• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2002.04a
• /
• pp.95-96
• /
• 2002

과산화수소(hydrogen peroxide, $H_2O$$_2$)는 광화학적 이차 생성물이며, 대기의 산화상태를 알려주는 지시자의 역할을 한다 과산화수소는 HO$_2$ 라디칼의 self-reaction 으로 생성된다. HO$_2$＋HO$_2$＋ M$\longrightarrow$$H_2O$$_2$＋M, OH나 HO$_2$ 라디칼은 NOx나 hydrocarbon 과 같은 대표적인 오존 전구물질들을 산화시킨다. 대기 내수명이 불과 1초 이내인 OH나 HO$_2$ 라디칼을 직접 측정하기란 어려우며 수명이 1-2 일 정도인 $H_2O$$_2$를 측정하므로써 이들 라디칼의 대기 내 농도를 예측 할 수 있다. (중략)

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.412-412
• /
• 2010

플라즈마는 미세 전기 소자 제작에 있어 박막의 증착, 식각, 세정등 여러 가지 공정에서 널리 사용되고 있다. 미세 소자의 선폭의 감소와 높은 생산성을 위한 웨이퍼 면적의 대형화가 진행됨에 따라 플라즈마의 균일도는 공정 수율 향상의 관점에서 중요한 요소로 그것의 계측과 공정 중 실시간 감시에 필요성이 부각되고 있다. 플라즈마에 존재하는 라디칼의 밀도, 이온의 밀도, 전자 온도 등의 웨이퍼 상에서의 공간 분포와 공정 결과물과의 상관관계에 대한 연구는 현재까지 다양하게 진행 되었으며 특히, 라디칼의 공간 분포가 공정 결과물의 균일도와 큰 상관 관계가 있는 것으로 알려져 있다. 라디칼의 농도 분포를 계측은 레이저 유도 형광법, 발광 분광법, 흡수 분광법 등을 통하여 이루어져 왔으며, 특히 발광 분광법의 경우 계측의 민감성, 편의성등을 이유로 가장 널리 사용되고 있다. 그러나 현재 까지 진행된 발광 분광법을 이용한 라디칼의 공간 분포 계측은 그 자체로 공간 분포를 계측하는 것이 아닌 플라즈마 밀도의 축 대칭성을 가정하여 Abel inversion을 적용하거나, 광섬유를 플라즈마에 직접 삽입하는 방식을 사용하기 때문에 실제 반도체 제작공정을 비롯한 미세소자 공정 플라즈마의 라디칼 밀도 분포를 실시간, 비 접촉 방식으로 계측 하는데 한계가 있다. 본 연구에서는 반도체 공정 플라즈마의 밀도 균일성 분석을 위한 공간 분해 발광 분광기를 제안한다. 기존의 발광 분광법과 비교하여 공간 분해능 향상을 위하여 직렬로 설치된 다수의 렌즈, 개구, 그리고 핀홀을 이용하였다. 공간 분해 발광 분광기의 공간 분해능을 계산하였으며, 실험을 통하여 검증 하였다. 또, HDP CVD를 이용한 $SiO_2$ 박막 증착 공정에서 산소 라디칼의 농도와 증착된 박막의 두께 분포의 상관 관계를 계측 함으로써 공간 분해 발광 분광기의 플라즈마 공정 적용 가능성 입증 하였다.

• Journal of Applied Biological Chemistry
• /
• v.62 no.2
• /
• pp.167-172
• /
• 2019

In vitro antioxidant effect of 50% ethanol extract from Napier grass (Penninsetum purpureum) was investigated. The yield and polyphenol content of the Napier grass extract were $6.3{\pm}0.35%$ and $79.6{\pm}3.65{\mu}g$ gallic acid equivalents/mg-extract, respectively. Antioxidant ability of the Napier grass extract such as fee radical and cation radical scavenging activities, reducing power, nitrite scavenging activity, and lipid peroxidation inhibitory activity proportionally increased as concentration of the extract increased. $EC_{50}$ values of the Napier grass extract for free radical scavenging, cation radical scavenging, reducing power, and nitrite scavenging were 1,930.0, 350.0, 840.0, and $1,470.0{\mu}g/mL$, respectively. In the presence of $85.0{\mu}g/mL$ of the Napier grass extract, lipid peroxidation was potently inhibited by 74.6%.

• Journal of the Korean Applied Science and Technology
• /
• v.37 no.6
• /
• pp.1583-1590
• /
• 2020

In this study, activity of anti-oxidation of Cinnamomum loureiroi extract (CLE). In order to measure anti-oxidation effect of CLE, phenol content of CLE, radical scavenging activity of ABTS and DPPH, and decrease of ROS production. Before the experiment, against Raw 264.7 cell, a cytotoxicity was measured and the result showed no toxicity. CLE's total polyphenol amount was 397.7±8.3 mg/g and the total flavonoid amount was 101.899±0.885 mg/g. As a measurement result of ABTS radical scavenging ability and DPPH radical scavenging ability, radical scavenging ability increased depends on the concentration. CLE's effect on the ROS creation was checked and the result showed that CLE suppressed ROS creation by showing a meaningful decrease of ROS generation. From all of the results, CLE is know to have an antioxidant effect. These results will be provided as fundamental data for further development of the new material of functional cosmetics to the results above.

• Journal of Bio-Environment Control
• /
• v.18 no.4
• /
• pp.442-447
• /
• 2009

Extracts from various parts of oriental melon were obtained and antioxidant property and antioxidant constituents including total phenol, total flavonoid, total vitamin C were examined. Free radical scavenging activity was measured by DPPH and ABTS method. Peel part of oriental melon showed the most potent scavenging activities against DPPH and ABTS radicals. The contents of total phenol, total flavonoid in peel were higher than other parts except vitamin C. The amount of vitamin C was the highest in placenta. The relationship between antioxidant activities and antioxidant constituents was determined and showed higher correlation coefficients between antioxidant activities and content of total phenol than other constituents. The above results suggest that phenolic compounds affect antioxidant activity of oriental melon and oriental melon has a good promise as functional food for enhancing health.

• Korean Journal of Food Science and Technology
• /
• v.45 no.2
• /
• pp.206-212
• /
• 2013

In the current study, antioxidant properties of extracts from different parts of Taraxacum officinale were determined by measuring the radical scavenging activity of 1,1-diphenyl-2-picryl hydrazyl(DPPH) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The antioxidant activity of aerial and root parts of this plant was measured in extracts obtained from various solvents, e.g., water, 50, 70, 100% ethanol, and hot-water. The hot-water extracts had the highest radical scavenging activities. A further study was conducted to determine the total antioxidant activity of hot-water extract fractions obtained from different solvents, e.g., chloroform, ethyl acetate, n-butanol, and water. The ethyl acetate fraction of this extract displayed the strongest DPPH and ABTS radical scavenging activity and the highest total phenolic contents. The inhibitory effect of individual solvent fractions on the production of nitric oxide in LPS-stimulated RAW 264.7 cells was measured. The results indicated that the ethyl acetate fraction of aerial and roots part extracts significantly reduced nitric oxide productions.

• Polymer(Korea)
• /
• v.38 no.6
• /
• pp.827-831
• /
• 2014

An organic radical polymer (ORP) was prepared by radical polymerization and following oxidation into nitroxyl radical. Two different oxidation methods were employed and their radical concentrations were measured using electroparamagnetic resonance spectroscopy (EPR) and UV-visible absorption (UV-vis) spectroscopy. From these measurements, $H_2O_2-Na_2WO_4$ oxidation method exhibited a complete oxidation, which resulted in 97.6% spin concentration. Also, it was revealed that convenient and cheap UV-vis measurement was useful for preliminary radical concentration comparison. After applied as a cathode material in lithium ion batteries, ORP electrode showed a high initial capacity ($110mAh\;g^{-1}$), a good initial efficiency (96%), a very high rate performance (70% charging during 1.2 min) and stable cycle performance.

• Food Science and Preservation
• /
• v.24 no.6
• /
• pp.879-884
• /
• 2017

In a continuing screening of selected medicinal plants native to Mongolia, the antioxidant and ${\alpha}$-glucosidase inhibitory activities of methanol extract of Iris bungei were investigated. After extraction with 80% of methanol, the methanol fraction was further extracted with n-hexane, EtOAc and n-BuOH in order to obtain four different solvent-soluble fractions, namely n-hexane-soluble, EtOAc-soluble, n-BuOH-soluble and $H_2O$ residue. The antioxidant properties were evaluated by radical scavenging assay using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) ($ABTS^+$) radicals. The anti-diabetic efficacy of I. bungei extract was investigated by ${\alpha}$-glucosidase assay. All tested samples showed dose-dependent radical scavenging and ${\alpha}$-glucosidase inhibitory activities. Among the tested extracts, the EtOAc-soluble fractions showed the greatest radical scavenging activity and ${\alpha}$-glucosidase inhibitory properties among other solvent-soluble fractions. This result suggested that there was a significant relationship between the total phenolic content and biological efficacy. Thus, I. bungei extract might be considered as a new potential source of natural antioxidant and as a ${\alpha}$-glucosidase inhibitory source. A more systematic investigation of this biomass sill be performed for further investigation of activity against antioxidative and anti-diabetic effects.

• Journal of Adhesion and Interface
• /
• v.15 no.1
• /
• pp.22-30
• /
• 2014

Self-photoinitiating acrylate (SPIA) which can undergo self-initiation under UV irradiation was synthesized by a Michael addition in the presence of a base catalyst. The SPIA polymerizations were investigated by photo-differential scanning calorimeter (photo-DSC) and surface physical properties such as pendulum hardness and pencil hardness. The results showed that the SPIA can cure upon UV irradiation by itself without a photoinitiator. But we found out that both the curing rate and the conversion were too low for the self-curing reaction of SPIA. In order to improve the SPIA curing properties, we introduced the SPIA/cationic hybrid system and observed the effects of the addition of commercial free radical type monomer and photoinitiator on the curing behaviors. SPIA/cationic hybrid system was the best suitable to improve the SPIA curing properties. The kinetic analysis indicated that the cationic monomer and photoinitiator apparently accelerated the cure reaction and rate of the hybrid SPIA system, mostly due to the synergistic effect of cationic monomer and photoinitiator increasing the mobility of active species and the generation of reactive species (free radical, cation) during the photopolymerization process. The physical properties showed that, unlike typical free radical system, the hybrid systems did not show oxygen inhibition effect because of cationic reaction on the coating surface.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.46 no.4
• /
• pp.329-337
• /
• 2020

In this study, Rubus idaeus (Raspberry) cultivar 'Willamette' fruit extract(RIFE) was prepared from the freeze-dried raspberry powder, n-hexane and ethyl acetate, and then the phenolic compound content, ferric reducing ability, and radical scavenging ability were measured. The raspberry cultivar 'willamette', 'polka', and 'polana' compound fruit extract did not show cytotoxicity up to the concentration of 10%. As a result of conducting an experiment at the concentration, it was confirmed that the total phenolic compound content was 375.3 ppm, and the total flavonoid content was 43.46 ppm, and the ferric reducing ability by ferric reducing antioxidant power (FRAP) reagent was equivalent to FeSO4 0.532 mM. It was confirmed that 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability was 94.5 ± 0.7%, and the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging ability was 99.4 ± 2.82%, and the nitric oxide (NO) radical scavenging activity was 88.5 ± 0.4%. When compared with the L-ascorbic acid 'standard' solution, DPPH radical scavenging ability was between 25 - 50 ppm / ABTS radical scavenging ability was close to 100 ppm / NO radical scavenging ability was more than 1,000 ppm. These results suggest that the raspberry cultivar 'willamette' fruit extract could be applied as an effective cosmetic material with antioxidant activity.