• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.850-856
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• 2001

This study investigates the ozonation kinetics of 2-chlorophenol in wastewater under acidic condition. Intermediates and by-products generated during the process were rigorously identified and quantified. The major by-products are four carboxylic acids: tartaric acid, oxalic acid, maleic acid, and hydroxymalonic acid. The generation of these organic acids is in agreement with theoretical predictions. But hydroxylated compounds are more favorable to produce than their corresponding non-hydroxylated ones. Based on the information concerning the generation of organic acids and other aromatic intermediates, the complete reaction pathways toward mineralization can be proposed and mathematically modeled. The fitted second-order rate constants are in the same order of magnitude with the results from other studies. Using these oxidation pathways and the corresponding kinetic model, by-products generated in ozonation process can be predicted. This can help in optimizing the design and operation of any subsequent treatment processes.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.1-7
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• 2013

During meiosis, genetic recombinants are formed by homologous recombination accompanying with the programmed double-strand breaks (DSBs) and strand exchanges between homologous chromosomes. The mechanism is generated by recombination intermediates such as single-end invasions (SEIs) and double-Holliday junctions (dHJs), and followed by crossover (CO) or non-crossover (NCO) products. Our study was focused on the analysis of meiotic recombination intermediates (DSBs, SEIs, and dHJs) and final recombination products (CO and NCO). We identified these meiotic recombination intermediates using DNA physical analysis under HIS4LEU2 "hot spot" system in budding yeast, Saccharomyces cerevisiae. For DNA physical analysis, when the hot spot locus is recognized by restriction enzyme from synchronous meiotic cells, the fragmented DNA that are forming recombination intermediates can be detected and quantified through Southern hybridization analysis. Our study suggests that this system can analyze the structural change of recombination intermediates during DSB-SEI transition, double-Holiday junctions and crossover/non-crossover products in meiosis.

• Journal of Applied Biological Chemistry
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• v.58 no.1
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• pp.9-11
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• 2015

Tissue extracts were prepared from liquid-cultured Arabidopsis and reacted with UDP-[$^3H$]-GlcNAc. Phospholipid fractions were then extracted by butanol partitioning. Consecutive thin-layer chromatography identified two glycolipids sensitive to PI-specific phospholipase C, known as early intermediates in glycosylphosphatidylinositol anchor biosynthesis; phosphatidylinositol N-acetylglucosamine and phosphatidylinositol glucosamine.

• Archives of Pharmacal Research
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• v.20 no.3
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• pp.288-290
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• 1997

An efficient synthesis of 3-(E)-hydroxy- and 3-(E)-acetoxypropenylcephem derivatives, key intermediates for the synthesis of 3-(E)-propenylcephalosporins was achieved via Stille coupling reaction of 3-trifloxycephem with 3-(E)-tributylstannylallylic alcohol.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2809-2811
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• 2009

• Bulletin of the Korean Chemical Society
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• v.17 no.5
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• pp.437-442
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• 1996

Electrocyclic ring-closure of 6-vinylcyclohepta-1,3,5-isocyanate has been carried out in the presence of triphenylphosphine to examine a catalyzing effect of the triphenylphosphine. The preparation of 10-(1-carboalkoxyalkyl)-2,7-methanoaza[10]annulenes by the electrocyclic ring-closure of ketenimine intermediates, which are formed by the reaction of triphenylalkylidenephosphorane and 6-vinylcyclo-hepta-1,3,5-isocyanate, is described. 10-Alkyl-2,7-methanoaza[10]annulenes were prepared by basic hydrolysis of the carboalkoxyaza[10]annulenes and decarboxylation of the acid intermediates. In the same manner, 10-(N-alkyl(or aryl))-2,7-methanoaza[10]annulenes were prepared from the reaction of the isocyanate and N-alkyl(or aryl)iminotriphenylphosphorane via electrocylic ring-closure of carbodiimide intermediate.

• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.526-528
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• 1992

1-Aminothiohydantoin derivatives were prepared in good yields by the reaction of alkyl or arylisothiocyanates with ethyl hydrazinoacetate hydrochloride in presence of triethylamine. The intermediates, N-amino-N-ethoxycarbonylmethyl-N'-aralkylthioure as, which were formed during the reaction and could be transformed into the appropriate 1-aminothiohydantoins, were isolated and characterized.

• Journal of Photoscience
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• v.9 no.2
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• pp.126-129
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• 2002

The chromophore/protein interactions in the photocycle intermediates of photoactive yel- low protein (PYP) were probed by site-directed mutagenesis. The absorption spectra of L- intermediates produced from E46Q, T50V, and R52Q mutants were calculated using the absorption spectra of dark states and difference absorption spectra between L-intermediates and dark states, and compared with that of PYP$\_$L/. The absorption spectrum of R52Q$\_$L/ agreed with that of PYP$\_$L/, but those of E46Q$\_$L/ and T50V$\_$L/ were red-shifted. The effect of these mutations on the absorption spectrum for L-intermediate was comparable to that for the dark state, suggesting that the interaction around the phe-nolic oxygen of the chromophore is conserved in PYP$\_$L/ unlike the crystal structure. On the other hand, we have reported that the absorption spectra of Y 42F$\_$M/, T50V $\_$M/, and R52Q$\_$M/ agreed with that of PYP$\_$M/, but that of E46Q$\_$M/ was red-shifted, suggesting that the hydrogen bond of the chromophore with Glu46 is conserved but that with Tyr42 is broken in PYP$\_$M/. These results suggest that the chromophore inter-acts with Glu46 throughout the photocycle, but never directly interacts with Arg52. This model con- flicts with some of the structural model of PYP intermediates proposed based on the high-resolution X -ray crystallography.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.11
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• pp.1639-1645
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• 2002

The purpose of this study was to investigate the effects of aflatoxin $B_1$ ($AFB_1$) on the ultracellular morphology alteration, apoptosis induction and reactive nitrogen and oxygen intermediates production of peritoneal macrophages (DPM) from mule ducks. The ducklings were purchased from a commercial hatchery, and were fed a corn-soybean based diet. As the ducklings were grown up to 3 wk of age, the Sephadex-elicited peritoneal exudative cells (PEC) were used as the source for duck peritoneal macrophages. The ultracellular morphology study showed that significant number of cells shifted from category I (normal cell with ruffled membrane) and II (cell membrane blebbing) to category III (cell membrane blebbing and even rupture) after DPM were incubated with $AFB_1$ ($20{\mu}g/ml$) for 12 to 48 h. When DPM were exposed to $AFB_1$ in vitro, the production of NO, $H_2O_2$ and $O_2{^-}$ in macrophages was reduced after 12-48 h incubation with previous LPS stimulation. There was a DNA laddering pattern observed in DPM incubated with $AFB_1$ 5, 10, 20, 50 or $100{\mu}g/ml$ for 12 h. Evidence also revealed that the percentage of apoptotic cells was increased along with the elevation of $AFB_1$ concentration. The results suggest that $AFB_1$ exposure causes duck macrophages going on apoptotic pathway through evidence of ultracellular morphology alteration and DNA laddering in agarose electrophoresis. The production of reactive nitrogen and oxygen intermediates of duck macrophages also depressed after $AFB_1$ exposure, and this implied that $AFB_1$ could cause deteriorated functions of bacteriocidal and tumoricidal activity in duck macrophages.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.4
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• pp.437-443
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• 1984

Muscular exercise induced by electrical stimulation of femoral nerves in perfused rat hindquarters(5 contractions per sec) in the presence of insulin and glucose effected a rapid increase(c. a. two-fold) in the level of citric acid cycle intermediates. The highest values were found within one minute of stimulation. The tissue concent ratios of lactate, pyruvate and alanine increased rapidly on initiation of exercese. Release of lactate also increased rapidly, whereas that of pyruvate was only moderately elevated. In the course of three minute exercese, the sum of alanine, glutamate and aspartate was only transiently elevated. A fall in creatine-p and ATP in the stimulated muscle was accompanied by increases in tissue level of AMP and release of ammonia into perfusing medium. However, the changes in glutamine were small. It is concluded that the pool of citric acid cycle intermediates is expanded during muscular work due (a) to an elevated level of pyruvate, leading to shifts in the levels of alanine and cycle intermediates vie trans-amination reactions and (b) to stimulation of the purine nucleotide cycle due to elevated AMP, resulting in generation of cycle intermediates and ammonia at the expense of aspartate.