RESUMO
During the interval from September through early December 2005, the Hayabusa spacecraft was in close proximity to near-Earth asteroid 25143 Itokawa, and a variety of data were taken on its shape, mass, and surface topography as well as its mineralogic and elemental abundances. The asteroid's orthogonal axes are 535, 294, and 209 meters, the mass is 3.51 x 10(10) kilograms, and the estimated bulk density is 1.9 +/- 0.13 grams per cubic centimeter. The correspondence between the smooth areas on the surface (Muses Sea and Sagamihara) and the gravitationally low regions suggests mass movement and an effective resurfacing process by impact jolting. Itokawa is considered to be a rubble-pile body because of its low bulk density, high porosity, boulder-rich appearance, and shape. The existence of very large boulders and pillars suggests an early collisional breakup of a preexisting parent asteroid followed by a re-agglomeration into a rubble-pile object.
RESUMO
A sphingomyelin analogue 2, in which the long alkenyl chain and the phosphodiester moiety of sphingomyelin were replaced by a phenyl and an isosteric difluoromethylenephosphonic acid, was prepared to evaluate its inhibitory potency to sphingomyelinase. The analogue non-competitively inhibited the neutral sphingomyelinase in bovine brain microsomes with an IC50 of 400 microM. The compound had the ability to suppress tumor necrosis factor alpha-induced apoptosis of PC-12 neurons at a low concentration of 0.1 microM.
