1,720,995 research outputs found
A LCAO-LDF study of Bronsted acids chemisorption on ZnO(0001)
No full textThe local density functional theory coupled to the molecular cluster approach has been used to study the chemisorption of Bronsted acids (H2O, H2S, HCN, CH3OH and CH3SH) on the ZnO(0001) polar surface. Geometrical parameters and vibrational frequencies for selected species molecularly and dissociatively chemisorbed have been computed. The agreement with literature experimental data, when available, has been found to be good. The nature of the interaction between the conjugate base of the examined Bronsted acids and the Lewis acid site available on the surface has been elucidated, confirming its leading role in determining the actual relative acidity scale obtained by titration displacement reactions. The strength of this interaction follows the order OH(-)approximate to CN- > CH3O- > SH- > CH3S-
Experimental and theoretical investigation of the molecular and electronic structure of [Zn-4(mu(4)-S){mu-S2As(CH3)(2)}(6)] and [Cd-4(mu(4)-S){mu-S2As(CH3)(2)}(6)]: two possible molecular models of extended metal chalcogenide semiconductors
No full textThe molecular and electronic structure of hexakis[mu-(dimethylarsinodithioate-S:S')]-mu(4)-thioxotetrazinc has been investigated by combining X-ray diffraction measurements, electrospray mass spectrometry (ESI), UV absorption spectroscopy, and density functional calculations. The polynuclear zinc complex consists of discrete "tetrazinc sulfide" moieties held together by van der Waals interactions. The unit cell contains four independent molecules and four solvent molecules. Each independent unit is characterized by a central mu(4)-S coordinated to four Zn ions, each of them at the center of an irregular tetrahedron of S atoms. ESI measurements point out that the synthesis of the analogous Cd derivative was successful. Crystal data are as follows: chemical formula, C12H36As6Cl1.5S13Zn4; monoclinic space group P2(1)/n (no. 14); a = 30.4228(7) Angstrom, b = 18.3720(5) Angstrom, c = 32.3758(8) Angstrom, beta = 95.857(1)degrees; Z = 16. Theoretical calculations indicate that, despite their structural arrangement, neither the Zn nor the Cd complex can be considered molecular models of the extended ZnS and CdS. Nevertheless, the electronic transitions localized in the Zn-4(mu(4)-S) and Cd-4(mu(4)-S) inner cores of the title compounds have the same nature as those giving rise to the maxima in the excitation spectra of the extended Zn4S(BO2)(6) and Cd4S(AlO2)(6)
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
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
RF-sputtering preparation of gold-nanoparticle-modified ITO electrodes for electrocatalytic applications
No full textThe preparation of gold-nanoparticle (AuNPs)-modified indium tin oxide (ITO) electrodes (AuNPs/ITO) was performed by radio-frequency (RF) sputtering from Ar plasmas at
temperatures as low as 60°C, tailoring the AuNP morphology and content as a function of the sole sputtering time. The latter parameter was varied from 5 to 20 min in order to investigate the influence of gold amount and distribution on the electrochemical performances of the resulting
AuNPs/ITO systems. The electrodes were characterized using field emission-scanning electron
microscopy (FE-SEM), UV–vis absorption and x-ray photoelectron spectroscopies (XPS);
moreover variable scan rate cyclic voltammetry (CV) studies were performed to examine their
electrochemical behavior. The electrocatalytic activity of the nanostructured AuNPs/ITO
electrodes toward methanol oxidation was investigated and compared with a continuous gold
film (Aufilm/ITO). The catalytic efficiency of the AuNPs/ITO systems was found to increase with
the gold content and the AuNPs–support boundary region in the corresponding samples. For the
longest sputtering time (i.e. 20 min) the performances of the nanostructured electrode were
better than the Aufilm/ITO reference, despite the much lower catalyst amount. Furthermore,
conversely from the AuNPs/ITO samples, in the Aufilm/ITO case the gold film displayed a poor
adhesion to the substrate and the electrode could be used only for a limited number of electrochemical cycles
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