Browsing by Author "Bonanno, Assunta"

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Adsorption properties of carbon nanotubes and application of thermal desoprtion spectroscopy to ammonia and methane ices and zoisite
(2010-12-14) Vasta, Roberta; Bonanno, Assunta; Falcone, Giovanni
In this work we wanted to underline the importance of Thermal Desorption Spectroscopy and its applications to several branches of Physics. Temperature-programmed desorption techniques (TPD) are important to determinate kinetic and thermodynamic parameters of desorption processes and decomposition reactions. Knowledge of the nature of the desorption process is fundamental to understand the nature of the elementary chemical processes of adsorbates, as the energetics of bonding, the specification of the chemical nature of the bound species and the nature and magnitude of interactional effect between adsorbed species. We focused our attention on the applications of Thermal Desorption Spectroscopy (TDS) to High-Energies Physics, Astrophysics and Geophysics; in fact this technique was used, respectively, to investigate the molecular hydrogen adsorption on carbon nanotubes, the effects of electron bombardment on ammonia and methane ices and changes of zoisite mineral after heating. The molecular hydrogen adsorption on carbon nanotubes was studied to find a possible solution to vacuum system problems of Large Hadron Collider (LHC); in fact, the circular path of photon beams produces synchrotron radiation which deteriorates LHC vacuum desorbing gas molecules from the ring walls. Among the desorbed species the most problematic to pump out is H2. Since LHC elements operate at low temperatures, a possible solution to vacuum problem is the installation of cryosorbent materials on the LHC walls. In this work we study the possibility to use carbon nanotubes as criosorbers in future accelerators. Our sample, furnished by Prof. Nagy group of Chemical Engineering Department of Calabria University, is constituted by MWNTs synthesized by chemical vapor deposition using C2H4 and subsequently purified. Our investigations confirm that the carbon nanotubes have a great adsorption capacity also at low temperatures both for H2 and noble gases as Kr; then we observed that H2 adsorption on CNT is described by a first kinetic-order, while Kr adsorption is characterized by a zero kinetic-order. By means of TDS we calculate the activation energy for H2 adsorption on carbon nanotubes and we found a value of about 3KJ/mol, perfectly coherent with theoretic one. Moreover, from a comparison between nanotubes and other carbon-based material (as charcoal), we noted that adsorption efficiency for CNT is almost an order of magnitude higher then charcoal. So carbon nanotubes are good candidates to cryosorbers in future accelerators. 2 As Thermal Desorption Spectroscopy application to Astrophysics we studied the effect of electron bombardment on ammonia and methane ices. The interstellar medium is composed for 99% by gas; molecules, atoms and radicals at gas state condense on dust grains surface of molecular clouds (at 10 K) creating an icy mantle with a thickness of 0.1 μm. The presence of ices is confirmed by IR spectroscopy of obscured stellar sources and in interstellar grains are localized solid mixture containing H2O, CO, CH4 and NH3. In these environments ices are subjected to chemical and physical processes, specifically to bombardment of photons and cosmic rays, with the consequent synthesis of new organic species In this work we conducted an investigation of the chemical processing of ammonia and methane ices subjected to energetic electrons. By Thermal Desorption Spectroscopy we verify the production of new organic species, after energetic irradiation in interstellar ices, as diazene (N2H2), ethane (C2H6) and acetylene (C2H2). Finally, in Geophysics and Petrology Thermal Desorption Spectroscopy can be used to study minerals chemical composition. Our interest was focused on zoisite and the sample investigated was furnished by prof. Ajò from “Institute of Inorganic Chemistry and Surfaces” of CNR, in Padova. In this work we used TDS to investigate zoisite behaviour during heating form room temperature to 650oC and to understand if its modification into tanzanite variety after heating is due to structural changes or to a dehydration mechanism.
Adsorption properties of carbon nanotubes and application of thermal desoprtion spectroscopy to ammonia and methane ices and zoisite
(2014-05-15) Vasta, Roberta; Bonanno, Assunta; Falcone, Giovanni
In this work we wanted to underline the importance of Thermal Desorption Spectroscopy and its applications to several branches of Physics. Temperature-programmed desorption techniques (TPD) are important to determinate kinetic and thermodynamic parameters of desorption processes and decomposition reactions. Knowledge of the nature of the desorption process is fundamental to understand the nature of the elementary chemical processes of adsorbates, as the energetics of bonding, the specification of the chemical nature of the bound species and the nature and magnitude of interactional effect between adsorbed species. We focused our attention on the applications of Thermal Desorption Spectroscopy (TDS) to High-Energies Physics, Astrophysics and Geophysics; in fact this technique was used, respectively, to investigate the molecular hydrogen adsorption on carbon nanotubes, the effects of electron bombardment on ammonia and methane ices and changes of zoisite mineral after heating. The molecular hydrogen adsorption on carbon nanotubes was studied to find a possible solution to vacuum system problems of Large Hadron Collider (LHC); in fact, the circular path of photon beams produces synchrotron radiation which deteriorates LHC vacuum desorbing gas molecules from the ring walls. Among the desorbed species the most problematic to pump out is H2. Since LHC elements operate at low temperatures, a possible solution to vacuum problem is the installation of cryosorbent materials on the LHC walls. In this work we study the possibility to use carbon nanotubes as criosorbers in future accelerators. Our sample, furnished by Prof. Nagy group of Chemical Engineering Department of Calabria University, is constituted by MWNTs synthesized by chemical vapor deposition using C2H4 and subsequently purified. Our investigations confirm that the carbon nanotubes have a great adsorption capacity also at low temperatures both for H2 and noble gases as Kr; then we observed that H2 adsorption on CNT is described by a first kinetic-order, while Kr adsorption is characterized by a zero kinetic-order. By means of TDS we calculate the activation energy for H2 adsorption on carbon nanotubes and we found a value of about 3KJ/mol, perfectly coherent with theoretic one. Moreover, from a comparison between nanotubes and other carbon-based material (as charcoal), we noted that adsorption efficiency for CNT is almost an order of magnitude higher then charcoal. So carbon nanotubes are good candidates to cryosorbers in future accelerators. 2 As Thermal Desorption Spectroscopy application to Astrophysics we studied the effect of electron bombardment on ammonia and methane ices. The interstellar medium is composed for 99% by gas; molecules, atoms and radicals at gas state condense on dust grains surface of molecular clouds (at 10 K) creating an icy mantle with a thickness of 0.1 μm. The presence of ices is confirmed by IR spectroscopy of obscured stellar sources and in interstellar grains are localized solid mixture containing H2O, CO, CH4 and NH3. In these environments ices are subjected to chemical and physical processes, specifically to bombardment of photons and cosmic rays, with the consequent synthesis of new organic species In this work we conducted an investigation of the chemical processing of ammonia and methane ices subjected to energetic electrons. By Thermal Desorption Spectroscopy we verify the production of new organic species, after energetic irradiation in interstellar ices, as diazene (N2H2), ethane (C2H6) and acetylene (C2H2). Finally, in Geophysics and Petrology Thermal Desorption Spectroscopy can be used to study minerals chemical composition. Our interest was focused on zoisite and the sample investigated was furnished by prof. Ajò from “Institute of Inorganic Chemistry and Surfaces” of CNR, in Padova. In this work we used TDS to investigate zoisite behaviour during heating form room temperature to 650oC and to understand if its modification into tanzanite variety after heating is due to structural changes or to a dehydration mechanism.
Decoration and Characterization of Carbon-based nanomaterial for third generation photovoltaic devices
(2018-03-16) Imbrogno, Alessandra; Critelli, Salvatore; Bonanno, Assunta; Macario, Anastasia; El Khakani, Alì
The PhD project is oriented on the synthesis and characterization of carbonbased nanomaterial and their eventual decoration with pulsed laser deposition technique for the developing of advanced nanomaterial suitable for photovoltaic application, in particular in DSSC devices. The dye sensitized solar cells belong to the third generation of photovoltaic devices, and are mainly composed of two electrodes deposited on FTO conductive glasses: the photoanode is also called \working electrode" (WE) and it is made of a thin lm of TiO2 deposited on a conductive FTO glass and sensitized by an organic dye, while the cathode, called \counter electrode" (CE), is made of a thin lm of platinum sputtered on a conductive FTO glass. The space between these two electrodes is lled with an electrolyte solution composed of a redox couple. The great advantage of these solar devices respect to traditional silicon-based solar devices is the relatively easy fabrication processes and the use of materials that are abundant on Earth. However, their conversion e ciency is still unsatisfactory, with conversion e ciency that barely reach the 18% for the solid-type DSSC and the 10% for the liquid-type of DSSC. The main issues that a ect the photovoltaic e ciency in DSSC are the dye deterioration, the high e-/h+ recombination in TiO2-dye substrate, the contact resistance between CE and electrolyte, and the degradation of the platinum counter electrode due to the electrolyte solution. During the last two decades many e orts have been made to resolve these issues, and some advances have been made by modify both the working and the counter electrodes. This Ph.D. project is focused on improving the materials used in both electrodes in liquid-type DSSC by using carbon nanomaterials. In particular, for what concern the counter electrode, the expensive platinum was substituted with multi walled carbon-nanotubes (MWCNT) decorated with metal nanoparticles that ensured both a good resistance to the corrosive action of the electrolyte solution and a highly rough surface that improved the catalysis of the redox reaction, resulting in a improvement of the photovoltaic performance of the DSSC device. For what concern the working electrode, instead, this Ph.D project was focused on the insertion of di erent carbon-based nanomaterials as multiwalled carbon nanotubes and graphene inside the TiO2 thin lm to reduce the loss of electron due to the e-/h+ recombination. Even in this case, the results showed interesting improvements of the photovoltaic e ciency of the DSSC device. All the experiments were conducted in both University of Calabria (Italy) and Institut National de la Recherche Scienti que (Canada).
Intelligent planning for curriculum personalization of e-Learning contents. Moodle as a case study
(2013-11-19) Caputi, Valentina; Bonanno, Assunta; Garrido, Antonio; Pantano, Pietro
The use and enhancement of technology in the field of (distance) education has increased the adoption of e-learning. Nowadays, a simple connection to the Internet makes it possible to access any on-line content. Thus, e-learning platforms based on Learning Management Systems (LMSs) permits us to eliminate the barriers of time and space that usually limit traditional teaching. LMSs facilitate the administration, storage, delivery, visualization and monitoring of e-learning contents to both students and teachers in a simple and functional way. There are many LMSs, such as Moodle, Docebo, Atutor, Ilias, .LRN, etc., widely used to support learning/teaching activities. For the best use of a LMS, it is fundamental not to consider it in an isolated way as a simple repository of learning contents, but as part of a larger system in which learning contents are aggregated for the construction of courses that can be fully personalized or adapted to the specific needs and abilities of each student. Curriculum personalization is faced in several ways by using several techniques, such as evolutionary algorithms, data mining techniques, decision support systems, etc., with the main objective to offer the best content to the most adequate person. In this thesis, we focus on Artificial Intelligence planning as a valuable formalism to describe actions (learning contents) in terms of preconditions (precedence relationships) and causal effects to find plans (learning paths) that entirely fit the students’ profiles. Thus, the integration of intelligent planning techniques into LMSs makes it possible to achieve the greatest learning benefits thanks to the automatic generation of customized learning paths. In particular, we focus on Moodle (Module Object-Oriented Dynamic Learning Environment) as a free, open-source PHP web application for producing modular Internet-based courses. Teachers and students interact in Moodle by means of activities (e.g. lessons, chats, SCORMs, forum, wikis, etc.) On the other hand, resources (e.g. text pages, web pages, links,etc.) are optionally used to transmit additional information regarding the activities. Consequently, courses can be created by appropriately combining activities and resources to deliver learning contents to the students. Moodle is flexible enough to model from small to big courses and it can be easily used and modified in order to extend its functionalities. The integration of planning in Moodle is not a straightforward task because Moodle and, in general, any LMS presents some limitations for this. The lesson is the most adequate Moodle’s activity to define causal and precedence relationships. But the lessons’ number and order must be fixed by the teacher. In other words, the execution sequence, i.e. learning path, may not take into consideration all the students’ needs, as determined by their profiles (background, learning style and goals). Thus, we have faced and solved the main limitations in order to integrate our intelligent planning approach in Moodle. First, complex relationships that usually appear when planning very elaborate courses cannot be easily defined in the form of (Moodle) lessons. We have overcome this limitation by using intermediate dummy lessons that simulate virtual transitions between learning states. Second, the information that students input into the platform are not always sufficient to exhaustively define their background and learning goals, indispensable to define customized learning paths. Again, our solution implies the creation of dummy lessons that help specify initial/goal learning states. Third, compiling a planning model from Moodle’s database is not intuitive because course properties are not easily available and, thus, we defined a detailed mapping. Fourth, once generated a plan by using a standard planner, a challenge arises to personalize the visualization and navigation of individual paths to each student. We coped with this by associating personal views to dynamically created groups of students. This work offers a scalability evaluation to demonstrate the applicability of the proposed approach. In particular, by using two standard planners it is possible to solve a number of tests involving courses of different sizes (up to 64 lessons) and with different numbers of students (up to 500 students). Courses containing up to 64 lessons and with 300 students are customized in less than 900 seconds that is an excellent result. From a more practical perspective, we have include a real demonstration of the functioning of the presented approach by implementing and customizing in Moodle a real Physics course of the University of Calabria (Italy). In conclusion, this thesis presents an AI planning approach to generate personalized learning paths within Moodle. In particular, it is explained how to generate and visualize personalized learning paths within Moodle. It is im portant to observe that in the presented system can use any standard planner and that the entire approach can be easily extrapolated to any other standard LMS. Furthermore, thanks to the flexibility of the approach, it is possible to adapt and customize our ideas to any type of learning course in any type of LMS
Laser ablation methods for cultural heritage: restoration, conservation, consolidation
(2014-11-12) Stranges, Fabio; Pantano, Pietro S.; Bonanno, Assunta
This thesis, developed in the period between March 2012 and November 2014, focuses on the researches on new methods for cleaning, diagnostics and restoration of Cultural Heritage assets. These methods are based on the use of Laser Ablation in various media (air, water and vacuum) and on different materials, such as alloys, metals and artificial stone materials. Furthermore, the thesis proposes different types of investigation, consolidation and restoration of archaeological artefacts, introducing new possible strategies of diagnostics and enhancements in the study of cultural heritage, through the contribution of nanotechnology and nanomaterials, still slightly used in the field of Cultural Heritage. The main objective of the thesis is to verify the applicability of different techniques in different environments, also trying to make the employed methodologies less invasive and more effective. In fact, a fundamental point is LA cleaning on various materials, directly in situ, using portable equipment and prototypes can be used in subaerial and underwater environments to selectively remove of crusts and deterioration patinas that often cover archaeological artifacts. The prototype has been realized during PhD and it can be used for measurements of LA cleaning and for Raman and PL spectroscopy. For testing the diagnostic methodology efficacy, the investigations were carried out by non-destructive methods on different types of materials (such as bronze, ceramics and precious metals) in different environments (subaerial and underwater), obtaining information comparable to laboratory measurements. Morphological studies were carried out using optical microscopy, Scanning Electron Microscopy SEM and Atomic Force Microscopy AFM (rarely used in Cultural Heritage). Chemical analysis were carried out with different spectroscopic techniques including X-Ray Fluorescence spectroscopy (XRF), X-ray Photoelectron Spectroscopy (XPS), PhotoLuminescence (PL), CathodoLuminescence (CL ) and finally the Energy Dispersive X-ray (EDX). Another aim concerns the study of particulate generated by LA cleaning for application in the consolidation of the artifact and high tech (photovoltaic and optoelectronic applications). Indeed, we study the production and characterization of nanoparticles and nanocomposites based on TiO2 and SiO2 for application to restoration and consolidation in archaeological artifacts, for exploring the possibility to use NPs as consolidating materials without introducing chemical, physical or esthetical changes in artifacts. Finally, our study has demonstrated that LA cleaning does not affect the Thermoluminescence measure. This thesis develops into five chapters. In the first chapter, we will introduce the LA processes, the second describes the Diagnostic techniques and experimental setup. Instead, in the third chapter we will discuss the materials analyzed, while in the fourth chapter describes the use of by-products generated from LA for consolidation of Cultural Heritage assets and for realization of nanocomposites for high-tech applications. Finally, in the fifth chapter we will conclude the study by listing the achievements.
Nano materials and innovative laser-based accelerators for cultural heritage
(2017-07-12) Veltri, Simona; Pantano, Pietro; Bonanno, Assunta; Antici, Patrizio
Nano materials and innovative laser-based accelerators for cultural heritage
(2017-07-12) Veltri, Simona; Pantano, Pietro; Bonanno, Assunta; Antici, Patrizio
Università della Calabria, Dipartimento di Fisica