1,720,993 research outputs found
Applications of Magnetic Oxide Nanoparticles in Hyperthermia
No full textMagnetic oxide nanoparticles (NPs) are probably the most common nanomaterials in everyday biomedicine, and have been in use since the 1990’s. They are usually magnetic iron oxide NPs, made of magnetite (Fe3O4 -Fe2O3), or a mixture of the two. Both of these have the spinel structure, and other spinel ferrites such as ZnFe2O4, CoFe2O4 and NiFe2O4 are also used. For applications in magnetic hyperthermia these NPs must be below the magnetic domain size, making them superparamagnetic, which means that their magnetisation can be “switched on” by the application of an external magnetic field. Magnetic hyperthermia treatment is a form of thermotherapy which is used to kill tumour cells with thermal energy (heat) in a very localised manner, by causing magnetic oxide NPs to heat up near tumour cells. Under an applied AC magnetic field the magnetic spin of the NPs switches rapidly in direction, transforming the magnetic energy into thermal energy. Temperatures of 41-46 °C are sufficient, this localised heating elevating the temperature of tumour cells, inhibiting growth, killing them, or inducing tumour cell apoptosis. Magnetic NPs were first used in tumour thermotherapy in 1996, and since then there has been a great deal of research in this field. The treatment can be applied alone, or used in combination with other therapies such as surgery, radiotherapy and chemotherapy, and it has shown excellent synergistic effects in combination with anticancer drugs (chemotherapeutics)
Multiferroic and Magnetoelectric Hexagonal Ferrites
No full textThe hexagonal ferrites, also known as hexaferrites, have become massively important materials commercially and technologically, accounting for the bulk of the total magnetic materials manufactured globally, and they have a multitude of uses and applications. As well as their use as permanent magnets, common applications are as magnetic recording and data storage materials, and as components in electrical devices, particularly those operating at microwave/GHz frequencies for mobile and wireless communications, electromagnetic wave absorbers for electromagnetic compatibility (EMC), radar absorbing materials (RAM) and stealth technologies. One of the most exciting recent developments has been the discovery of single phase magnetoelectric/multiferroic hexaferrites, firstly Ba2Mg2Fe12O22 Y-type ferrite at cryogenic temperatures, and more recently Sr3Co2Fe24O41 Z-type ferrite at room temperature. Several Y-type, substituted M-type, and U-type (Sr4Co2Fe36O60) ferrites have now been characterised as room temperature multiferroics, and are discussed in this chapter. © Springer-Verlag Berlin Heidelberg 2014
Combinatorial Materials Science, and a Perspective on Challenges in Data Acquisition, Analysis and Presentation
No full textCombinatorial Materials Science is the rapid synthesis and analysis of large numbers of compositions in parallel, created through many combinations of a relatively small number of starting materials. It is, therefore, essential that for a truly combinatorial approach both synthesis and measurement must be high-throughput, to handle the large number of samples required. Since the first serious attempts at combinatorial searches in Materials Science in the mid 1990s, the technique is still very much in its infancy, falling way behind the progress made in biomedical and organic combinatorial chemistry, despite attracting increasing interest from industry. The most investigated materials by combinatorial methods are catalysts and phosphors, and most work has been on libraries in deposited thin film form. This chapter will give a broad overview of the different synthetic strategies used, with a particular look at the difficulties of producing thick film or bulk ceramic/metal-oxide libraries. A vast number of characteristics can be quantified in combinatorial materials libraries, from compositional, crystal phase, structural and microstructural information, to functional properties including catalytic/photocatalytic, optical/luminescent, electrical/dielectric, piezoelectric/ferroelectric, magnetic, oxygen-conducting,watersplitting, mechanical, thermal/thermoelectric, magnetoelectric/optoelectric/magnetooptic/ multiferroic, bioactive/biocompatible, etc. This chapter will cover the range of high-throughput measurements open in combinatorial Materials Science, and especially the challenges in presenting and displaying the large and complex amount of data obtained for functional materials libraries. To this end, the use of glyphs is looked at, glyphs being data points that also contain extra levels of information/data in graphic form
Synthesis and Characterisation of Magnetoelectric Ceramic Composites based on M-type Strontium and Barium Hexagonal Ferrites and Barium Titante
No full textMagnetoelectric composite ceramics were prepared to study their phase compatibility, magnetic and piezoelectric/ferroelectric properties, and coupling between magnetic and ferroelectric properties. The synthesis of various BaFe12O19 and SrFe12O19 hexaferrites was undertaken with different sintering temperatures, and exploring four different methods: solid state reaction, coprecipitation, sol-gel and citrate (Pechini) routes. Ceramic composites of BaM and SrM with BaTiO3 (BT) as a ferroelectric/piezoelectric phase, were prepared with both uniaxial and isostatic pressing, and then sintered. The composites were characterised by XRD, SEM and VSM. Results showed that BaM and BT did not react in the composites, while SrM-BT composites possess SrM, BT and SrTiO3 phases
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
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