The relation of the concentration of macronutrients in the substrate and in the foliage to cell wall thickness and cellulose concentration in the xylem of slash pine (Pinus elliotti)

Sand culture experiments, using a sub-irrigation technique, were installed in order to find out the effects of the macronutrients N, P, K, Ca, Mg and S on growth, aspect, mineral composition, length of fibers, thickness of cell wall and cellulose concentration in slash pine. The aim was to obtain, under controlled conditions, basic information which could eventually lead to practical means designed to increase the rate of growth and to make of slash pine a richer source of cellulose. Nitrogen, Phosphorus, Potassium Experiment A 3 x 3 x 3 factorial design with two replicates was used. Nitrogen was supplied initially at the levels of 25, 50 and 100 ppm; phosphorus was given at the rates of 5, 10 and 20 ppm; potassium was supplied at the rates of 25, 50 and 100 ppm; six months after the experiment was started the first level for each element was dropped to zero. Others macro and all micronutrients were supplied at uniform rates. Fifteen hours of illumination per day were provided. The experimental technique for growing the slash pine seedlings proved quite satisfactory. Symptoms of deficiency of nitrogen, phosphorus and potassium were observed, described and recorded in photographs and water colors. These informations will help to identify abnormalities which may appear under field conditions. Chemical analysis of the several plant parts, on the other hand, give a valuable means to assess the nutritional status of slash pine, thus confirming when needed, the visual diagnosis. The correctness of manurial pratices, on the other hand, can be judged with the help of the analytical data tabulated. Under the experimental conditions nitrogen caused the highest increases on growth, as measured by increments in height and dry weights, whereas the effects of phosphorus and potassium were less marked. Cellulose concentration was not significantly affected by the treatments used. Higher levels of N seemed to decrease both length of fiber elements and the thickness of cell wall. The effects of P and K were not well defined. Calcium, Magnesium, Sulfur Experiment A 3 x 3 x 3 factorial design with two replicates was used. Calcium was supplied initially at the levels of 12.5, 25 and 50 ppm; magnesium and sulfur were given at the rates of 6, 12.5 and 25 ppm. Other macro and micronutrients were supplied at uniform rates, common to all treatments. Three months after starting the experiment the first level for each element was dropped to zero. Symptoms of deficiency of calcium, magnesium and sulfur were observed, described and recorded as in the case of the previous experiment. Chemical analysis were made, both for mineral content and cellulose concentration. Length of fibers and thickness of cell wall were measured. Both calcium and magnesium increase height, sulfur failing to give significant response. Dry weight was beneficially affected by calcium and sulfur. The levels of calcium, magnesium and sulfur in the needles associated with deficiency and maximum growth are comparable with those found in the literature. Cellulose concentration increased when the level of sulfur in the substrate was raised. The thickness of cell wall was negatively affected by the treatments; no effect was observed with regards to length of fibers.Foram conduzidos experimentos fatoriais cultivando P. elliottii em solução nutritiva destinados a estudar o efeito de macronutrientes na composição mineral, grossura da parede celular e concentração da celulose no xilema. Os sintomas de deficiencia dos elementos foram descri tos e registrados. O crescimento foi estimulado por N, P, K, Ca e Mg, sendo a maior resposta devida ao N. Somente o enxofre aumentou significativamente o teor de celulose. A grossura da parede celular diminuiu com altos níveis de N, Ca, Mg e S; os primeiros diminuiram o comprimento das fibras

Synthesis of Main-Chain Poly(fullerene)s from a Sterically Controlled Azomethine Ylide Cycloaddition Polymerization

International audienceFullerene is used as a monomer in this simple method to prepare soluble, well-defined polymers. The sterically controlled azomethine ylide cycloaddition polymerization of fullerene (SACAP) yields macromolecules with molecular weights of around 25 000 g mol-1. Importantly, cumbersome comonomers are employed to restrict cross-linking. Extensive characterizations, with the help of modeling studies, indicate that the polymers are regio-irregular with a majority of trans-3 isomers. Of particular interest is the exceptional ease of preparing polymers with zero metal content. © 2016 American Chemical Society

Plantas visitadas por abelhas africanizadas em duas localidades do estado de São Paulo Plants visited by africanized honey bees in two localites of the state of São Paulo

O conhecimento das plantas de uma região, sua época de florescimento e as características do pólen, auxiliam na determinação das espécies vegetais que contribuem para a composição do mel. Durante o período de 1994 a 1997 foram inventariadas, semanalmente, em diferentes horários e num raio de aproximadamente 300m dos apiários da USP/ESALQ, em Piracicaba,SP (22°43'S, 47°27'W e 580 m) e do Instituto de Zootecnia, em Pindamonhangaba, SP (22°57'S, 45°27'W e 560 m), as plantas que estavam sendo visitadas por abelhas. Foram anotados o mês e o período de florescimento das plantas inventariadas. Em Piracicaba foram identificadas 94 espécies de plantas pertencentes a 41 famílias (maior número de espécies nas famílias Asteraceae e Myrtaceae) e em Pindamonhangaba, 76 espécies, pertencentes a 26 famílias (maior número de espécies nas famílias Asteraceae e Verbenaceae). Os resultados indicam que 21 famílias, 22 gêneros e 15 espécies de plantas visitadas pelas abelhas africanizadas foram comuns em ambas as localidades.<br>The knowledge of plants from a given region, as well as the blooming period and the pollen characteristics, help for the determination of the plant species which contribute for the honey composition. Plants visited by honey bees were listed during the period 1994 to 1997. The survey was carried out weekly, at different times and within a 300 m radius at two sites: the apiaries of USP/ESALQ in Piracicaba, SP (22°43'S, 47°27'W e 580 m) and of the 'Instituto de Zootecnia', in Pindamonhangaba, SP (22°57'S, 45°27'W e 560 m), both in Brazil. The month and the blooming period were recorded. A total of 94 plants species, from 41 families was identified in Piracicaba (the largest number of species in Asteraceae and Myrtaceae) and 76 plant species of 26 families, in Pindamonhangaba (the largest number of Asteraceae and Verbenaceae). The results indicated that 21 families, 22 genera and 15 species were common for both localities