Gamma-ray spectroscopy in the decay of (83)Se to levels of (83)Br.
High-resolution γ ray spectroscopy experiments have been done to study the emissions from the radioactive decay of 22-min (83g)Se produced from neutron capture using samples of enriched (82)Se. Energy and intensity values have been obtained to roughly an order of magnitude greater precision than in previous studies. Based on energy sums, 2 new levels are proposed in the daughter (83)Br and one previously proposed level is shown to be doubtful. Some 25 new transitions appear to decay with the (83)Se halflife, about half of which can be accommodated among the previous or newly proposed levels. Several previous γ ray placements are shown to be inconsistent with the new determinations of the (83)Br energy levels, but cannot be accommodated anywhere else among the known levels. As a result of the missing γ ray placements, some of the β branchings in the decay to levels of (83)Br appear to be negative. Gamma rays from the 2.4-h decay of the daughter (83)Br to levels of (83)Kr have also been observed, along with decays of (81g)(,m)Se present as a small impurity in the enriched samples and also as a strong component in irradiated samples of natural Se.
Low-lying levels in 83Kr
83Kr has been studied by gamma -ray spectroscopy using the 80Se( alpha ,n) reaction and Coulomb excitation. Many new levels are proposed in the 1-3 MeV range of excitation energy. Spin-parities are assigned for most established and new levels up to 1.5 MeV. Transition strengths, multipole mixing ratios and branching ratios are deduced for many of the gamma decays. The data give some support for a cluster-vibrator coupling model of 83Kr although a detailed test must await theoretical application of this model specifically to this nucleus.
Effects of thyrotropin-releasing hormone and a thyrotropin releasing hormone analog on growth and selected plasma hormones in lambs.
An 8-wk growth trial was conducted to assess the effects of continuous infusion of thyrotropin-releasing hormone (TRH) and an active TRH analog less than Aad-His-Pro-NH2 (the less than Aad is L-pyro-alpha-aminoadipic acid) on growth trial performance, carcass composition and hormone profiles of growing lambs. Both drugs were infused at 600 micrograms X lamb -1 X d -1 with 16 lambs/treatment. Both TRH and less than Aad-His-Pro-NH2 decreased average daily gain (ADG; P less than .01) and increased feed conversion (FC; P less than .01) compared with saline infused controls. Average daily feed intake was not altered. Carcasses of lambs given TRH or less than Aad-His-Pro-NH2 contained fewer kilograms of moisture (P less than .05) and appeared to contain fewer kilograms of protein. Thyrotropin-releasing hormone and less than Aad-His-Pro-NH2 increased thyroid gland weights (P less than .05), but pituitary gland weights were not different. Plasma thyrotropin (TSH) concentrations were increased by both drugs compared with control lambs, peaking at 4 to 7 d after initiating infusion. However, by 14 d, TSH concentrations returned to control levels. Triiodothyronine (T3) and thyroxine (T4) were elevated by both drugs over the entire 8-wk trial, with peak levels reached at 10 d and maintained for the duration of the study. Both TRH and less than Aad-His-Pro-NH2 increased prolactin over the entire period. Growth hormone levels were not altered by either drug. The effects of less than Aad-His-Pro-NH2 infusion on growth trial performance, carcass composition and hormone profiles of growing lambs were very similar to TRH. The negative effects of TRH and less than Aad-His-Pro-NH2 infusion on ADG, FC and carcass protein appear to be the result of elevated T3 and T4 levels.