• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.4
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• pp.322-327
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• 2003

Giant magnetoresistance(GMR) NiO multilayer, which has been used to reading head of highly dense magnetic recording, was fabricated, and oxidized in an air during 80 days to study the dependence of magnetoresistance properties on residual stress in the interfaces. The magnetoresistance ratio and the exchange biasing $field(H_{ex})$ of $NiO(60nm)/Ni_{81}Fe_{19}(5nm)/Co(0.7nm)/Cu(2nm)/Co(0.7nm)/Ni_{81}Fe_{19}(7nm)$ spin valves were increased from 4.9% to 7.3%, and 110 Oe to 170 Oe after natural oxidation in the atmosphere for 80 days, respectively. The sheet resistivity ${\rho}$ decreased from $28{\mu}{\Omega}m$ to $17{\mu}{\Omega}m$, but ${\Delta}p$ did not almost change after the oxidation. Therefore, the increase of MR ratio is due to the decrease in the sheet resistivity. the reduced resistance may result from the increase in the reflection of conduction electrons at the oxidized top surface. Also, the increase in the exchange biasing field is originated from the reduction of residual stress at the interface of $NiO/Ni_{81}Fe_{19}$ according as the aging time increases.

• Journal of Life Science
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• v.20 no.12
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• pp.1777-1783
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• 2010

Plants generate reactive oxygen species (ROS) as a by-product of normal aerobic metabolism or when exposed to a variety of stress conditions, which can cause widespread damage to biological macromolecules. To protect themselves from oxidative stress, plant cells are equipped with a wide range of antioxidant proteins. However, the detailed reaction mechanisms of these are still unknown. Peroxiredoxins (Prxs) are ubiquitous thiol-containing antioxidants that reduce hydrogen peroxide with an N-terminal cysteine. The active-site cysteine of peroxiredoxins is selectively oxidized to cysteine sulfinic acid during catalysis, which leads to inactivation of peroxidase activity. This oxidation was thought to be irreversible. Recently identified small protein sulphiredoxin (Srx1), which is conserved in higher eukaryotes, reduces cysteine.sulphinic acid in yeast peroxiredoxin. Srx1 is highly induced by $H_2O_2$-treatment and the deletion of its gene causes decreased yeast tolerance to $H_2O_2$, which suggest its involvement in the metabolism of oxidants. Moreover, Srx1 is required for heat shock and oxidative stress induced functional, as well as conformational switch of yeast cytosolic peroxiredoxins. This change enhances protein stability and peroxidase activity, indicating that Srx1 plays a crucial role in peroxiredoxin stability and its regulation mechanism. Thus, the understanding of the molecular basis of Srx1 and its regulation is critical for revealing the mechanism of peroxiredoxin action. We postulate here that Srx1 is involved in dealing with oxidative stress via controlling peroxiredoxin recycling in Arabidopsis. This review article thus will be describing the functions of Prxs and Srx in Arabidopsis thaliana. There will be a special focus on the possible role of Srx1 in interacting with and reducing hyperoxidized Cys-sulphenic acid of Prxs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.245-245
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• 2009

l-D nanostructured materials have much more attention because of their outstanding properties and wide applicability in device fabrication. Copper oxide(CuO) has been realized as a p-type metal oxide semiconductor with narrow band gap of 1.2 -1.5eV. Copper oxide nanostructures can be synthesized by various growth method such as oxidation reaction, thermal evaporation thermal decomposition, sol-gel. and Mostly CuO nanowire prepared on the Cu substrate such as Copper foil, grid, plate. In this study, CuO NWs were grown by thermal oxidation (at various temperatures in air (1 atm)) of Cu metal deposited on CuO (20nm)/$SiO_2$(250nm)/Si. A 20nm-thick CuO layer was used as an adhesion layer between Cu metal and $SiO_2$

• Journal of Welding and Joining
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• v.27 no.5
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• pp.55-61
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• 2009

Pure titanium and its alloys have good formability, excellent corrosion resistance and high strength to weight ratios. Therefore, it has been using to heat exchangers, offshore plants, sports equipments, and etc. As broad as its application fields, it also increases welding locations. Conventional GTAW and GMAW are very popular welding methods of titanium, but it has a high heat input and wide HAZ. It has a possibility of inducing Stress Corrosion Cracking. So, laser welding method has been using to get reliable welds by reducing heat input. Weld beads change its color to silver, gold, brown, blue, and gray by shied conditions. And the closer to gray, the more oxidize, nitride and embrittlement. The most effective atom to embrittlement was nitrogen. And shield gas flow was not so effective over the constant flow rates. In this study, weld properties of the pure titanium were investigated by pulsed & CW Nd:YAG lasers and evaluated by various shield conditions. And It is observed that nitrogen is more effective to oxidation and embrittlement of titanium compared with oxygen by oxygen and nitrogen quantitative analysis.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.52-57
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• 2006

Metallothioneins(MTs) belong to the class of low molecular weight proteins. Recently, it has been suggested that MTs may playa direct role in cellular defense against oxidative stress by functioning as antioxidants. Oxidative damage to different cellular components makes a major contribution to many pathogenenesses. Several studies have demonstrated that MT is able to quench a wide range of reactive oxygen species at a higher efficiency than other well known antioxidants such as superoxide dismutate(SOD). The present study was designed to evaluate the effect of MT on the activities of the reactive oxygen species removal system. MT showed the scavenging of superoxide in the SOD assay system in the presence or absence of SOD. When MT was added to nicotinamide adenine dinucleotide phosphate(NADPH) oxidation system in presence of fixed amount of SOD increase the breakdown rate of superoxide. When MT was added to the system that form nitrite from hydroxylammonium chloride, the formation of nitrite was inhibit. We concluded that the function of MT as antioxidant might have an effect on the level of superoxide scavenging.

• Journal of Hydrogen and New Energy
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• v.21 no.6
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• pp.526-532
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• 2010

The anode may inevitably undergo a number of reduction.oxidation (redox) cycles during solid oxide fuel cells (SOFCs) operation. The re-oxidation of Ni to NiO causes significant mechanical stress to be developed across the anode, which may destroy the integrity of the whole cell. In this study, the redox behavior of Ni-YSZ composite was examined at $800^{\circ}C$ using various characterization techniques.

• The Korea Journal of Herbology
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• v.26 no.1
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• pp.87-96
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• 2011

Objectives : The aerial parts of Rumex japonicus Houtt. (RF) is used by traditional clinics to treat parasite infection in East asia. This study aims a verification of anti-oxidative and anti-inflammatory effects of RF methanol extract. Methods : Anti-oxidative effects of RF were measured by scavenging activities of DPPH, superoxide, nitric oxide (NO) and peroxynitrite radicals. And also scavenging activities of anti-oxidation in lipopolysaccharide (LPS)-treated RAW 264.7 cells were measured. The inhibitory effects against the production of inflammatory mediators including NO, prostaglandin $E_2$ ($PGE_2$), tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-$1{\beta}$ (IL-$1{\beta}$), IL-6, inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and the translocation of nuclear factor (NF)-${\kappa}B$ in LPS-stimulated RAW 264.7 cells by RF were tested. Results : RF scavenged DPPH, superoxide, NO and peroxynitrite radicals, and RF (at $200{\mu}g/m{\ell}$) reduced the inflammatory mediators definitely. Conclusions : These results indicate that RF may be a potential drug source for oxidative stress related inflammatory diseases.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.5
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• pp.1309-1314
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• 2008

This study was undertaken to elucidate the antioxidant activity of the ethanol (EEPB) and water (WEPB) extracts of Prunus persica branches. The extracts contained a high phenolic content and revealed a potent hydrogen donating activity in DPPH scavenging assay. Compared to $\alpha$-tocopherol, EEPB (p < 0.001) and WEPB (p < 0.05) significantly inhibited $FeCl_2$-ascorbic acid-induced lipid peroxidation, and also exhibited potent antiradical activities against hydroxyl radical, superoxide anion, nitric oxide and peroxynitrite. In copper- and AAPH-mediated human low-density lipoprotein (LDL) oxidation systems, the extracts demonstrated a strong antioxidant function by metal chelating, rather than direct scavenging, action. Furthermore, EEPB at 5 ${\mu}g/mL$ concentration showed 80.77% inhibition of the electrophoretic mobility of LDL, compared to 77.69% for ascorbic acid and 76.92% for BHT. These results suggest that PB branch extracts may protect against oxidative stress-induced diseases.

• Herbal Formula Science
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• v.9 no.1
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• pp.375-385
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• 2001

Objectives : This study was carried out to research the protective effects of Sagunja-Tang(SA) through in vivo experiments, and tried to investigate the relation between oxidation of liver tissues and deficiency of Qi. Methods : Acute liver injury which initiated from free radical induced by $CCl_4$, were applied to mice and metabolic data were obtained. In order to measure the degree of liver injury, serum level of alanine aminotransferase(AST), aspartate aminotransferase(ALT), creatinine, blood urea nitrogen(BUN), total protein(TP) and glucose were measured. Lipid peroxidation of liver slice was examined by measuring malondialdehyde(MDA), a product of lipid peroxidation. Results : SA had protective effects on $CCl_4$ induced acute liver injury by decreasing serum level of ALT. Kidney injury was induced by injection of $CCl_4$ too, and SA protected kidney injury by decreasing serum level of creatinine and BUN. Conclusions : Through this study, we found that SA have healing effects on liver and kidney injury of $CCl_4$ induced oxidative stress that is similar to deficiency of Qi. And further studies have to be followed to certify the mechanisms.

• Nuclear Engineering and Technology
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• v.43 no.5
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• pp.421-428
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• 2011

The out-of-pile mechanical performance and microstructure of recrystallized Zr-1.5 Nb-S alloy was investigated. The strength of the recrystallized Zr-1.5Nb-O-S alloys was observed to increase with the addition of sulfur over a wide temperature range, from room temperature up to $300^{\circ}C$. A yield drop and stress serrations due to dynamic strain were observed at room temperature and $300^{\circ}C$. Wavy and curved dislocations and loosely knit tangles were observed after strained to 0.07 at room temperature, suggesting that cross slip is easier. At $300^{\circ}C$, however, dislocations were observed to be straight and aligned along the slip plane, suggesting that cross slip is rather difficult. At $300^{\circ}C$, oxygen atoms are likely to exert a drag force on moving dislocations, intensifying the dynamic strain aging effect. Oxygen atoms segregated at partial dislocations of a screw dislocation with the edge component may hinder the cross slip, resulting in the rather straight dislocations distributed on the major slip planes. Recrystallized Zr-Nb-S alloys exhibited ductile fracture surfaces, supporting the beneficial effect of sulfur in zirconium alloys. Oxidation resistance in air was also found to be improved with the addition of sulfur in Zr-1.5 Nb-O alloys.