Analysis of the operating parameters in a Stirling cryocooler

In this work, the results obtained in different tests performed on a Stirling cryocooler are shown, as well as a comparative analysis of these results with different load pressures. The prototype is a single-acting Stirling engine with a piston and displacer, which is used to liquefy air with helium as the working fluid; this is an integral Stirling (β-type). A three-phase asynchronous electric motor drives the Stirling engine and cooling, in the hot focus, is performed with a pressurized water circuit. In the cold focus are reached very low temperatures, around 75 K (-198 °C). The study has been developed at different load pressures of the working fluid and it shows a comparative analysis about the most important work parameters evolution. The parameters studied are the following: cooling water inlet and outlet temperatures, cold and hot focus temperatures, voltage and intensity consumed by the electric motor that drives the Stirling engine and quantity of liquid air obtained. The results show that it is very likely to use this configuration in industrial processes when they need cold and heat simultaneously.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Cobalt oxide-Carbon nanocatalysts with highly enhanced catalytic performance for the green synthesis of nitrogen heterocycles through Friedländer condensation.

A novel series of eco-sustainable catalysts developed by supporting CoO nanoparticles on different carbon supports, highly efficient in the synthesis of quinolines and naphthyridines, through the Friedländer condensation, are reported for the first time. Textural properties, dispersion and location of the Co-phase are influenced by the nature of the carbon support, Co-precursor salt and metal loading, having a significant impact on the catalytic performance. Thus, the presence of the mesopores and macropores in carbon aerogels together with the homogeneous distribution of the active phase favours the formation of product 3a as a function of the metal loading. However, an increase in the metal content when using CNTs indicates the formation of CoO aggregates and an optimal concentration of 3 wt% CoO was observed, providing the highest conversion values. The carbon-based catalysts herein reported can be considered to be a sustainable alternative having advantages such as easy preparation, superior stability and notably enhanced catalytic performance, operating at lower temperature and under solvent-free conditions.pre-print815 K

Remote Sensing of Cell-Culture Assays

This chapter describes a full system developed to perform the remote sensing of cell-culture experiments from any access point with internet connection. The proposed system allows the real-time monitoring of cell assays thanks to bioimpedance measurement circuits developed to count the number of cell present in a culture. Cell-culture characterization is performed through the measurement of the increasing bioimpedance parameter over time. The circuit implementation is based on the oscillation-based test (OBT) methodology. Bioimpedance of cell cultures is measured in terms of the oscillation parameters (frequency, amplitude, phase, etc.) and used as empirical markers to carry out an appropriate interpretation in terms of cell size identification, cell counting, cell growth, growth rhythm, etc. The device is capable of managing the whole sensing task and performs wireless communication through a Bluetooth module. Data are interpreted and displayed on a computer or a mobile phone through a web application. The system has its practical application in drug development processes, offering a label-free, high-throughput, and high-content screening method for cellular research, avoiding the classical end-point techniques and a significant workload and cost material reduction

Self-inflicted wound with a nail in the heart: case report

Adequate diagnosis and treatment of penetrating cardiac injury (PCI) represents a great challenge for the surgeon in the emergency department (ED) because of its high mortality. It is estimated that more than 90% of mortality happens before the patient reaches the hospital and only 15---50% of those will receive appropriate medical treatment. Case report: A 42-year-old hemodynamically stable male is brought to the ED with a protruding nail in his thorax. He is taken to the operating room (OR) where a medial sternotomy is performed and an injury is found in the left ventricle. Cardiac muscle repair is performed with pericardial patch. Discussion: PCI from a suicide attempt secondary to a nail hammered into the chest is very rare and no previous reports were found by the author. Conclusion: The objects that penetrate cardiac structures must be removed in a proper OR with capable personnel and the resources available to perform procedures like an urgent thoracotomy or sternotomy

MÉTODO RÁPIDO DE DIAGNÓSTICO DE ROTAVIRUS EN HECES

Los rotavirus humanos (RVH) poseen un genoma de RNA bicatenario, formado por 11 segmentos que presentan una migración electroforética característica para cada cepa. La visualización de los patrones de migración de RNA viral en geles de poliacrilamida (PAGE) se ha vuelto un procedimiento común para la caracterización de las cepas de rotavirus y también como un método diagnóstico de infección viral. El objetivo de este trabajo fue buscar un método rápido de diagnóstico de rotavirus en heces de niños con diarrea aguda, utilizando las técnicas de extracción, separación y tinción descritos por otros autores. El mayor número de muestras positivas a rotavirus se obtuvo con el procedimiento de extracción descrito por Herring et al. (1982), la concentración del RNA viral con etanol absoluto (Sambrook et al., 1989) y la tinción con plata (Herring et al., 1982). La utilización de geles de poliacrilamida al 5% (Chudzio et al., 1989), produjo resultados en menor tiempo. El método descrito resultó de gran especificidad y menor costo que los ensayos inmunoenzimáticos comerciales usados para el diagnóstico de RVH. La sensibilidad del método se probó con especímenes fecales provenientes de niños diarréicos recluidos en la sala de rehidratación del Hospital Universitario “Antonio Patricio de Alcalá” de Cumaná, Venezuela.   PALABRAS CLAVES: Rotavirus, Diagnóstico, Electro-foresis.   ABSTRACT Human rotaviruses (HRV) possess a double-stranded RNA genome, formed by 11 segments that display a characteristic electrophoretic migrating pattern for each strain. The visualization of these viral RNA migration patterns in polyacrylamide gels (PAGE) has become a common procedure in order to characterize HRV strains, and also a method to diagnose viral infections. The purpose of this work was to look for a rapid method to diagnose rotaviruses in the feces of children with acute diarrhea by using extracting, separating and staining techniques described by other authors. The highest number of rotavirus positive samples was obtained with the extracting procedure described by Herring et al. (1982), the concentration of viral RNA with absolute ethanol (Sambrook et al., 1989), and silver staining (Herring et al., 1982). The use of 5% polyacrylamide gels (Chudzio et al., 1989) produced results in the shortest time. The method described in this paper turned out to be of high specificity and of lower cost than the commercial immunoenzymatic tests used for the diagnosis of HRV. The sensitivity of the method was tested with stools from diarrheic children recluded in the rehydration room of the “Antonio Patricio de Alcalá” University Hospital in Cumaná, Venezuela.   KEY WORKS: Rotavirus, Diagnosis, Electrophoresis

Productive and sanitary characterization of suckling calves breeding in Córdoba and Santa Fé (Argentina)

A study has been made in 72 dairy farms in the Argentine provinces of Cordoba and Santa Fe between years 2000 and 2002. This article is mainly referring to the calves in suckling stage, before its transfer to the pasture. The objective was to make a valuation of the main charac-teristics of farms and the breeding system of dairy calves in the zone. A questionnaire was designed, structuring the questions in six different sections: questions of general type, workers, feeding, handling, other species and contagious, and biosecurity and health. Among the results, it emphasizes the big size of farms, the great diffusion of open systems and the little pursuit of biosecurity measures.Se ha realizado un estudio, entre los años 2000 y 2002, en 72 explotaciones bovinas de aptitud láctea situadas en las provincias argentinas de Córdoba y Santa Fé. El estudio se centró principalmente en las primeras fases de producción de terneros, previamente a su traslado a los pastos. El objetivo fue realizar una valoración de las principales características de las explotaciones y el sistema de cría de terneros en la zona. Para ello, se diseñó un cuestionario, estructu-rándose las preguntas en seis apartados: cuestiones de tipo general, personal, alimentación, prácticas de manejo, otras especies y contagio y, bioseguridad y sanidad. Entre los resultados, destaca el gran tamaño de las explotaciones, la amplia difusión de sistemas abiertos y el escaso seguimiento de medidas de bioseguridad

Magnetic susceptibility studies of the spin-glass and Verwey transitions in magnetite nanoparticles

Magnetite nanostructured powder samples were synthesized by aging chemical method. Phase, structural, and magnetic properties were characterized. X-ray diffraction patterns showed cubic magnetite pure phase, with average crystallite size, , equal to 40 nm. Susceptibility measurements showed the well-known Verwey transition at a temperature of 90 K. The decrease of Verwey transition temperature, with respect to the one reported in literature (125 K) was attributed to the low average crystallite size. Moreover, the spin-glass like transition was observed at 35 K. Activation energy calculated from susceptibility curves, with values ranging from 6.26 to 6.93 meV, showed a dependence of spin-glass transition on frequency. Finally, hysteresis loops showed that there is not an effect of Verwey transition on magnetic properties. On the other hand, a large increase of coercivity and remanent magnetization at a temperature between 5 and 50 K confirmed the presence of a magnetic transition at low temperatures

Cáncer paratiroideo como causa de fractura y osteoporosis secundaria en el adulto mayor

Introducción. El carcinoma paratiroideo es infrecuente y más en población geriátrica, afecta el metabolismo óseo y es enmascarado por patologías comunes que causan fracturas de bajo impacto. Objetivo. Ilustrar el cáncer paratiroideo dentro del estudio de las fracturas patológicas y la osteoporosis secundaria, para favorecer el diagnóstico temprano en el adulto mayor. Presentación del caso. Mujer de 71 años con osteoporosis presentó fractura de fémur mientras caminaba. Se evidenció síndrome constitucional, anemia, nefrolitiasis y lesiones osteolíticas; se consideró metástasis óseas versus tumores pardos. Se descartaron neoplasias ginecológicas frecuentes y tumores de células plasmáticas. Estudios tomográficos mostraron nódulo pulmonar y nódulo tiroideo (4 cm), el perfil fosfocálcico indicó hiperparatiroidismo primario, gammagrafía paratiroidea Tc99 MIBI fue negativa. Previa dosis de zoledronato, se realizó exploración de paratiroides, hemitiroidectomía izquierda en bloque y paratiroidectomía superior derecha. Histología e inmunohistoquímica de masa cervical reportó carcinoma de paratiroides. Seguimiento posquirúrgico indicó paratohormona y calcio elevado, e imágenes con metástasis pulmonares. Discusión y conclusión. Las fracturas por osteoporosis son frecuentes, pero ante fracturas atípicas y/o puntaje Z?-2, se deben considerar causas tumorales, infecciosas y evaluación temprana del metabolismo fosfocálcico. El cáncer de paratiroides es más frecuente alrededor de los 50 años, pero puede presentarse a cualquier edad; en adultos mayores comparte características clínicas con entidades prevalentes como osteoporosis posmenopáusica, nefrolitiasis y nódulo tiroideo. El cáncer paratiroideo tiene un espectro clínico amplio y debe ser una posibilidad diagnóstica ante fracturas patológicas o hiperparatiroidismo grave, incluso en ausencia de lesión paratiroidea en un Tc99 MIBI o en presencia de patología tiroidea. El abordaje quirúrgico temprano es la mejor opción terapéutica, y el diagnóstico histológico debe apoyarse en inmunohistoquímica por falta de características citológicas específicas del cáncer paratiroideo

COMPARACIÓN DE TRES MÉTODOS DIAGNÓSTICOS PARA LA DETECCIÓN DE ROTAVIRUS EN HECES DE NIÑOS DIARREICOS

Para encontrar un método diagnóstico de Rotavirus asequible a laboratorios clínicos pequeños, se compararon dos inmunoensayos enzimáticos y un método de electroforesis en gel de poliacrilamida (PAGE). Se comparó la sensibilidad de los métodos entre sí, y la especificidad se determinó por microscopía electrónica de transmisión (MET) como método de referencia. Las tres técnicas resultaron con una sensibilidad del 100%, sin embargo, PAGE tuvo la mayor especificidad (100%), seguido por ELISA no comercial (96%) y por último la ELISA comercial con un (79%). La prueba de PAGE resultó ser la más ventajosa por tener una alta sensibilidad y especificidad de detección de rotavirus, se puede realizar en un tiempo relativamente corto y resulta mucho más económica, a diferencia de las ELISA que cada día elevan sus costos en el comercio.   PALABRAS CLAVES: Rotavirus, ELISA, electroforesis.   ABSTRACT A commercial and a non commercial branded enzyme linked immunoasorbent assays (ELISA) and a polyacrylamide gel electrophoretic assay (PAGE) for detecting human rotavirus from feces, were compared for determining their sensitivity and specificity as criteria to find a reliable analysis of human rotavirus in a basic clinical laboratory. Transmision electron microscope (TEM) was used as reference method to test the specificity of the assays. All the tested assay displayed 100% sensitivity, however PAGE showed 100% specificity followed in a decreasing order by the non commercial (96%) and commercial (79%) ELISA methods. The PAGE assay showed a better sensitivity and specificity than the ELISAs tested and demonstrated to be a most effective, low cost and rapid system for diagnosis of human rotavirus.   KEY WORDS: Rotavirus, ELISA, electrophoresis