1,720,982 research outputs found
Card from Monsignor G. Sinibaldi to Hagan
No full textHolograph card from Monsignor G. Sinibaldi, secretary to the Congregation for Seminaries and Universities, to Hagan, introducing his nephew Giacomo Modesti; asking to assist him
F-doped TiO2 prepared by flame spray pyrolysis: effect on the photoelectrochemical performance
No full textPhotoelectrochemical water splitting performed with semiconductor materials has attracted attention due to potential clean energy production, achievable utilizing light. In this context, TiO2 is the most investigated semiconductor, though characterized by i) low rate of photopromoted e- transfer and ii) high recombination rate of photoproduced charge carriers (e-/h+ pairs). Doping with non-metal elements is often suggested as a valuable remediation to limit the occurrence of these two drawbacks.
In line with this, a series of fluorine-doped TiO2 samples (with F/O ratio varying in the 1–10 at.% range) were synthesized, in single step, by flame spray pyrolysis starting from organic solutions containing titanium tetra-isopropoxide (Ti(OC3H7)4) and hexafluorobenzene (C6F6) as titanium and fluorine precursors, respectively.
By means of the selected synthesis technique, doping can be conveniently carried out by co-dissolving the dopant source, along with the TiO2 precursor, directly in the employed solvent (i.e., xylene), with a precise engineering of dopant concentration during synthesis.
Quantitative crystalline phase analysis, performed by applying the Rietveld refinement method to XRPD data, highlighted the presence of both anatase and rutile phases in all the prepared samples, with the former being always predominant. Accordingly, all samples exhibited a UV-vis absorption edge at λ = ca. 400 nm.
The prepared powders were then deposed on fluorine-doped tin oxide (FTO) glass by means of the doctor-blade technique, to investigate the effect of F-doping on the photoelectrochemical activity of TiO2. Incident Photon-to-Current Efficiency (IPCE), reflecting the semiconductor’s ability of generating and transferring photopromoted e-/h+ under irradiation and suitable applied voltage, was found to increase with increasing the F-dopant concentration, up to a F/O ratio of 5 at.%.
This finding pointed to an improved separation of photopromoted electron-hole pairs, ascribed to the formation of intra-band gap states, induced by fluorine doping and able to efficiently trap photoproduced charge carriers. Conversely, when the amount of F-doping exceeded the optimum value, structural defects acting as e-/h+ recombination centers were formed, reasonably yielding lower photocurrent
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
Size-dependent performance of CdSe quantum dots in the photocatalytic evolution of hydrogen under visible light irradiation
No full textNanocrystalline materials are widely employed as photocatalysts for water splitting applications. In particular, cadmium selenide quantum dots (QDs) attracted growing interest for their superior photon to H2 conversion efficiency and their stability under irradiation. A direct insight is here presented on the effects that CdSe QDs size has on their photoactivity in hydrogen evolution from Na2SO3 – containing aqueous solutions under visible light irradiation. Four highly monodisperse CdSe quantum dots with different nanocrystal diameters were synthesized and, after exchange of the capping ligand, employed as photocatalyst in H2 production in the absence of any co-catalyst. Their size-dependent photocatalytic activity is discussed in relation to their absorption properties, their conduction band energy and the recombination probability of the photogenerated charges inside the nanocrystals. High quantum efficiency in H2 generation results from a balance among these three QDs features, their activity scale being not exclusively dominated by the photocatalyst conduction band position
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
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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