1,720,959 research outputs found
Proprietà Chimico-fisiche di Film Elettrodici di Diamante Conduttore
No full textLa preparazione di film di diamante ad elevata conduttività elettrica, realizzata in più gruppi di ricerca a partire dalla fine degli anni ‘80, ha consentito l’ottenimento di film elettrodici caratterizzati da sovratensioni di sviluppo di ossigeno anche più elevate di quelle riscontrate su elettrodi quali il carbone vetroso, il biossido di piombo, il biossido di stagno.
Questa caratteristica, unita alla concomitante alta sovratensione di sviluppo d’idrogeno e all’assenza di micro- e meso- porosità nel materiale, ne consente interessanti applicazioni in chimica elettroanalitica, per l’ampliamento della finestra di polarizzabilità ideale.
Così come per carbone vetroso e grafite, l’elevata sovratensione di ossigeno tipica del diamante drogato viene spiegata ammettendo che lo stadio di formazione del radicale ossidrile adsorbito sia fortemente sfavorito dalla bassa stabilità di quest’ultimo. Questo fa naturalmente prevedere che il materiale elettrodico in questione possa avere interessanti applicazioni per la produzione elettrochimica di ozono e per l’incenerimento elettrochimico di inquinanti organici in ambienti acquatici.
L'indagine elettrochimica dei film di diamante conduttore è stata realizzata tramite voltammetria ciclica e curve di polarizzazione quasi stazionarie, in soluzione acquosa di H2SO4 e successivamente in ambiente perclorico in presenza di NaCl. Le polarizzazioni anodiche in presenza del solo elettrolita di supporto hanno evidenziato l’irreversibilità dell’inserimento sulla superficie carboniosa di gruppi ossidrilici e carbonilici, che rendono la superficie idrofilica; polarizzazioni catodiche non permettono di riportare la superficie al suo carattere idrofobico originale. Successivamente, è stata studiata la reazione modello di sviluppo di cloro, effettuando alcune prove anche relativamente all’evoluzione d’idrogeno e ossigeno. Come ci si attendeva, la scarsa stabilizzazione esercitata dalla superficie di diamante nei confronti dei radicali H, OH e Cl, determina modifiche sostanziali nei meccanismi delle tre reazioni elettrodiche considerate, consentendo in particolare una efficiente selettività nello sviluppo di cloro e/o nella produzione di ipoclorito in ambiente debolmente acido. L’elevata resa faradaica del processo di produzione di cloro attivo risulta interessante per la disinfezione elettrochimica di acque potabili o per altre applicazioni nel settore
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
Direct electro-oxidation of bisphenol-A in aqueous alkaline media
No full textThe treatment of wastewaters containing bisphenol-A (BPA) is a problem widely encountered in the industry of poly-carbonate and epoxydic resins production. Although present in moderate concentration (e.g. 50-200 ppm) in real effluents, its toxicity is still a problem and biological degradation is very slow. The electrochemical treatment is therefore of practical interest, considering that drastic chemical attacks (like ozonization) do not decrease the COD content of the effluent, although causing disappearance of BPA. Experiments have been carried out in alkaline media, with different electrode materials and at different temperature. Best results have been obtained electrolyzing solutions with a relatively low concentration of BPA (in order to minimize electrode fowling) and using electrode materials with high oxygen overpotential. The BPA disappearance has been followed by UV-Visible spectroscopy, while COD and TOC content determinations, at different time, allow considerations on the efficiency of the electrochemical process
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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