1,721,044 research outputs found
Influence of block length on crystallization kinetics and melting behavior of poly(butylene/thiodiethylene succinate) block copolymers
No full textThe melting behavior and the crystallization
kinetics of block poly(butylene/thiodiethylene succinate)
copolymers (PBSPTDGS) with identical chemical composition
(i.e., BS:TDGS = 50:50 mol %) were investigated
by means of differential scanning calorimetry.
Multiple endotherms were evidenced in PBSPTDGS samples,
because of melting and recrystallization processes,
similar to poly(butylene succinate) (PBS). By applying the
Hoffman–Weeks’ method, the Tm of the copolymers was
derived. The isothermal crystallization kinetics was analyzed
according to the Avrami’s treatment. The copolymer
with long PBS blocks (PBSPTDGS15) is characterized by
a very similar behavior with respect to pure PBS, indicating
that PBS macromolecular folding is not affected by the
presence of noncrystallizable thiodiethylene succinate
blocks. In all the other cases, the overall crystallization rate
was found to decrease as the block length is decreased,
even though the work of chain folding, derived on the basis
of Hoffman–Lauritzen nucleation theory, also decreased
with the block length
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
Crystallization behavior and morphology of poly(propylene terephthalate) copolymers containing neopenthyl glycol moieties
No full textCrystallization kinetics, melting behavior, and RAP of novel etheroatom containing naphthyl polyesters
No full textThe changes in crystalline phase of poly
(butylene naphthalate) (PBN), poly(diethylene naphthalate)
(PDEN) and poly(thiodiethylene naphthalate) (PTDEN)
upon thermal treatments were evaluated by X-ray diffraction
technique. The melting behavior and the crystallization
kinetics of the polymers under investigation were
investigated by means of differential scanning calorimetry.
Multiple endotherms were evidenced in PBN and PTDEN,
due to melting and recrystallization processes. By applying
the Hoffman–Weeks’ method, the Tm of PBN, PDEN, and
PTDEN was derived: the introduction of ethero-atoms
along PBN polymer chain causes a decrement of Tm value.
The isothermal crystallization kinetics was analyzed
according to the Avrami’s treatment: the presence of etheroxygen
or sulphur atoms in the chain deeply reduces the
PBN ability of crystallizing. Finally, no interphase was
evidenced both in PDEN and PTDEN
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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