• Proceedings of the PSK Conference
• /
• 2003.04a
• /
• pp.268.1-268.1
• /
• 2003

Brazilin is the phenolic compound isolated from the Caesalpinia sappan. This compound has shown a wide range of physiological properties, such as hypoglycemic, anticonvulsant, vasorelaxing, and immunomodulating effects. In this study, we have found that brazilin induced DNA strand scissions in the presence of Cu(II) and this DNA cleavages were mediated by reactive oxygen species. (omitted)

• Journal of the Korean institute of surface engineering
• /
• v.51 no.2
• /
• pp.133-137
• /
• 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).

• Proceedings of the PSK Conference
• /
• 2005.11a
• /
• pp.89-90
• /
• 2005

• Journal of Environmental Science International
• /
• v.27 no.10
• /
• pp.901-906
• /
• 2018

Water and oxygen are two of the most essential molecules for many species on earth. Their unique properties have been studied in many areas of science. In this study, the interaction of water and oxygen molecules was observed at the nano-scale. Using molecular dynamics, a water droplet with 30,968 water molecules was simulated. Then, 501 oxygen molecules were introduced into the domain. A few oxygen molecules were attracted to the surface of the water droplet due to van der Waals forces, and some oxygen molecules actually entered the water droplet. These interactions were visualized and quantified at four temperatures ranging from 280 to 370 K. It was found that at high temperatures, there was a higher possibility of the oxygen molecules penetrating the water droplet than that at lower temperatures. However, at lower temperatures, oxygen molecules were more likely to be found interacting at the surface of the water droplet than at high temperatures.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.180-180
• /
• 1999

The interaction of oxygen with a Ni(100) surface has been investigated using X-ray Photoelectron Spectroscopy (XPS) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) technique. Below 200L oxygen exposure, molecular oxygen was dissociated to atomic oxygen. Increasing oxygen exposure, -1s binding energy shifted from 531.0 eV to 533.0 eV due to molecular adsorption. The presence of molecular oxygen species was confirmed by NEXAFS. Molecular oxygen adsorbed on Ni(100) was oriented perpendicular to the surface. Upon heating over 150K molecular adsorbed oxygen surface was also analyzed using NEEXFS.

• YAKHAK HOEJI
• /
• v.37 no.6
• /
• pp.647-658
• /
• 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.

• Proceedings of the Korean Radioactive Waste Society Conference
• /
• 2004.06a
• /
• pp.105-114
• /
• 2004

This study investigated the thermal behavior of the nuclear graphite waste generated from the decommissioning of the Korean nuclear research reactor, The first part study investigated the decomposition rate of the nuclear graphite waste up to $1000^{\circ}C$ under various oxygen partial pressures using a thermo-gravimetric analyzer (TGA). Tested graphite waste sample not easily destroyed in the oxygen-deficient condition. However, the gas-solid oxidation reaction was found to be very effective in the presence of oxygen. No significant amount of the product of incomplete combustion was formed even in the limited oxygen concentration of 4% $O_2$. The influence of temperature and oxygen partial pressure was evaluated by the theoretical model analysis of the thermo-gravimetric data. The activation energy and the reaction order of graphite oxidation were evaluated as 128 kJ/mole and 1.1, respectively. The second part of this study investigated the behavior of radioactive elements under graphite oxidation atmosphere using thermodynamic equilibrium model. $^{22}Na$, $^{134}Cs$ and $^{137}Cs$ were found be the semi-volatile elements. Since volatile uranium species can be formulated at high temperatures above $1050^{\circ}C$, the temperature of incinerator furnace should be minimized. Other corrosion/activation products, fission products and uranium were found to be the non-volatile species.

• Journal of Microbiology and Biotechnology
• /
• v.19 no.3
• /
• pp.299-306
• /
• 2009

Dissolved oxygen (DO) has a significant effect on the molecular weight of hyaluronic acid (HA) during the fermentation of Streptococcus zooepidemicus. Therefore, to further investigate the effect of DO on the yield and molecular weight of HA, this study compared the metabolic flux distribution of S. zooepidemicus under aerobic conditions at various DO levels. The metabolic flux analysis demonstrated that the HA synthesis pathway, considered a dependent network, was little affected by the DO level. In contrast, the fluxes of lactate and acetate were greatly influenced, and more ATP was generated concomitant with acetate at a high DO level. Furthermore, the has gene expression and HA synthase activity were both repressed under anaerobic conditions, yet not obviously affected under aerobic conditions at various DO levels. Therefore, it was concluded that the HA molecular weight would seem to depend on the concomitant effect of the generation of ATP and reactive oxygen species. It is expected that this work will contribute to a better understanding of the effect of the DO level on the mechanism of the elongation of HA chains.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.06a
• /
• pp.81-86
• /
• 2005

The purpose of this study is to develop venturi type after-burner in order to obtain pollutant reduction effect and find the best stable combustion condition. For this purpose, through a flow analysis, the shape of venturi type was made and flame holder locations were also decided by measuring chemical species at before and after the after-burner. Also, various chemical species concentration were measured at changing the induced air rates and the oxygen for oxygen enrichment for the solution the problems of much oxygen flow rate and the flame stability range. As results of this study, a flow distribution and the purification effect was excellent at venturi contraction 0.5 and flame holder location 12mm below the center of Venturi throat. On the purification characteristics, we found that pollutants reduction was effective when area ratio and oxygen are increased. But there are suitable quantities due to the flame shape change and combustion efficiency.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.18 no.6
• /
• pp.1825-1831
• /
• 2004

Phellinus linteus is known as a medicinal mushroom, which has the pharmaceutical activity on tumors and inflammatory diseases in traditional Oriental medicine. However, despite extensive pharmacological studies on P. linteus, the liquor of fermentation using mycelium of P. linteus(LFMP) has not been investigated. In the present study, it was examined the effect of the evaporating extract from LFMP(E-LFMP) on the expression of inflammatory proteins and the generation of reactive oxygen species in human hepatocarcinoma HepG2 cells. E-LFMP inhibited acetaldehyde-induced morphological change in HepG2 cells. Also, E-LFMP inhibits expression of inflammatory proteins including cyclooxygenase(COX)-1 and COX-2 through suppressing nuclear translocation of nuclear factor κB(NF-κB) and degradation of inhibitory κBα(IκBα). In addition, E-LFMP inhibits generation of reactive oxygen species(ROS) by hydrogen peroxide(H₂O₂) in HepG2 cells. These results suggest that LFMP has the pharmaceutical, especially anti-inflammatory, activity similar to P. linteus mushroom.