RESUMO
Fumed silica nanoparticles with 14 nm of diameter were blended with poly(methylmethacrylate), PMMA, by means of a high energy ball milling process. AFM analysis revealed how this process of blending allows obtaining a very homogeneous dispersion of the nanoparticles within the PMMA. Furthermore, it was observed that the properties of the composite are highly dependent on the active milling time: (i) SEM inspection showed that the particle size of the silica-PMMA nanocomposite decreases and (ii) DSC analysis demonstrated that the Tg also decreases due to a reduction in the molecular weight of the PMMA caused by chain scission during the high energy blending process. Two Tg's were obtained in the case of the nanocomposite when milling times were higher than 6 h, one of them being even higher than that of the PMMA without being subjected to the HEBM process. This result was assigned to surface-induced molecular weight segregation near the nanoparticles surface. It has been demonstrated the possibility of preparing transparent nanocomposites with excellent moldability.
RESUMO
BACKGROUND: To evaluate exophthalmos by Hertel exophthalmometer (HE) compared to computed tomography (CT), and extraocular muscle width on CT and its relation with the clinical course in patients with thyroidal ophthalmopathy. METHODS: On reviewed 118 orbits from 59 patients (50 women, mean age 40.6 y., range 12-84) who suffered a thyroidal ophthalmopathy (Graves' disease, n = 57; Hashimoto's thyroiditis, n = 2). Muscle width was evaluated using coronal and mid-axial scans in all cases. Medial rectus (MR) width was analysed by Hallin and Feldon technique. RESULTS: Exophthalmos by HE was 22.5 +/- 2.5 and 23.2 +/- 3.2 mm (right-RE/left eye-LE), and CT 20.8 +/- 3.2 and 20.9 +/- 2.9 mm (p < 0.00001, r = 0.72 and 0.65, respectively). MR width on mid-axial scan was 4.1 +/- 1.6 and 4.2 +/- 1.5 mm (RE/LE). On coronal scans, MR was the muscle more often enlarged followed by superior, inferior and lateral rectus. CONCLUSIONS: Exophthalmos measured by HE was greater than by CT-measured one, but with a good correlation. Muscle were not equally affected, being MR the most frequently enlarged. MR-width was not related to duration and severity of disease.
