1,720,994 research outputs found
Magnetic characteristics adjustment through rare-earth lanthanum substitution in mechanically alloyed yttrium iron garnet nanoparticles
Full text linkYttrium iron garnet (YIG) is a very important ferrimagnetic ceramic and widely used in high frequency magneto-optical applications due to its high saturation magnetisation and low magnetic loss up to several GHz. Magnetic properties of YIG are strongly dependent on the processing technique, in which small amount of dopants can largely affect its properties. In this study, the effect of various lanthanum (La) content on structural, microstructural and magnetic characteristics of YIG was reported. The nanosized powders of La-subtituted YIG with La content of 0.0 to 0.5 were synthesised using mechanical alloying technique for 6 h followed by sintering at 1400°C. The physical characteristics of the samples were analysed using XRD, FTIR, TEM and SEM, meanwhile the magnetic and thermomagnetic characteristics of the samples were measured using VSM and LCR-meter respectively. The particle size of as-milled samples showed an increment from 38 to 53 nm with increasing La content and the XRD patterns of the samples showed evidently a highly crystalline and full phase YIG ferrite, regardless of its La content. While the microstructure of the samples barely remains consistent for all La content, the saturation magnetisation of the samples showed reduction with increasing La content. This is due to the magnetic dilution caused by La in overall superexchange interaction in magnetic moments of YIG, which is attributed to the paramagnetic nature of La rare earth ions at room temperature
Structural, microstructural and magnetic performance of NdFeB/Ni-Zn ferrites hybrid magnetic composites
No full textHybrid magnets integrate permanent and soft magnetic materials, resulting in enhanced magnetic performance suitable for a variety of applications. Neodymium-iron-boron (NdFeB) magnets, known for their high energy output, exhibit limitations at elevated frequencies due to eddy current effects. To address this problem, it is beneficial to combine NdFeB with high-resistivity nickel zinc ferrites (NZF) to optimize their magnetic properties. This study focuses on the synthesis of NZF and the fabrication of NdFeB/NZF hybrid composites with varying ratios of NdFeB-to-NZF (40:60, 50:50, and 60:40) and different configurations. Their structural, microstructural, and magnetic characteristics were analyzed to identify the optimum fraction for the hybrid composite formulations. In this work, a commercially available NdFeB and NZF were synthesized via high-energy ball milling while NdFeB was used for the composite’s fabrication. Among the synthesized samples, the mixture-composites of a 60:40 ratio exhibited the highest saturation magnetization of 43.01 emu/g with a notable Curie temperature of 390 °C. The results indicate that increasing the hard phase of NdFeB enhances both saturation magnetization and Curie temperature in all composite samples. Conversely, the stacked-composites with a 40:60 ratio displayed the highest resistivity at 7.96x106 Ωm, suggesting that a higher proportion of NZF significantly contributes to increased resistivity. The observed enhancements in magnetic properties can be attributed to the exchange spring mechanism between the soft and hard magnetic phases, as well as the larger grain size in the samples, which promotes a greater number of magnetic domains and reduction of the grain boundaries. Thus, it facilitates more efficient domain wall movement in response to the external magnetic field
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
Evolution of Magnetic Properties in Ferrites: Trends of Single-Sample and Multi-Sample Sintering
Full text linkMicrostructure of magnetic materials greatly influences the performance of magnetic properties, and sintering has been used as an agent to tailor the microstructure of these magnetic materials especially ferrites. Nanostructured ferrites prepared by high-energy milling method are often inherently unstable owing to their small constituent sizes, non-equilibrium cation distribution, disordered spin configuration, and high chemical activity. Therefore, sintering of the milled ferrites recrystallizes the nanostructure and causes its transition from an excited metastable (activated) state into the low-energy crystalline state. A better understanding of the response of nanoscale ferrites with changes in temperature is crucial not only for basic science (the development of an atomistic and microscopic theory of the mechanochemical processes) but also because of the technological high-temperature applications in catalysis, ferrofluids and information storage. This chapter discusses on two different sintering schemes, which are a commonly applied multi-sample sintering and a rarely adopted single-sample sintering. Experimental results of single-sample and multi-sample sintering of NiZn ferrites and yttrium iron garnet (YIG) were highlighted, and their microstructural consequences on the magnetic properties were also discussed
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
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