Limits on the quiescent radio emission from the black hole binaries GRO J1655-40 and XTE J1550-564

We present the results of radio observations of the black hole binaries GRO J1655-40 and XTE J1550-564 in quiescence, with the upgraded Australia Telescope Compact Array. Neither system was detected. Radio flux density upper limits (3 sigma) of 26 micro Jy (at 5.5 GHz), 47 micro Jy (at 9 GHz) for GRO J1655-40, and 1.4 mJy (at 1.75 GHz), 27 micro Jy (at 5.5 GHz), 47 micro Jy (at 9 GHz) for XTE J1550-564 were measured. In conjunction with quasi-simultaneous Chandra X-ray observations (in the case of GRO J1655-40) and Faulkes Telescope optical observations (XTE J1550-564) we find that these systems provide the first evidence of relatively `radio quiet' black hole binaries at low luminosities; indicating that the scatter observed in the hard state X-ray:radio correlation at higher luminosities may also extend towards quiescent levels.Comment: Accepted for publication in MNRA

The first resolved imaging of milliarcsecond-scale jets in Circinus X-1

We present the first resolved imaging of the milliarcsecond-scale jets in the neutron star X-ray binary Circinus X-1, made using the Australian Long Baseline Array. The angular extent of the resolved jets is ~20 milliarcseconds, corresponding to a physical scale of ~150 au at the assumed distance of 7.8 kpc. The jet position angle is relatively consistent with previous arcsecond-scale imaging with the Australia Telescope Compact Array. The radio emission is symmetric about the peak, and is unresolved along the minor axis, constraining the opening angle to be less than 20 degrees. We observe evidence for outward motion of the components between the two halves of the observation. Constraints on the proper motion of the radio-emitting components suggest that they are only mildly relativistic, although we cannot definitively rule out the presence of the unseen, ultra-relativistic (Lorentz factor >15) flow previously inferred to exist in this system.Comment: Accepted for publication in MNRAS Letters. 6 pages, 4 figure

Millimetre observations of a sub-arcsecond jet from Circinus X-1

We present results from the first successful millimetre (combined 33 GHz and 35 GHz) observations of the neutron star X-ray binary Circinus X-1, using the Australia Telescope Compact Array. The source was clearly detected in all three observing epochs. We see strong evidence for a periastron flare beginning at MJD 55519.9 \pm 0.04 with estimated peak flux densities of up to 50 mJy and which proceeds to decline over the following four days. We directly resolve jet structures on sub-arcsecond scales. Flux density variability and distance from the core of nearby components suggests recent shock re-energisation, though we are unable to directly connect this with the observed flare. We suggest that, if the emission is powered by an unseen outflow, then a phase delay exists between flare onset and subsequent brightening of nearby components, with flows reaching mildly relativistic velocities. Given resolved structure positions, in comparison to past observations of Cir X-1, we find evidence that jet direction may vary with distance from the core, or the source's precession parameters have changed.Comment: Accepted for publication in MNRA

Influence of phospholipids on the crystallization of waxes in sunflowerseed oil

The effect of lecithins on wax crystallization in sunflowerseed oil was studied. The results showed that the presence of lecithins does not modify the nucleation stage, but decreases the crystalline size. Lecithin has a minimal effect on viscosity and does not change the wax/oil equilibrium ratio. It is proposed that the main mechanism of action of lecithin involves the partial adsorption on the surface of the wax crystals interfering with their growth.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Parsec-Scale Bipolar X-ray Shocks Produced by Powerful Jets from the Neutron Star Circinus X-1

We report the discovery of multi-scale X-ray jets from the accreting neutron star X-ray binary, Circinus X-1. The bipolar outflows show wide opening angles and are spatially coincident with the radio jets seen in new high-resolution radio images of the region. The morphology of the emission regions suggests that the jets from Circinus X-1 are running into a terminal shock with the interstellar medium, as is seen in powerful radio galaxies. This and other observations indicate that the jets have a wide opening angle, suggesting that the jets are either not very well collimated or precessing. We interpret the spectra from the shocks as cooled synchrotron emission and derive a cooling age of approximately 1600 yr. This allows us to constrain the jet power to be between 3e35 erg/s and 2e37 erg/s, making this one of a few microquasars with a direct measurement of its jet power and the only known microquasar that exhibits stationary large-scale X-ray emission.Comment: 5 pages, 4 figures, to be published in the Astrophysical Journal Letter

Formation of the compact jets in the black hole GX 339-4

Galactic black hole binaries produce powerful outflows with emit over almost the entire electromagnetic spectrum. Here, we report the first detection with the Herschel observatory of a variable far-infrared source associated with the compact jets of the black hole transient GX 339-4 during the decay of its recent 2010-2011 outburst, after the transition to the hard state. We also outline the results of very sensitive radio observations conducted with the Australia Telescope Compact Array, along with a series of near-infrared, optical (OIR) and X-ray observations, allowing for the first time the re-ignition of the compact jets to be observed over a wide range of wavelengths. The compact jets first turn on at radio frequencies with an optically thin spectrum that later evolves to optically thick synchrotron emission. An OIR reflare is observed about ten days after the onset of radio and hard X-ray emission, likely reflecting the necessary time to build up enough density, as well as to have acceleration (e.g. through shocks) along an extended region in the jets. The Herschel measurements are consistent with an extrapolation of the radio inverted power-law spectrum, but they highlight a more complex radio to OIR spectral energy distribution for the jets.Comment: Accepted for publication in MNRAS Letter, 6 pages, 3 Figures + 1 online Tabl

Highly Enantioselective Iridium(I)-Catalyzed Hydrocarbonation of Alkenes: A Versatile Approach to Heterocyclic Systems Bearing Quaternary Stereocenters

We report a versatile, highly enantioselective intramolecular hydrocarbonation reaction that provides a direct access to heteropolycyclic systems bearing chiral quaternary carbon stereocenters. The method, which relies on an iridium(I)/bisphosphine chiral catalyst, is particularly efficient for the synthesis of five-, six- and seven-membered fused indole and pyrrole products, bearing one and two stereocenters, with enantiomeric excesses of up to >99 %. DFT computational studies allowed to obtain a detailed mechanistic profile and identify a cluster of weak non-covalent interactions as key factors to control the enantioselectivityThis work received financial support from the Spanish MINECO (SAF2016-76689-R, PID2019-108624RB-I00, CTQ2017-84767-P, PID2020-118579GB-I00), the Xunta de Galicia (ED431C 2017/19, 2015-CP082, Centro Singular de Investigación de Galicia accreditation 2019-2022, ED431G 2019/03, a predoctoral Fellowship to A. A. and M. C. and a postdoctoral Fellowship to D. F. F, ED481B-2019-005) and the ERDF, ERC (Adv. Grant No. 340055). The Orfeo-Cinqa network (CTQ2016-81797-REDC)S

Iridium(I)-Catalyzed Intramolecular Cycloisomerization of Enynes: Scope and Mechanistic Course

NOTICE: This is the peer reviewed version of the following article: David F. Fernández, Catarina A. B. Rodrigues, Martín Calvelo, Moisés Gulías, José L. Mascareñas and Fernando López (2018), Iridium(I)-Catalyzed Intramolecular Cycloisomerization of Enynes: Scope and Mechanistic Course. ACS Catalysis, 2018, 8 (8), 7397–7402 [DOI: 10.1021/acscatal.8b02139]. This article may be used for non-commercial purposes in accordance with American Chemical Society Terms and Conditions for self-archivingWe report an Ir(I)-catalyzed cycloisomerization methodology that provides access to carbocyclic systems bearing exo-alkene moieties from alkynyl-equipped acyclic precursors. The method relies on the C–H activation of olefinic and (hetero)aromatic C(sp2)–H bonds, followed by an exocyclization to a tethered alkyne, and provides interesting cyclic diene products that are amenable of further elaboration. Importantly, DFT calculations suggests that, in contrast to related hydrocarbonations of alkenes in which either migratory insertions or C–C reductive eliminations have been suggested to be rate-determining, in our reactions, the energetic barrier of these steps is lower than that of the previous C–H activationThis work received financial support from the Spanish MINECO (Nos. SAF2016-76689-R, CTQ2016-77047-P, and CTQ2017-84767-P, as well as an FPI fellowship to D.F.F.), the Xunta de Galicia (Nos. ED431C 2017/19 and 2015-CP082, as well as Centro Singular de Investigación de Galicia accreditation 2016-2019 ED431G/09 and predoctoral fellowship to M.C.), the ERDF, ERC (Adv. Grant No. 340055) and the Orfeo-Cinqa network (No. CTQ2016-81797-REDC). Dr. Rebeca García-Fandiño is acknowledged for helpful suggestions on DFT studiesS

e-VLBI observations of Circinus X-1: monitoring of the quiescent and flaring radio emission on AU scales

A recent detection of the peculiar neutron star X-ray binary Circinus X-1 with electronic very long baseline interferometry (e-VLBI) prompted the suggestion that compact, non-variable radio emission persists through the entire 16.6-day orbit of the binary system. We present the results of a high angular resolution monitoring campaign conducted with the Australian Long Baseline Array in real-time e-VLBI mode. e-VLBI observations of Circinus X-1 were made on alternate days over a period of 20 days covering the full binary orbit. A compact radio source associated with Circinus X-1 was clearly detected at orbital phases following periastron passage but no compact radio emission was detected at any other orbital phase, ruling out the presence of a persistent, compact emitting region at our sensitivity levels. The jet was not resolved at any epoch of our 1.4-GHz monitoring campaign, suggesting that the ultrarelativistic flow previously inferred to exist in this source is likely to be dark. We discuss these findings within the context of previous radio monitoring of Circinus X-1.Comment: Accepted for publication in MNRAS. 7 pages, 5 figure

Obtención, Acondicionamiento y Caracterizacion de Lecitinas de Girasol

Durante el proceso de refinacion de los aceites vegetales es relevante y necesaria la eliminacion de ciertos componentes minoritarios tales como los fosfolipidos (gomas) a fin de garantizar su estabilidad y calidad final. Dichas gomas al ser purificadas dan lugar a la obtencion de lecitinas de amplia aplicacion en la industria alimentaria, especialmente en el caso de la lecitina de soja (1). Las lecitinas constituyen un ingrediente multifuncional debido a que pue-den emplearse como agentes dispersantes, reguladores de la viscosidad, agen-tes emulsificantes, etc (2). El degomado acuoso involucra el tratamiento termico del aceite crudo de girasol con agua, siendo importante la eleccion de las variables operativas del proceso (temperatura, tiempo de contacto y relacion de fases acuosa/oleosa) para obtener lecitinas de distinta calidad (3). Estudios previos han permitido determinar los niveles optimos de estos parametros para lograr la remocion de la mayor cantidad de fosfolipidos del aceite crudo de girasol (T: 40ºC, t: 35 min, y 2.5% de agua) (4). Ademas, a fin de evitar el deterioro microbiologico y minimizar los procesos de oxidacion, las gomas deben someterse rapidamente a un proceso de secado a presión reducida y temperaturas inferiores a 80 ºC, como en el caso de la soja (5). Por otra parte, es importante considerar las propiedades reologicas del producto durante dicho proceso ya que su viscosidad se incrementa notablemente al disminuir su contenido de humedad (6). En el ambito local, este tipo de subproducto proveniente del girasol no ha sido muy utilizado ni extensamente estudiado por lo que, conjuntamente con la magnitud productiva de nuestro pais, puede representar un recurso potencial de considerable interes economico - industrialFil: Pan, Lucas G.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Buedo, A.. Molinos Rio de la Plata; ArgentinaFil: Tomás, Mabel Cristina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Calvelo, Alfredo. Molinos Rio de la Plata; ArgentinaFil: Añon, Maria Cristina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina2do Congreso Argentino de GirasolBuenos AiresArgentinaAsociación Argentina de Giraso