1,720,995 research outputs found
Chemical synthesis and structural characterization of highly disordered ni colloidal nanoparticles
Get PDFThis work focuses on synthetic methods to produce monodisperse Ni colloidal nanoparticles (NPs), in the 4−16 nm size range, and their structural characterization. Narrow size distribution nanoparticles were obtained by high-temperature reduction of a nickel salt and the production of tunable sizes of the Ni NPs was improved compared to other methods previously described. The as-synthesized nanoparticles exhibited spherical shape and highly disordered structure, as it could be assigned by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Annealing at high temperature in organic solvent resulted in an increase of nanoparticle atomic ordering; in this case, the XRD pattern showed an fcc-like structure. Complementary data obtained by X-ray absorption spectroscopy confirmed the complex structure of these nanoparticles. Temperature dependence of the magnetic susceptibility of these highly disordered Ni NPs showed the magnetic behavior cannot be described by the conventional superparamagnetic theory, claiming the importance of the internal structure in the magnetic behavior of such nanomaterials.Fil: Winnischofer, Herbert. Brazilian Synchrotron Light Laboratory; BrasilFil: Rocha, Tulio C. R.. Universidade Estadual de Campinas; BrasilFil: Nunes, Wallace C.. Universidade Estadual de Campinas; BrasilFil: Socolovsky, Leandro Martín. Universidade Estadual de Campinas; Brasil. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Knobel, Marcelo. Universidade Estadual de Campinas; BrasilFil: Zanchet, Daniela. Brazilian Synchrotron Light Laboratory; Brasi
A new activation process of bimetallic catalysts and application to the n-hexane isomerization
Get PDFBimetallic catalysts applied to the n-hexane isomerization reaction were prepared with a constant molar content of 130 μmol Me/gcat of Ni and Pt and characterized in its active form by X-ray absorption near edge spectroscopy (XANES), transmission electron microscopy (TEM), temperature programmed reduction and hydrogen chemisorption techniques. The metal was dispersed in a HUSY zeolite matrix in order to provide both types of sites, metallic and acid, to obtain a bifunctional catalyst. The catalytic activity was evaluated using the catalyst activated at different temperatures following a new activation process, named "fast activation method" and the profile pointed out a maximum catalytic activity when the catalyst was activated at 400 °C. XANES results showed that all samples present similar electronic properties in the studied conditions, despite the differences found in the average particle diameter obtained by TEM, suggesting that the catalytic activity is related to the metal/acid balance.Fil: Yoshioka, Carlos M.N.. Universidade Federal do São Carlos; BrasilFil: Jordão, Maura H.. Laboratorio Nacional de Luz Sincrotron;Fil: Zanchet, Daniela. Laboratorio Nacional de Luz Sincrotron;Fil: Garetto, Teresita Francisca. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Cardoso, Dilson. Universidade Federal do São Carlos; Brasi
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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