1,720,970 research outputs found
First-Principles Study of Twin 4–8 Graphene in Carbon and Boron Nitride Nanostructures: Implications for Mechanical and Optoelectronic Nanodevices
No full textA nanosheet with the name twin 4–8
graphene composed
of
4- and 8-membered rings is suggested. The structural, mechanical,
electronic, and optical properties of carbon (C) twin 4–8 graphene
and twin 4–8 graphene-like boron nitride (BN) sheets are studied
by using density functional theory. These sheets exhibit dynamic stability
as well as good energetic and thermal stability, especially at room
temperature. The C and BN twin graphene sheets are softer and more
prone to deformation compared to graphene. Thus, they can be used,
particularly when softer materials are required rather than graphene.
The C twin 4–8 graphene exhibits semiconductor properties,
while the BN twin 4–8 graphene is an indirect band gap insulator.
An anisotropic behavior is observed for the optical properties of
the sheets. These sheets could store energy and filter out harmful
ultraviolet radiation due to their high dielectric constants and optical
absorption, particularly in the ultraviolet region. These nanosheets
are well suited for use in nanomechanics and nano-optoelectronics
due to their favorable mechanical, electronic, and optical characteristics
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
Mechanical properties of novel forms of graphyne under strain: A density functional theory study
No full textStructural and Electronic Properties of α2-Graphyne Nanotubes: A Density Functional Theory Study
No full textSensing Caffeine and Nicotine with Biphenylene Carbon, α-Graphyne Sheet and Nanotube: A Density Functional Theory Study
No full textWe have used density functional theory to study adsorption of caffeine and nicotine on carbon based nanostructures. The effect of caffeine and nicotine molecules on the electronic properties of α-graphyne, biphenylene carbon, and (4,0) nanotube based on α-graphyne were studied. It was found that caffeine and nicotine molecules were adsorbed strongly on these sheets and nanotube. The charges were transferred from molecules to the sheets and nanotube. Because of adsorption of these donor molecules, biphenylene carbon, α-graphyne sheet and nanotube become n-type semiconductors. Sensitivity of the electronic properties of these sheets and nanotube to adsorption of caffeine and nicotine indicate the carbon based nanostructures can be used for detection of caffeine and nicotine molecules.</jats:p
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
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