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    Novel polyurethane-based thermosensitive hydrogels as drug release and tissue engineering platforms: Design and in vitro characterization

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    Poloxamer P407 (P407) is a Food and Drug Administration approved triblock copolymer; its hydrogels show fast dissolution in aqueous environment and weak mechanical strength, limiting their in vivo application. In this work, an amphiphilic poly(ether urethane) (NHP407) was synthesized from P407, an aliphatic diisocyanate (1,6-hexanediisocyanate) and an amino acid derived diol (N-Boc serinol). NHP407 solutions in water-based media were able to form biocompatible injectable thermosensitive hydrogels with a lower critical gelation temperature behavior, having lower critical gelation concentration (6% w/v versus 18% w/v), superior gel strength (G′ at 37 °C about 40 000 Pa versus 10 000 Pa), faster gelation kinetics (<5 min versus 15-30 min) and higher stability in physiological conditions (28 days versus 5 days) compared to P407 hydrogels. Gel strength and PBS absorption at 37 °C increased whereas dissolution rate (in phosphate-buffered saline (PBS) at 37 °C) and permeability to nutrients (studied using fluorescein isothiocyanate-dextran model molecule) decreased as a function of NHP407 hydrogel concentration from 10% to 20% w/v. By varying the concentration, NHP407 hydrogels were thus prepared with different properties which could suit specific applications, such as in situ drug/cell delivery or bioprinting of scaffolds. Moreover, deprotected amino groups in NHP407 could be exploited for the grafting of bioactive molecules obtaining biomimetic hydrogel

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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
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