The thermoelectric properties of 28 sintered Si0.8 Ge0.2 alloys, heavily doped with either boron or phosphorus and prepared from powders with median particle sizes ranging from about 1 μm to over 100 μm, have been determined from 300 to 1300 K. The thermal conductivity decreases with decreasing particle size, however, the figure of merit is not significantly increased due to a compensating reduction in the electrical conductivity. The thermoelectric figure of merit is in good agreement with results of Dismukes et al. [J. Appl. Phys. 10, 2899 (1964)] on similarly doped alloys prepared by zone-leveling techniques. The electrical and thermal conductivity are found to be sensitive to preparation procedure while the Seebeck coefficient and figure of merit are much less sensitive. The high-temperature electrical properties are consistent with charge carrier scattering by acoustic or optical phonons.

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To investigate whether maternal or fetal glucocorticoid secretion is altered during pregnancy complicated by diabetes mellitus, in vitro production of corticosterone (B) and cortisol (F) was measured on day 28 of gestation in rabbits made alloxan diabetic prior to pregnancy. In addition, plasma B and F were followed throughout the experimental period. Fetuses of diabetic mothers were hyperglycemic and hyperinsulinemic, and mortality was much higher (18%) than that of control animals (1.5%). No significant differences were found in maternal plasma B or F during gestation, whereas F was significantly lower in fetuses of diabetic mothers. In vitro production of both B and F by maternal and fetal adrenals was lower in the diabetic animals, and responses to ACTH or insulin added to the incubation were the same in both groups. These results suggest that the ability of the adrenal cortex to secrete glucocorticoids may be impaired both in the mother and fetus when maternal diabetes is present. This could have effects both on maturational events in the fetus that are accelerated by glucocorticoids and on the ability to respond to stress.

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