1,721,183 research outputs found
Lung penetration and patient adherence considerations in the management of asthma: role of extra-fine formulations [Corrigendum]
No full textScichilone N, Spatafora M, Battaglia S, Arrigo R, Benfante A, Bellia V. J Asthma Allergy. 2013;6:11–21. On page 13, Figure 1 was incorrect.Read the original article her
Fully bio-based ternary polymer blends: structural characterization and mechanical behavior
No full textIn this work, ternary immiscible blends based on poly (lactic acid) (PLA) as major phase and polybutylene succinate (PBS) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHH) as minor phases were prepared through melt blending, aiming at obtaining fully biobased materials with enhanced ductility and toughness as compared to the inherently brittle matrix. Thermodynamic considerations based on the calculation of the interfacial tensions predicted the achievement of a partial encapsulation between the domains of the two minor components embedded in the PLA matrix. The rheological characterization revealed higher melt viscosity and elasticity for all the ternary blends as compared to the PLA matrix and a growing level of interfacial interactions between the different phases when increasing amounts of PBS are incorporated. This last was confirmed through morphological observations, which allowed demonstrating the achievement of an improved homogeneous microstructure for the blends containing 30 and 40 wt% of PBS, notwithstanding the relatively good interfacial adhesion obtained in all the explored materials. The combined effect of the strong established interfacial interactions and of the uniform morphology resulted in the obtainment of dramatic increments of ductility, tensile toughness and impact strength for all formulated ternary blends as compared to the PLA matrix, and especially for those containing 30 or 40 wt% of PBS, while maintaining satisfactory levels of stiffness and tensile strength
Rheology, Morphology and Thermal Properties of a PLA/PHB/Clay Blend Nanocomposite: The Influence of Process Parameters
Full text linkThe effect of process parameters on the final properties of a poly-lactic acid (PLA) and polyhydroxybutyrate (PHB) polymer blend filled with nanoclays was evaluated. To this aim, the nanofilled blend was processed in a co-rotating twin screw extruder, considering three different screw profiles and different values of the screw rotation speed, and the thermal and thermo-mechanical properties of the so-obtained materials were investigated. Furthermore, XRD analyses, SEM observations and rheological characterization were exploited to infer the coupled effect of the process parameters and nanoclay presence on the microstructure of the filled blend. Preliminary thermodynamic calculations allowed predicting the preferential localization of the nanoclay in the interfacial region between the polymeric phases. The relaxation mechanism of the particles of the dispersed phase in nanofilled blend processed, by rheological measurements, is not fully completed due to an interaction between polymer ad filler in the interfacial region with a consequent modification of the blend morphology and, specifically, a development of an enhanced microstructure. Therefore, by varying the screw configuration, particularly the presence of backflow and distribution elements in the screw profile, high shear stresses are induced during the processing able to allow a better interaction between polymers and clay. This finding also occurs in the thermo-mechanical properties of material, as an improvement of storage modulus up to 20% in filled blend processed with a specific screw profile. Otherwise, the microstructure of filled blend processed with different screw speed is similar, according to the other characterizations where no remarkable alterations of materials were detected
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
Tunable radical scavenging activity of carbonaceous structures and their anti-oxidant behavior in polymer based nanocomposites
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