The surface condition of an implant has a significant impact on response occurring at the implant-biosystem border. The knowledge of physical-chemical and biological processes allows for targeted ...modification of biomaterials to induce a specified response of a tissue. The present research was aimed at development of technology composing of obtaining the nanotube oxide layers on a porous titanium alloy Ti13Nb13Zr, followed by the deposition of phosphate coating. The porous substrate (porosity about 50%) was prepared by a selective laser melting of the Ti13Nb13Zr powder with the SLM Realizer 100 equipment. The nanotubular oxide layers were fabricated by electrochemical oxidation in H
PO
+ 0.3% HF mixture for 30 min. at a constant voltage of 20V. The calcium phosphate coatings were formed by the electrochemically assisted deposition (ECAD). The presence of nanotubular oxide layers with their internal diameters ranging from 30 to 100 nm was observed by SEM (JEOL JSM-7600F). The nanotubes have dimensions that facilitated the deposition of hydroxyapatite.
The presence of the oxide layers on Zr alloys may retard or enhance the hydrogen entry and material degradation, depending on the layer features. This research has been aimed to determine the effects ...of pre-oxidation of the Zircaloy-2 alloy at a different temperature on hydrogen degradation. The specimens were oxidised in laboratory air at 350°C, 700°C, and 900°C. After, some samples were tensed at 10-5 strain rate and simultaneously charged with hydrogen under constant direct voltage in 1 N sulfuric acid at room temperature. Other specimens were charged without any tension, then annealed at 400°C for 4 h and finally tensed at above strain rate. The SEM examinations were performed on the cross-sections and fracture faces of specimens. The obtained results demonstrate the effects of the oxide layer on the cathodic current and hydrogen entry, mechanical properties and the appearance of hydrides and fracture behaviour.
The research results of corrosion resistance of the Ti6Al4V alloy in the simulated body fluids (SBF) are presented. The polished specimens have shown better corrosion resistance than grinded surfaces ...in both liquids. The artificial saliva has revealed more aggressive test solution than Ringer's solution. The pitting tendency has been observed in Ringer's solution for grinded specimens.
The first records of Sticta weigelii s.str. from Bolivia confirmed by molecular data are presented. The species is characterized by the presence of marginal isidia, which are darker than the thallus, ...usually cylindrical (not flattened), thin, dark brown to black lower tomentum and often partly yellow cyphellae. Previously, the presence of S. weigelii in Bolivia was based only on a morphological concept, encompassing various unrelated species, whereas the occurrence of S. weigelii s.str. was uncertain.
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