• Food Science and Biotechnology
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• 제17권2호
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• pp.373-378
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• 2008

Contents of phytochemicals in citron (Citrus junos Sieb. ex Tanaka) seeds and their effects on antioxidant activities were investigated. Methanol extract of defatted citron seeds contained the highest amounts of total polyphenols followed by 70% ethanol and water extracts. Neohesperidin was the most predominant citrus flavanones in these extracts. The highest amounts of limonoids were found in methanol extract, and this extract was the most efficient in scavenging both DPPH and ABTS radicals. All 3 extracts also exhibited good antioxidant activities against attack of linoleate free radicals on $\beta$-carotene. When methanol extract was sequentially fractionated into ether, ethyl acetate, n-butanol, and water fractions, butanol fraction contained the highest amounts of polyphenols otherwise most of limonoids were concentrated in ethyl acetate fraction. A positive relationship between radical scavenging activities and total polyphenol contents in fractions was observed while antioxidant activity on $\beta$-carotene seemed more related with contents of limonoids and other hydrophobic polyphenols.

• 한국세라믹학회지
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• 제51권5호
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• pp.453-458
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• 2014

SiC and its composites have been considered for use as nuclear fuel cladding materials of pressurized light water reactors. In this study, a $SiC_f$/SiC composite as a constituent layer of SiC triplex fuel cladding was fabricated using a chemical vapor infiltration (CVI) process in which tubular SiC fiber preforms were prepared using a filament winding method. To enhance the matrix density of the composite layer, winding patterns, deposition temperature, and gas input ratio were controlled. Fiber arrangement and porosity were the main parameters influencing densification behaviors. Final density of the composites decreased as the SiC fiber volume fraction increased. The CVI process was optimized to densify the tubular preforms with high fiber volume fraction at a high $H_2$/MTS ratio of 20 at $1000^{\circ}C$; in this process, surface canning of the composites was effectively retarded.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2206-2208
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• 2003

This paper is performed to find the effects on body heat by stimulating the skin with the heat of a moxibustion cauterizer and the Artemisia-lotion which cause the extension of the blood vessel. The Artemisia-lotion is made by extracting the vasodilator and antioxidant compounds from the $Artemisia-CH_2Cl_2$ fraction. The moxibustion cauterizer is constructed with a DC power supply and 3 heating electrodes with PTC(Positive Temperature Coefficients) thermistor. The stimulation temperature level of the moxibustion cauterizer is $45^{\circ}C\;-48^{\circ}C$. We gave the subjects the following stimulating conditions; only heat stimulation, only Artemisia -lotion stimulation, and both stimulations. The measurement of body heat was performed with a infrared thermography system . Finally we could estimate the effects of a betterment of circulation of the blood from $Artemisia-CH_2Cl_2$ fraction.

• 보존과학연구
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• 통권31호
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• pp.89-102
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• 2010

This study evaluated the activity of biocidal compounds isolated from natural products and confirmed applicable possibility as conservative agents for orgainic cultural heritages damaged by biological degradation. we used methanol extracts of 11 Korean trees and 17 medicinal plants as natural resources. Among these extracts, Phellodendron amurense was investigated on antifungal activity against Coniophora puteana, Lentinus lepideus, Tyromyces palustris and Aspergillus niger. Asarum sieboldii was investigated on insecticidal activity against adult of Lasioderma serricorne. First, the extract of Phellodendron amurense was partitioned into hexane, dichloromethan and ethylacetate fraction. Among them, the ethylacetate fraction had the most significant antifungal activity. In addition, Asarum sieboldii essential oil showed an effective antifungal and insecticidal activity. As a result, the extract of Phellodendron amurense and Asarum sieboldii essential oil could be useful for conservation of organic cultural heritage against biological deterioration by wood rot fungi and Lasioderma serricorne.

• Corrosion Science and Technology
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• 제12권4호
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• pp.185-190
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• 2013

In the present study, $Ni-TiO_2$ composite coatings were electrodeposited in a sulfamate bath containing $TiO_2$ particles. The influence of the ultrasonic treatment on the co-deposition of $TiO_2$ particles in the coating and the hardness of the electrodeposited $Ni-TiO_2$ composite has been investigated. Three different ultrasonic treatments (pretreatment before the electrodeposition (pre-UT), pretreatment + applied during the electrodeposition (UT), and the electrodeposition without the ultrasonic treatment (w/o UT)) were performed. The $Ni-TiO_2$ composite coatings are characterized using scanning electron microscopy (SEM), image analyzer, and hardness tester. Comparison of results indicates that the volume fraction is more important factor than the agglomerated particle size in terms of the strength improvement, and the strength of the electrodeposited $Ni-TiO_2$ composite coatings is enhanced with pre-UT condition.

• 한국환경과학회지
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• 제19권5호
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• pp.577-584
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• 2010

The generation of $TiO_2$ nanoparticles by a thermal decomposition of titanium tetraisopropoxide (TTIP) was carried out experimentally using a tubular electric furnace at various synthesis temperatures (700, 900, 1100 and $1300^{\circ}C$) and precursor heating temperatures (80, 95 and $110^{\circ}C$). Effects of degree of crystallinity, surface area and anatase mass fraction of those $TiO_2$ nanoparticles on photocatalytic properties such as decomposition of methylene blue was investigated. Results show that the primary particle diameter obtained from thermal decomposition of TTIP was considerably smaller than the commercial photocatalyst (Degussa, P25). Also, those specific surface areas were more than 134.4 $m^2$/g. Resultant $TiO_2$ nanoparticles showed improved photocatalytic activity compared with Deggusa P25. This is contributed to the higher degree of crystallinity, surface area and anatase mass fraction of $TiO_2$ nanoparticles compared with P25.

• 한국생명과학회:학술대회논문집
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• 한국생명과학회 2005년도 제45회 학술심포지움 및 추계학술대회
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• pp.93-93
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• 2005

• 동의생리병리학회지
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• 제17권5호
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• pp.1288-1292
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• 2003

This study was carried out to evaluate cytotoxic effects of Houttuynia cordata T/sub HUNB/ extracts on A549 (lung cancer), MDA-MB231 (breast cancer), SNU-C4 (colon cancer) and B16 (mouse melanoma) cell lines. We have determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazoliumbromide (MTT) assay. The 150 ㎍/㎖ concentration of methanol extract (63.81 %) of Houttuynia cordata T/sub HUNB/ was shown significantly antitoxic activity on A549 cell lines. The order of cytotoxicity fractions of methanol from Houttuynia cordata T/sub HUNB/ extracts against cancer cell lines in vitro is as follows : hexane fraction layer > chloroform fraction layer > ethyl acetate fraction layer > buthanol fraction layer > water fraction layer. These results suggest that the hexane fraction of methanol extract from Houttuynia cordata T/sub HUNB/ extract may be a valuable choice for the development of antitumor agents.

• Biomolecules & Therapeutics
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• 제13권1호
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• pp.26-31
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• 2005

The present study examined effects of a water-soluble fraction from mulberry leaves (ML water fraction) on the circulatory and autonomic nervous systems, which were compared with those of acetylcholine (ACh) used as a reference drug in order to elucidate its mechanism of action. Intravenous administration of ACh or a ML water fraction produced temporary depressor and tachycardiac responses in a dose-dependent manner in unrestrained, conscious Sprague-Dawley rats. The systemic hemodynamic effects of ACh and a ML water fraction were almost completely blocked by pretreatment with atropine, a muscarinic antagonist. The depressor responses to ACh and a ML water fraction were slightly enhanced and prolonged by pretreatment with neostigmine, an anticholinesterase, whereas the tachycardiac responses were remarkably blocked by pretreatment with pentolinium, a ganglionic blocking agent. In vitro experiments using the ileum isolated from rats showed that ACh and a ML water fraction increased ileal contractility in a dose-dependent manner. The increases in ileal contractility were also completely abolished in the presence of atropine. Finally, the specific binding of [$^3H$]quinuclidinyl benzilate, a muscarinic antagonist, to rat cortical synaptic membranes was inhibited by a ML water fraction in a concentration-dependent manner with an IC$_{50}$ value of 9.5 mg/ml. The results suggest that the effects of a ML water fraction are mediated through direct stimulation of muscarinic cholinergic receptors by unknown cholinomimetic substance(s) contained in that fraction.

• 생약학회지
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• 제48권3호
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• pp.208-212
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• 2017

In this study, analysis of active compounds that are believed to be highly relevant to antioxidant activity was carried out on the methanol extract and its solvent fractions of Corni fructus. The DPPH radical scavenging activity for the comparison of antioxidant activity was higher in order of aqueous fraction > methanol extract > ethyl acetate fraction > n-hexane fraction. It is similar to the order of total polyphenol contents in the samples. As a result of LC-MS analysis, phenolic acid compounds such as caffeic acid, gallic acid and chlorogenic acid and lognin, which is known as a representative active ingredient of Corni fructus, were identified as active compounds. And the antioxidative activity and the total polyphenol content of the extracts and solvent fractions were found to be related to the contents of the compounds. Particularly, it was confirmed that phenolic acid such as caffeic acid contributes to the antioxidative activity of the aqueous fraction of Corni fructus methanol extract.