Functionalised graphene sheets as effective high dielectric constant fillers

A new functionalised graphene sheet (FGS) filled poly(dimethyl)siloxane insulator nanocomposite has been developed with high dielectric constant, making it well suited for applications in flexible electronics. The dielectric permittivity increased tenfold at 10 Hz and 2 wt.% FGS, while preserving low dielectric losses and good mechanical properties. The presence of functional groups on the graphene sheet surface improved the compatibility nanofiller/polymer at the interface, reducing the polarisation process. This study demonstrates that functionalised graphene sheets are ideal nanofillers for the development of new polymer composites with high dielectric constant values

Graphene materials with different structures prepared from the same graphite by the Hummers and Brodie methods

[EN] Graphene materials containing different functional groups were prepared from a natural graphite, by means of two different oxidation methods (Hummers and Brodie). It was observed that the differences in the structure of the resultant graphite oxides (GOs) greatly affect the structure of the graphenes resulting from their thermal exfoliation/reduction. Although the oxidation of the graphite was more effective with the modified Hummers method than with Brodie’s method (C/O of 1.8 vs 2.9, as determined by XPS), the former generated a lower residual oxygen content after thermal exfoliation/reduction and a better reconstruction of the 2D graphene structure (with fewer defects). This is explained by the presence of conjugated epoxy and hydroxyl groups in the GO obtained by Brodie’s method, which upon thermal treatment, lead to the incorporation of oxygen into the carbon lattice preventing its complete restoration. Additionally, graphene materials obtained with Brodie’s method exhibit, in general, smaller sheet size and larger surface area.The authors thank MICINN and European Union (CONSOLIDER INGENIO 2010, Ref. CSD2009-00050, MAT2010-16194) for their financial support. Dr. Patricia Alvarez thanks MICINN for her Ramon y Cajal contract.Peer reviewe

Mejora de la competitividad del sector de la dorada (Sparus aurata) a través de la selección genética. PNA PROGENSA-III

Trabajo presentado en el XVI Congreso Nacional de Acuicultura, celebrado en Zaragoza (España), del 3 al 5 de octubre de 2017[EN] This project promotes technology developments for gilthead sea bream industrial sector of Spain, to facilitate and normalize the implementation of genetic selection schemes in this species, by defining new technological traits of commercial interest, with new standardized and extensible technological developments that permit, in an economical manner, normalized measuring methods, to study genetic parameters (growth,morphology, carcass and resistance disease), genotype-environment interaction to extend the Spanish production, and guarantee the production levels to the whole production chain. At the same time, improving the breeders management under industrial conditions, the validation of feeding efficiency during the selection processes and location of biomarkers linked and applied in genomic selection.[ES] Con la presente propuesta se pretende desarrollar metodología transferible al sector industrial de dorada en España que facilite y normalice la implementación de esquemas de selección genética en esta especie, mediante la definición de caracteres de interés comercial con nuevos desarrollos tecnológicos que estandaricen y hagan extensible a todo el sector, de manera económica, la medición de caracteres a escala industrial, el estudio de parámetros genéticos para caracteres de interés comercial (crecimiento, morfología, rendimiento y resistencia a enfermedades) en stocks de reproductores de la industria española, la estimación de la interacción genotipo-ambiente para permitir de manera garante la expansión de los rendimientos productivos de la industria Española, la gestión de reproductores bajo los propios condicionantes de la industria, así como la validación de la eficiencia alimenticia de los procesos de selección y búsqueda de biomarcadores asociados y aplicables en los modelos de selección.Este trabajo ha sido financiado a través de las Ayudas a la investigación de los Planes Nacionales de Acuicultura 2016 por el Ministerio de Agricultura y Pesca, Alimentación y Medioambiente (MAPAMA) y el Fondo Europeo Marítimo y de Pesca (FEMP).Peer reviewe

Conserved CDC20 Cell Cycle Functions Are Carried out by Two of the Five Isoforms in Arabidopsis thaliana

The CDC20 and Cdh1/CCS52 proteins are substrate determinants and activators of the Anaphase Promoting Complex/Cyclosome (APC/C) E3 ubiquitin ligase and as such they control the mitotic cell cycle by targeting the degradation of various cell cycle regulators. In yeasts and animals the main CDC20 function is the destruction of securin and mitotic cyclins. Plants have multiple CDC20 gene copies whose functions have not been explored yet. In Arabidopsis thaliana there are five CDC20 isoforms and here we aimed at defining their contribution to cell cycle regulation, substrate selectivity and plant development.Studying the gene structure and phylogeny of plant CDC20s, the expression of the five AtCDC20 gene copies and their interactions with the APC/C subunit APC10, the CCS52 proteins, components of the mitotic checkpoint complex (MCC) and mitotic cyclin substrates, conserved CDC20 functions could be assigned for AtCDC20.1 and AtCDC20.2. The other three intron-less genes were silent and specific for Arabidopsis. We show that AtCDC20.1 and AtCDC20.2 are components of the MCC and interact with mitotic cyclins with unexpected specificity. AtCDC20.1 and AtCDC20.2 are expressed in meristems, organ primordia and AtCDC20.1 also in pollen grains and developing seeds. Knocking down both genes simultaneously by RNAi resulted in severe delay in plant development and male sterility. In these lines, the meristem size was reduced while the cell size and ploidy levels were unaffected indicating that the lower cell number and likely slowdown of the cell cycle are the cause of reduced plant growth.The intron-containing CDC20 gene copies provide conserved and redundant functions for cell cycle progression in plants and are required for meristem maintenance, plant growth and male gametophyte formation. The Arabidopsis-specific intron-less genes are possibly "retrogenes" and have hitherto undefined functions or are pseudogenes

Deformation mechanisms in polylactic acid/natural rubber/organoclay bionanocomposites as revealed by synchrotron X-ray scattering

7 p.: gráf.The micromechanical deformation mechanisms of a polylactic acid (PLA)/natural rubber (NR) blend(PLA/NR 90/10 wt%) and its organoclay filled bionanocomposites have been investigated by small and wide angle X-ray scattering (SAXS–WAXS) under tensile conditions. The addition of NR to a PLA matrix changed the brittle fracture of PLA to a ductile deformation through the debonding of the rubber droplets. Otherwise, the formation of cavities between PLA and NR was hampered by the nanoclays since they were mainly located at the polymer blend interface. In this case, the nanoclays acted as craze nucleation sites. At 1 wt% of filler concentration, the crazes were able to fully develop in the blend and to evolve into stable microvoids, which kept growing and orienting in the tensile direction. These mechanisms also explained the progressive plastic deformation of the polymer chains and the preferential orientation of the nanoclay platelets.© Royal Society of Chemistry 2012Supported by the Spanish Ministry of Science and Innovation(MICINN) under projects MAT2010-18749, MAT2009-07789 and MAT2008-03232. JAE-Pre grant. Project FIS 2010-15502 (Direccion general de Investigación , Spain).Peer reviewe

Organobentonite as substitute of carbon black in rubber compounds

[ES] Se han preparado y caracterizado nanocomposites de caucho natural reforzados con bentonita modificada orgánicamente con una sal de amonio. Se pretende evaluar la posibilidad de utilizar estas cargas claras como sustitutos del negro de carbono en las formulaciones de caucho natural. Las curvas de vulcanización muestran que tanto la bentonita organofilizada como el negro de carbono aceleran la reacción de vulcanización y además, dan lugar a un considerable incremento en el torque. No obstante, es interesante destacar que estos efectos son más marcados en el caso de la organobentonita. Por su parte, la caracterización mecánica muestra el fuerte efecto reforzante de ambas cargas, si bien este efecto es nuevamente más acusado en presencia de la organobentonita. Es importante señalar que las propiedades mecánicas del nanocomposite reforzado con 10 partes de organobentonita son similares a las del composite con 40 partes de negro de carbono.[EN] Rubber compounds based on natural rubber reinforced with ammonium salt modified bentonite have been prepared and characterized. It pretends to evaluate the possibility of using these white fillers as substitute of carbon black in natural rubber compounds. Vulcametric curves show that the organoclay and carbon black accelerate the vulcanization reaction and, furthermore, give rise to a marked increase in the torque. However, it is of interest to point out that these effects are more marked in the case of the organoclay. In addition, the mechanical characterization show the strong reinforcing effect of both fillers, but this effect is newly more sensible when the organoclay is added to the NR. It is worthy to note that the mechanical properties of 10% organoclay-NR nanocomposite are comparable to the 40 phr carbon black filled compound.Los autores agradecen al CICYT, MAT 2001-1634 por su ayuda económica. El Dr. López Manchado agradece al Ministerio de Ciencia y Tecnología de Polímeros la concesión del contrato Ramón y Cajal.Peer reviewe