• Biomedical Science Letters
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• v.8 no.3
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• pp.155-159
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• 2002

To evaluate the physiological significance of xanthine oxidase (XO) in rat skin, the activity of XO (type O) in skin was compared with that of small intestine or liver. Concomitantly, XO activities in some partial portions (scalp, leg, dorsal and ventral part) of skin were determined and then compared with each partial portion. XO activity of skin was lower than that of small intestine and rather higher than that of liver. Furthermore, the activity of XO in skin, after clipping of hairs and then in 5 days, was more increased than that of rat which was clipped before having been sacrificed. As for activities of free radical scavenging system (GPx, GST, SOD), skin is lower than liver and small intestine. Although it is hewn that the oxygen free radical generated by XO system lead to injurious effect on the cell, the XO activity of ventral part which is to be less exposed to xenobiotics and biological agents was the lowest among those of ventral, dorsal, leg and scalp parts in skin. In conclusion, it may be hypothesized that XO system in skin act on defence mechanism.

• Advances in Traditional Medicine
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• v.10 no.4
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• pp.271-277
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• 2010

We tested to determine if Mori Cortex Radicis extract has antioxidant activities and its potential mechanism of action was explored. Anti-oxidative effects were tested by measuring free radical and nitric Oxide (NO) scavenging activity, and reducing power. Since iNOS and COX-2 are important enzymes responsible for the production of free radicals in the cell, Mori Cortex Radicis extract was tested as to whether it could inhibit iNOS and COX-2 expression in LPS stimulated Raw cells. 70% methanolic extract of Mori Cortex Radicis exerted significant DPPH free radical and NO scavenging activities. In addition, the Mori Cortex Radicis extract exerted dramatic reducing power with maximal activity observed at 1 mg/ml (11-fold over control). Production of iNOS induced by LPS was significantly inhibited by the Mori Cortex Radicis extract, suggesting it could inhibit NO production by suppressing iNOS expression. COX-2 induced by LPS was also significantly inhibited by the Mori Cortex Radicis extract. The extract contains well known antioxidant components including phenolics, flavonoids and anthocyanin at the concentration of 0.23 mg/g, 42.97 mg/g and 12.08 mg/g, respectively. These results suggest that 70% methanolic extract of Mori Cortex Radicis exerts significant anti-oxidant activity via inhibiting iNOS and COX-2 induction.

• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.315-321
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• 1984

The electrochemical reduction of 0,0-dimethyl-0-(3-methyl-4 -nitrophenyl)-phosphorothioate ($Sumithion^{(R)}$) in acetonitrile solution has been studied by direct current (DC), differential pulse (DP) polarography and cyclic voltammetry methods. The irreversible electron-transfer chemical reaction (EC) mechanism of Sumithion proceeds by six electron-transfer to form radical and reduction of three-step which undergoes single bond of the phosphorus atom & phenoxy group by electron-transfer and protonation cleaved to give p-hydroxyamino-m-cresol and dimethylthiophosphonate as major product.

• Textile Coloration and Finishing
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• v.24 no.1
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• pp.33-38
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• 2012

In this study, to increase flame retardation of poly(ethylene terephthalate) (PET) in burning, bisphenol A bis(diphenyl phosphate) (BDP), a well known flame retardant containing phosphorous, was reacted on end groups of PET by radical pathway. End-capping mechanism of PET with BDP was suggested and confirmed by spectroscopic and thermal analysis. From 400 MHz $^{31}P$ solid state FT-NMR spectrum of end-capped PET (PET-BDP), phosphorus spectra peak in BDP was found at ca. -20 ppm. Furthermore, P-C bond stretching vibration peaks were found ca. $600cm^{-1}$ in FT-IR spectrums of PET-BDP. These results showed that BDP can be chemically added on end groups of PET by our method. Thermal characteristics of pure PET (pPET) and PET-BDP were measured and evaluated by TGA analysis. There was not significant changes in thermal characteristics of PET-BDP compared to that of pPET.

• YAKHAK HOEJI
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• v.45 no.3
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• pp.258-268
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• 2001

Garlic has been known to be effective against the gastrointestinal diseases which can be induced by production of oxygen-derived free radical. It has been shown that bamboo salt is effective on the treatment and prevention of various gastrointestinal disorders. Bamboo salt is a processed salt invented by a Korean, ll-Hoon Kim. It has been reported that garlic and bamboo-salt are useful to the treatment of gastric disorders in Korea. To clarify the protective mechanism of the garlic-bamboo salt mixture, the gas-tropathy was induced in rats with alcohol-salicylate and the activities of the free radical scavenging enzymes were examined. In this study, we found that the garlic-bamboo salt mixture reduced the severity of hemorrhagic lesion in gastric mucosa in the rats. In addition, the activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) were significnatly increased and the total content of GSH was recovered. From those results, we concluded that the protective effect of the garlic-bamboo salt mixture on gastropathy in rats is its ability to recover the level of GSH and to increase the activities of the free radical scavenging enzymes (SOD, GPx, GR).

• Asia-Pacific Journal of Business
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• v.11 no.3
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• pp.217-227
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• 2020

Purpose - Against the backdrop of the recent intense political conflict in Korea's political circles, it is to reveal from an economic point of view the hidden aspects behind the hostile conflict between the two political forces. Design/methodology/approach - This paper is not a normative study to find a solution to political conflict, but a positive study to reveal the mechanism of reciprocity that exists between the two parties of conflict in real politics. Therefore, the analysis is based on game theory methodology. Findings - It is shown that the ruling party should choose a level of preemptive response that is neither insufficient nor excessive if it aims to avoid radical anti-government struggles by opposition parties. We also find that even if the chances of success of the opposition's radical offensive struggle are low, the use of that strategy is not necessarily reduced. In addition, we have obtained comparative static results that do not deviate much from our intuition. What's interesting is that unlike our intuition that the choice of the method will be indifferent if the marginal effects of radical and normal methods of struggle are the same, the opposition party rather chooses the normal method of struggle more often. Research implications or Originality - In forming the analytical model, it reflected the support of the general public following the opposition's struggle against the ruling party in order to capture real politics well in the conflict between the two opposing parties.

• The Korean Journal of Food And Nutrition
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• v.35 no.5
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• pp.313-323
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• 2022

To investigate antioxidant effects of tea tree root extracts using various extraction methods, cytotoxicity, DPPH and ABTS radical scavenging, SOD, nitrite scavenging activity and inhibitory activity of lipid peroxidation, reducing power, ferrous ion chelating activity were measured. Cytotoxicity for RAW 264.7 cells was not observed at concentrations treated with below 90 ㎍/mL in all extracts. The maximum DPPH radical, nitrite scavenging, SOD activity and inhibitory activity of lipid peroxidation were obtained at the ethylacetate and 70% ethanol extract. The maximum ABTS radical scavenging activity was obtained at the ethylacetate and hot water extract. However, in the case of reducing power and ferrous ion chelating activity, they were obtained at 70% ethanol and hexane extract, respectively. Nitrate scavenging activity showed the most excellent scavenging ability of 59.6% at 90 ㎍/mL of ethylacetate. The hexane extract had the highest ferrous ion chelating activity, showing 61.05% at 50 ㎍/mL, 66.07% at 70 ㎍/mL and 76.81% at 90 ㎍/mL, respectively. The results of this research show that the ethylacetate and 70% ethanol extracts of tea tree root can be used as a natural material for scavenging the radicals. However, future study is necessary to understand the mechanism of antioxidant activity by identification of substances.

• Nuclear Engineering and Technology
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• v.8 no.3
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• pp.159-168
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• 1976

Acrylic acid has been grafted onto nylon fabric with ceric salts and ${\gamma}$-rays from Co-60 as initiators. The distribution of molecular weight of the grafted polyacrylic acid has been determined and it was found that the ratio of weight-average and number-average molecular weight was higher in room temp. than in low temp. (-184$^{\circ}C$). The weight-average molecular weight of the polyacrylic acid was calculated from viscosity measurements in sodium hydroxide solution. The factors affecting graft polymerization of acrylic acid onto nylon were examined. A possible mechanism that the oxidation of nylon probably takes place at the methylene group attached to nitrogen to give a free-radical was discussed.

• Genomics & Informatics
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• v.8 no.4
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• pp.170-176
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• 2010

The Ribonucleotide reductases (RNR) are essential enzymes that catalyze the conversion of nucleotides to deoxynucleotides in DNA replication and repair in all living organisms. The RNRs operate by a free radical mechanism but differ in the composition of subunit, cofactor required and regulation by allostery. Based on these differences the RNRs are classified into three classesclass I, class II and class III which depend on oxygen, adenosylcobalamin and S-adenosylmethionine with an iron sulfur cluster respectively for radical generation. In this article thirty seven sequences belonging to each of the three classes of RNR were analyzed by using various tools of bioinformatics. Phylogenetic analysis, dot-plot comparisons and motif analysis was done to identify a number of differences in the three classes of RNRs. In this research article, we have attempted to decipher evolutionary relationship between the three classes of RNR by using bioinformatics approach.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.213-213
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• 1994

배풍등, 등혹 및 ginsenoside Rh$_1$의 간암세포에 대한 세포독성작용, 인삼 Rh$_1$의 세포보호작용, 비파의 ursolic acid 생체방어기전 활성화 및 산화억제작용, ononin의 radical 제거능을 검토하였다. 그 결과 배풍등 CHCl$_3$분획 및 등혹 CHCl$_3$분획의 간암세포에 대한 강한 세포독성작용을 나타내었으며 배풍등 CHCl$_3$은 sarcoma 180 이식 종양조직의 성장을 유의성있게 억제하였다. Ursolic acid는 지질과산화, 단백질 산화억제와 catalase, GSH S-transferase를 활성화시켰다. 인삼 saponin은 SOD 및 nonprotein-SH를 증가시키고, 지질과산화를 억제시켰다. Ginsenoside Rh$_1$ 및 Rh$_2$는 각각 radical에 대한 세포보호작용과 간암세포 세포독작용을 나타내었다.