Investigation of tribological and mechanical properties of Nb-Al-N coatings before and after annealing
Coatings Nb-Al-N were deposited on a silicon substrate under argon and nitrogen by magnetron sputtering at a substrate temperature of 350 °C and a constant current of 250 mA at the aluminum cathode. The analysis of the dependence chemical composition, morphology, structure and mechanical properties of the annealing temperature were performed for different series of coatings. Coatings demonstrated high thermal stability after annealing to 1000 °C.
Investigation of NbN and Nb-Si-N Coatings Deposited by Magnetron Sputtering
Investigation of NbN and Nb–Si–N Coatings Deposited by Magnetron Sputtering V.I. Ivashchenko, P.L. Scrynskyy, O.S. Lytvyn, V.M. Rogozc,∗, O.V. Sobol, A.P. Kuzmenko, H. Komsta and C. Karvat Institute for Problems of Material Science, NASU, Krzhyzhanovsky Str. 3, 03680 Kiev 142, Ukraine Institute of Semiconductor Physics, NASU, Nauky Pr. 41, 03028 Kyiv, Ukraine Sumy State University, Rimsky-Korsakov Str. 2, 40000, Sumy, Ukraine National Technical University “Kharkiv Polytechnic Institute”, Frunze Str. 21, 61002, Kharkov, Ukraine Kursk State Technical University, Center for collective use “High Tech”, 305040, October 50 Str. 94, Kursk, Russia f Institute of Transport, Combustion Engines and Ecology, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland Department of Electrical Devices and High Voltage Technology, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland
Cross talk between redox signalling and metabolic activity of osteoblasts and fibroblasts in the presence of hydroxyapatite-based biomaterials influences bone regeneration
Regeneration of bone tissue defects that result from metabolic disorders, including periodontal diseases, can be supported by biomaterials based on hydroxyapatite. Despite of good biocompatibility of biomaterials they can cause oxidative stress and inflammatory processes as a result of mechanical interaction with surrounding tissues. Because osteoblasts are responsible for bone regeneration process in which gingival fibroblasts may also participate, the aim of the work was to investigate the influence of hydroxyapatite-based biomaterials (allogeneic and xenogeneic) and biomaterials combined with enamel matrix derivative (Emdogain) on osteoblast and fibroblast redox balance in the context of osteoblast proliferation and differentiation.
The results showed that examined substitutes were not cytotoxic in vitro, but affected redox balance of osteoblasts and fibroblasts (ROS level increase and GSH level decrease) which led to oxidative stress (MDA and protein carbonyl groups level increase) resulting in an increase of the Nrf2 and NFκB expression. The consequence of these changes was partial inhibition of proliferation and osteoblast differentiation. Emdogain alone and combined with biomaterials decreased ROS generation and increased GSH level in both osteoblasts and fibroblasts leading to reduction of transcription factors expression especially proinflammatory NFκB, which promoted osteoblast differentiation and mineralization process.