Removal of Transition Metals from Contaminated Aquifers by PRB Technology: Performance Comparison among Reactive Materials.

The most common reactive material used for the construction of a permeable reactive barrier (PRB) is zero valent iron (ZVI), however, its processing can generate corrosive effects that reduce the efficiency of the barrier. The present study makes a major contribution to understanding new reactive materials as natural and synthetic, easy to obtain, economical and environmentally friendly as possible substitutes for the traditional ZHV to be used as filters in the removal of three transition metals (Zn, Cu, Cd). To assess the ability to remove these pollutants, a series of batch and column tests were carried out at laboratory scale with these materials. Through BACH tests, four of seven substances with a removal percentage higher than 99% were prioritized (cabuya, natural clinoptilolite zeolites, sodium mordenite and mordenite). From this group of substances, column tests were performed where it is evidenced that cabuya fiber presents the lowest absorption time (≈189 h) while natural zeolite mordenite shows the highest time (≈833 h). The latter being the best option for the PRB design. The experimental values were also reproduced by the RETRASO code; through this program, the trend between the observed and simulated values with respect to the best reactive substance was corroborated.

Patología tumoral ovárica en adolescentes / Ovarian tumor pathology in adolescents

Objetivo: Determinar el perfil de presentación de la patología ovárica tumoral en las mujeres adolescentes. Diseño: estudio retrospectivo y descriptivo. Material y métodos: Se revisó las historias clínicas y los reportes de biopsia de tejido ovárico de 48 adolescentes de 10 a 19 años de edad hospitalizadas en el Servicio de Ginecología del Hospital Nacional Cayetano Heredia, entre julio de 1992 y diciembre de 1998. Se excluyó las adolescentes embarazadas de más de 20 semanas de gestación. Resultados: Los hallazgos más frecuentes fueron cistoadenoma seroso (45,6 por ciento, quiste dermoide (20,8 por ciento), cuerpo lúteo (8,3 por ciento), quiste funcional ovárico (6,3 por ciento), cistoadenofibroma de ovario (6,3 por ciento), disgerminoma (4,2 por ciento), cistoadenoma mucinoso (4,27 por ciento) y cistoadenoma mixto (2,1 por ciento). Conclusiones: La patología tumoral ovárica benigna (37 casos, 77 por ciento) es más frecuente que la maligna (4 casos, 8,3 por ciento) en adolescentes. El perfil de presentación de la patología tumoral ovárica de las adolescentes de nuestro medio es similar a lo publicado en el Perú y en el extranjero.