Nuovi contributi alla valutazione del rischio d'inquinamento degli acquiferi nella fascia costiera dell regione carsica nebroidea (Sicilia nord-orientale)

Decomposition of nitrous oxide upon nickel oxide-magnesium oxide solid solutions

The decomposition of N 2 O has been studied over MgO catalysts, doped with NiO and NiO + Li 2 O from 1 to 10% (atomic). For pure MgO, activity is low, but is enhanced by addition of Ni 2+ ions. The apparent activation energy is reduced from 35 kcal/mole for pure MgO, to about 18 kcal/mole. Oxygen acts as a poison, and it is chemisorbed on the catalyst. The presence of lithium greatly increases the apparent activation energy. The results are interpreted in terms of oxygen chemisorption and of its influence on the course of the reaction.

Le forme della conoscenza: test diagnostici preliminari e verifiche a restauro in corso d’opera / Forms of Knowledge: Preliminary diagnostic testing and investigations during the restoration process

Il restauro persegue l’obiettivo di preservare il carattere autentico dell’architettura storica e le sue stratificazioni, rendere distinguibili le aggiunte e proporre un uso compatibile. Questa posizione culturale ha sostenuto l’intervento condotto sui resti dell’ex chiesa Madre a Santa Margherita di Belice in Sicilia, distrutta da un terremoto nel 1968, che oggi ospita il Museo della Memoria. Esclusa l’iniziale proposta di ripristino delle parti crollate, il progetto di restauro è stato indirizzato verso la conservazione critica del frammento autentico, la reintegrazione della fabbrica lacunosa e la ridefinizione dell’involucro architettonico con componenti strutturali dal carattere potenz…

A mathematical approach to model diffusion properties of sedimentary rocks relevant to Sicily cultural heritage

Cultural heritage vestiges represent complex physical systems, able to interact with the environment through continuous exchanges of heat and fluids (water, air). In this wide context, particular relevance is assumed by transport phenomena and diffusion of pollutant, vehiculated inside the considered structure by water itself. Interaction mechanisms can be considered at various observation scales, depending on the material provenance and on its geometry and location. Involved materials are commonly constituted by porous rocks - more or less altered - belonging to geological sedimentary formations, as limestone, calcarenite and travertine. Their appreciable porosity affects significantly liq…