1,721,017 research outputs found
Nanostructured carbon-crystalline titania composites from microphase separation of poly(ethylene oxide-b-acrylonitrile) and titania sols
No full textA simple "one-pot'' method utilizing a graphitic carbon source containing poly(ethylene oxide-b-acrylonitrile) diblock copolymer as a structure directing agent was used to synthesize carbon-crystalline titania composites as well as crystalline mesoporous titania materials after oxidative carbon removal.
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
Block Sequence Directed Materials: Functional And Ordered Nanocomposites Derived From Block Copolymer Coassembly
Get PDFNanocomposite materials with ordered structures are critical for the advancement of numerous fields ranging from microelectronics to energy conversion and storage. However, there are few techniques for controlling the necessary nanoscale morphologies and compositions which are compatible with affordable, large-scale manufacturing. The coassembly of block copolymers with inorganic materials provides such a route to achieve controlled nanomaterials, but such examples have generally resulted in mesoporous single-component materials. In this thesis it is shown that the general challenge to achieve multifunctional nanocomposites directly from block copolymer coassembly may be surmounted by designing novel block copolymers where each block has the design intent to result in a functional component of the resulting nanocomposites. Such a method would enable block sequence directed materials (BSDM), where a sequence of three or more chemically unique polymer blocks direct the spatial arrangement and interface definitions of multiple functional materials. Towards this end, four examples are provided. First, a diblock copolymer poly(ethylene oxide-b-acrylonitrile) is demonstrated to enable direct synthesis of nanocomposites composed of crystalline titania and partially-graphitic carbon. Second, this method is expanded by adding a third chemically unique block to form PAN-b-PEO-b-PPO-b-PEO-b-PAN where now the use of three chemically distinct polymer blocks enabled control over each of the three final components: partiallygraphitic carbon, crystalline transition metal oxide, and porosity. Although these nanocomposites only possessed short-range order, tuning of the individual block lengths and block fractions resulted in control over the three components. Third, it is shown that highly-ordered, multi-ply nanocomposites can result from the coassembly of poly(isoprene-b-styrene-b-ethylene oxide) (ISO) triblock terpolymers. Tuning the ratio of nanoparticles to ISO enabled access to four unique morphologies and the selection of quasi-1D, 2D, or 3D pathways. Fourth, it is shown that an ordered 3D network morphology which is chiral (non-centrosymmetric) can result from the coassembly of an ISO with a particular composition. Such non-centrosymmetric nanostructures are necessary to enable macroscopic polarization for piezoelectric, pyroelectric, and second-order nonlinear optical properties in amorphous materials. Thus through these four examples, it is demonstrated that the tuning of the polymer-oxide coassembled systems enables control over both nanocomposite composition and morphology
Single-Variable Porous Nanomaterial Series From Polymer Structure-Directing Agents
Get PDFBlock polymer structure-directing agents (SDA) enable the production of porous nanoscale materials. Most strategies rely upon polymer equilibration where diverse morphologies are realized in porous functional materials. This review details how solvent selectivity determines the polymer SDA behaviors, spanning from bulk-type to solution-type. Equilibrating behavior of either type, however, obscures nanostructure cause-and-effect since the resulting sample series convolve multiple spatial variations. Solution-type SDA behaviors include both dynamic and persistent micelles. Persistent micelle templates (PMT) use high solvent selectivity for kinetic entrapment. PMTs enable independent wall thickness control with demonstrated 2 Å precision alterations. Unimodal PMT pore size distributions have spanned from 11.8 to 109 nm and multimodal pore sizes up to 290 nm. The PMT method is simple to validate with diffraction models and is feasible in any laboratory. Finally, recent energy device publications enabled by PMT are reviewed where tailored nanomaterials provide a unique perspective to unambiguously identify nanostructure–property–performance relationships
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