Dipartimento di Fisica - Tesi di Dottorato

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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Fisica dell'Università della Calabria.

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    Chemical characterization of atmospheric aerosols from natural and anthropogenic sources in the Mediterranean area
    (Università della Calabria, 2019-10-14) Moretti, Sacha; Carbone, Vincenzo; Sprovieri, Francesca; Naccarato, Attilio
    The Mediterranean Sea basin constitutes a semi-enclosed area where atmospheric particles originating from natural and anthropogenic continental sources and gas-to-particle conversion processes are present at all times. The area is, in fact, located to the south of highly populated European countries characterized by industrial, semi-industrial, and rural economies, and to the north of Africa, which includes the Sahara desert. Detailed wind trajectory analysis reported in previous research studies show that more than 60% of air masses crossing the Mediterranean originate from the north-northwest sector, containing particles emitted or derived from industrial and urban sources, whereas 13–16% of air masses coming from the Sahara region carrying predominantly mineral dust. The transport of Saharan dust occurs mostly during the spring and summer seasons and causes sporadic crustal aerosol pulses to the Mediterranean area. On the other hand, aerosol scavenging by precipitation during the rainy season (from October to May) reduces aerosol concentrations. Summer is also characterized by low inversion layers and strong sunlight conditions, causing photochemical smog. Moreover, forest fires, which occur during the summer months in the Mediterranean region and in North Africa, increase black carbon and fine particle emissions. In this frame, it is clear enough that specific meteorological conditions result in high temporal variability of aerosol concentrations. There is strong evidence on the relationship between short-term and long-term exposure to atmospheric particles, with adverse health effects. Therefore, the study on atmospheric Particulate Matter (PM) (solid or liquid particles dispersed in the atmosphere which may persist for long times to undergo transport and diffusion phenomena), and the relative chemical composition of the two particle size fractions PM2.5, (aerodynamic diameter ≤ 2.5 μm) and PM10 (aerodynamic diameter ≤ 10 μm), is essential to evaluate the effect of the PM on human health and environment. The present work of thesis developed during the Ph.D. is focused on the chemical characterization of aerosol in the Mediterranean area through a monitoring program which has foreseen a number of oceanographic campaigns performed in the Mediterranean sea onboard the CNR-research vessel in the framework of the ongoing MEDOCEANOR measurements program as well as long-term measurements carried out on-land, specifically at the high altitude GAW observatory “Monte Curcio” of the CNR-IIA (1780 m a.s.l.), located on the Sila massif, Southern Italy, and thus able to intercept long-range transport air masses and across a number of monitoring sites (i.e., coastal, urban, rural sites etc.) distributed in the south of Italy as part of the I-AMICA regional network. The concentration of aerosol size fractions and its chemical composition performed at permanent ground-based stations as well as during oceanographic measurement campaigns have been analyzed in order to assess a spatially and temporally consistent measurement data across Mediterranean basin, and to investigate the main natural and anthropogenic sources affecting the air quality using source apportionment techniques. The seasonal oceanographic campaigns developed along different routes in the western sector of the Mediterranean Sea basin, and aimed to study the influence of natural and anthropogenic sources of PM and associated levels of pollutants. Chemical analysis assisted by the receptor models, identified, in particular, six main sources: crustal, volcanic, biomass burning, marine spray, industrial and vehicular traffic. The carbonaceous content in the PM sampled in Monte Curcio station shows seasonal trends for Organic Carbon (OC) and Elemental Carbon (EC) in both PM size fractions. The concentrations during the warm season are higher than those observed during the cold season and the annual levels of EC and OC were lower than those observed at the other four monitoring sites as part of the regional network “I-AMICA” distributed in southern Italy (Capo Granitola, Lamezia Terme, Lecce; Naples) due to different environmental conditions (eg, coastal/marine, suburban and urban) characterizing these sampling sites compared to “Monte Curcio” remote site. In particular, both OC and EC average concentrations were minimal at Monte Curcio and increased in the following order: remote < coastal/marine < suburban < urban (i.e., Monte Curcio < Capo Granitola < Lamezia Terme < Lecce < Naples). The Secondary Organic Carbon (SOC) was mainly present in PM2.5 at all sites, and higher SOC/OC ratios were observed at the urban and suburban site. Indeed, the yearly average SOC in Monte Curcio station has been estimated as 52% of OC in PM2.5 and representing, on average, the major mass contributes to PM2.5 during the cold season. Furthermore, the receptor models used shown differences among the possible sources of carbonaceous aerosol between different seasons. The cold season was characterized by aerosol mainly coming from the long-range transport, while during the warm season it is influenced by local and regional sources. In the following Chapters, the results have been presented and discussed.
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    Optimal design and numerical modelling of imperfection sensitive shell structures
    (Università della Calabria, 2020-02-24) Liguori, Francesco Salvatore; Garcea, Giovanni; Bartolino, Roberto
    A brand-new design philosophy tends to harness the load-carrying capacity hidden beyond the onset of buckling phenomena in shell structures. However, when designing in the postbuckling range, among other effects, attention should be given at imperfection sensitivity which may generate catastrophic and unexpected consequences on the optimised structures. Therefore, what would be necessary is an optimisation strategy able to deal with the complex geometries of full-scale structures and, meanwhile, efficiently gather the complexity of their postbuckling response. The aim of this work is to meet this demand by proposing numerical methods that face the problem from different sides, namely the geometrically nonlinear description of the shell, the solution algorithm and the optimisation strategy. As a starting point, a convenient format to describe geometrically nonlinear shell structures is identified in the solid-shell model. On the basis of this model, a discretised environment is constructed using isogeometric analysis (IGA) that, by taking advantage from the high continuity of the interpolation functions, leads to a reduced number of variables with respect to standard finite elements. Afterwards, an IGA-based multimodal Koiter’s method is proposed to solve the geometrically nonlinear problem. This method meets the aforementioned requirements of efficiency, accuracy and is capable of providing information on the worst-case imperfection with no extra computational cost with respect to the analysis of a perfect structure. Additionally, a new strategy for improving the accuracy of the standard version of Koiter’s algorithm in the presence of geometrical imperfections is devised. The last part of the thesis concerns the optimal design of full-scale structures undergoing buckling phenomena. In particular, the design focuses on variable angle tow laminates, namely multi-layered composites in which fibre tows can describe curvilinear paths, thereby providing great stiffness-tailoring capacity. Two optimisation strategies are proposed, both based on the use of Koiter’s method to evaluate the postbuckling response. The first one makes use of a fibre path parameterisation and stochastic Monte Carlo random search as a global optimiser. The second one is based on direct stiffness modelling using lamination parameters as intermediate optimisation variables that lead to a reduction of the nonlinearity of the optimisation problem and remove the direct dependence from the number of layers.
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    Ion energization in the terrestrial magnetosphere
    (Università della Calabria, 2019-10-29) Catapano, Filomena; Zimbardo, Gaetano; Delcourt, Dominique; Carbone, Vincemzo; Retinò, Alessandro
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    Optical and mechanical responses of liquid crystals under confinement
    (Università della Calabria, 2020-11-25) Zheng, Weichao; Cipparrone, Gabriella; Zappone, Bruno
    The optics of liquid crystals (LCs) lay an important foundation for LC displays and the mechanics of LCs are the backbones of LC elastomers that are promising materials for artificial muscles. Despite broad prospects for applications, it is still a challenge to precisely measure both optics and mechanics at the nanoscale. Here both optical and mechanical responses are simultaneously probed by the Surface Forces Apparatus to understand how optical anisotropies of LCs interact with the birefringence of the mica, and how mechanical anisotropies of LCs interact with anchoring conditions and the confinement. Optically, the birefringence of nematics adds complexities to the two intrinsic birefringent mica surfaces for multiple-beam interference. The phase retardation by multiple birefringent layers is a result of composition by the phase retardation from each layer and their relative intersection angles, which is intuitively understood by the parallelogram rule that is similar to the geometrical composition of forces but with double intersection angle. The simulation based on 4x4 matrices is used to reconstruct the interaction of fringes and to compare the deviation of average wavelengths in the same chromatic order and isotropic wavelengths generated by the average refractive indices. Mechanically, LC behaviours result from the competition among surface anchoring, elasticity of LCs and confinements. During the retraction of surfaces, the neck of cholesteric layers is broken by the innermost circular dislocation defect that serves as a bulk crack with the opening mode of fracture, producing periodical twist transitions and structural forces. During the approach of surfaces, three regimes, constrained, stick-slip and sliding-slip, of cholesteric mechanical windings are observed with the time evolution of the surface anchoring. The onset of three regimes and the retardation of twist transitions results from the balance between the twist elastic torque and the frictional surface torque, namely the anchoring torque and the viscous torque, which is analogous to friction torque in rotational friction. The deviation of the anchoring angle on surfaces provides evidence of interfacial ruptures, with tearing or sliding mode, described by the paradigm of fracture mechanics for the onset from static frictions to kinetic frictions. This thesis sheds light on the understanding of boundary effects on permeative flows, frictions, fractures, yield stress materials, adhesions and biomechanics.
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    Monitoring of mercury and organic pollutants in differents environmental compartments through traditional and innovative approaches
    (Università della Calabria, 2020-10-20) Tassone, Antonella; Cipparrone, Gabriella; Sprovieri, Francesca; Naccarato, Attilio
    Negli ultimi decenni il problema dell'inquinamento ambientale ha acquisito notevole importanza su scala globale sia per il continuo aumento dei livelli di inquinanti che per l'introduzione di nuovi contaminanti. Gli effetti tossici sulla salute umana e sugli ecosistemi rappresentano la più grande minaccia di questi inquinanti. Pertanto, negli ultimi anni la comunità scientifica si è impegnata nel monitoraggio questi inquinanti in tutti i settori ambientali, come aria, acqua, suolo e sistemi viventi con lo scopo di garantire un controllo rigoroso della loro presenza nell'ambiente e successivamente regolamentarli. Infatti, le diverse proprietà fisico-chimiche delle varie sostanze fanno sì che siano distribuiti nei vari comparti secondo un preciso ciclo biogeochimico. È per questo motivo che studi di monitoraggio adatti a ciascun comparto ambientale sono necessari. Nella maggior parte dei casi, i metodi analitici impiegati si basano su tecniche obsolete, che non trovano impiego per via dell’uso di sostante nocive o di un grande dispendio di tempo e risorse. In questo contesto, esiste una domanda crescente di metodi analitici innovativi, rapidi, eco-compatibili, a basso costo, semplici da impiegare. Il lavoro di ricerca presentato in questa tesi riguarda il monitoraggio del mercurio e di alcuni inquinanti organici emergenti, quali esteri organofosfati, benzotriazoli, benzotiazoli e benzosulfonammidi, mediante l’impiego di approcci analitici sia tradizionali che innovativi. Lo studio condotto durante il corso del dottorato ha riguardato l’indagine di diversi settori ambientali, come l’ambiente atmosferico di vari siti, interessati da fonti di inquinamento antropiche oltre che naturali. Inoltre, oggetto d’indagine sono stati anche l'ambiente acquatico del Mar Mediterraneo e il biota campionato in terreni agricoli di San Giovanni in Fiore (CS). Inoltre, lo studio del particolato atmosferico è stato condotto attraverso lo sviluppo di nuovi metodi analitici eco-compatibili per la determinazione di esteri organofosfati, benzotriazoli, benzotiazoli e benzosulfonammidi mediante estrazione mediata da microonde seguita da microestrazione in fase solida e quantificazione mediante gascromatografia-spettrometria di massa tandem. In the last decades, the issue of environmental pollution has acquired considerable importance at a global scale due to both the continuous increase in pollutant levels and the introduction of new contaminants. The toxic effects on human health and other ecosystems represent the greatest threat posed by these pollutants. Therefore, with the aim to ensure a strict control of their presence in the environment and subsequently regulate them, in recent years the scientific community has engaged in monitoring these pollutants in all environmental sectors, such as air, water, soil and living systems. Indeed, the different physico-chemical properties of the various substances ensure that they are distributed in the various compartments according to their own biogeochemical cycle. It is for this reason that monitoring studies suitable for each sector are necessary. In most cases, the analytical methods traditionally used are obsolete, relying on techniques that are no longer used. In this context, there is a growing demand for innovative analytical methods, which are fast, environmentally friendly, low cost, simple to use. Among the major ambient pollutants, the research work presented in this thesis is addressed to the monitoring of mercury and some emerging organic pollutants, i.e. organophosphate esters, benzotriazoles, benzothiazoles, and benzenesulfonamides, exploiting both traditional and innovative approaches. The investigation concerned the atmospheric environment of various sites affected by anthropic as well as natural emission sources, the aquatic environment of the Mediterranean Sea and the biota specimen collected in croplands from San Giovanni in Fiore (CS). Furthermore, the airborne particulate matter was monitored as an environmental matrix with the aim to detect organic pollutants through the use of new eco-friendly analytical methods.
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    X-RAY PHASE-CONTRAST TOMOGRAPHY APPLIED TO VIRTUAL UNFOLDING OF HERCULANEUM PAPYRI
    (Università della Calabria, 2020-11-11) Stabile, Sara; Cipparrone, Gabriella; Cedola, Alessia; Bukreeva, Inna
    In 1750 a large villa on a hill overlooking Herculaneum and the Bay of Naples was discovered. This villa probably once belonged to the wealthy Roman aristocrat Lucius Calpurnius Piso Caesoninus, a well-known Roman politician, who was a patron of Epicurean philosophers. The villa was lost from history in A.D. 79 in the catastrophic eruption of Mount Vesuvius when it was buried by tons of thick volcanic mud which gradually hardened to a concrete-like consistency. During villa excavations, workers discovered many important works of art and an impressive library of some 1800 papyri rolls - thus the name Villa of the Papyri. The library consists of a remarkable collection of Epicurean philosophical texts written in Greek, and a lesser number of Latin texts. Due to the intense heat of the volcanic flow and the pressure exerted by the weight of mud, lava, pumice, and rubble, these rolls are extremely fragile, lost more or less the original cylindrical shape, and the individual sheets stuck together tenaciously. Since their discovery, numerous efforts have been made to open the carbonized-Herculaneumpapyri and read the priceless information contained in them employing several manual and destructive techniques. My Ph.D. research work concerns the study of Herculaneum papyri using a non-destructive X-ray technique and a new set of numerical algorithms for ‘virtual-unrolling’. In particular, I used X-ray-micro-computed tomography (μX-CT) and X-ray Phase Contrast Tomography (XPCT) as powerful non-destructive testing techniques for the full-volume inspection of the papyri, able to give morphological and physical information on the inner structure of the investigated sample. I analyzed three Herculaneum papyri fragments: PHerc.1103 and PHerc.1105 belonged to the scroll exterior part, scorza, and PHerc.110 belonged to a papyrus partially unrolled in 1867. The main purpose of my research work was building a computational platform for the virtual 3D investigation of the Herculaneum papyri fragments. Due to the poor conditions of the fragments, virtual operations on the 3D tomographic images, such as segmentation and flattening of the papyrus sheets, result complicated and require an approach developed specifically for this particular task. In this thesis, I describe in detail this computational platform, which is the composite result of 3D data digitisation, segmentation, modelling, flattening and texture mapping of papyrus sheets. Following 3D data digitisation, the segmentation step is presented, thanks to which I can digitally identify the single papyrus sheet within the volume. After the sheet surface is modeled using triangular meshing, preferred to other kinds of mesh because it simplifies the math and allows for faster operations. Finally, I focus on the parameterization methods for unfolding sheet with minimum distortion. Once the good parametrization method has been identified, the next step is texturing, i.e., assignment of 3D color information to each point on a 2D mesh. The resulting texture reveals the features of the flattened sheet. Besides, investigations on different phase retrieval approaches have been performed. I implemented and tested three of the widespread methods to find the best one. Another challenging problem, due to the ring artifacts present in the reconstruction that disturbs the image impression, was resolved through algorithms adapted to this particular case. The artifacts removal process allowed the visualization of clean slices and helped to reveal traces compatible with writing. It has so been demonstrated the benefit of applying the XPCT technique to trace handwriting. Some of the results of this research are reported in the following paper has been accepted for publication: Stabile S., et al., Computational Platform for the virtual unfolding of Herculaneum Papyri, Sci. Reports.
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    Monte Carlo neutronic calculations for the design of VESPA shielding at the European Spallation Source
    (Università della Calabria, 2020-12-14) Scionti, Jimmy; Cipparrone, Gabriella; Agostino, Raffaele Giuseppe; Gorini, Giuseppe
    The European Spallation Source (ESS) is the next world’s most powerful pulsed neutron source, under construction in Lund, in the south of Sweden. Many scientific and industrial fields will benefit from ESS, like pharmaceutical drugs, manufacturing, biotechnology, information technology, chemistry, and so on. The facility will produce neutrons by spallation reactions, induced by high energetic protons, accelerated up to the energy of 2 GeV and eventually conveyed to impinge on a rotating tungsten target. Neutrons will then pass through a complex moderator system and will be delivered to the experimental stations of a suite of instruments through dedicated beamlines. Each instrument has a unique experimental station, neutron guide and design that are optimized and conceived for a specific scientific research field. ESS will be capable of producing neutrons with energies up to that of the incident proton beam. Such high energetic neutrons constitute a matter of particular care for radiological protection purposes. In fact, neutrons represent a higher concern respect to charged particles due to the fact that they carry no electric charge. Therefore, they can’t interact with matter by mean of the coulomb force, which dominates the energy loss mechanism for charged particles. In particular slow neutrons, of energy up to a few eV, are likely to be absorbed by the atomic nuclei by radiative capture reactions, that lead to the emission of gamma particles. Similarly to neutrons, gammas carry no electric charge, but their interaction mechanisms in matter differ from those of neutrons, and depend on the atomic number Z of the nuclei [1]. Both neutron and gamma radiations are an issue for radiological protection in neutron facilities, due to their higher penetrability respect to charged particles. In particular, being able to attenuate and shield that radiation down to acceptable limits is a crucial aspect within the ESS project. The radiological shielding of each component of the facility, from the accelerator down to the beam-lines, is an essential matter of studies and investigations at ESS. Shielding studies can be thought as a type of optimization studies. In fact, the typical purpose is to minimize a radiological quantity, usually the dose, in some particular area of interest, by choosing appropriate materials. The choice is bound to the attenuating capability of the selected materials for the given radiation, to the cost and to the available space that set geometrical constraints. The studies described in this thesis are focused on the design of an appropriate shielding for the beam-line of VESPA, one of the instruments under construction at ESS. VESPA is a joint venture between Consiglio Nazionale delle Ricerche (CNR, Italy) and Science and Technology Facilities Council (STFC, United Kingdom). The acronym VESPA stands for Vibrational Excitation Spectrometer using Pyrolytic-graphite Analyser. As the name suggest, it is a high-resolution broadband chemical spectrometer, enhanced with diffraction capabilities, fully dedicated for in-situ research. It will be capable of providing simultaneous dynamic and structural data on chemical bondings, intra-molecular and inter-molecular interactions and on the vibrational dynamics. VESPA is a 60m long straight instrument, in line of sight with ESS moderator. Most of the instrument, about 45 m, will be built in an area that will be frequently accessed by workers, scientists, ESS personnel and so on. Therefore, the radiation coming from the instrument has to be strongly attenuate by an adequate shielding structure, so to not constitute a radiological hazard. The studies for the shielding of VESPA presented here, were performed by mean of the Monte Carlo transport code MCNP and auxiliary codes like CombLayer and ADVANTG. The investigation benefited from the Common Shielding Project at ESS, that aims to standardize the shielding structures for all the participating instruments, as well as to provide a common teamwork for discussing and validating the investigations. Part of this thesis aims to describe the Monte Carlo method, with a particular care for the variance reduction techniques, especially those that were used in the MCNP calculations. A large part of the thesis is related to the characterization of the sources used in the simulations. The shielding for VESPA is investigated through studying the neutron and photon dose rate maps. The proposed design, in compliance with the Common Shielding requirements and the dose requirements, is given toward the end of the thesis. The last chapter of the thesis is an addendum about the early simulations aimed to design an essential component of the instrument.
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    Identification of Brain Structures and Functional Cortico - Muscular Networks: Machine Learning Object Recognition and Network Physiology Approach
    (Università della Calabria, 2020-03-05) Rizzo, Rossella; Critelli, Salvatore; Pantano, Pietro; Ivanov, Plamen
    The brain is the most complex part in the human body. This organ is responsible for our intelligence, interpreting sensation, initiating body movement, and controlling all of our behaviors. Over hundreds of years, scientists have learned much about the brain, from a microscopic and macroscopic point of view. We now know the general rules under which information is transferred from neuron to neuron and we can differentiate between various brain structures and brain areas, each of them responsible of a particular function in the human organism. However, due to the vast complexity of the brain, much remains to be discovered. Researchers continue to explore the mechanics regulating a healthy brain that functions quickly and automatically, but we are still at the point where much work remains to identify the key differences between a physiological and a pathological situation in anatomic brain structures and functionality of the brain. The lack of information in this sense affects the diagnostic process of many neurodegenerative disorders, that can be discovered only from the symptoms shown by the subject and that, therefore, can be treated to reduce the pain and to give better conditions of life. The present research aims to better understand anatomic brain structures and functional interactions networks in the brain in order to early diagnose the most common neurodegenerative diseases. In the framework of the investigation of the anatomic brain structures the Neuroimaging is the most powerful tool used in basic research and clinical field. The Magnetic Resonance Imaging (MRI) is one of the most recent techniques of brain imaging and largely used for its low degree of invasion in the human body. It can provide valuable information in the detection of morphological markers that can highlight on the healthy status of the subject. A fundamental step in the pre-processing and analysis of magnetic resonance images is the individuation of the Mid-Sagittal Plane (MSP), where the mid brain is located, in order to set a coordinate reference system for the MRI scan images, and to precisely measure small changes in the surfaces, volumes and distances between different brain areas, which are used as biomarkers in the diagnostic process of certain diseases, such as Parkinson, Alzheimer, Progressive Supra-Nuclear Palsy. In this regard, part of the present research involves the improvement of brain MRIs analysis, with the use of machine learning techniques applied for the automatic identification of the MSP. In particular, the proposed method, Image Pixel Intensity (IPI) algorithm, is implemented in MatLab and is based on the k-mean, which allow to automatically segment the 2D MRIs in different brain tissues, and automatically identifies the slice where the brain tissues are most distinct from each other exploiting the intensity of the resonance signal expressed in the MRI by the color of the grayscale pixels. The results of this algorithm have been compared with the evaluation of four medical experts who manually identified the Mid-Sagittal, providing an average percentage error of 1.84%, and demonstrating that the proposed algorithm is promising and could be directly incorporated into larger diagnostic support systems. Following the main aim of the present research, the early diagnosis of neurodegenerative diseases, another machine learning technique, elastic net, has been implemented in Matlab in order to automatically predict the brain age, exploiting relationships involving the amount of gray matter present in the brain of the subjects analyzed, through a structural MRI study. The outcome of this work is the identification of profound correlations between the expected brain age and the general cognitive state: semantic verbal fluidity, processing speed, visual attention and cognitive flexibility, and visual attention and cognitive flexibility. Among the neurodegenerative diseases Parkinson lately acquired particular interest, due to its growing diffusion even within forty years old patients. This led to the study of functional interactions networks between the brain and the locomotor system during different sleep stages. Electroencephalography (EEG) and electromyography (EMG) data of healthy subjects and Parkinson's patients have been analyzed highlighting the correlations between different frequency bands present in the electrical signals emitted in the different brain areas and in the muscles of the chin and leg. Synchronous bursts in electrical activity signals in the brain and muscles have been analyzed, using the innovative method of Time Delay Stability (TDS), based on the cross-correlation function in consecutive time windows between two different signals. Links between the different frequency bands of different brain areas and the muscles with a long stable delay of the peak in the cross-correlation function are considered more stable, then stronger. The same analysis has been conducted on healthy and Parkinson's subjects, showing substantial differences in the networks of cortico-muscular interactions involving different frequencies between a physiological situation and a pathological one. Each sleep stage is uniquely identified by a particular pattern in the brain-muscle interactions. For Parkinson’s subjects these functional patterns change during each sleep stage; moreover, in general the strength of the links decreases during wake and light sleep but increases or remains the same during REM and deep sleep, especially for the brain-leg interactions, showing that during the waking phase the brain is not able to adequately control the muscles of the lower limbs. Analyzing in details the behavior of muscles the electric activity of different muscle fibers has been studied, considering subjects of different age groups (children, young adults and elderly subjects) in situations of stress or rest. In particular, EMG signals from the muscles of the leg and the back have been taken into account. The analysis shows that rest and stress have very different patterns, due to the different types of muscle fibers involved and how they behave during muscle relaxation and contraction; these relationships also change with age, identifying patterns that uniquely identify the age of the subjects analyzed and also vary during the same exercise by marking the precise point at which the subject reaches fatigue first and exhaustion afterwards.
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    Sviluppo di materiali innovativi per adsorbimento H2 e realizzazione di una unità dimostrativa di bombola
    (Università della Calabria, 2020-09-05) Pedicini, Rolando; Cipparrone, Gabriella; Agostino, Raffaele Giuseppe
    The research activity carried out during this three-year of PhD was directed towards the synthesis of new materials for the hydrogen storage. In particular, the PEEK was used as a basic polymeric matrix; this is an aromatic polymer, heat-resistant of which many properties are known. This base material does not show such chemical-physical characteristics that it can be used to bind and release H2 molecules, moreover, not being a porous material, cannot even think of a physical bond with H2. A functionalization reaction was necessary in which a certain percentage of chlorosulfonic groups on the aromatic ring of the polymer was introduced. This reaction resulted in both a slight increase in the surface area (from 9 to 19 m2/g) and also a morphological variation of the material was observed. To give the possibility to hydrogen to bind, presumably in a chemical way to the polymer, the chloride was exchanged with the permanganate ion, coming from a solution of KMnO4, that act like a precursor, which in an acidic environment is reduced to MnO2. The importance of the synthesis parameters such as time and temperature and the concentration of the precursor was verified. From the study of these parameters, different materials have been synthesized with a metal oxide load ranging from 7 to 80 wt%. The X-ray study showed that the Mn oxide synthesised is of the Birnessite type, having a characteristic lamellar structure, needle-like structure with characteristic peaks located at 2q = 12 °, 37 ° and 66 °. It was found that the increase in the percentage of oxide in the composite material is almost directly proportional to the absorption capacity. From absorption measurements by Sievert apparatus at 110 °C / 60bar, particularly interesting results were obtained, reaching 1 wt% of H2 absorption with materials having a load of 80 wt% of Mn oxide. It has been seen how the increase of the synthesis temperature at 80 °C and 95 °C does not involve any variation from the H2 adsorption but changes, probably, the structure of the oxide clusters which tend to be smaller in size. Moreover, from post volumetric measurement analysis, evident differences were found, in fact the initial MnO2 (IV) was reduced in Mn2O3 (III). For this reason, the synthesis temperature was decreased to 50 °C, reducing the analysis temperature from 110 °C to 50 °C by operating at 40 bars, in these conditions, over 3 wt% of H2 absorption was revealed, moreover, a reversible trend after three cycles of abs / des was obtained. These results seem to suggest a chemical interaction between hydrogen and the material. This material was then selected as an absorbent material to be introduced into a laboratory prototype tank (having a volume of 20L) that powered a 10W fuel cell. After increasing the material synthesis from 2 to 10 g, leaving all the chemical-physical and H2 absorption properties unaltered, the tank was designed considering some of the basic characteristics of the material. To characterize the tank two tests were designed: an electrochemical one in which the prototype was directly connected to the tank and the cell power and its life in real time was followed. Through this test, a power system had achieved a value of about 10W for an average time of 6min, less than the expected time of 20min, due to H2 losses in the tank / cell system. This problem was also recorded using the other method through mass flow and P sensors at the inlet and outlet of the tank. Considering that the system is a small demonstration developed on a laboratory scale and the components used were probably unsuitable for this purpose, by making the necessary changes and shrewdness, the H2 losses can be eliminated and, consequently, the life of the tank can reach the ideal value.
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    Radon measurement techniques in building materials and water using Italian and Ecuadorian samples
    (Università della Calabria, 2020-11-25) Orbe Ordóñez, Jheny; Cipparrone, Gabriella; Capua, Marcella
    Several studies have widely shown that there is a strict correlation between radon exposure and potential health hazard to the population. The indoor radon concentration depends on the radon exhalation from soil and building materials and radon in the domestic water supply. Accurate knowledge of the exhalation rate of building materials and radon concentration in drinking water plays an important role in reducing the risk for the population. Detailed research is being carried out into the measurements of the ex- halation rate of building materials and numerous publications are available. However, analysis of published results shows that a standard measurement protocol would be necessary and is not yet available. As regards the assessment of radon gas content in source water, interna- tional protocols are available, however, the high dependence of measurements on numerous parameters, both environmental and instrumental, it still re- quires studies to choose the most suitable instrumentation and procedure in particular circumstances and in measurement campaigns. This thesis presents the results of studies aimed at contributing to the realization of a protocol for measuring the radon exhalation rate in building materials. In addition, it presents the results of measurements of radon in wa-ter intended for human consumption under di erent experimental conditions. Standard instruments have been used for this purpose, such as scintillation chambers, gamma spectrometry, electrets and a radon chamber built in our laboratories. The emphasis will be on the work carried out with the radon chamber built for the research on the exhalation rate and adapted by us, for the rst time, for radon gas concentration measurements in water. The results obtained with the radon chamber are in excellent agreement with those obtained with the commercial instrumentation but the measure-of the measurements in water on di erent environmental parameters. Of no less importance is the fact that the studies were conducted in paral- lel in Italy, in the physics department of the University of Calabria (UNICAL) and in the analogous laboratory of the physics department at the Escuela Su- perior Polit ecnica de Chimborazo (ESPOCH) in Riobamba, Ecuador, where a radon chamber twin to the Italian one was built. Samples of Italian tu were taken to the ESPOCH laboratoryfor a com- parison of the measurements of the exhalation rate. In both laboratories exactly the same protocol was used, but each was equipped with an inde- pendent radon chamber and di erent instrumentation. Despite the di erent experimental and environmental circumstances, the results obtained are in excellent agreement with what was observed at UNICAL and con rm the quality of our protocol. With our protocols were studied di erent samples: Italian and Ecuado- rian building materials, commonly used in the construction of houses and buildings and water samples collected from wells and springs of the Calabria region in Italy and the Chimborazo province in Ecuador. The results of the radon exhalation rate of the analyzed materials show a wide variability due to the di erent physical and chemical properties of the samples. The results range from the minimum detectable to 0.86 Bq kg􀀀1 h􀀀1 obtained with a sample of crushed Italian tu measured with the closed chamber technique. The results, obtained using di erent detectors and tech- niques, show a satisfactory agreement. The results of the measurements of the radon concentration in the Ital- ian and Ecuadorian spring waters collected, compared to the reference value, indicated in the European Directive EURATOM 51/2013 dedicated to water intended for human consumption, show values well below 100 Bq l􀀀1 except for a Calabrian source, San Giovanni in Fiore, with a concentration of 133 Bq l􀀀1 measured with the closed chamber technique. Protection from this important gas necessarily involves actions to pre- vent and inform the population, as also indicated by the recent Italian law 101/2020 implementing the EURATOM Directive 59/2013. To this end, the activities carried out with projects aimed at high school can, at the same time, bring young people closer to scienti c research and a possible future in research, but also improve the knowledge of the dangers associated with radon for these students and the surroundings in which they live. For this reason, the last chapter of this work brie y summarizes the activities of the INFN RadioLab project in which I have been able to participate in this three-year period and which has involved about 150 Calabrian and Ecuado- rian students. ments with the chamber will allow a wide research activity on the dependence