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  • 1
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: HA-ceramics used in human surgery as osteoconductive surfaces show a great variety of characteristics. Certain characteristics such as grain size, porosity, and surface area, are controlled by the sintering temperature of the slurry. We grew L-929 fibroblast cells on HA-ceramic disks that had been sintered at different temperatures ranging from 850°-1350°C. The cell line growth rate was lower on ceramic disks than on the culture-grade polystyrene used as a negative control. Cell growth correlated with the ceramic sintering temperature although no significant difference in the cell adhesion to the different ceramics was shown. Growth rate on ceramics sintered at low temperatures (850° and 950°C) was negative whereas it was positive on disks sintered at higher temperatures. When the cells were separated from the disks by a polycarbonate membrane, the growth rate was negative on those membranes in contact with low-temperature sintered disks and positive on the high-temperature sintered disks. The calcium and phosphorus concentration in the culture medium in contact with ceramics sintered below 1050°C decreased during the culture period. Ceramics sintered between 1100° and 1250°C brought about an increase in Ca and P concentrations while ceramics sintered at higher temperatures did not induce any changes. SEM examination of the 850° and 1200°C sintered ceramics showed that the 850°C sintered ceramics consisted of small grains with pores between them and the 1200°C sintered ceramics were made of larger grains without any visible pores, thereby decreasing the surface of material in contact with the culture medium. This difference in surface area was confirmed by the fact that the amount of albumin adsorbed onto the ceramic was dependent on the sintering temperature. In conclusion, the modification of the culture medium brought about by high-surfaced ceramics could influence the growth of cells with which such ceramics come in contact. © 1997 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A number of hydroxytelechelic polybutadiene samples were silylated. The completeness of the silylation reaction allows the determination of the number average functionality by continuous wave 1H NMR. The protonated groups of the silylated alcohol functions were identified at 100 and 250 MHz. It is observed that these three primary alcohol functions do not have the same reactivity towards hexamethyldisilazane as silylating agent.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The examination of H2O2-initiated hydroxytelechelic polybutadienes polymerized by H2O2 initiation by 1H NMR and 13C NMR allows the identification of three main primary alcoholic groups: α-unsaturated, β-substituted/α-unsaturated and γ-unsaturated. From 1H NMR accumulated spectra, it has been possible to calculate the number average OH-functionalities of the polymers. These should be slightly under-estimated because of the possible presence of secondary and tertiary alcoholic groups whose concentrations, however, should be very small. The nature of these alcohol functions gives information concerning the likely initiation, transfer and termination mechanisms of the radical polymerization of butadiene by H2O2 in alcoholic media.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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