I dati metereologici per applicazioni energetiche e ambientali

Many energetic and environmental evaluations need appropriate meteorological data, as input to analysis and prevision softwares. In Italy there aren't adeguate meteorological data because, in many cases, they are incomplete, incorrect and also very expensive for a long-term analysis (that needs multi-year data sets). A possible solution to this problem is the use of a Typical Meteorological Year (TRY), generated for specific applications. Nowadays the TRYs have been created, using statistical criteria, just for the analysis of solar energy systems and for predicting the thermal performance of buildings, applying it also to the study of photovoltaic plants (PV), though not specifically created for this type of application. The present research has defined the methodology for the creation of TRYs for different applications. In particular TRYs for environmental and wind plant analysis have been created. This is the innovative aspect of this research, never explored before. In additions, the methodology of the generation for the PV TRYs has been improved. The results are very good and the TRYs generated for these applications are adeguate to characterize the climatic condition of the place over a long period and can be used for energetic and environmental studies.

Caratterizzazione di membrane metalliche e ionomeriche per applicazioni energetiche

The work of this thesis has been focused on the characterization of metallic membranes for the hydrogen purification from steam reforming process and also of perfluorosulphonic acid ionomeric (PFSI) membranes suitable as electrolytes in fuel cell applications. The experimental study of metallic membranes was divided in three sections: synthesis of palladium and silver palladium coatings on porous ceramic support via electroless deposition (ELD), solubility and diffusivity analysis of hydrogen in palladium based alloys (temperature range between 200 and 400 °C up to 12 bar of pressure) and permeation experiments of pure hydrogen and mixtures containing, besides hydrogen, also nitrogen and methane at high temperatures (up to 600 °C) and pressures (up to 10 bar). Sequential deposition of palladium and silver on to porous alumina tubes by ELD technique was carried out using two different procedures: a stirred batch and a continuous flux method. Pure palladium as well as Pd-Ag membranes were produced: the Pd-Ag membranes’ composition is calculated to be close to 77% Pd and 23% Ag by weight which was the target value that correspond to the best performance of the palladium-based alloys. One of the membranes produced showed an infinite selectivity through hydrogen and relatively high permeability value and is suitable for the potential use as a hydrogen separator. The hydrogen sorption in silver palladium alloys was carried out in a gravimetric system on films produced by ELD technique. In the temperature range inspected, up to 400°C, there is still a lack in literature. The experimental data were analyzed with rigorous equations allowing to calculate the enthalpy and entropy values of the Sieverts’ constant; the results were in very good agreement with the extrapolation made with literature data obtained a lower temperature (up to 150 °C). The information obtained in this study would be directly usable in the modeling of hydrogen permeation in Pd-based systems. Pure and mixed gas permeation tests were performed on Pd-based hydrogen selective membranes at operative conditions close to steam-reforming ones. Two membranes (one produced in this work and another produced by NGK Insulators Japan) showed a virtually infinite selectivity and good permeability. Mixture data revealed the existence of non negligible resistances to hydrogen transport in the gas phase. Even if the decrease of the driving force due to polarization concentration phenomena occurs, in principle, in all membrane-based separation systems endowed with high perm-selectivity, an extensive experimental analysis lack, at the moment, in the palladium-based membrane process in literature. Moreover a new procedure has been introduced for the proper comparison of the mass transport resistance in the gas phase and in the membrane. Another object of study was the water vapor sorption and permeation in PFSI membranes with short and long side chains was also studied; moreover the permeation of gases (i.e. He, N2 and O2) in dry and humid conditions was considered. The water vapor sorption showed strong interactions between the hydrophilic groups and the water as revealed from the hysteresis in the sorption-desorption isotherms and thermo gravimetric analysis. The data obtained were used in the modeling of water vapor permeation, that was described as diffusion-reaction of water molecules, and in the humid gases permeation experiments. In the dry gas experiments the permeability and diffusivity was found to increase with temperature and with the equivalent weight (EW) of the membrane. A linear correlation was drawn between the dry gas permeability and the opposite of the equivalent weight of PFSI membranes, based on which the permeability of pure PTFE is retrieved in the limit of high EW. In the other hand O2 ,N2 and He permeability values was found to increase significantly, and in a similar fashion, with water activity. A model that considers the PFSI membrane as a composite matrix with a hydrophilic and a hydrophobic phase was considered allowing to estimate the variation of gas permeability with relative humidity on the basis of the permeability in the dry PFSI membrane and in pure liquid water.

Polialchiltiofeni contenenti derivati porfirinici per applicazioni in celle solari polimeriche

Il presente lavoro di tesi di laurea magistrale si è proposto di sintetizzare composti polimerici basati su un derivato del 3-esiltiofene e sulla porfirina per preparare materiali da utilizzare nelle celle fotovoltaiche. Politiofeni con queste caratteristiche sono stati sintetizzati a partire da un monomero -bromoalchiltiofenico, il 3-(6-bromoesil)tiofene (T6Br), dal quale è stato ottenuto il corrispondente derivato polimerico poli[3-(6-bromoesil)]tiofene (PT6Br). Esso è stato preparato con un metodo non regiospecifico, utilizzando la comune tecnica di polimerizzazione ossidativa in presenza di FeCl3. Il monomero T6Br è stato funzionalizzato con idrossifenil porfirina (TPPOH) per dare il 3-[5-(4-fenossi)-10,15,20-trifenilporfirinil]esiltiofene (T6TPP). Poiché la polimerizzazione diretta di questo monomero non si è mostrata una via percorribile, a causa dell’elevato ingombro del sostituente presente sulla catena macromolecolare, è stata effettuata l’eterificazione sul polimero bromurato PT6Br per ottenere il poli[3-[5-(4-fenossi)-10,15,20-trifenilporfirinil]esiltiofene] (PT6TPP). Contemporaneamente è stato sintetizzato il copolimero poli[(3-(6-bromoesil)]tiofene)-co-(3-[5-(4-fenossi)-10,15,20-trifenilporfirinil]esiltiofene)] (P(T6Br-co-T6TPP)) allo scopo di valutare l’effetto del diverso grado di sostituzione della catena polimerica sulle proprietà del polimero. Anch’esso è stato preparato con un metodo non regiospecifico, utilizzando la tecnica di polimerizzazione ossidativa in presenza di FeCl3. I prodotti sintetizzati sono stati caratterizzati mediante le comuni tecniche spettroscopiche (FTIR, NMR, UV-vis) e ne sono state determinate le proprietà termiche. I pesi molecolari medi e le relative distribuzioni sono stati determinati mediante cromatografia a permeazione su gel (GPC). Infine, con P(T6Br-co-T6TPP) e PT6Br sono state effettuate prove preliminari di preparazione e caratterizzazione di dispositivi per valutare la possibilità di un loro utilizzo come materiali per celle fotovoltaiche.

Derivati polimerici organometallici ancorati su matrice inorganica per applicazioni in chimica fine

Organotin compounds have found in the last few decades a wide variety of applications. Indeed, they are used successfully as antifouling paints, PVC stabilizers and ion carriers, as well as homogeneous catalysts. In this context, it has been proved that the Lewis acidity of the metal centre allows these compounds to promote the reaction between alcohol and ester. However their use is now limited by their well-known toxicity, moreover they are hardly removable from the reaction mixture. This problem can be overcome by grafting the organotin derivative onto a polymeric cross-linked support. In this way the obtained heterogeneous catalyst can be easily filtered off from the reaction mixture, thus creating the so-called "clean organotin reagents", avoiding the presence of toxic organotin residues in solution and the tin release in the environment. In the last few years several insoluble polystyrene resins containing triorganotin carboxylate moieties have been synthesized with the aim of improving their catalytic activity: in particular we have investigated and opportunely modified their chemical structure in order to optimize the accessibility to the metal centre and its Lewis acidity. Recently, we replaced the polymeric matrix with an inorganic one, in order to dispose of a relatively cheaper and easily available support. For this purpose an ordered mesoporous silica, characterized by 2D-hexagonal pores, named MCM-41, and an amorphous silica have been selected. In the present work two kinds of MCM-41 silica containing the triorganotin carboxylate moiety have been synthesized starting from a commercial Cab-O-Sil M5 silica. These catalysts have two different spacers between the core and the tin-carboxylate moiety, namely a polyaliphatic chain (compound FT29) or a poliethereal one (compound FT6), with the aim to improve the interaction between catalyst and reacting ester. Three catalysts supported onto an amorphous silica have been also synthesized: the structure is the same as silica FT29, i.e. a compound having a polialiphatic chain, and they have different percentage of organotin derivative grafted on the silica surface (10, 30, 50% respectively for silica MB9, SU27 and SU28). The performances of the above silica as heterogeneous catalysts in transesterification reactions have been tested in a model reaction between ethyl acetate and 1-octanol, a primary alcohol sensitive to the reaction conditions. The alcohol conversion was assessed by gas-chromatography, determining the relative amount of transesterified product and starting alcohol after established time intervals.

Sintesi di nanoparticelle polimeriche basate su acido(D,L-lattico-co-glicolico) per applicazioni in nanomedicina

Questo lavoro di tesi rientra nel progetto europeo SaveMe, al quale partecipa il gruppo di ricerca del dipartimento di chimica organica nel quale ho svolto l’attività di tirocinio. Obiettivo finale di tale progetto è la sintesi di nanoparticelle a base di PLGA (acido poli(D,L-lattico-co-glicolico)) superficialmente funzionalizzate con biomolecole, per l’impiego nel trattamento e nella diagnosi del cancro al pancreas. L’obiettivo da raggiungere nel primo anno di ricerca per il mio gruppo era la sintesi delle nanoparticelle centrali (core nanosystems). Nel presente lavoro sono quindi riportati i metodi di sintesi di polimeri derivati da PLGA e suoi copolimeri con PEG (polietilenglicole) aventi vari gruppi funzionali terminali: acidi idrossamici, amminici e acidi carbossilici. I polimeri sintetizzati sono stati caratterizzati tramite test colorimetrici qualitativi, 1H-NMR, 13C-NMR, spettrometria IR e TGA. Sono state sintetizzate nanoparticelle polimeriche (PNPs), con le tecniche Oil/Water (O/W) e nanoprecipitazione (NP), basate sui polimeri ottenuti, aventi quindi funzioni acide, idrossamiche ed amminiche sulla superficie. Su queste PNPs è stato effettuata una decorazione superficiale con nanoparticelle metalliche di maghemite (CAN-Maghemite). Le nanoparticelle polimeriche sono state caratterizzate tramite DLS e delle PNPs decorate sono state ottenute immagini TEM. Sono riportati inoltre i test di viabilità cellulare delle nanoparticelle ottenute.

Controllo molecolare del differenziamento osteoblestico per applicazioni nel campo della rigenerazione del tessuto osseo

The aim of the study was to identify expression signatures unique for specific stages of osteoblast differentiation in order to improve our knowledge of the molecular mechanisms underlying bone repair and regeneration. We performed a microarray analysis on the whole transcriptome of human mesenchymal stem cells (hMSCs) obtained from the femoral canal of patients undergoing hip replacement. By defining different time-points within the differentiation and mineralization phases of hMSCs, temporal gene expression changes were visualised. Importantly, the gene expression of adherent bone marrow mononuclear cells, being the undifferentiated progenitors of bone cells, was used as reference. In addition, only the cultures able to form mineral nodules at the final time-point were considered for the gene expression analyses. To obtain the genes of our interest, we only focused on genes: i) whose expression was significantly upregulated; ii) which are involved in pathways or biological processes relevant to proliferation, differentiation and functions of bone cells; iii) which changed considerably during the different steps of differentiation and/or mineralization. Among the 213 genes identified as differentially expressed by microarray analysis, we selected 65 molecular markers related to specific steps of osteogenic differentiation. These markers are grouped into various gene clusters according to their involvement in processes which play a key role in bone cell biology such as angiogenesis, ossification, cell communication, development and in pathways like TGF beta and Wnt signaling pathways. Taken together, these results allow us to monitor hMSC cultures and to distinguish between different stages of differentiation and mineralization. The signatures represent a useful tool to analyse a broad spectrum of functions of hMSCs cultured on scaffolds, especially when the constructs are conceived for releasing growth factors or other signals to promote bone regeneration. Morover, this work will enhance our understanding of bone development and will enable us to recognize molecular defects that compromise normal bone function as occurs in pathological conditions.