766 research outputs found

    A Model of Porous Catalyst Accounting for Incipiently Non-isothermal Effects*

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    An approximate model accounting for incipiently non-isothermal effects is derived from a well-known model of porous catalyst for appropriate, realistic limiting values of the parameters. In this limit, the original model is a singularly perturbed, m-D reaction–diffusion system, and the approximate model is given by the m-D heat equation with nonlinear boundary condition, coupled with infinitely many (ifm2) 1-D semilinear parabolic equations, one for each point of the boundary of the spatial domain. Some limiting cases are still considered in the approximate model that lead to further simplifications

    Binap-silver-catalyzed enantioselective multicomponent 1,3-dipolar cycloaddition of azomethines ylides derived from ethyl glyoxylate

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    The enantioselective binap–silver catalyzed multicomponent 1,3-dipolar cycloaddition using ethyl glyoxylate, phenylalanine ethyl ester, and maleimides is described. The employment of basic silver carbonate allows the reaction to take place in the absence of an extra base giving high yields and ee. In addition, low-level calculations regarding the importance of the benzyl substituent at the α-position of the amino ester justify the expected absolute configuration of the final cycloadducts and the observed high enantiodiscrimination.Financial support was provided by the Spanish Ministerio de Ciencia e Innovación (MICINN) (projects CTQ2010-20387, and Consolider Ingenio 2010, CSD2007-00006), the Spanish Ministerio de Economía y Competitividad (MINECO) (projects CTQ2013-43446-P, and CTQ2014-51912-REDC), FEDER, the Generalitat Valenciana (PROMETEO 2009/039 and PROMETEOII/2014/017), and the University of Alicante

    The taxonomic status and the geographical relationships of the Macaronesian endemic moss Fissidens luisieri (Fissidentaceae) based on DNA sequence data

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    Copyright © 2009 by The American Bryological and Lichenological Society, Inc.The taxonomic identity and the geographical relationships of the Macaronesian endemic moss Fissidens luisieri have been studied using the chloroplast trnGUCC intron, the spacer between trnM and trnV, together with the trnV intron and ITS1 and ITS2 sequences. A comparison of F. luisieri with the most closely related species, F. serrulatus, from the same geographical areas reveals that the distribution pattern of F. serrulatus and F. luisieri, rather than their morphological differences, explains the observed differences. Therefore, we conclude that both names correspond to the same species. One of the primers for the chloroplast trnGUCC intron and both primers for the trnM–trnV region were designed for this study; they can all be widely used within bryophytes because they provide similar degrees of variability as other regions of the chloroplast genome such as the atpB–rbcL intergenic spacer

    Distribution patterns of Leucodon species in Macaronesia, with special reference to the Canary Islands

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    Copyright © 2009 Adac. Tous droits réservés.The genus Leucodon is represented in Macaronesia by three species, L. sciuroides, L. canariensis and L. treleasei, the latter two being endemic to this region. An analysis of distribution, frequency and habitats for all three species in this region shows singular patterns for each species, mainly related to habitat conservation and type of habitat. Leucodon canariensis is the most restricted species as regards habitat conditions, with a confirmed presence only on Madeira and the Canary Islands, although more abundant in the latter. Leucodon treleasei exhibits the widest habitat amplitude, especially on Madeira, and it is present in all three northern archipelagos. Leucodon sciuroides is the most tolerant species to aridity and is mainly found on Madeira and the Canary Islands, although its occurrence was confirmed in all the Macaronesian archipelagos

    Supporting Native Indian Preschoolers and Their Families Family–School–Community Partnerships

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    In this urban midwestern public school district, families of Native Indian students, pre-K through grade 12, attend four multigenerational gatherings like this one during the school year—one of a number of events orchestrated by the Native Indian Centered Education (NICE) program. NICE is a program in the school district that partners with families to provide Native-centric educational opportunities for preschool children. Family events such as the storytelling activity in the opening vignette represent trends in early childhood education: building family-school-community partnerships to enhance learning and build family resources. The all- Native-Indian preschool program is unusual and rare in urban areas. (Most all-Native-American preschool programs are located on reservations). It is in its third year of funding from a US Department of Education Experimental Education Grant (four-year grant project)

    Enhancing Luminescence and X-ray Absorption Capacity of Eu3+:LaF3 Nanoparticles by Bi3+ Codoping

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    Bi3+ codoping has been proposed in this work with a twofold objective, namely, enhancing the luminescence emission of Eu3+:LaF3 nanoparticles (NPs) and increasing their X-ray attenuation capacity, with the purpose of obtaining a bimodal bioprobe for luminescence bioimaging and X-ray computed tomography. The synthesis method, reported here for the first time for LaF3 particles, allowed obtaining uniform, nonaggregated NPs using a homogeneous precipitation in polyol medium at room temperature in just 2 h. The simplicity of the synthesis method allows the large-scale production of NPs. LaF3 NPs with different Eu3+ contents were first synthesized to find the critical Eu3+ concentration, producing the highest emission intensity. This concentration was subsequently used to fabricate Bi3+-Eu3+-codoped LaF3 NPs using the same method. The emission intensity of the codoped NPs increased in more than one order of magnitude, thanks to the possibility of excitation through the Bi3+ ¿ Eu3+ energy-transfer band. The luminescence properties of the codoped NPs were analyzed in detail to find the mechanism responsible for the emission enhancement. Finally, it was demonstrated that the high atomic number of Bi3+, higher than that of lanthanides, was an added value of the material because it increased its X-ray attenuation capacity. In summary, the LaF3 NPs codoped with Eu3+ and Bi3+ presented in this work are promising candidates as a bimodal bioprobe for luminescence bioimaging and X-ray computed tomography

    The Asymptotic Justification of a Nonlocal 1-D Model Arising in Porous Catalyst Theory*

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    An asymptotic model of isothermal catalyst is obtained from a well-known model of porous catalyst for appropriate. realistic limiting values of some non dimensión al paiameters. In tliís limit, the original model is a singularly perturbed m-D reactiondiflusion system. The asymptotic model consists of an oidinary difleiential equation coupled with a semilinear parabolic equation on a semi-infmite one-dimensión al interval

    Teleoperación de Instrumentos Quirúrgicos Articulados

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    En este trabajo se describe la plataforma CISOBOT, desarrollada por la Universidad de Málaga para intervenciones de cirugía mínimamente invasiva, así como su ampliación a través del diseño mecatrónico de un instrumento motorizado que permite mover el extremo de este. El objetivo de esta plataforma es el estudio de nuevos algoritmos de control que permitan la teleoperación bilateral y el empleo de guiado hápticoUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
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