• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.103-106
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• 2002

A new reaction mechanism is proposed for the reaction of thianthrene cation radical perchlorate $(Th^{+{\cdot}}CIO_4^-}$ and tert-butyl peroxide in acetonitrile at room temperature on the basis of experimental and theoretical results. Rapid C-O bond rupture instead of O-O bond cleavage was observed by a good peroxy radical trapping agent, thianthrene cation radical. Products were N-tert-butyl acetamide, thianthrene 5-oxide (ThO), thianthrene 5,5-dioxide $(SSO_2)$, and thianthrene (Th). Thianthrene 5,10-dioxide (SOSO) was not obtained. A comparative computational study of the cation radical of tert-butyl peroxide is made by using B3LYP and CBS-4. The computational results are helpful to explain the reaction mechanism.

• 조명전기설비학회논문지
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• 제27권7호
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• pp.45-51
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• 2013

This study is to discuss simulation results with 51 principal chemical reactions in non-thermal plasma space under atmospheric pressure, and the ambient gas was mainly composed of oxygen and nitrogen molecules. The initial density of O and OH radicals under the ambient temperature of 300K is largely generated in comparison with other higher temperature, and the density of O radical decreased from $20{\mu}s$ according to increase the temperature. The initial density of OH radical seemed to decrease steeply at the initial stage. By increasing the initial density of $H_2O$ molecules, O radical's effect was few and the density of OH radical was largely generated about 2 times. In addition, ozone density was increased as increasing the density of O radical, but it was decreased as increasing the density of $H_2O$. In case of the temperature more than 300K, $NO_2$ tend to be removed, but NO was increased than the initial density.

• 한국물환경학회지
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• 제28권2호
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• pp.219-223
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• 2012

The fixed solid catalysts such as glass bead, steel mesh, and $TiO_2$ coated ceramic bead were used to investigate effect of radical production at different frequencies. The radical production rate at 300 kHz was faster than that at 35 kHz without solid, but the tendency was changed with the presence of glass bead. The presence of glass beads create non-continuous points between the solid and liquid phases leading to increased formation of cavitation bubbles. However, the radical production decreased when steel mesh was used at 35 kHz although the surface area of contact with liquid was same when glass bead was used. Hence the solid catalyst did not always enhance the radical production. The radical production using $TiO_2$ coated ceramic bead was dramatically increased at 35 kHz due to the breakage of $TiO_2$ coated ceramic bead. Therefore the radical productions at 300 kHz using fixed solid catalysts generally increased while at 35 kHz the results fluctuated according to the experimental conditions.

• 한국환경과학회지
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• 제20권7호
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• pp.891-898
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• 2011

The aim of this research was to evaluate the effect of combination of disinfection process (electrolysis, UV process) on Escherichia coli (E. coli) disinfection and oxidants (OH radical, $ClO_2$, HOCl, $H_2O_2$ and $O_3$) generation. The effect of electrolyte type (NaCl, KCl and $Na_2SO_4$) on the E. coli disinfection and oxidants generation were evaluated. The experimental results showed that performance of E. coli disinfection of electrolysis and UV single process was similar. Combination of electrolysis and UV process enhanced the E. coli disinfection and 4-carboxybenzaldehyde (4-CBA, indicator of the generation of OH radical) degradation. It is clearly showed synergy effect on disinfection and OH radical formation. However chlorine ($ClO_2$, HOCl) and oxygen type ($H_2O_2$, $O_3$) oxidants were decreased with the combination of two process. In electrolysis + UV complex process, electro-generated $H_2O_2$ and $O_3$ were reacted with UV light of UV-C lamp and increased 4-CBA degradation(increase OH radical). Disinfection of electrolyte of chlorine type was higher than that of the sulfate type electrolyte due to the higher generation of OH radical and oxidants.

• BMB Reports
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• 제43권3호
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• pp.219-224
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• 2010

Lipid peroxidation is known to be an important factor in the pathologies of many diseases associated with oxidative stress. We assessed the lipid peroxidation induced by the reaction of ferritin with $H_2O_2$. When linoleic acid micelles or phosphatidyl choline liposomes were incubated with ferritin and $H_2O_2$, lipid peroxidation increased in the presence of ferritin and $H_2O_2$ in a concentration-dependent manner. The hydroxyl radical scavengers, azide and thiourea, prevented lipid peroxidation induced by the ferritin/$H_2O_2$ system. The iron specific chelator desferoxamine also prevented ferritin/$H_2O_2$ systemmediated lipid peroxidation. These results demonstrate the possible role of iron in ferritin/$H_2O_2$ system-mediated lipid peroxidation. Carnosine is involved in many cellular defense processes, including free radical detoxification. In this study, carnosine, homocarnosine, and anserine were shown to significantly prevent ferritin/$H_2O_2$ system-mediated lipid peroxidation and also inhibited the free radical-generation activity of ferritin. These results indicated that carnosine and related compounds may prevent ferritin/$H_2O_2$ system-mediated lipid peroxidation via free radical scavenging.

• 접착 및 계면
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• 제2권2호
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• pp.11-19
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• 2001

트리카프릴메틸 암모니움 클로라이드를 상이동촉매로 사용하여 $Na_2S_2O_8$의 수용액과 톨루엔의 이상계에서 질소분위기하에 $60^{\circ}C$에서 스티렌의 라디칼중합을 행하였다. 중합시의 초기 중합속도는 촉매와 $Na_2S_2O_8$의 초기공급 농도보다는 수용액 상에서의 4급 암모늄양이온과 퍼록시디슬페이트 음이온의 농도로 나타낼 수 있었다. 관찰된 초기중합속도를 사용하여 분균일 액-액계에서의 순환 상이동에 의한 개시과정을 포함한 중함메카니즘을 밝힐 수 있었다. 폴리스티렌의 점도평균분자량은 $Na_2S_2O_8$의 농도에 역비례하였는데, 라디칼 중합메카니즘에 의하여 $[Q^+]([S_2O{_8}^{2-}]{\alpha}_2)^{1/2}$로 나타내어졌다.

• 대한한의학방제학회지
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• 제12권1호
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• pp.255-262
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• 2004

The inhibitory effect of the aerial parts of Fagopyrum esculentum on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical was examined. The n-butanol fraction from the methanol extract of title plant showed stronger inhibitory effect than other fractions on DPPH radical. Two flavonoids were isolated from n-butanol fraction having the potent activity and elucidated as quercetin-3-O-${\alpha}$-L-rhamnoside and quercetin-3-O-rutinoside on the basis of spectral evidence. The $IC_{50}$ values of these compounds on DPPH radical were 6.56 ${\mu}M$ and 8.37 ${\mu}M$, respectively.

• Bulletin of the Korean Chemical Society
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• 제16권3호
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• pp.281-284
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• 1995

The visible emission spectra of the o-xylyl radical in the gas phase have been obtained using a Fourier transform spectrometer coupled with a technique of supersonic expansion. The o-xylyl radical was generated in a jet by expansion with an inert buffer gas He from a high voltage dc discharge of the precursor o-xylene. The spectra were analyzed on the basis of the rotational contours of the vibronic bands as well as the known vibrational frequencies by a matrix isolation method.

• 한국물환경학회지
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• 제35권6호
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• pp.550-556
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• 2019

This study was carried out to improve the photocatalytic reaction of TiO₂ photocatalyst. During the photocatalytic reaction, OH radicals are generated and they have an excellent oxidation capability for wastewater treatment. To evaluate the OH radicals generated according to crystallographic structure of TiO₂ nanotubes photocatalyst, a probe compound, 4-Chlorobenzoic acid was monitored to evaluate OH radical. Ultraviolet light was applied for photocatalytic reaction of TiO₂. The 4-Chlorobenzoic acid solution was prepared at laboratory. TiO₂ nanotube was grown on titanium plate by using anodization method. The annealing temperature for TiO₂ nanotube was varied from 400 to 900 ℃ and the crystal forms of the TiO₂ nanotube was analyzed. Depending on annealing temperature, TiO₂ nanotubes have shown different crystal forms; 100% anatase (0 % rutile), 18.4 % rutile (81.6 % anatase), 36.6 % rutile (63.4 % anatase) and 98.6% rutile (1.4% anatase). As the annealing temperature increases, the rutile ratio increases. OH radical generation from 18.4 % rutile TiO₂ nanotube plate was about 3.8 times higher than before annealing and 1.4 times higher than only 100 % anatase-TiO₂ nanotube. The efficiency of the 18.4% rutile TiO₂ nanotube was the best in comparison to TiO₂ nanotube with 18.4 %, 36.6 % and 98.6 % rutile. As a result, photocatalytic ability of 18.4 % rutile-TiO₂ nanotube plate was higher than 100 % anatase-TiO₂ nanotube plate.

• 한국물환경학회지
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• 제32권5호
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• pp.403-409
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• 2016

In this study, a TiO₂ nanotube was grown on a titanium plate by using anodic oxidation method for the evaluation of TiO₂ nanotube morphology. The TiO₂ nanotube was grown in an electrolyte containing ethylene glycol, 0.2 wt% of NH₄F and 2 vol% of H₂O. Applied voltage varied from 30 to 70 V and the morphology of the TiO₂ nanotube was observed. After anodization, a TiO₂ nanotube plate was immersed in 35℃ ethanol for 24 hours. Anatase and rutile crystal forms of TiO₂ nanoutbe were observed after annealing. 4-chrolobenzoic acid, a probe compound for OH radicals, was dissolved in H₂O in order to measure the OH radical. Liquid chromatography was used to check the concentration of the 4-chrolobenzoic acid. The OH radical generation by TiO₂ nanotube plate was proportionate to the length of the TiO₂ nanotube. Furthermore, when the number of TiO₂ nanotube plate increased, the OH radical generation increased as well.