Studio del comportamento meccanico di smalti porcellanati per substrati metallici

Composite porcelain enamels are inorganic coatings for metallic components based on a special ceramic-vitreous matrix in which specific additives are randomly dispersed. The ceramic-vitreous matrix is made by a mixture of various raw materials and elements and in particular it is based on boron-silicate glass added with metal oxides(1) of titanium, zinc, tin, zirconia, alumina, ecc. These additions are often used to improve and enhance some important performances such as corrosion(2) and wear resistance, mechanical strength, fracture toughness and also aesthetic functions. The coating process, called enamelling, depends on the nature of the surface, but also on the kind of the used porcelain enamel. For metal sheets coatings two industrial processes are actually used: one based on a wet porcelain enamel and another based on a dry-silicone porcelain enamel. During the firing process, that is performed at about 870°C in the case of a steel substrate, the enamel raw material melts and interacts with the metal substrate so enabling the formation of a continuous varying structure. The interface domain between the substrate and the external layer is made of a complex material system where the ceramic vitreous and the metal constituents are mixed. In particular four main regions can be identified, (i) the pure metal region, (ii) the region where the metal constituents are dominant compared with the ceramic vitreous components, (iii) the region where the ceramic vitreous constituents are dominant compared with the metal ones, and the fourth region (iv) composed by the pure ceramic vitreous material. It has also to be noticed the presence of metallic dendrites that hinder the substrate and the external layer passing through the interphase region. Each region of the final composite structure plays a specific role: the metal substrate has mainly the structural function, the interphase region and the embedded dendrites guarantee the adhesion of the external vitreous layer to the substrate and the external vitreous layer is characterized by an high tribological, corrosion and thermal shock resistance. Such material, due to its internal composition, functionalization and architecture can be considered as a functionally graded composite material. The knowledge of the mechanical, tribological and chemical behavior of such composites is not well established and the research is still in progress. In particular the mechanical performances data about the composite coating are not jet established. In the present work the Residual Stresses, the Young modulus and the First Crack Failure of the composite porcelain enamel coating are studied. Due to the differences of the porcelain composite enamel and steel thermal properties the enamelled steel sheets have residual stresses: compressive residual stress acts on the coating and tensile residual stress acts on the steel sheet. The residual stresses estimation has been performed by measuring the curvature of rectangular one-side coated specimens. The Young modulus and the First Crack Failure (FCF) of the coating have been estimated by four point bending tests (3-7) monitored by means of the Acoustic Emission (AE) technique(5,6). In particular the AE information has been used to identify, during the bending tests, the displacement domain over which no coating failure occurs (Free Failure Zone, FFZ). In the FFZ domain, the Young modulus has been estimated according to ASTM D6272-02. The FCF has been calculated as the ratio between the displacement at the first crack of the coating and the coating thickness on the cracked side. The mechanical performances of the tested coated specimens have also been related and discussed to respective microstructure and surface characteristics by double entry charts.

Role of immunosuppressive and biologic therapy in pediatric IBD

We aimed to evaluate the role of anti-TNF-alpha therapy with infliximab and adalimumab in a cohort of pediatric patients followed by our Center from 2002 to 2012. The cohort of patients examined consisted of 40 patients: 34 with Crohn disease (85%), 5 with ulcerative colitis (12.5%), one with chronic pouchitis after IPAA for ulcerative colitis (2.5%). All patients were treated with the anti-TNF-α biologic agents infliximab and adalimumab. Thirty-six received infliximab therapy: 19/36 received only infliximab, 17/36 received infliximab and then adalimumab due to loss of response to infliximab and steroid dependency; 4 patients received only adalimumab (infliximab-naïve). Anti-TNF treatment was started before 18 years of age in 34 patients: 29 received infliximab and 5 started adalimumab during childhood. Medical charts were reviewed and safety and efficacy of anti-TNF-alpha have been determined in this population.

L’instrumentum fittile inscriptum della colonia romana di Mutina e del suo territorio

Il presente lavoro è incentrato sulla raccolta e l’analisi dell’instrumentum fittile inscriptum – in particolare laterizi, dolia, lucerne, ceramica fine da mensa, anfore e tappi d’anfora - rinvenuto a Modena e nel suo territorio. L’attenzione è stata concentrata sul materiale bollato e, per quanto riguarda le anfore, anche sullo studio degli esemplari recanti tituli picti. Si è proceduto ad una raccolta di tutto il materiale edito, a cui si è aggiunto lo studio di un’ingente quantità di reperti provenienti da due recenti scavi suburbani: quello presso il Parco Novi Sad, che si segnala soprattutto per la ricchezza del materiale anforico, e quello di Viale Reiter, ove sono venuti alla luce numerosi scarti di cottura di lucerne a canale recanti le firme di alcuni dei più noti produttori di tali oggetti nel mondo romano. A ciascuna categoria di instrumentum è stato dedicato un capitolo, corredato di tabelle in cui è stato raccolto tutto il materiale considerato; inoltre, per i reperti del Parco Novi Sad e di Viale Reiter, è stato realizzato un catalogo corredato di riproduzioni grafiche e fotografiche. Per quanto concerne le iscrizioni dipinte, un capitolo è stato dedicato a quelle presenti sulle anforette adriatiche da pesce; quanto ai tituli picti su anfore di morfologia betica per il trasporto di salse di pesce è stato effettuato un confronto con esemplari rinvenuti in due scavi inediti a Parma, che presentano significative analogie col materiale modenese. Dall’analisi dell’instrumentum inscriptum di Mutina, pur consapevoli dei limiti insiti in una ricerca incentrata unicamente su tale tipo di materiale, è emersa un’immagine della colonia, tra la tarda età repubblicana ed il I sec. d.C., congruente con quella delineata dalle fonti letterarie, dall’epigrafia lapidaria e dai rinvenimenti archeologici, ossia di una città di notevole importanza e ricchezza.

Ab initio quantum mechanical investigation of structural and chemical-physical properties of selected minerals for minero-petrological, structural ceramic and biomaterial applications

The purpose of this thesis is the atomic-scale simulation of the crystal-chemical and physical (phonon, energetic) properties of some strategically important minerals for structural ceramics, biomedical and petrological applications. These properties affect the thermodynamic stability and rule the mineral-environment interface phenomena, with important economical, (bio)technological, petrological and environmental implications. The minerals of interest belong to the family of phyllosilicates (talc, pyrophyllite and muscovite) and apatite (OHAp), chosen for their importance in industrial and biomedical applications (structural ceramics) and petrophysics. In this thesis work we have applicated quantum mechanics methods, formulas and knowledge to the resolution of mineralogical problems ("Quantum Mineralogy”). The chosen theoretical approach is the Density Functional Theory (DFT), along with periodic boundary conditions to limit the portion of the mineral in analysis to the crystallographic cell and the hybrid functional B3LYP. The crystalline orbitals were simulated by linear combination of Gaussian functions (GTO). The dispersive forces, which are important for the structural determination of phyllosilicates and not properly con-sidered in pure DFT method, have been included by means of a semi-empirical correction. The phonon and the mechanical properties were also calculated. The equation of state, both in athermal conditions and in a wide temperature range, has been obtained by means of variations in the volume of the cell and quasi-harmonic approximation. Some thermo-chemical properties of the minerals (isochoric and isobaric thermal capacity) were calculated, because of their considerable applicative importance. For the first time three-dimensional charts related to these properties at different pressures and temperatures were provided. The hydroxylapatite has been studied from the standpoint of structural and phonon properties for its biotechnological role. In fact, biological apatite represents the inorganic phase of vertebrate hard tissues. Numerous carbonated (hydroxyl)apatite structures were modelled by QM to cover the broadest spectrum of possible biological structural variations to fulfil bioceramics applications.

Evaluation of slope stability under water and seismic load through the Minimum Lithostatic Deviation method

The main objective of this thesis is to obtain a better understanding of the methods to assess the stability of a slope. We have illustrated the principal variants of the Limit Equilibrium (LE) method found in literature, focalizing our attention on the Minimum Lithostatic Deviation (MLD) method, developed by Prof. Tinti and his collaborators (e.g. Tinti and Manucci, 2006, 2008). We had two main goals: the first was to test the MLD method on some real cases. We have selected the case of the Vajont landslide with the objective to reconstruct the conditions that caused the destabilization of Mount Toc, and two sites in the Norwegian margin, where failures has not occurred recently, with the aim to evaluate the present stability state and to assess under which conditions they might be mobilized. The second goal was to study the stability charts by Taylor and by Michalowski, and to use the MLD method to investigate the correctness and adequacy of this engineering tool.