1,720,965 research outputs found
Toughened acrylic/melamine thermosetting clear coats using POSS molecules: Mechanical and morphological studies
No full textThis work attempts to introduce polyhedral oligomeric silsesquioxane compounds as a novel toughening agent for thermosetting systems. For this purpose, an acrylic/melamine thermosetting system was modified by OH-functional silsesquioxane nano-cage. Mechanical and thermo-mechanical behavior of resultant nanocomposites were studied by tensile and DMTA techniques. It was found that low content of silsesquioxane building blocks is sufficient to shift the mechanical behavior of the matrix from a brittle character to a flexible tough one. Various morphological techniques (SEM and TEM equipped with elemental analyzer together with XRD) were also utilized to clarify how nano-cages have been oriented within the matrix. It was revealed that nano-cages have been well dispersed in a molecular scale within the thermosetting network. The good dispersion of silsesquioxane compounds was assigned to the high compatibility within the matrix owing to their compact structure and OH-functional groups available on the cage
A scratch resistant yet healable automotive clearcoat containing hyperbranched polymer and POSS nanostructures
No full textIn this paper a typical acrylic melamine clearcoat has been modified with hyperbranched polymer and polyhedral oligomeric silsesquioxane nanostructures to simultaneously enhance its scratch resistance and healing ability. Scratch behaviour and healing performance of clearcoats were investigated by micro-scratching and confocal profilometry techniques. Various techniques were employed to correlate scratch resistance and healing enhancements to the various mechanical and structural characteristics of nano clearcoats. Enhanced scratch resistance was attributed to the increased elastic recovery of the clearcoats in the presence of nano-structured modifiers. In addition, the improved self-healing performance was assigned to the partial replacement of covalent cross-links with physical ones i.e. H-bonding. Simultaneous reinforcement with covalent and physical linkages led to the formation of a more flexible network which maintains its mechanical integrity at ambient temperature and also provides dynamic chain movements for thermal healing treatments at high temperature
Tribological properties and scratch healing of a typical automotive nano clearcoat modified by a polyhedral oligomeric silsesquioxane compound
No full textThe present work has studied the influence of an OH-functionalized polyhedral oligomeric silsesquioxane(POSS) nano-structure on the scratch resistance of a typical acrylic melamine clearcoat. Scratch resistance and the healing ability of clearcoats were investigated by micro-scratch studies and confocal profilometry techniques. In addition, hardness and thermo-mechanical characteristics of clearcoats were investigated by micro-indentation and dynamic mechanical thermal analysis (DMTA) respectively, to correlate the scratch behavior to the mechanical and structural properties of the clearcoats. The results revealed that incorporation of FOSS cages into clearcoats could effectively enhance the scratch resistance. This was attributed to the higher hardness and cross-linking density of the resulting nanocomposite coatings. The healing results also demonstrated that nanocomposites had a higher healing ability compared to the neat clearcoat. The higher healing of nanocomposites was explained by the physical H-bonding interactions formed in vicinity of POSS cages. The transparency measurements proved that these improvements were fulfilled without any negative effect on the optical quality of clearcoats
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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