Maximum power, ecological function and efficiency of an irreversible Carnot cycle. A cost and effectiveness optimization

In this work we include, for the Carnot cycle, irreversibilities of linear finite rate of heat transferences between the heat engine and its reservoirs, heat leak between the reservoirs and internal dissipations of the working fluid. A first optimization of the power output, the efficiency and ecological function of an irreversible Carnot cycle, with respect to: internal temperature ratio, time ratio for the heat exchange and the allocation ratio of the heat exchangers; is performed. For the second and third optimizations, the optimum values for the time ratio and internal temperature ratio are substituted into the equation of power and, then, the optimizations with respect to the cost and effectiveness ratio of the heat exchangers are performed. Finally, a criterion of partial optimization for the class of irreversible Carnot engines is herein presented.Comment: 17 pages, 4 figures. Submitted to Energy Convers. Manag

Modesto Armijo Lozano. Diario dedicado a su esposa, Carmenza Mejía Aráuz

Como parte de abonar al estudio de la historia de Centroamérica la doctora Monica Toussaint y el doctor Guillermo Fernández Ampié editaron: Modesto Armijo Lozano, Diario dedicado a su esposa, Carmenza Mejía Aráuz (octubre 1926- julio 19279).Incluido en la colección Testimonios del Instituto Mora. El texto publicado en 2015 puede considerarse una valiosa fuente histórica para analizar la Guerra Constitucionalista nicaragüense (1926-1927) que involucró a los países centroamericanos, Estados Unidos y México. Si bien Modesto Armijo, quien fue parte del gabinete de gobierno de Juan Bautista Sacasa durante la Guerra Constitucionalista, es un personaje poco conocido dentro de la historiografía nicaragüense y centroamericana. La publicación de su Diario es una muestra de que aún a inicios del siglo XXI existen episodios y procesos históricos que no terminan de revisarse, y queda mucho por analizar y develar

El antimperialismo de Froylán Turcios: reflexiones para el estudio de la Revista Ariel

En 2013 viajé a Managua y Tegucigalpa para realizar trabajos de archivo que pudiera fundamentar mi investigación de maestría sobre Augusto C. Sandino y México. De ante mano tenía conocimiento que para poder estudiar seriamente el movimiento sandinista de los años veinte era indispensable consultar Revista Ariel, así que uno de mis principales objetivos dentro de ese proceso de investigación fue encontrar y consultar la publicación dirigida por el intelectual hondureño Froylán Turcios. Después de una interesante travesía pude encontrar la Revista Ariel en Tegucigalpa, sin embargo las condiciones en que se incontraba la colección imposibilitó su consulta. Así que solo pude analizar aquellos ejemplares que no corrían el riesgo de dañarse. Durante el proceso de sistematización de la información recuperada pude dimensionar la importancia que esta publicación y su editor Turcios tuvo en la lucha antiimperialista latinoamericana y en la construcción de una identidad continental durante las primeras décadas del siglo XX. Este artículo tiene la intensión de analizar la Revista Ariel a partir de una serie de variables metodológicas señalando la relevancia de la dimensión política que tuvo esta y el resto de revistas culturales en América Latina, no solo por los temas y debates que albergaron sino por su incidencia en la realidad latinoamericana. El análisis arroja una problemática que debe considerarse al estudiarse el antiimperialismo latinoamericano desde esta perspectiva: la dispersión física de la revista, el descuido de la colección existente y aún más grave, lo incompleto de las mismas

Corrosion study of pipeline carbon steel in sourbrine under turbulent flow conditions at 60°C

This work presents the electrochemical results obtained during the corrosion study of X52 pipeline steel sample, immersed in “sour” solution under turbulent flow conditions at 60°C. In order to obtain information on the corrosion kinetics, weight loss method, linear polarization resistance, impedance and polarization curves were used at different immersion times. In order to control the turbulent flow conditions, a rotating cylinder electrode was used at two different rotation rates, 0 and 1000 rpm. A surface analysis was carried out in order to identify the corrosion morphology and the corrosion product formed on the steel sample. In general, it was found that flow has a considerable influence upon the electrochemical process occurring on the surface of the steel. It was observed as the flow rate increased the corrosion rate also increased. In surface analysis three phases were found, mackinawite (Fe,Ni)  1+xS ,pyrrhothite (Fe(1-x)S) and marcasite (FeS2). In addition, a “localized attack” was found

Porphyromonas gingivalis induce apoptosis in human gingival epithelial cells through a gingipain-dependent mechanism

<p>Abstract</p> <p>Background</p> <p>The oral pathogen <it>Porphyromonas gingivalis </it>has been shown to modulate apoptosis in different cell types, but its effect on epithelial cells remains unclear.</p> <p>Results</p> <p>We demonstrate that primary human gingival epithelial cells (HGECs) challenged with live <it>P. gingivalis </it>for 24 hours exhibit apoptosis, and we characterize this by M30 epitope detection, caspase-3 activity, DNA fragmentation and Annexin-V staining. Live bacteria strongly upregulated intrinsic and extrinsic apoptotic pathways. Pro-apoptotic molecules such as caspase-3, -8, -9, Bid and Bax were upregulated after 24 hours. The anti-apoptotic Bcl-2 was also upregulated, but this was not sufficient to ensure cell survival. The main <it>P. gingivalis </it>proteases arginine and lysine gingipains are necessary and sufficient to induce host cell apoptosis. Thus, live <it>P. gingivalis </it>can invoke gingival epithelial cell apoptosis in a time and dose dependent manner with significant apoptosis occurring between 12 and 24 hours of challenge via a gingipain-dependent mechanism.</p> <p>Conclusion</p> <p>The present study provides evidence that live, but not heat-killed, <it>P. gingivalis </it>can induce apoptosis after 24 hours of challenge in primary human gingival epithelial cells. Either arginine or lysine gingipains are necessary and sufficient factors in <it>P. gingivalis </it>elicited apoptosis.</p

Mamíferos de Pamplona

En esta guía quedan recogidos todos los grupos de mamíferos que tienen presencia en el entorno de Pamplona, así como sus principales características

In vitro modeling of host-parasite interactions: the 'subgingival' biofilm challenge of primary human epithelial cells

BACKGROUND: Microbial biofilms are known to cause an increasing number of chronic inflammatory and infectious conditions. A classical example is chronic periodontal disease, a condition initiated by the subgingival dental plaque biofilm on gingival epithelial tissues. We describe here a new model that permits the examination of interactions between the bacterial biofilm and host cells in general. We use primary human gingival epithelial cells (HGEC) and an in vitro grown biofilm, comprising nine frequently studied and representative subgingival plaque bacteria. RESULTS: We describe the growth of a mature 'subgingival' in vitro biofilm, its composition during development, its ability to adapt to aerobic conditions and how we expose in vitro a HGEC monolayer to this biofilm.Challenging the host derived HGEC with the biofilm invoked apoptosis in the epithelial cells, triggered release of pro-inflammatory cytokines and in parallel induced rapid degradation of the cytokines by biofilm-generated enzymes. CONCLUSION: We developed an experimental in vitro model to study processes taking place in the gingival crevice during the initiation of inflammation. The new model takes into account that the microbial challenge derives from a biofilm community and not from planktonically cultured bacterial strains. It will facilitate easily the introduction of additional host cells such as neutrophils for future biofilm:host cell challenge studies. Our methodology may generate particular interest, as it should be widely applicable to other biofilm-related chronic inflammatory diseases

Levels of insulin and HOMA-IR in adolescents in Saltillo, Coahuila, Mexico

An alarming rise of obesity in adolescents has been observed, placing them at risk of developing resistance to insulin (IR) and its adverse metabolic consequences such as diabetes mellitus type 2 (DM2), metabolic syndrome and cardiovascular disease. Objective: To know the prevalence of obesity, and the levels of glucose, insulin and HOMA-IR and its association with the BMIz, waist circumference and the pubertal stage in a random sample of adolescents. Materials and methods: 292 adolescents between 12 and 15 years (152 female and 140 male), whose anthropometric measurements (weight, height and waist circumference) were taken, body mass index calculated and Z-score determined. Blood glucose and insulin levels were evaluated from a sample of blood and their HOMA-IR was determined. Results: The results showed that 32.5% were obese, 22.3% were overweight and 23.6% showed adolescent central obesity. Glucose levels (p = 0.016), insulin (p = 0.0001) and HOMA-IR (p = 0.0001) showed significant differences in the group with obesity. Values of the three parameters were increased with the stage of puberty. We found significant differences in the levels of glucose (p = 0.0388), insulin (p = 0.0005) and HOMA-IR (p = 0.0001) between the prepubertal and postpubertal stages