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Lourdes M. Del Rosso and Raffaele Ferri

Abstract

Respiration is controlled by the complex orchestration of central nervous system centers, peripheral chemoreceptors and muscles of respiration and is shaped by complex ontogenetic factors. Genetic defects can interfere with these factors, leading to the development of disorders of central control of breathing. Here, we briefly discuss the most important of these rare genetic syndromes: congenital central hypoventilation syndrome (CCHS), Rett’s syndrome (RTT), Prader-Willi syndrome (PWS) and Joubert syndrome. All these conditions are severe neurodevelopmental pathologies that can also involve other organs and systems and have specific genetic backgrounds that if correctly identified can enable better prognostic counseling of patients and/or caregivers. Treatment of disordered breathing is often necessary to counteract the life-threatening problems typical of CCHS and those that complicate the clinical course of RTT, PWS and Joubert syndrome.

Open access

M. Suśniak, J. Karwan-Baczewska, J. Dutkiewicz, M. Actis Grande and M. Rosso

Abstract

The present work investigates the possibility of using powder metallurgy processing for producing a metal matrix composite. Materials were prepared from AlSi5Cu2 chips with reinforcement of 10, 15, 20 wt. % silicon carbide. Aluminum alloy chips were milled with SiC powder in a high-energy ball mill by 40 hours. Mechanical alloying process lead to obtain an uniform distribution of hard SiC particles in the metallic matrix and refine the grain size. The consolidation of composite powders was performed by vacuum hot pressing at 450°C, under pressure of 600 MPa by 10 min. The results shows that the addition of SiC particles has a substantial influence on the microstructure and mechanical properties of composite powder as well as consolidated material. Hot pressing is an effective consolidation method which leads to obtain dense AlSi5Cu2/SiC composite with homogeneous structure and advanced mechanical properties.

Open access

M. Śusniak, J. Karwan-Baczewska, J. Dutkiewicz, M. Actis Grande and M. Rosso

The paper is focused on the processing of aluminum alloy chips using powder metallurgy. Chips obtained from recycled AlSi5Cu2 alloy were ball milled with the addition of silicon carbide powder with an average size of 2μm. Mechanical alloying process was employed to obtain homogeneous composite powder. The effect of processing time (0 - 40h) on the homogeneity of the system was evaluated, as well as a detailed study of the microstructure of AlSi5Cu2 aluminum chips and SiC particles during MA was carried out. Addition of silicon carbide (10, 20wt%) to recycled aluminium chips and application of MA lead to fragmentation of the homogeneous composite powder down to particle size of about 3μm and spheroidization. The addition of hard SiC particles caused reinforcement and reduced the milling time. Higher content of silicon carbide and longer processing time allowed to obtain AlSi5Cu2/SiC powders with microhardness ∽500HV0,025. The results of MA were investigated with SEM, EDS, LOM, XRD and showed that relatively homogeneous distribution of SiC reinforcements in the matrix as well as grain refinement of aluminum solid solution down to 50nm can be obtained after 40h of processing.