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  • Polymer and Materials Science  (2)
  • Ultrastructure  (2)
  • 1975-1979  (4)
  • 1960-1964
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 171 (1976), S. 467-482 
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Secretion process ; Protein synthesis ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary After the application of parachlorophenylalanine (pCPA), an amino acid analogue, paracrystalline inclusions are observed in the exocrine pancreas of the rat. The formation of the paracrystalline structures varies according to the dose and the time of examination. Although the first alterations can be seen in the Golgi apparatus and the condensing vacuoles, the main localization of these structures is within the cisternae of the RER. At the same time as degenerative changes occur in the cells, involving autophagic and heterophagic processes, regneration also takes place. With the freeze-fracturing method, the paracrystalline inclusions are interpreted as lamellae or plates of probably altered secretory proteins in extremely extended RER-cisternae. The fracture surfaces of the paracrystals show a periodicity of about 80 Å running diagonally to the main axis of the paracrystalline structures, which are mainly oriented from the basal parts of the exocrine pancreatic cells to the cell apices. The mechanism of paracrystalline formation is discussed on the basis of the morphologic results. It could be shown that after pCPA administration the amylase content is decreased concomittantly with degranulation. pCPA seems not to be incorporated into secretory proteins; high intracellular concentrations, however, are required to induce the formation of the paracrystalline structures. This morphological study is the basis for other studies dealing with secretion and intracellular transport in the pancreatic acinar cell under experimental conditions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 177 (1977), S. 459-474 
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Isolated cells ; Cell membrane ; Tight junctions ; Gap junctions ; Ultrastructure ; Freeze-fracturing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the cell membrane and intercellular junctions was studied after isolation of exocrine pancreatic cells by tryptic digestion and mechanical treatment. The number and distribution of membrane associated particles does not change significantly when acinar cells in situ are compared to those after the isolation procedure. However, intercellular junctions undergo distinct alterations. Gap junctions in normal pancreatic cells are macular in shape and localized at the lateral parts of the cell membrane. In isolated acinar cells gap junctions are irregularly shaped, more extended, and frequently associated with tight junctions. Tight junctions form belt-like structures which are found to persist after isolation but subsequently become elongated and interrupted. Thus extensive macular areas of tight junctions develop. Further, the strands on the P-face and the grooves on the E-face of freeze-fracture replicas change in array, dissociate, and become loosely packed on large membrane areas. The present investigation shows that the intramembranous proteins of tight and gap junctions are mobile structures within the fluid membrane. The shape of their array is dependent on the form of the intercellular contact zone.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 30 (1979), S. 853-857 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Ion bombardment - a method for Investigating and preventingDuring the last years the technique of ion implantation gained increasing importance. It allows to introduce very element at any temperature in any material and to produce stable as well as metastable alloys. Applications for this method in corrosion science are pointed out in the light of results from different laboratories.First the stability of titanium and zirconium against thermal oxidation after ion bombardment is discussed. Then the passivation behaviour of iron irradiated with chromium and tantalum ions is mentioned. The third section deals with aqueous corrosion of iron and hydrogen evolution in diluted acids. The implantation of lead, gold and platinum is shown to modify the reaction rates by several orders of magnitude. Finally the possibility of using ion bombardment for the investigation of hydrogen embrittlement of metals is demonstrated.The results prove this method for the formation of alloys to allow studies being not accessible with more conventional techniques.
    Notes: In den letzten Jahren hat die Technik der Ionenbestrahlung von Materialien steigende Bedeutung gewonnen. Sie gestattet es, beliebige Elemente bei jeder Temperature in beliebige Basismaterialien einzubringen und sowohl stabile als auch metastabile Oberflächenlegierungen herzustellen. An Hand einer Reihe von Beispielen aus in- und ausländischen Labors werden Anwendungsmöglichkeiten in der Korrosionsforschung vorgestellt.Zunächst wird die Oxidationsbeständigkeit von mit Ionen bestrahltem Titan und Zirkon diskutiert, sodann das Passivierungsverhalten von Eisen, das mit Chrom- und Tantalionen beschossen wurde. Der Befund, daß die Korrosionsgeschwindigkeit und die Wasserstoffentwicklungsrate von Eisen in verdünnter Säure durch Implantation von Blei-, Gold-und Platinionen um mehrere Zehnerpotenzen verändert werden können, wird mitgeteilt. Schließlich wird die Möglichkeit, Ionenbeschuß zur Untersuchung der Wasserstoffversprödung von Metallen heranzuziehen, aufgezeigt. Die Ergebnisse beweisen, daß diese „Legierungsmethode“ Untersuchungen ermöglicht, die mit konventionellen Techniken kaum zugänglich sind.
    Additional Material: 4 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 50 (1978), S. 669-673 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Methodical design of a plant for the production of CaO for use in breathing equipment. The methodology of design nowadays taught at all technical universities can also be profitably applied to chemical engineering. Methodical examination of the production process for CaO used as CO2 absorber in respiratory equipment leads to a considerable improvement in product quality and to more economical production.
    Additional Material: 7 Ill.
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