Effect of the addition of calcium salts on the structure and anticorrosion properties of siloxane-poly(hydroxyethyl methacrylate) hybrid coating applied on Ti-6Al-4V alloy

Siloxane-pHEMA hybrid coatings with the addition of calcium chloride and calcium sulfate during the synthesis of the material were produced by the sol–gel method and deposited on Ti-6Al-4V alloy by dip-coating. The structural characteristics of the hybrid materials were analyzed by means of Nuclear Magnetic Resonance and Small/Wide Angle X-ray Scattering; their morphological properties were analyzed by means of Scanning Electron Microscopy and Atomic Force Microscopy. The electrochemical behavior and resistance to corrosion of hybrid coatings with and without addition of calcium salts were analyzed by means of Electrochemical Impedance Spectroscopy. The results showed that the coatings were homogeneous due to the rigid silica network formed during the polymerization, hydrolysis and reactions of condensation. In the sample, into which calcium sulfate was added, there was a decrease of the average roughness value (15.0 nm), while exhibiting regular topography and good adhesion to the substrate, suggesting that this coating has appealing characteristics for anticorrosive applications. Electrochemical tests in simulated body fluid (that underwent simulation) showed that the coatings with hybrid system showed better properties of a barrier with up to 96 h of immersion, in comparison to samples without coating. Therefore, these coatings showed promising features suitable for anticorrosion applications in biomaterials. Moreover, due to the addition of calcium sulfate, coatings made it possible to convey a good balance between biological and anticorrosion properties and, which in itself allows biocompatibility without compromising resistance to corrosion.Fil: Lima Almeida, Larissa de. Universidade Federal de Sergipe; BrasilFil: Silva Ferreira, Deidyane Wityla Félix da. Universidade Federal de Sergipe; BrasilFil: Andrade Santana, Joseane da. Universidade Federal de Sergipe; BrasilFil: Huck Iriart, Cristián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Kunst, Sandra Raquel. Universidade Federal do Rio Grande do Sul; BrasilFil: Ferreira, Jane Zoppas. Universidade Federal do Rio Grande do Sul; BrasilFil: Oliveira, Cláudia Trindade. Universidade Feevale; BrasilFil: Sarmento, Victor Hugo Vitorino. Universidade Federal de Sergipe; Brasi

Effect of reader experience on variability, evaluation time and accuracy of coronary plaque detection with computed tomography coronary angiography

OBJECTIVE: To assess the effect of reader experience on variability, evaluation time and accuracy in the detection of coronary artery plaques with computed tomography coronary angiography (CTCA). METHODS: Three independent, blinded readers with three different experience levels twice labelled 50 retrospectively electrocardiography (ECG)-gated contrast-enhanced dual-source CTCA data sets (15 female, age 67.3 +/- 10.4 years, range 46-86 years) indicating the presence or absence of coronary plaques. The evaluation times for the readings were recorded. Intra- and interobserver variability expressed as kappa statistics and sensitivity, specificity, and negative and positive predictive values were calculated for plaque detection, with a consensus reading of the three readers taken as the standard of reference. A bootstrap method was applied in the statistical analysis to account for clustering. RESULTS: Significant correlations were found between reader experience and, respectively, evaluation times (r = -0.59, p < 0.05) and intraobserver variability (r = 0.73, p < 0.05). The evaluation time significantly differed among the readers (p < 0.05). The observer variability for plaque detection, compared with the consensus, varied between kappa = 0.582 and kappa = 0.802. Variability of plaque detection was significantly smaller (p < 0.05) and more accurate (p < 0.05) for the most experienced reader. CONCLUSION: Reader experience significantly correlated with observer variability, evaluation time and accuracy of coronary plaque detection at CTCA