Search results for "Homogeneous"
showing 10 items of 718 documents
Poly-left-lactic acid tubular scaffolds via diffusion induced phase separation: Control of morphology
2013
n this work, tubular poly-left-lactic acid scaffolds for vascular tissue engineering applications were produced by an innovative two-step method. The scaffolds were obtained by performing a dip-coating around a nylon fiber, followed by a diffusion induced phase separation process. Morphological analysis revealed that the internal lumen of the as-obtained scaffold is equal to the diameter of the fiber utilized; the internal surface is homogeneous with micropores 1–2 μm large. Moreover, a porous open structure was detected across the thickness of the walls of the scaffold. An accurate analysis of the preparation process revealed that it is possible to tune up the morphology of the scaffold (w…
Tubular scaffold for vascular tissue engineering application
2010
A critical obstacle in tissue engineering is the inability to maintain large masses of living cells upon transfer from the in vitro culture conditions into the host in vivo. Capillaries, and the vascular system, are required to supply essential nutrients, including oxygen, remove waste products and provide a biochemical communication “highway”. Another goal in this research field is the possibility to tune the biodegradability of the scaffold. After implantation, the scaffold has to be gradually replaced by cells and extra cellular matrix and it is crucial that this replacement takes place with an appropriate dynamics. A premature degradation, in fact, could lead to a collapse of the struct…
4D Clifford algebra based on fixed-size representation
2008
Geometric algebra (also known as Clifford algebra) is a powerful mathematical tool that offers a natural and direct way to model geometric objects and their transformations. It is gaining growing attention in different research fields as physics, robotics, CAD/CAM and computer graphics. In particular, 4D geometric algebra implements homogeneous coordinates, which are used to model 3D scenery in most computer graphics applications. The research work on Clifford algebra is actually aimed at finding efficient implementations of the algebra. This paper wants to give a contribution to this research effort by proposing a direct hardware support for geometric algebra operators. The paper introduce…
Ancora sulle "esplosive palatali" nelle inchieste dell'Atlante Linguistico del Mediterraneo (ALM): i punti albanesi
2021
Tra i «Problemi redazionali» emersi in fase di controllo e organizzazione dei materiali giunti dalla campagna di rilevamenti dell’Atlante Linguistico del Mediterraneo (ALM), Berruto (1971-1973) rileva la proliferazione e l’eterogeneità di alcune scelte grafemiche operate da diversi raccoglitori che, impegnati in una trascrizione più o meno puntuale delle risposte ottenute, avevano interpretato e risolto variamente alcune delle indicazioni previste nel sistema di trascrizione fonetica che accompagnava il Questionario. Particolarmente complesso era emerso il quadro relativo alla trascrizione di alcune consonanti del settore “palatale”, per le quali i grafemi (e i foni a essi corrispondenti) p…
Rappresentazioni e territorio nelle dinamiche del turismo: il caso della Lonely Planet Sicily
2018
L’attuale dibattito sul riordino territoriale del Paese rende nuovamente centrale il concetto di territorio che, da sempre, in una prospettiva geografica pone problemi definitori. Esso può essere, infatti, oggetto di produzioni simboliche e (ri)semantizzazioni in grado di ridefinirlo e di creare specifiche modalità di interazione. A questo proposito, il presente lavoro intende proporre una riflessione su alcune dinamiche di produzione e riproduzione simbolica che interessano il concetto di territorio nel turismo, ambito in cui si può osservare una relazione diretta tra rappresentazione del territorio (intesa anche come narrazione) e possibilità d’azione. In particolare, attraverso il caso s…
Positive and nodal solutions for nonlinear nonhomogeneous parametric neumann problems
2020
We consider a parametric Neumann problem driven by a nonlinear nonhomogeneous differential operator plus an indefinite potential term. The reaction term is superlinear but does not satisfy the Ambrosetti-Rabinowitz condition. First we prove a bifurcation-type result describing in a precise way the dependence of the set of positive solutions on the parameter λ > 0. We also show the existence of a smallest positive solution. Similar results hold for the negative solutions and in this case we have a biggest negative solution. Finally using the extremal constant sign solutions we produce a smooth nodal solution.
Organic Monolayers by B(C6F5)3-Catalyzed Siloxanation of Oxidized Silicon Surfaces
2017
Inspired by the homogeneous catalyst tris(pentafluorophenyl) borane [B(C6F5)3], which acts as a promotor of Si-H bond activation, we developed and studied a method of modifying silicon oxide surfaces using hydrosilanes with B(C6F5)3 as the catalyst. This dedihydrosiloxanation reaction yields complete surface coverage within 10 min at room temperature. Organic monolayers derived from hydrosilanes with varying carbon chain lengths (C8-C18) were prepared on oxidized Si(111) surfaces, and the thermal and hydrolytic stabilities of the obtained monolayers were investigated in acidic (pH 3) medium, basic (pH 11) medium, phosphate-buffered saline (PBS), and deionized water (neutral conditions) for …
Classifying Regions for European Development Funding
2010
Structural and cohesion funds play a prominent role in European Union regional policy, which aims to reduce gaps in development between regions and disparities in well-being between European citizens. The regions and areas eligible for funding — 308,000 million during the 2007—13 period — are chosen according to regional GDP per inhabitant as the variable of reference. Despite the great importance of this indicator, the complex socioeconomic reality of regions cannot be fully explained by means of a single variable. Hence, using the large number of variables on economic, political, cultural and demographic characteristics available at regional level, this article groups European regions in…
Nuclear Magnetic Resonance for Cultural Heritage
2007
Abstract Nuclear magnetic resonance (NMR) portable devices are now being used for nondestructive in situ analysis of water content, pore space structure and protective treatment performance in porous media in the field of cultural heritage. It is a standard procedure to invert T 1 and T 2 relaxation data of fully water-saturated samples to get “pore size” distributions, but the use of T 2 requires great caution. It is well known that dephasing effects due to water molecule diffusion in a magnetic field gradient can affect transverse relaxation data, even if the smallest experimentally available half echo time τ is used in Carr–Purcell–Meiboom–Gill experiments. When a portable single-sided N…
Links and Bifurcations in Nonsingular Morse–Smale Systems
1997
Wada's theorem classifies the set of periodic orbits in NMS systems on S3 as links, that can be written in terms of six operations. This characterization allows us to study the topological restrictions that links require to suffer a given codimension one bifurcation. Moreover, these results are reproduced in the case of NMS systems with rotational symmetries, introducing new geometrical tools.