The multiple direct remelting of composites based on the A359 alloy reinforced with 20% of Al2O3 particles was performed. The results of both gravity casting and squeeze casting were examined in terms of the obtained microstructure and mechanical characteristics. In microstructure examinations, the combinatorial method based on phase quanta theory was used. In mechanical tests, the modified low cycle fatigue method (MLCF) was applied. The effects obtained after both gravity casting and squeeze casting were compared. It was noted that both characteristics were gradually deteriorating up to the tenth remelting. The main cause was the occurrence of shrinkage porosity after the gravity casting. Much better results were obtained applying the squeeze casting process. The results of microstructure examinations and fatigue tests enabled drawing the conclusion that the A359 alloy reinforced with Al2O3 particles can confer a much better fatigue life behavior to the resulting composite than the A359 alloy without the reinforcement. At the same time, comparing these results with the results of the previous own research carried out on the composites based also on the A359 alloy but reinforced in the whole volume with SiC particles, it has been concluded that both types of the composites can be subjected to multiple remelting without any significant deterioration of the structural and mechanical characteristics. The concepts and advantages of using the combinatorial and MLCF methods in materials research were also presented
Lipogranulomas are lesions found in histopathological liver examination in humans and in various animal species, including dogs, especially those with portosystemic shunts. They consist of macrophages and other inflammatory cells, and sometimes they contain iron salts (pigment granuloma). This study aimed at determining the number of granulomas and cellular composition of lipogranulomas in dogs with the congenital extrahepatic portosystemic shunt, and to identify factors associated with their development. 44 archival liver samples from dogs with portosystemic shunt were stained using HE, Perl’s method and – in randomly-selected cases – immunohistochemically against CD56, CD20 and CD3 (DAKO). A reduction in the size of the liver was observed in all dogs during laparotomy, and the diameter of the vessel circumventing the liver was also measured (in 24 dogs). Lipogranulomas were found in 52.3% of samples; iron salts were present in 47.8% of them; 72% of cells in lipogranulomas were macrophages. In lipogranulomas both types of lymphocytes – T and B – were seen. The presence of lipogranulomas in liver samples in dogs was connected with fatty degeneration of hepatocytes and was correlated with the age of animals and with the diameter of the abnormal vessel circumventing the liver. Their formation appears to be triggered by severe ischemia and shortage of nutrient supply.