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Abstract

We describe the development of a new type of heat exchanger. This heat exchanger operates using reverse thermosiphon action and consists of a self-acting and self-controlled liquid circulation loop with heat transfer in a downward direction, opposite to the direction of natural convection. This process moves a heat-carrying hot liquid downwards with the help of local heat transferred through the loop. This flow loop is partly filled with liquid and the upper part of the loop contains vapour from the liquid heat-carrier. The pressure difference in the saturated vapour is used to move the heated liquid downwards. The principles of action and the possibility of developing such a device using laboratory experimental methods are presented.
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Abstract

The study was performed on 21 H-F calves divided into 3 groups of 7 animals each. The first group was composed of calves whose mothers did not receive an injection of Se preparation. The second and third groups consisted of calves whose mothers were administered injections of Se and vitamin E in a single dose of 10 ml and 30 ml, 10 days before the expected parturition date. 24 hours after birth, blood samples were collected from all calves to determine Se, Fe and IgG concentrations and the activity of GSH-Px and GGT. The results of the study indicate that the administration of a single-dose Se supplement to cows in late pregnancy increases Se concentration in calves and promotes passive transfer of immunity from the mother to offspring.
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