1,720,997 research outputs found
How effective are reducing plasma afterglows at atmospheric pressure in removing sulphide layers: Application on tarnished silver, sterling silver and copper
No full textAbstract: A plasma afterglow from a gas mixture of 5 vol% H2 in He is able to remove tarnish layers on pure silver in a matter of seconds. This dry, localized, and noncontact cleaning technique is a promising method to clean historical objects where silver is combined with organic materials and where traditional cleaning techniques are not recommended. However, historical objects are often manufactured with silver alloys but somehow their tarnish layers are removed less effectively with plasma treatments. To understand the different impact of the afterglow, the surfaces of corroded silver, sterling silver, and copper coupons are characterized before and after plasma treatment by a multianalytical approach combing optical and confocal microscopy, scanning electron microscopy coupled to energy dispersive X-ray analysis and chronopotentiometry. The analyses demonstrate that the few hundred nanometre-thick tarnish layer on pure silver is transformed through the whole thickness resulting in a porous metallic film. On top of that metallic film, some isolated remnant Ag2S particles are found. For sterling silver, a yellowing of the surface occurs. The Ag-rich corrosion products are reduced to a large extent, while the Cu-rich corrosion products are only partially reduced. For corroded copper, no apparent visual change is observed at a macroscopic scale, although the morphology of the surface changed. The results allow an evaluation of the cleaning efficiency and provide a deeper understanding of hydrogen plasma effects on the transformation of sulphide corrosion layers at atmospheric pressure
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
Tarnished silver-copper surfaces reduction using remote helium plasma at atmospheric pressure studied by means of high-resolution synchrotron x-ray photoelectron microscopy
No full textAbstract: Previous investigations suggested that sulphide layers on pure silver surfaces were easily removed with a reducing plasma afterglow at atmospheric pressure, but were harder to remove on silver-copper alloys. In this study we investigated by synchrotron x-ray photoelectron spectroscopy the effect of plasma afterglow on tarnished pure silver, pure copper and sterling silver alloy. The results confirmed that plasma was able to reduce in depth all sulphides except Cu2S. The process was explained by standard reduction potentials and allowed to draw a detailed picture of the submicrometric evolution of the tarnished layers
A dataset of high-resolution synchrotron x-ray photoelectron spectra of tarnished silver-copper surfaces before and after reduction with a remote helium plasma at atmospheric pressure
Full text linkAbstract: The data presented in this article are related to the measure- ments in the contribution titled: \u2018Tarnished silver-copper sur- faces reduction using remote helium plasma at atmospheric pressure studied by means of high-resolution synchrotron x-ray photoelectron microscopy\u2019 published in Corrosion Sci- ence. X-ray photoelectron spectra were collected from pure silver, sterling silver (92.5 w% Ag and 7.5 w% Cu) alloy and pure copper. These metals were artificially sulphidised. A remote helium plasma at atmospheric pressure was applied on the metallic and sulphidised state. Then the top layer of the 4 surface states were analysed at the NanoESCA beamline (Electron Spectroscopy for Chemical Analysis at the Nanoscale) at Elettra Sincrotrone Trieste. The instrument installed as an end station at the NanoESCA beamline of the Elettra storage ring combines an electrostatic Photo Electron Emission Microscope (PEEM) with a double-hemispherical (\u2018IDEA\u2019) analyser, allowing the collection of photoemission electron microscopy (PEEM) images, X-ray photo electron- energy-filtered images and XPS spectra. The NanoESCA beamline provides electromagnetic radiation with variable polarization (linear, circular) and energies up to 10 0 0 eV. Information for Cu3p, Cl2p, S2p, C1s and Ag3d were obtained by collecting spectra at 450 eV. The goal of the analyses was to determine how the plasma treatment changed the top layer of the metallic and sulphidised surface of pure silver, sterling silver and pure copper. This contribution focuses on the calibration of the collected XPS spectra, as well as the impact of the plasma treatment on the surface states
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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