25 research outputs found

    Modelización de un absorbedor de burbujas de geometría cilíndrica utilizando la disolución amoniaco-nitrato de litio

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    En este proyecto se realiza un modelo matemático para la predicción del comportamiento de absorbedores de burbujas en máquinas de absorción. Uno de los problemas principales de este tipo de máquinas es la necesidad de disponer de grandes superficies para la transferencia de calor, viendo de esta manera mermada su competencia con máquinas de compresión simple. Los absorbedores de burbujas tienen un diseño que permite la reducción drástica del tamaño de estas máquinas y así poder mejorar el comportamiento de las mismas, convirtiéndolas en un modelo competitivo. ________________________________________________________________________________________________________This project develops a mathematical model for prediction of behavior of bubble absorber in absorption machines. One of the main problems of these machines is the need for having a large surface for heat transfer, looking at it from this point of view diminishes its performance compared to simple compression machines. Bubble absorbers have a design that allows a drastic reduction in size of these machines and thus improves the performance, by making a competitive model.Ingeniería Industria

    Análisis CFD de un flap Gurney instalado en perfiles NACA

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    Hoy en día, la búsqueda de automóviles competitivos se basa en el minucioso estudio de un conjunto de ramas de ingeniería que engloban la mecánica, la electrónica, los neumáticos, suspensiones, aerodinámica... Aunque esta última ha estado hasta hace unos años en un segundo plano, ha pasado a convertirse en un elemento fundamental a la hora de diseñar un vehículo. A menudo nos rodea información sobre automóviles de competición, sobretodo en los últimos años, que en un principio sonaba cómo algo raro y que cada día nos resulta más familiar. Este proyecto no está destinado ni mucho menos a ser un elaborado trabajo de investigación que se convierta en una idea revolucionaria para el campo de la automoción, pero sí intenta explicar cómo se consiguieron resultados sorprendentes de una idea brillante y revolucionaria: el flap Gurney, un pequeño dispositivo colocado en la zona de desprendimiento de alerones en posición perpendicular a los mismos. Intento por tanto, mediante la utilización de herramientas de cálculo computacional de fluidos desarrollar un estudio sobre el interés fundamental de utilizar un mecanismo aerodinámico y demostrar así la valía del mismo. Evidentemente en rasgos generales, no podemos esperar que un simple cambio en la aerodinámica de un vehículo suponga un cambio drástico en la concepción de automóviles, pero si podemos decir que un conjunto de cambios precisos y acertados pueden suponer un revulsivo, y este conjunto de mejoras son necesarios para conseguir la única finalidad que existe en competición, llegar el primero. Habitualmente se realizan estudios de aerodinámica de vehículos comenzando con un estudio simulado por ordenador, en el que se realizan miles de cálculos y con los resultados obtenidos se procede a la realización de los mismos experimentos en túneles de viento. Este proyecto es la primera parte del estudio, realizado con dos programas de diseño: Gambit, herramienta informática destinada al diseño del mallado y Fluent, software encargado del cálculo en sí mediante la aplicación de diversas hipótesis sobre el modelos fluidos. En un primer lugar se diseñaron las mallas de tres alas NACA introduciendo el flap en la parte posterior, a continuación mediante hipótesis de turbulencia se procedió a la toma de datos para diferentes ángulos de ataque.Ingeniería Técnica en Mecánic

    Determination of parathion in biological fluids by means of direct Solid Phase Microextraction.

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    A new and simple procedure for the determination of parathion in human whole blood and urine using direct immersion (DI) solid-phase microextraction (SPME) and gas chromatography/mass spectrometry (GC/MS) is presented. This technique was developed using only 100 ìL of sample, and ethion was used as internal standard (IS). A 65-ìm Carbowax/divinylbenzene (CW/DVB) SPME fibre was selected for sampling, and the main parameters affecting the SPME process such as extraction temperature, adsorption and desorption time, salt addition, agitation and pH effect were optimized to enhance the sensitivity of the method. This optimization was also performed to allow the qualitative determination of parathion’s main metabolite, paraoxon, in blood. The limits of detection and quantitation for parathion were 3 and 10 ng/mL for urine and 25 and 50 ng/mL for blood, respectively. For paraoxon, the limit of detection was 50 ng/mL in blood. The method showed linearity between the LOQ and 50 ìg/mL for both matrices, with correlation coefficients ranging from 0.9954 to 0.9999. Precision and accuracy were in conformity with the criteria normally accepted in bioanalytical method validation. The mean absolute recoveries were 35.1% for urine and 6.7% for blood. Other parameters such as dilution of sample and stability were also validated. Its simplicity and the fact that only 100 ìL of sample is required to accomplish the analysis make this method useful in forensic toxicology laboratories to determine this compound in intoxications, and it can be considered an alternative to other methods normally used for the determination of this compound in biological media

    LC–MS-MS determination of cytostatic drugs on surfaces and in urine to assess occupational exposure

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    The ever-increased usage of cytostatic drugs leads to high risk of exposure among healthcare workers. Moreover, workers are exposed to multiple compounds throughout their lives, leading to cumulative and chronic exposure. Therefore, multianalyte methods are the most suitable for exposure assessment, which minimizes the risks from handling cytostatic drugs and ensures adequate contamination containment. This study describes the development and full validation of two liquid chromatography–tandem mass spectrometry methods for the detection of gemcitabine, dacarbazine, methotrexate, irinotecan, cyclophosphamide, doxorubicinol, doxorubicin, epirubicin, etoposide, vinorelbine, docetaxel and paclitaxel in working surfaces and urine samples. The urine method is the frst to measure vinorelbine and doxorubicinol. For surfaces, limits of detection (LOD) and limits of quantifcation (LOQ) were 5–100 pg/cm2 , and linearity was achieved up to 500 pg/cm2 . Inaccuracy was between −11.0 and 8.4%. Intra-day, inter-day and total imprecision were <20%, except for etoposide and irinotecan (<22.1%). In urine, LOD and LOQ were 5–250 pg/mL, with a linear range up to 1,000–5,000 pg/mL. Inaccuracy was between −3.8 and 14.9%. Imprecision was <12.4%. Matrix effect was from −58.3 to 1,268.9% and from −66.7 to 1,636% in surface and urine samples, respectively, and extraction effciency from 10.8 to 75% and 47.1 to 130.4%, respectively. All the analytes showed autosampler (6°C/72 h), freezer (–22°C/2 months) and freeze/thaw (three cycles) stability. The feasibility of the methods was demonstrated by analyzing real working surfaces and patients’ urine samples. Contamination withemcitabine, irinotecan, cyclophosphamide, epirubicin and paclitaxel (5–4,641.9 pg/cm2) was found on biological safety cabinets and outpatients’bathrooms. Analysis of urine from patients under chemotherapy identifed the infused drugs at concentrations higher than the upper LOQ. These validated methods will allow a comprehensive evaluation of both environmental and biological contamination in hospital settings and healthcareworkersThe authors would like to thank the participants and staff of the University Clinical Hospital of Santiago de Compostela, and E.L., J.A.L.-A and L.P.-G. would like to thank the Consellería de Cultura, Educacion e Ordenación Universitaria, Xunta de Galicia (Spain), for her postdoctoral contract (ED481D-2019/025) and their predoctoral contracts (ED481A-2017/087 and ED481A-2018/059), respectively. We also thank the Xunta de Galicia (Galicia, Spain) for the Consolidation and Structuring of Competitive Research Units Help (2021-PG054)S

    ¿Es generalizable la existencia de una transición de primer orden ferromagnética-paramagnética en los materiales con magnetorresistencia colosal R2/3B1/3MnO3 (R=lantanido; B=alcalinoterreo)?

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    En este trabajo se examina la naturaleza de la transición de fase ferromagnética de materiales de manganeso con estructura de perovskita, de gran interés tecnológico por sus enormes variaciones de resistividad eléctrica ante la presencia de un campo magnético aplicado (magnetorresistencia colosal). Se encuentra que, en contra de la opinión generalizada, no todos estos materiales presentan un comportamiento cualitativamente similar. En concreto, el carácter de primer orden de la transición ferromagnética no es un factor común. Las implicaciones físicas de este resultado son discutidasIn this work, the nature of the ferromagnetic phase transition of manganese-based materials with perovskite structure, is examined. These are materials of great technological interest due to the enormous variations of their electrical resistivity under the presence of an applied magnetic field (colossal magnetoresistance). lt is found that, contrary to the assumed belíef, not all these materials present a qualitatively similar behaviour. Concretely, the first order character of the ferromagnetic transition is not a common factor. The physical implications of this result are discussedS

    Quantification of the interfacial and bulk contributions to the longitudinal spin Seebeck effect

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    This article appeared in P. Jiménez-Cavero et al. Applied Physics Letters 118, 092404 (2021) and may be found at https://aip.scitation.org/doi/10.1063/5.0038192We report the disentanglement of bulk and interfacial contributions to the thermally excited magnon spin current in the spin Seebeck effect under static heating. For this purpose, we have studied the dependence of the inverse spin Hall voltage and the thermal conductivity on the magnetic layer thickness. Knowledge of these quantities allows us to take into account the influence of both sources of thermal spin current in the analysis of the voltage dependence. The magnetic layer thickness modulates the relative magnitude of the involved thermal drops for a fixed total thermal difference throughout the sample. In the end, we attain the separate contributions of both sources of thermal spin current—bulk and interfacial—and obtain the value of the thermal magnon accumulation length scale in maghemite, which we find to be 29(1) nm. According to our results, bulk magnon accumulation dominates the spin Seebeck effect in our studied range of thicknesses, but the interfacial component is by no means negligibleThis work was supported by the Spanish Ministry of Science [through Project Nos. MAT2014-51982-C2-R, MAT2016-80762-R, MAT2017-82970-C2-R, and PID2019-104150RB-I00 (including FEDER funding) and the Aragón Regional government (Project No. E26)]. P.J.-C. acknowledges Spanish MECD for support through FPU program (Reference No. FPU014/02546). D.B. acknowledges support from MINECO (Spain) through an FPI program (No. BES-2017-079688). R.R. also acknowledges support from the European Commission through the Project No. 734187-SPICOLOST (H2020-MSCA-RISE-2016), the European Union's Horizon 2020 research and innovation program through the Marie Sklodowska-Curie Actions Grant Agreement SPEC No. 894006, and the Spanish Ministry of Science (No. RYC 2019-026915-I). Authors acknowledge the Advanced Microscopy Laboratory-INA University of Zaragoza for offering access to their instruments. C. L-B. acknowledges Xunta de Galicia and ESF for a PhD Grant (ED481A-2018/013)S

    Usefulness of hair analysis and psychological tests for identification of alcohol and drugs of abuse consumption in driving license regranting.

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    Implementation of the points-based driving license has helped to change driver behavior, and can be linked to to a reduction of traffic accidents and fatalities. In Spain, a driving licence is revoked when all points are lost, and the driver must enroll on a Driver Awareness and Re-education (DARE) course. However, offenders are currently not subjected to any tests that would confirm the absence of alcohol or other substances, despite the fact that 9% of Spanish drivers lose their driving license as a result of driving under influence (DUI). This pilot study aimed to compare the usefulness of psychological tests and hair analysis, as methods for identifying which DARE-course attendees had a longterm history of alcohol or drug abuse. Volunteers were submitted to the AUDIT and DAST-10 tests. Hair samples were also collected and analyzed, checking for ethylglucuronide (EtG) (LOQ 5 pg/mg), and thirty-five licit and illicit drugs (LOQ 5-50 pg/mg) by LC-MS/MS. Sixty-one participants - with a mean age of 37.2 (plus or minus 11.6 years) and mainly men (90.2%) - were recruited. All participants undertook both AUDIT and DAST-10 tests. All hair samples were analyzed for EtG and 17 samples were analyzed for licit and illicit drugs. The mean AUDIT score was 9.6 (SD = 7.5), showing a value 30 pg/mg) in twenty-one cases. All positive cases for methadone and cannabis - and half of the positive cases for opioids and cocaine - presented higher concentrations than SoHT cut-offs for chronic consumption. Higher AUDIT score and higher EtG concentration in hair were statistically associated with declaration of alcohol consumption > 4 times/month and with historical fines for DUI of alcohol. In addition, AUDIT scores and EtG concentration in hair had a moderate but significant Spearman correlation (r = 0.331, p < 0.05). The combination of psychological tests and hair analysis seems to be a promising way to identify individuals with alcohol or drug abuse problems. Moreover, applying these methods as part of the process of re-acquiring driving licences could increase the effectiveness of DARE courses, reduce recidivism and improve road safety
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