1,721,003 research outputs found
A versatile and highly efficient catalyst system for the ring-opening polymerization of lactones
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A microfluidic device for monitoring siRNA delivery under fluid flow
Get PDFWhen studying particle uptake in vitro, it is favorable to mimic the in vivo situation as much as possible. In this study we present a microfluidic device to mimic the mechanical stress caused by the flow of blood while studying particle uptake in vitro. Human endothelial cells were treated with liposomes containing fluorescent siRNA. It was found that applying physiologically relevant mechanical stress during transfection diminishes the uptake of liposomes in the cells
Biodegradable polymersomes for targeted ultrasound imaging
Get PDFBiodegradable polymersomes with a sub-micron size were prepared by using poly(ethylene glycol)–polylactide (PEG–PDLLA) block-copolymers in aqueous media. Air-encapsulated polymersomes could be obtained by a lyophilization/rehydration procedure. Preliminary results showed that these polymersomes were acoustically active
PEG-PLLA and PEG-PDLA multiblock copolymers: synthesis and in situ hydrogel formation by stereocomplexation
Get PDFWater-soluble PEG–PLLA and PEG–PDLA multiblock copolymers were synthesized and investigated for in situ hydrogel formation by stereocomplexation between the PLLA and PDLA blocks. The critical gel concentration measurements showed that these multiblock copolymers are able to form stereocomplexed hydrogels at a much lower concentration in water than the parent triblock copolymers. Furthermore, rheology studies showed significantly improved mechanical properties of the multiblock copolymer stereocomplexed hydrogels compared to the triblock copolymer hydrogels, obtained under otherwise same conditions
Protein release from injectable stereocomplexed hydrogels based on PEG-PDLA and PEG-PLLA star block copolymers
Get PDFThe release of two model proteins, lysozyme and immunoglobulin G (IgG) from injectable, fast gelling, biodegradable hydrogels composed of PEG–PLLA and PEG–PDLA star block copolymers was investigated. Lysozyme was quantitatively released in 10 days. The release of IgG was slower and after 20 days 40–60% was released depending on the composition of the gel
Fast in-situ formation of dextran-tyramine hydrogels for in vitro chondrocyte culturing
Get PDFDextran hydrogels were formed in situ by enzymatic crosslinking of dextran-tyramine conjugates (dex-TA)s using horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). Depending on the molecular weight (Mn) of dextran and the degree of substitution (DS) of dextran with tyramine groups, the gelation time varied from about 20 s to a few minutes. Hydrogels prepared from dex-TA (Mn = 3.1 × 104 g/mol) with a DS of 10 had storage moduli up to 60 kPa. Moreover, hydrogels in which chondrocytes were encapsulated had moduli comparable to those without cells. The H2O2/TA mole ratio applied for the preparation of the hydrogels influenced the cell viability of chondrocytes cultured in the hydrogels. A live-dead assay revealed that almost all chondrocytes retained their viability when cultured in hydrogels prepared with a relatively low H2O2/TA molar ratio of 0.2. Histological analysis showed that the encapsulated chondrocytes are capable of maintaining their phenotype as confirmed by the round shape of the cells and production of proteoglycans up to 3 weeks
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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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