27 research outputs found

    Why is the CO2-CS2 non-ideality larger than in CO2-CCl4? A Raman scattering study

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    The dense phases of the CO2-CCl4 (I) and CO2-CS2 (II) mixtures have been studied by Raman spectroscopy. Mixture I is found almost ideal and II strongly non-ideal. At high CS2 concentration in II, the local structure of CS2 is preserved suggesting a nano-segregation of the liquid phase without demixing whereas in CO2 concentrated mixtures a diversity of species are present. Thermodynamical considerations together with spectroscopic results show that a subtle interplay between attractive and repulsive interactions leads to this non-ideal behaviour. The connection of these results with the liquid-liquid demixing reported for CO2-CS2 at lower temperature is discussed. (C) 2013 Elsevier B. V. All rights reserved

    DFT Study of the Reaction Mechanisms of Carbon Dioxide and its Isoelectronic Molecules CS2 and OCS Dissolved in Pyrrolidinium and Imidazolium Acetate Ionic Liquids

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    The reaction mechanisms of CO, and its isoelectronic molecules OCS and CS2 dissolved in N-butyl-N-methylpyrrolidinium acetate and in 1-butyl-3-methylimidazolium acetate were investigated by DFT calculations in \"gas phase\". The analysis of predicted multistep pathways allowed calculating energies of reaction and energy barriers of the processes. The major role played by the acetate anion in the degradation of the solutes CS2 and OCS as well as in the capture of OCS and CO, by the imidazolium ring is highlighted. In both ionic liquids, this anion governs the conversion of CS2 into OCS and of OCS into CO, through interatomic S-O exchanges between the anion and the solutes with formation of thioacetate anions. In imidazolium acetate, the selective capture of CS2 and OCS by the imidazolium ring competes with the S-O exchanges. From the calculated values of, the energy barriers a basicity scale of the anions is proposed. The C-13 NMR chemical shifts of the predicted adducts were calculated and agree well with the experimental observations. It is-argued that the scenario issued from the calculated, pathways is shown qualitatively to be independent from the functionals and basis set used, constitute a valuable tool in the understanding of chemical reactions taking place in liquid phase

    GGP Push to Web Pilot

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    This data was collected as part of the Generations and Gender Programme - Evaluate, Plan, Initiate Project (Grant Agreement No 739511). The pilot consisted of online and face to face survey interviews in order to evaluate the impact of mode and selection effects on data quality in the Generations and Gender Survey. Data was collected in Germany, Croatia and Portugal in 2018

    Critical role of OX40 signaling in the TCR-independent phase of human and murine thymic Treg generation

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    Regulatory T cells (Tregs) play a pivotal role in immune-tolerance, and loss of Treg function can lead to the development of autoimmunity. Natural Tregs generated in the thymus substantially contribute to the Treg pool in the periphery, where they suppress self-reactive effector T cells (Teff) responses. Recently, we showed that OX40L (TNFSF4) is able to drive selective proliferation of peripheral Tregs independent of canonical antigen presentation (CAP-independent) in the presence of low-dose IL-2. Therefore, we hypothesized that OX40 signaling might be integral to the TCR-independent phase of murine and human thymic Treg (tTreg) development. Development of tTregs is a two-step process: Strong T-cell receptor (TCR) signals in combination with co-signals from the TNFRSF members facilitate tTreg precursor selection, followed by a TCR-independent phase of tTreg development in which their maturation is driven by IL-2. Therefore, we investigated whether OX40 signaling could also play a critical role in the TCR-independent phase of tTreg development. OX40-/- mice had significantly reduced numbers of CD25-Foxp3low tTreg precursors and CD25+Foxp3+ mature tTregs, while OX40L treatment of WT mice induced significant proliferation of these cell subsets. Relative to tTeff cells, OX40 was expressed at higher levels in both murine and human tTreg precursors and mature tTregs. In ex vivo cultures, OX40L increased tTreg maturation and induced CAP-independent proliferation of both murine and human tTregs, which was mediated through the activation of AKT-mTOR signaling. These novel findings show an evolutionarily conserved role for OX40 signaling in tTreg development and proliferation, and might enable the development of novel strategies to increase Tregs and suppress autoimmunity
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