1,720,982 research outputs found
Anodic silicon dissolution in acidic fluoride electrolyte. A probe beam deflection investigation
No full textSi anodic dissolution in acidic fluoride medium has been investigated in different regimes (porous silicon formation, electropolishing under stationary and oscillating current) by probe beam deflection (PBD) or the “mirage” technique. Evolution of deflection signal allows monitoring of dissolution processes both under polarization and at open circuit, providing for example an estimate of the oxide etch-back times during open circuit corrosion. The time evolution of deflection signal during current oscillations reveals components resulting from electrochemical film formation and chemical dissolution. The PBD technique shows larger etching rates for the less passivating film (low potential) and smaller etching rates for the better passivating film (high potential). Our observations are compared with those obtained from spectroscopic investigations of the oxide layer and their relevance for models of oxide formation, and dissolution is here discussed
Probe Beam Deflection Study of p-Si Electrodissolution in Acidic Fluoride Medium in the Oscillating Regimes
No full textThe ‘mirage’ or probe beam deflection (PBD) technique has been used to investigate Si dissolution in acidic fluoride in the
regime of electropolishing, in which the electrode surface is covered by a thin oxide film. During current oscillations at a constant applied potential, the variations of the dissolution rate basically reflect variations in the rate of oxide film formation. During potential oscillations at a constant imposed current, the dissolution rate varies with the same periodicity as the potential, with a maximum when the potential is low and a minimum when it is high. Results indicate a correlation between physico-chemical and electronic properties of the oxide film, which appears more prone to etching in its less passivating form and viceversa
Characterization of anodic silicon oxide thin films with non-invasive techniques
No full textIn this work the mechanical effects and the mirage associated with the formation and dissolution of Si oxide films during p-Si electrochemical oscillations are shown and analyzed. The experiments reported here describe the application of the bending beam method (BBM) and probe beam deflection (PBD) technique for the in situ characterization of such Si oxide films. The most relevant feature of the BBM experiments was the detection of a sudden increase of the electrode curvature corresponding to the onset of SiOx formation. PBD results showed that the deflection angle can be correlated with the variation of SiOx dissolution rate in the regime of galvanostatic oscillations
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
Direct electrodeposition of metal nanowires on electrode surface
No full textA method for decorating the surface of disk electrodes with metal nanowires is presented. Cu and Ni
nanowires with diameters from 1.0 m to 0.2 m are directly deposited on the electrode surface using
a polycarbonate membrane filter template maintained in contact with the metal substrate by the soft
homogeneous pressure of a sponge soaked with electrolyte. The morphologic and structural properties of
the deposit are characterized by scanning electron microscopy (SEM) and electron backscatter diffraction
(EBSD). The latter shows that the head of nanowires with diameter of 0.4 m is ordinarily polycrystalline,
and that of nanowires with diameter of 0.2 m is almost always monocrystalline for Cu and frequently
also for Ni. Cyclic voltammetries and impedance investigations recorded in alkaline solutions at representative
Ni electrodes decorated with nanowires provide consistent values of roughness factor, in the
range 20–25
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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