1,720,960 research outputs found
Nanostructured Magnetic Films Produced by Magnetic Nanoparticles
No full textGas-phase Fe nanoparticles with a diameter ~ 2nm, have been used in all the nanostructured material in this thesis. In pure Fe nanoparticle systems with different thicknesses, two important parameters the exchange interaction (Hex) and random anisotropy (Hr) were investigated using the Random Anisotropy Model (RAM). This reveals that for the same particle size Hex remains almost constant for varying Fe thicknesses; whereas Hr increases with the increase of Fe film thickness. This is ascribed to increasing strain imposed at the nanoparticle level. The observed high values of Hr are related to an oxide on the cluster surface in these films, whose effect is also observed in low temperature magnetometry data. This shows the appearance of exchange bias in the films. The RAM approach when applied to Fe clusters in Co matrices, reveals much lower values of Hr than found in pure Fe nanoparticles and both Hr and Hex show an increase with the Volume Fraction (VF) of Fe in Co. The increase in Hex is ascribed to the increasing spin moment with Fe volume fraction. The nature of Fe clusters in very thick layers produce a high frequency Ferromagnetic Resonance response in the radio frequency range, which is an important finding for many applications.
The EXAFS study of Fe nanoparticles in Cr matrices show no structural modification relative to the bulk bcc structure of both elements. The magnetometry results suggest that in dilute Fe concentration films, the observed decrease in the overall magnetization is due to the development of a nonmagnetic shell at the interface between Fe and Cr at each cluster boundary. This is reinforced by the lack of any evidence of EB. With increasing VF at about 10% of Fe there is strong evidence of the formation of a super-spin-glass (SSG) that shows the characteristic memory effect. Increasing the Fe nanoparticles VF to 20% Fe in Cr, the magnetization exceeds that expected for Fe indicating that the interaction induces some of the Cr to order ferromagnetically.
Core-shell nanoparticle systems have been synthesised by a method that allows a complete control over the morphology of these assemblies. Atomic investigations in Fe@Cu CS nanoparticles reveal that Fe nanoparticles adopt the fcc structure with a 20 monolayer Cu shell thickness and stay in the bcc structure for 1-2 monolayer thick Cu shells. No alteration in the Fe atomic structure has been reported for different Au shell thicknesses in Fe@Au. The magnetic data show a reduced magnetization of the FM-AFM Fe@Cr CS nanoparticles as compared to the bulk value which is also ascribed to the formation of a non-magnetic Fe shell at the interface
Optical and Magnetic Response of Pure and CU-Ions Substituted Dysprosium Oxide Thin Films for Various Applications
Full text linkDysprosium oxide (Dy2O3) and Cu/Dy2O3 thin films of thickness 117.14 nm and 258.30 nm, respectively were successfully deposited via a well-known DC-magnetron sputtering technique. Field emission scanning electron microscopy clarifies the growth of uniform and fine granular particles on silicon substrate. The hexagonal closed pack structure for both the thin films has been observed by the x-ray diffraction analysis and it was observed that by inclusion of copper the HCP structure of thin film was retain with a slight shift in the main peak. The reduction from 3.9 eV to 3.8 eV in the energy band gap value was observed by incorporation of copper ions Dy2O3 thin films. The M-H loops obtained through Vibrating Sample Magnetometer (VSM) shows that Dy2O3 thin film behave ferromagnetically at low temperature with a saturation magnetization value of 2860 emu/cc and evolves through its phase transition temperatures and behave paramagnetically at room temperature. In Cu/Dy2O3 case, the diamagnetic response of Cu dominates and produces reverse hysteresis loop at both temperatures make it a suitable candidate for energy and memory storage devices applications
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
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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