66 research outputs found
Synthesis of highly stable metal-containing extra-large-pore molecular sieves
[EN] The isomorphic substitution of two different metals (Mg and Co) within the framework of the ITQ-51 zeotype (IFO structure) using bulky aromatic proton sponges as organic structure-directing agents (OSDAs) has allowed the synthesis of different stable metal-containing extra-large-pore zeotypes with high pore accessibility and acidity. These metal-containing extra-large-pore zeolites, named MgITQ-51 and CoITQ-51, have been characterized by different techniques, such as powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, UV-Vis spectroscopy, temperature programmed desorption of ammonia and Fourier transform infrared spectroscopy, to study their physico-chemical properties. The characterization confirms the preferential insertion of Mg and Co atoms within the crystalline structure of the ITQ-51 zeotype, providing high Bronsted acidity, and allowing their use as efficient heterogeneous acid catalysts in industrially relevant reactions involving bulky organic molecules.Financial support by the Spanish Government-MINECO through 'Severo Ochoa' (SEV 2012-0267), Consolider Ingenio 2010-Multicat and MAT2012-37160 is acknowledged. The European Union is also acknowledged by the SynCatMatch project (ERC-AdG-2014-671093).Martínez Franco, R.; Paris-Carrizo, CG.; Moliner Marin, M.; Corma Canós, A. (2016). Synthesis of highly stable metal-containing extra-large-pore molecular sieves. Philosophical Transactions A: Mathematical, Physical and Engineering Sciences. 374(2061). https://doi.org/10.1098/rsta.2015.0075S3742061Jiang, J., Yu, J., & Corma, A. (2010). Extra-Large-Pore Zeolites: Bridging the Gap between Micro and Mesoporous Structures. Angewandte Chemie International Edition, 49(18), 3120-3145. doi:10.1002/anie.200904016Moliner, M., Rey, F., & Corma, A. (2013). Towards the Rational Design of Efficient Organic Structure-Directing Agents for Zeolite Synthesis. Angewandte Chemie International Edition, 52(52), 13880-13889. doi:10.1002/anie.201304713Davis, M. E. (1997). The Quest For Extra-Large Pore, Crystalline Molecular Sieves. Chemistry - A European Journal, 3(11), 1745-1750. doi:10.1002/chem.19970031104Davis, M. E. (2002). Ordered porous materials for emerging applications. Nature, 417(6891), 813-821. doi:10.1038/nature00785Corma, A. (2003). State of the art and future challenges of zeolites as catalysts. Journal of Catalysis, 216(1-2), 298-312. doi:10.1016/s0021-9517(02)00132-xCorma, A., Díaz-Cabañas, M. J., Jordá, J. L., Martínez, C., & Moliner, M. (2006). High-throughput synthesis and catalytic properties of a molecular sieve with 18- and 10-member rings. Nature, 443(7113), 842-845. doi:10.1038/nature05238Davis, M. E., Saldarriaga, C., Montes, C., Garces, J., & Crowdert, C. (1988). A molecular sieve with eighteen-membered rings. Nature, 331(6158), 698-699. doi:10.1038/331698a0Corma, A., & Davis, M. E. (2004). Issues in the Synthesis of Crystalline Molecular Sieves: Towards the Crystallization of Low Framework-Density Structures. ChemPhysChem, 5(3), 304-313. doi:10.1002/cphc.200300997Martinez-Franco, R., Moliner, M., Yun, Y., Sun, J., Wan, W., Zou, X., & Corma, A. (2013). Synthesis of an extra-large molecular sieve using proton sponges as organic structure-directing agents. Proceedings of the National Academy of Sciences, 110(10), 3749-3754. doi:10.1073/pnas.1220733110Staab, H. A., & Saupe, T. (1988). ?Proton Sponges? and the Geometry of Hydrogen Bonds: Aromatic Nitrogen Bases with Exceptional Basicities. Angewandte Chemie International Edition in English, 27(7), 865-879. doi:10.1002/anie.198808653Corma, A., Diaz-Cabanas, M. J., Jiang, J., Afeworki, M., Dorset, D. L., Soled, S. L., & Strohmaier, K. G. (2010). Extra-large pore zeolite (ITQ-40) with the lowest framework density containing double four- and double three-rings. Proceedings of the National Academy of Sciences, 107(32), 13997-14002. doi:10.1073/pnas.1003009107(s. f.). doi:10.1021/jp027447Martínez-Franco, R., Sun, J., Sastre, G., Yun, Y., Zou, X., Moliner, M., & Corma, A. (2014). Supra-molecular assembly of aromatic proton sponges to direct the crystallization of extra-large-pore zeotypes. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 470(2166), 20140107. doi:10.1098/rspa.2014.0107Man, P. P., Briend, M., Peltre, M. J., Lamy, A., Beaunier, P., & Barthomeuf, D. (1991). A topological model for the silicon incorporation in SAPO-37 molecular sieves: Correlations with acidity and catalysis. Zeolites, 11(6), 563-572. doi:10.1016/s0144-2449(05)80006-5Wilson ST Flanigen EM. 1986 Crystalline metal aluminophosphates . U.S. Patent 4 567 029.Corà, F., Saadoune, I., & Catlow, C. R. A. (2002). Lewis Acidity in Transition-Metal-Doped Microporous Aluminophosphates. Angewandte Chemie International Edition, 41(24), 4677-4680. doi:10.1002/anie.200290013Hartmann, M., & Kevan, L. (2002). Substitution of transition metal ions into aluminophosphates and silicoaluminophosphates: characterization and relation to catalysis. Research on Chemical Intermediates, 28(7-9), 625-695. doi:10.1163/15685670260469357Šponer, J., Čejka, J., Dědeček, J., & Wichterlová, B. (2000). Coordination and properties of cobalt in the molecular sieves CoAPO-5 and -11. Microporous and Mesoporous Materials, 37(1-2), 117-127. doi:10.1016/s1387-1811(99)00258-9Singh, P. S., Shaikh, R. A., Bandyopadhyay, R., & Rao, B. S. (1995). Synthesis of CoVPI-5 with bifunctional catalytic activity. Journal of the Chemical Society, Chemical Communications, (22), 2255. doi:10.1039/c39950002255Jhung, S. H., Jin, T., Kim, Y. H., & Chang, J.-S. (2008). Phase-selective crystallization of cobalt-incorporated aluminophosphate molecular sieves with large pore by microwave irradiation. Microporous and Mesoporous Materials, 109(1-3), 58-65. doi:10.1016/j.micromeso.2007.04.031Iton, L. E., Choi, I., Desjardins, J. A., & Maroni, V. A. (1989). Stabilization of Co (III) in aluminophosphate molecular sieve frameworks. Zeolites, 9(6), 535-538. doi:10.1016/0144-2449(89)90051-1Frache, A., Gianotti, E., & Marchese, L. (2003). Spectroscopic characterisation of microporous aluminophosphate materials with potential application in environmental catalysis. Catalysis Today, 77(4), 371-384. doi:10.1016/s0920-5861(02)00381-4Yu, T., Wang, J., Shen, M., & Li, W. (2013). NH3-SCR over Cu/SAPO-34 catalysts with various acid contents and low Cu loading. Catalysis Science & Technology, 3(12), 3234. doi:10.1039/c3cy00453hYang, X., Ma, H., Xu, Z., Xu, Y., Tian, Z., & Lin, L. (2007). Hydroisomerization of n-dodecane over Pt/MeAPO-11 (Me=Mg, Mn, Co or Zn) catalysts. Catalysis Communications, 8(8), 1232-1238. doi:10.1016/j.catcom.2006.11.00
3D indoor positioning of UAVs with spread spectrum ultrasound and time-of-flight cameras
Este trabajo propone el uso de un sistema híbrido de posicionamiento acústico y óptico en interiores para el posicionamiento 3D preciso de los vehículos aéreos no tripulados (UAV). El módulo acústico de este sistema se basa en un esquema de Acceso Múltiple por División de Código de Tiempo (T-CDMA), en el que la emisión secuencial de cinco códigos ultrasónicos de espectro amplio se realiza para calcular la posición horizontal del vehículo siguiendo un procedimiento de multilateración 2D. El módulo óptico se basa en una cámara de Tiempo de Vuelo (TOF) que proporciona una estimación inicial de la altura del vehículo. A continuación se propone un algoritmo recursivo programado en un ordenador externo para refinar la posición estimada. Los resultados experimentales muestran que el sistema propuesto puede aumentar la precisión de un sistema exclusivamente acústico en un 70-80% en términos de error cuadrático medio de posicionamiento.This work proposes the use of a hybrid acoustic and optical indoor positioning system for the accurate 3D positioning of Unmanned Aerial Vehicles (UAVs). The acoustic module of this system is based on a Time-Code Division Multiple Access (T-CDMA) scheme, where the sequential emission of five spread spectrum ultrasonic codes is performed to compute the horizontal vehicle position following a 2D multilateration procedure. The optical module is based on a Time-Of-Flight (TOF) camera that provides an initial estimation for the vehicle height. A recursive algorithm programmed on an external computer is then proposed to refine the estimated position. Experimental results show that the proposed system can increase the accuracy of a solely acoustic system by 70–80% in terms of positioning mean square error.• Gobierno de España y Fondos para el Desarrollo Regional Europeo. Proyectos TARSIUS (TIN2015-71564-C4-4-R) (I+D+i), REPNIN (TEC2015-71426-REDT) y SOC-PLC (TEC2015-64835-C3-2-R) (I+D+i)
• Junta de Extremadura, Fondos FEDER y Fondo Social Europeo. Proyecto GR15167 y beca predoctoral 45/2016 Exp. PD16030peerReviewe
Efficient Oligomerization of Pentene into Liquid Fuels on Nanocrystalline Beta Zeolites
[EN] Light alkenes oligomerization, performed in the presence of heterogeneous acid catalysts, is an interesting alternative for the production of clean liquid fuels. The process, when catalyzed by zeolites, is flexible and can be directed to the formation of oligomers in the gasoline, jet fuel, or diesel range by adjusting the reaction conditions and the zeolite's structure. Herein we show how reducing the crystal size of large-pore Beta zeolites down to 10-15 nm and controlling the number and strength distribution of their Bronsted acid sites leads to highly active and stable catalysts, selective to true oligomers within the naphtha and, especially, the diesel range. The shorter diffusion path lengths in the smaller crystallites and the reduced Bronsted acid site density of the two nanosized beta zeolites (10-15 nm) synthesized with Si/Al = 15 lead to 1-pentene conversion above 80% during the 6 h time on stream (TOS) at a space time (W/F) of 2.8 g.h.mol(-1). This value is higher than the olefin conversion obtained for a commercial nanobeta (30 nm) at a 3-fold space time of 9.1 g.h.mol(-1).Financial support by the Spanish Government-MINECO through "Severn Ochoa" (SEV-2016-0683), MAT2015-71261-R and CTQ2015-70126-R, by the Fundacion Ramon Areces through a research project within the "Life and Materials Sciences" program, and by the European Union through ERC-AdG-2014-671093-Syn-CatMatch is acknowledged. M.R.D-R. acknowledges "La Caixa-Severo Ochoa" International PhD Fellowships (call 2015). The Electron Microscopy Service of the Universitat Politecnica de Valencia is acknowledged for their help in sample characterization.Díaz-Rey, MDR.; Paris-Carrizo, CG.; Martínez Franco, R.; Moliner Marin, M.; Martínez, C.; Corma Canós, A. (2017). Efficient Oligomerization of Pentene into Liquid Fuels on Nanocrystalline Beta Zeolites. ACS Catalysis. 7(9):6170-6178. https://doi.org/10.1021/acscatal.7b00817S617061787
Human parvovirus B19 frequency among blood donors after an epidemic outbreak: relevance of the epidemiological scenario for transfusion medicine
A retrospective, cross-sectional study was conducted to determine the frequency of human parvovirus B19 (B19V) infected individuals, viral loads and immunity among blood donors from Argentina, in a post-epidemic outbreak period. B19V DNA and specific IgG were tested in minimum study samples of donors attending a blood bank at Córdoba, Argentina, in 2014. Anti-B19V IgM and viral loads were determined in B19V-positive plasma samples. Seven of 731 samples (0.96%) resulted positive, corresponding to individuals aged 32–53 years, four of them repeat donnors and three first-time donors. Viral loads were <103 IU/mL. None had IgM and 6/7 had IgG, one of them at a high level (in the range of 100–200 IU/ml, and the remaining 5 at low to medium level, 5–50 IU/ml). Thus one case was classified as acute infection (DNA+/IgM-/IgG-) and six as potentially persistent infections (DNA+/IgM-/IgG+). No coinfections with other pathogens of mandatory control in the pre-transfusion screening were detected. Prevalence of IgG was 77.9% (279/358). This study provides the first data of B19V prevalence in blood donors in Argentina, demonstrating high rates of acute and persistent B19V infections and high prevalence of anti-B19V IgG in a post-epidemic period. Further research is needed to elucidate mechanisms/factors for B19V persistence as well as follow-up of recipients in the context of haemo-surveillance programs, contributing to the knowledge of B19V and blood transfusion safety.Fil: Adamo, Maria Pilar. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; ArgentinaFil: Blanco, Sebastian. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; Argentina. Fundación Banco Central de Sangre de Córdoba; ArgentinaFil: Viale, Franco Agustín. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; ArgentinaFil: Rivadera, Sabrina Ximena. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; ArgentinaFil: Rodríguez Lombardi, Gonzalo Ramón. Universidad Nacional de Córdoba. Laboratorio de Hemoderivados; ArgentinaFil: Pedranti, Mauro. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; ArgentinaFil: Carrizo, Rubén Horacio. Fundación Banco Central de Sangre de Córdoba; ArgentinaFil: Gallego, Sandra Veronica. Universidad Nacional de Córdoba. Facultad de Medicina. Instituto de Virología Dr. J. M. Vanella; Argentina. Fundación Banco Central de Sangre de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin
Administración de QoS en ambientes de redes de servicios convergentes
La calidad de servicio (QoS) se ha convertido en un factor muy importante dentro de los servicios convergentes actuales. De esta manera es posible trabajar sobre una plataforma de red cableada, inalámbrica o móvil, dándole soporte de funcionamiento adecuado a servicios emergentes, como voz, video o datos.
En este tipo de ambientes donde convergen diferentes tipos de redes y de aplicaciones es necesario que se establezcan mecanismos que permitan proveer de niveles de QoS adecuados para las aplicaciones que lo necesiten.
Estos mecanismos de QoS se pueden implementar mediante la inclusión de extensiones de QoS a los protocolos existentes o mediante una gestión de tráfico que permita priorizar el tráfico proveniente de aplicaciones sensitivas.
El presente trabajo pretende evaluar el impacto de estas dos opciones en ambientes de red cableadas e inalámbricas donde coexisten aplicaciones con y sin restricciones de QoS.Eje: Arquitectura, Redes y Sistemas OperativosRed de Universidades con Carreras en Informática (RedUNCI
¡Sonamos! : músicas y adolescencias en las escuelas
La educación contemporánea asiste a un agotamiento de ciertas formas y esquemas tradicionales y la educación musical no queda exenta de ello.
Lejos de constituirse como un agregado superfluo a las vidas de quienes concurren a la escuela, la música se presenta
como fuerte interpeladora de sus identidades. Identidades que están emergiendo desde un complejo entramado de tensiones con diversos actores sociales, institucionales y políticos.
Si, al pensar en esta fragilidad de los esquemas tradicionales para enfrentar las realidades actuales centramos la atención en el Nivel Medio, encontraremos que, además, la adolescencia, tal como se la entendía hace tiempo, no existe.
Aparecen “adolescencias” nuevas, constantemente reconfiguradas por el vértigo que plantea el imperio de lo inmediato, que se
corren del lugar tipificado de lo contestatario para asumir una posición más participativa, más constructiva.
¿Qué pueden hacer las escuelas para aproximarse a un replanteo de aquellos esquemas tradicionales desde una perspectiva crítica que observe la complejidad de casos y escape a la aplicación de recetas estandarizadas? ¿Qué podemos aportar desde la clase de Música a esta empresa? ¿Hay aspectos de la clase de música “tradicional” que resulten aún funcionales a estos nuevos desafíos? ¿Qué propósitos, perspectivas y abordajes nos urge replantear? ¿Siguen siendo posibles esas viejas clases de Música “sin música ”, sin componente sonoro? ¿Qué lugar ocupan en la clase de Música de nuestros días la notación musical, la historia de la música y el canto colectivo como contenidos fundantes de la disciplina? ¿Propician las tecnologías nuevas maneras de encontrarnos con las músicas y los músicos en la clase? ¿Cómo configurar el escenario sonoro de nuestras clases? ¿Seguirá circulando el repertorio por caminos conocidos o se “embarrará” con los territorios musicales de los jóvenes?
Son estas, algunas de las preguntas que han motivado el contenido de este libro
An Overview of the 2014 ALMA Long Baseline Campaign
A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to
make accurate images with resolutions of tens of milliarcseconds, which at
submillimeter (submm) wavelengths requires baselines up to ~15 km. To develop
and test this capability, a Long Baseline Campaign (LBC) was carried out from
September to late November 2014, culminating in end-to-end observations,
calibrations, and imaging of selected Science Verification (SV) targets. This
paper presents an overview of the campaign and its main results, including an
investigation of the short-term coherence properties and systematic phase
errors over the long baselines at the ALMA site, a summary of the SV targets
and observations, and recommendations for science observing strategies at long
baselines. Deep ALMA images of the quasar 3C138 at 97 and 241 GHz are also
compared to VLA 43 GHz results, demonstrating an agreement at a level of a few
percent. As a result of the extensive program of LBC testing, the highly
successful SV imaging at long baselines achieved angular resolutions as fine as
19 mas at ~350 GHz. Observing with ALMA on baselines of up to 15 km is now
possible, and opens up new parameter space for submm astronomy.Comment: 11 pages, 7 figures, 2 tables; accepted for publication in the
Astrophysical Journal Letters; this version with small changes to
affiliation
Mejora en la promoción de actividades académicas especializadas y con perfil investigador en materia jurídica, económica y politológica en el ámbito de trabajo de Altos Estudios en Política y Buen Gobierno
Memoria ID-0124. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2014-2015
Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).
Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)
The 2014 ALMA Long Baseline Campaign: An Overview
A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to ~15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from September to late November 2014, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at ~350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy
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