Transparent conductive oxides, such as tin dioxide (SnO 2 ), have recently shown to be promising materials for thermoelectric applications. In this work we studied the thermoelectric properties of Fe-, Sb-and Zn-uniformly doping and co-doping SnO 2 , as well as of Sb and Zn planar (or delta)-doped layers in SnO 2 forming oxide superlattices (SLs). Based on the semiclassical Boltzmann transport equations (BTE) in conjunction with ab initio electronic structure calculations, the Seebeck coefficient (S) and figure of merit (ZT) are obtained for these systems, and are compared with available experimental data. The delta doping approach introduces a remarkable modification in the electronic structure of tin dioxide, when compared with the uniform doping, and colossal values for ZT are predicted for the delta-doped oxide SLs. This result is a consequence of the two-dimensional electronic confinement and the strong anisotropy introduced by the doped planes. In comparison with the uniformly doped systems, our predictions reveal a promising use of delta-doped SnO 2 SLs for enhanced S and ZT, which emerge as potential candidates for thermoelectric applications.

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Public playgrounds may be sources of parasite infections. This study analyzed the occurrence of intestinal parasites in playgrounds in the Federal District of Brazil (DF). Seventy sand samples were collected in 14 playgrounds distributed around the DF in 2015-2016 and were processed using the Willis and Hoffman methods. All playgrounds were contaminated with parasites. The parasites identified were Ascaris lumbricoides (33%), Strongyloides sp. (6%), Ancylostomidae (4%), Giardia sp. (4%), Trichuris sp. (3%) Toxocara sp. (3%) and Hymenolepis nana (1%). Results show the potential risk of transmission of parasitic diseases (mainly ascariasis) in playgrounds in central Brazil.