Assessment of thermohydraulic performance and entropy generation in an evacuated tube solar collector employing pure water and nanofluids as working fluids.

This study conducts a numerical comparison of the thermal performance of three distinct working fluids (pure water, TiO2, and SiO2 water-based nanofluids) within an evacuated tube solar collector using Computational Fluid Dynamics. The study evaluates thermohydraulic performance alongside global and local entropy generation rates, while considering variations in solar radiation values and inlet mass flow rates. Results indicate that nanofluids demonstrate superior performance under low solar radiation, exhibiting higher outlet temperatures, velocities, thermal efficiency, and exergy efficiency compared to pure water. However, at the higher solar radiation level, the efficiency of SiO2 water-based nanofluid diminishes due to its impact on specific heat. Furthermore, the entropy generation analysis reveals significant reductions with TiO2 water-based nanofluid in all the phenomena considered (up to 79 %). The SiO2 nanofluid performance aligns closely with pure water under high radiation value. This investigation offers valuable insights into the utilization of nanofluids in solar collectors across diverse operating conditions, emphasizing their pivotal role in enhancing overall performance.

Performance Comparison of Different Flat Plate Solar Collectors by Means of the Entropy Generation Rate Using Computational Fluid Dynamics.

In this work, a numerical analysis of three different flat plate solar collectors was conducted using their entropy generation rates. Specifically, the Computational Fluid Dynamics (CFD) technique was used to compare the detailed performance of conventional and zigzag tube geometries of flat plate solar collectors (FPCs) in terms of their entropy generation rates. The effects of fluid viscosity, heat transfer, and heat loss of the flat plate solar collectors were considered for the local and global entropy generation rate analyses. Variations on the inlet volumetric flow rate of the FPCs from 1.0 to 9.0 L/min were simulated under the average solar radiation for one year in the state of Guanajuato, Mexico. The results illustrate and discuss the temperatures, pressures, and global entropy generation rates for volumetric flow variations. The velocity, temperature, and pressure distributions and the maps of the local entropy generation rates inside the collectors are presented and analyzed for the case with a flow rate of 3.0 L/min. These results demonstrate that the zigzag geometries achieved higher outlet temperatures and greater entropy generation rates than the conventional geometry for all the volumetric flow rates considered.

Peptidic biofunctionalization of laser patterned dental zirconia: A biochemical-topographical approach.

A dual approach employing peptidic biofunctionalization and laser micro-patterns on dental zirconia was explored, with the aim of providing a flexible tool to improve tissue integration of restorations. Direct laser interference patterning with a femtosecond Ti:Sapphire laser was employed, and two periodic grooved patterns were produced with a periodicity of 3 and 10 µm. A platform containing the cell-adhesive RGD and the osteogenic DWIVA peptides was used to functionalize the grooved surfaces. Topography and surface damage were characterized by confocal laser scanning (CLSM), scanning electron and scanning transmission electron microscopy techniques. The surface patterns exhibited a high homogeneity and subsurface damage was found in the form of nano-cracks and nano-pores, at the bottom of the valleys. Accelerated tests in water steam were carried out to assess hydrothermal degradation resistance, which slightly decreased after the laser treatment. Interestingly, the detrimental effects of the laser modification were reverted by a post-laser thermal treatment. The attachment of the molecule was verified trough fluorescence CLSM and X-ray photoelectron spectroscopy. Finally, the biological properties of the surfaces were studied in human mesenchymal stem cells. Cell adhesion, morphology, migration and differentiation were investigated. Cells on grooved surfaces displayed an elongated morphology and aligned along the patterns. On these surfaces, migration was greatly enhanced along the grooves, but also highly restricted in the perpendicular direction as compared to flat specimens. After biofunctionalization, cell number and cell area increased and well-developed cell cytoskeletons were observed. However, no effects on cell migration were found for the peptidic platform. Although some osteogenic potential was found in specimens grooved with a periodicity of 10 µm, the largest effects were observed from the biomolecule, which favored upregulation of several genes related to osteoblastic differentiation in all the surfaces.

Intoxicación por metanol. Evolución de niveles sanguíneos con hemodiálisis de alto flujo / No disponible

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Papel de los factores natriuréticos (atrial y urodilatina) y antagonistas de la endotelina / Role of natriurético factors (atrial and urodilatin) and endothelin antagonists

El Péptido Natriurético Atrial (PNA) ha sido estudiado en el tratamiento del fracaso renal agudo (FRA). Aunque algunos trabajos ofrecieron resultados alentadores dos estudios randomizados, multicéntricos, con un gran número de enfermos no obtuvieron diferencias frente a placebo. Últimamente dos artículos, con pequeño tamaño muestral han objetivado buenos resultados, pero dados los antecedentes sería recomendable la realización de estudios a mayor escala antes de poder extenderlo en el tratamiento del FRA. (Recomendación B.) La urodilatina también mostró resultados iniciales positivos, pero en un estudio con un mayor número de pacientes tampoco demostró superioridad respecto al placebo (Recomendación A.) La endotelina es una molécula vasoactiva muy importante a nivel renal. En fase experimental se han estudiado las acciones de varios fármacos que bloquean los receptores de la endotelina A o mixtos A/B. Hasta el momento no ha habido estudios en humanos que pudieran ser susceptibles de análisis. (Recomendación A.)

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Our nine-year experience with the self-locating catheter: comparison of malfunction rate with other Tenckhoff catheter variants.

OBJECTIVE: To evaluate catheter-related complications among self-locating and other variants of Tenckhoff catheters. PATIENTS AND METHODS: We studied all self-locating catheters implanted in our hospitals from May/97 to Dec/05. We extended the follow-up to Jun/05. We collected demographic data, causes of catheter withdrawal and dropping of PD. We studied data about technique and catheter related complications. RESULTS: We included 328 catheters in 285 patients. There were 258 self-locating, 55 straight and 15 curled. There was a higher rate of catheter withdrawal due to malfunction in patients with straight or pig-tail catheters than in self-locating ones (log-rank, p < 0.001). CONCLUSION: In our patients, self-locating catheters have a lower malfunction rate than other variants of Tenckhoff catheters.

[What is the opinion of Spanish internists on osteoporosis?]. / 'Qué opinan los internistas españoles de la osteoporosis?

OBJECTIVE: To conduct an opinion survey on osteoporosis in Spanish internists. METHOD: Survey sent by mail and by personal visit to members of the Spanish Internists Society. Collection of data on opinion on the disease, diagnostic and therapeutic attitude and means available (general laboratory analyses, conventional radiology, biochemical markers of bone remodeling, densitometry and ultrasounds) and preference when choosing a certain treatment. RESULTS: A total of 538 internists answered. More than 90% of those surveyed consider that osteoporosis is a disease that should be treated by internists. A total of 93% consider that osteoporosis is a prevalent disease. More than 80% have access to densitometry. CONCLUSIONS: The majority of Spanish internists consider that osteoporosis is a disease that should be treated by internists and that it is a disease that enters into their action scope. In general, they have the means necessary for its study and treatment. Bisphosphonates constitute the drug of choice and calcium and vitamin D supplements are indicated in almost all the cases.

¿Qué opinan los internistas españoles de la osteoporosis? / What is the opinion of Spanish internists on osteoporosis?

Objetivo. Realizar una encuesta de opinión sobre osteoporosis en internistas españoles. Método. Encuesta remitida por correo y por visita personal a miembros de la Sociedad Española de Medicina Interna. Recogida de datos sobre opinión acerca de la enfermedad, actitud diagnóstica y terapéutica y medios disponibles (analítica general, radiología convencional, marcadores bioquímicos de remodelamiento óseo, densitometría y ultrasonidos) y preferencias a la hora de elegir un determinado tratamiento. Resultados. Contestaron un total de 538 internistas. Más del 90% de los encuestados opina que la osteoporosis es una enfermedad que deben tratar los internistas. El 93% considera que la osteoporosis es una patología prevalente. Más del 80% tiene acceso a una densitometría. Conclusiones. Los internistas españoles opinan mayoritariamente que la osteoporosis es una enfermedad que deben tratar los internistas y que entra en su ámbito de actuación. Por lo general disponen de los medios que necesitan para su estudio y tratamiento. Los bifosfonatos constituyen el fármaco de elección y en la práctica totalidad de los casos indican un suplemento de calcio y vitamina D

Objective. To conduct an opinion survey on osteoporosis in Spanish internists. Method. Survey sent by mail and by personal visit to member of the Spanish Internists Society. Collection of data on opinion on the disease, diagnostic and therapeutic attitude and means available (general laboratory analyses, conventional radiology, biochemical markers of bone remodeling, densitometry and ultrasounds) and preference when choosing a certain treatment. Results. A total of 538 internists answered. More than 90% of those surveyed consider that osteoporosis is a disease that should be treated by internists. A total of 93% consider that osteoporosis is a prevalent disease. More than 80% have access to a densitometry. Conclusions. The majority of Spanish internists consider that osteoporosis is a disease that should be treated by internists and that it is a disease that enters into their action scope. In general, they have the means necessary for its study and treatment. Bisphosphonates constitute the drug of choice and calcium and vitamin D supplements are indicated in almost all the cases

Aminoglycoside-associated Fanconi's syndrome: an underrecognized entity.

The Fanconi syndrome is an array of multiple proximal renal tubular dysfunctions occurring in association with several exogenous toxins, such as aminoglycosides. These antibiotics remain the drugs of choice in most gram-negative infections, but nephrotoxicity is the main drawback for them. Furthermore, the nephrotoxic effects may be overlooked with routine analyses. With the purpose of making physicians aware of this underrecognized complication, we are reporting here 3 cases of Fanconi's syndrome related to the administration of high-dose aminoglycosides (ranging from 3.6 to 15 g) with normal serum urea nitrogen and creatinine levels. The pattern of aminoaciduria demonstrated high increases in neutral amino acids, followed by dibasic and near-normal acidic amino acids. We also report the urinary excretion rates of total protein and beta2-microglobulin and protein electrophoresis results. We compared these cases with others reported in the literature.