Evolucion paleoambiental desde el Holoceno temprano hasta la actualidad del marjal de Almenara (Mediterráneo occidental)

The main aim of this study is to characterize the different stages in the palaeoenvironmental evolution of the Almenara marsh, Spain, from the early Holocene to the present day. This marsh is one of the most important in Castellón province. Five cores extracted from the marsh underwent sedimentological analysis, micropalaeontological study (foraminifera, ostracods and gastropods) and 14C dating. The results show that before the maximum transgression of the Mediterranean during the Marine Isotope Stage 1 (5500 cal yr. BP dating in the Almenara marsh), the area was occupied by a brackish marsh (prior to the 8.2 ka event). During the middle Holocene, the regional sea level rise and later stability caused an oligohaline/freshwater marsh with fluctuating water levels to form. This marsh occupied the entire area of today’s Almenara marsh at least between 7570 and 2780 cal yr BP. The results may indicate a phase of greater contribution of groundwater inputs (and rainfall/riverine discharge) during the middle Holocene as a response to a climatic phase characterized by higher humidity. Today, the marsh is filled with sediments from natural and anthropic processes related to the agricultural activity carried out throughout the area (except for the central part, which has been reclaimed as wetland). The water of the present-day marsh (like that prior to 8.2 ka event) is brackish, as is indicated by the benthic foraminiferal assemblage; this contrasts with the earlier oligohaline/freshwater marsh determined in the survey cores during the middle Holocene until the time of the Iberian culture.El principal objetivo de este trabajo es la caracterización de los diferentes estadios en la evolución paleoambiental del marjal de Almenara (España) desde el Holoceno temprano hasta la actualidad. Este espacio húmedo es uno de los más importantes de la provincia de Castellón. Se han estudiado cinco testigos sedimentarios que han sido analizados desde el punto de vista sedimentológico, micropaleontológico (especialmente foraminíferos) y cronológico (14C). Los resultados muestran que antes del máximo de la transgresión en el Mediterráneo del Estadio Isotópico 1 (5500 cal yr. BP datado en el marjal de Almenara), el área estaba ocupada por una marjal salobre (antes del evento frío y seco del 8.2 ka). Tras la desecación de este ambiente (en el episodio 8.2 ka), durante el Holoceno medio, el incremento del nivel del mar y su posterior estabilidad determinó la instalación de un marjal oligohalino y/o dulceacuícola, en el cual se constatan fluctuaciones del nivel del agua. Este ambiente ocupó el área de estudio al menos entre 7570 and 2780 cal yr BP. Los resultados indican una contribución más importante del acuífero (de la lluvia y de la escorrentía superficial) durante el Holoceno tardío, que contrarrestó el ascenso eustático, como respuesta a una fase climática mucho más húmeda que la actual. Hoy, el marjal está colmatado por sedimentos procedentes de procesos naturales y antropogénicos, vinculados a las actividades agrícolas que se desarrollan desde hace siglos, excepto en la parte central que ha sido recuperada como zona húmeda. El marjal actual es salobre (igual que el registrado antes del episodio 8.2 ka), como corroboran las asociaciones de foraminíferos bentónicos, lo cual contrasta con las asociaciones fósiles que revelan un paleoambiente oligohalino y/o dulceacuícola durante el Holoceno medio hasta la época de la cultura ibérica

Synthesis and complementary self-association of novel lipophilic π-conjugated nucleoside oligomers

The following article appeared in Organic and Biomolecular Chemistry 13.15 (2015): 4506-4513 and may be found at http://dx.doi.org/10.1039/c5ob00098j, reproduced by permission of The Royal Society of ChemistryA series of lipophilic nucleosides comprising natural and non-natural bases that are π-conjugated to a short oligophenylene-ethynylene fragment has been synthesized. These bases comprise guanosine, isoguanosine, and 2-aminoadenosine as purine heterocycles, and cytidine, isocytosine and uridine as complementary pyrimidine bases. The hydrogen-bonding dimerization and association processes between complementary bases were also studied by 1H NMR and absorption spectroscopy in order to obtain the relevant association constantsFunding from the European Research Council (ERC-StG 279548) and MINECO (CTQ2011-23659) is gratefully acknowledge

Isotope Labelling for Reaction Mechanism Analysis in DBD Plasma Processes

Dielectric barrier discharge (DBD) plasmas and plasma catalysis are becoming an alternative procedure to activate various gas phase reactions. A low-temperature and normal operating pressure are the main advantages of these processes, but a limited energy efficiency and little selectivity control hinder their practical implementation. In this work, we propose the use of isotope labelling to retrieve information about the intermediate reactions that may intervene during the DBD processes contributing to a decrease in their energy efficiency. The results are shown for the wet reforming reaction of methane, using D2O instead of H2O as reactant, and for the ammonia synthesis, using NH3/D2/N2 mixtures. In the two cases, it was found that a significant amount of outlet gas molecules, either reactants or products, have deuterium in their structure (e.g., HD for hydrogen, CDxHy for methane, or NDxHy for ammonia). From the analysis of the evolution of the labelled molecules as a function of power, useful information has been obtained about the exchange events of H by D atoms (or vice versa) between the plasma intermediate species. An evaluation of the number of these events revealed a significant progression with the plasma power, a tendency that is recognized to be detrimental for the energy efficiency of reactant to product transformation. The labelling technique is proposed as a useful approach for the analysis of plasma reaction mechanisms

Fate and effects of uncoated ZnO nanoparticles on nine crops exposed in two agricultural soils, a calcareous and an acidic soil.

The nanotechnology has a wide range of applications including those that deliberately release nanoparticles (NPs) into the environment. The use of nanoformulations containing agrochemicals to soils provides an efficient way to apply pesticides and fertilizers in a controlled mode. The zinc oxide nanoparticles (ZnO NPs) are of particular interest due to their increasing incorporation into agricultural products

Estudio del efecto de ceras reductoras de la viscosidad en un betún modificado con caucho

[Resumen:] Debido a una creciente preocupación sobre el calentamiento global, la industria de las mezclas bituminosas está haciendo un constante esfuerzo para lograr disminuir sus emisiones mediante la reducción de las temperaturas de fabricación y puesta en obra sin que se vean comprometidas las propiedades mecánicas de las mezclas bituminosas. El uso de mezclas con caucho de neumáticos ha logrado demostrar que estas mezclas pueden ser económicas, ecológicas y que mejoran el comportamiento de los pavimentos. Sin embargo, las mezclas con betunes de alto contenido en caucho presentan un inconveniente: su fabricación exige mayores temperaturas de mezclado y puesta en obra debido a la elevada viscosidad causada por la presencia masiva de caucho, siendo la emisión de gases de efecto invernadero mayor que la de las mezclas bituminosas convencionales. Este artículo presenta un estudio realizado sobre el efecto de cuatro aditivos reductores de la viscosidad de naturaleza orgánica añadidos a un betún modificado con un 15% de caucho. Los resultados del estudio indican que los aditivos logran disminuir la viscosidad, aumentar la temperatura de reblandecimiento y disminuir la penetración. Sin embargo, no tienen un claro efecto en el ensayo de recuperación elástica y de ductilidad a 25ºC.[Resumo:] Devido a uma crescente preocupação com o aquecimento global, a indústria betuminoso está fazendo um esforço constante para atingir emissões mais baixas, reduzindo a temperatura de fabricação e aplicação sem propriedades mecânicas comprometidas de misturas betuminosas . O uso de misturas de borracha de pneus não foi capaz de mostrar que essas misturas podem ser econômicos, ecológicos e melhorar o comportamento do pavimento. No entanto, as misturas de betume com elevado teor de borracha presente uma desvantagem: o seu fabrico requer altas temperaturas de mistura e de aplicação, devido à elevada viscosidade, causada pela presença de massa de borracha, com a emissão de gases com efeito de estufa do que o maior que a mistura de asfalto convencional. Este trabalho apresenta um estudo sobre o efeito de quatro redutor da viscosidade dos aditivos orgânicos adicionados a um betume modificado com 15% de borracha. Os resultados indicam que os aditivos são capazes de reduzir a viscosidade, aumentar a temperatura de amolecimento e reduzir a penetração. No entanto, eles têm um efeito claro no teste de recuperação elástica e a ductilidade a 25° C

Substrate-induced enhancement of the chemical reactivity in metal-supported graphene

Graphene is commonly regarded as an inert material. However, it is well known that the presence of defects or substitutional hetero-atoms confers graphene promising catalytic properties. In this work, we use first-principles calculations to show that it is also possible to enhance the chemical reactivity of a graphene layer by simply growing it on an appropriate substrate. Our comprehensive study demonstrates that, in strongly interacting substrates like Rh(111), graphene adopts highly rippled structures that exhibit areas with distinctive chemical behaviors. According to the local coupling with the substrate, we find areas with markedly different adsorption, dissociation and diffusion pathways for both molecular and atomic oxygen, including a significant change in the nature of the adsorbed molecular and dissociated states, and a dramatic reduction (∼60%) of the O2dissociation energy barrier with respect to free-standing graphene. Our results show that the graphene-metal interaction represents an additional and powerful handle to tailor the graphene chemical properties with potential applications to nano patterning, graphene functionalization and sensing devicesWe thank the financial support from the Spanish MINECO (projects MAT2014-54484-P, MDM-2014-0377, MAT2016-77852-C2-2-R (AEI/FEDER, UE) and MAT2017-83273-R (AEI/FEDER,UE)). Computer time provided by the Spanish Supercomputer Network (RES) at the Magerit (CesViMa, Madrid) and Altamira (IFCA, Santander) supercomputers. CRM is grateful to the FPI-UAM graduate scholarship program and to Fundación Universia for financial suppor

Nucleoside diphosphate kinase A (NM23-H1) as a potential biomarker candidate for colorectal cancer

Comunicaciones a congreso

Introducing the Catalytic Amination of Silanes via Nitrene Insertion

The direct functionalization of Si−H bonds by the nitrene insertion methodology is described. A copper(I) complex bearing a trispyrazolylborate ligand catalyzes the transfer of a nitrene group from PhINTs to the Si−H bond of silanes, disilanes, and siloxanes, leading to the exclusive formation of Si−NH moieties in the first example of this transformation. The process tolerates other functionalities in the substrate such as several C−H bonds and alkyne and alkene moieties directly bonded to the silicon center. Density functional theory (DFT) calculations provide a mechanistic interpretation consisting of a Si−H homolytic cleavage and subsequent rebound to the Si-centered radical.We thank the Ministerio de Ciencia e Innovación for Grants PID2020-113797RB-C21, PID2020-112825RB-I00, and CEX2019-000925-S as well as FEDER for “Una manera de hacer Europa” funding. We also thank Junta de Andalucía (P20-00348) and Universidad de Huelva (P.O.Feder UHU202016). A.M.R. and R.P.-S. thank Ministerio de Universidades for the FPU fellowships (FPU17/02738 and FPU18/ 01138, respectively), and J.P.-R. thanks Fondo de Garantía Juvenil for a research contract. CERCA Programme/Generalitat de Catalunya is also acknowledged. We thank Prof. T. R. Belderrain for helpful discussions on 29Si NMR spectroscopy. Funding for open access charge: Universidad de Huelva / CBU

High-fidelity noncovalent synthesis of hydrogen-bonded macrocyclic assemblies

This is the accepted version of the following article: Angewandte Chemie International Edition 54.23 (2015): 6780-6784, which has been published in final form at http://dx.doi.org/10.1002/anie.201501321A hydrogen-bonded cyclic tetramer is assembled with remarkably high effective molarities from a properly designed dinucleoside monomer. This self-assembled species exhibits an impressive thermodynamic and kinetic stability and is formed with high fidelities within a broad concentration rangeFunding from MINECO (CTQ2011-23659) and the E.U. (ERC-Starting Grant 279548) is gratefully acknowledge