1,720,969 research outputs found
Spectroscopic analysis of the structure of amorphous nitrogenated carbon films after wear tests
No full textThe effects of wear tests on the electronic structure of amorphous nitrogenated carbon (a-C:H:N) films prepared in a radiofrequency plasma-enhanced chemical vapor deposition system from a mixture of methane and nitrogen have been investigated. The tribological properties were investigated with a tribometer in a ball-on-disk configuration. For different N-2 fractions, film structure and chemical composition were examined using conventional Raman and X-ray photoelectron spectroscopy, and also by means of high-lateral-resolution soft X-ray photoemission microscopy using synchrotron radiation. Nitrogen incorporation into the as-deposited amorphous carbon network results in an increase in the number of N-sp(2)-C bonded sites with respect to the films grown in a nitrogen-free atmosphere. The wear stability of the films was analyzed as a function of the nitrogen fraction, and a thorough description of the electronic structure was obtained in the as-deposited state and after wear testing. High-lateral-resolution photoemission microscopy reveals for the first time that inhomogeneities within the film after wear testing are correlated to nitrogen incorporation. The study of energy distribution curves and high-lateral-resolution images on the nitrogenated samples shows that a modification of the surface chemistry occurs by mechanical action. (C) 2002 Elsevier Science B.V. All rights reserved. RI Valentini, Luca/D-5238-2011; Kenny, Jose/F-9372-201
Influence of grain size and film composition on wear resistance of ultra fine AISI 304 stainless steel coated with amorphous carbon films
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Wear Resistance of a High Nitrogen Austenitic Stainless Steel Coated with Amorphous Carbon Films: Influence of Grain Size and Film Composition
No full textGoing 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
Fluorinated amorphous carbon thin films: Analysis of the role of the plasma excitation mode on the structural and mechanical properties
No full textVariations 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
Structure and mechanical properties of argon assisted carbon nitride films
No full textThis paper reports on the effects of Ar dilution on the structure, bonding and tribological properties of nitrogen-doped amorphous carbon films (a-C:H:N) deposited by r.f. glow discharge from CH4-N-2 and CH4-N-2-Al mixtures on silicon substrates. For different N-2 fractions, film structure and chemical composition were examined using Raman spectroscopy, X-ray reflectivity (XRR) and X-ray photoelectron spectroscopy (XPS). The mechanical and tribological properties were investigated by scratch testing and a tribometer in a ball-on-disk configuration. Results indicate that, as argon is introduced in the gas mixture, progressive graphitization of the films occurs and the mass density decreases. The behavior of the adhesive strength, as a function of nitrogen content, achieved with Ar addition is of the same order as those reported for CN, films. However, at a fixed nitrogen partial pressure, films obtained without Ar dilution show better adhesion and a denser sp(3) bonded carbon network. (C) 2001 Elsevier Science B.V All rights reserved. RI Valentini, Luca/D-5238-2011; Kenny, Jose/F-9372-201
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
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