Publications by authors named "Roman Cabrera-Sierra"

Two heat treatments were carried out at below (Ti6Al4V) and above (Ti6Al4V) the beta-phase transformation temperature (T = 980 °C), to study the effect of microstructural changes on osseointegration. The alloys were implanted in the femurs of hind legs of Wistar rats for 15, 30, and 60 days. Histology of the femur sections obtained for the first 15 days showed inflammatory tissue surrounding the implants and tissue contraction, which prevented osseointegration in early stages.

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Two heat treatments were carried out below (Ti6Al4V) and above (Ti6Al4V) Ti6Al4V beta-phase transformation temperature (980 °C), with the purpose of studying the effect of microstructure on the adhesion and proliferation of fibroblast cells, as well as their electrochemical behavior. These alloys were seeded with 10,000 L929 fibroblast cells and immersed for 7 days in the cell culture at 37 °C, pH 7.40, 5% CO₂ and 100% relative humidity.

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In an effort to examine the effect of the microstructural changes of the Ti6Al4V alloy, two heat treatments were carried out below (Ti6Al4V) and above (Ti6Al4V) its β-phase transformation temperature. After each treatment, globular and lamellar microstructures were obtained. Saos-2 pre-osteoblast human osteosarcoma cells were seeded onto Ti6Al4V alloy disks and immersed in cell culture for 7 days.

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From electrochemical techniques (cyclic voltammetry, potential steps, and EIS), XRD, and SEM-EDX, the kinetics and mechanism of anodic film formation applying anodic potential steps on steel immersed in sour acid media was determined. It was found, from a thermodynamic analysis, based on equilibrium phase diagrams of the system considered in this work, that iron oxidation may produce different new solid phases, depending on the applied potential, the first being the iron oxidation associated with formation of FeS((c)) species, which in turn can be reoxidized to FeS(2(c)) or even to Fe(2)O(3(c)) at higher potential values. From analysis of the corresponding experimental potentiostatic current density transients, it was concluded that the electrochemical anodic film formation involves an E(1)CE(2) mechanism, whereby the first of the two simultaneous processes were the Fe electrochemical oxidation (E(1)) followed by FeS precipitation (C) that occurs by 3D nucleation and growth limited by mass transfer reaction and FeS oxidation (E(2)) forming a mix of different stoichiometry iron sulphides and oxides.

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Synopsis of recent research by authors named "Roman Cabrera-Sierra"

  • - Roman Cabrera-Sierra's research predominantly focuses on the impact of heat treatments on the microstructural properties of titanium alloys, particularly Ti6Al4V, and their subsequent biological responses, notably osseointegration and cellular behavior in a biomedical context.
  • - His studies have revealed that the microstructure of Ti6Al4V alloys, influenced by different heat treatments, affects the adhesion, proliferation of fibroblast cells, and osteoblast cellular responses, thereby shedding light on optimizing materials for bone implants.
  • - Cabrera-Sierra's findings indicate that the inflammation and tissue contraction observed in early stages of osseointegration are critical factors that need addressing to enhance implant performance and integration into the body, highlighting the necessity for careful consideration of alloy treatment processes in biomedical applications.