• 한국물환경학회지
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• 제28권3호
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• pp.401-408
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• 2012

High-voltage dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. The initiation and propagation of the electrical discharges depends on several physical, chemical, and electrical parameters such as 1st and 2nd voltage of power, gas supply, conductivity and pH. These parameters also influence the physical and chemical characteristics of the discharges, including the production of reactive species such as OH, $H_2O_2$ and $O_3$. The experimental results showed that the optimum 1st voltage and air flow rate for RNO (N-Dimethyl-4-nitrosoaniline, indicator of the generation of OH radical) degradation were 160 V (2nd voltage of is 15 kV) and 4 L/min, respectively. As the increased of the 2nd voltage (4 kV to 15 kV), RNO degradation, $H_2O_2$ and $O_3$ generation were increased. The conductivity of the solution was not influencing the RNO degradation and $H_2O_2$ and $O_3$ generation. The effects pH was not high on RNO degradation. However, the lower pH and the conductivity, the higher $H_2O_2$ and $O_3$ generation were observed.

• Environmental Engineering Research
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• 제10권3호
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• pp.144-154
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• 2005

The use of ozone gained acceptance in the production of ultrapure water because of its powerful oxidizing ability. Ozone is currently used to deactivate microorganisms and remove organic contaminants. However, interest also exists in using radical species, which arc stronger oxidants than ozone, in such processes. One means of producing radical species is by corona discharge. This work investigates the use of a novel pulseless corona-discharge system for the removal of organic substances in ultrapure water production. The method combines corona discharge with electrohydrodynamic spraying of oxygen, forming microbubbles. Experimental results show that pulseless corona discharge effectively removes organics, such as phenol and methylene blue, in deionized water. The corona-discharge method is demonstrated to be comparable to the direct use of ozone at a high-applied voltage. The results also show that a minimum applied voltage exists for operation of the corona-discharge method. In this work, the minimum applied voltage is approximately 4.5 kV. The kinetic rate or phenol degradation in the reactor is modeled. Modeling results show that the dominant species of the pulseless corona-discharge reactor are hydroxyl radical and aqueous electron. Several radical species produced in the pulseless corona-discharge process are identified experimentally. The. major species are hydroxyl radical, atomic hydrogen species, and ozone.

• 대한본초학회지
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• 제27권6호
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• pp.91-98
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• 2012

Objectives : Rhodiola rosea L. (Crassulaceae) is a plant living at the areas of high-altitude mountain, and Rhodiolae Radix(the root of R. rosea) has been used as a traditional medicine to decrease the symptoms of mental- or physical-stress in Asia and Europe. To examine the efficacy of Rhodiolae Radix on the oxidative stress, the anti-oxidative effects of the radix were examined, Methods : The effects of Rhodiolae Radix on several oxidative factors were examined in vitro, and also the effects were tested in the liver of rats which were treated with a high dose of alcohol during 2 weeks. Results : The extract of Rhodiolae Radix in vitro scavenged some oxidants, such as DPPH, Superoxide anion radical and LDL, and the extract also inhibited the oxidative capacity of linoleic acid, significantly. Meanwhile, in the in vivo test, the methanol-extract decreased some oxidation parameters, such as relative liver weight, TBARS and SOD activities, and also increased catalase activity in the liver of alcohol-loaded rats, But, the extract had no effects on GSH content and GSH-px activiy in the rats. Conclusion : The root of Rhodiola rosea has a strong anti-oxidative capacity, and also has some preventive properties aginst the alcoholic stress.

• The Plant Pathology Journal
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• 제40권3호
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• pp.235-250
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• 2024

During the infection process, plant pathogenic fungi encounter plant-derived oxidative stress, and an appropriate response to this stress is crucial to their survival and establishment of the disease. Plant pathogenic fungi have evolved several mechanisms to eliminate oxidants from the external environment and maintain cellular redox homeostasis. When oxidative stress is perceived, various signaling transduction pathways are triggered and activate the downstream genes responsible for the oxidative stress response. Despite extensive research on antioxidant systems and their regulatory mechanisms in plant pathogenic fungi, the specific functions of individual antioxidants and their impacts on pathogenicity have not recently been systematically summarized. Therefore, our objective is to consolidate previous research on the antioxidant systems of plant pathogenic fungi. In this review, we explore the plant immune responses during fungal infection, with a focus on the generation and function of reactive oxygen species. Furthermore, we delve into the three antioxidant systems, summarizing their functions and regulatory mechanisms involved in oxidative stress response. This comprehensive review provides an integrated overview of the antioxidant mechanisms within plant pathogenic fungi, revealing how the oxidative stress response contributes to their pathogenicity.

• Asian Journal of Atmospheric Environment
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• 제5권2호
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• pp.65-78
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• 2011

Ozone ($O_3$) is a main component of photochemical oxidants, and a phytotoxic anthropogenic air pollutant. In North America and Europe, the current concentration of $O_3$ has been shown to have significant adverse effects on vegetation. In this review, we summarize the experimental studies on the effects of $O_3$ on the growth and photosynthetic activity of Japanese forest tree species to understand the present knowledge and provide sound basis for future research toward the assessment of $O_3$ impacts on Japanese forest ecosystem. Since the 1990s, several Japanese researchers have conducted the experimental studies on the effects of ambient levels of $O_3$ on growth and physiological functions such as net photosynthesis of Japanese forest tree species. Although the sensitivity to $O_3$ of whole-plant growth is quite different among the species, it was suggested that the current ambient levels of $O_3$ in Japan are high enough to adversely affect growth and photosynthetic activity of Japanese forest tree species classified into high $O_3$ sensitivity group such as Japanese beech. The N load to soil has been shown to reduce the sensitivity to $O_3$ of Japanese larch and increase that of Japanese beech. To establish the critical level of $O_3$ for protecting Japanese forest tree species, therefore, it is necessary to take into account the N deposition from the atmosphere. There is little information on the combined effects of $O_3$ and other environmental factors such as elevated $CO_2$ and drought on growth and physiological functions of Japanese forest tree species. Therefore, it is necessary to promote the experimental study and accumulate the information on the combined effects of $O_3$ and any other abiotic environmental factors on Japanese forest tree species.

• Asian Pacific Journal of Cancer Prevention
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• 제16권7호
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• pp.2619-2627
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• 2015

There are several studies that relate oxidative damage as possible mechanism for many cancers. Many studies have also shown that anti-oxidants like selenium and vitamin E decrease the risk for prostate cancer. The main objective of the Selenium and Vitamin E Cancer Prevention Trial (SELECT) study was to look for the benefits of selenium and vitamin E supplementation on prostate cancer. The study had a large sample size, stringent experimental conditions, very long duration, standardized laboratories for biochemical analyses and other factors that contribute to high external validity. The SELECT study failed to show any significant risk reduction for prostate cancers ascribable to selenium and vitamin E supplementations. Because of these conflicting results, many researchers argue about the methods used, supplementations administered (selenium and vitamin E) and indicators used for assessing levels of supplementations. We reviewed many epidemiological studies, clinical trials, and pre-clinical studies. With corroborative evidences we justify that SELECT study has a sound methodology and rationale. In lieu of the contrary results of the select study, researchers should focus on the probable mechanisms for these contrary findings and continue their search for newer and effective agents for prevention of prostate cancer.

• 식물조직배양학회지
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• 제22권2호
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• pp.71-76
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• 1995

자리공 모상근에서 광처리에 따른 항산화효소의 활성을 조사하였다. Catalasa superoxide dismutasae, ascorbate oxidase (AO)의 활성은 광도가 2,000 lx까지 증가할수록 감소하였으며, 특히 AO활성은 2,000 lx에서 암상태보다 92% 감소하였다. Glutathione reductase, glutathione peroxidase (GPO), ascorbate peroxidase 그리고 peroxidase의 활성도는 500 lx까지는 광도가 높아질수록 증가하였으나 그 이상의 높은 광도에서는 현저하게 감소하였다. GPO의 활성은 AO처럼 2,000 lx에서 암상태보다 85%감소하였다. 광파장에 따른 항산화효소의 활성은 청색광의 파장에서 가장 많이 억제되었으며, AO의 활성은 25%까지 감소하였다. 청색광 파장의 광도에 따른 항산화효소의 활성도는 30 lx까지는 증가하다가 200 lx에서는 암상태보다 21-71%까지 감소하는 경향을 나타내었다. AO의 활성은 청색 파장의 광도(300-200 lx)가 증가할수록 급격히 감소하여 200 lx에서는 70%까지 억제되었다. 자리공 모상근의 항산화효소 활성은 청색광 파장의 높은 광도에서 주로 생성된 유해산소 의하여 억제되고 있음을 확인하였다. 광상태하에서 모상근의 생장과 betalain 합성을 향상시키기 위해서는 모상근에서 생성되는 산화제의 효율적인 제거가 요구됨이 시사되었다.

• 식물조직배양학회지
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• 제22권2호
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• pp.65-70
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• 1995

자리공 모상근에서 betalain의 합성에는 광이 필수이지만 생장률은 암상태 보다 광상태(1500 1X)에서 5배 정도 억제된다. 따라서 광상태에서 모상근의 생장이 억제되는 원인을 규명하기 위해서 항산화제 처리에 따른 효과를 조사하였다. 항산화제(ascorbic acid, glutathione, $\alpha$-tocopherol, sodium pyrosulfate, propylgallic acid) 처리에 따른 모상근의 생장은 암상태에서 무처리보다 1.2-1.4배, 광상태에서 약 1.3-1.9배 생장이 증가되었으며, betalain 합성은 무처리보다 1.2-2.1배 향상되었다. 자리공 모상근의 성장 및 betalain 합성에서 항산화제 복합 처리에 따른 효과는 나타나지 않았다. Betalain 합성 과정에서 항산화제의 효과는 청색 파장하에서 가장 높게 나타났다. 따라서 광상태에서 자리공 모상근의 생장과 betalain 합성을 촉진시키기 위해서는 청색 파장에서 적절한 항산화제의 개발이 요구된다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.139-148
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• 2003

In this study, biodegradable base Li-greases were prepared by using Li-soap thickener and vegetable oils such as soybean oil, rapeseed oil, castor oil and synthetic ester. Also, EP-greases were formulated by blending base Li-greases, anti-wear additives, EP additives, anti-oxidants and corrosion inhibitor etc. And EP-greases were characterized by analysing physical properties such as worked penetration, dropping point, 4-ball wear, extreme pressure, thermal properties etc. Biodegradability of base Li-greases and EP-greases were evaluated by CEC-L-33-A-93 method using several inoculums of domestic sewage treatment plant. As the results, biodegradability of vegetable oils were shown at the range of 97.1 to $98.4\%$. And biodegradability of base Li-greases and EP-greases were $86.2\%\;\~\;89.3\%\;and\;83.4\%\;\~\;90.0\%$ which were lower value than those o( vegetable oils due to effect of Li-soap thickener, respectively. Therefore, the EP-greases prepared in this study were easily biodegraded by microorgnism.

• 대한한방내과학회지
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• 제26권1호
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• pp.107-118
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• 2005

Objectives : Peroxynitrite $(ONOO^-)$, fonned from the reaction of $O_2^-$ and NO, is a cytotoxic species that can oxidize several cellular components such as proteins, lipids and DNA. It has been implicated in the aging process and age-related disease such as Alzheimer's disease, rheumatoid arthritis, cancer and atherosclerosis. Due to the lack of endogenous enzymes to thwart $ONOO^-$ activation, developing a specific $ONOO^-$ scavenger is remarkably important. The aim of this study was to investigate scavenging activities of $ONOO^-$ and its precursors, NO and $O_2^-$ and its scavenging mechanism of Ojawhan. Methods : To investigate scavenging activities of $ONOO^-$, NO, $O_2^-$ and its scavenging mechanism using fluorescent probes, DCFDA, DAF-2 and DHR 123. The $ONOO^-$ scavenging activity on Ojawhan was assayed by measuring oxidized dihydrorhodamine 123 (DHR 123) by fluorometry. Oxidative stress was induced by strong oxidants t-butyl hydroperoxide (t-BHP). Endothelial cell (YPEN-1) was used for detection of intracellular oxidative stress. Results : Ojawhan markedly scavenged authentic $ONOO^-$, $O_2^-$ and NO. It also inhibited $ONOO^-$ induced by $O_2^-$ and NO which are derived from SIN-1. Furthennore, ${\underline{Ojawhan}}$ blocked lipopolysaccharide (LPS)-induced $ONOO^-$, $O_2^-$ and NO generation utilizing kidney homogenates of LPS-injected mouse and inhibited t-BHP-induced ROS and $ONOO^-$ in endothelial cell culture system. Conclusions : These results suggest that Ojawhan be developed as an effective $ONOO^-$ scavenger for the prevention of $ONOO^-$ involved diseases and age-related diseases.