340 research outputs found

    Optimizing both catalyst preparation and catalytic behaviour for the oxidative dehydrogenation of ethane of Ni-Sn-O catalysts

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    [EN] Bulk Ni-Sn-O catalysts have been synthesized, tested in the oxidative dehydrogenation of ethane and characterized by several physicochemical techniques. The catalysts have been prepared by evaporation of the corresponding salts using several additives in the synthesis gel, i.e. ammonium hydroxide, nitric acid, glyoxylic acid or oxalic acid, in the synthesis gel. The catalysts were finally calcined at 500 degrees C in air. Important changes in the catalytic behaviour have been observed depending on the additive. In fact, an important improvement in the catalytic performance is observed especially when some additives, such as glyoxylic or oxalic acid, are used. Thus the productivity to ethylene multiplies by 6 compared to the reference Ni-Sn-O catalyst if appropriate templates are used, and this is the result of an improvement in both the catalytic activity and the selectivity to ethylene. This improved performance has been explained in terms of the decrease of the crystallite size (and the increase in the surface area of catalyst) as well as the modification of the lattice parameter of nickel oxide.The authors would like to acknowledge the DGICYT in Spain (CTQ2015-68951-C3-1-R and CTQ2012-37925-C03-2) for financial support. We also thank the University of Valencia and SCSIE-UV for assistanceSolsona Espriu, BE.; López Nieto, JM.; Agouram, S.; Soriano Rodríguez, MD.; Dejoz, A.; Vázquez, MI.; Concepción Heydorn, P. (2016). Optimizing both catalyst preparation and catalytic behaviour for the oxidative dehydrogenation of ethane of Ni-Sn-O catalysts. Topics in Catalysis. 59(17-18):1564-1572. https://doi.org/10.1007/s11244-016-0674-zS156415725917-18Heracleous E, Lee AF, Wilson K, Lemonidou AA (2005) J Catal 231:159–171Heracleous E, Lemonidou AA (2006) J Catal 237:162–174Savova B, Loridant S, Filkova D, Millet JMM (2010) Appl Catal A 390:148–157Heracleous E, Lemonidou AA (2010) J Catal 270:67–75Solsona B, Nieto JML, Concepcion P, Dejoz A, Ivars F, Vazquez MI (2011) J Catal 280:28–39Skoufa Z, Heracleous E, Lemonidou AA (2012) Catal Today 192:169–176Zhu H, Ould-Chikh S, Anjum DH, Sun M, Biausque G, Basset JM, Caps V (2012) J Catal 285:292–303Skoufa Z, Heracleous E, Lemonidou AA (2012) Chem Eng Sci 84:48–56Zhu H, Rosenfeld DC, Anjum DH, Caps V, Basset JM (2015) ChemSusChem 8:1254–1263Heracleous E, Lemonidou AA (2015) J Catal 322:118–129Solsona B, Concepcion P, Demicol B, Hernandez S, Delgado JJ, Calvino JJ, Nieto JML (2012) J Catal 295:104–114Nieto JML, Solsona B, Grasselli RK, Concepción P (2014) Top Catal 57:1248–1255Popescu I, Skoufa Z, Heracleous E, Lemonidou AA, Marcu IC (2015) PCCP 17:8138–8147Zhang X, Gong Y, Yu G, Xie Y (2002) J Mol Catal A 180:293–298Popescu I, Skoufa Z, Heracleous E, Lemonidou A, Marcu I-C (2015) Phys Chem Chem Phys 17:8138–8147Nakamura KI, Miyake T, Konishi T, Suzuki T (2006) J Mol Catal A 260:144–151Solsona B, Dejoz AM, Vazquez MI, Ivars F, Nieto JML (2009) Top Catal 52:751–757Bortolozzi JP, Gutierrez LB, Ulla MA (2013) Appl Catal A 452:179–188Takeguchi T, Furukawa S, Inoue M (2001) J Catal 202:14–24Richardson JT, Turk B, Twigg MV (1996) Appl Catal 148:97–112Biju V, Khadar MA (2002) J Nanopart Res 4:247–253Van Veenendaal MA, Sawatzky GA (1993) Phys Rev Lett 70:2459–2462Vedrine JC, Hollinger G, Duc TM (1978) J Phys Chem 82:1515–1520Salagre P, Fierro JLG, Medina F, Sueiras JE (1996) J Mol Catal A 106:125–13

    Spatio-temporal patterns of beaked whale echolocation signals in the North Pacific.

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    At least ten species of beaked whales inhabit the North Pacific, but little is known about their abundance, ecology, and behavior, as they are elusive and difficult to distinguish visually at sea. Six of these species produce known species-specific frequency modulated (FM) echolocation pulses: Baird's, Blainville's, Cuvier's, Deraniyagala's, Longman's, and Stejneger's beaked whales. Additionally, one described FM pulse (BWC) from Cross Seamount, Hawai'i, and three unknown FM pulse types (BW40, BW43, BW70) have been identified from almost 11 cumulative years of autonomous recordings at 24 sites throughout the North Pacific. Most sites had a dominant FM pulse type with other types being either absent or limited. There was not a strong seasonal influence on the occurrence of these signals at any site, but longer time series may reveal smaller, consistent fluctuations. Only the species producing BWC signals, detected throughout the Pacific Islands region, consistently showed a diel cycle with nocturnal foraging. By comparing stranding and sighting information with acoustic findings, we hypothesize that BWC signals are produced by ginkgo-toothed beaked whales. BW43 signal encounters were restricted to Southern California and may be produced by Perrin's beaked whale, known only from Californian waters. BW70 signals were detected in the southern Gulf of California, which is prime habitat for Pygmy beaked whales. Hubb's beaked whale may have produced the BW40 signals encountered off central and southern California; however, these signals were also recorded off Pearl and Hermes Reef and Wake Atoll, which are well south of their known range

    Using radium isotopes to characterize water ages and coastal mixing rates: A sensitivity analysis

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W., 2006, PAPERS SUMMER UNDERG, P51 Taniguchi M, 2003, BIOGEOCHEMISTRY, V66, P35, DOI 10.1023/B:BIOG.0000006090.25949.8d Taylor J. R., 1997, INTRO ERROR ANAL, P160 Turner IL, 1997, J COASTAL RES, V13, P46 Weinstein Y., 2006, RADIOACT ENV, V8, P360, DOI DOI 10.1016/S1569-4860(05)08029-0 Windom HL, 2006, MAR CHEM, V102, P252, DOI 10.1016/j.marchem.2006.06.016 Knee, Karen L. Garcia-Solsona, Ester Garcia-Orellana, Jordi Boehm, Alexandria B. Paytan, Adina 4 AMER SOC LIMNOLOGY OCEANOGRAPHY WACO LIMNOL OCEANOGR-METHNumerous studies have used naturally occurring Ra isotopes (Ra-223, Ra-224, Ra-226, and Ra-228, with half-lives of 11.4 d, 3.7 d, 1600 y, and 5.8 y, respectively) to quantify water mass ages, coastal ocean mixing rates, and submarine groundwater discharge (SGD). Using Monte Carlo models, this study investigated how uncertainties in Ra isotope activities and the derived activity ratios (AR) arising from analytical uncertainty and natural variability affect the uncertainty associated with Ra-derived water ages and eddy diffusion coefficients, both of which can be used to calculate SGD. Analytical uncertainties associated with Ra-224, Ra-226, and Ra-228 activities were reported in most published studies to be less than 10% of sample activity; those reported for Ra-223 ranged from 7% to 40%. Relative uncertainty related to natural variability-estimated from the variability in Ra-223 and Ra-224 activities of replicate field samples-ranged from 15% to 50% and was similar for Ra-223 activity, Ra-224 activity, and the Ra-224/Ra-223 AR. Our analysis revealed that AR-based water ages shorter than 3-5 d often have relative uncertainties greater than 100%, potentially limiting their utility. Uncertainties in eddy diffusion coefficients estimated based on cross-shore gradients in short-lived Ra isotope activity were greater when fewer points were used to determine the linear trend, when the coefficient of determination (R-2) was low, and when Ra-224, rather than Ra-223, was used. By exploring the uncertainties associated with Ra-derived water ages and eddy diffusion coefficients, this study will enable researchers to apply these methods more effectively and to reduce uncertainty

    Wines of Mendoza : price on supermarket shelf vs. quality in blind tasting

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    Cuando un posible consumidor de vinos decide su compra, lo hace influenciado por factores relacionados no sólo con la calidad del producto sino también con el conocimiento que tiene de la marca. Esta investigación se inició con un mapeo de vinos ofrecidos en puntos de venta minorista del Gran Mendoza, para luego realizar una degustación a ciegas con panelistas de la provincia de Mendoza, de sectores de ingresos medios, cuya única condición era la de ser consumidor de vinos. Los vinos elegidos para degustar fueron los que tenían presencia importante en los lugares de venta. Además se realizó una selección en góndola simulada, con vinos presentados con sus precios y packaging. La apreciación sensorial se complementó con el precio que el consumidor pagaría por lo que estaba degustando. En la selección en góndola el panelista no eligió el envase tetrabrik aunque después, al degustar a ciegas el producto, había predisposición a pagar mayor precio que el de mercado. La explicación de tal comportamiento podría encontrarse en que el envase tetrabrik podría asociarse a una clase social baja, mientras que la botella a las clases sociales de mayor ingreso. El análisis sensorial (sentidos: visual, olfativo, gustativo y equilibrio) permitió observar que los panelistas otorgan puntuaciones superiores a la media del rango especificado, en los precios más bajos. El consumidor tiene disposición a pagar precios menores a medida que los precios en góndola son más altos.When a potential customer decides to purchase wine, he does so under the influence of factors related not only to the product quality but also to his knowledge of the brand. This research began by mapping the wines offered in retail outlets of Mendoza, followed by blind tasting by a panel with people from middle-income sectors of Mendoza, on the sole condition of being a wine consumer. The wines chosen for tasting were those with significant presence in retail locations. A selection on a simulated supermarket shelf was also conducted, with wines displayed with their price and packaging. Sensory assessment was supplemented with the price the consumer would pay for what he tasted. When selecting from the supermarket shelf, the panelist did not choose the packaging cartons, but then, in doing a blind tasting of the product, he showed willingness to pay a higher price for it than its market value. The explanation for such behavior could be that the packaging carton may be associated to a lower social class, whereas the bottle is related to higher-income classes. The sensory analysis (senses: visual, olfactory, gustatory and balance) allowed us to observe that panelists give above-average scores in the specified range to the lowest prices. The consumer is willing to pay lower prices as prices go higher on the supermarket shelf.Fil: Antoniolli, Ester R.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y Agroalimentarias. Cátedra de Enología II e Industrias Afines.Fil: Alturria, Laura V.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y Agroalimentarias. Cátedra de Enología II e Industrias Afines.Fil: Ceresa, Alejandro M.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y Agroalimentarias. Cátedra de Enología II e Industrias Afines.Fil: Solsona, Juan E.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y Agroalimentarias. Cátedra de Enología II e Industrias Afines.Fil: Winter, Patricia. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y Agroalimentarias. Cátedra de Enología II e Industrias Afines.Fil: Galiotti, Hugo. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y AgroalimentariasFil: Fonzar, Alfredo. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Enológicas y Agroalimentarias. Cátedra de Enología II e Industrias Afines

    Compensación feedforward para controladores de estructura variable empleados en sistemas electrónicos de potencia

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    Este trabajo propone una compensación feedforward para rechazar perturbaciones en sistemas no lineales, del tipo afín en la variable de control, que trabajan bajo control en modo de deslizamiento real. Se obtiene la ley con que debe ser modificado el ciclo de trabajo de las llaves involucradas en el control, para obtener un efectivo rechazo de las perturbaciones. Se hace hincapié en la aplicación de la técnica propuesta a sistemas electrónicos de potencia que emplean la estrategia de control de PWM realimentado.In this paper feedforward compensation in order to reject disturbances for affine nonlinear systems using real sliding mode control strategy is proposed. The law of the modified duty cycle of the switches in order to reject the disturbances is obtained. Application to power electronic systems using the feedbaok PWM strategy is presented.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

    Compensación feedforward para controladores de estructura variable empleados en sistemas electrónicos de potencia

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    Este trabajo propone una compensación feedforward para rechazar perturbaciones en sistemas no lineales, del tipo afín en la variable de control, que trabajan bajo control en modo de deslizamiento real. Se obtiene la ley con que debe ser modificado el ciclo de trabajo de las llaves involucradas en el control, para obtener un efectivo rechazo de las perturbaciones. Se hace hincapié en la aplicación de la técnica propuesta a sistemas electrónicos de potencia que emplean la estrategia de control de PWM realimentado.In this paper feedforward compensation in order to reject disturbances for affine nonlinear systems using real sliding mode control strategy is proposed. The law of the modified duty cycle of the switches in order to reject the disturbances is obtained. Application to power electronic systems using the feedbaok PWM strategy is presented.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

    Redox and Catalytic Properties of Promoted NiO Catalysts for the Oxidative Dehydrogenation of Ethane

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    [EN] NiO and metal-promoted NiO catalysts (M-NiO, with a M/(M+Ni) atomic ratio of 0.08, with M = Nb, Sn, or La) have been prepared, tested in the oxidative dehydrogenation (ODH) of ethane, and characterized by means of XRD, TPR, HRTEM, Raman, XPS, and in situ XAS (using H-2/He, air or C2H6/He mixtures). The selectivity to ethylene during the ODH of ethane decreases according to the following trend: Nb NiO Sn NiO > La NiO > NiO, whereas the catalyst reducibility (determined by both TPR and XAS using H-2/He mixtures) shows the opposite trend. However, different reducibility and catalytic behavior in the absence of oxygen (ethane/He mixtures) have been observed, especially when comparing Nb- and Sn-promoted NiO samples. These differences can be ascribed mainly to a different phase distribution of the promoter. The results presented here are discussed in terms of the nature of active and selective sites for ODH of ethane in selective and unselective catalysts, but also the role of promoters and the importance of their phase distribution.The authors would like to acknowledge the DGICYT in Spain CTQ2012-37925-C03-2, CTQ2015-68951-C3-1-R, and CTQ2015-68951-C3-3-R. Authors thank European Synchrotron Radiation Facility, ESRF (Project CH-4512; BM25-SpLine Beamlime). Authors from ITQ also thank Project SEV-2016-0683 for financial support. D.D. thanks MINECO and Severo Ochoa Excellence Program for his fellowship (SVP-2014-068669). B.S. also thanks UV-INV-AE16-484416. Finally, the authors thank the Electron Microscopy Service of Universitat Politecnica de Valencia for their support.Delgado-Muñoz, D.; Solsona Espriu, BE.; Ykrelef, A.; Rodriguez-Gomez, A.; Caballero, A.; Rodríguez-Aguado, E.; Rodriguez-Castellón, E.... (2017). Redox and Catalytic Properties of Promoted NiO Catalysts for the Oxidative Dehydrogenation of Ethane. The Journal of Physical Chemistry C. 121(45):25132-25142. https://doi.org/10.1021/acs.jpcc.7b07066S25132251421214

    Identification of the rural poverty and some strategies of intervention : Mendoza (Argentina)

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    En Mendoza, Argentina, más del 60 % de los productores agrícolas tiene predios menores de 10 ha, algunos de ellos con modelos productivos que no alcanzan para la sustentabilidad del grupo familiar. La presente investigación identifica la situación actual de la población estudiada, mediante variables de ingreso familiar, grado de asociativismo, características de la comercialización y algunas prácticas de gestión, para establecer comparaciones entre grupos poblacionales. Se trabajó en una muestra de productores regantes del Río Mendoza. Para los de menos de 10 ha se agregó un cuestionario complementario que indagó sobre niveles de asociación y sus resultados. Se analizó con mayor detalle el sector vitícola y olivícola con nuevas encuestas y entrevistas en profundidad. El 42 % de los productores tiene vid, el 30 % olivos y el 28 % horticultura, fruticultura y floricultura. El mayor nivel de asociación se encuentra entre los viticultores. En los demás sectores, éste es muy bajo o nulo. En la comparación de grupos, los mayores niveles de pobreza están en los productores de menos de 10 ha y baja tecnología. Además, en el sector vitícola, los menores niveles de ingreso se encuentran en aquellos no asociados y en toda la población estudiada la pobreza es mayor en el sector asalariado que en los propietarios de la tierra. Este proyecto identifica la capacitación como una de las acciones para mejorar la situación socioeconómica de los productores.In Mendoza, Argentina, more of 60 % of the agricultural producers has smaller estates of 10 ha, with productive models that do not reach the sustentability of the familiar group. This paper identifies actions that improve their socioeconomic situation at the present time, througt of variables of familiar income, level of association and some practice of management for make comparisions between groups. Studied a sample of farmers´s of the Mendoza River. Farmers whose farms were smaller than 10 ha was inqueried with additional questonnaire in order to identify levels of association and their results. Vitiviniculture and olive growing was analyzed with more details, thought news questionnaire and deep interviews. The results show that 42 % of the farmers have got vineyards, 30 % are olive grower and 28 % are farmers that growing vegetables, fruits and flowers. The highest level of association was founded between grapevine growers. In the other activities is very low or null. Comparing groups, majors levels of poverty there are in farmers smaller than 10 ha and low technology. Furthermore in vitiviniculture, the smallest levels of incomes was founded in no associated farmers. Inside the population studied, poverty is greatest in salaried people than owners of farms. This paper identify to training has someone activity for improvement the social and economic situation of the farmersFil: Antoniolli, Ester R.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Alturria, Laura V.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Winter, Patricia. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Eisenchlas, Paula. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Thomas, Marta. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Filippini, María Flavia. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Hiramatsu, Kiyoe. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Solsona, Juan E.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y SocialesFil: Roby, Osvaldo. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Económico-Jurídico y Sociale

    NiO diluted in high surface area TiO2 as efficient catalysts for the oxidative dehydrogenation of ethane

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    [EN] Catalysts consisting of NiO diluted in high surface area TiO2 can be as efficient in the oxidative dehydrogenation of ethane as the most selective NiO-promoted catalysts reported previously in the literature. By selecting the titania matrix and the NiO loading, yields to ethylene over 40% have been obtained. In the present article, three different titanium oxides (TiO2) have been employed as supports or diluters of nickel oxide and have been tested in the oxidative dehydrogenation of ethane to ethylene. All TiO2 used present anatase as the main crystalline phase and different surface areas of 11,55 and 85 m(2) g(-1). It has been observed that by selecting an appropriate nickel loading and the titanium oxide extremely high selectivity towards ethylene can be obtained. Thus, nickel oxide supported on TiO2 with high surface areas (i.e. 55 and 85 m(2) g(-1)) have resulted to give the best catalytic performance although the optimal nickel loading is different for each case. The optimal catalyst has been obtained for NiO-loadings up to 5-10 theoretical monolayers regardless of the TiO2 employed. Free TiO2 is inactive whereas unsupported NiO is active and unselective (forming mainly carbon dioxide) and, therefore, unmodified NiO particles have to be avoided in order to obtain the optimal catalytic performance. The use of low surface area titania (11 m(2) g(-1)) have led to the lowest selectivity to olefin due to the presence of an excess of free NiO particles. (C) 2017 Elsevier B.V. All rights reserved.The authors would like to acknowledge the DGICYT in Spain CTQ2012-37925-C03-2, CTQ2015-68951-C3-1-R, CTQ2015-68951-C3-3-R and SEV-2012-0267 Projects for financial support. D.D. also thanks Severo Ochoa Excellence fellowship (SVP-2014-068669). We also thank the University of Valencia (UV-INV-AE-16-484416 project) and SCSIE-UV for assistanceSanchis, R.; Delgado-Muñoz, D.; Agouram, S.; Soriano Rodríguez, MD.; Vázquez, MI.; Rodriguez-Castellon, E.; Solsona, B.... (2017). NiO diluted in high surface area TiO2 as efficient catalysts for the oxidative dehydrogenation of ethane. Applied Catalysis A General. 536:18-26. https://doi.org/10.1016/j.apcata.2017.02.012S182653
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