1,720,964 research outputs found
Functional hydrogels with a multicatalytic activity for bioremediation: Single-step preparation and characterization
No full textIn a single-step free radical reaction, multicatalytic hydrogels were synthesized by covalent immobilization of Pancreatin onto a film composed of Acrylamide and Polyethylene glycol dimethacrylate750. Hydrogels were characterized by determination of their dynamic swelling ratios and each catalytic activity was extensively investigated by determination of kinetic parameters KM and Vmax. The immobilization process was found to preserve the hydrolytic properties of Pancreatin (Protease, Lipase, and Amylase catalytic activities). Catalytic efficiencies were the highest with Protease and the lowest with Amylase. Reusability values higher than 60% after 10 repeated cycles proved the applicability of the proposed material in industrial practice
Cotton gauze-hydrogel composites: Valuable tools for electrically modulated drug delivery
No full textCotton gauze was inserted into a hydrogel network composed of acrylamide, sodium methacrylate, and polyethylene glycol dimethacrylate to fabricate an electroresponsive delivery system for wound dressing. The composite was characterized by swelling measurements, showing that shrinking or swelling depend on the applied voltage. The release profile of incorporated diclofenac sodium salt shows the possibility to modulate the kinetics by changes in the amplitude and duration of applied electric pulses. Mathematical models allow a characterization of release profiles, which are slower when an external voltage of 6, 12, and 18 V is applied, and faster at 24 V
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
Recent advances in the synthesis and biomedical applications of nanocomposite hydrogels
No full textHydrogels sensitive to electric current are usually made of polyelectrolytes and undergo erosion, swelling, de-swelling or bending in the presence of an applied electric field. The electrical conductivity of many polymeric materials used for the fabrication of biomedical devices is not high enough to achieve an effective modulation of the functional properties, and thus, the incorporation of conducting materials (e.g., carbon nanotubes and nanographene oxide) was proposed as a valuable approach to overcome this limitation. By coupling the biological and chemical features of both natural and synthetic polymers with the favourable properties of carbon nanostructures (e.g., cellular uptake, electromagnetic and magnetic behaviour), it is possible to produce highly versatile and effective nanocomposite materials. In the present review, the recent advances in the synthesis and biomedical applications of electro-responsive nanocomposite hydrogels are discussed
Carbon nanotubes hybrid hydrogels for electrically tunable release of Curcumin
No full textElectro-responsive hybrid hydrogels were synthesized by free radical polymerization using Gelatin-coated multi-walled carbon nanotubes as electro-conductive component, acrylamide and polyethylene glycol dimethacrylate as plasticizing and crosslinking monomer, respectively. Dynamic light scattering, Raman spectroscopy, scanning electron microscopy, resistivity measurement, cell viability assay, and evaluation of swelling degree upon application of an external voltage at 0, 12, 24, 36, and 48 V were performed as characterization tools. Composite materials were found to be highly versatile in modulating the drug delivery of neutral drugs (e.g. Curcumin) as a function of both nanotube content and voltage magnitude, with drug partition between carrier and releasing media being dependent on the balance between electrostatic attractive and repulsive forces and hydrogel swelling degree. Finally, suitable mathematical modelling were employed for the kinetic characterization of the release mechanism. The results allowed hypothesizing the use of hybrid for different therapeutic needs in wound healing treatment
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