1,720,987 research outputs found
Mechanics and drug release from poroviscoelastic hydrogels: Experiments and modeling
No full textHydrogels are peculiar soft materials formed by a 3D polymeric network surrounded by water molecules. In these systems the mechanical and the chemical energy are well balanced and an applied external stimulus (mechanical or chemical) can cause a distinctive response, where the contributions of the mechanics and the mass transport are combined to form a “poroviscoelastic” behavior. In this work the poroviscoelastic behavior of the agarose gels has been investigated, from the experimental and modeling points of view, by applications of external mechanical stimuli. The pure gel, brought in the non-equilibrium condition, showed that the combined effect of mechanical viscoelasticity and water transport were essential to reach the new equilibrium condition. Furthermore, the agarose gel loaded with a model drug, theophylline, showed that the mechanical stimulus can enhance the drug release from the system by stretching the polymeric chains, modifying the mesh size and therefore the drug diffusion coefficient
Drug delivery of siRNA therapeutics
No full textThis Special Issue of Pharmaceutics titled “Drug Delivery of siRNA Therapeutics” aims to present
the state of the art of siRNA delivery, embracing investigation strategies of international research
groups with different experiences and skills. The Special Issue will thus be devoted to presenting
the current connections between experimental and in silico approaches for therapies based on siRNA
delivery, accounting for all the most promising techniques based on liposomes, polymeric and inorganic
nanoparticles, aptamers, chemical modification of siRNAs, and so on
Swelling Behavior of Anionic Hydrogels: Experiments and Modeling
Full text linkPolyelectrolyte hydrogels are smart materials whose swelling behavior is governed by ionizable groups on their polymeric chains, making them sensitive to pH and ionic strength. This study combined experiments and modeling to characterize anionic hydrogels. Mechanical tests and gravimetric analyses were performed to track hydrogel mass over time and at a steady state under varying pH and salt concentrations. The swelling ratio exhibited a bell-shaped curve with pH, reaching 120 in pure water, and decreased with increasing salt concentrations. Transient regimes showed slower swelling (similar to 40 h) under pH stimulation compared to faster deswelling (similar to 20 h) induced by salt. A fully coupled model integrating mass transport and solid mechanics was developed, with solvent diffusivity as the sole adjustable parameter in transient simulations. In conclusion, this study combined experiments and modeling to uncover complex mechanisms in PE behavior under two external stimuli, providing insights essential for designing advanced hydrogels
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
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