María Roxana Morales

Catalytic Combustion of n-Hexane Over Alumina Supported Mn–Cu–Ce Catalysts

Supported MnCuCe and MnCe mixed oxides catalysts were prepared and evaluated in n-hexane combustion reaction. They presented an excellent catalytic activity in total combustion of n-hexane. Catalysts were characterized by means of XRD, XPS, SBET and TPR techniques. The addition of Cu did not enhance the catalytic activity of MnOx/Al2O3 due to the formation of the complete Mn2CuO4 spinel. The presence of cerium favored the formation of manganese oxide species with low crystallinity, with high oxygen mobility and high oxygen vacancies. A higher content of Ce was necessary to obtain catalysts with higher oxidation state of Mn and Ce species.Graphical Abstract

Effects of exercise on myocardial catecholamine content and ischemic injury in dogs with gradual coronary occlusion

The effects of exercise on catecholamine content and the extent of myocardial damage in dogs with Ameroid constrictor occlusion of the left circumflex coronary artery were determined. Tissue samples from both the anterior and posterior walls of the left ventricle were obtained for determination of catecholamine content, and the rest of the ventricles were processed for histologic examination. When subjected to treadmill exercise for 40 days after surgery, obstructed animals performed significantly less exercise than sham-operated animals and showed significantly higher percentages of ischemia and necrosis in the left ventricle than sedentary, obstructed, sham-operated, or control dogs. Levels of norepinephrine and epinephrine in the posterior wall of the left ventricle were significantly lower than in the other groups. Our data show that exercise in this well-known model of chronic coronary artery stenosis produced deleterious effects on the myocardium and suggest a marked heterogeneity of catecholamine stores in the myocardium that may have important functional and electrophysiologic consequences.