1,720,958 research outputs found
Study of structure reactivity relationships for cobalt-based electrocatalysts for the CO2 electroreduction.
No full textThe CO₂ electrochemical reduction reaction (CO₂ERR) is a promising technique for tackling green gas emissions and creating value-added chemical products. However, shortcomings like poor selectivity for some products and low stability make it harder to expand the CO₂ERR to industrial scales. Identifying the nature of the reactive sites of CO₂ERR catalysts is key to developing materials with high reactivity and selectivity. In this thesis, several research approaches were investigated to bring new light onto the reactive structure of Co-based catalysts.
Several Co-based compounds were dispersed on carbon black support and tested for the CO₂ERR to identify the common structural features between the reactive materials. Among the screened materials, only cobalt phthalocyanine (CoPC), cobalt tetraphenyl porphyrin (CoTPP) and vitamin B12 (VB12) were active for the production of CO at high faradaic efficiency, suggesting that the structural features necessary to make a Co compound reactive for the CO₂ERR are a π-conjugated macrocycle and the presence of heteroatoms around the Co centre.
The following study reported the effects of pyrolysis in argon on the structure and reactivity of CoPC supported on carbon black and showed that at 700 °C and higher temperatures, materials with a high CO₂ERR activity and a structure significantly different to that of the non-pyrolyzed material were formed. This work also showed that the presence of carbon support was paramount to forming active materials upon pyrolysis.
The relation between the loadings of the CoPC catalytic precursor on carbon-based support and the CO₂ERR activity of the pyrolyzed precursor was then investigated. With X- ray diffraction and X-ray absorption spectroscopy analysis, it was demonstrated that only the materials with high loading and crystals of CoPC pre-pyrolysis had decent CO₂ERR activity at high temperatures and that the structure of the pyrolyzed material was related to the loading of Co precursor.
The study of the pyrolysis effects was also extended to the previously identified reactive materials, CoTPP and VB12 dispersed on carbon black, and their properties were compared to the results previously obtained on the pyrolyzed CoPC supported on carbon black. The CO₂ERR activities of the 700 °C pyrolyzed materials were similar between the three studied catalysts, and X-ray absorption spectroscopy analysis revealed that the structures surrounding the Co core were almost undistinguishable between the different pyrolyzed materials. Hence, the reactive cores of the pyrolyzed catalysts are likely identical. These results confirm that pyrolyzed Co macrocycles can be viable materials for the CO₂ERR and give new hindsight on the nature of their reactive structures.
Future work should attempt the synthesis of materials with the structural features identified in this work to validate the hypothesis on the nature of the reactive core. If successful, this would allow the design of a wide range of materials that could overcome the current shortcomings of the CO₂ERR catalysts. Future studies should also investigate the effect of pyrolysis on materials with other metallic centres, such as Cu or Ni, and compare the chemical stability of the different materials. Finally, in-situ characterisation should be undertaken to determine the reactive structures of the materials during the CO₂ERR
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
No full text“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
No full textWe 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
No full textWe 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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