1,721,037 research outputs found
The effects of molecular weight dispersity on block copolymer self-assembly
No full textThe influence of dispersity in the molecular weight distributions in the core forming block for block copolymer (BCP) self-assembly is analyzed via an automated flow synthesis approach. Polystyrenes with increasing dispersity in the core forming block are synthesized from reversible addition–fragmentation chain transfer (RAFT) polymerization with an average degree of polymerization (DPn) of 15 and 50 and dispersities between 1.10 and 1.45. After chain extension of these polymers with hydroxy ethyl acrylate, the residual BCPs were subjected to nanoaggregate formation via continuous flow mixing. Nanoaggregates were carefully analyzed with an ensemble of dynamic light scattering (DLS), scanning transmission electron microscopy (STEM) and small angle neutron scattering (SANS). With an increase in the dispersity of the core forming polymer block, the overall dispersity of the nanoparticles was reduced, demonstrating that lower polymer dispersities are not necessarily more advantageous to form uniform nanostructures. This unravels the fundamental role of molecular weight distribution shape in polymer self-assembly and introduces a new tool for tuning particle properties, specifically via continuous flow processes
3D-Printed Biobased Porous Polymer Scaffolds Reinforced with Bioactive Glasses by High Internal Phase Emulsion Polymerization
No full textOne-pot multifunctional polyesters by continuous flow organocatalysed ring-opening polymerisation for targeted and tunable materials design
No full textTargeted and tunable access to biodegradable polymers will be vital for their continued adoption and use in modern materials applications. Herein we report a platform for the synthesis of well-defined, curable biodegradable polymer precursors, prepared in a controlled manner via continuous flow ring-opening polymerisation/post-modification reactions of epsilon-caprolactone and L-lactide. Polymer architectures are characterised by H-1 NMR spectroscopy, ESI mass spectrometry, and size exclusion chromatography, and their potential application in materials synthesis is subsequently highlighted by employing them as precursors to prepare networks and polymerised high internal phase emulsions (polyHIPEs) via an emulsion templating strategy using photo-initiated thiol-ene click reaction.The authors acknowledge the use of the instruments and scientific and technical assistance at the Monash Centre for Electron Microscopy, a Node of Microscopy Australia, and thank the Australian Research Council for funding (DP190103309)
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
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