New materials for electrochemiluminescence

The study of electrochemiluminescence (ECL) involves photophysical and electrochemical aspects. Excited states are populated by an electrical stimulus. The most important applications are in the diagnostic field where a number of different biologically-relevant molecules (e.g. proteins and nucleic acids) can be recognized and quantified with a sensitivity and specificity previously not reachable. As a matter of fact the electrochemistry, differently to the classic techniques as fluorescence and chemiluminescence, allows to control the excited state generation spatially and temporally. The two research visits into A. J. Bard electrochemistry laboratories were priceless. Dr. Bard has been one of ECL pioneers, the first to introduce the technique and the one who discovered in 1972 the surprising emission of Ru(bpy)3 2+. I consider necessary to thank by now my supervisors Massimo and Francesco for their help and for giving me the great opportunity to know this unique science man that made me feel enthusiastic. I will never be grateful enough… Considering that the experimental techniques of ECL did not changed significantly in these last years the most convenient research direction has been the developing of materials with new or improved properties. In Chapter I the basics concepts and mechanisms of ECL are introduced so that the successive experiments can be easily understood. In the final paragraph the scopes of the thesis are briefly described. In Chapter II by starting from ECL experimental apparatus of Dr. Bard’s laboratories the design, assembly and preliminary tests of the new Bologna instrument are carefully described. The instrument assembly required to work hard but resulted in the introduction of the new technique in our labs by allowing the continuation of the ECL studies began in Texas. In Chapter III are described the results of electrochemical and ECL studies performed on new synthesized Ru(II) complexes containing tetrazolate based ligands. ECL emission has been investigated in solution and in solid thin films. The effect of the chemical protonation of the tetrazolate ring on ECL emission has been also investigated evidencing the possibility of a catalytic effect (generation of molecular hydrogen) of one of the complexes in organic media. Finally, after a series of preliminary studies on ECL emission in acqueous buffers, the direct interaction with calf thymus DNA of some complexes has been tested by ECL and photoluminescence (PL) titration. In Chapter IV different Ir(III) complexes have been characterized electrochemically and photophysically (ECL and PL). Some complexes were already well-known in literature for their high quantum efficiency whereas the remaining were new synthesized compounds containing tetrazolate based ligands analogous to those investigated in Chapt. III. During the tests on a halogenated complex was unexpectedly evidenced the possibility to follow the kinetics of an electro-induced chemical reaction by using ECL signal. In the last chapter (V) the possibility to use mono-use silicon chips electrodes as ECL analitycal devices is under investigation. The chapter begins by describing the chip structure and materials then a signal reproducibility study and geometry optimization is carried on by using two different complexes. In the following paragraphs is reported in detail the synthesis of an ECL label based on Ru(bpy)3 2+ and the chip functionalization by using a lipoic acid SAM and the same label. After some preliminary characterizations (mass spectroscopy TOF) has been demonstrated that by mean of a simple and fast ECL measurement it’s possible to confirm the presence of the coupling product SAM-label into the chip with a very high sensitivity. No signal was detected from the same system by using photoluminescence.

Non-Markovian stochastic processes and their applications: from anomalous diffusion to time series analysis

This work provides a forward step in the study and comprehension of the relationships between stochastic processes and a certain class of integral-partial differential equation, which can be used in order to model anomalous diffusion and transport in statistical physics. In the first part, we brought the reader through the fundamental notions of probability and stochastic processes, stochastic integration and stochastic differential equations as well. In particular, within the study of H-sssi processes, we focused on fractional Brownian motion (fBm) and its discrete-time increment process, the fractional Gaussian noise (fGn), which provide examples of non-Markovian Gaussian processes. The fGn, together with stationary FARIMA processes, is widely used in the modeling and estimation of long-memory, or long-range dependence (LRD). Time series manifesting long-range dependence, are often observed in nature especially in physics, meteorology, climatology, but also in hydrology, geophysics, economy and many others. We deepely studied LRD, giving many real data examples, providing statistical analysis and introducing parametric methods of estimation. Then, we introduced the theory of fractional integrals and derivatives, which indeed turns out to be very appropriate for studying and modeling systems with long-memory properties. After having introduced the basics concepts, we provided many examples and applications. For instance, we investigated the relaxation equation with distributed order time-fractional derivatives, which describes models characterized by a strong memory component and can be used to model relaxation in complex systems, which deviates from the classical exponential Debye pattern. Then, we focused in the study of generalizations of the standard diffusion equation, by passing through the preliminary study of the fractional forward drift equation. Such generalizations have been obtained by using fractional integrals and derivatives of distributed orders. In order to find a connection between the anomalous diffusion described by these equations and the long-range dependence, we introduced and studied the generalized grey Brownian motion (ggBm), which is actually a parametric class of H-sssi processes, which have indeed marginal probability density function evolving in time according to a partial integro-differential equation of fractional type. The ggBm is of course Non-Markovian. All around the work, we have remarked many times that, starting from a master equation of a probability density function f(x,t), it is always possible to define an equivalence class of stochastic processes with the same marginal density function f(x,t). All these processes provide suitable stochastic models for the starting equation. Studying the ggBm, we just focused on a subclass made up of processes with stationary increments. The ggBm has been defined canonically in the so called grey noise space. However, we have been able to provide a characterization notwithstanding the underline probability space. We also pointed out that that the generalized grey Brownian motion is a direct generalization of a Gaussian process and in particular it generalizes Brownain motion and fractional Brownain motion as well. Finally, we introduced and analyzed a more general class of diffusion type equations related to certain non-Markovian stochastic processes. We started from the forward drift equation, which have been made non-local in time by the introduction of a suitable chosen memory kernel K(t). The resulting non-Markovian equation has been interpreted in a natural way as the evolution equation of the marginal density function of a random time process l(t). We then consider the subordinated process Y(t)=X(l(t)) where X(t) is a Markovian diffusion. The corresponding time-evolution of the marginal density function of Y(t) is governed by a non-Markovian Fokker-Planck equation which involves the same memory kernel K(t). We developed several applications and derived the exact solutions. Moreover, we considered different stochastic models for the given equations, providing path simulations.

Study of silicon-on-insulator multiple-gate MOS structures including band-gap engineering and self heating effects

The progresses of electron devices integration have proceeded for more than 40 years following the well–known Moore’s law, which states that the transistors density on chip doubles every 24 months. This trend has been possible due to the downsizing of the MOSFET dimensions (scaling); however, new issues and new challenges are arising, and the conventional ”bulk” architecture is becoming inadequate in order to face them. In order to overcome the limitations related to conventional structures, the researchers community is preparing different solutions, that need to be assessed. Possible solutions currently under scrutiny are represented by: • devices incorporating materials with properties different from those of silicon, for the channel and the source/drain regions; • new architectures as Silicon–On–Insulator (SOI) transistors: the body thickness of Ultra-Thin-Body SOI devices is a new design parameter, and it permits to keep under control Short–Channel–Effects without adopting high doping level in the channel. Among the solutions proposed in order to overcome the difficulties related to scaling, we can highlight heterojunctions at the channel edge, obtained by adopting for the source/drain regions materials with band–gap different from that of the channel material. This solution allows to increase the injection velocity of the particles travelling from the source into the channel, and therefore increase the performance of the transistor in terms of provided drain current. The first part of this thesis work addresses the use of heterojunctions in SOI transistors: chapter 3 outlines the basics of the heterojunctions theory and the adoption of such approach in older technologies as the heterojunction–bipolar–transistors; moreover the modifications introduced in the Monte Carlo code in order to simulate conduction band discontinuities are described, and the simulations performed on unidimensional simplified structures in order to validate them as well. Chapter 4 presents the results obtained from the Monte Carlo simulations performed on double–gate SOI transistors featuring conduction band offsets between the source and drain regions and the channel. In particular, attention has been focused on the drain current and to internal quantities as inversion charge, potential energy and carrier velocities. Both graded and abrupt discontinuities have been considered. The scaling of devices dimensions and the adoption of innovative architectures have consequences on the power dissipation as well. In SOI technologies the channel is thermally insulated from the underlying substrate by a SiO2 buried–oxide layer; this SiO2 layer features a thermal conductivity that is two orders of magnitude lower than the silicon one, and it impedes the dissipation of the heat generated in the active region. Moreover, the thermal conductivity of thin semiconductor films is much lower than that of silicon bulk, due to phonon confinement and boundary scattering. All these aspects cause severe self–heating effects, that detrimentally impact the carrier mobility and therefore the saturation drive current for high–performance transistors; as a consequence, thermal device design is becoming a fundamental part of integrated circuit engineering. The second part of this thesis discusses the problem of self–heating in SOI transistors. Chapter 5 describes the causes of heat generation and dissipation in SOI devices, and it provides a brief overview on the methods that have been proposed in order to model these phenomena. In order to understand how this problem impacts the performance of different SOI architectures, three–dimensional electro–thermal simulations have been applied to the analysis of SHE in planar single and double–gate SOI transistors as well as FinFET, featuring the same isothermal electrical characteristics. In chapter 6 the same simulation approach is extensively employed to study the impact of SHE on the performance of a FinFET representative of the high–performance transistor of the 45 nm technology node. Its effects on the ON–current, the maximum temperatures reached inside the device and the thermal resistance associated to the device itself, as well as the dependence of SHE on the main geometrical parameters have been analyzed. Furthermore, the consequences on self–heating of technological solutions such as raised S/D extensions regions or reduction of fin height are explored as well. Finally, conclusions are drawn in chapter 7.

Percezione della direzione del proprio movimento: dalla registrazione dell'attività corticale al modello computazionale.

The main aim of this thesis is strongly interdisciplinary: it involves and presumes a knowledge on Neurophysiology, to understand the mechanisms that undergo the studied phenomena, a knowledge and experience on Electronics, necessary during the hardware experimental set-up to acquire neuronal data, on Informatics and programming to write the code necessary to control the behaviours of the subjects during experiments and the visual presentation of stimuli. At last, neuronal and statistical models should be well known to help in interpreting data. The project started with an accurate bibliographic research: until now the mechanism of perception of heading (or direction of motion) are still poorly known. The main interest is to understand how the integration of visual information relative to our motion with eye position information happens. To investigate the cortical response to visual stimuli in motion and the integration with eye position, we decided to study an animal model, using Optic Flow expansion and contraction as visual stimuli. In the first chapter of the thesis, the basic aims of the research project are presented, together with the reasons why it’s interesting and important to study perception of motion. Moreover, this chapter describes the methods my research group thought to be more adequate to contribute to scientific community and underlines my personal contribute to the project. The second chapter presents an overview on useful knowledge to follow the main part of the thesis: it starts with a brief introduction on central nervous system, on cortical functions, then it presents more deeply associations areas, which are the main target of our study. Furthermore, it tries to explain why studies on animal models are necessary to understand mechanism at a cellular level, that could not be addressed on any other way. In the second part of the chapter, basics on electrophysiology and cellular communication are presented, together with traditional neuronal data analysis methods. The third chapter is intended to be a helpful resource for future works in the laboratory: it presents the hardware used for experimental sessions, how to control animal behaviour during the experiments by means of C routines and a software, and how to present visual stimuli on a screen. The forth chapter is the main core of the research project and the thesis. In the methods, experimental paradigms, visual stimuli and data analysis are presented. In the results, cellular response of area PEc to visual stimuli in motion combined with different eye positions are shown. In brief, this study led to the identification of different cellular behaviour in relation to focus of expansion (the direction of motion given by the optic flow pattern) and eye position. The originality and importance of the results are pointed out in the conclusions: this is the first study aimed to investigate perception of motion in this particular cortical area. In the last paragraph, a neuronal network model is presented: the aim is simulating cellular pre-saccadic and post-saccadic response of neuron in area PEc, during eye movement tasks. The same data presented in chapter four, are further analysed in chapter fifth. The analysis started from the observation of the neuronal responses during 1s time period in which the visual stimulation was the same. It was clear that cells activities showed oscillations in time, that had been neglected by the previous analysis based on mean firing frequency. Results distinguished two cellular behaviour by their response characteristics: some neurons showed oscillations that changed depending on eye and optic flow position, while others kept the same oscillations characteristics independent of the stimulus. The last chapter discusses the results of the research project, comments the originality and interdisciplinary of the study and proposes some future developments.

Development of synthetic molecular circuits for the control of cell systems

Synthetic biology is a young field of applicative research aiming to design and build up artificial biological devices, useful for human applications. How synthetic biology emerged in past years and how the development of the Registry of Standard Biological Parts aimed to introduce one practical starting solution to apply the basics of engineering to molecular biology is presented in chapter 1 in the thesis The same chapter recalls how biological parts can make up a genetic program, the molecular cloning tecnique useful for this purpose, and an overview of the mathematical modeling adopted to describe gene circuit behavior. Although the design of gene circuits has become feasible the increasing complexity of gene networks asks for a rational approach to design gene circuits. A bottom-up approach was proposed, suggesting that the behavior of a complicated system can be predicted from the features of its parts. The option to use modular parts in large-scale networks will be facilitated by a detailed and shared characterization of their functional properties. Such a prediction, requires well-characterized mathematical models of the parts and of how they behave when assembled together. In chapter 2, the feasibility of the bottom-up approach in the design of a synthetic program in Escherichia coli bacterial cells is described. The rational design of gene networks is however far from being established. The synthetic biology approach can used the mathematical formalism to identify biological information not assessable with experimental measurements. In this context, chapter 3 describes the design of a synthetic sensor for identifying molecules of interest inside eukaryotic cells. The Registry of Standard parts collects standard and modular biological parts. To spread the use of BioBricks the iGEM competition was started. The ICM Laboratory, where Francesca Ceroni completed her Ph.D, partecipated with teams of students and Chapter 4 summarizes the projects developed.

Applicazioni industriali e di ricerca della spettroscopia NIR per la valutazione di indici qualitativi di prodotti alimentari

In the present work qualitative aspects of products that fall outside the classic Italian of food production view will be investigated, except for the apricot, a fruit, however, less studied by the methods considered here. The development of computer systems and the advanced software systems dedicated for statistical processing of data, has permitted the application of advanced technologies including the analysis of niche products. The near-infrared spectroscopic analysis was applied to the chemical industry for over twenty years and, subsequently, was applied in food industry with great success for non-destructive in line and off-line analysis. The work that will be presented below range from the use of spectroscopy for the determination of some rheological indices of ice cream applications to the characterization of the main quality indices of apricots, fresh dates, determination of the production areas of pistachio. Next to the spectroscopy will be illustrated different methods of multivariate analysis for spectra interpretation or for the construction of qualitative models of estimation. The thesis is divided into four separate studies that consider the same number of products. Each one of it is introduced by its own premise and ended with its own bibliography. This studies are preceded by a general discussion on the state of art and the basics of NIR spectroscopy.

La sostenibilità ambientale dal Progetto Edilizio al Piano Urbano: L'integrazione della variabile energetica nella pianificazione del territorio

La questione energetica ha assunto, negli ultimi anni, un ruolo centrale nel dibattito mondiale in relazione a quattro fattori principali: la non riproducibilità delle risorse naturali, l’aumento esponenziale dei consumi, gli interessi economici e la salvaguardia dell'equilibrio ambientale e climatico del nostro Pianeta. E’ necessario, dunque, cambiare il modello di produzione e consumo dell’energia soprattutto nelle città, dove si ha la massima concentrazione dei consumi energetici. Per queste ragioni, il ricorso alle Fonti Energetiche Rinnovabili (FER) si configura ormai come una misura necessaria, opportuna ed urgente anche nella pianificazione urbanistica. Per migliorare la prestazione energetica complessiva del sistema città bisogna implementare politiche di governo delle trasformazioni che escano da una logica operativa “edificio-centrica” e ricomprendano, oltre al singolo manufatto, le aggregazioni di manufatti e le loro relazioni/ interazioni in termini di input e output materico-energetiche. La sostituzione generalizzata del patrimonio edilizio esistente con nuovi edifici iper-tecnologici, è improponibile. In che modo quindi, è possibile ridefinire la normativa e la prassi urbanistica per generare tessuti edilizi energeticamente efficienti? La presente ricerca propone l’integrazione tra la nascente pianificazione energetica del territorio e le più consolidate norme urbanistiche, nella generazione di tessuti urbani “energy saving” che aggiungano alle prestazioni energetico-ambientali dei singoli manufatti quelle del contesto, in un bilancio energetico complessivo. Questo studio, dopo aver descritto e confrontato le principali FER oggi disponibili, suggerisce una metodologia per una valutazione preliminare del mix di tecnologie e di FER più adatto per ciascun sito configurato come “distretto energetico”. I risultati di tale processo forniscono gli elementi basilari per predisporre le azioni necessarie all’integrazione della materia energetica nei Piani Urbanistici attraverso l’applicazione dei principi della perequazione nella definizione di requisiti prestazionali alla scala insediativa, indispensabili per un corretto passaggio alla progettazione degli “oggetti” e dei “sistemi” urbani.

Progettualità e interventi educativi nella dislessia. Il progetto ProDSA e le prospettive future di ricerca.

Il presente lavoro è strutturato in quattro parti analizzando e comparando le pubblicazioni del settore scientifico italiano, anglofono e tedesco di riferimento. Nel primo capitolo della tesi viene proposta una riflessione sulle parole che ruotano attorno al tema dei DSA e della disabilità. Nel secondo capitolo vengono presentati, a partire dalla letteratura scientifica di riferimento, gli indicatori di rischio che segnalano possibili disturbi specifici di apprendimento e le caratteristiche di apprendimento dei DSA mettendo in luce potenzialità e talenti spesso intrinseci. Nel terzo capitolo viene vagliata la normativa di riferimento, in particolare la recente Legge 170/2010 e le relative Linee Guida. Nel quarto capitolo, partendo dal tema della diffusione delle tecnologie dell’informazione e della comunicazione (da ora in poi TIC) nel mondo della scuola, sono ampiamente trattati i principali strumenti compensativi (sintesi vocale, libri digitali, mappe concettuali, Lavagna Interattiva Multimediale) e le misure dispensative adottabili. Nel quinto capitolo viene analizzato in tutte le sue parti il Piano Didattico Personalizzato (da ora in poi PDP) e viene proposto un possibile modello di PDP pubblicato sul sito dell'Ufficio per l’Ambito Territoriale di Bologna. Nel sesto capitolo della tesi viene presentato il Progetto Regionale ProDSA. Il Progetto, rivolto a studenti, con diagnosi di DSA, delle scuole secondarie di primo grado e del primo biennio delle secondarie di secondo grado dell’Emilia-Romagna, ha visto, grazie a un finanziamento della Regione, la consegna in comodato d'uso gratuito di tecnologie compensative agli alunni che hanno aderito. La sezione empirica del presente lavoro indaga l’uso reale che è stato fatto degli strumenti proposti in comodato d’uso e le motivazioni legate alla scelta di non utilizzarli in classe. Nel settimo capitolo vengono proposti strumenti progettati per rispondere concretamente alle criticità emerse dall'analisi dei dati e per sensibilizzare il mondo della scuola sulle caratteristiche dei DSA.

Il rogo degli eretici nel Medioevo

Il presente lavoro mette in luce i diversi aspetti che ruotano intorno all’istituzione del rogo, cioè la condanna di un eretico alle fiamme e la conseguente morte per vivicombustione, che arrivò a imporsi nella procedura inquisitoriale come punizione ultima e unica nei casi di eresia. La prima parte del lavoro è dedicata ai fondamenti giuridici che caratterizzano questa pena. L’attenzione è rivolta poi alla letteratura controversistica di parte cattolica, usata dalla Chiesa a difesa della legittima occisio degli eretici. La parte centrale dello studio riguarda l’aspetto storico con una recensio dei principali roghi avvenuti prima e dopo la nascita dell’Inquisizione. Infine la riflessione si sposta sulla scelta e il significato di tale pena da un punto di vista antropologico.

Design and experimental characterization of antennas and wireless systems for innovative wearable and implantable ultra low–power applications

The present PhD thesis exploits the design skills I have been improving since my master thesis’ research. A brief description of the chapters’ content follows. Chapter 1: the simulation of a complete front–end is a very complex problem and, in particular, is the basis upon which the prediction of the overall performance of the system is possible. By means of a commercial EM simulation tool and a rigorous nonlinear/EM circuit co–simulation based on the Reciprocity Theorem, the above–mentioned prediction can be achieved and exploited for wireless links characterization. This will represent the theoretical basics of the entire present thesis and will be supported by two RF applications. Chapter 2: an extensive dissertation about Magneto–Dielectric (MD) materials will be presented, together with their peculiar characteristics as substrates for antenna miniaturization purposes. A designed and tested device for RF on–body applications will be described in detail. Finally, future research will be discussed. Chapter 3: this chapter will deal with the issue regarding the exploitation of renewable energy sources for low–energy consumption devices. Hence the problem related to the so–called energy harvesting will be tackled and a first attempt to deploy THz solar energy in an innovative way will be presented and discussed. Future research will be proposed as well. Chapter 4: graphene is a very promising material for devices to be exploited in the RF and THz frequency range for a wide range of engineering applications, including those ones marked as the main research goal of the present thesis. This chapter will present the results obtained during my research period at the National Institute for Research and Development in Microtechnologies (IMT) in Bucharest, Romania. It will concern the design and manufacturing of antennas and diodes made in graphene–based technology for detection/rectification purposes.