484 research outputs found

    Biodiesel via in situ wet microalgae biotransformation: Zwitter-type ionic liquid supported extraction and transesterification

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    The production of biodiesel derived from microalgae is among the most forthcoming technologies that provide an ecologic alternative to fossil fuels. Herein, a method was developed that enables the direct extraction and conversion of algal oil to biodiesel without prior isolation. The reaction occurs in aqueous media catalyzed by immobilized Candida antarctica lipase B (Novozyme 435). Zwitter-type ionic liquids were used as cocatalyst to improve the selectivity and reactivity of the enzyme. In a model reaction with sunflower oil, 64% biodiesel was obtained. Applying this method to a slurry of whole-cell Chlorella zof ingiensis in water resulted in 74.8% of lipid extraction, with 27.7% biotransformation products and up to 16% biodiesel. Factors that reduced the lipase activity with whole-cell algae were subsequently probed and discussed. This "in situ" method shows an improvement to existing methods, since it integrates the oil extraction and conversion into an one-pot procedure in aqueous conditions. The extraction is nondisruptive, and is a model for a greener algae to biodiesel process

    Coherent Contributions of Nuclear Mesons to Electroproduction and the HERMES Effect

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    We show that nuclear sigma, omega, and pi mesons can contribute coherently to enhance the electroproduction cross section on nuclei for longitudinal virtual photons at low Q^2 while depleting the cross section for transverse photons. We are able to describe recent HERMES inelastic lepton-nucleus scattering data at low Q^2 and small x using photon-meson and meson-nucleus couplings which are consistent with (but not determined by) existing constraints from meson decay widths, nuclear structure, deep inelastic scattering, and lepton pair production data. We find that while nuclear-coherent pion currents are not important for the present data, they could be observed at different kinematics. Our model for coherent meson electroproduction requires the assumption of mesonic currents and couplings which can be verified in separate experiments. The observation of nuclear-coherent mesons in the final state would verify our theory and allow the identification of a specific dynamical mechanism for higher-twist processes.Comment: Published version with improved shadowing parametrization. To be published in Physics Letters B 481, 245-252, May, 200

    Circles of support and personalisation: exploring the economic case

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    Circles of Support aim to enable people with learning disabilities (and others) to live full lives as part of their communities. As part of a wider study of the economic case for community capacity building conducted from 2012-2014, we conducted a mixed methods study of five Circles in North West England. Members of these Circles were supporting adults with moderate to profound learning disabilities and provided accounts of success in enabling the core member to live more independent lives with improved social care outcomes within cost envelopes that appeared to be less than more traditional types of support. The Circles also reported success in harnessing community resources to promote social inclusion and improve wellbeing. This very small scale study can only offer tentative evidence but does appear to justify more rigorous research into the potential of Circles to secure cost effective means of providing support to people with learning disabilities than the alternative, which in most cases would have been a long-term residential care placement

    Metal-organic frameworks invert molecular reactivity: Lewis acidic phosphonium zwitterions catalyze the Aldol-Tishchenko reaction.

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    The influence of metal–organic frameworks (MOFs) as additives is herein described for the reaction of n-alkyl aldehydes in the presence of methylvinylketone and triphenylphosphine. In the absence of a MOF, the expected Morita–Baylis–Hillman product, a β-hydroxy enone, is observed. In the presence of MOFs with UMCM-1 and MOF-5 topologies, the reaction is selective to Aldol-Tishchenko products, the 1 and 3 n-alkylesters of 2-alkyl-1,3-diols, which is unprecedented in organocatalysis. The (3-oxo-2-butenyl)triphenylphosphonium zwitterion, a commonly known nucleophile, is identified as the catalytic active species. This zwitterion favors nucleophilic character in solution, whereas once confined within the framework, it becomes an electrophile yielding Aldol-Tishchenko selectivity. Computational investigations reveal a structural change in the phosphonium moiety induced by the steric confinement of the framework that makes it accessible and an electrophile
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