Heat transfer enhancement using nanofluids in the compression exchanger in a solar Stirling engine

In this paper a improvement in the heat exchange of a solar Stirling engine during the compression phase was studied. The viability of using nanoparticles as ceramic oxide (Al2O3 in water) at different concentrations instead of conventional refrigerants (water or air) was evaluated. Since these systems could behave as non- Newtonian fluids the dynamic viscosity was measured, as well as other thermophysical properties. The results showed that the convective heat transfer coefficient could raise one order of magnitude respect to the conventional heat transfer fluids at moderately volume fractions (over 0.15).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Characterization and thermophysical properties of rutile and alumina nanofluids

The characterization in relation to shape and particle size of alumina and rutile suspensions was performed. The intrinsic viscosity exhibited the presence of nonspherical aggregates in both suspensions although TEM images showed non monodisperse spherical shape of alumina particles. DLS indicated the existence of particle aggregates for both systems. In all cases, the increase in thermal conductivity with respect to the base fluid is verified. The thermal conductivities obtained experimentally were compared with three mathematical models, which yielded lower values than those measured. From rheological measurements and by means of the Peclet number defined in colloidal suspensions, values of thermal conductivity were also proposed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Crónica de Derecho Procesal 2007

La presente crónica pretende acercar al lector a las distintas reformas de normas procesales que se han producido a lo largo del año 2007 coincidente con el último período de una Legislatura (2004/2008) pródiga en Leyes de carácter social y que han tenido indudable repercusión en el ordenamiento jurídico procesal no sólo por la necesidad de adaptar su contenido a las exi-gencias y previsiones derivadas del nuevo marco jurídico, sino también para posibilitar el cumplimiento de la regulación legal ordenada en las normas que se analizan en este trabajo y que, con una finalidad muy diversa, se han ido promulgando a lo largo del año de referencia. Con todo, una vez más, debemos lamentar la demora en la necesaria y urgente reforma global de la Administración de Justicia, sin duda una de las más importantes tareas legislativas pendientes en la modernización de nuestro ordenamiento jurídico2

Rheological study of the aggregation state of alumina nanofluids

Se adjunta una comunicación, aunque se han publicado tres comunicaciones más.The presence of alumina solid particles in aqueous phase induces a change in the viscosity of the suspension from Newtonian to non- Newtonian flow. Besides, the presence of solid particles is adequate for the use as a heat exchanger fluid. The effect of nanoparticle size on thermal properties of nanofluids is still today a question, which is far from being answered. In this respect, the results reported in the literature are contradictory [1], probably due to the formation of aggregates when particles are dispersed in the liquid phase. Regarding to the nanoparticle shape influence in thermal conductivity, cylinders and spheres have been considered as the more effective in heat transfer. Spherical nanoparticles of alumina, which is one of the most investigated nanofluid, dispersed in water were used in this study. TEM images showed a mean average diameter of 50 nm. However, DLS measurements showed monodispersed particles of 260 nm. Very recently [2], the relationship between shear rheology and aggregation state of suspensions has been reviewed. Mechanical and physical properties of the resultant materials depend on shape, size and size distribution, which are considered determining parameters in the formation of particle aggregates. The steady shear flow (figure 1) has shown that these clusters, when they are at rest, are formed by highly branched aggregates that erode when shear rate increases, until a suspension of individual particles is achieved. These results are in good agreement with the intrinsic viscosity obtained by Money and Krieger-Dougherty models. In both cases, these values are far from the 2.5 corresponding to spherical particles. The temperature effects were also taken into account.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Revisión de métodos para la determinación de pérdidas y eficiencia energética en generadores de vapor

En este trabajo se ha llevado a cabo el análisis de métodos para la determinación de pérdidas y de la eficiencia en calderas de vapor. En primer lugar, se ha desarollado con detalle el procedimiento que sigue cada método para la obtención del rendimiento. A continuación, se ha realizado una clasificación de los métodos en base a distintos factores. Esto permite evaluar y comprender mejor los métodos, observando las diferencias y similitudes existentes entre ellos. Por último, se ha llevado a cabo un análisis cuantitativo de algunos de los métodos. Se han evaluado, para unos mismos datos de entrada, diferentes métodos, de forma que se establecen unas conclusiones de su comportamiento.Universidad de Sevilla. Máster en Sistemas de Energía Térmic

PTS and PTSO, two organosulfur compounds from onion by‑products as a novel solution for plant disease and pest management

This research has been carried out within the project GRUPO OPERATIVO SALUD-OLIVAR from the Spanish Rural Development Program (2014-2020) funded by the Spanish Ministry of Agriculture, Fisheries and Food and co-financed by 80% by the European Agricultural Fund for Rural Development (FEADER) (Total investment 384.830,96 EUR). It has also received funding from European Union's Horizon 2020 research and innovation program under Grant agreement no. 887281 (BIOVEXO).This study is part of the Industrial Doctorate of the doctoral student Ana Falcon Pineiro, granted by the State Research Agency of the Spanish Government, with the following reference: DIN2019-010792.Background Over the past decade, the great impact of agricultural crop diseases has generated considerable economic losses and has compromised the production of edible crops at a time when the world population is only expected to rise, leading to the search for new pest management strategies. Besides that, the environmental impact resulting from the continued use of chemical pesticides has led to the search for natural and sustainable alternatives. One of the existing solutions that currently stands out for its effectiveness is the use of bioactive plant extracts. This study aims to evaluate the antimicrobial activity of propyl propane thiosulfinate (PTS) and propyl propane thiosulfonate (PTSO), two organosulfur compounds (OSCs) derived from Allium cepa, against a wide range of target bacteria and fungi. To this end, various in vitro procedures were conducted as well as soil sanitization tests using sterile substrate inoculated with soil-borne pathogens. In addition, this study also evaluates the pesticidal activity of both compounds through in vitro mortality and repellence tests. Results PTS and PTSO revealed inhibition activity on all the pathogens tested, belonging to different taxonomic groups. Moreover, both significatively reduced the population of bacteria and fungi in soil. The quantification of active substances in soil carried out in parallel to the microbial quantification showed that their use reduces the risk of residue accumulation since they break down quickly when applied. The set of antimicrobial tests performed demonstrated that the antifungal effect of both compounds is higher than the bactericidal effect. Lastly, PTS and PTSO showed a concentration-dependent significant biocidal and repellent effect against aphids. Conclusions The results presented in this work demonstrate that both PTS and PTSO have a significant antimicrobial and pesticidal activity against the great majority of phytopathogens tested, being a promising tool to improve pest management in crops.Spanish Ministry of Agriculture, Fisheries and FoodEuropean Agricultural Fund for Rural Development (FEADER)European Union’s Horizon 2020 research and innovation program 887281State Research Agency of the Spanish Government DIN2019‑01079

La corrupción política: una revisión de la literatura

Si bien la corrupción ha sido tradicionalmente un tema de interés para diferentes disciplinas, desde la década de los ochenta el fenómeno ha recibido una atención sin precedentes. Desde entonces se ha producido una extensa literatura sobre diferentes aspectos de la corrupción, que utilizan diversas herramientas analíticas. En este trabajo se hace una revisión de la literatura más relevante sobre la definición y medición de la corrupción, sus causas, consecuencias y posibles soluciones

Management of choledochal cysts:: 23 years of experience in a pediatric tertiary center

Introduction: Choledochal cyst is a rare pathology of the biliary tree, leading to hepatic cirrhosis and predisposition to malignancy if untreated. Excision and biliodigestive reconstruction is the standard treatment. Our objective in this study is to perform a retrospective analysis of choledochal cysts cases in our institution, focusing in diagnostic imaging and surgical management.Methods and materials: We analysed the medical records from patients with choledochal cysts in our institution from January 1994 to December 2017. Our research included gender, symptoms at presentation, age, preoperative and postoperative bilirubin levels, medical imaging, type of dilatation (following the Todani classification), performed surgery, complications and survival in 70 patients.Results: Ultrasonography was the only required exam to the diagnosis in 50 cases (71,4%), and used in 68 cases (97,1%). All Todani type I and IV cases were treated through cyst excision and biliodigestive reconstruction by proximal and distal hepaticojejunostomy through Roux-en-Y. Thirty-one patients were subjected to proximal hepaticojejunostomy. Eight (25,1%) presented postoperative complications, two of which died due to postoperative sepsis. Thirty-eight patients were subjected to distal hepaticojejunostomy. From this group, two patients (5,2%) presented postoperative complications. Thep-value between groups was 0.016.Conclusion: US is the only necessary diagnostic imaging prior to surgery. The surgeon should weight the risk of biliary cancer and postoperative complications upon choosing the height of the anastomosis in choledochal cysts. We preconize that it’s safer to perform a distal hepaticojejunostomy, maintaining the proximal part of a dilated common hepatic duct, than proximal hepaticojejunostomy.Keywords: Choledochal; Cyst; Management; Hepaticojejunostomy; Ultrasonography

LA CORRUPCIÓN POLÍTICA: UNA REVISIÓN DE LA LITERATURA

Si bien la corrupción ha sido tradicionalmente un tema de interés para diferentes disciplinas, desde la década de los ochenta el fenómeno ha recibido una atención sin precedentes. Desde entonces se ha producido una extensa literatura sobre diferentes aspectos de la corrupción, que utilizan diversas herramientas analíticas. En este trabajo se hace una revisión de la literatura más relevante sobre la definición y medición de la corrupción, sus causas, consecuencias y posibles soluciones.