Search results for "46"
showing 10 items of 1176 documents
Estudio de la interacción entre el ión Cu(II)y la fosfomicina (ácido L(cis) 1,2 epoxipropilfosfónico) en sus formas epóxido y glicol
1988
La experiencia es limitada en cuanto a las interacciones del ácido L-(cis) 1,2 epoxipropilfosfónico (fosfomicina, antibiótico de amplio espectro) con iones metálicos, aunque se sabe que los ácidos fosfónicos pueden interaccionar con metales como el Cu(II). El objetivo del estudio ha sido obtener un complejo de este ácido y su derivado glicólico (H2F(OH)2, ácido L-(cis) 1,2 dihidroxipropilfosfónico) con el Cu(II) para determinar las propiedades y efectos sobre el antibiótico. En solución acuosa de NaClO4 0.2M a 25  0.2ºC se obtienen dos especies CuF(OH)2 y CuFO(OH)-. El estudio espetrofotométrico permite deducir la existencia de dos puntos isosbésticos, los cuáles resultan útiles par…
Aplicación de la resonancia magnética nuclear de sistemas paramagnéticos a la determinación de propiedades estructurales y dinámicas de las proteínas…
2003
La presente tesis muestra la potencialidad de la Resonancia Magnética Nuclear (RMN) aplicadaa sistemas paramagnéticos a la hora de determinar propiedades estructurales, moleculares y dinámicas de los sistemas de estudio. La RMN paramagnética er información en las proximidades del entorno metálico. En esta Tesis se demuestra, sin embargo, que elparamagnetismo en RMN proporciona datos estructurales (derivados de las velocidades de relajación, de los desplazamientos de pseudocontacto y de los acoplamientos dipolares residuales) que compensan y superan la pérdida de información por relajación.Los sistemas de estudio han sido la proteína azul de cobre (BCP) rusticianina (Rc) y la proteína activa…
Materiales magnéticos moleculares: Diseño de imanes quirales basados en cianuros bimetálicos y de agentes de contraste en IRM basados en complejos me…
2009
El primer capítulo de esta Tesis trata del diseño de imanes quirales basados en cianuros bimetálicos. Se presenta la síntesis y caracterización de diez análogos del azul de Prusia del tipo Ni3Fe2 y Cu3Fe2 obtenidos con los ligandos trans-chxn, trans-(1S,2S)-chxn, trans-(1R,2R)-chxn y cis-chxn (chxn = ciclohexano-1,2-diamina): [Ni(trans-chxn)2]3[Fe(CN)6]2·2H2O (1), [Ni(cis-chxn)2]3[Fe(CN)6]2·2H2O (2), [Ni(trans-(1S,2S)-chxn)2]3[Fe(CN)6]2·2H2O (3), [Ni(trans-(1R,2R)-chxn)2]3[Fe(CN)6]2·2H2O (4), [Cu(cis-chxn)2]3[Fe(CN)6]2·7H2O (5), [Cu(trans-(1S,2S)-chxn)2]3[Fe(CN)6]2·4.5H2O (6), [Cu(trans-(1R,2R)-chxn)2]3[Fe(CN)6]2·4.5H2O (7), [Cu(cis-chxn)]3[Fe(CN)6]2·6H2O (8), [Cu(trans-(1S,2S)-chxn)]3[Fe(C…
The Bishop-Phelps-Bollobás property for bilinear forms and polynomials
2014
For a $\sigma$-finite measure $\mu$ and a Banach space $Y$ we study the Bishop-Phelps-Bollobás property (BPBP) for bilinear forms on $L_1(\mu)\times Y$, that is, a (continuous) bilinear form on $L_1(\mu)\times Y$ almost attaining its norm at $(f_0,y_0)$ can be approximated by bilinear forms attaining their norms at unit vectors close to $(f_0,y_0)$. In case that $Y$ is an Asplund space we characterize the Banach spaces $Y$ satisfying this property. We also exhibit some class of bilinear forms for which the BPBP does not hold, though the set of norm attaining bilinear forms in that class is dense.
L'autentico Gattopardo
2011
Assessing the Open Trenches in Screening Railway Ground-Borne Vibrations by Means of Artificial Neural Network
2009
Reducing ground borne vibrations in urban areas is a very challenging task in railway transportation. Many mitigation measures can be considered and applied; among these open trenches are very effective. This paper deals with the study of the effect, in terms of reduction of vertical and horizontal displacements and velocities, of the open trenches. 2D FEM simulations have been performed and several open trench configurations have been analysed varying the main geometric features such as width and depth, distance from the rail, thickness of the soil layer over the rigid bedrock, type of the ground, ratio between the depth of the trench, and the thickness of the soil layer. For quantifying t…
First measurement of quarkonium polarization in nuclear collisions at the LHC
2021
The polarization of inclusive J/$\psi$ and $\Upsilon(1{\rm S})$ produced in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV at the LHC is measured with the ALICE detector. The study is carried out by reconstructing the quarkonium through its decay to muon pairs in the rapidity region $2.5<y<4$ and measuring the polar and azimuthal angular distributions of the muons. The polarization parameters $\lambda_{\theta}$, $\lambda_{\phi}$ and $\lambda_{\theta\phi}$ are measured in the helicity and Collins-Soper reference frames, in the transverse momentum interval $2<p_{\rm T}<10$ GeV/$c$ and $p_{\rm T}<15$ GeV/$c$ for the J/$\psi$ and $\Upsilon(1{\rm S})$, respectively. The polarization parameter…
Neurophysiological Changes After Paired Brain and Spinal Cord Stimulation Coupled With Locomotor Training in Human Spinal Cord Injury
2021
Neurophysiological changes that involve activity-dependent neuroplasticity mechanisms via repeated stimulation and locomotor training are not commonly employed in research even though combination of interventions is a common clinical practice. In this randomized clinical trial, we established neurophysiological changes when transcranial magnetic stimulation (TMS) of the motor cortex was paired with transcutaneous thoracolumbar spinal (transspinal) stimulation in human spinal cord injury (SCI) delivered during locomotor training. We hypothesized that TMS delivered before transspinal (TMS-transspinal) stimulation promotes functional reorganization of spinal networks during stepping. In this p…
Sistemas híbridos orgánicos-inorgánicos en films de Langmuir-Blodgett
2002
ÉCe travail porte sur la formation et la caractérisation de nouveaux systèmes organiques-inorganiques par l'utilisation de films de Langmuir et de la technique de Langmuir-Blodgett. Plusieurs voies ont ainsi été explorées afin d'obtenir des films minces hybrides aux propriétés multiples, en particulier magnétiques. L'utilisation de l'interaction entre monocouches cationiques et des anions présents en sous-phase a ainsi permis l'organisation de différents polyanions inorganiques en structure lamellaire. Cette stratégie a ensuite été généralisée au cas de colloïdes de Bleu de Prusse, composés bimétalliques étendus. Une large étude (de la préparation à la caractérisation) a été consacrée à ces…
Relationship Between Visual Field Sensitivity and Retinal Nerve Fiber Layer Thickness Measured by Scanning Laser Polarimetry and Optical Coherence To…
2009
Purpose: To evaluate the correlation between automated achromatic perimetry (AAP) and the output of two retinal nerve fiber layer (RNFL) analysers: scanning laser polarimetry (GDx-VCC) and optical coherence tomography (OCT). Methods: Quantitative RNFL measurements with GDx-VCC and Stratus-OCT were obtained in one eye from 52 healthy subjects, 38 ocular hypertensive (OHT) patients and 94 glaucomatous patients. All patients underwent a complete examination, including AAP using the Swedish interactive threshold algorithm (SITA). The relationship between RNFL measurements and SITA visual field global indices were assessed by means of the following methods: analysis of variance, bivariate Pearso…