1,162 research outputs found

    Recommendations and guidelines for applied nutrition experiments in rabbits

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    [EN] The aim of this paper was to draw up a set of recommendations for applied nutrition and feeding trials with rabbits, in relation to certain aspects such as determining the nutritive value of raw materials or diets in growing or reproducing animals, studying digestive physiology and obtaining growth and reproduction parameters. We deal first with animals, size of the sample, housing conditions, diets, handling, measurements, and the data analyses relevant to the design of the experiment are described. Secondly, we give a list of recommended items and include some comments.This study was partly supported by the EUROPEAN COMMISSION (ERAFE program and the COST 848 Action).Fernández-Carmona, J.; Blas, E.; Pascual Amorós, JJ.; Maertens, L.; Gidenne, T.; Xiccato, G.; García, J. (2005). Recommendations and guidelines for applied nutrition experiments in rabbits. World Rabbit Science. 13. doi:10.4995/wrs.2005.516SWORD1

    Activation of H-H, HO-H, C(sp2)-H, C(sp3)-H, and RO-H bonds by transition-metal frustrated lewis pairs based onon M/N (M = Rh, Ir) couples

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    Reaction of the dimers (Cp*MCl)2(µ-Cl)2] (Cp* = 5-C5Me5) with Ph2PCH2CH2NC(NH(p-Tolyl))2 (H2L) in the presence of NaSbF6 affords the chlorido complexes Cp*MCl(¿2N, P-H2L)]SbF6] (M = Rh, 1; Ir, 2). Upon treatment with aqueous NaOH, solutions of 1 and 2 yield the corresponding complexes Cp*M(¿3N, N', P-HL)]SbF6] (M = Rh, 3; Ir, 4) in which the ligand HL presents a fac ¿3N, N', P coordination mode. Treatment of THF solutions of complexes 3 and 4 with hydrogen gas, at room temperature, results in the formation of the metal hydrido-complexes Cp*MH(¿2N, P-H2L)]SbF6] (M = Rh, 5; Ir, 6) in which the N(p-Tolyl) group has been protonated. Complexes 3 and 4 react with deuterated water in a reversible fashion resulting in the gradual deuteration of the Cp* group. Heating at 383 K THF/H2O solutions of the complexes 3 and 4 affords the orthometalated complexes Cp*M(¿3C, N, P-H2L-H)]SbF6] M = Rh, 7; Ir, 8, H2L-H = Ph2PCH2CH2NC(NH(p-Tolyl))(NH(4-C6H3Me))], respectively. At 333 K, complexes 3 and 4 react in THF with methanol, primary alcohols, or 2-propanol giving the metal-hydrido complexes 5 and 6, respectively. The reaction involves the acceptorless dehydrogenation of the alcohols at a relatively low temperature, without the assistance of an external base. The new complexes have been characterized by the usual analytical and spectroscopic methods including the X-ray diffraction determination of the crystal structures of complexes 1-5, 7, and 8. Notably, the chlorido complexes 1 and 2 crystallize both as enantiopure conglomerates and as racemates. Reaction mechanisms are proposed based on stoichiometric reactions, nuclear magnetic resonance studies, and X-ray crystallography as well as density functional theory calculations. © 2022 The Authors. Published by American Chemical Society

    Formaciones de "Antirrhinum majus" en los territorios hispalenses

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    Stands of Antirrhinum majus in the Hispalense sectorPalabras clave. Asociación, sintaxonomia, corología, sur Península Ibérica, Echio boissieri-Antirrhinetum majii.Key words. Association, syntaxonomy, chorology, south of the Iberian Peninsula, Echio boissieri-Antirrhinetum majii

    Una nueva asociación de matorral gipsófilo para el Sur de España (Provincia Bética)

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    El estudio de los matorrales gípsicos en el sur de España, revela la presencia de una comunidad diferente del resto de asociaciones descritas hasta el momento dentro de la alianza Lepidion subulati, al existir diferencias florísticas, ecológicas y biogeográficas. Por ello se propone la asociación Ononido angustifolii-Anthyllidetum cytisoidi nova, con un área subbética e hispalense, que se presenta en ambientes, secos y subhúmedos, sobre substratos gípsicos, los cuales dependiendo del ombrotipo se encuentran más o menos lavados, por lo que el matorral puede presentar más o menos gipsófitos estrictos. Asociación que se desarrolla sobre sustratos gípsicos, los cuales experimentan una pérdida de sales en ambientes seco-subhúmedos, por lo que esta nueva comunidad presenta un bajo porcentaje de gipsófilos estrictos frente a una mayor frecuencia de especies menos estrictas. Por lo que se propone la nueva alianza Resedo constrictae-Helianthemion syriacae nova de distribución ibérico-magrebíA study of the thickets growing on gypsum soils in the south of Spain reveals the presence of a community different from the other associations already described within the suballiance Lepidienion subulati as a result of the floristic, ecological and biogeographical differences. Therefore, we propose the association Ononido angustifolii-Anthyllidetum cytisoidi nova with a Subbetic and Hispalensean distribution. The association occurs in semiarid, dry and subhumid environments, on gypsum soils which, depending on the ombrotype, are more or less washed-out and, consequently, the thicket may comprise more o less strict gypsophytes. The association grows on gypsum soils which undergo salt deprivation in dry-subhumid environments. Thus, in this new community the percentage of strict gypsophilous taxa is low as compared to the number of less strict gypsophytes. To propose the new alliance Resedo constrictae-Helianthemion syriacae iberico-magrebi distribution

    Equations of motion, Noncommutativity and Quantization

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    We study the relation between a given set of equations of motion in configuration space and a Poisson bracket. A Poisson structure is consistent with the equations of motion if the symplectic form satisfy some consistency conditions. When the symplectic structure is commutative these conditions are the Helmholtz integrability equations for the nonrestricted inverse problem of the calculus of variations. We have found the corresponding consistency conditions for the symplectic noncommutative case.Comment: 18 pages, to appear PL

    Asymmetric 1, 3-dipolar cycloaddition reactions between methacrylonitrile and nitrones catalysed by well-defined M(diphosphane) (M=Rh, Ir) complexes

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    The cationic half-sandwich aqua-complexes (¿ 5-C5Me5)M(PP*)(H2O)]SbF6]2 M=Rh, Ir; PP* =(R)-Benphos, (R)-Cyphos, (2R, 4R)-Norphos] catalyse the 1, 3-dipolar cycloaddition reaction of nitrones with methacrylonitrile with perfect regioselectivity, low-to-perfect endo-selectivity and low-to-moderate enantioselectivity. The active species involved in the catalytic process, (¿ 5-C5Me5)M(PP*)(methacrylonitrile)]SbF6]2, have been isolated and characterised as mixtures of the (S)- and (R)-at-metal epimers. NMR measurements of these mixtures indicated that the (R M)-isomers epimerise to the corresponding (S M) counterparts. The molecular structure of the rhodium complex (S Rh, R C)-(¿ 5-C5Me5)Rh((R)-Benphos)(methacrylonitrile)]SbF6]2 has been determined by X-ray diffraction methods. Diastereomerically pure (S Rh, R C)-(¿ 5-C5Me5)Rh(PP*)(methacrylonitrile)]SbF6]2 compounds catalyse stoichiometrically the above mentioned dipolar cycloaddition reaction with up to 90% enantiomeric excess, thus indicating the influence of the metal handedness on the catalytic stereochemical outcome. Catalysts can be recycled up to three times without a significant loss of either activity or selectivity

    Cobalt (II) environment characterization in sol-gel thermochromic sensors

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    Optical absorption and magnetic properties of silica sol-gel monoliths doped with cobalt starting from different precursors and water/1-propanol molar ratios are investigated. Structural characterization of the sol-gel by X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy corroborate, that oxidising state of cobalt is Co^(2+). Furthermore, the Co^(2+) first neighbors are O atoms displaying a temperature transition from octahedral to tetrahedral coordination. The doped monoliths show thermochromic sensor activity ranging from 10 to 50⁰ C, which is related to the environment of Co^(2+) ions. The magnetic susceptibility also varies with Co^(2+) ions environment due to changes in the orbital contribution to the magnetic moment. Thus, we achieve a better understanding about environment of the Co^(2+) ions in the gel matrix and explain their reversible temperature behaviour in spite of the rigid state of the host matrix

    Noncommutative Quantum Cosmology

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    We consider noncommutative quantum cosmology in the case of the low-energy string effective theory. Exacts solutions are found and compared with the commutative case.The Noncommutative quantum cosmology is considered in the case of the low-energy string effective theory. Exacts solutions are found and compared with the commutative case.Comment: Revtex4, 3 pages, 2 figures, to appear in Gen.Rel.Gra
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