A large octupole magnetic trap for research with atomic hydrogen.

We describe the design and performance of a large magnetic trap for storage and cooling of atomic hydrogen (H). The trap operates in the vacuum space of a dilution refrigerator at a temperature of 1.5 K. Aiming at a large volume of the trap, we implemented the octupole configuration of linear currents (Ioffe bars) for the radial confinement, combined with two axial pinch coils and a 3 T solenoid for the cryogenic H dissociator. The octupole magnet consists of eight race-track segments, which are compressed toward each other with magnetic forces. This provides a mechanically stable and robust construction with a possibility of replacement or repair of each segment. A maximum trap depth of 0.54 K (0.8 T) was reached, corresponding to an effective volume of 0.5 l for hydrogen gas at 50 mK. This is an order of magnitude larger than ever used for trapping atoms.

[Some biochemical characteristics of substances from extracellular virus-like particles of the Gypsy retrotransposon (MDG4)]. / Issledovanie nekotorykh biokhimicheskikh kharkteristik preparatov vnekletochnykh virusopodobnykh chastits retrotranspozona Gypsy (Mdg4).

To investigate the gypsy functional activity, the possibility of conservation of its genetic information in VLP in the extracellular form has been examined. Preparations containing extracellular gypsy VLP from D. melanogaster and D. virilis were obtained. Non degradative full-sized polyA+ RNA and polyA+ RNA-DNA complexes of gypsy were revealed in the both preparations. The polypeptides with some specificity to gypsy nucleic acids were identified in VLP preparations. Some morphological and physical characteristics of the VLP preparations were obtained. The data obtained suggest the presence of non-degradative gypsy VLP in cultured media of D. melanogaster and D. virilis cells.

Presence of the gypsy (MDG4) retrotransposon in extracellular virus-like particles.

As a first step to investigate the functional activity of gypsy virus-like particles (VLPs) we explored the possibility of preservation of its VLP in extracellular form. The preparations containing extracellular gypsy VLP from Drosophila melanogaster and D. virilis were obtained. Full-length polyA+ RNA and polyA+ RNA-DNA complexes of gypsy were observed in both preparations. The polypeptides with some specificity to gypsy nucleic acids were identified in the obtained VLP preparations. These data accompanied by morphological characteristics of samples testify the presence of intact gypsy VLP in cultured media both from D. melanogaster and D. virilis cultivated cells.