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  • 1980-1984  (3)
  • 1982  (1)
  • 1981  (2)
Material
Years
  • 1980-1984  (3)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 25 (1981), S. 95-103 
    ISSN: 1432-0630
    Keywords: 74.70.Dg ; 74.60.-w ; 73.60.Ka
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We have studied the influence of oxygen on the superconducting properties of thin films of lead, indium and tin deposited on glass or sapphire substrates. In addition, the morphological microstructure was investigated by scanning electron microscopy. The film thickness was 1.0 μm, and the partial pressure of O2 during the film deposition was raised up to 1×10−4 Torr. In all three materials the development of a granular structure and a strong increase in the residual electric resistivity was observed due to the O2-treatment. Whereas in the Pb films no change of the critical temperature was found, the In films deposited on glass substrates showed a slight increase ofT c due to the oxygen. The strongest increase ofT c (up to 8%) was observed in the O2-treated Sn films. These results are discussed in terms of the McMillan theory. From our measurements of the critical current densityj c we conclude that edge pinning is dominant in the undoped films. All three materials showed a strong increase ofj c due to the O2-treatment which must be interpreted in terms of bulk pinning.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 63 (1981), S. 247-252 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents Using numerical methods, the eddy current distribution is calculated in a conducting wedge induced by two exciting wires located symmetrical to the wedge. The complex equationsystem is solved by the relaxation-method of Gauß-Southwell and the solution is verified for the case of a conductiong semispace.
    Notes: Übersicht Für den Fall der symmetrisch zu einem leitenden Keil angeordneten, gegensinnig von sinusförmigem Wechselstrom durchflossenen Doppelleitung, wird mit Hilfe numerischer Methoden die Wirbelstromverteilung im Keil berechnet. Das entstehende komplexe Gleichungssystem wird nach dem Relaxationsverfahren von Gauß-Southwell gelöst und die Ergebnisse für den leitenden Halbraum kontrolliert.
    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: N-Ethylaziridine (1) was polymerized in water with HCl as initiator and copolymerized with N-(2-hydroxyethyl)aziridine (2). Rapid propagation and termination reactions were observed. The maximum yield increases with the initiator concentration, whereas the molecular weight decreases. This is due to the difference in basicity between the tertiary N-atoms of the two monomers and the tertiary and the terminal secondary N-atoms of the polymers, which causes tranfer and termination reactions. Macrocycles with a side chain on a quaternary N-atom are formed. During the copolymerization, the more basic 1 is preferentially incorporated into the copolymer chain. The copolymerization parameters can be estimated roughly on the basis of basicity considerations: r1 〉 1; r2 〈 1. The ratio of the rate constants (propagation to termination) is lower for 1 than for 2. This is due to the fact that the basicity difference between the monomer and the tertiary N-atoms of the polymer is higher for 1 than for 2. By reaction of thionyl chloride with the copolymers the desired hydrochlorides of the N-(2-chloroethyl) derivatives are obtained. The neutralisation with alkali did not result the free bases, since the products formed are rather due to side reactions.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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