EFFECT OF Al₂O₃ ADDITIONS ON THE DIELECTRIC PROPERTIES OF A PORCELAIN INSULATOR PREPARED FROM ECONOMICAL NATURAL RAW MATERIALS

The aim of this work was to determine the effect of an Al₂O₃ addition on the dielectric properties of a porcelain insulator prepared from local Algerian raw materials. The new selected composition was 45 wt% kaolin, 30 wt% potash-feldspar and 25 wt% quartz. In order to find a relationship between the properties and the sample microstructures, the samples were analysed by SEM analysis, X-ray diffraction and Raman spectroscopy. The optimum sintering conditions gave a higher bulk density (2.50 g.cm−3). Dielectric measurements of porcelain insulator were carried out at 1 KHz from room temperature to 200 °C. The dielectric constant, loss factor, dielectric loss tangent and resistivity of the porcelain insulator sample containing 8 wt% Al₂O₃ sintered at 1160 °C for 2 h were: 45-50, 0.14-2.48, 0.005-0.08, and 0.9- 9 x 1013 W.cm, respectively. The value of the dielectric constant was significantly high when compared to that of that of conventional porcelains, which did not exceed generally 9

Spontaneous acute intussusception in a pregnant woman

Acute intussusception in adults is rare and particularly so in pregnant women. Its incidence ranges from 0.067% to 0.0015% (Choi et al., 2005 Choi et al. (2005) [1]). The non-specific presenting symptoms may be attributed to the pregnancy itself, making the diagnosis difficult. When it happens, however, it causes considerable morbidity and mortality for the pregnant woman and the fetus. In adults, such intussusceptions are mainly secondary to an intestinal disease and frequently a tumor. We present the case of a 21-year-old pregnant woman who was diagnosed of spontaneous acute intussusception at nine weeks of gestation and therapeutic management