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  • 1
    Electronic Resource
    Electronic Resource
    Complex composition distribution of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 6516-6521 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00123a018
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  • 2
    Electronic Resource
    Electronic Resource
    Cocrystallization of isothermally crystallized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 2046-2048 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00033a032
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetically accessible compact conformations of chain molecules (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 108 (1998), S. 8705-8712 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The kinetic accessibility of various compact conformations of chain molecules is studied using a short self-avoiding chain on a three-dimensional cubic lattice. The kinetic accessibility of a compact conformation depends on the conformational energy and the distances from the other conformations along kinetically possible trajectories. We focus on the kinetic distances. We consider a chain in a poor solvent, having multiple lowest-energy compact conformations. The chain collapse from an arbitrary conformation to one of the lowest energy conformations is investigated. Though the lowest energy states would be occupied with the same probability in equilibrium, the probabilities for a first hit are not necessarily all the same and they indeed are not. We show that the hit probability at low temperature can be used as a measure of the kinetic distances from other conformations. The hit probability is investigated under two kinetic processes. One is a Monte Carlo dynamic process and the other is a "contact-set stepping" process, in which kinetic distances between conformations are defined based on sets of contacts. The two kinetic processes exhibit similar results showing that both processes well reproduce the kinetic behavior of chain molecules. Through the characterization of the states with large hit probability at low temperature, we show that the influence of the kinetic distances on the kinetic accessibility can be explained by domain structure or locality of contacts. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476299
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  • 4
    Electronic Resource
    Electronic Resource
    Biosynthesis of polyesters from some unusual amino acids having linear carbon skeleton by Alcaligenes eutrophus (1994)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 195 (1994), S. 3699-3707 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The biosynthesis of polyesters by Alcaligenes eutrophus from some unusual amino acids having a linear carbon skeleton was investigated. Poly(3-hydroxybutyrate) (P(3 HB)) or poly(3-hydroxy-butyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) was found to be accumulated in the cells when a-amino acids with a linear carbon skeleton were used as the sole carbon source. The 3HV mole fractions in copolyesters ranged up to 70%. The following pathway is proposed; the a-amino acid with a linear carbon skeleton is at first metabolized to form the a-keto acid by oxidative deamination with transaminase. Then the resulted a-keto acid is converted into acyl-CoA by oxidative decarboxylation, and the acyl-CoA is further metabolized to the 3HB or 3HV unit through the same pathway as the fatty acids. P(3HB) was found to be produced from a-amino acids having a linear skeleton with odd carbon number, whereas P(3HB-co-3HV) arises from a-amino acids having a linear skeleton with even carbon number. This regularity is inverse to that of fatty acids, because amino acids are decarboxylated, with a reduction of one carbon atom, and then enter into the same synthetic pathway as fatty acids to form polyesters. On the other hand, when ω-amino acids with a linear carbon skeleton were used as the sole carbon source, accumulation of polyesters was scarcely detected.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1994.021951116
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  • 5
    Electronic Resource
    Electronic Resource
    Infrared analysis on blends of poly(3-hydroxybutyric acid) and stereoregular poly(vinyl alcohol): influence of tacticity of poly(vinyl alcohol) on crystallization of poly(3-hydroxybutyric acid) (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 869-880 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The extens of crystallization of poly(3-hydroxybutyric acid) (P(3HB)) in blends of P(3HB) with stereoregular poly(vinyl alcohol) (PVA) have been studied by means of infared spectroscopy. The degree of crystallinity of P(3HB) was found to decrease by blending with atactic PVA when PVA was the predominant component of the blend. In P(3HB) blends with highly syndiotactic PVA, a significant suppression of P(3HB) crystallization was observed in a wider range of blend composition than that in P(3HB)/atactic PVA blends. These results are consistant with previous results obtained by means of solid-state 13C nuclear magnetic resonance and differential scanning calorimetry. In blends with highly isotactic PVA, P(3HB) was found to crystallize in the same way as in pure P(3HB).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021970309
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  • 6
    Electronic Resource
    Electronic Resource
    Thermal and morphological study of fractionated poly(3-hydroxybutyric acid-co-3-hydroxypropionic acid) (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 3539-3557 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal and morphological characteristics of fractionated poly(3-hydroxybutyric acid-co3-hydroxypropionic acid)s (P(3HB-CO-3HP)) with narrow comonomer compositional distribution, as well as the natural poly(3-hydroxybutyric acid) (P(3HB)) and chemosynthetic poly(β-propiolactone) (PPL) were studied by means of differential scanning calorimeter (DSC) and infrared spectroscopy (IR). It is seen that melting point (Tm), heat of fusion (ΔH) and glass transition temperature (Tg) decrease with the increase of the content of 3HP units up to 60.5 mol-%. Employing 13C NMR in the solution, the sequence distributions of the fractionated copolyesters were revealed not to be in accordance with the results of the random statistical model. The carbonyl IR absorption bands were further resolved by curve fitting into several components stemming from the bond stretchings in the different molecular environments known as the amorphous, crystalline and intermediate regions. It is demonstrated that the contributions which belong to the crystalline regions show intrinsic absorption peaks at 1724.0, 1723.8 and 1729.1 cm-1 for P(3HB), P(3HB-CO-3HP)s and PPL, respectively. In the case of P(3HB-CO-3HP)s, the relative intensities of contributions originating from the crystalline regions decrease with the increase of 3HP units up to 60.5 mol-%. However, only the P(3HB) type of lattice structure is formed despite the variation of the 3HP unit content. Moreover, the effect of the substrates (silicon wafer and KBr) used for preparation of the IR samples on the crystallization behavior was also investigated.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021981118
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  • 7
    Electronic Resource
    Electronic Resource
    Microstructure of copoly(3-hydroxyalkanoates) produced in the anaerobic-aerobic activated sludge process (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 39 (1996), S. 183-189 
    Details
    ISSN: 0959-8103
    Keywords: polyhydroxyalkanoate ; copolyester ; microstructure ; NMR ; 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: The sequence structures of bacterially synthesized copoly(3-hydroxyalkanoates), isolated from the sludge developed in the anaerobic-aerobic waste-water treatment process containing propionate as a carbon source, were analysed by 13C NMR spectroscopy. These copolyesters were composed of four different monomer units, 3-hydroxybutyrate, 3-hydroxyvalerate, 3-hydroxy-2-methylbutyrate and 3-hydroxy-2-methylvalerate. By using water/acetone mixed solvent, one of the copolyester samples was fractionated into fractions by differences in average molecular weights as well as in monomer compositions. The carbonyl carbon resonances, split due to differences in diad sequences, were analysed on the basis of Bernoullian statistics. It is suggested that these copolyesters were mixtures of random copolymers with different monomer compositions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Crystallization and compatibility of poly(vinyl alcohol)/poly(3-hydroxybutyrate) blends: Influence of blend composition and tacticity of poly(vinyl alcohol) (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 17-24 
    Details
    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: Compatibility of a crystalline/crystalline polymer blend, poly(vinyl alcohol) (PVA)/poly(3-hydroxybutyrate) (PHB), was studied by high-resolution solid-state 13C-NMR spectroscopy. The 1H T1 measurement demonstrated that both the compatibility and the domain size depend on the composition of the blend. The PVA/PHB blend is compatible only when the blend contains a large amount of PVA. The domain sizes of the compatible blend are less than 200 Å. In the pulse saturation transfer (PST) MAS NMR spectra, the carbonyl carbon resonance from PHB showed a downfield shift, which indicates that the compatibility of the PVA/PHB blends is due to the hydrogen-bonding interaction in the amorphous phase. The DSC measurement showed that the compatible blends adopt low crystallinity for both PHB and PVA. The crystallization in these blends is likely to be distributed by the hydrogen-bonding interaction in the amorphous phase. The compatibility of PVA/PHB is also affected by the tacticity of PVA. The compatible composition range of the syndiotacticrich PVA/PHB blend is wider than that of the atactic-PVA/PHB blend. It is likely that the capacity to form the hydrogen bond depends on the tacticity of PVA. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070560103
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  • 9
    Electronic Resource
    Electronic Resource
    Morphological study of bacterial poly(3-hydroxybutyrate-co-3-hydroxypropionate) (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 2467-2480 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The solid-state structure of a bacterially synthesized copolyester, poly(3-hydroxybutyrate-co-3-hydroxypropionate), P(3HB-co-3HP), with the 3HP content ranging from 0 to 37 mol-%, was analyzed by 13C solid-state high-resolution NMR, X-ray diffraction, differential scanning calorimetry and optical microscopy. For the copolymers containing up to about 40 mol-% 3HP, it was confirmed from the X-ray diffraction measurement that the crystallographic parameters are similar to those of P(3HB) homopolymer and the degree of crystallinity decreases as the 3HP content increases. From the measurement of 13C spin-lattice relaxtion time (T1c) using solid-state high-resolution 13C NMR, it was concluded that the crystalline region is composed only of 3HB units, suggesting that the cocrystallization of 3HB and 3HB units in the same crystal lattice does not occur in P(3HB-co-3HP). This conclusion is supported by the thermal properties and the rate of spherulite growth.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021970811
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  • 10
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    Miscibility and Phase Structure of Blends of Poly(ethylene oxide) with Poly(3-hydroxybutyrate), Poly(3-hydroxypropionate), and Their Copolymers (2002)
    American Chemical Society
    Details
    Publication Date: 2002-01-01
    Print ISSN: 0024-9297
    Electronic ISSN: 1520-5835
    Topics: Chemistry and Pharmacology , Physics
    Published by American Chemical Society
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