Determination of58Fe and65Cu enriched stable isotopic tracers in studies of mineral metabolism of babies

Neutron activation analysis is an appropriate method for the determination of the excretion by infants of enriched stable isotopes which have been added to synthetic milks for assessment of elemental bioavailability.⁵⁸Fe enrichments in diet and faeces have been determined by instrumental NAA and a radiochemical procedure established for determination of⁶⁵Cu enrichments. Conditions for the latter facilitate determination of both stable Cu isotopes, thereby providing results for the total concentration of this element. Appearance of added stable isotopes in samples collected between carmine red markers has been confirmed, and the method applied to studies of Fe and Cu absorption.     

The spectrum of a Volterra composition operator

Lyubic's conjecture, that the Volterra composition operator of equation (1) is quasinilpotent iff condition (2) holds, is established and is generalized to Volterra composition operators on L^P[0, 1].