• Journal of Digital Convergence
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• v.13 no.2
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• pp.401-406
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• 2015

The aim of present study is to investigate antioxidative effect of the Rice Bran Extracts and Defatted Rice Bran Extracts. Rice Bran Extracts used Rice Bran Water Extract, Rice Bran Ethanol Extract, Defatted Rice Bran Water Extract, Defatted Rice Bran Ethanol Extract. This study was carried out to examine quenching effects of Rice bran extracts on DPPH-, Riboflavin-, and Xanthin oxidase- originated superoxide activities. In addition, in order to determine whether Rice Bran Extract can be safely applied to human skin, the cytotoxic effects of Rice Bran Extract in Human Dermal Fibroblast cells were determined using MTS Assay. These results demonstrated that RBE and DRBE had anti-oxidative properties and did not induce the cytotoxic effects in Human Dermal Fibroblast cells. Therefore, these findings suggest that anti-oxidative properties of RBE and DRBE may be considered convergence with skin care.

• Journal of Nuclear Fuel Cycle and Waste Technology
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• v.1 no.1
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• pp.65-73
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• 2013

Temperature-dependent hydrolysis behaviors of aqueous U(VI) species were investigated with time-resolved laser fluorescence spectroscopy (TRLFS) in the temperature range from 15 to $75^{\circ}C$. The formation of four different U(VI) hydrolysis species was measured at pHs from 1 to 7. The predominant presence of $UO{_2}^{2+}$, $(UO_2)_2(OH){_2}^{2+}$, $(UO_2)_3(OH){_5}^+$, and $(UO_2)_3(OH){_7}^-$ species were identified based on the spectroscopic properties such as fluorescence wavelengths and fluorescence lifetimes. With an increasing temperature, a remarkable decrement in the fluorescence lifetime for all U(VI) hydrolysis species was observed, representing the dynamic quenching behavior. Furthermore, the increase in the fluorescence intensity of the further hydrolyzed U(VI) species was clearly observed at an elevated temperature, showing stronger hydrolysis reactions with increasing temperatures. The formation constants of the U(VI) hydrolysis species were calculated to be $log\;K{^0}_{2,2}=-4.0{\pm}0.6$ for $(UO_2)_2(OH){_2}^{2+}$, $log\;K{^0}_{3,5}=-15.0{\pm}0.3$ for $(UO_2)_3(OH){_5}^+$, and $log\;K{^0}_{3,7}=-27.7{\pm}0.7$ for $(UO_2)_3(OH){_7}^-$ at $25^{\circ}C$ and I = 0 M. The specific ion interaction theory (SIT) was applied for the extrapolation of the formation constants to infinitely diluted solution. The results of temperature-dependent hydrolysis behavior in terms of the U(VI) fluorescence were compared and validated with those obtained using computational methods (DQUANT and constant enthalpy equation). Both results matched well with each other. The reaction enthalpies and entropies that are vital for the computational methods were determined by a combination of the van't Hoff equation and the Gibbs free energy equation. The temperature-dependent hydrolysis reaction of the U(VI) species indicates the transition of a major U(VI) species by means of geothermal gradient and decay heat from the radioactive isotopes, representing the necessity of deeper consideration in the safety assessment of geologic repository.

• Journal of the Korean Chemical Society
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• v.55 no.6
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• pp.932-935
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• 2011

Using tetrabutyl titanate as precursor, $Eu^{3+}$ doped $TiO_2$ nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with $Eu^{3+}$ doped $TiO_2$ was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was quenched by chlorpyrifos and the quenching rate constant ($k_q$) was $1.24{\times}10^{11}\;L/mol{\cdot}s$ according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of $TiO_2$ nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (${\Delta}G_{et}$) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of $Eu^{3+}$ doped $TiO_2$ was proportional to chlorpyrifos concentration. The range of detection was $5.0{\times}10^{-10}-2.5{\times}10^{-7}mol/L$ and the election limit ($3{\sigma}$) was $3.2{\times}10^{-11}$ mol/L.

• Journal of IKEEE
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• v.28 no.2
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• pp.174-179
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• 2024

In this work, we introduce a complementary metal-oxide semiconductor(CMOS)-based integrated circuit(IC) measurement set-up for quantum computer control and read-out using a cryogenic refrigerator. CMOS circuits have to operate at extremely low temperatures of 3 to 5 K for qubit stability and noise reduction. The existing cryogenic measurement system is liquid helium quenching, which is expensive due to the long-term use of expendable resources. Therefore, we describe a cryogenic measurement system based on a closed cycle refrigerator (CCR) that is cost-free even when using helium gas for long periods of time. The refrigerator capable of reaching 4.7 K was built using a Gifford-Mcmahon(G-M) type cryocooler. This is expected to be a cryogenic refrigerator set-up with excellent price competitiveness.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.4
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• pp.309-320
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• 2017

In this study, the antioxidative effects and component analysis of 50% ethanol extract, ethyl acetate fraction and aglycone fraction obtained from Annona muricata leaf were investigated. Free radical scavenging activities were performed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, total antioxidant capacities were estimated using luminol-dependent chemiluminescence assay and $^1O_2$ quenching effects were estimated. Free radical scavenging activities ($FSC_{50}$) of 50% ethanol extract, ethyl acetate fraction and aglycone fraction were 45.6, 29.8 and $18.0{\mu}g/mL$, and total antioxidant capacities ($OSC_{50}$) were 4.4, 1.1 and $2.8{\mu}g/mL$, respectively. As a result of $^1O_2$ quenching experiment, ethyl acetate and aglycone fraction showed similar activities to L-ascorbic acid used as a comparative control. The cellular protective effects of 50% ethanol extract on the $^1O_2-induced$ cellular damage of human erythrocytes were exhibited at concentration-dependent ($5-50{\mu}g/mL$). TLC and HPLC were used to analyse components in the ethyl acetate fraction and aglycone fraction of Annona muricata leaf. In ethyl acetate fraction, rutin (quercetin-3-O-rutinoside), kaempferol-3-O-neohesperidoside, nicotiflorin (kaempferol-3-O-rutinoside), p-coumaric acid were identified. In aglycone fraction, kaempferol was identified. These results suggest that the extracts of Annona muricata leaf have the applicability as antioxidant cosmeceutical ingredients.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.177-183
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• 2013

In this study, the antioxidative activities and component analysis of Broussonetia kazinoki SIEB (B. kazinoki). extracts were investigated. B. kazinoki extract showed the effective free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}=8.53{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activity ($OSC_{50}$) of the ethyl acetate fraction of B. kazinoki. extracts in the luminol-dependent $Fe^{3+}-EDTA/H_2O_2$ system was $1.69{\mu}g/mL$. The ethyl acetate fraction of B. kazinoki. extracts also exhibited more prominent cellular protective effects (${\tau}_{50}$, 183.3 min at $10{\mu}g/mL$) than that of typical antioxidant $\alpha$-tocopherol (${\tau}_{50}$ = 38.00 min) in the $^1O_2$-induced photohemolysis of human erythrocytes. Components of the ethyl acetate fraction obtained from B. kazinoki extracts were analyzed by TLC, HPLC chromatogram, LC/ESI-MS/MS and $^1H$-NMR. Consequently, Components, components were identified as the kazinol J of kazinol series and luteolin (2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-chromenone) of flavonoid series having antioxidant activities. These results indicate that extract/ fraction of B. kazinoki can be used as antioxidants in biological systems, particularly skins exposed to UV radiation by quenching and/or scavenging $^1O_2$ and other ROS, and protecting cellular membranes against ROS. Thus, the extract/fraction of B. kazinoki could be applicable to new cosmeceuticals.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.3
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• pp.265-273
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• 2011

In this study, the antioxidative and inhibitory effects on tyrosinase and elastase of Hippophae rhamnoides (H. rhamnoides) leaf extracts were investigated. The ethyl acetate fraction of H. rhamnoides extracts showed more effective free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}$ = 4.68 ${\mu}g$/mL). Reactive oxygen species (ROS) scavenging activity ($OSC_{50}$) of the aglycone fraction in the luminol-dependent $Fe^{3+}$-EDTA/$H_2O_2$ system was 0.19 ${\mu}g$/mL. The aglycone fraction exhibited more prominent cellular protective effects (${\tau}_{50}$, 133.3 min at 10 ${\mu}g$/mL) in the $^1O_2$-induced photohemolysis of human erythrocytes. The inhibitory effect ($IC_{50}$) of the aglycone fraction on tyrosinase was 54.86 ${\mu}g$/mL, and more effective than arbutin known as whitening agent. These results indicate that fractions of Hippophae rhamnoides extract can be used as antioxidants in biological system, particulaly skin exposed to UV radiation by quenching and/or scavenging $^1O_2$ and other ROS, and protecting cellular membranes against ROS.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.2
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• pp.215-223
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• 2018

Intracellular $Ca^{2+}$ mobilization is closely linked with the initiation of salivary secretion in parotid acinar cells. Reactive oxygen species (ROS) are known to be related to a variety of oxidative stress-induced cellular disorders and believed to be involved in salivary impairments. In this study, we investigated the underlying mechanism of hydrogen peroxide ($H_2O_2$) on cytosolic $Ca^{2+}$ accumulation in mouse parotid acinar cells. Intracellular $Ca^{2+}$ levels were slowly elevated when $1mM\;H_2O_2$ was perfused in the presence of normal extracellular $Ca^{2+}$. In a $Ca^{2+}-free$ medium, $1mM\;H_2O_2$ still enhanced the intracellular $Ca^{2+}$ level. $Ca^{2+}$ entry tested using manganese quenching technique was not affected by perfusion of $1mM\;H_2O_2$. On the other hand, $10mM\;H_2O_2$ induced more rapid $Ca^{2+}$ accumulation and facilitated $Ca^{2+}$ entry from extracellular fluid. $Ca^{2+}$ refill into intracellular $Ca^{2+}$ store and inositol 1,4,5-trisphosphate ($1{\mu}M$)-induced $Ca^{2+}$ release from $Ca^{2+}$ store was not affected by $1mM\;H_2O_2$ in permeabilized cells. $Ca^{2+}$ efflux through plasma membrane $Ca^{2+}-ATPase$ (PMCA) was markedly blocked by $1mM\;H_2O_2$ in thapsigargin-treated intact acinar cells. Antioxidants, either catalase or dithiothreitol, completely protected $H_2O_2-induced$ $Ca^{2+}$ accumulation through PMCA inactivation. From the above results, we suggest that excessive production of $H_2O_2$ under pathological conditions may lead to cytosolic $Ca^{2+}$ accumulation and that the primary mechanism of $H_2O_2-induced$ $Ca^{2+}$ accumulation is likely to inhibit $Ca^{2+}$ efflux through PMCA rather than mobilize $Ca^{2+}$ ions from extracellular medium or intracellular stores in mouse parotid acinar cells.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.181-189
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• 2012

We developed a new high-yield synthesis method of free-standing germanium nanocrystals (Ge NCs) by means of the gas-phase photolysis of tetramethyl germanium in a closed reactor using an Nd-YAG pulsed laser. Size control (5-100 nm) can be simply achieved using a quenching gas. The $Ge_{1-x}Si_x$ NCs were synthesized by the photolysis of a tetramethyl silicon gas mixture and their composition was controlled by the partial pressure of precursors. The as-grown NCs are sheathed with thin (1-2 nm) carbon layers, and well dispersed to form a stable colloidal solution. Both Ge NC and Ge-RGO hybrids exhibit excellent cycling performance and high capacity of the lithium ion battery (800 and 1100 mAh/g after 50 cycles, respectively) as promising anode materials for the development of high-performance lithium batteries. This novel synthesis method of Ge NCs is expected to contribute to expand their applications in high-performance energy conversion systems.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1661-1666
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• 1999

Yungmijihwgang-Won, Yollyunggobon-Dan and Palmi-Hwan, Korea traditional prescriptions composed of oriental medical herbs, have been used successfully to improve human health and regimen. This study was designed to examine the mechanism of healthful effects of the Korea traditional prescriptions through its antioxidative potentials. Using in vitro antioxidative activity assay system such as DPPH radical quenching assay, superoxide anion radical scavenging assay and inhibition of TBARS production, three Korea traditional prescriptions were observed to have nearly the same antioxidative potentials as ascorbic acid, a well-known strong water-soluble antioxidant. Moreover, we observed reinforced antioxidative effects of these drugs in liver from mouse fed these drugs with 4 weeks. When liver homogenate was incubated with 2.2'-azobis(amidinopropane) dihydrochloride(AAPH), as a free radical initiator, we observed that oxidative damages were decreased and antioxidative potentials were increased in liver homogenate treated these drugs. However, enzymatic antioxidative system as superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase was not affected by drug administration.