Fábio Lopes

Thickness Measurement of V2O5 Nanometric Thin Films Using a Portable XRF

Nanometric thin films have always been chiefly used for decoration; however they are now being widely used as the basis of high technology. Among the various physical qualities that characterize them, the thickness strongly influences their properties. Thus, a new procedure is hereby proposed and developed for determining the thickness of V2O5 nanometric thin films deposited on the glass surface using Portable X-Ray Fluorescence (PXRF) equipment and the attenuation of the radiation intensity Kα of calcium present in the glass. It is shown through the present paper that the radiation intensity of calcium Kα rays is proportional to film thickness in nanometric films of vanadium deposited on the glass surface.

Thickness Effect on the Optical Band Gap of V2O5 Thin Films Deposited by Thermal Evaporation

Thin V2O5 films have been used as a passive electrode to be applied in some electrochromic devices that requires particular optical, crystallographic and electrochemical energy properties. These properties are greatly influenced by the film thickness. In this work were determined the thickness dependence on, spectral optical absorption and particle size of the V2O5 thin films deposited by thermal evaporation in three nanoscale thickness. It is clear from the results that these particles size apparently are not influenced by the thickness of the film in its formation. Thus, it was verified that the microstructure, mainly the thickness, strongly influences the optical properties, especially the absorption energy, of these samples. The optical gap energy decrease as the film thickness increased. This actually proves that film thickness can be used as a way to modulate the materials optical absorption in optical and optoelectronic devices.

Investigating a Rock Art Site in Paraná State, South of Brazil

Jaguariaiva 1 is a sandstone rockshelter located in Jaguariaiva, Parana State, Brazil, with rock art on the surface of the walls and ceiling. A stratigraphic analysis of the soil within the shelter showed six occupational layers and a superficial disturbed layer with evidence from the end of the 19th century. The establishment of a rock-art chronology became possible using fallen painted rock sections incorporated into three sedimentary levels underlying this rock shelter. These show superimpositions of several pictures of differently sized animals, such as deer, and lattice motifs, which are generally associated with the Planalto rock art tradition. The chronological study was performed based on radiocarbon ( 14 C) analysis of charcoal collected from six excavated subsurface archaeological contexts. The two oldest layers, associated with hunters and gatherers of the Umbu tradition, were dated to 7680–7516 cal BP and 6913–6656 cal BP. There are four occupational layers from ceramists and farmers related to the south Je linguistic family, and linked to the Itarare-Taquara archaeological tradition: layer 3 linked to the oldest of such occupation, dated to 3058–2796 cal BP, followed by layer 4, dated to 2080–1701 cal BP. Layers 5 and 6, dated to 1995–1526 cal BP and 540–152 cal BP, respectively.

Preliminary analysis of Brazilian archaeological ceramics by non‐destructive analytical technique

Portable System of Energy Dispersive X‐ray Fluorescence was used to analyze of pre‐colonial pottery from northeast of Brazil. In 43 pottery fragments there is a different treatment on the faces in relation to the ceramic paste. The results of two‐dimensional graphs and cluster analyses show the formation of five groups of fragments. This result indicates that the fragments analyzed were manufactured with clay from five different origins. It was possible to observe elements K, Ca, Ti, Mn, Fe, Zn, Br, Rb, Sr, Y, Zr and Pb in the analyzed fragments.

Mussel Shell Evaluation as Bioindicator For Heavy Metals

Recently, in Brazil, it has appeared a new and unusual “plague” in lazer and commercial fishing. It is caused by the parasitic larval phase of certain native bivalve mollusks of fresh water known as “Naiades” and its involves the presence of big bivalve of fresh water, mainly Anodontites trapesialis, in the tanks and dams of the fish creation. These bivalve mollusks belong to the Unionoida Order, Mycetopodidae Family. The objective of the present work was to analyze the shells of these mollusks to verify the possibility of use as bioindicators for heavy metals in freshwater. The mollusks shells were collected in a commercial fishing at Londrina‐PR. A qualitative analysis was made to determine the chemical composition of the shells and verify a possible correlation with existent heavy metals in the aquatic environment. In the inner part of the shells were identified the elements Ca, P, Fe, Mn and Sr and in the outer part were identified Ca, P, Fe, Mn, Sr and Cu. The Ca ratio of the outer part by inner part...