• Title/Summary/Keyword: molecular engineering

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Direct Analysis in Real Time Mass Spectrometry: a Powerful Tool for Fast Analysis

  • Li, Xianjiang;Wang, Xin;Li, Linnan;Bai, Yu;Liu, Huwei
    • Mass Spectrometry Letters
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    • v.6 no.1
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    • pp.1-6
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    • 2015

  • Direct analysis in real time mass spectrometry (DART-MS) is one of the variants of ambient mass spectrometry. The ionization process of DART-MS is in open environment and only takes few seconds, so it is suitable for fast analysis. Actually, since its introduction in 2005, more and more attentions have been drawn to its various applications due to its excellent properties, e.g., fast analysis, and no or less sample preparation, high salt tolerance and so on. This review summarized the promising features of DART-MS, including its ionization mechanism, equipment modification, wide applications, coupling techniques and extraction strategies before analysis.

  • https://doi.org/10.5478/MSL.2015.6.1.1 인용 PDF KSCI KPUBS HTML

LC Alignment Behaviors at Rubbed Films of Brush Polyimides;Perpendicular LC Alignment versus Parallel LC Alignment

  • Lee, Taek-Joon;Hahm, Seok-Gyu;Lee, Seung-Woo;Chae, Bok-Nam;Lee, Seong-June;Kim, Seung-Bin;Jung, Jin-Chul;Ree, Moon-Hor
    • 한국정보디스플레이학회:학술대회논문집
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    • 2004.08a
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    • pp.766-768
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    • 2004

  • Rubbed films of a series of poly(p-phenylene 3,6-bis(4-(n-alkyloxy)phenyloxy)pyromellitimide)s (Cn-PMDA-PDA PIs), which are well-defined brush PIs composed of two aromatic-aliphatic bristles per repeat unit of a fully rodlike backbone, were investigated in detail using atomic force microscopy (AFM), optical retardation analysis and linearly polarized infrared (IR) spectroscopy in order to elucidate their surface morphology and molecular orientation. The liquid crystal (LC) alignment behavior and the anchoring energy of LC molecules on the rubbed films were also determined.

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High Level Production of Supra Molecular Weight Poly(3-Hydroxybutyrate) by Metabolically Engineered Escherichia coli

  • Park, Jong-il;Lee, Sang-Yup
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.9 no.3
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    • pp.196-200
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    • 2004

  • The supra molecular weight poly(〔R〕-3-hydroxybutyrate) (PH B), having a molecular weight greater than 2 million Da, has recently been found to possess improved mechanical properties compared with the normal molecular weight PHB, which has a molecular weight of less than 1 million Da. However, applications for this PHB have been hampered due to the difficulty of its production. Reported here, is the development of a new metabolically engineered Escherichia coli strain and its fermentation for high level production of supra molecular weight PHB. Recombinant E. coli strains, harboring plasm ids of different copy numbers containing the Alcaligenes latus PHB biosynthesis genes, were cultured and the molecular weights of the accumulated PHB were compared. When the recombinant E. coli XL1-Blue, harboring a medium-copy-number pJC2 containing the A. latus PHB biosynthesis genes, was cultivated by fed-batch culture at pH 6.0, supra molecular weight PHB could be produced at up to 89.8 g/L with a productivity of 2.07 g PHB/L-h. The molecular weight of PHB obtained under these conditions was as high as 22 MDa, exceeding by an order of magnitude the molecular weight of PHB typically produced in Ralstonia eutropha or recombinant E. coli.

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