1,721,205 research outputs found
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
Role of Ga<sup>3+</sup> Sites in Ethene Oligomerization over Ga/H-MFI
No full textBecause of their relatively low cost,
ethane and propane derived
from shale gas are the currently preferred feedstocks for the production
of aromatics. Ga-exchanged H-MFI zeolite (Ga/H-MFI) exhibits high
activity and selectivity for light alkane dehydroaromatization, a
process that involves alkane dehydrogenation to form alkenes, followed
by alkene oligomerization and cyclization, and further dehydrogenation
of the resulting products. Recent work has shown (Phadke et al. Characterization
of Isolated Ga3+ Cations in Ga/H-MFI Prepared by Vapor-Phase
Exchange of H-MFI Zeolite with GaCl3. ACS Catal.2018,8, 6106–6126; Phadke
et al. Mechanism and Kinetics of Propane Dehydrogenation and Cracking
over Ga/H-MFI Prepared via Vapor-Phase Exchange of H-MFI with GaCl3. J. Am. Chem. Soc.2019,141, 1614–1627; Phadke et al. Mechanism and Kinetics
of Light Alkane Dehydrogenation and Cracking over Isolated Ga Species
in Ga/H-MFI. ACS Catal. 2021,11, 2062–2075; Mansoor et al. ACS Catal. 2018,8, 2146–6162) that Ga3+ ([GaH]2+ and [Ga(H)2]+)
sites catalyze the initial dehydrogenation of alkanes; however, the
role of Ga3+ sites in the subsequent alkene oligomerization
step requires clarification. In this work, the kinetics of ethene
oligomerization over Ga/H-MFI were investigated as a function of Ga
loading, feed space time, temperature, and ethene partial pressure.
The presence of Ga3+ sites gives rise to enhanced rates
of ethene oligomerization and higher selectivities to butene and hexene
relative to H-MFI. However, selective titration of Brønsted acid
sites with NH3 reveals that, in the absence of Brønsted
acid sites, [GaH]2+ and [Ga(H)2]+ cations do not contribute appreciably to the higher activity of
Ga/H-MFI. Similarly, in situ Fourier-transform infrared spectroscopy
shows that the reaction pathway for ethene oligomerization over Ga/H-MFI
involves the same intermediates as that over H-MFI. The higher ethene
oligomerization activity and selectivity to even-carbon-numbered alkenes
of Ga/H-MFI stems from cooperative effects between Ga3+ sites and Brønsted acid protons
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
Understanding the Correlation between Ga Speciation and Propane Dehydrogenation Activity on Ga/H-ZSM‑5 Catalysts
No full textH-ZSM-5 zeolite-supported Ga (Ga/H-ZSM-5)
has been considered as
a selective catalyst for nonoxidative propane dehydrogenation (PDH)
for decades; however, the reaction mechanism remains a topic of considerable
discussion. In particular, the correlation between various Ga species
present on the catalyst at the reaction conditions and the PDH activity
has yet to be established. In this work, intrinsic PDH rates and activation
energies were determined on Ga+–H+ pair
sites and isolated Ga+ sites on Ga/H-ZSM-5 samples with
a wide range of Si/Al and Ga/Al ratios. The turnover frequency on
Ga+–H+ pair sites in the PDH is higher
than that of isolated Ga+ sites by a factor of ∼15.
Experimental measurements combined with a dual-site model show the
activation energy in the PDH on the Ga+–H+ pair sites and isolated Ga+ sites to be 90.8 ± 1.5
and 117 ± 4.7 kJ·mol–1, respectively.
These results demonstrate that Ga+–H+ pair sites are much more active in the PDH than isolated Ga+ sites. The activation energy of GaHx decomposition to form H2 was determined to be 40–60
kJ·mol–1 higher than that of the PDH on Ga
species, suggesting that the GaHx decomposition
is unlikely to be part of the PDH mechanism. Although both Brønsted
acid and Ga sites interact with propane, Fourier transform infrared
spectroscopy results provide strong evidence suggesting that the alkyl
mechanism is more likely in the PDH on Ga/H-ZSM-5 catalysts
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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