RESUMO
Though tungsten trioxide (WO3) in bulk, nanosphere, and thin film samples has been extensively studied, few studies have been dedicated to the crystallographic structure of WO3 thin films. In this work, the evolution from amorphous WO3 thin films to crystalline WO3 thin films is discussed. WO3 thin films were fabricated on silicon substrates (Si/SiO2) by RF reactive magnetron sputtering. Once a thin film was deposited, two successive annealing treatments were made: an initial annealing at 400 °C for 6 h was followed by a second annealing at 350 °C for 1 h. Film characterization was carried out by X-ray diffraction (XRD), high-resolution electron transmission microscopy (HRTEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) techniques. The ß-WO3 final phase grew in form of columnar crystals and its growth plane was determined by HRTEM.
RESUMO
Adrenal response to tolbutamide-induced hypoglycemia was studied in 23 normal men born and living at high altitude (Morococha, Perú, 4,540 m) and compared to 23 men born and living near sea level. Fasting blood sugar was significantly lower in the high altitude dwellers (HAD) and this difference persisted throughout the test period. The blood glucose decrement at 30 min was significantly less in the HAD. Plasma cortisol response was significantly higher at 30 and 60 min in the HAD. Peak cortisol level occurred earlier in the HAD than in men living at sea level. The absolute cortisol increment at 30 min was significantly greater in the HAD.