1,721,011 research outputs found
Da Canzoneri ad oggi: i componenti fenolici degli oli extravergini di oliva. Struttura chimica, ruolo e metodi analitici per la determinazione
No full textI biofenolici, componenti idrosolubili presente negli oli vergini di oliva, differenziano
questo prodotto dagli altri oli edibili. Questi composti svolgono diverse funzioni, in particolare sono importanti per la conservabilità del prodotto, intervenendo come antiossidanti,svolgono funzioni nutrizionali e infine lo caratterizzano sensorialmente
conferendogli particolari sensazioni gustative. Dal 1961 ad oggi sono state utilizzate numerose tecniche analitiche sia per la fase preparativa che per la separazione e quindi quantificazione dei diversi composti. Per quanto concerne la fase preparativa si utilizzano
diverse tecniche estrattive, in particolare liquido-liquido (L/L) con l’impiego di
differenti miscele di solventi, o estrazione su fase solida (SPE) con varie fasi stazionarie
e miscele eluenti. Per questa fase sono stati messi a confronto diversi metodi L/L con più solventi e SPE con diverse fasi stazionarie e mobili (Carrasco-Pancorbo et al., 2005°. I risultati hanno evidenziato recuperi elevati e prestazioni paragonabili per quanto
riguarda il metodo di estrazione L/L condotto con una miscela metanolo/acqua (60/40, v/v) e SPE con fase stazionaria diolica. La differenza principale nei due metodi è rappresentata dai costi di estrazione, minore per L/L e nei tempi di analisi, più rapidi per la SPEdiolica,per via della veloce fase di evaporazione del solvente di eluizione (metanolo) più volatile della miscela metanolo/acqua. Relativamente alla separazione dei singoli composti fenolici la prima tecnica utilizzata è stata la gascromatografia capillare (CGC) e la più diffusa è la cromatografia liquida ad alta prestazione in fase inversa (RPHPLC); tuttavia, recentemente l’elettroforesi capillare (CE) è stata applicata a tale scopo con buoni risultati
Electromagnetic simulators for the modelling of magnetically biased graphene
No full textIn this work, a novel procedure for the simulation of magnetically-biased graphene by means of standard simulators, is made available. To this aim, the similarity of graphene with lossy ferrite has been exploited. Simulations can be performed at microwave frequency, from DC up to 100 GHz, where the electromagnetic response of graphene is almost flat. The Duality theorem is applied to establish the formal equivalence of a thin layer of un-biased ferrite with biased graphene: boundary conditions and excitations are properly set in order to respect this equivalence. The simulation test-case is given by transmission/reflection of a plane-wave through a graphene sheet, with normal incidence. In order to validate the numerical results, simulations are performed also by independent analytical method
Efficient characterization of the electromagnetic-coupling of wire antennas- and graphene patches
No full textIn this contribution, the simulation of electromagnetic coupling of a wire antenna and graphene by means of standard electromagnetic simulators, has been carried out. Simulations are performed at microwave frequency, from DC up to 100GHz, where the electromagnetic response of graphene is almost flat. The actual simulated device is given by a resonating wire-antenna, made of a CNT of finite conductivity, perturbed by the close proximity of a graphene patch: many other choices were possible, but the present test resembles the interaction of a microscope-tip with graphene, and may have some interesting fallouts on the experimental side. All the simulations are performed, for comparison, by an independent tool, based on the method of moments. © 2014 European Association on Antennas and Propagatio
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
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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