Poscondicionamiento isquémico y duración de la isquemia previa

Ischemic postconditioningPostcondicionament isquèmicPostcondicionamiento isquémicoJ.A. Barrabés received research funds from Instituto de Salud Carlos III (PI20/01681 project) and Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV) co-financed by the European Regional Development Fund

Selective Hydrogenation Catalysts For Environmental Processes: Nitrate And Chlorocompounds Removal

En el presente trabajo se han diseñado, sintetizado y caracterizado catalizadores heterogéneos. Se ha estudiado la actividad y selectividad, de estos materiales, en el tratamiento de compuestos que comportan problemas medioambientales. Para la preparación de los catalizadores se han utilizado diferentes técnicas tales como impregnación, proceso redox y combustión. A su vez, se han sintetizado nanopartículas metálicas, depositándolas en diferentes materiales y testado su actividad catalítica. La actividad de estos catalizadores se ha comparado con catalizadores comunes en diferentes procesos. Por otro lado, se han utilizado diferentes materiales, alumina, carbón activo, ceria e hidrotalcitas, con el propósito de estudiar el efecto del soporte.La contaminación por nitratos en las aguas subterráneas es un problema importante en determinadas regiones. Esta problemática ha impulsado el estudio de la eliminación catalítica de los nitratos, en la que se enfoca la primera parte de la tesis. Este estudio se realizó en un reactor en continuo de lecho fijo. Se sintetizaron, caracterizaron y ensayaron, varios catalizadores monometálicos, bimetálicos y de nanopartículas soportadas. Una vez determinada la actividad y la estabilidad de los catalizadores se procedió a optimizar los materiales con el fin de mejorar la selectividad de éstos hacia nitrógeno. El presente trabajo ha sido el punto de partida para la puesta en marcha de una planta piloto para el tratamiento de aguas subterráneas reales contaminadas con nitratos. Próximamente será inaugurada una planta de eliminación catalítica de nitratos de aguas subterráneas con capacidad 500m3/día en las proximidades de El Morell (Tarragona).La segunda parte de la tesis se enfoca en el proceso de hidrodecloración catalítica de compuestos orgánicos clorados como el tricloroetileno. Los experimentos se llevaron a cabo en fase gas utilizando diferentes tipos de catalizadores, los cuales fueron sintetizados y caracterizados. Se emplearon diferentes catalizadores, mono y bimetálicos, para la transformación del tricloroetileno a un producto de valor añadido, como es el etileno.El presente trabajo, además de aportar conocimientos fundamentales en la catálisis heterogénea, contribuye a forjar soluciones a problemas medioambientales reales que afectan a la salud humana.In the present study have been designed, synthesised and characterised heterogeneous catalysts. Their activities and selectivity have been studied in the treatment of compounds that present environmental problems. For the catalysts preparation different protocols such as incipient-wetness impregnation, co-impregnation, redox and combustion have been followed. In addition, metal nanoparticles were synthesized and deposited on several materials as well as tested their catalytic behaviour. The activity and the selectivity of nanoparticle catalysts with that of other catalysts in different processes were compared. On the other hand, different materials such as alumina, active carbon, ceria and hydrotalcites were used to study the role of them as catalyst supports.In the light of the current demand for drinking water, the first part of this thesis studies the catalytic hydrogenation of nitrates. The study is carried out in a fixed bed continuous reactor. Several bimetallic, monometallic and supported nanoparticle catalysts have been synthesised, characterized and tested in order to improve their activity and stability and to optimise their selectivity to nitrogen. The present study was further extended and some of the catalysts have been used as a starting point for a Pilot Plant investigation into eliminating nitrate in real ground water. At this moment, a plant is being constructed in the vicinity of El Morell, Tarragona, which can use catalysis to reduce nitrates in 500 m3/day of groundwater.The second part of the thesis deals with the catalytic hydrodechlorination of chlorinated organic compounds such as TCE. The experiments were done in gas phase. Different types of catalysts have been synthesised, characterized and tested and the final objective is to obtain an active and stable catalyst that is selective toward valuable products such as ethylene. This research aims to use catalytic technologies to contribute to solving real environmental problems that affect human life

Predicció de complicacions maternes i fetals en pacients amb Pre-eclàmpsia

PE is classified as the third cause of global maternal deaths and it is also associated with increased perinatal morbidity and mortality, For all these conditions, an accurate identification of those patients at highest risk of complications remains a goal for modern obstetrics in developed countries. This would lead to a more appropriate management of these high-risk patients with a more intensive strategy and the possibility of home monitoring for those patients with a low-risk of complications. Third-trimester abnormal uterine artery Doppler has been related to worse perinatal outcomes among patients both with and without pregnancy complications. Furthermore, in PE clinical severity has been directly related to the extension of placental ischemia: the larger the ischemia, the more severe the clinical manifestations and the poorer the perinatal outcome. However, the role of uterine artery Doppler evaluation in the identification of pregnancy at risk of maternal or foetal morbidity with early-onset PE has not been investigated. In that context, our first article evaluated the performance of Uterine Doppler in the prognostic assessment of adverse outcomes. Our second article further explored the performance of Uterine Doppler in early-PE. Moreover, the excess in anti-angiogenic factors produced by the placenta may cause damage to the vasculature and distal orga. Karumanchi et al. showed that excess sFlt-1 would mediate the multiple symptoms of PE. Parallel, circulating PlGF levels are much lower in those patients who would develop PE than in normal pregnancies. The concentration of circulating PlGF begins to decrease 9 to 11 weeks before the onset of pre-eclampsia, with substantial reductions during the 5 weeks before the onset of hypertension or proteinuria. In that context, placental growth factor (PlGF) has emerged as a potential tool to be included in diagnostic and prognostic algorithms. This pro-angiogenic marker seems to be a more sensitive and precise predictor of PE than any other single biomarker, as it reflects placental function. Low concentrations of PlGF may reflect poor placentation and thus a response to oxidative stress in the placenta, which are mainly present in early PE. However, this excellent profile of PlGF as a marker of early PE may limit its clinical applicability for prognostic assessment if a high number of women already have very low levels at the onset of PE. The median of PlGF was of 12 pg/mL in women with either early onset or preterm PE. According to our results: 1- Uterine Doppler was the best predictive parameter for perinatal outcomes in pregnancies with PE and it was even more effective than classical clinical parameters 2- Uterine Doppler should be incorporated in the management strategy of PE at the clinical onset of the disease 3- Early-onset preeclamptic patients with impaired uterine Doppler are at higher risk of maternal and neonatal complications. 4- Uterine Doppler may help in the prognostic evaluation of early-PE and should be incorporated in the management strategy at its clinical onset 5- Very low PlGF is a highly prevalent finding in early onset PE leading to its low specificity and low positive predictive value 6- The predictive role of a low PlGF level in predicting maternal complications in very early PE is limite

Pseudo-heteroclinic connections between bicircular restricted four-body problems

In this paper, we show a mechanism to explain transport from the outer to the inner Solar system. Such a mechanism is based on dynamical systems theory. More concretely, we consider a sequence of uncoupled bicircular restricted four-body problems –BR4BP –(involving the Sun, Jupiter, a planet and an infinitesimal mass), being the planet Neptune, Uranus and Saturn. For each BR4BP, we compute the dynamical substitutes of the collinear equilibrium points of the corresponding restricted three-body problem (Sun, planet and infinitesimal mass), which become periodic orbits. These periodic orbits are unstable, and the role that their invariant manifolds play in relation with transport from exterior planets to the inner ones is discussed.Peer ReviewedPostprint (published version

Lightlike Branes as Natural Candidates for Wormhole Throats

We first briefly present a consistent world-volume Lagrangian description of lightlike p-branes (LL-branes) in two equivalent forms - a Polyakov-type and a dual to it Nambu-Goto-type formulations. The most important characteristic features of LL-brane dynamics are: (i) the brane tension appears as a non-trivial additional dynamical degree of freedom; (ii) consistency of LL-brane dynamics in a spherically or axially symmetric gravitational background of codimension one requires the presence of an event horizon which is automatically occupied by the LL-brane ("horizon straddling"). Next we consider a bulk Einstein-Maxwell system interacting self-consistently with a codimension one LL-brane. We find spherically symmetric traversable wormhole solutions of Misner-Wheeler type produced by the LL-brane sitting at the wormhole throat with wormhole parameters being functions of the dynamical LL-brane tension.Comment: Contribution to 4th RTN "Forces-Universe" Workshop, Varna (Sept. 2008

Invariant manifolds of L_3 and horseshoe motion in the restricted three-body problem

In this paper, we consider horseshoe motion in the planar restricted three-body problem. On one hand, we deal with the families of horseshoe periodic orbits (which surround three equilibrium points called L3, L4 and L5), when the mass parameter µ is positive and small; we describe the structure of such families from the two-body problem (µ = 0). On the other hand, the region of existence of horseshoe periodic orbits for any value of µ ∈ (0, 1/2] implies the understanding of the behaviour of the invariant manifolds of L3. So, a systematic analysis of such manifolds is carried out. As well the implications on the number of homoclinic connections to L3, and on the simple infinite and double infinite period homoclinic phenomena are also analysed. Finally, the relationship between the horseshoe homoclinic orbits and the horseshoe periodic orbits are considered in detail

Las didácticas específicas: consideraciones sobre principios y actividades.

Las didácticas específicas son parte significativa de la didáctica general, formas de su concreción. Su objeto es hacer educativo el conocimiento que les concierne en cada caso. La dificultad estriba en la forma de su comunicación. En este sentido se busca concretarlas, con finalidad aclaradora, para las matemáticas y las ciencias de la naturaleza

On central configurations of the kn-body problem

We consider planar central configurations of the Newtonian kn-body problem consisting in k groups of regular n-gons of equal masses, called (k, n)-crown. We derive the equations of central configurations for a general (k, n)-crown. When k = 2 we prove the existence of a twisted (2, n)-crown for any value of the mass ratio. Moreover, for n = 3,4 and any value of the mass ratio, we give the exact number of twisted (2, n)-crowns, and describe their location. Finally, we conjecture that for any value of the mass ratio there exist exactly three (2, n)-crowns for n = 5.Peer ReviewedPostprint (author's final draft

Relativistic dynamics of cylindrical shells of counter-rotating particles

Although infinite cylinders are not astrophysical entities, it is possible to learn a great deal about the basic qualitative features of generation of gravitational waves and the behavior of the matter conforming such shells in the limits of very small radius. We describe the analytical model using kinetic theory for the matter and the junction conditions through the shell to obtain its equation of motion. The nature of the static solutions are analyzed, both for a single shell as well as for two concentric shells. In this second case, for a time dependent external shell, we integrate numerically the equation of motion for several values of the constants of the system. Also, a brief description in terms of the Komar mass is given to account for the gravitational wave energy emitted by the system.Comment: 19 pages, 8 figure

On strictly convex central configurations of the 2n-body problem

We consider planar central configurations of the Newtonian 2n-body problem consisting in two twisted regular n-gons of equal masses. We prove the conjecture that for n=5 all convex central configurations of two twisted regular n-gons are strictly convex.Peer ReviewedPostprint (author's final draft