Juliana M. Oliveira

Richness preservation in a fragmented landscape: a study of epiphytic bryophytes in an Atlantic forest remnant in Northeast Brazil

Abstract Fragmentation and loss of habitat are considered to be the main causes for the decrease in biological diversity in tropical forests. This study aims to evaluate the size and edge effects on tree physiognomy and on the bryophyte community structure in relation to richness, composition, and distribution of ecological groups. Ten forest fragments from the Murici Ecological Station, in the state of Alagoas (Brazil) were studied. In each fragment 10 evenly spaced plots were delimited along four 100 m transects located perpendicularly to the border. One hundred and six species were found, of which 56 were liverworts and 50 were mosses. Results showed that flora impoverishment and other variations in the bryophyte community structure are related to fragment size. Shade epiphytes were the most affected. An ‘edge effect’ was not detected in this study. Vegetation physiognomy parameters contributed partially to the bryophytes’ responses. Diameter at breast height, height, and the density of trees were both positively correlated with bryophyte richness, while canopy openness was not. Our results suggest that the larger fragments are better structured physiognomically, i.e. the trees are taller and have larger diameters, which are probably important factors in enabling them to retain a rich bryophyte flora.

Influence of different protecting groups on the regioselectivity of the hydrotelluration reaction of hydroxy alkynes

A influencia de grupos protetores na sintese regio- e estereosseletiva de teluretos vinilicos preparados a partir de BuTeNa e alcoois propargilicos e homopropargilicos demonstrou que o eter de silicio TIPS e util como grupo regio-dirigente. A aplicacao da metodologia na sintese de um fragmento do (±)-Seselidiol, um produto natural, demonstrou a aplicabilidade da metodologia desenvolvida. The influence of protecting groups on the synthesis of regio- and stereodefined vinyl tellurides derived from the reaction of BuTeNa and propargylic- or homo-propargylic alcohols showed that TIPS silyl ether is useful as a regiodirecting group. The application of the methodology to the synthesis of a fragment of (±)-Seselidiol, a natural product, demonstrated the applicability of the new methodology.

Synthesis of Chalcogenides using Indium Intermediates in Aqueous Media

Abstract Selenides and vinylic selenides were synthesized from their corresponding organic halides and alkynes in aqueous media using indium metal.