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  • Electronic Resource  (5)
  • reperfusion  (3)
  • ball milling  (2)
  • 1
    ISSN: 1572-8838
    Keywords: ball milling ; chlorate electrolysis ; electrocatalysis ; hydrogen evolution ; nanocrystalline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodes made from nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2), with y varying from 0 to 1 by step of 0.25, and Ti:Ru:Fe:O (2:1:1:w), with w varying from 0 to 2 by step of 0.5, were prepared and tested as activated cathodes for the hydrogen evolution reaction in typical chlorate electrolysis conditions. These electrodes were subjected to an accelerated aging test, consisting of a succession of cycles of hydrogen discharge (HER) and open-circuit (OCP) conditions. In addition to monitoring the cathodic overpotential value during the aging test, visual inspection and mass loss measurements were performed on the electrodes at the end of the test to assess their stability. In the case of Ti:Ru:Fe (2:1:1), a large increase of the cathodic overpotential value is observed after 20 cycles. Adding O to the formulation causes a remarkable improvement of the long-term stability of the electrodes. As little as [O] = 10 at.% in nanocrystalline Ti:Ru:Fe:O (2:1:1:w) materials is sufficient for the electrode to show absolutely no sign of degradation after 50 cycles of HER/OCP, the longest accelerated test conducted. Adding more O to the formulation of the material does not lead to further stability improvement. A better stability under the conditions of the accelerated aging test can also be observed for nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2) materials with y 〉 0. In that case however, the level of improvement is dependent on the value of y. The best results are obtained for y = 0.75. A hypothesis is proposed to explain the improved stability obtained by lowering the Ti content and/or by adding O. The similarity and difference between both ways of improving the stability of the nanocrystalline Ti:Ru:Fe materials are also discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-879X
    Keywords: supported catalyst ; nanocrystalline alloys ; metastable alloys ; ball milling ; mechanical alloying ; surface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The high energy ball-milling technique has been used to produce metastable Ni(Ru) alloys supported on alumina. This catalyst has potential application for the hydrogenation of the C=O bond. The active species are first formed by mechanical alloying pure Ni and Ru powders. The alumina support is ground independently until no structural transformation occurs. Finally, the supersaturated Ni(Ru) powder is milled with the alumina support to produce highly dispersed individual Ni(Ru) nanocrystals on the surface of Al2O3. This supported catalyst has been characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and thermal desorption spectroscopy.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 91 (1996), S. 50-52 
    ISSN: 1435-1803
    Keywords: Myocardial ischemia ; reperfusion ; myocarial infarction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: In conclusion 1)Despite certain similarities between ischemic preconditioning and myocardial hibernation, these two cardioprotective phenomena are different in nature. 2) Intermittent reperfusion inbetween the preconditioning and the sustained ischemic period is not necessary for infarct size reduction by ischemic preconditioning.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1803
    Keywords: Greggphenomenon ; regionalfunction ; stunnedmyocardium ; myocardialoxygenconsumption ; reperfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The “Gregg phenomenon” implies that myocardial function and oxygen consumption ( $$M\dot VO_2 $$ ) increase when coronary perfusion is enhanced within or above the autoregulatory range. We have recently demonstrated that the “Gregg phenomenon” has no significance for regional myocardial function and $$M\dot VO_2 $$ in anesthetized swine in situ. There is, however, some evidence that the “Gregg phenomenon” may exist within stunned myocardium. To test whether coronary hyperperfusion increases regional myocardial function and $$M\dot VO_2 $$ in stunned myocardium, in six anesthetized swine the left anterior descending coronary artery (LAD) was cannulated and perfused at constant pressure (CAP) using an extracorporal circuit. The coronary vein which parallels the LAD was cannulated to allow measurement of regional $$M\dot VO_2 $$ and regional systolic wall thickening (WT%) of the anterior myocardium was assessed using sonomicrometry. Blood flow (CBF) to the LAD was increased by increasing CAP within the extracorporal circuit or by intracoronary adenosine infusion (150 μg/min). In normal myocardium, increasing CBF from 71.4 ± 19.7 (SD) to 156.7 ± 48.8 ml/min/100 g by increasing CAP from 100 ± 10 to 190 ± 10 mm Hg or increasing CBF from 75.1 ± 29.1 to 189.2 ± 45.8 ml/min/100 g by intracoronary adenosine infusion did not increase WT% (34.3 ± 12.2 % vs 32.1 ± 10.6 % and 32.3 ± 10.7 % vs 30.1 ± 13.2 %, respectively). $$M\dot VO_2 $$ was not changed during enhanced CAP (6.94 ± 1.05 vs 8.10 ± 1.08 ml/min/100 g) and during intracoronary adenosine infusion (6.67 ± 1.45 vs 7.30 ± 2.23 ml/min/100 g). Twenty min of hypoperfusion followed by 30 min of reperfusion depressed WT% by 47 % (p 〈 0.05). However, $$M\dot VO_2 $$ was only decreased by 23 % (NS). In the stunned myocardium, increasing CBF from 62.1 ± 36.4 to 157.1 ± 60.0 ml/min by increasing CAP was not associated with an increase in WT%. $$M\dot VO_2 $$ , however, increased from 5.14 ± 1.07 to 8.88 ± 1.83 ml/min/100 g (p 〈 0.05). Comparable results were achieved when CBF was increased from 60.3 ± 28.7 to 176.9 ± 48.5 ml/min by intracoronary adenosine infusion. WT% was unaffected, while $$M\dot VO_2 $$ increased from 4.69 ± 0.92 to 9.46 ± 3.39 ml/min/100 g (p 〈 0.05). Thus, increasing coronary perfusion within or above the autoregulatory range increases $$M\dot VO_2 $$ in stunned myocardium, but without a simultaneous increase in regional myocardial function.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 90 (1995), S. 294-296 
    ISSN: 1435-1803
    Keywords: Myocardial ischemia ; reperfusion ; inotropic reserve calcium antagonists ; ACE inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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