1,721,002 research outputs found

    XPS/ESCA on glass surfaces: A useful tool for ancient and modern materials

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    In the field of glass science and technology, as well as for historical glasses, a remarkable importance is devoted to the understanding of the interaction between the glass surfaces and the surrounding environment. Glass fabrication and preservation are very important issues in several research fields, involving both industrial and scientific problems. In general, a multi-technique approach should be used in order to achieve a better understanding of the complex phenomena involving reactions among glass surface atoms and environmental ones. In this frame, one of the most promising investigation technique is the X-ray photoelectron spectroscopy, XPS (also known as electron spectroscopy for chemical analysis, ESCA) mainly because of its ability to give information about the chemical bonds of the investigated atoms. In this paper the first part is devoted to the description of the basics of the technique, while in the second part several applications to the analysis of oxide glass surfaces are reported and discussed. The aim of this paper is to provide valuable help to all those who want to start or deepen the study of glass surfaces by this technique

    Insights on surface analysis techniques to study glass primary packaging

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    During the forming process of a vial by tubing glass, temperatures of up to 1200◦C are applied to adjust the glass viscosity. This process causes the release of volatile components such as alkali borates. Consequently, the percentage of sodium and boron measured on the inner surface of the vial can be higher than that measured on the corresponding glass tube. This study aimed to characterize the inner surface of two different borosilicate glass tubes of type I before and after the vial forming process at the nanoscale level. Quantitative elemental analysis of the surface along the vertical axis of glass tubes and vials was performed by X-ray photoelectron spectroscopy, whereas the topographical investigation was carried out by scanning electron microscopy (SEM). In the near-bottom region of a vial, which is usually the area most prone to corrosion, the SEM micrographs showed the appearance of bulges on the surface. The latter were then analyzed by time-of-flight secondary ion mass spectrometry to characterize their molecular composition. The purpose of this work is to identify possible new strategies for faster identification of factors that eventually influence chemical resistance of pharmaceutical glasses and to provide useful information needed to improve industrial processes

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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

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    “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

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    We 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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