1,721,062 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
A study on multilayered MXenes for rechargeable battery electrodes through surface termination control
Full text linkIn the transition from fossil fuels to renewable energy sources, the demand for rechargeable batteries is rapidly increasing. To meet this demand, a diversification of battery chemistries will be essential, due to limited abundance of currently used battery materials. In addition to Li-ion batteries (LiBs), rechargeable Mg batteries (RMBs) stand out as a theoretically promising battery chemistry, with the potential to yield high energy batteries based on abundant materials. However, to enable practical RMBs, competitive cathode materials need to be established. Potential candidates may come from the family of two-dimensional transition metal carbides and nitrides known as MXenes, which due to their high electrical conductivity, chemical tunability and ion intercalating properties, have been predicted to yield high intercalation capacities for a range of cations, including Mg-ions. Hence, this study aimed towards evaluating the feasibility of MXenes for rechargeable battery electrodes, and in particular for RMBs.
In the first paper of this work, the feasibility of MXenes as an RMB cathode was investigated by using two different MXene compositions: V2C and Ti3C2. To ensure the possibility for Mg-ion desolvation and migration, these electrodes were galvanostatically cycled in cells with four different electrolytes, and at both low (20 oC) and high (60 oC) temperatures. Still, only minimal capacities were obtained, indicating insignificant reversible Mg-intercalation in the MXene particles. However, by including Li-salts to the electrolyte, significant reversible capacities were measured, demonstrating the functionality of the MXene electrodes. To explain this difference, density functional theory (DFT) calculations were implemented and showed that the migration barriers for Mg-ions were significantly higher than for Li-ions, and that the termination groups attached to the surface of the MXene sheets strongly influenced the intercalation voltages for Li and Mg-ions. Denoted as "T" (i.e. V2CTx), these termination groups usually consist of a mixture of OH, O and F, and the DFT calculations showed that multilayered particles of O-terminated MXenes would be ideal for RMB cathodes. Hence, the focus of this work was directed towards controlling the termination groups of MXenes, and especially towards substituting F- with O-terminations.
In the second and third paper of this work, gas hydrolysation was explored as a post etching treatment to substitute F-terminations in multilayered V2CTx and Ti3C2Tx MXenes, respectively. It was found that successful hydrolysation required a MXene structure with an expanded interlayer spacing, to allow the water molecules to penetrate in between the MXene sheets. For the V2CTx phase, this was achieved by intercalated water molecules from the HF etching step, whereas the Ti3C2Tx phase required preintercalation of cations prior to hydrolysation. For both phases, a F-reduction around 70 % was achieved, demonstrating the greatest F-reduction in multilayered particles reported so far. However, due to challenges of quantifying the remaining terminations (O vs. OH vs. unterminated), the exact composition of the final MXenes remained unclear. Although the F-reduction was clear for both MXene phases, no increase in capacity was observed upon cycling in RMB coin cells. To investigate the termination group’s influence on the electrochemical performance, MXene electrodes were thus cycled in LiBs. This resulted in dissimilar changes for the two MXene compositions. Where the hydrolysed V2CTx phase displayed an enhanced rate capability compared to the pristine MXene, the opposite was true for the Ti3C2Tx MXene. The Ti3C2Tx phase also showed increased average voltages and capacities after hydrolysation, which was not observed for the V2CTx phase. Based on these ambiguous changes in electrochemical performance, and the uncertain composition of the resultant termination mixtures, no clear conclusion on the effect of termination change could be drawn from this work. To ensure controlled formation of O-terminated MXenes, further refining of the hydrolysis method will be required, combined with enhanced termination characterisation.
In addition to the published results, the thesis includes new results on a F-free etching method based on hydrothermal treatment in concentrated NaOH solutions. These etching
conditions allowed for F-free Ti3C2Tx MXene, while the synthesis of other MXene compositions was not successful. Whereas all of the Ti2AlC, Ti2AlN, Ti3AlCN, TiMo2AlC2, Nb4AlC3, Nb2AlC, V2AlC and V4AlC3 MAX phase precursors demonstrated significant oxidation, the former three showed possible signs of some unordered MXene. Further investigation, with optimised etching conditions, is therefore required to conclude about this etching method’s compatibility to form other MXene phases than Ti3C2Tx. Nevertheless, due to the mixture of O- and OH-terminations, this etching method is not ideal for optimal termination control. In comparison, a recently reported etching method, based on Lewis acid etching in molten salts, has enabled synthesis of homogeneously terminated MXenes from different precursors, and with various terminations
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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