• BMB Reports
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• v.35 no.4
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• pp.432-436
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• 2002

Pseudomonas sp. S-47 is capable of degrading catechol and 4-chlorocatechol via the meta-cleavage pathway. XyITE products catalyze the dioxygenation of the aromatics. The sylT of the strain S-47 is located just upstream of the xylE gene. XylT of the strain S-47 is located just upstream of the xylE gene. XyIT is typical chloroplast-type ferredoxin, which is characterized by 4 cystein residues that are located at positions 41, 46, 49, and 81. The chloroplast-type ferredoxin of Pseudomonas sp. S-47 exhibited a 98% identity with that of P. putida mt-2(TOL plasmid) in the amino acid sequence, but only about a 40 to 60% identity with the corresponding enzymes from other organisms. We constructed two recombinant plasmids (pRES1 containing xylTE and pRES101 containing xylE without xylT) in order to examine the function of XyIT for the reactivation of the catechol 2,3-dioxygenase (XyIE) that is oxidized with hydrogen peroxide was recovered in the catechol 2,3-dioxygenase (C23O) activity about 4 mimutes after incubation, but the pRES101 showed no recovery. That means that the typical chloroplast-type ferredoxin (XyIT) of Pseudomonas sp. S-47 is involved in the reactivation of the oxidized C23O in the dioxygenolytic cleavage of aromatic compounds.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.502-509
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• 1997

Aromatic pollutants(benzene, toluene, ethylbenzene and xylenes) were photodegraded by using a UV oxidation and the rates of degradation were investigated under various reaction conditions. Each of the solution containing 50 ppm benzene, 150 ppm ethylbenzene and 250 ppm xylenes was found UV-photodegraded over 90% in 1 hour of reaction time, wheras the only was 43 % degradation was obtained with 350 ppm toluene solution. A single component solution was more degradable than a mixed component solution and benzene was almost photodegraded at a pH 4.0, 6.4 and 10.0 after reaction time is 1 hr, ehtylbenzene was photodegraded about 92%(pH 4.0), 90%(pH 6.4) and 91%(pH 10.0), xylenes was photodegraded about 95%(pH 4.0), 90%(pH 6.4) and 92%(pH 10.0), but toluene was photodegraded about 80%(pH 4.0), 43%(pH 6.4) and 70%(pH 10.0), respectively. Kinetics studies show that the rate of decay in TOC(total organic carbon) were pseudo first-order rate except ethylbenzene, and then we could evaluate mineralization rate constants(k) of aromatics.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.382-386
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• 2006

Rice straw is one of the main renewable energy sources in Korea. Bio-oil is produced from rice straw with a bench-scale equipment mainly with a fluidized bed, a char removal system and zeolite catalyst. It was investigated how the zeolite catalyst affected the production of bio-oil and chemical composition of bio-oil. Compared with non catalytic pyrolysis, the catalytic pyrolysis increased the amount of gas and char but decreased the amount of oil. The water content in bio-oil increased due to deoxygenation. The aromatic compound and heating value was increased when catalytic pyrolysis was applied.u

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.5
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• pp.477-491
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• 2014

This study was carried out to evaluate the concentration variations of volatile organic compounds (VOCs) in the office environments located in a large urban area with respect to seasonality, smoking status, types of ventilation and heating. Indoor air sampling was undertaken in 37 and 30 offices in Daegu city during summer and winter, respectively. The VOC samples were collected using adsorbent tubes, and were determined by thermal desorption coupled with GC/MS analysis. The analytical method was validated for repeatability, method detection limits (MDL), and duplication precision. A total of 34 VOCs of environmental concern were determined, including 15 aromatics and 19 halogenated hydrocarbons. Average concentrations of BTEX appeared to 1.91 ppb, 22.98 ppb, 3.44 ppb, and 3.70 ppb, respectively. These values were relatively higher levels than those measured at homes and outdoor roadsides reported by other researches. In general, the concentrations of VOCs were higher in winter than summer, in smoking offices than non-smoking offices, in forced ventilation type than natural ventilation type, and in combustion heating than non-combustion heating offices. However, such differences were not always significant at a level of 0.05 by statistical tests (t-test and/or Mann-Whitney test) with some exceptions for BTEX and styrene. This study demonstrated that smoking status, ventilation type and presence of combustion sources indoors could be important factors on the elevated concentrations of some VOCs in the office environment.

• Applied Chemistry for Engineering
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• v.24 no.6
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• pp.672-675
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• 2013

Fast pyrolysis of medium-density fiberboard was carried out using a fluidized-bed reactor under various conditions to find an optimum pyrolysis condition. When the pyrolysis temperature was varied between $425^{\circ}C$ and $575^{\circ}C$, the maximum bio-oil yield of 52 wt% was obtained at $525^{\circ}C$. The quality of the bio-oil product increased with increasing pyrolysis temperature. Pyrolysis at a high temperature removed significant amounts of oxygenates and acids, producing more valuable species such as aromatics and phenolics. The main gaseous products were CO and $CO_2$. The yields of CO and $C_1-C_4$ hydrocarbons increased with increasing the pyrolysis temperature.

• The Korean Journal of Mycology
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• v.37 no.1
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• pp.73-79
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• 2009

As waste-water disposal plants and oxidative biodegradation for the removal of waste polyaromatic dyes are proved to be ineffective due to the chemical stability of dyes, we studied various strains of mushroom fungi for the removal of these dyes. 100 fungi were isolated from the mushroom samples of 230 species collected in Korea. The growth medium containing a dye (Bromophenol Blue, Congo Red, or Methylene Blue) was inoculated to 10% and incubated for 7 days without shaking. The six strains which removed dyes effectively were selected for further studies with respect to removal of polycyclic aromatic dyes. For all strains, the rate of decoloration of dyes was increasing with Methylene Blue, Bromophenol Blue and Congo Red. The rate of decoloration was higher with stationary culture than with shaking culture. Adsorption of the dyes was the highest with Congo Red.

• Food Science of Animal Resources
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• v.36 no.6
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• pp.719-728
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• 2016

The aim of this study was to explore the volatile compounds of hind leg, foreleg, abdomen and Longissimus dorsi in both male and female Hyla rabbit meat by solid phase microextraction tandem with gas chromatography mass spectrometry, and to seek out the key odorants via calculating the odor activity value and principal component analysis. Cluster analysis is used to study the flavor pattern differences in four edible parts. Sixty three volatile compounds were detected, including 23 aldehydes, 4 alcohols, 5 ketones, 11 esters, 5 aromatics, 8 acids and 7 hydrocarbons. Among them, 6 aldehydes and 3 acids were identified as the potential key odorants according to the ratio of concentration and threshold. The contents of volatile compounds in male Hyla rabbit meat were significantly higher than those in female one (p<0.05). The results of principal component analysis showed that the first two principal component cumulative variance contributions reach 87.69%; Hexanal, octanal, 2-nonenal, 2-decenal and decanal were regard as the key odorants of Hyla rabbit meat by combining odor activity value and principal component analysis. Therefore volatile compounds of rabbit meat can be effectively characterized. Cluster analysis indicated that volatile chemical compounds of Longissimus dorsi were significantly different from other three parts, which provide reliable information for rabbit processing industry and for possible future sale.

• Korean Journal of Food Science and Technology
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• v.26 no.5
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• pp.512-519
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• 1994

To investigate the effects of cultivation on the aroma characteristics of essential oil of peppermint (Mentha piperita L.), experimental peppermints were cultivated with different treatments of field mulching, soil fertilization, and harvesting time. Aroma characteristics of the different mint oils were analyzed by gas chromatography (GC) and GC/mass spectrometry (MS)/infrared spectroscopy (IR). Growth of peppermint with vinyl muching was faster in the early stage of cultivation, but became almost same in the harvest date. The higher amounts of rainfall and sunshine hour resulted in the better growth of stem and leaf of the peppermint. Contents of menthone in the essential oils from the peppermint cultivated in 1990 increased as harvest date delayed from late June 25 to late July 26 the same period. In 1991 menthone decreased from June 25 to August 5, but l-menthol increased from June 25 to august 5. The results indicated that the sunshing hour affected biosynthesis of the components. Contents of menthofuran increased significantly from early June to late July. The optimum cutting date resulting best oil production was late July 7 in 1991.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.167-176
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• 2005

Atmospheric deposition and riverine waters were sampled throughout a year, to estimate the loading fluxes of polycyclic aromatic hydrocarbons (PAHs) into the Masan Bay and its vicinity, Korea. Atmospheric deposition fluxes of total PAHs in the surveyed area varied from 62.2 to 464 ${\mu}g/m^2/year$. Concentration of total PAHs in water samples from six rivers ranged from 34.6 to 239 ng/L. Contribution of the carcinogenic PAHs to the total PAHs occupied $38\%$ and $50\%$ for atmospheric deposition and river waters, respectively. Atmospheric deposition fluxes and water concentrations of PAHs were slightly low or moderate to those in locations from some countries. Correspondence analysis was used to investigate the loading characteristics of PAHs according to transport routes. Atmospheric deposition samples were corresponded to higher molecular aromatics of PAHs, while riverine water samples were associated with lower molecular weight of PAHs. The results indicate that the higher-molecular-weight PAHs can be primarily transported by atmosphere deposition and the lower-molecular-weight PAHs can be mainly contaminated by riverine discharge into the Masan Bay and its vicinity. Loadings fluxes of PAHs into the Masan Bay and its vicinity were 39.2 g/day via atmosphere and 10.3 g/day via rivers, showing that atmospheric input was about 4 times higher than riverine one. Therefore, in order to minimize the contamination burden of PAHs from terrestrial sources to the Masan Bay and its vicinity, the control and management of PAHs deriving from atmosphere will be necessary.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_3
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• pp.113-119
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• 2001

Surface sediments(0~5 cm) were sampled from 22 stations in Ulsan Bay, one of the most highly industrialized regions in Korea, in November 2000. The sediment samples were analyzed for their polycyclic aromatic hydrocarbon(PAH) content using a gas chromatography coupled to a mass spectrometer detector(GC/MSD). The total PAH concentrations in the sediments varied from 14 to 7108 ng/g dry weight with a mean value of 1052 ng/g dry weight. The level of carcinogenic PAHs ranged from 6 to 2396 ng/g dry weight with a mean value of 433 ng/g dry weight. The highest PAH concentrations in the sediments from Ulsan Bay were found at Station U8, whereas the lowest levels were observed at Stations U2 and U 17. The PAH distribution exhibited a decreasing gradient from the inner basin to the outer bay. The predominant contributors to the aromatic ring groups of the 16 PAHs were four- and five-ring groups, such as fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzor[b]fluoranthene, benzor[k]fluoranthene and benzo[a]pyrene, while two- and three-ring aromatics, like naphthalene, acenapthylene, acenaphthene, fluorene, phenanthrene and anthracene, only exhibited a low concentration. The molecular indices for phenanthrene/anthracene and fluoranthen/pyrene were used to Identify the origin of the PAH contamination in the sediments. The results indicated that the PAH contamination in Ulsan Bay was mostly Pyrolytic in origin with a Petrogenic input adjacent to Ulsan and Jangsuengpo harbor.