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  • Polymer and Materials Science  (4)
  • Surface enhanced resonance Raman scattering spectroscopy  (1)
  • 1
    ISSN: 1432-1017
    Keywords: Key words Raman ; Surface enhanced resonance Raman scattering spectroscopy ; Flavins ; Flavocytochrome P450 BM3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Flavocytochrome P450 BM3, an FMN-deficient mutant (G570 D), the component reductase and an FAD-containing domain were studied using surface enhanced resonance Raman scattering (SERRS). They were compared to spectra obtained from the free flavins FAD and FMN. For the holoenzyme and reductase domain, FMN is displaced during SERRS analysis. However, studies with the G570 D mutant indicate that FAD is retained in its active site. Analysis of SERRS frequencies and intensities provides information on the nature of the flavin binding site and the planarity of the ring, and enables an interpretation of the hydrogen bonding environment around ring III of the isoalloxazine moiety. Hydrogen bonding is strong at N3–H, C2=O and C4=O, but weak at N5. Structural alteration of the FAD domain of P450 BM3 is caused by removal of the FMN-binding domain. Further, the hydrogen bond at N3–H is lost and that at C2=O is weakened and the isoalloxazine ring system in the FAD domain appears to adopt a more planar arrangement. Alterations in the environment of the FAD in its isolated domain are likely to relate to changes in the redox properties and suggest a close structural interplay of FAD with the FMN-binding domain in intact flavocytochrome P450 BM3.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 1659-1672 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Solubility and spectroscopic evidence are presented to support the formation of A-B block copolymers between monomers undergoing anionic polymerization (A units) and monomeric formaldehyde (B units). Comonomers included in the study were styrene, methyl and n-butyl methacrylate, acrylonitrile, isoprene, and N, N-di-n-butylacrylamide. Similar evidence is presented on the formation of B-A-B copolymers between styrene and α-methylstyrene and formaldehyde; an A-(B-C) random copolymer of styrene, formaldehyde, and phenyl isocyanate (C) was also prepared. Experimental details for the preparation of high-purity, monomeric formaldehyde suitable for such work is described in some detail. It should be emphasized that this study was directed primarily toward showing the feasibility of preparing formaldehyde block copolymers; therefore, further work is needed to establish the quantitative nature of these reactions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 48 (1960), S. 17-25 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Promoted preformed solids catalyze polymerization of ethylene and propylene and formation of copolymers of ethylene with such olefins as propylene and butene-1. The structure of the copolymers helps explain how they are formed and their properties. Kinetic studies alone do not distinguish between polymerization mechanisms involving either anionic centers or ion-radicals. Structural studies of ethylene-propylene copolymers of low propylene content show that they contain isolated propylene units in accord with the ion-radical theory of polymerization in a chemisorbed layer. Isolated short sidechains, so introduced, reduce density and increase flexibility. They give copolymers with flow properties more like those of linear polyethylenes than those of branched polyethylenes with long sidechains. Furthermore, they interfere with recrystallization and crystal growth; the resulting polymers have better stress-crack resistance and form clearer films.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 61 (1962), S. 39-44 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Copolymers of ethylene and C14-labeled propylene were prepared with a metal-oxide catalyst which polymerizes ethylene to a high density polymer. Methyl branches arising from the propylene were counted radiochemically and then related to the infrared absorption of films at 8.7 μ. This band was then used independently to determine methyl branching of a series of ethylene-propylene copolymers that differed in density and stiffness. Both properties decrease in value with an increase in branching.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 2001-2012 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Emulsion polymerization of methacrolein produces a polyacetal which can be converted through the action of sodium hydroxide to an alternating copolymer of methallyl alcohol and sodium methacrylate. Support for the alternating structure was gained primarily through a study of the polylactone formed through subsequent acidification of the sodium salt. Thus, the poly(methallyl alcohol-sodium methacrylate) copolymer was acidified under selected conditions to give a soluble polylactone containing 14.2 mole-% of residual acid and hydroxyl groups. This number agrees quite closely with the value of 13.5 mole-% which one would predict from the random cyclization of a true alternating copolymer. Cyclization of a random copolymer of poly(methallyl alcohol-sodium methacrylate) in a random fashion would have resulted in a value of about 36.8 mole-%. The results also support both the 1,2 vinyl polymerization of methacrolein and a nonrandom attack of the polymethacrolein by base. In a completely separate set of experiments, the value of r1 and r2 for the copolymerization of styrene (M1) and methacrolein (M2) were determined to be 0.22 ± 0.02 and 0.88 ± 0.02, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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