1,720,954 research outputs found
Lithium-aluminum-zinc phosphate glasses activated with Sm3+, Sm3+/Eu3+ and Sm3+/Tb3+ for reddish-orange and white light generation
No full textSpectroscopic evaluation of Sm3+, Sm3+/Eu3+ and Sm3+/Tb3+ doped lithium-aluminum-zinc phosphate glasses, based on excitation and emission spectra, and emission decay time measurements, were particularly focused on reddish-orange and white light emitting diode applications. The Sm3+ doped glass exhibits a reddish-orange emission tonality of 1676 K and a high color purity (CP) of 97.6% upon 408 nm excitation. The Sm3+/Eu3+ co-doped glass displays reddish-orange emission tonality of 1621 K (CP = 98.0%) and 2012 K (CP = 98.7%), upon 346 and 392 nm excitations, respectively. The Sm3+/Tb3+ co-doped glass emits neutral white light of 4946 and 4301 K upon 337 and 377 nm excitations, respectively, as well warm white light of 3504 K and reddish-orange light of 1758 K (CP = 91.5%) upon 370 and 396 nm excitations, respectively. The Sm3+/Tb3+ co-doped glass, excited at 337 and 396 nm, shows the highest values of luminous efficiency of radiation (LER = 444 lm/W) and color rendering index (CRI = 97), respectively. The Tb3+ and Sm3+ emission decay shortening in presence of Sm3+ and Eu3+, respectively, points out to Tb3+ -> Sm3+ and Sm3+ -> Eu3+ non-radiative energy transfers, with efficiencies of 8% and 21%, respectively. The Inokuti-Hirayama model suggests that such energy transfer processes might be dominated by an electric dipole-dipole interaction inside Tb3+-Sm3+ and Sm3+-Eu3+ clusters. (C) 2020 Elsevier B.V. All rights reserved
Li2O-Al2O3-ZnO-P2O5:Dy3+/Sm3+/Eu3+ glasses for solid-state yellow laser and color tunable phosphor applications
No full textLaser and optical properties (absorbance, excitation/emission and decay time data) of Dy3+, Dy3+/Sm3+, Dy3+/Sm3+/Eu3+-doped Li2O-Al2O3-ZnO-P2O5 glasses are investigated. Laser spectroscopic parameters of the dysprosium yellow emission show potentialities of the luminescent glass as yellow laser medium under excitation at 348 nm. The Dy3+/Sm3+-activated glass tonality can be shifted from neutral white of 4559 K under 350 nm excitation to yellowish-orange of 2033 K (85.3% color purity) upon 372 nm excitation. A shortening of the dysprosium F-4(9/2) level lifetime revealed that Sm3+ can be sensitized by Dy3+ by means of a non-radiative energy transfer that could be occurring into Dy3+-Sm3+ clusters with an efficiency of 0.13. The Dy3+/Sm3+/Eu3+-activated glass tonality can be shifted from warm white of 3387 K under 350 nm excitation to reddish-orange of 1638 K (92.1% color purity) upon 372 nm excitation. From lifetime data of the Dy3+ ion F-4(9/2) and Sm3+ ion (4)G(5/2) levels is inferred that non-radiative energy transfers from dysprosium to europium and/or samarium and from samarium to europium could be occurring into Dy3+-Sm3+-Eu3+ clusters with energy transfer efficiencies of 0.22 and 0.41, respectively
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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