The effect of acetylation on the mechanical properties, hydrophobicity, and dimensional stability ofPinus sylvestris

Summary Strips and blocks ofPinus sylvestris were acetylated for different periods of time. These, along with control samples, were tested for their tensile modulus, hydrophobicity and dimensional stability. The modulus of elasticity (tensile modulus) for each sample was derived using a statistical approach. The observations in this work suggest that the acetylation process significantly reduces the tensile modulus of the wood compared to its untreated state in an irreversible manner, and that the extent of the deterioration in tensile modulus is a function of the acetylation conditions. Acetylation improved significantly the hydro-phobicity and the dimensional stability of the wood as measured by the roll angle and swelling tests respectively. It appears therefore that acetylation using acetic anhydride in xylene has an optimum set of reaction conditions that compromise between the gains in water repellence and dimensional stability with the deterioration in mechanical properties.We would like to acknowledge the support of Unilever Research in providing the materials testing machine used in this work, and for the supportive discussions with Hickson & Welsh concerning the results     

Sea star platastenras: ossicle morphology and taxonomic position

The modern sea star Platasterias latiradiata, on the basis of ossicle morphology, is removed from the fossil subclass Somasteroidea and assigned to the genus Luidia of the living subclass Asteroidea. A somasteroid assignment of this species should not be used in inferences concerning evolution and morphology of primitive echinoderms.     

Nicotine blocks the suckling-induced rise in circulating prolactin in lactating rats

In lactating rats the rapid suckling-induced release of pituitary prolactin into circulating blood is inhibited by a subcutaneous injection of nicotine. This treatment does not block the lesser "stress-induced" rise in prolactin in response to either. Although nicotine may impair milk production by its effect on prolactin release, it does not appear to block milk ejection from the lactating mammary gland.