• Journal of Radiation Industry
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• v.5 no.3
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• pp.249-252
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• 2011

Lignin is one of the natural macromolecules. Every year large amount of lignin arises from the cellulose production as a by-product worldwide. The use of lignin as a precursor to carbonaceous materials has gained interest due to its low cost and high availability. Therefore, we improved the properties of alkali-lignin by exposing to gamma ray in this study. The alkali-lignin is irradiated by Gamma ray irradiation with varying doses. The char yields of alkali-lignin were investigated by increasing up to 50 kGy. The cross-linking and bond scission of alkali-lignin occur simultaneously during gamma ray irradiation. The crosslinking was predominantly accelerated by gamma ray irradiation up to 50 kGy. Bond scission predominantly occurs between 50 and 500 kGy. ESCA analysis indicated that the alcoholic carbon increase up to 50 kGy. Solution viscosity was increased as absorbed dose increased up to 20 kGy. In addition, the aromatic ring was not influenced by irradiation at doses ranging from 20 to 500 kGy as shown in FT-IR results.

• Applied Biological Chemistry
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• v.41 no.1
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• pp.78-83
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• 1998

Anticarcinogenicity of 12 kinds of colored rice cultivars was investigated in vitro with Ilpumbyeo as a control. Pigment and hexane fractions were prepared from the rice brans through extraction with 80% ethanol containing 0.5% TFA or n-hexane to use subsequent evaluation of their anticarcinogenic effect by determining inhibitory activity against DNA strand scission and tumor promotion, as well as antimutagenic activity using SOS chromotest system. Antimutagenic activity of the pigment fractions was revealed to decrease in order of LK1B4-12-1-1 > Sanghaehanghyulla > HP833-1-3-1-1 > Chokoto14 > Jagwangdo > Jajin > Kilmheugmi > Tiwan-Tsi-C > Heugjinmi > Linsia-Shoea-Dau > Suweon425 > Suweon415. The activity of the hexane fractions decreased in order of LK1B4-12-1-1 > Sanghaehyanghyulla>Ilpunibyeo > HP833-1-3-1-1 > Chokoto14 > Jagwangdo > Jajin > Linsia-Shoea-Dau >Tiwan-Tsi-C > Heugjinmi > Suweon425, Kilimheugmi > Suweon415. Results showed that inhibitory activity against DNA strand scission in the pigment fractions decreased in order of HP833-1-3-1-1 > Tiwan-Tsi-C > Jajin > Chokoto14 > Suweon425 > Heugjinmi > LK1B4-12-1-1 > Suweon415 > Jagwangdo > Kilimheugmi > Linsia-Shoea-Dau > Sanghaehyanghyulla. On the other hand, the activity of the hexane fractions decreased in order of LK1B4-12-1-1 > Suweon 415 > Kilimheugmi > Chokoto14 > Heugjinmi > Jajin > Suweon425 > Tiwan-Tsi-C > Sanghaehyanghyulla a Linsia-Shoea-Dau > Jagwangdo > HP833-1-3-1-1 > Ilpumbyeo. Experiment using the short-term assay for promotor substance showed that inhibitory activity contained in the pigment fractions against rumor promotor TPA decreased in order of Linsia-Shoea-Dau > Kilimheugmi > HP833-1-3-1-1, Suweon425 > Heugjinmi > Jajin > Chokoto14 > Sanghaehyanghylla > Suweon 415 > LK1B4-12-1-1 > Tiwan-Tsi-C > Jagwangdo.

• Journal of the Korean Chemical Society
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• v.11 no.2
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• pp.77-80
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• 1967

Radiolysis of polyacrylonitrile(PAN) has been studied. Parameters for crosslinking and scission induced by gamma-ray irradiation were obtained by means of sol-gel partitioning method. G-value of crosslinking in PAN ($\bar{M}n=6{\times}10^5$) was 0.038 and the gel dose 21.6 Mrad. The effects of irradiation on the thermal degradation rate in PAN was also studied. No appreciable changes in thermal degradation rate observed up to 81.8 Mrad of irradiation dose.

• Archives of Pharmacal Research
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• v.6 no.2
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• pp.137-140
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• 1983

A rapid, high yield of N-norapomorphine from apomorphine was accomplished by allowing it to react with phenyl chloroformate without isolating and purifying the intermediate carbamate, and have found that the crude carbamate can be easily cleaved in situ with a 1:1 mixture of 64% and 95% hydrazine to afford analytically pure N-norapomorphine in 81% overall yields. Previously, various other methods gave an untoward ring opening reactions and scission of the hydropyridine ring in the apomorphine series.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.10b
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• pp.160-160
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• 2003

Antioxidative potentials of estrogen and genistein were compared by measuring the degree of protection against plasmid DNA strand breakage induced by peroxyl free radicals using the DNA strand scission assay with pBR322 DNA. Genistein decreased DNA strand breakage by AAPH radical treatment at the all of three concentrations tested (0.5, 1.0, 1.5 $\mu\textrm{g}$/$m\ell$) with the range of 89.5% to 99.6%.(omitted)

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.540-544
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• 2008

Pyrolytic characteristics of mixed plastics containing 22 wt.% HDPE, 17 wt.% LDPE, 27 wt.% PP, 12 wt.% PS, 16 wt.% ABS, 6 wt.% PVC have been studied in the batch-type microreactor of stainless steel. Thermal degradation experiments were performed at temperature of $410{\sim}450^{\circ}C$. The yield of each pyrolytic products were obtained by the weight measurement and molecular weight distribution of pyrolytic liquid products determined by the GC-SIMDIS method. It was shown that the yield and molecular weight of pyrolytic liquid product were decreased with the increase of reaction temperature and time. It was know that 20wt% of PVC composing of the mixed plastics was converted to the gas products of chloride during the pyrolysis process. The chain-end scission rate parameter was determined to be 50.2 kcal/mole of mixed plastics by the Arrhenius plot.

• Natural Product Sciences
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• v.15 no.2
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• pp.101-105
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• 2009

We previously reported that a novel cerebroside, LCC, isolated from the fruits of Lycium chinense (Solanaceae), significantly exerted hepatoprotective activity against both the carbon tetrachloride-induced and galactosamine-induced toxicities in primary cultures of rat hepatocytes. In the present study, we further attempted to determine the effect of LCC on hepatic fibrosis in animal model. Hepatic fibrosis was induced in rats by bile duct ligation/scission (BDL) for a period of 5 weeks. Treatment of BDL rats with LCC significantly reduced collagen deposition and the activities of serum alkaline phosphatase and ${\gamma}$-glutamyl transpeptidase. In addition, the LCC treatment of BDL rats significantly preserved the decreased hepatic glutathione as well as the activities of glutathione reductase and catalase in BDL rats. From the results, it can be speculated that LCC might exert antifibrotic activity in rats with BDL, in part, through the preservation of antioxidant enzymes and hepatic glutathione.

• Composites Research
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• v.16 no.6
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• pp.33-40
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• 2003

The initial thermal degradation of polymer matrix composite is not observed easily. At the beginning of thermal degradation of polymer matrix composites, phase transformation such as chain scission, oxidation occur, and then micro delamination is produced in matrix and interface between matrix and fiber before blistering. Initial heat damage deteriorate mechanical properties of composites. We presented the detection method of the initial heat damage of composites conveniently using ultrasonic technique. Absorption coefficient and material velocity was measured with thermal degradation and degree of cure. The more thermal degradation was progressed, the more absorption coefficient was increased. When the cure temperature is more high, the absorption coefficient of cured composite is increased and material velocity is decreased. We concluded that cure temperature is more high, the defects such as void is increased and molecular structure cured at high temperature has cross-linking structure which is more absorb the ultrasonic waves.

• Biomedical Science Letters
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• v.15 no.1
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• pp.1-8
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• 2009

Human genomic DNA is continuously attacked by oxygen radicals originated from cellular metabolic processes and numerous environmental carcinogens. 2-deoxyribonolactone (dL) is a major type of oxidized abasic (AP) lesion implicated in DNA strand scission, mutagenesis, and formation of covalent DNA-protein crosslink (DPC) with DNA polymerase (Pol) ${\beta}$. We show here that human DNA polymerase (Pol)${\iota}$ and mitochondrial $Pol{\gamma}$ give rise to stable DNA-protein crosslink (DPC) formation that is specifically mediated by dL lesion. $Pol{\gamma}$ mediates DPC formation at the incised dL residue by its 5'-deoxyribose-5-phosphate (dRP) lyase activity, while $Pol{\gamma}$ cross links with dL thorough its intrinsic dRP lyase and AP lyase activities. Reactivity in forming dL-mediated DPC was significantly higher with $Pol{\gamma}$ than with $Pol{\iota}$. DPC formation by $Pol{\gamma}$, however, can be reduced by an accessory factor of $Pol{\gamma}$ holoenzyme that may attenuate deleterious effects of crosslink adducts on mitochondrial DNA. Comparative kinetic analysis of DPC formation showed that the rate of DPC formation with either $Pol{\iota}$ or $Pol{\gamma}$ was lower than that with $Pol{\beta}$. These results revealed that the activity of catalytic lyase in DNA polymerases determine the efficiency of DPC formation with dL damages. Irreversible crosslink formation of such DNA polymerases by dL lesions may result in a prolonged strand scission and a suicide of DNA repair proteins, both of which could pose a threat to the genetic and structural integrity of DNA.

• Polymer(Korea)
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• v.26 no.5
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• pp.599-606
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• 2002

In this study, 4,4'-tetraglycidyl diaminodiphenyl methane (TGDDM)/polyamideimide (PAI) blends were cured using diaminodiphenyl sulfone (DDS). And the effect of addition of different PAI contents to neat TGDDM was investigated in the thermal, mechanical, and morphological properties of the blends. The cure behavior and thermal stability of the cured specimens were monitored by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Also, the critical stress intensity factor (K$\_$IC/) was measured in UTM, and the phase separation behavior and final morphology of TGDDM/PAI blends were examined in scanning electron microscopy(SEM). As a result, the cure temperature and cure activation energy (E$\_$a/) were decreased with increasing the PAI content. The decreasing of cure temperature and cure activation energy were probably due to the presence of secondary amine group of PAI backbone used as co-initiator. But, the decomposition activation energy (E$\_$t/) and K$\_$IC/ value were increased up to 5. 10 phr of PAI content, respectively and they were decreased above the PAI contents. These results were explained on the basis of chain scission reaction by etherification. And morphology of blends observed from SEM was confirmed in co-continuous structures.