1,721,082 research outputs found
Structure and dynamics of hydrogen in nanocomposite solid acids for fuel cell applications
No full textThe transition to sustainable energy sources is inevitable. A possible future scenario could be the hydrogen economy, where the fuel cell plays an important role in the conversion of hydrogen back to electricity. The technology behind the fuel cell however, still has significant room for improvement. A next step would be the realization of so called intermediate temperature fuel cells. Solid acids have been shown to be promising candidates for fuel cell electrolytes as they possess high proton conductivity in the intermediate temperature range, from ambient up to 250 °C. One major problem of the solid acids was the low proton conduction at temperatures below their superprotonic phase transition. This has been solved by nanostructuring the materials, where the solid acid is mixed with e.g. TiO2 or SiO2 nanoparticles of 40 nm in size and smaller. The conductivity increases with orders of magnitude. Here a multi-technique approach is used to study this matter. Using Neutron Diffraction, direct experimental proof of the occurrence of space charge effects in these nanocomposites was shown in the form of deuterium ion intercalation in TiO2 nanoparticles together with deuterium depletion in the solid acid CsHSO4 phase. Very high, particle size dependent proton densities, up to 10% in the 7 nm TiO2 particles were found. Quasi elastic neutron scattering experiments showed fractions of up to 25% of the hydrogen ions at temperatures below the superprotonic phase transition to possess mobilities similar to the protons above this transition. Nuclear magnetic resonance spectroscopy showed similar fractions as well as T1 relaxation times of roughly 2 orders of magnitude shorter compared to the bulk crystalline solid acids. These results lead to the conclusion that because of the space charge effect, vacancies are created in the solid acid at temperatures below the superprotonic phase transition temperature. These empty sites allow a large fraction of the hydrogen ions to move, to such an extent that they become almost as mobile as in the superprotonic phase. Furthermore a composite electrolyte of CsHSO4 and Nafion was synthesized. The composite electrolyte membrane showed good mechanical strength resulting from the Nafion polymer matrix. It exhibited similar proton conductivity to pure Nafion at low temperatures in a humid environment and showed high conductivity of 10-3 S/cm at intermediate temperatures around 140 °C, where Nafion filled with water is inoperable. Finally the investigation was extended to another solid acid: CsH2PO4. Using the multi-technique approach, these CsH2PO4 composites with nanoparticulate TiO2 or SiO2 were studied and compared to the CsHSO4 composites. Acidity was found to be indicative for the amount of space charge occurring. The results indicate a reduced space charge effect in CsH2PO4-TiO2 composites consistent with the reduced acidity of CsH2PO4 and lower proton accepting capacity of TiO2 compared to SiO2. Using the acidity combined with computer calculations might be a useful way to predict the extent of space charge in future research towards the optimal combination for electrolyte membrane material.Applied physics, R3, FAMEApplied Science
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
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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