RESUMO
The terrestrial ages of three Allan Hills meteorites are between 3 x 10(4) and 3 x 10(5) years and one is (1.54(-0.28)(+0.14)) x 10(6) years old. The Antarctic ice sheet is therefore older than (1.54(-0.28)(+0.14)) x 10(6) years and the meteorite accumulation process at Allan Hills probably began between 3 x 10(4) and 3 x 10(5)years ago.
RESUMO
The concentrations of beryllium-7, sodium-22, aluminum-26, potassium-40, scandium-46, vanadium-48, chromium-51, manganese-54, cobalt-57, cobalt-60, and thorium-232 (thallium-208) have been measured in the Allende meteorite by nondestructive gamma-ray spectrometry. The high cobalt-60 content of the meteorite is indicative of a preatmospheric body with a minimum effective radius of 50 centimeters and a weight of 1650 kilograms; the aluminum-26 activity indicates a minimum exposure age of 3 million years.
RESUMO
The (7)Be, (22)Na, (26)Al, (44)Ti, (46)SC, (48)V (51)Cr, (54)Mn, (56)Co, (57)Co, (57)CO, (40)K, (238)U, and (232)Th were measured in lunar fines and portions of three rocks. Major production of cosmogenic radionuclides is due to solar protons, thus their concentrations are far different than those in meteorites. Surface exposures of the rocks and fines are long compared with the 0.74 million year half-life of (26)Al. Lunar fines show substantially higher concentrations of low energy reaction products. The ratios of thorium to uranium are extremely constant at 3.8, which indicates very little geochemical differentiation and are in good agreement with a common nucleosynthesis for lunar and earth materials.
RESUMO
Chemical and histochemical analyses were carried out on uteri of four monkeys in which plastic IUDs or Cu-IUDs had been implanted for 36 to 43 days. The mean uterine copper content of the plastic-treated animals was 1.1 mug/gm (mean of two), while this value for the Cu-IUD treated monkeys was 1.7 mug/gm. The copper was distributed primarily in the cyclically renewed regions of the endometrium: the luminal fluid, endometrial surface, and superficial lamina propria. The element was localized and was not uniformly distributed in these regions. Copper analyses of plasma, liver, and kidney showed no differences between these two groups. Histopathologic evaluation revealed some areas of edema and increased numbers of neutrophils in plastic-IUD-treated animals. In the Cu-IUD-implanted monkeys, similar changes were observed as was a flattening of the surface epithelium. The endometrium had a loose areolar appearance. The copper elution rate was about 90 mug/day, about twice that observed in women using Cu-IUDs.