1,721,144 research outputs found
Electrochemical characterization of an ambient temperature rechargeable Li battery based on low molecular weight polymer electrolyte
No full textPreliminary applications of low molecular weight polymer electrolyte (PEG) and lithium salt in lithium rechargeable batteries have been reported. The electrochemical characteristics of these electrolytes have been tested by cyclic voltammetry, charge-discharge cycles and ac impedance methods. Surface layers appear to be present on botg electrodes, but they develop upon time with different extension
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
Rechargeable lithium batteries based on Li1+xV3O8 thin films
No full textLow-temperature thin films of Li1+xV3O8 have been fabricated and tested in LiClO4/propylene carbonate-1,2-dimethoxyethane/Li cells. These cells show very good intercalation kinetics, and at 0.4 C discharge rate produce a specific energy of approximate to 110 Wh/kg. The films could be used in microbatteries for electronic devices, and applications requiring more power could also be envisaged
Copper polymer electrolytes
No full textMultivalent salt polymer complexes offer important prospects of the investigation and understanding of the fundamental properties of polymer electrolytes. In this work we present some recent results obtained by complex impedance, cyclic voltammetry and electron spin resonance on a series of polymer electrolyte systems based on the combination of poly(ethyleneoxide) PEO and copper salts of the Cu(CF3SO3)2 type. The data appear to confirm that copper ions contribute to the overall transport in these complexes. However, the mechanism of conductivity may also include a mixed ionic-electronic effect
Effect of the different structural distortions of MoO3 and the homologous Mo18O52 upon the thermodynamics of Li+ insertion.
No full textThe vanadium bronze Li1+x V3O8 compares well with other cathodic materials for high-energy, rechargeable lithium batteries, such as TiS2 and V6O13. On the basis of this evidence, further investigations were undertaken aimed at: a) the development of 1-5 Ah Li1+x V3O8 batteries; b) the elucidation of interfacial and bulk characteristics of the vanadium bronze electrodes. The latter task has been accomplished with the help of SEM, polarization, Li+ diffusion and impedance data. The results are consistent with an increase in charge transfer and diffusion resistance at high degrees of intercalation. The formation of a passivation layer on the cathode surface via electrolyte decomposition and a decrease of chemical Li+ diffusion upon intercalation, were also evidenced
Characteristics of electrochemically synthesized polymer electrodes in lithium cells—III. Polypyrrole
No full textThe characteristics of electrochemically synthesized polypyrrole electrodes have been examined in the lithium perchlorate-propylene carbonate electrolyte, by cyclic voltammetry, charge-discharge cycling, frequency response analysis and by vis-near ir absorbtion spectra. The results show that these polymer electrodes behave satisfactorily in terms of kinetics of the electrochemical doping process, cyclability and charge-discharge efficiency. However, their performance under high rates may be limited by the diffusion of the perchlorate counterion. The preliminary evaluation seems to indicate that polypyrrole may be more stable than other conducting polymers in organic electrolytes of interest for the development of rechargeable lithium batteries
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