1,720,974 research outputs found
Advanced carbon-based nanostructured materials for energy storage devices
Full text linkCommercially available batteries and capacitors normally use carbonaceous electrodes. However, since common graphite is often limited by its poor performances, alternative structures and morphologies could be developed. The possibility of exploiting innovative synthesis processes and virtuous alternative sources for advanced carbon-based materials opens new perspectives in a global scenario where the push for energy transition becomes progressively critical.
Aiming at studying innovative pure or composites carbon materials for electrochemical devices, i.e. lithium-ion batteries and supercapacitors, this thesis includes the development of synthetic processes (i.e. following purely chemical routes or exploiting agricultural wastes), electrochemical testing, optimization of the device features, and a feasibility study of advanced characterization in operando.
Hybrid C/Si anodes for lithium-ion batteries have been studied for many years. Carbon softness, conductivity, and capability of intercalating lithium ions are ideal to prevent the volumetric expansion of silicon lattice during cyclations. To obtain a composite anode material, carbon nanowalls (CNW) have been synthesized via CVD and combined with Si nanoparticles: the CNW outer layer proved to be able to protect Si beneath.
In a view of green transition, rice husk has been used as a C source to produce carbon aerogels (CAs) and carbon dots (CDs). First, a synthetic process has been developed to obtain the nanostructures, whose properties as electrode materials have been evaluated both in supercapacitors and lithium-ion batteries. The reported results show the efficacy of RH derivatives as resistant cost effective alternatives to currently available materials in both devices.
Prior to electrochemical testing, detailed characterization of all the abovementioned materials have been performed by means of SEM, EDS, AFM; XRD; Raman Spectroscopy, X ray Tomography and BET analysis. Besides routinary characterization, preliminary tests with AFM on electrodes have been conducted aiming at the optimization of our system to perform in operando electrochemical AFM
Elettrodi ibridi carbonio/materiale attivo per accumulatori agli ioni di litio Carbon/active material electrodes for lithium ion batteries
No full textLa presente invenzione è relativa alla procedura di realizzazione di un elettrodo negativo per batterie agli ioni litio in cui l’elettrodo è composto da una pluralità di strati di materiale carbonioso e di materiale attivo supportati su un substrato che funge da collettore di corrente. L’invenzione è relativa anche alla produzione di elettrodi nanostrutturati per altri dispositivi atti alla produzione e accumulo di energia elettrica, come per esempio i supercapacitori
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Analysis of Roman era archaeological finds from Museo Territoriale del Lago di Bolsena with non-destructive investigation techniques
Full text linkThe management of the Museo Territoriale del Lago di Bolsena has made various types of archaeological finds available for non-destructive and non-invasive analysis using advanced techniques. The finds date from the Roman period and were collected during the excavation campaigns of the French School in the archaeological area of Poggio Moscini in the town of Bolsena (Viterbo) between 1962 and 1973. The finds on which the analyses focused are: metallic handles, pots and mosaic tiles. The techniques used to carry out this archaeometric study are based on X-ray diffraction (XRD). In addition, Raman and Fourier-Transform IR (FTIR) spectroscopies in the reflection mode have been considered for the characterisation of the finds. The content of this paper is part of the research activity of the project REMEDIAVI (Ricostruzione virtuale ed in realtà aumentata di Volsinii Novi: un approccio avanzato per la fruibilità sostenibile dell'area archeologica di Bolsena)
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