1,721,054 research outputs found
Materiali catodici a base di zolfo per batterie Li-S ad alte prestazioni
Full text linkDurante il funzionamento di una batteria litio-zolfo (Li-S) si assiste alla dissoluzione nell’elettrolita
dei polisolfuri di litio. L’effetto di questi polisolfuri è duplice: limita fortemente l’efficienza
Coulombica ed il funzionamento nel tempo della batteria a causa dell’effetto shuttle tra anodo e
catodo, tuttavia permette un utilizzo più efficiente dello zolfo che allo stato solido risulta
scarsamente conduttivo. Gli elettrodi di zolfo convenzionali mostrano spesso dei valori di capacità
molto bassi perché la formazione dei polisolfuri avviene solamente all’interfaccia con l’elettrolita,
mentre la maggior parte dello zolfo risulta inattiva.
Le batterie litio-zolfo (Li-S) semi-flusso presentano come anodo il litio metallico mentre il catodo è
rappresentato da una soluzione di polisolfuri di litio disciolti nell’elettrolita. Questa soluzione
prende il nome di “catolita” e viene dispersa su una matrice conduttiva ad esempio carbone. In
questo modo si riesce ad ottenere un materiale catodico completamente disponibile,
contrariamente a quanto avviene con gli elettrodi classici in cui parte dello zolfo rimane inattivo
all’interno della matrice.Le soluzioni di polisolfuri sono state proposte per due differenti impieghi nelle batterie Li-S: come
additivi e come materiale attivo. Nel primo caso sono stati aggiunti polisolfuri a batterie con
elettrodi convenzionali, S/carbone e Li 2 S/carbone, con lo scopo di saturare la soluzione elettrolitica
inibendo in questo modo la dissoluzione dello zolfo presente negli elettrodi. Nel secondo caso le
soluzioni di polisolfuri sono state utilizzate come materiale attivo in batterie che hanno come
elettrodi di lavoro, dei catodi non contenenti zolfo. I risultati ottenuti sono estremamente interessanti. L’utilizzo di soluzioni di polisolfuri come materiale attivo in batterie Li-S ibride permette di ottenere delle ottime prestazioni, nettamente superiori rispetto alle Li-S con elettrodi convenzionali ed anche rispetto alle attuali Li-ione commerciali. In particolare le celle testate hanno raggiunto valori di capacità specifica di poco inferiori al valore teorico dello zolfo, accompagnati da un’elevata stabilità. I valori di capacità specifica ottenuti risultano superiori rispetto ai materiali catodici attualmente in commercio per le batterie Li-ione di un ordine di grandezza
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
The crucial role of the supporting electrolyte in redox flow battery performances
No full text6 figures, 3 tables.Renewable energy sources are being adopted more widely around the world. This is due to increasing energy demands, the fact that countries have set targets to reduce carbon emissions, and that solar and wind energy are intermittent by nature. This means that reliable, large-scale storage solutions are needed urgently. Redox flow batteries (RFBs) are proving to be leading candidates in this field, as they decouple power and energy capacities, enabling highly scalable and modular installations. One of the key parameters of RFB performances relies on the supporting electrolyte. It can affect ionic conductivity (IC), redox stability, membrane selectivity and cycle life. In this review we present a comparison of the supporting electrolyte's role in both aqueous and non-aqueous RFBs. A comparison between traditional inorganic salts (e.g. H2SO4, Na2SO4, KCl) and novel neutral organic electrolytes such as ionic liquids (ILs) and deep eutectic solvents (DES) is assessed. Here we highlight how those latter are able to improve the properties of the electroactive solution in terms of increasing solubility, conductivity and thermal and electrochemical stability. In addition, a cost analysis of those novel organic electrolytes is presented, alongside future hybrid electrolytes.The authors are thankful for the Grant MUR Dipartimento di
Eccellenza 2023-27 X-CHEM project ‘‘eXpanding CHEMistry:
implementing excellence in research and teaching’’.Peer reviewe
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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