1,720,994 research outputs found
H2S gas interaction with Pt(II)-containing polymetallaynes of selected chain length: An XPS and EXAFS study
No full textThe interaction between gaseous H2S and the surface of several metal-containing oligomers, investigated by emission and absorption spectroscopies, is presented and discussed. The polymetallayne trans-{Cl-[Pt(PBu3)(2)(C C-C6H4-C6H4-C C)](9)Pt(PBu3)(2)Cl} and related model molecules, i.e. the binuclear transition metal dialkynyl bridged Pt(II) square planar complex trans,trans-[ClPt(PBu3)(2)(C C-C6H4-C6H4 Pt(PBu3)(2)CI], the tetranuclear linear oligomer trans-[Cl-[Pt(PBu3)(2)(C C-C6H4-C6H4-C C)](3)Pt(PBu3)(2)Cl}, the tetranuclear cyclic oligomer cis- [Pt(PBu3)(2)(C C - C6H4-C6H4 -C C)](4), were exposed to hydrogen sulfide and then investigated by X-ray photoelectron (XPS) and X-ray absorption (XAS) spectroscopies, in order to shed light on the gas/polymer interaction associated to the sensing properties of these materials. XPS measurements evidenced the presence of S in the polymetallayne samples exposed to H2S, and the measured S2p binding energy values correlate with H2S adsorbed by means of sulfur atoms chemically bonded to metal atoms, owing to the formation of sulfur-containing adducts. XAS data analysis suggested a squarepyramidal geometry around the transition metal with H2S in the apical position for the pentacoordinated platinum units
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
Nanostructured polymetallaynes of controlled length: synthesis and characterization of oligomers and polymers from 1,1’-bis-(ethynyl)4,4’-biphenyl bridging Pt(II) or Pd(II) centres
No full text
Dinuclear Pt and Pd complexes with metalloporphyrin bridges: a NEXAFS study of the electronic structure and self assembling properties
No full textMolecular and electronic structure of organometallic assemblies containing Zn-diethynylporphyrin (ZnDEP) bridged between Pt(II) and Pd(II) tethers, i.e. –Pt(PBu3)2Cl or –Pd(PBu3)2(–C6-point triple bond; length half of m-dashC–Ph), were investigated by means of Near Edge X-ray Absorption Fine Structure spectroscopy (NEXAFS). N K-edge spectra collected on the two macromolecular arrays were compared with data on ZnDEP and diethynylporphyrin (DEP); an energy shift towards higher photon energy values was observed and attributed to charge transfer from the tetrapyrrolic macrocycle to the transition metal terminal groups. Angular dependent NEXAFS characterisation of both Pd–ZnDEP and Pt–ZnDEP films deposited on gold allowed to assess that the macromolecules grow in ordered layers
NEXAFS study of a Pt-containing rod-like organometallic polymer (Pt-DEBP). Molecular orientation onto HOPG, Au/Si(111), Cr/Si(111) AND Si(111) surfaces
No full textThe influence of different substrates on the molecular orientation of organometallic polymer Pt-DEBP, [Pt(PBu 3) 2CCC 12H 8CC] n, has been investigated by NEXAFS spectroscopy. Thin films were deposited on HOPG, Au/Si(1 1 1), Cr/Si(1 1 1), Si(1 1 1) and stainless steel. The assignment of the spectral features has been carried out on the basis of previous STEX calculations performed on phenylacetylene model molecule in gas phase and adsorbed on Pt(1 1 1) and Cu(1 0 0). Angular dependent analysis of the π* resonance occurring at 285.50 eV photon energy deriving by the benzene carbon orbitals showed a polarisation effect for all substrates. A preferential molecular orientation at nearly 40°to the surface normal was observed. This result might be explained by the strong interaction between sp and sp 2 carbons of the organic diethynylbiphenyl DEBP moiety contained in close chains, leading to polymer self-assembling
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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