• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.3
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• pp.139-144
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• 2003

Nickel fine powders were prepared from nickel chloride aqueous solution containing ethanol as an organic solvent, and their oxidation behaviors were investigated. The reduction reaction by hydrazine from nickel chloride aqueous solution containing ethanol depend on reaction temperature. The reduction reaction time by hydrazine decreased with the increase of reaction temperature. By controlling reaction temperature, the products could be obtained spherical particles in the range of 0.1 $\mu\textrm{m}$~1.0 $\mu\textrm{m}$. Also, As reaction temperature increased from $40^{\circ}C$ to $80^{\circ}C$, the particle size slightly increased and had a broad size distribution owing to the presence of the coarse particles. The mean particle size and specific surface area of nickel powders prepared at $60^{\circ}C$ were 0.3 $\mu\textrm{m}$ and 31.8 $\m^2$/g, respectively. Weight loss of the powders at $300^{\circ}C$ was due to composition of $_Ni(OH)2$. In case of heat treatment at $200^{\circ}C$ in air, oxidation resistance of nickel powders was remarkable than that of as-synthesized.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.4
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• pp.393-402
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• 1997

In the present study, we characterized the angiotensin II (AII)-induced relaxations in the phenylephrine-precontracted rabbit mesenteric arteries with endothelium. 1) AII-induced relaxation was consistently observed in the rabbit mesenteric arteries with and without endothelium, but not in the aortic segment with endothelium. 2) AII-induced endothelium-dependent relaxation was markedly inhibited by $N^w-nitro-L-arginine$ (L-NNA, $100\;{\mu}M$), methylene blue ($10\;{\mu}M$) and LY83583 ($10\;{\mu}M$), respectively. 3) Inhibition of cyclooxygenase with indomethacin ($10\;{\mu}M$) strongly decreased the vasorelaxant response to AII irrespective of the presence of endothelium. 4) 7-Ethoxyresorufin ($1\;{\mu}M$) and clotrimazole ($1\;{\mu}M$), inhibitors of cytochrome P-450-dependent arachidonic acid metabolism, greatly attenuated the vasodilator response to AII. 5) Carbacyclin, arachidonic acid and prostaglandin $F_{2{\alpha}}$ ($PGF_{2{\alpha}}$) caused concentration-dependent relaxations in the mesenteric artery with endothelium, which were inhibited by L-NNA and methylene blue. 6) AII and $PGF_{2{\alpha}}$ significantly stimulated cyclic GMP formation in the mesenteric arteries with endothelium, which was inhibited by L-NNA and methylene blue, respectively. 7) AII enhanced synthesis of $PGF_{2{\alpha}}$ and 6-keto $PGF_{1{\alpha}}$ from the arterial segments with endothelium, which was inhibitable by indomethacin, but not by L-NNA. In conclusion, the vasorelaxant responses to AII of the rabbit mesenteric artery with endothelium are subserved by arachidonic acid and its metabolites produced via activation of cyclooxygenase and cytochrome P-450 enzyme as well as by nitric oxide.

• Korean Journal of Food Science and Technology
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• v.49 no.5
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• pp.519-523
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• 2017

We investigated the applications of functional materials through the examination of a variety of physiological activities of Ipomoea aquatica extract. I. aquatica extract showed low cytotoxicity against murine melanoma B16F10 cells. At concentrations that exerted little or no cytotoxicity to the cells, I. aquatica extract showed high DPPH radical scavenging activity ($ID_{50}$, $7.84{\mu}g/mL$), inhibited tyrosinase activity ($ID_{50}$, $106.56{\mu}g/mL$), and decreased melanin content ($ID_{50}$, $41.75{\mu}g/mL$). The treatment of B16F10 cells with I. aquatica extract suppressed the protein expression of tyrosinase in a dose-dependent manner. These findings suggested that I. aquatica extract inhibited melanin synthesis in murine melanoma B16F10 cells through the suppression of intracellular tyrosinase expression, as well as the simultaneous direct inhibition of tyrosinase activity. Additionally, I. aquatica extract promoted the expression of involucrin, which is related to skin barrier protection. These results indicate that I. aquatica extract may be an appropriate material for the improvement of skin barrier function.

• YAKHAK HOEJI
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• v.35 no.6
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• pp.497-503
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• 1991

Six novel 5-substituted-1-[2-(3-methoxy-2-hydroxyphenyl)-1-methoxyethyl]uracils 2a-f were prepared by condensation of 2,4-bis(trimethylsilyloxy)-5-substituted uracils with 2,7-dimethoxy-2,3-dihydrobenzofuran (9) in the presence of Lewis acid. The 2,3-dihydrobenzofuran derivative 9 was obtained by intramolecular acetalization of 2-acetoxy-3-methoxyphenyl acetaldehyde (8) which was synthesized by oxidative cleavage of 1-allyl-2-acetoxy-3-methoxybenzene (7) using osmium tetroxide followed by $NaIO_4$. Compounds 2a-f were evaluated for in vitro antiviral activity against HSV-1, HSV-2 and HRV. None of these compounds showed activity with $ID_{50}$ values up to $100\;{\mu}g/ml$ except for 5-chlorouracil derivative 2d which exhibited antiviral activity against HSV-1 with $ED_{50}$ $30\;{\mu}g/ml$. In the antitumor activity against L1210 and P388 leukemia cell lines, 2d showed activity with $ID_{50}$ values of $14\;{\mu}g/ml$ and $11.6\;{\mu}g/ml$, and 2c with $ID_{50}$ values of $22.9\;{\mu}g/ml$ and $8.8\;{\mu}g/ml$, respectively.

• Resources Recycling
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• v.18 no.2
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• pp.56-61
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• 2009

The dissolution of domestic aluminum hydroxide of 99.7% purity has been performed with mineral and organic acid prior to the synthesis of aluminum compounds from aluminum solution. Mean particle size of aluminum hydroxide used in the work was $14.4{\mu}m$, $22.9{\mu}m$ and $62.3{\mu}m$, respectively and the effect of reaction temperature, concentration of acid and reaction time on the dissolution of aluminum hydroxide has been examined. As a result, the dissolution of aluminum hydroxide was increased with the concentration of HCl and more than 70% dissolution was obtained with 5 mole/l HCl at $70^{\circ}C$ for reaction time of 4 hr. As far as the dissolution of aluminum hydroxide with sulfuric acid was concerned, it was found that the optimum concentration of sulfuric acid was about 6 mole/l for the effective dissolution of aluminum hydroxide. When oxalic acid was used for the dissolution of aluminum hydroxide, nearly complete dissolution could be obtained by the dissolution for 16 hr with 1.0 mole/l oxalic acid at $90^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.48 no.1
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• pp.72-76
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• 2016

We investigated the application of functional materials by examining a variety of physiological activities of Geranium krameri extract obtained from the National Institute of Horticultural and Herbal Science. Geranium krameri extract had a low cytotoxicity against murine melanoma B16F10 cells. At concentrations with little or no cytotoxicity, Geranium krameri extract showed high DPPH radical scavenging activity ($IC_{50}$, $8.72{\mu}g/mL$) and anti-microbial activities against Bacillus subtilis, Escherichia coli, and Candida albicans. Additionally, Geranium krameri extract inhibited tyrosinase activity ($IC_{50}$, $456.86{\mu}g/mL$) and decreased melanin content ($IC_{50}$, $50.35{\mu}g/mL$). The treatment of B16F10 cells with Geranium krameri extract suppressed the protein expression of tyrosinase in a dose-dependent manner. These findings suggest that Geranium krameri extract inhibits melanin synthesis in murine melanoma B16F10 cells by suppressing intracellular tyrosinase expression, as well as directly inhibits tyrosinase activity simultaneously.

• Korean Journal of Food Science and Technology
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• v.50 no.3
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• pp.344-348
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• 2018

We investigated the application of functional materials by examining a variety of physiological activities of Abelmoschus esculentus extract. A. esculentus extract had a low cytotoxicity against murine melanoma B16F10 cells. At concentrations showing little or no cytotoxicity, A. esculentus extract showed high a DPPH radical scavenging activity ($ID_{50}$, $5.24{\mu}g/mL$), inhibited tyrosinase activity ($ID_{50}$, $102.12{\mu}g/mL$), and decreased melanin content ($ID_{50}$, $17.85{\mu}g/mL$). The treatment of B16F10 cells with A. esculentus extract suppressed the protein expression of tyrosinase in a dose-dependent manner. These findings suggest that A. esculentus extract inhibits melanin synthesis in murine melanoma B16F10 cells by suppressing intracellular tyrosinase expression, as well as directly inhibits tyrosinase activity simultaneously. Additionally, A. esculentus extract promotes the expression of involucrin, which is related to skin barrier protection. These results indicate that A. esculentus extract is an appropriate material for improving skin barrier function.

• The Korea Journal of Herbology
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• v.28 no.3
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• pp.1-5
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• 2013

Objectives : This study was designed to investigate the collagen metabolism and tyrosinase activity of Polygonati Rhizoma extracts (PR). It's effects are to tonify spleen qi and augment the spleen yin. It enrichs the yin and moisten the lung. Methods : The effect of PR on type I procollagen production and collagenase (matrix metalloproteinase-1, henceforth referred as MMP-1) activity in human normal fibroblasts Hs68 after ultraviolet B (UVB, 312 nm) irradiation was measured by ELISA method. The tyrosinase activity after treatment of PR was measured. Results : There were no cytotoxicity at concentrations of 10, 30, $100{\mu}g/ml$. The reduced type I procollagen production was recovered by PR in UVB damaged Hs68 cells at a concentration of $100{\mu}g/ml$ ($16.2{\pm}0.0$ ng/ml) from control group ($13.9{\pm}0.5$ ng/ml). However there was no statistical significance. PR reduced The increased MMP-1 activity after UVB damage at concentrations of $10{\mu}g/ml$, $30{\mu}g/ml$, and $100{\mu}g/ml$ in a dose dependent manner ($42.2{\pm}20.5%$, $44.8{\pm}8.5%$, and $22.0{\pm}5.8%$). PR $100{\mu}g/ml$ treatment showed the statistical significace (p < 0.05). PR significantly reduced the tyrosinase activity at a concentration of 10 mg/ml ($32.0{\pm}12.8%$, p < 0.05). However, the L-DOPA oxidation was not changed. Conclusion : PR showed the anti-wrinkle effects and whitening effects in vitro. Although more researches are needed to validate the efficacy, these results suggest that PR may have potential as an anti-aging ingredient in cosmetic herb markets.

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1571-1576
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• 2012

A diarylurea compound 1 possessing pyrrolo[3,2-$c$]pyridine nucleus was designed and synthesized with structure similarity to Sorafenib. Compound 1 was tested over 60-cancer cell line panel at a single dose concentration of 10 ${\mu}M$ and showed high activity. It was further tested in a five-dose mode to determine its $IC_{50}$, TGI, and $LC_{50}$ values over the 60 cell lines. Compound 1 showed high potency and good efficacy, and was accordingly tested at a single dose concentration of 10 ${\mu}M$ over a panel of 40 kinases. At this concentration, it completely inhibited the enzymatic activities of a number of oncogenic kinases, including ABL, ALK, c-RAF, FLT3, KDR, and TrkB. The target compound was subsequently tested over these 6 kinases in 10-dose testing mode in order to determine its $IC_{50}$ values.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.454-459
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• 2004

This paper considers the problem of satellite's orbit control and a solution based in Linear Matrix Inequalities (LMI) is proposed for the case of Low Earth Orbiters (LEO). In particular, the modelling procedure and the algorithm for control law synthesis are tested using as study case the European Gravity Field and Ocean Circulation Explorer satellite (GOCE), to be launched by the European Space Agency (ESA) in the year 2006. The scientific objective of this space mission is the recovering of the Earth gravity field with high accuracy (less than 10${\mu}m$/${\mu}m$) and spatial resolution (better than 100km). In order to meet these scientific requirements, the orbit control must guarantee stringent specifications in terms of environmental disturbances attenuation (atmospheric drag forces) even in presence of high levels of model uncertainty.