1,721,001 research outputs found
Graphene edge method for three-dimensional probing of Raman microscopes focal volumes
Full text linkIn this work, a layer of graphene was used as a standard material for the measurement of the dimensions of Raman microscopes focal volumes of different confocal Raman spectrometers equipped with different objectives and excitation laser wavelengths. This method consists in probing the volume near the focal point of the system by using a flat graphene monolayer sheet with a straight edge. Graphene was selected because of its high Raman cross section and mechanically and chemically stability, allowing fast measurements and easy manipulation. In this paper, a method to employ graphene to accurately and precisely measure the three dimensions of the focal volume of a Raman microscope is presented; scanning along the axial and lateral directions, it is possible to reconstruct the three dimensions of the focal volume. Furthermore, these operations can be combined in a single procedure which allows the measurement of projections of the volume on planes parallel to the optical axis. Knowledge of these parameters enable absolute quantification of Raman-active molecules and support high-resolution Raman imaging
Graphene edge method for three-dimensional probing of Raman microscopes focal volumes
Full text linkIn this work, a layer of graphene was used as a standard material for the measurement of the dimensions of Raman microscopes focal volumes of different confocal Raman spectrometers equipped with different objectives and excitation laser wavelengths. This method consists in probing the volume near the focal point of the system by using a flat graphene monolayer sheet with a straight edge. Graphene was selected because of its high Raman cross section and mechanically and chemically stability, allowing fast measurements and easy manipulation. In this paper, a method to employ graphene to accurately and precisely measure the three dimensions of the focal volume of a Raman microscope is presented; scanning along the axial and lateral directions, it is possible to reconstruct the three dimensions of the focal volume. Furthermore, these operations can be combined in a single procedure which allows the measurement of projections of the volume on planes parallel to the optical axis. Knowledge of these parameters enable absolute quantification of Raman-active molecules and support high-resolution Raman imaging
Production by solid/liquid reaction and characterisation of high purity MgB2 for superconducting application
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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
Surface Minimal Bactericidal Concentration: A comparative study of active glasses functionalized with different-sized silver nanoparticles
No full textIn this work the quantification of antimicrobial properties of differently sized AgNPs immobilized on a surface was studied. Three different sizes of spheroidal AgNPs with a diameter of (6, 30 and 52) nm were synthetized and characterized with UV–vis, SEM, TEM and ICP-MS. The MIC (Minimal Inhibitory Concentration) and MBC (Minimal Bactericidal Concentration) against Escherichia coli were investigated. Then, the antibacterial efficacy (R) of amino-silanized glasses coated with different amounts of the three sizes of AgNPs were quantified by international standard ISO 22196 adapted protocol against E. coli, clarifying the relationship between size and antibacterial properties of immobilized AgNPs on a surface. The total amount of silver present on glasses with an R ∼ 6 for each AgNPs size was quantified with ICP-MS and this was considered the Surface MBC (SMBC), which were found to be (0.023, 0.026 and 0.034) μg/cm2 for (6, 30 and 52) nm AgNPs, respectively. Thus, this study demonstrates that active surfaces with a bactericidal effect at least ≥ 99.9999 % could be obtained using an amount of silver almost 100 times lower than the MBC found for colloidal AgNPs. The immobilization reduces the aggregation phenomena normally occuring in liquid media, maximizing the exposed specific superficial area of the AgNPs and their direct contact with bacterial cells. Starting from this glass model system, our work could broaden the way to the development of a wide range of antibacterial materials with very low amount of silver that can be safely applied in biomedical and food packaging fields
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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