Radiación solar en la provincia de Tucumán: una comparación entre valores estimados por satélite y medidos por una red solarimétrica

El modelo GL/CPTEC de estimación de radiación solar utiliza imágenes del satélite GOES (canal VIS) para América del Sur, procesándolas en régimen operacional. Los valores estimados para el área del Noroeste Argentino fueron comparados con medidas realizadas en 17 estaciones de la red de estaciones automáticas de la Estación Experimental Agroindustrial Obispo Colombres (EEAOC). Los valores diarios de GL en el trimestre octubre-diciembre de 2010 presentan elevada linealidad (R2>0,93) al comparar con mediciones de la red. En general, promedios trimestrales difieren en menos de 4% en la llanura tucumana y en la región montañosa, y en 4-7% en la región del pedemonte, cercana a la cadena del Aconquija. La desviación estándar de valores diarios en torno del desvío sistemático es de 20-35 W.m-2. Los campos de radiación mensual permiten discernir variaciones espaciales significativas en escala de algunas decenas de kilómetros. Son analizadas algunas fuentes de error y métodos de perfeccionamiento.Model GL/CPTEC assesses solar irradiance using GOES-VIS imagery for South America, being run in a operational scheme. Resultant GL values for Argentine Northwest region were compared with measurements at 17 automatic stations operated by Estación Experimental Agroindustrial Obispo Colombres. Daily GL values during three-month period October-December 2010 exhibit high linearity (R2>0.93) when compared with EEAOC network. Three-month mean values differ fom EEAOC means by less than 4% over eastern Tucumán and by 4-7% nearby mountainous Aconquija slope. Standard deviation of daily values around mean deviation is about 20-35 W.m-2. Monthly mean fields allow discern for space variability meaningful in a several ten-kilometers scale. Some error sources and quality improvements are analyzed.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Purification and In Situ Immobilization of Papain with Aqueous Two-Phase System

Papain was purified from spray-dried Carica papaya latex using aqueous two-phase system (ATPS). Then it was recovered from PEG phase by in situ immobilization or preparing cross-linked enzyme aggregates (CLEAs). The Plackett-Burman design and the central composite design (CCD) together with the response surface methodology (RSM) were used to optimize the APTS processes. The highly purified papain (96–100%) was achieved under the optimized conditions: 40% (w/w) 15 mg/ml enzyme solution, 14.33–17.65% (w/w) PEG 6000, 14.27–14.42% (w/w) NaH2PO4/K2HPO4 and pH 5.77–6.30 at 20°C. An in situ enzyme immobilization approach, carried out by directly dispersing aminated supports and chitosan beads into the PEG phase, was investigated to recover papain, in which a high immobilization yield (>90%) and activity recovery (>40%) was obtained. Moreover, CLEAs were successfully used in recovering papain from PEG phase with a hydrolytic activity hundreds times higher than the carrier-bound immobilized papain

Some features of solar radiation regime in Argentine Northwest region, period 2017-2021

El modelo satelital GL1.2 evalúa irradiancia solar global con alta resolución espacial y error relativamente reducido al considerar promedios mensuales. En este trabajo es aplicado a la región Noroeste de Argentina en el quinquenio 2017-2021 para describir detalles del régimen regional de radiación solar difícilmente discernibles por la poco densa red de solarimetría. El análisis en componentes principales (ACP) muestra que la primera componente (CP1) describe la serie temporal normalizada de 5 años con más de 70% de contribución a la variancia local, excepto en la transición llanura-montaña (piedemonte). En esa región, las componentes CP2 a CP5 acumuladas responden por 95% de la variancia regional. En términos generales, la secuencia normalizada de irradiancia media mensual es adecuadamente descripta por las cinco primeras CPs en toda la región. Los resultados implican en que un número reducido de archivos digitales puede ser utilizado para describir la serie temporal de promedios mensuales con resolución espacial de 0,04° y errores de estimación del orden de 20% del desvío estándar de la serie, o sea, unos 12 W m⁻².Satellite-based model GL1.2 estimates solar irradiance with high spatial resolution and somewhat low error when considering monthly means. It was applied to Northwestern Argentine region for period 2017-2021 in order to describe details hardly detected by the coarse solarimetric network. Principal Components Analysis (PCA) showed that the first one (CP1) closely describes a normalized 5-year time series contributing to more than 70% of local variance, except in transition from plane to mountainous region. Here, components CP2 to CP5 allow for 95% of regional variance. In general, normalized monthly time series are closely described by the first five CPs. These results mean that a reduced number of binary files can be used to describe monthly time series with space resolution 0.04° and errors of about 20% of standard deviation of time series, say about 12 W m⁻².Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Effect of Surface Segmental Mobility on Adhesion of Acrylic Soft Adhesives

The dependence of adhesion on the surface segmental dynamics of polymer substrates in thin-film poly(methyl acrylate) (PMA)- and poly(methyl methacrylate) (PMMA)-adhesive tape systems was probed via tape peel tests. From 90 angle tape peel experiments at 28 C of very thin films of PMA adsorbed on glass slides, it was found that the peel velocities varied linearly with applied force and the force-velocity curves were dependent on film thickness. Extrapolation of the peel-velocity curves to zero velocity yielded an estimate of the fracture energies, which varied from about 50 to 20 J/m2 for thicknesses from 50 to 2000 nm. The fracture energies were also found to depend exponentially on film thickness with a decay length of 110 nm. In contrast to the behavior of PMA, PMMA films showed larger fracture energies but no thickness dependence. The differences in the behavior of the two types of films are believed to be due to differences in segmental mobilities in the films which give rise to differences in the motions of the anchoring sites across the interface. For PMMA, the glassy polymer was rigid at the interface, regardless of the thickness, and hence, no thickness dependence was observed. For PMA, a rubbery polymer at room temperature, the segments at the adhesive interface were influenced by the restrictions posed by interactions of the polymer with the glass surface. A model based on differing thicknesses of the polymer interphases is proposed to account for the behavior observed