1,722,468 research outputs found
Where zeolites and oxides merge: semi-condensed tetrahedral frameworks
No full textThe synthesis of new inorganic materials constructed with extended lattices has taken place mainly in two areas, complex oxides and porous framework structures. In the former case the drive has been towards controlling electronic and magnetic properties while in the latter domain porosity and the ability to enclathrate small organic or inorganic units has been paramount. Semi-condensed framework materials, whose compositions and structures place them at the borderline of these two classes, are described in this article, such compound types include the sodalite, cancrinite, analcime, zeloites ABW and JBW and scapolite structures. In each case recent chemistry and developments are described particularly with respect to advances made at The University of Southampton. The potential for merging the properties and structures of these two classes of compounds are also discussed
Die Herausforderung: Altern, Gesundheit, Versorgung
No full textKuhlmey A, Schaeffer D. Die Herausforderung: Altern, Gesundheit, Versorgung. In: Klein B, Weller M, eds. Masterplan Gesundheitswesen 2020. Baden-Baden: Nomos; 2012: 107-123
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
Synthesis and characterisation of perovskite-type oxynitrides
No full textRare earth and alkaline earth tantalum oxynitride perovskite-type systems of the stoichiometry A((1-x))Ln(x)TaO((2-x))N((1+x)), where A is an-alkaline earth metal (Ca, Sr and Ba) and Ln, a lanthanide, have been synthesised and characterised using powder X-ray and neutron diffraction. The samples formed were orthorhombically distorted perovskites and crystallised in the space group Pnma. Further analysis of the diffraction data has highlighted the influences that the nature of the cations incorporated and the distribution of the anions have on crystal structure and lattice size. Thermogravimetric analyses have been performed in air and show the onset of decomposition at ca. 400degreesC for all materials. UV-Vis spectroscopic measurements show that these compounds exhibit absorption bands in the visible region, due to inter-band transitions, with positions that can be correlated with structure and composition
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
Synthesis and structure of a new family of nickelates: Tl(Ln(2)Sr(2))Ni2O9, Ln = La, Pr, Nd, Sm, Eu, and Cd
No full textA novel series of nickelates described by the formula Tl(Ln(2)Sr(2))Ni2O9, Ln = La, Pr, Nd, Sm, Eu, and Gd, have been synthesized and their structures determined using both powder X-ray diffraction and powder neutron diffraction. The materials are isostructural with the superconducting cuprate, Tl(La2.4Ba1.6) Cu2O9, crystallizing in a tetragonal unit cell, space group I4/mmm, lattice parameters a = 3.8069-3.7667(1) Angstrom and c = 30.055-29.390(1) Angstrom. The compounds adopt the 1201-0201 intergrowth structure, consisting of layers of apex-sharing stoichiometric NiO6 octahedra connected by a Tl0 layer. A decrease in the cell dimensions is observed across the series, consistent with the lanthanide contraction and partial ordering of the strontium and lanthanide ions on the A cationic sites is observed. Magnetic susceptibility data reveal no evidence of long-range magnetic ordering for two of the compounds, TI(La2Sr2)Ni2O9 and Tl(Gd2Sr2)Ni2O9
Propane-1,2-diammonium tetrafluoroberyllate
No full textCocrystallization of the inorganic [BeF4](2-) unit with the organic moiety [NH3CH2CH(NH3)CH3](2+) results in the three-dimensional network of the title compound, (C3H12N2)[BeF4] or C3H12N22+.BeF42-, created by hydrogen bonds between the protonated ammonium groups and the highly electronegative F atoms of the anion. The structure is described in terms of layers related to each other by crystallographic centres of symmetry
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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