Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: catalytic aspects of in situ polymerization, crystalline features and mechanical properties

New nanocomposites based on polyethylene have been prepared by in situ polymerization of ethylene in presence of mesoporous MCM-41. The polymerization reactions were performed using a zirconocene catalyst either under homogenous conditions or supported onto mesoporous MCM-41 particles, which are synthesized and decorated post-synthesis with two silanes before polymerization in order to promote an enhanced interfacial adhesion. The existence of polyethylene chains able to crystallize within the mesoporous channels in the resulting nanocomposites is figured out from the small endothermic process, located at around 80 C, on heating calorimetric experiments, in addition to the main melting endotherm. These results indicate that polyethylene macrochains can grow up during polymerization either outside or inside the MCM-41 channels, these keeping their regular hexagonal arrangements. Mechanical response is observed to be dependent on the content in mesoporous MCM-41 and on the crystalline features of polyethylene. Accordingly, stiffness increases and deformability decreases in the nanocomposites as much as MCM-41 content is enlarged and polyethylene amount within channels is raised. Ultimate mechanical performance improves with MCM-41 incorporation without varying the final processing temperature

The effect of temperature and water stress on laboratory germination of Eucalyptus globulus Labill. seeds of different sizes

Germination rate and germination capacity of Eucalyptus globulus Labill. increased significantly with increasing temperature (13o to 33 oC) for all seed sizes to an optimum at 28 oC, then decreased. Biggest seeds generally germinated best at all temperatures. Germination was also very sensitive to water potential (0 to $-0.75$ MPa), with no germination occuring at potentials below $-0.25$ MPa.Effet de la température et du stress hydrique sur la germination en laboratoire de graines d'Eucalyptus globulus Labill de différentes tailles. On a étudié l'influence sur la germination des graines d'Eucalyptus globulus Labill de températures constantes comprises entre 13o et 33 oC et de potentiels hydriques compris entre 0 et $-0,75$ MPa. La germination était significativement influencée par la température et la taille des graines. La vitesse et le taux de germination augmentaient avec la température pour atteindre un optimum à 28 oC et ensuite diminuaient. Quand la germination était effectuée en conditions de stress on observait une diminution du taux de germination entre $-0,01$ et $-0,75$ MPa. Plus aucune graine ne germait à $-0,25$ MPa et au-delà

Drought tolerance acquisition in Eucalyptus globulus (Labill.): A research on plant morphology, physiology and proteomics

Plants perceiving drought stress activate multiple responses to synchronise developmental and molecular activities aimed at improving survival. In this study we attained a multidisciplinary approach to examine the interplay among plant morphology, physiology and proteomics for understanding the mechanisms underlying the adaptive response to drought stress. The stress-related phenotype, the differential expression of putative members of the LEA family of proteins, the seed proteomic profile, and the endogenous content of free and conjugated abscisic acid (ABA and ABAGE) were analysed in two Eucalyptus globulus provenances with contrasting drought tolerance. Differences in morphology were noticeable, drought-tolerant genotypes displaying smaller seeds with higher desiccation in the mature state and a more developed root system that was not reduced under water stress treatments. From physiological and molecular points of view, the endogenous contents of ABA and ABAGE were also higher in the tolerant provenance, as well as the accumulation of proteins involved in abiotic stress tolerance processes. In addition, evidence of two immunologically-related proteins to the maize RAB17 and RAB28 proteins is first reported in Eucalyptus, showing similarities between species. Our results show that E. globulus displays simultaneous adjustments for acquiring drought tolerance that are expressed at physiological, developmental and molecular levels.This work was economically supported by FICYT and ENCE — Spain.Peer reviewe

Confinement of iPP chains in the interior of SBA-15 mesostructure ascertained by gas transport properties in iPP-SBA-15 nanocomposites prepared by extrusion

Different nanocomposites based on isotactic polypropylene (iPP) and mesoporous SBA-15 silica have been prepared by melt extrusion as an attempt of incorporating iPP within the nanometric SBA-15 pores by the action of shear forces during processing. The observed inclusion of iPP chains in the SBA-15 leads to a change in the gas transport properties of the resultant iPP/SBA-15 membranes together with the improvement of their ultimate mechanical performance. Existence of confinement effects is observed, consequently, by the exhibited transport properties and is confirmed through real-time variable-temperature Small Angle X-ray Scattering (SAXS) experiments with synchrotron radiation. The former indicates that the mesostructure of silica is full, i.e., these particles essentially act as fillers. The latest has been proved by the presence of a discontinuity in the intensity of the (100) SBA-15 diffraction, which turn SAXS measurements at variable temperature into a valuable means to corroborate the development of iPP crystallites within SBA-15 channels. Moreover, SAXS profiles provide information about the most probable long spacing of chains located outside the SBA-15 nanospaces. On the other hand, changes in the β viscoelastic relaxation have been correlated to the influence of SBA-15 in the iPP amorphous regions. All the structural features have been crucial for the understanding the mechanical response shown by these nanocomposites. Mesoporous particles exert a reinforcing role and reduce the deformation capacity in the ultimate materials as their content is increased.This work was supported by the Agencia Estatal de Investigación (AEI, Spain) together with the European Regional Development Fund (FEDER, UE) [MAT2016-79869-C2-1-P]. Ms. R Barranco-García also thanks her pre-doctoral funding [BES-2014–070972] associated with the Ministerio de Economía y Competitividad (MINECO, Spain) [MAT2013-47972-C2-1-P] project. The synchrotron experiments were performed at beamline BL11-NCD at ALBA Synchrotron Light Facility with the collaboration of ALBA staff. Authors are grateful for the funding received to perform these measurements.Peer Reviewe

Influencia de las condiciones culturales en el crecimiento de diferentes hongos ectomicorricicos

Se estudió la capacidad de crecimiento de 12 especies de hongos ectomicorrícicos en cuatro medios de cultivo (MMN, MFM, BAF y MEPA) que difieren considerablemente en contenido mineral, fuentes de carbono y vitaminas. Los resultados obtenidos permiten determinar la existencia de diferencias significativas en el crecimiento de diferentes especies de hongos ectomicorrícicos en cultivo puro

Confinement of iPP crystallites within mesoporous SBA-15 channels in extruded iPP-SBA-15 nanocomposites studied by Small Angle X-ray scattering

The main objective of this research is the study of different nanocomposites based on isotactic polypropylene (iPP) and mesoporous SBA-15 silica prepared by melt extrusion, analyzing the possible effect of this filler on the polymorphic behavior of iPP and the eventual observation of confinement effects. Thus, simultaneous Small Angle X-ray Scattering/Wide Angle X-ray Diffraction (SAXS/WAXD) synchrotron experiments at variable temperature have been performed on several iPP nanocomposites with different contents of SBA-15 mesoporous particles. Real-time variable-temperature SAXS measurements turned out a very useful tool to analyze the confinement of iPP crystallites within SBA-15 channels, and also to determine the most probable long spacing of chains located outside the SBA-15 nanospaces. Importance of these structural features is assessed by changes in the mechanical response of the final materials, finding that the presence of mesoporous particles leads to a reinforcing effect and contribute to improve the final dimensional stabilityThe financial support from project MAT2016-79869-C2-1-P (AEI/ FEDER, UE) is greatly acknowledged. Ms. R Barranco-García also thanks her pre-doctoral funding (BES-2014-070972) associated with the MINECO (MAT2013-47972-C2-1-P) project. The synchrotron experiments were performed at beamline BL11-NCD at ALBA Synchrotron Light Facility with the collaboration of ALBA staff. Authors are grateful for the funding received to perform these measurements. Authors thank to Prof. V. Lorenzo his help in the indentation measurements.Peer reviewe

Comonomer Length Influence on the Structure and Mechanical Response of Metallocenic Polypropylenic Materials

The structure and properties have been comprehensively studied for metallocene copolymers of propylene-1-hexene (CiPH) and propylene-1-octadecene (CiPOD). The comonomer content constitutes the most important factor affecting both structure and properties in these CiPH and CiPOD copolymers, although the length of the comonomer is also very important. Thus, a considerable decrease in crystallinity and an easier obtainment of mesomorphic-like ordered entities are observed in the two kinds of copolymers as comonomer content increases. The variations in crystalline structure significantly influence the viscoelastic and mechanical behaviors of these CiPH and CiPOD copolymers. Consequently, the location and intensity of the different relaxation mechanisms as well as stiffness parameters (storage, Young’s moduli, and microhardness) and deformation mechanism are strongly dependent upon composition.The authors are grateful for the financial supports of Ministerio de Educacio´n y Ciencia (projects MAT2005- 00228 and MAT2007-65519-C02-01) and of CONICYT (project FONDAP 11980002)

A Truncated Form of IKKa Is Responsible for Specific Nuclear IKK Activity in Colorectal Cancer

Nuclear IKK alpha regulates gene transcription by phosphorylating specific substrates and has been linked to cancer progression and metastasis. However, the mechanistic connection between tumorigenesis and IKK alpha activity remains poorly understood. We have now analyzed 288 human colorectal cancer samples and found a significant association between the presence of nuclear IKK and malignancy. Importantly, the nucleus of tumor cells contains an active IKK alpha isoform with a predicted molecular weight of 45 kDa (p45-IKK alpha) that includes the kinase domain but lacks several regulatory regions. Active nuclear p45-IKK alpha forms a complex with nonactive IKK alpha and NEMO that mediates phosphorylation of SMRT and histone H3. Proteolytic cleavage of FL-IKK alpha into p45-IKK alpha is required for preventing the apoptosis of CRC cells in vitro and sustaining tumor growth in vivo. Our findings identify a potentially druggable target for treating patients with advance refractory CRC

A truncated form of IKKα is responsible for specific nuclear IKK activity in colorectal cancer

Nuclear IKKα regulates gene transcription by phosphorylating specific substrates and has been linked to cancer progression and metastasis. However, the mechanistic connection between tumorigenesis and IKKα activity remains poorly understood. We have now analyzed 288 human colorectal cancer samples and found a significant association between the presence of nuclear IKK and malignancy. Importantly, the nucleus of tumor cells contains an active IKKα isoform with a predicted molecular weight of 45 kDa (p45-IKKα) that includes the kinase domain but lacks several regulatory regions. Active nuclear p45-IKKα forms a complex with nonactive IKKα and NEMO that mediates phosphorylation of SMRT and histone H3. Proteolytic cleavage of FL-IKKα into p45-IKKα is required for preventing the apoptosis of CRC cells in vitro and sustaining tumor growth in vivo. Our findings identify a potentially druggable target for treating patients with advance refractory CRC.P.M. is a recipient of a FPU fellowship (AP2009-2892) and M.C.M. is funded by the ‘‘Sara Borrell’’ Program from MICIN (CD09/00421). This work was supported by Fondo de Investigaciones Sanitarias (PI07/0778 and PI10/01128), AGAUR (2009SGR23), Fondos Feder RD06/0020/0098 and RD09/0076/00036, and Xarxa de Bancs de tumors sponsored by Pla Director d’Oncologia de/nCatalunya (XBTC). M.W.M. was supported by funds from the NIH/NCI R01 CA10439