1,906 research outputs found

    Simulación de una cámara de combustión parauna microturbina de gas utilizando el programa de dinámica de fluidos fluent

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    En este artículo muestra los resultados de la simulación de una cámara de combustión diseñada y construida por estudiantes y docentes de la facultad de Ingeniería Mecánica de la Universidad Tecnológica de Pereira; integrantes del grupo de investigación de Sistemas Térmicos y Potencia mecánica. La cámara de combustión en cuestión, ha hecho parte de dos proyectos finales de grado de cuatro estudiantes de la facultad. El primero fue el diseño y construcción; el segundo de mejoras, pruebas y puesta a punto. La simulación fue realizada con el programa de dinámica de fluidos FLUENT y tiene como objeto principal validar los resultados obtenidos en los procesos de diseño y puesta a punto

    Simulación de una cámara de combustión parauna microturbina de gas utilizando el programa de dinámica de fluidos fluent

    Get PDF
    En este artículo muestra los resultados de la simulación de una cámara de combustión diseñada y construida por estudiantes y docentes de la facultad de Ingeniería Mecánica de la Universidad Tecnológica de Pereira; integrantes del grupo de investigación de Sistemas Térmicos y Potencia mecánica. La cámara de combustión en cuestión, ha hecho parte de dos proyectos finales de grado de cuatro estudiantes de la facultad. El primero fue el diseño y construcción; el segundo de mejoras, pruebas y puesta a punto. La simulación fue realizada con el programa de dinámica de fluidos FLUENT y tiene como objeto principal validar los resultados obtenidos en los procesos de diseño y puesta a punto

    Morphometric relations for body size and mouth dimensions for four fish species in the Strait of Gibraltar

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    Background. The deep-water longline fishery of the blackspot seabream, Pagellus bogaraveo, is an economically important fishery in the Strait of Gibraltar, which is a very complex transition ecosystem between the Mediterranean Sea and the Atlantic Ocean with an extreme spatial and temporal variability. This paper presents a series of morphometric relations for the four most important species in this fishery. Some ecological considerations about the results are also discussed. Materials and methods. The data were collected during a gear selectivity study, using different sizes of hooks baited with sardine. Relations for weight–length, length–length, and mouth dimensions for blackspot seabream, Pagellus bogaraveo (Brünnich, 1768); Atlantic pomfret, Brama brama (Bonnaterre, 1788); blackbelly rosefish, Helicolenus dactylopterus (Delaroche, 1809); and Mediterranean horse mackerel, Trachurus mediterraneus (Steindachner, 1868) were estimated and compared with the ones reported for the same species from other areas. Results. The sample size varied from 89 for T. mediterraneus to 2180 for P. bogaraveo. The fitted L–W relations explained more than 81% of the variance. For P. bogaraveo and T. mediterraneus, the estimated allometric coefficient was higher than those reported for other areas, showing a faster increase in weight, in contrast to H. dactylopterus and B. brama that showed a slower increase in weight. Moreover, linear and highly significant relations between mouth size and fish length were found for P. bogaraveo, H. dactylopterus, and T. mediterraneus. Conclusion. In this study, the first record for total length–standard length relation for H. dactylopterus is reported based on real measurements. There has been no previous studies on the relation between the different mouth size dimensions for the studied species as well as for mouth size and body length relations for P. bogaraveo and H. dactylopterus. The difference between estimated and reported coefficients might be attributed to different environmental adaptations and to the size ranges used due to the gear-size selectivity

    Cerebral Infarction Associated with Cocaine Use

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    We report the case of a young man with an acute infarction of the left putamen and caudate nucleus, whose symptoms appeared six hours after intranasal use of approximately 0.5 g of cocaine hydrochloride. It seems probable that in this patient cocaine consumption played a role in the development of stroke

    Light‐Emitting Diodes: Progress in Plant Micropropagation

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    In commercial micropropagation laboratories, the light source is one of the most important factors controlling plant morphogenesis and metabolism of plant cells and tissue and organ cultures. Lamp manufacturers have begun to rate lamps specifically for plant needs. The traditional light source used for in vitro propagation is fluorescent lamps (FLs). However, power consumption in FL use is expensive and produces a wide range of wavelengths (350–750 nm) unnecessary for plant development. Light‐emitting diodes (LEDs) have recently emerged as an alternative for commercial micropropagation. The flexibility of matching LED wavelengths to plant photoreceptors may provide more optimal production, influencing plant morphology and chlorophyll content. Although previous reports have confirmed physiological effects of LED light quality on morphogenesis and growth of several plantlets in vitro, these study results showed that LED light is more suitable for plant morphogenesis and growth than FLs. However, the responses vary according to plant species. This chapter describes the applications and benefits of LED lamps on chlorophyll in plant micropropagation. Two study cases are exposed, Anthurium (Anthurium andreanum) and moth orchids (Phalaenopsisis sp.), both species with economic importance as ornamental plants, where LEDs have a positive effect on in vitro development and chlorophyll content

    Casein phosphopeptides drastically increase the secretion of extracellular proteins in Aspergillus awamori. Proteomics studies reveal changes in the secretory pathway

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    <p>Abstract</p> <p>Background</p> <p>The secretion of heterologous animal proteins in filamentous fungi is usually limited by bottlenecks in the vesicle-mediated secretory pathway.</p> <p>Results</p> <p>Using the secretion of bovine chymosin in <it>Aspergillus awamori </it>as a model, we found a drastic increase (40 to 80-fold) in cells grown with casein or casein phosphopeptides (CPPs). CPPs are rich in phosphoserine, but phosphoserine itself did not increase the secretion of chymosin. The stimulatory effect is reduced about 50% using partially dephosphorylated casein and is not exerted by casamino acids. The phosphopeptides effect was not exerted at transcriptional level, but instead, it was clearly observed on the secretion of chymosin by immunodetection analysis. Proteomics studies revealed very interesting metabolic changes in response to phosphopeptides supplementation. The oxidative metabolism was reduced, since enzymes involved in fermentative processes were overrepresented. An oxygen-binding hemoglobin-like protein was overrepresented in the proteome following phosphopeptides addition. Most interestingly, the intracellular pre-protein enzymes, including pre-prochymosin, were depleted (most of them are underrepresented in the intracellular proteome after the addition of CPPs), whereas the extracellular mature form of several of these secretable proteins and cell-wall biosynthetic enzymes was greatly overrepresented in the secretome of phosphopeptides-supplemented cells. Another important 'moonlighting' protein (glyceraldehyde-3-phosphate dehydrogenase), which has been described to have vesicle fusogenic and cytoskeleton formation modulating activities, was clearly overrepresented in phosphopeptides-supplemented cells.</p> <p>Conclusions</p> <p>In summary, CPPs cause the reprogramming of cellular metabolism, which leads to massive secretion of extracellular proteins.</p

    Effects of a Respiratory Resistance Mask on Forced Expiratory Volume at 1s (FEV1), Forced Vital Capacity (FVC) and the Ratio of FEV1/FVC Lung Function following High Intensity Training (HIT)

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    Training masks (TMs), marketed as simulated altitude training devices, suggest increased workout capacity, intensity tolerance and recovery. The claim is that the training mask improves respiratory power and breathing mechanics by strengthening the respiratory muscles through breathing resistance provided by the TM. The aim of this study was to compare the effects of a commercially manufactured TM in conjunction with bicycle ergometry, high intensity training (HIT) on selected lung function parameters. Volunteers (N=16) participated in this study and were randomly assigned to an experimental or control group. The experimental group wore the TM with progressive increased respiratory resistance and the control group wore the TM with no respiratory resistance. To determine lung function, pre- and post-test assessments consisted of forced expiratory volume at 1s (FEV1), forced vital capacity (FVC), the ratio of FEV1/FVC. Additionally, to determine the TMs effectiveness of maximal oxygen consumption pre- and post-time to failure during a maximum treadmill test was performed. Training was completed on a cycle ergometer on 3d/wk for 4 wks. Participants exercised at 85% of HRmax with a pedal rate of 100-120 rpm at individually set resistance levels. Training sessions consisted of 10 bouts of 30s exercise followed by 30s of active recovery for a total time of 10 minutes. The respiratory resistance for the experimental group progressively increased over the training period. Repeated measures ANOVAs yielded significant between group difference in FVC (p = 0.02) but not for FEV1 or maximum treadmill time. In conclusion, TMs in combination with HIT failed to improve lung function but created sufficient resistance to strengthen the muscles in respiratory ventilation
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