• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.24-25
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• 2001

Persistent cellular oxidative stress and enhanced lipid peroxidation (LPO) of PUFAs, leading to macromolecular damage and disruption of signaling pathways, are implicated in the development of human malignancies and other chronic degenerative diseases. LPO generates by oxidation of linoleic acid (LA) or arachidonic acid ($\omega$ -6 PUPAs) reactive aldehydes, such as trans-4-hydroxy-2-nonenal, which form etheno $\varepsilon$ -DNA adducts in a variety of human tissues and thus can contribute to diet-related cancers.(omitted)

• Environmental Analysis Health and Toxicology
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• v.18 no.3
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• pp.165-174
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• 2003

Cr (Ⅵ) - containing compounds are well-established carcinogens, although the mechanism for chromium - induced carcinogenesis is still not well understood. The reduction of Cr (Ⅵ) to its lower oxidation states, par ticularly Cr (V) and Cr (IV), is an important step for the production of chromium-mediated reactive oxygen species (ROS). The persistent oxidative stress during the reduction process may play a key role in the mechanism of Cr (Ⅵ) -induced carcinogenesis. This paper summarizes recent studies on (1) the reduction of Cr (Ⅵ) to Cr (III) occur by a multiplicity of mechanisms depending on the nature of reducing agents including ascorbate, diol-and thiol-containing molecules, certain flavoenzymes, cell organelles, intact cells, and whole animals; (2) free-radical production with emphasis on hydroxy radical generation via Fenton or Haber-Weiss type reactions; and (3) free radical - induced cellular damage, such at DNA strand breaks, hydroxylation of 2'-deoxyguanosine, and activation of nuclear transcription factor kB.

• Nuclear Engineering and Technology
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• v.50 no.2
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• pp.306-312
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• 2018

There is an increasing need in the United States and around the world to move used nuclear fuel from wet storage in fuel pools to dry storage in casks stored at independent spent fuel storage installations or interim storage sites. Under normal conditions, the Nuclear Regulatory Commission limits cladding temperature to $400^{\circ}C$ for high-burnup (>45 GWd/mtU) fuel, with higher temperatures allowed for low-burnup fuel. An analysis was conducted with FRAPCON-4.0 on three modern fuel designs with three representative used nuclear fuel storage temperature profiles that peaked at $400^{\circ}C$. Results were representative of the majority of US light water reactor fuel. They conservatively showed that hoop stress remains below 90 MPa at the licensing temperature limit. Results also show that the limiting case for hoop stress may not be at the highest rod internal pressure in all cases but will be related to the axial temperature and oxidation profiles of the rods at the end of life and in storage.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.287.1-287.1
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• 2003

F$_2$-isoprostanes are derived in vivo principally from the formation of positional peroxyl radicals of arachidonic acid, endocyclization to prostaglandin G$_2$-like structures, and reduction to PGF$_2$-like compounds. F$_2$-isoprostanes have been proposed as biomarkers of lipid peroxidation, oxidative stress status, and oxidation of low density lipoprotein (LDL) in atherogenesis. Especially, elevated 8-iso-PGF$\sub$2a/ is known as a useful clinical biomarker of oxidative stress in-end stage renal disease (ESRD) patients receiving hemodialysis (HD). (omitted)

• Korean Journal of Materials Research
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• v.8 no.6
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• pp.538-544
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• 1998

The spallation of a thermal barrier coating layer depends on the formation of brittle spinels. thermal expansion mismatch between ceramic and metal. the phase transformation of a ceramic layer and residual stress of coating layer. In this work. the formation mechanism of oxide scale formed by oxidation treatment at 90$0^{\circ}C$ was investigated in order to verify oxidation behavior at the interface between E-beam coated $Zr0_2$-7wt.% $Y_20_3$ and plasma sprayed CoNiCrAIY. Some elements distributed in the bond coating layer were selectively oxidized after oxidation. At the initial time of oxidation. AI-depletion zone and $\alpha$-$Al_O_3$,O, were formed at the bond coating layer by the AI-outward diffusion. After layer grew until critical thickness. spinels. $Cr_20$, and $C0_2CrO_4$ by outward diffusion of Co. Cr, Ni were formed. It was found that the formation of spinels may be related to the spallation of $Zr0_2$-7wt.% $Y_20_3$ during isothermal oxidation.

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.101-107
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• 2010

Metal ions are essential to life. However, some metals such as mercury are harmful, even when present at trace amounts. Toxicity of mercury arises mainly from its oxidizing properties. Ionizing radiation (IR) is an active tool for destruction of cancer cells and diagnosis of diseases, etc. IR induces DNA double strand breaks in the nucleus, In addition, it causes lipid peroxidation, ceramide generation, and protein oxidation in the membrane, cytoplasm and nucleus. Yeasts have been a commonly used material in biological research. In yeasts, the physiological response to changing environmental conditions is controlled by the cell types. Growth rate, mutation and environmental conditions affect cell size and shape distributions. In this work, the effect of IR and mercury chloride (II) on the morphology of yeast cells were investigated. Saccharomyces cerevisiae cells were treated with IR, mercury chloride (II) and IR combined with mercury chloride (II). Non-treated cells were used as a control group. Morphological changes were observed by a scanning electron microscope (SEM). The half-lethal condition from the previous experimental results was used to the IR combined with mercury. Yeast cells were exposed to 400 and 800 Gy at dose rates of 400Gy $hr^{-1}$ or 800 Gy $hr^{-1}$, respectively. Yeast cells were treated with 0.05 to 0.15 mM mercury chloride (II). Oxidative stress can damage cellular membranes through a lipidic peroxidation. This effect was detected in this work, after treatment of IR and mercury chloride (II). The cell morphology was modified more at high doses of IR and high concentrations of mercury chloride(II). IR and mercury chloride (II) were of the oxidative stress. Cell morphology was modified differently according to the way of oxidative stress treatment. Moreover, morphological changes in the cell membrane were more observable in the frequently stress treated cells than the temporarily stress treated cells.

• Herbal Formula Science
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• v.17 no.2
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• pp.163-174
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• 2009

Reactive oxygen species(ROS) can induce hepatotoxicity and trigger apoptosis in the liver. In this study, we investigated the sulfated polysaccharide A-1 from Opuntia ficus-indica against alcoholic oxidative stress in human liver Hep G2 cell. An antioxidant substance A-1 obtained from the enzymatic extract of Opuntia ficus-indica fruit was purified by DEAE-cellulose ion exchange and sephadex G-100 gel permeation chromatography. The purification yield and molecular weight were 14.3% and 1.8 KDa, respectively. The A-1 predominately contained arabinose, galactose, rhamnose and also sulfate group. The structure of A-1 was investigated by periodate oxidation, FT-IR spectroscopy, $^1H$-NMR spectroscopy. The A-1 mainly composed of alternating unit of ${\rightarrow}4$)-$\alpha$-L- Rapp-2-$SO_3^-$-$\alpha$-L-Galp-($1{\rightarrow}$ and branched linkage of $\beta$-D-Arbp- ($5{\rightarrow}$. The antioxidative activity was measured using the SOD, CAT activity and GSH assay, respectively. The expression of Nrf2 protein was analyzed by western blotting. The viable cell count analyzed by autofluorescence. Oxidative stress induced by ethanol(1 M) were dramatically reduced by A-1 treatment. A-1 also prevented cell death induced by oxidative stress. It also increased expression Nrf2 protein level. We concluded that sulfated polysaccharide A-1 from Opuntia ficus-indica effectively protect Hep G2 liver cell from alcoholic oxidative stress.

• Journal of Oral Medicine and Pain
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• v.22 no.1
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• pp.65-80
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• 1997

Cytochrome P450 is an oxidase involved in oxidation of alcohol and is known to be an activator of carcinogen. The present study was perfomed to analyze the effect of diabetes and cold stress on the expression of Cytochrome P450 IIE1(CYPIIE1) in the liver and salivary glands in rats by an immunoblot analysis. Sixty three divided into 4 groups; 1) 20 rats belonging to group I were allowed diabetes (40mg/kg. I.V.) 2) 20 rats of group II were bathed in cold water for 30 seconds twice a day 3) 20 rats comprising group III were received diabetes and cold stress as described above 4) 3 rats of group IV were selected as a control. The rats were sacrificed at the end of the same day 1, 2, 3, 4 weeks experiment. The liver and parotid glands were removed and stored at $-70^{\circ}C$ until use. The stored organs were homogenized for 10 seconds and the supernatants were obtained by centrifugation. The proteins of the supernatants were separated by sodium dodecyl sulfate- polyacrylamide gel electrophoresis and subjected to Western blotting. The blotted membranes were incubated with polyclonal antibodies to CYPIIE1. And sepimens were observed with light microscope also under the Hematoxillin-Eosin staining. The obtained results were as follows : 1. In diabetes group, acini had changed to degeneration severely 1 week experiment, but repaired gradually in lapse of time. 2. In diabetes group, septal connective tissue had changed to degeneration little by little from 1 week after experiment, and progressed severely in lapse of time. 3. In stress group, acini had not changed remarkably, but slightly separated each other 3 weeks after experiment. 4. In diabetes and stress group, histological feature had changed remarkably campare with in the group of diabetes only. 5. In all experimental group, CTPIIE1 had expressed remarkably in the liver tissue, but not in the parotid gland tissues. 6. In diabetes and stress group, CYPIIE1 had expressed remarkably campare with in the group of diabetes only.

• Corrosion Science and Technology
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• v.17 no.3
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• pp.101-108
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• 2018

AA7010 is an Al-Zn-Mg-Cu alloy containing Zr, developed as an alternate to traditional AA7075 alloy owing to their high strength combined with better fracture toughness. It is necessary to improve the corrosion resistance and surface properties of the alloy by incorporating plasma electrolytic oxidation (PEO) method. AA7010-T7452 aluminum alloy has been processed through the forging route with multi-stage working operations, and was coated with $10{\mu}m$ thick $Al_2O_3$ ceramic aluminina coating using the plasma electrolytic oxidation (PEO) method. The corrosion, stress corrosion cracking (SCC) and nano-mechanical behaviours were examined by means of potentiodynamic polarization, slow strain rate test (SSRT) and nano-indentation tests. The results indicated that the additional thermomechanical treatment during the forging process caused a fully recrystallized microstructure, which lead to the poor environmental cracking resistance of the alloy in 3.5% NaCl solution, despite the overaging treatment. Although the fabricated PEO coating improved general corrosion resistance, the brittle nature of the coating did not provide any improvement in SCC resistance of the alloy. However, the hardness and elastic modulus of the coating were significantly higher than the base alloy.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.505-514
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• 2000

The carburizing behavior and fatigue properties of the plasma carburized low carbon Cr-Mo steel(0.176C-1.014Cr-0.387Mo) have been investigated. The effective case depth in plasma carburized steel increased up to 50% in comparison with that of gas carburizing, and this case depth increased with the increasing surface carbon content. With increasing time in plasma carburizing, the surface carbon content increased but its increasing rate decreased. Fatigue properties were studied in terms of microstructure, case depth, retained austenite and residual stress near the surface. The fatigue limit of the plasma carburized steel was higher than that of gas carburized one. The initiation of microcracks and initial crack propagation were retarded due to a relatively little surface and internal oxidation layer in plasma carburized steel. Fractography showed the crack initiated at the surface, and transgranular fracture at surface layer was more predominant in plasma carburized steel compared to that of gas carburized steel.