1,721,063 research outputs found
Iron vs Aluminum Based Layered Double Hydroxides as Water Splitting Catalysts
No full textThis paper describes the electrosynthesis, characterization and electrocatalytic properties towards oxygen evolution reaction (OER) of four layered double hydroxides (LDHs) containing cobalt or nickel as divalent cation and aluminum or iron as trivalent metal. The electrochemical behaviour of the LDH modified electrodes was studied by cyclic voltammetry (CV), and the LDHs were characterized by XRD and SEM/EDS. Two materials, i.e.; platinum and glassy carbon (GC), were investigated as electrode supports recording polarization and chronopotentiometric curves, with a rotating disk electrode in alkaline solutions. LDHs containing iron exhibited higher activity for OER and all the materials showed a good stability and durability in alkaline media. When GC was used as electrode support the performances of the OER catalysts resulted to be even better than those exhibited by the same LDHs electrodeposited on Pt
Temperature dependence of the rigid amorphous fraction of poly(butylene succinate)
No full textIn this contribution the temperature evolution of the constrained or rigid amorphous fraction (RAF) of biodegradable and biocompatible poly(butylene succinate) (PBS) was quantified, after detailed thermodynamic characterization by differential scanning calorimetry and X-ray diffraction analysis. At the glass transition temperature, around −40 °C, the rigid amorphous fraction in PBS is about 0.25. It decreases with increasing temperature and becomes zero in proximity of 25 °C. Thus, at room temperature and at the human body temperature, all the amorphous fraction is mobile. This information is important for the development of PBS products for various applications, including biomedical applications, since physical properties of the rigid amorphous fraction, for example mechanical and permeability properties, are different from those of the mobile amorphous fraction
New elastomeric biocompatible PLLA-based triblock copolymers for vascular tissue engineering applications
No full textReactive blending of poly(propylene 2,5-furandicarboxylate) and poly(propylene cyclohexanedicarboxylate). Bio-based multiblock copolymers for food packaging applications
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Bio-based poly(propylene 2,5-furandicarboxylate/cyclohexanedicarboxylate) multiblock copolymers for food packaging applications
No full textNovel biodegradable aliphatic copolyesters based on poly(butylene succinate) containing thioether-linkages for sustainable food packaging applications
No full textPoly(butylene succinate) (PBS) based random copolyesters containing thioether-linkages were synthesized by melt polycondensation, and characterized from the molecular and thermo-mechanical point of view. Permeability to O2 and CO2 gases and biodegradation rate in compost have been also evaluated. The synthesized semicrystalline copolymers have proved to be thermally stable and characterized by PBS crystal phase. The main effect of copolymerization was a lowering in the crystallinity degree and a decrease of Tm with respect to homopolymer. The dependence of Tm on composition was described by Baur's equation. Slightly different surface hydrophilicity has been also displayed. Mechanical properties and the biodegradation rate turned out to be deeply influenced by the copolymers composition, in particular the higher the thiodiethylene glycol mol% the higher the elongation at break and the biodegradation extent. It is worth mentioning that the synthesized copolymers displayed better barrier properties to both studied gases with respect to commercial Poly(lactic acid)
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
New nano and microparticles from PLLA-based triblock copolymers for controlled drug release
No full textVariations 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
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