1,721,020 research outputs found
Structural and electrochemical investigations of Li-ion battery electrodes. 1. Vanadium doping of LiFePO4 cathodes 2. Aqueous binders for anatase TiO2 anodes
No full textThe intense use of fossil fuels in the last two centuries is primarily responsible for global warming and severe environmental pollution. Moreover, the progressive depletion of the oil/gas resources and the strong dependence on foreign suppliers create national vulnerabilities. In this context, the development of renewable energy sources and the implementation of electric vehicles for transportation is becoming a worldwide imperative. Solar radiation, wind and waves are discontinuous energy sources, thus their use requires efficient energy storage devices to balance the supply with the demand. The most convenient way to store the energy is to convert it into chemical energy and, on demand, convert it back to electrical energy. This is exactly what batteries do. Batteries can also provide the portability of the stored energy and possess the ability to deliver the electricity with high efficiency and without gaseous emission. The development of batteries that can store sustainable energy with long term stability and have a very prolonged cycle life without environmental constraints is one of the main challenges of the 21st century. This is true also in the field of transportation where the use of electric vehicles will reduce the use of oil and pollution. Batteries with high energy and power densities, extended life and high safety are hence required. This type of ''green revolution'', implying an extended use of renewable energy sources to replace oil or carbon, may occur using Lithium ion batteries that dominate the consumer market (they are sold in billion pieces for laptop computers, cameras, etc) because of their ability to store a high density of energy, their high efficiency and prolonged cycle life. The performance of these devices depends on the physical-chemical properties of the anodic and cathodic reactants. The current lithium-ion technology is satisfactory for consumer electronics, but a quantum jump is necessary to meet the requirements for applications such as electric cars. Thus the research of new and advanced materials is currently challenging materials scientists. The research work presented in this thesis deals with the investigation of the electrochemical properties of electrode materials for rechargeable lithium ion batteries. Two different aspects have been studied that are both driven toward the development of greener, safer and cheaper lithium ion batteries. In the first part of my PhD thesis, the relationships between structural features and electrochemical performances of LiFePO4, a promising cathode material, have been investigated. The structure of LiFePO4 has been modified by introduction of vanadium (doping) in an attempt to overcome the intrinsic limitation (i.e. low electrical conductivity) of this material. The synthesized materials, with different concentrations of dopant, have better electrochemical performances than the pure LiFePO4. The structural modifications induced by vanadium were analyzed by means of X-ray diffraction and Synchrotron X-rays Absorption Spectroscopy and correlated with the improved electrochemical performances. The second part of the present dissertation describes the results obtained during my six months spent as a visiting PhD student at MEET (Ma'1⁄4nster Electrochemical Energy Technology) at the WWU University of Ma'1⁄4nster, Germany, under the supervision of Prof. Dr. Stefano Passerini. The work deals with the study of the effect water processible binders on anatase TiO2 anode electrochemical performances. The electrodes manufactured using aqueous binders showed improved electrochemical performance with respect to those made using traditional fluorinated binders. A full lithium ion cell comprising TiO2 anode and a high voltage cathode, both prepared using water as solvent (instead of toxic liquids) was assembled and successfully cycled The results reported within this thesis have been the subject of the following publications: A. Moretti, G.T. Kim, D. Bresser, K. Ranger, E. Paillard, R. Marassi, M. Winter, S. Passerini, ''Investigation of different binding agents for nanocrystalline anatase TiO2 anodes and its application in a novel, green lithium-ion battery'', Journal of Power Sources, 2013, 221, 419-426. L. Tabassam, G. Giuli, A. Moretti, F. Nobili, R. Marassi, M. Minicucci, R. Gunnella, L. Olivi, A. Di Cicco, ''Structural study of LiFePO4-LiNiPO4 solid solutions'', Journal of Power Sources, 2012, 213, 287-295. A. Moretti, G. Giuli, F. Nobili, A. Trapananti, G. Aquilanti, R. Tossici, R. Marassi, ''Structural and electrochemical characterization of Vanadium-doped LiFePO4 cathodes for Lithium-ion batteries'', Journal of the Electrochemical Society, submitted
OpenCitations Index
No full textA citation index is a bibliographic index recording citations between publications, allowing the user to establish which later documents cite earlier documents. Several citation indexes are already available, some of which are freely accessible but not downloadable (e.g. Google Scholar), while others can be accessed only by paying significant access fees (e.g. Web of Science and Scopus).
OpenCitations, as an infrastructure organization for open scholarship, has built the OpenCitations Index using the data available in particular bibliographic databases
Developing Application Profiles for Enhancing Data and Workflows in Cultural Heritage Digitisation Processes
Full text linkAs a result of the proliferation of 3D digitisation in the context of cultural heritage projects, digital assets and digitisation processes – being considered as proper research objects – must prioritise adherence to FAIR principles. Existing standards and ontologies, such as CIDOC-CRM, play a crucial role in this regard, but they are often over-engineered for the need of a particular application context, thus making their understanding and adoption difficult. Application profiles of a given standard – defined as sets of ontological entities drawn from one or more semantic artefacts for a particular context or application – are usually proposed as tools for promoting interoperability and reuse while being tied entirely to the particular application context they refer to. In this paper, we present an adaptation and application of an ontology development methodology, i.e. SAMOD, to guide the creation of robust, semantically sound application profiles of large standard models. Using an existing pilot study we have developed in a project dedicated to leveraging virtual technologies to preserve and valorise cultural heritage, we introduce an application profile named CHAD-AP, that we have developed following our customised version of SAMOD. We reflect on the use of SAMOD and similar ontology development methodologies for this purpose, highlighting its strengths and current limitations, future developments, and possible adoption in other similar projects
The OpenCitations Index: description of a database providing open citation data
Full text linkThis article presents the OpenCitations Index, a collection of open citation data maintained by OpenCitations, an independent, not-for-profit infrastructure organisation for open scholarship dedicated to publishing open bibliographic and citation data using Semantic Web and Linked Open Data technologies. The collection involves citation data harvested from multiple sources. To address the possibility of different sources providing citation data for bibliographic entities represented with different identifiers, therefore potentially representing same citation, a deduplication mechanism has been implemented. This ensures that citations integrated into OpenCitations Index are accurately identified uniquely, even when different identifiers are used. This mechanism follows a specific workflow, which encompasses a preprocessing of the original source data, a management of the provided bibliographic metadata, and the generation of new citation data to be integrated into the OpenCitations Index. The process relies on another data collection—OpenCitations Meta, and on the use of a new globally persistent identifier, namely OMID (OpenCitations Meta Identifier). As of July 2024, OpenCitations Index stores over 2 billion unique citation links, harvest from Crossref, the National Institute of Heath Open Citation Collection (NIH-OCC), DataCite, OpenAIRE, and the Japan Link Center (JaLC). OpenCitations Index can be systematically accessed and queried through several services, including SPARQL endpoint, REST APIs, and web interfaces. Additionally, dataset dumps are available for free download and reuse (under CC0 waiver) in various formats (CSV, N-Triples, and Scholix), including provenance and change tracking information
Lettura aumentata, compagni di lettura e il ruolo delle biblioteche scolastiche
No full textL’intervento prende in esame il collegamento fra le pratiche di promozione della lettura nell’ambito delle scuole e il nuovo ecosistema digitale, assumendo come punto di partenza le esperienze di due diversi progetti europei Erasmus+: “The Living Book” e “ReadTwinning”. Il progetto “The Living Book” (2016-2019) è basato sul concetto di lettura aumentata, una strategia orientata al lettore di collegamento sistematico e competente fra la lettura di un libro e l’uso di risorse e contenuti on-line, con l’obiettivo di migliorare tanto la comprensione del testo quanto la qualità dell’esperienza di lettura. Il progetto “ReadTwinning” (2019-2022), appena avviato, è basato invece sull’idea di amici di lettura, collegati attraverso interessi condivisi e per mezzo di una piattaforma on-line. Le linee guida metodologiche di tutti e due i progetti assegnano un ruolo centrale alle biblioteche scolastiche, considerate come l’ambiente ideale per promuovere sia la lettura aumentata (in primo luogo attraverso gruppi di lettura orientati agli interessi dei partecipanti) sia l’individuazione di ‘amici di lettura’ che condividano interessi specifici (reading pal) e dei libri per loro più rilevanti
Electrochemical and structural investigation of transition metal doped V 2 O 5 sono-aerogel cathodes for lithium metal batteries
No full textBilayered V2O5·nH2O is regarded as a universal host for metal ions and thus applicable to metal batteries. The achievable capacity is strongly related with material morphology and structure. Herein we report a modified aerogel synthesis involving a sonication step yielding to a faster gel formation. Doped sono-aerogel are prepared adding Ni and Mn (from 1 to 10 mol%) during the hydrolysis of the precursor. XAS analysis reveals that the dopants are both divalent and reside in the space between the V2O5 bilayers. The doped sono-aerogels display different morphology and improved electrochemical performance respect to the un-doped counterpart
Rotating disc electrode study of Pt-Co-Cs2.5PW12O40 composite electrodes toward oxygen reduction reaction
No full textThe oxygen reduction reaction (ORR) has been studied using different types of carbon supported Pt-Co alloys and (Pt-Co)-Cs 2.5H 0.5PW 12O 40 composite electrodes. The composite electrodes, prepared using different methods, have been characterized by RDE voltammetry in O 2 saturated acidic media. The composite electrodes show better performances toward ORR than the commercial pristine catalyst in terms of mass activities and half wave potentials. The composite prepared using the in house Pt-Co alloy shows the higher catalytic activity. The analysis of XRD spectra of the home-made Pt-Co alloy reveals the presence of different phases (fct and fcc) that probably justify the better catalytic properties
Educazione alla cittadinanza digitale: percorsi per la formazione iniziale degli insegnanti
No full textExamining the impact of digital media and artificial intelligence on the skills, behaviors, and responsibilities required to navigate and actively participate in online life is crucial for educating aware and responsible citizens in the contemporary digital context.
This research explores the importance of digital citizenship education by analyzing students’ and teachers’ perceptions of their own competencies, to develop effective and targeted training interventions to promote informed and responsible digital citizenship. In doing so, the study aims to understand how promoting critical thinking and ethical awareness can improve the ability to navigate responsibly in the digital landscape.
The research involved a thorough analysis of the methodologies, materials, and resources necessary for designing effective training programs in digital citizenship education, as well as the development of assessment tools to measure digital citizenship competencies. Furthermore, it led to the formulation of strategic recommendations to strengthen and support digital citizenship education initiatives, considering the challenges and opportunities generated by the rapid digital evolution
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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