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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 284 (1974), S. 195-206 
    ISSN: 1432-1912
    Schlagwort(e): Diazepam ; Tyrosine Hydroxylase ; Isoproterenol ; Reserpine ; 6-Hydroxydopamine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The increase in in vitro adrenal tyrosine hydroxylase (TH) activity caused by drugs which produce an increase in preganglionic nerve activity as a result of actions outside the central nervous system was increased by the administration of diazepam. However, other central nervous system depressants such as pentobarbital, phenobarbital and diphenylhydantion were not found to share this property. Adrenal enzyme induction provoked by isoproterenol and 6-hydroxydopamine was increased by diazepam administration, whereas that produced by reserpine or insulin was not altered. The enhanced adrenal TH activity produced by diazepam pretreatment and isoproterenol administration could not be attributed to an increase in intensity or to an altered body temperature. Administration of 5-hydroxytryptophan can antagonize the induction of adrenal TH produced by isoproterenol, however, it did not block the TH induction produced by concurrent administration of diazepam and isoproterenol. The effect of diazepam on adrenal TH induction may be the result of its ability to interfere with central nervous system amine containing nerve functions which modulate preganglionic nerve activity, but the particular neurotransmitter system involved has not been determined.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 31 (1989), S. 123-143 
    ISSN: 1573-4889
    Schlagwort(e): high-temperature sulfidation ; fluidized bed combustor ; nickel-base alloys ; 300-series stainless steels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract The modes of initiation and propagation of corrosion attack on a series of high-temperature alloys were studied in synthetic gas mixtures at 900°C. The gas mixtures were intended to simulate the oxygen and sulfur partial pressures experienced in reducing zones in a coal-fired fluidized-bed combustor and comprised mixtures of CO, CO2, and SO2. The alloys studied were candidates for in-bed heat exchanger tubing for an air-heater cycle operating at 843°C and 300–500 psig and so ranged from type 300-series stainless steels to nickel-base alloys. With the exception of two FeCrAlY alloys and types 304 and 347 stainless steels, it was found that sulfidation corrosion could be initiated on all the alloys within 0.25 hr; the rate of propagation of the corrosive attack depended on the flux of SO2 in the environment and on the nickel content of the alloys. The presence of iron in the alloys appeared to slow the initiation of sulfidation, by forming a continuous iron oxide layer. The effects of various alloying additions are discussed, and a schematic model for the initiation of sulfidation is proposed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Oxidation of metals 31 (1989), S. 325-340 
    ISSN: 1573-4889
    Schlagwort(e): sulfidation ; nickel-base alloys ; iron-base alloys ; fluidized-bed combustion ; deposit-related attack
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: Abstract This study addresses questions concerning the likelihood of sulfidation attack of heat-exchanger alloys beneath deposits of sulfur-sorbent material in fluidized-bed combustors. Alloy specimens were exposed at 900°C in calcium sulfate-calcium oxide and calcium sulfide-calcium oxide mixtures, in environments in which the oxygen partial pressures were fixed at values corresponding to the equilibrium values for each solids mixture, using controlled ratios of CO and CO2. The only source of sulfur in these systems was the calcium sulfate or sulfide. Sulfidation attack of nickel-base alloys occurred in both mixtures, the calcium sulfide-calcium oxide mixture being the more aggressive. Iron-base alloys were less susceptible to attack, although susceptibility increased with increasing nickel content. FeCrAlY-type alloys were resistant to attack. Comparison with corrosion behavior under conditions in which the oxygen and sulfur partial pressures were the same as those used here, but in which the sulfur source was in the gas phase, indicates that the form of the sulfidation attack is similar but that its progress is much slower under solid deposits.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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