1,720,980 research outputs found
Magnetic states and intervalence charge transfer of Ti and Fe defects in α-Al2O3: The origin of the blue in sapphire
No full textWe investigate the total energies and electronic structures of Ti-Fe pair defects in alpha-Al2O3 by carrying out density-functional-theory calculations for various configurations of spin, charge, and orientation of Ti-Fe pair. From the total energy results, we show that the high-spin state of Ti-IV-Fe-II with an anti-ferromagnetic alignment between Ti and Fe is the ground state for both edge- and face-sharing orientations. Among several meta-stable states, the high-spin state of Ti-III-Fe-III with an anti-ferromagnetic alignment is connected to the Ti-IV-Fe-II ground state. An optical transition from the highest occupied Fe defect level to the lowest unoccupied Ti leads to an excited state of the high-spin Ti-III-Fe-III configuration together with a donation of electron from Fe-II to Ti-IV. It explains that the intervalence charge transfer from Ti-IV-Fe-II to Ti-III-Fe-III is responsible for the color of blue in sapphire. In addition, the total energies of Ti-IV-Fe-II ground state are found to be quite close within 0.02 eV for both edge- and face-sharing orientations, but the optical excitation energies for edge- and face-sharing orientations are 1.99 and 1.36 eV, respectively. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.OAIID:RECH_ACHV_DSTSH_NO:T201800184RECH_ACHV_FG:RR00200001ADJUST_YN:EMP_ID:A072080CITE_RATE:6.036FILENAME:Na-Phattalung_ActaMaterialia_2018.pdfDEPT_NM:물리·천문학부EMAIL:[email protected]_YN:YFILEURL:https://srnd.snu.ac.kr/eXrepEIR/fws/file/1a5436cb-541d-4639-a5ca-429bf23e409c/linkN
Synthesis, characterization, and self-assembly of pencil-shaped CoO nanorods
No full textWe synthesized uniformly sized, pencil-shaped CoO nanorods by the thermal decomposition of a cobalt-oleate complex, which was prepared from the reaction of cobalt chloride and sodium oleate. The diameters and lengths of the CoO nanorods were easily controlled by varying the experimental conditions, such as the heating rate and the amount of Co-oleate complex. The X-ray diffraction pattern revealed that the CoO nanorods have an extraordinary wurtzite ZnO crystal structure. These uniformly sized nanorods self-assembled to form both horizontal parallel arrangements and perpendicular hexagonal honeycomb superlattice structures. Reduction of the nanorods by heating under a hydrogen atmosphere generated either hcp Co or Co2C nanorods. Characterization of the CoO nanorods using X-ray absorption spectroscopy, X-ray magnetic circular dichroism spectroscopy, and magnetic measurements showed that they contain a small fraction of ferromagnetic Co impurities.N
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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