1,720,996 research outputs found
New thiophenic polymer for organic photovoltaic device
No full textRegioregular polyalkylthiophenes are a very important class of conjugated polymers characterized by interesting features for pratical applications, like organic photovoltaic cells and others electronic devices. The bulk heterojunction formed by regioregular poli(3hexylthiophene) (P3HT) and the PCBM fullerene derivative is here fully characterized as active layer for the fabrication of photovoltaic devices. We also present the synthesis of a new thiophenic polymer, the regioregular poly[3-(6-methoxyhexyl)thiophene] (P3HOMe) which demonstrates being very suitable to be used as the organic electron donor component. The simple introduction of a methoxy group at the end of an hexamethylenic side chain, strongly enhances the solubility, workability and filmability of the final polymer, making it a promising alternative to P3HT, which often gives problems related to its solubility and processability. From the electrical point of view, P3HOMe possesses an high conductivity comparable with P3HT and also shows an enhanced stability towards oxygen oxidative doping and a very low dependence of the conductivity on temperature changes. For these reasons, P3HOMe is a very promising intrinsically conducting polymer exhibiting strategic features in processing and utilization conditions, thus leading to important developments towards the obtainment of electronic organic materials such as photovoltaic cells
Highly Processable ester-functionalized polythiophenes as valuable multifunctional and post-functionalizable conjugated polymers
No full textA series of newly ester-substituted polyalkylthiophenes (PATEs) was prepared. All polymers were fully soluble in common
organic solvents, which allowed for a wide range of physico-chemical measurements, including solvato- and thermochromic,
thermal, microstructural and electrical (in neutral and doped state) analyses. Marked differences were observed in
the material characteristics of these polyalkylthiophene derivatives. It was thus possible to identify and describe the different
properties ascribable not only to the different esteric groups in side chain but also to the different average degrees of
functionalization of the thiophenic repeating units. In neutral state the PATEs of this study proved to be thermostable and
soluble, while at the same time exhibiting high ordered molecular assemblies leading to high average conjugation lengths,
electrical conductivities and stabilities. These polymers can also be easily and quantitatively transformed in other PAT
derivatives using simple nucleophilic reactions either in solution or in solid (film) state. In view of the above and given that
these polymers can be profitably and inexpensively synthesized, their future use for innovative applications in the field of
synthetic metals appears feasible as from now
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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