525 research outputs found

    Gas-solid conversion in fluidised bed reactors

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    Asimplified model for gas–solid reactions in fluidised bed (FB) is proposed. Such models already exist for catalytic gas–solid reactions (CGSRs), providing general description of the system in terms of main governing parameters. Expansion of this approach to non-catalytic gas–solid reactions (NCGSRs) is difficult, because the solid reactant takes part in the reaction. Therefore, FB reactor models for NCGSR are usually devised only for specific cases, and a general analysis has not been presented up to date. The present model allows analysis of different types of NCGSR in a generalised way, handling catalytic reactions as a particular, simpler, case. It is shown that the reactor behaviour can be described by three governing dimensionless parameters. Two additional parameters, quantifying the importance of diffusion effects in single particles are also identified, and their impact on reactor behaviour is analysed. Possible simplifications are explored. Model limitations, that is, assumption of isothermal bed and particle and the occurrence of only one reaction, are discussed. Examples are outlined to show the applicability of the methodPublicad

    Switching to efficient technologies in traditional biomass intensive countries: The resultant change in emissions

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    This paper aims to quantify the benefits of switching from a system dependent on traditional biomass to systems running on more efficient fuels and technologies. It is estimated that even when open fires burning fuelwood are replaced by improved cooking stoves (ICSs) and liquefied petroleum gas (LPG) stoves, and biomass is processed in dedicated biomass power plants, a net reduction in CO2 emissions is still obtained. The ICS/LPG stove/biomass combustion power plant configuration could provide an average net reduction of 84 kg-C-e/tDM. Meanwhile, a net reduction of 105 kg-C-e/tDM could be obtained when implementing a ICS/LPG stove/biomass gasification power plant scheme. Main factors influencing the net reduction of CO2 emissions are technology efficiency and the fraction of non-renewable fuel wood use. The switch from traditional biomass to modern biomass in traditional biomass intensive countries must not only be done to reduce CO2 emissions but also to avoid indoor pollution and energy poverty. Health improvements should be more important than energy savings. Results also indicate that the use of modern biomass systems not only could provide a reduction of local environmental pollution, but also could boost the local economy by the creation of biomass infrastructures

    Preparation and optimization of a titanium-based feedstock for Fused Deposition Modeling

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    In this work the preparation and optimization of a titanium-based metal injection moulding (MIM) feedstock for Fused Deposition Modeling (FDM) is presented. The composition of the plastic binder system, consisting of a backbone polymer, a water-soluble polymer and a lubricant was optimized and MIM feedstocks with titanium contents ranging from 50 to 68 vol.% were prepared in a laboratory-scale internal mixer. During the feedstock preparation the torque of the mixing screws of the internal mixer was recorded, which allowed to determine an optimum Ti content of 59–61 vol.%. The morphology, thermal and rheological properties of the prepared MIM feedstocks were characterized using various techniques such as optical microscopy, SEM, FTIR, DSC, TGA, MFI and oscillatory rheometry. This study contributes to the emerging research on additive manufacturing of MIM feedstocks with the aim of producing pure titanium components with complicated shapes and high density from novel MIM feedstock as the starting material

    The role of Cis-Regulatory elements in morphological adaptation to cave environment in Astyanax mexicanus

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    Trabajo presentado en EMBO Workshop Enhanceropathies: Understanding enhancer function to understand human disease, celebrado en Santander (España) del 06 al 09 de octubre de 2021

    Genome evolution in morphological adaptation to cave environment in Astyanax mexicanus

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    Trabajo presentado en el EMBO Workshop The evolution of animal genomes, celebrado en modalidad virtual del 13 al 17 de septiembre de 2021

    In vitro performance of fluticasone/salmeterol pressurized metered dose inhaler in combination with three different valved holding chambers

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    Spacer devices are used to optimize airway aerosol deposition from pressurized metered-dose inhalers (pMDI). The in vitro performance of the combination fluticasone/salmeterol pMDI alone and connected to 3 different valved holding chambers (VHC) was compared by measuring impactor entry port (“throat”) deposition and fine particle dose (FPD) of each medication. Salmeterol (SX) and Fluticasone (FP) throat deposition was reduced over 90 % by all VHC compared to pMDI alone (p < 0,001). The FPD obtained from pMDI alone and connected to VHCs Vortex®, AeroChamber Plus® and Able Spacer® for Salmeterol (25 μg nominal dose) were 12.2 ± 0.7, 12.5 ± 0.5, 11.6 ± 0.8, and 7.9 ± 0.9 μg, respectively. For Fluticasone (125 μg nominal dose) the FPD were 42.5 ± 2.6, 36.3 ± 3.1, 39.8 ± 2.4, and 22.8 ± 3.5 μg, respectively. There were no statistical differences in FPD between devices, except for AbleSpacer® that delivered a lower FPD for both drugs (p < 0.001).Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Revista de Vertebrados de la Estación Biológica de Doñana

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    The Osteology of Barbus bocagei (Steindachner, 1866) (Pisces: Cyprinidae).El crecimiento del Cacho (Leuciscus cephalus pyraenaicus Günther, 1862) en el rio Jarama (cuenca del Tajo)Contribución al estudio de la bermejuela, Rutilus arcasi, Steindachner 1866 de la cuenca del Júcar (Osteichthyes: Cyprinidae) 1. MorfometríaDimensiones, estructura, forma y disposición en la cavidad de los nidos de Corvus monedula.Variaciones altitudinales en la composición de las comunidades nidificantes de aves de Sierra Nevada (Sur de España)Ecomorfología de una comunidadde Passeriformes en la Sierra de Cazorla, SE de EspañaLa Distribución del pez-sol (Lepolllis gibbostlS L.) en la Península IbéricaSobre la distribución de Barbus haasi (OSTARIOPHYSI: CYPRINIDAE)La Distribución de Barbus bocagei STEINDACHNER, 1865 (OSTARIOPHYSI: CYPRINIDAE) en la Península IbéricaLighy effects on circadian locomotor activity of Lacerta lepida under constant temperatureEvaluación de diferentes métodos para estimar el área de campeo de dos especies de iguánidos.Un Casal de Cartaxo-Nottenho (Saxicola rubetra) a criar em Portugal.Nidificación de Passer hispaniolensis en antiguos nidos de Dendrocopos major thanneri.Observación de un lince ibérico (Lynx pardina) en la provincia de Lugo. Norte de España.El Visón americano, Mustela vison SCHREBER, 1777 (MAMMALIA, MUSTELIDAE) en Cataluña, N.E. de la Península Ibérica.Peer reviewe

    Transiciones, conflictos y democracia : estudios de coyuntura

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    México ha vivido un largo proceso de transición que ha desencadenado dinamismos económicos, culturales y políticos. En la actual coyuntura, estos dinamismos muestran toda su complejidad, su inevitable articulación y la tensión entre las fuerzas que intentan sostener un viejo modelo de gobernar y decidir el rumbo del país, y aquellas que buscan abrirse a un espectro mucho más amplio y diversificado de actores. En ellos se conjuntan las aspiraciones más legítimas de los mexicanos por avanzar en el reconocimiento y respeto de la pluralidad étnica, de género y entre generaciones, y por impulsar una dinámica en la que —en medio de los procesos de mundialización— los distintos grupos e intereses de los mexicanos puedan ser incluidos. La transición mexicana tiende a centrarse en la dimensión política. La intensidad que cobran los procesos políticos y el énfasis que importantes analistas ponen en dichos procesos, contribuyen a que esta asociación vaya cobrandoíuerza. En este sentido, es necesario advertir que en las transiciones la tendencia privatizadora, la reducción del gasto social, así como la necesidad de pactos sociales que sean respetados, la participación creciente de la sociedad civil, etc. son factores importantes que, en medio de contradicciones, van generando nuevos esquemas de relación entre gobierno y sociedad.ITESO, A.C
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