Search results for "materiales"

Optical pulling and pushing forces in bilayer PT-symmetric structures

2018

Photons are massless, yet can exert force on small particles. This $r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}d\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}n$ $p\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e$, though discussed by Kepler, still needs investigation for modern systems. This study reveals that the optical force exerted on a parity-time-symmetric bilayer with balanced gain and loss can be $a\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}y\phantom{\rule{0}{0…

On the half-metallicity of Co2FeSi Heusler alloy: Point-contact Andreev reflection spectroscopy andab initiostudy

2013

Co2FeSi, a Heusler alloy with the highest magnetic moment per unit cell and the highest Curie temperature, has largely been described theoretically as a half-metal. This conclusion, however, disagrees with point contact Andreev reflection (PCAR) spectroscopy measurements, which give much lower values of spin polarization, P. Here, we present the spin polarization measurements of Co2FeSi by the PCAR technique, along with a thorough computational exploration, within the DFT and a GGA+U approach, of the Coulomb exchange U parameters for Co and Fe atoms, taking into account spin-orbit coupling. We find that the orbital contribution (mo) to the total magnetic moment (mT) is significant, since it…

Double pion photoproduction in nuclei

1995

The inclusive A(gamma,pi+ pi-)X reaction is studied theoretically. A sizeable enhancement of the cross section is found, in comparison with the scaling of the deuteron cross section (sigma_deuteron * A/2). This enhancement is due to the modifications in the nuclear medium of the gamma N ----> pi pi N amplitude and the pion dispersion relation. The enhancement is found to be bigger than the one already observed in the (pi,pi pi) reaction in nuclei.

Quark effects, meson-exchange currents and background in the d(e,e'p)delta reaction

1994

[EN] We have studied in detail the cross section for the d(e, e'p)Delta reaction leading to the emission of a fast nucleon and a Delta at rest, which has been advocated as a tool to investigate quark effects in nuclei. We find that ordinary meson-exchange currents mechanisms dominate the quark-exchange effects in the region of excitation of the Delta and could be competitive at higher energies. Furthermore, at these higher energies, the small cross sections for the quark signal, together with the presence of a background about one order of magnitude bigger than the quark signal, make in any case the extraction of information about quark-exchange currents effects extraordinarily difficult.

Más allá del acero: Otros metales y sus usos en la arquitectura del siglo XXI

2009

[ES] El protagonismo que ostentan los metales como compuestos básicos para el desenvolvimiento cotidiano de la vida humana resulta evidente e irrefutable. Del mismo modo que una mayoría de las actividades diarias que realizamos serían imposibles sin el apoyo que nos brinda el metal, un amplio porcentaje de la arquitectura de la última centuria también hace descansar sus fundamentos en la solidez de una estructura metálica. Más allá del hierro como predecesor y del acero como digno sucesor, la constructiva recurre asimismo con asiduidad a otros metales para conformar con ellos la imagen final del edificio, redundando en ésta componentes tanto técnicos como expresivos de los que son responsab…

Complement proteins regulating macrophage polarisation on biomaterials

2019

[EN] One of the events occurring when a biomaterial is implanted in an host is the protein deposition onto its surface, which might regulate cell responses. When a biomaterial displays a compromised biocompatibility, distinct complement pathways can be activated to produce a foreign body reaction. In this article, we have designed different types of biomaterial surfaces to study the inflammation process. Here, we used different concentrations of (3-glycidoxypropyl)-trimethoxysilane (GPTMS), an organically-modified alkoxysilane as a precursor for the synthesis of various types of sol-gel materials functionalizing coatings for titanium implants to regulate biological responses. Our results sh…

Phosphoric Acid Doped Polybenzimidazole (PBI)/Zeolitic Imidazolate Framework Composite Membranes with Significantly Enhanced Proton Conductivity unde…

2018

The preparation and characterization of composite polybenzimidazole (PBI) membranes containing zeolitic imidazolate framework 8 (ZIF-8) and zeolitic imidazolate framework 67 (ZIF-67) is reported. The phosphoric acid doped composite membranes display proton conductivity values that increase with increasing temperatures, maintaining their conductivity under anhydrous conditions. The addition of ZIF to the polymeric matrix enhances proton transport relative to the values observed for PBI and ZIFs alone. For example, the proton conductivity of PBI@ZIF-8 reaches 3.1 10&minus

Crosslinked Sulfonated Poly(vinyl alcohol)/Graphene Oxide Electrospun Nanofibers as Polyelectrolytes

2019

[EN] Taking advantage of the high functionalization capacity of poly(vinyl alcohol) (PVA), bead-free homogeneous nanofibrous mats were produced. The addition of functional groups by means of grafting strategies such as the sulfonation and the addition of nanoparticles such as graphene oxide (GO) were considered to bring new features to PVA. Two series of sulfonated and nonsulfonated composite nanofibers, with different compositions of GO, were prepared by electrospinning. The use of sulfosuccinic acid (SSA) allowed crosslinked and functionalized mats with controlled size and morphology to be obtained. The functionalization of the main chain of the PVA and the determination of the optimum co…

ROSÓN, María. "Género, memoria y cultura visual en el primer franquismo (materiales cotidianos, más allá del arte)"

2016

Active properties of edible marine polysaccharide-based coatings containing Larrea nitida polyphenols enriched extract.

2020

The aim of this work was to develop active edible coatings based on marine polysaccharide matrices and polyphenols-enriched native plant extracts from arid and semiarid regions of Argentina. Initially, five plant extracts were characterized in terms of antioxidant, antibacterial and antiviral activity and the one with better biological properties and no toxicity or genotoxicity, Larrea nitida (Ln) extract, was incorporated into agar, alginate or agar/alginate matrices. The Ln extract-containing films were characterized in terms of physicochemical and polyphenols release performance in food simulants. The incorporation of Ln extract provided darker films, with a more saturated orange-brownis…