1,720,980 research outputs found
Hybrid electrolytes for lithium-ion batteries
No full textLithium-ion batteries (LIBs) are playing a central role in the transition to a postoil society. Solid-state electrolytes are considered a promising technology to achieve high energy density (500Wh/kg) by implementing Li metal as anode material, as well as to overcome the safety concerns related to the liquid electrolytes used in LIBs. In this chapter, the limitations of traditional polymer solid electrolytes and the recent advances in hybrid solid electrolytes (e.g., composite solid electrolytes) will be reported. Furthermore, the effects of the inorganic filler (e.g., concentration, particle size, morphology, etc.) on Li+ ions’ conduction mechanism will be elucidated. Finally, the advantages of the use of ionic liquids will also be introduced
Hydrogels Generated from Cyclic Poly(2-Oxazoline)s Display Unique Swelling and Mechanical Properties
No full textCyclic macromolecules do not feature chain ends and are characterized by a higher effective intramolecular repulsion between polymer segments, leading to a higher excluded-volume effect and greater hydration with respect to their linear counterparts. As a result of these unique properties, hydrogels composed of cross-linked cyclic polymers feature enhanced mechanical strength while simultaneously incorporating more solvent with respect to networks formed from their linear analogues with identical molar mass and chemical composition. The translation of topology effects by cyclic polymers into the properties of polymer networks provides hydrogels that ideally do not include defects, such as dangling chain ends, and display unprecedented physicochemical characteristics
Fabrication of Biopassive Surfaces Using Poly(2-alkyl-2-oxazoline)s: Recent Progresses and Applications
No full textPoly(2-alkyl-2-oxazoline)s (PAOXAs) are emerging among the most promising nonionic alternatives to poly(ethylene glycol)s (PEGs), specifically in the modification and functionalization of biomaterials. Due to their chemical tailorability and robustness, coupled to their relatively easy synthesis, PAOXAs are increasingly applied as adsorbates to generate bioinert surfaces that prevent nonspecific contamination by proteins, cells and bacteria. Passivation of medical devices, sensors and cell-sensitive platforms with PAOXAs enables a nearly quantitative suppression of nonspecific biological contamination, while biopassivity is maintained over longer incubation times than those recorded for more degradable PEG-based coatings. Thanks to these unique advantages, surface modification strategies involving PAOXAs are expanding to nanomaterials, especially those applied in the fabrication of nanomedicine and bioimaging tools
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
Topology and Molecular Architecture of Polyelectrolytes Determine Their pH-Responsiveness When Assembled on Surfaces
No full textPolymer composition and topology of surface-grafted polyacids determine the amplitude of their pH-induced swelling transition. The intrinsic steric constraints characterizing cyclic poly(2-carboxypropyl-2-oxazoline) (c-PCPOXA) and poly(2-carboxyethyl-2-oxazoline) (c-PCEOXA) forming brushes on Au surfaces induce an enhancement in repulsive interactions between charged polymer segments upon deprotonation, leading to an amplified expansion and a significant increment in swelling with respect to their linear analogues of similar molar mass. On the other hand, it is the composition of polyacid grafts that governs their hydration in both undissociated and ionized forms, determining the degree of swelling during their pH-induced transition
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