• Applied Biological Chemistry
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• v.37 no.5
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• pp.356-360
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• 1994

The optimum pH and temperature for endo-polygalacturonase activity from Jujube were 5.0 and $50^{\circ}C$. The range of its stability to pH was 4.0 to 5.0. The enzyme was inactivated about 35% by treatment at $70^{\circ}C$ for 1 hr. It was found that $Ag^+$, $Zn^{++}$ and $Mg^{++}$ increased the enzyme activity. In contrast, $Ba^{++}$, $Hg^{++}$, $Pb^{++}$, $Ca^{++}$, $Mn^{++}$, $Cu^{++}$, $Fe^{+++}$, $Na^+$ and $K^+$ decreased it. The enzyme was inactivated by treatment with maleic anhydride, iodine and 2,4-dinitrophenol. The results indicate that active site is a imidazole group on the enzyme.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1283-1284
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• 2007

The barium strontium calcium titanate((Ba,Sr,Ca)$TiO_3$) powders prepared by the sol-gel method and $MnCO_3$ as acceptor were mixed oxide method. The microstructure was investigated with variation of $Pr_{2}O_{3}$ amount. The BSCT powder and $Pr_{2}O_{3}$ were mixed with organic vehicle(Ferro. B75001). BSCT thick films were fabricated by the screen-printing method on alumina substrates. The bottom electrode was Pt and upper electrode was Ag, respectively. All BSCT thick films were sintered at $1420^{\circ}C$, for 2h. The result of the differential thermal analysis(DTA), exothermic peak at around $654^{\circ}C$ due to the formation of the polycrystalline perovskite phase. In the X-ray diffraction(XRD) patterns, all BSCT thick films showed the typical perovskite polycrystalline structure and no pyrochlore phase was dbserved. The microstructure investigated by scanning electron microscope(SEM). Pore and grain size of BSCT thick films were decreased with increasing amount of $Pr_{2}O_{3}$ dopant. And the average grain size and thickness of BSCT thick films doped with 0.1 mol% $Pr_{2}O_{3}$ was $3.09{\mu}m$, $60{\mu}m$, respectively. The relative dielectric constant decreased and dielectric loss decreased with increasing amount of $Pr_{2}O_{3}$ dopant, the values of the BSCT thick films no doped with $Pr_{2}O_{3}$ were 7443 and 4 % at 1 kHz, respectively.

• Journal of Microbiology and Biotechnology
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• v.32 no.1
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• pp.99-109
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• 2022

This study is the first report on production and characterization of the enzyme from an Ornithinibacillus species. A 4.2-fold increase in the extracellular protease (called L9^T) production from Ornithinibacillus caprae L9^T was achieved through the one-factor-at-a-time approach and response surface methodological optimization. L9^T protease exhibited a unique protein band with a mass of 25.9 kDa upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This novel protease was active over a range of pH (4-13), temperatures (30-80℃) and salt concentrations (0-220 g/l), with the maximal activity observed at pH 7, 70℃ and 20 g/l NaCl. Proteolytic activity was upgraded in the presence of Ag⁺, Ca²⁺ and Sr²⁺, but was totally suppressed by 5 mM phenylmethylsulfonyl fluoride, which suggests that this enzyme belongs to the serine protease family. L9^T protease was resistant to certain common organic solvents and surfactants; particularly, 5 mM Tween 20 and Tween 80 improved the activity by 63 and 15%, respectively. More importantly, L9^T protease was found to be effective in dehairing of goatskins, cowhides and rabbit-skins without damaging the collagen fibers. These properties confirm the feasibility of L9^T protease in industrial applications, especially in leather processing.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.1-33
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• 1997

The objective of this study was to analyze the in vitro and in vivo corrosion products of low and high copper amalgams. The four different types of amalgam alloy used in this study were Fine cut, Caulk spherical, Dispersalloy, and Tytin. After each amalgam alloy and Hg were triturated according to the directions of the manufacturer by means of the mechanical amalgamator(Amalgam mixer. Shinhung Co. Korea), the triturated mass was inserted into a cylindrical metal mold which was 12mm in diameter and 10mm in height. The mass was condensed by 150Kg/cm compressive force. The specimen was removed from the mold and aged at room temperature for about seven days. The standard surface preparation was routinely carried out by emery paper polishing under running water. In vitro amalgam specimens were potentiostatically polarized ten times in a normal saline solution at $37^{\circ}C$(potentiostat : HA-301. Hukuto Denko Corp. Japan). Each specimen was subjected to anodic polarization scan within the potential range -1700mV to+400mV(SCE). After corrosion tests, anodic polarization curves and corrosion potentials were obtained. The amount of component elements dissolved from amalgams into solution was measured three times by ICP AES(Inductive Coupled Plasma Atomic Emission Spectrometry: Plasma 40. Perkim Elmer Co. U.S.A.). The four different types of amalgam were filled in occlusal and buccal class I cavities of four human 3rd molars. After about five years the restorations were carefully removed after tooth extraction to preserve the structural details including the deteriorated margins. The occlusal surface, amalgam-tooth interface and the fractured surface of in vivo amalgam corrosion products were analyzed. In vivo and in vitro amalgam specimens were examined and analyzed metallographically by SEM(Scanning Electron Microscope: JSM 840. Jeol Co. Japan) and EDAX(Energy Dispersive Micro X-ray Analyser: JSM 840. Jeol Co. Japan). 1. The following results are obtained from in vitro corrosion tests. 1) Corrosion potentials of all amalgams became more noble after ten times passing through the in vitro corrosion test compared to first time. 2) After times through the test, released Cu concentration in saline solution was almost equal but highest in Fine cut. Ag and Hg ion concentration was highest in Caulk spherical and Sn was highest in Dispersalloy. 3) Analyses of surface corrosion products in vitro reveal the following results. a)The corroded surface of Caulk spherical has Na-Sn-Cl containing clusters of $5{\mu}m$ needle-like crystals and oval shapes of Sn-Cl phase, polyhedral Sn oxide phase. b)In Fine cut, there appeared to be a large Sn containing phase, surrounded by many Cu-Sn phases of $1{\mu}m$ granular shapes. c)Dispersalloy was covered by a thick reticular layer which contained Zn-Cl phase. d)In Tytin, a very thin, corroded layer had formed with irregularly growing Sn-Cl phases that looked like a stack of plates. 2. The following results are obtained by an analysis of in vivo amalgam corrosion products. 1) Occlusal surfaces of all amalgams were covered by thick amorphous layers containing Ca-P elements which were abraded by occlusal force. 2) In tooth-amalgam interface, Ca-P containing products were examined in all amalgams but were most clearly seen in low copper amalgams. 3) Sn oxide appeared as a polyhedral shape in internal space in Caulk spherical and Fine cut. 4) Apical pyramidal shaped Sn oxide and curved plate-like Sn-Cl phases resulted in Dispersalloy. 5) In Tytin, Sn oxide and Sn hydroxide were not seen but polyhedral Ag-Hg phase crystal appeared in internal space which assumed a ${\beta}_l$ phase.

• The Korean Journal of Mycology
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• v.12 no.4
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• pp.133-140
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• 1984

Some properties of cellulolytic enzymes produced by Pleurotus sajor-caju JAFM 1017 during its growth in synthetic medium were investigated. The optimum pH of avicelase, CMCase, and ${\beta}-glucosidase$ was pH 5.5, pH 4.5 and pH 6.0, respectively. Avicelase and CMCase were stable within pH 5.0 to 6.0 and 4.0 to 6.0, respectively, and ,${\beta}-glucosidase$ was within pH 5.5 to 6.5. The optimum temperature of avicelase, CMCase and ${\beta}-glucosidase$ was the same of $40^{\circ}C$. The enzymes were stable below the optimum temperature, but the enzymes were unstable over the temperature of $50^{\circ}C$, and avicelase was losing about 91.7% of activity at $70^{\circ}C$ for 10 min. The enzyme activity of avicelase and CMCase was increased in proportion to the substrate concentration within 1% and 0.7%, respectively, and ${\beta}-glucosidase$ was within 0.1%. The Michaelis constants (Km) of avicelase and CMCase were 30.77mg avicel/ml and 14.64m Na-CMC/ml, respectively and ${\beta}-glucosidase$ was 5. 13mg salicin/ml. The reducing sugar production of avicelase was proportionaly increased until 120 min. and CMCase and ${\beta}-glucosidase$ were until 60min. The activity of three cellulolytic enzymes were increased by $Ca^{2+}$ at the concentration of $10^{-2}M$, but were inhibited by $Hg^{2+}$, $Ag^+$.

• Journal of Conservation Science
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• v.37 no.6
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• pp.723-737
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• 2021

This study analyzed the composition and structure of materials with Buddhist paper scriptures excavated from architectural sites in 'Sum Tolgoi' of the 17^th century and carried out conservation treatment base on the result of the analysis. The scriptures were covered in dust and foreign sub stances, and were so crumpled that it was impossible to identify the form. The damage, loss, and discoloration have been identified. Buddhist scriptures written in Tibetan used indigo and ink sticks on paper as a result of UV-Vis analysis, and ink sticks as black character materials from scriptures written ancient Mongolian. SEM-EDS and Micro-XRF analyses revealed that the outlines were drawn with red lines using a mix of Minium (Pb₃O₄) and Cinnabar (HgS), or Cinnabar (HgS) alone, and the contents of the scriptures were written with silver paint. Silver chloride (AgCl) and Calcium (Ca) were identified in the silver paint component of the characters, while Calcium and Orpiment (As₂S₃) were identified in the yellow lines. Concerning the paper ground, Buddhist scriptures written in ancient Mongolian were characterized by herbal plant fiber and bast fiber, and those written in Tibetan, by bast fiber. Radiocarbon dating indicates that the paper for the scriptures was produced between the 15^th and 17^th centuries. Conservation treatment of the scriptures was carried out based on the experiment on the production of pre-coated paper and how to coat that to prevent the second damage due to the deformation and fragility of the excavated paper. The scriptures were preserved and mounted, and a neutral box was made to identify the contents of the scriptures recorded on both sides after the treatment. This conservation treatment is the result of a study that applied new conservation treatment materials and methods according to the principle of conservation treatment reversibility.

• Economic and Environmental Geology
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• v.35 no.4
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• pp.325-337
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• 2002

We examined the contamination of stream water and stream sediments by heavy metal elements with respect to distance from the abandoned Backun Au-Ag-Cu mine. High contents of heavy metals (Pb, Zn, Cu, Cd, Mn, and Fe) and aluminum in the waters connected with mining and associated deposits (dumps, tailings) reduce water quality. In the mining area, Ca and SO$_4$ are predominant cation and anion. The mining water is Ca-SO$_4$ type and is enriched in heavy metals resulted from the weathering of sulfide minerals. This mine drainage water is weakly acid or neutral (pH; 6.5-7.1) because of neutralizing effect by other alkali and alkaline earth elements. The effluent from the mine adit is also weakly acid or neutral, and contains elevated concentrations of most elements due to reactions with ore and gangue minerals in the deposit. The concentration of ions in the Backun mining water is high in the mine adit drainage water and steeply decreased award to down stream. Buffering process can be reasonably considered as a partial natural control of pollution, since the ion concentration becomes lower and the pH value becomes neutralized. In order to evaluate mobility and bioavailability of metals, sequential extraction was used for stream sediments into five operationally defined groups: exchangeable, bound to carbonates, bound to FeMn oxide, bound to organic matter, and residual. The residual fraction was the most abundant pool for Cu(2l-92%), Zn(28-89%) and Pb(23-94%). Almost sediments are low concentrated with Cd(2.7-52.8 mg/kg) than any other elements. But Cd dominate with non stable fraction (68-97%). Upper stream sediments are contaminated with Pb, and down area sediments are enriched with Zn. It is indicate high mobility of Zn and Cd.

• Economic and Environmental Geology
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• v.40 no.6
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• pp.713-726
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• 2007

The Daebong deposit consists of gold-silver-bearing mesothermal massive quartz veins which fill fractures along fault zones($N10{\sim}20^{\circ}W,\;40{\sim}60^{\circ}SW$) within banded gneiss or granitic gneiss of Precambrian Gyeonggi massif. Ore mineralization of the deposit is composed of massive white quartz vein(stage I) which was formed in the same stage by multiple episodes of fracturing and healing and transparent quartz vein(stage II) which is separated by a major faulting event. The hydrothermal alteration of stage I is sericitization, chloritization, carbonitization, pyritization, silicification and argillization. Sericitic zone occurs near and at quartz vein and includes mainly sericite, quartz, and minor illite, carbonates and epidote. Chloritic zone occurs far from quartz vein and is composed of mainly chlorite, quartz and minor sericite, carbonates and epidote. Fe/(Fe+Mg) ratios of sericite and chlorite range 0.36 to 0.59($0.51{\pm}0.10$) and 0.66 to 0.73($0.70{\pm}0.02$), and belong to muscovite-petzite series and brunsvigite, respectively. Calculated $Al_{IV}-Fe/(Fe+Mg)$ diagrams of sericite and chlorite suggest that this can be a reliable indicator of alteration temperature in Au-Ag deposits. Calculated activities of chlorite end member are $a3(Fe_5Al_2Si_3O_{10}(OH){_6}=0.00964{\sim}0.0291,\;a2(Mg_5Al_2Si_3O_{10}(OH){_6}= 9.99E-07{\sim}1.87E-05,\;a1(Mg_6Si_4O_{10}(OH){_6}=5.61E-07{\sim}1.79E-05$. It suggest that chlorite from the Daebong deposit is iron-rich chlorite formed due to decreasing temperature from $T>450^{\circ}C$. Calculated $log\;{\alpha}K^+/{\alpha}H^+,\;log\;{\alpha}Na^+/{\alpha}H^+,\;log\;{\alpha}Ca^{2+}/{\alpha}^2H^+$ and pH values during wall-rock alteration are $4.6(400^{\circ}C),\;4.1(350^{\circ}C),\;4.0(400^{\circ}C),\;4.2(350^{\circ}C),\;1.8(400^{\circ}C),\;4.5(350^{\circ}C),\;5.4{\sim}6.5(400^{\circ}C)\;and\;5.1{\sim}5.5(350^{\circ}C)$, respectively. Gain elements (enrichment elements) during wallrock alteration are $K_2O,\;P_2O_5,\;Na2O$, Ba, Sr, Cr, Sc, V, Pb, Zn, Be, Ag, As, Ta and Sb. Elements(Sr, V, Pb, Zn, As, Sb) represent a potentially tools for exploration in mesothermal and epithermal gold-silver deposits.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.273-288
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• 2023

The Gubong Au-Ag deposit, which has been one of the largest deposits (Unsan, Daeyudong, Kwangyang) in Korea, consists of eight lens-shaped quartz veins (a mix of orogenic-type and intrusion-related types) that filled fractures along fault zones within Precambrian metasedimentary rock. Korea Mining Promotion Corporation found a quartz vein (referred to as the No. 6 vein with a grade of 27.9 g/t Au and a width of 0.9 m) at a depth of -728 ML by drilling (No. 90-12) conducted in 1989. Korea Mining Promotion Corporation conducted drilling (No. 04-1) in 2004 to investigate the redevelopment's possibility of the No. 6 vein. The author studied the occurrence and chemical composition of chlorite and white mica using wallrock, wallrock alteration and quartz vein samples collected from the No. 04-1 drilling core in 2004. The alteration of studied samples occurs chloritization, sericitization, silicification and pyritization. Chlorite and white mica from mineralized zone at a depth of -275 ML occur with quartz, K-feldspar, calcite, rutile and pyrite in wallrock alteration zone and quartz vein. Chlorite and white mica from ore vein (No. 6 vein) at a depth of -779 ML occur with quartz, calcite, apatite, zircon, rutile, ilmenite, pyrrhotite and pyrite in wallrock alteration zone and quartz vein. Chlorite from a depth of -779 ML has a higher content of Al and Mg elements and a lower content of Si and Fe elements than chlorite from a depth of -275 ML. Also, Chlorites from a depth of -275 ML and -779 ML have higher content of Si element than theoretical chlorite. Compositional variation in chlorite from a depth of -275 ML was mainly caused by phengitic or Tschermark substitution [Al^{3+,VI + Al3+,IV} <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], but compositional variation from a depth of -779 ML was mainly caused by octahedral Fe²⁺ <-> Mg²⁺ (Mn²⁺) substitution. The interlayer cation site occupancy (K+Na+Ca+Ba+Sr = 0.76~0.82 apfu, 0.72~0.91 apfu) of white mica from a depth of -275 ML and -779 ML have lower contents than theoretical dioctahedral micas, but octahedral site occupancy (Fe+Mg+Mn+Ti+Cr+V+Ni = 2.09~2.13 apfu, 2.06~2.14 apfu) have higher contents than theoretical dioctahedral micas. Compositional variation in white mica from a depth of -275 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV], illitic substitution and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution. But, compositional variation in white mica from a depth of -779 ML was caused by phengitic or Tschermark substitution [(Al³⁺)^VI + (Al³⁺)^IV <-> (Fe²⁺ or Mg²⁺)^VI + (Si⁴⁺)^IV] and direct (Fe³⁺)^VI <-> (Al³⁺)^VI substitution.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.1
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• pp.10-20
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• 1998

Heavy metal contamination in subsurface soils and stream sediments at the Suggok mine area were investigated on the basis of major, trace and rare earth elements geochemistry and mineralogy. The Sanggok mine area is mainly composed of Cambro-Ordovician carbonate rocks. The mine had been mined for Pb-Zn-Fe and Au- Ag, but already closed in past. For major elements, especially Fe (mean value=18.58 wt.%) and Mn (mean value=4. 18 wt.%) are enriched in soils, and the average enrichment indices of soils and sediments are 6.84 and 1.54, respectively. The average enrichment index of rare earth elements are 0.92 of mining drainage sediments and 0.52 of subsurface soils on the tailing dam. Concentrations of minor and/or environmental toxic elements in those samples range from 29 to 3400 for As,1 to 11 for Cd, 35 to 292 for Cu, 50 to 1827 for Pb, 1 to 22 for Sb and 112 to 2644 for Zn. Extremely high concentrations (mean values) are found in subsurface soils on the tailing dam (As=2278, Cd=7, Cu=206, Pb=1372, Sb=14 and Zn=2231 ppm, respectively). Average enrichment index normalized by composition of non-mining drainage sediments is 2.42 in mining drainage sediments and 25.47 in subsurface soils on the tailing dam. Based on EPA value, enrichment index of toxic elements is 0.53 in non-mining drainage sediments, 1.84 in mining drainage sediments and 23.71 in subsurface soils on the tailing dam. As a results from X-ray powder diffraction method, mineral composition of soils and sediments near the mine area varied in part, and are calcite, dolomite, magnesite, quartz, mica, chlorite and clay minerals. With the separation of heavy minerals, soils and sediments of highly concentrated toxic elements included some pyrite, arsenopyrite, sphalerite, galena, goethite and hydroxide minerals on the polished sections.