• Bulletin of the Korean Chemical Society
• /
• v.18 no.9
• /
• pp.985-994
• /
• 1997

The reaction of gas-phase atomic hydrogen with hydrogen atoms chemisorbed on Fe(110) surface is studied by use of classical trajectory procedures. Flow of energy between the reaction zone and bulk solid phase has been treated in the generalized Langevin equation approach. A London-Eyring-Polanyi-Sato energy surface is used for the reaction zone interaction. Most reactive events are found to occur in strong single-impact collisions on a subpicosecond scale via the Eley-Rideal mechanism. The extent of reaction is large and a major fraction of the available energy goes into the vibrational excitation of H2, exhibiting a vibrational population inversion. Dissipation of reaction energy to the heat bath can be adequately described using a seven-atom chain with the chain end bound to the rest of solid. The extent of reaction is not sensitive to the variation of surface temperature in the range of Ts=0-300 K in the fixed gas temperature, but it shows a minimum near 1000 K over the Tg=300-2500 K.

• Polymer(Korea)
• /
• v.34 no.2
• /
• pp.159-165
• /
• 2010

Dipyridine-terminated polystyrenes and polybutadienes were synthesized by the chain endfunctionalization reaction of polystyryllithium (PSLi) and polybutadienyllithium (PBDLi) with di(2-pyridyl) ketone(DPK) using a living anionic polymerization method in the Ar-glove box. Living polymeric lithiums with low molecular weights (Mw=1000~2000 g/mol) were used to investigate the chain end-functionalization yield with DPK and the degree of coupling reaction by the attack of organolithium to the pyridine ring in the presence of TMEDA using GPC, $^1H$-NMR, $^{13}C$ analysis. DPK-terminated PBD exhibited much higher functionalization yield and less amount of coupling reaction compared with DPK-terminated PS. 86% functionalization yield with 9% degree of coupling was obtained when the PBDLi was added dropwise to DPK solution at room temperature. The functionalization yield was increased as the reaction temperature decreased, however, no LiCl effect was observed in this chain end-functionalization reaction with DPK.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.1
• /
• pp.76-83
• /
• 2002

Mathematically and chemically simplified reaction scheme for n(heptane that simulates autoignitions of the end gases in spark ignition engines has been developed and studied computationally. The five(equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius pre-exponential constants, A, and heats of reaction for stoichiometric nheptane/air has all been optimized. Comparisons between computed and experimental autoignition delay times have validated the present simplified reaction scheme. The influences of heat loss and concentration of chain carrier at the beginning of compression upon autoignition delay times have been computationally investigated.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.3
• /
• pp.13-19
• /
• 2003

Mathematically simplified reaction scheme that simulates autoignitions of the end gases in spark ignition engines has been studied computationally. The five equation model is described, to predict the essential features of hydrocarbon oxidation. This scheme has been calibrated against autoignition delay times measured in rapid compression machines. The rate constants, activation temperatures, Ta, Arrhenius preexponential constants, A, and heats of reaction for stoichiometric n-heptane/air, iso-octane/air, and their mixtures have all been optimised. The optimisation has been guided by Morley's correlation of the ratio of chain branching to linear termination rates with octane number. Comparisons between computed and experimental autoignition delay times have validated the Present simplified reaction scheme and the influences of octane number upon autoignition delay times have been computationally investigated. It has been found that both cool flame and high temperature direct reactions can have an effect on autoignition delay times.

• Journal of Microbiology and Biotechnology
• /
• v.10 no.6
• /
• pp.881-884
• /
• 2000

A polymerase chain reaction (PCR) was performed to rapidly identify Lactobacillus plantarum from type strains and kimchi samples. The PCR experiments were carried out using specific oligonucleotide primer sets based on the 16S rRNA gene sequences of L. plantarum. The expected DNA amplificate of 419 bp was obtained when either purified DNA or whole cells of L. plantarum strains reacted with LP primers, yet not with any of the other strains. The PCR product was confirmed by DNA sequencing. Accordingly, since the PCR method used is simple, specific, and rapid, it will be useful for monitoring and evaluation L. plantarum in the mixed microbial population found in kimchi.

• Journal of Microbiology
• /
• v.40 no.4
• /
• pp.327-330
• /
• 2002

The purpose of this research was to test multiplex polymerase chain reaction in investigating the microbiological quality of the risky surfaces in social living places of a military base where over 15 thousand people live together. In 22 samples of 99, there were no bacteria. Only four of the samples contained Shigella, and one of them contained Salmonella, but 77 of the samples contained thermotolerant coliform organisms. There was no statistically significant difference among the microbiological quality of different sites and different equipment surfaces (p>0.05).

• Journal of Microbiology and Biotechnology
• /
• v.21 no.10
• /
• pp.1049-1052
• /
• 2011

In this study, we demonstrated the asymmetric synthesis of L-tert-leucine from trimethylpyruvate using branched-chain aminotransferase (BCAT) from Escherichia coli in the presence of L-glutamate as an amino donor. Since BCAT was severely inhibited by 2-ketoglutarate, in order to overcome this here, we developed a BCAT/aspartate aminotransferase (AspAT) and BCAT/AspAT/pyruvate decarboxylase (PDC) coupling reaction. In the BCAT/AspAT/PDC coupling reaction, 89.2 mM L-tert-leucine (ee>99%) was asymmetrically synthesized from 100 mM trimethylpyruvate.

• Korean Journal Plant Pathology
• /
• v.12 no.2
• /
• pp.191-196
• /
• 1996

위축, 황화, 총생 증상 등 전형적인 병징을 나타내는 phytoplasma에 감염된 식물에서 phytoplasma만을 특이적으로 검출하기 위하여 polymerase chain reaction(PCR) 방법을 이용하였다. Phytoplasma의 16S rRNA gence의 DNA 단편을 증폭하기 위하여 1.4 kb primers (forward, 5` -GTTGATCCTGGCTCAGGATT-3` 와 reverse, 5` -AACCCCGAGAACGTATTCACC -3`)를 사용하여 증폭한 결과, phytoplasma에 이병된 오동나무, 라일락 및 미역취에서는 약 1.4 kbp의 위치에서 특이 band가 검출되었으나 control로 사용한 건전주에서는 어떠한 band 검출되지 않았다. 위의 결과를 재확인 하기 위하여 약 0.5 kb의 primers(forward, 5` -ACGAAAGCGTGGGGAGCAAA-3` 와 reverse, 5` -GAAGTCGAGTTGCAGACTTC-3`)를 사용하여 증폭한 결과, 0.5 kb의 위치에서 특이 band가 검출되었으나 control로 사용한 건전주에서는 어떠한 band도 검출되지 않았다. Phytoplasma에 이병된 식물의 PCR 반응산물을 제한효소인 AluI으로 처리하 sruf과, 오동나무와 라일락에서는 동일한 band pattern을 나타내어 서로 유연관계가 가까운 phytoplasma인 것으로 생각되며, 미역취에서는 이들과는 다른 band pattern을 나타내어 오동나무와 라일락의 phytoplasma와는 유연관계가 먼 것으로 추측된다.

• Journal of Environmental Health Sciences
• /
• v.28 no.2
• /
• pp.193-202
• /
• 2002

The polymerase chain reaction(PCR) of target lacZ and uidA genes were used to detect total coliform and Escherichia coli for determining water quality, respectively. Of 109 spring waters, coliform were detected from 38 spring waters by lacZ PCR method but 21 spring waters by culture method accepted by the Ministry of Environment for water quality monitoring. The lacz PCR method gave the results statistically equivalent to those of the culture method(kappa=0.62, McNemar=17.00). The uidA PCR method gave the same results to those of the culture method. The sensitivity and specificity of coliform and E. coli by PCR method were 100% and 80.7%, respectively. Therefore, PCR can be used for the rapid identification of Escherichia coli and coliform in potable water using uidA and lacZ.

• Korean Journal of Veterinary Research
• /
• v.39 no.1
• /
• pp.90-95
• /
• 1999

A species-specific 760 base pair(bp) BamHI to EcoRI DNA fragment(fMG-2) of lipoprotein gene was isolated from a Mycoplasma gallisepticum(M gallisepticum) genomic library. Based on the DNA sequence data of fMG-2, a pair of 25bp primers was synthesized. When used in the polymerase chain reaction(PCR), 732bp DNA products were amplified from 6 standard strains and 10 field isolates of M gallisepticum, but not from 2 Mycoplasma synoviae and 7 other Mycoplasma species. The lower detection limit was 100fg of the genomic DNA. Identity of the PCR products was confirmed by comparison of patterns of restriction endonuclease analysis with AseI, DraI, EcoRV and SspI.