily stripped from the loaded MIBK and thus no Li(I) was extracted by the mixture with MIBK. The nature of neutral extractant with TBP/MIBK showed little difference in the extraction of Li(I) and stripping of Fe(III).

• Microbiology and Biotechnology Letters
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• v.50 no.2
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• pp.211-217
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• 2022

Sodium hypochlorite (NaClO) is a disinfectant widely used in hospitals and food industries because of its antimicrobial activity against not only bacteria but also fungi and virus. The antibacterial activity of NaClO lies in the maintenance of a stable hypochlorous acid (HClO) concentration, which is regulated by pH of the solution. HClO can easily penetrate bacterial cell membrane due to its chemical neutrality and the antibacterial activity of NaClO is thought to depend on the concentration of HClO in solution rather than hypochlorite ions (ClO^-). In this study, we investigated the antibacterial activity of NaClO according to pH adjustment by means of time kill test and assays of Reactive Oxygen Species (ROS) and adenosine triphosphate (ATP) concentration changes before and after NaClO treatment. We also investigated that the degree of cell wall destruction through field emission scanning electron microscopy (FE-SEM). Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) exposed to 5 ppm NaClO at pH 5 exhibited 99.9% mortality. ROS production at pH 5 was 48% higher than that produced at pH 7. In addition, the ATP concentration in E. coli and S. aureus exposed to pH 5 decreased by 94% and 91%, respectively. As a result of FE-SEM, it was confirmed that the cell wall was destroyed in the bacteria by exposing to pH 5 NaClO. Taken together, our results indicate that the antibacterial activity of 5 ppm NaClO can be improved simply by adjusting the pH.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.574-580
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• 2019

ATP drives the conformational change of the group II chaperonin from the open lid substrate-binding conformation to the closed lid conformation to encapsulate an unfolded protein in the central cavity. It is thought that the folding activity of group II chaperonin is strongly correlated with the ATP-dependent conformational change ability. In order to confirm the dependence of the reaction temperature and ATP concentration of PhCpn, the ATPase activities were measured under different reaction temperatures and ATP concentrations. The maximal ATPase activity of PhCpn was observed at 80℃ and 3 mM ATP concentration. As a result of ATPase activity according to the type of salt ions, the highest activity was observed at 300 mM LiCl among the univalent cations and 5 mM MgCl₂ among the divalent cations, respectively. The values of Km and Vmax for ATP substrate were estimated as 2.17 mM and 833.3 μM/min, respectively. This results provide the enzymatic information of PhCpn when the prolonged and high activities of pharmaceutical and industrial proteins (or enzymes), by using chaperonin molecules, are required.

• Journal of Environmental Impact Assessment
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• v.19 no.3
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• pp.281-296
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• 2010

방그라데시 북부에 위치한 풀바리 우파질라 지역의 지하수에서 pH, EC, 주요 양이온 ($Ca^{2+}$, $Mg^{2+}$, $Na^+$, $K^+$, $Zn^{2+}$, $Cu^{2+}$, $Mn^{2+}$, $Fe^{3+}$, and $As^{3+}$), 주요 음이온 (${CO_3}^{2-}$, $HCO_3{^-}$, $NO_3{^-}$, ${SO_4}^{2-}$ and $Cl^-$) 그리고 total dissolved solids (TDS) 등의 용존물질 함량을 측정하였다. 또한 sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), 경도 등의 지표도 계산하였다. 전체적으로 지하수의 pH는 약알칼리성 (6.24 - 8.10)을 띄었으며, 주요 양이온은 $Ca^{2+}$, $Mg^{2+}$ and $Na^+$ 이었고, 주요 음이온은 $HCO_3{^-}$ and $Cl^-$ 으로서 전형적인 담수의 이온조성을 보였다. $Cu^{2+}$, $Mn^{2+}$ and $Fe^{3+}$ 의 최대 농도는 각각 1.71, 0.606, 0.125 mg/L 이었다. 방글라데시의 여러 지역에서는 비소에 의한 지하수의 오염이 흔히 나 타나고 있으나 이지역에서 비소의 최대농도가 0.41 mg/L로서 기준치인 0.05 mg/L 보다 낮은 오 염도를 보였다. TDS와 SAR, SSP 등으로 볼 때 이 지역의 지하수는 대부분 양호한 수질을 가지는 담수인 것으로 평가된다. $As^{3+}$, $Zn^{2+}$, $Mn^{2+}$, $Fe^{3+}$, ${SO_4}^{2-}$, $NO_3{^-}$ and $Cl^-$ 등의 농도는 음용수로 적합한 수준이었으나 일부 항목은 특정 산업용도로는 부적합한 농도를 보였다. 현재로서는 이지역 의 지하수는 대부분 음용이 가능하고 일부 산업용에 대해서만 부적합성을 보였다. 그러나 앞으로 지 하수의 이용과 산업활동이 증가하면 방글라데시의 많은 다른 지역의 지하수에서 발생한 사례와 같 이 용존물질의 농도가 증가하여 물의 용도에 제한을 받게 될 우려가 있다.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.378-386
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• 2019

In the present paper we report the calculation results of operation energy consumption for dissolved ions concentration technologies using vacuum evaporation (VE) and hydrate formation. Calculations were conducted assuming the tenfold concentration of saline water (0.35 wt% NaCl solution) of 1 mol/s at room temperature and atmospheric pressure employing vacuum evaporation at $69^{\circ}C$ and 30 kPa and hydrate-based concentration using $CH_4$, $CO_2$ and $SF_6$ as guest molecules. Operation energy consumption of VE-based concentration resulted in 47 kJ/mol, whereas those of hydrate-based concentration were 43, 32, and 28 kJ/mol for $CH_4$, $CO_2$ and $SF_6$ hydrates, respectively. We observe that hydrate-based concentration can a competitive option for dissolved ions recovery from energy consumption standpoint. However, the selection of guest gas is very critical, since it accordingly determines the hydration number, the hydrate formation energy, gas compression energy, etc. The selection of guest gas, separation of concentrated brine and water phases, and the enhancement of hydrate formation rate are the key factors for the commercialization of hydrated-based technology for concentrating dissolved ions.

• Korean Journal of Crystallography
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• v.17 no.2
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• pp.41-45
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• 2006

The complex $cis-[Co(13-aneN_4)(N_3)_2]Cl\cdot H_2O$ (1) (13-ane$N_4$ = 1,4,7,10-tetraazacyclotridecane) has been synthesized and structurally characterized by X-ray crystalloaraphy. It crystallizes in the orthorhombic system Pbca, a = 7.8282(4) ${\AA}$, b = 14.3197(7) ${\AA}$, c = 29.9021(15) ${\AA}$, V = 3351.9(3) ${\AA}^3$, Z = 8. The cobalt(III) ion in 1 is coordinated to four nitrogen atoms from the macrocycle and two azide ligands of cis position in a distorted octahedral environment, which forms the 1D polymer through hydrogen bonding contacts involving the cation, chloride anion and solvent water molecules.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.2
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• pp.86-91
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• 2005

The layered structure of organic-inorganic perovskite hybrids, $(C_nH_{2n+1}NH_3)_2CuC1_4$ (n = 6, 8, 10, 12) have synthesized. In $(C_nH_{2n+1}NH_3)_2CuC1_4$ compounds, the long-chain protonated alkylammonium ions as tilted bilayer type are inserted into perovskite-type layers of corner sharing $CuCl_6$ octahedron. Three solid phases have been characterized in the perovskite layered compound $(C_nH_{2n+1}NH_3)_2CuC1_4$ using HT-XRD and DSC. The $(C_nH_{2n+1}NH_3)_2CuC1_4$ compounds shows solid-solid phase transitions with stepwise increasing of the layer distance. Three different structures are explained by the conformational change of the long-chain protonated alkylammonium ions.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.779-785
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• 1994

The interaction between the cationic dye, thionin(Th) and the anionic surfactant, sodium dodecyl sulfate (SDS) has been investigated by absorption spectra. As the temperature of surfactant solution was increased in premicellar range(S/D=10, 80, and 160) which was much lower than the critical micelle concentration(CMC), the increment or decrement of the molar extinction coeffecient ratio appeared. It was found that the most stable temperature range of the oligomer aggregate in Th-SDS system at S/D=160 was below $60^{\circ}C$. With increasing the concentration of inorganic salt and organic solvents in Th-SDS system, ${\alpha}$-band was increased, but ${\gamma}$=band or J-band was decreased. The orders of ${\alpha}$-band increasing power were $Cl^-$>$ClO{_4}{^-}$>$SO{_4}{^{2-}}$>$NO{_3}{^-}$ and 2-propanol>ethanol>methanol>ethylene glycol.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.433-442
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• 1996

Electrochemical characteristics and physical properties of polymer electrolyte which immobilized lithium salts such as $LiClO_4$ and $LiCF_3SO_3$ and plasticizers such as ethylene carbonate(EC) and propylene carbonate(PC) in high molecular weight poly(ethylene oxide)[PEO] polymer was investigated. PEO-Li based polymer electrolyte with plasticizers showed ionic conductivity of $10^{-4}S/cm$ at room temperature and high electrochemical stability up to 4.5 V(vs. $Li^+/Li$), so it can be applied to lithium secondary battery. The crystallinity of PEO decreased with the addition of lithium salts and plasticizers, especially $LiClO_4$ and PC showed more effective than and $LiCF_3SO_3$ and EC. Glass transition temperature($T_g$) of polymer electrolyte increased with increasing lithium salt concentration whereas melting temperature ($T_m$) decreased. Polymer electrolyte with plasticizers crystallized at $6^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.33 no.5
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• pp.510-515
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• 1989

New nickel(II) and coppr(II) complexes of a saturated pentaaza macrobicyclic ligand $[Ni(D)]^{2+},\;[Cu(D)]^{2+},\;and\;[Cu(D)Cl]^+$, where D is 1,3,6,9,12-pentaazabicyclo[10,2,l]pentadecane, have been prepared by the template condensation reaction of tetraethylenepentamine and formaldehyde in the presence of the metal ion. The complexes contain one imidazolidine ring in the macrobicyclic ligand, D. The complexes $[Ni(D)]^{2+}\;and\;[Cu(D)]^{2+}$ have square planar geometry with 5-5-5-6 chelate ring sequence. The electronic spectra of $[Cu(D)Cl]^+$indicate that the complex has square pyramidal geometry. Synthesis, charactrization, and the spectroscopic and chemical properties of the macrobicyclic nickel(II) and copper(II) complexes are described.