• Bulletin of the Korean Chemical Society
• /
• 제18권9호
• /
• 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.

• 폴리머
• /
• 제34권2호
• /
• pp.159-165
• /
• 2010

리빙 음이온 중합에 의해 sec-BuLi으로 개시된 polystyryllithium (PSLi)과 polybutadienyllithium (PBDLi)의 연쇄 말단에 di(2-pyridyl)ketone(DPK)을 반응시켜 dipyridine이 말단 관능화된 폴리스티렌과 폴리부타디엔을 각각 합성하였다. 분자량이 1000~2000 g/mol인 PSLi과 PBDLi을 사용하여 TMEDA 존재하에서 말단 DPK-관능화 반응 후 GPC에 의한 분자량 특성분석과 $^1H$-NMR, $^{13}C$-NMR 분석에 의한 고분자 말단 구조 분석을 통하여 말단 관능화 수율과 함께 유기리튬의 피리딘 링 친핵성 부가 반응으로 인한 커플링 현상을 확인하였다. PBDLi에 DPK를 부가하는 일반적인 말단 관능화 방법에 비하여 역으로 부가하는 방법에서 최대 9% 정도의 커플링 정도와 86% 이상의 관능화 수율을 보였다. 이 반응에서 LiCl 첨가효과는 없었으며, 반응온도가 낮을수록 높은 관능화 수율을 나타내었다.

• 한국자동차공학회논문집
• /
• 제10권1호
• /
• 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.

• 한국자동차공학회논문집
• /
• 제11권3호
• /
• 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
• /
• 제10권6호
• /
• 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
• /
• 제40권4호
• /
• 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
• /
• 제21권10호
• /
• 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.

• 한국식물병리학회지
• /
• 제12권2호
• /
• 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.

• 한국환경보건학회지
• /
• 제28권2호
• /
• 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.

• 대한수의학회지
• /
• 제39권1호
• /
• 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.