1,720,956 research outputs found
PVP-Assisted ZrO2 coating on LiMn2O4 spinel cathode nanoparticles prepared by MnO2 nanowire templates
No full textLiMn2O4 spinel nanorods prepared from nanowire MnO2 templates were capped with polyvinyl pyrrolidone (PVP) and coated with ZrC2O4 precursors in aqueous solution. Upon annealing at 600 ??C in air, an amorphous ZrO2 nanoscale coating layer was obtained on the spinel nanoparticles with a particle size of <100 nm that formed from the splitting of the original spinel nanorods. The electrochemical cycling results clearly showed that nanoscale ZrO2 coating significantly improved the rate capability and cycle life at 65 ??C in spite of very high surface area of the spinel nanoparticles.close687
Electrochemical and structural characterizations of InSb nanoparticles prepared using a sodium naphthalenide reduction method
No full textInSb nanoparticles with a mean particle size of 10 nm prepared by the reduction of metal salts using sodium naphthalenide at 350°C was discussed in terms of its electrochemical, ex situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations. Ex situ XRD and TEM results revealed the progressive formation of extruded In from InSb, followed by the formation of Li 3 In 2 and In 3 Li 13 with a lithium alloy process. In addition, it was observed that Li 2 Sb and Li 3 Sb were formed as a result of the decomposition of InSb. During lithium dealloying, Li 3Sb and In 3 Li 13 were returned to Sb and In, respectively. Nanosized InSb particles showed a charge capacity of 590 mAhg from the first-charge capacity of 670 mAhg after 30 cycles, leading to a cycle retention ratio of 86%. This value was far superior to its bulk counterpart, which showed only a 48% capacity retention ratio after the same cycles. The improved capacity retention of the nanosized InSb was due to significantly decreased particle pulverization, compared to the bulk counterpart.close2
PVP-functionalized nanometre scale metal oxide coatings for cathode materials: successful application to LiMn(2)O(4) spinel nanoparticles
No full textPVP functionalized metal oxide coatings on spinel nanoparticles demonstrated significantly improved rate characteristics under extensive cycling at 65??C and exhibited over 100% improved capacity retention compared to the bare counterpart.close212
Synthesis of nanowire and hollow LiFePO4 cathodes for high-performance lithium batteries
No full textThe synthesis of nanowire and hollow LiFePO4 cathodes using the hard templates KIT-6 and SBA-15 is reported for high-performance lithium batteries. The two-dimensional hexagonal SBA-15 silica template with P6mm symmetry is used for the template that contains parallel cylindrical pores arranged with hexagonal symmetry, which serves to organize the wires into parallel bundles. On the other hand, three-dimensional cubic arrangement of pores in KIT-6 silica with Ia3d symmetry yields hollow morphology with mesopores. After impregnation of the template into a solution or after coating on the template with a solution consisting of LiFePO4 precursors, the silica template is removed and is subsequently fired at 700??C. Electrochemical cycling of both the nanowire and hollow LiFePO4 cathodes demonstrates excellent rate capability even above 10C rate, showing >89% capacity retention of the initial capacity. Among them, the rate capability of the hollow cathode at 15C is higher than that of the nanowire cathode, showing 6% improvement due to its higher Brunauer-Emmett-Teller surface area.close11111
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
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