The behaviour of radionuclides was studied by the method of thermodynamic modelling in the wide temperature range 400-3200 K during interaction of radioactive graphite with water vapour, taken in the ratio C (s):H 2 O (g) = 1:10 and 1:20 (by mass). It was determined that the main components of the gaseous phase over the whole temperature range are H 2 O vapour, H 2 , gaseous CO and CO 2 containing radioactive 14 C. Their partial pressures exceed 10 3 Pa. Cs, Sr, Ca, Be, Ni radionuclides, which radioactive graphite contains, form volatile hydroxides, U, Pu radionuclides-volatile oxides. The partial pressure of these radionuclides does not exceed 10 -1 Pa.

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In view of the increasing number of hip joint replacement volume there remains the key issue of improving prosthesis survivorship which directly depends on the friction couple. Material and methods. The authors have analyzed five year outcomes of two bearing types (head and insert) used in hip replacement: ceramic-on-ceramic (CoC) in 324 patients and ceramic-on-polyethylene (CoP) in 300 patients. Totally 550 patients were operated in the period starting 2010 till 2014, including 74 patients underwent bilateral hip replacement. The authors divided patients based on gender and also into three age groups: 20-40, 41-60 and 61-80 years old. The largest group comprised 156 women aged 41-60 years (28.4%). Additional grouping of patients was made based on gender, age and bearing diameter.36 mm diameter bearing was characterized of the most frequent use. Functional outcomes were assessed by Harris Hip Score. Statistical analysis was made with Statistica 10 software. Statistical significant was observed at p0.05.Results.28 mm diameter bearing were rarely (19.5%) applied and mainly in women which is related to need for use of smaller acetabulum components and inability to implant a larger insert.36 mm diameter bearing were used most frequently, CoC articulation of36 mm was used in men in 34% of cases and in women – in 18.12% of cases.40 mm articulations were implanted in women two times less than in men which is related to a smaller diameter of acetabulum in women. Generally, CoC bearings were implanted more often in men which can be explained by a bigger social demand as well as a higher anti-luxation stability of large diameter bearings. Dislocations of implants occurred in 5 (0.91%) patients: in 4 patients with CoP bearingand in one patient with CoC articulation. Four revision procedures (0.64%) were made due to deep periprosthetic infection: two surgeries in each group. Harris Hip Score evaluation in CoC group demonstrated excellent and good outcomes in 99.2% of cases, and in CoP group – in 97.5% of cases.Conclusion. The authors observed no ceramic fractures or acoustic effects during 60 months follow up. It’s reasonable to increase CoC bearing diameter to achieve a better anti-luxation effect. CoC bearing selection should depend on patient’s activity and social demands but not only on the age. Based on study observations the authors forecast a higher survivorship of CoC couple within 15-20 years and expect to prove this conclusion in further studies.

a b s t r a c tThe composition of the vapor phase and the partial pressures of vapor components have been defined at pressures from 10 2 to 10 7 Pa and in the temperature range from 500 to 3000 K. Diagrams of liquid-vapor phase equilibria for the Pb-Bi system have been constructed. A good agreement between experimental results and the carried out calculations on the Pb-Bi phase diagrams is observed.