Search results for " Materiales"

REUTILIZACIÓN DE RESIDUOS DE PODA DE VID Y DE POSIDONIA OCEANICA EN LAS OBRAS DE BIOINGENIERÍA DEL PAISAJE

La popolazione mondiale è in continua espansione e la crescita demografica ed economica inducono allo sfruttamento progressivo dell’ambiente ed al depauperamento delle risorse naturali (acqua ed energia in particolare), con conseguenti impatti potenzialmente importanti sul cambiamento globale. Si rende, pertanto, necessaria ed urgente una più efficiente gestione delle risorse basata sulla rielaborazione di obiettivi sostenibili di politiche e strategie ambientali e sulla riduzione del consumo delle risorse, promuovendo la transizione da un modello di economia lineare ad uno circolare, costituito da un ciclo continuo di sviluppo positivo che preserva e migliora il capitale naturale, ottimizz…

INSTITUT DE CIÈNCIA DELS MATERIALS

2005

L'Institut de Ciència dels Materials de la Universitat de València treballa per a donar resposta a la demanda de nous materials sorgida en l'entorn empresarial, industrial i tecnològic. Els seus especialistes aborden projectes d'investigació aplicada des de diversos ámbits, per a obtindre estos nous materials i caracteritzar les seues propietats. L'Institut també realitza importants aportacions en el camp d'estudi dels nanomaterials, l'autèntica revolució tecnològica del segle XXI.

Frictional Forces between Strongly Compressed, Nonentangled Polymer Brushes: Molecular Dynamics Simulations and Scaling Theory

2010

By means of molecular dynamics simulations and scaling theory we study the response of opposing polymer brushes to constant shear motion under good solvent conditions. Model systems that contain explicit solvent molecules (Lennard-Jones dimers) are compared to solvent-free systems while varying of the distance between the grafted layers and their molecular parameters, chain length and grafting density. Our study reveals a power-law dependence of macroscopic transport properties on the Weissenberg number, W, beyond linear response. For instance, we find that the kinetic friction constant scales as μ ∼ W0.57 for large values of W. We develop a scaling theory that describes our data and previo…

Comparison of peri-implant soft tissues in submerged versus transmucosal healing: A split mouth prospective immunohistochemical study

2018

Objective The present split-mouth prospective study involves an immunohistochemical evaluation of peri-implant soft tissue healing after the osseointegration period, comparing submerged and transmucosal approaches using two-piece implant systems. The null hypothesis was that both surgical procedures elicit a similar immune response of the peri-implant soft tissues. Design Thirty-one healthy patients were included in this study, in which two implants were placed in the right and left maxillary pre-molar regions. A total of 62 dental implants were analyzed, establishing a control side with 31 submerged implants, and a study side with 31 exposed implants bearing healing abutments. After a thre…

Oxamato/Oxamidato-Based Multifunctional Porous Coordination Polymers

2017

El principal objetivo de esta presente Tesis concierne el diseño y la síntesis de materiales multifuncionales, una línea de investigación de creciente interés dentro del campo de la Química de Materiales. Para llevar a cabo dicho objetivo, hemos aprovechado los avances que ha experimentado la química metalosupramolecular en los últimos años. Concretamente pretendemos hacer uso de los métodos de auto-ensamblaje programado basado en las diferentes preferencias que muestran los iones metálicos en sus entornos de coordinación y en la funcionalización de ligandos orgánicos. Para ello, hemos sintetizado ligandos derivados de grupos oxamato y oxamidato, que actuarán como moléculas de partida para …

Protocolo para la evaluación y elección de materiales curriculares digitales

2016

El uso o no del libro de texto, y si ha de ser en formato impreso o digital, es una decisión importante en el planteamiento pedagógico del docente y, en consecuencia, en las prácticas de aula. En ese sentido, presentar una propuesta de criterios pedagógicos, tecnológicos y económicos para la selección de los materiales didácticos curriculares en formato digital puede ser de gran utilidad a los centros de enseñanza. Dichos criterios sirven de punto de partida en el proceso de reflexión que deberán iniciar para la selección de los materiales. Entendemos que lo primero que han de preguntarse, refiriéndonos a los libros de texto en general, es dónde situarlos en el proceso de enseñanza y aprend…

Heterogeneous nucleation of a droplet pinned at a chemically inhomogeneous substrate: A simulation study of the two-dimensional Ising case

2018

Heterogeneous nucleation is studied by Monte Carlo simulations and phenomenological theory, using the two-dimensional lattice gas model with suitable boundary fields. A chemical inhomogeneity of length b at one boundary favors the liquid phase, while elsewhere the vapor is favored. Switching on the bulk field Hb favoring the liquid, nucleation and growth of the liquid phase starting from the region of the chemical inhomogeneity are analyzed. Three regimes occur: for small fields, Hb bcrit, the critical droplet radius is so large that a critical droplet having the contact angle θc required by Young's equation in the region of the chemical inhomogeneity does not yet "fit" there since the base…

Curvature as a Guiding Field for Patterns in Thin Block Copolymer Films

2018

Experimental data on thin films of cylinder-forming block copolymers (BC)—free-standing BCmembranes as well as supported BC films—strongly suggest that the local orientation of the BC patternsis coupled to the geometry in which the patterns are embedded. We analyze this phenomenon using generalsymmetry considerations and numerical self-consistent field studies of curved BC films in cylindricalgeometry. The stability of the films against curvature-induced dewetting is also analyzed. In goodagreement with experiments, we find that the BC cylinders tend to align along the direction of curvature athigh curvatures. At low curvatures, we identify a transition from perpendicular to parallel alignm…

Diffusivity and free anion concentration of ionic liquid composite polybenzimidazole membranes.

2021

[EN] In this article, PBI composite membranes containing the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMIM-NTf2) at 1, 5, 10, 20 and 50 wt% (named PBI-IL-x) have been prepared by a casting method. The internal morphology of the membranes was analyzed by scanning electron microscopy (SEM), revealing that the incorporation of IL promotes the formation of porous channels. Thermal and mechanical stability was confirmed by thermogravimetric analysis (TGA) and tensile test measurements. The ionic transport through membranes was analysed by means of electrochemical impedance spectroscopy (EIS), showing a dependence on the IL loading, reaching a highest condu…

Enhanced Conductivity of Composite Membranes Based on Sulfonated Poly(Ether Ether Ketone) (SPEEK) with Zeolitic Imidazolate Frameworks (ZIFs)

2018

The zeolitic imidazolate frameworks (ZIFs) ZIF-8, ZIF-67, and a Zn/Co bimetallic mixture (ZMix) were synthesized and used as fillers in the preparation of composite sulfonated poly(ether ether ketone) (SPEEK) membranes. The presence of the ZIFs in the polymeric matrix enhanced proton transport relative to that observed for SPEEK or ZIFs alone. The real and imaginary parts of the complex conductivity were obtained by electrochemical impedance spectroscopy (EIS), and the temperature and frequency dependence of the real part of the conductivity were analyzed. The results at different temperatures show that the direct current (dc) conductivity was three orders of magnitude higher for composite …