1,721,145 research outputs found
Multi applicable stereocomplex PLA particles decorated with cyclodextrins
No full textIn this work, an innovative approach to covalently anchor cyclodextrins (CDs) on the surface of submicrometric particles, prepared from an equimolar mixture of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), was developed. The idea of the applied method lays in the potential reactivity of amino CDs towards the polymer functionalities to produce an aminolysis reaction, which should lead to the direct grafting of cyclodextrin molecules on the polymer surface. A preliminary investigation demonstrated the significant capacity of the modified particles to adsorb a model pollutant (alizarin red) and a hydrophobic drug (ketoprofen)
Enzymatic degradation of chitosan scaffold supporting 3D neuronal networks
No full textThe degradation of cell seeded 3D scaffolds is an important step both for the in vivo and in vitro use of biomimetic matrices mimicking the extracellular matrix. In this respect, we investigated the possibility of enzymatically degrading a chitosan microbeads scaffold supporting a mature 3D neuronal network. To this purpose, the enzymes chitosanase and β-glycosidase were used. As a first step, their impact on the development of a mature 2D neuronal and their degradative action on chitosan microbeads were evaluated. Then, the degradation protocol was used to treat chitosan microbeads supporting a 3D neuronal network. It was observed that the degradation was slowed down by the presence of the cells. Finally, the electrophysiological activity of 3D neuronal networks before and after the scaffold degradation was found to be not modified
On an effective approach to improve the properties and the drug release of chitosan-based microparticles
No full textThe work investigated the possibility to develop an easy scalable treatment capable of modifying only the surface of chitosan-based materials, limiting the degradation of the bulk and the burst release of a drug, without compromising the properties of the polymeric matrix. To this aim, microparticles of CHI were superficially coated with poly-(styrene-co-maleic anhydride) (PSMA), taking advantage of the potential reactivity of chitosan amino groups and maleic functionalities of PSMA. The specific reactions/interactions occurring between the two polymers were studied by IR measurements, while FE-SEM analysis evidenced the modification of the morphology of the particles contacted with PSMA. Contact angle measurements demonstrated the change of wettability in the modified systems and TGA analysis allowed to estimate the amount of the deposited PSMA. The above treatment turned out to improve the particle stability both in an acidic environment and in an enzymatic system. The release properties of the treated and of the untreated particles, over a period of 10 h, were tested using, as model drug, the protein Bovine Serum Albumin (BSA). Finally, the cytocompatibility of the developed composite microparticles was assessed on MCF-7 human breast cancer cells, which measurements demonstrated the non-toxicity of the treatment
Analysis of nestin protein in the aqueous humor as biomarker of open angle glaucoma
No full textPrimary open angle glaucoma (POAG) is a progressive optic nerve degeneration, leading to irreversible visual damage. Alterations of the aqueous humor (AH), the biological fluid filling both the anterior and the posterior chambers of the eye, play a pathogenic role in POAG. AH protein composition is altered during glaucoma progression. Nestin protein was found to be differentially expressed in the AH of glaucomatous patients compared to unaffected matched controls. Methods: Nestin was analyzed by an open quartz crystal microbalance (QCM) in the AH of 21 glaucomatous patients compared to nine unaffected controls. The surface of the electrode used in the QCM was coated with an analyte-specific recognition layer. Results: Positive nestin values were recorded in the AH collected from POAG patients; negative values of nestin detection were obtained by analyzing the AH collected from non-POAG glaucomatous patients and unaffected controls. Conclusion: The present study proposes and validates a new clinically applicable approach to analyze biological markers in AH for POAG diagnosis
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
Playing Against Nature: Risk Averse Behaviour of Physarum Polycephalum
No full textThe computational capabilities of the plasmodium of the slime mould Physarum polycephalum were first reported in 2001. Specifically, the ability of this organism to find the minimum-length path between two points in a labyrinth was demonstrated. This Physarum's ability has been attributed to chemo-attraction to food. More recently, it has been observed that slime moulds can choose conditions most amenable to their survival. Here we show how Physarum develops its route to food under a risk averse behaviour, as a game against nature, which means also choosing paths that are not the shortest ones
- …
