Hybrid sol-gel based coatings for the protection of historical window glass

Medieval glass is commonly attacked by atmospheric pollutants conveyed by water, triggering the corrosion process. Current conservation strategies aim to maintain window glass in its original context, and so it is necessary to protect it from further degradation. Sol–gel technology is very effective for the preparation of protective films, using Si-alkoxide precursors chemically similar to the substrate. The present work discusses water-repellent hybrid sol–gel coatings made from tetra-ethyl-ortho-silicate with different quantities of Si-alkoxides, functionalized with various alkyl groups. The coatings were deposited using the dip-coating technique and characterized by UV–VIS and FT-IR spectroscopy. Static and dynamic contact angle measurements showed an overall homogeneity of the coatings and indicated improved water-repellency when functionalized by long alkyl chains. The coatings with best performance in terms of transparency and contact angle, and with the lowest organic content, were selected and applied to medieval-like glass samples. Colorimetric characterization was carried out using a spectrophotometric scanner before and after application of the coatings and no significant color changes were found. The electron microscopy images revealed relatively even, crack-free coatings, especially with higher organic contents. Contact angle and colorimetric measurements were repeated after accelerated ageing by exposure to UV light and an SO2-saturated atmosphere. A significant decrease in the contact angle was observed only for the samples treated at the highest SO2concentration. The silica-based materials did not give reaction by-products, were water-repellent, compatible with the substrate, colorless, transparent, and stable under exposure to chemicals and light, thereby satisfying the main requirements for the conservation of Cultural Heritage

Germination of Ocotea pulchella (Nees) Mez (Lauraceae) seeds in laboratory and natural restinga environment conditions

The germination response of Ocotea pulchella (Nees) Mez seeds to light, temperature, water level and pulp presence is introduced. The laboratory assays were carried out in germination chambers and thermal-gradient apparatus, whereas the field assays were performed in environments with distinct light, temperature and soil moisture conditions within a permanent parcel of Restinga forest of the Parque Estadual da Ilha do Cardoso, Cananéia, São Paulo. The seeds do not exhibit dormancy, they are non photoblastic, and a loss of viability in dry stored seeds can be related to a decrease in water content of the seed. The presence of the pulp and the flooded substratum influenced negatively the germination of O. pulchella seeds tested in the laboratory. Otherwise, light and temperature probably are not limiting factors of the germination of O. pulchella seeds in the natural environment of Restinga. The optimum temperature range for germination of Ocotea pulchella seeds was 20 to 32 ºC, the minimum or base temperature estimated was 11 ºC and the maximum ranged between 33 and 42 ºC. The isotherms exhibited a sigmoidal pattern well described by the Weibull model in the sub-optimal temperature range. The germinability of O. pulchella seeds in the understorey, both in wet and dry soil, was higher than in gaps. Germination was not affected by fluctuations in soil moisture content in the understorey environment, whereas in gaps, germination was higher in wet soils. Thus, the germination of this species involves the interaction of two or more factors and it cannot be explained by a single factor

Socioeconomic status, birth weight, maternal smoking during pregnancy and adiposity in early adult life: an analysis using structural equation modeling Situação sócio-econômica, peso ao nascer, tabagismo na gravidez e adiposidade na vida adulta jovem: uma análise utilizando-se modelagem com equações estruturais

We describe here an example of structural equation modeling in epidemiology. The association between birth weight and adiposity in early adult life, adjusted for the number of cigarettes smoked during pregnancy and socioeconomic status at birth, was evaluated. Data involving 2,063 adults from the 1978/1979 Ribeirão Preto cohort study were used. Adiposity was measured by body mass index (BMI), waist circumference (WC) and the sum of triceps and subscapular skinfolds (STSS). Models were submitted to maximum likelihood estimation, separately for men and women. Birth weight had a small and significant effect on adiposity in men (standardized coefficient, SC = 0.08) and women (SC = 0.09). Smoking during pregnancy did not influence adiposity in men (SC = 0.004), but its effect was marginally significant in women (SC = 0.07; P = 0.056). Socioeconomic status at birth had a small and positive effect on adiposity in men (SC = 0.08) and a moderate and negative effect in women (SC = -0.16). In this young adult population, BMI, WC and STSS used alone or in combination were valid estimators of body adiposity.<br>O objetivo desse artigo é apresentar um exemplo da modelagem com equações estruturais. Foi avaliada associação entre peso ao nascer e adiposidade na vida adulta jovem, ajustando-se para número de cigarros fumados na gravidez e situação sócio-econômica ao nascimento. Dados de 2.063 adultos da coorte de Ribeirão Preto, São Paulo, Brasil, de 1978/1979 foram utilizados. A adiposidade foi medida pelo índice de massa corporal (IMC), circunferência da cintura, e somatório das pregas cutâneas subescapular e a tricipital. Os modelos foram estimados por máxima verossimilhança, separadamente para homens e mulheres. O peso ao nascer teve efeito pequeno e significante na adiposidade em homens (CP - coeficiente padronizado = 0,08) e mulheres (CP = 0,09). Tabagismo materno durante a gravidez não influenciou a adiposidade em homens (CP = 0,004), mas em mulheres a significância foi marginal (CP = 0,07; p = 0,056). O efeito da situação sócio-econômica da família ao nascimento foi pequeno e positivo para os homens (CP = 0,08) e moderado e negativo (CP = -0,16) para as mulheres. Nesta população adulta jovem, os indicadores utilizados sozinhos ou em conjunto mediram bem a adiposidade corporal