Eco-friendly preparation of electrically conductive chitosan - reduced graphene oxide flexible bionanocomposites for food packaging and biological applications

Electrically conductive materials have been highlighted in the biomedical and food packaging areas. Conventional electrically conductive polymers have limited biodegradability and biocompatibility and should be replaced by suitable biomaterials. Herein, electrically conductive bionanocomposites of chitosan and reduced graphene oxide were produced by a green methodology. The reduced graphene oxide was hydrothermally reduced in the presence of caffeic acid and was dispersed into chitosan. The final bionanocomposites achieved an electrical conductivity of 0.7 S/m in-plane and 2.1 × 10−5 S/m through-plane. The reduced graphene oxide promoted a great enhancement of antioxidant activity and a mechanical reinforcement of chitosan matrix, increasing the tensile strength and decreasing the water solubility. The electrical conductivity, mechanical properties and antioxidant activity of the bionanocomposites can be tuned according to the filler content. These active bionanocomposites, prepared using a green methodology, revealed good electrical and mechanical properties, which make them promising materials for food packaging and biological applications.publishe

The genetic history of the Southern Arc: a bridge between West Asia and Europe

By sequencing 727 ancient individuals from the Southern Arc (Anatolia and its neighbors in Southeastern Europe and West Asia) over 10,000 years, we contextualize its Chalcolithic period and Bronze Age (about 5000 to 1000 BCE), when extensive gene flow entangled it with the Eurasian steppe. Two streams of migration transmitted Caucasus and Anatolian/Levantine ancestry northward, and the Yamnaya pastoralists, formed on the steppe, then spread southward into the Balkans and across the Caucasus into Armenia, where they left numerous patrilineal descendants. Anatolia was transformed by intra–West Asian gene flow, with negligible impact of the later Yamnaya migrations. This contrasts with all other regions where Indo-European languages were spoken, suggesting that the homeland of the Indo-Anatolian language family was in West Asia, with only secondary dispersals of non-Anatolian Indo-Europeans from the steppe

Estimating the Size of the Renewable Energy Generators in an Isolated Solar-Biodiesel Microgrid with Lead-Acid Battery Storage

Climate change, fossil fuel decline, expensive power grid extensions focused the attention of scientist in developing electrical power systems that use as primary resources renewable energy generators. Romania has a high renewable energy potential and presents interest in developing renewable energy microgrids using: solar energy, wind energy, biomass Hydro, etc. The paper presents a method of estimating the size of the renewable energy generators in an isolated solar-biodiesel microgrid with lead-acid battery storage. The mathematical model is first presented and then an algorithm is developed to give an estimation of the size of the microgrid. The microgrid is installed in the region of Oradea, Romania. The results are validated through comparison with existing sizing software programs like: PV*Sol and PVSyst