A theoretical analysis of Sb5+ incorporation in highly doped SnO2 matrix

We have used the periodic quantum-mechanical method with density functional theory at the B3LYP hybrid functional level in order to study the doping of SnO2 with pentavalent Sb5+. The 72-atom 2x3x2 supercell SnO2 (Sn24O48) was employed in the calculations. For the SnO2:4%Sb , one atom of Sn was replaced by one Sb atom. For the SnO2:8%Sb, two atoms of Sn were replaced by two Sb atoms. The Sb doping leads to an enhancement in the electrical conductivity of this material, because these ions substitute Sn4+ in the SnO2 matrix, leading to an electronic density rise in the conduction band, due to the donor-like behavior of the doping atom. This result shows that the bandgap magnitude depends on the doping concentration, because the energy value found for SnO2:4%Sb was 2.8eV whereas for SnO2:8%Sb it was 2.7eV. It was also verified that the difference between the Fermi level and the bottom of the conduction band is directly related to the doping concentration. - See more at: http://www.eurekaselect.com/117255/article#sthash.Z5ezhCQD.dpuf

Interferência Fano antissimétrica assistida por um férmion de Majorana

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Study of stillage biodegradation by respirometry in sandy and clay soils

The stillage, which is a liquid residue from the distillation of the sugarcane ethanolic fermentation, contains organic matter and can be a big source of pollution when it is discarded in the wrong way. Its application as fertilizer has been extended, which is reason to cause concerns regarding the environment. The aim of this work was to evaluate and quantify the biodegradation of stillage in sandy and clay soils, besides verifying the efficiency of the Embiotic Line®inoculum as an accelerator of the biodegradation. Bartha and Pramer respirometric technique was used to determine the production of CO2 during the 50 days of the biodegradation process, and the quantification of the initial and final microorganisms was also conducted. Results were analyzed using the Friedman statistical test. Clay soils were significantly better on stillage decomposition when compared to sandy soils (p=0.0153). Clay soils presented greater efficiency in stillage biodegradation, with higher field capacity, better water, organic matter and microbial retention. Regarding the use of the embiotic line, the experiment has shown this product does not interfere positively in the stillage biodegradation for both soils, possibly needing adjustments in its composition.