1,721,026 research outputs found
Electrochemical polymerisation of phenol in aqueous solution on a Ta/PbO2 anode
Full text linkThis paper deals with the treatment of aqueous phenol solutions using an electrochemical technique. Phenol can be partly eliminated from aqueous solution by electrochemically initiated polymerisation. Galvanostatic electrolyses of phenol solutions at concentration up to 0.1 mol dm−3 were carried out on a Ta/PbO2 anode. The polymers formed are insoluble in acidic medium but soluble in alkaline. These polymers were filtered and then dissolved in aqueous solution of sodium hydroxide (1 mol dm−3). The polymers formed were quantified by total organic carbon (TOC) measurement. It was found that the conversion of phenol into polymers increases as a function of initial concentration, anodic current density, temperature, and solution pH. The percentage of phenol polymerised can reach 15%
Facilitated Electron Hopping in Nanolayer Oxygen-Insensitive Glucose Biosensor for Application in a Complex Matrix
No full textElectrochemical experimental evidence of facilitated electron transfer in a sub-micrometer biosensor is presented. Layer-by-layer self-assembled deposition provides the unique advantage to specifically control the thickness of the biosensors, allowing an oxygen-insensitive device with a film thickness of 70 nanometers to be obtained. The biosensor is based on a poly(allylamine) osmium redox mediator and glucose 1-oxidase. The immobilized enzyme contributes to the signal generation through the full biosensor thickness, with no loss of “active enzyme” in the outer layer of the biosensor through reaction with oxygen, as reported in the case of thick redox hydrogels. The application of the biosensor in complex matrices was approached with tests in wastewater. Encapsulation of the biosensor with Nafion® membrane ensured the protection of the enzyme molecules from the external environment, allowing the successful application of the sensor in a complex matrix
EFFECT OF CALCINATION TEMPERATURE ON THE SURFACE PROPERTIES OF Ti/RuO2-SUPPORTED Co3O4 LAYERS.A SPECTROSCOPIC INVESTIGATION
No full textPTFE effect on the electrocatalysis of the oxygen reduction reaction in membraneless microbial fuel cells
No full textInfiuence of PTFE in the external Gas Diffusion Layer (GDL) of open-air cathodes applied tomembranelessmicrobial fuel cells (MFCs) is investigated in thiswork. Electrochemicalmeasurements on cathodeswith different PTFE contents (200%, 100%, 80% and 60%)were carried out to characterize cathodic oxygen reduction reaction, to study the reaction kinetics. It is demonstrated that ORR is not under diffusion-limiting conditions in the tested systems. Based on cyclic voltammetry, an increase of the cathodic electrochemical active area took placewith the decrease of PTFE content. This was not directly related to MFC productivity, but to the cathode wettability and the biocathode development. Low electrodic interface resistances (from 1 to 1.5 Ω at the start, to near 0.1 Ω at day 61) indicated a negligible ohmic drop. A decrease of the Tafel slopes from120 to 80mV during productive periods of MFCs followed the biological activity in the whole MFC system. A high PTFE content in the cathode showed a detrimental effect on the MFC productivity, acting as an inhibitor of ORR electrocatalysis in the triple contact zone. The lowest PTFE content (60%) manifested mechanical instability of the cathode, together with the best performance
Electrochemical behavior of archaeological arsenical bronzes according to the concentration of arsenic in the alloy|Comportamento elettrochimico di bronzi archeologici arsenicali in funzione della concentrazione dell'arsenico in lega
Full text linkn questo studio si è voluto comprendere come la concentrazione di arsenico in lega influenzi i fenomeni di corrosione in leghe di rame archeologiche. Sono state condotte analisi elettrochimiche su tre leghe in triplicato (denominate CuAs-1, CuAs-3, CuAs-5 sulla base delle diverse percentuali in peso di As in lega). I risultati elettrochimici, confrontati con quelli di campioni di rame puro, indicano che la presenza di arsenico comporta un sostanziale miglioramento del comportamento a corrosione e la lega migliore è quella con il più alto contenuto di arsenico. Questi dati sono confermati dalle analisi spet- troscopiche che indicano la formazione di uno strato di ossidi protettivi misti di rame e arsenico. La minore resistenza alla corrosione del rame è stata invece collegata alla presenza in superficie di sali solubili
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
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