1,720,963 research outputs found
Smart Materials in Construction Sector Decarbonisation: Few-Layer Graphene Based Radiant Heating
No full textFrom single-layer graphene to HOPG: Universal functionalization strategy with perfluoropolyether for the graphene family materials
Get PDFGraphene functionalization offers the opportunity to modify the chemical-physical properties of graphene, therefore broadening the variety of its possible applications. In this work, single- and few-layers graphene as well as highly oriented pyrolytic graphite (HOPG) were functionalized with perfluoropolyether (PFPE) chains via a peroxide decomposition and radical reaction. Samples were prepared using different amounts of PFPE peroxide and the effects of the treatment were studied through Raman spectroscopy, grazing angle Fourier-transform Infrared spectroscopy (GA-FTIR), X-ray Photoelectron Spectroscopy (XPS) and water contact angle measurements. A coherent trend of Fsingle bondC bonds with increasing amount of peroxidic precursor was detected, attacking the sp2 reactive sites of the grains of graphene itself and generating new sp3 hybridizations. The perfluorinated chains were found to give hydrophobic properties to graphenic layers, demonstrating the functionalization route as an easy and universal strategy for the preparation of hydrophobic graphenic substrates
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Functionalization of CVD multi-layer graphene and hard carbon with fluorinated reactive compounds for electrochemical applications
No full textLAUREA MAGISTRALELa struttura a strati dei materiali carboniosi, così come il loro alto grado di coniugazione, li rendono ottimi candidati nella progettazione di elettrodi, laddove buona conducibilità e alta capacità di interazione con specie ioniche siano richieste. In questo lavoro di tesi, grafene multistrato è stato deposto su substrati di nichel tramite CVD e successivamente funzionalizzato con catene perfluoropolieteree tramite un processo radicalico che sfrutta la decomposizione termica di un intermedio perossidico proveniente dalla sintesi del perfluoropolietere (PFPE) stesso. Il materiale non trattato è stato caratterizzato tramite analisi del grado di ricoprimento, di bagnabilità, di struttura cristallina e di composizione. La procedura di funzionalizzazione è stata ottimizzata per migliorare la riproducibilità del trattamento modificando gli stadi di rimozione del polimero non reagito e di asciugatura del solvente. I campioni di grafene sono stati trattati con diverse quantità di PFPE perossido e gli effetti della funzionalizzazione sono stato valutati tramite spettroscopia Raman e IR ad angolo radente, spettroscopia fotoelettronica a raggi X e misure di angolo di contatto. Infine, tre metodi per il calcolo dello spessore di PFPE deposto e per una valutazione della resa del processo sono proposti. I risultati riportano un aumento nell’idrofobicità della superficie del campione funzionalizzato senza alcuna modifica significativa alla struttura cristallina dello stesso, effetto spesso riscontrato nella funzionalizzazione con molecole a più basso peso molecolare. I provini sono stati testati come sensori elettrochimici per la rilevazione di acido perfluoroottanoico, acqua ossigenata e ossigeno disciolto. Si era ipotizzato che la presenza di uno strato di PFPE potesse migliorare le prestazioni degli elettrodi, data l’alta solubilità che gli analiti presi in considerazione hanno nel PFPE stesso. Tuttavia, è stato riscontrato solo un effetto protettivo contro l’adsorbimento fisico di agenti chimici presenti in soluzione.
Del carbone attivo è stato inoltre fluorurato con fluoro elementare per provocare una modifica superficiale della sua struttura, con l’obiettivo di migliorare la capacità di intercalazione di cationi e quindi le performance come anodo in batterie agli ioni di sodio. L’efficacia del trattamento è stata già testata per l’applicazione nelle batterie agli ioni di litio. I carboni attivi fluorurati sono stati caratterizzati nei termini della loro composizione a seguito di diversi metodi di trattamento, delle modifiche apportate alla struttura cristallina e all’area superficiale e dell’effetto sulla bagnabilità e sulle proprietà elettriche. I risultati dei test suggeriscono che la fluorurazione del carbone attivo possa aumentare la capacità alla prima scarica e rendere più omogeneo il calo di prestazioni a seguito dei cicli di carica-scarica.The layered structure of carbonaceous materials and their extensive conjugation makes them an ideal choice for applications as conductive materials for electrodes. In this thesis work multi-layer CVD graphene grown on nickel substrates was synthesized and functionalized with perfluoropolyether (PFPE) chains via a peroxide decomposition. The pristine material was characterized in terms of its degree of covering, wettability, structure and composition. The functionalization procedure was optimized in order to grant consistent results, by reducing the amount of unreacted polymer. Samples were prepared using different amounts of PFPE peroxide and the effects of the treatment were studied through Raman spectroscopy, grazing angle FT-IR, XPS and contact angle measurements. Three methods are finally presented for the estimation of the thickness of the functionalizing layer and of the yield of the process, using data from XPS and IR analyses. The perfluorinated layers was found to give hydrophobic properties to graphene without altering its lattice structure. Prepared samples were tested as sensing electrodes for perfluorooctanoic acid, hydrogen peroxide and dissolved oxygen. The PFPE layers were theorized to improve the sensing ability of graphene due to the high solubility of tested analytes in the polymer. Although, only a protective effect against adsorption of compounds in solution was detected.
Surface modification with elemental fluorine was also performed on hard carbon so as to improve intercalation of cations and thus yield better performances as an anode in Na-ion batteries. Carbon fluorination had already been found to be effective for the application in Li-ion batteries. In this work, fluorinated hard carbon was characterized and tested, with results suggesting an increase in the initial discharge capacity of the electrode and a smoother decrease in performances with cycling
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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