Prótesis anular regulable para anuloplastia Mitral

Uno de los factores anatómicos más importantes en la insuficiencia mitral es la dilatación del anillo valvular. Esta dilatación puede ser primitiva, como factor causal o secundaria. Una insuficiencia mitral de cualquier etiología, evoluciona dando lugar a una distensión de la aurícula que ocasiona un aumento de longitud del anillo mitral, en la que también colabora la dilatación ventricular consecutiva a la regurgitación. ..

Aneurismas de aorta torácica: corrección quirúrgica

El tratamiento de los aneurismas de aorta torácica podemos decir que es exclusivamente quirúrgico, salvo algunos casos de aneurisma disecante. En esta comunicación revisamos nuestra experiencia en dicho tema. Materiales y métodos: Comprende 12 casos intervenidos hasta la actualidad la actualidad, 4 mujeres y 8 hombres, de los que una mitad eran de aorta ascendente y la otra de aorta torácica descendente. La etiología de los mismos era: Degeneración quística de la media en 2. Infección en 2. Arteriosclerosis en 1. Valvulopatía aórtica en 1. Traumatismo en 1. Coartación de aorta en 3. Revisaremos los casos agrupados según su localización y etiología

Perpendicular magnetic anisotropy in granular multilayers of COPD alloyed nanoparticles

Co-Pd multilayers obtained by Pd capping of pre-deposited Co nanoparticles on amorphous alumina are systematically studied by means of high-resolution transmission electron microscopy, x-ray diffraction, extended x-ray absorption fine structure, SQUID-based magnetometry, and x-ray magnetic circular dichroism. The films are formed by COPD alloyed nanoparticles self-organized across the layers, with the interspace between the nanoparticles filled by the non-alloyed Pd metal. The nanoparticles show atomic arrangements compatible with short-range chemical order of L10 strucure type. The collective magnetic behavior is that of ferromagnetically coupled particles with perpendicular magnetic anisotropy, irrespective of the amount of deposited Pd. For increasing temperature three magnetic phases are identified: hard ferromagnetic with strong coercive field, soft-ferromagnetic as in an amorphous asperomagnet, and superparamagnetic. Increasing the amount of Pd in the system leads to both magnetic hardness increment and higher transition temperatures. Magnetic total moments of 1.77(4) µB and 0.45(4) µB are found at Co and Pd sites, respectively, where the orbital moment of Co, 0.40(2) µB, is high, while that of Pd is negligible. The effective magnetic anisotropy is the largest in the capping metal series (Pd, Pt, W, Cu, Ag, Au), which is attributed to the interparticle interaction between de nanoparticles, in addition to the intraparticle anisotropy arising from hybridization between the 3d-4d bands associated to the Co and Pd chemical arrangement in a L10 structure type

Perpendicular magnetic anisotropy in Co–Pt granular multilayers

Magnetization hysteresis curves have been measured on Co granular multilayers, (Al₂O₃/Co/Pt)N (N = 1 and 25), with the applied magnetic field parallel and perpendicular to the substrate plane. In all samples perpendicular magnetic anisotropy was observed. For Co particles with average diameter 3 nm, the coercive field at low temperature is μ₀HC = 0.5 T. HC decreases for increasing temperature and disappears at ≈200 K. A soft magnetic component is also present in all samples up to the freezing temperature Tf = 365 K. Co and Pt XMCD measurements at the L2,3 edges were performed, yielding to the orbital mL and spin mS contributions to the total magnetic moment of the system. These results, in addition to XANES ones, indicate the presence of CoxPt₁₋x alloy. Particles conformed of CoPt alloy, embedded in Pt and coupled magnetically by dipolar or RKKY interaction, may explain the phenomenology observed in these systems

Aneurismes dissecants d'aorta ascendent. Tractament quirúrgic

Els aneurismes dissecants d'aorta constitueixen una malaltia molt greu, de mal pronòstic i que acostuma a plantejar problemes diagnòstics i terapèutics importants, especialment en els casos aguts. Al nostre país la publicació dels casos operats és escassa. El pronòstic d'aquesta malaltia, el tractament mèdico-quirúrgic i la tècnica a seguir depenen en gran part de la localització de l'aneurisma i de la intervenció que es faci. En aquesta comunicació revisarem la nostra experiència en aquells casos en què la cirurgia es va circumscriure a l'aorta ascendent, amb intervenció sobre la vàlvula aòrtica o sense, i valorarem els problemes diagnòstics que hem trobat i la nostra conducta actual

Ni K-Edge XANES Studies of Hole Doped Nd2-xSrxNiO4 and Reduced Nd2-xSrxNiOy

In the present work we have analyzed the Ni K-edge XANES of two series of families in order to determine their Ni oxidation state : i) the hole doped Nd2-xSrxNiO4 (0.2+x+0.8) ; and ii) the reduced Nd2-xSrxNiOy (0.2+x+0.5 and 3.5+y+3.79). The Ni K-edge XANES shows an increase of Ni(III) content with the Sr concentration for the hole doped samples. Additionally, the reduced family shows the disappearance of Ni(III), a decrease of Ni(II) with respect to the non-reduced one and an increase of Ni(I)