Homogenization results for chemical reactive flows through porous media

This paper deals with the homogenization of a nonlinear problem mod-elllng chemica! reactive flows through periodically perforated domains. The chemical reactions take place on the walls of the porous médium. The effective behavior of these reactive flows is described by a new elliptic boundary-value problem contalning an extra zero-order term which captures the effect of the chemical reactions

Movimiento de descarga de gases en conductos largos: modelizacion y estudio de una ecuacion parabolica doblemente no lineal

Movimiento de descarga de gases en conductos largos: modelizacion y estudio de una ecuacion parabolica doblemente no linea

On the asymptotic behavior of solutions of a damped oscillator under a sublinear friction term: from the exceptional to the generic behaviors

We show that there are two curves of initial data (xo, vo) for which the solutions x(t) of the corresponding Cauchy problem associated to the equation xtt + |xí|a_1 xt + x — 0, where a G (0,1), vanish after a finite time. By using asymptotic and methods and comparison arguments we show that for many other initial data the solutions decay to 0, in an infinite time, as i-"/í1-")

Dolor bilateral de muslo en paciente en tratamiento con bifosfonatos.

Los Bifosfonatos son utilizados para el tratamiento de osteoporosis en mujeres post menopáusicas. Sus efectos a largo plazo no están completamente establecidos, sin embargo, diversos estudios describen casos de fracturas por estrés o por traumatismos de baja energía a nivel femoral asociadas a tratamientos crónicos con alendronato. El tratamiento de estas fracturas no está completamente claro y persisten discusiones en cuanto a los beneficios del tratamiento médico conservador frente al tratamiento quirúrgico. Describimos el caso de una mujer de 61 años quien consulta por dolor en muslo bilateral de 2 años de evolución y tratamiento con alendronato desde hace más de 15 años. Las radiografías y RMN mostraban signos de fractura por estrés en ambas diáfisis femorales, con reacción cortical. En este caso se decidió tratamiento quirúrgico con enclavado endomedular bilateral.Bisphosphonates are used for treatment of postmenopausal osteoporosis. Long terms effects re - main unclear although several reports describe cases of proximal femur stress fractures or low energy fractures associated with long term alendronate use. However, it is unclear the treatment that require this kind of fractures, and there are discussions about the best decision between medical or surgical care strategy. We describe a case of a 61 years old woman with 2 years bilateral femoral pain and alendronate therapy for more than 15 years. Radio - graphs and MRI images showed bilateral femoral stress fractures and cortical bone reaction. In this case we decide surgical treatment whit bilateral intramedullary nailin

Thermophysical and volumetric study of mixtures {p-cymene¿+¿propan-1-ol} at several temperatures and atmospheric pressure. Modeling with COSMO-RS

Experimental isobaric molar heat capacities at atmospheric pressure have been determined for the mixture {p-cymene + propan-1-ol} every 10 K in the temperature interval (298.8–328.5) K and over the entire composition range with a Calvet type calorimeter. Densities, necessary for calculating heat capacities, have been also measured in similar conditions. Excess molar volumes have been calculated from densities. They are positive at (318.15 and 328.15) K and sigmoidal at (298.15 and 308.15) K with negative values in the zone very rich in propan-1-ol. Excess molar heat capacities have been calculated from the molar heat capacities and show positive values. Both excess molar properties increase as the temperature rises at a given molar fraction. Excess properties are discussed in terms of intermolecular interactions. The solvation model COSMO-RS has been applied to predict the excess molar heat capacities, being the quantitative predictions rather poor

Solubility of gases in fluoroorganic alcohols. Part III. Solubilities of several non-polar gases in water¿+¿1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol at 298.15¿K and 101.33¿kPa

Solubilities of the non-polar gases H2, N2, O2, CH4, C2H6, C2H4, CF4, SF6, and CO2 in the mixture (water + 1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol) at the temperature of 298.15 K and 101.33 kPa partial pressure of gas are reported. A polynomial dependence of the solubilities on the molar fraction of the binary liquid mixture is found. The Henry''s constants at the vapor pressure of water, the standard changes in the Gibbs energy for the solution process and for the solvation process, and the so-called excess Henry''s constant are calculated. The results have been compared with those obtained by Scaled Particle Theory (SPT). A method to compare the solubility of a gas in different liquids is proposed and applied to 2, 2, 2-trifluoroethanol and 1, 1, 1, 3, 3, 3-hexafluoropropan-2-ol

El evento “Younger Dryas” en el norte de suramérica

En el norte de Suramérica y el Caribe existen indicios de la presencia de un evento frío y seco, análogo al “Younger Dryas” (YD) del Atlántico Norte. Las evidencias más contundentes se encuentran en los registros geoquímicos y micropaleontológicos marinos de la Cuenca del Cariaco (Venezuela) y del Abanico del Amazonas, junto con registros palinológicos de alta resolución de los Andes del Norte. Durante este periodo, las tierras altas de los Andes del norte y las cordilleras de Centro América experimentaron descensos de temperatura y pluviosidad y las áreas costeras del norte de Suramérica registraron eventos de surgencia más intensos. Las condiciones climáticas y oceanográficas se encuentran aparentemente relacionadas con un desplazamiento hacia el sur de la Zona de Convergencia Intertropical (ITCZ) y un fortalecimiento de los vientos Alisios del noreste.In northern South America and the Caribbean there are evidences for the presence of a cold and dry event analogous to the Younger Dryas (YD) from the North Atlantic. The most compelling evidences are found in the geochemical and palynological marine records of the Cariaco Basin (Venezuela) and the Amazon fan, and the high-resolution palynological records from the northern Andes. During the YD, the highlands of the Andes and the Central America cordilleras experienced drops in temperature and moisture, at the same time that coastal upwelling in northern South America was more intense. Climate and oceanographic conditions for the YD were apparently related to the southern displacement of the Intertropical Converge Zone (ITCZ) and the strengthening of the northeast Trade Winds

El evento “Younger Dryas” en el norte de suramérica

En el norte de Suramérica y el Caribe existen indicios de la presencia de un evento frío y seco, análogo al “Younger Dryas” (YD) del Atlántico Norte. Las evidencias más contundentes se encuentran en los registros geoquímicos y micropaleontológicos marinos de la Cuenca del Cariaco (Venezuela) y del Abanico del Amazonas, junto con registros palinológicos de alta resolución de los Andes del Norte. Durante este periodo, las tierras altas de los Andes del norte y las cordilleras de Centro América experimentaron descensos de temperatura y pluviosidad y las áreas costeras del norte de Suramérica registraron eventos de surgencia más intensos. Las condiciones climáticas y oceanográficas se encuentran aparentemente relacionadas con un desplazamiento hacia el sur de la Zona de Convergencia Intertropical (ITCZ) y un fortalecimiento de los vientos Alisios del noreste.In northern South America and the Caribbean there are evidences for the presence of a cold and dry event analogous to the Younger Dryas (YD) from the North Atlantic. The most compelling evidences are found in the geochemical and palynological marine records of the Cariaco Basin (Venezuela) and the Amazon fan, and the high-resolution palynological records from the northern Andes. During the YD, the highlands of the Andes and the Central America cordilleras experienced drops in temperature and moisture, at the same time that coastal upwelling in northern South America was more intense. Climate and oceanographic conditions for the YD were apparently related to the southern displacement of the Intertropical Converge Zone (ITCZ) and the strengthening of the northeast Trade Winds

Solubilities of gases in cycloethers. The solubility of 13 nonpolar gases in 2, 5-dimethyltetrahydrofuran at 273.15 to 303.15¿K and 101.32¿kPa

The solubilities of gases in liquids are interesting, not only from a practical point of view, but also because they provide a rigorous touchstone to test the structural models on the liquid state. In this work the solubilities of 13 nonpolar gases, He, Ne, Ar, Kr, Xe, H2, D2, N2, CH4, C2H4, C2H6, CF4, and SF6, in 2, 5-dimethyltetrahydrofuran at five temperatures between (273.15 and 303.15) K and 101.32 kPa partial pressure of gas were measured and the associated thermodynamic functions were calculated. Correlation of data has been made and the capacity of prediction of several typical molecular models of liquids, namely, SPT model, perturbation theory, UNIFAC and COSMO-RS, specifically applied to gas solubilities, has been checked

Molar heat capacities of the mixture {1, 8-cineole + ethanol} at several temperatures and atmospheric pressure

Molar heat capacities at atmospheric pressure have been determined every 5 K for the mixture {1, 8-cineole (1) + ethanol (2)} in the temperature interval (304.7 to 324.5) K and the whole composition range with a Calvet type calorimeter Setaram C80. From the molar heat capacities, excess molar heat capacities have been calculated, their values being positive and increasing as the temperature rises. The solvation model COSMO-RS has been applied to predict the excess molar heat capacities. The model overestimates the values of the excess heat capacities but predicts well the trend of variation of the excess molar heat capacity with the temperature