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  • 1
    Electronic Resource
    Electronic Resource
    A scanning electron microscopic study of the growth of hydroxyapatite crystals (1972)
    Springer
    Calcified tissue international 10 (1972), S. 91-102 
    Details
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Calcification ; Phases ; Growth ; Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La croissance cristalline de l'hydroxyleapatite à 25° et à pH constant de 7.4 a été étudiée à l'aide du microscope électronique à balayage. La technique reproductible de croissance par ensemencement à partir de solutions stables sursaturées est utilisée efficacement pour produire des échantillons de minéral à divers stades distincts de croissance. Des changements de phase sont observés avec le progrès de la croissance; ils correspondent dans le temps avec les résultats cinétiques obtenus antérieurement. Un essai de rationalisation est tenté à la lumière des mécanismes proposés pour la formation d'hydroxyleapatite dans des conditionsin vivo.
    Abstract: Zusammenfassung Das Kristallwachstum von Hydroxyapatit bei 25° und einem konstanten pH von 7,4 wurde mit Hilfe eines Raster-Elektronenmikroskopes studiert. Die reproduzierbare Technik des Keimwachstums aus stabilen übersättigten Lösungen wurde mit Erfolg verwendet, um Mineralproben in verschiedenen bestimmten Stadien des Wachstums zu erhalten. Phasenveränderungen wurden beim fortschreitenden Wachstum beobachtet, und diese stimmten zeitlich gut überein mit kinetischen Resultaten, über welche früher berichtet wurde. Es wurde versucht, diese Beobachtungen zu erklären in Anbetracht von Mechanismen, welche für die Bildung von Hydroxyapatit unterin vivo-Bedingungen vorgeschlagen wurden.
    Notes: Abstract The crystal growth of hydroxyapatite at 25° and at a constant pH of 7.4 has been studied with the aid of a scanning electron microscope. The reproducible technique of seeded growth from stable supersaturated solutions was used effectively to produce samples of the mineral at various distinct stages of growth. Phase changes were observed as the growth proceeded and these corresponded favorably in time with kinetic results reported earlier. An attempt was made to rationalize the observations in light of mechanisms proposed for the formation of hydroxyapatite under conditions foundin vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012539
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dose responses and relationships between anticholinergic activity and mood with tricyclic antidepressants (1972)
    Springer
    Psychopharmacology 25 (1972), S. 205-217 
    Details
    ISSN: 1432-2072
    Keywords: Imipramine ; Tricyclic Antidepressants ; Salivation ; Anticholinergic Activity ; Mood Change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A pilot study showed that single doses of imipramine (100 mg) produced a maximum reduction in salivation after 3 h which persisted for 72 h after drug. Effects after 3 h were reproducible in 3 subjects and differed from control levels on all 6 occasions of testing. A double-blind study in 6 subjects was then carried out to ascertain whether a dose response measured by salivary flow could be obtained for imipramine and dimethacrin, a developmental drug with fewer anticholinergic effects in animals. A further objective was to study the effects of both drugs on subjective feelings of mood, appetite, and dry mouth in order to make correlations between these effects and the anticholinergic activity. Results showed a linear log-dose response reduction in salivation for imipramine which differed significantly from placebo and dimethacrin. Significant changes on the Clyde Mood Scale in sleepiness and friendliness factors occurred only with imipramine, raising the question of whether there is a causal relationship between the central actions of imipramine and its anticholinergic activity. The significant decrease in friendliness with imipramine as compared to placebo suggests that anticholinergic activity is unlikely to be responsible for antidepressant effect, but may account for the drug's sedative action.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00422502
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Glass transition temperature as a guide to selection of polymers suitable for PTC materials (1973)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 13 (1973), S. 462-468 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: It has been shown that the only way to predict the size of the PTC effect displayed by a crystalline polymer when filled with conductive particles is through the knowledge of the glass transition point of the polymer. The size of the PTC anomaly is found to decrease sharply with rise in glass transition temperature and for a polymer to be a useful PTC material its glass transition must be below 0°C. It has not been possible to explain this relationship by any of the current theories of the PTC mechanism in filled polymers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760130611
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Stability of polymer composites as positive-temperature-coefficient resistors (1974)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 706-716 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: This is a study of materials which are positive-temperature-coefficient resistors. Such materials, composed of conductive particles dispersed in a crystalline polymeric matrix, have been found to be of limited stability. An example is carbon black in high-density polyethylene. On repeated cycling through the anomaly temperature or on extensive heating at or above the anomaly temperature, the room temperature resistivity rises and the anomaly height falls to zero. This phenomenon has been shown to be caused by the absorption of oxygen by the polymer matrix which alters the structure, reduces the crystallinity, and induces an unusual form of crosslinking of a reversible nature.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760141009
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    Paper (German National Licenses)
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