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  • 1
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sum-over-states perturbation and finite perturbation calculations, within the ‘Solvaton’ model, are presented for the variation of some 17O and 19F chemical shifts as a function of the dielectric constant of the medium. In general, the nuclear screening and charge are predicted to increase as the dielectric constant increases. The effects of hydrogen bonding are included by means of minimum energy dimer models in some of the sum-over-states calculations.
    Additional Material: 3 Tab.
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  • 2
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 3
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: With a view to developing biomaterials for semipermanent substitution, we have studied a composite material constituted with collagen and a synthetic polymer which possesses high tissue compatibility. This collagen - synthetic polymer composite was applied as a support for immobilization of enzymes for the purpose of providing a material surface with biological function. The enzymes, urokinase and trypsin, were successfully bound to the collagen membrane layer which had been activated by acyl azide formation of its carboxyl groups. The enzyme-bearing composite material showed excellent catalytic activity toward a protein substrate as well as a low-molecular-weight synthetic substrate. The immobilized urokinase was characterized enzymatically and compared with native urokinase. The apparent affinity of immobilized urokinase for the substrate was slightly decreased, but its intrinsic kinetic properties were not significantly affected. No decrease in its esterase activity was observed both on repeated use and on long-term storage, and its fibrinolytic activity was stable on heat or disinfection treatment. When this urokinase-bearing composite material was applied into rabbit blood vessels, its in vivo fibrinolytic activity was maintained. Thus, enzyme - collagen - synthetic polymer composites may find wide application for biomaterials and artificial organs as functional biomaterials.
    Additional Material: 7 Ill.
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  • 4
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In order to study the effects of factors governing the bioabsorption rate of polylactides, implantation tests were carried out in rabbits using various samples (20 × 10 × 2 mm3) differing in their chemical composition, residual monomer content, and molecular orientation. Copolymer samples with a higher lactic acid content showed a lower rate of absorption, whereas those with a higher unreacted monomer content were absorbed faster and showed a more drastic decrease in molecular weight. In contrast, degradation of the purified polymers was slow; the purified poly-L-lactide showed no weight change and a 50% reduction in molecular weight after 6 months of implantation. Scanning electron microscopy of the samples containing monomers showed a microporous structure extending from the surface to the inner region a few days after implantation, whereas the purified poly-L-lactide did not exhibit a microporous structural change even after 10 months of implantation.
    Additional Material: 14 Ill.
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  • 5
    ISSN: 1075-4261
    Keywords: brain microsomal membranes ; fatty acids ; learning behavior ; FTIR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We measured the Fourier transform infrared spectra of brain microsomal membranes prepared from rats fed under two dietary oil conditions with and without brightness-discrimination learning tasks: one group fed α-linolenate deficient oil (safflower oil) and the other group fed the sufficient oil (perilla oil) from mothers to offspring. The infrared spectra of microsomes under the two dietary conditions without the learning task showed no significant difference in the range 1000-3000 cm-1. Only after the learning task were the infrared spectral differences noted between the microsomal membranes from both groups. Spectral differences were observed mainly in the absorption bands of fatty acid ester at around 1730 cm-1 (sn-2 position), those of phosphate and oligosaccharides in the range of 1050-1100 cm-1, and a band at around 1145 cm-1. The infrared band of fatty acid ester at the sn-2 position in the microsomal membrane shifted to a longer wavenumber position in the perilla oil group than in the safflower oil group, suggesting a difference between both groups in hydrogen bonding of the fatty acid ester with water. A band observed at 1055 cm-1 and a small band at around 1145 cm-1 in the second derivative spectrum decreased in intensity in the perilla oil group after learning task. These bands were assigned mainly to the oligosaccharide C - O bond in hydroxyl groups that might interact with some other membrane components. These results suggest changes in hydration of membrane surface and modification in oligosaccharide environment (removal or modification) of microsomes, which may be correlated in part with dietary oil-induced changes in learning performance. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 281-290, 1997
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 625-632 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of LiCl, NaCl, and CsCl as univalent salts, and of CaCl2, ZnCl2, and MgCl2 as divalent salts, on the α and antiparallel β-sheet, and random conformations of poly(L-lysine) (PLL), in water at room temperature were examined by means of CD and compared quantitatively on the basis of elliptical strength at the maximal peak. Changes in the α-helical and antiparallel β-sheet helical conformations of PLL were markedly dependent on the salt concentrations of LiCl, NaCl, and CsCl, which induced decreases in negative intensity in that order. The CD spectrum of the random conformation, the most disordered form, displayed positive cotton effect in concentrations of these salts up to 3.0M and a negative peak in concentrations of 6.0M. The effect of these salts on the random conformation of PLL was stronger than that on the α- and β-conformations in higher concentrations. The CD spectrum of the random conformation in the presence of CaCl2, ZnCl2, and MgCl2, on the other hand, showed negative cotton effect in salt concentrations as low as 3.0M. It was impossible, however, to measure the effect on α- and β-conformations of ZnCl2 and MgCl2 above concentrations of 10 mM because of a solubility problem with salts in alkaline solution.
    Additional Material: 5 Ill.
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