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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 53 (1991), S. 317-323 
    ISSN: 1432-0630
    Keywords: 61.70.Jc ; 81.10.Dn ; 73.40.Ty
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Epitaxial lateral overgrowth (ELO) on thermally oxidized and patterned (111) Si is effected by liquid phase epitaxy (LPE). It produces Si layers spreading out on the amorphous SiO2 which are either perfectly grown defect-free or, coexisting, defective layers containing dislocations. High voltage electron microscopy of the defective layers reveals regular arrangements of the dislocations which result from glide and multiplication processes governed by the elastic interactions between the dislocations. The nucleation of the first dislocations during the ELO process is attributed to a slight warping of the substrates. A corresponding bending of the epitaxial layer induces mechanical stress, which may exceed the critical value at the oxide edges of the seeding windows where the first dislocations nucleate. The characteristics of the dislocation arrangements and lattice imaging results support this model. Suggestions are made for ways to reduce stress and, thus, avoid dislocation formation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-2451
    Keywords: Gentamicin added to polymethylmethacrylate ; Relesae of gentamicin ; Urine concentration ; Serum concentration ; Gentamicin plomb in femur ; Gentamicin concentration at site of action ; Bactericidal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Pharmakokinetische In-vivo-Versuche zeigten bei Ratten und Hunden eine deutliche Freisetzung und Resorption von in Polymethylmethacrylat (Palacos® R) inkorporiertem Gentamycin (Refobacin®). Bei Ratten, denen Prüfkörper aus Gentamycin-Palacos® R unter die Rückenhaut implantiert worden waren, konnten im Serum geringe Gentamycinkonzentrationen nur innerhalb der ersten 3 Tage p. op. gemessen werden. Die Konzentrationen im Harn nahmen im Lauf der ersten Tage p. op. rasch ab: nach 22 Wochen war kein Gentamycin mehr nachweisbar. Hunde, denen Gentamycin-Palacos® R-Plomben in den Femurschaft eingesetzt wurden, zeigten im Serum keine oder nur Spuren einer Gentamycinaktivität nur innerhalb der ersten 5 Std p. op. Auch die Harnkonzentrationen waren sehr gering und lagen spätestens ab dem 4. Tag p. op. unter 1 μg/ml. Nach 16 bis 24 Tagen p.op . war im Harn kein Gentamycin mehr nachweisbar. Die Verwendung einer gekammerten Plombe machte bei Hunden die Messung der Gentamycinkonzentration am Wirkort möglich. Mit dieser Versuchsanordnung wurden in dem sich in der Kammer sammelnden Sekret für die ätiologisch üblicherweise auftretenden Krankheitserreger sicher bacterizid wirksame Gentamycinkonzentrationen gemessen. Aus technischen Gründen war eine Beobachtung maximal nur bis zu 9 Tagen möglich. Die genannten Ergebnisse sind auf andere Antibiotica und/oder Knochenzemente nicht übertragbar.
    Notes: Summary Pharmacokinetic in vivo tests in rats and dogs have shown that gentamicin (Refobacin®) incorporated in polymethyl methacrylate (Palacos® R) is distinctly released and absorbed by the body. Samples of Gentamicin-Palacos®R (1 g of gentamicin sulfate, 40 g of polymer powder) were implanted under the dorsal skin of rats. Slight gentamicin concentiations in the serum were only observed in the first 3 days after implantation. The urine concentrations decreased rapidly within the first few days; after 22 weeks no gentamicin was detectable. In dogs the shaft of the femur was filled with Gentamicin-Palacos® R. Serum analysis showed either no gentamicin activity at all, or only traces thereof in the first 5 h after treatment only. The concentration in the urine was also only slight and measured less than 1 μg/ml by the 4th day at the latest. 16 to 24 days after treatment no gentamicin was detectable in the urine. A built-in cavity was used in dogs thus making it possible for the gentamicin concentration to be determined at the site of action. Via this procedure the secretion which collected in the cavity showed gentamicin concentrations which would definitely have a bactericidal effect on the usual pathogens involved. Technical reasons prevented a follow-up from being made for more than 9 days after administration. The results obtained are not transferable to other antibiotics and/or bone cements.
    Type of Medium: Electronic Resource
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