1,721,012 research outputs found
New conducting thermoplastic elastomers. Part 2-Physical and chemical physical characterization
No full textTo overcome poor mech. stability and mech. properties of polyaniline, a conducting copolymer was prepd. by grafting polyaniline (Emeraldine Base) or sulfonated polyaniline (SPAN) chains to the backbone of carboxylated segmented polyurethane (PEUA). As evidenced by thermal (DSC) and dynamo-mech. (DMTA) characterization, the introduction of EB or SPAN in the matrix enhances the hard-soft phase segregation effect, because of the strong tendency of the conductive polymer chains to aggregate. The EB and SPAN chains grafted to the polyurethane backbone cause an increase of the Young's modulus and ..
Emergency cannulation for proximal perfusion in descending thoracic aorta procedures
No full textAcute cardiac failure during descending thoracic aorta operations, although rare, may have catastrophic consequences. Under these circumstances, the use of partial veno arterial bypass is advantageous, allowing an assisted perfusion of both proximal and distal circulation districts. Traditionally, the ascending aorta or the aortic arch are the preferred sites of cannulation for proximal arterial reinfusion, but some limitations, such as extensive calcifications or extreme fragility of these segments, may hamper or at least delay this action. Herein, we describe a simple technique for rapid cannulation of proximal aorta in emergency circumstances
Polyurethane/Polyaniline conducting graft copolymer with improved mechanical properties
No full textThe crosslinking effects on the mechanical and electrical properties of a conducting copolymer obtained by grafting polyaniline on a carboxylated polyurethane were investigated. The synthesis and characterization of the polyurethane-polyaniline copolymer (PEUAPAN) were previously reported. The crosslinking process was carried out by reacting ethylenediamine with those polyurethane residual carboxylic groups not involved in the amide binding to the conducting chains. The insoluble material obtained (PEUAPANc) shows a marked elastomeric feature, as evidenced in stress-strain and stress-relaxation measurements. Although the crosslinked graft copolymer conductivity is lower than that of the pristine material, its variation during deformation cycles is reversible because the chain relaxation and viscous flow phenomena are drastically suppressed by the crosslinks
Evolution toward dissection of an intramural hematoma of the ascending aorta
No full textIntramural hematoma of the aorta is a condition increasingly observed in clinical practice. Uncertainty exists whether such lesions represent a different pathology or simply the precursors of classic dissecting aneurysm. The patient was a 76-year-old woman with intramural hematoma of the ascending aorta. Clinical course, progression of the lesion to type A aortic dissection, and surgical treatment are described. Although natural history of intramural hematoma of the ascending aorta is not clearly elucidated, the case presented confirms that the evolution toward intimal flap formation is possible and that we cannot foresee the stabilization of these lesions. We stress that intramural hematoma of the ascending aorta has to be managed as an aortic type A dissection and that aggressive treatment is advisable
Glue containment and anastomosis reinforcement in repair of aortic dissection
No full textIn operations for aortic dissection anastomotic bleeding or secondary anastomosis dehiscence are common problems. The advent of Gelatin-resorcin- formaldehyde-glutaraldehyde (GRF) biologic glue has ameliorated type A dissection operative management. Glue containment is mandatory since detrimental effects of glue migration are described. We herein present a simple technique of anastomosis reinforcement and glue containment that helps in overcoming these complications
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