• Applied Biological Chemistry
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• v.40 no.6
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• pp.519-524
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• 1997

As an investigation for utilization of ascidian tunic carotenoids as a food color additives, we attempted to collect the volatile thermal degradation compounds from ascidian tunic carotenoids. Oxygenate volatile compounds were extracted by simultaneous distillation and extraction/concentration apparatus and analyzed by gas chromatography and mass spectrometery. Total 63 compounds were identified and some of them were caused by thermal degradation. They included 1,3,5-trimethylbenzene, 3,5,5-trimethyl-3-cyclohexen-1-ol, 3,5,5-trimethyl-3-cyclohexen-1-one, 1,1,2,3-tetramethyl-2-cyclohexen-5-ol, 1,1,2,3-tetramethyl-2-cyclohexen-5-one, 2,3,4,4-tetramethyl-6-hydroxy-2-cyclohexene-1-one, 1,2,3,8-tetrahydro-3,3,6-trimethyl-1-naphtol, dihydroacetinidolide, ${\beta}-ionone$, 2-(1,1,5-trimethyl-3-hydroxy-5-cyclohexen-6-yl)-1-tolylethene, 2,6-dimethyl-8-(1,1,5-trimethyl-3-hydroxy-5-cyclohexen-6-yl)-1,3,5-octatriene-7-yne. Proposed mechanism of formation of some compounds as thermal degradation products of ascidian tunic carotenoids are provided.

• Archives of Pharmacal Research
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• v.24 no.6
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• pp.607-612
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• 2001

Endogenous carbon monoxide (CO) shares with nitric oxide (NO) a role as a putative neural messenger in the brain. Both gases are believed to modulate CNS function via an increase in cytoplasmic cGMP concentrations secondary to the activation of soluble guanylate cyclase (sGC). Recently CO and NO were proposed as a possible mediator of febrile response in hypothalamus. NO has been reported to activate both the constitutive and inducible isoform of the cyclooxygenase (COX). Thus, we investigated whether CO arising from heme catabolism by heme oxygenate (HO) is involved in the febrile response via the activation of COX in the hypothalamus. $PGE_2$ which is a final mediator of febrile response released from primary cultured hypothalamic cells was taken as a marker of COX activity. $PGE_2$ concentration was measured with EIA kits. Exogenous CO (CO-saturated medium) and hemin (a substrate and potent inducer of HO) evoked an increase in $PGE_2$ release from hypothalamic cells, and these effects were blocked by methylene blue (an inhibitor of sGC). And membrane permeable cGMP analogue, dibutyryl-cGMP elicited significant increases in $PGE_2$release. These results suggest that there may be a functional link between HO and COX enzymatic activities. The gaseous product of hemin through the HO pathway, CO, might play a role through the modulation of the COX activity in the hypothalamus.

• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.52-59
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• 2006

This paper examined the conversion of methane to hydrogen and other higher hydrocarbons using dielectric barrier discharge with AC pulse power. Two metal electrodes of a coaxial-type plasma reactor were separated by gas gap and an alumina tube. The inner electrode was located inside the alumina tube. The alumina tube was located inside the stainless steel tube, which was used as the outer electrode. Effect of feed gas composition (methane, oxygen, argon, water and helium), flow rate, applied frequency, input volt-age on methane conversion and product distribution were studied. The major products of plasma chemical reactions were ethylene, ethane, propane, buthane, hydrogen, carbon monoxide and carbon dioxide. The increment of applied voltage and the usage of inert gas as the background (helium and argon) enhanced the selectivity of hydrocarbons and methane conversion. The addition of water in the feed stream enhanced the conversion of methane and yield of hydrogen. Higher voltage leads to higher yield of $C_2H_6,\;C_3H_8,\;C_4H_{10}$ and yield or $C_2H_2\;and\;C_2H_4$ appeared highly in lower voltage.

• Journal of the Korean Society of Groundwater Environment
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• v.7 no.1
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• pp.55-58
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• 2000

Methyl tertiary butyl ether (MTBE) is a gasoline additive that boosts the oxygen content in fuel (an oxygenate), resulting in less air-polluting carbon monoxide being released from vehicle exhaust systems. Then, groundwater contamination problems have been developed in areas where the chemical is used. Common sources of water contamination by MTBE include leaking underground gasoline storage tanks and leaks and spills from above ground fuel storage tanks, etc.. Studies on the chemical and these problems are going on abroad vigorously. These studies should be performed in our country as well more actively. This paper reviews on articles on these studies and focuses on the identification of the chemical as a groundwater contamination source.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.159-169
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• 2016

In this study, the effects of MTBE contents as oxygenates in gasoline on exhaust emissions and fuel economy in MPI and GDi vehicles have been investigated. Various oxygen contents have been selected such as 0, 1.0, 2.3 and 2.7 wt%. FTP-75 and HWFET modes as fuel economy test methods which are widely used in Republic of Korea and US were applied to investigate exhaust emissions from the test vehicles. Emissions of CO, NMHC and NOx did not show significant correlation with oxygen contents in gasoline fuels, although having slight difference with these contents. In addition, CO2 emissions were not significantly changed with respect to oxygen content. But in case of warm-up and FTP-75 and HWFET modes including high speed regimes, CO2 emissions showed inverse correlation with oxygen contents. Particulate number concentration was inversely proportional to the oxygen contents, having the minimum value at the condition of 2.3 wt%. In case of fuel economy through carbon balance method, the highest value has been obtained at 2.3 wt% and there was positive correlation with oxygen contents and fuel economy.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2000.11a
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• pp.207-208
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• 2000

Since trichloroethylene (TCE), dichloroethylene (DCE), and vinyl chloride (VC) arise from anaerobic degradation of tetrachloroethylene (PCE) and TCE, there is interest in creating aerobic remediation systems that avoid the highly toxic VC and cis-DCE which predonominate in anaerobic degradation. However, it seemed TCE could not be degraded aerobically without an inducing compound (which also competitively inhibits TCE degradation). It has been shown that TCE induces expression of both the toluene dioxygenase of p. putida F1 as well as toluene-p-monooxygenase of P.mendocina KRI. We investigated here the ability of PCE, TCE, and chlorinated phenols to induce toluene-o-xylene monooxygenase (ToMO) from P.stutzeri OX1. ToMO has a relaxed regio-specificity since it hydroxylates toluene in the ortho, meta, and para positions; it also has a broad substrate range as it oxidizes o-xylene, m-xylene, p-xylene, toluene, benzene, ethylbenzene, styrene, and naphthalene; chlorinated compounds including TCE, 1, 1-DCE, cis-DCE, trans-DCE, VC, and chloroform : as well as mixtures of chlorinated aliphatics (Pseudomonas 1999 Maui Meeting). ToMO is a multicomponent enzyme with greatest similarity to the aromatic monooxygenases of Burkholderia pickettii PKO1 and P.mendocina KR1. Using P.sturzeri OX1, it was found that PCE induces P.mendocina KR1 Using P.situtzeri OX1, it was found that PCE induces ToMO activity measured as naphthalene oxygenase activity 2.5-fold, TCE induces 2.3-fold, and toluene induces 3.0 fold. With the mutant P.stutzeri M1 which does not express ToMO, it was also found there was no naphthalene oxygenate activity induced by PCE and TCE; hence, PCE and TCE induce the tow path. Using P.putida PaW340(pPP4062, pFP3028) which has the tow promoter fused to the reporter catechol-2, 3-dioxygenase and the regulator gene touR, it was determined that the tow promoter was induced 5.7-, 7.1-, and 5.2-fold for 2-, 3-, 4-chlorophenol, respectively (cf. 8.9-fold induction with o-cresol) : however, TCE and PCE did not directly induce the tou path. Gas chromatography and chloride ion analysis also showed that TCE induced ToMO expression in P.stutzeri OX1 and was degraded and mineralized. This is the first report of significant PCE induction of any enzyme as well as the first report of chlorinated compound induction of the tou operon. The results indicate TCE and chlorinated phenols can be degraded by P.stutzeri OX1 without a separate inducer of the tou pathway and without competitive inhibition.

• Journal of the Korean Applied Science and Technology
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• v.33 no.1
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• pp.118-128
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• 2016

As the interest on the air-pollution is gradually rising up at home and abroad, automotive and fuel researchers have been working on the exhaust emission reduction from vehicles through a lot of approaches, which consist of new engine design, innovative after-treatment systems, using clean (eco-friendly alternative) fuels and fuel quality improvement. This research has brought forward two main issues : exhaust emission and PM (particulate matter) particle emissions of gasoline vehicle. Exhaust emission and PM particle of automotive had many problem that cause of ambient pollution, health effects. In addition, researcher studied the environment problems of the MTBE contained in the fuel as oxygenate additives. The researchers have many data about the health effects of ingestion of MTBE. However, the data support the conclusion that MTBE is a potential human carcinogen at high doses. Based on the oxygenated fuel additive types (MTBE, Bio-ETBE, Bio-ethanol, Bio-butanol), this paper discussed the influence of oxygen contents on gasoline fuel properties and evaporative emission characteristics. Also, this paper assessed the acceleration and power performance of gasoline vehicle for the fuel property.

• Journal of Soil and Groundwater Environment
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• v.6 no.3
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• pp.31-41
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• 2001

In this study, we have examined the potential degradation of MTBE(methyl tert-butyl ether) by pure culture ENV425 and mixed culture obtained from gasoline contaminated soil using n-butane as the sources of carbon and energy. The results described in this study suggest that MTBE is degraded cometabolically by ENV425 and mixed culture grown on n-butane. Butane and MTBE degradation was completely inhibited by acetylene, which indicated that both substrates were degraded by butane monooxygenase. These cultures grown on n-butane generated TBA (tert-butyl alcohol) as a metabolite of MTBE oxidation. TBA Production was accounted 54.7% and 58.6% for MTBE oxidation by ENV425 and mixed culture, respectively. In resting cell experiments, however, TBA and TBF were detected as the oxidation products of MTBE by ENV425 and mixed culture. The observed maximal MTBE degradation rates were 52.3 and 62.3 (nmol MTBE degraded/hr/mg TSS) by ENV425 and mixed culture, respectively, and the observed maximal transformation yields ($T_y$) were 44.7 and 34.0 (nmol MTBE degraded/$\mu$mol n-butane utilized), and the observed maximal transformation capacities ($T_c$) were 199 and 226 ($\mu$mol MTBE degraded/mg TSS used).