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Bimetallic Ru-Cu samples supported on SiO 2, Al 2 O 3 and MgO were studied by the temperature-programmed reduction (TPR) technique. Experiments were carried out both on unreduced impregnated salts and after oxidation of already reduced samples. The TPR profiles reveal a simultaneous reduction of ruthenium and copper precursors, even though the Ru and Cu in the monometallic catalysts exhibit reduction peaks which differ by up to 150??C. It is suggested that the two metal salts interact during the stages of preparation and drying, and after reduction form bimetallic aggregates which are not stable and tend to separate. The stability of the bimetallic particles was found to be strongly dependent on the support used, being higher on SiO 2 than on Al 2 O 3 and MgO. It is suggested that the chemical nature of the support determines the different degree of interaction and/or agglomeration of the bimetallic particles. Auf SiO 2, Al 2 O 3 und MgO aufgebrachte bimetallische Ru-Cu-Proben wurden mittels temperaturprogrammierter Reduktion (TPR) untersucht. Experimente wurden sowohl mit unreduzierten, durch Impregnation aufgebrachten Salzen als auch mit nach vorangegangener Reduktion reoxydierten Proben ausgef??hrt. Die TPR-Profile lassen eine gleichzeitige Reduktion der Ruthenium- und Kupfervorstufen erkennen, obwohl Ru und Cu in monometallischen Katalysatoren Reduktionspeaks zeigen, die um bis zu 150??C voneinander entfernt liegen. Es wird angenommen, da?? die zwei Metallsalze w??hrend des Darstellungs- und Trocknungsstadiums miteinander in Wechselwirkung treten und nach der Reduktion nicht stabile, zum Zerfall tendierende bimetallische Aggregate bilden. Die Stabilit??t der bimetallischen Partikel ist stark vom Tr??ger abh??ngig, sie ist an SiO 2 h??her als an Al 2 O 3 und MgO. Es wird angenommen, da?? die chemische Natur des Tr??gers den Grad der Wechselwirkung und/oder Agglomeration der bimetallischen Partikel bestimmt.??????????????????????????????????????-???????????

Restoration of blood flow after an ischaemic event generates the formation of oxygen radicals which could augment brain damage. The authors studied the effects of different doses (50, 100, 200 mg/kg/i.p.) of a new antioxidant, IRFI-016, [2(2,3-dihydro-5-acetoxy-4,6,7-trimethylbenzofuranyl) acetic acid] on brain damage in the Mongolian gerbil induced by 5 min of bilateral carotid occlusion (BCO) followed by reperfusion. Post-ischaemic brain malondialdehyde (MDA) levels and locomotor activity at different times and delayed neuronal death of hippocampal CA1 area on the fourth day after occlusion were evaluated. During reperfusion, after BCO, enhancement of brain MDA occurs (37.5%, 62.5% and 100% at 15, 30 and 60 min of reperfusion, respectively). Brain MDA postischaemic increases were reduced at 15 min of reperfusion to 15.4% and 44.4% by IRFI-016, 100 and 200 mg/kg, respectively. After 30 min of reperfusion brain MDA was reduced to 31.25% and 53.13% by IRFI-016 100 and 200 mg/kg, respectively. Hyperactivity and delayed neuronal death of CA1 were significantly reduced in postischaemic gerbils treated with the highest doses of IRFI-016. Results indicate that pretreatment with the antioxidant IRFI-016 improves in a dose-dependent manner brain damage induced by ischaemia and reperfusion in the gerbil