1,720,961 research outputs found
The effects of cold plasma treatments on LDPE wettability and curing kinetic of a polyurethane adhesive
No full textA cold plasma feed with either oxygen or nitrogen was used to modify thin Low Density Polyethylene films. The treatment improved both the surface wettability and the curing kinetic of a polyurethane based adhesive spread on the surface. The chemical functionalities responsible of the observed behaviours were investigated and monitored over time by high resolution x-ray photoelectron spectroscopy. Atomic force microscopy were used to compare the effects of the two feeding gases on the surface morphology of films exposed (to the plasma) for equal times. The effect on the treated films of the atmosphere exposure and of the aging time were also considered
Growth morphology and electronic properties of Sn deposited on different InSb surfaces
No full textWe present a study of the growth morphology and electronic properties of Sn deposition on ZnSb(111) A-type and ZnSb(110) surfaces, by means of photoemission spectroscopy. Tin grows in a layer-by-layer fashion on the (111) substrate, with a (1x1) symmetry characteristic of pseudomorphic bulk-like Sn(111). A first-ordered monolayer followed by Sn island formation is observed on the (110) surface, and we estimate a fractional area of Sn islands increasing from 60% at two monolayers nominal coverage to about 80% at higher coverages. Both interfaces show the formation of non-metallic Sn adlayer at room temperature, while annealing of a multilayer Sn/InSb(110) produces a light metallic-like response, probably due to Sn clustering. (C) 1999 Elsevier Science B.V. All rights reserved
Long range ordered pentacene chains assembled on Cu(119) vicinal surface
No full textPentacene (C22H14), deposited on the Cu(119) vicinal surface, forms ordered molecular chains, with the long molecular axis aligned along the step direction. Phase correlation between neighboring chains gives rise to large domains, observed in the low-energy electron-diffraction (LEED) pattern. Scanning tunneling microscopy (STM) images show that the molecules are laying flat on the copper terraces with the molecular axis aligned along the steps, hence, facing the short side of one another. High-resolution STM data suggest that the molecules adsorb, locating the central benzene ring on the hollow site of the Cu(001) surface
Strong chemical reactivity at the early stages of Yb overgrowth on GaP(110): A synchrotron-radiation study
No full textThe GaP(110)/Yb interface was studied with use of synchrotron radiation to excite the Ga 3d and the P 2p semiconductor core levels, the quasiatomic Yb 4f states together with the valence-band region, and the P L2,3VV Auger line shape in Yb coverages ranging from 0.2 to 5 monolayers. Strong reactivity was found at the interface region with semiconductor surface disruption and the formation of intermixed Yb-Ga-P products distributed on the substrate surface from the lowest coverage range investigated up to about 1 monolayer. Ga surface segregation with Yb-Ga alloying and Yb phosphide-like product trapping at the interface are dominant in the highest coverage range, resulting in a strong gradient concentration of the substrate chemical species, along a direction normal to the semiconductor surface. The reacted contributions in the Ga 3d, the P 2p, and the Yb 4f levels suggest a highly heterogeneous character of the growing interface with the presence of a multiplicity of atomic sites for each of the reacted atoms. Primarily divalent character of Yb atoms was found over all the coverage range investigated, as derived by Yb 4f spectroscopy. From the changes shown by the P L2,3VV line shape it was possible to model the evolution of the local density of states in Yb-P bonds in terms of Yb 5d- and P 3p-derived states mixing. The results are compared with the growth mechanisms of other III-V-semiconductorrare-earth-metal interfaces
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
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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