Seasonal variation in the phenol content of Eugenia uniflora L. leaves Variação sazonal nos teores de fenóis de folhas de Eugenia uniflora L

Hydrolysable tannins, total phenols and flavonoids in Eugenia uniflora leaves were monthly analysed for one year. The results were correlated with climate conditions (rainfall, humidity, cloudiness and mean temperature) through chemometric methods. Principal component analysis revealed high levels of hydrolysable tannins in the rainy season, whereas flavonoids were mainly produced in the dry season. These facts suggest that climatic changes may be one of the factors affecting phenol levels in Eugenia uniflora.<br>Taninos hidrolisáveis, fenóis totais e flavonóides presentes em folhas de Eugenia uniflora foram quantificados mensalmente durante um ano. Os resultados foram correlacionados com as condições climáticas (pluviosidade, umidade, nebulosidade e temperatura média) através de métodos quimiométricos. Análise de componentes principais revelou a ocorrência de altos teores de taninos hidrolisáveis durante a estação de chuvas, enquanto os flavonóides foram produzidos principalmente na estação seca. Estes fatos sugerem que mudanças climáticas podem ser um dos fatores que afetam os níveis de fenóis em Eugenia uniflora

Microsize and nanosize BPO4 from pyrolysis of a carborane-substituted polyphosphazene

8 pages, 4 figures, 6 scheme.-- et al.Pyrolysis in air of the carborane-substituted polyphosphazene, {[NP({OCH2}2C2B10H10)]0.5 [NP({OCH2}2C2B9H10· NBu4)]0.5} n affords BPO4 crystals of varied sizes in the micro and nano regime.The materials were characterised by IR spectroscopy, SEM-EDAX, TEM, X-ray diffraction, and DTA analysis. A possible mechanism for the formation of these materials is discussed and compared with that found for the formation of metallic nanostructured materials from the pyrolysis of anchored organometallic derivatives of polyphosphazenes.This work is supported by Fondecyt (project 1030515), MEC (CTQ2004–05495-C02–01/BQU) and Gobierno de Aragon.Peer reviewe