No abstract

The crystal structure of (1-x)KNbO3-xBiFeO3 (KNBF) and (1-x)KNbO3-LaFeO3 (KNLF) (where x=0.00; 0.01; 0.02; 0.04; 0.08; 0.16; 0.32) was evaluated by XRD and Raman spectroscopy. XRD data show the crystal symmetry to evolve from orthorhombic to tetragonal with increasing x. The optical bandgap was found to narrow systematically with increasing x. Raman spectroscopy analysis corroborated long-range polar order in all compositions. The photoresponse of x=0.32 shows a typical diode-like behaviour, with current and voltage of 0.115 µA and 0.075 V for KNBF and 0.19 µA and 0.035 V for KNLF, respectively. To our knowledge these represent the largest values among KNbO3-based ceramics, making them promising for photovoltaic applications.

No abstract

In recent years was an increasing interest in the use of microalgae for biofuels, especially biodiesel, from previous extraction and subsequent transesterification of fatty acids present in the biomass of cyanobacteria. However, this is a time consuming and expensive process, which presents low productivity. Currently, this method has been successfully replaced by in situ esterification. This approach combines extraction and esterification of lipids in a single step, simplifying the process required for biodiesel production from microalgae biomass. In this work, biodiesel synthesis was performed using as feedstock biomass of cyanobacteria Phormidium sp., Pseudanabaena sp. and mixed culture Synechococcus sp. and Aphanocapsa sp. Biodiesel derivated of cyanobacteria biomass showed 42-51% of satured fatty acids, 33-46% of monounsaturated fatty acids and 4-16% of polyunsaturated fatty acids, proving to be a potentially viable technique for production in larger scales.