Investigation of diamond biocompatible coatings for medical implants

Despite the advantages of diamond-like carbon fi lms that are used as wear-resistant coatings for implants, they may have a number of disadvantages such as the high level of internal tension, low adhesive durability and high sensitivity to environment conditions. These problems can be overcome by application of the new carbon nanocomposite coatings that can be deposited from C60 ionic beam. It was found that the proposed diamond-like nanocomposite coatings increase implant material resistance to electrochemical corrosion processes due to shift of its electrode potential to area of positive values, and also promote a complex of reparative and adaptation and compensatory reorganizations that will allow to accelerate processes of healing and postoperative adaptation of organism in zone of implant inputting.Незважаючи на переваги діамантоподібних вуглецевих покриттів, що використовуються в якості зносостійких захисних покриттів для імплантатів, вони можуть мати ряд недоліків, таких як високий рівень внутрішніх напружень, низька адгезійна міцність, висока чутливість до умов навколишнього середовища. Ці проблеми можуть бути подолані в разі застосування нових вуглецевих нанокомпозитних покриттів, нанесених з іонного пучка С60. Встановлено, що запропоновані діамантоподібні нанокомпозитні покриття підвищують опірність матеріалу імплантату до електрохімічних корозійних процесів за рахунок зміщення його електродного потенціалу в область позитивних значень, а також сприяють комплексу репаративних і адаптаційно-компенсаторних перебудов, що дозволить прискорити процеси загоєння та післяопераційної адаптації організму в зоні введення імплантату

Features of medical implant passivation using anodic oxide films

The passivation ability of metals from groups IV and V of the Periodic Table is considered. Anodic treatment is able to neutralize the increase of metal hardening when comminuting grains to nanometre sizes. The deposition of metal oxide film coatings on a cobalt–chromium alloy surface results in substantial passivation of its surface and prevents cobalt and chromium accumulation in bone tissues. The decrease of surface activity of titanium implants can be achieved both by cleaning the surface during vacuum annealing before oxidation and by the increase of the anodic oxide film thickness, which limits mass and charge transfer through the implant surface. Recommended titanium implant treatment regimens are vacuum annealing at 650 °C and anodic oxidation to attain an oxide thickness less or equal to 300 nm

Diamond biocompatible coatings for medical implants

New carbon (diamond-like) nanocomposite coatings deposited from a C60 ionic beam can be used as a wear-resistant protective coating for implants. It was found that these coatings enhance resistance to тelectrochemical corrosion processes due to a shift of the material’s electrode potential to a zone of positive values. They also promote a complex of reparative, adaptative and compensatory reorganization that accelerates the healing processes in the vicinity of the implant

Stimulation of calcium phosphate crystal formation by implant surfaces with electret properties

Oxide coatings with electret properties are investigated. The possibility of stimulation of the formation of calcium phosphate sediments near the electroactive surface is discussed. The exposure of implants with such coatings to solutions imitating blood plasma showed their high efficiency of biointegration due to activation of an exchange processes in living tissues by a negative superficial charge. The revealed effect amplifies with the growth of the thickness of the anodic oxide film

Properties of magnetron hydroxyapatite coatings deposited on oxidized substrates

Hydroxyapatite (HA) coating were formed on oxidized niobium surfaces by the highfrequency magnetron sputtering method using hydroxyapatite and tricalcium phosphate targets. The structure, substructure and mechanical properties of the Nb–Nb2O5–HA system were investigated by X-ray diffraction, atomic force microscopy and nanoindentation and the stress state was assessed. The synthesized hydroxyapatite film had the following characteristics: thermal expansion coefficient 10–5 K–1; modulus of elasticity 120 GPa; adhesive strength not less than 0.45 kg/mm2; density 2900 kg/m3. The stress magnitude in the metal oxide substrate was from 11 to 14 MPa after hydroxyapatite film deposition

IMMUNOSUPPRESSIVE EFFECTS OF ARGININE DEIMINASE FROM STREPTOCOCCUS PYOGENES

Many pathogens use metabolic pathway of arginine for successful dissemination. Bacterial arginine deiminase hydrolyzes arginine to form one molecule of ammonia and two molecules of ATP. The activity of the enzyme contributes to the improvement of survival of pathogenic bacteria in conditions of low pH at the site of infection or in phagolysosome, as well as in anaerobic conditions, and also leads to deficiency of arginine. Metabolism of arginine plays an important role in regulating the functions of immune system cells in mammals. Arginine is a substrate of enzymes NOS and arginase. Arginine depletion, potentially contributs to immunosuppression. The review analyzed the literature data on the effect of streptococcal arginine deiminase on the metabolism of arginine eukaryotic cells, and discusses immunosuppressive action of the enzyme

Management culture of public servant as a factor of social and economic development of the territory

В статье рассматривается влияние управленческой культуры на социально-экономическое развитие территории.In the article we consider an impact of administrative culture on socioeconomic development of the territory

Velocity Dispersion of Dissolving OB Associations Affected by External Pressure of Formation Environment

This paper presents a possible way to understand dissolution of OB associations (or groups). Assuming rapid escape of parental cloud gas from associations, we show that the shadow of the formation environment for associations can be partially imprinted on the velocity dispersion at their dissolution. This conclusion is not surprising as long as associations are formed in a multiphase interstellar medium, because the external pressure should suppress expansion caused by the internal motion of the parental clouds. Our model predicts a few km s$^{-1}$ as the internal velocity dispersion. Observationally, the internal velocity dispersion is $\sim 1$ km s$^{-1}$ which is smaller than our prediction. This suggests that the dissipation of internal energy happens before the formation of OB associations.Comment: 6 pages. AJ accepte