• Korean Journal of Food Science and Technology
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• v.49 no.6
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• pp.714-716
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• 2017

Rose flower is widely used in the preparation of tea and contains a large variety of phytochemicals, including phenolics such as catechin, quercetin, and rutin. The effects of aging on rose (Rosa hybrida L.) flower extracts (RFE) were examined under conditions of varying temperature and relative humidity. The total phenolic content, antioxidative activity, and catechin levels were measured to evaluate the effects of temperature and relative humidity on the aging process. Performing the aging process at $30^{\circ}C$ under 60% or 90% relative humidity for 24 h significantly increased the total phenolic content and the antioxidant activities of RFE (p<0.05). Additionally, an aging process performed at $30^{\circ}C$ and 60% relative humidity for 24 h maximized the extraction rate of phenolics such as catechin and consequently led to increased antioxidative activity of RFE. In summary, this study indicates that the extraction rate of physiologically active phenolic compounds in rose flower can be increased by performing an aging process under optimized temperature and relative humidity conditions.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.554-560
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• 2012

Recently, it has been increasing trend to use conductive materials as electronics and communication technology in electronics industry are developing. The noble metal such as Ag, Pt, Pd etc. are mostly used as conductive materials, To reduce production cost, alternative materials with similar characteristics of noble metals are needed. Copper has advantages, i.e its electronic properties are similar to noble metals and low cost than noble metal, but its use has been restricted because of oxidation in air. In this study, the tin film was coated on copper by electroless plating to protect copper from oxidation and to confirm the effects of temperature, pH, amount of $SnCl_2$, and feeding speed in plating conditions. Additionally, we apply $Cu_{core}Sn_{shell}$ powder as conductive filler with low-temperature densification and analysis by SEM, XRD, FIB and 4-Point Probe techniques. As result of the study, tin film was coated well on copper and was protected from oxidation. After low-temperature densification treatment, the meted tin made chemical interconnections with copper. Accordingly, conductivity was increased than before condition. We hope $Cu_{core}Sn_{shell}$ powder to replace noble metals and use in the electronic field.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.486-491
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• 2019

Phenolic compounds and antioxidant activities of ethanol extracts from barley sprouts were evaluated in this study. Barley sprouts were extracted using water and ethanol in various concentration (25, 50, and 75%) using reflux extraction methods. Ultra performance liquid chromatography (UPLC) analysis showed that barley sprouts are mainly composed of rutin, gallic acid, ferulic acid, and ${\rho}$-coumaric acid. The 75% ethanol extracts had higher total polyphenol contents ($44.01{\pm}1.32mg/g$) and total flavonoid contents ($102.96{\pm}2.49mg/g$). 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity ($EC_{50}$ value: $1.65{\pm}0.02mg/mL$) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging activity ($EC_{50}$ value: $1.67{\pm}0.02mg/mL$) of the 75% ethanol extracts of barley sprouts were found to be the most effective. The 75% ethanol extracts of barley sprouts exhibited a strong reducing activity and ferric reducing antioxidant activity. As a result, the 75% ethanol extracts of barley sprouts showed stronger antioxidant activity than other extracts.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.3
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• pp.67-86
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• 1999

Ascorbic acid which has various physiological benefits as the functional substance is easily oxidized and destroyed by the structural instability. Liposome encapsulated pure ascorbic acid was prepared for the sake of the constraint of oxidation. The influence of cholestrol or $\beta$-sitosterol on the stabilization of liposome was investigated. Butylated hydroxytoluene(BHT), tertiary butylhydroquinone(TBHQ), $\alpha$ -glycosyl rutin and natural concentrated tocopherol were used for constraint of oxidation of ascorbic acid. The presence of cholesterol or $\beta$-sitosterol decreased oxidation of ascorbic acid. That results were thought that cholesterol or $\beta$-sitosterol so increased rigidity of bilayer that the leakage of vitamin C decreased. As a result the oxidation and degradation of vitamin C were constrained. At 0.3w/w% cholesterol content the most stable liposome was formulated. The whole antioxidant that used at the research constrained oxidation of ascorbic acid. The antioxidation for ascorbic acid increased in order of tertiary butylhydroquinone, $\alpha$-glycosyl rutin, butylated hydroxytoluene and natural concentrated tocopherol. But u -glycosyl rutin is preferable to tertiary butylhydroquinone which was the most effective in antioxidation as the antioxidant of ascorbic acid which was utilized in cosmetics and pharmacy.

• Journal of Korean Association for Spatial Structures
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• v.6 no.4 s.22
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• pp.73-80
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• 2006

It is an object of the present paper to investigate a electrochemical properties of Mg-based sacrificial anodes and the effect of calcium added from calcium chloride into magnesium on the melt protection during the melting. Electrochemical data will be correlated with processing control variables, and the microstructural change by the addition of CaCl2. Small addition of calcium into magnesium from CaCl2 imparts beneficial effect in electrochemical properties of Mg alloys, primarily, through microstructural modifications. In addition, the protection effect of the melts surface of Ca with low melting point modification is obtained by adding Ca not more than 0.6%.

• Korean Journal of Food Science and Technology
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• v.48 no.3
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• pp.284-288
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• 2016

To investigate the physiological effect of Hibiscus sabdariffa, in vitro antioxidant activities and neuroprotective effects against high glucose-induced oxidative stress were examined. The ethyl acetate fraction (EtOAc-Fr) from H. sabdariffa contained high total phenolic contents compared with other fractions but total anthocyanin contents were lower than 80% Ethanol extract showed the highest 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging activity and malondialdehyde inhibitory effect. Furthermore, the EtOAc-Fr decreased the intracellular reactive oxygen species level, and protected the neuron-like PC12 cells from high glucose-induced cytotoxicity. The EtOAc-Fr also presented inhibitory effects against acetylcholinesterase as an acetylcholine hydrolase enzyme. Finally, chlorogenic acids as main phenolics by high performance liquid chromatography analysis.

• Journal of the Korean Magnetics Society
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• v.12 no.4
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• pp.127-131
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• 2002

We fabricated MTJ devices that have doubly oxidized tunnel barrier using plasma oxidation method to from oxidized AlO$\sub$x/ tunnel barrier. Doubly oxidation I, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it with oxidation time of 10 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 50, 80 and 120 s., respectively. Doubly oxidation II, which sputtered 10 ${\AA}$-bottom Al layer and oxidized it varying oxidation time for 30∼120 s. Subsequent sputtering of 13 ${\AA}$-Al was performed and the metallic layer was oxidized for 210 sec. Double oxidation process specimen showed MR ratio of above 27％ in all experiment range. Singly oxidation process. 13 ${\AA}$-Al layer and oxidized up to 210 s, showed less MR ratio and more narrow process window than those of doubly oxidation. Cross-sectional TEM images would that doubly oxidized barrowers were thinner and denser than singly oxidized ones. XPS characterization confirmed that doubly oxidation of Fe with bottom insulating layer. As a result, doubly oxidation could have superior MR ratio in process extent during long oxidation time because of preventing oxidation of bottom magnetic layer than singly oxidation.

• Korean Journal of Food Science and Technology
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• v.23 no.5
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• pp.578-581
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• 1991

The antioxidative effects of three kinds of commercial lecithin in fish oil(EPA 25%, DHA 10%) were investigated through active oxygen method (AOM, hrs. at $97.8^{\circ}C$), Oven test, polymer test by gel chromatography and coloring test. Although there were difference of antioxidative effect among commercial lecithins, antioxidative effects of the lecithins added to the fish oil increased with increasing the concentration of lecithin. Lecithin III(acetone insoluble content 65%) had the greatest antioxidative effect and the addition of 1%, 5 and 10% enhanced the oxidative stability to 310%, 620% and 840%, respectively. The results also showed that the polymerization in presence of 10% lecithin III did not occur up to 10 hours at the AOM condition, and the degree of color(Gardner number) increased as storage time went by and was accerated at high temperature.

• Korean Journal of Food Science and Technology
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• v.23 no.3
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• pp.251-255
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• 1991

The antioxidative effects of the six commercial lecithins, tocopherols, citric acid and ascorbyl palmitate on refined perilla oil were inverstigated by active oxygen method ($AOM,\;hrs\;at\;97.8^{\circ}C$) and oven test. Except for the lecithin I (aceton insoluble content 55%), the induction time on perilla oil treated with commercial lecithins at 5% level was longer than that of refined soybean oil. When the concentration of lecithin (0.5, 1, 2.5, 4 and 5%) in perilla oil was increased, enhanced the antioxidative effect at AOM and oven test. Lecithin also showed synergistic effect with the mixtures of tocopherol, citric acid and ascorbyl palmitate. The antioxidative effect of ${\gamma}-rich-tocopherol$ on perilla was higher than that of ${\dalta}-rich-tocopherol$ or mixed tocopherol.

• Korean Journal of Food Science and Technology
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• v.49 no.3
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• pp.296-303
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• 2017

Curcuma powder, having a significantly higher electron donating ability than glutinous rice flour (p<0.001), was added into hwajeon at 0-5% concentrations. There was no significant difference in the moisture content of hwajeon depending on the curcuma content, which was attributed to a similar water-holding capacity of curcuma powder and glutinous rice flour when subjected to hot water. As the curcuma content increased, the redness of dough and hwajeon increased, and the lightness of hwajeon decreased to a higher degree than that of dough. With the addition of curcuma, hardness of hwajeon increased and its adhesiveness decreased, presumably due to the increased content of amylose relative to amylopectin. Sensory evaluation revealed that the strong flavor of curcuma was a negative determinant of the preference for hwajeon. Nevertheless, total reducing capacity and 2.2'-diphenyl-1-picrylhydrazyl radical scavenging activity increased in proportion to the curcuma content in hwajeon (p<0.001).