Stability Analysis of the Mg2Si Phase in AA 6061 Aluminum Alloy

AbstractThe spent MTR fuel elements, manufactured with the aluminum-based alloy AA 6061, are stored under water in interim storage basins. In such conditions the AA 6061 is susceptible to degradation by localized corrosion processes which might be related to the behavior of second-phase particles present in the alloy.According to its electrochemical behavior, the second-phase particles present in AA 6061 can be classified into cathodic or anodic in relation to the aluminum matrix.In order to investigate the stability of the Mg2Si phase, which dissolves in high purity water, immersion and polarization tests were carried out in alkaline solutions. SEM and EDS were used to analyze the second-phase particles after the tests.It was determined that Mg2Si phase particles are stable in solutions of pH 8 to 14, and undergo selective magnesium dissolution from pH 7 to lower values

Analysis of the antibiotic resistance profiles in methicillin-sensitive s. Aureus pathotypes isolated on a commercial rabbit farm in Italy

The breeding of meat rabbits is an important sector in the livestock industry in Italy. The focus of this study was to describe the antibiotic resistance profile distribution among the Methicillin-sensitive Staphylococcus aureus isolated in a rabbit farm. From 400 animals of different ages and three farm workers, 96 randomly selected strains isolated from various anatomical sites and lesions were analysed. According to spa typing and the resistance profiles towards veterinary and human antibiotics, 26 pathotypes were identified. The highest resistance was observed against Tetracyclines (92.3%) and Macrolides (80.8%), while almost all were susceptible to Penicillins, according to the limited use of β-lactams on the farm. In total, 92.3% of pathotypes were multidrug resistant (MDRs). Two MDR pathotypes belonging to the t2802 spa type were isolated from both farmers and rabbits. Age categories harboured significantly different pathotypes (p = 0.019), while no association was found between pathotypes and lesions (p = 0.128) or sampling sites (p = 0.491). The antibiotic resistance was observed to increase with the time spent in the farm environment (age category). The selective pressure exerted by antibiotic use acted by giving advantage to more resistant strains rather than by lowering susceptibility to various drug categories within strains