University of Palermo

About: University of Palermo is a education organization based out in Palermo, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 15621 authors who have published 40250 publications receiving 964384 citations. The organization is also known as: Università degli Studi di Palermo & Universita degli Studi di Palermo.

Influence of intracoronary attenuation on coronary plaque measurements using multislice computed tomography: observations in an ex vivo model of coronary computed tomography angiography.

Abstract: Assessment of attenuation (measured in Hounsfield units, HU) of human coronary plaques was performed using multislice computed tomography (MSCT) in an ex vivo model. In three ex vivo specimens of left coronary arteries in oil, MSCT was performed after intracoronary injection of four solutions of contrast material (400 mgI/ml iomeprol). The four solutions were diluted as follows: 1/infinity, 1/200, 1/80, and 1/20. All scans were performed with the following parameters: slices/collimation 16/0.75 mm, rotation time 375 ms. Each specimen was scored for the presence of atherosclerotic plaques. In each plaque the attenuation was measured in four regions of interest for lumen, plaque (non-calcified thickening of the vessel wall), calcium, and surrounding (oil surrounding the vessel). The results were compared with a one-way analysis of variance test and were correlated with Pearson's test. There were no significant differences in the attenuation of calcium and oil in the four solutions. The mean attenuation in the four solutions for lumen (35+/-10, 91+/-7, 246+/-18, 511+/-89 HU) and plaque (22+/-22, 50+/-26, 107+/-36, 152+/-67 HU) was significantly different between each decreasing dilution (p<0.001). The mean attenuation of lumen and plaque of coronary plaques showed high correlation, while the values were significantly different (r=0.73; p<0.001). Intracoronary attenuation modifies significantly the attenuation of plaques assessed with MSCT.

Design of the friction stir welding tool using the continuum based FEM model

Abstract: In friction stir welding (FSW), the welding tool geometry plays a fundamental role in obtaining desirable microstructures in the weld and the heat-affected zones, and consequently improving strength and fatigue resistance of the joint. In this paper, a FSW process with varying pin geometries (cylindrical and conical) and advancing speeds is numerically modeled, and a thermo-mechanically coupled, rigid-viscoplastic, fully 3D FEM analysis able to predict the process variables as well as the material flow pattern and the grain size in the welded joints is performed. The obtained results allow finding optimal tool geometry and advancing speed for improving nugget integrity of aluminum alloys.

Relationship between structure and CO oxidation activity of ceria-supported gold catalysts.

Abstract: Gold catalysts supported on cerium oxide were prepared by solvated metal atom dispersion (SMAD), by deposition-precipitation (DP), and by coprecipitation (CP) methods and were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The catalytic activity was tested in the CO oxidation reaction. The structural and surface analyses evidenced the presence of a modified ceria phase in the case of the DP sample and the presence of pure ceria and gold metal crystallites in the case of the SMAD and CP samples. The DP sample, after a mild treatment in air at 393 K, exhibited only ionic gold, and it was very active below 273 K. By comparing the activities of the different catalysts, it is suggested that the presence of small gold particles, as obtained by the SMAD technique, is not the main requisite for the achievement of the highest CO conversion. The strong interaction between ionic gold and ceria, by enhancing the ceria surface oxygen reducibility, may determine the particularly high activity.