1,721,065 research outputs found
Effect of topology on the adhesive forces between electrospun polymer fibers studied using a T-peel test
No full textElectrospinning provides an effective methodology to obtain high aspect ratio polymer fibers for biomimetic applications. In this article, we evaluate the effect of topology on adhesion between aligned fibers. Polycaprolactone is electrospun using two different setups: (i) a tip collector and (ii) a flat collector. The tip collector enables the fibers to self-align. When a fiber reaches the tip collector, the next fiber is repelled by the charge they carry, forcing the fibers to deposit in a parallel arrangement. The flat collector allows the fibers to deposit at random. The adhesion between the fiber mats is measured using a T-peel test. Adhesion strength (758.7 ± 211.7 kPa) changes marginally with the peeling rate and applied pressure on the membranes. Aligned fibers exhibit higher adhesion strength between the membranes in comparison to randomly oriented nonwovens (613.1 ± 79.9 kPa). The estimated Johnson–Kendall–Roberts contact energy (83.1 ± 32.5 mJ/m2) is consistent with the range of van der Waals adhesion forces. This work shows how the adhesion between two polymer membranes can be modulated by surface topology, based on a T-peel testing setup.Fil: Montini Ballarin, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingenieria; ArgentinaFil: Blackledge, Todd A.. The University Of Akron (uoa);Fil: Capitos Davis, Nicole L.. Center for Research and Technology; Estados UnidosFil: Frontini, Patricia Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingenieria; ArgentinaFil: Abraham, Gustavo Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingenieria; ArgentinaFil: Wong, Shing Chung. The University Of Akron (uoa)
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
A Micromechanics Analysis of Nanoscale Graphite Platelet-Reinforced Epoxy Using Defect Green\u27s Function
No full textIn the modeling of overall property of composites, the effect of particle interaction has been either numerically taken into account within a (representative) volume element of a small number of particles or neglected/ignored in order for efficient solution to a large system of particles. In this study, we apply the point-defect Green\u27s function (GF) to take into account the effect of particle interaction. It is applicable to small volume fractions of particles (within 10%). The high efficiency of the method enables a simulation of a large system of particles with generally elastic anisotropy, arbitrary shape and composition, and arbitrary spatial distribution. In particular, we apply the method to study the nanoscale graphite platelet reinforced polymers, guided by some preliminary experimental observations. We first verify the method by comparing the prediction with a full-field model in the case of a regular lattice of particles. The comparison has demonstrated that the method is a considerable improvement over the classical Eshelby\u27s method employing the regular GF and thus ignoring the effect of particle interaction. Upon the verification, we apply the method to examine the effect of a number of parameters on the overall composite behavior. The effect of particle interaction is shown to be strongly dependent on particle arrangement due to the strong elastic and geometrical anisotropy in graphite platelets. The strongest effect occurs when the platelets are orientated uniformly and stacked in a simple cubic lattice. However, the (overall) effect becomes trivial when the platelets are randomly orientated, which is expected. The effect of platelet aspect ratio is also studied. Finally, a thin soft layer is inserted between the platelets and the matrix material in order to simulate a partial bonding condition between them. It is shown to play a significant role in determining the overall composite behavior. The present work sets up a base for further large-scale simulations of micro-damages (microcracks, particle debonding, etc.) under interaction, as well as providing insights to further experimentation in graphite platelet nanocomposites
Structure-property Relationship of Some Novel Multi-component Polymeric Materials
Get PDFThis thesis is concerned with the study of microstructure—property relationship in
selected multi—component polymeric materials using a variety of microscopic and fracture
characterization techniques. An approach based on concepts and principles was adopted
throughout its presentation. A major objective in this thesis was to understand the effect
of reactive functionality on microstructures, fracture toughness and toughening
mechanisms in nylon 6,6/polypropylene (PP) blends, which were compatibilized by
styrene-ethylene/butylene-styrene block copolymers (SEBS). It was emphasized that
morphological control arising from the change in the degree of reactive functionality in
SEBS was most effective in providing the essential toughening and compatibility in 75/25
nylon 6,6/PP blends. Toughness characterization was accomplished using rigorous
fracture mechanics concepts. Novel concept of the specific essential fracture work was
tested in the short glass fiber—reinforced blends. In situ fibers in the form of liquid
crystalline polymer (LCP) fibrils were also attempted on polymer blends. The effect of
LCP inclusions on mechanical and fracture properties was examined in the framework of
composite theory in relation to the observed microstructures
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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