Análisis de la velocidad de difusión molecular de una mezcla binaria alcohol – agua

Este artículo se propone determinar las velocidades de difusión para una mezcla de dos líquidos utilizando de base teórica la difusión molecular, así como la difusividad de los líquidos y sus velocidades. El sistema es alcohol que se transfiere del gas al líquido y agua que se transfiere del líquido al gas. Las velocidades de flujo molares de alcohol y agua son iguales y de sentido contrario. Este caso surge de la aplicación de la ecuación de Hirschfelder modificada para la resolución de cuatro pruebas del sistema, en donde cada corrida se encuentra en diferentes condiciones de mezcla de alcohol-agua para así determinar las velocidades de difusión de cada una. El modelo de Hirschfelder utiliza como variables la difusividad volumétrica (Dv) reportada por la literatura de los líquidos involucrados, las condiciones de presión y temperatura involucradas en el sistema y la relación de las integrales de colisión (ΩD) reportadas por la literatura los líquidos en cuestión para determinar la difusividad en las condiciones finales. Y con esto de base determinar las velocidades de difusión de cada corrida

Effect of vermicompost, worm-bed leachate and arbuscular mycorrizal fungi on lemongrass ( Cymbopogon citratus (DC) Stapf.) growth and composition of its essential oil

The objective of this study was to investigate the effect of vermicompost, worm-bed leachate (WBL) and Glomus mosseae , an arbuscular mycorrhizal fungi (AMF), on growth of lemongrass ( Cymbopogon citratus (DC.) Stapf). A response surface methodology, i.e. a three-level Box Benhen design with three repetitions and three blocks, was applied to optimize biomass production, essential oil yield and its composition. Application rates of Glomus mosseae were 0, 1 or 2 g plant-1, vermicompost 0, 5 or 10 g plant-1 and WBL 0, 10 and 20%. The AMF had no significant effect on the variables tested, but vermicompost had a significant effect on essential oil yield and WBL on essential oil yield, myercene concentration and shoot dry weigh (p < 0.05). It was found that lemongrass fertilized with 2.0 g G. mosseae, 5.0 g vermicompost and 20% worm-bed leachate would yield 0.797% essential oil of which 62.6% was citral

Evolution over Time of Ventilatory Management and Outcome of Patients with Neurologic Disease∗

OBJECTIVES: To describe the changes in ventilator management over time in patients with neurologic disease at ICU admission and to estimate factors associated with 28-day hospital mortality. DESIGN: Secondary analysis of three prospective, observational, multicenter studies. SETTING: Cohort studies conducted in 2004, 2010, and 2016. PATIENTS: Adult patients who received mechanical ventilation for more than 12 hours. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among the 20,929 patients enrolled, we included 4,152 (20%) mechanically ventilated patients due to different neurologic diseases. Hemorrhagic stroke and brain trauma were the most common pathologies associated with the need for mechanical ventilation. Although volume-cycled ventilation remained the preferred ventilation mode, there was a significant (p &lt; 0.001) increment in the use of pressure support ventilation. The proportion of patients receiving a protective lung ventilation strategy was increased over time: 47% in 2004, 63% in 2010, and 65% in 2016 (p &lt; 0.001), as well as the duration of protective ventilation strategies: 406 days per 1,000 mechanical ventilation days in 2004, 523 days per 1,000 mechanical ventilation days in 2010, and 585 days per 1,000 mechanical ventilation days in 2016 (p &lt; 0.001). There were no differences in the length of stay in the ICU, mortality in the ICU, and mortality in hospital from 2004 to 2016. Independent risk factors for 28-day mortality were age greater than 75 years, Simplified Acute Physiology Score II greater than 50, the occurrence of organ dysfunction within first 48 hours after brain injury, and specific neurologic diseases such as hemorrhagic stroke, ischemic stroke, and brain trauma. CONCLUSIONS: More lung-protective ventilatory strategies have been implemented over years in neurologic patients with no effect on pulmonary complications or on survival. We found several prognostic factors on mortality such as advanced age, the severity of the disease, organ dysfunctions, and the etiology of neurologic disease