Authors:E. Lukács, B. Magyari, L. Tóth, Zs. Petrási, I. Repa, A. Koller and Iván Horváth
There are several experimental models for the in vivo investigation of myocardial infarction (MI) in small (mouse, rat) and large animals (dog, pig, sheep and baboons). The application of large animal models raises ethical concerns, the design of experiments needs longer follow-up times, requiring proper breeding and housing conditions, therefore resulting in higher cost, than in vitro or small animal studies. On the other hand, the relevance of large animal models is very important, since they mostly resemble to human physiological and pathophysiological processes. The first main difference among MI models is the method of induction (open or closed chest, e.g. surgical or catheter based); the second main difference is the presence or absence of reperfusion. The former (i.e. reperfused MI) allows the investigation of reperfusion injury and new catheter based techniques during percutaneous coronary interventions, while the latter (i.e. nonreperfused MI) serves as a traditional coronary occlusion model, to test the effects of new pharmacological agents and biological therapies, as cell therapy. The reperfused and nonreperfused myocardial infarction has different outcomes, regarding left ventricular function, remodelling, subsequent heart failure, aneurysm formation and mortality. Our aim was to review the literature and report our findings regarding experimental MI models, regarding the differences among species, methods, reproducibility and interpretation.
Authors:Ivan M. Berezin, Alexandre A. Petunin, Dimtrij I. Kryuchkov and George L. Kovács
A specific process of manufacturing of vessel shell tabs, namely the method of cold stamping is studied in this paper. Recommendations are proposed to gain the proper technology of manufacturing spherical vessels with a volume above 600 cubic meters with regard to labor saving of tabs stamping on hydraulic press. The necessity of having proper technology of stamping is motivated by the large quantity of manual operations, having a direct influence on the conversion costs of a spherical vessel as a whole. The importance of this research is connected with the necessity of multiple shape control of tabs being manufactured during stamping and time-consuming point-by-point shaping-up. The reduction of material costs is supported by using finite-element simulation. Problems are solved with specific modules of the computer aided engineering-system ABAQUS. The results of some finite-element simulations are described. The analysis of stress-strain state at each step of the application of loads is performed.