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  • Best. von Isoniazid, Oxalyldihydrazid, Hydrochinon, Resorcin, organ. Verbindungen  (1)
  • Erythropoiesis  (1)
  • High pressure phase transition  (1)
  • 1
    ISSN: 1618-2650
    Keywords: Best. von Isoniazid, Oxalyldihydrazid, Hydrochinon, Resorcin, organ. Verbindungen ; coulometrische Titration ; Silber(II)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Conditions are described for the efficient generation of silver(II) and the titration of organic compounds by electrogenerated silver(II). An electrolyte of 0.1 M silver nitrate and 5 M nitric acid at −10°C is used, with a gold generating anode and a current density of 1.5–5 mA/cm2. A potentiometric (platinum-S.C.E. pair) or biamperometric (platinum electrodes, 200 mV) end point detection is used. For potentiometric detection, the platinum electrode is preconditioned with AgO in nitric or by anodization. The compounds isoniazid, oxalyldihydrazide, hydroquinone, and resorcinol were titrated down to sub-milligram quantities with errors of 1–2%.
    Notes: Zusammenfassung Der verwendete Elektrolyt besteht aus 0,1 M Silbernitrat in 5 M Salpetersäure bei −10°C. Die Generatoranode besteht aus Gold (Stromdichte 1,5–5 mA/cm2). Die Bestimmung des Endpunkts erfolgt potentiometrisch (Pt/SKE) oder biamperometrisch (Pt-Elektroden, 200 mV). Für die potentiometrische Bestimmung wird die Indicatorelektrode mit einer Lösung von AgO in Salpetersäure oder durch elektrochemische Anodisierung vorbehandelt. Folgende Substanzen wurden bis herab in den sub-Milligramm-Bereich mit Fehlern von 1–2% titriert: Isoniazid, Oxalyldihydrazid, Hydrochinon, Resorcin.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1439-6327
    Keywords: Altitude ; Hypobaric chamber ; Physical training ; Aerobic metabolism ; Erythropoiesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of training in a hypobaric chamber on aerobic metabolism were studied in five high performance triathletes. During 3 weeks, the subjects modified their usual training schedule (approximately 30 h a week), replacing three sessions of bicycling exercise by three sessions on a cycle ergometer in a hypobaric chamber simulating an altitude of 4,000 m (462 mm Hg). Prior to and after training in the hypobaric chamber the triathletes performed maximal and submaximal exercise in normoxia and hypoxia (462 mm Hg). Respiratory and cardiac parameters were recorded during exercise. Lactacidaemia was measured during maximal exercise. Blood samples were drawn once a week to monitor blood cell parameters and erythropoetin concentrations. Training in the hypobaric chamber had no effect on erythropoiesis, the concentrations of erythropoetin always remaining unchanged, and no effect on the maximal oxygen uptake ( $$\dot V$$ O2max) and maximal aerobic capacity measured in normoxia or hypoxia. Submaximal performance increased by 34% during a submaximal exhausting exercise performed at a simulated altitude of 2,000 m. During a submaximal nonexhausting test, ventilation values tended to decrease for similar exercise intensities after training in hypoxia. The changes in these parameters and the improved performance found for submaximal exercise may have been the result of changes taking place in muscle tissue or the result of training the respiratory muscles.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2021
    Keywords: Key words Germanium dioxide ; High pressure phase transition ; Rietveld refinement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  Germanium dioxide was found to undergo a transition from the tetragonal rutile-type to the orthorhombic CaCl2-type phase above 25 GPa. The detailed structural evolution of both phases at high pressure in a diamond anvil cell has been investigated by Rietveld refinement using angle-dispersive, X-ray powder-diffraction data. The square of the spontaneous strain (a−b)/(a+b) in the orthorhombic phase was found to be a linear function of pressure and no discontinuities in the cell constants and volume were observed, indicating that the transition is second-order and proper ferroelastic. Compression of the GeO6 octahedra was found to be anisotropic, with the apical Ge-O distances decreasing to a greater extent than the equatorial distances and becoming shorter than the latter above 7 GPa. Above this pressure, the GeO6 octahedron exhibits the common type of tetragonal distortion predicted by a simple ionic model and observed for most rutile-type structures such as those of the heavier group-14 dioxides and the metal difluorides. Above the phase transition, the columns of edge-sharing octahedra tilt about their two fold axes parallel to c and the rotation angle reaches 10.2(5)° by 36(1) GPa so as to yield a hexagonal close-packed oxygen sublattice. The compressibility increases at the phase change as is expected for a second-order transition at which an additional compression mechanism becomes available.
    Type of Medium: Electronic Resource
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