Chemical analysis of giant stars in the young open cluster NGC 3114

Context: Open clusters are very useful targets for examining possible trends in galactocentric distance and age, especially when young and old open clusters are compared. Aims: We carried out a detailed spectroscopic analysis to derive the chemical composition of seven red giants in the young open cluster NGC 3114. Abundances of C, N, O, Li, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd were obtained, as well as the carbon isotopic ratio. Methods: The atmospheric parameters of the studied stars and their chemical abundances were determined using high-resolution optical spectroscopy. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. The abundances of the light elements were derived using the spectral synthesis technique. Results: We found that NGC 3114 has a mean metallicity of [Fe/H] = -0.01+/-0.03. The isochrone fit yielded a turn-off mass of 4.2 Msun. The [N/C] ratio is in good agreement with the models predicted by first dredge-up. We found that two stars, HD 87479 and HD 304864, have high rotational velocities of 15.0 km/s and 11.0 km/s; HD 87526 is a halo star and is not a member of NGC 3114. Conclusions: The carbon and nitrogen abundance in NGC 3114 agree with the field and cluster giants. The oxygen abundance in NGC 3114 is lower compared to the field giants. The [O/Fe] ratio is similar to the giants in young clusters. We detected sodium enrichment in the analyzed cluster giants. As far as the other elements are concerned, their [X/Fe] ratios follow the same trend seen in giants with the same metallicity.Comment: 17 pages, 9 figures, 10 tables; accepted for publication in A&

Dual Drug Release of Triamterene and Aminophylline from Poly (N-Isopropylacrylamide) Hydrogels

We used temperature‐sensitive poly(N‐isopropylacrylamide) hydrogels as drug delivery systems, so changes in body temperature induced by pathogens could act like external stimuli to activate controlled release of the drugs incorporated in the hydrogel. In the distilled water combined release studies, we chose two model drugs: aminophylline and triamterene. The amount of drug released was measured by UV‐Vis spectroscopy following the evolution of the absorption peaks of aminophylline (271 nm) and triamterene (365 nm). The maximum release time was greater for triamterene than for aminophylline at 37 oC, so these time‐release profiles enabled the active ingredients to work over different periods of time. By increasing molar mass or solubility of the drug, we observed that the diffusion coefficient decreased. On the contrary, increasing hydrophobicity of the drug leads to a diffusion coefficient increase. The evolution of pore size distribution of hydrogels during loading and releasing was measured by quasi‐elastic light scattering and by environmental electronic scanning microscope. When loading and releasing the drugs, the pore size of the hydrogel decreased and increased again without reaching the initial pore size of the hydrogel, respectively. We observed that the greater the concentration of drug loaded into the hydrogel, the greater the reduction in pore size

Electrocardiografía clínica: taquiarritmias supraventriculares de origen atrial

Las arritmias se pueden definir como “cualquier anormalidad en la frecuencia, regularidad o sitio de origen del impulso cardiaco o trastorno de la conducción que produce una alteración de la activación auricular o ventricular”; mientras que taquicardia se define como “frecuencia cardiaca en adultos, mayor de 100 latidos por minuto (lat/ min.)”. Por tanto, las taquiarritmias supraventriculares son “aquellas taquicardias que requieren tejido atrial o de conducción atrioventricular para su iniciación y mantenimiento”. En este artículo se expondrán las características electrocardiográficas de aquellas provenientes del tejido auricular. (DUAZARY 2010, 117 - 124

Respuesta del Maíz (Zea Mays L.) a Dos fuentes Nitrogenadas (Urea y Nitroform)

Este ensayo fu é realizado en la Zona Bananera, región de Sevilla, Municipio de Ciénaga, en la Estación Experimental "Caribia" del Instituto - Colombiano Agropecuario. Geográficamente la zona está enmarcada dentro de las siguientes coordenadas 740 8' 30" de longitud oeste y 10° 11' - O" de latitud norte. La zona está situada a 20 m. sobre el nivel del - mar, con una temperatura media anual de 30.4°C con una humedad relativa del 84% y una precipitación anual de 1.371 m.m. de lluvia. El trabajo consistió en una fertilización nitrogenada en marz (variedad ICA V-106) con Urea y Nitroform. Para tal efecto se emplearon tres nive les de Urea (0-100-150 Kg/Ha.) y tres de Nitroform (0-100-150 Kg/Ha.). El diseño utilizado fu é el de bloques al azar. El número total de trata mientos fu é de 9 con tres replibaciones, lo que da un total de 27 paree las. El círea de cada parcela fue de 19.2 metros cuadrados y un área total de 518.4 metros cuadrados con un área efectiva de 172.8 metros cuadrados. La siembra se hizo al chorrillo y se fertilizó planta por planta cubrien do posteriormente el fertilizante aplicado. El tiempo de duración del ensayo fué de 98 dras. Si hubo respuesta signi ficativa de los tratamientos. Los mejores resultados correspondieron a - - 33 - los tratamientos 1, 3, 2 y 8 respectivamente. La mayor producción fu é de 3.764.6 Kg/Ha, de maíz que corresponde al - tratamiento número 1, donde se aplicó 100 Kg. de Urea. De acuerdo con la prueba de Duncan los tratamientos 1, 3, 2 y 8 fueran significativos respecto a los demás tratamientos. Los resultados promedios obtenidos nos indican que hubo un aumento de 906 Kg/Ha., lo que representa un 31% de incremento debido al efecto de la aplicación de la fertilización ensayada

Acceso al crédito como determinante del crecimiento económico en Colombia 1997-2011

En este artículo se analiza como el acceso al crédito es determinante del crecimiento económico en Colombia desde 1997 hasta el 2011 a través de datos trimestrales con variación porcentual anual. Recurriendo a un modelo de regresión lineal múltiple, cerca de la mitad del comportamiento del crecimiento real de la economía es explicado por el crecimiento real de la cartera comercial más leasing, el crecimiento real de la cartera consumo más leasing, el crecimiento real de la cartera microcrédito más leasing y el crecimiento real de la cartera vivienda. La explicación de estos sobre la variación real del Producto Interno Bruto PIB3 es la misma sin o con crisis económica nacional

Application of Tiab's Direct Synthesis technique to transient pressure response of non-Newtonian fluids in vertical wells

Non-Newtonian fluids are very common during drilling, fracture operations and enhanced oil recovery processes. When a reservoir contains a non-Newtonian fluid such as those injected during polymer flood or the production of heavy oil, well test data cannot be interpreted using Newtonian fluid flow models. The resulting analysis would be erroneous because non-Newtonian fluids behave rather differently. These results suggest the need for a thorough study of the behavior of non-Newtonian fluids in the reservoir and also a new look at the flow of those fluids in porous media. This study presents an interpretation technique for pressure behavior of non-Newtonian fluid flow in a homogeneous reservoir without type-curve Matching. The inclusion of a no-flow and/or a constant pressure line is also investigated. First, the TSD (Tiab's Direct Synthesis) technique was applied for analyzing the pressure behavior of a well located in (1) an infinite reservoir and, (2) near a linear boundary where wellbore storage and skin effects were considered. The analysis required the generation of type-curve sets for different wellbore storage and skin values. A step-by-step procedure is presented for the calculation of the reservoir parameters: the permeability/viscosity ratio, wellbore storage coefficient, skin factor and the distance to the nearest boundary without the use of type-curve Matching. The procedure is illustrated by a numerical example

Dispersión de luz del PMMA en disolución

Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias, Sección de Químicas, 1971.Fac. de Ciencias QuímicasTRUEProQuestpu

Abundâncias químicas em associações estelares jovens caso AB DORADUS.

Apresentamos neste trabalho os parâmetros estelares, metalicidade e abundância do Lítio para as estrelas da associação AB Doradus, determinadas através de fotometria e espectroscopia. A fotometria utilizada foi obtida da literatura e de por Torres et al. (2006a) e os espectros de alta resolução foram obtidos com os espectrógrafos FEROS (telescópio de 1, 52m do ESO) e Coudé (telescópio de 1, 60m do OPD). Os parâmetros atmosféricos foram determinados através de fotometria, utilizando as calibrações fotométricas de Alonso et al. (1996b) e Houdashelt et al. (2000) e espectroscopia, através razões de linhas de Padgett (1996), curvas de crescimento (Spite e Spite 1967) e síntese espectral (Gray & Corbally 1994). Os parâmetros determinados para as estrelas estão na faixa de Tef = [4486, 6031]K, log(gs) = [3.90, 4.60], [Fe/H] = [−0.20, 0.15], Vmt = [1.00, 2.50]Km/s e log(N(Li)) = [0.64, 2.89]. Nossos resultados confirmam que as estrelas identificadas por Torres et al. (2006a), como membros da associação, são estrelas jovens e tem parâmetros e abundâncias compatíveis com a pertinência à associação AB Doradus. Os resultados mostram também concordância com as hipóteses levantadas por Travaglio et al. (2001) com relação ao comportamento do Lítio na pré-sequência principal e na sequência principal