1,720,970 research outputs found
Adsorption studies of simple molecules on metallic, bimetallic and semi-conductor interfaces
No full textThe UHV spectroscopic techniques of AES, TDS, HREELS and LEED were used to examine a variety of adsorbate systems.Trimethyl aluminium (TMA) adsorption and decomposition on Si was investigated over the temperature range 77-1500K. At 77K, simple multilayer physisorption was observed, with TMA desorbing at 200K. Adsorption at 300K occurred at a slower rate as there was an activation barrier to chemisorption. This barrier was thought to be that for the formation of HjAl(CH3)i_s intermediates (1< x< 3), which were shown to be on the surface by desorption of CH4 and C2H2. As the surface temperature rose above 600K, diffusion of Al into the bulk (dominated > 800K) competed with Al deposition (dominated > 600K & < 770K). Pre-evaporation of Al onto the Si surface lowered the activation barrier and the process of film deposition was auto-catalytic.Acetic acid and ethanol adsorption were investigated on Rh (111). Ethanol formed ethoxide, water and CO on adsorption at 180K. The ethoxide decomposed in the range 220-270K, to give acetaldehyde, ethanol and H2. Above 500K, only CH residues remained on the surface. Acetic acid adsorbed at 200K to form multilayers. The first monolayer contained some acetate and acetic anhydride; lateral interactions between these groups gave rise to unusual off-specular EELS signals and desorption temperature variations with coverage. On heating to 400K, the excess acid desorbed, leaving large quantities of acetic anhydride. Above 550K only CH residues remained on the surface. The similarity in M-M interatomic distances of Rh and the carbonyl-carbonyl distance in the anhydride was discussed.Adsorption, trimerisation and desorption/decomposition of acetylene was investigated on Pd, Pd-Cu and Pd-Pb surfaces.Benzene production was clearly detected on Pd(331), benzene desorbing at 300K and 500K. On adsorption, acetylene blocked many of the benzene decomposition pathways, though extensive dehydrogenation did occur, with ethylidyne species being detected on the surface. Some acetylene chemisorbed reversibly when adsorbed at 200K.Dehydrogenation processes were almost eliminated by small surface concentrations of Cu, which greatly increased reversible adsorption of acetylene and benzene production, as well as changing their desorption temperatures compared to those on clean Pd. Cu adsorption reduced the available numbers of large Pd ensembles, needed for decomposition, whilst the small Pd ensembles which produce benzene & desorb acetylene are unchanged.Adsorption of acetylene was greatly limited by low concentrations of lead on the Pd surface. Above a composition of PdgPb, a surface alloy formed; the highest lead content achievable was PdPb2 owing to diffusion of Pd to the surface. On unheated alloy surfaces, there was detectable dehydrogenation but no reversible chemisorption. Heating a surface of composition Pd2Pb led to formation of Pd3Pb in which the lead was evenly distributed over the surface Pd triplet sites, such that almost all adsorption was blocked. CO desorption studies on the mixed surfaces were used to provide information on alloy structures formed. (DX 84802)</p
Going 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
Variations 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
Rowe, Simon
No full textSee entry in Marengo County, volume 1, page 70: https://digital.archives.alabama.gov/digital/collection/voter1867/id/410
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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