Campionamento e determinazione di sostanze rilevanti per la valutazione della capacità ossidante dell’atmosfera e studio del loro effetto sui materiali ceramici

Carbonyl compounds are very important volatil organic compounds receiving increasing attention due to their critical role in tropospheric organic chemistry and to their effects on human health. They are first photo-oxidation stage of almost all organic compounds and originators of free radicals (OH, O3...). Therfore, continuous determination of their atmospheric concentrations is essential. Currently, field measurements are very limited mainly because of the analytical challenges posed by trace concentrations and interferences arising from atmospheric co-pollutants. Additionally, hydroxyl radical (OH) plays a central role in atmospheric chemistry processes. The measurement of atmospheric OH concentrations is essential for the comprehension of atmospheric chemical and photochemical processes. In this context, objectives of this work were: To perform a continuous survey of atmospheric concentrations of carbonyl compounds on different sites around the area of Bologna. For this purpose, an automatic instrument for the continuous measurement (one hour of time resolution) was developed and used. Additionally, the development of a complete and original analytical method was realised. To develop an original OH generation system in order to evaluate the effect of OH and the reactivity of solid and/or liquid materials of interest. This included the validation of an analytical method for the quantification of OH concentrations generated. Effect of OH on ceramic materials and reactivity of snow surface samples, involved as sink of OH in atmospheric chemistry, were evaluated.

Magnetic fields around radio galaxies from Faraday rotation measure analysis

The purpose of this thesis is to investigate the strength and structure of the magnetized medium surrounding radio galaxies via observations of the Faraday effect. This study is based on an analysis of the polarization properties of radio galaxies selected to have a range of morphologies (elongated tails, or lobes with small axial ratios) and to be located in a variety of environments (from rich cluster core to small group). The targets include famous objects like M84 and M87. A key aspect of this work is the combination of accurate radio imaging with high-quality X-ray data for the gas surrounding the sources. Although the focus of this thesis is primarily observational, I developed analytical models and performed two- and three-dimensional numerical simulations of magnetic fields. The steps of the thesis are: (a) to analyze new and archival observations of Faraday rotation measure (RM) across radio galaxies and (b) to interpret these and existing RM images using sophisticated two and three-dimensional Monte Carlo simulations. The approach has been to select a few bright, very extended and highly polarized radio galaxies. This is essential to have high signal-to-noise in polarization over large enough areas to allow computation of spatial statistics such as the structure function (and hence the power spectrum) of rotation measure, which requires a large number of independent measurements. New and archival Very Large Array observations of the target sources have been analyzed in combination with high-quality X-ray data from the Chandra, XMM-Newton and ROSAT satellites. The work has been carried out by making use of: 1) Analytical predictions of the RM structure functions to quantify the RM statistics and to constrain the power spectra of the RM and magnetic field. 2) Two-dimensional Monte Carlo simulations to address the effect of an incomplete sampling of RM distribution and so to determine errors for the power spectra. 3) Methods to combine measurements of RM and depolarization in order to constrain the magnetic-field power spectrum on small scales. 4) Three-dimensional models of the group/cluster environments, including different magnetic field power spectra and gas density distributions. This thesis has shown that the magnetized medium surrounding radio galaxies appears more complicated than was apparent from earlier work. Three distinct types of magnetic-field structure are identified: an isotropic component with large-scale fluctuations, plausibly associated with the intergalactic medium not affected by the presence of a radio source; a well-ordered field draped around the front ends of the radio lobes and a field with small-scale fluctuations in rims of compressed gas surrounding the inner lobes, perhaps associated with a mixing layer.

The gaseous environment of radio galaxies: a new perspective from high-resolution x-ray spectroscopy

It is known that massive black holes have a profound effect on the evolution of galaxies, and possibly on their formation by regulating the amount of gas available for the star formation. However, how black hole and galaxies communicate is still an open problem, depending on how much of the energy released interacts with the circumnuclear matter. In the last years, most studies of feedback have primarily focused on AGN jet/cavity systems in the most massive galaxy clusters. This thesis intends to investigate the feedback phenomena in radio--loud AGNs from a different perspective studying isolated radio galaxies, through high-resolution spectroscopy. In particular one NLRG and three BLRG are studied, searching for warm gas, both in emission and absorption, in the soft X-ray band. I show that the soft spectrum of 3C33 originates from gas photoionized by the central engine. I found for the first time WA in 3C382 and 3C390.3. I show that the observed warm emitter/absorbers is not uniform and probably located in the NLR. The detected WA is slow implying a mass outflow rate and kinetic luminosity always well below 1% the L(acc) as well as the P(jet). Finally the radio--loud properties are compared with those of type 1 RQ AGNs. A positive correlation is found between the mass outflow rate/kinetic luminosity, and the radio loudness. This seems to suggest that the presence of a radio source (the jet?) affects the distribution of the absorbing gas. Alternatively, if the gas distribution is similar in Seyferts and radio galaxies, the M(out) vs rl relation could simply indicate a major ejection of matter in the form of wind in powerful radio AGNs.

Analisi di modelli teorico-empirici di capacità per le intersezioni a rotatoria

In questa tesi di laurea si affronta l’analisi di diversi modelli per il calcolo della capacità di un’intersezione a rotatoria: alcuni di questi sono di tipo empirico, altri invece sono di tipo teorico (teoria del gap acceptance). Innanzitutto si descrivono le caratteristiche di tutti i modelli studiati e si esaminano i risultati ottenuti nel calcolo della capacità al variare del flusso circolante, effettuato su un campione di venti rotatorie. In particolare si cerca di confrontare tra loro i vari modelli e di interpretare il significato dei parametri che compaiono nelle diverse formule. Successivamente si amplia l’analisi, utilizzando i dati raccolti come punto di partenza per una serie di altre elaborazioni ed interpolazioni. Alla base di questa seconda parte dello studio c’è l’idea di provare a vedere se sia possibile ricavare un nuovo modello, derivante da quelli studiati, che possa riassumerli in maniera semplice e aiutare a chiarire quali sono i parametri più importanti dai quali dipende il valore di capacità di una rotatoria. Questo nuovo modello dovrebbe eventualmente servire più che altro per interpretare i modelli studiati e per capire se uno di questi si comporti meglio degli altri in situazioni particolari oppure se sia più adatto in determinate condizioni di traffico piuttosto che in altre. Uno degli obiettivi principali di questo studio è infatti quello di provare a capire se la capacità di una rotatoria è influenzata maggiormente da aspetti geometrici, legati quindi alla forma e alle dimensioni della rotatoria stessa, oppure se un ruolo predominante è svolto da fattori comportamentali, legati quindi all’interazione tra i veicoli e ai processi di scelta degli utenti, che devono decidere se immettersi o meno nella rotatoria.

Il deperimento dei geomateriali da costruzione: implicazioni sulla capacità sismica residua di edifici in CA e muratura ordinaria

This work is dedicated to the study of damaging phenomena involving reinforced concrete structures and masonry buildings and the consequences in terms of structural performances decay. In the Italian context there are many examples of structures that have already exceeded their service life, considering not only the ancient buildings but also infrastructures and R/C buildings that today are operating from more than 50th years. Climate change which is subject to the entire planet, with changing in seasonal weather and increasing in environmental pollution, is not excluded could have a harmful influence on the rate of building materials decay previously deemed as durables. If the aggressive input changes very fast, for example in a few decades, then it can also change the response of a construction material considered so far durable; in this way the knowledge about the art of good build, consolidated over the centuries, is thwarted. Hence this study is focused on the possibility to define the residual capacity for vertical or seismic loads for structures that are already at the limit of their service life, or for which is impossible to define a service life. The problem in an analysis of this kind, and that is what makes this research different from the main studies avaibles in the literature, is to keep in correlation – in a not so expensive computationally way – issues such as: - dangerous environmental inputs adequately simulated; - environmental conditions favorable to the spread of pollutants and development of the degradation reactions (decay’s speed); - link between environmental degradation and residual bearing capacity A more realistic assessment of materials residual performances that constitute the structure allows to leave the actual system for the residual load-bearing capacity estimation in which all factors are simply considered through the use of a safety factor on the materials properties.

Sviluppo di un metodo elettrochimico per la determinazione della capacità antiossidante

The aim of the present thesis, carried out at the Analytical Group of the Faculty of Industrial Chemistry in Bologna, is to develop a new electrochemical method for the determination of the Antioxidant Capacity (AOC). The approach is based on the deposition of a non-conducting polymeric film on the working electrode surface and the following exposition to the radicals OH· produced by H2O2 photolysis. The strongly oxidant action of hydroxyl radicals degrades, causing an increase of the Faradic current, relevant to the redox couple [Ru(NH3)6]2+/3+ monitored by cyclic voltammetry(CV); the presence of an antioxidant compound in solution slows down the radical action, thus protecting the polymeric film and blocking the charge transfer. The parameter adopted for the quantification of the AOC, was the induction time, called also lag phase, which is the time when the degradation of the film starts. Five pure compounds, among most commonly antioxidant, were investigated : Trolox®(an analogue water-soluble of vitamin E), (L)-ascorbic acid, gallic acid, pyrogallol and (-)- epicatechin. The AOC of each antioxidant was expressed by TEAC index (Trolox® Equivalent Antioxidant Capacity), calculated from the ratio between the slope of the calibration curve of the target compound and the slope of the calibration curve of Trolox®. The results from the electrochemical method, have been compared with those obtained from some other standardized methods, widely employed. The assays used for the comparison, have been: ORAC, a spectrofluorimetric method based on the decrease of fluorescein emission after the attack of alkylperoxide radicals, ABTS and DPPH that exploit the decoloration of stable nitrogen radicals when they are reduced in presence of an antioxidant compound and, finally, a potentiometric method based on the response of the redox couple [Fe(CN)6]3-/ [Fe(CN)6]4-. From the results obtained from pure compounds, it has been found that ORAC is the methodology showing the best correlation with the developed electrochemical method, maybe since similar radical species are involved. The comparison between the considered assays, was also extended to the analysis of a real sample of fruit juice. In such a case the TEAC value resulting from the electrochemical method is higher than those from standardized assays.

Progettazione e implementazione di applicazioni context-aware su dispositivi mobili

Il progetto descritto in questo documento consiste fondamentalmente nell'integrazione di applicazioni context-aware su dispositivi mobili con reti di sensori e nello studio delle problematiche derivanti, vantaggi e potenziali utilizzi. La rete è stata costruita sfruttando l'insieme di protocolli per comunicazioni via radio Zigbee, particolarmente adatti per interazione tra dispositivi a basso consumo energetico e che necessitano di uno scarso tasso di trasferimento di dati. Le informazioni ottenute da sensori di varia natura sono processate da microcontrollori Arduino, scelti per la loro versatilità di utilizzo e design open source. Uno o più dispositivi sono designati per aggregare i dati rilevati dai singoli nodi in un unico pacchetto di informazioni, semanticamente correlate tra loro, quindi emetterle in broadcast su una diversa interfaccia di rete, in modo che diverse applicazioni esterne in ascolto possano riceverle e manipolarle. Viene utilizzato un protocollo specifico per la comunicazione tra i microcontrollori e le applicazioni che si interfacciano con la rete, costruito su misura per dispositivi con risorse limitate. L'applicazione context-aware che interagisce con la rete è stata sviluppata su piattaforma Android, la cui particolare flessibilità favorisce una migliore capacità di gestire i dati ottenuti. Questa applicazione è in grado di comunicare con la rete, manipolare i dati ricevuti ed eventualmente intraprendere azioni specifiche in totale indipendenza dal suo utilizzatore. Obiettivo del progetto è quello di costruire un meccanismo di interazione tra le tecnologie più adattivo e funzionale possibile.

Origin and Nature of Radio-Loud Broad Absorption Line Quasars

The origin of Broad Absorption Line Quasars (BAL QSOs) is still an open issue. Accounting for ~20% of the QSO population, these objects present broad absorption lines in their optical spectra generated from outflows with velocities up to 0.2 c. Nowadays, the hypotheses about their nature are principally related to orientation or evolutionary scenarios. In the first one, absorption lines are produced by outflows originated by the accretion disk, basically present in all QSOs, but seen only when they intercept the line of sight. In the second hypothesis, BAL QSOs would be young or recently re-fueled QSOs, still ejecting their dust cocoon. In this case orientation would not play a role, since the absorption features would be produced by spherically ejected matter. In this work we present the results of a multi-frequency study of a Radio-Loud BAL QSO sample, and a comparison sample of Radio-Loud non-BAL QSOs. We performed observations from radio to Near-Infrared, aiming at collecting useful informations about the orientation, the age, and the morphologies of these objects. Various techniques have been applied, including local and continental radio interferometry, single dish observations and spectroscopy. The comparison with the non-BAL QSO sample allows us to conclude that no particular orientation is present in BAL QSOs. Moreover, various morphologies and ages can be found, analogously to "normal" QSOs. Thus, the solution to this astrophysical problem seems not to reside in a peculiarity of the BAL QSO subclass with respect to non-BAL QSOs, since both the studied models do not completely explain the observed characteristics. Further experiments with future instrumentation will allow us to underline useful differences and test the physical conditions in BAL QSOs.

Fistola Artero-venosa Radio-Cefalica Distale per Emodialisi nel paziente anziano: Valutazione dei risultati ottenuti con l'utilizzo della Tecnica Microchirurgica

PREMESSA: Le linee guida raccomandano la fistola AV radio-cefalica autogena (RCAVF)come prima scelta per l'emodialisi. Preoccupazione è stata sollevata che questo potrebbe non essere appropriato nei pazienti anziani. METODO: Noi abbiamo seguito in modo prospettico 126 pazienti per tre anni. Dopo sistematica valutazione clinica ed ecografica, la RCAVF è stata creata utilizzando un microscopio operatore. La pervietà è stata valutata subito, a 1 settimana, a 1 mese e a 1 anno. I risultati sono stati registrati e stratificati in 2 gruppi: <70a e > 70a. RISULTATI: La RCAVF è stata creata nel 75% dei <70a e nel 70% dei >70a. L'incidenza di insuccesso immediato è stata 11% (<70a) e 13% (>70a). La pervietà primaria e secondaria ad 1 anno è stata 67% e 84% (<70a), 63% e 80% (>70a). CONCLUSIONI: La microchirurgia ha permesso la creazione di RCVAF in >70a con un rischio accettabile di fallimento e lievi differenze rispetto a <70a. L'età non deve precludere una creazione di RCAVF.

Innovative architecture of on-board and on-ground radio systems for space communication

The radio communication system is one of the most critical system of the overall satellite platform: it often represents the only way of communication, between a spacecraft and the Ground Segment or among a constellation of satellites. This thesis focuses on specific innovative architectures for on-board and on-ground radio systems. In particular, this work is an integral part of a space program started in 2004 at the University of Bologna, Forlì campus, which led to the completion of the microsatellite ALMASat-1, successfully launched on-board the VEGA maiden flight. The success of this program led to the development of a second microsatellite, named ALMASat-EO, a three-axis stabilized microsatellite able to capture images of the Earth surface. Therefore, the first objective of this study was focused on the investigation of an innovative, efficient and low cost architecture for on-board radio communication systems. The TT&C system and the high data rate transmitter for images downlink design and realization are thoroughly described in this work, together with the development of the embedded hardware and the adopted antenna systems. Moreover, considering the increasing interest in the development of constellations of microsatellite, in particular those flying in close formations, a careful analysis has been carried out for the development of innovative communication protocols for inter-satellite links. Furthermore, in order to investigate the system aspects of space communications, a study has been carried out at ESOC having as objective the design, implementation and test of two experimental devices for the enhancement of the ESA GS. Thus, a significant portion of this thesis is dedicated to the description of the results of a method for improving the phase stability of GS radio frequency equipments by means of real-time phase compensation and a new way to perform two antennas arraying tracking using already existing ESA tracking stations facilities.