Tailoring properties and functionalities of TiO2 and Ag nanoparticles involved in surfaces engineering processes

The functionalization of substrates through the application of nanostructured coatings allows to create new materials, with enhanced properties. In this work, the development of self-cleaning and antibacterial textiles, through the application of TiO2 and Ag based nanostructured coatings was carried out. The production of TiO2 and Ag functionalized materials was achieved both by the classical dip-padding-curing method and by the innovative electrospinning process to obtain nanofibers doped with nano-TiO2 and nano-Ag. In order to optimize the production of functionalized textiles, the study focused on the comprehension of mechanisms involved in the photocatalytic and antibacterial processes and on the real applicability of the products. In particular, a deep investigation on the relationship between nanosol physicochemical characteristics, nanocoating properties and their performances was accomplished. Self-cleaning textiles with optimized properties were obtained by properly purifying and applying commercial TiO2 nanosol while the studies on the photocatalytic mechanism operating in self-cleaning application demonstrated the strong influence of hydrophilic properties and of interaction surface/radicals on final performance. Moreover, a study about the safety in handling of nano-TiO2 was carried out and risk remediation strategies, based on “safety by design” approach, were developed. In particular, the coating of TiO2 nanoparticles by a SiO2 shell was demonstrated to be the best risk remediation strategy in term of biological response and preserving of photoreactivity. The obtained results were confirmed determining the reactive oxygen species production by a multiple approach. Antibacterial textiles for biotechnological applications were also studied and Ag-coated cotton materials, with significant anti-bacterial properties, were produced. Finally, composite nanofibers were obtained merging biopolymer processing and sol-gel techniques. Indeed, electrospun nanofibers embedded with TiO2 and Ag NPs, starting from aqueous keratin based formulation were produced and the photocatalytic and antibacterial properties were assessed. The results confirmed the capability of electrospun keratin nanofibers matrix to preserve nanoparticle properties.

Sinus rhythm restoration with electrical cardioversion: acute effect of shock configuration and subsequent modifications in peripheral flow and sleep.

Atrial fibrillation (AF) is a widespread arrhythmia, associated with higher risk of stroke, sleep disorders and dementia. In some conditions, electrical cardioversion (ECV) represents the best choice for rhythm control. Nowadays, there is a growing interest in developing new devices for screening and monitoring of AF patients. We aimed to improve acute efficacy of ECV procedure and to explore the feasibility of the use of new wearable devices for monitoring in candidates to AF ECV. We compared antero-apical pads vs antero-posterior patches approach for AF ECV, and we elaborated a decision algorithm to improve acute efficacy. After, we evaluated the feasibility of the use of new wearable devices for monitoring of candidates to AF ECV. In particular, we analysed the effect of AF ECV on heart rate variability and vascular age parameters derived from PPG signals registered with Empatica (CE 1876/MDD 93/42/EEC), and on EEG pattern registered with Neurosteer (Israel). From December 2005 to September 2019, 492 patients were enrolled. We evaluated acute efficacy of the two approaches for AF ECV and we elaborated a decision algorithm based on body surface area, weight, and height. The decision algorithm improved first shock efficacy (93.2% vs. 87.2%, p=0.025). From 1st November 2021 to 1st April 2022, 24 patients were enrolled in PPEEG-AF pilot study. Considering vascular age parameters, a significant reduction in TPR and a wave was observed (p<0.001). Considering sleep patterns, a tendency to higher coherence was observed in registrations acquired during AF, or considering signals registered for each patient independently from AF. The new decision algorithm improved acute efficacy and reduced costs associated with adhesive patches. Significant modifications were observed on vascular age parameters measured before and after ECV, and a possible AF effect on sleep pattern was noticed. More data are necessary to confirm these preliminary results.

Study of materials and interphases for electrochemical energy storage from renewable sources

Batteries should be refined depending on their application for a future in which the sustainable energy demand increases. On the one hand, it is fundamental to improve their safety, prevent failures, increase energy density, and reduce production costs. On the other hand, new battery materials and architecture are required to satisfy the growing demand. This thesis explores different electrochemical energy storage systems and new methodologies to investigate complex and dynamic processes. Lithium-ion batteries are described in all their cell components. In these systems, this thesis investigates negative electrodes. Both the development of new sustainable materials and new in situ electrode characterization methods were explored. One strategy to achieve high-energy systems is employing lithium metal anodes. In this framework, ammonium hexafluorophosphate is demonstrated to be a suitable additive for stabilizing the interphase and preventing uncontrolled dendritic deposition. Deposition/stripping cycles, electrochemical impedance spectroscopy, in situ optical microscopy, and operando confocal Raman spectroscopy have been used to study lithium metal-electrolyte interphase in the presence of the additive. Redox Flow Batteries (RFBs) are proposed as a sustainable alternative for stationary applications. An all-copper aqueous RFB (CuRFB) has been studied in all its aspects. For the electrolyte optimization, spectro-electrochemical tests in diluted solution have been used to get information on the electrolyte’s electrochemical behaviour with different copper complexes distributions. In concentrated solutions, the effects of copper-to-ligand ratios, the concentration, and the counter-ion of the complexing agent were evaluated. Electrode thermal treatment was optimized, finding a compromise between the electrochemical performance and the carbon footprint. On the membrane side, a new method for permeability studies was designed using scanning electrochemical microscopy (SECM). The Cu(II) permeability of several membranes was tested, obtaining direct visualization of Cu(II) concentration in space. Also, two spectrophotometric approaches were designed for SoC monitoring systems for negative and positive half-cells.

Characterization of pyrolysis and oxidation processes of biomaterials, biomasses and biofuels

The urgent need for alternative solutions mitigating the impacts of human activities on the environment has strongly opened new challenges and opportunities in view of the energy transition. Indeed, the automotive industry is going through a revolutionary moment in its quest to reduce its carbon footprint, with biofuels being one of the viable alternatives. The use of different classes of biofuels as fuel additives/standalone components has attracted the attention of many researchers. Despite their beneficial effects, biofuel’s combustion can also result in the production of undesirable pollutants, requiring complete characterization of the phenomena occurring during their production and consumption. Industrial scale-up of biomass conversion is challenging owing to the complexity of its chemistry and transport phenomena involved in the process. In this view, the role of solid-phase and gas-phase chemistry is paramount. Thus, this study is devoted to detailed analysis of physical-chemical phenomena characterizing biomass pyrolysis and biofuel oxidation. The pyrolysis mechanism has been represented by 20 reactions whereas, the gas-phase kinetic models; manually upgraded model (KiBo_MU) and automated model (KiBo_AG), comprises 141 species and 453 reactions, and 631 species and 28329 reactions, respectively. The accuracy of the kinetic models was tested against experimental data and the models captured experimental trends very well. While the development and validation of detailed kinetic mechanisms is the main deliverable of this project, the realized procedure integrating schematic classifications with methodologies for the identification of common decomposition pathways and intermediates represents an additional source of novelty. Besides, the fundamentally oriented nature of the adopted method allows the identification of most relevant reactions and species under the operating conditions different industrial applications, paving the way for reduced kinetic mechanisms. Ultimately, the resulting detailed mechanisms can be used to integrate with more complex fluid dynamics model to accurately reproduce the behavior of real systems and reactors.

Innovation in aquaculture. Modeling the adoption and implementation processes of innovations in the Italian aquaculture sector

Since the turn of the century, fisheries have maintained a steady growth rate, while aquaculture has experienced a more rapid expansion. Aquaculture can offer EU consumers more diverse, healthy, and sustainable food options, some of which are more popular elsewhere. To develop the sector, the EU is investing heavily. The EU supports innovative projects that promote the sustainable development of seafood sectors and food security. Priority 3 promotes sector development through innovation dissemination. This doctoral dissertation examined innovation transfer in the Italian aquaculture sector, specifically the adoption of innovative tools, using a theoretical model to better understand the complexity of these processes. The work focused on innovation adoption, emphasising that it is the end of a well-defined process. The Awareness Knowledge Adoption Implementation Effectiveness (AKAIE) model was created to better analyse post-adoption phases and evaluate technology adoption implementation and impact. To identify AKAIE drivers and barriers, aquaculture actors were consulted. "Perceived complexity"—barriers to adoption that are strongly influenced by contextual factors—has been used to examine their perspectives (i.e. socio-economic, institutional, cultural ones). The new model will contextualise the sequence based on technologies, entrepreneur traits, corporate and institutional contexts, and complexity perception, the sequence's central node. Technology adoption can also be studied by examining complexity perceptions along the AKAIE sequence. This study proposes a new model to evaluate the diffusion of a given technology, offering the policy maker the possibility to be able to act promptly across the process. The development of responsible policies for evaluating the effectiveness of innovation is more necessary than ever, especially to orient strategies and interventions in the face of major scenarios of change.

Numerical simulation of the flow and performance evaluation of an aerospike engine

The main focus of this work is to define a numerical methodology to simulate an aerospike engine and then to analyse the performance of DemoP1, which is a small aerospike demonstrator built by Pangea Aerospace. The aerospike is a promising solution to build more efficient engine than the actual one. Its main advantage is the expansion adaptation that allows to reach the optimal expansion in a wide range of ambient pressures delivering more thrust than an equivalent bell-shaped nozzle. The main drawbacks are the cooling system design and the spike manufacturing but nowadays, these issues seem to be overcome with the use of the additive manufacturing method. The simulations are performed with dbnsTurbFoam which is a solver of OpenFOAM. It has been designed to simulate a supersonic compressible turbulent flow. This work is divided in four chapters. The first one is a short introduction. The second one shows a brief summary of the theoretical performance of the aerospike. The third one introduces the numerical methodology to simulate a compressible supersonic flow. In the fourth chapter, the solver has been verified with an experiment found in literature. And in the fifth chapter, the simulations on DemoP1 engine are illustrated.