• Title/Summary/Keyword: tetrahydropyran

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Optical Transmittance of Polybenzoxazole Precursor (폴리벤조옥사졸 전구체의 광투과도 연구)

  • 김대겸;김종화;최길영;오재민;이무영;박동원;이광섭;진문영
    • Polymer(Korea)
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    • v.26 no.1
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    • pp.18-27
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    • 2002
  • Poly(ο-hydroxyamide)s as polybenzoxazoles precursors were synthesized by polycondensation from 2,2'-bis(3-amino-4-hydroxyphenyl) hexafluoropropane and various bis-acids. And the polymers were modified to acid-sensitive polyamides by introducing tetrahydropyran in order to impart photosensitivity. A study of optical transmittance at 365 nm, according to the chemical structure of bis-acid, revealed that the polymer derived from 4,4'-oxydibenzoic acid showed better optical transparency than those from other bis-acids. This tendency of optical transmittance could be explained by formation of charge transfer complex. In case of the polymer derived from 4,4'-oxydibenzoic acid, the electron accepting characteristic of bis-acid is reduced by introduction of electron donating group, -O-. Thus, optical transmittance increased due to the diminished formation of intramolecular charge transfer complex. In addition, the optical transmittance increased with increasing the THP content in the polymer. This is attributed to the reduced intermolecular interaction by the loosening of the packing density of the polymer chain.

Analysis of Kasugamycin in Pesticide Formulations by Reversed-Phase Ion Pair Liquid Chromatography (역상 이온쌍 액체크로마토그래피에 의한 농약 제품 중 Kasugamycin의 분석)

  • Kim, Taek-Jae;Kim, Kyong-Sun;Yoon, Chae-Hyuk;Joo, Jin-Bok;Kim, Chung-Hyo
    • Analytical Science and Technology
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    • v.10 no.5
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    • pp.343-349
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    • 1997
  • Analytical method using the reversed phase ion-pair chromatography (RP-IPC) for the determination of kasugamycin(5-amino-2-methyl-6-(2,3,4,5,6-pentahydroxy cyclohexyloxy)tetrahydropyran-3-yl-amino-${\alpha}$-imino acetic acid), pesticide as fungicide bactercide has been established. The retention behavior of kasugamycin in the RP-IPC was examined with respect to the effect of concentrations of organic modifiers, pH of eluent and types and concentrations of the counter ions as ion-pair reagent. This method developed by the optimum factors, can be used for the application of the quality control in the crude product and its formulation.

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Liquid Chromatography-Solid Phase Extraction-NMR (LC-SPE-NMR) Analysis of Liquid Crystalline Mixtures

  • Park, Gregory Hyung-Jin;Park, Ae-Na;Rho, Kyung-Rae;Shin, Jong-Ho;Kim, Yeong-Jeon;Jo, Sung-Chan;Oh, Weon-Sik
    • Journal of the Korean Magnetic Resonance Society
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    • v.15 no.1
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    • pp.14-24
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    • 2011
  • We have performed Liquid Chromatography-Solid Phase Extraction-NMR (LC-SPE-NMR) analysis for liquid crystalline mixture and elucidated the structures of selected components by NMR spectra. Combining the results of one-dimensional 1H experiments as well as homonuclear and heteronuclear two-dimensional experiments, we could analyze the molecular structure of the liquid crystal singles whose structure had not been interpretable by mass spectrometry alone.

Volatile Flavor compounds of Pinus densiflora Sieb and Zucc according to extracting solvents and steam distillation method (솔잎(Pinus densiflora Sieb & Zucc)의 용매분획별 향기성분의 조성)

  • Kang, Seong-Koo;Kang, Seong-Hoon;Choi, Ok-Ja;Kim, Young-Whan;Kim, Yong-Doo
    • Journal of the Korean Society of Food Culture
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    • v.11 no.3
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    • pp.403-408
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    • 1996
  • This study was carried out to investigate the volatile flavor compounds of Pinus densiflora Sieb & Zucc according to extraction solvents and steam distillation method. The research results are as follows: 29 kinds of components were extracted by extraction solvents. Hydrocarbon was the major flavor components of the Pinus densiflora Sieb & Zucc. When the flavor components were extracted by solvents and analyzed by GC-Mass, in the hexane, ${\alpha}$-pinene was the highest and the contents ${\beta}$-thujene, trans-caryophyllene, ${\beta}$-mercene, ${\beta}$-cubebene were higher; in the ethyl acetate, the ${\alpha}$-cubebene content was the highest and the contents ${\alpha}$-cubebene, 3,6,9,12,15-pentaoxanonadecan-1-ol, camphene were higher; in the ethanol, the ${\beta}$-D4-tetrahydropyran was the highest and the contents ${\gamma}$-cadinene, 3-ethyl-1,4-hexadiene, ${\alpha}$-cubebene were higher. When the volatile constituents were extracted by steam distillation method, 44 kinds of components were extracted. Hydrocarbon was the major flavor components of the Pinus densiflora Sieb & Zucc. The ${\beta}$-cubebene content was the highest and the contents trans-caryophyllene, 2-hexenal, T-muurolol, ${\delta}$-cadinene were higher. This fact indicated that volatile constituents differ depending upon the extracting solvents and method.

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Enhancement of Herboxidiene Production in Streptomyces chromofuscus ATCC 49982

  • Jha, Amit Kumar;Lamichhane, Janardan;Sohng, Jae Kyung
    • Journal of Microbiology and Biotechnology
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    • v.24 no.1
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    • pp.52-58
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    • 2014
  • Structurally, herboxidiene contains the tetrahydropyran acetic acid moiety and a side chain including a conjugated diene, and has been isolated from Streptomyces chromofuscus ATCC 49982. Its production was significantly elevated nearly 13.5-fold (0.74 g/l) in a medium supplemented with glycerol (medium No. 6A6), and was more efficacious (1.08 g/l; 19.8-fold) in fed-batch fermentation at 36 h in medium No. 6A6, from Streptomyces chromofuscus. For further enhancement, regulatory genes metK1-sp and afsR-sp from Streptomyces peucetius were overexpressed using an expression vector, pIBR25, and similarly ACCase from Streptomyces coelicolor and two genes, metK1-sp and afsR-sp, were also overexpressed using an integration vector, pSET152, under the control of the strong $ermE^*$ promoter in Streptomyces chromofuscus. Only the recombinant strains S. chromofuscus SIBR, S. chromofuscus GIBR, and S. chromofuscus AFS produced more herboxidiene than the parental strain in optimized medium No. 6A6 with an increment of 1.32-fold (0.976 g/l), 3.85-fold (2.849 g/l), and 1.7-fold(1.258 g/l) respectively.