• Applied Biological Chemistry
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• v.20 no.1
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• pp.33-42
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• 1977

Asparagine biosynthesis by soybean sprouts grown under the dark conditions has been demonstrated. The amount of free asparagine synthesized in ten day-old soybean sprouts increases to 22.7% on the dry weight base. The effects of nitrogen compounds such as $NH_4Cl,\;(NH_4)_2SO_4$ and urea on asparagine synthesis during the sprouting were examined and the results showed that urea was more effective than other two compounds. Glutamine-dependent asparagine synthetase was partially purified (8.6 folds) through ammonium sulfate fractionation, followed by Sephadex G-150 gel filtration. The enzyme was very labile and required protection by thiol groups or high level of glycerol. The mixture of ATP and $Mg^{++}$ ion also stabilized the enzyme activity. The enzyme utilized glutamine more effectively than ${NH_4}^+$ as an amide donor for the formation of asparagine. The enzyme required L-aspartate (Km=3.1 mM), L-glutamine, ATP and $Mg^{++}$. It showed pH optimum of 7.5 and catalyzed the formation of ${\beta}-aspartyl$ hydroxamate in the presence of L-aspartate, ATP, $Mg^{++}$ and $NH_2OH$ in the reaction mixture.

• Journal of Surface Science and Engineering
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• v.31 no.6
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• pp.334-344
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• 1998

Yew coating pmccss t.o form a surface layer ol CrN phasc on mild steel (A81 1020!, AlSI Hi3, 1Cr-0.5Mo steel (ASTM A213 and Nickrl-base superalloy (Inconel 718) was developed. Surlaces of various alloys t,n.ateii by chromizing for the formation ol Cr diffusion layer was subsequently trcaled by plasma nitriding in order t.o form the hard CrS coating layer on the surfaces. This duplex plasma surface tri-atments of chromizing and plasma nitriding have induced a lormation of a duplex-lrcated surfacr hyer of approximat~ls 70-80 $\mu\textrm{m}$thickncss with a iargcly improved microiiardnrss up to approxiniateW 1500Hv(50gf). The main cause for the lage improvment in the surface hardncss is altribilted to [.he fact that CrN and $Fe_xN$ phases are created successfully by ccliromizins and plasma nilriding treatment. High tenipera1,urc wear resislance of the duplex-treated mild steel and HI3 steels at $600^{\circ}C$ was examined. Comparing the duplex-treated specimens with the specimens treated only by chromizing, the rcsults shovmi that, thc wear volume of the duplex-treated mild skcl and 1113 stcel aSt.er a wear test, at $600^{\circ}C$ were reduced hy a Iactor of 8 and 3, respectively. Characteristics of the CrS phase by duplrx treatment were compared with $CrN_x$,/TEX> film by ion plating and the wear behaviors of CrN film lormed by two different nroccsses arc nea.riy identical.

• Journal of the Korean Ceramic Society
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• v.16 no.1
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• pp.3-12
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• 1979

The effects of sintering temperature and sintering atmosphere on magnetic properties and microstructuresof Mn-Zn ferrites have been studied. Mixture of 52.8mole% $Fe_2O_3$, 26.4mole% MnO, 15.1mole0% ZnO and 5.7mole% NiO was prepared, and 0.1mole% CaO, 0.02mole% $SiO_2$ were added as minor additives. After calcining and ball milling the powder was granulated for compacting. The specimens were sintered at $1, 250^{\circ}$, $1, 300^{\circ}$and 1, 35$0^{\circ}C$ in the various atmosphere of $N_2$, $N^_2\DIV0.6% O_2$, $N_2＋2.7% O_2$, $N_2＋4.1% O_2$, $N^2＋8.2% O_2$ and air for 3 hours and cooled in $N_2$ atmosphere. The grian growth rate and densities increase as sintering temperature and oxygen content of atmosphere increase. At the sintering temperature of $1, 250^{\circ}C$ the initial permeabilities increase as oxygen content of atmosphere increase. At the sintering temperature of$ 1, 300^{\circ}$and $1, 350^{\circ}$ the initial permeabilities show maximum values at $N_2＋4.1% O_2$ atmosphere. The secondary peaks of initial permeabilities are observed between 100$^{\circ}$and 20$0^{\circ}C$, and the positions of secondary peaks move to higher temperature as oxygen content of atmosphere increases. Q-factors decrease as sintering temperature increases and oxygen content of atmosphere decreases.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.3
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• pp.294-305
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• 2012

The objective of this study is to estimate the chemical compositions and to identify qualitative sources of fall-out particles in study area. Also, this study used a spatial analysis to estimate spatial distributions and average deposition flux. In this study, the chemical compositions of fall-out particle samples collected at Muncheon lake from May 2010 to January 2011 were analyzed by ICP and IC. The monthly trend of deposition fluxes for fall-out particles showed highest in June ($107.61kg/km^2/day$) and lowest in October ($22.22kg/km^2/day$). The average fluxes of Fe, Si, Al, Zn and Ba are 0.44, 0.24, 0.20, 0.17, $0.09kg/km^2/day$, respectively. Also, the average fluxes of $NO_3^-$, $SO_4^{2-}$, $NH_4^+$, $Ca^{2+}$, and $Na^+$ are 6.48, 5.01, 4.96, 1.75, $1.37kg/km^2/day$, respectively. A Factor analysis identified four sources such as 1) nonferrous metal, motor vehicle, and agriculture, 2) soil, 3) field burning, incineration, and 4) road dust and oil burning. The IDW (inverse distance weighting) spatial analysis method was used to estimate spatial distribution and average deposition flux for fall-out particles. A total average deposition fluxes estimated in Muncheon lake were 936.15 kg/month. The spatial distribution trend of deposition flux showed higher at site 1 and 2 than at site 3, 4 because local road is adjacent to the site 1 and 2.

• Economic and Environmental Geology
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• v.23 no.1
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• pp.35-57
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• 1990

This study has been carried out on the Pegmatites, Naedeogri Granites, Nonggeori Granites and Metasedimentary rocks in the middle area of Taebaeksan region to investigate the geochemical properties and possibility of productivity. Pegmatites are characterized by metamorphosed anatectic pegmatite and differentiated magmatic pegmatite, and are mixed type of rare-element pegmatite and mica-bearing pegmatite by the classification of Ginsburg(1979). The petrological type of the igneous rocks is thought to be calcalkali, subalkaline and peralumious. According to chemical variations against D. I., differentiation trends from Naedeogri and Nonggeori Granites through non-mineralized pegmatites to mineralized pegmatites are supposed. From the relationship between oxided and $SiO_2$, pegmatites and Nonggeori Granite have shown similar tendencies and bulk composition of pegmatites and similar to metasedimentary rocks near the intrusives. By judging the correlations of trace elements, it is elucidated that pegmatites adjacent to Naedeogri and Nonggeori Granites have been originated in magma differentiation from these granites and the others have been differentiated by remelting or partial melting from metasedimentary rocks. $Sp_5$, $Sp_8$, and $Sp_9$ pegmatites are considered as productive rocks, and $Sp_4$, $Sp_6$, $Sp_7$, $Sp_{10}$, $Sp_{11}$, and $Sp_{12}$ pegmatites and granites are supposed to have a weak productivity, in terms of element ratios related with Sn mineralizations. Tourmalines in productive pegmatites are formed under the circumstance of Li-poor granitoids and associated with pegmatites, and the others are seemed to be originated in metapelites and metapsammites which are not coexisting with an Al-saturating phase. Three types of chemical zoning are noticed in tourmalines: (1) apparently homogeneous compositional patterns, (2) a continuous core-to-rim zoning and, (3) a discontinuous core-to-rim zoning. From results of EPMA of tourmalines, Al, Mg and Ca increase closer to rim, while Fe decreases.

• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.415-421
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• 2003

A bacterium, Pseudomonas fluorescens 2112, that is antagonistic against a red-pepper blight-causing fungus, Phytophthora capsici, was isolated from the local soil of Gyongju, Korea. This strain formed an orange-colored clear halo zone on chrome azurol S (CAS) blue agar, suggesting the production of a siderophore in addition to an antifungal antibiotic. The optimal culture conditions for siderophore production by P. fluorescens 2112 were 30-h cultivation at $25^{\circ}C$ and pH 6.5 in King's B medium. The presence of $20{\mu}g/ml\;of\;Fe^3+$ ion or EDDHA promoted the production of siderophore in King's B medium. The siderophore was purified from culture broth by CM-Sephadex C-25 and Sephadex G-25 column chromatographies. The UV spectra of the purified siderophore was the same as that of pyoverdins or pseudobactins. The molecular mass was 1,958 Da determined by FAB-rlass spectrometer, and the amino acid composition analysis showed that the purified siderophore consisted of glycine/threonine/serine/glutamic acid/alanine/lysine with the molar ratio of 3:2:1:1:1:1, DL-Threo-${\beta}$-hydroxyaspartic acid and $N^{\delta}$-hydroxyornithine, two of the essential constituents of pyoverdin, were also found. The purified siderophore pyoverdin showed strong in vitro and in vivo antagonistic activities against phytophthora blight-causing P. capsici. Especially in an in vivo pot test, the siderophore protected red-pepper Capsicum annum L. very well from the attack of P. capsici. These results indicated that the purified siderophore of P. fluorescens 2112 played a critical role in the biocontrol of the red-pepper blight disease, equivalent to treatment by P.fluorescens 2112 cells.

• Economic and Environmental Geology
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• v.20 no.3
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• pp.169-177
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• 1987

The Manjang copper magnetite-fluorite orebodies are imbedded within the limestone beds of the Hwajonri Formation. The ore deposits are characterized by magnetite-fluorite bearing skarn orebody in the west orebody and copper sulfide veins of the central and main orebodies. This study includes fluid inclusion geothermometry, salinity analysis, stable isotope analysis, and application of phase rule to mineral associations in skarn ore. Ore minerals are closely associated with the skarn silicates such as garnet, wollastonite and epidote. Magnetite and fluorite are remarkable in the west orebody whereas chalcopyrite is dominate in the central and main orebodies where pyrite and pyrrhotite also appear as sulfide gangues. Homogenization temperature and salinity of fluid inclusions are measured ranging between $240^{\circ}C$ and $350^{\circ}C$, 6.3~12.9 wt. percent in quartz and $220^{\circ}C$ and $350^{\circ}C$, 8.5~9.9wt. percent in fluorite, respectively. This indicates that the filling temperature and salinity are higher in quartz than in fluorite with the tendency of both to be linearly decreased suggesting an attribution of meteoric water to the mineralization. $T-fo_2$ diagram in the Ca-Fe-Si system at 1 kb and $Xco_2$=0.02 shows that the mineral assemblages with decreasing temperature are andradite-hedenbergite-calcite, hedenbergite-andradite-quartz, magnetite-andradite-quartz, and magnetite-quartz-calcite, indicating that magnetite crystallizes mostly late skarn stage at lower temperature. According to the carbon and oxygen isotopic values of the host limestone and calcite in ores, the sourec of carbon might be mixture of host limestone and deep seated carbons. Sulfur isotope data imply that ore fluids be relatively homogeneous in sulfur isotopic composition, mainly derived from igneous source.

• The Journal of the Petrological Society of Korea
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• v.18 no.1
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• pp.31-47
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• 2009

We performed petrological, geochemical, and geochronological study for the Pyeonghae granite gneiss and the Hada leuco-granite gneiss intruding the Paleoproterozoic meta-sedimentary rocks (pyeonghae formation and Wonnam formation) of the Pyeonghae area located in northeastem part of the Yeongnam (Sobaeksan) massif. The Pyeonghae granite gneiss generally has higher abundance of mafic minerals (biotite etc.), and posesses higher ${Fe_2}{O_3}^t$, MgO, CaO, $TiO_2$, $P_{2}O_{5}$ contents but lower $SiO_2$ and $K_{2}O$ contents than the Hada leuco-granite gneiss which tends to have slightly high $Al_{2}O_{3}$ and $Na_{2}O$ contents and slightly high larger negative Eu anomalies. However both gneisses reveal very similar REE concentrations and chondrite-normalized patterns and apparently show differentiation trend affected by crystallization of biotite, plagioclase, apatite and sphene. Their peraluminous and calc-alkaline chemistry suggests tectonic environment of volcanic arc. SHRIMP Zircon U-Pb age determinations yield upper intercept ages of $1990{\pm}23\;Ma$ ($2{\sigma}$) and $1939{\pm}41\;Ma$ ($2{\sigma}$), and weighted mean $^{207}Pb/^{206}Pb$ ages of $1982{\pm}6.3\;Ma$ ($2{\sigma}$) and $1959{\pm}28\;Ma$ ($2{\sigma}$) for the Pyeonghae granite gneiss and the Hada leuco-granite gneiss respectively, showing overlapping ages within the error. Our study suggests that the Precambrian granitoids in this area intruded contemporaneously with the Buncheon granite gneissin volcanic arc environment.

• Korean Journal of Heritage: History & Science
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• v.50 no.1
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• pp.4-17
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• 2017

In this research, the chemical composition of the iron artifacts from the late 6th-century to early 7thcentury Baekje remains in Gwanbuk-ri, Buyeo, specifically of the nine iron artifacts including slags, furnace walls and ingot iron excavated in the District "Na", were examined by observing their chemical compounds and microstructures. As a result, GB1 and GB6 were determined to be proto-reduction lumps whereas GB2, GB3, GB4 and GB5 were determined to be tempered slags, respectively. Also, he furnace wall GB7 were containing mullite and cristobalite, which are high temperature index minerals, The extrusion temperature was found out to be about $1200{\sim}1300^{\circ}C$, and it is most likely that the smelting temperature in the furnace was in that temperature range. GB8 ingot iron was determined to be a forged ironware. This ingot iron was an intermediary product for making ironware and its nonmetallic inclusions displayed similar microstructure and contents compared to the forged iron. Because of the existence of proto-reduction lumps and forged iron, the iron making facility located in District "Na" most likely had a small-scale iron making facility that handled iron bloom smelting and refining processes.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.3
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• pp.287-294
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• 2015

In this study, we investigated the antioxidative effects of brown seaweed Ecklonia cava extract and its subfractions. All experiments were performed with 50% ethanol extract, ethyl acetate fraction and aglycone fraction of E. cava. The free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activities ($FSC_{50}$) of ethyl acetate fraction ($FSC_{50}=6.98{\mu}g/mL$) and aglycone fraction ($7.03{\mu}g/mL$) are similar to that of (+)-${\alpha}$-tocopherol ($8.98{\mu}g/mL$) which is a reference control. Reactive oxygen species (ROS) scavenging activity (total antioxidant capacity, $OSC_{50}$) of the aglycone fraction ($OSC_{50}=14.48{\mu}g/mL$) on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system using the luminol-dependent chemiluminescence assay was the strongest among all extract and fractions. However, all samples showed lower antioxidant activities than that of L-ascorbic acid ($6.88{\mu}g/mL$) known as a powerful antioxidant. The protective effect of 50% ethanol extract on the $^1O_2$-induced cellular damage of human erythrocytes was dependent on the concentration from 5 to $50{\mu}g/mL$. Both ethyl acetate fraction and aglycone fraction showed strong cellular protective activities at $10{\mu}g/mL$, where the cellular protective effects (${\tau}_{50}$) of each fraction were recorded 442.0 min and 539.9 min, respectively. Three kinds of extract/fractions of E. cava showed much greater cellular protective activities at $10{\mu}g/mL$ than that of liposoluble antioxidant (+)-${\alpha}$-tocopherol (40.6 min) which is a reference control. These results suggest E. cava extracts and its fractions can be applied as an antioxidant ingredient in a field of cosmetics.