53 research outputs found

    The Cambrian of the Iberian Peninsula : an overview

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    This work is a brief overview of the Cambrian in the Iberian Peninsula, along with an updated review of lithostratigraphic and biostratigraphic data. A Cambrian correlation chart between the different stratigraphical units that have been established in the Iberian Peninsula is given. We also reappraise the Lower and Middle Cambrian regional stages in the light of new palaeontological data, and the different biozonations proposed with several palaeontological groups

    Las células troncales pluripotenciales en la terapia celular

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    Las células con pluripotencialidad inducida (iPS) son un nuevo tipo de célula troncal derivada de células somáticas humanas, mediante reprogramación con factores de transcripción. Estas células iPS tienen características de las células troncales embrionarias, como la capacidad de convertirse en todos los tipos de células diferenciadas del organismo. A corto plazo, las células de pacientes reprogramadas están siendo útiles para crear modelos celulares de enfermedades, en las que estudiar los procesos patológicos y probar fármacos. A pesar de algunas críticas, se ha ido acumulando evidencia en los trabajos preclínicos, sobre la efectividad de la terapia celular con los clones de iPS apropiadamente seleccionados. La generación de células iPS ha propiciado el desarrollo de otras técnicas,como por ejemplo, la transdiferenciación por la que se convierte directamente in vivo fibroblastos cardiacos en miocitos. Este tipo celular pluripotencial es de un gran valor en la investigación biomedicina y abre nuevas posibilidades a la terapia celular.Induced pluripotent stem (iPS) cells are a novel stem cell population derived from human somatic cells through reprogramming using a set of transcription factors. These iPS cells were shown to share the characteristics of embryonic stem cells, including the ability to give rise to differentiated cells of every tissue type of the body. In the shorter term, iPS cells will be useful for creating patient-identical disease model cells in which the pathological process can be studied and drugs can be tested. Despite critical attitudes, accumulating preclinical evidence supports the effectiveness of iPSCbased cell therapy on the selection of appropriate iPSC clones. The production of iPS cells has also spurred the development of other techniques, for example, transdifferentiation by researchers can now convert heart fibroblasts directly in vivo into myocytes by similar methods. This pluripotent cells is indeed of great value in medical research and it is opening new possibilities in cell therapy

    A new occurence of the genus Tonkinella in northern Spain and the Middle Cambrian intercontinental correlation

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    The genus Tonkinella is a typical polimeroid trilobite in lower Middle Cambrian rocks from Vietnam, Canada, U.S.A., India, Korea, Siberia, China and Argentina. It has recently been found in the Mediterranean region (Iberian Chain, northeastern Spain). In this paper we refer the finding of Tonkinella aff. breviceps in the Leonian (lower Middle Cambrian) of the Cantabrian Mountains (northern Spain), analysing its stratigraphical position, fossil assemblages, biochronology and utility for intercontinental correlation. The presence of this taxon allows us to make a more accurate correlation between the Middle Cambrian biochronological scales of Laurentia, the Mediterranean area and China

    Estratigrafía y petrología del subsuelo recuaternario del sector sw de la depresión de Barcelona (cadenas costeras catalanas, ne de Iberia)

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    [email protected] numerosas obras de Ingeniería Civil que se han realizado en los últimos años en la depresión de Barcelona (ampliación del aeropuerto, ampliación del metro y AVE fundamentalmente) han permitido recabar mucha información sobre el subsuelo de esta área. En este trabajo se caracterizan las distintas unidades de subsuelo precuaternarias que aparecen en los numerosos sondeos realizados recientemente en la zona SW de la depresión de Barcelona. Se ha identificado un sustrato triásico formado por areniscas del Buntsandstein y dos unidades de edad Miocena, una basal de carácter continental y otra superior depositada en un ambiente marino. Todas estas unidades fueron fracturadas debido a una tectónica extensiva y, posteriormente, fueron fosilizadas en primer lugar por los sedimentos del Plioceno, que recubren la superficie de erosión messiniense, y finalmente, por el Cuaternario. El análisis de las distintas unidades permite obtener datos sobre la evolución paleogeográfica y tectónica de la depresión de Barcelona durante el Mioceno y el Plioceno.Current building of civil Engineering infrastructures in the Barcelona plain and Llobregat delta (mainly metro and airport extension and high speed train) is providing new geological subsurface data to build better geologic models and understand the basin evolution. This work focuses on the pre-Quaternary units observed in cores. Based on petrographic analyses combined when it was possible with paleontological studies, we identified the lower Triassic Buntsandstein sandstone facies and Miocene continental and marine facies which appear compartmentalized due to extensive deformation. After this extensive episode, Pliocene and Quaternary sediments, which were deposited after the development of successive erosive surfaces, overlay the Triassic and Miocene units. The identification of these units enabled one to improve the interpretation of the tectonic and paleogeographic evolution of the Barcelona plain

    Volcanic sequence in Late Triassic – Jurassicsiliciclastic and evaporitic rocks from Galeana, NE Mexico

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    In northeastern Mexico, volcanic rocks interbedded with Late Triassic–Jurassic siliciclastic and evaporitic strata have been linked to magmatic arcs developed in the Pangea western margin during its initial phase of fragmentation. This work provides new petrographic and geochemical data for volcanism included in the El Alamar and Minas Viejas formations outcropping in the Galeana region. Andesitic dykes and sills (n= 10) in the El Alamar redbeds show SiO2= 47.5–59.1% and MgO= 1.2–4.2%, as well as a geochemical affinity to island arc magmas. This work represents the first report of this tectonic setting in the region. Geological and petrographic evidence suggest that this arc system likely developed after ~220 and before ~193Ma. Trachy-andesitic and rhyodacitic domes (n= 20) associated with the Minas Viejas gypsum-carbonates sequence show SiO2= 61.8–82.7% and MgO= 0.1–4.0% with a tectonic affinity to continental arc. A rhyodacite sample from this region has been dated by U-Pb in zircon, yielding an age of 149.4 ± 1.2Ma (n= 21), being the youngest age related to this arc. Finally, we propose a threestep model to explain the tectonic evolution from Late Triassic island arc to Jurassic continental arc system in the northeastern Mexico

    V-shaped pyranylidene/triphenylamine-based chromophores with enhanced photophysical, electrochemical and nonlinear optical properties

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    We report the synthesis and comprehensive study of two chromophores based on 4H-pyranylidene moiety as a part of the p-conjugated spacer. Triphenylamine (TPA) acts as donor and tricarbonitrile-based electron-accepting groups complete these V-shaped D-A-D architectures (A, acceptor; D, donor). Their electrochemical, photophysical and nonlinear optical properties are analyzed in detail by using a joint experimental and theoretical approach. The two chromophores exhibit near-infrared fluorescence, large Stokes shift, enhanced emission in tetrahydrofuran/water mixtures and good photostability. Additionally, the dimerization of triphenylamine groups to tetraphenylbenzidine (TPB) takes place upon electrochemical and chemical oxidation showing their peculiar electrochemical behavior and film formation capabilities. Interestingly, high molecular first hyperpolarizabilities and two-photon absorption cross-sections were found, highlighting their potential applications in electro-optical devices. Overall, our work demonstrates that these near-infrared (NIR) fluorescent chromophores are versatile materials with a myriad of applications ranging from optoelectronics to biological applications. © 2021 The Royal Society of Chemistry
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