• Journal of the Mineralogical Society of Korea
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• v.24 no.2
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• pp.91-99
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• 2011

The turbidity in several wells of Samdong-myeon, Ulsan, exceeded potable groundwater standard (1 NTU). Mineralogical analysis showed that the fine suspended particles are ferrihydrite spheres with a size of less than $0.5\;{\mu}m$ and helical iron-oxidizing bacterial filaments, and their aggregates. Ferrihydrite was almost amorphous only showing two electron diffraction rings, and contained Si and P. Helical bacterial filaments were almost replaced by ferrihydrite. The helical bacteria have played an important role in the ferrihydrite formation by becoming the loci for ferrihydrite precipitation as well as oxidizing ferrous iron. The physicochemical conditions of low pH, low redox potential, high Ca concentration, and high alkalinity are consistent with the hydrogeochemical characteristics of carbonate groundwater, implicating that the inflow of deep ferriferous carbonate groundwater and its oxidation have caused the ferrihydrite turbidity in several wells of the study area.

• Korean Journal of Microbiology
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• v.35 no.1
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• pp.7-12
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• 1999

By SDS-polyacrylamide gel elcctrophoresis (SDS-PAGE) and immunoblot analysis that a protein with 66,000 daltons in size was recognized by P. aeruginosa anti-exotoxin A from P. sp. PY002. The yields of exotoxin A in P. sp. PY002 culture were influenced by the concentration of iron in the culture media. Increasing of the exotoxin A production and siderophore production was made slight increasing in the MKB medium. On the other hand, to clone the gene encoding the exoloxin A genomic library of P. sp. PY002 was constructed in pBluescript SK(+). From this library a exotoxin A homologous gene was isolated by immunological hybridization method using P. aemginosa anti-exoloxin A as a probe. Two putative clones were isolated and designated pETA23 and pETA42. Thc restriction analysis ol pETA42 demonstrated that thc 1760 bp insert contained one NcoI, PvuII, SstI, Kpnl and EcoRI site and three SmaI and HaeD sites.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.5
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• pp.590-603
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• 2006

Size-and time-resolved aerosol samples were collected using an eight-stage Davis rotating unit for monitoring (DRUM) sampler from 23 March to 29 April 2001 at Gosan, Jeju Island, Korea, which is one of the super sites of Asia-Pacific Regional Aerosol Characterization Experiment(ACE-Asia). These samples were analyzed using synchrotron X-ray fluorescence for 3-hr average concentrations of 19 elements including Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Rb, and Pb. The size-resolved data sets were then analyzed using the positive matrix factorization(PMF) technique to identify possible sources and estimate their contributions to particulate matter mass. PMF analysis uses the uncertainty of the measured data to provide an optimal weighting. Twelve sources were resolved in eight size ranges($0.09{\sim}12{\mu}m$) and included continental soil, local soil, sea salt, biomass/biofuel burning, coal combustion, oil combustion, municipal incineration, nonferrous metal source, ferrous metal source, gasoline vehicle, diesel vehicle, and volcanic emission. The PMF result of size-resolved source contributions showed that natural sources represented by local soil, sea salt, continental soil, and volcanic emission contributed about 79% to the predicted primary particulate matter(PM) mass in the coarse size range ($1.15{\sim}12{\mu}m$) while anthropogenic sources such as coal combustion and biomass/biofuel burning contributed about 58% in the fine size range($0.56{\sim}2.5{\mu}m$). The diesel vehicle source contributed mostly in ultra-fine size range($0.09{\sim}0.56{\mu}m$) and was responsible for about 56% of the primary PM mass.

• Economic and Environmental Geology
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• v.11 no.3
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• pp.89-98
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• 1978

Mineralogy, beneficiation, and processes of titanium ores are reviewed from petrographic viewpoints. The most important titanium minerals are ilmenite ($FeTiO_3$) and rutile ($TiO_2$). Ilmenite will play major role :for raw material, because rutile are rapidly diminishing. Thus, there is a need to develope a successful process for producing high grade Ti02 from ilmenite. Commercial, as well as R and D processes to treat more abundant ilmenite ores fall in three general classess: 1. Iron in ilmenite is partially or completely reduced and separated either physically or chemically. 2. Iron is reduced to ferrous state and chemically leached away from the titanium. 3. Ore is treated to make chlorides either selectively or with subsequent separation and purification of $TiC_4$. Routes and efficiencies of these process technologies are primarily influenced by the particular ore deposit to be mined and secondly by environmental considerations. One deposit parameters which influence ilmenite process technologies are: 1. Complexity of microtextures of ilmenite intergrown with Fe-oxide minerals. 2. Composition of concentrates; ilmenites contain minor amounts of substituted Mg, Mn, and V. These elements plus iron and gangue minerals can cause difficulties to complete reactions, substantial acid consumption, difficulties of removing waste solids, and waste disposal problems. Major contributions to be made by petrologists for process optimization are: characterization and interpretation of compositional and physical changes of raw materials and solids derived from process streams. These informations can play significant role in selecting and improving process steps for titania production.

• Economic and Environmental Geology
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• v.47 no.1
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• pp.61-69
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• 2014

As we are trying to in-situ treat (purify or immobilize) heavy metals or radionuclides in groundwater, one of the geochemical factors to be necessarily considered is the value of oxidation/reduction potential (ORP) of the groundwater. A biogeochemical impact on the characteristic ORP change of groundwater taken from the KAERI underground was observed as a function of time by adding electron-donor (lactate), electron-acceptor (sulfate), and indigenous bacteria in a laboratory condition. There was a slight increase of Eh (slow oxidation) of the pure groundwater with time under a $N_2$-filled glove-box. However, most of groundwaters that contained lactate, sulfate or bacteria showed Eh decrease (reduction) characteristics. In particular, when 'Baculatum', a local indigenous sulfate-reducing bacterium, was injected into the KAERI groundwater, it turned to become a highly-reduced one having a decreased Eh to around -500 mV. Although the sulfate-reducing bacterium thus has much greater ability to reduce groundwater than other metal-reducing bacteria, it surely necessitated some dissolved ferrous-sulfate and finally generated sulfide minerals (e.g., mackinawite), which made a prediction for subsequent reactions difficult. As a result, the ORP of groundwater was largely affected even by a slight injection of nutrient without bacteria, indicating that oxidation state, solubility and sorption characteristics of dissolved contaminants, which are affected by the ORP, could be changed and controlled through in-situ biostimulation method.

• Journal of Life Science
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• v.23 no.1
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• pp.31-37
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• 2013

The present study aimed to investigate effects of ethanol extracts from Hydropsyche kozhantschikovi on cell and DNA damage caused by oxidative stress. In a radical scavenging assay, compared with ascorbic acid used as a control, the level of DPPH (1,1-diphenyl-2-picrylhydrazyl) and that of hydroxyl radicals in H. kozhantschikovi extracts were 60.0% and 43.7%, respectively. The ferrous iron chelating level was 37.5% compared to the chelating value of EDTA (ethylenediaminetetraacetic acid) as a positive control at the same concentration. To verify inhibitory effects of oxidative cell damage induced by reactive oxygen species (ROS), the relative level of lipid peroxidation and the expression level of the p21 protein were compared in extracts-treated and untreated groups. Lipid peroxidation was completely inhibited in the extracts-treated group compared with the radical-only treated group. The level of p21 protein expression was restored to 92.2% of p21 protein expression in the control sample. In addition, DNA cleavage inhibition in the H. kozhantschikovi extracts was 74.1% compared with that of the control group, suggesting that H. kozhantschikovi extracts repress DNA cleavage induced by ROS. Moreover, the phosphorylation ratio of the H2AX protein was 16.7% in the radical-treated group, indicating that the ethanol extracts inhibited 83.3% of DNA damage. Our findings suggest that ethanol extracts from H. kozhantschikovi are effective not only in repressing the oxidation of free radicals and highly toxic hydroxyl radicals, but also in decreasing cell and DNA damage caused by oxidative stress.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.527-534
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• 1999

This study was carried out to investigate the effects of pine needle extracts on lipid oxidation and free radical reaction in iron sources reacted with active oxygen species. The results were summarized as follow; the catalytic effects of active oxygen on lipid oxidation in oil emulsion tended to be showed $OH,\;H_2O_2\;and\;KO_2$ in order. At the same time, pine needle extracts itself were tended to be showed a little catalytic effects. Active oxygen scavenging ability of pine needle extracts didn't show, but pine needle extracts played role as a strong chelating agents to bind iron ion if $Fe^{2+}$ ion exist in oil emulsion. The content of $Fe^{2+}$ ion and total iron in CPNP were higher than those of HPNP and FPN. The content of ascorbic acid of FPN showed the highest (87.77 ppm) among several pine needle extracts. Electron donating ability of HPNP and CPNP were 81% and 78%, respectively, which were showed higher content than those of FPN. The SOD-like activity of HPNP showed 44.30%, compared to other pine needle extracts which means the most strong antioxidant reaction. The nitrite scavenging effects were tended to be different, depending on pH value as pH value was increased. Especially, they didn't show the nitrite scavenging effect in pH6.0.

• Journal of the Korean Magnetics Society
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• v.17 no.1
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• pp.34-37
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• 2007

The crystallographic and magnetic properties of $Fe_{0.9}Zn_{0.1}Cr_2S_4$ have been studied by X-ray diffractometer(XRD), vibrating sample magnetometer(VSM) and $M\"{o}ssbauer$ spectroscopy measurement. The crystal structure was determined by the normal cubic spinel of space group Fd3m and the lattice constant was $a_0=9.9967\;{\AA}$. The specific phenomenon which looks like cusp pattern at 77 K was observed in magnetization corves(ZFC : Zero Field Cooling) under 100 Oe applied field. $N\acute{e}el$ temperature($T_N$) was determined to be 153 K by VSM and $M\"{o}ssbauer$ spectra. The asymmetric 8-line profile has been observed at 4.2 K, which was attributed by the colossal electric quadupole interaction(${\Delta}E_Q$), ${\Delta}E_Q$ has 2.22 mm/s at 4.2 K. The ${\Delta}E_Q$ abruptly decreases around 77 K and then it disappears above 77 K with diminishing of 8-line pattern. The isomer shift $\delta$ at room temperature is 0.48 mm/s relative to Fe metal, which means that the charge state of Fe ions is ferrous in character.

• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.155-161
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• 2009

The most upcoming technical issue of automotive coating is the compact coating process. Pre-primed coating is the outstanding technology eliminating electro-deposition and primer coating process. The main properties of pre-primed coating for automotive are flexibility, corrosion resistance, and weldability. Therefore, we synthesized the conventional polyester, elastomeric polyester and polyvinylidene fluoride resins and evaluated their properties to use as weldable pre-primed automotive coatings. As the results of flexibility and curing behavior, the elastomeric polyester coating was most appropriate to use for the pre-primed automotive coatings.

• Food Science and Preservation
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• v.24 no.5
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• pp.631-637
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• 2017

The physiological properties of extracts from Hizikia fusiforme with different extraction methods (hot water extraction, autoclave extraction and high pressure extraction) were investigated. The amounts of substances related to polyphenol and flavonoids contents were the highest in autoclave extract (30.51 mg/g and 4.78 mg/g, respectively). The DPPH radical scavenging activity was the highest in the autoclave extract (81.80%) at the 5 mg/mL. Autoclave extract exhibited the strongest ABTS radical scavenging activity and reducing power among the three extraction methods. However, ferrous ion chelating, TBA reactive substances and xanthine oxidase inhibition activity of high pressure extract were higher than those of the other extracts. Additionally, the tyrosinase and elastase inhibition activities of high pressure extract with a concentration of 1 mg/mL were higher than those of the other extracts. These results suggest that extracts of Hizikia fusiforme have a potential to act as functional materials, and autoclave and high pressure extractions are superior to hot water extraction for enhancement of the biological activity.