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  • 1
    ISSN: 1434-6079
    Keywords: 76.30F ; 76.30H ; 71.70J
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The possibilities to identify small diluted paramagnetic cluster defects in solids by Electron Paramagnetic Resonance are demonstrated in two examples: the Mn 4 0 cluster and a Cu-Au cluster in silicon crystals. A comprehensive picture of the clusters can be given containing the chemical nature of the constituents, the spatial arrangement, the charge states and the electronic structure.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8943
    Keywords: cold crystallization ; DSC ; heat capacity ; modulated temperature DSC ; poly(ethylene terephtalate)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The modulated temperature differential scanning calorimetric method (MT-DSC) yields three temperature dependent signals, an underlying heat capacity curve from the underlying heat flow rate (corresponding to the conventional DSC signal), and a complex heat capacity curve with a real part (storage heat capacity) and an imaginary part (loss heat capacity). These curves have been measured in the cold crystallization region for poly(ethylene terephtalate) with a modified Perkin-Elmer DSC-7. The underlying curve shows the well known large exothermic crystallization peak. The storage heat capacity shows a step change which reproduces the change in heat capacity during crystallization. This curve may be used as baseline, to separate the crystallization heat flow rate from the underlying heat flow rate curve. The loss heat capacity curve exhibits a small exothermic peak at the temperature of the step change of the storage curve. It could be caused by changes of the molecular mobility during crystallization.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-8943
    Keywords: calibration material ; calibration procedure ; DSC ; heat calibration ; heat flow rate calibration ; standards ; temperature calibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Metrologically based measuring procedures and evaluation methods are recommended as guidance for practical temperature, heat and heat flow rate calibration of DSC instruments which are largely independent of instrumental, test and sample parameters. The relevant terms are defined, the measuring procedures and evaluation methods described, calibration materials and their characteristic data stated and guidance for the sample handling provided. Reference is made to three extended papers on calibration. The recommendations were developed by the working group ‘Calibration of Scanning Calorimeters’ of the German Society of Thermal Analysis (GEFTA).
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1440
    Keywords: Nicotine ; Metabolism ; Lung ; Liver ; Phenobarbital ; Cytochrome P-450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The metabolic fate of cotinine, the major metabolite of nicotine, was studied in phenobarbital-induced and non-induced isolated perfused rat lung and liver and in isolated hepatocytes of rats and mice. The non-induced lung tissue showed low cotinine metabolizing capacity while the perfused liver was approximately four times more active. After phenobarbital pretreatment the metabolism of cotinine was increased eight-fold in the intact liver. A substantial increase in cotinine metabolism was also found in isolated hepatocytes from PB-induced rats and in cultured mouse hepatocytes grown in a medium supplemented with PB. This was paralleled by an increased formation of cotinine-N-oxide which could be inhibited by 100 μM metyrapone. In contrast, the pulmonary elimination of cotinine was not affected by PB. A dominant role of primary N-oxidation of nicotine compared to C-oxidation was apparent in non-induced rat liver. After PB treatment the rate of nicotine-N′-oxide formation dropped markedly while the cotinine related pathways were increased causing an inversion of the N- to C-oxidation ratio. In the lung, cotinine formation was the preferred metabolic pathway of nicotine already in non-induced organs. The pattern of nicotine metabolites was not altered by PB induction. In conscious PB-induced rats receiving nicotine orally or intravenously, 3′-hydroxycotinine was found as the main urinary metabolite of nicotine while only a small fraction was excreted as cotinine-N-oxide. This discrepancy between the profile of nicotine metabolites in perfused liver and lung and in the urine in vivo indicates that extrahepatic organs other than the lung may be important sites of cotinine metabolism.
    Type of Medium: Electronic Resource
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