Spray aiming in bombardier beetles: jet deflection by the coanda effect

Bombardier beetles of the carabid subfamily Paussinae have a pair of flanges, diagnostic for the group, that project outward from the sides of the body. Behind each flange is a gland opening, from which the beetles discharge a hot, quinone-containing secretion when disturbed. The flanges are curved and grooved and serve as launching guides for anteriorly aimed ejections of secretion. Jets of fluid, on emergence from the gland openings, follow the curvature of the flanges and are thereby bent sharply in their trajectory and directed forward. The phenomenon is illustrative of the Coanda effect, widely applicable in engineering and responsible for the familiar tendency of liquids to curve around spouts and down the front of containers when being poured.     

The other frontiers of science

Frontiers of science are usually considered as those areas where the boundares of human knowledge are being pushed most vigorousl into the unknown. These are the intemal frontiers. But no less important are the external frontiers. Those bordering on the federal govermment, on education, on private industry and on intemational affairs and the developing world are among the most critical and demanding. Some of the outstanding problems facing science, and scientists in these extemal interactions, are discussed within the context of our changing national and international priorities.     

Orthopyroxene exsolution in augite: a two-step, diffusion-transformation process

Orthopyroxene lamellae exsolved from augite on (100) are shown to grow by a two-step process involving (i) the diffusion of calcium and (magnesium, iron) to form clinohypersthene and (ii) the inversion of clinohypersthene to orthopyroxene, probably by glide twinning. If complete inversion is prevented by cooling or steep concentration gradients, the two-step process produces orthopyroxene with narrow margins of clinohypersthene. Measured elemental concentration gradients at (100) lamellar interfaces support this mechanism.     

Conservation and duplication of isozymes in plants

Many enzymes in plants have isozymes because the same catalytic reaction is often present in several subcellular compartments, most frequently the plastids and the cytosol. The number and subcellular locations of the isozymes appear to be highly conserved in plant evolution. However, gene duplication in diploid species and the addition of genomes in polyploid species have increased the number of isozymes.