1,263 research outputs found

    On infrastructure network design with agent-based modelling

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    We have developed an agent-based model to optimize green-field network design in an industrial area. We aim to capture some of the deep uncertainties surrounding infrastructure design by modelling it developing specific ant colony optimizations. Hence, we propose a variety of extensions to our existing work, first ideas on how to realize them and three cases to explicate our ideas. One case is the design of a CO2 pipeline network in Rotterdam industrial area. First simulation results have shown the relevance of the approach. Keywords-Infrastructure design, network planning, ant colony optimization, deep uncertainty, socio-technical systems

    An atom efficient synthesis of tamoxifen

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    The direct carbolithiation of diphenylacetylenes and their cross-coupling procedure taking advantage of the intermediate alkenyllithium reagents are presented. By employing our recently discovered highly active palladium nanoparticle based catalyst, we were able to couple an alkenyllithium reagent with a high (Z/E) selectivity (10 : 1) and good yield to give the breast cancer drug tamoxifen in just 2 steps from commercially available starting materials and with excellent atom economy and reaction mass efficiency

    One-pot, modular approach to functionalized ketones via nucleophilic addition/Buchwald-Hartwig amination strategy

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    A general one-pot procedure for the 1,2-addition of organolithium reagents to amides followed by the Buchwald-Hartwig amination with in situ released lithium amides is presented. In this work amides are used as masked ketones, revealed by the addition of organolithium reagents which generates a lithium amide, suitable for subsequent Buchwald-Hartwig coupling in the presence of a palladium catalyst. This methodology allows for rapid, efficient and atom economic synthesis of aminoarylketones in good yields

    Murahashi Cross‐Coupling at −78 °C:A One-Pot Procedure for Sequential C-C/C-C, C-C/C-N, and C-C/C-S Cross-Coupling of Bromo-Chloro-Arenes

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    The coupling of organolithium reagents, including strongly hindered examples, at cryogenic temperatures (as low as -78 degrees C) has been achieved with high-reactivity Pd-NHC catalysts. A temperature-dependent chemoselectivity trigger has been developed for the selective coupling of aryl bromides in the presence of chlorides. Building on this, a one-pot, sequential coupling strategy is presented for the rapid construction of advanced building blocks. Importantly, one-shot addition of alkyllithium compounds to Pd cross-coupling reactions has been achieved, eliminating the need for slow addition by syringe pump

    Palladium-Catalyzed C(sp<sup>3</sup>) C(sp<sup>2</sup>) Cross-Coupling of (Trimethylsilyl)methyllithium with (Hetero)Aryl Halides

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    The palladium-catalyzed direct cross-coupling of a range of organic chlorides and bromides with the bifunctional C(sp(3))-(trimethylsilyl)methyllithium reagent is reported. The use of Pd-PEPPSI-IPent as the catalyst allows for the preparation of structurally diverse and synthetically versatile benzyl- and allylsilanes in high yields under mild conditions (room temperature) with short reaction times.</p

    Synthesis of Core-Modified Third-Generation Light-Driven Molecular Motors

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    The synthesis and characterization of a series of light-driven third-generation molecular motors featuring various structural modifications at the central aromatic core are presented. We explore a number of substitution patterns, such as 1,2-dimethoxybenzene, naphthyl, 1,2-dichlorobenzene, 1,1 ':2',1 ''-terphenyl, 4,4 ''-dimethoxy-1,1':2',1 ''-terphenyl, and 1,2-dicarbome-thoxybenzene, considered essential for designing future responsive systems. In many cases, the synthetic routes for both synthetic intermediates and motors reported here are modular, allowing for their post-functionalization. The structural modifications introduced in the core of the motors result in improved solubility and a bathochromic shift of the absorption maxima. These features, in combination with a structural design that presents remote functionalization of the stator with respect to the fluorene rotors, make these novel motors particularly promising as light-responsive actuators in covalent and supramolecular materials

    Microbial catabolic activities are naturally selected by metabolic energy harvest rate

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    The fundamental trade-off between yield and rate of energy harvest per unit of substrate has been largely discussed as a main characteristic for microbial established cooperation or competition. In this study, this point is addressed by developing a generalized model that simulates competition between existing and not experimentally reported microbial catabolic activities defined only based on well-known biochemical pathways. No specific microbial physiological adaptations are considered, growth yield is calculated coupled to catabolism energetics and a common maximum biomass-specific catabolism rate (expressed as electron transfer rate) is assumed for all microbial groups. Under this approach, successful microbial metabolisms are predicted in line with experimental observations under the hypothesis of maximum energy harvest rate. Two microbial ecosystems, typically found in wastewater treatment plants, are simulated, namely: (i) the anaerobic fermentation of glucose and (ii) the oxidation and reduction of nitrogen under aerobic autotrophic (nitrification) and anoxic heterotrophic and autotrophic (denitrification) conditions. The experimentally observed cross feeding in glucose fermentation, through multiple intermediate fermentation pathways, towards ultimately methane and carbon dioxide is predicted. Analogously, two-stage nitrification (by ammonium and nitrite oxidizers) is predicted as prevailing over nitrification in one stage. Conversely, denitrification is predicted in one stage (by denitrifiers) as well as anammox (anaerobic ammonium oxidation). The model results suggest that these observations are a direct consequence of the different energy yields per electron transferred at the different steps of the pathways. Overall, our results theoretically support the hypothesis that successful microbial catabolic activities are selected by an overall maximum energy harvest rate
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