Antropologia e Migrazioni: una storia di co-sviluppo tra l'Italia ed il Ghana

Nella tesi sono rielaborati i dati etnografici, prodotti in Italia ed in Ghana, con una ricerca sul campo di oltre un anno. Attraverso la ricostruzione di un progetto di co-sviluppo che mobilita i migranti in quanto attori di sviluppo, ed in questo caso l’associazione ghanese di Modena per avviare alcune iniziative di sviluppo economico, umano e sostenibile nel paese d’origine, si sono indagate le forme concrete di transnazionalismo attivate da questo gruppo sociale. Nell’analisi, prettamente antropologica, si rivela come, nel progetto di co-sviluppo osservato, le identità etniche, le relazioni asimmetriche di genere ed i processi di negoziazione politica sono celati ed agiti dai diversi attori sociali coinvolti. Si sono inoltre osservate le forme di partecipazione politica in Italia ed in Ghana rivelando come il collettivo ghanese abbia avviato un processo di depoliticizzazione dello sviluppo nel contesto d’origine e, nonostante ciò, sia divenuto nel paese d’immigrazione un nuovo attore politico. Particolare attenzione è stata posta alle produzioni discorsive dello sviluppo e della diaspora, evidenziando come i collettivi migranti se ne riapproprino e le riformulino nelle pratiche quotidiane.

Catalytic liquid- and gas-phase oxidations for the synthesis of intermediates and specialty chemicals: some examples of industrial relevance

Nowadays, it is clear that the target of creating a sustainable future for the next generations requires to re-think the industrial application of chemistry. It is also evident that more sustainable chemical processes may be economically convenient, in comparison with the conventional ones, because fewer by-products means lower costs for raw materials, for separation and for disposal treatments; but also it implies an increase of productivity and, as a consequence, smaller reactors can be used. In addition, an indirect gain could derive from the better public image of the company, marketing sustainable products or processes. In this context, oxidation reactions play a major role, being the tool for the production of huge quantities of chemical intermediates and specialties. Potentially, the impact of these productions on the environment could have been much worse than it is, if a continuous efforts hadn’t been spent to improve the technologies employed. Substantial technological innovations have driven the development of new catalytic systems, the improvement of reactions and process technologies, contributing to move the chemical industry in the direction of a more sustainable and ecological approach. The roadmap for the application of these concepts includes new synthetic strategies, alternative reactants, catalysts heterogenisation and innovative reactor configurations and process design. Actually, in order to implement all these ideas into real projects, the development of more efficient reactions is one primary target. Yield, selectivity and space-time yield are the right metrics for evaluating the reaction efficiency. In the case of catalytic selective oxidation, the control of selectivity has always been the principal issue, because the formation of total oxidation products (carbon oxides) is thermodynamically more favoured than the formation of the desired, partially oxidized compound. As a matter of fact, only in few oxidation reactions a total, or close to total, conversion is achieved, and usually the selectivity is limited by the formation of by-products or co-products, that often implies unfavourable process economics; moreover, sometimes the cost of the oxidant further penalizes the process. During my PhD work, I have investigated four reactions that are emblematic of the new approaches used in the chemical industry. In the Part A of my thesis, a new process aimed at a more sustainable production of menadione (vitamin K3) is described. The “greener” approach includes the use of hydrogen peroxide in place of chromate (from a stoichiometric oxidation to a catalytic oxidation), also avoiding the production of dangerous waste. Moreover, I have studied the possibility of using an heterogeneous catalytic system, able to efficiently activate hydrogen peroxide. Indeed, the overall process would be carried out in two different steps: the first is the methylation of 1-naphthol with methanol to yield 2-methyl-1-naphthol, the second one is the oxidation of the latter compound to menadione. The catalyst for this latter step, the reaction object of my investigation, consists of Nb2O5-SiO2 prepared with the sol-gel technique. The catalytic tests were first carried out under conditions that simulate the in-situ generation of hydrogen peroxide, that means using a low concentration of the oxidant. Then, experiments were carried out using higher hydrogen peroxide concentration. The study of the reaction mechanism was fundamental to get indications about the best operative conditions, and improve the selectivity to menadione. In the Part B, I explored the direct oxidation of benzene to phenol with hydrogen peroxide. The industrial process for phenol is the oxidation of cumene with oxygen, that also co-produces acetone. This can be considered a case of how economics could drive the sustainability issue; in fact, the new process allowing to obtain directly phenol, besides avoiding the co-production of acetone (a burden for phenol, because the market requirements for the two products are quite different), might be economically convenient with respect to the conventional process, if a high selectivity to phenol were obtained. Titanium silicalite-1 (TS-1) is the catalyst chosen for this reaction. Comparing the reactivity results obtained with some TS-1 samples having different chemical-physical properties, and analyzing in detail the effect of the more important reaction parameters, we could formulate some hypothesis concerning the reaction network and mechanism. Part C of my thesis deals with the hydroxylation of phenol to hydroquinone and catechol. This reaction is already industrially applied but, for economical reason, an improvement of the selectivity to the para di-hydroxilated compound and a decrease of the selectivity to the ortho isomer would be desirable. Also in this case, the catalyst used was the TS-1. The aim of my research was to find out a method to control the selectivity ratio between the two isomers, and finally to make the industrial process more flexible, in order to adapt the process performance in function of fluctuations of the market requirements. The reaction was carried out in both a batch stirred reactor and in a re-circulating fixed-bed reactor. In the first system, the effect of various reaction parameters on catalytic behaviour was investigated: type of solvent or co-solvent, and particle size. With the second reactor type, I investigated the possibility to use a continuous system, and the catalyst shaped in extrudates (instead of powder), in order to avoid the catalyst filtration step. Finally, part D deals with the study of a new process for the valorisation of glycerol, by means of transformation into valuable chemicals. This molecule is nowadays produced in big amount, being a co-product in biodiesel synthesis; therefore, it is considered a raw material from renewable resources (a bio-platform molecule). Initially, we tested the oxidation of glycerol in the liquid-phase, with hydrogen peroxide and TS-1. However, results achieved were not satisfactory. Then we investigated the gas-phase transformation of glycerol into acrylic acid, with the intermediate formation of acrolein; the latter can be obtained by dehydration of glycerol, and then can be oxidized into acrylic acid. Actually, the oxidation step from acrolein to acrylic acid is already optimized at an industrial level; therefore, we decided to investigate in depth the first step of the process. I studied the reactivity of heterogeneous acid catalysts based on sulphated zirconia. Tests were carried out both in aerobic and anaerobic conditions, in order to investigate the effect of oxygen on the catalyst deactivation rate (one main problem usually met in glycerol dehydration). Finally, I studied the reactivity of bifunctional systems, made of Keggin-type polyoxometalates, either alone or supported over sulphated zirconia, in this way combining the acid functionality (necessary for the dehydrative step) with the redox one (necessary for the oxidative step). In conclusion, during my PhD work I investigated reactions that apply the “green chemistry” rules and strategies; in particular, I studied new greener approaches for the synthesis of chemicals (Part A and Part B), the optimisation of reaction parameters to make the oxidation process more flexible (Part C), and the use of a bioplatform molecule for the synthesis of a chemical intermediate (Part D).

Polymorphs solvates and co-crystals of molecular materials

The scope of my research project is to produce and characterize new crystalline forms of organic compounds, focusing the attention on co-crystals and then transferring these notions on APIs to produce co-crystals of potential interest in the pharmaceutical field. In the first part of this work co-crystallization experiments were performed using as building blocks the family of aliphatic dicarboxylic acids HOOC-(CH2)n-COOH, with n= 2-8. This class of compounds has always been an object of study because it is characterized by an interesting phenomenon of alternation of melting points: the acids with an even number of carbon atoms show a melting point higher than those with an odd one. The acids were co-crystallized with four dipyridyl molecules (formed by two pyridine rings with a different number of bridging carbon atoms) through the formation of intermolecular interactions N•••(H)O. The bases used were: 4,4’-bipyridine (BPY), 1,2-bis(4-pyridyl)ethane (BPA), 1,2-(di-4-pyridyl)ethylene (BPE) and 1,2-bis(4-pyridyl)propane (BPP). The co-crystals obtained by solution synthesis were characterized by different solid-state techniques to determine the structure and to see how the melting points in co-crystals change. In the second part of this study we tried to obtain new crystal forms of compounds of pharmaceutical interest. The APIs studied are: O-desmethylvenlafaxine, Lidocaine, Nalidixic Acid and Sulfadiazine. Each API was subjected to Polymorph Screening and Salt/Co-crystal Screening experiments to identify new crystal forms characterized by different properties. In a typical Salt/Co-crystal Screening the sample was made to react with a co-former (solid or liquid) through different methods: crystallization by solution, grinding, kneading and solid-gas reactions. The new crystal forms obtained were characterized by different solid state techniques (X-ray single crystal diffraction, X-ray powder diffraction, Differential Scanning Calorimetry, Thermogravimetric Analysis, Evolved gas analysis, FT-IR – ATR, Solid State N.M.R).

Co-simulazione e co-progetto non lineare/elettromagnetico di sistemi wireless non convenzionali

L’attività di ricerca contenuta in questa tesi si è concentrata nello sviluppo e nell’implementazione di tecniche per la co-simulazione e il co-progetto non lineare/elettromagnetico di sistemi wireless non convenzionali. Questo lavoro presenta un metodo rigoroso per considerare le interazioni tra due sistemi posti sia in condizioni di campo vicino che in condizioni di campo lontano. In sostanza, gli effetti del sistema trasmittente sono rappresentati da un generatore equivalente di Norton posto in parallelo all’antenna del sistema ricevente, calcolato per mezzo del teorema di reciprocità e del teorema di equivalenza. La correttezza del metodo è stata verificata per mezzo di simulazioni e misure, concordi tra loro. La stessa teoria, ampliata con l’introduzione degli effetti di scattering, è stata usata per valutare una condizione analoga, dove l’elemento trasmittente coincide con quello ricevente (DIE) contenuto all’interno di una struttura metallica (package). I risultati sono stati confrontati con i medesimi ottenibili tramite tecniche FEM e FDTD/FIT, che richiedono tempi di simulazione maggiori di un ordine di grandezza. Grazie ai metodi di co-simulazione non lineari/EM sopra esposti, è stato progettato e verificato un sistema di localizzazione e identificazione di oggetti taggati posti in ambiente indoor. Questo è stato ottenuto dotando il sistema di lettura, denominato RID (Remotely Identify and Detect), di funzioni di scansione angolare e della tecnica di RADAR mono-pulse. Il sistema sperimentale, creato con dispositivi low cost, opera a 2.5 GHz ed ha le dimensioni paragonabili ad un normale PDA. E’ stato sperimentata la capacità del RID di localizzare, in scenari indoor, oggetti statici e in movimento.

Characterization of circulating steroids and endocannabinoids levels in obese subjects by liquid chromatography tandem mass spectrometry

Nowadays obesity can be defined as a global epidemic. The precise identification of circulating biomarkers involved in this pathology could be essential to early diagnose potential co-morbidities and to better address the development of future therapeutic strategies. Published evidences show that circulating steroid hormones and endocannabinoids might have a role in the physiopathology of obesity; however, a precise and reliable quantification of these molecules is still lacking. In the first part of the present thesis, we developed a sensitive, specific and accurate quantification method for nine steroid hormones using a liquid chromatography tandem mass spectrometry (LC-MS/MS) system. This method has been used first for a comparative study with immunoassays, currently used in the clinical practice to quantify these molecules and then to redefine circulating reference intervals in healthy subjects. Furthermore, we measured circulating steroid hormones in three groups of subjects: normo-weight, over-weight and obese, defining different steroid hormones profiles depending on the obesity state. The role of circulating endocannabinoids in humans is still unclear, however there are several evidences concerning their involvement in obesity. In the second part of the thesis, we determined changes of circulating endocannabinoids in obese patients after a weight loss induced by bariatric surgery, currently the most effective long-term treatment for obesity, using LC/MS-MS. We measured basal and dynamic endocannabinoids plasma levels in 12 patients with severe obesity before, one month after and six months after the Roux-en-Y gastric bypass intervention, currently one of the most performed types of bariatric surgery. All together the findings illustrated in this thesis project will help better define the role of steroid hormones and endocannabinoids in the framework of obesity in humans and the role that each type of molecule might have in its pathophysiology.