• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.118-125
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• 2019

Metals exposed to high temperature/high pressure/oxidant excess environment of an oxygen excess pre-combustor may undergo rapid oxidation. In this study, the test facility to simulate the high temperature/high pressure/oxidant excess environment was constructed and the oxidation resistance evaluation was carried out for various metal materials. As a result, the discoloration of the metallic materials, the change in the surface roughness and the peeling of the metal surface were observed, and the weight change was also observed. The resulst showed that oxidation-resistant coating of a metal material of the combustor is indispensably required, and the use of XM-19, which has the highest content of Cr and Ni, is expected to provide more structural stability.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.51-56
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• 2001

$CeO_2$ thin films as insulator for MFISFET (Metal-ferroelectric-insulator- semiconductor-field effect transistor) were deposited by r.f. magnetron sputtering. Ar and $O_2$ gas as the deposition gas were used and the effects of oxygen partial pressure during sputtering on texture and electrical properties of $CeO_2$ thin films were evaluated. All $CeO_2$ thin films deposited on p-type Si(100) substrate at $600^{\circ}C$ exhibited (200) preferred orientation. The films deposited with only Ar gas among various condition had highest preferred orientation but show large hysteresis characteristics in capacitance-voltage measurement due to relatively many charged paricles and roughness. Films show smooth surface state and good C-V characteristics with increasing oxygen partial pressure. It was thought that this trend in C-V characteristics was due to the amount of mobile ionic charge within $CeO_2$ films. The composition of films show oxygen excess, that is, O/$Ce_2$ ratio of films was 2.22~2.42 range and leakage current of films show $10^{-7}~10^{-8}A$order at 100 kV/cm.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.46-51
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• 2004

The film coated snap bean (Phaseolus vulgaris) seeds with five different coating materials treated with 3% increase in seed weight were planted at sandy loam soil controlled moisture content of 18, 19, 20 and 21 %. The oxygen diffusion rate (ODR) was calculated from the different moisture content soil. The number of normal seedlings, seedling vigor, and seedling capability in field (seed vigor x dry matter weight) were observed at 9 days after planting and compared to the changes of ODR. The germination rate and ODR were sharply decreased simultaneously in the seeds planted at 21 % soil moisture content. Seedling emergence did not occur at all as the soil moisture content increased above 22 %. Hence this value should be considered as the threshold of soil moisture content for seedling emergence. An ODR value under 20% did not influence the percent emergence significantly. The certain difference observing in the emergence at the same ODR was not related clearly to the condition of soil. So it can be assumed that the limit of soil moisture content for the emergence of snap bean was approximately 20%. The value of 18% soil moisture content may be considered as the optimum for snap bean emergence. There was close relationship between the mean value of ODR in different soil moisture contents and the emergence. The germination rates of the seeds coated with the different materials were quite different when the seeds were planted at 21 % soil moisture. Dry weight of the seedlings from film coated seeds was decreased slightly, but the germination rates were not much different from the non-treated control under relatively higher soil moisture content (21 %). Major factor lowering emergence rate was oxygen stress while film coating act as a minor constraint for snap bean sown in excess soil moisture condition.

• Clinical and Experimental Pediatrics
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• v.55 no.7
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• pp.238-248
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• 2012

Purpose: Hypoxic-ischemic encephalopathy is an important cause of neonatal mortality, as this brain injury disrupts normal mitochondrial respiratory activity. Carnitine plays an essential role in mitochondrial fatty acid transport and modulates excess acyl coenzyme A levels. In this study, we investigated whether treatment of primary cultures of rat cortical neurons with L-carnitine was able to prevent neurotoxicity resulting from oxygen-glucose deprivation (OGD). Methods: Cortical neurons were prepared from Sprague-Dawley rat embryos. L-Carnitine was applied to cultures just prior to OGD and subsequent reoxygenation. The numbers of cells that stained with acridine orange (AO) and propidium iodide (PI) were counted, and lactate dehydrogenase (LDH) activity and reactive oxygen species (ROS) levels were measured. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and the terminal uridine deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay were performed to evaluate the effect of L-carnitine (1 ${\mu}M$, 10 ${\mu}M$, and 100 ${\mu}M$) on OGD-induced neurotoxicity. Results: Treatment of primary cultures of rat cortical neurons with L-carnitine significantly reduced cell necrosis and prevented apoptosis after OGD. L-Carnitine application significantly reduced the number of cells that died, as assessed by the PI/AO ratio, and also reduced ROS release in the OGD groups treated with 10 ${\mu}M$ and 100 ${\mu}M$ of L-carnitine compared with the untreated OGD group (P<0.05). The application of L-carnitine at 100 ${\mu}M$ significantly decreased cytotoxicity, LDH release, and inhibited apoptosis compared to the untreated OGD group (P<0.05). Conclusion: L-Carnitine has neuroprotective benefits against OGD in rat primary cortical neurons in vitro.

• Journal of Ecology and Environment
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• v.41 no.9
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• pp.235-245
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• 2017

Background: Loading of excess nutrient via bioremediation of polluted sediment to overlying water could trigger anoxia and eutrophication in coastal area. The aim of this research was to understand the changes of overlying water features such as dissolved oxygen (DO); pH; oxidation reduction potential (ORP); $chlorophyll-{\alpha}$ ($Chl-{\alpha}$); and nitrogen nutrients ammonia ($N-NH_4{^+}$), nitrate ($N-NO_3{^-}$), and nitrite ($N-NO_2^-$) when the sediment was not treated (control) and treated by calcium peroxide for 5 weeks. Methods: The water samples were analyzed for measuring physical and chemical properties along with the sediment analyzed by polymerase chain reaction (PCR) including denaturing gradient gel electrophoresis (DGGE) for identifying the phylogenetic affiliation of microbial communities. Results: Results showed that due to the addition of calcium peroxide in sediment, the overlying water exposed the rise of dissolve oxygen, pH, and ORP than control. Among the nitrogen nutrients, ammonia inhibition was higher in calcium peroxide treatment than control but in case of nitrate inhibition, it was reversed than control. $Chlorophyll-{\alpha}$ was declined in treatment column water by 30% where it was 20% in control column water. Actibacter and Salegentibacter group were detectable in the calcium-peroxide-treated sediment; in contrary, no detectable community ware found in control sediment. Both phylogenetic groups are closely related to marine microflora. Conclusions: This study emphasizes the importance of calcium peroxide as an oxygen release material. Interaction with peroxide proved to be enhancing the formation of microbial community that are beneficial for biodegradation and spontaneity of nutrient attenuation into overlying water.

• Bulletin of the Korean Chemical Society
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• v.18 no.9
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• pp.916-922
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• 1997

A superconducting phase La2CuO4+δ (Tc=44 K) has been prepared by electrochemical oxidation which allows the oxygen to intercalat into the La2O2 layers. According to the Cu K-edge X-ray absorption near edge structure spectroscopic analysis, the oxidized phase shows an overall spectra shift of about 0.5 eV to a higher energy region compared to the as sintered one with the occurrence of an additional peak corresponding to the transition to the |1s13dn+1L-14pσ1 > final state, indicating the oxidation of CuO2 layer. From the X-ray photoelectron spectroscopic studies, it is found that the binding energy of La 3d5/2 is significantly shifted from 834.3 eV (as sintered La2CuO4) to 833.6 eV (as electrochemically oxidized La2CuO4+δ), implying that the covalency of the (La-O) bond is decreased due to the oxygen intercalation. The O 1s spectra do not provide an evidence of the superoxide or peroxide, but the oxide (O2-) with the contaminated carbonate (CO32-) based on the peaks at 529 eV and 532 eV, respectively, which is clearly confirmed by the Auger spectroscopic analysis. Oxygen contents determined by iodometric titration (δ=0.07) and thermogravimetry (δ=0.09) show good coincidence each other, also giving an evidence for the "O2-" nature of excess oxygen. From the above results, it is concluded that "O2-" appeared as O 1s peak at 528.6 eV is responsible for superconductivity of La2CuO4+δ.

• Journal of Photoscience
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• v.9 no.2
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• pp.55-58
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• 2002

The reaction center Dl protein of photosystem II is the target of photodamage by excess illumination. The Dl protein is damaged by reactive oxygen species generated by photochemical reactions and then degraded by specific proteolytic enzymes. We found that the Dl protein also cross-links with the surrounding polypeptides, such as D2 and CP43 in isolated thylakoids or photosystem II-enriched membranes from spinach under the illumination with strong visible light. The cross-linking was observed in spinach leaf discs as well when they were illuminated at higher temperature (40°C). It was also shown that the cross-linked products are digested efficiently by a protease(s) in the stroma. Thus the cross-linking/digestion processes of the Dl protein seem to comprise a new pathway in the turnover of the photodamaged Dl protein. It should be noted, however, that the cross-linked products of the Dl protein and CP43 induced by endogenous cationic radicals in the donor-side photoinhibition are resistant to proteolytic digestion. Accumulation of these cross-linked products in the thylakoids may lead to the decay of the function of chloroplasts and finally to the death of plant cells. Thus, we suggest that the quality control of photosystem II, especially removal of the cross-linked products of the Dl protein, is crucial for the survival of chloroplasts under the light stress.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.561-569
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• 2010

The present study deals with experimental investigations on the syngas-oxygen combustion characteristics of a swirl-stabilized premixed flame in a 10 kW combustor. The effect of hydrogen in syngas has been investigated with different swirl angles to identify the role of hydrogen and swirl strength on the flame stability and CO emissions. The results show that hydrogen addition extended the blowout limit while narrowing the flashback limit. The dependence of blowout on the swirl angle is negligible while the dependence of flashback on the swirl angle is evidenced by two regimes depending on the amount of hydrogen. CO emission is decreased with increasing excess $O_2$ supply or increasing hydrogen content. Chemiluminescence diagnostics is utilized to provide information on the structure of a swirl-stabilized premixed flame. The OH chemiluminescence intensity is more concentrated near the burner exit with an increase in the hydrogen content, which results from high reactivity of hydrogen.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.89-94
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• 2003

For the development of high efficiency and low emission combustion systems, high temperature air combustion technology has been tested by utilizing preheated air over 1100 K and exhaust gas recirculation. In this system, combustion air is diluted with large amount of exhaust gases ($N_2$, $CO_2$), such that the oxygen concentration is relatively low in the reaction zone, leading to low flame temperature. Since, the temperature fluctuations and sound emissions form the flame are small and flame luminosity is low, the combustion mode is expected to be flameless or mild combustion. Experiment was performed to investigate the turbulent flame structure and $NO_X$ emission characteristics in the high temperature air combustion focused on coflowing jet diffusion flames which has a fundamental structure of many practical combustion systems. The effect of turbulence has also been evaluated by installing perforated plate in the oxidizer inlet nozzle. LPG was used as a fuel. Results showed that even though $NO_X$ emission is sensitive to the combustion air temperature, the present high temperature air combustion system produce low $NO_X$ emission because it is operated in low oxygen concentration condition in excess of dilution.

• Journal of Veterinary Science
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• v.21 no.1
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• pp.6.1-6.12
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• 2020

Currently, the optimal resuscitation fluid remains debatable. Therefore, in the present study, we designed a trometamol-balanced solution (TBS) for use as a resuscitation fluid for hemorrhagic shock. Hemorrhagic shock was induced in 18 male Wistar-Kyoto rats, which were assigned to normal saline (NS), Ringer's solution (RS), and TBS groups. During the hemorrhagic state, their hemodynamic parameters were recorded using an Abbott i-STAT analyzer with the CG4+ cartridge (for pH, pressure of carbon dioxide, pressure of oxygen, total carbon dioxide, bicarbonate, base excess, oxygen saturation, and lactate), the CG6+ cartridge (for sodium, potassium, chloride, blood glucose, blood urea nitrogen, hematocrit, and hemoglobin), and enzyme-linked immunosorbent assay kits (calcium, magnesium, creatinine, aspartate aminotransferase, alanine aminotransferase, bilirubin, and albumin). Similar trends were found for the parameters of biochemistries, electrolytes, and blood gas, and they revealed no significant changes after blood withdrawal-induced hemorrhagic shock. However, the TBS group showed more effective ability to correct metabolic acidosis than the NS and RS groups. TBS was a feasible and safe resuscitation solution in this study and may be an alternative to NS and RS for resuscitation in hemorrhagic shock patients without liver damage.