In this work, two types of nano-structured TiO2 layers were obtained by two different methods. First, during an exploratory study, a set of nano-columnar TiO2 films and niobium doped TiO2 films was obtained on stainless steel, by a RF reactive sputtering technique. The argon gas is ionized by a high negative voltage applied to the TiO2 target (cathode), and a plasma is created between the cathode and the substrate (anode). Positively charged ions (Ar+) are accelerated toward the TiO2 target (a co-target Nb is placed beside the TiO2 cathode for Nb doping) and their impact sputters atoms off the target. These atoms travel across the chamber and a fraction of them land on stainless steel, resulting in a film TiO2 and Nb-doped film TiO2. With adjusting the RF power applied on the co – target, different concentrations of Nb in the TiO2 film could be controlled. The results of EIS (Electrochemical Impedance Spectroscopy) mainly showed the presence of a barrier layer (junction metal/semiconductor or metal/oxide/semiconductor) between the TiO2 layer and the stainless steel in the absence and presence of niobium. The carrier density is estimated at almost 1018 cm-3. In the second part of this thesis, two types of TiO2 nano-tubular arrays with nanotubes (NT) aligned perpendicular to the titanium substrate were obtained by anodization of a titanium foil, in two different solutions containing fluoride ions. The NT obtained in a tetrabutylammonium / formamide solution (named: TiO2-NT(TB)) are rough, while the second solution, ethylene glycol , allows to synthesize smoother and denser tubes (named: TiO2-NT(EG)). All the nanotubular arrays were characterized by EIS and showed in the high frequency range a contribution related to the presence of surface states, and a contribution at low frequencies related to the capacity of the space charge layer. In the dark, in the Na2SO4 solution with neutral pH, the EIS study of TiO2-NT (TB) anatase showed that these two contributions vary with the applied potential. The capacity of surface states varied exponentially in a wide range of potential, but in addition the presence of a localized energy state in the gap could be evidenced. This localized state is the signature of the adsorption of molecular water. After UV exposure during 3h, and back to the dark, the quasi irreversible disappearance of the localized energy states is related to photo-induced adsorbed water dissociation at some sites on the surface of NT. Furthermore, the increase by a factor 112 of the capacity of the space charge layer was observed after UV exposure. This increase can be explained by the photo activation of the surface of NT, which was inactive before UV exposure. This activation is related to the dissociation of adsorbed molecular water and the insertion of hydrogen into the walls of NT. A geometric model considering the variation of the band bending taking place inside the wall of NT is proposed to replace the classical Mott-Schottky relation, which is only valid for a plate condensator. This model allows understanding the variation of the space charge layer as a function of the applied potential. With this new model, a carrier density of about 1018 cm-3 et 1020 cm-3 respectively before and after UV illumination were determined, confirming that the photo-induced activation of the wall of NT is linked to the phenomenon of doping due to hydrogen insertion. In the case of TiO2 –NT(EG), the contribution of adsorption of molecular water was not observed. The spectrum of EIS before and after UV exposure did not show a significant change and the capacities of space charge layer after illumination only increased by a factor 8. The simulation with the model shows that the carrier density is about 1020cm-3 before and after illumination. In other words, these tubes of TiO2 –NT(EG), are already activated before illumination and the photo-induced effects are less important compared to the TiO2 –NT(TB) array. For a better identification of the chemical nature of the surface state in the case of rough tubes of TiO2 –NT(TB), EIS measurements were performed in the same manner, but in acidic (pH=3.5) and basic (pH=12.5) media, in order to compare the behaviour to that observed in the neutral Na2SO4 solution. In the alkaline electrolyte, the band bending varies only slightly with the applied potential, reflecting a shift of band edge and the filling/emptying of the surface states during polarization. Moreover, the exponential distribution of capacities of surface states is more spread out (850 meV) in alkaline solution than in the neutral solution (257meV), showing clearly the particular role of the OH groups at the surface of the tubes. In the acidic electrolyte, a phenomenon of diffusion –insertion of protons should be taken into account for interpreting the spectra of EIS. H atoms play the role of electron donors able to increase the carrier density in the wall of the tubes. The comparison between the behaviours in the 3 media clearly associates the surface states to hydroxyl groups. In the last part of this thesis, experiments were performed on TiO2 –NT(TB) in a NaOH electrolyte, using Intensity Modulated Photocurrent Spectroscopy (IMPS), and the results are discussed in comparison with a thin compact film deposed on a titanium foil par PVD.

The aim of this thesis is to study renormalization of Wick polynomials of quantum Boson fields in locally covariant algebraic quantum field theory in curved spacetime. Vector fields are described as sections of natural vector bundles over globally hyperbolic spacetimes and quantized in a locally covariant framework through the known functorial machinery in terms of local *-algebras. These quantized fields may be defined on spacetimes with given classical background fields, also sections of natural vector bundles: The most obvious one is the metric of the spacetime itself, but we encompass also the case of generic spacetime tensors as background fields. In our framework also physical quantities like the mass of the field or the coupling to the curvature are viewed as background fields. Wick powers of the quantized vector field are then axiomatically defined imposing in particular local covariance, scaling properties and smooth dependence on smooth perturbation of the background fields. A general classification theorem is established for finite renormalization terms (or counterterms) arising when comparing different solutions satisfying the defining axioms of Wick powers. The result is then specialized to the case of spacetime tensor fields. In particular, the case of a vector Klein-Gordon field and the case of a scalar field renormalized together with its derivatives are discussed as examples. In each case, a more precise statement about the structure of the counterterms is proved. The finite renormalization terms turn out to be finite-order polynomials tensorially and locally constructed with the backgrounds fields and their covariant derivatives whose coefficients are locally smooth functions of polynomial scalar invariants constructed from the so-called marginal subset of the background fields. Our main technical tools are based on the Peetre-Slov\'ak theorem characterizing differential operators and on the classification of smooth invariants on representations of reductive Lie groups.

Thermally-driven slope winds are mesoscale atmospheric circulations, known as breezes, that take place because of the heating (cooling) of the air layer close to the ground during daytime (nighttime). Mostly known to occur on days with weak synoptic forcing and under clear sky conditions, the wind blows up valleys and slopes during the daytime, and in the opposite direction during nighttime. A better comprehension of slope winds can improve the understanding of the soil-atmosphere turbulent exchange processes and of the energy budget over complex terrain, in addition to the evaluation of the along-slope transport of dangerous species (pollutants, pesticides), as well as water vapor (relevant for the development of convection). This research project aims to improve the knowledge of thermally-driven slope winds, with particular attention to the differences between the diurnal and nocturnal regimes. This is done through a multiple-way approach. Field data analysis, analytical solutions with realistic forcing, and numerical models are all employed to fulfill the objective. At first, data from two stations located on slopes were analyzed. Measurements were taken in the surroundings of the Alpine city of Innsbruck, as part of the i-Box field campaign, covering a period of 7 years (2013 to 2020). Observation indicates a marked seasonality of the phenomena, with warm season months being more prone to the occurrence of slope winds. Moreover, the results highlighted the key role played by the local topographical characteristics in the development of pure slope wind days, with both slope angle and orientation playing a major role in the interplay between valley and slope winds. Previous results suggested the development of an improved analytical model which uses the available net radiation at the surface as the forcing for slope circulations, in the form of a truncated Fourier series expansion. The net radiation model accounts for both the seasonality (day of the year) and the local topographic characteristics (latitude, slope angle, orientation, elevation). Therefore, differences in the properties of slope winds occurring in different seasons and on slopes with different slope angles and orientations are highlighted and studied. The last chapter of the thesis investigates the structure of the eddy viscosity and diffusivity employing numerical models. These parameters govern the mass, momentum, and heat turbulent exchanges from slope winds. A simple one-dimensional model was developed to test different turbulence closures. In particular, the attention focused on the so-called K-l closure, meaning that the eddy viscosity and diffusivity parameters are bounded to the turbulence length scale l, representing the distance a turbulent eddy can travel “carrying” heat, momentum, and mass. In the current work, different parameterizations of the turbulence length scale l are tested and compared. Results show how simple K-l closures are compared with other non-constant K profiles proposed in the literature for the case of katabatic winds. Nevertheless, such simple parameterizations for the turbulence length scale l still fail to properly discriminate between the daytime and nighttime regimes of slope winds.

MACPF/CDCs proteins are a huge family of pore-forming proteins present from the bacteria to the human genera. Cholesterol-dependent cytolysins (CDCs) are a family of toxins that participate in bacterial infection pathway at the membrane level. Great interest in this family is due to their similarity, in structure and in pore-forming mechanism, with some human immune system proteins (MACPF). We focused our attention particularly on two bacterial CDCs, Perfringolysin O and Listeriolysin O, and on the human protein Perforin, which is involved in the apoptotic pathway facilitating Granzyme release. In the literature, two possible configurations of CDCs and Perforin pores are proposed: ring and arc structures that could have different implications on the biological mechanism of action of these pore-forming proteins. By electrophysiological measurements and atomic force microscopy technique on different artificial membrane, we are able to enrich the ring and the arc fraction and demonstrate that both kinds of pore are active, i.e. conduct ions. Thus, my PhD work underlines two physiological structures which are involved in several ways, more than merely by disrupting membrane integrity, in pathogenic attack (bacterial CDCs proteins) as well as in immune response (human Perforin proteins).

Time-resolved fluorescence measurements enable the study of structure of molecular systems and dynamical processes inside them. This is possible because of a very high sensitivity of fluorescence lifetime to the physical and chemical properties of micro-environment in which fluorophores are situated. However, proper detection of the fluorescence lifetime is a challenging task, due to the fact that the fluorescence decay time of commonly used fluorophores lies in a nanosecond range. This puts strict requirements on the parameters of the fluorescence detectors. The features of single-photon avalanche diodes (SPAD) make these optical detectors a good alternative to conventional photomultiplier tubes and micro-channel plates. CMOS technology allows cointegration of a SPAD and electronic circuits on the same substrate and provides advantages in time resolution and noise characteristics. Monolithic integration of signal processing circuits and detectors on the same chip allows using such detectors without additional external hardware. New SPAD sensors with improved characteristics are produced every year. However, the designers consider various performance metrics while the importance of each particular detector characteristic depends on its application. Therefore, the validation and optimization of SPAD characteristics should be performed in a close connection with the analysis of a specific system, wherein this detector will be used. This work was aimed at developing of a model able to describe a typical fluorescence experiment with SPAD-based detector. The model simulates all essential parts of the fluorescence experiment starting from the light emission, through photo-physical processes occurring inside a bio-sample, to a detector itself and read-out electronics. The ability of the developed model to simulate various light sources (laser and micro-LED), fluorescence measurement techniques (time-correlated single photon counting and time-gating) was verified. The simulated results were in good agreement with the experimental data and the model proved its flexibility. Furthermore, the model provided the explanation of the distortions in experimental fluorescent curves measured under a very high ambient light when pile-up effects appear. Finally, a set of virtual experiments were established to investigate the influence of noisy pixels in SPAD array on a lifetime estimation and to study the feasibility of time-filtering instead of conventional optical filtering. Simulation results are in good agreement with data available in literature.

The purpose of this thesis is to focus on the aspect of passive devices allowing for WDM, routing, switching and filtering of optical signals, investigating novel routing concepts based on micro optical side coupled resonators to achieve large bandwidth by multiple cascading and/or multiple coupling (low group velocity) periodicity effects. We will describe some technical aspects necessary for the design and fabrication of some passive circuitry, and usually neglected in purely theoretical approaches, including optical routers based on racetrack resonators and novel SCISSOR and CROW devices.

Atomistic simulations based on Molecular Dynamics (MD) were used to model the lattice distortions in metallic nano-polycrystalline microstructures, with the purpose of supporting the analysis of the X-ray powder diffraction patterns with a better, atomic level understanding of the studied system. Complex microstructures were generated with a new modified Voronoi tessellation method which provides a direct relation between generation parameters and statistical properties of the resulting model. MD was used to equilibrate the system: the corresponding strain field was described both in the core and in surface regions of the different crystalline domains. New methods were developed to calculate the strain tensor at the atomic scale. Line Profile Analysis (LPA) was employed to retrieve the microstructure information (size and strain effects) from the powder diffraction patterns: a general algorithm with an atomic level resolution was developed to consider the size effects of crystalline domains of any arbitrary shape. The study provided a new point of view on the role of the grain boundary regions in nano-polycrystalline aggregates, exploring the interference effects between different domains and between grain boundary and crystalline regions. Usual concepts of solid mechanics were brought in the atomistic models to describe the strain effects on the powder diffraction pattern. To this purpose the new concept of Directional - Pair Distribution Function (D-PDF) was developed. D-PDFs calculated from equilibrated atomistic simulations provide a representation of the strain field which is directly comparable with the results of traditional LPA (e.g. Williamson-Hall plot and Warren-Averbach method). The D-PDF opens a new chapter in powder diffraction as new insights and a more sound interpretation of the results are made possible with this new approach to diffraction LPA.

Matter at the nanoscale exhibits peculiar properties, often not shown by the bulk counterpart, and strongly coupled to the specific size, shape and structure of the atomic aggregate. Particularly, the enormous surface-to-volume ratio implies boosted reactivity with respect to the environment, while the electronic confinement might cause quantum effects to dominate physical properties. Characterization techniques are of course essential to investigate properties at the atomic scale. Scattering techniques have tremendously evolved in the recent past benefiting from third and fourth generation light sources, producing beams with unprecedented spatial and temporal resolution. In a different realm, atomistic simulations have also greatly evolved deriving advantages from both recent theories and modern computing units. In this framework, a detailed description of the system in a spatial and temporal range compatible with lengths probed by scattering techniques is provided. In a single sentence, the subject of this Thesis is the effort of tying atomistic methods and scattering techniques so to increase the comprehension around size, shape and structure of nanostructured particles.

This work presents the design, realization and characterization of high efficiency Silicon photovoltaic cells for concentration applications. In order to develop high efficient Si concentrator solar cells two different ways have been followed. The first one aims to optimize the design and the fabrication process of a conventional front-side contacted cell, based on a planar n-p junction. Although this cell structure is rather simple and cheap to produce, we show that a conversion effciency higher than 23% can be reached under concentrated light, if the cell design and the fabrication process are suitably optimized. The second way aims to investigate and propose completely new cell designs which use some 'three-dimensional' structures, such as deep-grooved contacts and through-silicon vertical connections. The new cell designs allow to overcome some intrinsic limits of the conventional front-side contacted cells and could be worthwhile to improve the conversion eciency in future real applications.

The results of research activities performed in two Italian Alpine valleys (Chiese Valley, Trentino; Camonica Valley, Lombardy) are presented. The four intensive field campaigns held during summer 2019 and winter 2020 covered different topics: wintertime black carbon (BC) concentrations, techniques for measuring PM10 and temperature vertical profiles, surface size-resolved aerosol fluxes, aerosol concentrations, and chemical composition. Firstly, the contribution of two significant PM sources (traffic and biomass burning) to wintertime total black carbon concentrations was estimated, and the effect of meteorological factors on BC levels was assessed. In both pilot areas, traffic resulted as the predominant BC source during the daytime, while biomass burning weighed more than 50% at night. Atmospheric mixing and strong winds contributed to the removal of BC from the atmosphere, while wet scavenging was not effective if accompanied by low wind and friction velocities along with a significant increase in emission sources. Other aerosol sources, such as secondary particulate matter formation in the atmosphere, manure, fertilizers, or lithospheric erosion, were instead appointed in both seasons through the chemical speciation of the inorganic aerosol fraction, which had deposited on the filters of a multi-stage Electrical Low-Pressure Impactor (Elpi+, Dekati, FI) during an entire campaign. Results showed that SIA (secondary inorganic aerosol) components were the most abundant inorganic water-soluble ions in the collected samples. Secondly, three techniques for measuring PM10 and temperature vertical distributions were applied and compared. The first method enabled continuous monitoring by positioning 5 battery-powered stations, equipped with low-cost sensors, on the mountain slope overlooking the valleys. These measurements extended up to about 1000 m above the valley floor and were accompanied by drone profiles in summer and tethered balloon soundings in winter, both of them equipped with the same sensors installed in the slope stations. The research aimed at evaluating the effectiveness of the temperature and PM10 slope pseudo-vertical profiles in reproducing soundings measured in the valley centre. Slope stations successfully replicated the vertical profiles, especially in the morning/evening hours, thus representing a good and inexpensive alternative for long-lasting campaigns or even excellent support to traditional methods. Finally, the role of a typical alpine agro-economic ecosystem (pasture/grass field) in the atmosphere-Earth surface aerosol exchange was evaluated, studying aerosol size-segregated fluxes (9 classes, 10 nm ≤ GMD ≤ 0.76 m) with the eddy covariance technique, employing the aforementioned Dekati (FI) Elpi+ multi-stage impactor. Surprisingly, the pasture did not behave as an aerosol sink, favouring aerosol removal from the atmosphere, but rather contributed to the formation of secondary particulate matter through ammonia, NOX, and organic sulphides emissions from soil and vegetation. Deposition phenomena were registered under atmospheric stability or low turbulence conditions, but emission phenomena were very frequent, especially during winter. Thanks to the ion chromatography analysis of the inorganic particulate soluble fraction deposited on the impactor filters, aerosol fluxes were also linked to aerosol chemical composition and sources, thus hypothesizing nucleation, growth, and coagulation processes as responsible for the formation of concentration gradients in the atmosphere and the observation of deposition fluxes in the ultrafine range. The data collected and described in the present thesis had an interesting follow-up within the EU Alpine Space project BB-CLEAN, within which the activities developed. In particular, the experimental data were used by modellists to calibrate a meteorological and dispersion modelling chain that provided 48-hour PM concentration forecasts to a smartphone app, indicating when the activation of biomass burning heating systems might be sustainable. The researchers of the BB-CLEAN project also employed the model to evaluate some scenarios that envisaged the reduction of PM emissions from biomass burning appliances (e.g., through system upgrades, app use, and realization of a district heating network). Simulations showed that some of these scenarios could lead to a significant decrease in PM concentrations. However, no scenario can be elected as an absolute best, as policymakers should consider the characteristics of their respective municipalities when faced with the need to decide which scenario to implement.