• 한국안전학회지
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• 제20권1호
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• pp.81-86
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• 2005

This study has investigated radiation degradation of low density polyethylene(LDPE). Samples were irradiated up to 800kGy using a $Co^{60}\;\gamma-ray$ at a dose rate of 5kGy/hr in the presence of air atmosphere at room temperature. After irradiation, storing for 2 weeks, free radical measurement of LDPE has established by electron spin resonance(ESR). ESR measurement showed that free radical concentration(FRC) was increased with radiation dose and decreased with the time. The radical types showed alkyl, allyl, and peroxy radical with the irradiation, these changed to peroxy radical with the time.

• 한국식품영양학회지
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• 제26권1호
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• pp.150-153
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• 2013

본 연구에서는 한국, 중국, 일본 등의 대표적 면요리 육수의 항산화 활성을 검토하였다. 이를 위하여, 한국식, 중국식, 일본식 육수를 각각 제조하여, ESR과 비색법을 이용하여 DPPH, hydroxyl, peroxyl, superoxide, ABTS 등의 radical 소거 활성을 측정함으로써 항산화력을 비교하였다. 한국식 육수, 중국식 육수 및 일본식 육수의 DPPH radical 소거 활성은 2 $mg/m{\ell}$의 농도의 실험에서 2.78%, 25.37% 및 40.74%의 소거 활성을 보였다. 한국식 및 중국식 육수는 hydroxyl radical 소거 활성은 매우 낮았으나, 일본식 육수는 0.5 $mg/m{\ell}$에서 59.06%로 소거 활성이 높았다. 한국식, 중국식 및 일본식 육수의 peroxy radical 소거 활성($IC_{50}$)은 각각 0.121 $mg/m{\ell}$, 0.222 $mg/m{\ell}$ 및 0.013 $mg/m{\ell}$으로 일본식 육수가 peroxy radical 소거 활성이 높았다. 한국식, 중국식 및 일본식 육수의 ABTS radical 소거 활성의 $IC_{50}$ 값은 1.2 $mg/m{\ell}$, 1.8 $mg/m{\ell}$ 및 1.249 $mg/m{\ell}$였다.

• 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.

• 한국대기환경학회지
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• 제22권6호
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• pp.779-790
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• 2006

This study examines relative contributions of volatile organic compounds (VOCs) to the formation of hydroxyl (OH) and peroxy radicals such as $HO_2$ and $RO_2$ during the intensive sampling period (Jun. $1{\sim}30$, 2004) in the air of Seoul metropolitan area. As to the contribution of VOCs to $HO_x$ levels, the impact of individual VOC concentration change on $HO_2$ concentration change was more than an order of magnitude higher than that on OH concentration change during the study period. The contribution of change in isoprene concentration to $HO_2$ concentration change was 38 times higher than OH and that in the concentration of alkene compounds to $HO_2$ concentration change was 31 times higher than OH. Moreover, the concentration changes of isoprene and aromatic compounds (AROM) played significant roles in $HO_x$ concentration changes. On the other hands, aldehydes (ALD2) and alkanes (ALKA) showed anti-correlation (negative) in $HO_x$ concentration changes with low contribution ($-4{\times}10^{-3}$ pptv/ppbv (OH) and $-58{\times}10^{-3}$ ($HO_2$) for ALD2; $-1{\times}10^{-3}$ (OH) and $-15{\times}10^{-3}$ ($HO_2$) for ALKA). Unlike other VOCs, $C_2H_6$ and $C_3H_8$ showed positive or negative contribution to peroxy radicals, depending on ambient air conditions. The contribution of VOC concentration changes to changes in $CH_3O_2$ and $RO_2$ concentration showed similar pattern to $HO_x$ contribution.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.381.3-382
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• 2002

Free radical-mediated cell damage and free radical attack on polyunsaturated fatty acids result in the formation of lipid radicals. These lipid radicals react readily with molecular oxygen to produce peroxy radicals responsible for initiating lipid peroxidation. The peroxidation of cellular membrane lipid can lead to cell necrosis and considered to be implicated in a number of pathophysiological conditions as well as in the toxicity of many xenobiotics. DPPH is known to abstract labile hydrogen and the ability to scavenge the DPPH radical is related to the inhibition of lipid peroxidation. (omitted)

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2001년도 추계학술대회 논문집
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• pp.325-326
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• 2001

오존은 태양광선의 존재 하에 질소산화물과 VOCs가 관련하여 발생하는 생성물이다. 대기중의 VOCs 는 히드록실 라디칼(hydroxyl radical, OHㆍ)과 같은 자유 라디칼(free radical)과 반응하여 하이드로퍼옥시 라디칼(hydroperoxy radical, HO$_2$ㆍ)과 알킬 퍼옥시 라디칼(alkyl peroxy radical, RO$_2$ㆍ)을 생성해 낸다. 이 퍼옥시 라디칼들은 NO를 NO$_2$ㆍ로 산화시키며 또한 히드록실 라디칼을 재생하며 이 히드록실 라디칼은 다시 VOCs와 반응한다. 그리고, 이때 산화된 NO$_2$는 햇빛에 의해 NO와 자유산소원자(free oxygen atom)로 광분해 되는데, 여기서 생성된 자유산소인자는 산소분자와 반응하여 오존을 생성한다. (중략)

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
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• pp.473-476
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• 2004

This study has investigated radiation degradation of low density polyethylene(LDPE). Samples were irradiated using a $Co^{60}\;\gamma-ray$ and ray up to 800 kGy at a dose rate of 5 kGy/hr in the presence of air atmosphere at room temperature. After irradiation, free radical measurement of LDPE has established by electron spin resonance(ESR). Then, each sample was stored for 2 weeks. ESR measurement showed that free radical concentration(FRC) was increased with radiation dose and changed from alkyl, allyl radical to peroxy radical with time.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.381.2-381.2
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• 2002

There is now increasing evidence that free radicals and active oxygen species are involved in a variety of pathological events. often associated with ageing. Free radical-mediated cell damage and free radical attack on polyunsaturated fatty acids result in the formation of lipid radicals. These lipid radicals react readily with molecular oxygen to produce peroxy radicals responsible for initiating lipid peroxidation. The peroxidation of cellular membrane lipid can lead to cell necrosis and considered to be implicated in a number of pathophysiological conditions as well as in the toxicity of many xenobiotics. (omitted)

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 2003년도 추계 학술논문발표회 논문집
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• pp.54-59
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• 2003

유기과산화물은 분자구조내에 과산화결합(Peroxy, -O-O-)을 갖고 있는 유기화합물로서 매우 불안정한 과산화수소(H-O-O-H)의 유도체이다. 과산화물을 특징짓는 산소-산소(-O-O-) 과산화결합은 C-H, C-O, C-C 등의 결합에 비하여 결합에너지가 작아서 열이나 빛에 의해서 쉽게 균형분해(Homolysis)가 일어나 두 개의 유리기인 라디칼(Free radical)을 생성하게 되는데, 이때 생성된 라디칼은 비닐중합반응을 개시시킬 수 있고, 또한 다른 자유 라디칼 반응을 유발시킬 수 있다.(중략)

• 방사선산업학회지
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• 제9권2호
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• pp.57-62
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• 2015

In this study, we fabricated effect of storage conditions on graft of polypropylene (PP) non-woven fabric induced by electron beam. The electron beam irradiations on PP non-woven fabric were carried out over a range of irradiation doses from 25 to 100 kGy to make free radicals on fabric surface. The radical measurement was established by electron spin resonance (ESR) for confirming the changes of the alkyl radical and peroxy radical according to effect of storage time, storage temperature and atmosphere. It was observed that the free radicals were increased with irradiation dose and decreased with storage time due to the continuous oxidation. However, the radical extinction was significantly delayed due to reduced mobility of radicals at extremely low temperature. The degree of graft based on the analysis of ESR was investigated. The conditions of graft reaction were set at a temperature: $60^{\circ}C$, reaction time: 6 hours and styrene monomer concentration: 20 wt%.