1,721,028 research outputs found
Rh3B2-x, new structure type of binary borides with triclinic symmetry
No full textNew binary compound Rh3B2-x, x = 0.167 crystallizing with its own structure type has been observed from the as cast alloys. The compound has a limited thermal stability range: it was found to decompose after annealing at 800 degreesC for 20 days. The crystal structure was investigated by X-ray diffraction from two single crystals using different techniques: CAD-4 automatic diffractometer, a = 5.470(2) b = 6.816(3), c = 9.068(4), alpha = 110.74(3), beta = 94.81(3), gamma = 90.44(2), 107 refined parameters, R-1 = 0.0418, WR2 = 0.1087 for 1223 reflections with I > 2sigma(I-o), and BRUKER SMART AXS, a = 5.483(4), b = 6.818(6), c = 9.072 (7), a = 110.78(1), b = 94.73(1), g = 90.46(1) 107 refined parameters, R-1 = 0.040 1, wR(2) = 0.0959 for 943 reflections with I > 2sigma(I-o). The Rh3B2-x, structure (space group P (1) over bar, Pearson symbol aP30 - 1) is the first representative of structures with triclinic symmetry among binary borides and contains three different types of boron-boron aggregation: isolated boron atoms, B-B pairs and B-6 chain fragments
On the crystal structure of Sc2MB6 (M = Rh, Ir) compounds
No full textTernary samples SC2MB6 and ScMB4 (M = Rh, Ir) were synthesized and studied by X-ray powder and single crystal diffraction. The crystal structure of the ternary boride SC2RhB6, Y2ReB6 structure type, Pbam space group, a = 8.9144(8) angstrom, b = 11.2105(10) angstrom, c = 3.4833(3) angstrom, Z = 4, V=348.10(5) angstrom(3), rho =4.917 g cm(-3), mu = 8.216mm(-1) was refined to R=0.0193, wR2 = 0.0518 from single crystal X-ray diffraction data (Bruker SMART 100 CCD diffractometer, 573 reflections with I > 2 sigma(I-o)). The lattice parameters for the isotypic Sc2IrB6 compound are a = 8.9149(18) angstrom, b = 11.211(19) angstrom, c = 3.48367(13) angstrom (X-ray powder diffraction, Image Plate Huber G 670 camera). No evidence of formation of the ternary ScMB4 (M = Rh, Ir) compounds with YReB4 structure type was obtained
Structural investigation of the CeRh2Sb2−x compound
No full textThe crystal structure of the CeRh2Sb2-x compound was studied by powder and single crystal X-ray diffraction from as-cast and annealed at 770K alloys. The compound crystallizes with a CeGa2Al2 structure type, space group I4/mmm: CeRh2Sb2-x (x=0.34) (crystal I, as-cast alloy): a=4.4925(11)angstrom, c= 10.1778(26)angstrom, V=205.41(9)angstrom(3), rho= 9.530g cm(-3), mu=31.468 mm(-1), R-1=0.0431, wR(2)=0.1187 for 103 reflections with I > 2 sigma(I-o); CeRh2Sb2-x, (x=0.405) (crystal II, as-cast alloy): a=4.4781(9)angstrom, c=10.1652(20)angstrom, V=203.85(7)angstrom(3), rho=9.603 g cm(-3) mu=31.710 mm(-1), R-1=0.0397, wR(2)=0.0857 for 116 reflections with I > 2 sigma(I-o); CeRh2Sb2-x (x=0.24) (crystal 111, annealed at 770K sample): a=4.5106(7)1 angstrom c=10.2442(16) angstrom, V=208.42(6) angstrom(3), rho=9.392 g cm(-3), mu=31.014 mm(-1), R-1 =0.0494, wR(2)=0.1069 for 122 reflections with I > 2 sigma(I-o); Bruker SMART CCD, data corrected for absorption using SADABS, structure refinement-WinGX 1.70
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
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