Calibración del modelo de Hargreaves para la estimación de la evapotranspiración de referencia en Coronel Dorrego, Argentina

La Organización de las Naciones Unidas para la Agricultura y la Alimentación FAO propone el uso de la ecuación de Penman-Monteith (PM) como el estándar para la estimación de la evapotranspiración de referencia y para la calibración de otras ecuaciones. El principal inconveniente del uso de esta ecuación es que requiere datos que no se tienen en la mayoría de las estaciones. El uso de métodos de cálculos alternativos es usual en la bibliografía. El método de Hargreaves (HG), recomendado por la FAO, es el más usado en la bibliografía cuando sólo se dispone de los datos de temperaturas. El principal objetivo de este trabajo es analizar la posibilidad de calibración y ajuste del método HG en la estación de Coronel Dorrego. Se han comparado los métodos PM y HG, encontrándose una buena correlación entre ambos. Se concluye que el modelo HG es una metodología adecuada, para la zona de Coronel Dorrego y se sugiere la fórmula siguiente: ETo HG = 0,00206⋅Ra⋅(Tmáx-- T mín) 0,49⋅(tm+17,8) mm/día

Bond strength of Epiphany (TM) Sealer combined with different adhesive systems photo-activated with LED and QTH

The Epiphany (TM) Sealer is a new dual-curing resin-based sealer and has been introduced as an alternative to gutta-percha and traditional root canal sealers. The canal filling is claimed to create a seal with the dentinal tubules within the root canal system producing a `monoblock` effect between the sealer and dentinal tubules. Therefore, considering the possibility to incorporate the others adhesive systems, it is important to study the bond strength of the resulting cement. Forty-eight root mandibular canines were sectioned 8-mm below CEJ. The dentine discs were prepared using a tapered diamond bur and irrigated with 1% NaOCl and 17% EDTA. Previous the application Epiphany (TM) Sealer, the Epiphany (TM) Primer, AdheSE, and One Up Bond F were applied to the root canal walls. The LED and QTH (Quartz Tungsten Halogen) were used to photo-activation during 45 s with power density of 400 and 720 mW/cm(2), respectively. The specimens were performed on a universal testing machine at a cross-head speed of 1 mm/min until bond failure occurred. The force was recorded and the debonding values were used to calculate Push-out bond strength. The analysis of variance (ANOVA) and Tukey`s post-hoc tests showed significant statistical differences (P < 0.05) to Epiphany (TM) Sealer/Epiphany (TM) Primer/QTH and EpiphanyTM Sealer/AdheSE/QTH, which had the highest mean values of bond strength. The efficiency of resin-based filling materials are dependent the type of light curing unit used including the power density, the polymerization characteristics of these resin-based filling materials, depending on the primer/adhesive used.