• Natural Product Sciences
• /
• 제5권4호
• /
• pp.165-171
• /
• 1999

Since reactive oxygen species (ROS) play an important role in carcinogenesis and other several human diseases, antioxidants present in consumable fruits, vegetables, and beverages have received considerable attention as cancer chemopreventive agents. Thus, in order to identify antioxidants in plant extracts, potential activity was assessed by determining with inhibition of a xanthine/xanthine oxidase assay system. Approximately 170 plant extracts of Korean herbal medicines were primarily evaluated for the potential of antioxidant activity. As a result, 13 plant extracts were found to be active $(IC_{50}$<$100\;{\mu}g/ml)$. Especially, Juncus effusus, Selaginella tamariscina, Pueraria thunbergiana and Sedum albroseum showed strong inhibitory activity in this process. Further studies for the identification of active principles from these active lead plant extracts might be warranted.

• Transactions on Electrical and Electronic Materials
• /
• 제10권1호
• /
• pp.5-8
• /
• 2009

The reliability of multilayer ceramic capacitor with active thin dielectric layer was investigated by highly accelerated life test at various stress condition. The distribution of multilayer ceramic capacitor failure times is plotted as a function of time from Weibull distribution function. According to the test result, voltage acceleration factor is obtained from 2.24 to 2.96. The acceleration by temperature is much higher than other values of active thick dielectric layer. It is clear that median time to failure is affected by the stress voltage for high volumetric efficiency ceramic capacitors with active thin dielectric layer. The degradation under stress of voltage involves electromigration and accumulation of oxygen vacancy at Ni electrode interface of cathode.

• Bulletin of the Korean Chemical Society
• /
• 제23권7호
• /
• pp.985-989
• /
• 2002

For efficient biopulping process, very active and stable lignase is essential. Laccase is one of the best enzyme in terms of environmentally benign processes, since the enzyme uses oxygen as an oxidant to degrade lignin and produces no hamful prod ucts. We could purify a laccase homogeneously from Cerrena unicolor in a very active state. It shows characteristic absorption feature with blue band at λmax = 604 ㎚. Molecular weight of the enzyme is 57,608 which could be accurately determined by MALDI/TOF MS. The enzyme has 2.8 copper ions per enzyme implying apoenzymes might exist together. The enzyme is active in lignin degradation and the activity increases 4 times in the presence of ABTS as a mediator.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
• /
• pp.318-321
• /
• 2009

We have studied transparent top gate Al-Zn-Sn-O (AZTO) TFTs with an $Al_2O_3$ protective layer (PL) on an active layer. We also fabricated a transparent 2.5 inch QCIF+AMOLED display panel using the AZTO TFT back-plane. The AZTO active layers were deposited by RF magnetron sputtering at room temperature and the PL was deposited by ALD with two different processes. The mobility and subthreshold slope were superior in the cases of the vacuum annealing and the oxygen plasma PL compared to the $O_2$ annealing and the water vapor PL, however, the bias stability was excellent for the TFTs of the $O_2$ annealing and the water vapor PL.

• Journal of Microbiology and Biotechnology
• /
• 제17권1호
• /
• pp.110-115
• /
• 2007

Electrochemically active bacteria were successfully enriched in an electrochemical cell using a positively poised working electrode. The positively poised working electrode (+0.7 V vs. Ag/AgCl) was used as an electron acceptor for enrichment and growth of electrochemically active bacteria. When activated sludge and synthetic wastewater were fed to the electrochemical cell, a gradual increase in amperometric current was observed. After a period of time in which the amperometric current was stabilized (generally 8 days), linear correlations between the amperometric signals from the electrochemical cell and added BOD (biochemical oxygen demand) concentrations were established. Cyclic voltammetry of the enriched electrode also showed prominent electrochemical activity. When the enriched electrodes were examined with electron microscopy and confocal scanning laser microscopy, a biofilm on the enriched electrode surface and bacterium-like particles were observed. These experimental results indicate that the electrochemical system in this study is a useful tool for the enrichment of an electrochemically active bacterial consortium and could be used as a novel microbial biosensor.

• KSBB Journal
• /
• 제16권4호
• /
• pp.351-355
• /
• 2001

호흡율 측정법을 이용하여 하수의 유기물 성분을 ASM No.1에서 제안한 네 가지 성분으로 구분하였다. Ss의 경우 전체 TCOD의 10-16%, Xs의 경우 32-50%, S$_1$의 경우 8-1% 정도를 차지하는 것으로 나타났으며, X$_1$의 경우 2-47% 정도를 차지하는 것으로 관찰되었다. 그리고 이 결과는 외국의 결과와 비교해 볼 때 Ss 성분이 10% 작을 반면 X$_1$ 성분은 10% 정도 큰 것으로 비교되었다. 하수의 미생물 농도를 분석한 결과, active heterotrophic biomass가 TCOD의 10-23% 정도를 차지하고 있었으며, active autotrophic biomass는 검출되지 않았다. 본 실험은 현재 TCOD, SCOD로 구분하는 하수의 유기물 성분을 미생물의 이용 정도를 나타내는 호흡률 측정법으로 세분화함으로서, 본 실험 방법을 이용하여 유기물 분해 과정 및 탈질화 그리고 인 제거 기작에 사용되는 유기물에 대한 정보를 구체적으로 제공할 수 있음을 보여 주었다.

• 한국환경과학회지
• /
• 제20권12호
• /
• pp.1509-1519
• /
• 2011

The protective effect of nitric oxide (NO) on the antioxidant system under paraquat(PQ) stress was investigated in leaves of 8-week-old lettuce (Lactuca sativa L.) plants. PQ stress caused a decrease of leaf growth including leaf length, width and weight. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated PQ stress induced growth suppression. SNP permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem II than in non-treated controls under PQ exposure, suggesting that NO has protective effect on chloroplast membrane in lettuce leaves. Flavonoids and anthocyanin were significantly accumulated in the leaves upon PQ exposure. However, the rapid increase of these compounds was alleviated in the SNP treated leaves. PQ treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide ($H_2O_2$) in the leaves, while SNP prevented PQ induced increase in malondialdehyde (MDA) and $H_2O_2$. These results demonstrate that SNP serves as an antioxidant agent able to scavenge $H_2O_2$ to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, superoxide dismutase (SOD) and catalase (CAT) in lettuce leaves in the presence of NO donor under PQ stress were higher than those under PQ stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, to the lettuce leaves arrested SNP mediated protective effect on leaf growth, photosynthetic pigment and antioxidant systems. However, PTIO had little effect on lettuce leaves under PQ stress compared with that of PQ stress alone. The obtained data suggest that the damage caused by PQ stress is in part due to increased generation of active oxygen by maintaining increased antioxidant enzyme activities and SNP protects plants from oxidative stress. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative damage induced by PQ stress and thus confer PQ tolerance.

• 대한추나의학회지
• /
• 제1권1호
• /
• pp.91-102
• /
• 2000

To prove the effect of Yukmijihwngwon(YMJHW) and Taeyoungjeon(TYJ) extract on the Meridian of Human body and Active oxygen experimentally, ORS & Free Radical of extract and precipitate of YMJHW and TYJ was measured. The results were summarized as follows; 1. TYJ extract, as a result of measuring QRIS, had a considerable effect on the function of pituitary gland, the 4th cervical vertebra and the 1 st lumbar vertebra. 2. TYJ precipitate, as a result of measuring QRIS, had a considerable effect on the function of liver, uterus, and vertebra. 3. YMJHW extract, as a result of measuring QRIS, had a considerable effect on the function of lung, adrenalin gland, bladder, prostate gland, ovaria, the 2nd cervical vertebra, the 3rd cervical vertebra, the 5th cervical vertebra, the 6th cervical vertebra, the 2nd lumbar vertebra, the 4th lumbar vertebra and the 5th lumbar vertebra. 4. YMJHW precipitate, as a result of measuring QRIS, had a considerable effect on the function of spleen, lung, kidney, adrenal gland, bladder, ovaria, the 2nd cervical vertebra, the 6th cervical vertebra, the 7th cervical vertebra, the 2nd lumbar vertebra, the 5th lumbar vertebra, sacrum, and knee joint. 5. As a result of measuring Free Radical, the level of TYJ is higher than YMJHW. It is thiut that's because of Duchung and roasted Gamcho. 6. As an order of QRIS levels, YMJHW precipitate is the highest, YMJHW extract is next, TYJ extract and TYJ precipitate. These results suggested that TYJ and YMJHW be usefully applied for suppressing of abnormal Meridian and noxious oxygen, preventing and curing all the disease.

• Natural Product Sciences
• /
• 제3권1호
• /
• pp.19-28
• /
• 1997

Constitutive cyclooxygenase (COX-I) is present in cells under physiological conditions, whereas inducible cyclooxygenase (COX-II) is induced by some cytokines, mitogens, and endotoxin presumably in pathological conditions such as inflammation. We have evaluated the inhibitory effects of solvent fractionated extracts of natural products on the activities of COX-I and COX-II. Oxygen uptake COX assay was performed, as a primary screening from the tissue extracts of bovine seminal vesicles (BSV), by monitoring the initial rate of oxygen uptake using an oxygen electrode. Additionally, we evaluated plant extracts for the inhibitory effects of COX-I (in HEL cells) and COX-II (in lipopolysaccharide activated J774A.1 macrophages) using thin layer chromatography of prostanoids produced from $^{14}C-labelled$ arachidonic acid (AA). The use of such models of COX-I and COX-II assay will lead to the identification of specific inhibitors of cyclooxygenases with presumably less side effects than present therapies. Inhibitory effects of 50 kinds of plant extracts on the COX-I and COX-II activities were determined and the active fractions were found in the ethyl acetate fractions of Dryopteris crassirhizoma (roots), Amomum cardamomum (roots), Triticum aestivum (seeds), Perilla sikokiana (leaves), Anemarrhena asphodeloides (roots). Especially, the ethyl acetate fraction of Dryopteris crassirhizoma (roots), which exhibited the strong inhibition against BSV COX $(IC_{50},\;65.4\;{\mu}g/ml)$, COX-I $(IC_{50},\;8.5\;{\mu}g/ml)$, and COX-II $(IC_{50},\;17.2\;{\mu}g/ml)$, is under investigation to isolate active principles using activity-guided fractionation method.

• 대한기계학회논문집B
• /
• 제30권5호
• /
• pp.405-412
• /
• 2006

In order to realize a stably propagating flame in a narrow channel, flame instabilities resulting from flame-wall interaction should be avoided. In particular flame quenching is a significant issue in micro combustion devices; quenching is caused either by excessive heat loss or by active radical adsorptions at the wall. In this paper, the relative significance of thermal and chemical effects on flame quenching is examined by means of quenching distance measurement. Emphasis is placed on the effects of surface defect density on flame quenching. To investigate chemical quenching phenomenon, thermally grown silicon oxide plates with well-defined defect distribution were prepared. ion implantation technique was used to control defect density, i.e. the number of oxygen vacancies. It has been found that when the surface temperature is under $300^{\circ}C$, the quenching distance is decreased on account of reduced heat loss; as the surface temperature is increased over $300^{\circ}C$, however, quenching distance is increased despite reduced heat loss effect. Such abberant behavior is caused by heterogeneous surface reactions between active radicals and surface defects. The higher defect density, the larger quenching distance. This result means that chemical quenching is governed by radical adsorption that can be parameterized by oxygen vacancy density on the surface.