Hydrogenated graphene nanoribbons for spintronics

We show how hydrogenation of graphene nanoribbons at small concentrations can open venues toward carbon-based spintronics applications regardless of any specific edge termination or passivation of the nanoribbons. Density-functional theory calculations show that an adsorbed H atom induces a spin density on the surrounding π orbitals whose symmetry and degree of localization depends on the distance to the edges of the nanoribbon. As expected for graphene-based systems, these induced magnetic moments interact ferromagnetically or antiferromagnetically depending on the relative adsorption graphene sublattice, but the magnitude of the interactions are found to strongly vary with the position of the H atoms relative to the edges. We also calculate, with the help of the Hubbard model, the transport properties of hydrogenated armchair semiconducting graphene nanoribbons in the diluted regime and show how the exchange coupling between H atoms can be exploited in the design of novel magnetoresistive devices.

Structure, gas-barrier properties and overall migration of poly(lactic acid) films coated with hydrogenated amorphous carbon layers

Hydrogenated amorphous carbon (a-C:H) films were grown on a poly(lactic acid) (PLA) substrate by means of a radiofrequency plasma-enhanced chemical vapour deposition (rf-PECVD) technique with different deposition times (5, 20 and 40 min). The main goal of this treatment was to increase the barrier properties of PLA, maintaining its original transparency and colour as well as controlling interactions with food simulants for packaging applications. Morphological, chemical, and mechanical properties of PLA/a-C:H systems were evaluated while permeability and overall migration tests were performed in order to determine the effect of the plasma treatment on the gas-barrier properties of PLA films and their application in food packaging. Morphological results suggested a good adhesion of the deposited layers onto the polymer surface and the samples treated for 5 and 20 min only slightly darkened the PLA film. X-ray photoelectron spectroscopy revealed that the structural properties of the carbon layer deposited onto the PLA film depend on the exposure time. PLA/a-C:H system treated for 5 min showed the highest barrier properties, while none of the studied samples exceeded the migration limit established by the current legislation, suggesting the suitability of these materials in packaging applications.

«Soy vampiro, pero también una chica»: vampiros regenerados en True Blood

En la literatura y el cine góticos clásicos, el vampiro se concebía como un monstruo al que cabía eliminar. Sin embargo, en los últimos cuarenta años, novelas, películas y series revelan una voluntad de asimilarlo a la sociedad humana, un proceso conocido como domesticación o regeneración. Como metáfora de la diferencia sexual, racial, de género o de clase, tal asimilación representa, de acuerdo con los postulados de Foucault, una operación que lleva a cabo el poder para someterlas, integrándolas en el orden social y cultural establecido. La serie estadounidense True Blood (2008-2014) refleja a la perfección este proceso dual de regeneración que implica, a su vez, sometimiento. Relacionado con los supuestos de la corrección política, el nuevo monstruo ya no simboliza al «perverso» sino al «diferente» que se debe proteger y aceptar en el seno de la sociedad, pese al riesgo de cohesión social y amenaza para la familia que comporta.