• Asian-Australasian Journal of Animal Sciences
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• v.13 no.6
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• pp.748-756
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• 2000

Effects of xanthine (X), xanthine oxidase (XO), and catalase (C), $H_2O_2$, and carbohydrates on sperm capacitation, acrosome reaction, and fertilizing ability in vitro were examined. Glucose alone, but not fructose, supported the maximum rate of sperm capacitation and acrosome reaction. However, in the combination of X, XO, and C (XXOC) or $H_2O_2$, fructose alone also supported maximum capacitation, acrosome reaction, and fertilization. Either insufficient or excessive amounts of $H_2O_2$ decreased sperm capacitation and the acrosome reaction. In order to understand how glucose generates $H_2O_2$ or other reactive oxygen species in sperm cells, 6-aminonicotinamide, an inhibitor of the pentose-phosphate pathway (PPP), and apocynin, an inhibitor of NADPH oxidase, were added to sperm suspensions in glucose-containing medium. Results appeared that sperm capacitation, acrosome reaction, and fertilization were consequently inhibited by either one of these compounds. These inhibitory effects were nullified by addition of XXOC. These results support the hypothesis that glucose, in addition to being a substrate for glycolysis, facilitates sperm capacitation and the acrosome reaction by generating reactive oxygen species through G-6-P dehydrogenase and NADPH oxidase.

• Journal of Power System Engineering
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• v.10 no.3
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• pp.5-10
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• 2006

In a conventional and lean operating engine, the state of mixture is very important in the combustion and emission characteristics. Lean operation is known to decrease the formation while maintaining a good fuel economy, but the unstable operation due to misfire and erratic combustion prevents engines from being operated at very lean mixtures, so both combustion rates and exhaust emission formation need to be satisfied comparably. In this study, it is designed and experimented the modified engine, and analyzed the combustion and exhaust emission according to the change of engine speed and with adding ozone. The conclusions were drawn out and enumerated as follows. 1. At the experimental result of automobile diesel engine, it has been verified that the formation of particulate matter(PM) gas is able to be lower with the addition of optimum quantities of ozone. 2. Carbon monoxide(CO) was formed by the lack of oxygen and the thermal dissociation in the combustion process. Therefore, with the change of swirl valve's position and addition of oxygen and ozone, CO formation was decreased by the increasing of excessive O2, but it was increased by the temperature of combustion gas growing higher. As a result of the two effects, CO formation was decreased in this study. 3. Hydrocarbon(HC) was formed by the lack of O2, and the flow of mixture in cylinder. According to opening of the swirl valve and adding the oxygen and ozone, hydrocarbon gas was decreased by 20%, 9%, and 27.5%, respectively. 4. Nitric oxides($NO_x$) was strongly affected by the combustion gas temperature. As a result of respectively experimental conditions, $NO_x$ formation was increased about 20% due to (be the) high(er) combustion gas temperature.

• Environmental Engineering Research
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• v.25 no.2
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• pp.230-237
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• 2020

Nitrogen flux release from organically enriched sediments into overlying water, which may have significantly influence on water quality and increasing continuous eutrophication. The purpose of this study is to evaluate the remediation efficiency of oyster shell powder and its treated product into organically enriched sediment in terms of nitrogen flux, organic matter, chlorophyll-a, pH and dissolved oxygen (DO). The TOSP was mainly composed of CaO2. The application of TOSP into the sediment has increased the pH, DO and significantly decreased the concentrations of NH₄⁺-N and T-N compared to other basins. On the other hand, nitrate was enriched with the addition of treated oyster powder, an oxygen releasing compound on both phases. Furthermore, chlorophyll-a was found to be increasing with time in the control basin meanwhile it dropped drastically with the addition of TOSP, which implied on the repression of algal growth owing to blockage of nitrogen source migrating from the sediment. This study has shown that the TOSP was effective to improve sediment-water quality, diminish eutrophication and control harmful algae blooms in a marine environment. Therefore, it is a good reference as an effective environmental remediation agent.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.179-182
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• 2001

The chloride volatilization method for the recovery of zirconium and removal of uranium from zirconium containing metallic wastes formed in spent fuel reprocessing was studied using the simulated alloy waste, i.e. the mixture of Zr foil and UO$_2$/U$_3$O$_{8}$ powder. When the simulated waste was heated to react with chlorine gas at 350- l00$0^{\circ}C$, the zirconium metal changed to volatile ZrCl$_4$showing high volatility ratio (Vzr) of 99%. The amount of volatilized uranium increases at higher temperatures causing lowering of decontamination factor (DF) of uranium. This is thought to be caused by the chlorination of UO$_2$ with ZrCl$_4$vapor. The highest DF value of 12.5 was obtained when the reaction temperature was 35$0^{\circ}C$. Addition of 10 vol.% oxygen gas into chlorine gas was effective for suppressing the volatilization of uranium, while the volatilization ratio of zirconium was decreased to 68% with the addition of 20 vol.% oxygen. In the case of the mixture of Zr foil and U$_3$O$_{8}$, the V value of uranium showed minimum (44%) at 40$0^{\circ}C$ with chlorine gas giving the highest DF value 24.3. When the 10 vol.% oxygen was added to chlorine gas, the V value of zirconium decreased to 82% at $600^{\circ}C$, but almost all the uranium volatilized (Vu=99%), which may be caused by the formation of volatile uranium chlorides under oxidative atmosphere.ere.

• Corrosion Science and Technology
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• v.7 no.1
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• pp.45-49
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• 2008

The cyclic polarisation technique was applied to determine the corrosion, primary-passivation, transpassive, and protection potential of AISI 316L stainless steels immersed in 3550-ppm NaCl solution containing sulfate in the content up to 3000 ppm. The solutions were kept constant at $27^{\circ}C$ and saturated by laboratory air. The solution pH was varied from 3 to 11. Each type of potentials was plotted in function of pH and linked as lines to determine the different zones in the constructed potential-pH diagram. The predominant regimes of the immunity, general corrosion, perfect passivation, imperfect passivation, and pitting corrosion were determined based on those lines of potentials. Comparing to the potential-pH diagram of specimens immersed in the aerated and deaerated 3550-ppm NaCl solutions, the addition of 3000-ppm $Na_2SO_4$ to these solutions increased the overall, perfect and imperfect, passivation regime by shifting the transpassive-potential line to the noble direction. However, it also widened the imperfect passivation area. The addition of $Na_2SO_4$ did not significantly affect the corrosion potential. It was found that the dissolved oxygen tends to negatively shift the transpassive-potential and protection-potential lines at all studied pH. The considerable effect of dissolved oxygen on corrosion and primary-passivation potentials could not be observed.

• Radiation Oncology Journal
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• v.28 no.4
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• pp.211-218
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• 2010

Purpose: All-trans retinoic acid (ATRA) has anti proliferative effects against brain tumor cells. Recently, ATRA has been reported to induce catalase. We investigated whether catalase induction by ATRA is associated with its anti proliferative effects. Materials and Methods: 36B10 cells were exposed to 0~50${\mu}M$ ATRA for 24 or 48 hours and mRNA, protein, and activity of catalase were measured. Reactive oxygen species (ROS) were measured using 2',7'-dichlorofluorescin diacetate. A clonogenic assay was used to confirm the cytotoxic effect. Results: The mRNA, protein, and activity of catalase were found to increase in a concentration- and incubationtime-dependent manner. The increase in catalase activity induced by ATRA was decreased by the addition of 3-amino-1,2,4-triazole (ATZ). ROS was also increased with ATRA and decreased by the addition of ATZ. The decrease in cell survival induced by ATRA was partly rescued by ATZ. Conclusion: Catalase induction by ATRA is involved in ROS overproduction and thus inhibits the proliferation of 36B10 cells.

• Journal of the Korean Chemical Society
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• v.61 no.6
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• pp.352-358
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• 2017

The addition of alginic acid, a natural polysaccharide, to improve the wettability and the reduction of protein adsorption of hydrogel contact lenses. Hydrogel contact lenses were manufactured with various monomers such as 2-methacryloyloxyethyl phosphorylcholine (MPC) and NVP (N-Vinyl-2-pyrrolidone). Alginic acid was added by by the initial mixing method and the interpenetrating polymer networks(IPN) method. Properties of contact lens such as contact angle, oxygen permeability, and protein adsorption amount were evaluated. The oxygen permeability and wettability of the IPN-treated alginate samples were higher than those of the samples that were not treated with IPN. The physical properties were improved as the concentration of IPN-treated alginic acid increased. Protein adsorption decreased by the addition of alginic acid and further decreased with IPN. In particular, contact lenses containing MPC and NVP significantly decreased protein adsorption. Therefore, the effect of alginate on the functional improvement of contact lens was confirmed.

• Resources Recycling
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• v.28 no.3
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• pp.59-67
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• 2019

This study was conducted to fabrication pig iron containing copper and to reduce sulfur content pig iron. Roasting test was conducted for 1 ~ 9 hours at each temperature of $500^{\circ}C$, $700^{\circ}C$, and $900^{\circ}C$. In addition, the effect of oxygen partial pressure with 0.5, 0.8, and 1 atm was carried out for 30 minutes at $900^{\circ}C$. It was found that there is no effect to reduce sulfure in pig iron through roasting and oxygen partial pressures. The addition of CaO with 15 wt.% was found to reduce sulfur content up to 0.001 wt.%. The suitable temperature and reactive time for carbothermic reduction were $1600^{\circ}C$ and 30 minutes which shows the highest recovery rate of iron from the copper slag.

• Journal of Powder Materials
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• v.26 no.6
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• pp.455-462
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• 2019

ZrB₂ ceramic and ZrB₂ ceramic composites with the addition of SiC, WC, and SiC/WC are successfully synthesized by a spark plasma sintering method. During high-temperature oxidation, SiC additive form a SiO₂ amorphous outer scale layer and SiC-deplete ZrO₂ scale layer, which decrease the oxidation rate. WC addition forms WO₃ during the oxidation process to result in a ZrO₂/WO₃ liquid sintering layer, which is known to improve the anti-oxidation effect. The addition of SiC and WC to ZrB₂ reduces the oxygen effective diffusivity by one-fifth of that of ZrB₂. The addition of both SiC and WC shows the formation of a SiO₂ outer dense glass layer and ZrO₂/WO₃ layer so that the anti-oxidation effect is improved three times as much as that of ZrB₂. Therefore, SiC- and WC-added ZrB₂ has a lower two-order oxygen effective diffusivity than ZrB₂; it improves the anti-oxidation performance 3 times as much as that of ZrB₂.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.127-134
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• 2014

This study was performed to evaluate the effects of sesame oil addition to a tuna oil-enriched emulsion during chlorophyll-photosensitized oxidation. The emulsion principally consisted of tocopherol-stripped canola and tuna oil with or without sesame oil, acetic acid, phospholipids, and xanthan gum. Chlorophyll b was added to promote the production of singlet oxygen upon exposure to light. The oxidation of oil in the emulsion was evaluated by determining the peroxide value (POV) and conjugated dienoic acid (CDA) contents. Concentrations of minor compounds in the emulsion were monitored. Increasing POV and CDA contents in the emulsion were paralleled with decreased docosahexaenoic acid during oxidation, and oxidation was inhibited by the addition of sesame oil. Chlorophyll, polyphenols, tocopherol, and phospholipids were degraded during oxidation of the emulsion; however, their degradation was slowed down by the addition of sesame oil. Lignans in the emulsions containing added sesame oil were barely changed, suggesting that they quenched singlet oxygen physically. Polyphenols were the most effective in improving the stability of tuna oil-enriched emulsions during chlorophyll-photosensitized oxidation.