Sao Paulo State University

About: Sao Paulo State University is a education organization based out in São Paulo, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 55715 authors who have published 100436 publications receiving 1375332 citations.

Luminescent solar concentrators: challenges for lanthanide-based organic–inorganic hybrid materials

Abstract: Luminescent solar concentrators (LSCs) are devices comprising a transparent matrix embedding optically active centres that absorb the incident radiation, which is re-emitted at a specific wavelength and transferred by total internal reflection to photovoltaic (PV) cells located at the edges of the matrix. Organic–inorganic hybrids incarcerating trivalent lanthanide ions (Ln3+) are a very promising class of materials for addressing the required challenges in the LSC design to improve solar energy harvesting and, then, PV energy conversion. This feature article offers a general overview of the potential of down-shifting-based Ln3+-containing organic–inorganic hybrids for the development of the area with special focus on (i) optically active layer design, (ii) energy conversion mechanisms, (iii) performance and geometry and (iv) figures of merit in PV cell enhancement. Finally, a prospective outlook on future progress, e.g. optically active centre alignment, geometry optimization and building integration, is provided. The use of Ln3+-containing hybrids in LSCs is at an infant initial research step and considerable basic knowledge is still needed to enable prototypes to become a commercial reality.

Sistemas de colheita e manejo da palhada de cana-de-açúcar

Abstract: The use of sugarcane harvesting without residue burning is a common harvesting management in Brazil. The objective of this work was to evaluate the effect of harvest systems and management of sugarcane with and without trash incorporation and of burned sugarcane on soil physical attributes as on production of stems in a Red Yellow Latosol (Typic Hapludox). The treatments can be described as sugarcane (Saccharum officinarum) with burning and manual cutting; sugarcane without burning and automated cutting, with incorporation of chopped residue down to 0.30 m; sugarcane without burning and automated cutting, without incorporation of chopped residue. The particle size distribution, soil organic matter, aggregate stability, bulk density and soil porosity in 0.0-0.1, 0.1-0.2 and 0.2-0.3 m depths were determined as well as soil resistance to penetration and soil moisture in 0.0-0.1, 0.1-0.2, 0.2-0.3 and 0.3-0.4 m depths. The systems sugarcane without burning and sugarcane with residue incorporation revealed the highest stalk production and higher values of organic matter, aggregate stability, macroporosity, water content and smaller values of soil resistance to penetration and bulk density of soil, compared to sugarcane system without incorporation of residue and burned sugarcane.

Role of CuO in the modification of the photocatalytic water splitting behavior of TiO2 nanotube thin films

Abstract: The role of CuO nanoparticles decorating TiO 2 nanotubes (TNT) thin film photoanodes in the behavior of photo-electrocatalytic (PEC) cells for water splitting reaction is investigated. CuO is present mainly as small nanoparticles of few nanometer decorating the internal walls of the TiO 2 nanotubes. Their presence improves i) the photocurrent behavior, ii) the H 2 generation rate by water splitting in a full PEC device (without application of a bias) and iii) the solar-to-hydrogen ( STH ) efficiency. The increase is about 20% with respect to parent TNT photoanodes using open spectrum light from a solar simulator and about 50% increase using AM 1.5G filtered light from a solar simulator. An STH efficiency over 2% in the full PEC cell is observed in the best conditions. IPCE (incident photon to current conversion efficiency) measurements clearly evidence that the presence of CuO nanoparticles induce an enhanced IPCE in the 300–340 nm region. The increase in the performances in water splitting is mainly associated to the transient generation of a p–n junction between the Cu x O nanoparticles and TNT upon illumination, which enhances photocurrent density by promoting charge separation.

Alimentação dos peixes em um riacho do Parque Estadual Morro do Diabo, bacia do Alto Rio Paraná, sudeste do Brasil

Abstract: The trophic structure of a fish assemblage in a first order stream in the upper Parana River basin was investigated using standard methods of diet analysis and underwater observations utilizing snorkeling. Three stretches of the Corrego Sao Carlos were studied. Eighteen fish species belonging to five orders and ten families were captured. The stomach analysis of 299 fishes revealed that 70% of the food items are autochthonous, 24% allochthonous, and 6% material of unidentifiable origin. Eighteen pairs of species (33%) showed significant feeding overlap, though this overlap does not necessarily indicate competition given the temporal and spatial segregation during foraging. Three feeding guilds were found. The invertivores included Astyanax altiparanae, Moenkhausia sanctaefilomenae, and Oligosarcus pintoi, whose diet demonstrated a predominance of allochthonous items, and Rhamdia quelen, Trichomycterus sp., Corydoras aeneus, and Crenicichla britskii, that had a predominance of autochthonous items in their diets. In this group, A. altiparanae and M. sanctaefilomenae are drift feeders, R. quelen is a benthic opportunistic predator, Trichomycterus sp. and C. aeneus are grubbers, and O. pintoi and C. britskii are ambush predators. The omnivore with a tendency to herbivory is represented by Phalloceros caudimaculatus, which feeds mainly on algae. The periphitivores included Hisonotus sp., Hypostomus nigromaculatus, and H. ancistroides that are grazers with a diet composed mostly of diatoms, clorophyts, and organic matter. The results indicated that the fish assemblage in the Corrego Sao Carlos is structured at spatial, temporal, and trophic levels, and shows partitioning of the food resources. The addition of the fish species in each trophic guild along the stream is possibly due to the longitudinal increase of microhabitats that makes available more feeding sites.