RESUMEN
Sodium chlorate is an achiral molecule that crystallizes from water in the chiral space group P2(1)3. In the absence of chiral perturbations, a random distribution of (+) and (-) crystals is obtained. Kondepudi(2) has shown that constantly stirring an evaporating NaClO(3) solution gives mostly either (+) or (-) crystals. Repeating this experiment many times gives equal numbers of (+) and (-) sets of crystals. Herein we report that when evaporating aqueous NaClO(3) is subjected to beta particles from an Sr-90 source, an asymmetric distribution of (+) and (-) crystals favoring the (+) crystals is obtained. The beta particles are energetic polarized electrons that are approximately 80% of left-handed helicity. By a poorly understood mechanism, the spin polarized electrons produce chiral nucleating sites that favor formation of the (+)-NaClO(3) crystals. Exposure of the evaporating solution instead to energetic positrons from an Na-22 source yields mainly (-)-NaClO(3) crystals. Polarized positrons are of predominantly right-handed helicity. One may conclude that the chirality of the radiation is correlated with the chirality of the crystals being generated.
RESUMEN
A laborer who worked in a steel mill and in a shipyard developed a nonspecific pulmonary interstitial fibrosis. Postmortem samples of his lung were digested, and the inorganic material present was extracted and examined using transmission electron microscopy, electron diffraction, and electron microprobe analysis. Uncoated asbestos fibers were present (1.4 X 10(5)/g wet lung), but the surprising finding was the presence of a large number of fly ash particles (6 X 10(6)/g wet lung). Fly ash, the particulate material produced during coal combustion, has not previously been reported to be present in human lung tissue. Although the contribution of the asbestos to this man's lung disease is uncertain, we believe, based on previous studies implicating aluminum silicates in pneumoconiosis, that the fly ash, an aluminum silicate, may be a contributing factor.
Asunto(s)
Carbono/efectos adversos , Neumoconiosis/etiología , Anciano , Carbón Mineral , Ceniza del Carbón , Polvo , Humanos , Pulmón/patología , Masculino , Metalurgia , Material Particulado , Neumoconiosis/patologíaRESUMEN
Fly ash specimens from four power plants in the Tennessee Valley Authority system have been separated into three matrices: glass, mullite-quartz, and magnetic spinel. Chemical species of trace elements are defined to a large extent by the matrices that contain them. The magnetic component of fly ash is ferrite. The mullite-quartz phase is relatively pure and can be recovered as a resource.
RESUMEN
The influence of three alloys and their amalgams on the in vitro growth of Streptococcus mutans has been estimated. Spherical, fine cut, and dispersion alloys were studied. Dispersion alloy amalgams seem to inhibit bacterial growth more than amalgams prepared from the other alloys in a similar fashion.