• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.1013-1016
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• 1995

The color stability of betacyanins and effects of antioxidants from Opuntia dillenii Haw were determined in the fruit juice at temperature up to $90^{\circ}C$. The absorption maxima of betacyanins occurred between 536 nm and 538 nm. When fruit juice was heated at $90^{\circ}C$ for various times, the red color gradually diminished and the absorption maxima slightly shifted toward uv region. The kinetic analysis of the data obtained indicated that the discoloration for betacyanins obeyed first order reaction pattern, when the thermal stability test was performed at $50{\sim}90^{\circ}C$. And the rate constant increased from $1.56{\times}10^{-3}/min\;to\;71.91{\times}10^{-3}/min$ with the half-life decreasing from 444.23 min to 9.64 min. The results also indicated that the thermal stability of pigment decreased with increasing temperature. The energy of activation was 10.94 kcal/mole for the pigment. N-propyl gallate, L-cysteine, and ascorbic acid were added to cactus fruit juice at concentrations of $0.01{\sim}0.3%$ at different temperatures. Npropyl gallate and L-cysteine had a little antioxidant effect on betacyanins stability at $50^{\circ}C\;and\;70^{\circ}C$, whereas ascorbic acid had a great antioxidant effect with the half-life value of 2 to 10 times to that of the control.

• Journal of Electrochemical Science and Technology
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• v.9 no.4
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• pp.282-291
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• 2018

The pristine fluorine-doped $SnO_2$ (abbreviated as FTO) inverse opal (IO) was developed using a 410 nm polystyrene bead template. The nanolayered copper tungsten oxide ($CuWO_4$) was decorated on the FTO IO film using a facile electrochemical deposition, subsequently followed by annealing at $500^{\circ}C$ for 90 min. The morphologies, crystalline structure, optical properties and photoelectrochemical characteristics of the FTO and $CuWO_4$-decorated FTO (briefly denoted as $FTO/CuWO_4$) IO film were investigated by field emission scanning electron microscopy, X-ray diffraction, UV-vis spectroscopy and electrochemical impedance spectroscopy, showing FTO IO in the hexagonally closed-pack arrangement with a pore diameter and wall thickness of about 300 nm and 20 nm, respectively. Above this film, the $CuWO_4$ was electrodeposited by controlling the cycling number in cyclic voltammetry, suggesting that the $CuWO_4$ formed during 4 cycles (abbreviated as $CuWO_4$(4 cycles)) on FTO IO film exhibited partial distribution of $CuWO_4$ nanoparticles. Additional distribution of $CuWO_4$ nanoparticles was observed in the case of $FTO/CuWO_4$(8 cycles) IO film. The $CuWO_4$ layer exhibits triclinic structure with an indirect band gap of approximately 2.5 eV and shows the enhanced visible light absorption. The photoelectrochemical (PEC) behavior was evaluated in the 0.5 M $Na_2SO_4$ solution under solar illumination, suggesting that the $FTO/CuWO_4$(4 cycles) IO films exhibit a photocurrent density ($J_{sc}$) of $0.42mA/cm^2$ at 1.23 V vs. reversible hydrogen electrode (RHE, denoted as $V_{RHE}$), while the FTO IO and $FTO/CuWO_4$(8 cycles) IO films exhibited a $J_{sc}$ of 0.14 and $0.24mA/cm^2$ at $1.23V_{RHE}$, respectively. This difference can be explained by the increased visible light absorption by the $CuWO_4$ layer and the favorable charge separation/transfer event in the cascading band alignment between FTO and $CuWO_4$ layer, enhancing the overall PEC performance.

• Journal of Microbiology
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• v.41 no.3
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• pp.196-201
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• 2003

The object of this study was to characterize Bacillus strains GB-017 and GB-0356, which produce antifungal substances, especially for plant pathogens. In addition, this study was undertaken to characterize the culture conditions required for the production of antifungal substances and to document some of the properties of the antifungal substance produced by these soil-isolated strains. Strains GB-0365 and GB-017 were found to be bacillus-shaped, gram-positive and motile, and to inhibit Botrytis cineria, Fusarium sp., Pythium sp., and Rhizoctonia solani. Antagonistic activity was maintained up to pH 9.0, and the antifungal activity was stable to heat at 80$^{\circ}C$ for 1 h. Antifungal substances were separated and purified using ion exchange and adsorption columns including WK-I0(H$\^$＋) (pH 7.0), HP20 column (pH 3.0) and IPA (pH 3.0). and IPA. Its UV absorption spectrum showed major peaks at 231 and 259 nm, corresponding to polyene and lactone. A fast atom bombardment mass spectrum (FAB MS) showed a highest peak at 441 m/z and major peaks at 192, 205, and 370 m/z.

• Korean Journal of Materials Research
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• v.24 no.10
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• pp.556-564
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• 2014

To synthesize a high-performance photocatalyst, N doped $TiO_2$ nanotubes deposited with Ag nanoparticles were synthesized, and surface characteristics, electrochemical behaviors, and photocatalytic activity were investigated. The $TiO_2$ nanotubular photocatalyst was fabricated by anodization; the Ag nanoparticles on the $TiO_2$ nanotubes were synthesized by a reduction reaction in $AgNO_3$ solution under UV irradiation. The XPS results of the N doped $TiO_2$ nanotubes showed that the incorporated nitrogen ions were located in interstitial sites of the $TiO_2$ crystal structure. The N doped titania nanotubes exhibited a high dye degradation rate, which is effectively attributable to the increase of visible light absorption due to interstitial nitrogen ions in the crystalline $TiO_2$ structure. Moreover, the precipitated Ag particles on the titania nanotubes led to a decrease in the rate of electron-hole recombination; the photocurrent of this electrode was higher than that of the pure titania electrode. From electrochemical and dye degradation results, the photocurrent and photocatalytic efficiency were found to have been significantly affected by N doping and the deposition of Ag particles.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.23 no.3
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• pp.101-107
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• 1997

Phellinus linteus was artificially cultivated in kangwon province in Korea. The air-dried phellinus linteus was frozen in liquid nitrogen tank and powdered in jar. 10g of the powder was extracted with each 200g of ethanol, methanol, distilled water and 1,3-butylene glycol/distilled water 4 hours under refluxing and then the liquidextract was concentrated under reduced pressure. As a result of analysis by high performance liquid chromatography and thin layer chromarography, many kinds of sugar and flavonoids were detected. Also we knew that phellinus linteus' extract had a strong UV-ray absorption. In the efficacy test for applying to cosmetics, free radical scavenging effect was confirmed. As a result, 2% of sample was the most potent inhibitory effect and the free radical savenging activity, was 0.31%. This is more effective than any other meterial. In the test of antioxidative activity against lipid autoxidation, phellinus linteus' extract had a good effect by 46% while vitamine E was 42.3%. The immunological activity of phellinus linteus was showed through the activation of macrophage cell. Actually, phellinus linteus activated macrophage function of 1.1-1.8 times including nitrite production compared to control. The whitening effect of phellinus linteus was showed through the inhibition of tyrosinase activity, melanin biosynthesis of S. bikiniensis and B-16 melanoma cells. Phellinus linteus' extract was showed strong mushroom tyrosinase inhibitory activity with IC50 value of 0.5% and inhibited melanin biosynthesis with 28mm inhibition zone at 0.005%/paper disc in S. bikinniensis, a bacterium used as an indicator organism in this work. Also it inhibited melanin biosynthesis in B-16 melanoma cells with a minimum inhibitory concentration of 0.134%.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1669-1678
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• 2011

Six new binuclear copper(II) complexes have been prepared by template condensation of the dialdehydes 1,8-[bis(3-formyl-2-hydroxy-5-methyl)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-a) and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-l,4,8,11-tetraazacyclotetradecane (PC-b) with appropriate aliphatic diamines, and copper(II) perchlorate. The structural features of the complexes have been confirmed by elemental analysis, IR, UV-vis and mass spectra etc. The electrochemical behavior of all the copper(II) complexes show two irreversible one electron reduction process. The room temperature magnetic moment studies depict the presence of an antiferromagnetic interaction in the binuclear complexes. The catechol oxidation and hydrolysis of 4-nitrophenylphosphate were carried out by using the complexes as catalyst. The antimicrobial screening data show good results. The binding of the complexes to calf thymus DNA (CT DNA) has been investigated with absorption and emission spectroscopy. The complex [$Cu_2L^{1a}$] displays significant cleavage property of circular plasmid pBR322 DNA in to linear form. Spectral, electrochemical, magnetic and catalytic studies support the distortion of the copper ion geometry that arises as the macrocyclic ring size increases.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.2
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• pp.65-69
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• 2011

The $Tio_2$ films were prepared on glass, silicon and quartz substrate at different temperature by radio frequency reactive magnetron sputtering under different flow ratios of Ar and O2 gases. The films were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and UV-VIS spectrophotometer. Only the anatase phase was observed in films and their diffaction peaks increased with temprature of substrate. The size of crystallites decreased with higher concentration of oxygen. Refractive index and optical absorption of thin films decreased with higher concentration of oxygen. The thin films which have good transmittance spectra and smooth surface, deposited in the sputtering ambient with 10 % of $O_2$ at the temperature from $400{\circ}C$ to $300{\circ}C$.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.701-705
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• 2014

Water extracts of root, leaf, branch and fruit of Cudrania tricuspidata were tested to use as natural antiwrinkle and whitening cosmetic ingredient. Root extract indicated 86.5 mg/g polyphenol concentration and 55.5 mg/g flavonoid concentration. From MTT test, root, branch and fruit extract did not show cell toxicity up to $1,000{\mu}g/mL$, however, leaf extract displayed significant cell toxicity in concentrations higher than $200{\mu}g/mL$. Cudrania tricuspidata root extracts displayed excellent 81% tyrosinase inhibition (whitening effect), 58% elastase inhibition (antiwrinkle effect) at $500{\mu}g/mL$ and showed minor UVB absorbance. When solution and lotion formulation were made including Cudrania tricuspidata root extract, they are stable at $25^{\circ}C$ for 21 days, but showed significant deviation in viscosity and particle size at $47^{\circ}C$. From the study, Cudrania tricuspidata root extract demonstrated good potential for natural whitening and antiwrinkle cosmetic agent.

• Composites Research
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• v.31 no.3
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• pp.83-87
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• 2018

An object in the Low Earth Orbit (LEO) is affected by many environmental conditions unlike earth's surface such as, Atomic oxygen (AO), Ultraviolet Radiation (UV), thermal cycling, High Vacuum and Micrometeoroids and Orbital Debris (MMOD) impacts. The effect of all these parameters have to be carefully considered when designing a space structure, as it could be very critical for a space mission. Polybenzimidazole (PBI) is a high performance thermoplastic polymer that could be a suitable material for space missions because of its excellent resistance to these environmental factors. A thin coating of PBI polymer on the carbon epoxy composite laminate (referred as CFRP) was found to improve the energy absorption capability of the laminate in event of a hypervelocity impact. However, the overall efficiency of the shield also depends on other factors like placement and orientation of the laminates, standoff distances and the number of shielding layers. This paper studies the effectiveness of using a PBI coating on the front bumper in a multi-shock shield design for enhanced hypervelocity impact resistance. A thin PBI coating of 43 micron was observed to improve the shielding efficiency of the CFRP laminate by 22.06% when exposed to LEO environment conditions in a simulation chamber. To study the effectiveness of PBI coating in a hypervelocity impact situation, experiments were conducted on the CFRP and the PBI coated CFRP laminates with projectile velocities between 2.2 to 3.2 km/s. It was observed that the mass loss of the CFRP laminates decreased 7% when coated by a thin layer of PBI. However, the study of mass loss and damage area on a witness plate showed CFRP case to have better shielding efficiency than PBI coated CFRP laminate case. Therefore, it is recommended that PBI coating on the front bumper is not so effective in improving the overall hypervelocity impact resistance of the space structure.

• Journal of Conservation Science
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• v.31 no.3
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• pp.299-308
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• 2015

Aim of this study is to identify dyestuff of the Dallryeong(official's robe in Joseon Dynasty, 16th century) excavated from Yuryang-dong, Cheonan, in 1996. For this purpose, extracted dyestuffs from Dallryeong fabric and from natural dyestuffs for red color(safflower, Sapanwood, Madder) which are presumed to have been used in the Dallryeong, are analyzed and compared by high performance liquid chromatography(HPLC). As a result, HPLC chromatogram of extracts of the Dallryeong's dyestuff and safflower are showed a peak at 17.5 minutes. The UV/Vis spectra of the samples are showed the maximum absorption wavelength at 519nm. This result is identical with the analysis of the previous studies on red dyestuff of safflower. In addition, the analysis of Mass Spectrometry(MS) showed the identical result of the peak with m/z 910. Following these results, excavated pink Dallryeong were considered to have been dyed with safflower.