Microstructural design for mechanical and electrical properties of Spark Plasma Sintered Al2O3-SiC nanocomposites

[EN] Al2O3-17 vol.% SiC nanocomposites were prepared by powder mixture of submicrosized alpha-Al2O3, nanosized gamma-Al2O3 and different nanosized beta-SiC. Materials were sintered by spark plasma sintering (SPS) technique at two temperatures (1400-1550 degrees C) and their electrical conductivity and mechanical properties were investigated. High-density composites have been achieved even at the lowest sintering temperatures and the microstructure characterization shows SiC particles located both within the Al2O3 matrix grains and/or at the Al2O3 grain boundaries. It has been demonstrated that microstructure tailoring is possible by suitable selection of starting materials and fast sintering by SPS. Accurate design of nanocomposites microstructures allows obtaining moderately conductive (<100 Omega cm) or insulating (10(8) Omega cm) materials while the chemical composition is similar. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.Financial support of this work by the European Commission is gratefully acknowledged (IP Nanoker P3-CT-2005-515784). A. Borrell acknowledges the Spanish Ministry of Science and Innovation for Ph.D. grant (MAT2006-01783).Borrell Tomás, MA.; Alvarez, I.; Torrecillas, R.; Rocha, VG.; Fernandez, A. (2012). Microstructural design for mechanical and electrical properties of Spark Plasma Sintered Al2O3-SiC nanocomposites. Materials Science and Engineering: A. 534:693-698. https://doi.org/10.1016/j.msea.2011.12.032S69369853

'Correction:' Serum transforming growth factor beta-1 (TGF-beta-1) levels in diabetic patients are not associated with pre-existent coronary artery disease

<p>Abstract</p> <p>Background</p> <p>The association between TGF-β1 levels and long-term major adverse cardiovascular events (MACE) in patients with coronary artery disease (CAD) is controversial. No study specifically addressed patients with CAD and diabetes mellitus (DM). The association between TGF-β1 levels and long-term major adverse cardiovascular events (MACE) in patients with coronary artery disease (CAD) is controversial. No study specifically addressed patients with CAD and diabetes mellitus (DM).</p> <p>Methods</p> <p>Patients (n = 135, 30–80 years) referred for coronary angiography were submitted to clinical and laboratory evaluation, and the coronary angiograms were evaluated by two operators blinded to clinical characteristics. CAD was defined as the presence of a 70% stenosis in one major coronary artery, and DM was characterized as a fasting glycemia > 126 mg/dl or known diabetics (personal history of diabetes or previous use of anti-hyperglycemic drugs or insulin). Based on these criteria, study patients were classified into four groups: no DM and no CAD (controls, C n = 61), DM without CAD (D n = 23), CAD without DM (C-CAD n = 28), and CAD with DM (D-CAD n = 23). Baseline differences between the 4 groups were evaluated by the χ²test for trend (categorical variables) and by ANOVA (continuous variables, post-hoc Tukey). Patients were then followed-up during two years for the occurrence of MACE (cardiac death, stroke, myocardial infarction or myocardial revascularization). The association of candidate variables with the occurrence of 2-year MACE was assessed by univariate analysis.</p> <p>Results</p> <p>The mean age was 58.2 ± 0.9 years, and 51% were men. Patients with CAD had a higher mean age (p = 0.011) and a higher percentage were male (p = 0.040). There were no significant baseline differences between the 4 groups regarding hypertension, smoking status, blood pressure levels, lipid levels or inflammatory markers. TGF-β1 was similar between patients with or without CAD or DM (35.1 ×/÷ 1.3, 33.6 ×/÷ 1.6, 33.9 ×/÷ 1.4 and 31.8 ×/÷ 1.4 ng/ml in C, D, C-CAD and D-CAD, respectively, p = 0.547). In the 2-year follow-ip, independent predictors of 2-year MACE were age (p = 0.007), C-reactive protein (p = 0.048) and systolic blood pressure (p = 0.008), but not TGF-β1.</p> <p>Conclusion</p> <p>Serum TGF-β1 was not associated with CAD or MACE occurrence in patients with or without DM.</p