Induced radioactivity of LDEF materials and structural components

We present an overview of the Long Duration Exposure Facility (LDEF) induced activation measurements. The LDEF, which was gravity-gradient stabilized, was exposed to the low Earth orbit (LEO) radiation environment over a 5.8 year period. Retrieved activation samples and structural components from the spacecraft were analyzed with low and ultra-low background HPGe gamma spectrometry at several national facilities. This allowed a very sensitive measurement of long-lived radionuclides produced by proton- and neutron-induced reactions in the time-dependent, non-isotropic LEO environment. A summary of major findings from this study is given that consists of directionally dependent activation, depth profiles, thermal neutron activation, and surface beryllium-7 deposition from the upper atmosphere. We also describe a database of these measurements that has been prepared for use in testing radiation environmental models and spacecraft design.     

Studies in alkylation. I. Synthesis and reactions of spiro[oxirane-2,4-piperidines]

Spiro[oxirane-2, 4′-piperidines] have been prepared by the action of dimethyloxosulfonium methylide on 4-piperidones. The spiro[oxirane-2,4′-piperidines] act as alkylating agents to introduce (4-hydroxy-4-piperidyl) methyl moieties onto heteroaromatic compounds such as 4(3H)-quinazolone.     

Characterization of the carotenoid complex of the leaves of different varieties of subtropical persimmon

All-Union Scientific-Research and Experimental-Design Institute for the Storage and Processing of Subtropical Fruits, Batumi. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 410–411, May–June, 1990.     

C-10 substituted 19-norsteroids—VII 10-cyano-2-ketosteroids

The syntheses of 10- and 10β-cyano-5-estran-2-one-17β-ol is described. Some reactions of the new compounds are described and discussed.