Monte Carlo Simulations of Peptide Adsorption on Solid Surfaces (Monte Carlo Simulations of Peptide Adsorption)

Monte Carlo (MC) simulations of a short peptide in bulk water and at charged and neutral surfaces were performed. To pursue the objective of finding whether or not the water structure around the peptide changes upon adsorption and how these changes affect the orientation of the peptide at the surface, the water structure around the peptide in the bulk and at charged and neutral surfaces were compared by analyzing the pair correlation functions (PCFs) between selected groups in the peptide and the surrounding water. In general, evidence was obtained that water is not homogeneously distributed over the peptide surface

Utilizando el modelo satelital GL 1.2 en escala diaria como referencia para calibración provisoria de la red EEAOC - Tucumán

En Tucumán, la Estación Experimental Agroindustrial "Obispo Colombres" (EEAOC) dispone de una red de estaciones meteorológicas automáticas con generación continua de datos de irradiancia solar. En este trabajo se contrastan las irradiancias medias diarias de 18 estaciones (período 2017-2021) con los valores obtenidos por el modelo satelital GL1.2 desarrollado en la División de Satélites e Sensores Meteorológicos (DISSM/CGCT/INPE, Brasil). Este modelo ya mostró un buen desempeño en la comparación con datos de piranómetros Kipp & Zonen CM6B y CMP6 de la red automática del INMET (Instituto Nacional de meteorología, Brasil). Se realizó un análisis preliminar de la calidad del GL1.2, comparándolo con datos diarios (primer semestre de 2018) de la red del INMET en una región relativamente homogénea del Brasil en latitud semejante a la de Tucumán, obteniéndose un buen ajuste, por lo que se adoptó el GL1.2 como "piranómetro de referencia" para una calibración provisoria de los datos solarimétricos diarios de la red EEAOC. Los resultados de los estadísticos utilizados para juzgar el ajuste lineal EEAOC vs. GL 1.2 sugieren que el modelo satelital puede utilizarse para la calibración provisoria de la red de Tucumán, con dispersión típica (desviación estándar) de 20 W/m2

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

Algunas características del régimen de radiación solar global en el Noroeste Argentino, período 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

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

Emergent behaviour and phase transitions in spatially distributed multi-cellular metabolic networks

Overflow metabolism is a ubiquitous phenomenon whereby cells in aerobic conditions excrete byproducts of glycolysis, such as lactate or acetate, into the medium in a seemingly wasteful and polluting fashion. Whilst overflow may confer microbes a fitness advantage by allowing them to overcome a finite oxidative capacity, its occurrence in higher organisms is harder to assess. Important insight was however obtained in recent experiments conducted at single-cell resolution, which revealed that accumulation of overflow products in tumor cell cultures known as the Warburg effect arises from imbalances in the dynamic and heterogeneous inter-cellular exchange network through which cells collectively regulate the microenvironment. Here we provide a quantitative characterization of this scenario by integrating metabolic network modeling with diffusion constraints, statistical physics theory and single-cell experimental flux data. On the theoretical side, we clarify how diffusion-limited exchanges shape the space of viable metabolic states of a multi-cellular system. Specifically, a phase transition from a balanced network of exchanges to an unbalanced overflow regime occurs as the mean cellular glucose and oxygen uptakes vary while single-cell metabolic phenotypes are highly heterogeneous around this transition. We then show that time-resolved data from human tumor-stroma cell co-cultures consistently map to this crossover region, supporting the idea that environmental deterioration reflects a failure of coordination among recurrently interacting cells. In summary, our findings suggest that, rather than deriving from multiple independent cell-autonomous processes, environmental control is an emergent feature of multi-cellular systems.Comment: Main(14 pages)+ supporting information(14 pages). Comments are welcom

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

Highly Sensitive Ratiometric Fluorescent Fiber Matrixes for Oxygen Sensing with Micrometer-Spatial Resolution

Oxygen (O2)-sensing matrices are promising tools for the live monitoring of extracellular O2 consumption levels in long-term cell cultures. In this study, ratiometric O2-sensing membranes were prepared by electrospinning, an easy, low-cost, scalable, and robust method for fabricating nanofibers. Poly({\epsilon}-caprolactone) and poly(dimethyl)siloxane polymers were blended with tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride, which was used as the O2-sensing probe, and rhodamine B isothiocyanate, which was used as the reference dye. The functionalized scaffolds were morphologically characterized by scanning electron microscopy, and their physicochemical profiles were obtained by Fourier transform infrared spectroscopy, thermogravimetric analysis, and water contact angle measurement. The sensing capabilities were investigated by confocal laser scanning microscopy, performing photobleaching, reversibility, and calibration curve studies toward different dissolved O2 (DO) concentrations. Electrospun sensing nanofibers showed a high response to changes in DO concentrations in the physiological-pathological range from 0.5 to 20% and good stability under ratiometric imaging. In addition, the sensing systems were highly biocompatible for cell growth promoting adhesiveness and growth of three cancer cell lines, namely metastatic melanoma cell line SK-MEL2, breast cancer cell line MCF-7, and pancreatic ductal adenocarcinoma cell line Panc-1, thus recreating a suitable biological environment in vitro. These O2-sensing biomaterials can potentially measure alterations in cell metabolism caused by changes in ambient O2 content during drug testing/validation and tissue regeneration processes.Comment: 15 pages, 4 figure

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