Tarragona, Spain
Tarragona, Spain

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Belmonte A.,Polytechnic University of Catalonia | Dabritz F.,Leibniz Institute of Polymer Research | Ramis X.,Polytechnic University of Catalonia | Serra A.,University RoviraiVirgili | And 3 more authors.
Journal of Polymer Science, Part B: Polymer Physics | Year: 2014

Hyperstar polymers (HSPs) with hyperbranched aromatic polyester core and arms consisting of block copolymers of poly(methyl methacrylate) and poly(hydroxyethyl methacrylate) have been used as polymeric modifiers in cycloaliphatic epoxy-anhydride formulations catalyzed with tertiary amines, with the purpose of enhancing the impact strength of the resulting materials without compromising other thermal and mechanical properties.> In this work, the effect of these polymeric modifiers on the curing kinetics, processing, thermal-mechanical properties and thermal stability has been studied using thermal analysis techniques such as DSC, TMA, DMA, and TGA. The morphology of the cured materials has been analyzed with SEM. The curing kinetics has been analyzed by isoconversional procedures and phenomenological kinetic models taking into account the vitrification during curing, and the degradation kinetics has been analyzed by means of isoconversional procedures, summarizing the results in a time-temperature-transformation (TTT) diagram. The results show that HSPs participate in the crosslinking process due to the presence of reactive groups, without compromising significantly their thermal-mechanical properties. The modified materials show a potential toughness enhancement produced by the formation of a nano-grained morphology. The TTT diagram is shown to be a useful tool for the optimization of the curing schedule in terms of curing completion and safe processing window, as well as for defining storage stability conditions. © 2014 Wiley Periodicals, Inc.

Orozco G.A.,French Institute of Petroleum | Orozco G.A.,University RoviraiVirgili | Nieto-Draghi C.,French Institute of Petroleum | Mackie A.D.,University RoviraiVirgili | Lachet V.,French Institute of Petroleum
Oil and Gas Science and Technology | Year: 2014

Using molecular simulation techniques such as Monte-Carlo (MC) and molecular dynamics (MD), we present several simulation results of thermodynamic and transport properties for primary, secondary and tertiary amines. These calculations are based on a recently proposed force field for amines that follows the Anisotropic United Atom approach (AUA). Different amine molecules have been studied, including n-ButylAmine, di-n-ButylAmine, tri-n-ButylAmine and 1,4-ButaneDiAmine for primary, secondary, tertiary and multi-functional amines respectively. For the transport properties, we have calculated the viscosity coefficients as a function of temperature using the isothermal-isobaric (NPT) ensemble. In the case of the pure components, we have investigated different thermodynamic properties using NVT Gibbs ensemble simulations such as liquid-vapor phase equilibrium diagrams, vaporization enthalpies, vapor pressures, normal boiling points, critical temperatures and critical densities. We have also calculated the excess enthalpies for water-n-ButylAmine and n-heptane-n-ButylAmine mixtures using Monte-Carlo simulations in the NPT ensemble. In addition, we present the calculation of liquid-vapor surface tensions of n-Butyl-Amine using a two-phase NVT simulation as well as the radial distribution functions. Finally, we have investigated the physical Henry constants of nitrous oxide (N2O) and nitrogen (N2) in an aqueous solutions of n-ButylAmine. In general, we found a good agreement between the available experimental information and our simulation results for all the studied properties, ratifying the predictive capability of the AUA force field for amines. © 2014, IFP Energies nouvelles.

Ribas-Latre A.,University RoviraiVirgili | Del Bas J.M.,Center Tecnologic Of Nutricio lut Ctns | Baselga-Escudero L.,University RoviraiVirgili | Casanova E.,University RoviraiVirgili | And 5 more authors.
Journal of Functional Foods | Year: 2015

Proanthocyanidins (PAs), a flavonoid sub-class, alter the expression of clock genes in the liver of lean and obese rats. The present study aimed to determine whether PAs could modulate the 24-hour rhythmicity of clock gene expression and to identify the molecular mechanism through which PAs could adjust the clock system in HepG2 cells. The 24-hour rhythmicity of core clock (CLOCK and BMAL1) and clock-controlled (CRY, PER2, RORα, REV-ERBα) gene expression indicated that a grape seed proanthocyanidin extract (GSPE) shifted the acrophase of nearly all of them, but BMAL1 appeared as the most sensitive gene to GSPE. Specifically, GSPE increased BMAL1 expression strongly and very quickly. This effect was also reproduced by melatonin. The overexpression of BMAL1 was melatonin receptor 1 (MT1) dependent for melatonin but MT1 independent for GSPE. However, GSPE increased the transcriptional activity of RORα, suggesting that this nuclear receptor could be responsible for the modulation of BMAL1 by GSPE. © 2015 Elsevier Ltd.

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