Le pietre artificiali ed i cementi artistici utilizzati durante la stagione Liberty rappresentano tutt’oggi un patrimonio artistico non ancora sufficientemente studiato. In seguito ad una ricerca bibliografica su testi e riviste dei primi anni del Novecento, è stata eseguita una ricognizione del patrimonio architettonico emiliano-romagnolo, al fine di valutarne i materiali e le tipologie di degrado più diffuse. Le città e le zone oggetto di studio sono state: Bologna, Ferrara, Modena e provincia, Reggio Emilia, Parma, Firenze, la Romagna e le Marche settentrionali. Tra gli edifici individuati sono state analizzate le decorazioni e gli intonaci di tre edifici ritenuti particolarmente significativi: il villino Pennazzi (noto anche come Villa Gina) a Borgo Panigale (Bologna), villa Verde a Bologna e l’ex-albergo Dorando Pietri a Carpi. Da tali edifici sono stati selezionati campioni rappresentativi delle diverse tipologie di decorazioni in pietra artificiale e successivamente sono stati caratterizzati in laboratorio tramite diffrattometria a raggi x (XRD), termogravimetria (TGA), microscopio ottico in sezioni lucide, microscopio elettronico a scansione (SEM) e porosimetria ad intrusione di mercurio (MIP). In particolare per Villa Verde sono state formulate e caratterizzate diverse tipologie di malte variando il tipo di legante ed il rapporto acqua/cemento, al fine di garantire la compatibilità fisico-meccanica con il supporto negli interventi di risarcimento delle lacune previsti nel restauro. L’attività sperimentale svolta ha permesso di mettere a punto un vero e proprio protocollo diagnostico per il restauro di questo tipo di decorazioni che potrà essere utilizzato sia nei casi di studio analizzati che per ogni futuro intervento. / Artificial stones used during Liberty season are still today an artistic patrimony not sufficiently studied yet. After a bibliographical research on books and journals of the first years of the XX century, a recognition of the architectural patrimony of Emilia-Romagna was performed, with the purpose of evaluating the most diffused typologies of decay. Cities and regions that were taken into account are: Bologna, Ferrara, Modena, Reggio Emilia, Parma, Florence, Romagna region and the northern Marche region. Among the studied buildings, the decorations and the plasters of three buildings, considered as more relevant, were analyzed: villa Pennazzi (known also as Villa Gina) in Borgo Panigale suburb (Bologna), Villa Verde in Bologna and the ex-hotel Dorando Pietri in Carpi. From such buildings, representative samples of the different typologies of decorations have been selected and characterized in laboratory using: X-Ray Diffraction (XRD), Thermogravimetry (TG), Optical Microscope in polished section, Scanning Electron Microscope (SEM) and Mercury Intrusion Porosimetry (MIP). In particular, for Villa Verde different typologies of repair mortars were formulated, varying the type of binder and water/cement ratio, with the purpose of guaranteeing the physical-mechanical compatibility with the support. The performed activity allowed to set a real diagnostic protocol for the restoration of this type of decorations, which can be used not only in the analyzed cases of study but also for every future restoration.

This PhD Thesis is composed of three chapters, each discussing a specific type of risk that banks face. The first chapter talks about Systemic Risk and how banks get exposed to it through the Interbank Funding Market. Exposures in the said market have Systemic Risk implications because the market creates linkages, where the failure of one party can affect the others in the market. By showing that CDS Spreads, as bank risk indicators, are positively related to their Net Interbank Funding Market Exposures, this chapter establishes the above Systemic Risk Implications of Interbank Funding. Meanwhile, the second chapter discusses how banks may handle Illiquidity Risk, defined as the possibility of having sudden funding needs. Illiquidity Risk is embodied in this chapter through Loan Commitments as they oblige banks to lend to its clients, up to a certain amount of funds at any time. This chapter points out that using Securitization as funding facility, could allow the banks to manage this Illiquidity Risk. To make this case, this chapter demonstrates empirically that banks having an increase in Loan Commitments, may experience an increase in risk profile but such can be offset by an accompanying increase in Securitization Activity. Lastly, the third chapter focuses on how banks manage Credit Risk also through Securitization. Securitization has a Credit Risk management property by allowing the offloading of risk. This chapter investigates how banks use such property by looking at the effect of securitization on the banks’ loan portfolios and overall risk and returns. The findings are that securitization is positively related to loan portfolio size and the portfolio share of risky loans, which translates to higher risk and returns. Thus, this chapter points out that Credit Risk management through Securitization may be have been done towards higher risk taking for high returns.

Scopo dello studio: valutare i cambiamenti indotti da diversi trattamenti di mordenzatura sulla morfologia superficiale e sulla microstruttura di due vetro-ceramiche a base disilicato di litio (IPS e.max® Press e IPS e.max® CAD) ed esaminarne gli effetti sia sull’adesione con un cemento resinoso che sulla resistenza alla flessione. Materiali e metodi: Settanta dischetti (12 mm di diametro, 2 mm di spessore) di ogni ceramica sono stati preparati e divisi in 5 gruppi: nessun trattamento (G1), HF 5% 20s (G2), HF 5% 60s (G3), HF 9.6% 20s (G4), HF 9.6% 60s (G5). Un campione per ogni gruppo è stato analizzato mediante profilometro ottico e osservato al SEM. Per gli altri campioni è stato determinato lo shear bond strength (SBS) con un cemento resinoso. Dopo l’SBS test, i campioni sono stati caricati fino a frattura utilizzando il piston-on-three-ball test per determinarne la resistenza biassiale alla flessione. Risultati: L’analisi morfologica e microstrutturale dei campioni ha rivelato come diversi trattamenti di mordenzatura producano delle modifiche nella rugosità superficiale che non sono direttamente collegate ad un aumento dei valori di adesione e dei cambiamenti microstrutturali che sono più rilevanti con l’aumento del tempo di mordenzatura e di concentrazione dell’acido. I valori medi di adesione (MPa) per IPS e.max® CAD sono significativamente più alti in G2 e G3 (21,28 +/- 4,9 e 19,55 +/- 5,41 rispettivamente); per IPS e.max® Press, i valori più elevati sono in G3 (16,80 +/- 3,96). La resistenza biassiale alla flessione media (MPa) è più alta in IPS e.max® CAD (695 +/- 161) che in IPS e.max® Press (588 +/- 117), ma non è non influenzata dalla mordenzatura con HF. Conclusioni: il disilicato di litio va mordenzato preferibilmente con HF al 5%. La mordenzatura produce alcuni cambiamenti superficiali e microstrutturali nel materiale, ma tali cambiamenti non ne influenzano la resistenza in flessione. / Purpose: The aim of this study was to evaluate the changes induced by different etching treatments on the surface morphology and microstructure of two lithium disilicate-based glass ceramic (IPS e.max® Press and IPS e.max® CAD) and examine the effects on the bond strength between ceramic and composite resin and on the biaxial flexural strength. Materials and methods: Seventy discs (12 mm diameter, 2 mm thickness) of each ceramic were prepared and divided in 5 groups: no treatment (G1), HF 5% 20s (G2), HF 5% 60s (G3), HF 9.6% 20s (G4), HF 9.6% 60s (G5). One specimen for each group was examined by optical profilometer and observed under scanning electron microscopy. On the other specimens was determined the shear bond strength (SBS) with a resin cement. After SBS test, specimens were loaded to failure using a piston-on-three-ball test to determine the biaxial flexural strength. Results: morphological analysis of treated specimens showed that different etching treatments produces changes in surface roughness but this changes are not directly related to an increasing adhesion value. The SEM analysis revealed that etching causes microstructural changes in lithium disilicate which are more relevant with the increasing of etching time and acid concentration. The mean bond strength values (MPa) for IPS e.max® CAD are statistically higher in G2 and G3 (21,28 +/- 4,9 and 19,55 +/- 5,41 respectively); for IPS e.max® Press, G3 has significant higher adhesion value (16,80 +/- 3,96). The mean biaxial flexural strength values (MPa) are significantly higher in IPS e.max® CAD (695 +/- 161) than in IPS e.max® Press (588 +/- 117). Etching with HF does not affect the flexural strength of the material. Conclusions: lithium disilicate has to be etched preferably with 5% HF. Etching produces several changes in surface and microstructure of the material, but does not compromise the flexural strength.

We introduce labelled sequent calculi for indexed modal logics. We prove that the structural rules of weakening and contraction are height-preserving admissible, that all rules are invertible, and that cut is admissible. Then we prove that each calculus introduced is sound and complete with respect to the appropriate class of transition frames.

Recentemente, sempre più attenzione è stata rivolta all' utilizzo di coloranti organici come assorbitori di luce per la preparazione di strati fotoattivi in celle solari organiche (OPV). I coloranti organici presentano un'elevata abilità nella cattura della luce solare grazie all'elevato coefficiente di estinzione molare e buone proprietà fotofisiche. Per questi motivi sono eccellenti candidati per l'incremento della conversione fotoelettrica in OPV. In questa tesi viene descritta una nuova strategia per l'incorporazione di derivati porfirinici in catena laterale a copolimeri tiofenici. Gli studi svolti hanno dimostrato che poli(3-bromoesil)tiofene può essere variamente funzionalizzato con idrossitetrafenilporfirina (TPPOH), per l'ottenimento di copolimeri utilizzabili come materiali p-donatori nella realizzazione di OPV. I copolimeri poli[3-(6-bromoesil)tiofene-co-(3-[5-(4-fenossi)-10,15,20-trifenilporfirinil]esil tiofene] P[T6Br-co-T6TPP] contenenti differenti quantità di porfirina, sono stati sintetizzati sia con metodi non regiospecifici che regiospecifici, con lo scopo di confrontarene le proprietà e di verificare se la strutture macromolecolare che presenta una regiochimica di sostituzione sempre uguale, promuove o meno il trasporto della carica elettrica, migliorando di conseguenza l'efficienza. E' stato inoltre effettuato un ulteriore confronto tra questi derivati e derivati simili P[T6H-co-T6TPP] che non contengono l'atomo di bromo in catena laterale con lo scopo di verificare se l'assenza del gruppo reattivo, migliora o meno la stabilità termica e chimica dei film polimerici, agendo favorevolmete sulle performance dei dispositivi fotovoltaici. Tutti i copolimeri sono stati caratterizzati con differenti tecniche: spettroscopia NMR, FT-IR e UV-Vis, analisi termiche DSC e TGA, e GPC. Le celle solari Bulk Heterojunction, preparate utilizzando PCBM come materiale elettron-accettore e i copolimeri come materilai elettron-donatori, sono state testate utilizzando un multimetro Keithley e il Solar Simulator. / Recently, more and more attention has been directed to the application of organic dyes as light absorbers for the preparation of active polymeric layers in organic photovoltaic (OPV) solar cells. Organic dyes usually present a strong light-harvesting ability, thanks to their high extinction coefficient, and useful photophysical properties and are good candidates for the improvement of OPV solar cells photocurrent. In this work is described a new strategy for the incorporation of a porphyrin derivatives in the side chain of a polythiophene copolymers. The studies carried out have shown that poly[3-(6-bromohexyl)thiophene] can be variously functionalized with hydroxytetraphenylporphyrin [TPPOH] to obtain copolymers used as p-donors materials for the realization of the photoactive blend in OPV. The copolymers poly[3-(6-bromohexyl)thiophene-co-(3-[5-(4-phenoxy)-10,15,20-triphenylporphyrinyl]hexyl thiophene] P[T6Br-co-T6TPP] prepared at different chromophore contents were obtained through both not-regiospecific and regiospecific methods, with the aim to compare the properties and verify whether the macromolecular structure that presents the same regiochemistry of substitution along the system, promote the transport of electric charge, improving the efficiency. Was also carried out a further comparison between these derivatives and similar compounds P[T6H-co-T6TPP] which doesn’t link the bromine atom in the side chain, with the purpose to verify if the absence of the reactive group may improve the thermal and chemical stability of the polymer films, acting on the performance of photovoltaic devices. All the soluble and easily filmable copolymers, have been deeply characterized using different techniques, such as NMR, FT-IR and UV-Vis spectroscopy, DSC and TGA analyses, and GPC. The bulk heterojunction solar cells prepared using PCBM as electron-acceptor molecule and the copolymers as electron-donor molecules were tested using Keithley multimeter and Solar Simulator.

Charge transport in conjugated polymers as well as in bulk-heterojunction (BHJ) solar cells made of blends between conjugated polymers, as electron-donors (D), and fullerenes, as electron-acceptors (A), has been investigated. It is shown how charge carrier mobility of a series of anthracene-containing poly(p-phenylene-ethynylene)-alt-poly(p-phenylene-vinylene)s (AnE-PVs) is highly dependent on the lateral chain of the polymers, on a moderate variation of the macromolecular parameters (molecular weight and polydispersity), and on the processing conditions of the films. For the first time, the good ambipolar transport properties of this relevant class of conjugated polymers have been demonstrated, consistent with the high delocalization of both the frontier molecular orbitals. Charge transport is one of the key parameters in the operation of BHJ solar cells and depends both on charge carrier mobility in pristine materials and on the nanoscale morphology of the D/A blend, as proved by the results here reported. A straight correlation between hole mobility in pristine AnE-PVs and the fill factor of the related solar cells has been found. The great impact of charge transport for the performance of BHJ solar cells is clearly demonstrated by the results obtained on BHJ solar cells made of neat-C70, instead of the common soluble fullerene derivatives (PCBM or PC70BM). The investigation of neat-C70 solar cells was motivated by the extremely low cost of non-functionalized fullerenes, compared with that of their soluble derivatives (about one-tenth). For these cells, an improper morphology of the blend leads to a deterioration of charge carrier mobility, which, in turn, increases charge carrier recombination. Thanks to the appropriate choice of the donor component, solar cells made of neat-C70 exhibiting an efficiency of 4.22% have been realized, with an efficiency loss of just 12% with respect to the counterpart made with costly PC70BM.

The consistent, uniform pressing of green bodies is a necessary part of producing high-quality, high-performance ceramics with predictable qualities and behavior. Undesirable density variation in the compacted ceramic powder causes variability in performance, failure to meet quality control standards, and, possibly, complete piece failure during successive processing. These issues contribute directly to a decrease in production efficiency through lost time and an increase in energy and material use. The careful control of the green body density field is of the utmost importance to consistently producing high-performance ceramics. Current methods for minimizing heterogeneity of the density field are often based on trial-and-error to optimize mold geometry and forming pressure, which is both expensive and prolongs development. The present research presents a continuum-level constitutive model for accurately modeling the densification of ceramic powders into green bodies and outlines the numerical implimentation of said model. The constitutive model incorporates nonlinear elasticity, elatic-plastic coupling, cap evolution, pressure- and Lode angle-dependent plasticity, and hardening. To evaluate the constitutive model, a new method for measuring density in green bodies has been developed. This method utilizes readily-available laboratory equipment to produce density projection data for the sample and subsequently processes that data to produce a 3D density field using well-developed tomographic reconstruction techniques. Finally, a green body is produced from alumina powder (Martoxid KMS-96) and the density field is evaluated and compared to that of a numerical simulation. They are shown to agree within the error of the density measurements. These comparisons demonstrate the performance of the developed constitutive model and the potential utility for companies and research institutions that are in the ceramics production field.

Through a second-order homogenization procedure, the explicit relation is obtained between the non-local parameters of a second gradient elastic ma- terial and the microstructure of a composite material. This result is instru- mental for the definition of higher-order models, to be used for the analysis of mechanics at micro- and nano-scale, where size-effects become important. The obtained relation is valid for both plane and three-dimensional prob- lems and generalizes earlier findings by Bigoni and Drugan (Analytical deriva- tion of Cosserat moduli via homogenization of heterogeneous elastic materials. J. Appl. Mech., 2007, 74, 741753) from several points of view: i) the result holds for anisotropic phases with spherical or circular ellipsoid of inertia; ii) the displacement boundary conditions considered in the homogenization procedure is independent of the characteristics of the material; iii) a perfect energy match is found between heterogeneous and equivalent materials (instead of an optimal bound). From the obtained solution it follows that the equivalent second-gradient Mindlin elastic solid: a) is positive definite only when the discrepancy tensor is negative defined; b) the non-local material symmetries are the same of the discrepancy tensor; c) the non-local effective behaviour is affected by the shape of the RVE, which does not influence the first-order homogenized response. Finally, explicit derivations of non-local parameters from heterogeneous Cauchy elastic composites are obtained in particular cases.

TThe present work addresses the rigorous derivation of the Flügge treatment of the buckling of a thin cylinder. The incremental equilibrium equations in terms of generalized stresses are rigorously derived in terms of mean quantities (holding true regardless of the thickness of the cylinder), through a generalization of the approach introduced by Biot (1965) for rectangular plates. The incremental kinematics is postulated through a novel deduction from the deformation of a two-dimensional surface, thus generalizing an approach introduced to derive the incremental kinematics of a plate. The nonlinear elastic constitutive equations proposed by Pence and Gou (2015), describing a nearly incompressible neo-Hookean material, are used in a rigorous way. While the employed kinematics coincides with that used by Flügge, the incremental equilibrium and constitutive equations derived in this work are different from those given by Flügge, but are shown to reduce to the latter by invoking the smallness of the cylinder wall. The equations derived for the incremental deformation of prestressed thin cylindrical shells are general and can be used for different purposes. The study of the bifurcation problem of a thin-walled circular cylinder subject to compressive load is offered. When compared, the bifurcation landscape obtained from the formulation developed in this work and that given by Flügge are numerically shown to coincide and be consistent with results obtained by a fully three-dimensional theory of nonlinear elasticity. Furthermore the formula for the axial buckling stress of a ‘mid-long’ cylindrical shell made of a nearly incompressible neo-Hookean material and of a Mooney-Rivlin material are rigorously obtained from the presented formulation.

The present Ph.D. dissertation is divided into two Parts: Green's function and problems of the inclusions and dislocations are addressed in the first Part, while implementation of elastoplastic constitutive laws are treated in the second. These subjects can be seen as different approaches to the investigation of the plastic behaviour of materials. In the first Part, infinite-body two-dimensional Green's functions are derived for the incremental deformation of an incompressible, anisotropic, prestressed body. These functions, given by Bigoni and Capuani, show the response of an infinite body to a concentrated force. The effect of prestress on dislocation (and inclusion) fields in non-linear elastic solids is analyzed by extending previous solutions by Eshelby and Willis. Employing a plane strain constitutive model (for incompressible incremental non-linear elasticity) to describe the behaviour a broad class of (anisotropic) materials, but with a special emphasis on ductile metals (J2-deformation theory of plasticity), it is shown that strongly localized strain patterns emerge, when a dislocation dipole is emitted by a source and the prestress level is high enough. These strain patterns may explain cascade activation of dislocation clustering along slip band directions. Several of the presented results remain valid within a three-dimensional context. Novel infinite-body three-dimensional Green's functions are derived for the incremental deformation of an incompressible, anisotropic, prestressed body. The case of a force dipole is developed within this framework. Results are used to investigate the behaviour of a material deformed near the limit of ellipticity loss and to reveal features related to shear failure cones development in a three-dimensional solid medium. Non-standard elastoplastic constitutive laws are treated in the second Part of the present Ph.D. dissertation, based on pressure-sensitive yield functions, such that proposed by Bigoni and Piccolroaz, which describes the inelastic deformation of ceramic powders and of a broad class of rock-like and granular materials. This yield function is not defined outside the yield locus, so that 'gradient-based' integration algorithms of elastoplasticity cannot be directly employed. Therefore, two ad hoc integration algorithms are proposed: an explicit scheme based on a forward Euler technique with a 'centre-of-mass' return correction and an implicit scheme based on a 'cutoff-substepping' return algorithm.