• 한국물환경학회지
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• 제28권2호
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• pp.213-218
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• 2012

Abnormal dissolved oxygen concentration in aquatic habitat, both depletion and supersaturation, can be stress factor to aquatic animals. In this study the nationwide distribution of oxygen supersaturation was analyzed for three categories of streams (43 urban streams, 15 rural streams, and 14 forest streams) by using monitoring network data of the Korean Ministry of Environment. From the distribution analysis 30% of urban streams showed hyperoxic condition of eutrophic level, while no forest stream showed hyperoxic condition. The physiological effect of hyperoxia on fish was examined using two species of fish Zacco koreanus, which resulted in higher concentration of a stress hormone (cortisol) in fish exposed to hyperoxic concentration (196%) of oxygen. This study shows that hyperoxic condition is ubiquitous in urban and rural Korean streams, and it can be a stress factor to aquatic animals.

• 한국식품과학회지
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• 제28권1호
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• pp.197-202
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• 1996

콜레스테롤을 함유하는 수용성 모형계에서 erythrosine의 첨가농도, 광도, tocopherol과 ${\beta}-carotene$의 첨가에 따른 headspace내의 산소량의 변화와 콜레스테롤 산화물의 생성량의 변화를 연구하였다. Erythrosine의 첨가량이 증가할수록 headspace내 산소량의 감소가 컸고, 각종 COP 생성량은 증가하였다. 형광등의 조도가 증가할수록 headspace내 산소량의 감소가 컸고, 이에 비례하여 콜레스테롤은 감소하였고 총 COP의 생성량은 증가하였다. 일중항 산소 소거제로 tocopherol과 ${\beta}-carotene$을 첨가하였을 때 headspace내의 산소량은 완만하게 감소하였으며, 이에 비례하여 콜레스테롤의 감소가 완만하였고 총 COP의 생성량 또한 감소하였다.

• 식품보건융합연구
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• 제10권2호
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• pp.13-17
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• 2024

Oxygen is necessary to sustain life, but reactive oxygen species (ROS) produced by oxygen metabolism can cause mutations and toxicity. ROS can damage cellular macromolecules, leading to oxidative stress, which can accelerate cell death and aging. ROS generated in food affect the taste, color, and aroma of food, and high levels of ROS in meat can cause spoilage. Superoxide dismutase (SOD) plays an important role in scavenging ROS in food and reducing their toxicity to organisms. SOD exerts its antioxidant effect by catalyzing the breakdown of O₂-• to H₂O₂. As a natural antioxidant, SOD has the ability to regenerate and maintain its activity over a long period of time without depletion, unlike chemical antioxidants that may have side effects or stability issues. This antioxidant effect of SOD has great potential in a variety of industries, and in the food industry it can be utilized to improve product quality and provide safe and healthy products to consumers. By disrupting the SOD2 and SOD3 genes in Candida albicans, we studied the effects of SOD2 and SOD3 genes on the antioxidant system, suggesting its potential as a natural antioxidant.

• 대한한의학방제학회지
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• 제28권4호
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• pp.327-337
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• 2020

Objective : Citri Unshius Pericarpium is the dried peel of mature fruit of Citrus unshiu Markovich and has been used to treat indigestion, vomiting, and removal of phlegm. This study investigated the hepatoprotective and antioxidant effect of CEE (Ethanol extract of Citri Unshius Pericarpium) in cadmium (CdCl₂)-treated HepG2 cells. Methods : Component analysis of Citri Unshius Pericarpium was analyzed by UPLC with C₁₈ column. Cell viability was determined by MTT assay. The enzyme activity of superoxide dismutase (SOD) and the level of reactive oxygen species (ROS) and reduced glutathione (GSH) were analyzed using commercially available kits. Results : Cadmium caused severe HepG2 cell death. Cadmium also increased ROS production, consistent with depletion of GSH and inhibition of the SOD enzyme. However, CEE treatment reduced cell death and relieved oxidative stress caused by cadmium toxicity. CEE lowered ROS levels and improved depletion of GSH levels. CEE also enhanced the enzymatic activity of SOD. In component analysis, hesperidin was the most abundant of the five marker compounds (Narigenin, Narigin, Narirutin, Hesperidin and Hesperidin), which assumes that hesperidin partially contributed to the antioxidant activity of CEE. Conclusion : These results suggested that CEE could be a potential substance to solve heavy metal-related health problems. In particular, inhibition of oxidative stress by CEE can be a way to treat liver damage caused by cadmium.

• The Korean Journal of Physiology and Pharmacology
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• 제13권2호
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• pp.115-121
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• 2009

Functional defects in mitochondria are involved in the induction of cell death in cancer cells. We assessed the toxic effect of camptothecin against the human cervical and uterine tumor cell line SiHa with respect to the mitochondria-mediated cell death process, and examined the combined effect of camptothecin and anticancer drugs. Camptothecin caused apoptosis in SiHa cells by inducing mitochondrial membrane permeability changes that lead to the loss of mitochondrial membrane potential, decreased Bcl-2 levels, cytochrome c release, caspase-3 activation, formation of reactive oxygen species and depletion of GSH. Combination of camptothecin with other anticancer drugs (carboplatin, paclitaxel, doxorubicin and mitomycin c) or signaling inhibitors (farnesyltransferase inhibitor and ERK inhibitor) did not enhance the camptothecin-induced cell death and caspase-3 activation. These results suggest that camptothecin may cause cell death in SiHa cells by inducing changes in mitochondrial membrane permeability, which leads to cytochrome c release and activation of caspase-3. This effect is also associated with increased formation of reactive oxygen species and depletion of GSH. Combination with other anticancer drugs (or signaling inhibitors) does not appear to increase the anti-tumor effect of camptothecin against SiHa cells, but rather may reduce it. Combination of camptothecin with other anticancer drugs does not seem to provide a benefit in the treatment of cervical and uterine cancer compared with camptothecin monotherapy.

• 대한기계학회논문집B
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• 제41권2호
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• pp.109-115
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• 2017

전산유체해석(CFD) 기법을 이용하여 음극 지지체형 고체산화물 연료전지(SOFC)에 대한 수치해석을 수행하였다. 평판형 구조의 SOFC 에서 가스채널과 리브폭 변화에 따른 성능과 온도균일성에 관한 연구가 이루어졌다. 전산해석 툴로서는 공개소스 전산유체해석 툴박스인 OpenFOAM 을 이용하였다. 수치해석결과, 산소고갈이 일어나지 않는 범위 내에서 가스채널과 리브폭의 증가는 성능과 온도 균일성에 크게 영향을 미치지 않음을 알 수 있었다. 하지만 넓은 리브폭의 사용과 고전류밀도에서의 작동은 산소고갈로 인한 성능저하의 가능성이 있음을 확인하였다.

• 한국정보통신학회논문지
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• 제22권4호
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• pp.664-669
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• 2018

본 연구는 투명산화물반도체의 전기적인 특성과 산소공공과의 관계를 알아보기 위해서 $TiO_2$ 박막을 증착하여 MIM 구조를 만들어서 전압전류 특성을 관찰하였다. 산소공공은 XPS분석으로 이루어졌으며, 커패시턴스를 측정하여 전하의 용량이 많은 곳에서 산소공공이 어떤 영향을 주는가에 대하여도 조사하였다. 열처리를 통하여 결정질구조로 변하는 $TiO_2$ 박막은 산소공공이 가장 낮은 곳에서 커패시턴스 값이 가장 높았으며, 전하의 양이 많았다. 따라서 전하의 양이 많은 $TiO_2$박막이 $CO_2$ 가스에 대하여 가장 잘 민감하게 반응하는 것을 확인하였다.

• Journal of Photoscience
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• 제9권2호
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• pp.376-378
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• 2002

Role of cl$^{[-10]}$ in photosynthetic oxygen-evolving complex was studied by light-induced Fourier transform infrared (FTIR) spectroscopy. cl$^{[-10]}$ depletion resulted in the suppression of amide I and amide II IR modes upon S$_1$ to S$_2$ transition. Br$^{[-10]}$ , 1$^{[-10]}$ and N0$_3$$^{[-10]}$ substituted FTIR difference spectra were very similar to that in cl$^{[-10]}$ reconstitution. F$^{[-10]}$ and $CH_3$COO$^{[-10]}$ substituted spectra were largely distorted. We succeeded in detecting the structural change of N0$_3$ $^{[-10]}$ in the cl$^{[-10]}$ site upon the S$_1$ to S$_2$ transition from $^{14}$ N0$_3$$^{[-10]}$ /$^{15}$ N0$_3$$^{[-10]}$ difference spectrum.

• Food Science and Biotechnology
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• 제18권2호
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• pp.413-418
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• 2009

Effects of chlorophyll and visible light exposure on the volatile formations and headspace oxygen content were studied in lard model systems at $55^{\circ}C$. Samples with or without addition of chlorophyll under light underwent photosensization or photooxidation, respectively. Total volatiles (TI) in lard with 5 ppm chlorophyll photosensization were 19 times higher than those in visible light photooxidized samples for 48 hr while TI in lard with chlorophyll in the dark were not significantly different from those in photooxidized samples (p>0.05). Headspace oxygen content in photosensitized lard decreased from 21 to 15% for 48 hr but that in photooxidized lard or that in lard with chlorophyll in the dark did not change significantly (p>0.05), which indicates that lard system used in this study is a photosensitizer-free model system and the presence of chlorophyll accelerated the lipid oxidation only under visible light. Oxidation mechanisms of photooxidation with or without presence of photosensitizers under visible light were not the same based on the difference of oxidized volatile profiles and headspace oxygen depletion.

• The Korean Journal of Physiology and Pharmacology
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• 제2권4호
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• pp.427-433
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• 1998

In brain hypoxic-ischemia, an excess release of glutamate and a marked production of reactive oxygen species (ROS) occur in neuronal and non-neuronal cells. The present study investigated the effect of the biological antioxidants dihydrolipoic acid (DHLA) and lipoic acid (LA) on N-methyl-D-aspartate (NMDA)- and ROS-induced neurotoxicity in cultured rat cortical neurons. DHLA enhanced NMDA-evoked rises in intracellular calcium concentration ($[Ca^{2+}]_i$). In contrast, LA did not alter the NMDA-evoked calcium responses but decreased after a brief treatment of dithiothreitol (DTT), which possesses a strong reducing potential. Despite the modulation of NMDA receptor-mediated rises in $[Ca^{2+}]_i$, neither DHLA nor LA altered the NMDA receptor-mediated neurotoxicity, as assessed by measuring the amount of lactate dehydrogenase released from dead or injured cells. DHLA, but not LA, prevented the neurotoxicity induced by xanthine/xanthine oxidase-generated superoxide radicals. Both DHLA and LA decreased the glutathione depletion-induced neurotoxicity. The present data may indicate that biological antioxidants DHLA and LA protect neurons from ischemic injuries via scavenging oxygen free radicals rather than modulating the redox modulatory site(s) of NMDA receptor.