Una propuesta para el abordaje de la refracción y reflexión total interna utilizando el GeoGebra

En ocasiones la falta de insumos en las instituciones escolares afecta el desarrollo de las prácticas de laboratorio de Física en secundaria. Sin embargo, el uso de GeoGebra como simulador de fenómenos físicos ofrece una alternativa para suplir esta falta. Pero la integración del GeoGebra en la instrucción no se logra de forma inmediata, pues requiere que los profesores tengan una comprensión integrada de los contenidos a enseñar en relación a las posibilidades didácticas del programa. Por ello este trabajo presenta una secuencia para analizar la refracción y reflexión total interna usando el GeoGebra, con el propósito de ofrecer al profesorado la oportunidad de conocer algunas bondades del software y guiarles en la integración de tecnologías en sus clases

Impulse Response of Civil Structures from Ambient Noise Analysis

Increased monitoring of civil structures for response to earthquake motions is fundamental to reducing seismic risk. Seismic monitoring is difficult because typically only a few useful, intermediate to large earthquakes occur per decade near instrumented structures. Here, we demonstrate that the impulse response function (IRF) of a multistory building can be generated from ambient noise. Estimated shear-wave velocity, attenuation values, and resonance frequencies from the IRF agree with previous estimates for the instrumented University of California, Los Angeles, Factor building. The accuracy of the approach is demonstrated by predicting the Factor building’s response to an M 4.2 earthquake. The methodology described here allows for rapid, noninvasive determination of structural parameters from the IRFs within days and could be used for state-of-health monitoring of civil structures (buildings, bridges, etc.) before and/or after major earthquakes

Modelling and assessing ionospheric higher order terms for GNSS signals

High precision positioning and time transfer are required by a large number of scientific applications: seismic ground deformations, sea level monitoring or land survey applications require sub-centimeter precision in kinematic position; monitoring of stable atomic frequency standards requires an increasing sub –nanosecond precision. Differential GNSS is presently the best tool to reach such precisions, as it removes the majority of the errors affecting the GNSS signals. However, the associated need for dense GNSS observation networks is not fulfilled for many locations (e.g. Pacific, Africa). An alternative is to use Precise Point Positioning (PPP), but this technique requires correcting signal delays at the highest level of precision, including high order ionospheric effects. It is thus essential to accurately characterize the higher order ionospheric terms (I2+), i.e. I2, I3, I4, geometric bending and differential STEC bending, which is the goal of this paper. For that, we used a network of well-distributed GPS stations, and the Bernese v5.0 software. We have focused our attention in the I2+ terms, studying two approaches: A) Combining independent and simultaneous measurements of the same transmitter-receiver pair at three (or more) different frequencies, in order to remove the I2 term: it is theoretically possible to cancel out both I1 and I2 similarly as it is done typically in precise dual-frequency GNSS measurements for I1. It is shown that, as expected, due to the proximity of the corresponding frequencies in L-band, the high noise of the combinations makes this approach unpractical to either isolate or remove I2. B) Modelling the I2+ terms, in function of estimates of electron content, geomagnetic field and electron density values. Their characterization has been done in a realistic and full-control environment, by using the last version of the International Reference Ionosphere model (IRI2012) and International Geomagnetic Reference Model in its 11th version (IGRF11). Two metrics have been considered to assess the importance of the different higher order ionospheric corrections and their approximations: a) At the signal level, or range level, directly provided by the corresponding slant delays. b) At the geodetic domain level, provided by the impact of such values in the different geodetic parameters estimated consistently (i.e. simultaneously) from a global GNSS network.Peer ReviewedPostprint (author's final draft

Uso del modelo de Rasch para poner en la misma escala las puntuaciones de distintos tests

Los usuarios de los tests tienen que poner en una escala común las puntuaciones de distintos instrumentos en varias situaciones prácticas, tales como la evaluación académica, la selección de personal, los estudios acerca del cambio de un atributo psicológico o educativo, la construcción de bancos de ítems, la validación intercultural de tests y los estudios sobre el funcionamiento diferencial de los ítems. Situar en una escala común las puntuaciones de diferentes tests es una de las principales aplicaciones del modelo de Rasch. En este artículo, mostramos el proceso de equiparación de dos tests (diseño, análisis de datos e interpretación) usando como anclaje un conjunto de ítems comunes

Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes

[EN] The main challenge in the hydrogenation of alkynes into (E)- or (Z)-alkenes is to control the selective formation of the alkene, avoiding the over-reduction to the corresponding alkane. In addition, the preparation of recoverable and reusable catalysts is of high interest. In this work, we report novel nickel nanoparticles (Ni NPs) stabilized by three different imidazolium-amidinate ligands (ICy center dot(NCN)-N-(Ar); L1: Ar = p-tol, L2: Ar = p-anisyl and L3: Ar = p-ClC6H4). The as-prepared Ni NPs were fully characterized by (HR)-TEM, XRD, WASX, XPS and VSM. The nanocatalysts are active in the hydrogenation of various substrates. They present a remarkable selectivity in the hydrogenation of alkynes towards (Z)-alkenes, particularly in the hydrogenation of 3-hexyne into (Z)-3-hexene under mild reaction conditions (room temperature, 3% mol Ni and 1 bar H-2). The catalytic behaviour of Ni NPs was influenced by the electron donor/acceptor groups (-Me, -OMe, -Cl) in the N-aryl substituents of the amidinate moiety of the ligands. Due to the magnetic character of the Ni NPs, recycling experiments were successfully performed after decantation in the presence of an external magnet, which allowed us to recover and reuse these catalysts at least 3 times preserving both activity and chemoselectivity.The authors thank CNRS, UPS-Toulouse, INSA, "IDEX/Chaires d'attractivite l'Universite Federale Toulouse Midi-Pyrenees", "Instituto de Tecnologia Quimica" (ITQ; UPV-CSIC), "Juan de la Cierva" programme (IJCI-2016-27966), "Primero Proyectos de Investigacion" (PAID-06-18), "Instituto de Investigaciones Quimicas" (IIQ; CSIC-US), "Ministerio de Ciencia, Innovacion y Universidades" (MCIU/AEI), FEDER funds of the European Union (PGC2018-095768-B-I00) and ERC Advanced Grant (MONACAT 2015-694159) for financial support. We also thank L. Datas for the TEM facilities (UMS Castaing) and S. Cayez for the HRTEM measurements.López-Vinasco, AM.; Martínez-Prieto, LM.; Asensio, JM.; Lecante, P.; Chaudret, B.; Cámpora, J.; Van Leeuwen, PWNM. (2020). Novel nickel nanoparticles stabilized by imidazolium-amidinate ligands for selective hydrogenation of alkynes. Catalysis Science & Technology. 10(2):342-350. https://doi.org/10.1039/c9cy02172hS342350102Swamy, K. C. K., Reddy, A. S., Sandeep, K., & Kalyani, A. (2018). Advances in chemoselective and/or stereoselective semihydrogenation of alkynes. Tetrahedron Letters, 59(5), 419-429. doi:10.1016/j.tetlet.2017.12.057Lei, J., Su, L., Zeng, K., Chen, T., Qiu, R., Zhou, Y., … Yin, S.-F. (2017). Recent advances of catalytic processes on the transformation of alkynes into functional compounds. Chemical Engineering Science, 171, 404-425. doi:10.1016/j.ces.2017.05.021J. G. de Vries and C. 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Hydrogenation of carbon–carbon multiple bonds: chemo-, regio- and stereo-selectivity. Journal of Molecular Catalysis A: Chemical, 173(1-2), 185-221. doi:10.1016/s1381-1169(01)00150-9Lindlar, H. (1952). Ein neuer Katalysator für selektive Hydrierungen. Helvetica Chimica Acta, 35(2), 446-450. doi:10.1002/hlca.19520350205Delgado, J. A., Benkirane, O., Claver, C., Curulla-Ferré, D., & Godard, C. (2017). Advances in the preparation of highly selective nanocatalysts for the semi-hydrogenation of alkynes using colloidal approaches. Dalton Transactions, 46(37), 12381-12403. doi:10.1039/c7dt01607gK. Philippot and P.Serp , Nanomaterials in Catalysis , Wiley-VCH , Weinheim , 2013D. Astruc , Nanoparticles and Catalysis , Wiley-VCH , Weinheim , 2008U. Heiz and U.Landman , Nanocatalysis , Springer , Berlin , 2007Vilé, G., Almora-Barrios, N., Mitchell, S., López, N., & Pérez-Ramírez, J. (2014). From the Lindlar Catalyst to Supported Ligand-Modified Palladium Nanoparticles: Selectivity Patterns and Accessibility Constraints in the Continuous-Flow Three-Phase Hydrogenation of Acetylenic Compounds. Chemistry - A European Journal, 20(20), 5926-5937. doi:10.1002/chem.201304795Witte, P. T., Boland, S., Kirby, F., van Maanen, R., Bleeker, B. F., de Winter, D. A. M., … Berben, P. H. (2012). NanoSelect Pd Catalysts: What Causes the High Selectivity of These Supported Colloidal Catalysts in Alkyne Semi-Hydrogenation? ChemCatChem, 5(2), 582-587. doi:10.1002/cctc.201200460La Sorella, G., Sperni, L., Canton, P., Coletti, L., Fabris, F., Strukul, G., & Scarso, A. (2018). Selective Hydrogenations and Dechlorinations in Water Mediated by Anionic Surfactant-Stabilized Pd Nanoparticles. The Journal of Organic Chemistry, 83(14), 7438-7446. doi:10.1021/acs.joc.8b00314Nikoshvili, L. Z., Bykov, A. V., Khudyakova, T. E., LaGrange, T., Héroguel, F., Luterbacher, J. S., … Kiwi-Minsker, L. (2017). Promotion Effect of Alkali Metal Hydroxides on Polymer-Stabilized Pd Nanoparticles for Selective Hydrogenation of C–C Triple Bonds in Alkynols. Industrial & Engineering Chemistry Research, 56(45), 13219-13227. doi:10.1021/acs.iecr.7b01612Reina, A., Favier, I., Pradel, C., & Gómez, M. (2018). Stable Zero-Valent Nickel Nanoparticles in Glycerol: Synthesis and Applications in Selective Hydrogenations. Advanced Synthesis & Catalysis, 360(18), 3544-3552. doi:10.1002/adsc.201800786De los Bernardos, M. D., Pérez-Rodríguez, S., Gual, A., Claver, C., & Godard, C. (2017). Facile synthesis of NHC-stabilized Ni nanoparticles and their catalytic application in the Z-selective hydrogenation of alkynes. Chemical Communications, 53(56), 7894-7897. doi:10.1039/c7cc01779kWen, X., Shi, X., Qiao, X., Wu, Z., & Bai, G. (2017). Ligand-free nickel-catalyzed semihydrogenation of alkynes with sodium borohydride: a highly efficient and selective process for cis-alkenes under ambient conditions. Chemical Communications, 53(39), 5372-5375. doi:10.1039/c7cc02140bKonnerth, H., & Prechtl, M. H. G. (2016). Selective partial hydrogenation of alkynes to (Z)-alkenes with ionic liquid-doped nickel nanocatalysts at near ambient conditions. Chemical Communications, 52(58), 9129-9132. doi:10.1039/c6cc00499gCarenco, S., Leyva-Pérez, A., Concepción, P., Boissière, C., Mézailles, N., Sanchez, C., & Corma, A. (2012). Nickel phosphide nanocatalysts for the chemoselective hydrogenation of alkynes. Nano Today, 7(1), 21-28. doi:10.1016/j.nantod.2011.12.003Polshettiwar, V., Baruwati, B., & Varma, R. S. (2009). Nanoparticle-supported and magnetically recoverable nickel catalyst: a robust and economic hydrogenation and transfer hydrogenation protocol. Green Chem., 11(1), 127-131. doi:10.1039/b815058cAlonso, F., Osante, I., & Yus, M. (2007). Highly selective hydrogenation of multiple carbon–carbon bonds promoted by nickel(0) nanoparticles. Tetrahedron, 63(1), 93-102. doi:10.1016/j.tet.2006.10.043Rossi, L. M., Costa, N. J. S., Silva, F. P., & Wojcieszak, R. (2014). Magnetic nanomaterials in catalysis: advanced catalysts for magnetic separation and beyond. Green Chemistry, 16(6), 2906. doi:10.1039/c4gc00164hMartínez-Prieto, L. M., & Chaudret, B. (2018). Organometallic Ruthenium Nanoparticles: Synthesis, Surface Chemistry, and Insights into Ligand Coordination. Accounts of Chemical Research, 51(2), 376-384. doi:10.1021/acs.accounts.7b00378Martínez-Prieto, L. M., Baquero, E. A., Pieters, G., Flores, J. C., de Jesús, E., Nayral, C., … Chaudret, B. (2017). Monitoring of nanoparticle reactivity in solution: interaction of l-lysine and Ru nanoparticles probed by chemical shift perturbation parallels regioselective H/D exchange. Chemical Communications, 53(43), 5850-5853. doi:10.1039/c7cc02445bMartínez-Prieto, L. M., Rakers, L., López-Vinasco, A. M., Cano, I., Coppel, Y., Philippot, K., … van Leeuwen, P. W. N. M. (2017). Soluble Platinum Nanoparticles Ligated by Long-Chain N-Heterocyclic Carbenes as Catalysts. Chemistry - A European Journal, 23(52), 12779-12786. doi:10.1002/chem.201702288Asensio, J. M., Tricard, S., Coppel, Y., Andrés, R., Chaudret, B., & de Jesús, E. (2016). Knight Shift in 13 C NMR Resonances Confirms the Coordination of N‐Heterocyclic Carbene Ligands to Water‐Soluble Palladium Nanoparticles. Angewandte Chemie International Edition, 56(3), 865-869. doi:10.1002/anie.201610251Martínez-Prieto, L. M., Urbaneja, C., Palma, P., Cámpora, J., Philippot, K., & Chaudret, B. (2015). A betaine adduct of N-heterocyclic carbene and carbodiimide, an efficient ligand to produce ultra-small ruthenium nanoparticles. Chemical Communications, 51(22), 4647-4650. doi:10.1039/c5cc00211gMartínez-Prieto, L. M., Cano, I., Márquez, A., Baquero, E. A., Tricard, S., Cusinato, L., … van Leeuwen, P. W. N. M. (2017). Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts. 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Prolactin in saliva of pigs as a possible biomarker of stress: analytical validation of an immunoassay and changes at slaughterhouse

Oral session 2[EN] Prolactin (PRL) is considered a biomarker of stress response, both acute and chronic, in several species. Although the scientific literature reports divergent results, some studies suggest that prolactin secretion during stress acts to maintain homeostasis within the immune system. Several studies have investigated the possibility of measuring PRL in saliva in different species such as rats, domestic ruminants, donkeys, dogs, cattle, and sheep for diagnosis or research purposes. Results obtained in animal models have indicated that the secretion of this hormone is dependent on the type and intensity of the stress

Velocity Dispersions and Stellar Populations of the Most Compact and Msssive early-Type Galaxies at Redshift similar to 1

We present Gran-Telescopio-Canarias/OSIRIS optical spectra of four of the most compact and massive early-type galaxies (ETGs) in the Groth Strip Survey at redshift z similar to 1, with effective radii R-e = 0.5-2.4 kpc and photometric stellarmasses M-star = (1.2-4) x 10(11)M(circle dot). We find that these galaxies have velocity dispersions sigma = 156-236 km s(-1). The spectra are well fitted by single stellar population models with approximately 1 Gyr of age and solar metallicity. We find that (1) the dynamical masses of these galaxies are systematically smaller by a factor of similar to 6 than the published stellarmasses using BRIJK photometry, and (2) when estimating stellarmasses as 0.7xM(dyn), a combination of passive luminosity fading with mass/size growth due to minor mergers can plausibly evolve our objects to match the properties of the local population of ETGs

Hybrid nanostructured magnetite nanoparticles: From bio-detection and theragnostics to regenerative medicine

Nanotechnology offers the possibility of operating on the same scale length at which biological processes occur, allowing to interfere, manipulate or study cellular events in disease or healthy conditions. The development of hybrid nanostructured materials with a high degree of chemical control and complex engineered surface including biological targeting moieties, allows to specifically bind to a single type of molecule for specific detection, signaling or inactivation processes. Magnetite nanostructures with designed composition and properties are the ones that gather most of the designs as theragnostic agents for their versatility, biocompatibility, facile production and good magnetic performance for remote in vitro and in vivo for biomedical applications. Their superparamagnetic behavior below a critical size of 30 nm has allowed the development of magnetic resonance imaging contrast agents or magnetic hyperthermia nanoprobes approved for clinical uses, establishing an inflection point in the field of magnetite based theragnostic agents.Fil: Piñeiro, Yolanda. Universidad de Santiago de Compostela; EspañaFil: González Gómez, Manuel. Universidad de Santiago de Compostela; EspañaFil: de Castro Alves, Lisandra. Universidad de Santiago de Compostela; EspañaFil: Arnosa Prieto, Angela. Universidad de Santiago de Compostela; EspañaFil: García Acevedo, Pelayo. Universidad de Santiago de Compostela; EspañaFil: Seco Gudiña, Román. Universidad de Santiago de Compostela; EspañaFil: Puig, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Teijeiro, Carmen. Universidad de Santiago de Compostela; EspañaFil: Yáñez Vilar, Susana. Universidad de Santiago de Compostela; EspañaFil: Rivas, José. Universidad de Santiago de Compostela; Españ