Analysis of the cell cycle of neural progenitors in the developing ferret neocortex

Description of the cell cycle features of neural progenitors during late stages of neurogenesis in a gyrencephalic mammal, the ferret

Lime mortar-compacted bentonite-magnetite interfaces: An experimental study focused on the understanding of the EBS long-term performance for high-level nuclear waste isolation DGR concept

The aim of this study was to obtain evidences regarding the physical and geochemical processes occurring as a result of the combined effects of cementitious materials from the concrete degradation and magnetite from steel corrosion on the bentonite barrier during disposal of high-level radioactive waste.A series of six experiments were done that attempt to reproduce the repository conditions prevailing from 1000 to 3000 years after emplacement of wastes. A lime mortar was used as the source of calcium and alkalinity as this is the presumed reactive product produced during concrete degradation at long-term. Magnetite powder was used to simulate the final corrosion product of cast iron and C-steel under anaerobic conditions. Either a natural FEBEX bentonite or a pretreated "aged" sample, depleted in exchangeable Mg and enriched in K, were used as the swelling clay component. Experiments, with both types of bentonite, were performed simultaneously in cylindrical specimens (50 mm diameter, 25 mm length), confined in a Teflon® sleeve/steel case cells. These specimens were composed of cement mortar in contact with compacted bentonite, which was in turn in contact with compressed magnetite powder. They were hydrated with an artificial Na+-Ca2+×SO42-type Spanish reference clayey formation water for 18 months at 60 °C and constant hydraulic pressure applied through the base of the mortar.After dismantling and sampling the specimens, distribution of soluble ions, exchangeable cations and mineralogy were studied in the bentonite by different instrumental techniques. Iron migration or any impact of the corrosion products in the bentonite was not noticeable in the clay. Both, mortar and magnetite acted as sinks of chloride and sulfate. Small quantities of Ca-Al-sulfates and carboaluminates, which can allocate chlorides, were determined near the mortar-bentonite interface. Portlandite dissolved near the bentonite interface and induced the formation of calcium silicates hydrates (C-S-H) phases cementing the clay interface characterizing a calcium front that was developed from the mortar towards the bentonite. Magnesium silicate hydrates (M-S-H) phases were also concentrated at the interface with mortar in the natural bentonite. It was also determined that natural bentonite has potentially higher buffering capacity attenuating the calcium alkaline front than the pretreated clay. In both cases, a low porosity bentonite-mortar zone was experimentally created at the interface. This type of material should be carefully studied in order to predict the potential for further development of a diffusive alkaline alteration, the radionuclides retention and the consequences in the hydration rate of the unaffected bentonite bufferThe research leading to these results has received funding from the European Atomic Energy Community's Seventh Framework Program (FP7/2007–2011) under grant agreement no. 249681

Bentonite powder XRD quantitative analysis using Rietveld refinement: Revisiting and updating bulk semiquantitative mineralogical compositions

Bentonite is a claystone formed by a complex mineralogical mixture, composed of mont-morillonite, illite, and accessory minerals like quartz, cristobalite, feldspars, carbonates, and minor amounts of iron oxy-hydroxides. Bentonite presents complexity at various scales: (1): a single mineral may present different chemical composition within the same quarry (e.g., feldspars solid solu-tions); (2): montmorillonite presents variability in the cation-exchange distribution while illite may be presented as mixed-layer with smectite sheets; and (3): hardness and crystal size are larger in accessory minerals than in clay minerals, preventing uniform grinding of bentonite. The FEBEX bentonite used is originally from Almería (Spain), and it is a predominantly calcium, magnesium, and sodium bentonite. This Spanish FEBEX bentonite has been hydrothermally altered at laboratory scale for 7–14 years. A thermal gradient was generated by heating a disk of pressed iron powder, simulating the metal waste canister, in contact with the compacted bentonite sample. Hydration was forced from the opposite direction. XRD recorded patterns were very similar. In order to min-imize the bias of XRD semi-quantitative determination methods, Rietveld refinement was per-formed using BGMN software and different structural models. Confidence in the quantification of the main phases allows us to convincingly detect other subtle changes such as the presence of calcite in the hydration front, right at the interface between the saturated and unsaturated bentonite, or the presence of goethite, and not hematite, in the saturated bentonite, near the source of hydration. Smectite component was 72 ± 3% and the refinement was consistent with the presence of ~10% illite, comparable with previous characterization

Heterogeneous subsidence and paleogeographic elements in an extensional setting revealed through the correlation of a storm deposit unit (Aptian, E Spain)

Durante el Aptiense, en la Subcuenca de Las Parras (NW Cuenca del Maestrazgo) se depositó una unidad siliciclástica en un contexto tectónico extensional. Esta unidad se ha dividido en cuatro secuencias granocrecientes, de las cuales se analiza en detalle la tercera (S3) ya que presenta un alto potencial de correlación lateral. El análisis sedimentológico de la secuencia S3 ha permitido interpretar una evolución vertical de shoreface inferior con procesos de tormenta, a shoreface superior; también ha permitido correlacionar esta secuencia entre dos sectores de la subcuenca que presentan un desarrollo litológico considerablemente diferente. El techo de la secuencia S3 es una superfi cie erosiva menor con valor cronoestratigráfi co y se ha utilizado como datum de correlación para el análisis de la unidad siliciclástica. Las variaciones laterales de facies de la secuencia S3 permiten interpretar la proximidad de un sistema de descarga siliciclástico hacia el sureste, y se propone una zona de intersección de fallas normales, próxima al sector suroriental de la zona estudiada, como un elemento paleoestructural favorable para la entrada de un sistema de drenaje en la cuenca. En el sector suroriental, por encima del datum de correlación, la secuencia S4 presenta un desarrollo muy reducido debido a la ausencia de su parte inferior; esto ha permitido interpretar la presencia de una discontinuidad local intra-S4. Esta discontinuidad local se correlaciona con otra reconocida en el sector noroccidental. Debido a las diferencias de espesor y al grado de desarrollo de la discontinuidad intra-S4 se deduce que la historia de subsidencia de diferentes bloques de la cuenca no es exactamente la misma. Esta discontinuidad intra-S4 podría tener interés regional ya que separa sedimentos dominantemente siliciclásticos de sedimentos carbonatados y podría indicar una modifi cación importante del sistema sedimentario. Para uno de los bloques estudiados, las variaciones espaciales de espesor para cada secuencia podrían representar un desarrollo de la subsidencia alternando periodos con subsidencia diferencial atenuada y periodos con subsidencia diferencial acentuada, que pueden estar relacionados con la dinámica extensional

Long-term hydrological changes in northern Iberia (4.9–0.9 ky BP) from speleothem Mg/Ca ratios and cave monitoring (Ojo Guareña Karst Complex, Spain)

An absolute-dated stalagmite from Kaite Cave (Ojo Guareña Karst Complex, N Spain) provides a nearly continuous, high-resolution record of a proxy of regional precipitation patterns through the 4.9–0.9 ka BP interval. This record is based on the Mg/Ca ratio of the calcite and its variation through the stalagmite stratigraphy, which is interpreted to be primarily driven by changes in precipitation amount. The calibration of the proxy is supported by the present-day monitoring carried out in the cave for the last 10 years, which reveals a robust inverse relationship between the inter-annual/inter-decadal variability of rainfall and the Mg concentration of dripwaters and precipitating speleothems. The record of paleoprecipitation, based on 2400 Mg/Ca measurements, shows strong variability at inter-annual to inter-decadal scales, and more subtle but significant changes at secular to millennial scales. This long-term paleohydrological evolution outlines five successive intervals with consistent trends, which are bounded by abrupt shifts in the regional precipitation. These shifts took place at 4.65, 4.2, 2.6, and 1.3 ka BP. Significantly, the intervals of maximum precipitation of the whole record (around 4.9–4.65, 2.6–2.45, and 1.3–1.1 ka BP) can be related with episodes of minimum solar activity and correlated with cold climatic events elsewhere.Contribution to research projects 28 CGL2010-21499-BTE and CGL2013-43257-R of the Spanish R+D National Program 29 (MINECO) and research groups ‘‘Paleoclimatology and Global Change’’ and ‘‘Laser Induced 30 Breakdown Spectroscopy (LIBS)’’ from the UCM (Spain).Peer reviewe

Short communication: Reply to Comment by Domínguez-Villar on “Land surface temperature changes in Northern Iberia since 4000 yr BP, based in δ13C of speleothems” (Martín-Chivelet et al., 2011)

We have considered the additional data that Domínguez-Villar (this issue) has provided, as well as his criticisms of the interpretations of Martín-Chivelet et al. (2011). We argue that with or without the additional data, our original interpretations are the most likely interpretations, on the basis of Ockham's Razor. Those of Domínguez-Villar violate Ockham's Razor, and in the final analysis do not offer an alternative explanation for the Martín-Chivelet et al. (2011) and Domínguez-Villar (this issue) data. In particular, all of the 230Th ages (reported by both Martín-Chivelet et al. (2011) and Domínguez-Villar (this issue)) are in stratigraphic order, within quoted errors, so that our original chronology is robust, with no reason to invoke diagenetic processes. Given this chronology, the empirical relationship between δ13C and temperature also hold. Finally, our original mechanism for the cause of this relationship (prior calcite precipitation) has been invoked in a number of other studies to explain carbon isotopic variations and remains a perfectly plausible explanation for the observations at the studied caves

4000 years of climate change in Northern Spain from speleothem records

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu

Leaching behaviour of cement encapsulated thermally treated organic ion exchange resins

Cementation in OPC is a widely accepted method for the conditioning of Spent Ion Exchange Resins (IERs). However, the resulting waste forms tends to crack due to the induced forces by IERs swelling upon the adsorption of water. Pre-treatments, such as pyrolysis and incineration, are effective ways to minimize resin swelling issues, besides providing a significant volume reduction. In the present work, immobilization of ashes resulting from the thermal treatment of IERs was performed into three selected cement matrices of CEM I, CEM III and one-part geopolymer; the latter based on metakaolin, blast furnace slag and sodium silicate. By means of a series of batch experiments, the leaching behaviour of the waste/matrix system was assessed. Prismatic probes of 1×1×6 cm3 for each cement matrix, encapsulating 0 (reference) and 20 wt.% of the IERs ashes, were immersed in either a) deionized water, b) in situ disposal site water from El Cabril, the Spanish disposal facility for very low, low and intermediate level radioactive waste, and c) synthetic cementitious water, for reasons of leaching comparison in agreement with the ISO 6961 standard [1]. The ratio between the external surface area of the cement probes and the volume of solution was set to 0.1. All solutions were renovated every week for the first month and then every month up to 180 days. Monitoring of pH, electrical conductivity (EC) and concentrations of main and trace elements in solution were carried out. In general, no significant changes in pH were observed in the experiments performed with cementitious water as the pH was controlled by the initial pH of the solution (12.7). The pH in experiments with deionized and in situ waters increased rapidly from 7 to values in the range 10-11 (depending on the cement matrix composition) over the first week, and then stabilized into a steady range. However, the pH in samples with geopolymer decreased continuously to a range within 9.5-10 and does not seem to have reached a steady stage after 6 months. Similar trends were observed in the leaching behaviour of main cations (Ca, Na, K, Al, and Si) from the reference and IERs-containing cement probes but, as for pH, in general, steady stage was not reached. Additionally, in experiments with sampled water in El Cabril, oxidation-reduction potential was monitored and TOC in solution was measured, confirming no release of organics. Limited leaching of doping elements was observed. The joined evaluation of data may contribute to help to assess the potential of the three candidate materials a suitable conditioning matri

Desarrollo de una herramienta para la evaluación de los examen tipo test y sus aplicaciones en la mejora de la calidad y en los criterios de evaluación de estos exámenes

Depto. de Radiología, Rehabilitación y FisioterapiaFac. de MedicinaFALSEsubmitte

Modeling delta δ-18 in drip waters and recent speleothems: Implications for paleoclimate records in N Spain

Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu