1,720,980 research outputs found
Mg-substituted tricalcium phosphates: Formation and properties
No full textThis study aimed to investigate the formation and properties of magnesium (Mg)-substituted tricalcium phosphate, beta-TCMP, its properties and potential as biomaterial for bone repair. beta-TCMPs were prepared and characterized using x-ray diffraction, FT-IR and SEM. Dissolution properties were determined in acidic buffer. beta-TCMP discs were implanted in surgically created holes in femoral and tibial diaphyses of rabbits. Results demonstrated that the formation of beta-TCMP and Mg incorporation in beta-TCMP were dependent on reaction pH, temperature and solution Mg/Ca ratios. Sintered beta-TCMP was significantly less soluble than beta-TCP. Implanted unsintered beta-TCMP showed osteoconductive properties associated with new bone formation. This study suggests that beta-TCMP (sintered or unsintered), alone or in combination with other calcium phosphates, may be useful as biomaterials for bone repair and maybe useful in cases where slower biodegradation than that of beta-TCP is desire
Structural Characterisation of Bioactive Glasses
Get PDFMelt-quenched glasses containing SiO2, CaO, Na2O and P2O5, and sol-gel
derived glasses containing SiO2 and CaO are known to have bioactive properties.
Foaming of binary sol-gel derived bioactive glasses containing SiO2 and CaO can be
used to produce 3D porous scaffolds which mimic the structure of trabecular bone,
increasing the potential for these glasses to be used as bioactive bone-regenerative
materials.
A range of experimental techniques have been used to investigate the atomic
scale structure of these materials, and also to observe the reaction mechanisms which
occur when these materials are immersed in a simulated physiological solution
(simulated body fluid, SBF) and a standard cell culture medium (tris buffer solution,
TBS).
A robust structural model of the most bioactive of the melt-quenched glasses,
namely Bioglass®, has been produced by combining high energy X-ray and neutron
diffraction data, magic angle spinning nuclear magnetic resonance (MAS NMR) and
reverse Monte Carlo (RMC) modelling. It has been shown that Ca clustering occurs
in the glass, which is of direct relevance to the understanding of the facile nature of
calcium within such glasses giving rise to its relatively rapid diffusion from the solid
into solution.
Hydroxyapatite has been confirmed as the calcium phosphate phase which
grows on the surface of Bioglass® when immersed in the standard cell culture
medium, TBS.
A new method which can be used for in-situ time resolved high-energy X-ray
diffraction studies of reaction mechanisms, such as those involved when a bioactive
glass is immersed in a simulated physiological solution, is decribed in this thesis.
Small-angle X-ray scattering has enabled the growth of mesopores to be
observed during the foamed sol-gel stabilisation process. In-situ simultaneous small
and wide angle X-ray scattering measurements of a foam in SBF have shown that the
mesoporous network facilitates the rapid growth of relatively high-density HCA,
which will therefore eventually replace the initial silicate glass as the material
bounding the macropores.
The data presented herein reveal the structure of highly important materials in
the field of biomaterials and enable a link to be made between the atomic scale
structure of the materials and their bioactive properties
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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