5 resultados para Fermi superfluid

em AMS Tesi di Dottorato - Alm@DL - Università di Bologna


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In Italia, il contesto legislativo e l’ambiente competitivo dei Confidi è profondamente mutato negli ultimi anni a seguito dell’emanazione di due nuove normative: la “Legge Quadro” sui Confidi e la nuova regolamentazione del capitale di vigilanza nelle banche (c.d. "Basilea 2"). la Legge Quadro impone ai Confidi di adottare uno dei seguenti status societari: i) ente iscritto all’albo di cui all’art. 106 del Testo Unico Bancario (TUB); ii) ente iscritto all’albo di cui all’art. 107 del Testo Unico Bancario; iii) banca cooperativa di garanzia collettiva dei fidi. Fermi restando i requisiti soggettivi sui garanti ammessi da Basilea 2, la modalità tecnica finora utilizzata dai Confidi non risponde ai requisiti oggettivi. Il pensiero strategico si enuclea nelle seguenti domande: A) qual è la missione del Confidi (perché esistono i Confidi)? B) Quali prodotti e servizi dovrebbero offrire per raggiungere la loro missione? C) Quale modello organizzativo e di governance si conforma meglio per l'offerta dei prodotti e servizi individuati come necessari per il raggiungimento della missione? Le riflessioni condotte nell’ambito di un quadro di riferimento delineato dal ruolo delle garanzie nel mercato del credito bancario, dalle “Nuove disposizioni di vigilanza prudenziale per le banche”, dalla “Legge Quadro” sui e, infine, dall’assetto istituzionale ed operativo dei Confidi si riassumono nelle seguenti deduzioni: Proposizione I: segmentare la domanda prima di adeguare l’offerta; Proposizione II: le operazioni tranched cover sono un'alternativa relativamente efficiente per l'operatività dei Confidi, anche per quelli non vigilati; Proposizione III: solo i Confidi‐banca hanno la necessità di dotarsi di un rating esterno; Proposizione IV: le banche sono nuovi Clienti dei Confidi: offrire servizi di outsourcing (remunerati), ma non impieghi di capitale; Proposizione V: le aggregazioni inter settoriali nel medesimo territorio sono da preferirsi alle aggregazioni inter territoriali fra Confidi del medesimo settore. Alle future ricerche è affidato il compito di verificare: quali opzioni strategiche nel concreato siano state applicate; quali siano state le determinati di tali scelte; il grado di soddisfacimento dei bisogni degli stakeholder dei Confidi; misurare i benefici conseguiti nell'efficienza allocativa del credito.

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The main aims of my PhD research work have been the investigation of the redox, photophysical and electronic properties of carbon nanotubes (CNT) and their possible uses as functional substrates for the (electro)catalytic production of oxygen and as molecular connectors for Quantum-dot Molecular Automata. While for CNT many and diverse applications in electronics, in sensors and biosensors field, as a structural reinforcing in composite materials have long been proposed, the study of their properties as individual species has been for long a challenging task. CNT are in fact virtually insoluble in any solvent and, for years, most of the studies has been carried out on bulk samples (bundles). In Chapter 2 an appropriate description of carbon nanotubes is reported, about their production methods and the functionalization strategies for their solubilization. In Chapter 3 an extensive voltammetric and vis-NIR spectroelectrochemical investigation of true solutions of unfunctionalized individual single wall CNT (SWNT) is reported that permitted to determine for the first time the standard electrochemical potentials of reduction and oxidation as a function of the tube diameter of a large number of semiconducting SWNTs. We also established the Fermi energy and the exciton binding energy for individual tubes in solution and, from the linear correlation found between the potentials and the optical transition energies, one to calculate the redox potentials of SWNTs that are insufficiently abundant or absent in the samples. In Chapter 4 we report on very efficient and stable nano-structured, oxygen-evolving anodes (OEA) that were obtained by the assembly of an oxygen evolving polyoxometalate cluster, (a totally inorganic ruthenium catalyst) with a conducting bed of multiwalled carbon nanotubes (MWCNT). Here, MWCNT were effectively used as carrier of the polyoxometallate for the electrocatalytic production of oxygen and turned out to greatly increase both the efficiency and stability of the device avoiding the release of the catalysts. Our bioinspired electrode addresses the major challenge of artificial photosynthesis, i.e. efficient water oxidation, taking us closer to when we might power the planet with carbon-free fuels. In Chapter 5 a study on surface-active chiral bis-ferrocenes conveniently designed in order to act as prototypical units for molecular computing devices is reported. Preliminary electrochemical studies in liquid environment demonstrated the capability of such molecules to enter three indistinguishable oxidation states. Side chains introduction allowed to organize them in the form of self-assembled monolayers (SAM) onto a surface and to study the molecular and redox properties on solid substrates. Electrochemical studies on SAMs of these molecules confirmed their attitude to undergo fast (Nernstian) electron transfer processes generating, in the positive potential region, either the full oxidized Fc+-Fc+ or the partly oxidized Fc+-Fc species. Finally, in Chapter 6 we report on a preliminary electrochemical study of graphene solutions prepared according to an original procedure recently described in the literature. Graphene is the newly-born of carbon nanomaterials and is certainly bound to be among the most promising materials for the next nanoelectronic generation.

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This thesis analyzes theoretically and computationally the phenomenon of partial ionization of the substitutional dopants in Silicon Carbide at thermal equilibrium. It is based on the solution of the charge neutrality equation and takes into account the following phenomena: several energy levels in the bandgap; Fermi-Dirac statistics for free carriers; screening effects on the dopant ionization energies; the formation of impurity bands. A self-consistent model and a corresponding simulation software have been realized. A preliminary comparison of our calculations with existing experimental results is carried out.

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The aim of this thesis was the synthesis and photophysical characterization of some new polysulfurated aromatic compounds: this class of molecules can offer intriguing properties, potentially useful for the construction of new materials for optoelectronic devices. Two main families of compounds have been synthesized: the first is represented by a series of small molecular asterisks, with peripheral aromatic units, showing luminescence in solid phase or in highly rigid conditions. All compounds with peripheral substituents display an AIE behavior (Aggregation Induced Emission) with radiative deactivation of the triplet states. Taking inspiration from these smaller asterisks, a larger molecule with the same geometry has been designed, decorated with terpyridyl moieties as the outermost units: this compound shows great affinity for the coordination of several transition metal ions, changing luminescence properties after the interaction with zinc ions. With the same intentions, a tetrasulfurated pyrene-core molecule with terpyridyl external units has been synthesized and isolated: this ligand exhibits good coordination capabilities towards transition metal ions, giving rise to luminescent nanoaggregates upon addition of zinc(II), characterized by DLS and AFM microscopy. In addition a NIR emission is recorded after coordination of neodymium(III), showing evidence of an intramolecular energy transfer process.

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In this thesis work we will explore and discuss the properties of the gamma-ray sources included in the first Fermi-LAT catalog of sources above 10 GeV (1FHL), by considering both blazars and the non negligible fraction of still unassociated gamma-ray sources (UGS, 13%). We perform a statistical analysis of a complete sample of hard gamma-ray sources, included in the 1FHL catalog, mostly composed of HSP blazars, and we present new VLBI observations of the faintest members of the sample. The new VLBI data, complemented by an extensive search of the archives for brighter sources, are essential to gather a sample as large as possible for the assessment of the significance of the correlation between radio and very high energy (E>100 GeV) emission bands. After the characterization of the statistical properties of HSP blazars and UGS, we use a complementary approach, by focusing on an intensive multi-frequency observing VLBI and gamma-ray campaign carried out for one of the most remarkable and closest HSP blazar Markarian 421.