1,720,999 research outputs found
Production of PEGylated nanocapsules through solvent-displacement in confined impinging jets mixers
No full textThe growth of importance of nanocapsules (and other particulate systems) in different fields requires fast and reproducible methods for their production. Confined impinging jet mixers were successfully used for the production of nanospheres and are now tested for the first time for the production of nanocapsules. This work focuses on the understanding of formation mechanisms and on the quantification of the effect of the most important operating parameters involved in their production. Solvent displacement is employed here for the assembly of the nanocapsules by using a PEGylated derivative of cyanoacrylate as copolymer. A comparison with nanospheres obtained under the same operating conditions is also reported. Results show that the oil-to-copolymer mass ratio (MR) is the main factor affecting the final size distribution and that small nanocapsules are obtained only at low oil-to-copolymer MR. The effect of mixing is significant, proving that mixing of solvent and antisolvent also affects the final size distribution; this depends mainly on the inlet jet velocity, but the size of the mixer is also important. The Reynolds number may be useful to take this into account for geometrically similar systems. Quenching by dilution allows to stabilize the nanocapsules, evidencing the role of aggregation and ripening
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
Paclitaxel and pegylated liposomal doxorubicin in recurrent head and neck cancer: clinical and unexpected pharmacokinetic interactions
No full textBACKGROUND:
The combination of paclitaxel (PTX) with pegylated liposomal doxorubicin (PLD) is an interesting treatment for recurrent head and neck cancer. The pharmacokinetic behavior may depend on the interval between the intravenous administration of the two drugs. This study evaluates the clinical efficacy, toxicity and any possible interval-dependent pharmacokinetic interactions.
PATIENTS AND METHODS:
Thirty patients were randomized to receive 80 mg/m2 PTX weekly and 12.5 mg/m2 PLD every two weeks at administration intervals of 0, 1, 3, 12 or 24 hours. Blood sampling was performed at day 1 and 15 and pharmacokinetics of PTX, PLD and Cremophor EL were evaluated by non-compartmental analysis.
RESULTS:
Neutropenia was the most frequent side-effect (100% of patients; 30% grade 3-4). Hand-foot syndrome was severe in only 3% of patients. Overall response rate was 30%, with 3% complete responses and 27% partial responses. Stable disease and progression were 43% and 27%, respectively. Median response duration and overall median survival were 5.5 and 10 months respectively. Co-administration of PLD markedly reduced Cmax and the area under the curve (AUC), and increased PTX clearance. The differences in the PTX AUC and clearance between the 0 h and the 24 h experimental arms were statistically significant.
CONCLUSION:
The PTX/PLD combination plays a palliative role (clinical benefit in 73% of patients) and has good tolerability. The PTX pharmacokinetic profile was unexpectedly affected by different administration time intervals; in the 0 h arm the AUC was reduced to one fourth, therefore a schedule with PTX on day one, PLD on day two may be preferred
Effect of mixing in the preparation of doxorubicin-loaded cyanoacrylate nanoparticles via solvent displacement
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