• Journal of Photoscience
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• v.5 no.1
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• pp.23-26
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• 1998

Irradiation of diphenylbutadiyne (DPB) in methanol with 9,10-dicyanoanthracene (DCA) yields four methanol adducts, two more than the products obtained in the absence of DCA. Laser flash photolysis studies indicate the reaction to proceed through a photoinduced electron transfer mechanism involving DPB cation radical and DCA anion radical.

• Bulletin of the Korean Chemical Society
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• v.7 no.2
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• pp.150-153
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• 1986

Co-sensitized photooxygenation of 1,1-diphenyl-2-vinylcyclopropane (VCP-DPh) with 9,10-dicyanoanthracene and biphenyl in oxygen-saturated acetonitrile solution produced 3,3-diphenyl-5-vinyl-1,2-dioxolane as the major product. The same photoproduct was obtained by acetone sensitized photooxygenation in oxygen-saturated acetone solution. However, VCP-DPh remained intact when directly irradiated with DCA or irradiated with Rose Bengal to generate singlet oxygen. A mechanism involving a cosensitizer radical cation and sensitizer radical anion is proposed.

• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1087-1088
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• 2007

• Journal of Radiation Protection and Research
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• v.21 no.2
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• pp.99-105
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• 1996

After high-dose irradiation(8 Gy). the viability of lymphocyte with a prior low-dose irradiation was 3.7-fold higher than that without a prior low-dose irradiation The viability could be increased by the reduction of oxygen radicals or the removal of damaged molecules-DNA, protein. lipid membrane. or the removal of damaged cells. In this paper. we studied the radioresistance mechanism in lymphocytes and lymphoma cells by examining the activities of radical scavengers(catalase. peroxidase, superoxide dismutase, and glucose-6-phosphate dehydrogenase), and a radical protector(glutathione). Different enzymes were induced in lymphocyte and lymphoma with low-dose irradiation. The activity of peroxidase increased most(133.3%) in lymphoma while the enzymes increased most in lymphocyte were superoxide dismutase (138.5%), glucose-6-phosphate dehydrogenase (122.4%) and glutathione(120.8%). The activities of these enzymes were highest when the interval was 7 hours between low-dose and high-dose irradiation.

• Preventive Nutrition and Food Science
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• v.12 no.3
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• pp.177-180
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• 2007

Tocotrienols (T3) are minor plant constituents found abundantly in rice bran, which provide a significant source of vitamin E in animal feeds. T3 was reported to have an intrinsic hypocholesterolemic effect by inhibiting HMG-Co A reductase. It has similar antioxidative properties as tocopherols in food and biological system due to their similar chemical structures. However, the antioxidant activity and mechanism of T3 to scavenge free radicals and to inhibit the peroxidation of linoleic acid are less understood. The purpose of this study was to investigate the scavenging effect of T3 on free radicals and its inhibition of peroxide formation. Free radical scavenging activity was monitored by the DPPH (1,1-diphenyl-2-picrylhydrazyl) method whereas inhibition of linoleic acid peroxidation was evaluated using the thiocyanate method. Thiobarbituric acid (TBA) test was used to determine malonaldehyde formation from linoleic acid peroxidation. Free radical scavenging activity increased with increasing concentration levels of T3. T3 exhibited 38.2, 78.6, 92.7 and 96.2% radical scavenging activity at concentrations of 2, 8, 32 and 128 ppm, respectively. At 128 ppm, it was highly effective in inhibiting linoleic acid peroxidation. The activity of T3 evaluated by the thiocyanate method showed low absorbance values indicating a high level of antioxidant activity. All treatments showed similar trends in antioxidant activity when evaluated by both the thiocyanate method and TBA test.

• Journal of Food Hygiene and Safety
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• v.15 no.3
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• pp.226-234
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• 2000

Protective effect of Corydalis ternata against the carbon tetrachloride-induced toxicity was investigated. Carbon tetrachloride($CCl_4$) induces hepatotoxicity due to the reactive free radical(CCl$_3$ . ) generated by cytochrome P-450 enzyme. We examined effects of hexane, chloroform, butanol and water fractions prepared from the Corydalis ternata methanol extract. Rats were treated with those for 3 days, and liver microsomes and cytosols were prepared at 24 hour after last treatment. Hepatoprotective activity of the water fraction was higher than that of other fractions. To examine mechanism of the hepatoprotective effect of Corydalis ternuta, we measured contents of malondialdehyde(MDA), cytochrome P46O(CYP), glutathione, calcium as well as the activities of NADPH-CYP reductase, glutathione S-transferase(GST), superoxide dismutase(SOD), glutathione peroxidase(GPX) and catalase. The fraction inhibited production of MDA, content of CYP and calcium in liver of water fractions - treated rats as compared with those of CCl4-treated rats. The GST activity was increased. We speculate that the O2 radical scavenging activities of the water fraction might play a key role in the mechanism opposing the progression of $CCl_4$-induced hepatotoxicity, but the activities of SOD, GPX, CAT were decreased. These results suggest that the mechanism might be mainly due to the decrease of CYP contents, act as calcium channel blocker and increase of GST activity rather than $O_2$ radical scavenging activities.

• Korean Journal of Pharmacognosy
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• v.36 no.2 s.141
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• pp.81-87
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• 2005

The effects of the DWP-04 [DDB:selenium yeast:glutathione (31.1 : 6.8 : 62.1 (w/w%)] on acetaminophen detoxification enzyme system were studied in rats. Treatment with DWP-04 was prevented againt acetaminophen-induiced hepatotoxicity in rat as evidenced by the decreased formation of lipid peroxide. Effect of DWP-04 on the activities of free radical-generating enzymes, free radical scavenging enzymes and glutathione-related enzymes as well as detoxification mechanism of DWP-04 against acetaminophen-treated was investigated in rat. Activities of cytochrome p450, cytochrome b5, aminopyrine demethylase and aniline hydroxylase as free radical-generating enzymes activities were decreased by the treatment with DWP-04 against acetaminophen treated. Although acetaminophen-induced hepatotoxicity results in the significantly decrease in the level of hepatic glutathione and activities of glutathine S-transferase, quinone reductase, glutathione reductase and ${\gamma}-glutamyl-$cysteine synthetase, these decreasing effects were markedly lowered in the DWP-04-treated rat. Therefore, it was concluded that the mechanism for the observed preventive effect of DWP-04 against the acetaminophen-induced hepatotoxicity was associated with the decreased activities in the free radical-generating enzyme system.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.184-184
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• 2011

Using first-principles density-functional calculations, we investigate the chain reaction mechanism of allyl alcohol (ALA) molecules on the H-terminated Si(001)-2${\times}$1 surface. Recently, it was reported [1] that allyl mercaptan (ALM) molecules show a self-directed line growth across the dimer rows through a chain reaction involving several reaction processes: (i) The created radical at the C atom is transferred to the S atom, (ii) the resulting S-centered radical easily abstracts an H atom from the neighboring dimer row, and (iii) the generated S-H group further reacts with the neighboring dimer row to produce the Si-S bond on the neighboring dimer row, accompanying the associative desorption of H2. This H2-desorption process creates a new DB on the neighboring dimer row, setting off the chain reaction across the dimer rows. In the present study, we find that although the structure of ALA with -OH functional is analogous to that of ALM with -SH functional, ALA and ALM lines show a difference in their growth direction. We predict that ALA undergoes the chain reaction to show a line growth along the dimer row, contrasting with the ALM line growth across the Si dimer rows. Our analysis shows that the different growth direction of ALA is due to the strong instability of oxygen radical intermediate, which prevents from growing across the dimer rows. Thus, we demonstrate that the stability of the radical intermediate plays a crucial role in determining the direction of molecular line growth.

• Journal of Korea Technology Innovation Society
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• v.21 no.1
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• pp.454-490
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• 2018

This paper examined the nonlinear relationships between external knowledge sources and the innovation performance of SMEs (small and medium-sized enterprises). Using 3,218 firm-year panel data in South Korea, this study found that increasing the number of external knowledge channels out of the value chain increases radical innovation. Meanwhile, increasing the number of external knowledge channels within the value chain increases the incremental innovation. Further, the external sources of knowledge both out of and in the value chain had inverted U-shaped relationships on radical and incremental innovation respectively. This finding implies that a mechanism of diminishing returns works in the relationship between the external sources of knowledge and innovation. The study also identified the synergistic effects between the external sources of knowledge out of the value chain and within the value chain, and confirmed that the synergistic effects strengthen the linear mechanism between the external sources of knowledge and innovation. In addition, this study found that the sources of knowledge both out of and within the value chain positively moderate the relationships between R&D investment and radical innovation of SMEs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.4
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• pp.392-397
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• 1993

The present work was undertaken to investigate the protective mechanism of Oenanthe iavanicu n-butanol extract on the carbon tetrachloride-induced hepatotoxicity in mice. It was observed that a striking enhancement of serum alanine aminotransferase and hepatic lipid peroxide content after carbon tetrachloride administration were markedly decreased by the presentment of Oenanthe javanica extract for 5 days. It was also observed that the hepatic aniline hydroxylase, catalase, glutathione S-transferase activity and glutathione content were not changed by the injection of Oenanthe javanica extract for 5 days. Whereas, hepatic xanthine oxidase activity was inhibited by the treatment of Oenanthe javanica extract for 5 days. After treatment with Oenanthe javanica extract, xanthine oxidase activity was decreased with dose and time-dependent manner as compared to control group. However, hepatic xanthine oxidase activity was not affected by the addition of Oenanthe javanica extract in vitro. These results suggest that the inhibition of hepatic xanthine oxidase activity by the injection of Oenanthe javanica extract is believed to be a possible protective mechanism for the carbon tetrachloride-indured hepatotoxicity in mice.