1,720,970 research outputs found
Flexible electrodes for supercapacitors assembled with NiOx(OH)y nanoflakes on H-plasma nanosculptured carbon fiber patches
No full textA surface nanosculpturing is performed on twill wave carbon fibers patches by means of hydrogen plasma treatments in a dual-mode MW-RF CVD reactor. A tufts-like texture is realized on the surface of the single fibers of the patches that show an enhanced electrochemical reactivity and capacitive behavior with respect to the pristine material. The nanostructured carbon fiber fabrics are successfully used as support for the electrochemical growth of nickel species nanoflakes. The hybrid NiOx(OH)y-carbon fibers electrodes exhibit remarkable increases of both capacitive and pseudo-capacitive currents up to specific capacitance values of 1050 F g(-1). Charge storage capability given by the coupling of Ni-species and etched carbon fibers is preserved after long time cycling and is also maintained after mechanical deformation, making such composite systems promising as suitable electrode materials for flexible energy storage devices. (C) 2017 Elsevier Ltd. All rights reserved
Graphene platelets from shungite rock modulate electropolymerization and charge storage mechanisms of soft-template synthetized polypyrrole-based nanocomposites
No full textWe report here on soft-template electropolymerizations of polypyrrole (Ppy)-based nanocomposites triggered by graphene platelets (GP) from shungite (SH) rocks. A properly designed procedure for an efficient extraction of graphene platelets from SH powders is established to produce remarkable graphene materials in a low oxidation state and with a high electrical conductivity (1490 S cm−1). By using positively and negatively charged templating surfactants the role played by the graphene units on the electropolymerization reactions is pointed out by SEM, EDX, TEM, SAED, XPS and Raman spectroscopy. The morphological/structural characterizations highlight that GP from SH have a surface chemistry suitable for selective and mutual interactions with the growing Ppy chains. CV and galvanostatic charge/discharge measurements evidence that GP improve the transport of both electrons and ions within the bulk material by means of a synergistic action with the polymer phase. This cooperative behavior induces an enhancement of the specific capacitance up to 250 F g−1 at 2 A g−1. The Ppy-GP materials produced following the settled protocols result to be appropriate for fabricating multifunctional charge transport and storage electroactive systems
Chemical routes for synthesis of polypyrrole–based nanocomposites incorporating graphene platelets from natural Shungite
No full textPolypyrrole (PPy)-based nanocomposites are synthesized by a micro-emulsion oxidative chemical polymerization of pyrrole monomer. Graphene platelets (GP), extracted from Shungite mineral powders through innovative procedures, are used as nanoinclusions to enhance the interesting properties of the pure polymer. SEM and HR-TEM analyses evidence that diverse PPy nanostructures are obtained in the presence of different dopant surfactants: globular grains with sodium dodecyl sulfate (SDS) anionic surfactant, and tubular features with hexadecyltrimethylammonium bromide (CTAB) cationic surfactant. Raman spectroscopy reveals that the polymer chains are in a semi-oxidized state. Functional characterizations evidence that the PPy-based nanocomposites doped with SDS are characterized by improved charge transport properties. (C) 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of AEM2017
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 new fabrication route for PVA/graphene platelets composites with enhanced functionalities
No full textThis work deals with the synthesis and characterization of composites made of poly(vinyl alcohol) (PVA) and oxidized graphene platelets obtained from an ad hoc treatment of graphite. The composite is produced by a modified solution mixing procedure in which the in situ crosslinking of PVA with maleic anhydride has been carried out in the presence of the carbon filler. A complete characterization of the material is presented carried out by SEM, DTGA, Raman spectroscopy and I-V characteristics analysis
Electronic Thermal Management by Nanodiamonds
No full textIn this paper are presented nanodiamond based materials for Thermal Management and the setup allowing to measure the thermal conductivity of these materials
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
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