Search results for "materiales"
showing 10 items of 204 documents
Shear-aligned block copolymer monolayers as seeds to control the orientational order in cylinder-forming block copolymer thin films
2016
We study the dynamics of coarsening of a cylinder-forming block copolymer thin film deposited on a prepatterned substrate made of a well-ordered block copolymer monolayer. During thermal annealing the shear-aligned bottom layer drives extinction of the disclinations and promotes a strong orientational correlation, disturbed only by dislocations and undulations along the cylinders of the minority phase. The thin film bilayer system remains stable during annealing, in agreement with self-consistent field theory results that indicate that although the thickness of a stack of two monolayers is not at the optimum thickness condition, it is very close to equilibrium. Phase field simulations indic…
Densely packed semiflexible macromolecules in a rigid spherical capsule
2018
The ordering of semiflexible polymers with persistence length lp and contour length L confined in a sphere of radius R is studied by molecular dynamics simulations of a coarse-grained model. Monomer densities are chosen where the corresponding bulk lyotropic solution or melt is a well-ordered nematic, and purely repulsive walls of the rigid confining sphere are considered. It is found that polymers close to the walls are bent according to the curvature of the confining spheres with all their monomers in a few layers parallel to the sphere surface, whereas the remaining macromolecules closer to the sphere center have one chain end and their center of mass far from the surface. The latter cha…
Microstructure and mechanical properties of plasma spraying coatings from YSZ feedstocks comprising nano-and submicron-sized particles
2015
Atmospheric plasma spraying (APS) is an attractive technique to obtain nanostructured coatings due to its versatility, simplicity and relatively low cost. However, nanoparticles cannot be fed into the plasma using conventional feeding systems, due to their low mass and poor flowability, and must be adequately reconstituted into sprayable micrometric agglomerates. In this work, nanostructured and submicron/nanostiuctured powders of yttria-stabilised zirconia (YSZ) were deposited using APS, with a view to obtaining high-performance thermal bather coatings (IBC). All powders were reconstituted by spray-drying from different solid loading suspensions, followed by a thermal treatment of the spra…
Polylactide-based self-reinforced composites biodegradation: Individual and combined influence of temperature, water and compost
2018
[EN] Self-reinforced polymer composites (SRCs) are proposed as a suitable alternative for composite development, based in the combination of a polymeric matrix and a polymeric fibre made of the same polymer. SRCs based in polylactide (PLA) could be fully biodegradable and their valorisation routes could presumably be assimilated to those for neat PEA. In this sense, the aim of this study was to develop new self-reinforced PLA-based composites and ascertain their biodegradability. For this purpose, PLA-based SRCs were obtained through a thermo-compression procedure and their biodegradability corroborated under standard conditions (ISO 20200). Moreover, a deep study of the effect of the diffe…
Comparative characterization of a novel cad-cam polymer-infiltrated-ceramic-network.
2015
Background The field of dental ceramics for CAD-CAM is enriched with a new innovative material composition having a porous three-dimensional structure of feldspathic ceramic infiltrated with acrylic resins.The aim of this study is to determine the mechanical properties of Polymer-Infiltrated-Ceramic-Network (PICN) and compare its performance with other ceramics and a nano-ceramic resin available for CAD-CAM systems. Material and Methods In this study a total of five different materials for CAD-CAM were investigated. A polymer-infiltrated ceramic (Vita Enamic), a nano-ceramic resin (Lava Ultimate), a feldspathic ceramic (Mark II), a lithium disilicate ceramic (IPS-e max CAD) and finally a Le…
Cobalt ferrite nanoparticles under high pressure
2015
We report by the first time a high pressure X-ray diffraction and Raman spectroscopy study of cobalt ferrite (CoFe2O4) nanoparticles carried out at room temperature up to 17 GPa. In contrast with previous studies of nanoparticles, which proposed the transition pressure to be reduced from 20–27 GPa to 7.5–12.5 GPa (depending on particle size), we found that cobalt ferrite nanoparticles remain in the spinel structure up to the highest pressure covered by our experiments. In addition, we report the pressure dependence of the unit-cell parameter and Raman modes of the studied sample. We found that under quasi-hydrostatic conditions, the bulk modulus of the nanoparticles (B0 = 204 GPa) is consid…
Impact of hydrothermal ageing on the thermal stability, morphology and viscoelastic performance of PLA/sisal biocomposites
2016
The influence of the combined exposure to water and temperature on the behaviour of polylactide/sisal biocomposites coupled with maleic acid anhydride was assessed through accelerated hydrothermal ageing. The biocomposites were immersed in water at temperatures from 65 to 85 °C, between the glass transition and cold crystallisation of the PLA matrix. The results showed that the most influent factor for water absorption was the percentage of fibres, followed by the presence of coupling agent, whereas the effect of the temperature was not significant. Deep assessment was devoted to biocomposites subjected to hydrothermal ageing at 85 °C, since it represents the extreme degrading condition. Th…
Bioactivity of bioceramic materials used in the dentin-pulp complex therapy : a systematic review
2019
Este es el artículo que se ha publicado de forma definitiva en: https://www.mdpi.com/1996-1944/12/7/1015 Dentistry-applied bioceramic materials are ceramic materials that are categorized asbioinert, bioactive and biodegradable. They share a common characteristic of being specificallydesigned to fulfil their function; they are able to act as root canal sealers, cements, root repair or fillingmaterials. Bioactivity is only attributed to those materials which are capable of inducing a desiredtissue response from the host. The aim of this study is to present a systematic review of availableliterature investigating bioactivity of dentistry-applied bioceramic materials towards dental pulp stemcel…
Les biens publics de la Méditerrannée
2007
Converencia de José Vidal-Beneyto en la "IX Asamblea de la Comunidad de las Universidades del Mediterráneo (CUM)" y con motivo también de la entrega del Premio del Mediterráneo 2003 al propio autor. Bari, Italia, 20-22 de noviembre de 2003. El texto no fue publicado hasta el año 2007.
Explotación de recursos geológicos en la periferia valenciana: Camp de Túria y Hoya de Buñol-Chiva
1990
En este artículo se pretende estudiar la influencia que ejerce el área metropolitana de Valencia (AMV) sobre el espacio contiguo occidental (las comarcas del Camp de Turia y la Hoya de Buñol-Chiva) en un aspecto determinado: la explotación de los recursos geológicos de este espacio. Para ello el estudio se centrara en primer lugar en las condiciones litológicas del área en cuestión. Seguidamente, definiremos la evolución de este sector desde finales del siglo XVIII. Y, finalmente, estudiaremos la situación actual. Para ello nos basaremos en la localización de los yacimientos y su evolución, así como en la titularidad de las distintas explotaciones y en los principales destinos del volumen e…