Morphology, Thermo-Mechanical Properties and Biodegradibility of PCL/PLA Blends Reactively Compatibilized by Different Organic Peroxides

Reactive blending is a promising approach for the sustainable development of bio-based polymer blends and composites, which currently is gaining more and more attention. In this paper, biodegradable blends based on poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) were prepared via reactive blending performed in an internal mixer. The PCL and PLA content varied in a ratio of 70/30 and 55/45. Reactive modification of PCL/PLA via liquid organic peroxides (OP) including 0.5 wt.% of tert-butyl cumyl peroxide (BU), 2,5-dimethyl-2,5-di-(tert-butylperoxy)-hexane (HX), and tert-butyl peroxybenzoate (PB) is reported. The materials were characterized by rotational rheometer, atomic force microscopy (AFM), thermogravimetry (TGA), differential scanning calorimetry (DSC), tensile tests and biodegradability tests. It was found that the application of peroxides improves the miscibility between PCL and PLA resulted in enhanced mechanical properties and more uniform morphology. Moreover, it was observed that the biodegradation rate of PCL/PLA blends reactively compatibilized was lower comparing to unmodified samples and strongly dependent on the blend ratio and peroxide structure. The presented results confirmed that reactive blending supported by organic peroxide is a promising approach for tailoring novel biodegradable polymeric systems with controllable biodegradation rates.

Leveraging circuit theory and nonlinear dynamics for the efficiency improvement of energy harvesting

We study the performance of vibrational energy harvesting systems with piezoelectric and magnetic inductive transducers, assuming the power of external disturbance concentrated around a specific frequency. Both linear and nonlinear harvester models are considered. We use circuit theory and equivalent circuits to show that a large improvement in both the harvested energy and the power efficiency is obtained, for linear systems, through a proper reactive modification of the load. For nonlinear systems, we use methods of nonlinear dynamics to derive analytical formulae for the output voltage, the harvested energy and the power efficiency. We show that also for the nonlinear case, the modified load significantly boosts the performance.

Ibuprofen, a Potential Cause of Acute Hemorrhagic Gastritis in Children - A Case Report

Introduction: Upper gastrointestinal bleeding is an uncommon but possible life-threatening entity in children, frequently caused by erosive gastritis. Non-steroidal anti-inflammatory drugs are one of the most common class of drugs which can cause gastrointestinal complications, including hemorrhagic gastritis. Case report: The case of a 6-year-old male, admitted for hematemesis, abdominal pain and loss of appetite. It was ascertained at the time of admission, that ibuprofen had been prescribed as the patient had a fever. This was inappropriately administered as the mother did not respect the intervals between the doses. Initial laboratory tests revealed neutrophilia, leukopenia, high levels of lactate dehydrogenase and urea. An upper digestive endoscopy revealed an increased friability of the mucosa, digested blood in the gastric corpus and fornix. No active bleeding site was detected. The histopathological examination described a reactive modification of the corporeal gastric mucosa. Intravenous treatment with proton pump inhibitors and fluid replacement were initiated, with favorable results. Conclusion: Ibuprofen can lead to upper digestive hemorrhage independently of the administered dose. Parents should avoid administering Ibuprofen for fever suppression without consulting their pediatrician.