1,720,997 research outputs found
New Crystal Data for High Temperature Hexagonal Silver Sulfate
No full textPowder data for Ag2SO4 were obtained with a conventional diffractometer equipped with a vacuum heating chamber. The transition from the low-temperature orthorhombic phase occurs over a temperature range of about 415° to 425°C and forms a hexagonal phase plus metallic silver. The lack of a sharp transition must be taken into account in high-temperature X-ray diffraction or DSC/DTA studies. The lattice parameters of the high-temperature hexagonal phase are a = 5.531(3), c = 7.456(5)Å at 440°C, λ = 1.540562 Å. Crystal structure determination was not completed because of uncertainty in the chemical composition. © 1990, Cambridge University Press. All rights reserved
Rietveld powder structure refinement of Na2Al2Ti6O16; Comparison of synchrotron radiation and conventional x-ray tube datasets
No full textThe crystal structure of Na2Al2Ti6O16 was refined by the Rietveld method using synchrotron radiation and conventional x-ray powder data, and the agreement factors were Rp = 3.35%, Rwp = 4.30 %, and RBragg = 6.39% for synchrotron data. The formula based on the chemical analysis and 16 O atoms is Na1.97Al1.82Ti6.15O16. The crystal data are monoclinic, C2/m, a = 12.1239(3) Å, b = 3.7749(1) Å, c = 6.4180(2) Å, β = 107.59(1)°, V = 280.00(4) Å3, Z = 1, and Dx = 3.82 g cm–3. The site occupancy refinement showed a partial ordering of Al3+ and Ti4+ ions in the two-crystallographically independent octahedral sites. © 1990, Materials Research Society. All rights reserved
Effect of energetic neutralized noble-gas ions on the structure of ion-beam sputtered thin metal-films
No full textMICROSTRUCTURE OF SPUTTERED METAL-FILMS GROWN IN HIGH-PRESSURE AND LOW-PRESSURE DISCHARGES
No full textCrystal structure and cation distribution of MnCrInS4 from synchrotron powder diffraction data
No full textThe structure and site-occupancy of the spinel-type MnCrInS4 was determined from powder diffraction data using synchrotron radiation (λ = 0.748Å) and the two-step method (integrated intensities determined by individual profile fittings followed by last-squares refinement). A Rietveld analysis was also done in order to check for the reliability of the method. The site-occupancy formula was [Mn0.75In0.25] [Cr0.5Mn0.12In0.38]2S4. © by R. Oldenbourg Verlag, München 199
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
MWP-fit: a program for multiple whole-profile fitting of diffraction peak profiles by ab initio theoretical functions
Get PDFA computer program has been developed for the determination of micro-structural parameters from diffraction profiles of materials with cubic or hexagonal crystal lattices. The measured profiles or their Fourier transforms are fitted by ab initio theoretical functions for size and strain broadening. In the calculation of the theoretical functions, it is assumed that the crystallites have log-normal size distribution and that the strain is caused by dislocations. Strain and size anisotropy are taken into account by the dislocation contrast factors and the ellipticity of the crystallites. The fitting procedure provides the median and the variance of the size distribution and the ellipticity of the crystallites, and the density and arrangement of the dislocations. The efficiency of the program is illustrated by examples of severely deformed copper and ball-milled lead sulfide specimens
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