Physisorption of perylene dyes on graphite​

This thesis work was carried out at CNR of Bologna. CNR- ISOF (Institute of Organic Synthesis and Photoreactivity) in the group of Dr. Vincenzo Palermo. The aim of this thesis was to perform a comparative and quantitative study on the interaction of three different PDI (perylene diimide) dyes with graphene (G) sheets in solution, using a phenomena called “dye’s capturing”. The only difference between the PDI dyes tested was the terminal atom in the side groups. In particular, we used a perylene core with side ethyl-phenyl group exposing in the para position a hydrogen (PDI-H), fluorine (PDI-F), or chlorine atom (PDI-Cl). Although the relative simplicity of the process and the measurement itself, the preparation of a reliable experimental setup is not trivial and several issues had to be taken into account. The main challenges to be overcame were related to the effective stability and reliability of the chemical systems, such as dyes, solution and graphite during the entire exposure time. For this reasons the work addressed the following issues: 1)Studying the interaction of small organic molecules and graphite flakes, using commercial products. 2)Finding the best conditions for the dye capturing process (concentration, stabilization of the solution, solvent etc.).3)Understanding of the “dye’s capturing” phenomena by UV-VIS and fluorescence techniques. 4)Stabilizing a relationship between the chemical structure of PDI-X (with side chains symmetrically terminated with a different atom) and the interaction with graphite, taking into account adsorption speed, packing, etc. 5)After testing the samples, the reported results were used to: 1) Determinate the best suitable molecule for the dye capturing process, and optimize a hypothetical industrial process by calculating the surface area for each molecule. 6)Morphology and structural characterizations with different technique like: AFM, SEM, EDX, XRD, fluorescence microscopy, TGA/DSC, IR

Quantitative imaging of the complexity in liquid bubbles' evolution reveals the dynamics of film retraction

The dynamics and stability of thin liquid films have fascinated scientists over many decades. Thin film flows are central to numerous areas of engineering, geophysics, and biophysics and occur over a wide range of length, velocity, and liquid properties scales. In spite of many significant developments in this area, we still lack appropriate quantitative experimental tools with the spatial and temporal resolution necessary for a comprehensive study of film evolution. We propose tackling this problem with a holographic technique that combines quantitative phase imaging with a custom setup designed to form and manipulate bubbles. The results, gathered on a model aqueous polymeric solution, provide an unparalleled insight into bubble dynamics through the combination of full-field thickness estimation, three-dimensional imaging, and fast acquisition time. The unprecedented level of detail offered by the proposed methodology will promote a deeper understanding of the underlying physics of thin film dynamics

Dynamical friction in multi-component evolving globular clusters

We use the Chandrasekhar formalism and direct N-body simulations to study the effect of dynamical friction on a test object only slightly more massive than the field stars, orbiting a spherically symmetric background of particles with a mass spectrum. The main goal is to verify whether the dynamical friction time (t_DF) develops a non-monotonic radial-dependence that could explain the bimodality of the Blue Straggler radial distributions observed in globular clusters. In these systems, in fact, relaxation effects lead to a mass and velocity radial segregation of the different mass components, so that mass-spectrum effects on t_DF are expected to be dependent on radius. We find that, in spite of the presence of different masses, t_DF is always a monotonic function of radius, at all evolutionary times and independently of the initial concentration of the simulated cluster. This because the radial dependence of t_DF is largely dominated by the total mass density profile of the background stars (which is monotonically decreasing with radius). Hence, a progressive temporal erosion of the BSS population at larger and larger distances from the cluster center remains the simplest and the most likely explanation of the shape of the observed BSS radial distributions, as suggested in previous works. We also confirm the theoretical expectation that approximating a multi-mass globular cluster as made of (averaged) equal-mass stars can lead to significant overestimates of t_DF within the half-mass radius.Comment: In press on Ap

A complete census of HαH\alpha emitters in NGC 6397

We used a dataset of archival Hubble Space Telescope images obtained through the F555W, F814W and F656N filters, to perform a complete search for objects showing $H\alpha$ emission in the globular cluster NGC 6397. As photometric diagnostic, we used the $(V-H\alpha)_0$ color excess in the $(V-H\alpha)_0$-$(V-I)_0$ color-color diagram. In the analysed field of view, we identified 53 $H\alpha$ emitters. In particular, we confirmed the optical counterpart to 20 X-ray sources (7 cataclysmic variables, 2 millisecond pulsars and 11 active binaries) and identified 33 previously unknown sources, thus significantly enlarging the population of known active binaries in this cluster. We report the main characteristics for each class of objects. Photometric estimates of the equivalent width of the $H\alpha$ emission line, were derived from the $(V-H\alpha)_0$-excess and, for the first time, compared to the spectroscopic measurements obtained from the analysis of MUSE spectra. The very good agreement between the spectroscopic and photometric measures fully confirmed the reliability of the proposed approach to measure the $H\alpha$ emission. The search demonstrated the efficiency of this novel approach to pinpoint and measure $H\alpha$-emitters, thus offering a powerful tool to conduct complete census of objects whose formation and evolution can be strongly affected by dynamical interactions in star clusters.Comment: Accepted for publication by ApJ; 14 pages, 8 Figures, 1 Tabl

Crystallization of Levitons in the fractional quantum Hall regime

Using a periodic train of Lorentzian voltage pulses, which generates soliton-like electronic excitations called Levitons, we investigate the charge density backscattered off a quantum point contact in the fractional quantum Hall regime. We find a regular pattern of peaks and valleys, reminiscent of analogous self-organization recently observed for optical solitons in non-linear environments. This crystallization phenomenon is confirmed by additional side dips in the Hong-Ou-Mandel noise, a feature that can be observed in nowadays electron quantum optics experiments.Comment: 9 pages, 4 figure

Minimal excitation states for heat transport in driven quantum Hall systems

We investigate minimal excitation states for heat transport into a fractional quantum Hall system driven out of equilibrium by means of time-periodic voltage pulses. A quantum point contact allows for tunneling of fractional quasi-particles between opposite edge states, thus acting as a beam splitter in the framework of the electron quantum optics. Excitations are then studied through heat and mixed noise generated by the random partitioning at the barrier. It is shown that levitons, the single-particle excitations of a filled Fermi sea recently observed in experiments, represent the cleanest states for heat transport, since excess heat and mixed shot noise both vanish only when Lorentzian voltage pulses carrying integer electric charge are applied to the conductor. This happens in the integer quantum Hall regime and for Laughlin fractional states as well, with no influence of fractional physics on the conditions for clean energy pulses. In addition, we demonstrate the robustness of such excitations to the overlap of Lorentzian wavepackets. Even though mixed and heat noise have nonlinear dependence on the voltage bias, and despite the non-integer power-law behavior arising from the fractional quantum Hall physics, an arbitrary superposition of levitons always generates minimal excitation states.Comment: 15 pages, 7 figure

Heat pumps in existing heating and hot water systems: an evaluation of primary energy savings and reduction of CO2 produced

In a previous work we recorded a significant contribution to urban air pollution attributable to heating systems powered by fuel. Thus, we propose the replacement of existing boilers for heating and domestic hot water (DHW) production systems with high temperature air-to-water heat pumps as an intervention to improve urban air quality and energy use. We analyze replacement scenarios within the entire residential building stock of two Italian cities, Milan and Salerno, belonging to different climate zones and with their own thermophysical characteristics. For each of them, the consequences of the replacement intervention in terms of primary energy savings and lower CO2 production are evaluated. The results show a reduction of primary energy consumption by 34% in Milan and 43% in Salerno, and of CO2 production by 30% in Milan and 39% in Salerno

«Il sale della satira è il condimento della commedia». Elementi satirici nel poema eroicomico europeo

The focus of this paper is the relationship between mock-heroic and satire. The analysis will deal with the most important satirical and mock-heroic authors in Europe: Tassoni, Boileau, Pope and Parini. The purpose is to prove how the satirical element is an essential part of the genre invented by Tassoni. In the second part of the paper we will try to demonstrate that the satire becomes the main mode of the comic in mock-heroic poems after the Secchia rapita. By analyzing chronologically, the most representative works, our article proposes a reflection about the genre and the evolution of its characteristics during almost two centuries. Luca FerraroL’articolo è incentrato sul rapporto tra eroicomico e satira. Gli autori passati in rassegna sono i principali del canone europeo: Tassoni, Boileau, Pope e Parini. L’obiettivo è stato quello di verificare quanto l’elemento satirico sia parte integrante del genere inventato da Tassoni. Nella seconda parte del testo si è cercato di dimostrare che la satira diventa la forma del comico predominante nei poemi eroicomici successivi alla Secchia rapita. Analizzandone in ordine cronologico le opere più rappresentative, si è voluto fare una riflessione sul genere e su come mutano gli elementi che lo caratterizzano nel corso dei suoi quasi due secoli di vita. The focus of this paper is the relationship between mock-heroic and satire. The analysis will deal with the most important satirical and mock-heroic authors in Europe : Tassoni, Boileau, Pope and Parini. The purpose is to prove how the satirical element is an essential part of the genre invented by Tassoni. In the second part of the paper we will try to demonstrate that the satire becomes the main mode of the comic in mock-heroic poems after the Secchia rapita. By analyzing chronologically the most representative works, our article proposes a reflection about the genre and the evolution of its characteristics during almost two centuries. 

Quantitative imaging of the complexity in liquid bubbles’ evolution reveals the dynamics of film retraction

Thin liquid films: Seeing bubbles in a better light A procedure for imaging the complex fluid dynamics in bubbles could greatly assist efforts to understand and exploit thin liquid films in applications ranging through medicine, industrial chemistry and engineering. Thin liquid films are ubiquitous in nature, found in such varied systems as soap bubbles, biological membranes, detergents, oils, insulation, foods and geological magma. Researchers in Italy led by Biagio Mandracchia at the Institute of Applied Science and Intelligent Systems in Naples, devised a novel holographic phase imaging technique to watch bubbles as they form, develop, burst and retract. The researchers built customized apparatus to create and manipulate the bubbles. The unprecedented level of detail being revealed offers deeper understanding of the physics underlying thin film behavior. Insights into the complex fluid dynamics within bubbles could advance thin film technology for many applications