Harnessing biopolyesters in the design of functional materials for biomedical applications

The present contribution illustrates the versatility of poly(3-hydroxyalkanoate)s (PHAs) in the design of a wide variety of biodegradable and/or biocompatible macromolecular architectures with controlled degradability. Firstly, functionalized PHAs were prepared from unsaturated PHAs. Pendant double bonds have been turned into carboxyl, hydroxyl, alkyne or epoxy groups. These reactive functions were used for further grafting hydrolyzable polylactide (PLA) or poly(ε-caprolactone) (PCL) as well as hydrophilic poly(ethylene glycol) (PEG). Additionally, block copolymers with a PLA, PCL or PEG segment have been prepared by ring-opening polymerization or "click" chemistry from a PHA oligomeric macroinitiator. Functional PHAs represent biodegradable aliphatic polyesters with many possibilities to tune physico-chemical characteristics, such as hydrophilicity and degradation rate, thus making the resulting materials suitable as devices for drug delivery or as scaffolds for tissue engineering. Herein, we address the recent trends in the synthesis of these polymeric materials and their applications in controlled drug delivery and tissue engineering

ATV GNC flight performance and lessons learned

ESA’s fifth and final Automated Transfer Vehicle (ATV), Georges Lemaître, performed its fully automated rendezvous and docking with the International Space Station (ISS) on August 12, 2014. The ATV’s navigation sensors have shown their worth docking the 20-ton vehicles with aft port of the Space Station, manoeuvring into position and docking with an excellent accuracy. For the second consecutive time after ATV-4, the accuracy at docking was such that the ATV probe head was directly captured inside the Zvezda docking mechanism without contact with the receiving cone. From 30 km and down to a distance of 250 m, ATV uses GPS (Global Positioning System) information from its own receiver and the Station’s that is transmitted over a radiofrequency link. As it moves closer, ATV switches to laser navigation, using the reflection of laser pulses on reflectors mounted on the Space Station. This paper presents the achievements and performance of ATV GNC (Guidance, Navigation, and Control) across the 5 missions for both types of navigation. It will also discuss the observations made during the various flights regarding unforeseen conditions such as space environment or target pattern contamination having a potential impact on performance and how they were resolved

On the existence of chaos in jerky flow

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