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Abstract Isomeric 1-(fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-1 H-indenyl) ethanes 1a,b and C1-symmetric metallocenes, viz., rac-1-(η5-fluoren-9-yl)-2-(2-methyl-5, 6-dihydrocyclopenta [f]-η5-inden-1-yl) ethanezirconium dichloride (9) and rac-1-(η5-fluoren-9-yl)- 2-(2-methyl-5, 6-dihydrocyclopenta [f]η5-inden-1-yl)ethanehafnium dichloride (10), with these ligands were synthesized by modified procedures. The structures of compounds 1b (two crystalline modifications) and 10 were established by X-ray diffraction analysis. The synthesis of polypropylene (PP) in bulk was studied in the presence of polymethylalumoxane-activated metallocenes 9 and 10 in the temperature range of 30–70°C. It was demonstrated that triisobutylaluminum can be used as a cocatalyst. In this case, the molecular weight of PP increases by a factor of ∼2. An increase in the reaction temperature leads to an increase in stereoregularity and crystallinity of PP. The polymer synthesized at high temperatures crystallizes in the γ form. The resulting PP is characterized by a wide range of properties from rigid crystalline thermoplastic to amorphous elastomeric. Samples, which have a high molecular weight and moderate isotacticity, exhibit high elastomeric and durability properties. [ABSTRACT FROM AUTHOR]

Gamma spectrometers with 100 × 100 mm NaI(Tl) and 200 × 100 mm CsI(Tl) crystals for detecting annihilation radiation of β+ radionuclides are described. Two spectrometers are located in a surface laboratory and one underground, at a depth of 500 m of water equivalent, in Novorossiisk. The background characteristics and the detection efficiency are presented for different operating modes of the coincidence system and for samples with different mass. A coincidence scheme in which all events with coincidences of pulses in both crystals and energy released in each detector are detected, making it possible to raise the 22Na detection efficiency by approximately 30%, was tested. The results of measurements of the 22Na content in some natural waters in Krasnodar krai, including in mud volcanoes, are presented. They show large seasonal variations. [ABSTRACT FROM AUTHOR]