Evolution of the spherical cavity radius generated around a subsurface drip emitter

The emitter discharge in subsurface drip irrigation can be affected by soil properties. A positive pressure develops at the emitter outlet where a spherical cavity is assumed to form. In steady-state conditions, the pressure in the soil relates to soil hydraulic properties, the emitter discharge, and the cavity radius. This pressure in the soil is very sensitive to the cavity radius. In this paper, the development of the cavity around the emitter outlet was measured for various emitter discharges in laboratory tests carried out in containers with uniform loamy soils. A trend between soil pressure and emitter discharge was established that illustrates the performance of buried emitters in the field. Its application to the prediction of water distribution in subsurface drip irrigation units and its effect on the estimation of irrigation performance are also shown

Internal and relative motions of the Taurus and Ophiuchus star-forming regions

We investigate the internal and relative motions of the Taurus and Ophiuchus star-forming regions using a sample of young stars with accurately measured radial velocities and proper motions. We find no evidence for expansion or contraction of the Taurus complex, but a clear indication for a global rotation, resulting in velocity gradients, this suggests a common origin, possibly related to that of Gould's Belt.Comment: 2 figure

Fidelidad de una intervención educativa: el papel de los facilitadores

Objetivo: evaluar las estrategias de aseguramiento de fidelidad utilizadas en un estudio de intervención controlada y aleatorizada, tales como protocolización y estandarización de la intervención, selección y entrenamiento de los facilitadores, establecimiento de criterios de evaluación de apego y monitoreo del mismo. Métodología: análisis de las estrategias a través de las evaluaciones pre y post entrenamiento, los reportes de monitoreo, evaluaciones de final de día y comentarios de participantes de investigación. Resultados: el análisis muestra que la selección y entrenamiento aseguró que los facilitadores contaran con el conocimiento suficiente para la entrega del currículo pero también que se sintieran autoeficaces en el proceso y confiaran en la eficiencia de resultado. La protocolización del currículo, y el monitoreo aseguraron el apego a la intervención. Las evaluaciones de final de día de los facilitadores y los comentarios de los participantes reflejan una actuación dinámica, asertiva y apegada a currículo de los facilitadores. Conclusiones: el cuidado de los elementos que definen tanto el apego como la entrega competente en una intervención controlada y aleatorizada permite garantizar la integridad de la intervención y con ello disminuir la posibilidad de sesgo por esta fuente

The Gould's Belt Very Large Array Survey III. The Orion region

We present results from a high-sensitivity (60 $\mu$Jy), large-scale (2.26 square degree) survey obtained with the Karl G. Jansky Very Large Array as part of the Gould's Belt Survey program. We detected 374 and 354 sources at 4.5 and 7.5 GHz, respectively. Of these, 148 are associated with previously known Young Stellar Objects (YSOs). Another 86 sources previously unclassified at either optical or infrared wavelengths exhibit radio properties that are consistent with those of young stars. The overall properties of our sources at radio wavelengths such as their variability and radio to X-ray luminosity relation are consistent with previous results from the Gould's Belt Survey. Our detections provide target lists for followup VLBA radio observations to determine their distances as YSOs are located in regions of high nebulosity and extinction, making it difficult to measure optical parallaxes.Comment: Accepted for publication in ApJ; 51 pages, 15 figures, 5 table

A kinetic study for NO catalytic reduction on silica sub-micron diameter tubes with platinum nanoparticles

The selective catalytic reduction (SCR) of NOx with C3H6 in the presence of O2 on silica sub-microtubes with platinum nanoparticles was studied in order to establish a possible reaction mechanism at different experimental conditions. This catalyst showed a high NO conversion with very high selectivity to N2 at mild conditions in the presence of excess oxygen when using C3H6 as reducing agent. The influence of both NO and C3H6 concentrations on their conversions was analyzed at different space times. The obtained results suggest that the three reactants (C3H6, NO, and O2) are adsorbed on Pt sites. The kinetic model proposed considers that both dissociative adsorption of NO and activation of the hydrocarbon can take place simultaneously. Nevertheless, the value of the parameters obtained by the resolution of the model equations indicates that the first one presents a major relevance. These results are in concordance with the high selectivity to N2 observed, because the preponderance presence of dissociated NO avoids the formation of N2O by the reaction of molecular NO with N dissociated from NO. Furthermore, both NO reduction and C3H6 oxidation conversions are represented reasonably well by the model presented.This work was supported by the Spanish Ministry of Economy and Competitiveness under CTQ2012-36408 and CTQ2015-68654-R projects

Activation of electrospun lignin-based carbon fibers and their performance as self-standing supercapacitor electrodes

The production and activation of self-standing carbon electrodes from electrospun lignin fibers was analyzed in this work. Carbon microfibers were prepared at 900 °C from air-stabilized spun cloths by direct carbonization under inert atmosphere and with diluted O2. The modifications of the porosity and surface chemistry of the carbon fibers was also studied by adding H3PO4 in the lignin solution and using different oxygen partial pressures during activation. The presence of phosphoric acid not only increases the porosity development and the preparation yield, but also enhances the gravimetric capacitance of the electrodes. In addition, the activation in presence of oxygen increases the surface area and the generation of wider micropores. Microporous carbon fibers with surface areas as high as 2340 m2 g−1 were obtained using this method. The direct conformation of carbon fibers into binderless electrodes allows to achieve high-power rate capability supercapacitors. Activation in presence of oxygen can enhance up to 50% the energy storage of supercapacitors without compromising the power of the device (8.4 Wh kg−1 and Pmax of 47 kW kg−1). However, at high activation degrees, no further gain in energy density is observed due to the excessive widening of micropores, and the loss of electrical conductivity that increases the cell resistance, limiting the power capability of the device. The optimal results in terms of energy, power and durability are achieved combining low amounts of H3PO4 and mild activation with O2, confirming that electrospinning of lignin is a promising method for sustainable production of self-standing supercapacitor electrodes.We thank MICINN (RTI2018-097555-B-100 and RTI2018-095291-B-I00) for the financial support. F.J.G.M. gratefully acknowledges the assistance of MINECO through a research grant (PTA2015-11464-I)

Estimation of Dietary Exposure to Contaminants Transferred from the Packaging in Fatty Dry Foods Based on Cereals

Food packaging has received special attention from the food safety standpoint since it could be a potential source of contamination through the migration of chemical substances from the packaging material into food. The assessment of the exposure through the diet to these contaminants from food packaging is necessary. In this work, an estimation of dietary exposure of the young Spanish population (1–17 years) to target chemicals from packaging for fatty dried foods based on cereals was assessed. For this purpose, a gas chromatography coupled to mass spectrometry (GC–MS) method was developed for screening of volatile and semivolatile compounds, potential migrants from the packaging. Then, this technique was used to quantify 8 target analytes, which were previously identified in the packaging (including phthalates, acetyl tributyl citrate (ATBC), butylated hydroxytoluene (BHT) and octocrylene), in composite food samples of fatty cereals prepared according to the consumption data for different age groups. Among the phthalates, exposure to diethyl phthalate (DEP) was the highest for the three groups considered (0.0761–0.545 µg/kg body weight/day), followed by bis(2-ethylhxyl)phathalate (DEHP), while the lowest mean intake was found for di-n-octyl phathalate (DNOP; 0.00463–0.0209 µg/kg body weight/day). The estimated dietary exposures did not exceed for any of the analytes the corresponding established tolerable daily intakesThis research was funded by the Ministerio de Economía y Competitividad, by Fondo Europeo de Desarrollo Regional (FEDER), and by Agencia Estatal de Investigación Ref.No. AGL2015-69609-P “MIGRAEXPO” (MINECO/FEDER, UE)S

GC-MS screening for the identification of potential migrants present in polymeric coatings of food cans

The coatings used in cans can release complex chemical mixtures into foodstuffs. Therefore, it is important to develop analytical methods for the identification of these potential migrant compounds in packaged food to guarantee the compliance with European food packaging legislation and ensure consumer safety. In the present work, the type of coating in a total of twelve cans collected in Santiago de Compostela (Spain) were evaluated using an ATR (attenuated total reflectance)-FTIR spectrometer. These samples were analysed after extraction with acetonitrile in order to identify potential migrants through a screening method by gas chromatography coupled to mass spectrometry (GC-MS). A total of forty-seven volatile and semi-volatile compounds were identified in these samples, including plasticizers, photoinitiators, antioxidants, lubricants, etc. Then, in a second step, a targeted analysis was carried out for the simultaneous determination of 13 compounds, including bisphenols (BPA, BPB, BPC, BPE, BPF, BPG) and BADGEs (BADGE, BADGE.H2O, BADGE.2H2O, BADGE.HCl, BADGE.2HCl, BADGE.H2O.HCl, cyclo-di-BADGE) by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) with atmospheric pressure chemical ionisation (APCI) source. Among all the bisphenols analysed, only the bisphenol A was detected in four samples; while cyclo-di-BADGE was the predominant compound detected in all the samples analysed.This research was funded by the Ministerio de Ciencia, Innovación y Universidades, by Fondo Europeo de Desarrollo Regional (FEDER), and by Agencia Estatal de Investigación Ref.No. PGC2018-094518-B-I00 “MIGRACOATING” (MINECO/FEDER, UE)S