Nesting stingless bees in urban areas: a reevaluation after eight years

Studies of nesting ecology have proven to be extremely important for stingless bee conservation. These studies have rarely been conducted in urban landscapes, and even fewer have compared species diversity and abundances over time. We surveyed native stingless bee nests at the Federal University of Juiz de Fora campus in Minas Gerais, southeastern Brazil, from May 2008 to April 2009. We recorded the number of nests, nest height, species diversity, and nest substrate type (i.e., natural or artificial). We compared our results to those of a similar survey carried out in the same location eight years prior (2000/2001) in order to evaluate how urban expansion on campus has influenced the Meliponini bee community. Stingless bee abundance and richness were greater in the second survey. The use of natural substrates decreased, while the use of artificial substrates increased. This suggests that the increase in man-made structures on the UFJF campus has provided favorable sites for establishment of some stingless bee species

Nanometric Particle Size And Phase Controlled Synthesis And Characterization Of γ-fe2o3 Or (α + γ)-fe2o3 By A Modified Sol-gel Method

Fe2O3 nanoparticles with sizes ranging from 15 to 53 nm were synthesized by a modified sol-gel method. Maghemite particles as well as particles with admixture of maghemite and hematite were obtained and characterized by XRD, FTIR, UV-Vis photoacoustic and Mössbauer spectroscopy, TEM, and magnetic measurements. The size and hematite/maghemite ratio of the nanoparticles were controlled by changing the Fe:PVA (poly (vinyl alcohol)) monomeric unit ratio used in the medium reaction (1:6, 1:12, 1:18, and 1:24). The average size of the nanoparticles decreases, and the maghemite content increases with increasing PVA amount until 1:18 ratio. The maghemite and hematite nanoparticles showed cubic and hexagonal morphology, respectively. Direct band gap energy were 1.77 and 1.91 eV for A6 and A18 samples. Zero-field-cooling-field-cooling curves show that samples present superparamagnetic behavior. 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