1,721,277 research outputs found
Transformation of polysialate matrixes from Al-rich and Si-rich metakaolins: Polycondensation and physico-chemical properties
No full textTwo metakaolins from Al-rich and Si-rich kaolinitic clays were used to design polysialate matrices with different Si/Al and NaK/Al ratios. The aim was to investigate the influence of oligomers formed during dissolution and hydrolysis on the polycondensation and transformation to hard and stable matrices. Products of geopolymerization of the different matrices were subjected to mechanical testing considering various loading configurations. The geopolymer matrices showed compressive strength from 51 ± 5 MPa (Si/Al = 1.23) to 61 ± 2 MPa (Si/Al = 2.42) and bi-axial four-point strength from 11 ± 2 MPa to 16 ± 1.1 MPa respectively. These results obtained were consistent with density, leaching ability, and microstructure. It is proposed that the mechanical properties and the stability of the products of reactions can be discussed as the important parameters for the evaluation of geopolymer matrices. Moreover, polycondensation and the final performance of the product are greatly influenced by the unreacted crystalline or semi-crystalline phases that act as fillers and contribute to increase the stability and mechanical properties
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
Dynamic neutron diffraction study of thermal stability and self-recovery in aluminium titanate
Full text linkAluminium titanate (Al2TiO5) is an excellent refractory and thermal shock resistant material dueto its relatively low thermal expansion coefficient and high melting point. However, Al2TiO5 unstableand undergoes a eutectoid-like decomposition to a-Al2O3 and TiO2 (rutile) at the temperature range of900-1280C. In this paper, we describe the use of high-temperature neutron diffraction to study (a) thephenomenon of self-recovery in decomposed Al2TiO5, and (b) the role of grain size on the rate ofisothermal decomposition at 1100C. It is shown that the process of decomposition in Al2TiO5 isreversible whereby self-recovery occurs readily when decomposed Al2TiO5 is re-heated above 1300C,and the rate of phase decomposition increases as the grain size decreases
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
Study of high-temperature thermal stability of MAX phases in vacuum.
Full text linkThe susceptibility of two MAX phases (Ti2AlN and Ti 4AlN3) to high-temperature thermal dissociation in a dynamic environment of high-vacuum has been investigated using in-situ neutron diffraction. In high vacuum, these phases decomposed above 1400°C through the sublimation of Ti and Al elements, forming a surface coating of TiN. The kinetics of isothermal phase decomposition was modelled using the Avrami equation and the Avrami exponent (n) of isothermal decomposition of Ti 2AlN and Ti4AlN3 was determined to be 0.62 and 0.18 respectively. The characteristics of thermal stability and phase transitions in Ti2AlN and Ti4AlN3 are compared and discussed.American Ceramic Society; American Ceramic Society’s Engineering Ceramics Divisio
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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