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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 337-343 
    ISSN: 1572-8943
    Keywords: DTA ; DTG ; immobilized cinchonidine ; Pt/K-10 montmorillonite ; TG ; thermal stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The characterization of new cinchonidine doped K-10 montmorillonite supported noble metal catalysts is described. Our aim was the mapping of thermal stability of these new catalytic materials by thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermoanalysis (DTA) methods accompanied by X-ray diffraction (XRD) measurements. The catalysts were prepared by various methods including conventional, microwave and ultrasonic treatments. They were characterized first by X-ray diffraction to verify the stability of montmorillonite crystal structure during preparation. Then, TG and DTG methods were applied to determine their stability under the experimental conditions usually applied. The main changes observed were the loss of water and the decomposition of the organic modifiers in the higher temperature region. The catalyst showed the best performance were prepared and characterized using microwaves and ultrasonic irradiation in order to get more insight to the effect of preparation methods on their stability. As a consequence, the catalysts were found to be stable and regenerable under 450-500 K, however, higher temperatures resulted in the complete destruction of the catalysts.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Clinical and experimental medicine 148 (1968), S. 81-89 
    ISSN: 1591-9528
    Keywords: Cardiac surgery ; Myocardial revascularization ; Coronary flow reversal ; Myocardial infarction ; Veines of the heart ; Herzchirurgie ; Myokard-Revascularisation ; Coronarflowumkehr ; Myokardinfarkt ; Herzvenen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei Hunden wurde der Einfluß der retrograden Perfusion des Descendens anterior-Gebietes auf die Folgen der Ramus descendens-Ligatur untersucht. Aus den Akutversuchen geht hervor, daß im Coronarsystem eine Flowumkehr zu verwirklichen ist und daß eine echte Gewebedurchblutung stattfindet. Im günstigsten Fall (3 von 23 Tieren) kann die Flowumkehr ein Kammerflimmern verhindern. Diese Vorteile sind aber mit nachteiligen Begleiterscheinungen verbunden. Die Coronarvenen halten dem hohen arteriellen Druck nicht immer stand, weswegen Gewebeblutungen entstehen können; die venösen Kollateralen leiten mehr als 80% des in die Venen einströmenden Blutes vom Descendensgebiet ab, und die Gewebedurchströmung ist ungleichmäßig, weswegen Zirkulationsstörungen und Infarktzeichen im EKG auftreten. Das Problem der Coronarflowumkehr sollte daher mit weiteren, auf Langzeitüberleben ausgerichteten Versuchen abgeklärt werden.
    Notes: Summary The influence of retrograde perfusion of the vena cordis magna on the sequelae of ligaturing the anterior descendens coronary artery was investigated in acute canine experiments. The results prove that a real inversion of the coronary circulation with an effective tissue perfusion can be obtained. In some cases (3 out of 23) the inversion of the flow prevents ventricular fibrillation. Besides these favorable results a few disadvantageous effects have been noted. The high arterial pressure in the venous system may cause extravasations. By the way of venous collaterals more than 80 percent of the blood may be shunted away from the area to be perfused. The tissue perfusion may be irregular. Further studies with experiments designed for long term survival are therefore necessary.
    Type of Medium: Electronic Resource
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