• Economic and Environmental Geology
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• v.36 no.2
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• pp.75-87
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• 2003

The Haman-Gunbuk mineralized area is located within the Cretaceous Gyeongsang Basin along the southeastern part of the Korean peninsula. Major ore minerals, magnetite, scheelite, molybdenite and chalcopyrite, together with base-metal sulfides and minor sulfosalts, occur in fissure-filling tourmaline, quartz and carbonates veins contained within Cretaceous sedimentary and volcanic rocks anu/or granodiorite (118{\pm}$3.0 Ma). The ore and gangue mineral paragenesis can be divided into three distinct stages: Stage 1, tourmaline+quartz+Fe-Cu ore mineralization; Stage II, quartz+sulfides+sulfosalts+carbonates; Stage 111, barren calcite. Earliest fluids are recorded in stage I and early por-tions of stage II veins as hypersaline (35~70 equiv. wt.% NaCl+KCl) and vapor-rich inclusions which homogenize from ~30$0^{\circ}C$ to $\geq$50$0^{\circ}C$. The high-salinity fluids are complex chloride brines with significant concentrations of sodium, potassium, iron, copper, and sulfur, though sulfide minerals are not associated with the early mineral assemblage produced by this fluid. Later solutions circulated through newly formed fractures and reopened veins, and are recorded as lower-salinity(less than ~20 equiv. wt.% NaCl) fluid inclusions which homogenize primarily from ~200 to 40$0^{\circ}C$. The oxygen and hydrogen isotopic compositions of fluid in the Haman-Gunbuk hydrothermal system represents a progressive shift from magmatic-hydrothermal dominance during early mineralization stage toward meteoric-hydrothermal dominance during late mineralization stage. The earliest hydrothermal fiuids to circu-late within the granodiorite stock localiring the ore body at Haman-Gunbuk could have exsolved from the crystal-lizing magma and unmixed into hypersaline liquid and $H_2O$-NaCl vapor. As these magmatic fluids moved throughfractures, tourmaline and early Fe, W, Mo, Cu ore mineralization occurred without concomitant deposition of othersulfides and sulfosalts. Later solutions of dominantly meteoric origin progressively formed hypogene copper and base-metal sulfides, and sulfosalt mineralization.

• The Korean Journal of Food And Nutrition
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• v.17 no.3
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• pp.294-301
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• 2004

Effects of superoxide dismutase(SOD), catalase(CAT), and such other proteins as bovine serum albumin(BSA), ovalbumin, lysozyme, and v-globulin on the autoxidation rates of L-ascorbic acid(AsA) in the absence of heavy metal ions and in the presence of Fe(III) or Cu(II) ions in water were examined. AsA was dissolved in a ultra-refined water at a concentration of 50 ${\mu}$M and 5 ${\mu}$M Fe(III) or 0.1 ${\mu}$M Cu(II) were added, and a oxygen gas was bubbled through the solution at a flow rate of 200 ml/min at 35$^{\circ}C$. The amount of remaining AsA in the reaction mixture was determined by using a UV spectrophotometer(at 265 nm). It was found that the Cu(II) at a concentration of 0.1 ${\mu}$M had a more accelerated for the autoxidation of AsA than Fe(III) at 5 ${\mu}$M. Moreover, it was confirmed that the ratio of remaining AsA was significantly larger in the presence of SOD, CAT, BSA, ovalbumin, lysozyme, and v-globulin than in the absence of proteins. The stabilization of AsA by various proteins were confirmed during the autoxidation of AsA in the presence of Fe(III) or Cu(II) in water. It was suggested that the non-enzymatic effects of SOD, CAT and some other proteins might be involves in the stabilization of AsA.

• Economic and Environmental Geology
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• v.35 no.1
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• pp.1-12
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• 2002

Manus Basin, located in the equatorial western Pacific, is a back arc basin formed by collision between the IndoAustralian and the Pacific Plates. The basin is host to numerous hydrothermal vent fields and ore deposits. The basement rocks of the Manus Basin consist primarily of dacite and basaltic andesite. Some of the minerals that form the hydrothermal chimneys that were dredged on the Manus basin include pyrite, chalcopyrite, marcasite, sphalerite and galena. The chimneys can be classified into chalcopyrite dominant Cu-rich type and sphalerite dominant Zn-rich type. The concentration of Zn shows good positive correlation with that of Sb, Cd and Ag. The content of Cu, on the other hand, positively correlates with that of Mo, Mn and Co. For samples that were taken from Zn-rich chimney, a strong positive correlation is found between Au and Zn contents. The chimney also shows enrichments of Cd, Mn and Sb. On the other hand, the samples from Cu-rich chimney exhibit strong correlation among Au, Zn and Pb, and are enriched in Mo and Co concentration. Average contents of Au in Cu-rich and Znrich chimneys were 15.9 ppm and 29.0 ppm, respectively. Because of high concentration of Au with Ag and Cu, the ore deposit have high economic potential. Homogenization temperatures and salinities of fluid inclusions in anhydrite and amorphous silica from Zn-rich chimney are estimated to be l74-220$^{\circ}$C and 2.7-3.6 equiv. wt. % NaCI, respectively. These value suggest that ore forming processes were occurred at around 200$^{\circ}$C and that the oxygen fugacity changed from 2: 10$^{-39.5}$bar to -s: 10$^{-40.8}$bar and the sulfur fugacity from -s: 10$^{-14.7}$bar to 10$^{-13.4}$bar during the process. It appears that the temperature at which the ores formed on Cu-rich chimney was higher than that on Zn-rich chimney.

• Economic and Environmental Geology
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• v.22 no.1
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• pp.35-63
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• 1989

Geochemical characteristics of the Guryongsan (Ogcheon) uraniferous black slate show that this is an analogue to the conventional Chattanooga and Alum shales in occurrences. Whereas, its highest enrichment ratio in metals including uranium, among others, is explained by the cyclic sedimentation of the black muds and quartz-rich silts, and the uniform depositional condition with some what higher pH condition compared to the conditions of the known occurrences. The cyclic sedimentation, caused by the periodic open and close of the silled basin, has brought about the flush-out) of the uranium depleted water and the recharge with the new metal-rich sea water, which consequently contributed to the high concentration of metals in mud. The metal-rich marine black muds, which mostly occur in the early to middle Palaeozoic times, is attributed by the geologic conditions which related to the atmospheric oxygen contents, and these are scarcely met in the late Precambrian and/or with the onset of Palaeozoic era in the geologic evolution of the earth.

• Journal of the Korean Chemical Society
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• v.44 no.2
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• pp.95-101
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• 2000

Macroacyclic transition metal complexes such as $Cu(H_2L[A]).H_2O$, $Cu(H_2L[B]).H_2O$, CuFe(L[A]($NO_3$).$4H_2O$, CuFe(L[B])($NO_3$).$4H_2O$, [$CuGd(H_2L[A])(NO_3)_2](NO_3).2CH_3OH$, [CuGd($H_2L$[B])($NO_3)_2$]($NO_3).2CH_3OH were prepared from the corresponding hexadentate compartmental ligands, $H_4L[A]$ and $H_4L[B]$, which were obtained by the condensation of 2-hydroxy-3-hydroxymethy1-5-methyIbenzaldehyde(HHNNB) and ethylenediamine or l,3-diaminopropane. Ln-macrocyclic([20]DOTA) complexes,[Ln([20]DOTA)($NO_3)(H_2O)$]($NO_3$)2.$xH_2O${Ln(III)=Pr, Sm, Gd, Dy, which had been synthesized from 2,6-diformyl-p-cresol(DFPC), was placed in methanol for 2 days, and [Ln([20] DOTA)($NO_3)(CH_3OH)]^{2+}$ was formed The equilibrium constants (k) for the substitution of coordinated $CH_3OH$ in the Ln-[20]DOTA complexes by various bidentate auxiliary ligands, $L_a$(=o-phenylenediamine,1,10-phenanthroline, ethylenediamine,oxalicacid, malonic acid, acethylacetone) were determined by spectroscopic method at $25^{\circ}C$ and 0.1M $NaClO_4$.The pKa of auxiliary ligands is in the order of o-phenylenediamine < 1,10-phenanthroline < ethylene-diamine, oxalic acid < malonic acid < acethylacetone. However, the equilibrium constant(K) has shown thetrend of ethyleneiamine < 1,10-phenanthroline < o-phenylenediamine, acethylacetone < malonic acid < oxalic acid.

• Resources Recycling
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• v.28 no.6
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• pp.79-86
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• 2019

Recently, the use of lithium ion battery(LIB) has increased. As a result, the price of lithium and the amount spent lithium on ion battery has increased. For this reason, research on recycling lithium in waste LIBs has been conducted1). In this study, the effect of roasting for the selective lithium leaching from the spent LIBs is studied. Chemical transformation is required for selective lithium leaching in NCM LiNi_xCo_yMn_zO₂) of the spent LIBs. The carbon in the waste EV cell powder reacts with the oxygen of the oxide at high temperature. After roasting at 550 ~ 850 ℃ in the Air/N₂ atmosphere, the chemical transformation is analysed by XRD. The heat treated powders are leached at a ratio of 1:10 in D.I water for ICP analysis. As a result of XRD analysis, Li₂CO₃ peak is observed at 700 ℃. After the heat treatment at 850 ℃, a peak of Li₂O was confirmed because Li₂CO₃ is decomposed into Li₂O and CO₂ over 723 ℃. The produced Li₂O reacted with Al at high temperature to form LiAlO₂, which does not leach in D.I water, leading to a decrease in lithium leaching ratio. As a result of lithium leaching in water after heat treatment, lithium leaching ratio was the highest after heat treatment at 700 ℃. After the solid-liquid separation, over 45 % of lithium leaching was confirmed by ICP analysis. After evaporation of the leached solution, peak of Li₂CO₃ was detected by XRD.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.4
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• pp.599-604
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• 1998

We have investigated Pt and $RuO_2$ as a bottom electrode for ferroelectric capacitor applications. The bottom electrodes were prepared by using an RF magnetron sputtering method. Some of the investigated parameters were a substrate temperature, gas flow rate, RF power for the film growth, and post annealing effect. The substrate temperature strongly influenced the surface morphology and resistivity of the bottom electrodes as well as the film crystallographic structure. XRD results on Pt films showed a mixed phase of (111) and (200) peak for the substrate temperature ranged from RT to $200^{\circ}C$, and a preferred (111) orientation for $300^{\circ}C$. From the XRD and AFM results, we recommend the substrate temperature of $300^{\circ}C$ and RF power 80W for the Pt bottom electrode growth. With the variation of an oxygen partial pressure from 0 to 50%, we learned that only Ru metal was grown with 0~5% of $O_2$ gas, mixed phase of Ru and $RuO_2$ for $O_ 2$ partial pressure between 10~40%, and a pure $RuO_2$ phase with $O_2$ partial pressure of 50%. This result indicates that a double layer of $RuO_2/Ru$ can be grown in a process with the modulation of gas flow rate. Double layer structure is expected to reduce the fatigue problem while keeping a low electrical resistivity. As post anneal temperature was increased from RT to $700^{\circ}C$, the resistivity of Pt and $RuO_2$ was decreased linearly. This paper presents the optimized process conditions of the bottom electrodes for memory device applications.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.1
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• pp.14-22
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• 2020

Purpose: The aim of this study is to evaluate the effectiveness of MnO₂-diatom microbubbler (DM) on the surface of prosthetic materials as a mouthwash by comparing the biofilm removal effect with those previously used as a mouthwash in dental clinic. Materials and methods: DM was fabricated by doping manganese dioxide nanosheets to the diatom cylinder surface. Scanning electron microscopy (SEM) was used to observe the morphology of DM and to analyze the composition of doped MnO₂. Stereomicroscope was used to observe the reaction of DM in 3% hydrogen peroxide. Non-precious metal alloys, zirconia and resin specimens were prepared to evaluate the effect of biofilm removal on the surface of prosthetic materials. And then Streptococcus mutans and Porphyromonas gingivalis biofilms were formed on the specimens. When 3% hydrogen peroxide solution and DM were treated on the biofilms, the decontamination effect was compared with chlorhexidine gluconate and 3% hydrogen peroxide solution by crystal violet staining. Results: Manganese dioxide was found on the surface of the diatom cylinder, and it was found to produce bubble of oxygen gas when added to 3% hydrogen peroxide. For all materials used in the experiments, biofilms of the DM-treated groups got effectively removed compared to the groups used with chlorhexidine gluconate or 3% hydrogen peroxide alone. Conclusion: MnO₂-diatom microbubbler can remove bacterial membranes on the surface of prosthetic materials more effectively than conventional mouthwashes.

• Korean Journal of Food Science and Technology
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• v.38 no.3
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• pp.452-455
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• 2006

The in vitro cytoprotective and anti-oxidative effects of ursodeoxycholic acid, a major active compound from bear's gall were investigated in mouse brain microglia. In the present study, we wished to scrutinize the potential role of UDCA as an anti-neurodegenerative agent in neurodegenerative disease such as Alzheimer's disease. This concept was supported by the multiple preliminary studies in which UDCA has an anti-inflammatory effect in microglial cells. In the study, we found that $7.5\;{\mu}g/mL$ UDCA was effective in the protection of cells from $H_2O_2$ damage, a reactive oxygen, and the resuIt was coincided with the anti-apoptotic effect in DAPI staining. Moreover, the metal-catalyzed oxidation study showed that UDCA has antioxidant effect as much as ascorbic acid at $50{\sim}100\;{\mu}g/mL$. In conclusion, these study results suggested that neuro-degenerative diseases such as Alzheimer's disease probably caused by over-expressed beta amyloid peptide in elderly people can be controled by UDCA through an anti-inflammatory, anti-oxidative and anti-apoptotic effect. The evidences showed in the study may be references for more in-depth in vivo and clinical studies for a candidate of anti-neurodegenerative therapy in the near future.

• Tuberculosis and Respiratory Diseases
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• v.56 no.2
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• pp.187-197
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• 2004

Background : Nitric Oxide (NO) is a multi-faceted molecule with dichotomous regulatory roles in many areas of biology. NO can promote apoptosis in some cells, whereas it inhibits apoptosis in other cell types. This study was performed to characterize NO-induced cell death in lung epithelial cells and to investigate the roles of cell death regulators including iron, bcl-2 and p53. Methods : A549 cells were used for lung epithelial cells. SNP (sodium nitroprusside) and SNAP (S-nitroso-N-acetyl- penicillamine) were used for NO donor. Cytoxicity assay was done by MTT assay and crystal violet assay. Apoptotic assay was done by fluorescent microscopy after double staining with propidium iodide and hoecst 33342. Iron inhibition study was done with RBCs and FeSO4. For bcl-2 study, bcl-2 overexpressing cells (A549-bcl-2) were used and for p53 study, Western blot analysis and p53 functionally knock-out cells (A549-E6) were used. Results : SNP and SNAP induced dose-dependent cell death in A549 cells and fluorescent microscopy revealed that SNAP induced apoptosis in low doses but necrosis in high doses while SNP induced exclusively necrotic cell death. Iron inhibition study using RBCs and FeSO4 significantly blocked SNAP-induced cell death. And also SNAP-induced cell death was blocked by bcl-2 overexpression. Finally, we found that SNAP activate p53 by Western blot analysis and that SNAP-induced cell death was decreased in the abscence of p53. Conclusion : In lung epithelial cells, NO can induce cell death, more precisely apoptosis in low doses and necrosis in high doses. And iron, bcl-2, and p53 play important roles in NO-induced cell death.