1,720,964 research outputs found
Investigation of Sm → Ca substitution in Bi(Pb)SrCaCuO high temperature superconductor by low field AC magnetic susceptibility
No full textYegen, Dincer/0000-0003-3180-600X; Terzioglu, Cabir/0000-0002-3944-0367We have investigated the effect of Sm substitution in Bi(Pb)SrCaCuO system by performing AC susceptibility (chi = chi' + i chi ''), XRD (X Ray Diffraction) and SEM (Scanning Electron Microscopy) measurements. The Sm -> Ca substitution (Bi(1.)6Pb(0.4)Sr(2)Ca(2-x)Sm(x)Cu(3)O(y)) was carried out by conventional solid-state reaction method. The susceptibility measurements were carried out at different values of the AC field amplitudes. The imaginary part of susceptibility is used to estimate the intergranular critical current density by means of the Bean's model. The intergranular critical current density (J(c)) of pure sample is found to be about 68 A/cm(2) at 95 K. The intergranular J(c) is seen to decrease with increasing Sm substitution. XRD pattern and SEM micrographs are given to provide information about Bi-2223 phase and grain size respectively
Structural and physical properties of Sm-doped Bi1.6Pb0.4Sr2Ca2-xSmxCu3Oy superconductors
No full textOzturk, Ozgur/0000-0002-0391-5551; Terzioglu, Cabir/0000-0002-3944-0367The superconducting Bi1.6Pb0.4Sr2Ca2-xSMxCu3Oy (X = 0.0, 0.0005, 0.001, 0.005, 0.01, 0.1, 0.5, 1.0, and 1.5) system was investigated for different concentrations of Sm. The structural analysis was carried out by XRD. XRD results show that the samples with substitution of various amounts of Sm for Ca transform from the major high-T-c phase (Bi-2223) to the low-T-c phase (Bi-2212). The lattice parameter data extracted from XRD showed that with increasing Sm concentration (x), the lattice parameter a increases slightly while the lattice parameter c decreases significantly. DC resistivity measurements were carried out by the standard four-probe technique in the temperature range between 25 K and 130 K. With increasing Sm substitution up to x = 0.1, the values of T-e(offset) vary between 107 K and 70 K. The samples with x > 0.1 did not show any superconducting transition down to 25 K. The critical current density measurements were performed in liquid nitrogen. Critical current density decreases with increasing Sm substitution, and it was measured to be 43 A/cm(2) for the sample with x = 0.0 at zero field. Microstructure examinations were carried out by SEM. All the reported data were discussed, and compared with earlier results on Sm and other substituted Bi-Sr-Ca-Cu-O system. (c) 2005 Elsevier B.V. All rights reserved
Electron Paramagnetic Resonance and High Temperature Susceptibility Measurements in Cesium Hexabromide.
Get PDFTo our knowledge the research reported here represents the first attempt to understand the 4f electronic structure in CeB6 using EPR. We report extensive temperature and angular dependent EPR measurements on a single crystal of CeB6 in the paramagnetic phase from 4 to 300 K at 35, 95, and a few measurements at 220 GHz. The 35 GHz measurements were performed at LSU and the 95 and 220 GHz measurements were performed at the National High Magnetic Field Laboratory, Tallahassee, FL. These experiments were made using a standard microwave frequency-locked spectrometer and magnetic field modulation. The measurements are supplemented by temperature and field dependent DC measurements of the sample magnetization. From the EPR line shapes, g-value and spin-lattice relaxation time (T1) were extracted. The EPR results for CeB6 showed one absorption peak at the magnetic field corresponding to temperature independent g-value of g = 1.98 and T1 = 6.35*10 -11 seconds at room temperature. The g factor for this transition is independent of temperature between 4 and 300 K, depends on magnetic field (measurement frequency) in a non-monotonic manner, and depends slightly on crystal orientation with respect to the applied field direction in the [100] plane. The line width of the EPR spectra decreased and the relaxation time increased with increasing temperature because of exchange narrowing. Similar measurements were performed on ferromagnetic EuB6 and g values and spin-lattice relaxation times were extracted
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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