1,721,104 research outputs found
Use of Spanish Broom (Spartium junceum L.) Fibers for Removal of Heavy Metal Ions from Aqueous Solutions
No full textIn this work, potential use of Spanish broom fibers for removing from aqueous solutions heavy metal ions such as copper Cu(II) and lead Pb(II) was investigated. The fibers were extracted by DiCoDe (Digestion-Compression-Decompression) process changing experimental conditions. Morphology of fibers was evaluated by scanning electron microscopy and chemical composition, as well as the carboxylic group content, was determined by conventional methods. Various initial concentrations of heavy metal ions were studied to explore potential sorption on cellulose fibers. The results suggest that cellulose fibers, extracted by different conditions of DiCoDe process, are capable of sorbing metal ions
Bilayered buccal films as child-appropriate dosage form for systemic administration of propranolol
Full text linkBuccal mucosa has emerged as an attractive site for systemic administration of drug in paediatric patients. This route is simple and non-invasive, even if the saliva wash-out effect and the relative permeability of the mucosa can reduce drug absorption. Mucoadhesive polymers represent a common employed strategy to increase the contact time of the formulation at the application site and to improve drug absorption. Among the different mucoadhesive dosage forms, buccal films are particularly addressed for paediatric population since they are thin, adaptable to the mucosal surface and able to offer an exact and flexible dose. The objective of the present study was to develop bilayered buccal films for the release of propranolol hydrochloride. A primary polymeric layer was prepared by casting and drying of solutions of film-forming polymers, such as polyvinylpyrrolidone (PVP) or polyvinylalcohol (PVA), added with different weight ratios of gelatin (GEL) or chitosan (CH). In order to achieve unidirectional drug delivery towards buccal mucosa, a secondary ethylcellulose layer was applied onto the primary layer. Bilayered films were characterized for their physico-chemical (morphology, thickness, drug content and solid state) and functional (water uptake, mucoadhesion, drug release and permeation) properties. The inclusion of CH into PVP and PVA primary layer provided the best mucoadhesion ability. Films containing CH provided a lower drug release with respect to films containing GEL and increased the amount of permeated drug through buccal mucosa, thanks to its ability of interfering with the lipid organization. The secondary ethylcellulose layer did not interfere with drug permeation, but it could limit drug release in the buccal cavity
Mucoadhesive Buccal Tablets Based on Chitosan/Gelatin Microparticles for Delivery of Propranolol Hydrochloride
No full textPropranolol administration through buccal route offers some distinct advantages thanks to the easy access to the oral mucosa, fast onset of action, and avoidance of hepatic and intestinal degradation mechanisms. To overcome the effective removal existing in the buccal cavity, mucoadhesive delivery systems are considered a promising approach as they facilitate a close contact with the buccal mucosa. The aim of this study was to prepare mucoadhesive tablets based on chitosan/gelatin microparticles for buccal delivery of propranolol hydrochloride. Spray-dried microparticles were prepared with different chitosan-gelatin weight ratios and characterized in terms of yield and morphology. Microparticles were subsequently compressed with the drug to obtain loaded buccal tablets. In vitro water uptake, mucoadhesion, release, and permeation tests were performed to investigate tablet ability to hydrate, to adhere to the mucosa, and to deliver drug through buccal mucosa. Microparticles showed a different morphology based on the different chitosan-gelatin weight ratios. Moreover, buccal tablets based on the prepared microparticles showed different technological and functional characteristics in virtue of their composition. In particular, tablets with an excess of chitosan showed the best mucoadhesive properties, allowed the permeation of the greatest drug amount among all formulations, and could be promising for buccal administration of propranolol hydrochloride. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci
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
Chitosan nanoparticles for lipophilic anticancer drug delivery: Development, characterization and in vitro studies on HT29 cancer cells
No full textThe aim of this study was to develop chitosan-based nanoparticles that could encapsulate lipophilic molecules and deliver them to cancer cells. Nanoparticles were prepared with different molar ratios of chitosan, hyaluronic acid and sulphobutyl-ether-β-cyclodextrin and with or without curcumin. The nanosystems were characterized in terms of their size, zeta potential, morphology, encapsulation efficiency and stability in different media. Intestinal epithelial and colorectal cancer cells were treated with unloaded nanoparticles in order to study their effect on cellular membrane organization and ROS production. Finally, in vitro assays on both cellular lines were performed in order to evaluate the ability of nanoparticles to promote curcumin internalization and to study their effect on cell proliferation and cell cycle. Results show that nanoparticles were positively charged and their size increased with the increasing amounts of the anionic excipient. Nanoparticles showed good encapsulation efficiency and stability in water. Unloaded nanoparticles led to a change in lipid organization in the cellular membrane of both cell lines, without inducing ROS generation. Confocal microscopy, cell proliferation and cell cycle studies allowed the selection of the best formulation to limit curcumin cytotoxicity in normal intestinal epithelial cells and to reduce cancer cell proliferation. The latter was the result of the increase of expression for genes involved in apoptosis
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
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