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Plasma synthetic jet actuators for biological indirect treatment: the role of the charged particles
Get PDFPlasma Synthetic Jet Actuators (PSJA) have demonstrated their ability to produce a flow from the surface where the Dielectric Barrier Discharge (DBD) is ignited. This ionic wind is due to the Electro Hydro Dynamic (EHD) interaction. These fluid-dynamic actuators enhance the delivery of reactive species towards the target to be treated. The long-life charged particles are generated within the plasma region and then carried on by the induced flow. The disinfection efficacy of PSJA
used to indirectly treat different pathogens was demonstrated. In particular, the inactivation effect of free charges advected by the ionic wind has been investigated. An assessment of the various factors that may affect the production and the effect of the free charges are analysed. It was observed that humidity rate weakly influences the charge deposition. Besides, the most notable effect is an increase of the deposition time for higher humidity rate. In addition, a higher applied electric field produces higher charge deposition rates. Moreover, different geometries and dielectric materials have been considered. Linear actuators have proven to be more effective in charge delivery with respect to annular actuators. The EHD interaction was measured also for a streamer corona discharge utilised for cancer cells
treatment
Development and Validation of a CO2 Sensor for Extra Corporeal Life Support Applications
Get PDFMeasurement of carbon dioxide (CO2) in medical applications is a well-established method for monitoring patient’s pulmonary function in a noninvasive way widely
used in emergency, intensive care, and during anaesthesia.
Even in extra corporeal life support (ECLS) applications, such as Extra corporeal Carbon Dioxide Removal (ECCO2R), Extra corporeal Membrane Oxygenation (ECMO), and cardiopulmonary by-pass (CPB), measurement of the CO2 concentration in the membrane oxygenator exhaust gas is proven to be useful to evaluate the treatment progress as well as the performance of the membrane oxygenator.
This thesis presents the development of a new optical sensor specifically designed for the measurement of CO2 concentration in the oxygenator exhaust gas. The project’s goal is to develop a sensor with Technology Readiness Level of 9, meaning that the developed sensor
shall also be proven and validated in the operational environment.
Initially, to allow a better comprehension of the application for which the developed sensor is intended, an overview of the ECLS application scenario is given, describing the key components of an ECLS device, as well as the most used ECLS procedures. Further, considerations about the importance of CO2 concentration measurement in the membrane oxygenator exhaust gas are reported. Then, the measurement principle for carbon dioxide concentration is described, as well as state-of-the-art technologies used in this field. Moreover, design requirements that the developed sensor should meet are analyzed and disclosed. Sensor architecture is described, focusing on the method implemented to prevent condensation of the water vapour in the membrane oxygenator’s exhaust gas. Effects of temperature on the sensor optical elements performance are addressed through theoretical and experimental analysis, and methods to avoid signal–temperature dependency are described. Finally, the results of the test performed on the developed sensor both in-vitro and in-vivo conditions are reported and discussed
Convergent bioenergetic defects in Coenzyme Q10 depleted cells by pharmacological inhibition of coq2 enzyme (p-hydroxybenzoate polyprenyl transferase) and by genome editing technology targeting the encoding gene (COQ2)
Get PDFPrimary CoQ10 deficiency diseases encompass a heterogeneous spectrum of clinical phenotypes. Among these, defect or mutation on COQ2 gene, encoding a para-hydroxybenzoate polyprenyl transferase, have been associated with different diseases. Understanding the functional and metabolic impact of COQ2 mutation and the consequent CoQ10 deficiency is still a matter of debate. To date the aetiology of the neurological phenotypes correlated to CoQ10 deficiency does not present a clear genotype-phenotype association. In addition to the metabolic alterations due to Coenzyme Q depletion, the impairment of mitochondrial function, associated with the reduced CoQ level, could play a significant role in the metabolic flexibility of cancer. This study aimed to characterize the effect of varying degrees of CoQ10 deficiency and investigate the multifaceted aspect of CoQ10 depletion and its impact on cell metabolism. To induced CoQ10 depletion, different cell models were used, employing a chemical and genome editing approach. In T67 and MCF-7 CoQ10 depletion was achieved by a competitive inhibitor of the enzyme, 4-nitrobenzoate (4-NB), whereas in SH-SY5Y the COQ2 gene was edited via CRISPR-Cas9 cutting edge technology
Novel catalytic systems and methidologies for organocatalysis and photocatalysis
Get PDFThe thesis is divided into two main parts. In the first one organocatalysis is briefly introduced. Then, new enantiopure trityl pyrrolidines modified with an ionic tag are described. All the catalysts are tested in the benchmark Michael addition reaction to prove their activity and stereoselectivity.
In the second part, photocatalysis is first introduced. Then, four different research projects are described.
At first, the construction of a hybrid metal-organo-photoredox catalyst is described. The hybrid photocatalysts obtained were employed in the benchmark photoredox alkylation of aldehydes.
Then, the use of visible light and a photocatalytic system for the cyclization of iodoaryl vinyl derivatives to tetrahydroquinoline structures is described. In addition, the reaction can also be performed using flow-chemistry. Finally, a mechanistic proposal based on some mechanistic studies is described.
Third, a new photoredox catalyzed transformation for the synthesis of 2,3-dihydrofurans is reported. Depending on the involved starting materials, different pathways have arisen. A mechanistic proposal based on reported literatures and experimental data is described.
At last, a new photoredox catalyzed transformation for the synthesis of 2-aminofurans is described. Electrophilic radical addition on allenamides and subsequential intramolecular cyclization are exploited. The reaction proceeds under very mild conditions and in 2-aminofurans are obtained in good to high yield. It represents one of the few applications of allenamides in photoredox catalysis. A mechanistic proposal is described. Finally, preliminary investigations on the applicability of the developed transformation under flow chemistry conditions
Profile graphical models
Get PDFThis thesis concerns the theory and the inference of a new class of independence models based on a graphical representation that we name profile graphs. Multiple graph models are special cases in this class and the compatibility in terms of independence structure is derived with respect to chain graph models of different types. Inference and model selection based on both Lasso methodology and Bayesian theory are studied and implemented. The thesis is composed of four chapters. In the first chapter, we present a literature review of multiple and chain graphs. Markov properties, parameterization and inference are reviewed for undirected, bidirected, LWF chain and regression graphs. In the second chapter, a class of profile graphs is introduced for modelling the effect of an external factor on the independence structure of a multivariate set of variables. Conditional and marginal independence structures are explored by using profile undirected and bi-directed graphical models, respectively. These two families of graphical models are formally defined with their corresponding Markov properties. Furthermore, necessary conditions are derived to induce, for any profile undirected and bi-directed graph model, a compatible class of chain graph models of different type known as LWF chain graph and regression graph, respectively. In the third chapter, we propose two Bayesian approaches for the selection of Ising models associated to multiple undirected graphs. We devise a Bayesian exact-likelihood inference for low-dimensional binary response data, based on conjugate priors for log- linear parameters. We also propose a quasi-likelihood Bayesian approach for fitting high-dimensional multiple Ising graphs, where the normalization constant results computationally intractable. In both methods, we define a Markov Random Field prior on the graph structures, which encourages the selection of the same edges in related graphs. Finally, in the fourth chapter we present some final remarks on Chapters 2 and 3
Mode-I fracture parameters of quasi-brittle materials: direct evaluation using DIC and relationship with Mode-II interfacial parameters
Get PDFThe objective of this thesis is the investigation of the Mode-I fracture mechanics parameters of quasi-brittle materials to shed light onto the influence of the width and size of the specimen on the fracture response of notched beams. To further the knowledge on the fracture process, 3D digital image correlation (DIC) was employed. A new method is proposed to determine experimentally the critical value of the crack opening, which is then used to determine the size of the fracture process zone (FPZ). In addition, the Mode-I fracture mechanics parameters are compared with the Mode-II interfacial properties of composites materials that feature as matrices the quasi-brittle materials studied in Mode-I conditions. To investigate the Mode II fracture parameters, single-lap direct shear tests are performed. Notched concrete beams with six cross-sections has been tested using a three-point bending (TPB) test set-up (Mode-I fracture mechanics). Two depths and three widths of the beam are considered. In addition to concrete beams, alkali-activated mortar beams (AAMs) that differ by the type and size of the aggregates have been tested using the same TPB set-up. Two dimensions of AAMs are considered. The load-deflection response obtained from DIC is compared with the load-deflection response obtained from the readings of two linear variable displacement transformers (LVDT). Load responses, peak loads, strain profiles along the ligament from DIC, fracture energy and failure modes of TPB tests are discussed. The Mode-II problem is investigated by testing steel reinforced grout (SRG) composites bonded to masonry and concrete elements under single-lap direct shear tests. Two types of anchorage systems are proposed for SRG reinforced masonry and concrete element to study their effectiveness. An indirect method is proposed to find the interfacial properties, compare them with the Mode-I fracture properties of the matrix and to model the effect of the anchorage
Low codimensional intrinsic regular submanifolds in the Heisenberg group H^n
Get PDFThe thesis mainly concerns the study of intrinsically regular submanifolds of low codimension in the Heisenberg group H^n, called H-regular surfaces of low codimension, from the point of view of geometric measure theory. We consider an H-regular surface of H^n of codimension k, with k between 1 and n, parametrized by a uniformly intrinsically differentiable map acting between two homogeneous complementary subgroups of H^n, with
target subgroup horizontal of dimension k. In particular the considered submanifold is the intrinsic graph of the parametrization. We extend various results of Ambrosio, Serra Cassano and Vittone, available for the case when k = 1. We prove that the uniform intrinsic differentiability of the parametrizing map is equivalent to the existence and continuity of its intrinsic differential, to the local existence of a suitable approximating family of Euclidean regular maps, and, when the domain and the codomain of the map are orthogonal, to the existence and continuity of suitably defined intrinsic partial derivatives of the function. Successively, we present a series of area formulas, proved in collaboration with V. Magnani. They allow to compute the (2n+2−k)-dimensional spherical Hausdorff
measure and the (2n+2−k)-dimensional centered Hausdorff measure of the parametrized H-regular surface, with respect to any homogeneous distance fixed on H^n.
Furthermore, we focus on (G,M)-regular sets of G, where G and M are two arbitrary Carnot groups. Suitable implicit function theorems ensure the local existence of an intrinsic parametrization of such a set, at any of its points. We prove that it is uniformly
intrinsically differentiable.
Finally, we prove a coarea-type inequality for a continuously Pansu differentiable function acting between two Carnot groups endowed with homogeneous distances. We assume
that the level sets of the function are uniformly lower Ahlfors regular and that the Pansu
differential is everywhere surjective
Representations and narrations of Africa in 1960s Italy
Get PDFAttraverso l’analisi di settimanali illustrati, film, programmi televisivi, reportages di viaggio, questa tesi vuole offrire un’ampia panoramica sulle rappresentazioni africane più diffuse nella società italiana degli anni Sessanta. L’indagine considera un decennio di transizione sia per l’Italia che per l’Africa: mentre la prima, dopo aver perso Libia, Eritrea ed Etiopia durante la Seconda guerra mondiale, termina l’amministrazione fiduciaria in Somalia, la seconda è attraversata dalle lotte di liberazione e celebra la nascita dei nuovi Stati indipendenti, finalmente libera di immaginarsi svincolata dalle ingerenze europee.
I casi studio presentati fanno emergere i vari aspetti dello sguardo italiano al continente africano: reticente nel riconoscere le potenzialità dei nuovi Stati e ancora viziato da una forte componente esotica e coloniale, fatica a considerare l’Africa parte della Storia mondiale, ritenendola ancora semplice meta per eccellenza delle fughe esotiche occidentali. Per quanto riguarda gli ex territori coloniali italiani, essi fanno molto spesso la loro apparizione sulle pagine delle riviste perché sfondo necessario per i racconti delle gesta eroiche dell’esercito italiano in Libia e in Africa Orientale. A queste rappresentazioni ne vengono affiancate altre, più marginali e militanti, che rivelano altri modi attraverso i quali l’immagine del Continente circolasse nei media del periodo: l’Africa e il suo desiderio di futuro, esempio per i vari soggetti rivoluzionari globali, pienamente inserita nella Storia, e l’Africa come continente in movimento, finalmente liberato dall’immobilità del mito.Through the analysis of illustrated magazines, films, television programmes, travelogues, this thesis aims to offer a broad overview on the most widespread representations of Africa in 1960s Italian society. The study examines a decade of transition for both Italy and Africa: while the former, after losing Libya, Eritrea and Ethiopia during the Second World War, ends its trusteeship in Somalia, the latter is in the midst of liberation struggles and celebrates the birth of the new independent states, finally free to imagine itself emancipated from European influence.
The case studies presented highlight the various aspects of the Italian view on the African continent: reluctant to recognise the potential of the new states and still marked by a strong exotic and colonial component, it struggles to consider Africa as part of world history, still holding it to be a simple destination par excellence for exotic Western escapes. As far as the former Italian colonial territories are concerned, they very often appear in the pages of magazines as a necessary background for the stories of the heroic deeds of the Italian army in Libya and East Africa. Alongside these representations are other, more marginal and militant ones, which reveal other ways in which the image of the Continent circulated in the media of the period: Africa and its desire for the future, an example for the various global revolutionary actors, fully embedded in History, and Africa as a continent in motion, finally freed from the immobility of myth
Positive and negative intergroup contact from the perspective of immigrants: Their impact on acculturation strategies and psychological adjustment
Get PDFSocial psychologists only recently started to examine the effects of both positive and negative intergroup contact on intergroup attitudes of minority groups. However, little is yet known about the joint and differential effects of these two forms of contact on immigrants’ adaptation. Basing on this, it was examined the joint and differential effects of positive and negative contact on immigrants' acculturation and adjustment in their host society across four studies. Study 1 and Study 2 investigated the joint effect of positive and negative contact on immigrants’ fear of being stereotyped, perceived symbolic threat, social avoidance, and anxiety in two different contexts (Italy and Turkey). Consistently across the samples, negative contact was a strong predictor of fear of being stereotyped, perceived symbolic threat, and social avoidance. Only in the Italian sample, where respondents reported negative contact experiences with native people to a greater extent, positive contact was not associated with reduced avoidance of them. Study 3 and Study 4 considered cross-sectionally and longitudinally other crucial aspects of the adaptation process, such as acculturation preferences and psychological adjustment of immigrants. Study 3 highlighted that positive contact strongly predicted positive outcomes (i.e., culture adoption and psychosocial well-being), whereas negative contact predicted negative outcomes (i.e., group discrimination and post-traumatic stress disorder). Study 4 displayed the role of negative contact as a stronger predictor of psychosocial well-being and culture maintenance over time. Overall, evidence highlighted the crucial role of both positive and negative intergroup contact, their interplay, and the underlying processes in shaping immigrants’ adaptation to their contexts
Musical tension in harmonic intervals: behavioral and neural correlates
Get PDFMusical tension is what drives our emotional experience in music listening. However, the specific role of the musical elements involved in tension-resolution perception remains largely unclear. This dissertation aims to advance the understanding of tension perception dynamics related to sensory consonance-dissonance.
The first experiment aimed to design and validate a new crossmodal proprioceptive device for tension rating that overcomes some of the limitations of known tools. As a result, a psychophysical equation for the matching of physical force and psychological force was presented.
The same tool was subsequently used in the second and third experiments to collect ratings of perceived tension and movement in harmonic musical intervals and standard noises. Besides, a visual analog scale (VAS) was used to allow a comparison of these two methods. The results confirmed the close relationship between sensory dissonance and perceived tension. Moreover, stimuli in the higher pitch register were perceived as more tense, confirming the primary role of pitch as a mediator of tension. The comparison between ratings obtained with the proprioceptive device and the VAS highlighted the tendency to give higher tension ratings using the VAS compared to the proprioceptive device.
In the last experiment, brain electrical activity was recorded during the presentation of short tension-resolution patterns created using the most tense (perfect unison, fourth, and fifth) and the least tense harmonic intervals (augmented fourth, minor second, and inverted major seventh) to understand how consonance-dissonance can convey meaningful information on perceived tension-resolution. Results showed overall larger effects during the ‘resolution’ condition compare to the ‘tension induction’ condition, indicating that the resolution of harmonic instability towards a state of stability may be more salient than its opposite. A late positive component (LPC) was elicited, possibly reflecting deeper processing of tension-related meaning within a minimal harmonic context