1,721,021 research outputs found
On the Polarity of Buckminsterfullerene with a Water Molecule Inside
No full textSince the recent achievement of Kurotobi and Murata to capture a water
molecule in a C60 fullerene (Science 2011, 333, 613), there has been a debate about the
properties of this H2O@C60 complex. In particular, the polarity of the complex, which is
thought to be underlying the easy separation of H2O@C60 from the empty fullerene by HPLC,
was calculated and found to be almost equal to that of an isolated water molecule. Here we
present our detailed analysis of the charge distribution of the water-encapsulated C60 complex,
which shows that the polarity of the complex is, with 0.5 ± 0.1 D, indeed substantial, but
significantly smaller than that of H2O. This may have important implications for the aim to
design water-soluble and biocompatible fullerenes
Interaction of H2with a Double-Walled Armchair Nanotube by First-Principles Calculations
No full textWe have studied, by first-principles methods, the interaction of molecular hydrogen with a double-walled (2,10) carbon nanotube (DWCNT). This combination of the smallest possible diameter for the inner nanotube with a significantly larger outer tube allows for substantial space between the nanotube walls, in which molecular hydrogen can adsorb. We performed classical force field molecular dynamics simulations of the infinitely extended (periodic) DWCNT with varying amounts of hydrogen, which showed that, depending on the H-2 loading, both a coaxial and a noncoaxial DWCNT configuration can be stable. We then carried out the electronic structure calculations on both the coaxial and the noncowdal geometries of the nanotubes to accurately compute the H-2 adsorption pathways inside the DWCNT. Interestingly, the noncoaxial DWCNT (2,10) shows a barrierless reaction path to dissociate the H-2 molecule. We also investigated the case of a DWCNT of finite length, whose edges are either clean or terminated with H atoms, and we searched for the favorite adsorption sites for a H-2 molecule in the interstitial region between the inner and the outer tube. The finite DWCNT whose edges are passivated by H atoms can be suggested as a potential candidate for hydrogen storage. The H-2 molecules, in fact, may enter in the cavity between the two nanotubes without reacting with the dangling bonds of the C atoms and can be physisorbed with a binding energy of about 0.06 eV, suitable for hydrogen storage. We emphasize the important role played in the physisorbed states for all the systems studied by the van der Waals interactions, which are properly included in the present study. Compared to the interaction of H-2 with graphene and the single-walled carbon nanotube (SWCNT), the existence of another carbon layer, for the coaxial DWCNT, does not significantly lower the energy barriers for chemisorption and instead enhances the binding energy of the H-2 molecule to the inner tube up to 0.1 eV
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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