• Journal of Ginseng Research
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• 제13권1호
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• pp.98-104
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• 1989

In order to determine the specific active oxygen species directly related to chlorophyll bleaching in the leaf-burning disease, we investigated the effects of singlet oxygen (1O2), superoxide radical (O2-), and hydrogen Peroxide (H2O2) on isolated chloroplast suspension and leaf discs from Panax ginseng C.A. Meyer. When the singlet oxygen was added to the chloroplast suspension, the chlorophyll and carotenoid contents were decreased by more than 809), similar to treatment with high light intensity (100 KLux). We assumed that the conversion of dioxygen (O2) produced either in photolysis or in breakdown of hydrogen peroxide to singlet oxygen resulted from photorespiration. On the basis of these experiments , :he inhibitory effects of active oxygen scavengers propylgallic acid (PGA), 2,5-ditetrabutyl hydroquinon (DBH), sodium pyrosulfate (SPS), and ascorbic acid (ABS) were examined. In chloroplast suspension all four scavengers inhibited chlorophyll bleaching by more than 75fl , and in the leaf discs the inhibition rates of SPS, PGA and ABS were 46%, 51%, and 96% respectively.

• 공업화학
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• 제19권2호
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• pp.236-241
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• 2008

자외선 조사에 따른 광촉매 $TiO_2$의 표면에서 발생하는 활성산소종의 기상확산을 이용하여 실리콘기판 위에 산화박막을 성장시켰다. 자외선의 세기, 기판의 온도와 반응기 내의 산소 압력을 공정변수로 한 결과, 일정두께의 실리콘 산화박막의 성장이 자외선의 세기가 증가할수록 빨랐으며, 자외선램프의 세기를 60 W BLB 램프에서 1 kW 고압수은 랩프로 변경할 경우 성장속도가 8배 정도 빨라졌다. 반응기 내의 압력이 증가할수록 실리콘 산화박막의 성장속도는 느렸다. 대부분 산화박막의 성장은 $20{\AA}$에서 포화되었으며, 자외선의 세기가 증가할수록 포화상태까지 도달시간이 빨라졌다. 성장된 산화박막을 열처리를 통하여 전형적인 열산화막의 물성에 도달할 수 있었다. 광활성 산소종의 기상확산은 실리콘 산화박막의 저온 형성에 대한 광촉매 활용이라는 새로운 산화공정 방법으로 사용이 가능함을 확인할 수 있었다.

• 한국환경농학회지
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• 제12권3호
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• pp.264-280
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• 1993

The environmental pollutions were a serious problem in Korea recently. So many researcher have studied the effect of environmental pollution on plants and agro-ecosystem, but the basic mechanisms of environmental stresses were various. One of the important mechanisms was oxidative stress caused by active toxic oxygen. The toxic oxygen was generated by several stresses, abnormal temperature, many xenobiotics, air pollutants, water stress, fugal toxin, etc. In the species of toxic oxygen which is primary inducer of oxidative stresses, superoxide, hydrogen peroxide, hydroxyl radical and singlet oxygen were representative species. The scavenging systems were divided into two groups. One was nonenzymatic system and the other enzymatic system. Antioxidants such as glutathione, ascorbic acid, and carotenoid, have the primary function in defense mechanisms. Enzymatic system divided into two groups; First, direct interaction with toxic oxygen(eg. superoxide dismutase). Second, participation in redox reaction to maintain the active antioxidant levels(eg. glutathione reductase, ascorbate peroxidase, etc.).

• 약학회지
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• 제37권6호
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• pp.647-658
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• 1993

The susceptibilities of aldehyde dehydrogenase (AldDH) and alcohol dehydrogenase (ADH) to active oxygen generated by xanthine-xanthine oxidase (XOD) system were studied. Incubation of AldDH with 2$\times$10$^{-3}$ units of XOD for 30 min at $25^{\circ}C$ resulted in the decrease of enzyme activity to 30% and it was inactivated completely when incubated with 5$\times$10$^{-3}$ units of XOD. Whereas 70% of ADH activity was retained after exposure to 5$\times$10$^{-3}$ units of XOD for 30 min, 40% of ADH activity was retained after exposure to 5$\times$10$^{-2}$ unit of XOD for 30 min. This inhibition effect by the active oxygen was preventable by catalase and glutathione, but not by SOD. The rates of the NADPH-dependent oxygen consumption by the liver S-9 mixture and microsomes were also determined in this study. Rate of oxygen consumption is increased in the liver S-9 mix and microsomes from phenobarbital-treated rat, and it was consistent with increased lipid peroxidation. In the presense of ethanol as a substrate, the oxygen consumption rates were increased. It is reported that hepatic AldDH activity is depressed in alcoholic liver diseases, however there is few report that explains the reason of depressed AldDH activity. These results are supportive of the theory that the increase in hepatic ethanol oxidation through the induced ME activity after chronic ethanol feeding generate oxygen radical at elevated rates and it leads to the depression of AldDH activity.

• 한국식품저장유통학회지
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• 제6권1호
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• pp.115-120
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• 1999

This study was carried out to investigate the effect of Pine needle extract on lipid oxidation and free radical reaction in iron sources reacted with active oxygen species. The results were summarized as follow; The pine needle extracts didn`t show a distinct effect on reduction of lipid oxidation if the iron ion didn`t exist in oil emulsion. The pine needle extracts played role as a strong chelating agents to bind iron ion if Ferrous iron(Fe\ulcorner) exist in oil emulsion. Ferric iron(Fe) was lower effect than Ferrous iron(Fe) on free radical reaction in oil emulsion. And also, the Fe\ulcorner reacted with pine needle extract did not show distinct effect on free radical reaction, compared to Fe\ulcorner reacted with pine needle extract. And also, Pine needle extracts reacted with H\ulcornerO\ulcorner were tended to show a low oxygen scavenging ability in case of H\ulcornerO\ulcorner only was existed, compared to those of H\ulcornerO\ulcorner + Fe\ulcorner complex. Pine needle extracts were the most powerful Fe\ulcorner binding agents, compared to other strong synthetic antioxidants such as EDTA and DTPA.

• 한국표면공학회지
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• 제51권2호
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• pp.133-137
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• 2018

Plasma devices such as jets, pencils, and torches have been developed as new tools that help penetration of target agents and applied to plasma medicine. However, these devices cannot be used in a large area. Therefore, we introduced a flexible plasma device, which can be treated of large area and designed as bendable plasma. In additional, in vitro model based on agarose gel was prepared that can be show effectiveness in the depth of penetration. Plasma treatment conditions such as power, time and distance can be optimized on the agarose gel wound model. The chemical structure of changed polysaccharides was predicted due to reactive excited atoms and molecules, UV photons, charged particles and reactive oxygen and nitrogen species (RONS).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.174-174
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• 2012

The nature of feed gas is essential for the active species formed in the nonthermal plasma jets, which would induce various biological phenomena. We investigated the different physiological effects of atmospheric pressure soft-plasma jets on Esherichia coli and blood cells according to the feed gas. Cell death rate, growth curve, membrane molecular changes and induced genes were examined. The relationship between cellular reactions and active species generated by discharge will be discussed.

• 약학회지
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• 제51권1호
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• pp.75-82
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• 2007

Reactive oxygen species (ROS) are produced in the metabolic process of oxygen in cells. The superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in cells systemize the antioxidant enzymes to control the oxidative stress. Genistein is one of the isoflavonoids, and its role in controlling cellular oxidative stress is presently the active issue at question. In this study; we analyzed genistein-induced survival rates of the CHO-K1 cells, activities of antioxidant enzymes, ROS levels, and expression levels of antioxidant enzyme genes in order to investigate the effect of genistein on cellular ROS production and antioxidative systems in CHO-K1 cells. As results, the survival rate of cells was decreased as the dose of genistein increases (12.5${\sim}$200 ${\mu}$M). Genistein increased cellular ROS levels, while it reduced total SOD activities and the expression of CuZnSOD. In conclusion, we suggest that genistein may induce oxidative stress via down-regulation of SOD.

• 공업화학
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• 제3권2호
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• pp.256-265
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• 1992

NaCl(30wt%)/ZnO(60wt%)/${\alpha}-Al_2O_3$ 촉매상에서 메탄의 oxidative coupling 반응의 속도식을 연구하여 활성 산소종에 관하여 고찰하였다. 반응온도 $650^{\circ}C$에서 $750^{\circ}C$까지 메탄의 전화율 10%미만의 범위에서 메탄과 산소의 분압을 변화시켜 가면서 메탄의 전환속도를 측정하여 속도식을 검증하였다. 제안된 메틸라디칼의 생성반응은 Langmuir-Hinshelwood형 반응기구를 따른다. 촉매표면의 서로 다른 활성점에 흡착된 메탄분자와 산소분자가 반응하여 메틸라디칼이 생성되는 반응이 속도결정단계이며, 이때 활성화 에너지는 약 39kcal/mol이었다. 메탄의 C-H 결합의 해리에 관여하는 산소종은 표면상의 이원자 산소인 $O{_2}{^{2-}}$나 $O_2{^-}$로 제시할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.35-35
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• 2010

Understanding the mechanistic details of heterogeneous catalytic reactions will provide a way to tune the selectivity between various competing reaction channels. In this regard, catalytic decomposition of alcohols over the rutile $TiO_2$(110) surface as a model oxide catalyst has been studied to understand the reaction mechanism employing the temperature-programmed desorption (TPD) technique. The $TiO_2$(110) model catalyst is found to be active toward alcohol dehydration. We find that the active sites are bridge-bonded oxygen vacancies where RO-H heterolytically dissociates and binds to the vacancy to produce alkoxy (RO-) and hydroxyl (HO-). Two protons adsorbed onto the bridge-bonded oxygen atoms (-OH) readily react with each other to form a water molecule at ~500 K and desorb from the surface. The alkoxy (RO-) undergoes decomposition at higher temperatures into the corresponding alkene. Here, the overall desorption kinetics is limited by a first-order decomposition of intermediate alkoxy (RO-) species bound to the vacancy. We show that detailed analysis on the yield and the desorption temperatures as a function of the alkyl substituents provides valuable insights into the reaction mechanism. After the catalytic role of the oxygen vacancies has been established, we employed x-ray photoelectron spectroscopy to further study the surface electronic structure related to the catalytically active defective sites. The defect-related state in valence band has been related to the chemically reduced $Ti^{3+}$ defects near the surface region and are found to be closely related to the catalytic activity of the $TiO_2$(110) surface.