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Towards cheaper, safer and low environmental impact materials for energy storage devices: natural resources-derived carbon based electrodes and aqueous electrolytes for supercapacitors
Get PDFThe growing market of electrical cars, portable electronics, photovoltaic systems..etc. requires the development of efficient, low-cost, and low environmental impact energy storage devices (ESDs) including batteries and supercapacitors.. Due to their extended charge-discharge cycle, high specific capacitance, and power capabilities supercapacitors are considered among the most attractive ESDs. Over the last decade, research and development in supercapacitor technology have accelerated: thousands of articles have been published in the literature describing the electrochemical properties of the electrode materials and electrolyte in addition to separators and current collectors. Carbon-based supercapacitor electrodes materials have gained increasing attention due to their high specific surface area, good electrical conductivity, and excellent stability in harsh environments, as well as other characteristics. Recently, there has been a surge of interest in activated carbon derived from low-cost abundant sources such as biomass for supercapacitor electrode materials. Also, particular attention was given to a major challenging issue concerning the substitution of organic solutions currently used as electrolytes due to their highest electrochemical stability window even though their high cost, toxicity, and flammability.
In this regard, the main objective of this thesis is to investigate the performances of supercapacitors using low cost abundant safe, and low environmental impact materials for electrodes and electrolytes. Several prototypes were constructed and tested using natural resources through optimization of the preparation of appropriate carbon electrodes using agriculture by-products waste or coal (i.e. Argan shell or Anthracite from Jerrada). Such electrodes were tested using several electrolyte formulations (aqueous and water in salt electrolytes) beneficing their non-flammability, lower cost, and environmental impact; the characteristics that provide a promising opportunity to design safer, inexpensive, and environmentally friendly devices compared to organic electrolytes.Il mercato in crescita delle auto elettriche, dell'elettronica portatile, degli impianti fotovoltaici, ecc. richiede lo sviluppo di dispositivi di accumulo di energia (ESD) efficienti, a basso costo e a basso impatto ambientale, come batterie e supercondensatori. A causa della loro lunga vita di ciclo, dell'elevata capacitanza e potenza specifiche, i supercondensatori sono considerati tra gli ESD più interessanti . Nell'ultimo decennio, la ricerca e lo sviluppo della tecnologia dei supercondensatori hanno subito un'accelerazione: in letteratura sono stati pubblicati migliaia di articoli che descrivono le proprietà elettrochimiche dei materiali elettrodici ed elettrolitici, dei separatori e collettori di corrente. Gli elettrodi per supercondensatori a base di carbone hanno guadagnato crescente attenzione grazie alla loro elevata area superficiale specifica, buona conduttività elettrica ed eccellente stabilità chimica. Recentemente, e’ crescuito l’interesse verso carboni attivati derivati da fonti abbondanti a basso costo come la biomassa di scarto per realizzare componenti elettrodiche di supercondensatori. Inoltre, è sempre piu’ alta l’attenzione verso la sostituzione delle soluzioni organiche attualmente utilizzate come elettroliti per il loro costo, tossicità e infiammabilità elevati.
A questo proposito, l'obiettivo principale di questa tesi è quello di indagare le prestazioni dei supercondensatori utilizzando materiali a basso costo, abbondanti, sicuri e a basso impatto ambientale per elettrodi ed elettroliti. Diversi prototipi sono stati costruiti e testati utilizzando risorse naturali attraverso l'ottimizzazione della preparazione di elettrodi di carbone utilizzando scarti di sottoprodotti dell'agricoltura o carbone naturale (ad esempio guscio di argan o antracite di Jerrada). Tali elettrodi sono stati testati utilizzando diverse formulazioni di elettroliti acquosi selezionati per la loro non infiammabilità e minor costo e impatto ambientale, caratteristiche che offrono un'opportunità promettente per progettare dispositivi più sicuri, economici e rispettosi dell'ambiente rispetto agli elettroliti organici.
Parole chiave: Supercondensatore; Carbone attivo nanoporoso; Biomassa, gusci di argan, antracite, elettroliti acquosi, acetato di ammonio, elettrolita wáter in sal
Escaping the debt trap: peripheral countries in prolonged debt crises and how to exit
Get PDFThis thesis is an interdisciplinary piece of academic research, situated within Critical Theory but engaging with other disciplines, mainly Political Economy and Politics, to tackle the topic at hand; sovereign debt crises.
The thesis deals with the Problem of Debt and, more specifically, the Problem of Prolonged Sovereign Debt Crises, which is described in this thesis as the phenomenon of the “Debt Trap”. The specific question that will occupy us in this thesis is why countries appear unable to exit these prolonged debt crises. By exiting a debt crisis, we mean here a state of affairs in which a country has managed to render its debt sustainable, regain its democratic sovereignty, achieve economic recovery and, what is more, mitigate adverse effects of the crisis, especially in what human development, social inequality and poverty rates are concerned. This question is tackled through the use of an interdisciplinary approach that combines critical theory perspectives -which are grouped in two paradigms, the Subjectivity paradigm and the genealogies of Capitalism paradigm- with financialisation literature. The purpose is to form an interdisciplinary intellectual framework that will allow us to analyse with a critical perspective the two case studies of the Greek crisis from 2009 to 2015 and the Argentinean crisis from 1983 to 2005. The aim of the thesis is to develop a theoretical framework that allows us to deconstruct the various ideological approaches to these two particular cases of Debt traps, including neoclassical and neoliberal approaches, Conservative and Keynesian approaches and uncover the political, economic and class relation that underpin the prolonged crises that the two countries have experienced
Sex differences in coronary artery disease severity and mortality: the impact of conventional cardiovascular risk factors
Get PDFIt is still unknown whether traditional risk factors may have a sex specific impact on the severity of coronary artery disease (CAD) and subsequent mortality in acute coronary syndromes (ACS). We identified 14 793 patients who underwent coronary angiography for acute coronary syndromes in the ISACS-TC (NCT01218776) registry from 2010 to 2019. The main outcome measure was the association between conventional risk factors and severity of CAD and its relationship with 30-day mortality. Risk ratios (RRs) and 95% CIs were calculated from the ratio of the absolute risks of women versus men using inverse probability of weighting. Severity of disease was categorized as obstructive (≥50% stenosis) versus nonobstructive CAD, specifically Ischemia and No Obstructive Coronary Artery disease (INOCA) and Myocardial Infarction with Non obstructive Coronary Arteries (MINOCA). The RR ratio for obstructive CAD in women versus men among people without diabetes mellitus was 0.49(95%CI,0.41–0.60) and among those with diabetes mellitus was 0.89(95% CI,0.62–1.29), with an interaction by diabetes mellitus status of P =0.002. Exposure to smoking shifted the RR ratios from 0.50 (95% CI, 0.41–0.61) in nonsmokers to 0.75 (95%CI, 0.54–1.03) in current smokers, with an interaction by smoking status of P=0.018. There were no significant sex-related interactions with hypercholesterolemia and hypertension. Women with obstructive CAD had higher 30-day mortality rates than men
(RR, 1.75; 95% CI, 1.48–2.07). No sex differences in mortality were observed in patients with INOCA/MINOCA. In conclusion, obstructive CAD in women signifies a higher risk for mortality compared with men. Current smoking and diabetes mellitus disproportionally increase the risk of obstructive CAD in women. Achieving the goal of improving cardiovascular health in women still requires intensive efforts toward further implementation of lifestyle and treatment interventions
Treatment of aortic valve stenosis: molecular and surgical new perspectives
Get PDFLa stenosi valvolare aortica è la più frequente patologia valvolare cardiaca nei paesi sviluppati come diretta conseguenza dell’aumentata aspettativa di vita. In Europa si stima che il numero di soggetti sintomatici per stenosi valvolare aortica aumenterà da 1.3 milioni nel 2025 a 2.1 milioni in 2050. Di conseguenza la stenosi aortica ha e avrà un forte impatto sulla salute pubblica e sui costi che ne determina, poiché spesso associata a un declino funzionale dei pazienti ed aumentata incidenza di ospedalizzazione. D’altra parte è noto che la stenosi valvolare aortica severa non trattata si associa a prognosi infausta con una sopravvivenza del 50% a 2 anni dall’insorgenza dei sintomi e del 20% a 5 anni. Ad oggi non esiste una terapia medica efficace per la stenosi valvolare aortica in quanto andando a costituire un’ostruzione meccanica, resta di competenza del cardiochirurgo o del cardiologo interventista. La sostituzione valvolare aortica, sia essa chirurgica o percutanea, resta pertanto il solo trattamento definitivo per la stenosi valvolare aortica. Nel tempo il rischio operatorio è estremamente diminuito e i vantaggi in termini di miglioramento della qualità di vita sono evidenti.
Questo progetto di ricerca prevede pertanto un’analisi delle più recenti tecnologie per il trattamento chirurgico della stenosi valvolare aortica a partire dalla tipologia di approccio chirurgico, se mini-invasivo o tradizionale, fino all’utilizzo delle più recenti protesi biologiche sutureless studiandone i vantaggi, svantaggi e risultati. Prima ancora, tuttavia, saranno analizzati i meccanismi di biologia molecolare alla base dell’eziologia della stenosi aortica al fine di poter identificare precocemente i pazienti, di prevedere l’andamento della patologia e forse, in futuro, anche di ipotizzare una terapia farmacologica mirata.Aortic valve stenosis is the most frequent heart valve disease in developed countries as a direct consequence of increased life expectancy. In Europe it is estimated that the number of people symptomatic of aortic valve stenosis will increase from 1.3 million in 2025 to 2.1 million in 2050. Consequently, aortic stenosis has and will have a strong impact on public health and the costs it determines, as it is often associated with a patients functional decline and with an increased incidence of hospitalization. On the other hand, it is known that untreated severe aortic valve stenosis is associated with a poor prognosis with a survival of 50% at 2 years from the onset of symptoms and 20% at 5 years. To date, there is no effective medical therapy for aortic valve stenosis as it constitutes a mechanical obstruction. Aortic valve replacement, be it surgical or percutaneous, therefore remains the only definitive treatment for aortic valve stenosis. Over time, the surgical risk has greatly decreased and the advantages in terms of improving the quality of life are evident.
This research project therefore provides for an analysis of the most recent technologies for the surgical treatment of aortic valve stenosis starting from the type of surgical approach, whether minimally invasive or traditional, up to the use of the most recent sutureless biological prostheses, studying their advantages, disadvantages and results. Before that, however, the molecular biology mechanisms underlying the etiology of aortic stenosis will be analyzed in order to be able to identify patients early, to predict the course of the disease and perhaps, in the future, also to hypothesize a targeted drug therapy
Timeliness, efficiency and public procurement in hip surgery in Italy
Get PDFConsidering different perspectives, the scope of this thesis is to investigate how to improve healthcare resources allocation and the provision efficiency for hip surgeries, a resource-intensive operation, among the most frequently performed on the elderly, with a trend in volume that is increasing in years due to population aging.
Firstly, the effect of Time-To-Surgery (TTS) on mortality for hip fracture patients is investigated. The analysis attempts to account for TTS endogeneity due to the inability to fully control for variables affecting patient delay – e.g. patient severity. Exploiting an instrumental variable model, where being admitted on Friday or Saturday predicts longer TTS, findings show exogenous TTS does not have a significant effect on mortality. Thus suggesting surgeons prioritize patients effectively, neutralizing the adverse impact of longer TTS. Then, the volume-outcome relation for total hip replacement surgery is analyzed, seeking to account for selective referral, which may be present in elective surgery context, and induce reverse causality issue in the volume-outcome relation. The analysis employs a conditional choice model where patient travel distance from all regions' hospitals is used as a hospital choice predictor. Findings show the exogenous hospital volume significantly decreases adverse outcomes probability, especially in the short run. Finally, the change in public procurement design enforced in the Romagna LHA (Italy) is exploited to assess its impact on hip prostheses cost, surgeons' implant choice, and patient health outcomes. Hip prostheses are the major cost-driver of hip replacement surgeries, hence it is crucial to design the public tender such that implant prices are minimized, but cost-containment policies have to be weighted with patient well-being. Evidence shows that a cost reduction occurred without a significant surgeons’ choices impact. Positive or no effect of surgeons specialization is found on patients outcomes after the new procurement introduction
Application of Pulsed Electric Fields for the Modulation of Chemico-Physical Properties of Different Foods
Get PDFPulsed electric field technology is one of the most attractive new non-thermal technology thanks to its lower energy consumption and short treatment times. It consists of an electric treatment of short duration (from several ns to several ms) with electric field strengths from 0.1 to 80 kV/cm that lead to an increase in the permeability of the cell membrane.
In this PhD thesis, PEF technology was investigated with the aim of improving mass transfer in plant and animal foods by using it alone or in combination with conventional food processes. Different methods of evaluating electroporation for optimizing PEF processing parameters were investigated. In this respect, the degree of membrane permeabilization in plant and animal food matrices was investigated using electrical impedance spectroscopy, current-voltage measurements and magnetic resonance imaging.
The research findings provided useful insights and calls for critical choice of electroporation assessment methods for the selection of adequate PEF treatment conditions.
It was outlined that the effect of electroporation is highly dependent on the properties of the food matrix and secondary phenomena occurring in the cell structure undergoing PEF treatment, such as the water re-distribution in the tissue due to the exchange of fluids between intra- and extra-cellular environments.
This study also confirmed the great potential of combining PEF technology with conventional food processes, with the main purpose of improving the quality of the food material and accelerating the kinetics of mass transfers, in both plant and animal tissues. Consistent reduction of acrylamide formation in potato crisps was achieved by monitoring key PEF process parameters and subsequent manufacturing steps. Kiwifruit snacks showed a significant reduction in drying kinetics when pre-treated with PEF, while their quality was well maintained. Finally, the research results showed that PEF pre-treatments can shorten the brine process as well as the rehydration kinetics of fish muscles
Feeding the Gut Microbiome and Immune Maturation to Manage Weaned Piglets
Get PDFThis thesis reports five studies that may contribute to understand how weaning affects the immune and intestinal microbiota maturation of the piglet and proposes some possible nutritional strategies to attenuate its negative effects. The first study showed that weaning is associated in Payer’s patches with the activation of MHC response against class I antigens and that related to the stimulation to IFN-γ and showed, for the first time, that their blood at weaning remains dominated by immature blood cells. In the second study we tested if the use of a live vaccine against a conditionally but also genetically based intestinal disease, like PWD, could have an impact on the growth performance of pigs and their intestinal microbiota and if it could provide a model to test the response to nutritional strategies under conditions of an immune and intestinal stimulation for animals susceptible to ETEC type. In this study, we demonstrated how a vaccinal strain of F4/F18 E. coli can affect the gut microbial composition of piglets, regardless of their genetic susceptibility to ETEC infection. In the third study we evidenced how a nucleotide supplementation can favor the proliferation of jejunal Peyer patches and anticipate the maturation of the fecal microbiota. In the fourth study we reported how xylanase can favor the proliferation of Lactobacillus reuteri. Finally, we showed some first results on the muscles fiber development in fast- and slow-growing suckling pigs and the relationship with the intestinal microbiota. Taken together, the results presented in this thesis provide new insight about the interplay between the host-genetics, gut microbial composition, and host physiological status. Furthermore, it provides confirmation that the use of known genetic markers for ETEC F4 and F18 could represent a potential tool to stratify the animals in the trials both in healthy or challenge-based protocols
Computational Investigation of the Molecular Mechanisms Regulating Nucleic Acid Processing Metalloenzymes
Get PDFPolymerases and nucleases are enzymes processing DNA and RNA. They are involved in crucial processes for cell life by performing the extension and the cleavage of nucleic acid chains during genome replication and maintenance. Additionally, both enzymes are often associated to several diseases, including cancer. In order to catalyze the reaction, most of them operate via the two-metal-ion mechanism. For this, despite showing relevant differences in structure, function and catalytic properties, they share common catalytic elements, which comprise the two catalytic ions and their first-shell acidic residues. Notably, recent studies of different metalloenzymes revealed the recurrent presence of additional elements surrounding the active site, thus suggesting an extended two-metal-ion-centered architecture. However, whether these elements have a catalytic function and what is their role is still unclear. In this work, using state-of-the-art computational techniques, second- and third-shell elements are showed to act in metallonucleases favoring the substrate positioning and leaving group release. In particular, in hExo1 a transient third metal ion is recruited and positioned near the two-metal-ion site by a structurally conserved acidic residue to assist the leaving group departure. Similarly, in hFEN1 second- and third-shell Arg/Lys residues operate the phosphate steering mechanism through (i) substrate recruitment, (ii) precise cleavage localization, and (iii) leaving group release. Importantly, structural comparisons of hExo1, hFEN1 and other metallonucleases suggest that similar catalytic mechanisms may be shared by other enzymes. Overall, the results obtained provide an extended vision on parallel strategies adopted by metalloenzymes, which employ divalent metal ion or positively charged residues to ensure efficient and specific catalysis. Furthermore, these outcomes may have implications for de novo enzyme engineering and/or drug design to modulate nucleic acid processing
Design and Off-design modelling of advanced Power-to-Gas energy storage systems
Get PDFPower-to-Gas storage systems have the potential to address grid-stability issues that arise when an increasing share of power is generated from sources that have a highly variable output. Although the proof-of-concept of these has been promising, the behaviour of the processes in off-design conditions is not easily predictable.
The primary aim of this PhD project was to evaluate the performance of an original Power-to-Gas system, made up of innovative components. To achieve this, a numerical model has been developed to simulate the characteristics and the behaviour of the several components when the whole system is coupled with a renewable source. The developed model has been applied to a large variety of scenarios, evaluating the performance of the considered process and exploiting a limited amount of experimental data. The model has been then used to compare different Power-to-Gas concepts, in a real scenario of functioning.
Several goals have been achieved. In the concept phase, the possibility to thermally integrate the high temperature components has been demonstrated. Then, the parameters that affect the energy performance of a Power-to-Gas system coupled with a renewable source have been identified, providing general recommendations on the design of hybrid systems; these parameters are: 1) the ratio between the storage system size and the renewable generator size; 2) the type of coupled renewable source; 3) the related production profile. Finally, from the results of the comparative analysis, it is highlighted that configurations with a highly oversized renewable source with respect to the storage system show the maximum achievable profit
Development of thermochemiluminescence-based sensitive probes: synthesis, optimization, and characterization of c2- and c7-substituted acridine-containing 1,2-dioxetanes
Get PDFAfter initial efforts in the late 1980s, the interest in thermochemiluminescence (TCL) as an effective detection technique has gradually faded due to some drawbacks, such as the high temperatures required to trigger the light emission and the relatively low intensities, which determined a poor sensitivity. Recent advances made with the adoption of variably functionalized 1,2-dioxetanes as innovative luminophores, have proved to be a promising approach for the development of reagentless and ultrasensitive detection methods exploitable in biosensors by using TCL compounds as labels, as either single molecules or included in modified nanoparticles.
In this PhD Thesis, a novel class of N-substituted acridine-containing 1,2-dioxetanes was designed, synthesized, and characterized as universal TCL probes endowed with optimal emission-triggering temperatures and higher detectability particularly useful in bioanalytical assays. The different decorations introduced by the insertion of both electron donating (EDGs) and electron withdrawing groups (EWGs) at the 2- and 7-positions of acridine fluorophore was found to profoundly affect the photophysical properties and the activation parameters of the final 1,2-dioxetane products. Challenges in the synthesis of 1,2-dioxetanes were tackled with the recourse to continuous flow photochemistry to achieve the target parent compound in high yields, short reaction time, and easy scalability. Computational studies were also carried out to predict the olefins reactivity in the crucial photooxygenation reaction as well as the final products stability. The preliminary application of TCL prototype molecule has been performed in HaCaT cell lines showing the ability of these molecules to be detected in real biological samples and cell-based assays. Finally, attempts on the characterization of 1,2-dioxetanes in different environments (solid state, optical glue and nanosystems) and the development of bioconjugated TCL probes will be also presented and discussed