Preparation and characterization of polyester resin-layered silicate containing reactive groups

Polymer nanocomposites, specifically nanoclay-reinforced polymers, have attracted great interest as matrix materials for high temperature composite applications. Nanocomposites require relatively low dispersant loads to achieve significant property enhancements. These enhancements are mainly a consequence of the interfacial effects that result from dispersing the silicate nanolayers in the polymer matrix and the high in-plane strength, stiffness and aspect ratio of the lamellar nanoparticles. The montmorillonite (MMT) clay, modified with organic onium ions with long alkyl chains as Cloisites, has been widely used to obtain nanocomposites. The presence of reactive groups in organic onium ions can form chemical bonds with the polymer matrix which favours a very high exfoliation degree of the clay platelets in the nanocomposite (1,2

Assessment of predation risk through conspecific cues by anuran larvae

Accurate assessment of predation risk is critical for prey survival during predator–prey interactions. Prey can assess predation risk by the presence of cues dropped by predators themselves, but they can also gather information about risk level through cues released by other prey, avoiding the hazard of being in close proximity to predators. In this study, we examine the ability of anuran larvae (Pelobates cultripes) to detect predation risk indirectly when they are in contact with conspecifics that have been recently exposed to chemical stimuli from natural predators (larvae of aquatic beetles). In a first experiment, we confirmed that larvae exposed to predator cues exhibited innate defensive behavior, indicating that they perceived the risk of predation and, thus, could potentially act as risk indicators for naïve conspecifics. In a second experiment, we observed that unexposed larvae paired with a startled conspecific adjusted their antipredator behavior, presumably by mirroring conspecifics’ behavior and/or using chemical cues from their partners as a risk information source. This cognitive ability of tadpoles to assess predation risk through conspecific cues might play an important role in their interaction with predators, facilitating the early detection of potential threats to elicit appropriate antipredator responses and increase the chances of survivalFinancial support was provided by the Spanish Ministry of Science and Innovation (MICINN), under Grant CGL2015-68670-

Influence of the epoxy/amine stoichiometry on the thermomechanical properties of nanocomposites based on high Tg epoxy and organophilic clays.

In layered silicate-epoxy nanocomposites organic modification of the silicates makes them compatible with the epoxy which intercalates into the clay galleries. The effect of clay dispersion on epoxies of high Tg is not clear. Decreases of the epoxy Tg have been frequently reported. The presence of clay may cause stoichiometry imbalances that conduces to the formation of imperfect network

El papel funcional de las larvas de anfibios en los ecosistemas acuáticos temporales

Programa de Doctorado en Estudios MedioambientalesThe structure and dynamics of ecological communities is determined and regulated by several key processes that influence in the species distribution and abundance (e.g., selection, drift, speciation, and dispersal), and by ecological interactions as competition and predation. The relative importance of competition and predation will depend largely on the local assemblage of species, the type of predators, or the degree of niche segregation. Amphibians constitute an ideal system to address these questions, as they are key species in the trophic webs with a profound role in several ecological processes. Moreover, the effect of amphibian larvae in the aquatic systems and their trophic niche largely depend on their complex ecological interactions with competitors and predators, as they respond to them altering their morphology and behavior. As amphibians continue showing generalized dramatic and global population declines, it is essential to fully characterize the functional role of amphibians in the natural systems to understand the possible consequences of their local declines and extinction. The main objective of this thesis is to know the regulatory potential of amphibian larvae according to the environmental conditions, focusing on the research about their role over other trophic levels, and their interactions with the aquatic vegetation, comparing their effects in Mediterranean and Neotropical systems. By means of experiments with mesocosms, which simulate the environmental conditions in controlled conditions, I evaluated the effect of a guild of amphibian larvae from Doñana National Park on several biological and physicochemical parameters of the system. We detected an important effect of amphibian larvae on these parameters, mostly when at high larval density, causing a marked reduction of plants biomass, increasing water turbidity and several nutrients like the ammonia. Amphibian larvae also affected algae abundance, indirectly inferred by estimating chlorophyll concentration in the water, and they reduced zooplankton diversity. However, these changes were not produced as a consequence of all amphibian species, but they were caused mainly to the larvae of the western spadefoot toad (Pelobates cultripes). The larvae of this species are disproportionally larger than the other amphibian larvae of the area, and they consume a large amount of macrophyte biomass. This species by itself altered the zooplankton composition, as the presence of tadpoles of P. cultripes increased the relative proportion of copepods in respect to cladocerans. Urodeles (newts and salamanders) can also contribute to this bias in the zooplankton community, as they are efficient carnivorous that can considerably alter the zooplankton community composition. Apart from density, we also experimentally manipulated the presence of native and invasive predators, which were introduced either freely roaming or caged in the mesocosms to distinguish their non-consumptive predator effects. The direct consumptive effects of the invasive predator, the red swamp crayfish, were very harmful in the great survival reduction of amphibians as well as in the physicochemical characteristics of the system (e.g., marked increase in water turbidity and nutrients, pronounced reduction of the plants biomass). Using stable isotopes, we evaluated the trophic plasticity of the amphibian larvae community derived of the changes in the environmental conditions detected in the former experiment. We observed variations in the stable isotopic values for carbon (¿13C) and nitrogen (¿15N) among species and according to the treatments the amphibians were exposed to. High larval density, presence of P. cultripes and presence of red swamp crayfish produced a decrease in the ¿13C of amphibians, related to an increase in carbon-depleted resources in their diet such as detritus or zooplankton. Therefore, the opportunistic feeding of amphibians is widely conditioned by competition, whereas the indirect predator effects are negligible in this temperate system. However, in neotropical systems predators have a greater structuring role in the amphibian community, altering the relative trophic position of the different studied species in central Panama, and changing their growth rate and survival. Furthermore, the community composition also has a great effect in the trophic niche of the amphibian larvae as we distinguished changed in the ¿15N of some of the amphibian species. Since our results bring to light that anuran larvae of temporary aquatic systems are important primary consumers, and not only of phytoplankton or periphyton but also of aquatic macrophytes, this thesis also try to figure out the feeding preferences of different amphibian larvae regarding several species of macrophytes and charophytes. The western spadefoot toad is the greatest macrophyte consumer, showing special preference for those from the genus Callitriche. Herbivory by amphibian larvae can have an important role in these ecosystems, affecting the community composition of plants, their reproductive phenology or their seed dispersal. In fact, the role of amphibian larvae in the direct or indirect ¿through seed predators- seed dispersal of aquatic plants has been ignored until the present study, and therefore our data are the first observations concerning this. Apart from the seeds directly ingested from the plants, tadpoles can also consume the seeds buried in the seed bank while feeding on detritus, as it is a common resource for tadpoles. We observed that between 9 and 32% of the tadpoles, depending on the species, transported seeds or spores from the pond vegetation. Among them, P. cultripes was the species with greatest number of seeds. The preferred plant in the feeding experiment (Callitriche) was also the one from which we found in greatest number in the tadpole feces, whose germination rate was between 40 and 88% depending on the tadpole species. The results of this thesis reveal the important role of amphibian larvae on the complex community structure of aquatic systems. Thus, it is essential to widen our knowledge in respect to their functional role aiming to anticipate and understand the consequences of their pronounced and predictable population declines.Universidad Pablo de Olavide. Departamento de Sistemas Físicos, Químicos y Naturale

Propiedades de nanocompuestos de matriz termoestable con nuevos organosilicatos laminares

En este trabajo se han preparado nanocompuestos de matriz polímero termoestable del tipo poliéster insaturado y epoxídica utilizando como refuerzo nanosilicatos laminares que se han modificado específicamente para mejorar la interacción con la matriz. En concreto se han modificado montmorillonitas con cationes orgánicos reactivos con la matriz de poliéster insaturado. Asimismo se han silanizado montmorillonitas comerciales orgánicamente modificadas con el objetivo de formar enlaces químicos con la matriz epoxídica. En ambos nanocompuestos se han estudiado las propiedades termo- mecánicas pudiendo comprobar la efectividad de los nuevos organosilicatos

Molecular characterization of autophagic and apoptotic signaling induced by sorafenib in liver cancer cells

Sorafenib is the unique accepted molecular targeted drug for the treatment of patients in advanced stage of hepatocellular carcinoma. The current study evaluated cell signaling regulation of endoplasmic reticulum (ER) stress, c-Jun-N-terminal kinase (JNK), Akt, and 5′AMP-activated protein kinase (AMPK) leading to autophagy and apoptosis induced by sorafenib. Sorafenib induced early (3–12 hr) ER stress characterized by an increase of Ser51P-eIF2α/eIF2α, C/EBP homologous protein (CHOP), IRE1α, and sXBP1, but a decrease of activating transcription factor 6 expression, overall temporally associated with the increase of Thr183,Tyr185P-JNK1/2/JNK1/2, Thr172P-AMPKα, Ser413P-Foxo3a, Thr308P-AKt/AKt and Thr32P-Foxo3a/Foxo3a ratios, and reduction of Ser2481P-mammalian target of rapamycin (mTOR)/mTOR and protein translation. This pattern was related to a transient increase of tBid, Bim EL, Beclin-1, Bcl-xL, Bcl-2, autophagy markers, and reduction of myeloid cell leukemia-1 (Mcl-1) expression. The progressive increase of CHOP expression, and reduction of Thr308P-AKt/AKt and Ser473P-AKt/AKt ratios were associated with the reduction of autophagic flux and an additional upregulation of Bim EL expression and caspase-3 activity (24 hr). Small interfering-RNA (si-RNA) assays showed that Bim, but not Bak and Bax, was involved in the induction of caspase-3 in sorafenib-treated HepG2 cells. Sorafenib increased autophagic and apoptotic markers in tumor-derived xenograft model. In conclusion, the early sorafenib-induced ER stress and regulation of JNK and AMPK-dependent signaling were related to the induction of survival autophagic process. The sustained drug treatment induced a progressive increase of ER stress and PERK-CHOP-dependent rise of Bim EL, which was associated with the shift from autophagy to apoptosis. The kinetic of Bim EL expression profile might also be related to the tight balance between AKt- and AMPK-related signaling leading to Foxo3a-dependent BIM EL upregulation.Ministerio de Economía y Competitividad BFU2016‐75352‐PInstituto de Salud Carlos III PI15/00034, PI13/ 00021, PI16/00090, PI14/01349Ministerio de Educación FPU16/05127, FPU12/01433, FPU13/01237Junta de Andalucía CTS-6264, PI-00025-2013, PI-0127-2013, PI-0198-201

Factores que controlan la sedimentación en el humedal costero de Almenara: análisis geoquímico y estratigráfico.

La utilización conjunta de análisis sedimentológico, secuencias y geoquímico apolicado a depósitos de lagunas costeras (marjales) es una herramienta potente para el análisis de las variaciones del nivel del mar y costeros (playas, deltas). La aplicación de dicha metodología en los depósitos del Marjall de Almenara (Castellón) permite identificar, a partir del análisis de facies y selcuencial, las variaciones en la lámina del agua del humedal mientras que el análisis de los datos geoquímicos permite relacionar dichas fluctuaciones con episodios de mayor o menor intrusión sallina que pueden relacionarse con variaciones observados con los de otras áreas del Mediterráneo español

Giant calcite concretions in aeolian dune sandstones; sedimentological and architectural controls on diagenetic heterogeneity, mid-Cretaceous Iberian Desert System, Spain

Aeolian dune sandstones of the Iberian erg system (Cretaceous, Spain) host giant calcite concretions that constitute heterogeneities of diagenetic origin within a potential aeolian reservoir. The giant calcite concretions developed in large-scale aeolian dune foresets, at the transition between aeolian dune toeset and damp interdune elements, and in medium-scale superimposed aeolian dune sets. The chemical composition of the giant concretions is very homogeneous. They formed during early burial by lowMg-calcite precipitation frommeteoric pore waters. Carbonate componentswith yellow/orange luminescence form the nuclei of the poikilotopic calcite cement. These cements postdate earlier diagenetic features, characterized by earlymechanical compaction, Fe-oxide cements and clay rims around windblown quartz grains resulting from the redistribution of aeolian dust over the grain surfaces. The intergranular volume (IGV) in friable aeolian sandstone ranges from 7.3 to 15.3%, whereas in cemented aeolian sandstone it is 18.6 to 25.3%. The giant-calcite concretions developed during early diagenesis under the influence of meteoric waters associated with the groundwater flow of the desert basin, although local (e.g. activity of fluid flow through extensional faults) and/or other regional controls (e.g. variations of the phreatic level associated with a variable water influx to the erg system and varying sea level) could have favoured the local development of giant-calcite concretions. The spatial distribution pattern of carbonate grains and the main bounding surfaces determined the spatial distribution of the concretions. In particular, the geometry of the giant calcite concretions is closely associated with main bounding aeolian surfaces. Thus, interdune, superimposition and reactivation surfaces exerted a control on the concretion geometries ranging fromflat and tabular ones (e.g. bounded by interdunes) towedge-shaped concretions at the dune foresets (e.g. bounded by superimposition and reactivation surfaces) determining the spatial distribution of the heterogeneities of diagenetic origin in the aeolian reservoir

Evaluación de factores cognitivos positivos y negativos relacionadas con el trastorno de pánico: Validación del CATP

The aim of the study was to examine the factor structure and psychometric properties of the Abbreviated Panic Disorder Questionnaire(CATP) and, in addition, the Panic Disorder Severity Scale–Self Report (PDSS-SR), in a sample of patients with a principal diagnosis of panic disorder (PD). The CATP comprises three separate short scales designed to assess cognitive constructs related to PD, being the Panic Catastrophic Misinterpretations Scale (PCMS), the Panic Self-efficacy Scale (PSES) and the Panic Severity Scale (PSS). Exploratory factor analyses showed a three-factor structure of the PCMS consistent with the three hypothesized dimensions of catastrophic misinterpretations, i.e., physical, mental and social. We also found a strong unidimensional structure for the remaining scales (PSES, PSS and PDSS). Data on reliability (internal consistency) and validity (convergent and discriminant) show that the scales have sound psychometric properties and could be useful instruments to assess positive and negative constructs related to PD.El objetivo del estudio fue investigar la estructura factorial y las propiedades psicométricas del Cuestionario Abreviado del Trastorno de Pánico (CATP) y, adicionalmente, de la Panic Disorder Severity Scale–Self Report (PDSS-SR), en una muestra de pacientes con diagnóstico principal de trastorno de pánico (TP). El CATP incluye tres escalas breves diseñadas para evaluar constructos cognitivos relacionados con el TP, i.e., Escala de Interpretaciones Catastrofistas al Pánico (EICP), Escala de Autoeficacia ante el Pánico (EAP) y Escala de Gravedad del Pánico (EGP). Los análisis factoriales exploratorios indicaron una estructura trifactorial de la escala EICP consistente con las tres dimensiones de interpretaciones catastrofistas (física, mental y social). Las restantes escalas (EAP, EGP y PDSS-SR) exhibieron una robusta estructura unidimensional. Los datos sobre fiabilidad (estructura interna) y validez (convergente y discriminante) muestran que las escalas poseen excelentes propiedades psicométricas y pueden resultar de utilidad para la evaluación de constructos positivos y negativos del TP