1,720,959 research outputs found
Highly luminescent yttria–silica core–shell nanoparticles by the sacrificial polymer shell method
No full textThis paper describes the correlation existing between the photoluminescence of core–shell SiO2@Y2O3:Eu3+ nanoparticles synthesised by a method based on a sacrificial polymer-shell intermediate, and the thickness of that polymer shell. The method is based on the synthesis of a covalently bonded sacrificial polymer shell by polymerization of methacryl oxyethyl isocyanate (MOI) onto silica cores; the polymer shell was demonstrated to act as a promoter and stabilizer of the adsorption of yttrium and europium ions on the surface of silica, and its thickness plays an important role on the final luminescent intensity of the hybrid particles, which is related to the adhesion and continuity of the lanthanide shell of SiO2@Y2O3:Eu3+ nanoparticles. Yttria shells were obtained with thickness varying in the range 3–20 nm by tuning the polymer shell thickness in the range 0–50 nm. Results demonstrate that photoluminescence of SiO2@Y2O3:Eu3+ nanoparticles prepared via the sacrificial polymer shell method is much higher with respect to nanoparticles obtained by a traditional procedure
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
Synthesis of Suitable SiO2 Nano Particles as the Core in Core–Shell Nanostructured Materials
No full textThe effect of surfactant on the luminescent intensity of SiO2@Y2O3:Eu3+ particles with a core shellstructure is described. Core–shell particles are used in phosphor materials and employing sphericalparticles with a narrow size distribution is vital for the enhancement of luminescent properties. Threekinds of different surfactants were used to synthesis SiO2 nano particles via a sol gel process. Theresults demonstrated that comb polycarboxylic acid surfactant had a significant influence on themorphology and particle size distribution. Somehow, particles with 100 nm size and narrow sizedistribution were produced. These particles had relatively uniform packing, unlike particles producedwith other surfactants or without surfactant which had irregular assembly. The photoluminescenceintensity of SiO2@Y2O3:Eu3+ particles that was synthesized by comb polycarboxylic acid surfactantwas higher than those which were produced without surfactan
Novel approach to the synthesis of core–shell particles by sacrificial polymer-shell method
No full textIn this work a new approach has been developed for the synthesis of SiO2@Y2O3 particles with core–shellstructure. The method is based on the synthesis of a covalently bonded sacrificial polymer shell grown ontosilica particles. It is suitable to promote and stabilize the adsorption of different ions, namely Yttrium from itsnitrate solution. After calcination and consequent elimination of the sacrificial polymer shell, the SiO2@Y2O3core–shell particles are obtained. Results reveal that the shell thickness of these core–shell particles is higherand more uniform than that of particles prepared without sacrificial polymer shell
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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