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Studio strutturale, analisi computazionale e correlazione struttura-proprietà in elettroliti a conduzione anionica per celle a combustibile
No full textA combined experimental and theoretical approach has been used in order to investigate the local structural features that have an influence on ionic conductivity of IT-SOFC (Intermediate Temperature Solid Oxide Fuel Cell) electrolytes, in order to link the properties of these materials with their atomic and electronic structure.
Doped delta-Bi2O3 and LaGaO3 electrolytes for AC-SOFC applications have been studied as model compounds for oxygen-ion diffusion in fluorite-like and perovskite-like materials, due to their incredibly high anion conductivity. A combined X-Ray Absorption Spectroscopy (XAS) and Density Functional Theory (DFT) study has been carried out with the aim to unveil the role of the dopants on the short range structure of these materials, to probe the preferential association of vacancies with both dopant and regular site cations, and to highlight the preferential oxygen-ion diffusion paths. This could help to define criteria for the design of new materials with improved properties.
The influence of the electrode-electrolyte interface on the overall fuel cell ionic conductivity has been also addressed. To this aim, a novel protocol to evaluate electrode-electrolyte compatibility through Scanning X-Ray Microscopy (SXM) has been developed and cation interdiffusion has been successfully probed at the interface between some electrolyte-cathode couples
Polymorphisms at lipogenic loci in interaction with feeding systems: effects on milk traits
No full textSicily has one of the richest heritages of animal biodiversity of Italy. The dairy sector is characterized by many typical products, often related to breeds and indigenous cows, to feeding techniques that make extensive use of grazing and traditional cheese-making techniques. Dairy cattle breeds have been subjected to an intensive selection towards improvement of milk production traits. Milk composition is very variable, being conditioned by the complex metabolic activity linked to individual variability of animals, to nutritional and environmental factors.
In the present study, it was investigated for the first time in Modicana breed, novel information about polymorphisms at key genes involved in lipid metabolism and interaction between these polymorphisms and the feeding systems. It was studied how the presence of pasture in the diet can interfere with the effects of polymorphisms at the studied loci on milk yield, gross composition and fatty acid profile.
Modicana cows reared in two farms of the Ragusa province with an extensive and semi-intensive system were characterized under the genetic profile for the lipogenic polymorphisms (ABCG2-Y581S, DGAT1-K232A, STAT5A-V686A, SCD1-A293V). Subsequently, on the basis of the genotypes detected, 36 and 38 cows were selected from the semi-intensive and extensive systems, respectively. From these animals, individual phenotypic data were collected relative to productivity, milk composition, fatty acid profile and mineral composition, in order to evaluate the effect of the genetic polymorphisms and interaction with feeding systems on the quantitative and qualitative characteristics of milk.
The entire population resulted monomorphic at ABCG2 Y581S polymorphism while for the other loci the allele with higher frequency were: 91% for GC (232A) at DGAT1, 68% for T (686V) at STAT5A and 73% for T (293A) at SCD1.
Feeding system influenced milk yield and protein content that resulted higher in animals fed with natural pasture while, when feeding systems were considered in interaction with the polymorphisms, results do not allow to find significant differences within the different phenotypes in milk in both systems, extensive and semi-intensive.
Feeding system also affected milk FAs composition and animals reared in an extensive system, showed a lower content of SFA and a higher fraction of MUFA, PUFA and trans FAs. Then, considering the interaction between the feeding systems and the polymorphisms on milk FAs composition, results showed that some FAs were significant affected by this interaction. The DGAT1-K232A polymorphism in interaction with feeding system, affected the content of C4, CLA and C22:4. Milk of animals with DGAT1 GC/GC genotype (232A) and fed with pasture showed a higher content of CLA. The STAT5A-V686A polymorphism affected OBCFA composition, the content of which resulted higher in animals with TT genotype (686V). Animals with TT genotype showed also a higher content of C18:1t11, C18:1c9, C20:4 and C22:5n3 and a lower C20:5n3 content. No interaction has been detected between the identified genotypes and the feeding systems. The SCD1-A293V polymorphism in interaction with feeding systems affected the contents of C4, C6, C8, C18:1t11 and C20:3 that gradually decreased in animals reared in an extensive system from CC to heterozygous to TT genotype.
Finally, regarding mineral composition, the only significant effect was reported for the K content that was associated with STAT5A-V686A polymorphism and resulted higher in heterozygous animals.
This study described that relationship between the polymorphisms at lipogenic loci and feeding systems in Modicana cows affected some milk production traits but further research are required to describe and better understand the variations in milk traits, within and between the breeds, not only through a genetic or nutritional point of view but as a dynamic interaction between these two aspects
Dynamics of Periodic Stratified Shear Flows
No full textIn questa tesi studiamo le instabilità in fluidi stratificati laminari dove la stratificazione in densità ha un effetto stabilizzante. Nonostante l idea comune che la forza d Archimede abbia un effetto stabilizzante, in alcune circostanze tale stratificazione ha mostrato di poter indurre instabilità in fluidi altrimenti stabili. Qui studiamo due sistemi differenti e come la stratificazione in densità influenzi la stabilità delle loro soluzioni di equilibrio.
Nel primo caso consideriamo l analogo stratificato del flusso di Kolmogorov, il quale è stato ampiamente studiato e mostra la formazione di un ricco numero di stati al diminuire della viscosità del fluido. Conduciamo un raffinamento dell analisi di questa serie di transizioni che portano il sistema a stati caotici, mostrando l esistenza di stati finora non osservati e provando la natura caotica di soluzioni a grandi numeri di Reynolds.
Quindi confrontiamo questi risultati con la route to chaos di fluidi via via più stratificati e osserviamo che la stratificazione in densità non influenza le biforcazioni per numeri di Richardson inferiori di . Invece nuove dinamiche compaiono quando o maggiore. Osserviamo che il gradiente di densità stabilizzante aumenta i numeri di Reynolds critici necessari a innescare le transizioni di stato e sblocca nuovi stati che erano inaccessibili per la controparte non stratificata.
La seconda parte della tesi riguarda l analisi delle instabilità dovute a onde generate in corrispondenza di difetti nella densità di un fluido. Consideriamo un fluido composto da un numero di strati a differente densità sottoposto a un profilo di velocità laminare. Fluidi multi-stratificati sono strutture comuni in sistemi naturali come oceani e laghi. L elevato gradiente di densità fra ciascuno strato supporta la formazione di onde di interfaccia. Grazie al profilo di velocità laminare, queste onde possono interagire risuonando fra di loro e diventare instabili (Instabilità di Taylor-Caulfield - TCI). Il numero di queste interfacce fra uno strato e l altro permette un gran numero di interazioni fra le suddette onde che possono minare la stabilità di questo particolare sistema. In questo lavoro l obbiettivo principale è quello di studiare la suscettibilità di questo sistema alle TCI e analizzare la successiva evoluzione nonlineare del sistema. Nel limite di grandi lunghezze d onda, strutture debolmente nonlineari in un fluido debolmente stratificato, noi studiamo l innescarsi delle instabilità. Infine stati totalmente nonlineari vengono studiati numericamente nel limite di grandi lunghezze d onda e debole stratificazione di densità
L'atto di destinazione ex art. 2645-ter c.c. Profili ricostruttivi e prassi applicativa
No full textPorre l attenzione su una disposizione normativa a più di dieci anni dalla sua entrata in vigore può forse apparire insolito, specie se le mire siano quelle di apportare un contributo che non sia meramente ricognitivo dello stato dell arte.
Ciò sembrerebbe valere, a maggior ragione, per l art. 2645-ter c.c., disposizione che, tanto per i suoi oscuri natali quanto per le risposte che in tesi voleva fornire, si è resa protagonista di una copiosa letteratura, a tal punto da poter far ritenere superflua qualsivoglia ulteriore analisi.
Tuttavia, tali considerazioni non si sono rivelate del tutto persuasive, specie nella misura in cui i numerosi contributi scientifici reperibili in materia abbiano sovente sostenuto lo scardinamento di determinate categorie giuridiche concettuali.
In questo quadro di contesto, peraltro, notevole rilievo ha avuto il ruolo della giurisprudenza di merito, il cui lavoro si è rivelato propizio a riaccendere il dibattito specie sulla meritevolezza degli interessi consentendo così di mantenere un elevato livello di attenzione per la fattispecie. Inoltre, il contrasto, a tratti palese e ridondante, tra le posizioni espresse in dottrina e la giurisprudenza ha spinto, in ultima analisi, per una disamina dell atto di destinazione opponibile ai terzi che prendesse le proprie mosse dalla prospettiva delle situazioni giuridiche soggettive nascenti dall atto medesimo, ambito, quest ultimo, spesso lasciato nell ombra e non posto in correlazione a prescindere dalla tesi alla quale si aderisca con la natura del vincolo di destinazione.
Con queste premesse si è condotta un indagine che ha restituito la sensazione che la disposizione dell art. 2645-ter c.c., così come (confusamente) formulata e inquadrata all interno del sistema, non abbia, in definitiva, sovvertito i principi sui quali si fonda l ordinamento civilistico positivo. E si badi, ciò non deve sembrare un morboso attaccamento alla tradizione, anzi; si tratta molto più semplicemente di una presa di coscienza circa la necessità per il giurista di affidarsi (non solo nominalisticamente) a categorie e principi, pena il rischio di svuotare semanticamente il lemma ordinamento . Sicché, ove di quest ultimo si paventi una rivisitazione, essa non può risolversi in una confusa legislazione di matrice rimediale.
L impressione che si desta è che l art. 2645-ter c.c. abbia rappresentato, anziché un ammodernamento del Codice Civile, forse un misero rattoppo, confermando piuttosto la bontà delle categorie pre-esistenti
A Pathway to EMU: the SCORPIO Project
No full textWe are entering a golden age for radio astronomy. There are several new interferometers upcoming, whose characteristics, in terms of sensitivity, frequency coverage, angular and temporal resolution, field of view, will permit unprecedented deep observations. The most outstanding ones among them will be the Square Kilometre Array (SKA) and its precursors, such as the Australian SKA Pathfinder (ASKAP) and MeerKAT. Several surveys will be carried out, in continuum and spectral line. In particular we will have as continuum surveys the Evolutionary Map of the Universe (EMU), to be carried out with ASKAP, the MeerKAT International GigaHertz Tiered extra-galactic Exploration Survey (MIGHTEE) and the MeerKAT High Frequency Galactic Plane Survey (Meer-GAL), both to be carried out with MeerKAT. All this surveys will observe large regions of the sky at high sensitivity, providing a huge increase in known object. This thesis focuses on radio stars and the science that can be carried out with the new radio interferometers. Even if, in general, stars emit in radio a small fraction of their luminosity, at these wavelengths it is possible to trace different phenomena that is not possible to study by other means. Furthermore the Galaxy is optically thin in radio, then we can observe stars in the GP that we could not observe in the optical frequencies. Unfortunately, due to the faintness of stars in radio, the number of currently known radio stars is limited to a small sample. Furthermore, they have all been observed directly, not discovered in a blind survey. We want to know how many radio stars to expect from the new surveys and, to do that, we worked on two different approaches. In the theoretical approach, described in Chapter 3 of the thesis, we estimate the number of stars that belong to those spectral type that incorporates radio emitting classes, such as Magnetic Chemically Peculiar (MCP) stars, OB stars, Flare stars and RS CVn stars from the Besancon model (Robin et al., 2003), and, from this information, from the probability of a certain spectral type star to be a radio emitter, we estimate the total number of stars detected at different sensitivities. As reported in the conclusions, we expect about 250 000 stars in EMU and about 50 000 000 with SKA-1. For the observational approach, we started the Stellar Continuum Originating from Radio Physics In Ourgalaxy (SCORPIO). SCORPIO is a blind survey of a five square degree region of the Galactic Plane, carried out with ATCA at 2.1 GHz and designed with two major goals, a scientific and a technical one. First of all, we wanted to know how may stars per square degree we can detect in a blind survey and to collect as much information as possible about the radio emission. Secondly, we wanted to know how to address the issues that comes from a blind survey on a area of the Galactic Plane, such as issues due to the complex structures present in the GP; issues due to the presence of variable sources; issues due to the diffuse emission that dominate the GP; issues regarding the identification of different populations. The work on the SCORPIO project is described in Chapters 4, 5 and 6 of this thesis. In Chapter 4 we focused on the data reduction, analysing each step from the raw data to the final image. In Chapter 5 we described a way to discriminate the source classes, studying their emission mechanism through their spectral indices. We found out, comparing our work to the ATLAS survey, that, in the SCORPIO field, about 20 sources per square degree with a flux density greater than 1 mJy are Galactic. In Chapter 6 we show all the different images created during the process, showing their importance in the study of specific physical properties. We also described the H ii regions and the radio stars found in the field. On Chapter 7 we do a summary and present the results accomplished in the thesis and the planned future work
EXONIC VARIATION IN PARKINSON'S DISEASE
No full textParkinson's disease (PD) is one of the most common movement disorders worldwide, characterized by a profound and selective loss of dopaminergic neurons in the substantia nigra pars compacta. Treatments aimed at compensating dopamine deficit can alleviate the major motor symptoms and enhance the patients quality of life, but finally are not able to halt or slow down disease progression. Therefore, there is an urgent need to better understand the molecular mechanisms underlying the physiopathology of PD and to identify new biomarkers and new therapeutic targets.
The hypothesis addressed in this PhD thesis aims to decipher the structural variability of exonic regions in PD-linked genes and in their relative mRNA transcripts, in order to investigate if these perturbations have some effects on PD pathogenesis. Two major cellular events able to trigger exonic variations in both DNA and mRNA molecules will be examined: copy number variations and alternative splicing. Both mechanisms are well known to play a crucial role in PD onset and can modulate disease severity. An improved comprehension of exonic variability at both genomic and transcriptomic level may prompt new insights to understand the missing heritability and the variety of phenotypic outcomes in PD patients
In vitro physiological and pathophysiological models: dynamic expression of aquaporins.
No full textWater is the main component of biological fluids and a prerequisite of all organisms living. In 1987, Agre isolated a new integral membrane protein acting as a channel that mediates the water flux and uncharged solutes across biological membranes. This protein was called aquaporin1 and ever since its discovery, more than 300 homologues have been identified in animal, bacteria and plant. In human have been discovered 13 aquaporins (AQPs) isoform (AQP0-AQP12) widely distributed in various epithelia and endothelia where are important actors of fluid homeostasis in secretory and absorptive processes in response to an osmotic or pressure gradient. In the human brain nine aquaporin subtypes (AQP1, 2, 3, 4, 5, 7, 8, 9, and 11) have been recognized and partially characterized, but only three aquaporins (AQP1, 4, and 9) have been clearly identified in vivo. This discovery highlighted the concept of the important role of AQPs in all brain functions and of the dynamics of water molecules in the cerebral cortex. Additionally, AQPs relieved an important role in glial control and neuronal excitability, such as in brain structure and general development. However, a clearer understanding of specific function and distribution of water channels in adult or in development brain requires a more detailed elucidation. Some of these findings are limited from the complexity of direct investigation, inaccessibility of the neural tissue, and hence difficulty in obtaining a brain biopsy, until after the death of an individual. In this sense, several past and present in vitro models have been used to provide important clues about many processes, such as brain development, neurotoxicity, inflammation, pathogenic mechanisms of the diseases and potential pharmacological targets. In the Chapter I, we have reviewed some in vitro approaches used to investigate the mechanisms involved in Krabbe disease with particular regard to the cellular systems employed to study processes of inflammation, apoptosis and angiogenesis. In this study, we used some in vitro methods with the aim to update the knowledge on stem cells biology and to provide a relationship between aquaporins expression and cellular differentiation. In particular, we have analysed the differentiation of human mesenchymal stem cells from adipose tissue (AT-MSCs) into neural phenotypes and SH-SY5Y neuroblastoma cell line into physiological and pathophysiological dopaminergic neurons. In the Chapter II, we have reported the results of the expression of AQP1, 4, 7, 8 and 9 at 0, 14, and 28 days in AT-MSCs during the neural differentiation by immunocytochemistry, RT-PCR and Western blot analysis. Our studies demonstrated that AT-MSCs could be differentiated into neurons, astrocytes and oligodendrocytes, showing reactivity not only for the typical neural markers, but also for specific AQPs in dependence from differentiated cell type. Our data revealed that at 28 days AT-MSCs express AQP1, astrocytes AQP1, 4 and 7, oligodendrocytes AQP1, 4 and 8, and finally neurons AQP1 and 7. In the Chapter III, we have examined the possible involvement of AQPs in a Parkinson s disease-like cell model. For this purpose, we used SH-SY5Y cell line, differentiated in dopaminergic neurons with retinoic acid (RA) and phorbol 12-myristate 13-acetate (MPA) alone or in association. The vulnerability to dopaminergic neurotoxin 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) and H2O2 was evaluated and compared in all cell groups. We found that the vulnerability of cells was linked to dynamic changes of AQP4 and AQP9. The data described here provides fundamental insights on the biology of the human mesenchymal stem cells and significant evidences on the involvement of AQPs in a variety of physiological and pathophysiological processes. This suggests their possible application as markers, which may be helpful in diagnosing as well as in the understanding of neurodegenerative diseases for future therapeutic approaches
Phytosociological investigation on the thermo-chasmophilous vegetation of the Eastern Mediterranean territories
No full textIn this work, the chasmophilous plant communities of thermophilous type occurring in some countries of the East-Mediterranean area are examined. This study is based on numerous phytosociological relevés carried out especially in continental and insular stands of Greece, and also in Cyprus, Israel, Cyrenaica (Libya), Croatia and E-Italy. The data used for this investigation are represented by many unpublished relevés, as well as by literature ones, in part published in synoptical tables
Surface plasmon resonance imaging biosensors for the detection of pathogens and toxins in food
No full textThe detection of pathogens and toxins in food represents an essential requirement for food quality control. Standard methods for pathogen detection rely on laborious and time-consuming growth of pathogens in different culture media followed by biochemical or serological identification. Such methods often operate with poor sensitivity and selectivity. In recent years, efforts have been made to provide rapid, reliable and sensitive detection platforms for foodborne pathogens detection. The demand for more rapid, sensitive and accurate methods has been push forward by the implementation of the Hazard Analysis and Critical Control Points (HACCP) protocols. In this context, biosensing platforms provide promising alternatives for the detection of pathogens and toxins with good selectivity and sensitivity. In particular, optical biosensors based on Surface Plasmon Resonance Imaging (SPRI) are attractive because they allow the sensitive detection of analytes from food matrices in real-time. SPRI can assays crude samples without purification and can exploits antibodies or single-stranded DNA (ssDNA) probes for the specific detection of pathogens and toxins with high sensitivity.
My research activity has been aimed at developing SPRI biosensors able to detect pathogens and toxins in food matrices in a rapid, specific and sensitive way. In this perspective, specific oligonucleotide sequences and antibodies have been used for the detection of DNA and bacterial toxins, respectively. SPRI biosensor sensitivity benefited of the use of properly functionalized gold nanoparticles (AuNPs). The combination of the SPRI sensing apparatus with microfluidics devices reduces the amount of sample needed for the analysis and provides an efficient environment for the detection
Modeling and analysis of epidemic spreading in mobile agents
No full textEvery day humans have to face with different kinds of diseases; from the most common one, the flu, to others more dangerous for our lives, like the EBOLA virus or the AIDS that fill us with dread. The spread of the epidemic through a population can be explosive or can remain in a steady state over long time periods. The way the illness propagates not only depends on the disease parameters but also on the structure of the network of the populations. This thesis focuses on two different aspects of the epidemic spreading: the first one is to find a low-dimensional representation of a large epidemic dataset by using a dimensionality reduction algorithm, the second one is to find a numerical computation of the epidemic threshold by considering a mobile-agent based model. Regarding the first topic, the dimensionality reduction method considered was the isometric features mapping (ISOMAP), a nonlinear dimensionality reduction method that overcomes the limitations provided by other methods attempting to reduce the order of the representation and gives the possibility to recognize the macroscopic behaviour of the epidemics thanks to the low dimensional embedding provided. This low-dimensional description of epidemic spreading is expected to improve our understanding of the role of individual response on the outbreak dynamics, inform the selection of meaningful global observables, and, possibly, aid in the design of control and quarantine procedures. Hence, in other words, the questions that this thesis wants to answer about this problem are: "What ISOMAP is able to do for epidemic description?", "There exists a relationship among embedded points and the process parameters?", "What we can expect from the obtained representation?".Concerning the second issue, the main idea was to find a link between epidemic spreading (obtained by simulating a mobile-agent based model with time-varying interactions) and the time-varying network of interactions. Thus, the non-trivial problem is to understand if it is possible to estimate the epidemic threshold from the time-varying network properties. To this aim, the method used in this thesis is based on the percolation theory; this approach was already used in order to associate the epidemic threshold to the percolation threshold but considering an activity-driven network (often used to study epidemic spreading models) or a static network. In this work instead it is faced the case of mobile agents models