Study of thermal effects of silicate-containing hydroxyapatites

The possibility of modifications of hydroxyapatite silicate ions, from the extracellular fluid prototype solution under near-physiological conditions has been studied. Formation of silicon-structured hydroxyapatite with different extent of substitution of phosphate groups in the silicate group has been established through chemical and X-ray diffraction analyses, FTIR spectroscopy and optical microscopy. The results obtained are in agreement and suggest the possibility of substitution of phosphate groups for silicate groups in the hydroxyapatite structure when introducing different sources of silica, tetraethoxysilane and sodium silicate, in the reaction mixture. Growth in the amount of silicon in Si-HA results in the increase in the thermal stability of the samples. The greatest mass loss occurs at temperatures in the range of 25-400 °С that is caused by the removal of the crystallization and adsorption water and volatile impurities. It is shown that the modified apatites are of imperfect structure and crystallize in a nanocrystalline state

Evaluation of the occupational risk of dock engineer of the seaport in Saint-Petersburg city

The aim of the study is assessment of harmful factors affecting the dock engineer’s health basing on the models of evaluation of the occupational risk to develop preventive measures in following.Целью исследования является оценка влияния вредных факторов на здоровье докеров — механизаторов на основе использования моделей профессионального риска для последующей разработки профилактических мероприятий